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14-102355June 22, 2014 AHBL Attn: Sean M. Comfort, PE Grene-Gasaway Architects, PLLC PO Box 4158 Federal Way, WA 98063 RE: Permit # 14-102355-00-CO TIR Hydrologic Analysis & Civil Plan Review Comments for Panther Lake Elementary School; 34424 First Avenue South Dear Mr. Comfort, PE The Public Works Department has completed the first review of the civil plans for the above project. The following comments must be addressed: Technical Information Report: 1.0 Project Overview, Page 1 Please indicate in this discussion the following information. • Redevelopment project proposed over 2,000 sf of new impervious, over 5,000 sf new impervious and over 7,000 sf land disturbing activity for proposed four portable buildings. • Flow control will be required because the peak flows from the 100 year storm not increase by more than 0.1cfs from pre -developed conditions. • This project proposes additional total 9,250 sf of new PGIS not subject to vehicular traffic and dispersion trenches for each building will be provided for required BMP's and separations between NVFS to mitigate the sheet flow runoff. 2.3 CORE REQUIREMENT #3: - FLOW CONTROL ■ At first proposed portable total impervious 2,210 square feet for new roof 1792 and sidewalks/ramps 418sf. • At second proposed portable total impervious 2,542 square feet for new roof 1792 and sidewalks/ramps 750sf. • At first proposed portable total impervious 2,392 square feet for new roof 1792 and sidewalks/ramps 600sf. ■ At first proposed portable total impervious 2,122 square feet for new roof 1792 and sidewalks/ramps 330sf. Please provide corrections and accurate basin description Page 2. 2.4 CORE REQUIREMENT #4: - CONVEYANCE SYSTEM New conveyance pipe systems shall be designed with sufficient capacity to convey and the 25-year peak flow, assuming developed conditions for onsite tributary areas and existing conditions. • New conveyance for roof downspouts has to be tideline connected to properly modeled and constructed for each gravel dispersion trench because splash rock pads are not allowed for over 1,400 sf impervious surface. Page 2. 2.5 CORE REQUIREMENT #5: - EROSION AND SEDIMENT CONTROL Provide new erosion and sediment controls plan to prevent the transport of sediment from the project site to downstream drainage facilities, water resources, and adjacent properties. • In addition, these measures, both temporary and permanent, shall be implemented consistent with the requirements for clearing and grading of four portable building pads with new elevations and amounts of cut and fill of approximately 9,250 sf. • Each of the following categories of ESC measures must be considered for application to the project site as detailed in the King County Erosion and Sediment Control (ESC) Standards: a. Demolition Limits b. Cover Measures c. Perimeter Protection d. Traffic Area Stabilization e. Sediment Retention f. Surface Water Collection g. Dewatering Control h. Dust Control i. Flow Control • The applicant will designate an ESC supervisor who shall be responsible for the performance, maintenance, and review of ESC measures and is a Certified Professional in ESC. • The turbidity test of surface and storm water discharges leaving the project site will not be greater than the benchmark value of 25 NTU set by the Washington State DOE. Page 2 2.6 CORE REQUIREMENT #6: - MAINTENANCE AND OPERATIONS Maintenance and operation of all dispersion trenches and drainage conveyance facilities is the responsibility of the applicant or property. • A copy of the Operation and Maintenance Manual will be submitted as part Of the permit application for privately maintained flow control BMPs must be maintained. 5.0 CONVEYANCE SYSTEM ANALYSIS Page 5. Please update land cover areas for all proposed development area sub -basins of all four new portable buildings impervious areas, roofs, sidewalks, ramps new landscape and trenches dispersion including NVFS and separation areas of total approximately 9,250 sf. 6.0 SPECIAL REPORTS AND STUDIES Page 5 ■ Wetland Delineation Report is needed for Category and offset zones requirements 8.0 CSWPPP ANALYSIS AND DESIGN Page 5 • Report is needed for TESC requirements. • Please provide TESC Plan updates per PWD DS comments and Core Requirement #5 and Site Plan Drawing with all erosion control standard detail drawings requirements and sediment trapping. 10.0 OPERATION AND MAINYNANCE MANUAL Page 5 ■ Wetland Delineation Report is needed for Category and offset zones requirements CIVIL PLANS: General: 1. At least one sheet must show boundary survey information stamped by a professional land surveyor licensed in the State of Washington. 2. Distinguish between existing and proposed facilities. Example Drawings Site Data shows Proposed Parking 78 Stalls. Need to correct if this is Existing Parking, or if New show layout and location with SWMF. 3. Show all site locations of proposed portable and future portables on all civil sheets with proposed dispersion trenches adequately sized and located with Min. 100-ft long NVFS and Min. 50' separations b/w existing and proposed SWMF. 4. Please provide complete peak flow calculations of KCRTS and include all pre -developed drainage area and development drainage area sub -basins maps new sheets with flow paths. Include all new and replaced impervious areas, and new landscape area of total approximately estimated 9,250 sf (0.21 ac 5. Include City of Federal Way standard details as applicable. 6. Add the City's standard approval block to each sheet. Cover Sheet C1.0 7. Show all site locations of proposed portable and future portables on all civil sheets with proposed dispersion trenches. 8. Show proposed portable building FFE and Pad Elevation, and SF Area. 9. Label Wetland Area, and all new and proposed facility. 10. Include in Site Data Total Proposed Floors Area for all four portables and Total Existing and Proposed Gross Floors Areas of all floors. 11. Label Existing SWMF trench and do not disturb any underground facilities. 12. Address all Questions and Review Comments as marked. T.E.S.C. And Clearing Plan C1.1 13. Show all site locations of proposed portable and future portables on all civil sheets with proposed dispersion trenches adequately modeled and located. 14. Show proposed portable building FFE and Pad Elevation, and SF Area. 15. Label Wetland Area Limit, and all new and proposed facilities. 16. Include in Site Data Total Proposed Floors Area for all four portables and Total Existing and Proposed Gross Floors Areas of all floors. 17. Label Existing SWMF trench and do not disturb any underground facilities. 18. Address all Questions and Review Comments as marked 19. Show Grading Limit for proposed portable foundation pad and cut and fill amounts per Existing Geotechnical Report requirements. 20. Install and extend Silt Fence approximately 350 linier ft. along perimeter to intercept all sediment flow path from construction activity. Civil Drainage Site Plan and Gradincl Plan C1.2 21. Show proposed portable new downspout tideline convenience system location to dispersion trench. 22. Show proposed portable building HE and Pad Elevation, and cross sections A & B showing required cut and fill and slopes. 23. Label Wetland Area Limit, and all new and proposed facilities. 24. Layout location of proposed dispersion trench size min 10' or more was required and show 50 ft. Separation b/w SWMF and flow path Segment min.100 ft. (NVFS) per Figure C2.1.C. 25. Label Existing SWMF trench and do not disturb any underground facilities. 26. Address all Questions and Review Comments as marked up 27. Provide Grading Limit for proposed portable foundation pad cross sections with proposed paved sidewalks. NOTES AND DETAILS C1.3 28. Show CFW Standard Trench Restoration Detail Drawing. No. 3-28 for reference. 29. Show dispersion trench details per Figure C2.1.C, or C.2.1.D. 30. Address all Questions and Review Comments as marked up. SECTION C.2 FLOW CONTROL BMPs FIGURE C.2.1.0 10-FOOT DISPERSION TRENCH CROSS-SECTION AND ROOF APPLICATION v o o C)° Y level outlet as o�O4 4° °° o 4 d o ° 4 ° Q ° 4 0 � ° ° Max 20% slope ° ° ° a v v v C,Q °° ❑ Qv ° ° �a CA 0 v v❑ °° q❑° o r °° A°a cp❑ 5" min ° a q� o a�Q° ° °o° a Q ❑r, _-Oa 4" perf pipe + ❑ 7 Q 170A 090 o tla4o°q vvLod0L1 18" min ° va a ❑ °0a° a all ° ° o❑ ° a 4❑d c°4 �" 1 1/2" - 3/4" washed rock C ❑� qq°4❑ Q a °a ° p °aV 7 ° Q 10 0° °❑ o e a° o L- 24" min �►I TRENCH X-SECTION NTS Edge of undisturbed native vegetation Small catch basin or yard drain ,f rh 51,400 sq ft for a 100-ft NVFS s2,800 sq ft for a 200-ft NVFS Typp I CB 55,000 sq ft for a 100-ft NVFS 510,00U sq ft for a 200•ft NVFS PLAN VIEW OF ROOF NTS Max 15% slope Min..1-00-ft €ong NVFS �i 50-fodt separation b/t rry flowpdth segments 101,foot-long dispersion trench r" Wive .Ve9ela O- F€bwpatli Segment {NVFS} - lob feet minimum'. �. iY w <15% Slope 50-foot-long dispersion trench with notch board See Figure C.2.1.D 1/9/2009 2009 Surface Water Design Manual — Appendix C C-34 SECTION C.2 FLOW CONTROL BMPs FIGURE C.2.4.11 TYPICAL GRAVEL -FILLED DISPERSION TRENCH FOR BASIC DISPERSION 0° v°o o C° 9 level outlet d° 1 4 d oC) v d p d d ° ~� ° a Qv� ° q p° ° p n av v v v p p ° q p a 1 °1 a p v vp ° vq 6" d, e;�e .o u min otrd oda 94 a a„ c a 4" perf pipe VV 4q°� °ed0,8 40°d gE1a❑ 18" min Q° n ❑ °00 a o° ° ❑ , ap,A 1 1/2' - 3/4' washed rock q na °❑ p�aQ ❑ ate❑ ° a a p❑ ao a 16 60 nan0a°�Q4C, ❑A q G° ° ° 0 a 6 a 0 L 24" min TRENCH X-SECTION NTS slope small catch basin or yard drain ' 25-Foot Vegetated . C� Flowpath Segment <_700 sq. ft. Simple 10-foot trench Type I CB >700 sq. ft. 25-Foot Vegetated Flowpath Segment N-r.�-� Y. Maximum 50-foot trench w/notch board (see Figure C.2.1.D, p. C-32) PLAN VIEW OF ROOF NTS 1/9/2009 2009 Surface Water Design Manual — Appendix C C-56 C.2.1 FULL DISPERSION FIGURE C.2.1.1) 50-FOOT DISPERSION TRENCH WITH NOTCHED BOARD notched grade board _ 2"x 2" notches 18" O.C. A 0 uO pipe O.D. 1 1-0 1'-0 min min end cap or plug v❑°a clean out wye from pipe o n c°a4 4" or 6" perforated pipe laid flat/k 0 0° a 0° k❑ q o v _.. type I CB w/solid cover (locking) ti ❑ f ° influent pipe (max design o a.flow 5 0.5 CFS per trench) oo v° clean out wye from pipe p q ra 9l - a � PLAN NTS galvanized bolts 1'-0 mm �a � ' 2" x12" t pressure treated grade board N 4" x 4' support post filter fabric Ape O.D. 1'-0 mine T04" 6" perforated laid flat n (<— 5% fines) - 3/4 " washed rock SECTION A -A NTS flow to second dispersal trench if necessary 3 :over f flow to other branching CB's as necessary 18" O.C. 2" 1 i 2" grade board notches 2" NOTES: 1. This trench shall be constructed so as to prevent point discharge and/or erosion. 2. Trenches may be placed no closer than 50 feet to one another. (100 feet along flowline) 3. Trench and grade board must be level. Align to follow contours of site. 4. Support post spacing as required by soil conditions to ensure grade board remains level. 2009 Surface Water Design Manual — Appendix C 1/9/2009 C-35 §1k 41W aMu o0 %3a774 » oaoC) E� 2 7= ;D � j $-a\� f�2/ƒ m ® �\2E ®0¥�m CDa e CDR CDCDG e® 7 e ;Ekk®3 / x§\ƒ_/\ t \/ co �Cn 0 �\ to\ 2 k M ) \ 3 E ƒ 0 & N CD k 000\ { \ _ §0000\ « E %q7@ »� @ $ 7a$$ $� I � a §0000§ > a §0000} / \ � § 4cn �0000g & ESQ& a $¥a$ 0)%_ §0000% §0000§ \ t d2m co E L"w� w ƒ wu_ Sty cc m 2 # % Ili _# 0 m| [ ic �7 $w 0 r. G w § § 0002 m § ESR/ z� O _■ ooCD / z ooo/ \ ■/; zz m>m �2# W W k/k \Cc N3 %ad/2» 02 o#oo0 m E" S ti �7 E j $-0/a f� 1p \k\ m \gm 3 o - _ ; r m » @ _ ° G e / e ;q\ -2 - \ 24 kI/w o\\ f to °e n*U? n tƒ & 0f e / 22 \ § CD � �e CD a) , ® w �2 $ 0 $ CD\� = cook k 7 = ¥ \ NJ m f §0000\ � @ %5Eq ®CD W a $f$$ +� I � 2 §0000§ 2 \ C. o 000\ / .�00004 § E ) > 0 \ 14-(0365 RESUBMITTED JUL 21 2014 CITY OF FEDERAL WAY CDS July 21, 2014 Ms. Ann Dower Senior Engineering Plans Reviewer City of Federal Way 33325 8th Avenue South Federal Way, WA 98003-6325 Project: FWPS Panther Lake Elementary School Portables, Our File No. 2140205.10 Subject: Response to Comments dated July 10, 2014 Folder #14-102355-00-CO: 3442 1st Avenue South; Public Works First Review Dear Ms. Dower: This letter is in response to your comments dated July 10, 2014, regarding the above referenced project. The comments below are in the same format as was provided in your comment letter and are typed verbatim. Our responses are shown in bold after each comment. Technical Information Report Project -Overview 1. Please discuss the intention to add more portables, timing, and the impervious area that would eventually be added at full build -out. Discuss the ramifications of this in light of the square footage thresholds established by both the 2009 KCSWDM for detention and the Federal Way Revised Code Section 19.30.120 for nonconforming water quality. Response: An additional paragraph has been added to Section 1.0 (Project Overview) of the Technical Information Report documenting 2009 KCSWDM requirements and Federal Way Revised Code requirements for future improvements. 1.8 Water Quality 2. FWRC Section 19.20,120 requirements should be discussed here. Response: An additional paragraph has been added to Section 2.8 (Core Requirement #8 — Water Quality) of the Technical Information Report documenting Federal Way Revised Code requirements for water quality improvements to existing surfaces. Civil Engineers Structural Engineers Landscape Architects Community Planners Land Surveyors Neighbors TAC0MA 2215 North 30th Street Suite 300 Tacoma, WA 98403-3350 253.383,2422 TEL 253.383.2572 EAR www.ahbl.com Ms. Ann Dower July 21, 2014 2140205.10 !i Page 2 of 3`_; 4.0 Flow Control and Water Quality Facility Analysis and Design Distinguish between the single portable proposed at this point, and the project as a whole with additional portables. Indicate at what point the project will be required to meet current detention and water quality standards, or explain how' it already meets current standards. Response: Additional paragraphs have been added to Section 4.0 (Flow Control and Water Quality Facility Analysis and Design) of the Technical Information Report documenting 2009 KCSWDM requirements and Federal Way Revised Code for future redevelopment. Civil Plans 4. Provide City approval block with project number on each sheet. Response: The City approval block and Project No. 14-102355-00 have been added to each of the plan sheets. 5. Provide City of Federal Way Standard Plan Notes and Erosion/Sedimentation Control Notes, available at www.Cityoffederalway.com in the Development Standards. Response: City of Federal Way Standard Erosion/Sedimentation Control Notes and Construction Sequence have been added to Sheet C1.1 (TESC and Demolition Plan). City of Federal Way General Notes and Drainage Notes have been added to Sheet C1.2 (Civil Site Plan). Per the instructions provided on the City of Federal Way Standard Plan Notes, notes which in no way apply to the project have been omitted and remaining notes have not been renumbered. Street lighting notes have been omitted in their entirety, as there is no street lighting proposed. Sheet C1.0 6. Portions of the Site Data do not apply to this project. Please remove or strike through. Response: No plan change is being made related to Comment 6, as discussed in a phone conversation between Ann Dower (City of Federal Way), Bill Fierst (AHBL), and Adam Braun (AHBL) on July 17, 2014. Sheet CIA 7. Call out that the existing dispersion trenches are not to be disturbed, and provide a minimum 5' clearance between the silt fence and the dispersion trench. Response: Annotation has been added to both Sheets C1.1 and C1.2 to protect the existing trench from damage and sedimentation. The location of silt fence has been revised to provide a minimum of 5 feet between the silt fence and existing trench. A dimension has been added to show 5 feet between the silt fence and dispersion trench. 7RIHJB L. Ms. Ann Dower July 21, 2014 ■1'■ 2140205.10 �, Page 3of3 � IN ■� Sheet C1.2 8. The dimensions on this sheet are provided at 1:10 and do not match the 1:20 scale provided. Resolve. Response: Scale issues have been resolved on Sheet C1.2. 9. Call out minimum separation between the proposed rock pads and the existing infiltration trench and dispersion trench. Response: Dimensions have been added to Sheet C1.2 showing the distance between the rock pads and the existing trench. 10. Extend northerly trench so that water is not directed across the existing infiltration trench to the south. Response: As discussed in a phone conversation between Ann Dower (City of Federal Way), Bill Fierst (AHBL), and Adam Braun (AHBL) on July 17, 2014, the middle downspout outfall that previously directed water across the existing trench has been removed from the plans. 11. Provide pad elevation for the portable classroom. Response: The portable classroom will not be constructed on a level pad. The construction will take place primarily over existing grades with slight grading in a few locations to provide level walkways. The grading for the walkways is shown on Sheet C1.2. 12. Show any proposed grading. Response: Grading is shown on Sheet C1.2, including both existing and proposed contours, proposed spot elevations, and rim elevations at drainage structures. As instructed in your comment letter, we are providing one set of plans and one Technical Information Report for further review. If you have any questions, please call me at (253) 383-2422. Sincerely, 7 II Adam C. Braun, PE Project Engineer ACB/Isk Bill Fierst, AHBL Q:\2014\2140205\WORDPROC\Letters\20140721 Ur (Resp-FedWay 1stRev) 2140205.10.dooc UP 102 RESUBM . 1: JUL11 11141Y CjTy OF FEDERAL CDS .Lj 0 V FROM DAMAGE 11 G OIL V - 10 7m 2.215 North 30th Street, WS.R. 300, ---..-9-3 253.13.2422 TEL 253 363.2572 FAX x PERMIT RE-SUBMCTTAi. Q TO CITY OF FEDERAL WAY (0725/2014) PERMIT RE -SUBMITTAL #1 To CITY OF FEDERAL WAY (071MV %4) PANTHER LAKE ELEMENTARY SCHOOL PORTABLES EX-1 T.E.S.C. AND DEMOLITION PLAN EROSION / SEDIMENTATION CONTROL NOTES 1 APPROVAL OP THIS EROSiONmE91MENTATION CONTROL (ESC) PLAN DOES NOT CONSTITUTE AN APPROVAL OF PERMANENT ROAD OR DRAINAGE DESIGN O.E. SIZE AND LDCATION OF ROADS, PIPES, RESTRICTORS, CHANNELS. RETENTION FACILITIES, UTILITI ES, ETC.). 2 THE IMPLEMENTATION OF THESE ESC PLANS AND THE CONSTRUCTION, MAINTENANCE, REPLACEMENT, AND UPGRADING OF THESE ESC FACILITIES IS THE RESPONSIBILITY OF THE APPLICANT/CONTRACTOR UNTIL ALL CONSTRUCTION IS APPROVED. 3. THE BOUNDARIES OF THE CLEARING LIMITS SHOWN ON THIS PLAN SHALL BE CLEARLY FLAGGED IN THE FIELD PRIOR TO CONSTRUCTION, DURING THE CONSTRUCTION PERIOD, NO DISTURBANCE BEYOND THE FLAGGED CLEARING LIMITS -SHALL BE PERMITTED. THE FLAGGING SHALL BE MAINTAINED BY THE APPLICANTICONTRACTOR FOR THE DURATION OF CONSTRUCTION. 4. STABILIZED CONSTRUCTION ENTRANCES AND WASH PADS SHALL BE INSTALLEDATTHE BEGINNING OF CONSTRUCTION AND MAINTAINED FOR THE DURATION OF THE PROJECT- ADDITIONAL MEASURES MAYBE REQUIRED TO ENSURE THAT ALL PAVED AREAS ARE KEPT CLEAN AND TRACKING IN THE ROADWAY DOES NOT OCCUR FOR THE DURATION OF THE PROJECT 5. THE ESC FACILITIES SHOWN ON THIS PLAN MUST BE CONSTRUCTED PRIOR TO OR IN CONJUNCTION WITH ALL CLEARING AND GRADING ACTIVITIES, AND IN SUCH A MANNER AS TO ENSURE THAT SEDIMENT LADEN WATER DOES NOT ENTERTHE DRAINAGE SYSTEM, ADJACENT PROPERTIES, OR VIOLATE APPLICABLE WATER STANDARDS- 6 THE ESC FACILITIES SHOWN ON THIS PLAN ARE THE MINIMUM REQUIREMENTS FOR ANTICIPATED SITE CONDITIONS. DURING THE CONSTRUCTION PERIOD. THESE ESC FACILITIES SHALL BE UPGRADED ANDfOR REVISED AS NEEDED FOR UNEXPECTED STORM EVENTS, AND MODIFIEDTO ACCOUNT FOR CHANGING SITE CONDITIONS jE.G-. ADDITIONAL COVER MEASURES, RELOCATION OF DITCHES AND SILT FENCES, PERIMETER PROTECTION, ETC.). 7. THE ESC FACILITIES SHALL BE INSPECTED DAILY BY THE APPLICANT/CONTRACTOR AND MAINTAINED AS NECESSARY TO ENSURE THEIR CONTINUED PROPER FUNCTIONING, B. ANY AREAS OF EXPOSED SOILS, INCLUDING ROADWAY EMBANKMENTS, THAT WILL NOT BE DISTURBED FOR SEVEN (7) DAYS DURING THE DRY SEASON OR TWO (2) DAYS DURING THE VLE-T SEASON, SHALL BE IMMEDIATELY STABILIZED WITH THE APPROVED ESC METHODS (I.E., SEEDING, MULCHING, NETTING, EROSION BLANKETS, ETC.). 9. ANY AREA NEEDING ESC MEASURES, NOT REQUIRING IMMEDIATE ATTENTION, SHALL BE ADDRESSED WITHIN SEVEN (7) DAYS. 10. THE ESC FACILITIES ON INACTIVE SITES SHALL BE INSPECTED AND MAINTAINED A MINIMUM OF ONCE A MONTH OR WITHIN 24 HOURS FOLLOWING A STORM EVENT. 11. AT NO TIME SHALL MORE THAN 1 FOOT OF SEDIMENTBE ALLOWED TO ACCUMULATE WITFIIN A CATCH BASIN. ALL CATCH BASINS AND CONVEYANCE LINES SHALL BE CLEANED PRIORTO PAVING. THE CLEANING OPERATION SHALL NOT FLUSH SEDIMENT -LADEN WATER INTO THE DOWNSTREAM SYSTEM, 12. ANY PERMANENT RETENTIONIDETENTION FACILITY USED AS A TEMPORARY SETTLING BASIN SHALL BE MODIFIED WITH THE NECESSARY EROSION CONTROL MEASURES AND SHALL PROVIDE ADEQUATE STORAGE CAPACITY, IF THE PERMANENT FACILITY IS TO FUNCTION ULTIMATELY AS AN INFILTRATION SYSTEM, THE FACILITY SHALL NOT BE USED AS ATEMPORARY SETTLING BASIN. NO UNDERGROUND DETENTION TANKS OR VAULTS SHALL BE USED AS A TEMPORARY SETTING BASIN. 13. COVER MEASURES WILL BE APPLIED IN CONFORMANCE WITH APPENDIX D OF THE KCSWDM- 14. MANAGEMENT PRACTICES PROVIDING SIGNIFICANT TREE PROTECTION (PER FWRC) SHALL BE PROVIDED ON THE ESC PLANS. 15. WET SEASON SPECIAL PROVISIONS, AS DESCRIBED IN SECTION 05.2 OF APPENDIX D. KCSWOM ARE 1N EFFECT OCTOBER 1 THROUGH APRIL 30. PRIOR TO THE BEGINNING OF THE WET SEASON. ALL DISTURBED AREAS SHALL BE REVIEWED TO IDENTIFY WHICH ONES CAN BE SEEDER IN PREPARATION FOR WINTER RAIN& DISTURBED AREAS SHAILL BE SEEDED WITHIN ONE WEEK OF THE BEGINNING OF THE WET SEASON. %R CONSTRUCTION SEQUENCE BEFORE ANY CONSTRUCTION OR DEVELOPMENT ACTIVITY, A PRECONSTRUCTION MEETING MUST BE HELD BETWEEN THE CITY OF FEDERAL WAY, THE APPLICANT AND APPLICANTS CONSTRUCTION REPRESENTATIVE. FLAG CLEARING LIMITS. INSTALL FILTER FABRIC FENCE AS INDICATED ON PLAN. INSTALL OFFSITE CATCH BASIN PROTECTION, CLEAR AND GRUB AREAS OF THE SITE TO BE ROUGH GRADED OR FILLED. INSTALL INTERCEPTOR SWALES/BERMS AND CHECK DAMS. ROUGH GRADE SITE AND INSTALL STORM CONVEYANCE SYSTEM AND RETENTIONIDETENTION FACIUTIES, PROVIDE INLET PROTECTION WHERE INDICATED, INSTALL REMAINING UTILITIES AND BUILDING. FINISH GRADESITE AND CONSTRUCT ASPHALT PARKING AREAS, ACCESS DRIVES, SIDEWALKS, CURBS AND GUTTERS. COMPLETE SITE STABILIZATION IN ACCORDANCE WITH LANDSCAPE PLANS. CLEAN STORM DRAINAGE SYSTEM, ON AND OFF SITE, OF ALL SEDIMENT AND DEBRIS. REMOVE TEMPORARY EROSION CONTROL FACILITIES WHEN SITE IS COMPLETELY STABILIZED. PERMIT RE -SUBMITTAL Ili TO CITY OF ® FEDERAL WAY (01121M 14) 2215North 30hStnsat, PANTHER LAKE ELEMENTARY SCHOOL Suile 300, S Tacoma, WA11-3 PORTABLES EX-2 Q253383.2422 TEL T.E.S.C. AND ` C 253.3B32572FAX DEMOLITION PLAN MEET Jl I I j t: l 1 �� �' f 5 0 F L 011, MEANO Lfr AlMm 266.86 1 E= 2M, 9_7 IE-266.w III le--256.53 92 MR� ;laiii-P6. LITE 74 _W 264,24• LEM OPE zo ; GRADES A , RIM= 263.68 0., 'ESSARY TO IE=M 53 0 3 LF 2", IE=261 5 r CPEP` If 264.27 LF W HDPE 17.67% zw*: us N I 1CV585.54 IJ N.1 10584.97 E 1268441,37 CENTER PT. N 116545.55 Ell, 04- ' I 262.74* CENTER PT. EJITIER PT' N110528, 08 Ejg68jq222 E 12603B9.1288.60 f 3 LF CLemour RIM= 26037 IE=258.37 (8") GRAPHIC SCAIX 5 10 20 FEET 2215 North 30th Street Suite 300, Te—e. WA 98403 O W 0 0 253 383.2422 TEL 253.383.2572 FAX FEr= 266.70;' —CENTER fly .�, N I zimil *E 126"12 , 00 N `I111052099--N � 1118 , 177L F?' HDPE @ 6.36% N 110521.55.' E 1268412.09 CLEAKOUT— -3 LF B"HDPE RIM= 258.3j.. %K IE=256.59 (Er) SE--256.48— IE=256.59,.(B') IE=256,59 (8') L GRADING NOTES — C 1. SPOT ELEVATIONS WITH AN -BESIDE THEM ARE I _ �.0 DESIGN ELEVATIONS BY OTAK THE CONTRACTOR SHALL -HALL FIELD VERIFY ALL GRADES. CONTACTTHE ENGINEER IF DISCREPANCIES ARE FOUND. PROTECT EXISTING TRENCH FROM DAMAGE OR SEDIMENTATION T IMTATFION It 8 4' 16 B' -n4 MtN. 50' FLOW PATH PERMIT RE -SUBMITTAL 02 TO CITY OF FEDERAL WAY (07M f2014) PERMIT RE -SUBMITTAL 01 To CITY OF FEDERAL WAY (07JOB0014) PANTHER LAKE ELEMENTARY SCHOOL PORTABLES CIVIL SITE PLAN EX-3 �AHBL- GRAPH BCAIE 0 9 10 20 FM 1" 10 I = »� Lw Iva On. mmom CITY OF FEDERAL WAY GENERAL NOTES 1 ALL CONSTRUCTION SHALL BE IN ACCORDANCE 10. VERTICAL DATUM SHALL BE KCAS OR NGVD-29. WITH THE FEDERAL WAY REVISED CODE (FWRC), 11.GROUNDWATER SYSTEM CONSTRUCTION SHALL APPLICABLE ORDINANCES, AND THE CITY BE WITHIN A RIGHT-OF-WAY OR APPROPRIATE COUNCIL CONDITIONS OF PROJECT APPROVAL. DRAINAGE EASEMENTS, BUT NOT UNDERNEATH THESE DOCUMENTS ARE SUPPLEMENTED BY THE THE ROADWAY SECTION, ALL GROUNDWATER STANDARD SPECIFICATIONS FOR ROAD, BRIDGE, SYSTEMS MUST BE CONSTRUCTED IN AND MUNICIPAL CONSTRUCTION (WSDOT/APWA), ACCORDANCE WITH THE WSDOT/AP WA THE KING COUNTY ROAD STANDARDS (KCRS), STANDARD SPECIFICATIONS. AND THE KING COUNTY SURFACE WATER DESIGN 12. ALL UTILITY TRENCHES IN THE RIGHT-OF-WAY MANUAL (KCSWDM). IT SHALL BE THE SOLE SHALL BE BACKFILLED 5/8" CRUSHED ROCK AND RESPONSIBILITY OF THE APPLICANT AND THE COMPACTED TO 95% DENSITY. WHEN TRENCH PROFESSIONAL ENGINEER TO CORRECT ANY WIDTH IS 18 INCHES OR LESS, AND IS WITHIN THE ERROR, OMISSION, OR VARIATION FROM THE TRAVELED WAY, TRENCH WILL BE BACKFILLED ABOVE REQUIREMENTS FOUND IN THESE PLANS- WITH CONTROL DENSITY FILL (SELF -COMPACTED ALL CORRECTIONS SHALL BE AT NO ADDITIONAL FLOWABLE FILL) AS DEFINED BY WASHINGTON COST OR LIABILITY TO THE CITY OF FEDERAL AGGREGATES AND CONCRETE ASSOCIATION. WAY, THE AGGREGATE WILL BE 318-INCH MINUS. 2, THE DESIGN ELEMENTS WITHIN THESE PLANS 13. ALL ROADWAY SUBGRADE SHALL BE BACKFILLED HAVE BEEN REVIEWED ACCORDING TO THE AND COMPACTED TO 95% DENSITY IN FEDERAL WAY ENGINEERING REVIEW ACCORDANCE WITH WSDOT 2-06,3, CHECKLIST. SOME ELEMENTS MAY HAVE BEEN 15.THE CONTRACTOR SHALL BE RESPONSIBLE FOR OVERLOOKED OR MISSED BY THE CITY PROVIDING ADEQUATE SAFEGUARDS, SAFETY ENGINEERING PLAN REVIEWER. ANY VARIANCE DEVICES, PROTECTIVE EQUIPMENT, FLAGGERS, FROM ADOPTED STANDARDS IS NOT ALLOWED AND ANY OTHER NEEDED ACTIONS TO PROTECT UNLESS SPECIFICALLY APPROVED BY THE CITY LIFE, HEALTH, AND SAFETY OF THE PUBLIC, AND OF FEDERAL WAY, PRIOR TO CONSTRUCTION. TO PROTECT PROPERTY IN CONNECTION WITH 3, APPROVAL OF THIS ROAD, GRADING, AND THE PERFORMANCE OF WORK COVERED BY THE DRAINAGE PLAN DOES NOT CONSTITUTE AN CONTRACTOR. ANY WORK WITHIN THE TRAVELED APPROVAL OF ANY OTHER CONSTRUCTION (I,E, RIGHT-OF-WAY THAT MAY INTERRUPT NORMAL DOMESTIC WATER CONVEYANCE, SEWER TRAFFIC FLOW SHALL REQUIRE AT LEAST ONE CONVEYANCE, GAS, ELECTRICITY, ETC.) FLAGGER FOR EACH LANE OF TRAFFIC 4- BEFORE ANY CONSTRUCTION OR DEVELOPMENT AFFECTED. ALL SECTIONS OF THE WSDOT ACTIVITY, A PRECONSTRUCTION MEETING MUST STANDARD SPECIFICATIONS 1-07.23 -TRAFFIC BE HELD BETWEEN THE CITY OF FEDERAL WAY, CONTROL, SHALL APPLY. THE APPLICANT, AND THE APPLICANTS 16, CONTRACTOR SHALL PROVIDE AND INSTALL ALL CONSTRUCTION REPRESENTATIVE. REGULATORY AND WARNING SIGNS PER THE 5. A SIGNED COPY OF THESE APPROVED PLANS LATEST EDITION OF MANUAL ON UNIFORM MUST BE ON THE JOB SITE WHENEVER TRAFFIC CONTROL DEVICES (MUTCD), CONSTRUCTION IS IN PROGRESS. 17. ALL UTILITIES SHALL BE ADJUSTED TO FINAL 6. CONSTRUCTION NOISE AND ACTIVITY (ON GRADE AFTER PAVING ASPHALT WEARING PRIVATE PROPERTY) SHALL BE LIMITED AS PER COURSE- FWRC (SECTION 19,105.040); NORMALLY THIS IS 7:00 A.M. TO 8:00 P.M., MONDAY THROUGH FRIDAY, AND 9:00 A.M. TO 8:00 PM. ON SATURDAYS- DRAINAGE NOTES 1. PROOF OF LIABILITY INSURANCE SHALL BE 7. ALL DRIVEWAY CULVERTS LOCATED WITHIN THE SUBMITTED TO THE CITY PRIOR TO, OR AT, THE RIGHT-OF-WAY SHALL BE OF SUFFICIENT LENGTH PRECONSTRUCTION MEETING. TO PROVIDE A MINIMUM 3:1 SLOPE FROM THE 2. ALL PIPE AND APPURTENANCES SHALL BE LAID EDGE OF THE DRIVEWAY TO THE BOTTOM OF ON A PROPERLY PREPARED FOUNDATION IN THE DITCH. CULVERTS SHALL HAVE BEVELED ACCORDANCE WITH WSDOT SPECIFICATIONS. END SECTIONS TO MATCH THE SIDE SLOPES. THIS SHALL INCLUDE LEVELING AND 8. ROCK FOR EROSION PROTECTION OF DITCHES, COMPACTING THE TRENCH BOTTOM, THE TOP OF CHANNELS AND SWALES, WHERE REQUIRED, FOUNDATION MATERIAL, AND REQUIRED PIPE MUST BE OF SOUND QUARRY ROCK, PLACED TO BEDDING, TO A UNIFORM GRADE SO THAT THE A DEPTH OF ONE FOOT AND MUST MEETTHE ENTIRE PIPE IS SUPPORTED BY A UNIFORMLY FOLLOWING SPECIFICATIONS: 4"-8" DENSE UNYIELDING BASE. ROCK/40%-70% PASSING; 2"-4" ROCK/30%-00% 6, ALL DRAINAGE STRUCTURES, SUCH AS CATCH PASSING; AND -2" ROCK/10%-20% PASSING. BASINS AND MANHOLES, NOT LOCATED WITHIN A INSTALLATION SHALL BE IN ACCORDANCE WITH TRAVELED ROADWAY OR SIDEWALK SHALL HAVE KCRS, OR AS AMENDED BY THE APPROVED SOLID LOCKING LIDS, ALL DRAINAGE PLANS, RECYCLED ASPHALT OR CONCRETE STRUCTURES ASSOCIATED WITH A PERMANENT RUBBLE SHALL NOT BE USED. RETENTION/DETENTION FACILITY SHALL HAVE SOLID LOCKING LIDS. PERMIT RESUBMITTAL#2 TO CITY OF ® FEDERAL WAY (0707112014) 2215 North 30th Sheat, PANTHER LAKE ELEMENTARY SCHOOL Suite 300, Tacoma, WA 98403 253.383.2422 TEL 253.383.2572 FAX PORTABLES CIVIL SITE PLAN exr � CITY OF Federal July 10, 2014 Tim Toerber Green Gasaway Architects, PLLC 30405 18" Ave S FEDERAL WAY, WA 98003 CITY HALL 33325 8th Avenue South Feder y Federal Way, WA 98003-6325 (253) 835-7000 www.cityoffederalway.com RE: PANTHER LAKE ELEMENTARY PORTABLE CLASSROOM Folder # 14-102355-00-CO; 3442 1ST AVE S; Public Works First Review Dear Mr. Toerber: Public Works Department has completed its review of the information provided on May 21, 2014. Please make the following revisions: Technical Information Repo Project Overview: 1. Please discuss the intention to add more portables, timing, and the impervious area that would eventually be added at full build -out. Discuss the ramifications of this in light of the square footage thresholds established by both the 2009 KCSWDM for detention and the Federal Way Revised Code Section 19.30.120 for nonconforming water quality. L8 Water Oualit 2. FWRC Section 19.20.120 requirements should be discussed here. 4.0 Flow Control and Water Qualit Facilit Anal sis and Desi n 3. Distinguish between the single portable proposed at this point, and the project as a whole with additional portables. Indicate at what point the project will be required to meet current detention and water quality standards, or explain how it already meets current standards. Civil Plans 4. Provide City approval block with project number on each sheet. 5. Provide City of Federal Way Standard Plan Notes and Erosion/Sedimentation Control Notes, available at www.Cityoffederalway.com in -the Development Standards. Sheet C 1.0 6. Portions of the Site Data do not apply to this project. Please remove or strike through. Sheet C 1.1 7. Call out that the existing dispersion trenches are not to be disturbed, and provide a minimum 5' clearance between the silt fence and the dispersion trench. l:\csdc`,docs\save\ 1957840 1056.doc Sheet C 1.2 8. The dimensions on this sheet are provided at 1:10 and do not match the 1:20 scale provided. Resolve. 9. Call out minimum separation between the proposed rock pads and the existing infiltration trench and dispersion trench. 10. Extend northerly trench so that water is not directed across the existing infiltration trench to the south. 11. Provide pad elevation for the portable classroom. 12. Show any proposed grading. Please provide one set of plans and TIR revisions for further review. If you have any questions, please contact me at ann.dower(b)cityoffederalway.com or at 253-835-2732. Sincerely, f Ann Dower Senior Engineering Plans Reviewer AD:jo Cc: Adam Braun, P.E.; AHBL; 2215 N 30" St, Suite 300; Tacoma, WA 98403 Will Appleton, P.E.; Interim Deputy Public Works Director Df Had I:\csdc`docs�save\ 19578401056:doc 4to. 1q-,1t)ez555w-60 TACOMA SEATTLE RESUBmITTE® JUL 21 2014 CITY OF FEDERAL WAY CDS Technical Information Report PREPARED FOR: Greene-Gasaway Architects, PLLC PO Box 4158 Federal Way, WA 98063-4158 PROJECT.' Panther Lake Elementary School 34424 First Avenue South Federal Way, WA 98003 Project No. 2140205.10 PREPARED BY.' Adam C. Braun, PE Project Engineer REVIEWED BY.' Sean M. Comfort, PE Principal William J. Fierst, PE Project Manager DATE.' t May 12, 2014 Revised July 9, 2014 Revised July 21, 2014 Civil Engineers • Structural Engineers • Landscape Architects - Community Planners • Land Surveyors • Neighbors I hereby state that this Technical Information Report for Panther Lake Elementary School has been prepared by me or under my supervision, and meets the standard of care and expertise that is usual and customary in this community for professional engineers. I understand that the City of Federal Way does not and will not assume liability for the sufficiency, suitability, or performance of drainage facilities prepared by me. Technical Information Report PREPARED FOR: Greene-Gasaway Architects, PLLC PO Box 4158 Federal Way, WA 98063-4158 PROJECT' Panther Lake Elementary School 34424 First Avenue South Federal Way, WA 98003 Project No. 2140205.10 PREPARED BY: Adam C. Braun, PE Project Engineer REVIEWED BY' Sean M. Comfort, PE Principal William 1. Fierst, PE Project Manager DATE.• May 12, 2014 Revised ]uly 9, 2014 Revised July 21, 2014 Table of Contents Section Page 1.0 Project Overview............................................................................................................1 2.0 Conditions and Requirements Summary........................................................................1 2.1 Core Requirement #1 - Discharge at the Natural Location.............................................1 2.2 Core Requirement #2 - Offsite Analysis........................................................................2 2.3 Core Requirement #3 - Flow Control............................................................................2 2.4 Core Requirement #4 - Conveyance System.................................................................2 2.5 Core Requirement #5 - Erosion and Sediment Control...................................................3 2.6 Core Requirement #6 - Maintenance and Operations....................................................3 2.7 Core Requirement 0 - Financial Guarantees and Liability .............................................3 2.8 Core Requirement #8 - Water Quality ..........................................................................3 2.9 Special Requirement #1 - Other Adopted Requirements................................................3 2.10 Special Requirement #2 - Flood Hazard Delineation......................................................3 2.11 Special Requirement #3 - Flood Protection Facilities......................................................3 2.12 Special Requirement #4 - Source Control.....................................................................3 2.13 Special Requirement #5 - Oil Control...........................................................................3 3.0 Offsite Analysis...............................................................................................................4 3.1 Task 1 — Study Area Definition and Maps......................................................................4 3.2 Task 2 — Resource Review...........................................................................................4 3.3 Task 3 — Field Inspection.............................................................................................4 3.4 Task 4 — Drainage System Description and Problem Descriptions...................................5 3.5 Task 5 — Mitigation of Existing or Potential Problems.....................................................5 4.0 Flow Control and Water Quality Facility Analysis and Design........................................5 5.0 Conveyance System Analysis and Design.......................................................................5 6.0 Special Reports and Studies...........................................................................................6 7.0 Other Permits.................................................................................................................6 8.0 CSWPPP Analysis and Design.........................................................................................6 9.0 Bond Quantities, Facility Summaries, and Declaration of Covenant ..............................6 10.0 Operations and Maintenance Manual.............................................................................6 Technical Information Report 101Dme Panther Lake Elementary School Project No. 2140205.10 Appendices Appendix A Technical Information Report (TIR) Worksheet Exhibits A-1.................... Vicinity Map A-2.................... Soils Map A-3.................... Site Plan A-4.................... Existing Basin Map A-5.....-- .......... Developed Basin Map A-6 .................... Site Flow Rates A-7.................... Conveyance Calculations A-8.................... FIRM Rate Map A-9.................... King County HAP Information Appendix B Panther Lake Elementary School Technical Information Report Prepared by Otak, Inc., November 12, 2008 Technical Information Report M10130 Panther Lake Elementary School Project No. 2140205.10 1.0 PROJECT OVERVIEW Panther Lake Elementary School is located at 34424 1st Avenue South on Parcel No. 2021049110 in Federal Way, Washington. See Appendix A-1 for Vicinity Map. The 2014 portable classroom project is proposing to install one double portable classroom, ramp, stairs, and landings at Panther Lake Elementary School. See Appendix A-3 for Site Plan. This would result in 2,300 square feet of new impervious surface and zero (0) square feet of replaced impervious surface (total of 2,300 square feet of new plus replaced impervious surfaces). In addition, zero (0) square feet of impervious surface will be converted to pervious lawn. The site will realize a net increase of 2,300 square feet of impervious surfaces. See Appendices A-4 and A-5 for Existing and Developed Basin Maps. This project meets Full Drainage Review criteria per Section 1.1.2.3 of the 2009 King County Surface Water Design Manual (KCSWDM), as amended by the CFWAddendum to the KCSWDM, as the project will result in more than 2,000 square feet of new plus replaced impervious surface, but is not subject to Small Project Drainage Review. Dispersion will be used to meet Flow Control BMP Requirements. The new double portable classrooms will include four downspout extensions, connected to 8-inch drainpipes, which will discharge at the bottom of the existing slope for a total proposed roof area of 1,764 square feet. Approximately 882 square feet of roof area will drain to each of the two corner drainpipes, slightly exceeding the one splash block per 700 square feet of roof area requirement. Rock pads with 50 feet of separation meeting the requirements of Appendix C of the KCSWDMare provided, with minimum non-channelized vegetated flow paths exceeding 50 feet to the property line. r Federal Way School District has long-term plans of potentially building additional portable classrooms onsite. The number of additional portables, area of additional new impervious surfaces, and project schedule are not known at this time. Under the requirements of Section 1.2.3 of the 2009 KCSWDM, existing impervious surface added after January 8, 2001, that is not fully dispersed and not mitigated by an approved facility is considered a target surface subject to flow control requirements. The applicant understands that this requirement could necessitate construction of additional flow control improvements to mitigate for the current proposed portable classroom in the event that additional portable classrooms are constructed. Under the requirements of Sections 16.25.010 and 19.30.120 of the Federal Way Revised Code, redevelopment that involves the creation or addition of 5,000 square feet or more of new or replaced impervious surfaces results in the requirement to bring existing property improvements into compliance with water quality regulations in place at the time of redevelopment. The applicant understands that this requirement could necessitate construction of additional water quality improvements to mitigate for all existing site improvements, as well as the current proposed and any future proposed portable classrooms in the event that additional portable classrooms are constructed. 2.0 CONDITIONS AND REQUIREMENTS SUMMARY 2.1 Core Requirement #1 - Discharge at the Natural Location The natural discharge location for stormwater from the work area is the lawn area at the bottom of the existing hill, east of the proposed portable, which discharges to an offsite wooded area that contains at least one existing wetland. Technical Information Report Panther Lake Elementary School 1 Project No. 2140205.10 Stormwater roof runoff from the new portable will be discharged from the roof with downspouts connected to 8-inch drain lines. The 8-inch drain lines convey water to the bottom of the existing slope and discharge to a lawn area where water will sheet flow across additional flat lawn area to the east boundary of the site. All surface and stormwater runoff from the proposed development will continue to be discharged at the natural location, and thus will not adversely affect downstream properties or drainage systems. 2.2 Core Requirement #2 - Offsite Analysis AHBL staff performed a Level One Downstream Analysis for the project on April 30, 2014. The analysis included: • Defining and mapping the study area. ■ Reviewing available information on the study area. • Field inspecting the study area. • Analyzing the existing drainage system, including its existing and predicted problems, if any. Please refer to Section 3.0 for the full offsite analysis. 2.3 Core Requirement #3 - Flow Control The project site lies in the Conservation Flow Control Area, per the King County Flow Control Application Map of the 2009 KCSWDM. Projects in the Conservation Flow Control Area are subject to Level 2 Flow Control. This project meets Exception 2 for Conservation Flow Control Area because there is no more than a 0.1 cfs difference in the sum of developed 100-year peak flows for those target surfaces subject to this requirement and the sum of historic site conditions 100-year peak flows for the same surface areas. See pre- and post -developed peak flow rates in Appendix A-6. The project qualifies under Large Lot Low Impervious BMP Requirements per Section 5.2.1.2 of the 2009 KCSWDM. The feasibility and applicability of full dispersion was evaluated. The required 100-foot flow path to the edge of property is not available; therefore, full dispersion is not applicable. Full infiltration of roof runoff was evaluated. Per USGS Soils Maps, Everett-Alderwood gravelly sandy loam (EwC) soils are likely present on the site. See Appendix A-2 for a Soils Map. The geotechnical report prepared in 2008 for this site indicated that the site has seasonal perched groundwater above underlying impermeable till soil layers. See Appendix B for the 2008 Panther Lake Elementary School Technical Information Report (TIR), which includes the geotechnical report. Due to the impermeable lenses of soil underlying the site, full infiltration is not feasible. Basic dispersion was selected from the list of applicable BMPs in Section 5.2.1.2(3) of the 2009 KCSWDM. Rock pads for basic dispersion were selected as the dispersion device for the roof drain runoff per C.2.4.2 of the 2009 KCSWDM. Five roof drains with three discharge locations will be used to limit the roof area (1,764 square feet) per outfall location to less than 700 square feet. Flow from the splash blocks disperses to a 70-foot long lawn area, followed by offsite forest. 2.4 Core Requirement #4 - Conveyance System No new conveyance systems are proposed for this project. There will not be a significant change in flow characteristics; therefore, the project is exempt from Core Requirement #4. Technical Information Report©�� Panther Lake Elementary School 2 Project No. 2140205.10 2.5 Core Requirement #5 - Erosion and Sediment Control Onsite land disturbance will be very minimal and will consist of clearing the work site (approximately 5,000 square feet), and installation of the roof drain lines to the bottom of the slope. Erosion and sediment control will be provided with the use of temporary and permanent seeding within the work limits and existing grass areas downstream of the site, silt fence or wattles, and catch basin inlet protection. A Temporary Erosion and Sedimentation Control Plan has been included in the plan set. 2.6 Core Requirement #6 - Maintenance and Operations Maintenance and operation of all drainage facilities will be maintained by the owner. The project does not propose new structural drainage facilities. 2.7 Core Requirement #7 - Financial Guarantees and Liability No flow control, water quality, conveyance, erosion control, or road drainage facilities are being proposed for this development; therefore, Core Requirement #7 does not apply to this development. 2.8 Core Requirement #8 - Water Quality No pollution generating surfaces are proposed as part of this development; therefore, the development meets the Surface Area Exemption. Core Requirement #8 will not apply. Section 19.30.120 of the Federal Way Revised Code requires that the addition of more than 5,000 square feet of new or replaced impervious surfaces results in a requirement to provide water quality improvements for all existing pollution generating surfaces, meeting the requirements in place at the time of redevelopment, as cited in Chapter 16 of the Federal Way Revised Code. The project is proposing less than 5,000 square feet of new plus replaced impervious surfaces, as documented in Section 1.0 of this report, and therefore is not subject to this requirement at this time. 2.9 Special Requirement #1 - Other Adopted Requirements No adopted requirements apply to this project. 2.10 Special Requirement #2 - Flood Hazard Delineation The proposed project is not in or adjacent to the 100-year floodplain. 2.11 Special Requirement #3 - Flood Protection Facilities This project does not rely on existing flood protection facilities, nor will it modify or construct new flood protection facilities. 2.12 Special Requirement #4 - Source Control This project does not require a commercial building or commercial site development permit, and therefore does not require source controls. 2.13 Special Requirement #5 - Oil Control The site does not meet high use criteria and is not subject to oil control measures. Technical Information Report [Blame Panther Lake Elementary School 3 Project No. 2140205.10 3.0 OFFSITE ANALYSIS 3.1 Task 1— Study Area Definition and Maps Panther Lake Elementary School proposes to place one new portable building on the 11.15-acre site located at 34424 1" Avenue South in Federal Way, Washington. The project site lies within the Hylebos Creek Drainage Basin, as delineated by the King County Water Features Map. There are no wetlands on the project site. A small delineated wetland does exist offsite to the east of the project area. The attached 2008 TIR for Panther Lake Elementary, included as Appendix B, provides a full downstream analysis for the site. 3.2 Task 2 — Resource Review The following resources were reviewed to discover any existing or potential problems in the study area: Drainage Studies/Offsite Analysis Reports: Panther Lake Elementary School Technical Information Report prepared by Otak, Inc., November 12, 2008, included as Appendix B. FEMA Map: FEMA Flood Insurance Rate Map 53033C1250F, dated May 16, 1995, (see Appendix A-8) indicates that the project site lies within Zone X — Areas determined to be outside the 500-year floodplain. King County iMAP: The project site is not located in any of the following mapped critical areas (see Appendix A-9): o Coal Mine Hazard Areas o Erosion Hazard Areas o Landslide Hazard Areas o Seismic Hazard Areas o Critical Aquifer Recharge Areas 0 100-Year Flood Plain o Wetlands Soils Information: Site soils have been classified by the USDA Natural Resources Conservation Service (NRCS) as Alderwood gravelly sandy loam, 6 to 15 percent slopes (EwC) (see Appendix A-2). Associated Earth Sciences, Inc. prepared a Geotechnical Engineering Report for the project site in 2008, confirming the existence of Vashon Lodgement Till onsite. The Geotechnical Engineering Report is included in its entirety as a portion of Appendix B. The resource review did not reveal any potential downstream drainage problems. 3.3 Task 3 — Field Inspection A site visit was conducted on March 28, 2014, by AHBL staff. No drainage problems were noted at the time of the site visit. Technical Information Report Panther Lake Elementary School 41=1133 Project No. 2140205.10 3.4 Task 4 — Drainage System Description and Problem Descriptions The point of discharge from portable classroom improvements is an onsite lawn area. The lawn area sheet flows east to an offsite forested area. The 2008 TIR, attached as Appendix B, shows that the water continues to flow southeast through the forested area and a non -jurisdictional wetland to South 348th Street, under South 348th Street in a culvert, and into the West Hylebos Wetlands Park. 3.5 Task 5 — Mitigation of Existing or Potential Problems No downstream drainage problems were identified in the downstream analysis. 4.0 FLOW CONTROL AND WATER QUALITY FACILITY ANALYSIS AND DESIGN The project will not increase the 100-year peak flow rate from the forested condition to the proposed condition by more than 0.1 cfs, which exempts the project from flow control requirements, per Exception 2 in Section 1.2.3.1(B) of the 2009 KCSWDM. Detailed calculations to demonstrate exemption from flow control have been included in Appendix A-6. Future improvements to the site, including additional portable classrooms, may require additional flow control improvements to mitigate for the currently proposed portable classroom. Under the requirements of Section 1.2.3 of the 2009 KCSWDM, existing impervious surface added after January 8, 2001, that is not fully dispersed and not mitigated by an approved facility is considered a target surface subject to flow control requirements. The impervious surface added by this project would need to be included in flow control calculations for future onsite improvements to demonstrate continued exemption from the requirements or required mitigation meeting the requirements in place at the time of redevelopment. See Section 2.8 above for the Water Quality Analysis. Future improvements to the site, including additional portable classrooms, may require additional water quality improvements to mitigate for any existing onsite pollution -generating surfaces not meeting water quality regulations in place at the time of future redevelopment. Section 19.30.120 of the Federal Way Revised Code requires that redevelopment resulting in 5,000 square feet of new or replaced impervious surface results in a requirement to provide water quality improvements for all existing pollution generating surfaces, meeting the requirements in place at the time of redevelopment, as cited in Chapter :16 of the Federal Way Revised Code. The project is proposing less than 5,000 square feet of new plus replaced impervious surfaces, as documented in Section 1.0 of this report, and therefore is not subject to this requirement at this time. Construction of additional portable classrooms has been considered by the School District, but not yet committed to. In the event that additional portable classrooms or other onsite improvements resulting in added or replaced impervious surfaces are constructed, water quality improvements meeting the requirements in place at that time may be required for existing pollution -generating surfaces not meeting the requirements in place at that time. 5.0 CONVEYANCE SYSTEM ANALYSIS AND DESIGN The only drainage structures are roof downspout lines. Calculations to confirm the geometry of the downspout drains are included in Appendix A-7. Technical Information Report 1318100 Panther Lake Elementary School 5 Project No. 2140205.10 6.0 SPECIAL REPORTS AND STUDIES The need for special reports or studies is not anticipated at this time. 7.0 OTHER PERMITS No other permits are required as part of this proposed development per Sections 2.3.1.1 or 1.1.3 of the 2009 KCSWDM. 8.0 CSWPPP ANALYSIS AND DESIGN See Section 2.5 for Erosion and Sediment Control. 9.0 BOND QUANTITIES, FACILITY SUMMARIES, AND DECLARATION OF COVENANT See Section 2.7 above for Core Requirement #7 Financial Guarantees and Liability. 10.0 OPERATIONS AND MAINTENANCE MANUAL The project does not propose new drainage facilities to operate and maintain. This analysis is based on data and records either supplied to or obtained by AHBL. These documents are referenced within the text of the analysis. The analysis has been prepared using procedures and practices within the standard accepted practices of the industry. AHBL, Inc. 1) 17�L C a,. Adam C. Braun, PE Project Engineer ACB/lsk May 12, 2014 Revised July 9, 2014 Revised July 21, 2014 Q:\2014\2140205\WORDPROC\Reports\20140721_Rpt_MR)_2140205.10.doa Technical Information Report 101DOM Panther Lake Elementary School 6 Project No. 2140205.10 Appendix A Technical Information Report (TIR) W orksheet Exhibits A-1 ..................Vicinity Map A-2 ..................Soils Map A-3 ..................Site Plan A-4..................Existing Basin Map A-5 ..................Developed Basin Map A-6 .................. Site Flow Rates A-7 ..................Conveyance. Calculations A-8 ..................FIRM Rate Map A-9 ..................King County NAP Information Technical Information Report 13(0133 Panther Lake Elementary School Project No. 2140205.10 VICINITY MAP NOT TO SCALE r ■ Civil Engineers Mrra! Structural Engineers LandscapeArchilecls Q ©Q a Community Planners a Land Surveyors A40*rs T A C O M A• S E A T T L E 2215 North 30th Street, Suite 300, Tacoma, WA 98403 253.383.2422 TEL 1200 6th Avenue, Suite 162.0, Seattle, WA 98101 206.267.2425 TEL USDA United States Department of Agriculture N RCS Natural Resources Conservation Service A product of the National Cooperative Soil Survey, a joint effort of the United States Department of Agriculture and other Federal agencies, State agencies including the Agricultural Experiment Stations, and local participants Custom Soil Resource Report for King County Area, Washington May 9, 2014 Preface Soil surveys contain information that affects land use planning in survey areas. They highlight soil limitations that affect various land uses and provide information about the properties of the soils in the survey areas. Soil surveys are designed for many different users, including farmers, ranchers, foresters, agronomists, urban planners, community officials, engineers, developers, builders, and home buyers. Also, conservationists, teachers, students, and specialists in recreation, waste disposal, and pollution control can use the surveys to help them understand, protect, or enhance the environment. Various land use regulations of Federal, State, and local governments may impose special restrictions on land use or land treatment. Soil surveys identify soil properties that are used in making various land use or land treatment decisions. The information is intended to help the land users identify and reduce the effects of soil limitations on various land uses. The landowner or user is responsible for identifying and complying with existing laws and regulations. Although soil survey information can be used for general farm, local, and wider area planning, onsite investigation is needed to supplement this information in some cases. Examples include soil quality assessments (http://www.nres.usda,gov/wps/portal/ nres/main/soils/health/) and certain conservation and engineering applications. For more detailed information, contact your local USDA Service Center (http:// offices.sc.egov.usda.gov/locator/app?agency=nres) or your NRCS State Soil Scientist (http:,' - jvj,,.v.nres.usda.gov/wps/portal/nres/detaii/soils/contectus/? cid=nres142p2_053951). Great differences in soil properties can occur within short distances. Some soils are seasonally wet or subject to flooding. Some are too unstable to be used as a foundation for buildings or roads. Clayey or wet soils are poorly suited to use as septic tank absorption fields. A high water table makes a soil poorly suited to basements or underground installations. The National Cooperative Soil Survey is a joint effort of the United States Department of Agriculture and other Federal agencies, State agencies including the Agricultural Experiment Stations, and local agencies. The Natural Resources Conservation Service (NRCS) has leadership for the Federal part of the National Cooperative Soil Survey. Information about soils is updated periodically. Updated information is available through the NRCS Web Soil Survey, the site for official soil survey information. The U.S. Department of Agriculture (USDA) prohibits discrimination in all its programs and activities on the basis of race, color, national origin, age, disability, and where applicable, sex, marital status, familial status, parental status, religion, sexual orientation, genetic information, political beliefs, reprisal, or because all or a part of an individual's income is derived from any public assistance program. (Not all prohibited bases apply to all programs.) Persons with disabilities who require alternative means 2 for communication of program information (Braille, large print, audiotape, etc.) should contact USDA's TARGET Center at (202) 720-2600 (voice and TDD). To file a complaint of discrimination, write to USDA, Director, Office of Civil Rights, 1400 Independence Avenue, S.W., Washington, D.C. 20250-9410 or call (800) 795-3272 (voice) or (202) 720-6382 (TDD). USDA is an equal opportunity provider and employer. 3 Contents Preface ......... .......................... ...............................:......... . ,.,...................2 SoilMap ............................ ................ .....:................................................................ 5 SoilMap............................................................................ :................................... 6 Legend..................................................................................................................7 MapUnit Legend ........ ......................................... .......... ................. :........... ........... 8 MapUnit Descriptions..........................................................................................8 King County Area, Washington.......................................................................10 EwC-Everett-Alderwood gravelly sandy loams, 6 to 15 percent slopes .... 10 References....................................................................... :.................................. 12 4 Soil Map The soil map section includes the soil map for the defined area of interest, a list of soil map units on the map and extent of each map unit, and cartographic symbols displayed on the map. Also presented are various metadata about data used to produce the map, and a description of each soil map unit. Z F Nfi/G7S M „TS,6T oZZT . 1 I i ry (D L 3 Q O m 1 U) O O U) l U) 11 C O En 3 U M „T.OZ oZZT Z a OS61EZS 0£6LEZS OT6LEZS 06BLEZS OLSL£ZS z a OSSLEZS M .TS.6T ZZT 3 R N pU67 Q{ - d l7 O N v N N v — v CD m co Ln > 06 x µ O � g C E N E � o ry 0 0 L 0 p O Z_ m N Z M.T.OZ oZZT z a Z 0 O LL Z Ca C 0 Z W 0 W J a O O O N m aa) a a m 3 Q 0 a� a E O U m w T Z 7 O m H CD C C O 0 C) CDN CTrn J N O m O O a) >p C.1 N O m U) Q a) a N U C C T O m a tm m 0 L U a N a) p N j 0 O O C uE—�' O E U)CA a�>i NE w 0 o co,E a U J > �.- r U N N — U a) m E a) C m ca CL — w O` er m °D a) L d w (� m E Oj N a) � N w ° o m E m a) o C c'? CL N J oL Zaa U c No w w w N w p O) E O a C j a aai N a) a N Z m N �o ri) L E p N a� a� E co U ww m aNi o v p 03 r 3 N m O aCo to U) N U COa N N O Q > NE3m o o c ; m �a)� 7�` sm m o m - Q� Q � a L 3 N c O o Tm c• ° O cao a N ° L E �m a m L C O N ° m a) a� Q' ? a O d d J en U 'O m E D O J C O D fv a O L E N a C C 0 0 a) Mo U .O a) m L> Z- a O a -O O) a m L Q N 1° Nwaa1 mJ> (nN0 a)occ °u, Y> d Lac E m 0 m> m L Z w E L Q V m N_ N O rn O N O a m tm m E C E L a) T ,O a) a ca N L m c v an m E w a O O) a) a) .L a) N d f6 �� U 4 ° d ya )tm6 `) Q m Y T o c mH a ° 3a m m t c a C E� L ` N 0 0 C: w O co a) O � Q CLca L��. -C �' C E a N w U o N C y 5 U a a) N (n N Z E 2 co N O 'a a) N C N N N a E p a) cn�c) m O y L a'vQ cmi N Hw _ (°con = U) `o .2 aN a) E m E y N y J a m c m m LL U m t L a dJ N O y y O T C C = y N Q 0_ ). to J O m E al c0 N Jo p of a'O of t a O 0_ U) C O co Z. N > N a) L_ O N `1 D_ y _ U) ; U) y C • c w N R' U Z) O a ca v Q c i 3 F61 IM 0 y C O) y w w d Q O C .O p W U d N D E ra) a) C 7 +-. is a oQ a a) r. a a CO 3 3 y O 10 J O 0 m m 2� m Q -2 J O OQ ° W �^ n —O 1 O g m m m LL o cn 0) T w o LL r ( a O to ro o 0 rn N _ _ _ O t O ` l0 C > _C IC'/1 a) O C C > Y 'O Q m 'p m m U U C7 C7 J J a w (n a) U) fo aJ a) a, a X J 0 0 ,raw m 0 a a 'o U) w r- Custom Soil Resource Report Map Unit Legend Map Unit Symbol EwC King County Area, Washington (WA633) Map Unit Name YF Acres in AOI Percent of A01 Everett-Alderwood gravelly 3.3 100.0% sandy loams, 6 to 15 percent slopes Totals for Area of Interest 3.3 100.0% Map Unit Descriptions The map units delineated on the detailed soil maps in a soil survey represent the soils or miscellaneous areas in the survey area. The map unit descriptions, along with the maps, can be used to determine the composition and properties of a unit. A map unit delineation on a soil map represents an area dominated by one or more major kinds of soil or miscellaneous areas. A map unit is identified and named according to the taxonomic classification of the dominant soils. Within a taxonomic class there are precisely defined limits forthe properties of the soils. On the landscape, however, the soils are natural phenomena, and they have the characteristic variability of all natural phenomena. Thus, the range of some observed properties may extend beyond the limits defined for a taxonomic class. Areas of soils of a single taxonomic class rarely, if ever, can be mapped without including areas of other taxonomic classes. Consequently, every map unit is made up of the soils or miscellaneous areas for which it is named and some minor components that belong to taxonomic classes other than those of the major soils. Most minor soils have properties similar to those of the dominant soil or soils in the map unit, and thus they do not affect use and management. These are called noncontrasting, or similar, components. They may or may not be mentioned in a particular map unit description. Other minor components, however, have properties and behavioral characteristics divergent enough to affect use or to require different management. These are called contrasting, or dissimilar, components. They generally are in small areas and could not be mapped separately because of the scale used. Some small areas of strongly contrasting soils or miscellaneous areas are identified by a special symbol on the maps. If included in the database for a given area, the contrasting minor components are identified in the map unit descriptions along with some characteristics of each. A few areas of minor components may not have been observed, and consequently they are not mentioned in the descriptions, especially where the pattern was so complex that it was impractical to make enough observations to identify all the soils and miscellaneous areas on the landscape. The presence of minor components in a map unit in no way diminishes the usefulness or accuracy of the data. The objective of mapping is not to delineate pure taxonomic classes but rather to separate the landscape into landforms or landform segments that have similar use and management requirements. The delineation of such segments on the map provides sufficient information for the development of resource plans. If intensive use of small areas is planned, however, onsite investigation is needed to define and locate the soils and miscellaneous areas. 11 Custom Soil Resource Report An identifying symbol precedes the map unit name in the map unit descriptions. Each description includes general facts about the unit and gives important soil properties and qualities. Soils that have profiles that are almost alike make up a soil series. Except for differences in texture of the surface layer, all the soils of a series have major horizons that are similar in composition, thickness, and arrangement. Soils of one series can differ in texture of the surface layer, slope, stoniness, salinity, degree of erosion, and other characteristics that affect their use. On the basis of such differences, a soil series is divided into soil phases. Most of the areas shown on the detailed soil maps are phases of soil series. The name of a soil phase commonly indicates a feature that affects use or management. For example, Alpha silt loam, 0 to 2 percent slopes, is a phase of the Alpha series. Some map units are made up of two or more major soils or miscellaneous areas. These map units are complexes, associations, or undifferentiated groups. A complex consists of two or more soils or miscellaneous areas in such an intricate pattern or in such small areas that they cannot be shown separately on the maps. The pattern and proportion of the soils or miscellaneous areas are somewhat similar in all areas. Alpha -Beta complex, 0 to 6 percent slopes, is an example. An association is made up of two or more geographically associated soils or miscellaneous areas that are shown as one unit on the maps. Because of present or anticipated uses of the map units in the survey area, it was not considered practical or necessary to map the soils or miscellaneous areas separately. The pattern and relative proportion of the soils or miscellaneous areas are somewhat similar. Alpha - Beta association, 0 to 2 percent slopes, is an example. An undifferentiated group is made up of two or more soils or miscellaneous areas that could be mapped individually but are mapped as one unit because similar interpretations can be made for use and management. The pattern and proportion of the soils or miscellaneous areas in a mapped area are not uniform. An area can be made up of only one of the major soils or miscellaneous areas, or it can be made up of all of them. Alpha and Beta soils, 0 to 2 percent slopes, is an example. Some surveys include miscellaneous areas. Such areas have little or no soil material and support little or no vegetation. Rock outcrop is an example. 0 Custom Soil Resource Report King County Area, Washington EwC—Everett-Alderwood gravelly sandy loams, 6 to 15 percent slopes Map Unit Setting Elevation: 50 to 800 feet Mean annual precipitation: 25 to 60 inches Mean annual air temperature: 48 to 52 degrees F Frost -free period: 180 to 220 days Map Unit Composition Alderwood and similar soils: 45 percent Everett and similar soils: 45 percent Minor components: 5 percent Description of Everett Setting Landform: Terraces Parent material: Glacial outwash with a component of volcanic ash in the upper part Typical profile H1 - 0 to 17 inches: moderately acid, gravelly ashy sandy loam H2 - 17 to 32 inches: moderately acid, very gravelly sandy loam H3 - 32 to 60 inches: slightly acid, very gravelly coarse sand Properties and qualities Slope: 6 to 15 percent Depth to restrictive feature: More than 80 inches Natural drainage class: Somewhat excessively drained Capacity of the most limiting layer to transmit water (Ksat): High (1.98 to 5.95 in/hr) Depth to water table: More than 80 inches Frequency of flooding: None Frequency of ponding: None Available waterstorage in profile: Low (about 5.0 inches) Interpretive groups Farmland classification: Not prime farmland Land capability classification (irrigated): None specified Land capability classification (nonirrigated): 3e Hydrologic Soil Group: A Other vegetative classification: Unnamed (G002XN402WA) Description of Alderwood Setting Landform: Moraines, till plains Parent material: Basal till with some volcanic ash Typical profile H1 - 0 to 12 inches: moderately acid, gravelly ashy sandy loam H2 - 12 to 27 inches: moderately acid, very gravelly sandy loam H3 - 27 to 60 inches: moderately acid, very gravelly sandy loam Properties and qualities Slope: 6 to 15 percent Depth to restrictive feature: 24 to 40 inches to densic material 10 Custom Soil Resource Report Natural drainage class: Moderately well drained Capacity of the most limiting layer to transmit water (Ksat): Very low to moderately low (0.00 to 0.06 in/hr) Depth to water table: About 18 to 37 inches Frequency of flooding: None Frequency of ponding: None Available water storage in profile: Very low (about 2.5 inches) Interpretive groups Farmland classification: Not prime farmland Land capability classification (irrigated): None specified Land capability classification (nonirrigated): 4s Hydrologic Soil Group: B Other vegetative classification: Unnamed (G002XN302WA) Minor Components Norma Percent of map unit.- 2 percent Landform: Depressions Seattle Percent of map unit: 2 percent Landform: Depressions Tukwila Percent of map unit: 1 percent Landform: Depressions 11 References American Association of State Highway and Transportation Officials (AASHTO). 2004. Standard specifications for transportation materials and methods of sampling and testing. 24th edition. American Society for Testing and Materials (ASTM). 2005. Standard classification of soils for engineering purposes. ASTM Standard D2487-00. Cowardin, L.M., V. Carter, F.C. Golet, and E.T. LaRoe. 1979. Classification of wetlands and deep -water habitats of the United States. U.S. Fish and Wildlife Service FWS/OBS-79/31. Federal Register. July 13, 1994. Changes in hydric soils of the United States. Federal Register. September 18, 2002. Hydric soils of the United States. Hurt, G.W., and L.M. Vasilas, editors. Version 6.0, 2006. Field indicators of hydric soils in the United States. National Research Council. 1995. Wetlands: Characteristics and boundaries. Soil Survey Division Staff. 1993. Soil survey manual. Soil Conservation Service. U.S. Department of Agriculture Handbook 18. http://www.nres.usda.gov/wps/portal/nres/ detail/national/soils/?cid=nresl42p2-054262 Soil Survey Staff. 1999. Soil taxonomy: A basic system of soil classification for making and interpreting soil surveys. 2nd edition. Natural Resources Conservation Service, U.S. Department of Agriculture Handbook 436. http://www.nres.usda.gov/wps/portal/ nres/detail/national/soils/?cid=nres142p2_.053577 Soil Survey Staff. 2010. Keys to soil taxonomy. 11th edition. U.S. Department of Agriculture, Natural Resources Conservation Service. http://www.nres.usda,gov/wps/ portal/nres/detail/national/soils/?cid=nres142p2_053580 Tiner, R.W., Jr. 1985. Wetlands of Delaware. U.S. Fish and Wildlife Service and Delaware Department of Natural Resources and Environmental Control, Wetlands Section. United States Army Corps of Engineers, Environmental Laboratory. 1987. Corps of Engineers wetlands delineation manual. Waterways Experiment Station Technical Report Y-87-1. United States Department of Agriculture, Natural Resources Conservation Service. National forestry manual. http://www.nres.usda.gov/wps/portal/nres/detail/soils/ home/?cid=nres142p2_053374 United States Department of Agriculture, Natural Resources Conservation Service. National range and pasture handbook. http://www.nres.usda.gov/Wps/portal/nres/ detail/national/landuse/rangepasture/?cid=stelprdb1043084 12 Custom Soil Resource Report United States Department of Agriculture, Natural Resources Conservation Service. National soil survey handbook, title 430-VI. http;l/www.nres.usda.gov/wps/portal/ nres/detail/soilslscientistsl?cid=nres 142p2_054242 United States Department of Agriculture, Natural Resources Conservation Service. 2006. Land resource regions and major land resource areas of the United States, the Caribbean, and the Pacific Basin. U.S. Department of Agriculture Handbook 296. http://www. n rc s. u s d a. g ov/wps/p orta I/nres/d eta i t/national/so i Is/? cid=nres 142p2_053624 United States Department of Agriculture, Soil Conservation Service. 1961. Land capability classification. U.S. Department of Agriculture Handbook 210. http:// www.nrcs,usda.g<)v/lnternet/FSE_DOCUMENTSInrcsl42pLO52290.pdf 13 PANTHER LAME ELEMENTARY SCHOOL - POR1 A PORTION OF THE NE. 1/4 OF THE NW. 1/4 OF THE SW. 1/4 OF SEC. 20, TWP. KING COUNTY, WASHINGTON 1 l :JJJjJ3I II 1 _ 4 - CLEANOUT . y`264�a1• P61�7 R!M=TB3.10 y� IE-261.68 (8") ryp 3 28 LF 8"HDPE @ 1721%RD RI�M58.88 1 r I .^ 1 •[! �. D8 I E=256.86 (8") DS fLF B"1 DE�B� -----T .-- IE=254.94- 1 + CLEANOUT RIM- 258-72 IE=256.72 (8") RD CLPJWOU7 RIM= 256 85 IE=257.31 (8") FABLES 21 N., RGE. 4 E., W.M. I I JI I I 1 • AHBL=,; I: I C7tAPA7C SCALE 1 0 10 20 40 FELT V = 20 FEET KEYNOTES ODOWNSPOUT CONNECT TO ROOF DRAIN LINE. 5 C7.3 O ASPHALT PAVEMENT @ HOT TAR SEAL JOINT CS.3 OPORTABLE CLASSROOM PER MANUFACTURER'S DRAWINGS. O ROCK PAD FOR BASIC DISPERSION e C1.3 GENERAL NOTES 1. CONTRACTOR SHALL VERIFY EXISTING AND PROPOSED GRADES BEFORE COMMENCING WORK. CONTACT ENGINEER IF ACTUAL GRADES DO NOT REFLECT GRADES OF TOPOGRAPHICAL SURVEY- 2. ADJUST VISTWS UTILITIES WITHIN WORK LIMITS TO FINISHED GRADE 3. REDD W AND WKFI LL IN PIPE TRENCHES PER DETAIL CL3 4. ENSURE POSITIVE DRAINAGE MAINTAINED AWAY FROM PORTABLES. SOIL SHALL NOT BE PLACED AGAINST SKIRTING. S. ALL EXCESS SOIL MATERIAL AND CONSTRUCTION WASTE SHALL BE DISPOSED OF AT AN APPROVED OFF -SITE LOCATION 6. RESTORE IRRIGATION IN DISTURBED VEGETATION AREAS, 7, RESTORE DISTURBED LAWN AREAS WITH TOPSOIL AND HYDROSEED PER HYROSEEDING NOTES ON SHEET C7.1. i �r_GNn ROOF DRAIN LINE RD ASPHALT CONCRETE PAVEMENT STRUCTURE 2 C 4.3 STORM DRAIN CLEANOUT • 1 C1.3 v Know what's below. Call before you dig. .ESS THAN 22" x 34" SCALE ACCORDINGLY Mar& T A C O M A• SEATTLE • SPOKANE •TRI-CITIES 2215 North 30th Street, Sulte 300 Tacoma, WA 98403 253.303.2422 TEL 253.333.2572 FAX wwwahbl com W® Prole. L rr8c. PANTHER LAKE ELEMENTARY SCHOOL PORTABLES C11e"r FEDERAL WAY SCHOOL DISTRICT 210 31405 18th AVENUE SOUTH FEDERAL WAY, WASHINGTON 98003 (253) 945-2000 Job No. 2140205 10 PERMIT SET APRIL 15, 2014 �� 47 ••T.�o,�a 70pAL N"01 biaaww Mir¢ewi Re.hiane ShootT411e- CIVIL SITE PLAN A BRAUN M. STEWART W. FIERST Snbe1 No. A- 3 L11---- I I a 1- J PANTHER LAKE ELEMENTARY SCHOOL - PORTABLES A PORTION OF THE NE. 1/4 OF THE NW. 1/4 OF THE SW. 1/4 OF SEC. 20, TWP. 21 N., RGE. 4 E., W.M. KING COUNTY, WASHINGTON LEGEND ':• '• •::.: yr: l� -•�' --- - - .+�-'� STING FOREST (TARGET SURFACE) EXISTING CE f ii i r 1 I � � 1 I ; ox Know what's below. Call before you dig. x 34" SCALE ACCORDINGLY mom D= F A C 0 M A- SEATTLE • SPOKANE •TRI-CITIES 215 North 30th Street, Sufte 300 Tacoma, WA 98403 253.3832422 TE 253.393292 FAX www.ahbl.com Wm a vlte.� Talc. PANTHER LAKE ELEMENTARY SCHOOL PORTABLES u �I: FEDERAL WAY SCHOOL DISTRICT 210 314051 S0r AVENUE SOUTH FEDERAL WAY, WASHINGTON 98003 (253) 945-2000 Jab No. 2140205.10 Issue SePERMIT SET APRIL 15, 2014 �L. CO 2 we 70NAL NOTICE sheet Tm% EXISTING BASIN MAP OvslosvV_ys� Orj w— t, , GNckeo m A BRAUN M. STEWART W. FIERST A-4 or 4 Sheets PANTHER LAKE ELEMENTARY SCHOOL - PORTABLES A PORTION OF THE NE. 1/4 OF THE NW. 1/4 OF THE SW. 1/4 OF SEC. 20, TWP. 21 N., RGE. 4 E., W.M. KING COUNTY, WASHING ON LEGEND N" PROPOSED IMPERVIOUS (TARGET SURFACE) i •axBL=: c GRAPe<C SCALE 0 10 20 40 FEET 1' = 20 FEET CX3 Know whars below. Call before you dig. 0 r A C 0 M A• SEATTLE • SPOKANE •TRI-CITIES 215 North 30th Street, Sulle 300 Tacoma, WA 88403 253.383.2422 TEL 253.383.2572 FAX www ahbl.com waa vralvcr Tllrn: PANTHER LAKE ELEMENTARY SCHOOL PORTABLES Cllent: FEDERAL WAY SCHOOL DISTRICT 210 31405 lath AVENUE SOUTH FEDERAL WAY, WASHINGTON 98003 (253) 945-2000 Job No. 2140205.10 Icsov SatJ_0.14_ PERMIT SET APRIL 15, 2014 �In® , loftt. NoN0110 pil Ra.'slvas: At" T-11m DEVELOPED BASIN MAP Ovclvv�eyy D'... ev, OhackCd_br: A BRAUN M STEWART W. FIERST A-5 or 4 Sheets I KCRTS Program ... File Directory: c:\kc_swdm\kC_DATA\ [C] CREATE a new Time Series ST 0.05 0.00 0.000000 Till Forest 0.00 0.00 0.000000 Till Pasture 0.00 0.00 0.000000 Till Grass 0.00 0.00 0.000000 Outwash Forest 0.00 0.00 0.000000 Outwash Pasture 0.00 0.00 0.000000 Outwash Grass 0.00 0.00 0.000000 Wetland 0.00 0.00 0.000000 Impervious pre.tsf T 1.00000 T [T] Enter the Analysis TOOLS Module [P] Compute PEAKS and Flow Frequencies pre.tsf pre.pks [R] RETURN to Previous Menu [C] CREATE a new Time Series ST 0.00 0.00 0.000000 Till Forest 0.00 0.00 0.000000 Till Pasture 0.00 0.00 0.000000 Till Grass 0.00 0.00 0.000000 Outwash Forest 0.00 0.00 0.000000 Outwash Pasture 0.00 0.00 0.000000 Outwash Grass 0.00 0.00 0.000000 Wetland 0.05 0.00 0.000000 Impervious post.tsf T 1.00000 T [T] Enter the Analysis [P] Compute PEAKS and F1 post.tsf post.pks [R] RETURN to Previous Menu [X] eXit KCRTS Program Flow Frequency Analysis Time Series File:pre.tsf Project Location:Sea-Tac ---Annual Peak Flow Rates --- Flow Rate Rank Time of Peak (CFS) 0.003 2 2/09/01 15:00 0.001 7 1/05/02 17:00 0.003 3 2/28/03 3:00 0.000 8 12/28/03 21:00 0.002 6 1/05/05 8:00 0.003 4 1/18/06 22:00 0.002 5 11/24/06 4:00 0.004 1 1/09/08 6:00 Computed Peaks Flow Frequency Analysis Time Series File:post.tsf Project Location:Sea-Tac ---Annual Peak Flow Rates --- Flow Rate Rank Time of Peak (CFS) 0.012 7 2/09/01 2:00 0.011 8 1/05/02 16:00 0.015 3 12/08/02 18:00 0.012 6 8/26/04 2:00 0.015 4 10/28/04 16:00 0.013 5 1/18/06 16:00 0.018 2 10/26/06 0:00 0.023 1 1/09/08 6:00 Computed Peaks TOOLS Module ow Frequencies Flow Frequency Analysis------- - - Peaks - - Rank Return Prob (CFS) Period 0.004 1 100.00 0.990 0.003 2 25.00 0:960 0.003 3 10.00 0.900 0.003 4 5.00 6.800 0.002 5 3.00 0.667 0.002 6 2.00 0.50C 0.001 7 1.30 0.231 0.000 8 1.10 0.091 0.004 50.00 0.98C Flow Frequency Analysis------- - - Peaks - - Rank Return Prob (CFS) Period 0.023 1 100.00 0.990 0.018 2 25.00 0.960 0.015 3 10.00 0.900 0.015 4 5.00 0.800 0.013 5 3.00 0.667 0.012 6 2.00 0.500 0.012 7 1.30 0.231 0.011 8 1.10 0.091 0.022 50.00 0.980 The maximum flow rate on -site is 0.05 cubic feet per second. The smallest pipe with the flattest slope is an 8-inch diameter pipe with 1.81% or 0.0181. This calculation demonstrates that the smallest flattest pipe on the site is capable of conveying the largest 100-year flow on -site. No additional calculations have been provided. The calculation provides the conservative assumption that one downspout drain carries flow for the entire additional impervious surface, when, in fact, the flow is split. Q = AV = (A/n) x Rh'/3 x Si/z r = 0.33 ft A = 7G rz Rh = A/Pv, = nr2/27cr = r/2 Smin = 0.0181 n = 0.014 Qsystem = 1.19 cfs Qreq'd = 0.023 cfs The system provides 5153% of the flow capacity required for this project. HOME NEWS SERVICES DIRECTORY CONTACTSearch Terms: Search KCGIS Parcel Reports r Districts and Development Conditions Report Find Your Council District Find Your Watershed KCGIS Center King County GIS Center King Street Center 201 S. Jackson St. Suite 706 Seattle, WA 98104 aiscenter0kingcounhL_q v 1 + 47.59909 N - 122.33136 W + 47' 35' 56.72" 1 - 122' 19' 52.90" _J KCGIS Center www.KingCounty.gov/GIS King County Districts and Development Conditions for parcel 2021049110 Parcel number 2021049110 Drainage Hylebos Creek Address 344241ST AVEf Basin S Wate shed Puyallup River Jurisdiction _ _ _ Federal WayT ^ MIA Puyallup -White 98003 - ._ .......... . .... ....--. -... .... Kroll Map page W _ 736 PLSS SW - 20 - 21 - 4 Thomas Guide 744 Latitude 47.29443 page Longitude -122.33339 7 •r..t Electoral Districts ^Fire FED 30-3003- district South King Fire and Rescue Kirq Coon. Courlcil..disttict District 7, Pete von Water district does not apply Reichbauer Sewer district does not apply (206) 296-1007 :- _.._._.................._._....,.._.__....._,.,,_.._,.,..,...._..._.._ Water & Sewer district ...._ .... - Lakehaven Utility District — - - -- - ".... T''- Parks & Recreation does not apply Congressional district 9 district Legislative district 30 Hospital district does not apply School district Federal _ - ----•- •••-•-• Rural library district Rural King County Library Seattle school board district does not apply (not in System J u ^ Seattle) Trihnl l.aW.{F? — Al _ 9 planning and critical areas designations— King County nations . King County zoning NA, check with Potetrtial annexation a= does not apply jurisdiction J Rural town? No Deve op!: lent conditions T None Water service planninti area not ppl Camprehensiv Plan _ --- _._ does not apply ................._.........._.......... Roads Mpg zone 252 and 256 _ .. . .......... Urban Growth Area .... Urban - _ Transportation CoricArrency� _ does not apply ........... __............ pprrlmunity Service AwiL � does not apply Management Community Planning Are Federal Way Forest Production district? No Coal mine hazards? None mapped Agricultural Production district? No Erosion hazards? None mapped Critical aquifer recharge area? None mapped _... - Landslide hazards? _ None mapped 100-yeas flood plain? None mapped Seismic hazards? None mapped Wetlands at this parcel? None mapped Within ft Tacoma 5 elter Non -Detect to 20.0 Plume? PPm Related resources King County Assessor: eReal Property Report King County Assessor: Quarter Section Map (PDF format requires Acrobat) King County DPER: Permit Applications Report (for unincorporated areas only) King County Treasury Operations: Lrogern Tax Information for this rra ert King County Recorders Office: Scanned Images of plats, King County Recorders Office: Scanned images of surveys and other map documents. Seattle/King County Public Health: Septic system as -built documents, Open WAP to this property Open Parcal Viewer to this property Search Address or parcel number: Go Reset ❑ search by condo name example address: 8621 428TH AVE SE I example parcel number: 0942000860 This report was generated on 5/9/2014 3:27:42 PM Horne Pri_ vacv Accessihiii I Tennof use Sgar n Contact us at giscenterrwkingGpuntv.00v. Links to external sites do not constitute endorsements by King County. By visiting this and other King County web pages, you expressly agree to be bound by terms and conditions of the site. © 2013 King County Appendix B Panther Lake Elementary School Technical Information Report Prepared by Otak, Inc., November 12, 2008 Technical Information Report 1310MM Panther Lake Elementary School Project No. 2140205.10 M Panther Lake Elementary School Technical Information Report Submitted to: The City of Federal Way 33325 8"� Avenue South Federal Way, WA 99063 Owner's Representative: Greene Gasaway Architects PO Box 4158 Federal Way, WA 98063 Prepared by: Otak, Inc. 10230 NE Points Drive, Suite 400 Kirkland; WA 98033 Otak Project No. 31147A November 12, 2008 Table of Contents Panther Lake Elementary School Technical Information Report Section I— Project Overview Figure 1—Vicinity Map Figure 2a—East and West Developed Basin Area Figure 2b—East and West Existing Basin Area Figure 2c—Offsite Improvement Basin Area Figure 2d--Roof Drainage Areas Figure 3—Soils Map Section 2—Preliminary Conditions Summary and Conditions of Approval Section 3—Offsite Analysis Figure 4a — East Downstream Exhibit Figure 4b — West Downstream Exhibit Figure 5a — West Offsite Drainage Table Figure 5b — East Offsite Drainage Table Section 4—Flow Control and Water Quality Facility Analysis and Design Appendix A.I—West Basin KCRTS Input Files Appendix A.2—West Basin Flow Control Calculations Appendix A.3 West Basin Water Quality Calculations Appendix A.4—West Basin Existing Parking Area Appendix B.I—East Basin Water Quality Calculations Appendix B.2— KCES Flow Splitter Design Appendix B.3— Roof Downspout Study Appendix B.4— Source Controls Section 5--Conveyance System Analysis and Design Appendix C.I—East 25 Year Backwater Analysis Appendix C.2—East 100 Year Backwater Analysis Appendix C.3—West 25 Year Backwater Analysis Appendix CA —West 100 Year Backwater Analysis Appendix C.5-25 Year Rational Method Computations Appendix C,6-100 Year Rational Method Computations Figure 6--Conveyance Sub -Basins Exhibit Section 6—Special Reports and Studies Appendix D—Preliminary Geotechnical Report This page left intentionally blank for double -sided printing. Table of Contents. Continued Section !—Other Permits Section 8—Erosion and Sedimentation Control Analysis and Design Appendix E.I—West Sediment Tank Sizing Calculations Appendix E.2-^East Sediment Pond SIA' nZ Calculations Appendix. F--Construct€orr Stormwlater Poll uWn Preventi.on Plan CSWPPP Figure 7--Sedimot Basin Areas Section "and Quantity Worksheet, Facility Summaries .and Declaration of Covenant Section I0=—Ciperations and Maintenance Manual Appendix G.1—Maintenance Requirements for Flaw Control, Conveyance, and WQ Facilities Appendix G.Z-- Catch Basin Stormfilter Operation and Maintenance: Appendix G.3—=Stormfrlter Inspection and Maintenance Procedures, 1 J j Section One Section I —Project Overview This Technical Information Report (TIR) is provided in support of the design of the redevelopment of the existing Panther Lake Elementary School. Project Overview Panther Lake Elementary School is located on parcel numbers 202104-9110-05 and 202104-918M8, which total 11,15 acres in Federal Way, King County, Washington as shown on the Vicinity Map shown in Figure 1. The site is located in the SW Quarter of Section 20 of Township 21 North, Range 4 East, and lies within the West Hylebos Drainage Basin of the larger Puyallup River Watershed. The site currently serves as the location of the existing Panther Lake Elementary School. The site is located at 34424 1st Avenue South. The property is bordered by the Federal Way Regional Library to the north, Western Hill condominium complex to the south, a large wetland to the east, and 1" Avenue. South to the west. The project will consist of building a new school at the northern portion of the parcel. The total gross floor area of the new school will be approximately 43,145 SF. The existing parking and drive isles will be expanded along the west property frontage along 1" Avenue South. The existing school will remain as the new school is being constructed. A temporary detention pond/sediment basin will be provided to mitigate storm -water runoff from the new building, and will be used until the existing building is demolished. v{ r FA NTH L E� � I S•. H ST, PKc� PROJECT � 1 SITE v: S: 348TH ST. NT4+, VICINITY MAP 1 Figure 1: Vicinity Map Panther Lake Elementary .Scbool TIR 1 otak IG\projrct\.S t 1CO\341i7A\Hepnnsl.T)R\Test dw Section I —Project Overview Continued Existing Conditions The site is the location of an existing school., originally built in the 1960"s, the north wing of the school was added in 1967. The site consists of the existing school and _ ] associated out -buildings; it also contains a parking lot, playground, and playfield. There are two separate threshold discharge areas onsite, which flow east and west before joining together approximately 0.8 miles downstream of the site, a location i within the Hylebos Wetland Park, which is located south of the site. The existing east and west basin sections in the Offshe Analysis section of this TIR will address the tributary roof areas. East Basin; The east basin is composed of a portion of the north parking and drive lane around the east side of the building, grassy open spaces; non -pollution generating rooftops, sidewalks and paved playgrounds. Exhibit 2b is included in this section, and shows the - existing land cover for the east basin. West Basin; The west basin is comprised of non -pollution generating rooftops and sidewalks in addition to three parking. lots. The southern parking lot discharges directly without any flow control or water quality treatment. The middle bus drop-off parking lot, built in 2003, passes through a pair of Stormfilter catch basins then through a twin 72" diameter CMP by 45 L.F. flow control tank before discharging west to a catch basin in 1st Avenue. The north parking ! lot is free draining to 1st Avenue South without treatment. See Figure 2b for existing west basin areas. A left turn lane will be added to 1st Avenue South, No turn lane exists in the existing I'I condition. The proposed frontage improvements consist of curb, gutter; planter strip, �1 and sidewalk. See Figure 2c for offsite improvement areas, Panther Labe Elementary School TIR 2 otak K:\projca �J; I.60\] ] 147n\a �or.s\'CSIi\Te.c,due Section I —Project Overview Continued Proposed Site Drainage Characteristics West Basin: The proposed west basin development consists of parking lots, landscaping, and a portion of the proposed roof area. There is an existing flow control facility located underneath the existing parking lot; which will continue to mitigate stormwater runoff from the 0.17 acres of PGIS that currently flow to it. An additional flow control facility will be required for this basin because the proposed impervious areas result in a net increase of greater than 5,000 square feet when compared to the existing impervious areas within the threshold discharge area. See Figure 2a for developed basin exhibit, and Section 4 for flow control calculations. A 54" underground detention pipe will be used to mitigate stormwater from the proposed west basin. It will be preceded by a CDS pretreatment catch basin and a 8- foot by 16-foot Stormfilter water quality vault with 26 cartridges. The water quality facility is required for this basin because the project exceeds the existing PGIS area thrreshold by more than the 5,000 SF for the threshold discharge. area (see Figure 2a for details). East Basin: The east basin is comprised of areas which include the proposed school, shared access drive, play area, and existing grass field. A flow control facility will not be required for this basin because the proposed impervious areas do not result in a net increase of greater than 5,000 square feet when compared to the existing impervious areas within the basin. See Figure 2a for developed basin exhibit and Section 4 for flow control calculations. A water quality facility will be provided for this basin because the project exceeds the existing PGIS area threshold by more than 5,000 SF for the east basin threshold discharge area. The water quality facility will be shared and thus sized in conjunction. with offsite flows from the adjacent King County Library improvement project. Panther Lake EIementary Schaal TIR atak K:\projm\3IIG:\3I14;,\\Ripor1s\'3TR\Try[ dur Section I —Project Overview Continued The water quality facility will consist of an 8-foot by 18-foot Stormfilter vault. A CDS pretreatment catch basin will precede the Stormfilter water quality vault, and thus meet pretreatment requirements. A flow splitter will be used to only enable the 2-year storm event from the King 1 County Library System (KCLS) site to flow to the shared water quality vault. Storm 1 events exceeding the 2-year event will bypass the water quality vault and disperse north lin the east corner of the site. (see Appendix B.2 for flow splitter design information). 1 Offsite lmprovements: A left turn lane will be added at the south entrance site entrance along 1st Avenue South. The addition of a left turn lane requires the roadway to be widened between the middle and south entrances. There is a high point at the south entrance (see point A in Figure 2c), which diverts stormwater to two distinct threshold discharge areas; one to the north and another to the south. Approximately 2143 SF of impervious surface will be added to the south drainage 1 basin, and 2822 SF of impervious will be added to the north drainage basin. i Existing catch basins along the south frontage improvement basin will need to be retrofitted with a solid lid. New catch basins will be added along the face of curb of the widened roadway, and will connect to the existing catch basins (see points B and C in Figure 2c). Basis for Stormwater Detention Facility Design I A detention facility will be utilized to mitigate stormwater runoff for a threshold I discharge area which results in a net increase in impervious surface of 5,000 SF over the existing basin. Detention facilities will be designed to comply with Level 1 flow control requirements as described in Section 1.2.3 of the 1998 King County Surface JWater Drainage Manual (KCSWDA. See Section 4 for flow control design information. Panther Lake Elementary School TIR 4 otak K:\projm\3€100\31147A\Ilgxrita\TLK\Te.xi.4, .. J Section I --Project Overview Continued Basis for Storm Drainage Conveyance Design The storm drainage and conveyance systems have been designed in accordance with. the KCSWDM, Core Requirement #4 of the KCSWDVI requires storm_ drains to convey 25-year storm events without overtopping drainage structures. The pipe system may overtop for runoff events that exceed the 25-year design capacity, provided the overflow from a 100-year runoff event does not create or aggravate a severe flooding or erosion problem. See Section 5 for storm water design information. Site Soil Condition The soils onsite are identified as Everett-Alderwood gravelly sandy loam (EwC), an outwash soil as classified by the National Cooperative Soil Survey, see Figure 3-Soils Map. The geotechnical investigation findings show that lodgment till make up the onsite soils. See Appendbr .D for Preliminary G.eotechnical Report. Panther Lake Elementary School TIR 5 alak &;\Pf- jW\11IM" I147MReuffrrsST[R\T.VL.d6r Figure 2a—East and West Developed Basin Area Section 1--Project Overview This Technical Information Report (TIR) is provided in support of the design of the redevelopment of the existing Panther Lake Elementary School. Project Overview Panther Lake Elementary School is located on parcel numbers. 202104-9110-05 and 202104-9182-08, which total 1 1. 15 acres in Federal Way, King County, Washington as shown on the Vicinity Map shown in Figure 1. The site is located in the SW Quarter of Section 20 of Township 21 North, Range 4 East, and lies within the West Hylebos Drainage. Basin of the larger Puyallup River Watershed. The site currently serves as the location of the existing Panther Lake Elementary School. The site is located at 34424 1st Avenue South. The property is bordered by the Federal Way Regional Library to the north, Western Hill condominium complex to the south, a large wetland to the east, and 1' Avenue South to the west. The project will consist: of building anew school at the northern portion of the parcel. The total gross floor area of the new school will be approximately 43,145 SF. The existing parking and drive isles will be expanded along the west property frontage. along I" Avenue South. The existing school will .remain as the new school is being constructed. A temporary detention pond/sediment basin will be provided to mitigate stormwater runoff from the new building, and will be used until the existing building is demolished. �F�E TW 1 H ST. ,)rrrrP ArxL=tE c PROJECT = - SITE r S. MTM �l. r 4� .I S. Tr" VICINITY MAP Figure 1: Vicinity Map Panther Lake Elementary School TIR 1 otak k:\proity 13l lM\'41147:i\RepoA24\TiR\TL�m.doc Section I —Project Overview Continued Existing Conditions - The site is the location of an existing school, originally built in the 1960's, the north wing of the school was added in 1967. The site consists of the existing school and associated out -buildings; it also contains a parking lot, playground, and playfield. There are two separate threshold discharge areas onsite, which flow east and west before joining together approximately 0.8 miles downstream of the site, a location within the Hylebos Wetland Park, which is located south of the site. The existing east and -west basin sections in the. Offshe Analysis section of this TIR will address the tributary roof areas. East Basin: j The east basin is composed of a portion of the north parking and drive lane around the J east side of the building, grassy open spaces, non -pollution generating rooftops, sidewalks and paved playgrounds. Exhibit 2b is included in this section, and shows the existing land cover for the east basin. West Basin: The west basin is comprised of non -pollution generating rooftops and sidewalks in addition to three parking lots. The southern parking lot discharges directly without any flow control or water quality 1 treatment. The middle bus drop-off parking lot, built in 2003, passes through a pair of Stormfilter catch basins then through a twin 72" diameter CMP by 45 L.F. flow control tank before discharging west to a catch basin in 1st Avenue. The north parking -� lot is free draining to 1st Avenue South -without treatment. See Figure 2b for existing west basin areas. A left tarn lane will be added to 1st Avenue South. No turn lane exists in the existing condition. The proposed frontage improvements consist of curb, gutter, planter strip, and sidewalk. See Figure 2c for offsite improvement areas. Panther Lake Elementary School TIR 2 otak K:1prpl:rti}I1QOV 1137�\Anpunsii`Iit\'I'rxt.d<:c Section I —Project. Overview Continued Proposed Site Drainage Characteristics West Basin: The proposed west basin development consists of parking Iots, landscaping, and a. portion of the proposed roof area. There is an existing flow control facility located underneath the existing parking lot, which will continue to mitigate storm -water runoff from the 0.17 acres of PGIS that currently flow to it. An additional flow control facility will be required for this basin because the proposed impervious areas result in a net increase of greater than 5,000 square feet when. compared to the existing impervious areas within, the threshold discharge area. See Figure 2a for developed basin exhibit, and Section 4 for flow control calculations,. A 54" underground detention pipe will be used to mitigate stormwater from the proposed west basin. It will be, preceded by a CDS pretreatment catch basin and a 8- foot by 16-foot Stormfilter water quality vault with 26 cartridges- The water quality facility is required for this basin because the project exceeds the existing PGIS area threshold by more than the 5,000 SF for the threshold discharge area (see Figure 2a for details). East Basin: The east basin is comprised of areas which include the proposed school; shared access drive, play area, and existing grass field. A flow control facility will not be required for this basin because the proposed impervious areas do not result in a net increase of greater than 5,000 square feet when compared to the existing impervious areas within the basin, See Figure 2a for developed basin exhibit and Section 4 for flow control calculations. A water quality facility will be provided for this basin because the project exceeds the existing PGIS area threshold by more than 5,000 SF for the east basin threshold discharge area. The -water quality facility will be shared and thus sized in conjunction with offsite flows from the adjacent King County Library improvement project. Panther Lake Elementary School TIP. 6tak,, K;\projea111 I CG\i I I+f7>�\Repnrrs�'I'IN\l'rxr.dat Section I —Project Overview Continued The water quality facility willconsist of an 8-foot by 18-foot Stormfilter vault. A CDS pretreatment catch basin will precede the Stormfilter water quality vault, and thus meet pretreatment requirements. A flow splitter will be used to only enable the 2-year storm event from. the King 1 County Library System. (KCLS) site to flow to the shared water quality vault. Storm J events exceeding the 2-year event will bypass the water quality vault and disperse north l in the east corner of the site (see Appendix B.2 for flow splitter design information). } Offsite Improvements: A left turn lane will be added at the south entrance site entrance along 1st Avenue South. The addition of a left turn lane requires the roadway to be widened between the middle and south entrances. There is a high point at the south entrance (see point A in Figure 2c), which diverts stormvaater to two distinct threshold discharge areas, one to 1 the north and another to the south. .Approximately 2143 SF of impervious surface will be added to the south drainage basin, and 2822 SF of impervious will be added to the north drainage basin. Existing catch basins along the south frontage improvement basinn will need to be retrofitted with a solid lid. New catch basins will be added along the face of curb of the widened roadway, and will connect to the existing catch basins (see points B and C in Figure 2c). Basis for Stormwater Detention Facility Design _I A detention facility will be utilized to. mitigate stormwater runoff for a threshold discharge area which results in a net increase in impervious surface of 5,000 SF over the J existing basin. Detention facilities will be designed to comply with Level 1 flow control requirements as described in Section 1.2.3 of the 1998 King County Surface Water Drainage Manual (KCSWD1Vl). See Section 4 for flow control design information. 1 Panther Lake Elementary School TIR 4 otak K:\projea\JIILO31147A\Kepoil \VI'IK\Tez1 dm Section 1—Project Overview Continued Basis for Storm Drainage Conveyance Design The storm drainage and conveyance systems have been designed in accordance with the KCSWDM. Core Requirement #4 of the. KCSVMM requires storm drains to convey 25-year storm events without overtopping drainage structures. The pipe system may overtop for runoff events that exceed the 25-year design capacity; provided the 'overflow from a 100-year runoff event does not create or aggravate a severe flooding or erosion problem. See Section 5 for storm. water design information. Site Soil Condition The soils onsite are identified as Everett-Alderwoo:d gravelly sandy loam (EwC), an outwash soil as classified by the National Cooperative Soil Survey, see Figuure 3-Soils Map. The geotechnical investigation findings show that lodgment till make up the onsite soils. See Appendix f7 for Preliminary Geatechnical Report. Panther Lake Elementary School TIR 5 otak K:\panKv.r\3 t 143DiJ 11 aXA\Re�vtrts\'1'fIt\T��.�lor Figure 2a—East and West Developed Basin Area XREFaLESty Ux4re: 5a Rcaay.a-- C47AG450 u7AP-11 z.eaaloa7 Mf-esms AE 17m3ot� I j e s E JMM- THIS PLM LS CAHCEFTU& TlUWHM LOf LAYOUTS AND WPROffUEM SHOWN ARE S REPRESDUATIYE OF WE TYPES OF pEVE "MOR TM tS PROPOSED. &A !H 1JP6T 05E : THEY NAA NOS a EMN OESKNM OR CONSFRIIt.•EEO, K FKAL PERM MAY O1M FRM THIS CORMPT1A L KM THE OE'1ELOPER RESERVES THE PO4 TO W1HC CHANGES AS THE PL+Vt tS FINKAZE0 AND IMPLEMENTED. fit 4cv14 Aiif} ter - • �r Sri !�►t!t +t*P►r'�"r'i -., , • r� f I�y4yt�i+Ai�4f�}�?±!�'riiti!!i!4!`ili��, � , ... • I • I I. Al,}i,T V.v}i!}!. �4fii4i+if�t►. ..f•I I + }'�'+- ■ � � —� ■g}44iii► ,it cif moo �� -�� yi'9k 9IF. GG,*• � f}�; � rrp.d � • �i�ii it4ic ,''' ■ w � +►';+r+a+►��+��� -• I • I . '`t■ ayb6 i+.0 I { ■-'y c �, ' tia'c�{,�, :� yea; �� ,�' ��A r�� ��; • �i� _ _ ' -_�' �. ., ,. L _ h5t k s �sF • rzr'FT. MATAvILti =w. ,.m<t+��� �i IE• s�'/�'�1�' llf �r�i f 1 bpi+ rr ■ii _ , y1Ei 1•°�+i�s }Vs�►Fi/ IA '� tAil� lA�11iiIF' r "11- Y�M �.Y.�: i.i�� J_iri ice,► ismyl' �„I �►A�A► ivy MCA iie7�,9,Gi�,tsF !b! k■a `fi"�.p1t� ii�i - r�a�i.TSS��;1���' ' �r � i t ���it i:�L�li�i ■ • ► '1 L d17S7rfi ArAAMATAVA �f1H;i knTA'rATA r 1 �L �s: W 1 vvL�► MALATA ■Lr AMAUTA tivAMWA7A1 ,3' a, • ►L +'_• �� �. � 1�°F 'I �fl�'k'.b�` rjlcy 17►r'F'!A'iI! AM, l; y 11 1 `���fii.+�li.'�L�I IVAA�.f►►AM J11� :5 I � i.. AMAYAAVA te I I 11 E­1� �a QU) Q I bi CL �o O �p Li W V w Q :2 M w �w i �w 3' n J. r Qfkisud amIdn n ISM Fwo� �MM) ear PAX kZ5 BR7-457T I 'i'��c: Sti P.. , r r• r . . - • ' /aJm n straUan offices: !°ErmeL TR.DkiCR ••�r•sy,;_'- - - �• I _ 31047A.003.001-D .!, }i ik}• .• u _ t, r. r ¢p . ..y-. Fe&%J11 Feamo W-Y, INAAv98pFS.3 Pr*Cre H0. r� 'I� -_ :y - � '+ _ a.-:r �+ .r='_-�' �� •'a�- •` y= ` +{ . _ a aa;wi�116EiGScfloois Ft�vnr- (25J7s45-2uc10 FIGURE L c n. C3 CWi NEl7u ry 'N._, - - ,�_:�„� 'f.. �'o'�" "' e,N. _ i -- _ _, CALL BEFORE YOU D16 rMM M1rr1 sheet M i, 2 of 3 Figure 2b —East and West Existing Basin .Area LA-1. 50 ft.W"d 24602100i C47AT7s1 0 -TR-W IAS BSt4B •S01 E F c gz 7 E $M- THIS PLAN 5 CONCEP'TEIAL BUILDINGS, LOT ! LAYOUTS AND IMPRONUENTS SFM ARE REPRESENTATIVE OF THE TYPES OF DEVELOPMENT THAT IS PROPOSED, B111 IN UOSI CASES, THEY NAVE NOT PEEN DESIGNED OR CONSTAUCTED. THE FINk PLAN MAY DIFFER FROM THIS CONCEPTUAL PLAN, THE DEMDPER RESERVES THE RW TO MAKE CHANGES 5 AS THE PLAN IS FI14M AND IMPLEMENTED. s L Z-22 4 .0 E511' NORTH — BASIN SOUL BASI IC ;14 ; IE-245.Ei lC-h4,�,Ru 2.2 sc }5A7. 3s i LEGEND ° . t NORIl1 BASH FRONTAGE IMPROVEMENTS t i - SOUTH BASIN FRONTAGE IMPROVEMENTS f� •'>>, - WATERSHED BOUNDARY J\ If( !F r � J !^r. ,71 For Review Only Preliminaryii �V) In LLJ f� U OOf O O a I J O O 2 CU �4 z �+z W F2� w 1�I W LLLI O Lid W� QLLJ V) �Z LL r li P=4 a O r 50' 0. 50, 100' 0 HORIZONTAL SCALE I:I F£Er IncaX'j70rd to I irm NE F.I.Is Vem we a 1Rrla►ea, TlanldejRm "M Mac m) 67-44i9 FIL 4a IiR7'-1'577 10Wra& IRTTAtokm Adminlstto(ion aif!ces: 3104703QQI Lys 31405 - 15th ANe. S. PLI�G� � PMd (253Way, 4 -2MO FIGURE 2c Pnalec (253J945-7000 CALL BEFURE YOtI DIG /htisuoacsusTAnaa'ru; Sheaf Ne. ,—,,-424-5555 r,nsat.a+ra► +rrreuaa�vr sree( 3 aT 3 Figure 2d —Roof Drainage Areas This page left intentionally blank for double -sided printing. Ltsaah• IM R _anted Y 047AT731 o-Ta-asr�a WAS C47AT240 TnJIL r a plla ploy 1rta-6,0av9r FRAlAEiDLR I I I � m \ ri made C— — — — --- — — — — — — -- 3 :-w W W w `\ �04 \\\ is • W �\ FD I - - =w wSR ROOF AREA TO WM MASSM } ROOF QuNspvIt r' 1 • r lip" sr I TO rAST +. RJRW I TO� � f ,Ef] ; i h ROOF AREA , To W7 i5,3W SF � �• RpOF ARFA lI i I ppgpi U Ld �� �V) In O o 4 t40 O a isLLJ LLI �Ld Z w �1 For Review Only W Q Preliminary - W Y o II w2L of "9-01I Ip � I 1 20, 20' 4U' 14MONTAI SCrArE IN FEET lam 8lrouts 6im%Ma K@Hr'v8. 1mhmervx cause Pbaac (425) 5*-" FAL 1 4, BYI-GSr7 iotvoel: YIIfAk�COY Adrrlinialrvtivn vFficee: 31047A.L1i13.D91.DS 31405 - }Slh " 1 Fedrral wq, wA s900a Project Nv. t'ubl�G $C3'1d015 phaaar (2W)945-2mnFIGURE ZC ML BEFORE YOU D1G r vaaw+lsc rls twe n Ju; shear NO. 1-800•-424-5555 J400MMUM Xummwishfal v! 3 J Figure 3—Soils Map N x•sw: . �L 4Y _ L • a Yip^ �f •J �i-y� � :Y' � � r • � may. a• . � f'ST �' 1 GY}i A E s s lip 91HAVE S ^9 ,s, •.� o _j Sail Map- King County Area, Washington PANTHER LAKE SCHOOL - FEDERAL WAY., WA Map Unit Legend KitA Co,Urlit Area, washi- Nlap.ilnitySyTnbal.. A9g; rAlderwoodgravellysandyloam,. ] 0 to 6 .percent slopes AgC Alderwood gravelly sandy loam, 6 to 15 percent slopes i AgD Alderwood gravelly sandy loam, 1 15 to 30 petcenl slopes V gh Bellingham silt loam t Evg _ ' Everett gravelly sandy loam, 0 ] to 5 percent slopes fwC Everett-Alderwood gravelly sandy loams, 6 to 15 percent ' slopes InC Indianola loamy tine sand, 4 to l 15 percent slopes No _ Norma sandy loam ,.. F8k Seattle muck- SM ' Shalcar muck Water — il—Aws for Area of Interest (AOI) VA . • ... ''• -� - PercQnt o Adl 16.9 6.6% 14.3 ' 5.6%° 0.31 i 0.1 2.7 18.9 7.4% 176.3 68.8% 0.1 % 0.3 6.0% 7.1 ° 2.8% 1,6 0.6% -- - - 1.0% 2.5 256.1 : 100.0% USDA Nature! Resources Web Soil Survey 2.0 — M W2008 Conservation Service National Cooperative Sol] Survey Page 3 of 3 Section Two i Section 2—Conditions and Requirements Summary Compliance with Project Drainage Requirements ' The KCSWDM specifies eight core requirements and five special requirements for projects in King County. The projecvspecific requirements relating to stormwater are _ listed below. KCSWDM Core Requirements 1, Discharge at the Natural. Location: Natural points of discharge will be maintained for bath the east and wrest basins. Stormwater runoff from the west basin will continue to discharge to the existing storm drain system at 1" Avenue South, following onsite detention and water quality treatment as required by the 1998 King County Surface Water Design Manual. 1 Stormwater runoff from the east basin will discharge at two locations. A flow splitter will direct flow exceeding the water quality Flow from. the KCLS detention system to a dispersion trench_ The trench will allow the runoff to .infiltrate through a perforated pipe. Runoff that does not infiltrate will disperse along the length of the trench, prior to leaving the site. The second discharge - location is an infiltration trench along the eastern fence line, The trenches are located as close to existing flow paths as conditions will allow. dater quality treatment will be provided within this basin, as required by the 1998 KCSWDM. Stormwater runoff from the offsite improvement areas will continue to flow along their natural drainage courses. The high point at the south entrance will be maintained and will not divert. flow to or from the north and south basins. More information is provided in Section 4—Flow Control and Water Quality Facility Analysis and Design. Panther Lake Elementary School TIR 6 otak K:\�ml��\-;11LY3U 11i7A\Re�ai�slTIiC\Texi,dx J Section 2--Conditions and Requirements Summary Continued Z Offsite Analysis:. Provided in Section 3—Offsite Analysis, 3, Flow Control: Provided in Section 4—Flow, Control and Water Quality Facility Analysis and Design.. 4. Conveyance System: Provided in Section 5—Conveyance System Analysis and Design. 5. Erosion and Sediment Control: Provided in Section 8—Construction Stormwater Pollution and Prevention Plan (CSWPPP) Analyisis and Design. 6. Operations and Maintenance- Provided in. Section 10-0perations: and Maintenance Manual. 7. Financial Guarantees and Liability: Provided in Section 9-Bond Quantity Worksheet, Facility Summaries and Declaration of Covenant. 8. Water. Quality: Provided in Section 4—Flow Control and Water Quality Facility Analysis and Design. KCSWDM Special Requirements 1. Other Adopted Area. -Specific Requirements, No area -specific requirements Have been adopted for the Panther Lake Elementary TIR, 2. Flood Hazard Area Delineation: The limits of this project do not lie in a 100- year floodplain. 3. Flood Protection Facilities: Not applicable. 4. Sotirce Controls: Anticipated activities of the Panther Lake Elementary School site have been reviewed. The Activity Worksheet and applicable BMP Activity sheets are .included as Appendix BA. P4nther Lake Elementary School TIR 7 otak 14.;\prQjrc:\31 f 40`} I I�l7r\\LS6purts\'i'I ll1'! ex�.cipc Section 2—Conditions and Requirements Summary Continued 5. oil Control The Panther Lake Elementary School site will serve approximately five buses per day and is not classified js "high-use"x therefore, oil Control from the ugh -Use menu is riot required. Farathgr Lg%e £leragn.tgry $c&»al TTA 8 otak k:lpro�ec4�11 L3D�S1�AiAlRrpun+l'19N�'I'tYti.J�.r Section Three MI Section 3—Offsite Analysis Upstream Basin — West Basin No stormvvrater runoff from adjacent parcels within the west basin, or public right-of- way flows onto our site. Upstream Basin — East Basin The outfall from the KCLS site currently discharges onto a corner of the school site, located near the east property line. This runoff appears to sheet flow across the corner of the school site, discharging to the adjacent property to the east. The 2-year storm event from the detention facility at the adjacent KCLS site will be routed to a shared Stormfilter water quality vault located on the school site, and outfall to a perforated pipe dispersion trench located upstream of the east property line. The 100-year discharge from the KCLS site is 3.185 CFS and the 2-year discharge is 0.583 CFS. See Appendix B,2 in Section 4 for details. Downstream Analysis Existing Conditions - West Basin The school site has two distinct drainage basins, dividing the site in the east and west directions. The west side of the site consists mostly of an existing parking lot, landscaping, and a portion of the roof (see west basin roof drainage section below). A portion of the north parking lot sheet flows to onsite Stormfilter catch basins and. is conveyed to a 72" detention pipe facility located under the existing north parking lot. The outlet for the underground detention pipe discharges to a catch basin located i-within I" Avenue South (see points A and B in Figure 4b). The remaining flow from this basin sheet flows out to 1' Avenue South and is - conveyed north approximately 300 feet in a .1.2" CMP to a catch basin at the intersection of the Winco shopping center- access drive and lu Avenue South (see point JB in Figure 4b). Flow continues west 46 feet in a 30" CMP to another catch basin (see point C in Figure 4b). This catch basin structure has a 24" concrete overflow pipe which flows northwest to an existing detention pond. The outlet for the existing J detention pond is located approximately 425 .feet west of the inlet (see point D in Figure 4b). The outlet pipe discharges southeasterly in a 12" LCPE pipe approximately _1 .Panther Lake Elementary School TIR -I KAprofeaV 1 I00\3 I I47MR"m\TMTe.,tA,., 9 otak Section 3—Offsite Analysis Continued 230 feet to an existing concrete vault (see point E in Figure 4b). A 36" LCPE pipe conveys flow south underneath the Winco parking lot to a point which is a quarter of a mile downstream of our site. The 36" LCPE pipe continues south, to a culvert located underneath SW Campus Blvd, and discharges to a drainage channel which flows south to West Hylebos Creek. West Hylebos Creek continues to flow south though Hylebos Wetland Parr, to a distance one mile downstream of the school site. No existing or potential drainage problems were observed during the site visit. No potential overtopping or scouring were observed along the drainage course. No drainage complaints have been reported for properties that lie within the drainage course that extends one mile downstream of the school site. Existing Conditions - West Basin Roof Drainage A roof downspout study was conducted on October 6"' and 7th 2009 by Flowhawks, to determine how the existing roof is draining, and to which basin the various roof sections drain. As-builts from the existing school are provided in appendix B.3 for both the 1960 construction, and the 1967 north wing addition. Four points are defined in the roof drain study, points A, B, C and R Points A, B, and C are defined in the plans for the. 1967 addition, and appear to convey flow to the east basin. Points A and B describe downspout locations, and Point C describes a catch basin which is part of the same roof drain system, downstream of downspout B. Point D is defined. in the plans for the phase built in 1960, and appears to convey flow to the west basin. Point D describes a cleanout which is connected to a line running west under the school, also serving the two roof drains in line with it. The portion of existing roof area which is tributary to the west basin was determined by a roof drainage study conducted by Flohawks on October 6`' and 7"' 2009, Flowhawks study defines points A, B, and C in the plans for the 1967 addition, and D for the 1960 construction. It appears that downspout A and cleanout D and the roof drain lines they connect to, flow to the west basin. The following describes the findings of the investigation conducted. by Flowhawks and an e-mail is included in Appendix B.3 that describes it. Point D is a cleanout that appear to have been broken Panther Lake Elementary School TIR 10 otak k:\pwj mk\J I100\ 31147A\Repom\TIMTesi.da Section 3—Offsite Analysis Continued and.filled with concrete. Drawings show it to be connected to a line running west, under the school, also serving the two roof drains in line with it. Flowhawks l attempted to feed a camera down the two roof drains, .but could not get past bends in I the pipe. This outfall of this line, if per drawings is unknown. Considering the Flowhawks findings, we are making the determination the roof drainage tributary to downspout A, cleanout D, and the roof drain lines they connect to, flows to the west basin. The tributary area to the roof drain line which includes cleanout D has been determined to consist of the portion of the school that was constructed in 1960, which consists of the original school., minus the 1967 addition. (See Figure 2b west basin delineation). The tributary area to the roof drain line which includes downspout A has also been determined to drain west, although the outfall for the roof drain line could not be located. Any stormwater discharging north from this location would most likely drain west, and is not shown to connect to any conveyance system going east. The roof area tributary to this roof drain system consists of the north half of the 1967 addition, as shown in the 1967 plans included in appendix B,3 (See Figure 2b west basin 1 delineation). Existing Conditions - East Basin An 8-inch perforated pipe conveys a portion of the roof runoff (see East Basin Roof Drainage section below), as well as a portion of the parking and drive lane, to an outfall located at the east property line. (See Figure 2b for pipe location). The remaining areas of the east basin generally sheet flow east across the site flowing to a forested area, and non -jurisdictional wetland located adjacent to the site (see point Ain Figure 4a). Runoff from the site continues to sheet flow southeasterly, approximately 1100 feet to south 348"' street (see point B in Figure 4a). Stormwater from this point passes under JSouth 348`" Street via a culvert, and flows to West Hylebos Creek, which flows 1`4 mile downstream of our site to a point located within Hylebos Wetland Park. Hylebos Creep flows through Hylebos Wetland Park to a distance one mile downstream of our site. No potential overtopping or scouring were observed along the drainage course. Panther Lake Elementary School TIR 11 otak K: \prnprn \J 11 CO\] 179 YA Vt epnrts\T7 €tiTcsr,dce Section 3—Offsite Analysis Continued Existing Conditions - East Basin Roof Drainage As discussed above, roof downspout study was conducted on October 601 and 7`h, 2008 by Flowhawks, to determine how the existing roof .is draining, and to which. basin, the various roof sections drain. The portion of existing roof area which is tributary to the east basin was determined by a roof drainage study conducted by Flohawks on October 6`t' and 7", 2008 Flowhawks study defines points A, B, and C in the plans For the 1967 addition, and D for the 1960 construction. The following describes the findings of the investigation conducted by Flowhawks and an e-mail is included in Appendix_ B.3 that describes it. "Downspout A is shown on the drawings to connect to the same lines as the other downspouts along the north face of the 1967 wing, On the 6`E', Flowhawks tried locating two of the storm pipes for that system, but .ran into clogs less than 20-feet in, On the 7"' they returned with a jetter and attempted to clear the lines, including the cleanout, without success. A search of the woods to the north revealed no obvious outfall, even when water was pumped into the line." "Drawings show downspout B's line running into the same system as CB "C", which was filled with rock., dirt; and vegetation, partially covering the pipe within. The CB to the north of C, also on. the same line, was injected with water without any running into C. The perforated pipe designation on the drawings could account for this. The directions of the pipes seen in the catch basins seem to be in conformance with the drawings and the direction of the calculated (not located) outfall shown on the attached survey." Considering the Flowhawks findings we are retaking the determination the roof drainage tributary to downspout B, and the roof drain line it connects to, flows to the east basin. It is shown in the 1967 plans that tributary flow to downspout B is conveyed in an 8-inch perforated pipe, downstream .to a catch basin labeled point C, A catch basin north of point C conveys a portion of the parking and drive lane to point C, although no flow was .seen at point C when water was injected into the line. It is believed that the water that was injected into the line infiltrated within the perforated pipe. The 84nch outfall pipe was not able to be located at the east property line, but it is noted the directions of the pipes were shown to be in conformance with the Panther Lake Llernentary School TIR FAPWjW\'� I I W%.) I 1 #7R\Reports\T[R\Teri. &), 1'2 otak Section 3---Offsite Analysis Continued 1 drawings, so we assume the pipe is there. The tributary area to the roof drain line which includes downspout B has been determined to consist of the southern half of the roof of the 1967 addition. (See Figure 2b for pipe location, and east basin delineation). The remaining areas of the east basin generally sheet flow east across the site flowing into a non -jurisdictional wetland located adjacent to the site (see Figure 2b for details). Existing Conditions — Offsite Improvements No downstream analysis is required for the south offsite improvement area. The south frontage improvement basin meets the criteria established under the 1998 KCSVDi'A,_ as being exempt from meeting core requirement #2. The south drainage basin adds less than 5000 SF of new impervious area, does not modify a drainage pipe/ditch that is 12- inches or more in size/depth or that receives runoff from a drainage pipe/ditch that is 12-inches or more in size/depth and does not contain or lie adjacent to a SAO defined landslide, steep slope, or erosion hazard area. The natural point of discharge for the north offsite drainage basin is the same as the west onsite drainage basin. The downstream for this basin is covered in the west basin downstream analysis. Developed Conditions - West Basin Peak flows from the developed west basin will be mitigated with the use of a proposed underground detention pipe, preceded by a pretreatment and water quality facility. Runoff from the west basin will continue to discharge to the existing conveyance system located within 1" Avenue South. Developed Conditions - East Basin Runoff :from the developed area of the east basin of our site, as well as the 2-year storm event flow from the KCLS site will be conveyed to a shared 8-foot by 18-foot Stormfilter water quality vault, before outfalling to an infiltration trench located upstream of the east property line. The shared water quality facility will he sized for the 2-year release from the detention system for the adjacent KCLS site, and 60% of the developed 2-year storm event from our developed east basin. Panther Lake Elementary School TIT 13 otak jI K:\prnjecr�_?11G6\J,11�7A\Kepors�PiK\'I'rxi.dac Section 3—Offsite Analysis Continued A flow splitter will be used to only enalrle the 2-year storm event from the IKCLS site to flow to the shared water quality vault (see Appendix B.2 for floor splitter design information). Storm events exceeding the 2-year event will bypass the water quality vault and discharge to a dispersion trench. The trench will allow the runoff to infiltrate along a perforated pipe. Runoff that does not infiltrate will then disperse along the trench toward the east property line. The grass play€ield and open space area at the southeast basin will continue to sheet flow onto the adjacent parcel, and non -jurisdictional wetland, continuing south along the existing drainage course. Drainage Complaints There are no drainage complaints on file which .demonstrate drainage problems within a distance one -mile downstream of our site, Pafither Lake Elemenlary School TIR KApmjm\3I10\3114?A\RegontlTQt\Te,,t.da 14 otak Figure 4a—East Downstream Exhibit East Basin Do ��,,-�•�- ��:�. �rr�' �,r' _ __..,.., ..� wnstream Exhibit ��• i 'ANTHER LAKE J , £I.E1dENTARY � `' -. , � . -�, ��--r.. � "•�� J�' __ � ram• •� ..S � � n �i M' SsA. n � ;r F � .!•'•�. - , 1', ram• � � • �^ �M1lII ''� ! , •' rf C WES 09 Ter -- 32 -�, r ._. ;r -'� ':.k},�• - j � pip � �,.�' eta 825 '�'�..-t � � � .�' ' �f 'ter•. � , � � ! �.• • �...,;c. a� ' r. jFigure 4b—West Downstream Exhibit J West Basin Downstream Exhibit E -P. 0771 ER LAKE ELEMENTARY -171 HD 78 � LA KEWb OD iic, Coif( ry 11 ADD 71r i z�6 ft Y4'M,x� 71 23 4632 M,24 Figure 5a —West offsite Drainage Table a GO «1 E✓Q J r N a Q. G ►t, r t rj, :< � 1 77 1 dz `u a CL a� a a � r �= y `- S .. o 6c 2 v �' �' �, ° O co G vO .ice O O O rOn O cn LLJ d p O O O O O ° O z O z z X. z Q O O i L° rC YF+ �L.<I X 3 K YoN U >-.t -+ a 4 o u i-+ GS, `�• G a q„) L♦.. a 21 4, P. 4d111 oAP< a—,K y }-1 C] o �. F o �� x o o o Lri d d 4- -- o ter: o R o Q •d 'G D d c d 4 t 'C7 lt.f. CO O bo 0 Q) wC"fir W � r+- O �� Y N r� �� 1I c m o p� N 79 � -00 E d am o o o r Q a o o �'' o 7 M 10, + o � o ci o o G o w . � w F7 rd rites C% w fi rf] f 4Q) aIRDI P its W o CJ U UJ U p7 U N a N F v V A4 .--1 a t*l Lt. l�1 Q Q-i ►'� M �/ U 1'Y 77j V CIO Figure 5b —East Offs ite Drainage Table I �l w W R E a �a a rema _r. 0 � t: am 3 ,� CL o C4 C/O U! E w �1 4) C pl n V 0 4 ik a a m0 Z. .n E' r f� C 4 — Ca 0 . ID C. D O O rJ O z IZ z a du G 0 v) r� � "+ J3 70J -+\ P, ? yCL n1 Q CD kn Ff� Mnrs tli rn y -'o ul too m� c ( F to pl� �4 j CN'3_am m r- tp C) �d 45 O � UZh�a UEC rn rtj N th -i Section Four 1 Section 4—Flow Control and Water Quality Facility Analysis and Design West Basin: The proposed impervious area of the west basin is 2.00 acres, whereas the existing impervious area is 1.83 acres. A flow control facility will be required for this basin because the proposed impervious areas result in a- net increase of greater than 5,000 square feet when compared to the existing impervious areas within the threslold discharge area basin as established under section 1.2.3 of the.1998 KCSWDM. 7,973 SF of new and/or replaced pollution generating surfaces are being added to the west basin. Water quality will be required for this basin because the PGIS areas have increased by more than the 5000 SF threshold as established under section 1.2.8 of the 1998 KCSWDM. An 8-foot by 16-foot Stormfilter vault with 26 cartridges will be provided to treat 60% of the developed 2-year storm event for the west basin. KCRTS was used to calculate runoff, using a 15-m1nute time steps,, See the existing and developed west basin land cover tables below for details. Land Cover — West Basin Existing Conditions see Figure 2b Impervious NPGIS = 1.23 acres Impervious PGIS = 0.60 acres Forest (till) = 0.15 acres Bypass (till forest) = 0.63 acres Grass (till) = 0.12 acres Developed Conditions (see Figure 2a) Impervious NPGIS (roof) = 0.45 acres Impervious PGIS = 1.43 acres Grass (till) = 0.22 acres Bypass (till forest) — 0.58 acres Bypass (impervious) = 0.12 acres Land Cover — West Basin Offsite Improvements Existinz Conditions (see Fieure 2b Impervious NPGIS = 0.00 acres Impervious PGIS = 0,00 acres Forest (till) = 0.06 acres Grass (till) = 0.00 acres Developed Conditions (see Fieure 2a Impervious NPGIS = 0.00 acres Impervious PGIS = 0.06 acres Forest (till) = 0.00 acres Grass (till) = 0.00 acres Panther Lake Elementary School TTR 15 Uotak K;\projaii IOJ131;a 7A\Rex i„\7731\. I'e:ci,dnc _1 Section 4---Flow Control and Water Quality Facility Analysis and Design Continued The onsite detention facility was oversized to account for the onsite and offshe improvement areas that will bypass the detention facility. A point of compliance was set up, matching the 2 and 10-year peak flows from the developed site to the pre - developed site, given a portion of the west basin is being bypassed, see the point of compliance time series areas below. Land Cover —West Basin Pre -developed Basin (predev_w) Pre-Develoved Conditions (see Figure 2b Impervious NPGIS = 1.17 acres Impervious PGIS = 0.60 acres Forest (till) = 0.15 acres Bypass (forest) = 0.63 acres .Grass (till) = 0.12 acres NPGIS (offsite ROW) = 0.06 acres Land Cover — West Basin to Flow Control Facility (rdin_w) Deyeloped Conditions (see Figure 2a) JImpervious NPGIS = 0.45 acres Impervious PGIS = 1.43 acres - Forest (till) = 0.00 acres Grass (till) = 0.22 acres Land Cover — West Basin Bypass area (bypass_w) Developed Conditions see Figure 2a --j Impervious NPGIS = 0.06 acres Impervious PGIS = 0.00 acres Forest (till) = 0.58 acres Grass (till) = 0.00 acres NPGIS (offsite ROW) = 0.06 acres 1 Panther Lake Elementary School TIR 16 oW k KAprcyccr\3I109\3I147A\1kr[.)tu\1'fft\'1car. oc 1 1I I Section 4—Flow Control and Water Quality Facility Analysis and Design Continued 'Water quality facilities have been designed to meet standards of the Resource Stream Protection Water Quality Menu, the site is located in a Resource Stream Protection, Treatment area, as defined by the City of Federal Way Water Quality Applications Map. An 8-foot by 16-foot stormfilter vault preceded by a pretreatment facility will be used upstream of our proposed flow control facility. The stormfilter vault will use CSF leaf media to satisfy the Resource Stream Protection Treatment. Detailed analysis and supporting calculations are provided in Appendices A.1, A.2, and A.3. The existing north parking lot currently flows to two Stormfilter catch basins followed by a 72-inch detention pipe with sediment storage, The current basin area for this facility is 0.17 acres. The existing tributary basin for these facilities will be maintained in the developed condition. The two existing Stormfilter catch basins will be relocated to match the proposed curb. See sheet C4,10 for storm drain layout and Appendix A.4 for previous parking lot design by David Evans and Associates. A portion of the proposed roof area has been directed to the west basin to limit the increase in new impervious area to the east basin to under 5,000 SF, as allowed udder section 1.2.3 of the 1998 KCSWDM, See Figure 2d for proposed roof drainage area exhibit, and the west basin land cover table in this section for details. East Basin: Water quality and pre-treatment facilities will be required for the east basin because the new, and/or replaced onsite PGIS areas have increased by 10,133 SF, which is greater than the 55000 SF threshold established under section 1.2.8 of the 1998 KCSWDM. A Stormfilter media'water quality vault have been sized to treat the combination of 60% of the developed 2-year peak flows from the developed east basin, plus the 2-year release rate from the KCLS detention facility. The Stormfilter vault will use CSF leaf media to satisfy the Resource Stream. Protection Threshold. Panther Lake Elementary School TIR 17 otak F.:lpivjrrr1S11001! I1�17A\Repacis\,'!'!k\Tr..i.ilgc: _ Section 4—Flow Control and Water Quality Facility Analysis and Design Continued i Flows from the KCLS site consist of discharge from their existing onsite detention. facility, and a slight increase in discharge due to the proposed parking and access drive. j The detention discharge calculations from the library can be seen in Appendix B.2 and show a 2-year discharge of 0,583 CFS and a 100-year discharge of 3.185 CFS. KCRTS was used to calculate developed site runoff, using 15-minute time steps. The water quality facility will be shared with the adjacent. KCLS site, and will consist of an 8-foot by 18-foot Stormfilter vault. The discharge rates from the developed east basin consist of 0.174 CFS for the 2-year storm event. A flow splitter will be used to only enable the 2-year storm event from the KCLS site to flow to the shared water quality vault. Storm events exceeding the 2-year event will bypass the water quality vault and disperse north of the shared outfall. Detailed water quality analysis and supporting calculations are provided in Appendix B.1, flow splitter design information is provided in Appendix B,2, A flow control facility will not be required for the east drainage basin, because the proposed impervious areas add 4,605 SF, which is less than the 5,000 SF threshold when compared to the existing impervious areas within the basin as established Larder section 1.2.3 of the 1998 KCSWDM, Sec the east basin land cover tables below for details. _ A portion of the proposed school roof area has been directed to the east basin to achieve an increase in new impervious area, -which is close to the allowable impervious area increase of 5,000 SF within the east basin, See Figure 2d for roof area basin 1 delineation. The entire proposed roof area could not be directed to one specific basin. Rather, some of the proposed downspouts had to go to the east basin and sonic to the _ l ';vest basin in order to keep the total existing and developed areas for each basin as equal as possible. See the east basin land cover areas below for details. J Panther Lake Elementary School TIR 18 otak K:\pmjgoV I IOOUl:g7:1\Rrp++nx1TIR\Text.+ku Section 4—Flow Control and Water Quality Land Cover — East Basin Existing Conditions (see Fieure 2b Impervious NPGIS = 1.05 acres Impervious PGIS = 0.38 acres Forest (till) = 3,53 acres Grass (till) = 3.36 acres Facility Analysis and Design Continued Develo. Conditions see Figure 2a Impervious NPGIS = 0.65 acres Impervious (roof) = 0,68 acres Impervious PGIS = 0.20 acres Forest (till) = 1.65 acres Grass (till) = 5.05 acres The total site area is broken down into the following sub basins as follows. - Land Cover — East Basin Pre -developed Existing Conditions (see Rzo3re 2b IrtmFervious NPGIS = 1,05 acres Impervious PGIS = 0.38 acres Forest (till) = 3.53 acres Grass (till) = 3.36 acres Land Cover — Last Basin to Water Quality Facility Developed Conditions see Figure 2a Impervious = 0.28 acres Forest (till) 0.56 acres Grass (till) = 0.49 acres Land Cover — East Basin to Shared Qutfall Developed Conditions (see Fieure 2a Impervious N-PGIS = 0.58 acres Impervious PGIS = 0.20 acres Impervious (roof) = 0.68 acres Forest (till) = 0.56 acres Grass (till). =: 1.11 acres Panther Lake Elementary School TIR R;SprojSi:r\�11�J11f Ld7A\Rrpatn\TjR\'Trsi for 19 otak r� I Section 4—Flow Control and Water Quality Facility Analysis and Design Continued Land Cover — East Basin Bypass Area Develooed Conditions (see Figure 2a Impervious NPGIS 0.07 acres Impervious PGIS = 0.00 acres Forest (till) = 1.09 acres Grass (till) = 3.94 acres Offsite Improvements: Offsite frontage improvements are proposed along the west property line. A flow control facility will not be required for the south drainage basin, because the proposed impervious areas add less than 5,000 square feet when compared to the existing impervious areas within the basin as established under section 1.2.3 of the 1998 KCSWDM. The south basin is its own threshold discharge area, because it's shortest flow path does not combine with any other site flows within 1/4 mile downstream of our site. Land Cover — Offsite Improvements (South Basin) F;aistine Conditions (see Figure 2c 'Impervious NPGIS = 0,00 acres Impervious PGIS = 0.00 acres Forest (till) = 0.05 acres Grass (till) = 0.00 acres Develooed Conditions (see Figure 2c Impervious NPGIS. = 0.00 acres Impervious PGIS 0.05 acres Forest (till) = 0.00 acres Grass (till) = 0.00 acres _1 Runoff from the north basin of the proposed offsite improvements discharges to the + same catch basin along r Avenue South, as the vest basin of the proposed onsite development (point D in Figure 2c). Flow combines with onsite flow within 1/4 mile downstream of our site, and thus will be considered as part of the onsite drainage basin. The proposed west basin detention facility has been oversized to account for the ` undetained/untreated runoff from the north basin frontage improvements. _J Panther Lake Elementary School TIR 24 owk OprojegV1146\-11117A\Aapons\T1XVr& Ax Section 4—Flow Control and Water Quality Land Cover — Offske Improvements (North Basin) Existing Conditions see Figure 20 Impervious NPGIS — 0.00 acres Impervious PGIS = 0.00 acres Forest (till) = 0.06 acres Grass (till) = 0.00 acres Hydrology Facility Analysis and Design Continued Develo ed Conditions see Figure 2c Impervious NPGIS 0.00 acres Impervious PGIS = 0.06 acres Forest (till) = 0.00 acres Grass (till) = 0.00 acres The water quality and detention requirements for the. flow control facility are based on drainage area characteristics. For the purposes of determining hand cover for calculation of flow control and water quality facility sizing, three different land covers are used, till, forest, till grass, and impervious. The existing site areas were delineated based: on current land cover characteristics. The. existing site was developed prior to May 1979, thus the existing land cover areas were delineated and considered the pre -development condition. See Figure 2b for details. The developed site is a mixture of impervious areas, such as roadway, and roof area. All landscaping is considered till grass. See Figure 2a for details. KCRTS, using one -hour time steps, and the reduced time series, was used to calculate runoff rates for the west basin detention facility sizing. KCRTS, using 15-minute time steps, and. the .reduced time series, was used to calculate runoff rates for ons' water quality facility sizing, as all water quality facilities are located: prior to detention facilities, as required in section 6.2 of the 1998 KCSVrDM. KCRTS Input files for the west basin flow control facility are located in Appendix A.1., KCRTS flow control facility sizing output is located in Appendix A,2. West basin and east basin water quality calculations are located in Appendices A.3 and B.1 respectfully. Panther Lake Elementary School TIR K:1pmjmt\ 3laOA31147A\ .Repo ru\1TMTcu,duc 21 atak Appendix A. I — West Basin KCRTS Input Files KCRTS INPUT FILE: WEST BASIN KCRTS Program ... File Director}r: C:\1e,'C SWDM\I,C DATA\ [C] CREATE a new Time .Series ST 0.77 0.00 0.000000 Till Forest 0.00 0.00 0.000000 Till Pasture 0.12 0.00 0.000000 Till Grass 0.00 0.00 0.000000 Oumvash Forest 0.00 0.00 0.000000 Outwash Pasture 0.00 0.00 0,000000 Outwash Grass 0.00 0.00 0.000000 Wetland 1.38 0.00 0.000000 Impervious predev�_w.tsf T 1.00000 T [C] CREATE a ne-w Tirne Series ST 0.00 0.00 0.000000 Till Forest 0.00 0.00 0.000000 Till, Pasture 0.22 O:OU 0.000000 Till Grass 0.00 0.00 0.000000 Outwash Forest 0.00 0.00 0.000000 Outwash Pasture 0.00 0.00 0.000000 Outwash Grass 0.00 0.00 0.000000 Wetland 1A3 0.00 0,000000 Imperious, rdin w.tsf 1.00000 T [Cj CREATE a rivvy Time Series ST 0.58 0.00 0.000000 Till Forest 0.00 0.00 0.000000 Till Pastore 0.00 0.00 0,000000 Till Grass 0.00 0.00 0.000000 Oumvash Forest 0.00 :0.00 0,000000 Outwash Pasture 0.00 0.00 0.000000 Outwash Grass 0.00 0.00 0.000000 Wetland 0..12 0,00 0.000000 Impervious bypasses. tsf T 1.00000 T Appendix A.2— West Basin Flow Control Calculations Retention/Detehtion Facility Type of Facility: Tank Diameters Tank Lengths Effective Storage Depth: Stage 0 Elevation: Storage Volume: Riser Read: Riser Diameter: Number of orifices: Detention Tank 4.50 ft 128.00 ft 3 _50 ft 0.50 ft 1699. cu. ft 4.00 ft 1B.00 inches 1 Full Head Pipe - Orifice # Height Diameter Discharge Diameter (ft) (in) (CF8) (in) 1 0.00 2.23 0.270 Tog Notch Weir: .None Outflow Rating Curve: None Stage Elevation Storage Discharge Percolation (ft) (ft) (cu. ft) (ac-ft) (cfs) (cfs) 0.00 0.50 0. 04000 0.060 0.00 0,02: 0.52 0. 0.000 0.021 0.00 0.0.5 0.55 Q. 0.0.00 0.029 0.00 0.07 0.57 0_ 0.000 0.036 0.00 0.09 0.59 0. 0.000 0.041 0.00 0,12 0..62 0. 01000 0.046 0.00 0.14 0.64 0. 0.000 0.050 0..00 0.16 0.66 0. 0.000 0.054 0.00 0.19 0.69 0_ 0.000 0.05S 0.00 0.29 0.79 0. 0.000 0.072 0.00. 0.39 0.89 0. 0.000 0.084 0;00 0.49 0.99 Q. 0.000 0.094 0.00 0.50 1.00 0. 0.0.00 0.095 0.00 0.60 1.10 49. 0.001 0.104 0.00 0.70 1.20 99. 0.002 0.113: 0.00 0.80 1.30 151. 0.003 0.121 0.00 0.90 1.40 203. 0.905 0.126 0.00 1.00 1.50 257. 0.006 0.135 0.00 1.10 1.60 312. 0.007 0.141 0.00 1.20 1.70 367, 0.008 0,149 0.00 1.30 1.80 424_ 0.010 0.154 0.00 1.40 1.90 480, 0.011 0,160 0.00 1.50 2.00 537. 0.012 0.165 0.00 1.60 2-10 595. 0.014 0.171 0.00 1.7.0 2.20 652. 0,015 0.178 0.00 1.80 2.30 710, 0.016 0.181 0.00 1.90 2.40 767. 0.0.18 0.186 0.00 2.00 2.50 825. 0.019 0.191 0.00 2.10 2.60 B82. 0.020 0.195 0.00 2.20 2.70 939. 0.022 0.200 0.00 2.30 2.80 995. 0.023 0.205 0.00 2.40 2.90 1050. 0.024 0.209 0.00 2.50 3.00 1105. 0.025 0.213 0.00 2.60 3.10 1159. 0.027 0.217 0.00 2-70 3.20 1212. 0.028 0.222 0-00 2.80 3.30 12.63. 0.029 0.226 0.00 2.90 3.40 1313. 0.030 0.230 0-00 3.00 3.50 1362. 0.031 0.214 0.00 3.10 3.60 1409. 0.032 0.237 0.00 3.20 3.70 1454. 0.033 0.241 O.00 3.30 3.80 1497. 0.034 0,245 0.00 3.40 3.90 1538. 0.035 0,249 0.00 3.50 4.00 1575. 0.036 0.252 0.00 3.60 4.10 1610. 0.037 0.256 0.00 3.70 4.20 1641. 0.038 0.255 0.00 3.80 4.30 1667. 0:038 0.263 0.00 3.90 4.40 1688. 0,039 0.266 0.00 4.00 4.50 1699. 0.039 0.270 0.00 4.10 4.60 1699. 0.039 0.735 0.00 4,20 4.70 1699. 0.039 1.580 0.00 4.30 4.80 1699. 0.039 2.680 0.00 4.40 4.90 1699. 0.039 3.980 0.00 4.50 5.00 1699, 0.039 5.450 0.00 4.60 5.10 1699. 0.039 6,880 0.00 4.70 5.20 1699. 0.039 7.410 0.00 4,B0 5-30 1699. 0.039 7.910 0.00 4.90 5.40 1699. 0.039 8.370 0.00 5.00 5.50 1699. 0.039 8.810 0.00 5.10 5.60 1699. 0.039 9.230 01.00 5.20 5.70 1699. 0.039 9.630 0.00 5.30 5.80 1699, 0.039 10.010 0.00 5.40 5.90 1699. 0,039 10.380 0.00 5.50 6.00 1699. 0.039 10.740 0.00 5.60 6.10 .1699. 0.039 11.080 0.00 5.70 6.20 1699. 0.039 11.420 0.00 5.80 6.30 1699. 0.039 11.740 0.00 5.90 6.40 1699. 0.039 12.060 0.00 6.00 6.50 1699. 0.039 12.360 0.00 Hyd Inflow Outflow Peak Storage Stage Elev (Cu-Ft) (Ac-Et) 1 0.72 .0,69 4.09 4.59 1699. 0.039 2 0.44 0.43 4.03 .4..53 1699. 0.029 3 0.52 0.38 4-02 4.52 1699. 0.039 4 0.39 0.40 4.03 4.53 1699, 0.039 5 0,43 0.38 4.02 4.52 1699. 0.039 6 0.37 0.33 4.01 4.51 1699. 0.039 7 0.32 0.20 2.14 2.64 906, 0.021 B 0.36 0.20 2.23 2.73 953. 0.022 Hyd R/D Facility Tributary Reservoir POC Outflow Outflow Inflow Inflow Target Calc 1 0.69 0.10 ******** ******* 0.79 2 0.43 0.08 **** *** ******* 0,48 3 0.382 0.05 ******** 0.44 0.43 4 0.4.0 0.06 ******** ******* 0.45 5 0..38 0.04 ******** ******* 0..40 6 0.33 0.06 ******** 0.38 0.38 7 0.20 0.03 ******** ******* 0.22 8 0.20 0.03 ******** ******* 0.21 ---------------------------------- Route Time Series through Facility Inflow Time Series File:rdin_w.tsf Outflow Time Series File:rdout_w POC Time. Series Fi:le;dsout w Inflow/Outflow Analysis Peak Inflow Discharge: 0.722 CFS at Peak Outflow Discharge: 0.695 CFS at Peak Reservoir Stage: 4.09 Ft Peak Reservoir Elev: 4.59 Ft Peak Reservoir storage: 1699. Cu-F.t 0.039 Ac-Ft Add mime Series:bypass w.tsf 6;00 on Jan 9 in Year 8 6:00 on Jan 9 in Year 8 Peak Summed Discharge: 0,793 CPS at 6:00 on Jan 9 in Year 8 Point of Compliance File:dsout_w.tsf Flow Frequency Analysis Time Series File:rdout_w.tsf Project Loaation:Sea-Tac ---Annual Peak Flow Rates --- Flow Rate Rank Time of Peak (CFS) 0.329 6 2/09/.01 4:00 0.197 8 1/05/02 .17:00 0.427 2 2/27/03 8:00 0.201 7 8/26/04 3.00 0.379• 5 10/28/04 18:00 0.395 3 1/18/06 16:00 0.379 4 11/24/06 4:00 0.695 1 1/09/08 6:00 Computed Peaks Flow Frequency Analysis Time Series File:dsout_w.tsf Project Location:Sea-Tac ---Annual Peak Flow Rates --- Flow Rate Rank Time of Peak (CFS) 0.378 6 2/09/01 4:00 0.217 7 1/05/02 17:00 Flow Frequency Analysis------- - - Peaks - - Rank. Return Prob (CFS) (ft) Period 0.695 4.09 1 100.00 0.990 0.427 4.03 2 25.00 0.960 0.395 4.03 3 10.00 0.900 0.379 4,02 4 5.00 0.800 0.379 4.02 5 3.00 0.667 0.329 4.01 6 2100 0..500 0.201 2.22 7 .1.30 0.231 0.197 2.14 8 1.10 0.091 0.606 4.07 50.00 0.980 Flow Frequency Analysis------- - Peakg - - Rank Return Prob (CFS) Period 0.793 1 100.06 0.99.0 0.480 2 25.00 0.960 0.480 2 2/27/03 .8:00 0.452 3 10.00 0.900 0.214 8 8/26/04 3:00 0.430 4 5.00 0.800 0.402 5 10/28/04 18:00 0.402 5 3.00 0.667 0.452 3 -1/18/06 16:00 0.3.78 6 2.00 0.500 0.430 4 11/24/06 4:00 0.217 7 1.30 0.231 "I 0.793 1 1/09/08. 6:00 0.214 8 1.10 0..091 Computed Peaks 0.688 50.00 0.980 Flow Duration from Time Series File:rdout_w,tsf Cutoff Count Frequency CDF Exceedence_Prob4bility CFS $ % 0.006 53162 86.69E 86.696 13.304 0.133E+00 0.018 3372 5.499 92.195 7.805 0.780E-01 0.030 1394 2.273 94.468 5.532 0.553E-01 0.042 825 1.34.5 95.814 4.186 0.419E-01 i 0.054 589 0.961 96-774 3.226 0.323E-01 0.066 341 0.556 97,330 2.670 0.267E-01 0.078 237 0.386 97.717 2.283 0.22SE-01 0.090 148 0.241 97.958 2.042 0.20.4E-01 0.102 462 0.753 :98.712 1.288 0.129E-01. 0.114 190 0.310 99.022 0.978 0.978E-02 0.126 154 0,251 99.2.73 0.727 0.727E-02 0,138 108 0.176 99.449 0.551 0.551E-02 0.150 61 0.0.99 99.548 0.452 0.452E-02 0.162 65 0.106 99.654 0.346 0.346E-02 0.174 49 0.080 99.734 0.266 0.266E-02 0.186 35 0.057 59.791 0.209 0.209E-02 0.198 36 0.059 99_850 0.150 0.150E-02 0.210 31 0.051 99.901 0.099 0.995E-03 tt 0.222 14 0.023 59.923 0.077 0.766E-03 0.234 13 0.021 99.945 0.055 0.5543-03 0.246 8 0.013 99.958 0.042 0.424E-03 0.25B 8 0.013 99.971 0.029 0.294E-03 0.270 5 0.008 99.979 0.021 0.21`2E-03 0.282 2 0.003 99.982 0.018 0.179E-03 0.294 0 0.000 99.982 0.01E 0.179E-03 i 0.306 1 0.002 99.984 0.016 0.163E-03 -.f 0.318 1 0.002 99.985 0.019 0,147E-03 0.330 2 0.003 99.989 0.011 0.114E-03 0.342 1 0.002 99,990 0-010 0.978E-04 11 0.354 1 0.002 99.992 0.008 0.815E-01 _1 0.366 0 0.000 99,992 0.008 0.815E-04 �+ 0.378 1 0.002 99.993 0.007 0.652E-04 0.390 2 0.003 99.997 0.003 0.32.5.E-04 -+ 0.402 1 0.002 99.998 0.002 0.163E-04 0.414 0 0.000 99.998 0.002 0.163E-04 D 0.000 99.499 0.002 0.163E-04 J0.426 Flow Duration from Time Series File:dsout w,tsf Cutoff count Frequency CDF Exceedence_Probability CFS W W 0.007 52727 85.987 85.981 14.013 0.140E+00 J 0.020 3603 5.876 91.862 8.138 0.814E-01 0.034 1532 2.498 94.361 5.639 0.564E-01 0.047 890 1.451 95.812 4.188 0-419E-01 0.061 602 0.982 96.794 3.206 0.321E-01 0.074 357 0.582 97.376 2.624 0.262E-01 0.088 221 0.360 97.736 2.264 0.226E=01 0.101 174 0,284 98.020 1.980 0.19BE-0.1 0.115 426 0.695 98.715. 1.285 0..129E-01 0-128 216 0.352 99.067 0.933 0.933E-02 0.142 139 0.227 99.294 0.706 0.706E-02 0.155 102 0.166 99.460 0,540 0.540E-02 0.169 65 0.106 99.566 0.434 0.434E-02 0.182 59 0.096 99.662 0.338 0.33&E-02 0.196 45 0.073 99.716 0.264 0,264E-02 .0.209 42. 0.068 99.804 0.196 0.196E-02 0.223 31 0.051 99.855 0.145 0.145E-02 0.236 15 0.024 99.879 0.121 0.121E-02 0.249 21 0.034 99.924 0..086 0.864E-03 0.263 8 0.013 99.927 0.073 0.734E-03 0.276 1.6 0.026 99.953 0.047 0.473E-03 0.290 6 0.010 99..962 0.038 0.375E-03 0.303 7 0.011 99.974 0.026 0.2.61E-03 0.317 3 0.005 99.979 0.021 0.212E-03 0.330, 3 0.005 99.984 0,016 0.163.E-03 0,344 0 0.000 99.984 0.016 0.163E-03 0-357 1 0.002 99.985 0.015 0.147E-03 0.371 1 0,002 99.9B7 0.013 0.130E-03 0.384 2 0.003 99,990 0.010 0.978E-04 0.3.98 1 0.002 99.992 0.008 0.815E-04 0.411 1 0.002 .99.993 0.007 0.652E-04 0.425 1 0.002 99.995 0.005 0.489E-C4 0.438 1 0.002 99;997 0.003 0.326E-04 0.452 0 0.000 99.997 0.003 0.326E-04 0.465 1 0,002 99,998 0.002 0,1.63E-04 0.479 0 0.000 99.99B 0.002 0.163E-04 Duration Comparison Anaylsi5 Base File: predev w_tsf New File: dsout_w.tef Cutoff Units. Discharge in tF5 -----Fraction of Time ----- ---------Check of Tolerance------- CutoffBase New *Change Probability Ease New %Change 0.187 0.30E-02 0.30E-02 0.0 0.30E-02 0.187 0.187 0.0 0.212 0.22E-02 0,19E-02 -13.6 I 0.22E-02 0.212 0.204 -3.6 0.236 f 0.16E-02 0.12E-02 -22.9 0.16.E-02 0.2.36 0.220 -6.8 0.260 0.11E-02 0.75E-03 --30,3 0.11E-02 0.2.60 0.242 -7.0 0.285 OA E-03 0.44E-03 --34.1 I 0.67E-03 0.285 0.267 -6.3 0.309 1 0.52E-03 0.23E 03 -56.3 0.52E-03 0.309 0.274 -11.3 0.333 I 0.36E--03 0.16E-03 -54.5 I 0.36E-03 0.333 0.293 -12.2 0.357 0.28E-03 0.1.5E-03. -47.1 j 0.2BE-03 0,357 0.298 -16.6 0.382 + 0.15E-03 0.98F-04 -33.3 0.15E-03 0.382 0.364 -4.6 0.406 j 0:.82E-04 0.65E-04 -20.0 0,82E-04 0.406 0.402 -0.9 _1 i J 0.430 0.65E-04 0.49E-04 -25.0 0.65E-04 0.430 0.419 -2.6 0.455 0.16E-04 0.16E-04 0.0 0.16E-04 0.455 0.480 5.5 0.479 0.16E-04 0.16E-04 0.0 0.16E-04 0.479 0.480 0.2 0.503 0.16E-04 0.00E+00 -100.0 0.16E-04 0.503 0.480 -4.7 Maximum positive excursion = 0.036 cfs ( 8.2t) occurring at 0.443 cfs on.the Base Data:predeY_w.tsf and at 0.480 cfs. on the New Data:dsout w.tsf Maximum negative excursion = .0.060 cfs (-16.7%) occurring at 0.358 cfsan. the Base Data:predev_w.tsf and at 0.298 cfs on the New Data :dsrntt w.tsf Route Time Series through Facility Inflow Time Series File:rdinrw.tsf outflow Time Series File:rdaut w POC Time Series File:dscut w Inflow/Outflow Analysis Peak Inflow Discharge: 0.722 CFS at 6:00 on Jan 9. in Year 8 Peak Outflow Discharge: 0.69E cps at 6:00 on Jan 9 in Year 9 Peak Reservoir Stage: 4.09 Ft Peak Reservoir Elev: 4.59 Ft Peak Reservoir Storage: 1699. Cu-Ft 0.039 Ac-Ft Add Time Series:bypass_w_tsf peak Summed Discharge: 0.793 CFS at 6:00 on Jan 9 in Year 8 Point of Compliance File:dsout_w_tsf Flow Frequency Analysis Time Series File:rdout w.tsf Project Location:Sea-Tac ---Annual Peak Flow RateS--- Flow Rate Rank Time of Peak (CFS) 0.32.9 6 2109/01 4:00 0.197 8 1/05/02 11:00 0.427 2 2/27/03 8:00 0.201 -7 8/26/04 3:00 0.379 5 1.0/28/04 18:00 0.395 3 1/18/06. 16:00 0.379 4 11/24/06 4:00 0.695 1 1/05/08 6:00 Computed Peaks Flaw Frequency Analysis Time Series File:dsout_w.tsf Project Location:Sea-Tac ---Annual Peak Flow Rates--- ,Flow Rate Rank Time - of Peak ----Flow Frequency Analysis - Peaks - - Rank Return Prob (CFS) (ft) Period 0.695 4.09 1 100.0U 0.990 0.427 4.03 2 25.00 0.960 0.395 4.03 3 10.00 0.900 0.379 4.02 4 5.00 0.800 0.379 4.02 5 3.00 0.667 0.329 4.01 6 2.00 0.500 0.201 2.22 7 1.30 0.231 0.197 2.14 8 1.10 0.091 0.606 4.01 50.00 0.980 -----Flow Frequency Analysis-- ­ Peaks - Rank Return Prob (CPS) (CPS) Period 0.379 6 2/09/01 4:00 0.793 1 100.00 0.990 0,217 7 1/05/02 17:00 0.480 2 25.00 0.960 0.480 2 2/27/03 6:00 0.452 3 10.00 0.900 0.214 8 8/26/04 3:00 0,430 4 5.00 0.600 0.402 5 10/28/04 18:00 0,402 5 3.:00 0.667 0.452 3 1118106 16:00 0.378 6 2.00 0,500 0.430 4 11/24/06 4:OD 0.217 7 1.30 0,231 0.793 1 1/09/08 6:00 0.214 8 1.10 0.091 Computed Peaks 0.688 50.00 0.980 Flaw Duration from Time Series File:rdout_w.tsf Cutoff Count Frequency CDF Exceedence_Probability CFS 0.006 53162 86.696 86.696 13.304 0.133E+00 0.018 3372 5.499 92,195 7.805 0.780E-01 0.030 1394 2.273 94,468 5.532 0.553E-01 0.042 825 1.345 95.814 4.186 0.419E-01 0.054 589 0.961 96.774 3.226 0.323E-01 0.066 34.1 0.556 97.330 2.670 0.267E-01 0.078 237 0.386 97.717 2,283 0.228E-01 0.090 148 0.241 97.958 2.042 0..204E-01 0.102 462. 0.753 98.712 1.288 0.129E-01 0.114 190 0.310 59.022 0.978 0.97&E-02 0.126 154 0.251 99,273. 0.727 0.727E-02 0.138 108, 0.176 99.449 0.551 0.551E-02 0.150 61 0.099 99.540 0,452 0.452E-02 0.162 65 0.106 99.654 0.346 0.346E-02 0.174 49 0.080 99.734 0.266 0,266E-02 0.186 35 0.057 99.791 0.209 0.209E-02 0.198 36 0.059 99.850 0.1150 0.150E-02 0.210 31 0.051 99.901 0.099 0,995E-03 0.222. 14 0.023 99.923 0,077 0.765E-03 0.234 13 0.021 99.9.45 0.055 0.554E-03 0.24.6 8 0.013 99.958 0.042 0.424E-03 0.258 8 0.013 99.971 0.029 0.294E-03 0.270 5 0.008 99.979 0.021 0.212E-03 0.282 2 0.003 99.982 0.018 0,179E-03 0.294 0 0.000 99,982 0.018 0.179E-03 0.306 1 0.002 99,984 0.016 0.163E-03 0.318 1 0.002 99.985 0.015 0.147E-03 0.330 2 0.003 99=989 DA 1.1 0.114E-03 0.342 1 0.002 99.990 0.010 0.978E-04 0.354 1 0.002 99.992 0.008 0,815E-04 0.366 0 0.000 99.9.92 0.008 0..815E-04 0.378 1 0.002 99.993 0.007 0.652E-04 0.390 2 0.003 99.997 0.003 0.326E-04 0,402 1 0.002 99.998 0.002 0.163E-04 0.414 0 0.000 99.998 0.002 0.163E-04 0.426 0 0.000 99.998 0.002 0.163E.-04 Flow Duration from Time. Series File.dsout w.tsf Cutoff Count Frequency CIF Exceedence Probability CPS 0.007 52727 85.987 85.987 14.013 0.140E+00 0.020 3603 5.876 91.862 8.138 0.814E-01 0.034 1532 2.498 94.361 5.639 0.564E--01 0.047 890 1.451 95.812 4.188 0.419E-01 0.061 602, 0.982• 96.794 3.206 0.321E-01 ] 0.074 357 0.582: 97.376 2.624 0.262E-01 _ 0.088 221 0.360 97.736 2.264 0.226E-01 0.101 174 0.284 98.020 1.980 0.198E-01 l J 0.115 426 0.695 98.715 1.285 0.129E-01 0.128 216 0.352 99.067 0.933 0.933E-02 0.142 139 0.227 99.294 0.706 0.706E-02 0.155 102 0.166 99.460 0.540 0.540E-02 0..169 65 0.106 99.566 0.434 •0.434E-02 0.182 59 0.096 99.662 0.338 0.338E-02 0.196 45 0.073 99.736 0.264 0.264E-02 0.209 42 0.068 99.804 0.196 0.196E-02 0.223 31 0.051 99.855 0.145 0.145E-02 0.236 15 0.024 99.879 0.121 0.121E-02 0.249 21 0.034 99.914 0.086 0.864E-03 0.263 B 0.013 99.927 0.073 0.734E-03 0.276 16 0.026 99.953 0.047 0.473E-03 0.290 6 0.010 99.962 0.038 0.375E-03 0.303 7 0.011 99.974 0.026 0.261E-03 0.3111 3 6.005 99.979 0.021 0.212E-03 0.330 3 0.005 99.984 0.016 0.163E-03 0.344 0 0.000 9.9.984 0.016 0.163E-03 0.357 1 0.002 99.985 0.015 0.14.7E-03 0.371 1 0.002 99.987 0.013 0.130E-03 0.364 2 0.003 99.990 0.010 0.978B-04 0.390 1 0.002 99.992 0.008 0.615E-04 0.411 1 0.002 99.993 0_007 0.652E-04 0.425 1 0.002 99.995 0.0.05 0.489E-04 0.438 1 0.002 99..997 0.003 0.32GE-04 0.452 0 0.000 99.997 0.003 0.32.6E-04 { 0.4-65 1 0.002 99.998. 0.002 0..163E-04 -� 0.479 0 0.000 99.998 0.002 0.163E-04 I J Appendix A.3— West Basin Water Quality Calculations ►`R:r i W STORMWATER SOt.IJTiONs iNc: Prepared by J Reidy on November 25, 2008 Size and Cost Estimate Panther Lake Elementary School West — Stormwater Treatment System Federal Way, WA Information provided: • Total contributing area = 1.65 acre ■ Impervious area = 1.43 acre • Water quality flow, 0,kg = 0.409 cfs • Peak hydraulic flow rate, Opeat,= 1.90 cfs • Presiding agency = City of Federal Way Assumptions: • Media = CSF cartridges • Cartridge Height = 18" • Flow rate per cartridge = 7.5 gpm • Drop required from inlet to outlet = 2.3' minimum Size and cost estimates: The StormFllter is a flow -based system, and therefore, is sized by calculating the peak water quality flow rate associated with the design storm. The water quality flow rate was calculated by using KCRTS and provided to CONTECH Stormwater Solutions Inc. Th, 6tormFilter for this site was sized based on a water quality flow rate of 0.409 cfs. To accommodate this flow rate, CONTECH Stormwater Solutions recommends using an 8'x16' StormFilter with 26 cartridges (see attached detail). The estimated cost of this system is _$54,000 - $63,000, complete and delivered to the job site. This estimate assumes that the vault is 6 feet deep. The final system cost will depend on the actual depth of the units and whether extras are specified. The contractor is responsible for setting the StormFilter and all external plumbing. Typically the precast StormFilters have internal bypass capacities of 1.8 cfs. If the peak discharge off the site is expected to exceed this rate, we recommend placing a high -flow bypass upstream of the StormFilter system. CONTECH Stormwater Solutions could provide our high -flow bypass, the StormGate, which provides a combination weir -orifice control structure to limit the flow to the StormFilter, The estimated cost of this structure is $4,000. The final cost would depend on the actual depth and size of the unit. ©2006 CONTECH Stormwater solutions 12021-6 NE Airport Way, Portland OR 97220 Page 1 of 1 corttechstormWater.com Tall-free:800.548.4667 Fax.80.0.561.1271 TS-P027 wCI—wes topks F1ow Frequency Analysis Time Series File:wq west_no_fp.tsf Project Location:5ea-Tac --annual Peak Flaw €gates --- Flow Rate Rank Time of Peak (CFS) 0.681 6 8/27/01 18:00 0.476 6 9/17/02 17:45 1.34 2 12/08/02 17:15 0.548 7 8/23/04 14:30 0.735 .5 10/28/04 16:00 0.776 4 10/27/05 10:45 0.932 3 10/25/06'22:45 1.80 1 1/09/08 .6:30 computed peaks -----Flaw Frequency Analysis-------- - - Peaks - - Rank Return Prob CCFS) Period, 1.80 1 100.00 0.990 1.34 2 25.00 0.960 0.932 3 10.00 0.900 0.776 4 5.00 0.800 0.735 5 3.00 0.667 0.681 6 2.00 0.5.00 0.548 7 1.30 0.231 0.476 8 1.10 0.091 1.65 50.00 .0.98D Page 1 Appendix A.4— West Basin Existing Park Area VICINITY MAP FEDERAL WAY SCHOOL DISTRICT BID PACKAGE - B PANTHER LAKE ELEMENTARY SCHOOL BUS SEPARATION PROJECT 34424 FIRST AVENUE SOUTH FEDERAL WAY, WA 98003 CONTACTS FEDERAY. WAY SCHOOL DISTRICT t210 1066 SOUTH 320TH STREET FEDERAL WAY, WA 98003 (2m 945-5930 P DAVID EVA14S AND ASSOCIATES, INC. DAN SCAMPORLINA, L.A. 3700 PACIFIC HIGHWAY FAST, 51C 311 TACOlMA, WA 08424 (253) 922-97.99 CIVIL ENGINEER DAVID EV'ANS AND ASSOCIATES INC. DONALD BERGSTROM, P.E. 37D0 PACIFIC HICHWAY EAST, SE 31T TACOMA. WA 94424 (253) 922-9780 SURVEYOR SADLER BARNARD & ASSOCIATES 12714 VALLEY AVENUE EAST SUMNER, VIA 98390 (233) 826--5130 ELECTRICAL ENGINEER ABACUS £NGINEEREO SYSYEWS 401 2NO AVE S. SUITE 201 (SEATTLE. WA 03104 2.9.6) SB:1-0200 INDEX OF DRAWINGS Cl COVER SHEET C2 GENERAL NOTES AND LEGEND C3 DEMOLITION, T.E.S.C. PLAN AND DETAILS C4 GRADING, PAVING AND DRAINAGE C5 STRIPING AND SIGNAGE C6 DETAILS C7 DETAILS C8 DETAILS S1 TOPOGRAPHICAL SURVEY 32 TOPOGRAPHICAL SURVEY Ll IRRIGATION PLAN L2 LANDSCAPE PLAN L3 IRRIGATION AND LANDSCAPE DETAILS E1 ELECTRICAL SITE PLAN S � 5 r� _ SITE i t,nln 1Y. UZI IN Sr s 34RTTI sr 1 uAI'J[f[c. 1 REQUIRED _. _ � ,y� Ol1tY7! WORK W l ..' C Eieeva7 �- .. Ue ,,,• � ,4i a�9'��;•1' - 78E AV�,� � -� r�;yr.;:a., � �.�' �'., -.-T„ �_y fF ".^'-•..f� � �« - - ]r• '^-' "-^� �}� ~- 'f - �,.ti �:.._ - - `'-w_ �L.,�. Ate= �� v' � r �- f �:I. -^:sE� r �y�: _ J� srxe .asea�, r �• !"^ na �ir.'���� �- �'Y•---�bf.. _ taw - f.. ; { � 1` __ �:=:: 1 _.�.:r�- � ,• ..- - _- ._ - -- _ L' ..��-�� •�; wu.... .� .'� .,_ "_• � �,. _-i to l.i a! r in Tr, D' ' E LEGAL DESCRIPTION THE NW OTR Or THE Nw Om Or 711E SW OTR OF SEC 20. TWP 21N RANGE 4E WM. KING SOUNTY WA. LAX PARCEL No, 202104-9110 BENCH MARK CITY OF FEDERAL WAY BENCH MARK NO ZIM-67-1 NCVD-29 TOP OF CASED MONUMENT LOCATED AT THE INTERSECTION OF FIRST AVENUE SWI14 AND SOUTHWEST MOTH STREET, ELEVATION ZOOM? SITE BENCH MARK TOP WEST BOLT OF HYDRANT LOCATED AT THE SOUTH END OF SCHOOL AS SHOWN. ELEVATION 271.97 BASIS OF BELL GS: WEST CAMPUS BUSINESS PARK AS RECORDEO IN VOLUME 97 AT PAGL 78-82. RECORDS OF KING COUNTY, WASIiINGTON. SURVEY NOTES EYJ$TING CONTOURS STORM SEWER, SANITARY SEWER ANO OTHER SURFACE FEATURES WERE PRONDED BV SADLER. BARNARD AND ASSOCIATES, DAM EVANS AND ASSOLTATES, WC HAS NOT VERIFIED UNDERGROUND OR SURFACE FEATURES. SITE PLAN PLANS REVIEWED FOR UALITY ASSURANCE BY: eA s� to 01 SAL PERMIT No CITY OF FEDERAL WAY MPAO150 6Y � COVER SHEET _! W86 U �Q w _j co ❑d� d Ir c� o ~Z�° m Q W CLw° J w REVT91oNS=-all'O- LArr URNlCN: Ploue nHAWN. Gin c"CKsDN REVISION NUNTNL'R SCALY -AS SHOWN PROJECT NUAiOER: FW800M "HEST NCL Up 8 C1 A GENERAL NOIES• 1, ALL CONSTRUCTION SMALL BE IN ACCORDANCE WITH THE FEDERAL WAY CITY CODE (FWCC). APPLICABLE ORDINANCES, AND THE CITY COUNCIL CONDITIONS OF PROJECT APPROVAL THESE DOCUMENTS ARE SOPPLEMENTED BY 111E STANDARD SPECIFICATIONS FOR ROAD. BRIDGE, AHD MUNICIPAL CONSTRUCTION (WSOOT/APWA), WE KING COUNTY ROAD STANDARDS (kCRS), AND TFIE RING COUNTY SURFACE RATER DESIGN MANUAL (IUSWDM). T SNAIL BE THE SOLE RESPONSIBRJTY of THE APPLICANT AND THE PROFESSIONAL ENGINEER To CORRECT ANY ERROR. OMISSION. OR VARIATION FROM THE AOOVE REOUIREMERTS FOUND IN THESE PLANS ALL CORRECTIONS SHALL BE AT NO ADDITIONAL COST OR LIABILITY TO THE CITY OF FEDERAL WAY, T, THE DESIGN ELEMENTS 'WITHIN THESE PLANS HAVE BEEN REVIEWED ACCORDING TO THE FEDERAL WAY ENCI)IEERWG REVIEW CHECKLIST. SOME ELEMENTS MAY HAYS BEEN OVERLOOKED OR MISSED BY THE OTT ENGINEERING PUN REVIEW ANY VARIANCE FROM ADOPTED STANDARDS IS NOT ALLOWED UNLESS SPECIFICALLY APPROvo BY THE CITY OF FEDERAL WAY, PRIOR TO CONSTRUDTDN ... APPROVAL OF INS ROAD', GRADING, AND DRAINAGE PLAN DOES NOT CCINSRIUTE AN APPROVAL OF ANY OlWR CONSTRUCTION (I.E. DOMESTIC WATER CONVEYANCE. SEWER CONVEYANEE, GAS, ELECTRICITY. ETU:.) 4. BEFORE ANY CONSTRUCTION OR DEVELOPMENT ACTIVITY, A PRECOHSTRUCTICN MEETING MUST BE HELD BETWEEN THE CITY OF FEDERAL WAY, THE APPLICANT, AND THE APPLICANTS CONSIRUCTION REPRCSENTAtlYE, 5- A COPY OF THESE APPROVED PLANS MUST DE ON THE JIM SITE WHENEVER CONSTRUCTION IS W PROGRESS. N 6, CONSTRUCT" NOSE SHALL BE LIMITED AS PER FWCC (SECTION 22- 1006): NORMALLY THIS IS 7 A.M. TO B F.U. MONDAY THROUGH SATURDAY. E 7. IT SHALL ➢E THE APPLICANT'S/CONTRACTOR$ RESPONSIBILITY 10 OBTAIN I ALL C014STRIJOQN EASEMENTS NECESSARY BEFORE INITIATING OFF -STYE WORK MINK THE ROAD RIGHTS OF WAY IL FRANCHISED UHLITICS OF OTHER INSTALLATIONS THAT ARE NOT SHOWN ON THESE APPROVED PLANS SHALL NOT DE CONSTRUCTED UNLESS AN APPROVED SET OF PLANS THAT MEET ALL CITY REQUMIENTS AND THE RECUIRF.MENTS OF KCRS CHAPTER 8 ARE SUBUITTED 10 THE CITY OF FEDERAL WAY AT LEAST THREE VATS PRIOR TO CONSTRUCTION. 9, VERTICAL DATUM SHALL DE KCAS OR NGVT-29, NIL GROUNDWATER SYSTEM CONSTRUCTION SHALL BE 1WTHII A RICHI OI WAY (IN APPROPRIATE DRAINAGE EASEMENTS, 131JT NOT UNDERNEATH TIIE ROADWAY SECTION ALL GROLINOWATER SYSTEMS MUST UE GONSTRUCRI, IN ACCORDANCE WITH DIE W-sjOT/APWA STANDARD SP.IGITNCATIONS NA, ALL UTILITY TRE14CHES IN THE RIGHT OT WAY SMALL RF NALI(FI.LED YATN 5/8 INCH CRUSHED ROCK AI,L DIIITY UDVUIHES SNAIL DE OA.CMUED AND COMPACTED If1 959. DIN51 TY 13 ALL ROAUWAY SUBGRADE MAIL OE DAUCFT,I.F.D AND COMPACTED FO .y5' f. DENSITY IN ACCORDANCE WITH NTAOT 2-06.3. 14 ❑PCH CUTIINC CC EXISTING ROADWAYS IS iNDT ALLOKD LIALESS S EV1ICALLY APPROVED BY THE PUBLIC WE'RKS OIRF.CTUR A19 NOCIEU UN THESE APPROVED PEANE, ANY OrEN CANT SHALL BE BESTMED IN ACCORDANCE WITH KCRS 8.03(8)1 15. THE CONTRACTOR SHALL BE RE'SPONSIILE TOR PROVIDING AOEDUATE SAFEGUARDS. SAFETY DFWES. PROTECTIVE EQUIPMENT, FIAGGERST AND ANY 07110? NEARED AC11UR5 ILA PROTECT LIFE. HEAL Ri AND SAFETY OF IHE PUBLIC, AND TO PROTECt PT((JpERT'r IN COwcTiON WTH THE PERFORMANCE OF WORK COVERED BY THE CONTRACTOR. ANY WORK WITHIN THE TRAVELCO RIGHT OF WAY THAT UAY INTERRUPT NORMAL TRAFFIC FLOW SHALT RETIRE AT LEAST ONE FLACOER FOR EACH LANE Or TRAFFIC AFFECTED. ALL,. SECTIONS OF TIE V600T STANDARD SPECIPIGATONS 1-07.2.3-TRAFFIC CONTROL, SHALL APPLY. : 16. CONTRACTOR SHALL PROVIDE AND INSTALL ALL REGULATORY AND WARNING SIGNS PER THE LATEST EDITION OF MANUAL ON UNIFORM TRAFFIC CONTROL DEVICES I 17 ALL imumS SHALL BE ADJUSTED TO FINAL GRADE AFTER PAVTNG ASPHALT WFARINC COURSE CITY OF FEDERAL WAY PUBLIC WORKS DEPARTMENT PRECONSTRUCTTON/INSPECTION NOTIFICATION NO. (253) 661-4131 EEEEEEEER05l-QL[f SEDlMEN T8Tl0N CONP N�JT1rS: DRAINAGE I. APPROVAL OF THIS CROSION/SDIMENTATICN CONTROL (ESC) PLAN DOES NOT CONSTITUTE „NOTES: I PROOF OF 1JABATiY TM"A"a SHALL BE SLIBMITTEO TO THE CITY PRIOR AN APPROVAL OF PERMANENT ROAD OR DRAINAGE OESIM IT E. FIE AND LOCATION OF TO TFIE PREI:(IlS1.R)CTHA4 MFETm ROADS, PIPES, RESTRICTORS, CHANNELS, RETENTION FACTURES, UTIUTES, ETC.) I ALL PIPE AND APPURTENANCES SHALL BE LAID ON A PROPERLY �' 111E IMPLEMENTATION OF THESE ESL: PUNS 0.N0 THE CONSTRUCTION, MAINTENANCE, PREPARED FOUNDATION IN ACCORDANCE WITH WSDO7 T-02. J(7). THIS REPLACEMENT, AND UPGRADING OF THESE ESC FACILITIES IS THE RESPONSIBILITY OF THE SHALL I+OIUDE LVVMX MITI MWPACrm THE ITIMi 00FTOM, THE APPUC,1MT/(ATIIRACTOR UNTIL ALL CONSTRUCTION IS APPROVED. TOP M YWrMATM t V41ERIAL. ASO REWREU POPE BEDDING, TO A UNIFORM GRADE SO THAT THE ENTIRE PIPE IS SUPPORTED BY A 3, THE BOUNDARIES Gii TNF CLEARWC LOTS 51NOWN ON THIS PLAN SHALL BE CLEAIgY UNIFORMLY DENSE UNYIELDING BASE, RAGGED IN THE FIELD f"OR TO CRMKTRUCSWN DURING K CONSTRUCTON PERIOD, NO DISTURBANCE BEYOND THE FLAGGED CLEARING LIMITS SHALL BE PERMITTED. TIC RAGGING 3 $ PIPE SHALL BE CALVAODTFD AND HAVE ASPHALT {RFATME?1T %I SHALL BE MAINTARHED BY THE APPLICANT/CONTRACTOR FOR THE DURATION (I' OR 8VTM INSIDE AI/j W isoc C0.NSTCUCTON- a. ALL DRAWAGF STRUCTURES SUM Al CLTCH OAARS AND MAIROLCS, H. THE ESC FACILITIES SHOWN OFF THIS PUN MUST BE CONSTRUCTED IN CONANNCTION MTN NOT LOOTED MDHW A TRAVELED "ADIM► OR 9TOEWAL9, SNMtU HA>IE ALL CLEARING AND GRADING ACNTES, AND IN SUCH A UANNER AS FO INSURE THAT SOLD LODKWG LIDS. ALL DRAINAGE STRUCTURE'S ASSOCIATED WITH A SEDIMENT LADEN WATER DOES NOT ENTER THE DRAINAGE SYSTEM OR VIOUIE APPLICABLE PERMANENT RETENTION,/DETENTION FACFUTY:SHALL HAVE. SOLID LOCKING WATER STANDARDS: LIDS, 5- THE ESC FACILITIES SHOWN ON THIS PLAN ARE THE MITRAUM REOUIREMENTS FOR S. AU_ CATCH BASIN CRATES SHALL CONFORM TO CFW DRAWING W,IMDERS ANTICIPATED SITE CONDITIONS DURING THE CONSTRUCTION PERIOD, THESE ESC FAOUTIE$ 4-1. 2, 3, W OR S SHALL BE UPGRADED (i,E. ADDITIONAL SUMPS, RELOCATION OF PITCHES AND SILT FENCES, ETC) AS NEEDED FOR UFNE%PECTED STORM EVENTSWHERE 7, Rf1CJf FOR EROSION PROTECTION OF PITCNEB, GHANNRS AND SWAL£S, REWIRED. MUST BE OF SOUND QUARRY ROUT PLACED TO A IL G THE ESC FACILITIES SHAft HE IHSPEZR"D DORY DY THE APIR ICANTjCC3NTRACTOk 4NTi DEPTH OF ONE FOOT AND MUST MEET Tic FOLLOWING SPECIFICATIONS MAIN TATTED NECESSARY TO ENSURE THEIR Cl7HONUET FU/ICDONRNC 4--S- ROCK/WX-70% PASSING: 2^-r RGCK/709.• /OR PASSING; AND -2` RDOC/!OX-ZDX PASSING INST'ALLAIION SHALL BE TIN ACLORDATTCE 7. ANY AREA STMPPEO OF V[c-'ETATM, INCLUDNRC ROADWAY EMBANKNEHIS, YSIIERL NO WITH KCRS DRAWTAD NUMBER 51 M 45 AWeaD BY THE APPROVED FMrARR WD" IS ANTICIPATED OR A PERIOD OF 15 DAIS. SHALL BE IWEDIAIEL r PUNS. RECYCLED ASPHALT OR CONCRETE RUBBLE SHALL HOT BE USED, STABII2F-O WITH THE APPROVED ESC ME11HOD5 (I.E S£EENNO, MULCHING. HEFTING. EP.OSION BLANXETS, EYC ) B ANY AREA NEEDING ESC MEASURES, NOT REQUIRING ►fVXDIAIE ATTEN1100. SHALL BE ADDRESSED MOTION 15 DAYS. 9. THE ESC FACILITIES ON INACTIVE SITES SHALL BE INSPECTED AND MAINTAINED A MININUM �7yT rt �+ y7 ■ r CONSTRUCTION SITE AQREAGE OF ONCE A MONTH OR WITHIN THE 48 HOURS FOLLOWING A STORM EVENT APPROX 69,666 SD.fT IA AT 140 TIME SHALL MORE THAN ONE FOOT OF SEUIMENT BE ALLOWED TO ACCUMUL,AT, 'WITHIN A CATUII BASIN, ALL CATCH BASINS AN O £oNVEYANGE LINES SHALL BE gFANL'D T r �p t ��+ NET IM V10V JAREA IN PIOR TO PAVIRG. THE CLEANING OPEPATKW SHALL NOT FLL191 SEDIMENT -LADEN WATER -CREASE INTO THE DOYINSiRENA SYSTIA. Agpggy &RN4 S,T_ (2,3X Of 51YHOOL Slit ) I^ DURING 114E TIME PERIOD OF NOVEMBER I T1HP.OICH MARCH 31. ALI, PROJECT DISTURBED AP RkiNfj STALL ❑ATM AREAS GREATER THAN 5.000 SQUARETHAT FEET. AT ARE LEFT LINIICIRKED FOR MORE. THEN 12 HOURS, SNALL BE COVERED ELY CNE OF 714E FOLLOINR, COVER MEASURES: ULkr.4, r"ti1S11I ' -� -36 P"OSIYIL SOO. OR PLASTIC. COVERING. SFATI %-- .,,,,,,.. 3M PARENT-...--...1C lIANDIRAP--�.--7 13. ANY PERMANENT REIENTION,'DETENTION FALTLITY USED AS A TEMPORARY SCTTLNC B/ti-TIN '�1'U'•'•"�^••^l+•'9S SHALL HE MODSTED WITH THE NECESSARY FROSILM CONTROL MEASLIBES AND SHALL 20 GRAVEL SURFACED PARKING: PHOVgO£ ADEQUATE STORAGE CAPA0IY, IF THE PERMANENT FACILITY 15 TO FUNCIIDN STALLS ARE LOCATED NORM OF' MF- UL IIMATELY AS AN INFOLTRA-IMN OR DISPERSION SYSTEM. THE FACILITY SHALL NOT BE SQXIOOL USED AS A TEAIPORARY5ETTµNG BASIN NO UNDERGROUND DETEN1iON 1ANY,S OR VAULTS BE USED AS A TEMPORARY SETTLING BASMNL SHALLP�BREVfA710NS H. MERE SCEMIIHC FOR TVAPORARY 111010,11 -00flIRLY IS PFOUIRED. PANT :,ERIMAIING STA SRAR GASSES ASSE; MAIL BE APPLIED AT AN APPROPRIATE LAIC (LE., AFI111At GN PEERENN1A.L RYE RT RIGHT APPLIED AT APPROXIMATELY 80 POUNDS PER ACRE) LT LEFT PVA4T PAVEMENT 15. WHERE iMAW i Ui 0..1 FOR IENPCIR.AP,Y EROSION CONTRO IS RfO(YRF.D, IT 51/4L[. BE AN TANGENT APPLIED AT A h9MiMON PFCKNESS. O TWO INCHES. F,X EXISTING R FLOW'UNC 16- MANAGEMENT PRACTICES PROVIDING SIGNIFICANT TREE PROTECTION SHALL BE PROVIDED IIP HiLk POINT OC ON C:NTEFL PER SECTION 22-15E6 (C) (S) (A-G) OF FWCG EW EAC+I Witt ACP ASPHALT tONCRETE PAVEUEINT TYP TYPICAL 1F0 OUTSIDE DIAMETER CA GAUGE C/L CFNTERLIN£ WSOQT WASHOrrGIN STATE DEPAR1417:: OF LTATNSPORTATION ACH AMEFD_^AN COINr� RNSTHUTE ADA AMERIC.41S WITH DISABILITIES ACT DETAIL AND SEC-RON AND RELIQRATIONS F}ETA t CALLULI7 DETAIL NUMBER UTILITY WAR10N1]; I{ THE UNDERGROUND UTILITIES SHOWN HAvf BEEN LOCATED FROtN SHEET NUMBER L'N SHEET NUMBER ON FIELD SURVEY INFORMATION AND EXISRNC DRAWNLS. THE WHICH CALLOUT APPEARS WHICH CETALL APPEARS SURVEYOR MAKES NO GUARANTEE THAT THE UNDERGROUND UTILITIES SHOWN COMPRISE ALL SUCH UTILITIES IN THE AREA EITHER IN SERVICE OR ABANDONED. THE SURVEYOR FURTHER DOES NOT WARRANT THAT THE UNDERGROUI40 UTUTIES SHOWN SECTION CA L O MT -SECTM NUMBER ARE W THE EXACT LOCATION INDICATED ALTHOUGH HE DOES CERTIFY THAT THEY ARE LOCATED AS ACCURATELY AS POSSIBLE A FROM INFORMATION AVAILABLE. THE SURVEYOR HAS NOT PHYSICALLY LOCATED THE UNDERGROUNO UTILITIES. `#HEET NUMBER Ol' V411CH CALIOUT APPEARS SiECT-IMM L44 WHICH *M APPEARS `may CALL BEFORE YOU DIG CaIL• TOLL FREE 1-800-424-5555 ■r114.0 R iF WORKERS ENTER ANY TRENCH OR HOMER IXCAVA TDN FOUR OR LIOM FEET N OEPTH THAT DOES Not MEET THE OPEN FIT REWIRE99NM OF WSTOY SECTION 7-09.A3)B, IT SHALL BE SHORED Alto CRlftCO. THE CONTRACTOR ALOK cHALL BE RESFOMSMLE FOR pYMLR SAFETY AND OCA ASSUMES NO RESPORSIBRITY. ALL TWNCN SAFETY SYSTEMS SI'KI MEEK THE REOUIWWPITS OF THE Wl.SII1ICTON INDUSTRIAL SAFETY ,UNIT HEALTH ACT, CHAPTER 49.A7 RCW. PROJECT SUMMARY THIS IS A BITS SEP,LRATON PRGAECF DNmma TO SEPARATE BU.4, PEDESTRIAN. AND ',EiDCULAR NRAYHC IN W PANONG AND tOADIN0jU NLOADRNC A AEAS WEST OF PANTH�P LARF FIEMENTAPY- SGNOCk LEGEND DOS SING POWER POLE GUY WIRE GAS METER. BOLLARD PLATER VALVE FIRE HYDRANT WATER METER TELEPHONE RISER CAILF BOA' LIGHT MALL BOX SIGN CATCH BASIN DRAIN MH SAMIARY MH MONUMENT AS DESCRIBED REBAR AND CAP IRON PIPE PK NAIL HEDGE CROSSWALK SWOP BAR LAWN -n; GRAVEL CONCRETE CHAIN LINK FENCE - WARE FENCE WOW FENCE — — RIGHT-OF-WAY LINE GRAVEL PARKWG -� CONCRETE SOFWALk eBQEMYF M, ASPHALT CONCRETE RN -OVAL r 7, 73 REMOVE LAWNfCRASS/T'gPCGgI. —-- SILT FENCE - --- REARBRF, LIMNS a CATCH BASIN PRRTEC m i SIGN I^ F = H ASPHALT CONCRETE PAVLNC CONCRETE S'OEWALIC OR [:AD (AS :HOAR) TOP OF CURB kavA RON PAM)AEMT O VAMR TYPE I CATCH BASIN -- SURFACE FLOW FAREC TONAL ARROW --___- SAWUT UK PAINTED HANDICAP SYMDOL --lw PAINTED BIIECIIGNAL ARROW No- -. CITY OF FEDERAL WAY AFFRO" IF OATH GENERAL NOTES AND LEGEND g �. W=� -1co °� Sr W CC 0-i Z 5:0 m < w I� .. J � W RRVISIONS; APPD 0 AT7-• JNAIAR'r ZO,1x UESICN' L'yBE DfLt1[N- :Ar: CFfEClCET: RL1vt5IULr MI}®ER: SCALE: AS SHOWN PRRO`JJEECT NUMBER 1 ►TJDOO14 SLEET NO OF 8 C2 + s 1 1 1 1 . I + m 0 dCHGM Nt►R1i TNpi MESS 3sr,l H MM�OPan1 5f i, OR WIRE RINGS iTYPj I'ILTER FAOK9C MATL-MAL - NIRAIR 1.Op K OR EQUAL r� REMOVE Ei1¢:N STRIPING (rak) s SLMRNARLD CAT0i yAJk CP.ANL wrm ^- 'NOR %givEN FILNENL FABRIC "'0111 1 I "IQ-N4 OR EQUAL) MO 'sxcu E van, YARE / •� H1 15 REY04E-E70611NC WR8 tics 's j AND. SipEIIALK TL7 -iFIE • NEAREST fir 7L5' ` : 3pfY1,y lV7 � ° � �� FIELDED TO INSTALL NEW ArpN ^sIDEwALJc - •� �)"R ( . uUITTS NC- P't / 14J� U1.RT5 TYP: � f3� RE+AOVE N:xlstuNc � DLERo m +BAR - WAIi59011 Joe*, . r— GRATE CATCIH 2" k 2" X 14 GA- SASH •� FA$R+C OR EQUAL ,,� CATCH BASIN N D T lL NO TO CALF [rj 'll 2" X i' DOtJG *!R OR EOIIAL 5' .• f," TkENCH i1LTER FABRIC MATERIAL ,L_ 2' 4 2' X 14 f;A. W.W.F. , �y1' IlATI NOTES- I. PLACE I' OF 3147 -- 1-1 �2' WASHED ROCx OR PEA !' -- I -I 2' WASLIED RUCK � OR PEA GRAYLYjj1. GRAVEL ON BORN SIDES OF FENCE TO CREATE A BEVEL SHAPE. 6" 2 FABRIC SHALL COVER BOTT04 OF 6' k 6' INEHN:IL AND F-xlEND @EYONO THE LUAt TS OF ! TINE GRAVEL tH ORDER TO RAINIA114 AtN tf;CC.SS 2" EXCESS OVERLAP 6� OVERLAP OF 2" EALNIMUNI AS Slio*J IN THE MIN TYPICAL CROSS-SECTION. S[LTAiION FENCE pETAILS IYEICALOSS 5EC Q NOT TO SCALE 1iOY YD SCALE r / N 1 9 E 3(NS 3015 �• I —o X `s PIP) 3 F � �• z 1 DEMOLITION NQIE5 . C� FIAL DEPTH SA%7W 1 2 =1, MACK MDk •-ACE or EKI$lIN CLRO• PROPOSED CURB OR A.; $t" AND REMOVE PAYE1dEN1. C21 REMOVE ERISTONG CONCRETED S"IAL[ AF:D/OR G.RUSFk'.O ROCK BASE j COURSE. j 3� CLEAR AND GRUB ALL AREAS WITHIN CLEARING LIMITS 4 4) 178TdOVE AND DISPOSE OF EK15DNG RAILROAD TIES ADJACENT TO ASPHALT WALK. 1.[FP CEAIPL1CHi AWONiC PSY VHD 535£LL yDIED R MAiM0.L VJNWI2C OATNAGE TO £7OST04ti ASPHALT CONCRETE PAVFSIENT ANO LAVM. RCSTOTE ANY D&VACED AREAS, REMOVE AND DISPOSE CF MTWD aCLLARD5 AMID F0041405. BACK FILL POST HOLES TO 9UAROUIM314C L'ROtiiiD F,'LE'VATHNN. OT 9ETAOVE AND DISPOSE or 004M TWC CHAIR LINK FENCE FABRIC, GATE POSTS, FOOTIHDS, A O ACCESSOL M BACK ru PAST HOLZ5 In SURROUH00+G i*WTID ELEVAT+ON. REMOVE AND DISPOSE OF EXISTING GRASS AND TOPSOIL I. a,FULL WIN SAWMIT 0.5' NNSIDE OF PROPOSED BACK OF GURB, SEE SREE7 C4 FAR OIMEN!I TO CONTRACTOR YO PROTECT ALL F1'15TINC tITN,TRES M REMAIN RIMS A5 NECESSARYSQ FiM511 GEIAik'. 0.1 REL(&JE E)QSIING SIGN AND MOUNT ADJACENT TO ENtSIING SIDEWALK. 12 SAWVUT AND REMOVE EV511NNC S.OEWALN[ AND CURB FOS STEAM DRAIN W1F. INSTALLA11014. REPLACE WITH CLIUFNT CONCRETE AS SHOWN ON SIDEWALK DETAIL. 113 SAWCIIT AND RETAM A914WI `.ONCRETE PAVEMENT AS NEEDED FOR IRNOCATPH ANDIOR ELCCTRMCAL UIiES- 8 PRLIVIOE FULL DEP7k SAWUl A014 REMOVE ASPHALT CONCRETE PAYEL"1 r'QR COZEN. CONCRETE 9DEVU0. SA1fCLT LINE 9MAAL HE LSEO TO rORM CE3AEHT CONCRETE SRICWALK. "SE SHEET C4 MR 01NCHSW6 019 pj,QAVrL FULL SAWCUT AND REMOVE ASPHALT CO CIRt'IE %ILA PAVEMENT AND CEMENr CMNCKIE TXMUM CURS FOR 20 N•ROT FXtMSION OF ISLAND. SAPICUT LINO SHAI BE 0.5 FEET INSIDE OF ftopOSED CDR& ME SWLI.C4 FOR AW110NAL INFORMATION. T. E. S. C. NOTES QINSTALL CATO-I BASIN PROTECTION 15ER DETAIL THIS SHEET, & INSIALL SILTATION FENCE PER DETAIL THIS SHEET. ONSTRt1C-DON SEQUENCE s, SiJU" AND MIEND H�51RZTTOFI AEE.PHO V'ATR TILE CITY DF FEDERAL'.WLT. CCN00a PREC£N SMUCIf01t TNSPEM;MQ N OFF PROJECT SITF. z_ FLAG CLEi3Rk6• LIMITS, S. Cp11RAC701t SNALL RAVE UTILITY COMPANIES LOOXF ALL LINES PM TO ODNSTRUC1x0m 4 INSTALL TEWORARY EROSION AND SEDIMENTATION CONTROL rAwTIES S a.EAR AND GRUB ALL AREAS VATNIN CLEARING LIMITS PER PLANS. B DENQ6R, REUCVE AND SALVAGE ITEMS PER PLANS, 7- INSTALL C.IRIENNC B RECMPACT HEW PAYING AREAS, LAY CRUSHED SUB -BASF AND PAVE. INSTALL SIDEWALKS AND APPURTENANCES AS REQUIRED. 9, SMKIPAWT PACED AREAS AS INDICATED. M LANDSCAPE AND STAMU2£ THE SITE iN, RE NCK IC PORARY EROSION AHD SEDIMENTATION CONTROL fACILIIES AFTER THE SITE IS STABILIZED, CLEAN DpN115TREAM SYSTEM IF NECESSARY PER INSPECTOR_ ?ERMIT Nc ^ CITY OF FEDERAL WAY AareDy�iNNr� —. _—� DAY£ APPO ux�1+:N: Uwnr DR1.RN- +T'N CFIECI�D: R6YISi0H NUMBER - PROJECT NUMBER_ FWSDO014 DEMOLITION, T.E.S.C. PLAN AND DETAILS I DP C3 S3 [ 60GE.tF7rF1 � � South �LEGQe ����1s f _ r^g' 7. ti IS - { END T EO0 6C C7Y - - - 1• - t, •. SR 5 7 � � 9EGrH R L ,: e s !`•; 5' - `Z . •6 - 71 ' ik.er♦ y -I. kF e- PLC U $9R, )S --- 1 _ ➢ I 7 v su 0#01M GATE 91 I 1 - r f _ ; .r jF, - ' - 5.•' V 1 • ' i4} a • 0 f 0+AMC LCCA71Dn AS [%. Ge1E . A 1 � � _ _ 1 .p ��.••[ ]^.J 2 ' � f _ r 56116.15 5546.37 1-1� �'Li�l1: 555.'s6 5152-731 ,,.. m 1 v I I � a •� ��` . R 'T y-�" 6, , • ! 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JAK''ARY1 'D0- DICCIGI:: QE ORAFN- GiTI rH€C1�: R6ti E$T0ti vuaet:w SCALE: 1'.30' I,KOJECT NW45FR: FWSDO014 SHfiET ", OF B C4 1 J J � � � — � .�. � � �. ��`YQ- ,� � ��` ��•` it �` • - - 3oat�r�r � D � r J ' �� p,�enue south _ .. - �•_ - --� � ..� ��� �. , _. _ � -} ~� �` � venue South .d. ,.3: s'i' w. •.�",,.,�•"'' J M �.�.r-"' _--='�+, � f .. _mow �'.•- ....-, - : i~ �'�'- � t ••,t �.- _• _ �_ - `h--J - r ,.•.rs - 4 -Y1 L''`c •• ` • _ S'u llC •. _. t �- �' - �[ , _F _ rrrr '"..q •i3' � 7 BELaG11ESpt -'ter_. - ..� L'y:i�" _ _�1 ' -J 'tit .•5@C O[TAL TITS '7*tl i4 Rip I RBI �� .�. f e � ,i y` • ���'. -r '. � :..p I r .f F •'y 5 - .�....a s rr n0:t plc�r ur Irlrarrafr i � ELEYA l9d•••Zn.4J f � 01 I ;� y , n:J NUT EXTEND POSI ABOVE TOP OF3C4 ¢l0 FiOl EXTEND "IN ` T F•OST AODS'E STO ` 2 1 'T07 4F S61 N,:[ u WAX a '2' POE 111Br P.`.RFCY.AIiLF--'t I sro. = 6• POST F2 CAULi 1 7•-0. O7kE 41FO-L S10E1fA1K F� RKFALlA71ON - 10r -m-WATEO PTST 9OGCAa mW 1� SD AdO • 12 GAUGE Um EVA0 W ..XN1T I 13 I4' TYPE I TYPE 2L (left) shown TYPE 2R (right) PAVEMENT ARROWS HOi TQ SGALK /, -U CONCRETE UI N. [__9LZL IAN- CASE 1 CASE 2 (NO CURE & GUTTER) (WIH OW AND GUTTER) SIGN LATERAL ELKEMENIT tiQL Ij AIE ILA1StTIIAL F 11rJJOgtANSHp= ALL Cp+RORY s0 THE LATEST r,Gpp1 ST.WOARO RllLS AND SPECgYJIIONS 2) ALL LT.EItAE1G IAHNYI cn @ 4 Cr eAY %I vAAI :If SIrJI yS 15 tNE pESPpxANUTr OF r.>~ COHIRACIq A R*11-0r-WAY VmT om TW_ m IS Ik"OLIM DfPIRE WORK COLWENIiS .T) THE Step sw SHAM BL HS�kF fAOP A pgjANCE OF AT Uf05s I55no 25 YP". n 11 6 hASATC�SY[6 is 10 mm,An � EEO WITH POSlEO SPEfP M 15 UPK }) SIGN KiF AL SHALL BE ALTI-MR 5012-1130 fIR EO6I-T6 ALLOY TREAICO riTH ALOBHE 1200 CIWYERS!W COAY41w TIOCKNES5 SHALL RE 0.000, S) Mf1{Y DYL SI L WTG FOR STOP ANO YIELD SIGNS $ICI L BE 1q�H DH N IC1f5M cpxK {ASTM IYPF .1 OR [ImER) AEFWqv BOOZED 747IT PRO, tCRW PLASBC SHEETING, 6) LEITFAWG. LAVEW. SHAPE AND WLORwr SHALL NEEI `JECfLO ItEOUIMUFUIS a THE MANUAL CII LOAiORIA TRAFFIC WItM DEVICES. LATEST EDITION. 7) IF YTF b SW is R[4.f01ED, SICH SHALL NET All ABOVE RE91 MUF/FFS AHD TIE J6 X, 36• X 36- 04 SIZE. SIG P�ACEMT BETA NOT TO SCALE KEY NOTES () 4''4W MITE PAINT STRIPE OYP CID1 PAINT HANDCAP SVOCA PER AUA STANDARLIS IYP) C CU PAVE)AEIIT ARRDYIS PER DETIM, 04 THIS S:-iFET O '140 PARIONG - FIRE LANC (3' '-ME LETTERS . le HIGH - 7E LONG) YELLOW PAINTER tnTEAS, SPACING AS 511OWN- pPAW em YELLOW W It SOr ifWRt 1t W FIRE LANE- l7Fk 4- VIE WTL PAW iV0E 2' OC. 1 6" *a SWO PKIt PAdII STRn (TTP �k-BOVIDE FIANDCAP PARKING 5.'A:L SEE SHEET Csi. LEFF wA TURH 11 XI B' - S?GN TYPE 8 SD�z]D" OHLY 17-XIB" \ C1 / RE*ES ► STAFF "00 NOT ENTER" G "LEFT TURN ONCE' OULT DNI WAT' PJMI L+m1LF[ ON 0 12%ID- RI-1 30'X30' R7-B Q,X18" @ -NO PARKING DROP OFF LANE' 0-STOP" 0 'RESERVED PARKING' SIGN LEGEND !R{GIIT I Tll llfl ON:r 1z"zle' j"RIGMi PJRN GrILt'- No. CITY OF FEDERAL WAY ~K D BY DA Ir STRIPING AND SIGNAGE U 07U) mve QF- dam W U 0-C) 3. z n a RIMISIONS; APPO_ DATE, :ANURY 2DO2 NTi51CN; 05'!UE DRArN' 'ILNI CNEOKEWB R$VISFON NUITUR : BCALN: 1'-M' PRO.Irm NUXBER: FWSE)009 STTFv. r 10. OF 8 LM 2-S/8. O.D OAL Tf. S1Eil ROURB POST CONTRAG7JON JOINTS CO TS' CTI LE FKN RIN Uv, PER PLAN w...mo16 SOW uANHUANE M SNDWK ©'imm E. STD. T}'PE Ii CB GONG LOP SLAB Cw UNLm AgjJ 51 AS MOM ' P'Ai CEyERT CONC: INSTALL I SET IN � P9 CONCREIfi A W DF �• OEEP 7TP 8071T � 4 ASP C6 G HALT CONCRETE PAS Sf2TI0N �- CL 3080 OIALAft ;'ACC Or W" PLACE S;Oi5 i• KwM f TeTRncrloar 1aN7s srlALl ae allb QC PARKING ONLY " riH1Trl VARIEi ASPI{AL,I SATURATED M-T PL .EP Ai i5' 11AHD1GAP 'VAN AGCESS1eLE• S1CN SICN PER ADA SPEWICARONSL 011i STAl1 ONL7 z ym KANS •r 7 THflli .IdINi5 FiALL BE 3/6•� �• ASR}lALT 5A7URATEO 17:1; PLACED AT BITIVFWAYS. ALLE7 REnJHNS ANO VMEFLGHAIR RAMPS _ S. V-QROOVE µARKS SHALL BE via• OUR nFCT I a A9 - 1e - J 4 BARS D 6' U.L -�{OTT 47.• a C11P - i _ COiIPAG1El1 M+WE BEDDING IMpE PLACA7 AT S A.C. top 7 SIDEw" 7 1 /2' ❑ C FOR B• SWEWALN T REA*W PACKING WATER STOPS +' WIDE ?017 a- ME muff S;Ff+PE S IRKS. " k z � ALL MWS SHALL BE CLEA.Y A" CO(ZO TO A IBC RAj;WS. IMTS SNAIL BE KUSK MT" iFSE FIHISIHEO SVRFACE `A FORLIS SFIALL BE EITHER WOOD OR STEEL AIA SHALL 1AEET A11 4EOU1RE NTS or 71AESE J� F04 TALK 36' a SAME VATERIAL AS TANK. iAELAFI: OR FUSED TO TAN; s� %•F71 J SPEC{}TLA,. P IB. F'ADITW H.I: SYi18OL PER ADA SIRM"ICATIOHS o_ B p l YntlSH ^�- 5 :.GPiCfIETE SH BE K WI FIX 3000 PP 9-I SACK KITH E1C - ? CONI:SE AGCR GA IF G7�ASJING NQ 7 FINE AYxdeEGATt I'LItS$ T \ 4 ('A 7. SIDEWALK IHICItNf55 AbdACEN[ i:l ROLLED CURB — !1 H. STEP O 12 O,C- riELO GR BOLT SID.�� 1 ATI TO CURB b+ (ATr1ER - a• H.K 53Ep5 TO RISER TANK. [pI1PLf VA kk ADA S} _ + VERTICAL CURD - H• �/ (rf? 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OF rs 59-ir Or f!'lphC r'IiE$O GEIta[iR TP:/ + > VPS ►L[M'iA IrBPIC .1SERI $FY[L iE Cpouncr[V yrfrl A W+!INN r,•6`� 11Retr4 DiSEID SHALL in 1/A• 0.O. x [ 1a L11 o[HESS i4 8uRi1 � fi P9. ke CW CH cw Of SEcrIaN ]• RLA1E0 OF 11G nl' 1W9 vl? �.4r rH figpailcY WYIfCI& RK 'a•CR1Lt !M . n. .APY ]O rpEt O[ANPOIIiNI n![R; DATA BLOCK ONE -CARTRIDGE STEEL CATCH BASIN STORMFILTER f1' f atTIIET OUTLET 0 INLET INLET 6PTiON5 VMLAM AT Ex6--IJ. ❑ OUTLET :TUB - OTHER THAN 8 DIAkETER INLET STUB © OTHER: C6L2A., M ;A Ai A i. E PA iV T jp2t h lAC AIRPOPT WAY. PURTIAMU. OR 5?4Lf7 f.71J3L] FAX f503% !� pA_!A BLACK ONE -CARTRIDGE STEEL CATCH BASIN STORMFIL_TER MB liLE EOFrFFuIfRPFKK+. �'r- !'l II ET OUT F'.T 01 DO INLET INLET j I,T,�S (AYFRABL£ ­TRA LOST}: n OUTLET STUB - OTHER TII.AN 8' DWAF.TER C3 INLET STUB C] OTTER: C 5?0,1- !"WATT, AAANAGEM r1cT71-N H-[ ,y=40 YIAY••2DitTLAn;7. ' jsbiJ 240-5793 FAX: {9O-Y y,q-9SSJ PERMIT No- C1TY OF FEDERAL WAY APPRf1FCP Ds . DETAILS J ti z F N bl ZIn QF- ?Q I°gym 2a Y 0 $ REVISIONS: -APPD. 1 DATE: JANuIm 7G0 DESTCN: DIer- DRAIrm GEN CFi FI:(rELI: REVISION YVNRBA: SCALE: AS SHOM PRWF'•CT VUMbER- FWSDM4 SE[Slii H4. OF 8 POPOlIT�,'r'Aa7: 101AACT[ •.•�•• 1-1 Appendix B. I— East Basin Water Quality Calculations ST ORMWATER soi.unoNs,r�c. Prepared by J Reidy on November 25, 2008 Size and Cast Estimate Panther Lake Elementary East and King County Library — Stormvwater Treatment System Federal Way, WA Information provided: • Total contributing area-= 5.42 acre • Impervious area = 2.66 acre • Detention release rate from Library = 0.583 cfs • Undetained water quality flow rate from Elementary = 0.1044 cfs • Presiding agency = City of Federal Way, WA Assumptions: • Media = CSF cartridges: Cartridge Height = 18" • Per cartridge flow rate = 7.5 gpm • Drop required from inlet to outlet = 2.3' minimum Size and cost estimates: The StormFilter is a flow -based system, and therefore, is sized by calculating the peak water quality flow rate associated with the design storm. However, when the StormFilter is placed downstream of detention the flow rate nerated at the water quality storm is not always representative of the total volume of water that will go through the ,.ystem or type of pollutant -loading the system may experience in one year. For this site, CONTECH Stormwater Solutions Inc. recommends using an 8'x18' StormFi{ter with 42 cartridges (see attached detail). The estimated cost of this system is $76,000 - JaL000, complete and delivered to the jab site. This estimate assumes that the vault is 8 feet deep.. The final system cost will depend on the actual depth of the unit and whether extras like doors rather than castings are specified. The contractor is responsible for setting the StormFilter and ail external plumbing. Typically, precast StormFilters have internal bypass capacities of 1.8 cfs. If the peak discharge off the site is expected to exceed this rate, we recommend placing a high flow bypass upstream of the StormFilter system. CONTECH Stormwater Solutions could provide our high -flow bypass, the StormGate, which provides a combination weir-orifico control structure to limit the flow to the StormFilter. The estimated cost of this structure its $4,000. The final cost would depend on the actual depth and size of the unit. 02006 CONTECH 8tormwater Solutions 12021-B NE Airport Way, Portland OR 97220 Page 1 of 1 contechstormwater.cam Toll-free:800.548.4667 Fax:800.561.1271 T5-P022 ■+►�•i��u��wu # �'WWOWWW ■ Iiralkww STORMWATER CONTECH Stormwater Solutions Inc. Engineer: Date Site Information Project Name Project State Project Location Drainage Area, Ad impervious Area, Al Pervious Area, Ap % Impervious Runoff Coefficient, Rc Upstream Detention System Peak release rate from detention, Q feWm peak Treatment release rate from detention, Qrelea6e treat Detention pretreatment credit (from removal efficiency caics) Mass loading calculations Mean Annual Rainfall, P Agency required % removal Percent Runoff Capture Mean Annual Runoff,Vt Event Mean Concentration of Pollutant, EMC Annual Mass Load, MtQtat Filter System Filtration brand Cartridge height Specific Flow Rate Number of cartridges - mass loading Mass removed by pretreatment system, MP,e Mass load to filters after pretreatment, Mpess1 Estimate the required filter efficiency, Emit,,, Mass to be captured by fitters, Mtiitet Allowable Cartridge Flow rate, Qaarl Mass load per cartridge, Mt;,,, (Ibs) Number of Cartridges required, Nma,, Treatment Capacity Determine Critical Sizing Value Number of Cartridges using Qroeate treat, Nflow Method to Use: SUMMARY Determining Number of Cartridges for Systems Downstream of Detention JHR Blue Cells = Input 1112512008 Black Cells = Calculation King County Regional Library and Panther Lake Elementary East Washington Federal Way 4.09 ac 2,38 ac 1.71 58% 0.57 3.82 cfs 0.69 cfs 50%q 38 in 80% 90% 291,309 00 60 mgll 1090,49 Ibs StormFilter 18 in 1.0. gpmlft' 545.24 lbs 545.24 Ibs 0.60 327.15 Ibs 7.50 36.00 Ibs 10 0.17 cfs 42 HYDRAULIC Treatment: Flow Rate, cfs 0.69 Cartridge Flow Rate, gpm 7.5 Number of Cartridges 42 F1 aw Frequency Anal ySi s Ti ffle Series Fi 1 e : wq_east_new . tsf Projett Location, sea-Tac ---annual Peak Flow Ra'tes--- FIOw Rate Rank Time of Peak (CFs) 0.174 6 2/09/01 12:30 0.120 7 1/05/02 15:00 0.382 2 12/08/02 17:15 0.11.0 8 8/26/04 0:45 0.269 3 11/17/04 5:00 0.182 5 10/27/05 10:45 0.197 4 1O/25/O6 22:45 0.620 1 1/09/08 6:30 computed Peaks wq_east_new.,pks Frequency Analysis------- - - Peaks - - Rank Return Prob (CFS) Period 0.620 1 100.00 €5.990 0.382 2 25.00 0.960 0.269 3 1.0.00 0.900 0.197 4 5.00 0..800 0.182 5 3.00 0.667 6.174 6 2.00 0:500 0.120 7 1.30 0.231 01110 8 1.10 9.091. 0.540 50.00 0.980 Page 1 Appendix B.2— KCLS Flow Splitter Design Panther Lake Elementary Project # 31147A Flow 5plitter Design Stage Dischar e Orifice Weir Total Elevation Circular Discharge I Discharge (ft} Stage(ft cfs) (efs} (cfs 0.00 0.00 - - 0.50 0.50 0.46 - 0.46 6.52 0.52 0.47 0.47 0,54 0.54 0.48 0.48 0.56 0:56 0.49 0.49 0.58 0.58 0.50 0.50 0.60 0.60 0.51 0.51 0:62 0,62 0.52 0,52 0,64 0.64 0.53 0.53 0.66 0.65 0,53 0.53 0.68 0.68 0.54 0-54 0.70 0.70 0.55 0.55 0.72 0.72 0.56 0.56 0,74 0.74 0.56 0,56 0.76 0.76. 0:57 0.57 0.78 0,78 0.58 0.58 0.80 0.80 0.59 0.59 0.$1 0.62 t158 0,0 : 0.69 0.84 0.84 0.60 0.0 0.64 0.86 0.86 0.61 0.1 0.71 0,88 0.88 0.62 0.2 0.81 0.90 0.90 0.62 0.3 0.9.2 0:92 0.92 0.53 0.4 1.05 0.94 0.94 0.64 0.5 1.19 0.96 0.96 0.64 0.7 1.33 0.98 0.98 0,65 0.6 1.49 1.00 1 M 0.66 1.0 1.66 1.02 1.02 0.66 1.2 1.84 1.04 1.04 0.67 1.4 2.03 1.06 1.06 0.68 1.6 2,23 1.08 1.08 0.68 1.7 2A3 1.10 1.10 0.69 2.0 2.64 1.12 1.12 0.69 2.2 2.86 1.14 1.14 0.70 2A 3.09 1.16 :. 6.- - - 0 1 2.6 3,32 1,18 1.18 0.71 2.9 3,56 1.20 1.20 0.72 3.1 3.61 1.22 1.22 0.73 3.3 4.06 1.24 1.24 0.73 3.6 4.32 1.26 126 0.74 3.9 4.59 1.28 1.28 0.74 4.1 4.86 1,30 1.30 0.75 4.4 5.14 1.32 1.32 0.75 4.7 5.42 1.34 1.34 0.76 4.9 5.71 1.36 1.35 0.77 5.2 6.00 1.38 1.38 0.77 5.5 6.30 1.40 1.40 0.78 5.8 6.61 1 A2 1.42 0.78 6.1 6.92 1.44 1.44 0.79 6.4 7.23 1.46 1.46 0.79 68 7.55 KAproject1311.00131147AMa feeResNtowsplitierxls Orifice Circular Weir dia (ft) 0.410 NIA length (ft) NlA 4.0 disch. Coe 0.82 3.3 IE 0 0,82 figure 6.2.5.A, flow spiitter, option A in the 1998 WOM for design critera. "The design wafer surface should be set to provide a headwater/diameter ratio of 2,0 on the outlet diameter of the office plate on the 184nch r quality pipe = 0.41 feet: Therefore the design r surfce and weir elevation is set at 0.82 feet. 0.82 feet the flow rate though the water quality nce plate is equal to 0.59 CFS which Is equat to s 2-year release from the KCLS detention facility. Flows exceeding the water quality flow rate will flow over the weir and discharge to the 18" bypass pipe. 100-year flow rate from the library = 3.185 i, this flow will stage within the catch basin at an ration of 1.164eet, flowing over the weir and th bypass pipe. The flow to the water quality facilty ng the 100-year stone event will be 0.71 CFS. Protect Name Client Name Sheet Uj.44y Prepared 6q: flat Checked h : Nte o �n16 4&V iC�� w _ Q2EX? �Ei�141nIJN�•' For f�bNO A2,V106FS 1AISGA�F■CJt-TI1 570RAri5 AZ 7 ^`SIZE Gt3 f , 'ONO - _ - 1� _ 3.15 _ kW U106ur4g -' - -- -4 TERZ Y47C - 5 6 _ 5U eF . ,QA° C� D• 5. •r I "a /M o� t/1 [x� S - 2-5-, = CIBf 61r��.. � voLuNe >��2¢;. CELZ6--o746Wla F(?_ FI7 [J5c,._tld9.!�_C' 21i A5.. UWu-57 AW05 01& Fu'V67-X,1 C�>�/3 ���7 /�C�.-zs•5��j5 ti•' ��`�°;�-3'-��/W[=z�j°� ff3�;�-�Go°�M CPe� K 41jC70DNP V 4G L UOM ?o -Z.] ° )Pg -' 5430A) ;? t�7,t✓s7) 05' 2157 fi Q3) IzZ)f &,5T710 1102 i7x3 2 sY I4 1) r Mg/ (Zo..5Ya 2) co Project dame f CUent Name Sheet 2 of f &J,4q �t �ZG1IPrepared by: C Date Checked by: Date L,,w 9D _... _ .._ 67 _.L= �Jl�, 4eL=SD���60/ Kf= zl�io�vOk /,00 &m ��. Cv�r�� 4pp 7d C��s _ /Do 1>_..._ . - -a ...... _._ ' --z8z ' /� � JUM ro �CJEI`PDM� • � � � �� ,' 2-9¢ � 8 / S ¢D of S IG Tf�'C E571/147O Z- 69-65 = lZ 40058 = 3,Z_ F 5 �= fv85� lv mr�t Project Name CUent Name _ Sbeet-Z,Q of /Q Fev 'i w-4u Lrg2412 Prepared by: Date Checked by: Date 401 o•�T hf 1�1 �fr' " f - ....... ... 02 A WE;c�ZG AA" \ p1241n/(,IW Project Name Client Name 5beet oP �L W� i3 Prepared bp: Date Checked by: Date I �u�5 Ir-eo^9� - - GDrITMO(, IYI &44-Y1710 - 7- f3 Y--- ,� z 5a 1-4V :DC/TFFILL Z S10 2.54 • 1710� 0 � Z5� INV= � 52 ° ZSL rrVseci Y7uinG ...... ,_ FEpE,2AL way &.O e,4 / Sheet or Prepared by - fiats Checked by: Date �&S //- Nt 3'0 j�1Yt�Y �7'�crJ 4Yr=��LQ� POO IJI.&"6V o y "Y 6•''Gl tPA 77YP 0 T, FF1244cl�, P105PIT4L i Federal Way Regional Library i KFFF # 107494 August 18, 2008 1 Basin Areas Upstream Forested Library Lane - irn erviaus Library Lane - Landscape Library Lane - Total On -sits: Impervious to detention On -site landscape to detention On -site total to detention Total Area Draining to Facility.' On -site Irnpervious- bypass detention" On -site Perviod!s- by ass detention` On -site Total- bypass detention" Existing vropaseu Condition Condition Change (acres) acres} (acres) 10.780 10.780 0.000 0.510 Q.51Q 0.000 O.Q70 0.070. 0.000 0.580 0.580 0.000 T220 ±2.539 0,319 1.870 4 -0.066 q_090 4.343 0.253 15.450 j 15.7031 0• WO.900 0.046 0.046 0.601 -0.299 0.647 -0.253 l r ' � contributes to the Facility. 'Note that the original FAIRL detention system design assumes al 0 this area Approximately 0.90 acres actualty drains south to the existing trees before crossing under the library driveway. Total lncraase in Flow: 100-yr flow for 0.385 arras_ of grass on tilt with 1-h6ur time step.: 0.077 cfs 1QNyrflow for 0355 acres of impervious** with 1-hour fime step: 0.172 cfs Difference: O,Q95 cfs r 0.1 cfs Per KCSWDM Gore Req, 43 Exemption #3A with roof downspout controls per Section 5.1, a flow control facility is fret required because the project produces less than 0-1 cfs incroas.e in the I M year flow. otal Increase to Water Quality Flow: yr flaw for 0.355 acres of grass on till with 1-hour time step:. 0.018 cfs -yr flow for 0;365 acres of impervious" With 1-hour time step: 0.091 nfs ifference: 0.073 cfs Tote that Us analysis does not account for now attenuation by roof runoff dishersed to native Appendix B.3— Roof Downspout Study V Daniel Moore Subject: RE: Panther Lake Storm dutfall Check gym: Jeff Greene [mailto:jeff@ggarchitects.com] Sent: Wednesday, October 08, 200811:40 AM To: Ray Smalling; Chad Weiser; `Greenberg, Noah' -' Cc: 'Kate Baumann' Subject: FW: Panther Lake Storm Outfall Check Information gathered during two days of investigation. Let us know if additional investigation is required. Jeff From: Shane Sobotka [mailto:shanesobotka@gmail.com] Sent: Wednesday, October 08, 2008 11:27 AM _ To: jell@ggarchitects.com Subject: Panther Lake Storm Outfail Check On October 6th and 7th, I met with Flohawks to determine the outfall locations for downspouts at Panther lake j Elementary. Downspout A is shown on drawings to connect to the same line as the other downspouts along the f north face of the 1967 wing. On the 6th, Flohawks tried locating two of the storm pipes from that system, but ran into clogs less than 20ft in. On the 7th, they returned with a fetter and attempted to clear the lines, including the cleanout, without success. A search of the woods to the north revealed no obvious outfall, even when water was pumped into the line. Drawings show downspout B's line running into the same system as CB "C", which was filled with rock, dirt, and vegetation, partially covering the pipes within_ The CB to the north of C, also on the same line, was injected with water without any running into C. The perforated pipe designation on the wings could account for this. The directions of the pipes seen in the catch basins seem to be in conformance .ch the drawings and the direction of the calculated (not located) outfall shown on the attached survey_ "D" is a cleanout that appears to have been broken and filled with concrete. Drawings show it to be connected to a line running west, under the school, also serving the two roof drains in line with it. Flohawks attempted to feed a camera down the two roof drains, but could not get past bends in the pipe, The outfall of this line, if per drawings, is also unknown. -� Shane (reply to s.hane,�'uy.,g4qLr,hitects. oc0GGA GREENE GASAWAY ARCHITECTS PLLC Architecture •Planning aManageinent Tel 253-941-4937 Fax 253-941-5122 M l 0/13/2008 .J d �1 Jf f1 i ICI 41 e I -100HOS 3AV 1 U3H1NVd S-L')DIiHOHV AVMVSVE) N3AHO 3 � G q (Da(Dalnn b119 �: gr i a i- z `I 'Tv-�Mo T*AIRM 1D rc+v �(01 I-Vc -,-I it T 2,11 L TxST Ljfs4.tjLS —DOAS" Ttti-q 11,31-.kqt - E5yT! Fl-r- Au O'ek 4 it llku 1" T I:. W", NT 1 qt,�s Appendix B.4— Source Controls Activity Use this worksheet to identify the activities that you conduct. Do you conduct this Sheet Interpret the categories broadly. Numbers A-1 — A-43 activity? If so, Number correspond to sheets located in Chapter Ill. where? TYPE OF ACTIVITY INDOORS OUTDOORS TZ A-1 Required BMPs for All Commercial Pro erties A-2 Storage of Liquid Materials in Stationary Tanks This does not include underground tanks or small containers A-3 Storage of Any Liquid Materials in Portable Containers Such as drums, buckets, jugs, or barrels A4 Storage of Soil, Sand, and Other Erodible Materials This includes storage of all types of erodible materials A-5 Storage of Pesticides and Fertilizers This includes non -liquid pesfi6qes and ba s ar lies of fertilizer A-6 Storage and Treatment of Contaminated Soils This applies to contaminated soils that are excavated and left on site A-7 Storage and Processing of Food Items This includes storage of fruits, vegetables, meats, and other foods and processing activities at wineries. fresh and frozen juice makers, and other food and beverage processing operations _ A-8 Storage of Solid Wastes and Food Wastes (Including Cooking Grease) This includes re ular arbage and all other discarded non -liquid items A-9 Storage of Scrap and Recycling Materials (including Auto Recycling Facilities) This includes scrapped equipment, metal, empty metal drums, junk a (lances and vehicles, and assorted ree ciatales A-1 tl Treatment, Stora a or Disposal of Dangerous Wastes ..F l� .� .,.. :F' - y■++.� i1+ 'l. ir! �� � i ��4 '"f��.'i 3'_�f. �.�... :•. r2}�•, f� .L L 1 .'ih ,5il•1<< �.: h,.a 7'.. :.i'. n.i:r A-11 Cleaning or Washing of Tools and Equipment This Includes tools, all types of manufactured equipment components, and work equipment such as lawn mowers and fork lifts A-12 Cleaning or Washing of Cooking Equipment This includes vents, fitters, puts and pans, rills, and related items A-13 Vehicle Washing and Stearn Cleaning This covers cleaning and washing at all types of establishments, Including fleet vehicle yards, car dealerships, car washes, and maintenance facilities A-14 Interior Washing Operations (including Mobile Contractors) This includes carpet cleaners, upholstery cleaners, and drapery cleaners A-15 Pressure Washing of Buildings, Rooftops, and Other Large Objects r7.L• _ Yi=':i.r'. — t ��� Ir x�.=i..:;: ��-jrrFNg A•-16 Truck or Rail Loading and Unloading of Liquid Materials A-17 Fueling Operations I This includes gas stations, mobile fuel trucks, pumps at fleet vehicle yards or sho Ds, and other p rivateiy owned p urn s A-18 Engine Repair and Maintenance This covers oil changes and other handling of en ine fluids Rpm Concrete and Asphalt Production at Stationag Sites A-19 J Activity Use this worksheet to identify the activities that you conduct. Do you conduct this Sheet Interpret the categories broadly. Numbers A-1 —A-43 activity? If so, N um ber correspond to sheets located in Chapter III. TYPE OF ACTIVITY where? INDOORS OUTDOORS A-20 Concrete and Asphalt at Temporary Sites This includes construction sites, remodeling, and driveway and parking lot resurfacing A-21 _ Manufacturing and Post -Processing of Metal Products This includes machining, grinding, soldering, cutting, welding, quenching, rinsing, etc. A-22 Painting, Finishing, and Coating of Vehicles, Products, and Equipment A-23 Wood Treatment and Preserving This includes small scale contractor operations (such as patio decks) and large scale lumber treatment operations A-24 Commercial Composting A-25 Chemical Applications -Other than for Landscaping This includes use of a1 aecides, fungicides, pesticides, and rodenticides �ii—` •!'�:`wi� .1a Z 1! L A-26 Landscaping Activities This includes vegetation removal, herbicide and insecticide application, fertilizer a ppl]cation, ardeni , and lawn care F &:-.v. - ''a'=.S�i`b' _ . P✓s?',4 .-m. `�• � � pd�,H�i .v, �.. ���� �:ySiiL... .}. A-27 Clearing, Grading, and Preparation of Land for Small _ Construction Projects A-28 Demolition of Buildings A-29 Buildlnq_Re air, Remodeling, and Construction A-30 Boat Building, Maintenance, and Repair A-31 Vehicle and Equipment Parking and Storage This includes all types of parking lots (commercial, public, and private), X retail/store parking, car dealerships, rental car lots, other fleet vehicle lots, equipment storage and parking areas such as at equipment rentalyards) A-32 Sidewalk Maintenance This includes cleaning, and deicing A-33 Swimming Pool and Spa Cleaning and Maintenance This includes all swimming pools ands as not at a single family -residence A-34 Keeping Animals In Controlled Areas This includes kennels, rabbit hutches, and similar animal rearing and care A-35 Keeping Livestock in Stables, Pens, Pastures or Fields This includes cattle, horses, pigs, sheep, oats and other hoofed animals A 36 Logging and Log Yards This applies to Class IV general forest practices only A-37 Mining and Quarrying of Sand, Gravel, and Other Materials This covers sand, gravel, minerals, peat, clay, rock, etc. but does not Include excavation at construction sites A-38 Well and Geotechnical Drilling This includes mechanical drilling and directional drilling for water wells and utilities, environmental protection and monitoring wells, and geotechnical borings A-39 Roof Vents and Fugitive Emissions(including Dust A40 Street Deicing Operations This includes deicing and anti -icing of streets and highways A-41 Wheel Wash and Tire Bath Operations A-42 Potable Water Line Flushing or Tank Maintenance A-43 Use of Soil Amendments on Construction Sites 1 J Required BMPs for All Commercial Properties MINIMUM REQUIREMENTS The following EMPs are required if you own or occupy commercial, industrial, agricultural, public, or multifamily residential property in unincorporated King County. Clean Your Storm Drainage System Maintain your storm drainage system by removing sediment and other debris to prevent the transport of pollutants into receiving waters. The storm drainage system includes all drains, catch basins, pipes, ditches, gutters, and flow control and water quality facilities. See l3M1' Info Sheet 7 in Chapter 5 for details on drainage system -maintenance. Eliminate Illicit Connections to the Storm Drainage System A common situation that can cause severe stormwater pollution problems is discharge of non-stormwater to the storm drainage system. Examples are discharges from internal floor drains, appliances, industrial processes, sinks, and toilets. These are sometimes illegally or inadvertently connected or drained to the nearby storm drainage system. These discharges must go to the sanitary sewer system, a holding tank, an on -site process water treatment system, or a septic system. You must correct these illicit dischargm if you have any questions as to whether your discharge is allowable, contact the King County Water and Land Resources Division at 206-296-1900. (ZPI See BMP Info Sheet 1 in Chapter 5 for information on how to check for illicit connections. You can also ask for help from your local sewer utility. If you find out that your internal drains are January 2005 King County Stormwater Pollution Prevention Manual Required BMPs for All Commercial Properties (continued) improperly connected to the storm drainage system, they will need to be either removed, permanently plugged, or connected to the sanitary sewer, septic system, on -site treatment system, or a holding tank. Stencil Your Storm Drains Stencil storm drains where applicable to prevent the improper disposal of pollutants. Storm drain inlets should have stenciled messages such as "Dump No Waste Drains to Stream" stenciled next to the catch basin to warn against intentional dumping or discharge of pollutants. If the metal catch basin grate has been cast with this message, stenciling may not be required unless evidence of dumping is found. For more information or assistance in implementing these best management practices, contact the icing County Department of Natural Resources and Parks Water and Land Resources Division at 206-296-1900. Reader Note: The above requirements are the minimum required BMPs. If these BMPs fail to prevent: discharges to the storm drainage system, you will be asked to take additional measures to correct the continued pollution discharges. King County Stormwater Pollution Prevention Manual January 2005 Landscaping Activities This broad activity encompasses all aspects of landscaping, from small-scale yard maintenance to large-scale commercial landscaping businesses. It includes vegetation removal, herbicide and insecticide application, fertilizer application, watering, and other gardening and lawn care practices. Stormwater runoff from areas that have been subject to pesticide or fertilizer application or extensive cutting may be contaminated with toxic organic compounds, metals, oils, suspended solids, nutrients, or coliform bacteria, and may cause biochemical oxygen demand. Landscaping activities related to golf courses should refer to King County's Golf Course BMP Manual (see Chapter 6 of this manual for more information). The BMPs listed below are intended to complement other regulatory requirements. See related Activity Sheets for "Storage of Pesticides and Fertilizers" and "Storage of Liquid Materials in Portable Containers." Note: Vie terra pesticide includes insecticides, Herbicides, fungicides, rodenticides, etc. 0 The following BMPs, or equivalent measures, methods, or practices are required if you are engaged in landscaping activities: Do not apply any pesticides directly to surface waters, unless the application is approved and permitted by the Washington State Department of Ecology. Follow manufacturers' recommendations and label directions. Pesticides and fertilizers must never be applied if it is raining or about to rain. Do not apply pesticides within 100 feet of surface waters such as lakes, ponds, wetlands, and streams. This also can include stormwater conveyance ditches. (This buffer distance is specified in the Department of Ecology's Stormwater Management Manual and the King County Critical Areas Ordinance). Remove weeds/vegetation in stormwater ditches by hand or ❑then mechanical means. Chemicals should be used as a last resort. Dispose of grass clippings, leaves, branches, sticks, or other collected vegetation as garbage, by composting, or by burning (where allowed). Do not dispose of collected vegetation into storm drainage systems, conveyance ditches, stormwater ponds, or surface water. Use mulch or other erosion control measures when soils are exposed for more than one week during the dry season or two days during the rainy season. January 2005 King county Stormwater Pollution Prevention Manual Landscaping Activities (continued) Avoid planting Species on the King County Noxious Weed List. Contact the King County WLRD Noxious Weed Program at 206-296-0290 or 206-296-6519 for information on these types of plants. Required Routine Maintenance: ' ' Store and maintain appropriate spill cleanup materials in a location known to all. Ensure that employees are familiar with proper spill cleanup procedures. Educate and train employees on the use of pesticides and in pesticide application techniques to prevent pollution. The following BMPs are optional unless the above minimum required EMPs do not provide adequate source control: Integrated pest management (IPM), a comprehensive approach to the use of pesticides is the most effective BMP measure that can be taken for .herbicide, insecticide, and fungicide use. 13" See BMP Info Sheet 6 in Chapter 5 for information on IPM. Fertilizers should be worked into the soil rather than dumped or broadcast onto the surface. Determine the proper fertilizer application for the types of soil and vegetation involved. Soil should be tested for the correct fertilizer usage, Use mechanical methods of vegetation removal rather than applying herbicides. An effective measure that can be taken to reduce pesticide use, excessive watering, and removal of dead vegetation involves careful soil mining and layering prior to planting. A topsoil mix or composted organic material should be rototil led into the soil to create a transition layer that encourages deeper root systems and drought -resistant plants. This practice can improve the health of planted vegetation, resulting in better disease resistance and reduced watering requirements. Use native plants in landscaping. Native plants do not require extensive fertilizer or pesticide applications. For more information or assistance in implementing these best management practices, contact the King County Department ofNatural Resources and Parks Water and Land Resources Division at 206-296-1900. Reader Note: The above requirements are the minimum required BMPs. If these BMPs fail to prevent discharges to the storm drainage system, you will be asked to take additional measures to correct the continued pollution discharges. King County 5tormwater Pollution Prevention Manual January 2005 7 Vehicle and Equipment Parking and Storage This activity applies to all types of parking lots (commercial, public, and private), retail store parking lots, fleet vehicle lots and yards (including rent -a -car lots and car dealerships), equipment sale and rental lots, and parking lot driveways. Stormwater runoff from these sites can be contaminated with toxic hydrocarbons and other organic compounds, oils and greases, metals, nutrients, and suspended solids. MINIMUM REQUIRED ROUTINE MAINTENANCE The following BMPs, or equivalent measures, methods, or practices are required if you have parking lots and driveways: Sweep parI:ing lots, storage areas, and driveways as needed to collect dirt, waste, and debris. Do not hose down the area to the storm drainage system. If washing/pressure washing of the parking lot occurs, the wash water trust be collected and discharged to a sanitary sewer or other treatment system. There are services that will clean parking lots and collect water for off -site disposal. Never drain washwater to the storm drainage system. CZFI See BMP Info Sheet 2 in Chapter 5 for information on disposal options. Gravel and dirt lots may require additional BMPs to prevent sediment laden water from leaving your site. Also, vehicles can track dirt out of the parking and storage areas onto public roadways. Basic sediment controls as outlined in Appendix D ("Erosion and Sediment Control Standards") of the King County Surface Water Design Manual may need to be installed if other BMPs do not adequately control sediment laden water from entering off site storm water conveyance systems. Wheel wash facilities may need to be considered if track out of mud becomes a problem. See Activity Sheet A-41, "Wheel Wash and Tire Bath Operations." January 2005 King County Stormwater Pollution Prevention Manual Vehicle and Equipment Parking and Storage (continued) The following BMPs are optional, unless the above minimum required BMPs do not provide adequate source control. Encourage employees to carpool or use public transit through incentives, Encourage customers to use public transit by rewarding valid transit pass holders with discounts_ A catch basin insert configured for sediment and also oil removal may remove some of the pollutants in runoff from this activity. Catch basin inserts require frequent maintenance to be effective. Carefully consider this when evaluating your options. Clean up oil and antifreeze spills with absorbent materials_ C See BMP Info Sheet 10 in Chapter 5 for more information, For more information or assistance in implementing these best management practices, contact the King County Department of Natural .Resources and Parks Water and Land Resources Division at 206-296-1900. Reader Note: The above requirements are the minimum required BMPs. If these BMPs fail to prevent discharges to the storm drainage system, you will be asked to take additional measures to correct the continued pollution discharges. King County Stormwater Pollution Prevention Manual January 2005 Sidewalk Maintenance ' This activity applies to you if you have sidewalks. Litter accumulation on sidewalks can contribute suspended solids to stormwater runoff; runoff from sidewalks crossing driveways may also have hydrocarbon, oil and grease, and metal contaminants. If herbicides are used on sidewalks, toxic pesticide compounds, oils, and metals may also be introduced into stormwater. If crack sealants or surface coatings are applied, toxic hydrocarbons, oils and greases, and metals may be, contributed to stormwater runoff. Sidewalks and driveways are important areas to target for stormwater pollution control because they typically drain directly to stormwater conveyance facilities. Note that BMPs for driveways associated with parking lots are described under Activity Sheet 31, "'Vehicle and Equipment Parking and Storage." MINIMUM REQUIREMENTS The following BMPs, or equivalent measures, methods, or practices are required if you are engaged in sidewalk maintenance: Sweep sidewalks as needed to collect loose dirt and debris rather than pushing it into the street or gutter or hosing it down. Collected materials must be disposed of as regular garbage. Conduct spot stain removal instead of washing the entire sidewalk. Do not use soaps and detergents to wash down sidewalks. If pressure washing of sidewalks is needed, and soaps or other cleaners are used, the wash water must be collected and disposed of to the sanitary sewer or taken off site for appropriate disposal. if only water is used, filtering devices at catch basins must be used to collect all solids and debris. January 2005 King County Stormwater Pollution Prevention Manual Sidewalk Maintenance (continued) The following BMPs are optional unless the above minimum required BMPs do not provide adequate source control: Use deicing salts and sands only when snow or ice is present (not as a preventive measure) and apply sparingly. Shoveling of snow is always preferred to dumping excessive amounts of deicing materials in an effort to avoid shoveling. if deicing salts are used, the residues and remaining granules should be swept up when the snow and ice: have melted, and reused or disposed of in your garbage. For more information or assistance in implementing these best management practices, contact the King County Department of Natural Resources and Parks Water and Land Resources Division at 206-296-1900. Reader Note'. The above requirements are the minimum requirod BMPs. If these BMPs fail to prevent discharges to the storm drainage system, you will be asked to take additional measures to correct the continued pollution discharges. King County Stormwater Pollution Prevention Manual January 20.05 Street Deicing Operations This activity applies to you if you perform deicing and/or anti -icing operations on streets and highways to control ice and snow. Deicers commonly used on highways and streets include sand, calcium magnesium acetate (CMA), calcium chloride, magnesium chloride, sodium[ chloride, urea, and potassium acetate. These deicing and anti -icing compounds become pollutants when they are conveyed to storm drains or to surface water after application. Leaks and spills of these chemicals can also occur during handling and storage. !]MINIMUM REQUIREMENTS 1 The following BMPs, or equivalent measures, methods, or practices, ' are required if you are perform deicing and/or anti -icing operations on streets and highways,: Select deicers and anti -icing materials that cause the least adverse environmental impact. Apply only as needed using minimum quantities. Always adhere to manufacturers and industry standards of use and application. Where feasible and practicable use roadway deicers, such as sand, calcium chloride, magnesium acetate, potassium acetate, or similar materials, that cause less adverse environmental impact than urea, and sodium chloride. Store and transfer de/anti-icing materials on an impervious containment area in a manner that ensures the material does not enter storm or natural drainage systems. Sweep/clean up accumulated delanti-icing materials and grit from roads -J as soon as possible after the road surface clears. Minimize use in areas where runoff or spray from the roadway immediately enters sensitive areas such as fish -bearing streams. January 2005 King County Stormwater Pollution Prevention Manual J 1 Street Deicing Operations (continued) The following BMPs are optional unless the above minimum required BMPs do not provide adequate source control: Intensify roadway cleaning in early spring to help remove particulates from road surfaces. Include limits on toxic metals in the specifications for de/anti-icers. For more information or assistance in implementing these best management practices, contact the King County Department of Natural Resources and Parks Water and Land Resources Division at 206-296-1900. Reader Now The above requirements are the minimum required BMPs. If these BMI's fail to prevent discharges to the storm drainage system, you will be asked to take additional measures to correct the continued pollution discharges. King County Stormwater Pollution Prevention Manual January 2005 Maintenance of Drainage Systems Many commercial, industrial, residential and. public agency properties have storm drainage flow control and water quality systems to capture and treat stormwater flows. Most of these systems have catch basins as key components. Catch basins are typically located along curbs, at low spots in parking lots, and where stormwater conveyance pipes combine flows:. Storm drains collect runoff that directs flows into basins and pipes that are located underneath parking lots and storm drain grates. Most catch basins have a few feet of storage in the bottom or sump. This storage area is intended to trap sediment, debris, and other particulates that settle out of stormwater, to prevent clogging of downstream pipes and to keep solids from being flushed into receiving waters. Anyone who has ever looked into a catch basin can attest to its ability to capture dirt, leaves, twigs, litter, and a variety of other materials that make for a mucky buildup in the bottom. However, if the sump (the bottom of the catch basin) is full of solid material, everything in the 1 incoming runoff passes straight through to an outflow pipe. The bottom (or sump) in catch basins must be cleaned out periodically so they can continue to trap solids from stormwater runoff. Routine maintenance practices at all sites with storm drains and catch basins must include cleaning/removal of sediment or solids from these important drainage system features. if catch basins are not cleaned, they can actually contribute to receiving water pollution problems as trapped solids, and stagnant, polluted water in sumps can be flushed out in large quantities with turbulent storm flow conditions. l - Check your catch basins regularly for needed maintenance (at a minimum twice a year) Once during the dry summer months and once prior to the rainy season: As a rule of thumb, catch basins must be. cleaned out when the solids, trash, and debris in the sump reaches one-third of the i depth between the bottom of the sump and the bottom (invert) of the lowest inflow or outflow pipe connected to the catch basin. This is the level at which flushing of pollutants can be a problem. The rate at which a sump fills with solid material is quite variable, and depends on the characteristics of the drainage basin feeding into it. If activities that generate a lot of sediment are taking place in the drainage area that contributes stormwater flows to a catch basin, such as exposing soils due to construction or landscaping, stockpiling erodible materials, or if your site is not paved and has heavy traffic use on dirt or gravel surfaces, the sump will fill up relatively quickly. Therefor, sites with activities generating a lot of sediments and other debris will have to clean out their catch basins more often. January 2005 King County Stormwater Pollution Prevention Manual _J `j BMP Info Sheet #7, Maintenance of Dralnage Systems (continued) Other components of drainage systems include ponds, tanks, and bioswales. These components must also be maintained to ensure your drainage systems functions as designed. Vegetation in ponds and bioswales must be mowed or thinned, and sediment accumulations must be removed. Maintenance of ponds, tanks, and bioswales is generally beyond the ability of the typical property owner. Drainage system maintenance contractors are available to complete this work. If you clean out/maintain the catch basins yourself, you may dispose of up to one cubic yard of solid material as solid waste in your regular garbage. if you exceed this threshold you are encouraged to contact a company offering catch basin cleaning services. You can locate a cleaning service by calling the King County Water and Land Resources Division at 206-296- 1900 for a list of firms performing drainage system maintenance services or in your telephone directory's yellow pages under headings like "Sewer Cleaning Equipment and Supplies," "Sewer Contractors," and "Tank Cleaning," All of the solids and stagnant water collected from catch basin sumps must be disposed of properly. None of the sump contents can be flushed into the catch basin outflow pipe. Depending on the nature of the pollutants in the sump, and the associated types of activities taking place on the site, the sump contents may need to be handled as contaminated waste. Contractors who perform catch basin clean -out services are required to follow appropriate disposal requirements, Frequent sweeping of paved parking and storage areas, covering pollutant generating activity areas, and containing runoff from activity areas will help reduce catch basin and drainage system cleaning frequency, and may save time and money spent on required maintenance. All businesses and public agencies should set up maintenance schedules for all of their BMPs so that coordinated BMP efforts result in reduced catch basin and drainage system maintenance and cleaning. January 2005 ling County Stormwa€er Pollution Prevention Manual Water Quality Treatment BMPs Water quality treatment BMP options may be required if operational or basic structural source controls do not adequately address pollutant discharges from your site. Source control BMPs, as presented in Chapter Three, must always be implemented before treatment BMPs are considered. The following information describe some basics of water quality treatment systems/facilities. Design and construction details can be found in the King County Surface Water Design Manual (which contains relevant information for the treatment BMPs discussed). A private vendor specializing in the treatment system or an engineering consultant can provide information on treatment systems. Businesses and agencies are allowed to select a treatment BMP other than those presented in this manual .if they follow the adjustment process as outlined in the King County Surface Water Design Manual or if they complete the Alternative BMP request in this manual. Table 5.2 (next page) presents a brief description of some typical water quality treatment BMPs. Table 5.3 presents water quality treatment BMPs for removing specified pollutants. One treatment BMP usually cannot treat all pollutant problems. Each BMP is designed for a specific purpose and is capable of removing only specified pollutants. If you decide to install a water quality treatment BMP, always ensure that it is removing the pollutant of concern from your site runoff. January2005 King County StormwaterPollution Prevention Manual BMP Info Sheets #8, Water Quality Treatment BMPs (continued) TABLE 5.2 WATER QUALITY TREATMENT BMPs TREATMENT BM.P BRIEF DESCRIPTION Oil/Water Separator An underground vault specifically designed to remove oil and grease. Also will remove floatabl.e and some settleable solids. Catch Basin Insert A filtering device that is installed within an existing catch basin and uses various sorbent materials and settling space to collect pollutants. Catch Basin Sump and Vault Filter A device similar to catch basin inserts, only larger and placed underground. Leaf Compost Filters A filtering device that is installed above or below ground and uses leaf compost to remove pollutants from stormwate.r. Wet Pond, Constructed Wetland, A. wet pond is a stormwater pond that retains a permanent pool of Wet Vault water. A constructed wetland is similar to a vet pond, but shallower and supporting wetland vegetation in large areas. A wet vault is an underground, covered, engineered Structure that retains a permanent pool of water. Vegetated Biofilter - Biofiltration A biofiltration swale is a long, gently sloped ditch or depression Swale and Filter Strip designed to treat water as it passes through the vegetation. Grass is the most common vegetation. A filter strip is a grass area, wider than biofilters, also with gentle slopes. Water usually enters as sheet flow from the adjacent pavement. Sand Filter A structure placed in the landscape, with grass grown on top, or in vaults. Stormwater passes through the sand allowing particulate pollutants to be filtered out. Infiltration A normally dry basin which temporarily stores stormwater until it soaks through the bottom and sides of the basin, and .infiltrates into surrounding soil. January 2005 King County Soormwater Pollution Prevention Manual BMP Info Sheets #S, Water Quality Treatment BMPs (continued) TABLE 5.3 APPROPRIATE USES FOR WATER QUALITY TREATMENT BMPs POLLUTANTS TO REMOVE Oil/Grease Sources: vehicle and equipment areas, industrial areas, food preparation Sediments/Solids Sources: sand/gravel storage, construction sites, unpaved areas, agriculture/livestock uses APPROPRIATE TREATMENT BMPs Oil/water separators; catch basin inserts; catch basin sump/vault filters, leaf compost filters. For coarse sediments -Wet pond/vault; constructed wetland (with forebay); vegetated biofilter; sand filter; catch basin insert; catch basin sump/vault filters; leafcompost filters. For fine sediments. -Wet pond/vault; constructed wetland (with forebay); vegetated biofilter; sand filter. Also see catch basin sump/vault filters. Phosphorus Compounds For particulate phosphorus -Wet pond/vault; constructed Sources: detergents/cleaners, fertilizers, wetland (with forebay); vegetated biofilter; sand filter. If organic matter, animal wastes dissolved phosphorus must also be removed - a large "oversized" wet pond or sand filter. Nitrogen Compounds For particulate nitrate -Wet pond/vault; constructed wetland Sources: fertilizers, animal wastes, organic (with forebay); vegetated biofilter; sand filter. For dissolved matter nitrate - constructed wetland. Metals For particulate metals -Wet pond/vault; constructed wetland Sources: industrial areas, vehicle and (with forebay); vegetated biofilter; sand filter. For dissolved equipment areas, paints, pesticides metals - leaf compost filter or constructed wetland. Fecal Coliform Bacteria There is no treatment BMP that can reliably reduce fecal Sources: animal wastes; fertilizers conform bacteria to acceptable levels. Some studies have shown constructed wetlands provide some benefit. pH A constructed wetland can neutralize some ranges of pH. Sources: metal plating, printing/graphic industries, cementiconcrete production, cleaners BOD and Trace Organics For particulate BOD - see "particulate nitrate" above. For Sources: organic debris, food wastes, some dissolved BOD -A constructed wetland will remove some chemical wastes dissolved BOD and trace organics; more reliable performance requires activated carbon. January 2005 King County Stormwater Pollution Prevention Manual Section Five t J ._ J .ti r s W Section 5—Conveyance System Analysis and Design Hydrology The modified rational method was used to calculate tributary runoff volumes per the criteria outlined in section 3.2.1 of the :1995 KCSWDM, detailed analysis and catch basin flows can be found in Appendix C.1 of Section 5. The conveyance system was designed to convey the 25-year storm event without overtopping drainage structures. A backwater analysis was conducted and demonstrates that both the 25-year and 100-year storm events are contained within our onsite conveyance system. Overtopping of the conveyance system may occur for events larger than the 100-year storm event. Any stortnwater discharged as a result of overtopping will continue to flow to its respective target threshold discharge area. Hydraulics Pipe sizes and slopes have been established to convey the 25-year storm event; design information is given in the construction plan set. Panther Lake Elementary School TIR 22 otak KAVwjen\3110011147A\ tpons%VM'I'Mj.doc Appendix C. I— East 25 Year Backwater Analysis 9 205 . bw.p 31.00 18.00 1 251.20 251.35. 254.50 93.00 4.00 0.000 84.00 18.00 1 251.35 251.52.' 264-80 77.00 4.00 0.000 57.00 18.00 1 251.52 251.91 263.82 90.00 4►0.0 0.867 14.00 18.00 1 251.91, 251..99 263.60 0.00 4.00 0.000 12..00 18.00 .1 254..18 . 254.34 263.38 6.00 4.00 0.291. 41,00 12.00 1 254.67 263.07 23.00 4.00 0.000 53.00 12.00 1 257.86 258.1.3 262.52 6.00 4.00 0.075 84.00 12.00 1 258.13 258.55 262.40 51.00 4.00 0.027 72.00 12.00 1 258.55 258.90 Page 1 205.bwx 8 Mainmenui:Perform Backwater on PIPES 205..bwp Pipe Filename F broad -crested weir at intermediate junctions F UTW:USe HW/Tw File for, Tailwater 252.700 Tailwater elevation [only read when UTW=False] (specify) Tailwater Filename [only read when UTW=True] 5.84000 minimum discharge 5.84000 Maximum discharge 1.00000 discharge Increment 205.doc Documentation Filename (specify) for NONE 1 1=standard,2=condensed,3=Expanded output 1 1=no weir,2=Broad,3=Sharp 262,7000 overflow Elevation --0.999990E+15 Weir Length [used only for Broad/sharp weirs] 0.999990E+15 weir Height above overflow [used only for Broad/sharp weirs] T UVF:Upstream Velocity Fixed? 3.00000 Upstream velocity [used only for UVF=True) -0.999990E+15 Channel width [used only for UVF=False] 0 Return to Main Menu 15 MainMenu:E.xit KCBW Program Page 1 BACKWATER COMPUTER PROGRAM FOP PIPES Pipe data from file:205.bwp Surcharge condition at intermediate junctions } Tailwater Elevation:252.7 feet Discharge Range:5.84 to 5.84 Step of 1. Eefs1 Overflow Elevation:262.7 feet Weir:NONE Upstream Velocity:3. feet/sec PIPE NO. 1: 31 LF 18"CP @ 0.40% OUTLET: 251.20 INLET: 251.35 INTYP: 5 JUNC NO. 1: OVERFLOW -EL: 254.50 BEND: 90 DEG DIA/WIDTH: 4.0 Q-RATIO: 0.00 1 Q(CFS) HW(FT) HW ELEV. * N-FAC DC DN TW DG DE HWO HWI 5.84 1.74 253.09 * 0.012 0.94 0.96 1.50 1.50 1.42 1.74 1.49 PIPE NO, 2: 84 LF - 18"CP 9 0.20% OUTLET: :251.35 INLET: 251.52 INTYP: 5 JUNC NO. 2: OVERFLOW -EL: 264.80 BEND: 77 DEC DIA/WIDTH: 4:6 Q-RATIO: 0.00 Q(CPS) HW(FT) HW ELEV. * N-FAC DC DN TW DO DE HWO HWI wwww*k*ww*wwwwwkw**x#x#*aewwwwww*wwwww*kwwwwkxirwwwirxwwkwxxxxk*wwxxx*xwwwwwx*xwwx 5.84 2.05 253.57 * 0.012 0.94 1.50 1.74 1.74 1.79 2.05 1.44 PIPS NO. 3: 57 LF - 18"CP 4 0.68% OUTLET: 251.52 INLET: 251.91 INTYP: 5 JUNC NO. 3: OVERFLOW -EL: 263.82. BEND: 90 DEG DIA/WIDTH : 4.0 Q-RATIO: 0.87 J Q(CFS) HW(FT) HW ELEV. * N-FAC DC ➢N TW DO DE HWO HWI *wxwwxxwxwwk**ww*wwww*:r***********wwww*xwwx:�***�rx�r**x*xx*w*xx*xkx**x**k;r**xwx** I 5.94 2.10, 254.01 * 0..012 0.94 0.86 2.05 2.05 1.81 2.10 1.47 j PIPE NO. 4: 14 LF - 16"CR g 0.50% OUTLET: 251.91 INLET: 251.98 INTYP: 5 } JUNC NO. 4i OVERFLOW -EL: 263.60 BEND: 0 DEG DIA/WIDTH: 4.0 Q-RATIO: 0.00 1 Q(CFS) HW(FT) HW HLEV. * N-FAC DC DN TW DO DE HWO HWI kwx**wk*k*ww*x*k***wkwwxwxw***xw*wwwwwkk*wxkw*www**�rwww***kwwwxwwx*xx***ww*wx** 3.13 2.08 254.06 * O.Q12 0.68 0.65 2.10 2.10 2.05 2.08 0.91 PIPE NO. 5: 12 LF - 18"CP Q 0.50% OUTLET: 254.28 INLET: 254.34 INTYP: 5 JUNC NO. 5: OVERFLOW -EL: 263.38 BEND: 6 DEG DIA/WIDTH: 4.0 Q-RATIO: 0.29 Q(CFS) HW(FT) HW ELEV. * N-FAC DC DN TW DO DE HWO HWI ;r**k**wxw*war*ww**;twwxxw:�wv�x�►�e�r*w****x*xx*x**wxw*******xx**x***x,rw,�*www ►*kw***kx 3.13 0.85 255.19 * 0.012 0.66 0.65 0.00 0.65 0.68 ***** 0.85 PIPE NO. 6: 41 LF - 1211CP 9 7.181 'OUTLET: 254.67 INLET: 257.86 INTYP: 5 JUNC NO. 6: OVERFLOW -EL: 263,07 BEND: 23 DEG DIA/WIDTH: 4.0 Q-RATIO: 0:00 Q(CFS) HW(FT) HW ELEV. * N-FAC DC DN TW DO DE HWO HWI 2.42 0.89 258.75 * 0.012 0.67 0.33 0,52 0.52 0.67 PIPE NO. 7: 53 LF - 12"CP @ 0.51W OUTLET: 257.86 INLET: 258.13 INTYP: 5 JUNC NO. 7: OVERFLOW -EL:. 262.52 BEND: 6 DEG DIA/WIDTH: 4.0 Q-RATIO: 0.08 Q (CFS ) HW ( FT) HW ELEV. N-FAC DC DN TW ➢O DE HWO Hwi 2.42 0.98 259.11 * 0.012 0.67 0.73 0.89 0.89 0,79 0.98 0.94 PIPE NO. 6: 64 LF - 12"CP @ 0.50-k OUTLET: 258.13 INLET: 258.55 INTYP: 5 JUNC NO. 8: OVERFLOW -EL: 262.4.0 SEND: 51 DEG DIA/WIDTH: 4.0 Q-RATIO: 0.03 Q(CFS) HW (FT) HW ELEV. * N--FAC DC DN TUT DO DE HWO HWI 2.25 1.00 259.55 * 0.012 0.65 0.70 0.98 0.98 0.80 1.00 0.94 PIPE NO. 9: 72 LF - 12"C'P @ 0.494 OUTLET: 250.55 INLET: 2:58.90 II+7TYP: 5 Q(CFS) HW(FT) HW ELEV. * N-FAC DC DN TW DO DE HWD HWI 2.19 0.93 259.83 * 0.012 0.64 0.69 1.00 1.00 0.85 0.93 0.84 01 216.bwp 15.00 18.00 1 254.34 254.41 Page 1 216.bwx 8 MainMenu:Perform Backwater on PTPE5 216.bwp Pipe Filename F broad -crested weir at intermediate junctions F UTW: Use Hw/TW File for' Tailwater 255.190 Tailwater elevation [only read when UTw=False] (specify) Tailwater Filename [only read when UTW=True] 0.71000 minimum discharge 0.71000 Maximum discharge 1.00000 discharge Increment 216.doc Documentation Filename (specify) for NONE 1 1=Standard,2=condensed,3=Expanded 1 1=no weir,z=Broad,3=sharp 263.4000 overflow Elevation -01.999990E+15 weir Length [used -0.999990E+15 weir Height above overflow [used T UVF:Upstream Velocity Fixed? 3.00000 Upstream Velocity fused only for -0.999990E+15 channel Width [used only for 0 Return to Main Menu 15 MainMenU:EXit KCBW Program Page. 1 output only for Broad/Sharp weirs] only for Broad/Sharp,weirs uvF=True] UVF=False] 'BACKWATEP, COMPUTER PROGRAM FOR PIPES Pipe data from file:216.b'Wp Surcharge- coaditior, at intermediate junctions Tailwater, tftevati0n:255.19feet Dischazqe Ranqe-0;.'71 to '0.71 Step of 1. [cfal overflow glevation:2-61.4 feat Weirt:XONE t1patream Velocityx3. feet/sec PIPE NO. 1z 15 1w - 180:0 0: 0.i47k OUTLET: 2'54.34 iNTAT: 254-41 INTY'?; 5. 0 (CFE0, HW (PT), HW ELEV. N-VAC DC DbY TW bo, DE awo, HWI 0.71 0-79 255.20 0.32 0-31 0.85 0.85 0,79 0.46 0.31 01 217.bwp 42.00 12.00 1 252.80 254.41 Page 1 217.bwx 8 MainMenu:Perform Backwater on PIPES 217.bwp Pipe Filename F broad -crested weir at intermediate junctions F uTw. Use HW/TW File for Tailwater 253.800 Tailwater elevation [only read when UTW=False]' (specify) Tailwater Filename [only read when UTW=True] 2.48000 minimum discharge 2.48000 Maximum discharge 1.00000 discharge Increment 217.doc Documentation Filename (Specify) for NONE i 1=standard,Z=condensed,3=Expanded 1 1.=no weir,2=Broad,3=sharp 263.4000 overflow El-evation -0.999990E+15 Weir Length [used --0.999990E+15 weir Height above overflow [used T UVF:Upstream velocity Fixed? 3.00000 Uppstream Velocity [used only for -0.993990E+15 Ci�annel Width [used ❑nly for 0 Return to Main Menu 15 MainMenu.Exit KC6W Program Page 1 Output only for Broad/Sharp weirs] only far Broad/sharp weirs] UVF=Tru0] UVF=Fa7 se] BACKWATER COMPUTER PROGRAM FOR PIPES Pipe, data from file:217.bu? Surcharge condition at intermed�ate junctions Tailwater Rlevation:253.8 feet Discharge Range,2,48: to, 2.48 Stop of I. [v-fa] Overflow BlevatiQu:201.4 feet Weir -.NOUN 1�pstxpam Velacity--3, ,Meet/sea PIPE $0 - 142 LF � 1211CP 0 3.834s OUTL'9T: 252.80 INLET: 254.41 INTYP- S Q (CFS) HW (PT-) EW Al�RV. -'Tq-FAC bC M TT -DO DO HWO Hwl 2.48 0-91 255-32 * 0.01Z 0.60 6.40 1.00 140 0.68 2z0.bwp 05 73.00 12.00 1 252.4.1 256.89 261.99 68.00 4.00 0.265: 95.00 12.00 1 257.00 257.43 262.31 0.00 4.00 0.000 5..2.00 12.00 1 257.31 257.57 262,00 45.00 4.00 9.364 50.00 8.00 1 257.90 258.20 262.00 45.00. 4.00 0.000 68.00 8.00 1 258.20 258.73 Rage 1 220.bwx 9 MainMenu:Perform Backwater on PIPES 220.bwp Pipe Filename F broad -crested weir at Intermediate junctions F UTW:Use HW/Tw File for Tailwater 254.01 Tailwater elevation [only read when UTW=False] (specify) Tailwater Filename [only read when UTW=True] 2.31000 Minimum discharge 2.31000 Maximum discharge 1.00000 discharge increment 220.doC Documentation Filename (specify) for NONE 1 1=standard,2=condensed,3=Expanded output 1 1=no weir,2=aroad,3=Sharp 263.0000 overflow Elevation -0.999990E+15 Weir Length [used only for Broad/Sharp weirs] -0.999990E+15 weir Height above overflow [used only for Broad/sharp weirs] T UVF:Upstream Velocity Fixed? 3.00000 upstream velocity [used only for UVF=True] -0.999990E+15 channel width [used only for UVF=False] 0 Return to Main Menu 15 MainMenu:Exit KCBW Program Page 1 BACKWATER COMPUTER PROGRAM FOR PIPES Pipe data from file:220.bwp Surcharge condition at intermediate }.unctions -? Tailwater Elevation:254.01 feet Discharge Range-2.31 to 2.31 Step of 1. (Cfs] Overflow Elevation:263. feet _ Weir:NONE Upstream Velocity:3. feet/sec PIPE NO. 1: 73 LF - 12"CP @ 6.14% OUTLET: 252.41 INLET: 256.89 INTYP: 5 JUNC NO. 1: OVERFLOW -EL: 261.89 BEND: 68 DEG DIA/WIDTH: 4.0 4-RATIO: 0.26 Q(CFS) HW(FT) HW ELEV. * N-.FAC DC DN TW DO DE HWO HWI 2.31 0.99 257.88 * 0.012. 0.66 0.34 1.60 1.60 0.66 ***** 0.99 PIPE NO. 2: 85 LF - 12"CP @ 0.51% OUTLET: 257.00 INLET: 257.43 INTYP: 5 JUNC NO. 2: OVERFLOW -EL: 262.31 BEND: 0 DEG DIA/WIDTH: 4.0 Q-RATIO: 0:00 i ! Q.(CF5) HW (FT) HW ELEV, * N-FAC DC DN TW DO DE HWO HWI i 1.83 0.91 258.34 * 0.012 0.58 0.60 0.88 0.88 0.63 0.91 0.96 ee PIPE NO. 3: 52 LF - 12!'CP @ 0.50% OUTLET: 257.31 INLET: 257.57 INTYP: 5 1 JUNC NO. 3: OVERFLOW -EL: 262.00 BEND: 45 DEC, DIA/WIDTH: 4.0 Q-RATIO: 9.36 Q(CFS) HW(FT) HW ELEV. * N-FAC DC DN TW DO DE HWO HWI **********,rx***�ti�***x�r*N*xx*x*********x***:k******x,►*,�**sk*�-x*x******�r**x***x**x* 1.83 1.02 258.59 * 0.012 0.59 0.60 1.03 1.03 0.87 1.02 0.87 -� PIPE NO. 4: 60 LF - 8"CP @ 0.50% OUTLET: 257.90 INLET: 258.20 INTYP: 5 TuNC NO. 4: OVERFLOW -EL: 262.00 BEND: 45 DEG DIA/WIDTH: 4.0 Q-RATIO: 0.00 Q(CFS) HW(FT) HW ELEV. * N-FAC DC DN TW DO DE HWO HWI 0.18 0,42 258.62 * 0.012 0.20 0.20 0,69 0.69 0.41 0.42 0.26 PIPE NO. 5: 68 LF - 8"CP @ 0.780 OUTLET: .258.20 INLET: 258,73 INTYP: 5 1 Q(CFS) HW (FT) HW ELEV, * N- FAC DC D14 TW DO DE XWO HWI 0.18 0.20 258.93 * 0.012 0.20 0.18 0.42 0.42 0.26 ***** 0.18 03 roo 27.00 12.00 1 257.57 257.71 260.80 89.00 4.00 3.997 42.00 8.00 1 258.04 259.13 261.80 39.00 4.00 0.742 108.00 12.00 1 259.13 263.02 Page 1 300 . bwx 8 MainMenu:Perform Backwater on PIPES 300 . bwp Pipe Filename F broad -crested weir at Intermediate junctions F u`rw•use HW/Tw Fite for Tailwater 258.590 Tailwater elevation [only read when uTw=False] (specify) Tailwater Filename [only read when LTw-True] 1.66000 Minimum discharge 1.66000 Maximum discharge 1.00000 discharge Increment 300.doc Documentation Filename (specify) for NONE 1 l�standard,2=condensed,!=Expanded 1 I=no weir,2-Broad,3wsharp 265.6900 overflow Elevation -0.999990E+15 weir Length [used -0.999990E+15 weir Height above overflow [used T uvF:upstream velocity Fixed? 3.00000 Upstream velocity [used only for -0.999990E+15 channel width [used only for 0 Return to main Menu 15 Mainmenu:Exit KCBW Program Page 1 outpt4t only for Broad/Sharp weirs] only for Broad/sharp weirs] UVF=True] UVF=Falsel BACKWATER COMPUTER PROGRAM FOR PIPES Pipe data from file:.300.bwp Surcharge condition at intermediate junctions Tail.water Elevation.:258.59 feet Discharge Range:1.66 to 1.66 Step of 1. [efsj Overflow Elevation:265.69 feet Weir:NONE Upstream Velocity:3: feet/sec PIPE NO. 1: 27 LF - 1211CP b 0.52% OUTLET: 257.57 INLET: 257.71 INTXP: 5 Jt3NC NO. 1e OVERFLOW -EL: 260.80 BENDi- 89 DEG DIA/WIDTH: 4.0 Q-RATIO: 4.00 Q(CFS) HW(FT) HW ELEV. * N-VAC DC DN TW DO DE HWo HWI 1.66 1.06 258.77 0.012 0.55 0.56 1.02 1.02 0.93 1.06 0.83 PIPE NO. 2: 42 LF - B"CP C 2.606 OUTLET: 258.04 INLET: 259.13 NTYP: 5 JUNC NO. 2z OVERFLOW -EL: 261.60 BEND: 39 DEG DIA/WIDTH. 4.0 Q-RATIO: 0.74 Q(CFS) HW(FT) HW ELEV. * N-FAC DC DN TW DO DE HWO HW.X: 0�33 0.37 259.50 0.012 0.27 0.18 0.73 0.73 0-27 ***** 0.37 ;PIPE NO. 3: 108 LF - 121JCP @ 3.60% OUTLET: 259.13 INLET: 26.3.02 INTYP: 5 Q(CFS) HW (FT) HW ELEV. * N-FAC DC DN TW DO DE HWO HWI 0.19 0.18 263.20 * 0,012 0.18 0.1.2 0.37 0.37 0.18 **** 0.12 500.bwp 01 42.00 18.00 1 254.65 254.86 Page 1 500.bwx 8 MainMenu:Perform Backwater on PIPES 500.bwp Pipe Filename F broad -crested weir at Intermediate junctions F UTW:Use HW/TW File for' Tailwater 255.200 Tailwater elevation [only. read when UTW=False] (specify) Tailwarer Filename [only read when UTW=True] 3.185000 Minimum discharge 3.185000 maximum discharge 1.00000 discharge increment 500.doc Documentation Filename (specify) for NONE 1 1=standard,2=Condensed,3=Expanded I 1=no weir,2=Broad,3=sharp 263.6500 overflow Elevation 0.999990E+IS weir Length [used -0.999990E+15 weir Height above overflow [used T UVF:upstream velocity Fixed? 3.00000 Upstream Velocity [used only for -0.999990E+15 Channel width [used only for a Peturn to Main Menu 15 MainMenu:Exit KCBW Program Page 1 output only for Broad/Sharp weirs] only for Broad/sharp weirs] UVF=True] UVF=False] BACKWATER COMPUTER PROGRAM FOR PIPE$ Pipe data from fille445070.bwp surchatge condirlon at lht6rmediate NndtiO", Tailwat*;r Xlevation:255.2 feet Dis .,ohar_qe: R.-mge-3.185 to 3,185 Step of 1. [cfr.] overf lbw 'g-levation,263.65 feet Wejr;NQNE: feet/sed PIPS 'NO. 1. 4�2 LF 9"0 0.50,W OUTLET. :254.65' INLET: 254.8:6 INTYP.- 5 -Q (CVS) $W (VTaW ELEV. *'N-FAC DC DX TW DO D8 RVO UK Q-'83 255-.69 0-012 0.68 G-66 0.55 0-66 b46.8 This page left intentionally blank for double -sided printing. I s Appendix C.2—East 100 Year Backwater Analysis This page left intentionally blank for double -sided printing. WK 2Q5. bwp 49 31.00 1.8.00 1 251.20 251.35 254.50 93.00 4.00 0.000 84.00 18.00 1 251.35 251.52 2654.80 77.00 4.00 0.000 57.00 18.00 1 251.52 251r31 263.82 90.00 4.00 0.906 14.00 18.00 .1 251.91 251.98 263.60 0.00 4.00 0.000 12.00 18.00 1 254.28 254.34 263.38 6.00 4.00 0.236 41.00 12.00 1 254.67 257.86 2636:07 23.00 4.00 0.000 53.00 12.00 1 257.86 258.13 262.52 6.00 4.00 0.075 MOO 12.00 1 258.13 258.55 262.40 51.00 4.00 0.027 72.00 12.00 1. 258.55 258 90 Page I 205.bwx 8 MainMenu:Rerform Backwater on PIPES 205.bwp Pipe Filename F broad -crested weir at intermediate junctions F UTW:Use HW/TW File for Tailwater 252.700 Tailwater elevation [only real when UTW=Fa1se] (specify) Tailwater Filename [only read when uTW=True] 7,03000 Minimum discharge 7.03000 Maximum discharge 1.00000 discharge increment 205.doC Documentation Filename (specify) for NONE 1 1=standard,2=condensed,3=Expanded I 1=no weir,2=Broad,3=Sharp 262.7000 overflow Elevation -0.999990E+15 weir Length [used -0.999990E-15 weir Height above overflow [used T UVF:Upstream Velocity Fixed? 3.00000 Upstream velocity [used only for -0.999990E-15 channel Width fused only for 0 Return to Main Menu 15 MainMenu:Exit KCBW Program Pag e 1 output only for Broad/sharp weirs] only for Broad/sharp weirs] UVF True] UV F= Fal s e] _ BACKWATER COMPUTER PROGRAM FOR PIPES + Pipe data from file:205.bwp I Surcharge condition at intermediate junctions _1 Tailwater Elevation:252.7 feet Discharge Range;7.03 to 7.03 Step of I. [cfs] Overflow Elevation:262.7 feet Weir:NONE Upstream Velocity;3. feet/sec PIPE N.O. 1: 31 LF - 18"CP @ 0.48t OUTLET: 251.20 INLET: 251.35 INTYP: 5 JUNC NO. 1: OVERFLOW -EL: 254.50 BEND: 90 DEG DIA/WIDTH: 4.0 Q-RATIO: 0.00 Q:(CFS) HW(FT) HW ELEV. N-FAC DC DN TW DO DE HWO HWI 7.03 1.91 253.26 * 0.012 1.03 1.11 1.50 1.50 1-46 ,1.91 1.72 PIPE NO. 2: 84 LF - 18"CP @ 0.20% OUTLET: 251.35 INLET, 251.52 INTYP:.5 JUNC NO. 2: OVERFLOW -EL: 264.80 .BEND: 77 DEG DTA/WIDTH: 4.0 Q-RATIO: 0,00 Q(CFS) HW(FT) HW ELEV. "` N-FAC DC PN TW DO DE HWO HWI 7.03 2.43 253.95 * 0.012 1.03 1.50 1.91 1.91 2.06 2.43 1.64 PIPE NO. 3: 57 LF - 18"CP L 0.68% OUTLET: 251.52 INLET: 251.91 INTYP: 5 JUNC NO. 3: OVERFLOW -EL: .263.82 BEND: 90 DEG DIA./WIDTH: 4.0 Q-RATIO: 0.91 Q(CFS) HW(FT) HW ELEV. * N-FAC DC DN TW DO DE HWO HWI J 7.03 2.70 254.61 * 0,012 1.03 0.97 2.43 2.43 2.27 2.70 1.70 PIPE NO. 4: 14 LF - 18"CP @ 0.50%- OUTLET: 251.9i INLET°: 251.98 INTYP: 5 JUNC NO. 4: OVERFLOW -EL: 263.60 SEND: 0 DEG DIA/WIDTH: 4-0 Q-RATIO: 0.00 _1 Q(CFS) HW(FT) HW ELEV. * N-FAC DC DN TW DO DE HWO HWI 3.69 2.69 254.67 * 0.012 0.74 0.72 2.70 2.70 2.65 2.69' 0.99 J y -PIPE NO. 5. 12 LF - 18"CP @ 0.50% OUTLET: 254.28 INLET: 254.34 INTYP: 5 JUNC NO. 5. OVERFLOW -EL: 263.38 BEND: 6 DEG DIA/WIDTH: 4.0 Q-RATIO: 0.24 Q(CFS) F1W(FT) TAW ELEV. * N-FAC DC DN TW DO DE HWO HWI 3.69 0.88 255.22 0.012 0.74 0.72 0.39 0.72 0.74 PIPS NO. 6: 41 LF - 1211CP 9 7.78% OUTLET: 254..67 INLET.- 257.86 INTYP: 5 JUNC NO. 6: OVERFLOW -EL: 263.07 BEND: 23 DEG DIA/WIDTH: 4.0 Q-RATIO: 0-010 Q(CFS) HW(FT) HW ELEV. * N-FAC DC DN TW DO OF HWO awi 2.96 1.01 258.87 * 0.012 0.75 0.36 0.55 0.55 0.75 ***** 1.01 PIPE NO. 7: 53 LF - 12."CP @ 0.5:1% OUTLET:,257,86 INLET: 258.13 INTYP: 5 JUNC NO, 7: OVERFLOW -EL: 262.52 BEND: 6 DEG DIA/WIDTH: 4.0 Q-RATIO: 0.08 Q(CFS) HW(FT) HW ELEV. * N-FAC DC: DN TW DO DE IWO HWI 2.98 1.22 259.35 * 0.012 0.75 1.00 1.01 1.01 1.06 1<22 1.06 PIPE NO, 8: 84 LF - 1211CP @ 0.50% OUTLET: 258.13 INLET: 258.55 INTYP: 5 JUNC NO. 8: OVERFLOW -EL: 262.4.0 BEND: 51 D,EG DIA/WIDTH: 4.0 Q-RATIO: 0.03 Q(CFS) HW(FT) HW ELEV. * N-FAC DC DN TW DO DE HWO HWI **,r*it*xxarx.*�r,r*:t,x***:tx*xfx*x:�#xv:�*,►****x**,rx*****tax*�r***:rx+r**-��x�w**x*xv**x***�r* 2.78 1.43 259.98 * 0.012 0.72 0.84 1.22 1,22 1.23 1.43 1.07 PIPE NO. 9: 72 LF - 1211CQ 0 0.49% OUTLET: 258.55 INLET: 258.90 INTYP: 5 Q(CFS) HW(FT) HW ELEV. * N-FAC DC DN TW DO DE. HWO HWI ********x*�**�*�****�r******xx**:r*x***x*x*.x*+*x*+..x.*.*�**,�***x,►*x;��r**xx*�r**xx**,r*x 2.70 1.14 260.04 * 0.012 0.71 0.83 1_43 .1.43 1,00 1.14 1.00 216.bwp 01 15.00 18.00 1 254.34 254.41 Page 1 216.bwx 8 MainM.enu.Perform Backwater on PIPES 216.bwp Pipe Filename F broad -crested weir at Intermediate junctions F UTW:USe HW/TW File for Tailwater 255.220 Tailwater elevation [only read when. UTW=False] (specify) Tailwater Filename [only read when UTW=True] 0.71000 minimum discharge 0.71000 Maximum discharge 1.00000 discharge Increment 216.doc Documentation Filename (specify) for NONE I I=5tandard,2=condensed,3=Expanded output 1 I=no weir,2=B.road,3=Sharp 263.4000 overflow Elevation -0.999394E+15 weir Length [used only for Broad/sharp weirs] -0.999990E+15 weir Height above overflow [used only for Broad/sharp weirs] T UVF:Upstream velocity Fixed? 3.00000 Upstream velocity [used only for UVF=True] -0.999990E+15 channel width [used only for UVF=False] 0 Return to Main Menu 15 Mainmenu:Exit KCBW Program Page 1 BACKWATER COMPtM-R PROGRAM FOR PIPES Pipe data from f`11:e-.216,bwP Surcharge condition at intermediate junctions Tailwat6r Elevation:25.5.22 feet Dioch-arge Rango. 0 - 71 to 0. 71 Step of 1, tCf 11 overflow ElevatjOA;2153.4 feet Fa7eir :NONE: Upotteam Velocity:3. feet/geo PIPE NO, 'I - 15 LF - O.47% OUTLET: 254.,:34 rXLM- �54.41 I%MP: 5 Q (CpS) gW (pT) Mq RLIKV. N-FAC DC T)N TW DO DR AND HWI 0.71 0.82 255.23 0,012 0.32 0.31 0.98 0.8,8 0-82 O..4S-q 0.31 -J 01 217.bwp 42.00 12.00 1 252.80 254.41 Page 1 217.bWX 8 MainMenu:Perform Backwater on PIPES Z17,bwp Pipe. Filename F broad -crested weir at intermediate junctions uT a- NW/Tw File for Taz l wat e r F 253.800 Tailwater elevation [only read when UTW=False] (specify) Tai`[water Filename [only read when UTw=True] 2.48000 Minimum discharge 2.48000 Maximum discharge 1..00000 discharge increment 217.doG Documentation Filename (specify) for NONE 1 1 Standard,2=Condensed,3=Expanded 1 1=no weir,2=Broad,3=Sharp 263.4000 overflow Elevation 0.999990E+15 Weir Length [used -0.999990E+15 weir Height above overflow [used T uvF:upstream velocity Fixed? 3.00000 upstream velocity [used ❑nly for -0.999990E+15 Channel width [used only for 0 Return to Main Menu 15 mainMenu:Exit KCBW Program Page 1 output only for Broad/sharp weirs] only for Broad/sharp weirs] uvF=Truel UVF=False] BACKWATER COMPUTER PROGRAm FOR PrPHS Pipe data from file:217.bwp Surcharge condition at intermediate Junctions Tailwater Elevationc251.8 feet Discharge Range:2.48 to 2:.48 Step of 1. tr-te7 overflow Dlevation.263.4 .feet Weir- : NONE Upstream Velb.city:.1. feetjoeC -PT-PH NO. 1; 42 T,F - 12"CP 9 3...83W OUTLET: 252.80 INLET: 2,54.41 IWTYP: 9 Q (CFs) xW (ST) HW HLEV r N-FAC DC DN TW DO DE HWO HW1 iF�at*.*.7Fat*#�**�**,t�;i�atfrx�r*i4*t�s+t:ttiFt#�*ic.%Abe*rtr��#*�irieatttyr*te�iA�F3F�'�*1r�i'�YitlkRyrtk.*YF�y:it�*4c-k 2.4 , 6.91 2.55.32 * 0.012 0.6.8 0.40 1.60 1..00. 0.68 05 73.00 12.00 1 2.61.89 68.00 4.00 85.00 32.00 1 262.31 0.00 4.00 5L00 12.00 1 262..00 45.00 4.00 60.00 8.00. 1 2.62.0D 45.00 4.00 69.00 slog 1 J I i J i 220.bwp 252.41 256.89 0.265 257.00 257.43 0.000 257.31 257.57 9.364 257.90 258.20 0.000 258.20 258.73 Page I 220.hwx 8 MainMenU:Perform Backwater on PIPES 220.bwp Pipe Filename F broad -crested weir .at intermediate junctions F UTW:Use NW/TW File for Tailwater 254.61 Tailwater elevation [only read when UTW=False] (specify) Tailwater Filename [only read when UTN-True] 2.85000 Minimum discharge 2.85000 maximum discharge 1.00000 discharge Increment 220.doc Documentation Filename (specify) for NONE 1 1=Standard,2=Condensed,3=Expanded 1 1=no weir,2=Broad,3=5harp 263.0000 Overflow Elevation -0.999990E+15 weir Length [used -0.999990E+15 Weir Height above overflow [used T UVF:Upstream velocity Fixed? 3.00000 u stream velocity [used only for -0.9999.90E+15 Cannel width [used only for 0 Return to Main Menu 15 Mainmenu:Exit KCBW Program Page 1 output only for Broad/sharp weirs] only for Broad/sharp weirs] UVF=True] UVF=False] �1 BACKNATER COMPUTER PROGRAM FOR PIPES Pipe data from file:220_bwp Surcharge condition at intermediate junctions i Tailwater Elevation:254.El feet II Discharge Range:2.65 to 2.85 Step of 1. [cfs] Overflow Ele`vation:263. feet Weir -NONE -Upstream Velocity:3. feet/sec PIPE NO. 1: 73 LF - 12'tCP 6.141 OUTLET: 252.41 INLET: 256.89 INTYP: 5 ,TUNC NO. 1: OVERFLOW -EL: 261.89 BEND: 6B DEG DIA/WIDTH: 4.0 Q-RATIO: 0_.26 Q(CFS) HW(FT) HW ELEV. * N--FAC DC DN TW DO DE HWO HWl 2.85 1.16 258.05 0_1012 0.72 0.38 2.20 2.20 0.73 ***** 1.16 PIPE NO.. 2: 85. LF - 1211CP @ 0.51% OUTLET: 257-00 INLET: 257.43 INTYP: 5 JUNC NO. 2: OVERFLOW -EL: 262.31 BEND: 0 DEG DIA%WIDTH: 4.0 Q-RATIO: 0.00 Q(CFS) HW(FT) HW ELEV. * N-FAC DC DN TW DO DE HWO HWI *�s*******:�#:t***�*,��r*�r*�**,r***,�***�r**Wit*wW*;r*�:*#*tit*,►,r****fir*�r*#***#**vrx#*+�.�t*#*** 1 2.25 1.10 258.53 * 0.012 0.65 0.69 1.05 1.05. 0.88 1.10 0.99 PIPE NO. 3: 52 LF - 12"CP @ 0.50°s OUTLET: 257,31 INLET: 257.57 INTYP: 5 JUNC NO. 3: OVERFLOW -EL: 262.0.0 BEND: 45 DEG DIA/WIDTH: 4.0 Q-RATIO: 9.36 1 Q(CFS) HW(FT) HW ELEV. * N-FAC DC DN TW DO DE HWO Hwl 2.25 1.34 258.91 `" 0.012 0.65 0.70 1.22 1.22 1.14 1.34 1.00 PIPE NO. 4: 60 LF - 8"CP @ 0.501 OUTLET: 257.90 INLET: .25B.20 INTYP: 5 JUNC NO. 4: OVERFLOW -EL: 262.00 BEND: 45 DEG DIA/WIDTTH: 4.0 Q-RATIO: 0.00 Q(CFS) HW(FT) HW ELEV. * N-FAC DC DN TW DO DE HWO HWI 0.22 0.74 258.94 * 0.012 0.22 0.22 1,01 1.01 0.73 0.74 0.29 PIPE NO. 5: 68 LF - 8"CP @ 0.78%- OUTLET: 25B.20 INLET: 258.73 INTYP: 5 Q(CFS:) HW(FT) HW ELEV. * N- FA.0 DC DN TW` DO DE HWO HWI 0.22 0.27 259.00z 0,012 0.22 0.20 0.74 0.74 0.27 0.19 0.20 03 300, bw'p 27.00 12.00 1 257.57 257.71 260.80 89.00 4.00 3.997 42.00 8.00 1 258.04 259.13 261.80 39.00 4.00 0.742 108.00 12.00 1 259.13 263.02 Page 1 300.bwx 8 MainMenu:perform Backwater on PIPES 300.bwp Pipe Filename F broad -crested weir at intermediate junctions F UTW-USe HW/TW File for Tailwater 258.910 7ailwater elevation [only read when UTW=False] 'f ] (T '1 ter Filename [only read when UTW=True] spec? y ai wa 2.04000 Minimum discharge 2.04000 Maximum discharge 1.00000 discharge increment 300.doc Documentation Filename (specify) for NONE 1 1=5tandard,2=Condensed,3=Expanded 1 1--no weir,2=Broad,3=sharp 265.6900 overflow Elevation --0.999990E+15 weir Length [used -0.999990E+15 weir Height above overflow [used T UvF:Upstream velocity Fixed? 3.0000.0 Upstream velocity [used only for -0.999990E-15 channel Width [used only for ,0 Return to Main Menu 15 Mainmenu:Exit KCBW Program Page 1 output only for Broad/Sharp Frei rs] only for Broad/Sharp weirs]] UVF=True] UVF=Fal Sel BACKWATER. COMPUTER PROGRAM FOR PIPES Pipe data from file:300.bwp Surcharge condition at intermediate junctions Tailwater Slevation:258.91 feet Discharge Range:2.04 to 2.04 Step of 1. (cfsj Overflow Elevation:265.69 feet Weir:IYONE Upstream Velocity-.3. feet/sec PIPE NO. 1: 27 LF - 12"CP @ 0.52% OUTLET: 251.57 INLET: 257.71 INTYP: 5 JU9C NO. 1: OVERFLOW -EL: 260.80 BEND: 8.9 DEG DIA/WIDTH: 4.0. Q-RATIO: 4.00 Q (CFS) HW (FT) HW ELEV. * N--FF,C DC DN TW DO DE HWO HWI 2.04 1.47 2.59.18 * 0.012 0.61 0.64 1,34 1.34 1.28 1.47 0.96 PIPE NO, 2: 42 LF - 811CP @ 2.60% OUTLET: 258.04 INLET: 259.13 INTYP: 5 JUNC NO. 2: OVERFLOW -EL: 261.80 BEND; 39 DEC DIA/WIDTTI: 4.0 Q-RATIO: 0.74 Q (CFS) HW (FT) HW ELEV. * N-FAC DC DN TW DO DE HWO IIWI 0.41 0.42 259.55 * 0.012 0.30 0.20 1,14 1.14 0.30 ***** 0.42 PIPE NO. 3: 1:08 LF - 121ECP @. 3.60% OUTLET: 259.13 INLET: 263.02 INTYP: 5 Q(CFS) HW(FT) HW ELEV, * N-FAC DC DN TW DO DE HWO BWI 0.23 0.20 263.22 * 0.012 0.20 0.13 0.42 0.42 0.20 ***** 0.13 500.bwp Ol 42.00 18.00 1 254.65 254.86 Page 1 500.bwx 8 MainMenu:Perform Backwater on PIPES 500.bwp Pipe Filename F broad -crested weir at intermediate junctions F UTW:Use NW/Tw File foi• Tailwater 255.230 Tailwater elevation [only read when UTW=False] (specify) Tailwater Filename [only read when UTW=True] 3.185000 minimum discharge 3.185000 maximum discharge 1.00000 discharge Increment 500.doc Documentation Filename (specify) for NONE 1 1=5tandard,2=condensed,3—Expanded 1 1=no weir,2=Broad,3=Sharp 263.6500 overflow Elevation -0.999990E+15 weir Length [used -0.999990E+15 weir Height above overflow [used T UVF:Upstream Velocity Fixed? 3..00000 upstream velocity [used only for -0.999990E+15 channel width [used only for 0 Return to Main Menu 15 MainMenu:Exit I(CBW Program Page 1 output only for Broad/sharp weirs] only for Broad/sharp weirs] UVF=Truel UVF=False] BACKWATER COMPUTER PROGRAM FOR 'PIPES Pipe, data. from. file,-500,bvrp Surcharge a,=ditiou at intermediate juntitioxis Tallwater Fliavat;ion!255.23 feet Discharge Range.-1-195, to at HS Step of I. [cfal orverflow Elevatioht263.6S feet Upstream Velacity,.:3. feet/sec PIPE; '-X0. 1: 42 L? - 181'tV 6 0.504 OUT 254.65 19LET: 284.:06 INTYP: 5 iiW.(.FT) -RW ZLEV, *'X-FAC DC DVTW DO liz xmo HW.l 2-55-69 * 0.012 0.68 0.66 0',59 0.66 D.68 __j Appendix C.3— West 25 Year Backwater Analysis WQl.bwp �8. 2.00 12.00 1 262,11 262.12 269.80 0.00 4.00 0.000 2.00 12.00 1 262..12 262.15 268.71 90.00 4.00 1.542 45.00 12.00 1 262.15 .262.37E 268.15 89.00 4.00 0.137 49.00 12.00 1 262,37 262.62 267.15 20.00 4.00 0.126 39.00 12.00 1 262.62 262.8.2 267.00 13.00 4.00 . 0.262 72.00 8.00 1 263.15 263.51 265.50 82.00 4.00 0.404 19.00 8.00 1 263.51 263.60 265.97 89.00 4.00 0.000 65.00 8.00 1 263.60 263..93 I I J J J i Page :1 J i WQ1.bwx B MainMenu:Perform Backwater on PIPES wQ1. bwp Pipe: Fi l en.afne F broad -crested weir at Intermediate junctions F UTW.Use HW/TW File for Tailwater 263.790 Tailwater elevation [only read when UTw=False] (specify) Tailwater Filename [only read when UTW=True] 2.01000 Minimum discharge 2.01000 Maximum discharge 1.00000 discharge Increment wQ1. doC Documentation Filename (Specify) for NONE 1 1=Standard,2=eondensed,3=Expanded output 1 I=no weir,2=13road,3=Sharp 266.0000 Overflow Elevation -4.999990E+15 weir Length [used only for Broad/Sharp weirs] -0.999990E+15 weir Height above overflow [used only for Broad/sharp weirs] T UVF:Upstream velocity Fixed? 3.00000 Upstream velocity [used only for UVF=True] -0.999990E+15 Channel width [used only for UVF=False] 0 Return to Main Menu 15 MainMenu:Fxit KCBw Program Page 1 BACKWATER COMPUTER PROGRAM FOR PIPES Pipe data from file:WQ1.bwp Surcharge condition at intermediate junctions Tailwater Elevation:263.79 feet Discharge Range:2.01 to 2.01 Step Of. I. [afa] Overflow Elevation:266. feet Weir -NONE Upstream Velocity:3. feet/sec PIPE NO. 1: 2 IF - 12"CP @ 0.50% OUTLET: 262.11 INLET: 262.12 INTYP: 5 JUNC NO. 1. OVERFLOW -EL: 266.80 BEND: 0 DEG DIA/WIDTH: 4.0 Q-RATIO: 0.00 s Q(CFS) HW(FT) HW ELEV. * N-FAC DC DN TW DO DE HWO HWI 2.01 1.73 263.85 * 0:012 0.61 0.64 1.68 1.68 1.68 1.73 0.82 PIPE NO. 2: 2 LF - 12"CP @ 1.50a OUTLET: 262.12 INLET: 262.15 INTYP: 5 JUNC NO. 2: OVERFLOW -EL: 268.71 BEND: 90 DEG DIA/WIDTH: 4.0 Q-RATIO: 1,54 Q(CFS) HW(FT) HW ELEV. N-FAC DC DN TW DO DE HWO HWI. 2.01 1.88 264.03 * 0.012 0.61 0.46 1.73 1.73 1.71 1.88 0.93 PIPE NO. .3: 45 LF - 12"'CP @ 0.49% OUTLET: 262.15 INLET: 262.37 INTYP: 5 JUNC NO, 3: OVERFLOW -EL: 268.15 BEND: 89 DEG DIA/WIDTH: 4.0 Q.-RATIO: 0.14 Q(CFE) HW(FT) HW ELEV. * N-FAC DC DN TW DO DE HWO HWI 0.79 1.71 264.08 * 0.012 0.38 0.38 1.88 1.88 1.68 1.71 0.52 PIPE NO. 4: 49 LF - 12"'CP @ 0.51% OUTLET: 262.37 INLET: 262.62 INTYP: 5 JUNC NO. 4: OVERFLOW -.EL: 267.15 BEND: 20 DEG DIA/WIDTH: 4.0 Q-RATIO: 0.13 Q(CFS) HW(FT) HW ELEV. * N-FAC DC DN TW DO DE HWO HWI 0.70 1.4.9 264.11 0.012 0.35 0.35 1.71 1.71 1.48 1.49 0.47 PIPE NO, 5: 39 LF - 12"CP @ 0.51% OUTLET: 262.62 INLET: 262.82 INTYP: 5 JUNC NO. 5: OVERFLOW -EL: 267.00 BEND: 13 DEG DIA/WIDTH: 4.0 Q-RATIO: 0.26 Q:(CFS) HW(FT) HW ELEV. N-FAC DC DN TW DO DE HWO HWI 0.62 1.31 264.13 * 0.022 0.33 0.33 1.49 1.49 1.,31 1.30 0.43 PIPE NO. 6_ 72 IF - 8"CP 0.50& OUTLET: 263.15 INLET: 263-SI INTYP: 5. JUNC NO. 6: OVERFLOW -EL: 265.50 BEND: 82 'DEG DIA/WIDTH: 4.0 'Q-RATIO: 0.40 Q(Cps) HW(FT) HW ELEV. * N-FAC DC DN TW DO DE HWO HWI 0.49 0.78 264.29 * 0.012 0.33 0.35 0.98 0.98 0.73' 0.78 0.48 PIPE NO. 7: 19 LF - 811CP @ 0.47% OUTLET: 263.51 INLET: 263.60 INTYP: 5 JUNC NO. 7: OVERFLOW -EL: 265.97 BEND: 89.DEG DIA/WIDTH: 4..0 ¢-RATIO: 0.00 Q(CFS) HW(FT) HW ELEV. * NWFAC DC DN TW DO DE HWO HWI ***xwww*ww*wwww*ww**w�*,�w**w**w,r�*,�w*w*w*x#�,t+r,��t:►,r,�* �e*�*ww*t��rw�rh;�,+,v�,�n,�*�*,�*raw 0.35 0.74 264.34 0.012 U.28 0.25 0.78 0.78 0.71 0.74 0.39 PIPE NO. 8: 65 LF - 811CP @ 0.5I-W OUTLET: 263.60 INLET: 263.9.3 IN'T'YP: 5 Q(CFS) HW(FT) HW ELEV. * N-FAC DC DN TW DO DE HWO HWI 0.35 0.46 264.39 0.28 0.29 0...74 0.74 0.46 0.36 0.25 01 136.bwp 33.00 8.00 1 263.15 263.31 Page 1 136.bwx S. MainMenu.Perform Backwater on PIPES 136_bwp Pipe Filename F broad -crested weir at Intermediate junctions F UTW. use HW/TW File for Tailwater 264.130 Tailwater elevation [only read when UTW=False] [specify] Tailwater Filename [only read when uTW=True] 0.13000 Minimum discharge 0.13000 Maximum discharge 1.00000 discharge increment 136.doc Documentation Filename (Specify) for NONE 1 1=standard,2=condensed,3=Expanded 1 1=no weir,Z=Sroad,3=sharp 265.7500 overflow Elevation -0.999990E+15 Weir Length [used -0.999990E+15 Weir Height above overflow [used T uvF:Upstream velocity Fixed? 3.00000 Upstream velocity [used only for -0.999990E+15 Channel width [used only for 0 Return to Main Menu 15 MainMenu:Exit KCBW Program Page 1 output only for Broad/sharp weirs] only for Broad/sharp weirs] UVF=True] , UVF=False] BACKWATER COMPUTER PROUPULM FOR PIPBS Pipe :data fi-om file:1315--bwP Surcharge condition .at ittermediat-t- j:=ctlons Tailwater Elevation;264.23 feet Discharge RangetO-13 to 0.13 Step of OverfloW Zlevatlon;265,75 feet Weir I NONE 'Up Cream Velac$ty:3. feet/sec PIPE 'N I 0. 1, 33 LF - VdP 9. t.48-� OUTLET: 263.15 INLET; 263-3l INTYM 5 (CFs) j10 (F-jt) #0 ELEV : -t IT-7AC PC INN 'TW DO 1A Ewa Awl. 6.13 0. e3 264.14 0-17 '0-18 0,98 0.$98 0.0 0. wy 0.08 07 116.bwp 29.00 12.00 1 262.15 263.70 268.08 89.00 4.00 0.000 103.00 12:00 1 263.70 264.22. 268.1.2 14.00 4.00 0.051 4.8.00 12.00 1 264.22 264.46 267,5.1 26.00 4.00 0.206 102.00 12.00 1 264.46 266.93 270..53 94.00 4.00 0,229 74.00 12.00 1 266.93 267.30 271..77 92.00 4.00 1.001 112.00. 8.00 1 2.67.63 268.24 273.24 90.00 4.00 5.124 74.00 8.00 1 268.24 269.61 Page 1 5 5 5 116.bwx 8 MainMenu:Perform Backwater on PIPES 116.bwp Pipe Filename F broad --crested weir at intermediate junctions F uTw:use HW/TW File for Tailwater 264.030 Tailwater elevation [oily read when uTW=False] (specify) Tailwater Filename [only read when uTW=True] 1.22000 Minimum discharge 1.22000 maximum discharge 1.00000 discharge Increment 116.doc Documentation Filename (Specify) for NONE 1 1=standard,2=condensed,3=Expanded 1 1=no weir,2=Broad,3=Sharp 271.8000 overflow Elevation -0.999990EA-15 weir Length [used -0.999990E+15 weir Height above overflow [used 7 uvF:upstream velocity Fixed? 3.00000 Upstream velocity [used only for -0.999990E+15 Channel Width [used only for 0 Return to Main Menu 15 Mai nMenu :Exit KC-BW Frog raM, Page 1 output only for Broad/sharp weirs] only for Broad/Sharp weirs] UVF=True] UVF=False] BACKWATER COKPUTER PROGRAM FOR PIPES Pipe data from file:116.bwp Surcharge condition at intermediate junctions Tailwater Elevation:264.03 feet Discharge Range:1.22 to 1.22 Step of 1. [cfs] Overflow Elevation:271.8 feet Weir -.NONE Upstream. Velocity:3. feet/sec PIPE NO. 1: 29 LF - 1211CP @ 5.34% OUTLET: 262.15 INLET: 263.70 INTYP: 5 JUNC NO. 1: OVERFLOW -EL: 268.08 BEND: 89 DEG DIA/WIDTH: 4.0 Q-RATIO: 0.00 Q(CFS) HW(FT) HW ELEV. * N-FAC DC DN TW DO DE HWO HWI 1.22 0.65 264.35 * 0.012 0.47 0.25 1,88 1.88 0.47 ***** 0.65 PIPE NO. 2; 103 IF - 12"CP @ 0.50% OUTLET: 263.76 INLET: 264.22 INTYP: 5 JUNC NO. 2: OVERFLOW. -EL: 268.12 SEND; 14 DEG DIA/WIDTH.: 4:0 Q-RATIO: 0.05 Q(CFS) HW(FT) HW ELEV. * N-FAC DC DN TW DO DE HWO HWI 1.22 O3 70 264..92 * O.012 0.47 0.47 0.65 0.65 0.47 0.70 0.64 PIPE NO. 3: 48 IF - 12"CP @ 0.50& OUTLET: 264.22 INLET: 264.46 INTYP: 5 JUNC NO. 3: OVERFLOW -EL: 267,51 BEND: 26 DEG DIA/WIDTH: 4.0 Q-RAT'TO: 0.21 Q(CF5) HW(FT) HW ELEV. * N=FAC DC DN TW DO DE HWO HWI xnx*9F.xx.*xr�rlkiF***Y�x**icix***#�iit%iriiaaYk**#Yc*ir*x*tYh�*�*tl';rdFfi'ir�c*t�taflc.fFxvY:t1lYt**Stye*fit&x*xif 1.16 0.69 265.15 * 0,012 0.46 0.46 0.70 0.70 0.51 0.69 0.6.3: PIPE NO, 4: 102 LF 12"CP @ 2.42t OUTLET: 264.46 INLET: 266.93 INTYP: 5 JUNC NO. 4< OVERFLOW -EL: 270.53 BEND; 90.D:EG DIA/WIDT-H: 4.0 Q-RATIO: 0.23 Q(CFE) HW(FT) HW ELEV.. * N-FAC DO DN TW DO DE HWO FIWI 0.96 0.58 267.51 * 0.012 0.42 0.28 0.69 0.69 0.42 ***** 0.58 PIPE NO. 5: 74 LF - 12"CP 0 0.50t OUTLET: 266.93 INLET: 267.30 TNTYP: 5: JUNC NO. 5: OVERFLOW -EL: 271.77 }SEND: 90 DEG DIA/WIDTH: 4.0 Q-RATIO: 1.00 ¢(CPS) HW(FT) HW HLEV, * N-PAC DC DN TW DO DE HWO HWI 0.78 0.59 267.89 * 0.012 0.37 0.37 0.58 0.58 0.37 0.59 0.53 PIPE NO. 6: 112 IF - 8"CP 0 0..54% OUTLET: 267.63, INLET: .2.60,24 INTYP. S JUNC ITO, Z, OVERFLOW-M - 773.24 BMM . 90 DEG r)jA/WTDTH; 4.b Q-RATrO: 5.12 Q(CFS) HW (FT) UW .9LEV. X-VAC VC UN Tw DO m Hwo Hw r O.012 0.30 Q-30 0.26 0.30 0.30 0,45 0.41 PIPE M - 7 74 LF - 84CP 6 G.SQ& OUTLET: 268.24 INLET: 268-61 GYP: 5 Q(CFSY RW(FT) FM- ELEV- W-FAC DC DN Tw DO DS Hwo Awl 168.76 b,012 0,12 0,12 0.48 0.46 0.15 Q-.04 6-01 Appendix C.4—West 100 Year Backwater Analysis 08 wpl.bwp 2.00 12.00 1 262.11 262.12 268..80 0.00 4.00 0.000 2.00 12.00 1 2Q.12 262.15 268.71 90.00 4.00 1.542 45.00 12.00 1 262.25 262,37 268.1S 89.00 4.00 0.137 49.00 12.00 1 262.37 262.62 267.15 20.00 4.00 0.126 39.00 12.00 1 262.62 . 262.82 267.00 13.00 COO 0.262 72.00 8.00 1 263..15 261,51 765.50 82.00 4.00 0.404 19.00 8.00 1 261.51 .263.60 265.97 89.00 4.09 0.000 65.00 8.00 1 2.63.60 263.93 P4ge 1 WQ1.bwx 8 MainMenu:Perform Backwater on PIPES wQl.bwp Pipe Filename F broad -crested weir at intermediate junctions F UTW:Use FEW/TW File for Tailwater 263.850 Tailwater elevation [only read when UTW=False] (specify) Tailwater Filename [only read when UTw=True] 2.48000 Minimum discharge 2.48000 maximum discharge 1.00000 discharge increment WQ1.doc ❑ocumentation Filename (Specify) for NONE 1 1=standard,Z=Condensed,3=Expanded 1 I=no weir,2=Broad,3=Sharp 266.0000 overflow Elevation -0.999990E+15 Weir Length [used -4.999990E+15 weir Height above overflow [used T UVF : upstream Velocity Fixed? 3.00000 Upstream Velocity [used only for -0.999990E+15 Channel width [used only for 0 Return to Main Menu 15 MainMenu.Fxit KCBW Program Page 1 output only for Broad/sharp weirs] only for Broad/sharp weirs] UV F =True] UVF=False] BACKWATER COMPUTER PROGRAM FOR PIPES Pipe data from file:WQI.bwp surcharge condition at intermediate junctions Ta.ilwater Elevation:263.85 feet Discharge Range:2.48 to 2.48 Step of 1. [cfs] Overflow Elevation:266. feet. Weir:NONE Upstream Velocity:3. feet/sec PIPE NO. 1: 2 LF - 12"CP @ 0.50o OUTLET: 262.11 INLET: 262.12 INTYP: 5 ! JUNC NO. 1: OVERFLOW -EL: 268.60 BEND: 0 DEG DIA/WIDTH: 4.0 Q-RATIO: 0.00 Q(CFS) HW(FT) HW ELEV. * N-FAC DC DN TW DO DE HWO HWI 2.48 1.82 263.94 * 0.012 0.68 0.75 1.74 1.74 1.74 1.82 0.92 PIPE NO. 2: 2 LF - 12"CP 6 1,50% OUTLET: 262.12: INLET: 262.15 INTYP: 5 JUNC NO. 2: OVERFLOW -EL: 268.71 BEND: 90 DEG DIA/WIDTH: 4.0 Q-RATIQ: 1.54 Q(CFS) HW(FT) HW ELEV. * N-FAC DC DN TW DO DE HWO HWI 2.48 2.06 264.21 * 0.012 0.68 0.52 1.82 1.82 1.80 2.06 1.09 PIPE NO. 3: 45 LF - 12"CP @ 0,49% OUTLET: 262.15 INLET: 262.37 INTYP: 5 JUNC NO. 3: OVERFLOW -EL: 268.15 BEND: B9 DEG DIA/WIDTH: 4.0 Q-RATIO: 0.14 Q(CFS) HW(FT) HW ELEV. * N-FAC DC DW TW DO DE HWQ HWI 0.98 1.91, 264.28 * 0.012 0.42 0.42 2.06 2.06 1.57 1.91 0.59 PIPE NO. 4: 49 LF - 12"CP @ 0.51W OUTLET: 262.37 INLET: 262.62 INTYP: 5 JUNC NO. 4: OVERFLOW -EL: 267.15 BEND: 20. DEG DIA/WIDTH: 4.0 Q-RATIO: 0.13 Q(CFS) HW(FT) HW ELEV. * N-FAC DC DN TW DO DE HWO HWI 0.86 1.71 264.33 * 0.012 6.3.9 0.39 1.91 1.91 1.69 1.71 0.53 PIPE NO. 5: 39 LF - 12"CP @ 0.51W OUTLET: 262:62 INLET: 262.82 INTYP; 5 JUNC NO. 5: OVERFLOW -EL: 267.00 BEND: 1.3 DEG DIA/WIDTH: 4.0 Q-RATIO: 0.26 Q(CFS) HW(FT) HW ELEV. * N-FAC DC DN TW DO DE HWO HWI 0.76 1.53 264.35 * 0.012 0.37 0.36 1.71 1,71 1.53 1.52 0.47 _a W _3 PIPE NO. 6: 72 LF - 8"CP 0 0.50% OUTLET: 263.15 INLET: 2'63.51 INTYP: 5 JUNC NO. 6: OVERFLOW -EL: 265.50: BEND: 82 DEG DIA%WIDTH: 4.0 Q-RATIO: 0.40 0(CFS) HW(FT) HW ELEV. N-FAC DC DN TW D. DR HWO HWI 0.60 . 1.08 264.59 * 0.012 0.37 0.40 1.20 1.20 1.00 1.08 0- 55 f PIPE NO. 7: 19 LF - 811CP @ 0.41% OUTLET: .263.51 INLET; 263.60 INTYP: 5 JM,TC NO, 7: OVERFLOW -EL: 265.57 BEND: 89 DECK DIAIWIDTH: 4.0 Q-RATIO: 0.00 Q(CFS) HW(FT) Hw ELEV. * N-FAC. DC DN TW DO DE HWO HWI 0.43 1.05 264.65 * 0.012 0.31 0.33 1.08 1.08 1.01 1.05 0.44 PIPE N0. 8: 65 LF - 811CP Q 0.515 OUTLET. 263.60 INLET: 263.93 INTYP: 5 Q (CFS) HW (FT) RW ELEV. * N-FAC DC DN TW DO DE HWO HWI 0.43 0.80 264.73 * 0.012 0.31 0.32 1.05 1.05 0.80 0.70 0.30 136.bwp 01 33.00 8.00 1 263.15 263.31 Page 1 136.bwx 8 MainMenu:Perform Backwater on PIPES 136.bwp pipe Filename F broad -crested weir at Intermediate junctions F UTW:Use Hw/Tw File for Tailwater 264.350 Tailwater elevation [only read when M=False] (specify) Tailwater Filename [only read when UTW=True] 0.16000 Minimum discharge 0.16000 maximum discharge 1.00000 discharge increment 136.doc Documentation Filename (Specify) for NONE 1 1=5tandard2�condensed,3=Expanded output 1 1=no wei r, KBroad, 3=Sharp 265.7500 overflow Elevation -0.399990E+15 weir Length [used only for Broad/Sharp weirs] -0.999994E+15 Weir Freight above overflow [used only for Broad/sharp weirs] T UVF:Upstream Velocity Fixed? 3.00000 upstream Velocity [used only for UVE=iruej -0.999990E+15 channel width [used only for UVF- False) 0 Return to main Menu 15 MainMenu:Exit KCBW Program Pane 1 BACKWATER COMPUTER PROGRAM FOR 'FIFES ~ Pipe data from filet136.bwp Surcharge condition at intermediate junctions ` Tallwate.r Elevation:264.35 feet bischarge Range:0.16 to 0.16 Step of 1. (cf6) overflow Elevation:265,75 feet Weir -NONE Upstream Velocity:3. feet/sec PIPE NO. 1: 33 LF - VCP 0.46* OUTLET: 263.15 INLET: 263.31 INTYP: 5 Q (CPS:) HW (FT) HW ELEV". * N-FAC PC DN TW DO DE HWO HwI 0:16 1.05 264.36 * 0.012 0.19 0.19 1.20 1.20 1.65 0.91 0.11 07 116.bwp 29.00 12.00 1 262.15 263.10 268.08 89.00 4.00 0.000 103.60 12.00 1 263.70 26.4.22 268.12 14.00 4.00 0.051 48.00 12.00 1 264.22 264.46 267.51 26.00 4.00 0.206 102.00 12.00 1 264.46 266.93 270.53 94.00 4.00 0.229 74.00 12.00 1 Z66..93 267.30 271.77 92..00 4.00 1.001 112.00 8.00 1 267,+63 268.24 273.24 90.00 4.00 5.124 74.00 8.00 1 269.24 268,61 Fagg 1 11'6 . bwx .$ Mai nKenu: Peri+orm Backwater on PIPES 116.bwp Pipe Filename F broad -crested weir at Intermediate junctions F uTw:use HW/Tw File for Tailwater 264.210 Tailwater elevation [only read when uTw=Falsel (specify) Tailwater Filename [only read when UTW-True] 1.51000 Minimum discharge 1.51000 maximum discharge 1.00000 discharge increment 116.doc Documentation Filename (specify) for NONE 1 1=Standard,2=condensed,3=Expanded output 1 1=no weir,2=Broad,3=Sharp 271.8000 Overflow Elevation -0.999990E+15 weir length used only for Broad/sharp weirs] -0.999990E+15 weir Height above overflowruso-d only fo:r Broad/sharp weirs] T uVF:upstream velocity Fixed 3.00000 Upstream velocity [used only for UVF=True] -0.999990E-15 Channel width [used only for uVF=Fa1se� 0 Return to Main Menu 15 MainMenu:Exit Kcaw Program Page I BACKWATER COMPUTER PROGRAM FOR PIPES Pipe data trot. file:116.hwp Surcharge condition at intermediate junctions Tailwater Elevation:264.21 feet Discharge Range41.51 to 1.51 Step of 1- [cfe] Overflow Elevation:271.8 feet Weir --NONE Upstream Velocity:3. feet/see PIPE:NO. 1: 29 LF - 120CP @ 5,34� OUTLET: 262..15 INLET: 263.70 INTYP: 5 JUNC NO. 1: OVERFLOW-E:L; 268.08 BEND: 89 DEG DIA/WIDTH: 4.0 Q-RATIO; 0.00 Q(CPS) HW (FT) HW ELEV. * N-PAC DC DN TW DO DE HWO HWI. 1.51 0.75 264.45 * 0.012 0.53 0.28 2.06 2.0.6 0.53 ***** 0.75 PIPE NO. 2: 103 LF - 1211CP @ 0.50* OUTLET: 263,70 INLET: 264.22 INTYP: 5 JUNC NO. 2: OVERFLOW -EL: 268.12 BEND: 14 DEG DIA/WIDTH: 4:0 Q-RATIO; 0.05 Q(CP'S) HW (FT) HW ELEV. * X-FAC DC DN TW DO DE HMO HWI * * * * * * * * * * * * * * * * * * * * * * * * * * * **********.********k*****r************************ 1.51 0..78 265.00 * 0.012 0.53 0.53 0.75 0.75 0.53 0..78 0.72 PIPE NO. 3: 48 LF - 12:"CP @ 0.50m OUTLET: 264.22 INLET: 264:46 INTYP: 5 JUNC NO. 3: OVERFLOW -EL: 267.51 BEND: 26 DEG DIA/WIDTH: 4..0 Q-RATIO. 0.21 Q(CFS) HW(FT) HW ELEV. N-PAC DC DN TW DO DE HWO HWI 1.44 0.77 265.23 * 0.012 0.51 0.52 0.78 0,78 0.60 0.77 0.71 PIPE NO. 4: 102 LF - 12"CP @ 2.42 OUTLET; 264..46 INLET: 266.93 INTYPt 5 JUNC NO. 4: OVERFLOW -FL: 270.53 BEND: 90 DEG DIA/WIDTH: 4.0 Q-RATIO: 0.23 Q(CFS) HW(FT) HW ELEV. * N-FAC DC DN TW , DO DE HWO HWI 1.19 0.66 267.59 * 0.012 0,47 0.31 0..77 0.77 0.47 PIPE NO, 5: 74 LF : 12"CP @ 0.50% OUTLET: 266.93 INLET: 261.30 INTYP: 5 JUNC NO. 5: OVERFLOW -EL: 271.77 BEND: 90 DEG DIA/WIDTH: 4,0 Q-RATIO: 1.00 Q(CFS) HW (FT) HW ELEV. * N-FAC DC DN TW` DO DE HWO HWI 0.97 0.67 267.97 * 0.012 0.42 0.42 0.66 0.66 0.42 0.67 0.61 PIPE NO. 6: 112 LF p,541 OUTIM; 267,63 INLET: 269,24: iNTYP,. 5 JUNC NO. 6: OMFLOW-PTA- 275-24 REND: 90 D-Va r)�A/WMTR- 4.0 Q-RATIGt. S-1:2 HW (FT) 11W ELEV. N-FAC DC IDN Tw DO DB gwo HWI 0-48 0.,51 268.75 0.012 0,33 6.34 0.34 0,34 0.34. 0.51 0.47 P'lPS NO. 7 74 LF - 0.50A OUTLET., 268-.24 INLET:. 268,151 INTYP. 5 1W (FT) HW ELEV.. V-VAC DC D9 Tw: DO DE. Kwo HWI 264.60 0.012 0-13 O,14 0-51 0-51 0-19 0.07 0.03 ml m �j C.5— 25 Year Rational Method Computations Panther Lake Elementary School Runoff Computations Using Rational Method Equations Definitions 2$ Reference: 1998 KCSWDM, Section 3.2.1 R = return period (years) QR. = CIRA A = subbasin area (acres) iR=a T bR R c aR, bR=coefficient(Table 3.2.1.B) Z66 0,65 IR= PRIR C = runoff coefficient (Table 3.2.1.A) T� = Max of Tpipe + Tc prev, 6.3, or Tt iR = unit peak rainfall intensity factor Tt= U60V IR = peak rainfall intensity Cinches/hour) V = kR(so)e's kR = values forTt (Table 3.2.1.C) L = Flow length (feet) PR =Total precipitation for R-year, 24-hour storm (inches) From isopluvial maps (Figures 3.2.1C to 3-2.1D) QR = Flow for individual basin (cfs) Qr = Total flow for sequential basins (cfs) so = slope of flow path (ftlil) Tc = time of concentration for sequential basins (minutes) T, = time of concentration for individual basin (minutes) V = average velocity across land cover (feellsecond) 3.40 25 yr 100 yr aR 2.66 2.61 0.63 bR 0.65 -- PR 3.4 _ 4.12 To Flow Control Facility RSRHEM A v ie: '• '.D = S ij7'e:: Vful! Cf Qt Qf Vptpe Tpipe To CB Qratfo OR = r -_ 1,:W .:. -.: �, '. ..AZ j C k -:s =_ V l.. `' Tr Tvsea fR� la A Basle C1..-- -_:.- �`.-- WEST t3A51N RUN 1 CW3 100 0.90 0.00 105 0.90 0.00 025 0.25 0.00 0.00 #DIVIO! #DIV/01 #Diva #DFVIOI #DFV1O! #DFWOI #DIVIOI #DIVIOI #DIV101 #DIVIOI #DIV/O! #DIV/O! 4DIV/01 #DIV/Ot 0,00 0,00 0.00 0.43 0.43 0 112.480 0.012 0.012 12 12 0.005 0.005 3.47 3A7 2.73 2.73 0.16 0.16 2.17 2.17 0,00 0.86 0.000 0.000 115 0.90 0,00 125 0,90 0.01 13o D.90 0.01 135 0.90 0.00 136 090 0.00 0_fl0 D.O3 0.90 0.00 ISO 6.90 0.14 0.25 0.25 0,25 0.25 0.25 025 025 025 0.00 0.09 0.09 0.00 0.17 0,08 000 o.00 0-34 #DIV101EM#DV 029 #D!V/01 0.26 0.44 #DiV/01 0.90 1 20.00 0.029 0.030 0.028 0.025 D.025 0.054 #DIVIOI 1.50 1.34. #DIVIO! 1.21 1.70 #DIV/0! 4.64 107 113 171 60 61 167 t 9DIV/01 1.18 1.40 ;;rDtVIOT 2.35 0.59 #DiV101 0.60 IIDIVI01 6,30 6,30 #DIVI01 6.30 6.30 #01V/01 6.30 #DIVIOI 0.80 0.80 #DIV/O! 0.80 OA0 9DIV101 0.80 #D!W01 2,73 2.73 IlO V101 2.73 2.73 #DIV/01 2.73 O.DO 0,1D 0.10 0,00 0.18 0.12 MO 0,14 0.00 0.10 0.08 O.DO 0.73 0.14 0.00 0.35 2.01 0.79 0.70 0.62 D-13 OA9 0.35 0.36 7.000 45.000 49.000 40.218 19.000 19.0D0 19.000 65,569 0.012 0.012 0.012 . 0.012 D.012 0.012 0.012 0.012 12 12 12 12 12 8 8 8 0.005 0.005 0.005 0-005 0.005 0,005 0.005 0.005 3.47- 3.47 3.47 3.47 3A7 2.65 2.65 2-65 273 2.73 2.73 2.73 273 0.83 0.93 0.93 0.74 029 0.26 023 0-05 0.53 0.38 0.38 3.31 2.57 2.48 2400.2B 1.57 2,31 Z10 2.10 0.04 0.29. 0.33 0.20 0.140.4D4145 0-15 0.52 1.542 0.137 0.126 0.262 0.004140 0.000 0.000 RUN 2 CB's 115 0.90 0,00 116 0.90 0.00 117 0.90 0.00 118 0,90 0.02 119 0.90 0.03 120 0.90 0.00 121 0.90 0.07 1'2 0.90 0.00 123 0.90 0.07 025 0.25 0.25 0.25 0.25 0.25 025 025 025 0.00 0.00 0.09 0.23 0.16 0.09 0.23 0.09 0.23. 4/DIV/0! #DIVIOI 0.25 0.29 0'35 0.25 0.4D 0.25 0-40 #DIV/01 #DIV/01 7.00 7.82 9.03 7.00 9.98 7.00 9.98 0.026 0,029 0.018 0.020 0.010 0,013 0.024 #6IV/01 #DIV/O! 1.12 1.32 1.21 0-9B 1.00 0,81 1.56 73 203 192 126 177 164 100 #DFV/01 #D!V1O) 1,09 2.58 2.63 2-14 2.90 #DIV/01 #DIV/01 I 6.30 6.30 6.30 6.30 8.30 6.30 6.30 #DfV/01 #DiV/01 0.80 0.80 0.80 0.80 0.80 0.80 0.80 #DIV/o! #DIVIOI 2.73 2.73 2.73 2.73 2.73 2.73 2.73 0.00 0.00 0,09 0.25 0,19 0.D9 0.30 0.09 0.30 0.00 0,00 0.06 0.20 0.18 0.06 0.33 0,06 0.33 2-01 1.22 1.22 1.16 0.96 0.78 0.39 D.06 0.33 7 29.247 117 47.93652 102,2789 73.53249 112 73.5008 102 0.012 0.012 0.012 0.012 0.012 0.012 0.012 0.012 0.012 12 12 12 12 12 12 12 12 8 0.005 0.053 0.005 0.005 0.024 0.008 O.D10 0.005 0.005 3.47 11.31 3.47 3.47 7.64 4.40 4.91 3.47 2.65 2.73 8.89 2.73- 273 6.00 3,45 3.86 Z73 0.93 0.74 0.14 0.45 0-43 0.16 0.23 0.10 D.02 0.35 3,31 6.83 Z89 2-85 4.82 3.04 273. 1.30 Z07 0.04 0.07 0.68 0.28 0,35 OAD 0.68 0.94 0.82 0.64$ 0.000 0.051 0.206 0-=9 1.001 5.124 0.000 0.000 EAST BASIN d#DtV/01 RUN 1 CBS 205 0.90 0.00 210 0.90 0.00 215 0.90 0.00 233 0.90 0.03 234 0.90 0.00 235 0.90 0.68 0.25 0.25 0.25 025 0.26 0.25 0,00 0.58 0.00 0-15 0.09 0.05 #DIVIOI 025 NDIVI01 0.35 025 0.87 #D!V/01 7.00 #DIV/O! 9.10 7-00 19.36 0-020 0-010 0.02 0.019 41DIV/0! 0.09 #D!V/01 0.93 0.99 2.64 200 142 78 232 3,37 #DIVIOI 2.55 1.31 1.47 #DIV/DI 6.30 #DIV/0! 6,30 6.30 6,30 #DIV1O! 0.80 *nlW0! 0.80 0.80 0.80 #DIV/O! 2-73 00TVI01 2.73 273 273 0.00 0.58. 0.00 0.17 0.09 0.92 0.00 0.40 0.00 0.17 0.06 2.19 5.84 5.84 3,13 2-42 2.25 219 69 24 26 53 84 72 0.012 0.012 0.012 0.012 0.012 0.012 18 18 18 12 12 12 0.005 0.005 0.005 0.065 0.005 0.005 4.55 4.55 4Z5 3.47 3.47 3.47 8.05 8.05 8.05 273 273 273 0.73 0.73 0.39 0.89 0.83 0.80 4.31 4.31 3.64 3,48 3.41 3.38 027 0,09 0.12 0.25 0.41 0,35 0.000 0.887 0.291 0.075 0.027 0,000 RUN 2 CB'S 220 0.90 0.20 222 0.90 O.Do 223 0,90 O.DO 224 0.90 0.00 225 0.90 0.07 0.26 0.25 025 0.25 0.25 0.00 0,00 0.00 0-00 0100 0.90 #DIV/O! #DiV/01 #DIV/01 0,90 20.00 4DIV/01 #UVIOI #DIVIO! 20,00 0.031 0-004 0-023 0,029 0,056 3.54 #D!V/O! #DIV/DI #DIV/O! 4.71 04 83 142 75 72 0.30 #D!V/01 #DIV/01. #DIV/0! 0.25 6.30 #DIVI01 #DIVIDI #DIVIOI B.30 0.80 #DIVIOI #DIV/O! -#DIVIOI 0.80 2.73 #DIVIO! #DIVJO! #DIVIOI 273 0.20 0.00 0.00 0.00 D-07 0.48 0.00 0.00 0.00 OA7 2.31 1.63 1.83 0.17 0.17 73 84.62 76,33 36.02 79,09 0.012 0.012 0,012 0.012 0.012 12 12 12 12 12 0.067 0.005 0.005 0,005 0.005 1272 3.4T 3.47 3.47 3.47 9.99 273 2-73 2.73 1 2.73 0.23 0.67 0.67 0.06 13.06 1 8.85 3 22 3.22 1.70 1,70 0.14 0-44 0.41 0.35 0,78 0265 0000 9.634 .34 0.000 0.000 300 0.90 0.42 301 0,90 0.06 302 O.SD 0,07 025 0.25 0.25 0.43 0.00 0,03 0.57 0.90 0.72 13.37 20.00 16.43 0.023 0.026 0.050 2O1 3.24 3,69 142 84 125 1.18 0.43 0.56 6.30 6.30 6,30 0.80 0-80 0.80 Z73 273 2.73 0.85 0.08 0.10 1.32 0.14 e% 1.66 0.33 0.19 108 42 108 0.012 0.012 0.012 12 12 12 0.036 0.023 0.036 9.32 7.50 9.32 7.32 5.89 7.32 0.23 0.08 1 11.03 6.45 3.56 3.59 0.28 0.20 0.50 3.997 0.742 0.000 D.000 217 216 2.48 #DtV101 215 216 0,71 0.000 216 50.0 0.00 0.00 3.19 O.DDO Panther Lake Elementary School K:lprojec1131100131147A1W aterReshRationat_25.x1s To Flow Control FadGty Printed: 12/112000 Dlak Appendix C.6-100 Year Rational Method Computations is To Flow Control Facility Panther Lake Elementary School Runoff Computations Using Rational Method Equaoons Definitions Reference: 1998 KCSWDM, Section 3.21 R = return period (years) OR = C1RA A = subbasin area (acres) iR=aRTcbri. aR, bR = coefficient (Table 3.2.1.B) IR = PRIER C = runoff coefficient (fable 3.21.A) T, = Max of Tpipe + Tc prev, 6.3, orTt iR = unit peak rainfall intensity factor Tt= U60V IR= peak rainfall intensity (inches/hour) V = kR(sa)°•5 kR = values for T, Cfable 3.2.1.C) L = flow length (feet) 1 oo PR = Total precipitation for R-year, 24-hour storm (inches) From isopluvial maps (Figures 3.21C to 3.2.1D) 2.61 0:63 OR = Flow for individual basin (cfs) Cr = Total Flow for sequential basins (cfs) S. = slope of flow path (ft/ft) Tc = time of concentration for sequential basins (minutes) T, = time of concentration for individual basin (minutes) V = average velocity across land cover (feet/second) 4.12 25 yr 100 yr aR 2-66 2.61 bR 0.65 0.63 PR 3.4 4.12 - - - -_Mff-_-_ = _ w_� x --• -� -sue _:= - - _ - Vpipe Tpipe To CB 4ratio I-A1R. - Y -tl:. _.' :". -t7 -_ Gft AE �- ;. Al - j - . Cc R _. # A QR __ _ Basin k ' _ - V =_ _ => =�.'' Tr T �,a !R IR _^:p7pi . Vfull Qf WEST BASIN RUN 1 CWs 100 0.90 0.00 0.25 0.00 #D1V101 #DIVIDI dDIV/01 #DIV101 #DIV101 #DN/01 VDIVIOi 0,0D 0.00 0.70 0 0.012 12 0.005 3.47 2.73 0.26 2.49 0.00 0.000 106 0.90 0.00 0.26 O.OD #DtV101 #DIV101 #DIVIOI #DWAA #DW01 #DN101 #DIV101 0.00 � 0.70 112.480 0.072 12 0.005 3.47 273 0.26 2.49 u.75 0.000 145 0.96 O.OD 0.25 0.00 #DIV101 #DIVIOT #DIV101 #DIV/0! #DiV1Ol #D1V/01 fIDIVI01 0.0000 2.48 7.000 0.012 12 0.005 3.47- 2.73 0.91 3.50 0,03 1.542 125 0,90 0.01 0.25 0,09 0.34 8,82 0.029 1.50 107 1.19 0.30 0.82 3.37 0.1012 Us 7D.110 45.000 D.012 12 0.005 3A7 273 .0.36 Z72 0.28 0.137 130 0.90 0.01 0.25 0.09 0,29 7.80 0.030 1,34 113 1.40 8.30 0.82 3.37 D.1Q 0.86 49.000 0.012 12 0.005 3.47 273 0 31 2,63 0.31 0.126 135 0.90 0.00 0.25 0.00 #0IV/01 #DNI01 #DlV/ol #DIVI01 IIDIV101 #DIV101 #DN141 0.0000 0,76 40,218 0.012 12 0.005 3.47 273 0.28 2,54 0.26 0.262 136 090 0.00 0,25 0,17 0.26 7.28 0.026 1.21 171 2.35 6.30 0.82 3.37 0.1816 0.16 19.000 0.012 12 0.005 3.47 273 0.06 1.68 0.19 0.000 140 0.90 0.03 0.25 0.08 1 0.44 10.78 0.025 130 60 0.59 B.30 0.82 3.37 0.12 0.17 0.60 19.DDDI 0.012 8 0.005 265 0.93 0.65 244 0.13 0.404 745 0,90 0.00 0.28 O.t7a #DIV10! #DIV101 t7.025 #DIVJO! 61 #D1V101 #DIV101 #D1V/0! IFDIVIO! 0.00 O,OD 0.4,3 19.000 0.012 8 0.005 2.65 0.93 0.48 2.23 0.14 0.000 150 0.90 0.14 0.25 0.00 0.90 20.00 0.054 4.64 167 0.60 6.30 0.82 3.37 0.14 0.43 0.43 65.569 0.012 8 0.005 2.65 0.93 0 46 223 0.49 0.000 RUN 2 CB's 115 0.25 0.00 #DIVIDI # DIV/Ot #DfV101 401VAN #DWi01 #D!VIO! #DW101 O.t}0 0,00 2,48 7 0.012 12 ao05 3.47 2.73 0.91 3.50 0.03 0.648 115 0.25 0.00 #DIVI01 ANVIDT 11tDIVI01 901V101 9DIV101 9DIV101 #DIV101 0.06 0.00 1.51 29.247 U12 12 0.053 11.31 8.99 0.17 7.23 0.07 0.00D 117 0- 0.25 0.09 0.25 7,00 0.026 1.12 73 1,09 6.30 0.82 3,37 0.09 0.07 1.51 117 0.012 12 01005 3,47 273 0.55 3.D6 0.64 0.051 lib 2 0.25 0.23 0.29ft7,,"S-2 0.029 1-32 203 2.56 6,30 0.82 3.37 0.25 0.24 1.43 47.93852 OAl2 12 0.005 3.47 273 0.52 3.02 0.26 0.2063 W0�1900.02 0,25 0.16 0.35 0.018 1.21 192 263 8.30 0-82 3.37 .0.19 0.22 1.19 102 2789 0,Q12 f 2 0.024 7.64 B.OD 03D 5.10 0.33 0.229 720 0 0.25 0.09 0.25 0.D2O 0.88 126 214 8.30 D-82 3.37 0.09 UB 0.97 73.53249 0.012 12 0.008 4.40 3,45 0.28 3.22 0.38 1.001 121 7 0.25 0.23 0.40 0.010 too 177 296 6.30 0.82 3.37 0.30 0.40 0.48 112 0.012 12 0,010 4.91 3.86 0.13 2.89 0.645.724 122 0.25 0.09 US 0.013 0.81 164 3.37 6.30 0.82 3,37 0.09 O.08 0.08 73.5008 0.012 12 0.005 3.47 2.73 0.03 1.38 0.89 0.000 723 ..0 0.90 0.07 0.25 0.23 0.44 OA24 1.56 100 1.67 6.30 D.82 3.37 0.30 0.40 0.40 102 0.012 8 0.005 2.65 0.93 0.44 2-19 0.78 0.040 EAST BASIN REIN 7 CI3'S 0.90 0.00 0,25 0.00 ifDIV101 #D1V101 #DiV/01 #DIV101 #DIV101 #DIV/01 #D1VIQ! 0.00 0.00 7.03 69 0.012 18 0,005 4.555 6.05 0.87 4,54 0.25 0.000 205 210 0.90 0-00 0,25 0.58 0.25 7.00 0.020 0.99 200 3.37 6.30 0.82 3,37 0.58 0.49 7.03 24 0.012 18 0.005 4.55 1 8.05 0.87 4,54 0,09 0.906 215 0.90 0.00 0.25 0.00 #DtVl01 91DIV/0! I'VolVfol #DIV101 tniv/Dl fi-DIVIG! #01V101 0,00 0.00 3.69 26 0.012 18 0.005 4.55 1 8.05 0.46 3.Si 0.11 0.236 233 0.90 0,03 0.25 0.15 0.35 9.10 0.010 0.93 142 2.55 6.30 0.82 337 0.17 0.21 2.99 53 0.012 12 0.005 3.47 273 7.D9 3.68 0.24 0.076 234 0.90 0.00 0.25 0.09 0.25 7.00 0.02 0.99 78 1.31 6.30 0.82 3.37 0.09 0.07 2.78 84 0.012 12 0.005 3.47 2.73 1.02 1 3.81 0.39 0.027 735 0,90 0.88 0,25 0.05 0.87 19.36 0,019 264 232 1.47 6.30 0.82 3.37 0,92 2.70 2.70 72 0,012 12 9,005 3,47 2.73 0.09 1 3.58 0.33 0.000 RUN 2 CB'S 220 0.90 0.20 0.25 0.00 0.90 20,00 0.031 3,54 64 0.30 6.30 0.82 3.37 020 0,60 2.85 73 0.012 12 0.067 12.72 9.99 0.29 9.37 0.13 0,265 222 0.90 0.00 0.25 0.00 #DIV101 #DIV/01 0.004 #DIV/D! 83 #D1V101 #D!VID1 #DIV/0! #011WO! 0.00 0.00 2.26 84,92 0.012 12 0.005 3.47 2.73 0.83 3.47 1 0.42 0.000 223 0.90 0,00 0.25 0.00 #DIV101 #DIV101 0,023 #DIV/01 142 #DIV/01 #DfV101 #DIV/01 #DIV/01 0.00 0.00 2.26 78.33 0.012 12 0.005 3.47 2-73 0.93 3.41 0.38 9.634 224 0.90 0.00 0.25 0.00 #D1V101 # DrV/01 0.029 #DIViol 75 #DIV101 #DIV101 #DIV10] #DN/0I 0.00 0.00 0.21 36.02 0.012 12 0.005 3.47 2.73 0,06 1.80 0.33 0.000 225 F9-0 0,07 0.25 0.00 0.90 20.00 0,056 4.71 72 0.25 6.30 032 3.37 0.07 0.21 021 79.09 0,012 12 0.005 3,47 2.73 0.08 1.80 0.73 0.000 300 0.90 0.42 D.25 0.43 0.57 13,37 0.023 2,01 142 1.18 6.30 0,82 3.37 0.65 1.83 2,04 106 0.012 12 0.036 9,32 7,32 0.28 1332 0,26 3,997 301 0.90 0.06 0.25 1 0.00 1 0.90 2D.DO 0.028 3.24 04 1 0.43 5.30 1 0,82 1 3.37 0.06 0.17 0.41 42 0.012 12 0.023 7.50 6-in 0.07 3.77 0.19 0.742 302 ❑,90 o.07 0.25 0.03 0,72 i6.43 0.050 3,69 125 0.55 6.30 0.82 3.37 0.10 023 0.23 108 0,012 12 0.on 0.32 7.32 1 nn,% I SAO 0,47 10.000 0.000 217 2.48 216 215 0.71 0.000 246 81B 0.00 0.00 3.19 D.aoO 500 Panther lake Elementary School IClpmiec031100\31147A\WaterReslRationat 100.%!s To Flow Control Facility Printed: 12M 11200E Otak Figure 6—Conveyance Sub -Basins Exhibit Section Six J Mi Section 6—Special Reports and Studies The following special report has been prepared for the Panther Lake Elementary School site, and has been included separately as a part of the Pre -Application Package! Subsurface Exploration, Geologic Hazard, and Pr6iminary GeotechnicaI Engineering Report, New Panther Lake Elementary. School, Federal Way, Washington, Associated Earth Sciences, December 21, 2. 007 P,4nt er Lake Elementary School TIC 23 otax I.:�pibject�.tl k00�}1�7A�Ftepunz�illtl"I`e�r,do� Appendix D—Preliminary Geotechnical Report Associated aEaA Sciences, Inc. E N 0 0 Cefe6r(I nS O�er 25 Vearil o[SErviee February 13, 2008 Project No. KE050647B Federal Way School District No. 210 c/o Greene-Gasaway Architects, PLLC P.O. Box 4158 Federal Way, Washington 98063 Attention: Mr. Jeff Greene Subject: Additional Subsurface Exploration and Supplemental fieotechnical Engineering Deport New Panther Lake Elementary School 34424 - I" Avenue South Federal Way, Washington Dear Mr. Greene; We- are pleased to present the following supplemental .report to our original "Subsurface Exploration, Geologic Hazard, and Preliminary Geotechaical Report." for the referenced project dated December 21, 2007. This report supplement presents additional explorations excavated on the north side of the property in an area that was not explored during our December 2007 exploration program. The location of the project site is shown on the 1 "Vicinity Map," Figure 1. The existing site conditions and approximate locations of the explorations accomplished for this study and our previous study are presented on the "Site and Exploration Plan," Figure 2. Purpose and Authorization The purpose of this study was to provide additional subsurface data across the north half of the property to be used in the preliminary design of the project. This area was not explored during our December study due to drill rig access limitations. Written authorization to proceed with this study was granted by Mr. Jeff Greene of Greene- Gasaway Architects, PLLC (GGA) on behalf of the Federal Way School District No. 210 (FWSD) by signing our proposal and scope of work letter dated January 24, 2008. This report has been prepared for the exclusive use of GGA, FWSD, and their agents for specific Kirkland Everett y Tacoma 425-827-7701 425-259-0522 253-722-2992 www.ae$geo.com application to this project. Within the limitations of scope, schedule, and budget, our services have been performed in accordance with generally accepted geotechnical engineering and engineering geology practices in effect in this area at the time our report was prepared. No other warranty, express or implied, is made. Project and Site Description This report was completed with an understanding of the proposed project based on verbal information provided to us by GGA representatives, and review of preliminary site plans for the area north of the existing school provided to us via e-mail on January 21, 2008. We used this undated preliminary site plan as the basis for Figure 2 of this report. The area explored for this supplemental report is an undeveloped, wooded parcel located across the north side of the existing Panther Lake Elementary School grounds located at 34424 — ? Avenue South in Federal Way, Washington. The site is relatively flat with a gentle downward slope to the east with a topographic low near the center of the parcel. Vegetation across this parcel consists of a medium dense canopy of Douglas fir trees around the perimeter with scattered deciduous trees through the interior and a thick ground cover of salal. Subsurface Exploration Our supplemental field study included the excavation of six exploration pits to gaits subsurface information about the site, The pit locations are approximately shown on Figure 2, "Site and. Exploration Plan." The various types of sediments, as well as the depths where characteristics of the sediments changed, are indicated on the exploration logs attached to this report. The depths indicated on the logs where conditions changed may represent gradational variations between sediment types in the field, Because of the nature of exploratory work below ground, extrapolation of subsurface conditions between field explorations is necessary. It should be noted that differing subsurface conditions may sometimes be present due to the random nature of deposition and the alteration of topography by past grading and/or filling. The nature and extent of any variations between the field explorations may not become fully evident until construction. If variations are observed at that time, it may be necessary to re-evaluate specific recommendations in this report and make appropriate changes:. The six exploration pits (EP-1 through EP-C) were excavated on January 30, 2.008 utilizing a track -mounted excavator under subcontract to our firm. The pits permitted direct, visual observation of subsurface conditions. Materials encountered in the exploration pits were studied and classified in the field by an engineering geologist from our firm. All exploration pits were backfilled immediately after examination and logging. Selected samples were then transported to our laboratory for further visual classification and .testing, as necessary. 2 Subsurface Conditions Subsurface conditions at the project site were inferred from the field explorations accomplished for #his study, visual reconnaissance of the site, and review of selected geologic literature. As shown on the field logs, the explorations generally encountered a surficial layer of forest duff/topsoil with one area of recessional outwash soils over glacially consolidated till soils. Strati Eaph Forest DafflOrganic Topsoil We encountered 8 to 18 inches of forest duff and organic topsoil within each of our exploration pits EP-1 through EP-6. The upper 4 to 6 inches of this unit generally consisted of decaying organic material (typically fallen leaves and fir needles) over the organic topsoil and root zone. This material should be stripped from the site at the onset of site grading operations. Vashon Recessional Outivash Natural sediments encountered beneath the organic topsoil within exploration EP-5 consisted of medium dense to dense, moist, gray, medium sand, little gravel, trace silt interpreted as Vashon recessional outwash. Recessional outwash soils typically consist of an unsorted mixture of silt, sand, and gravel deposited by meltwater streams from the retreating glacial ice during the Vashon Stade of the Fraser Glaciation approximately 12,500 to 15,000 years ago. This material. is considered :suitable for support of foundations, floor slabs, and paving with proper preparation. Vashon Lodgement Till Natural sediments encountered below the recessional outwash sails in exploration EP-5 and below the organic topsoil near the surface in EP-1 through EP-4 and EP-6 consisted of medium dense to very dense, medium- to fine-grained sand with variable amounts of silt, gravel, and cobbles with occasional boulders. These sediments were interpreted to be representative of Vashon lodgement till. Vashon lodgement till consists of an unsorted mixture of silt, sand, gravel, and cobbles that was deposited by basal, debris -laden glacial ice during the Vashon Stade of the Fraser Glaciation approximately 12,500 to 15,000 years ago. Lodgement till typically possesses high -strength and low -compressibility attributes that are favorable for support of foundations, floor slabs, and paving with proper preparation- The high relative density characteristic of Vashon lodgement till is due to its consolidation by the massive weight of the glacial ice from which it was deposited. In the areas such as the subject site, where Vashon lodgement till sediments are exposed at or near the ground surface, the density of the upper 1 to 21/2 feet of the Vashon lodgement till typically becomes reduced to a loose to 3 medium dense state by weathering. Where the weathering process rendered these soils loose, the weathered till is not suitable for direct foundation support, but may be suitable for reuse as structural fill provided it can be properly moisture -conditioned and compacted to project specifications. Our interpretations of subsurface conditions ou-site are consistent with a published geologic reap of the area (Geologic Map of the Poverty pay 7.5' Quadrangle, King and Pierce Counties, Washington, by Booth, Waldron, and Troost, 2004). Hydrology Light ground water seepage was encountered within exploration pit EP-5 at the time of our site exploration within the recessional outwash soils "perched" atop the lodgement till soil. It is typical for ground water to "perch" above the relatively impermeable fill soils and within the more permeable recessional outwash or weathered till. Perched conditions develop in the winter and spring months. It should be noted that fluctuations in the level of ground water may occur due to the time of the year and: variations in rainfall, and may occur randomly. Laboratory Testing We completed three grain -size analyses and six moisture contents to further classify the existing site soils. We provided recomulendations regarding the use of on -site soils within the "Structural Fill" section of our referenced December 2007 report. The lab results are attached to this report. Pit # Depth (feet) % Moisture % Gravel' % Sand, % Silty 1 5 8.0 44.4 26.1 29.5 2 4 10.3 --- --- --- 3 4 6.7 68.7 19.2 13.1 4 5 9-7 --- --- -- 5 4 5.7 74.1 21.1 5.8 6 4-- 1 - % Gravel = amount retained on the #10 (10 openings per inch) screen 2 - % Sand = amount retained on .the /1200 screen less the % gravel 3 - % Silt = amount passing the #200 (200 openings per inch) screen * Sample #5 consisted of recessional outwasb soils, all other samples consisted of native till soils a Conclusions The existing subsurface conditions encountered within the exploration pits excavated on January 30, 2008 are consistent with the subsurface conditions encountered within the exploration borings advanced for our December 2007 preliminary report. Therefore we conclude that the geologic hazards and mitigations and the preliminary design recommendations contained within our original "Subsurface Exploration, Geologic Hazard, and Preliminary Geotechnical Report" dated December 21, 2007 are applicable to the entire Panther Labe Elementary project site. If you should have any questions or require further assistance, please do not hesitate to call. Sincerely, ASSOCIATED EARTH SCIENCES, INC. Kirkland, Washington. Jess Overton, P.G. Project Geologist Attachments: Figure 1: Vicinity Map Figure 2: Site and Exploration Plan Exploration Boring. Logs Laboratory Testing Results morld KE050647B3 Projeis120050647UM\W P Jr' tit wns��� 235$D a NOV FJ�P�FIES 1112010 Kurt D. Merriman, P.E. Principal Fngineer ,- .'....y:,< ?'�T{• .5.` ,. '..7. )' ... '•,fir (/� `.I•' -Im,"� v��: •`• rv.:§Z�F yn� ..4=__J' j� I•tY.•• �. '" �L{� � ;- � 1.�+ ''� } nit •� - 1 sµ7'p6�A3i! �IIU!S'!A lY9SO 41�S J Q Q = z U O Lu F— L> Z tLl J w L7 S LEJ z R Lb C) ION, U O iayfL,2d IHS[ EP-3 APPROXIMATE LOCATION OF EXPLORATION PIT p TYP EP-4 Ep T EB EB-66 J- 4 pi ►.: r', `I, I ' L,— sS:.LI ;U- Um, ZEN EB .1 11,55 �e vul B- ti pp== EB E134 Eq-3 L APPROXIMATE LOCATION N OF EXPLORATION BORING o. TYP NO SCALE FIGURE I Nssociated Earth Sciences, Inc. SITE AND EXPLORATION PLAN PANTHER LAKE ELEMENTARY SCHOOL DATE 210B FEDERAL WAY, WASHINGTON PROD. NO. KE0506478 p . a, ti Well graded gravel and Terms Describing Relative Density and Consistency " b a, GW g ravel with sand, little to Densl 51'T�bfoWSlfotlE ( si �O�p no Fines Vim' Loose D to 4 N W s i a o oa n c Poariy-graded gravel C:oarse� Grained Sorts Md um Dense il) to 30 Test Symbols ,3 m NI -0* oc GP and gravel with sand, Dense o C ��oflo a o A tittle tD no fines Very Dense >50 G -Grain S¢e M = Moisture Content N a � ti Co c opaoo f i6nSl3rency SPTEZiblowsffoot A= Atlerberg Limits a . ° Silty gravel and silty Very Sots 0102 C = Chemical a N W -E - GIYI gravel with sand l tne- soft 2 to 4 DD = Dry Density o — ID F s ... Grained Solis Medium SO4 to t{ = Parmeabililit stiff 8 to l5 r Clayey gravel and very stiff i 5 to 30 At tyc clayey gravel with sand Hard >3A Component Definitions h Well -graded sand and Descriptiya 'perm Size Range and Slave Number r_ n syy sand wiIh.gravel,106 Boulders Larger than 12' U a d : to no fines Cobbles T to 12" g tL m . Gravel X to No. 4 (4,75 mm) 0 > to _ r Poorly -graded Goarsd Gravel 3'to3/V rn 1:10 w - SP and sand with gravel, Fine Gravel 3/4" to No. 4 (4.75 mm) m `a cr little to no limes Sand No: 4 (4.75 mm) to No. 200 (4.D75 mm) c m Q a Coarse Sand No_ 4 (4.75 mm) to Nm 10 (2.00 mm) 0 w Silty send and Medium Sand No. 10 (2AD mm) to No_ 40 (0,425 mm) m ro_ e WWS � r S silty sand with Fine Sand No. 40 (D.425 mm) to No_ 2V0 (0.075 mm.) 0 a c - gravel Sill and Clay Smaller than No, 20D (0.075 mm) in X Clayey sand and P) Estimated Percentage Moisture Content SC clayey sand wiiti gravel Punta e b Dry -Absence of moisture, rn Comment_ dusty, dry to the touch Trace rb Slightly Moist - Perceptible Silt, sandy silt, gravelly sill, Few 51010 moisture sit( with sand or gravel tattle 15 to 25 Moisl - Damp lout mvisbte With - Non -primary coarse water Gfay of low to rstedium constlhienis: > 15% very Moist - Waler visible but 5� 1, �lasticl k-2-��E—Ec4)LL si4l sand ofFines ty'Y'y'596 content betweeno hot Irme draining c yp gravellyclay, lean clayfrom and IS"ti Wet - Visible free wafer, usually below water table Organic; clay or silt of low Symbols plasticity $lowsl6' Pr = Sampler portion ors, Cement grovi — — Typa suslacp seat ' Elastic sill, clayey slit, silt 2.D OD 58mP3er 7y� Bentnnile _ d MH with m1caceou8 or Description SplitSpIn!,„ 1+1 seat ❑ diatomaceous fine sand or Sampler3.0' QD SpG1 Sp❑on5arrspler - pack VAh *! a silt(SPT)3 25' OD Split -Spoon Ping Sampler [+r : = bfankcasing v' 6 Clay of high plasticity, -: seclim &a C❑ 'v o c Lo GH sandy of gravelly clay, fat Buik sa 3.(r OD Thin -Wall Tube Sampler -' Screened casing r ro E cla with sand or rave) includin 5hetb tube w Hydiotlpyg 9 y ) ++nth Iflerpack Grab Sa EndA m C _Q ir'i/ f�,f; Organic clay or silt of Portion not recovered i1 J 0" medium to high i'i Percentage by dryweight r4) Depth of ground water r%f'%� f��r! pta:Slfcity 12) (S Standard Penetration Test � X RTD = At lime of driping (ASTM O-15g6) Static water level. (date) t.. > Peat, muck and other fat In General Accordance Wlh w a, a,'Q PT highly organic. soils Standard Practice for Description tsi Combined USCS symbols used for = p and Identification of Soils (ASTM D--2488) fines between 5'%and 15% it 9 classiritaQris of soils in this report are based on visual livid and/or laboratory obaervalli nm. whith include densitylconshlaticy, moistvn condition, grain size, and plasi;city estimates and should not be conslrvad In empty field or Iaboralory testing unless pmsehled herein. Visuabmanual andlor laboratory classification i methods of ASTM t]2457 and U•24Be were used as an idemifrmtion gu4n for the Unified 54M ClasslficaSiRn System. y 5 — _ Isoci.ated Earth Sciexices, Inc. EXPLORATION LOG KEY FIGURE At o _ 1 2 - 3 4 - 5- 6 7 - 8 9 - 10 11 12 - 13 - 14 - 15 �- 16 17 - 18 - 19 - LOG OF EXPLORATION PIT NO. EP-1 This log is part of the report prepared by Associated Earth Sciences, Inc. (AESI) far the named' roject and should be read together with that repvrl Far corn fete InterprelaUm. This summary applies only to the lawkian of this french at the line of eica4en of a [Subs neo dltWnsencountered.ionsange at this location with the passage of time. The data presented are DESCRIPTION roreta vu,1i 1 vYawu —�- — Weathered Till Medium dense, moist, brown, silty SAND, trace gravel Vashon L.odge►nent Till Dense to very dense, moist, gray, slaty SAND, little gravel, trace cobbles. Very very dense below 4.5 feet. Bottom of exploration pit at depth 10 feet Panther Lake Elementary School Federal Way, WA Associated Earth sciences,, Inc. Lagged by: JAa Approved by: Project No. KED50647B 1/30/08 LOG OF EXPLORATION PIT NO, EP-2 717is lag is part of the n par# prepared by Assodaled Earth S�Jenees, Ina. (AESI} for the named project and should be for fnterpretalion. 'Phis CL read tagethor rvilh Thai report camppl,te su ,I y applies only la She taro ion of this trench at the lime of excavation. Subsurface conditions may r>�ange at this lacalion with the passage of time. The data presented are a simplRmUon of actual conditions encountered. DESCRIPTION Forest Duff/Topsoil Weathered Till 2 Vashon Lodgement Till 3 Dense to very dense, moist, gray, silly SAND, little gravel, trace cobbles. 4- 5 - 6 Very very dense below 6 feet~ 7 9 Bottom of exploration pit at depth 8 feet 10 11 12 13 14 15 16 17 18 19 Panther Lake Elementary School Federal Way, WA A,ssodated Earth Sciences, Inc. Project No. KE050647B Logged by: JPO Approved by: 1130108 LOG OF EXPLORATION PIT NO. EP-3 7tds log is garf of the repflrt prspared by Assflciafed Earth Sr�onoes. Inc. (AE53) far the named project and should be read iagelher"0," trial report fnr complete interpretation. This summary apgplies only to the local;.. VIM trench aL tyre time a€ excavatlon. Subsurface conditions "'ay? ay change at Ihis location uAih ttsfl passage of time, The data presented are o a sirnplf aftn of actual conditlons encountered. DESCRIPTION 1 Weathered Till Medium dense, moist, brown, silty SAND, little gravel. 2 Vashon Lodgement Till Dense to very dense, moist, gray, silty SAND, little gravel, trace cobbles. 3- 4 Very very dense below 4 feet. 5 - 6 7 8 - - Bottom of exploration pit at depth 8 feet 9 10 11 -12 13 14 15 16 - 17 18 - 19 - n Panther Lake Elementary School Federal Way, WA Asstaciattied Earth Sciences, Inc. Project No. KE050647B Logged by: JPO ry I/30/08 Approved by : LOG OF EXPLORATION PIT NO. EP4 UZ This lag Ls partof the report prepared by Associated Earth Sciences, Inc. [AE51] for the named project apd, should be � read =o9ether wlfh that report for comptete inlerpreiaiian. This summary a��ppplies only to the lacailon of this frenr� at the tlme of excavatlon. Seh2%ce candl ons may change at this location YA1 the passage of time. The data presented are ❑ a simpl5rxtion of actual conditions encountered. DESCRIPTION Forest Dui`ffFopsoil 1- Weathered Till Medium dense, moist, brown, silty SAND, trace gravel. 3 Vashon Lodgement `Fill 4 !Dense to very dense, moist, gray, silty SAND, little gravel, trace cobbles. 5 Very very dense below 5 feet. ti 7 — 8 9 19 - 11 Bottom of exploration pit at depth 10 feet 12 13 14 15 16 17 18 19 - Panther Lake Elementary School Federal Way, WA Ass6da#ed Earth Sciences Inc. Project Logged by. JPO ® ' j No. KE050647B Approved by: } 1130108 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 LOG OF EXPLORATION PIT NO. EP-5 This log is pan of the repots prepared by Associated Earth Sdences, Inc.(At=Sl) for the named rolect and should be read to ether with ihat report for ❑orn leie interpretation. This summary a plies only to the incatlon of this trench at the Hme o€ excavation. Subsurface conditions may ehango at this iocallon wi the passage of time. The data presented are a simpification of actual conditions encountered. DESCRIPTION Vashon Recessional Outwash Medium dense to dense, moist, gray, medium SAND, little gravel, trace sift. Very vary light seepage at approximately 6 feet. Vashon Lodgement Till Dense to very dense, moist, gray, silty SAND, little gravel, trace cobbles. Bottom of exploration pit at depth 10 feet Panther Lake Elementary School Federal Way, WA Logged by: JPa Ass6dated Earth Sciences, Inc. Project No. KE050647B ApprovedM , by: 1130108 a Ed a m a 1 2 3 4 6 7 B 9 10 11 12. 13 14 15 16 17 18 19 LOG OF EXPLORATION PIT NO. EP-6 This tag [s part of the report prepared by Associated Earth 5clences, lno. (AE513 for the named proiec! and shau3d he read tapaiher with Ihat report for r�mppl�le in€erpretatian. This svmrnary appplies on€y to tho location of this french at the time o excavafivn, Subsurface corsdiflvns may change at Ibis toca�on with the passage of8me. The data presented are a slmpifisailon n€actual tondltlans encnuntared. DESCRIPTION Weathered Till Medium dense, moist, brown, silty SAND, trace gravel. Vashon Lodgernent Till Dense to very dense, moist, gray, silty SAND, little gravel, trace cobbles. Very very dense below 6 feet. Bottom of exploration pot at depth B feet Panther Lake Elementary School Federal Way, WA Asskiat-ed Barth Seienees, Inc. Lugged by. dP0 Approved by_ _ Project No. KE050647B 1130108 GRAIN SIZE ANALYSIS - MECHANICAL Date Project Project No. Soil Description _//3012008 Tested By MS Panther Lake E. Location Onsite KE050647B EB/EP No ^ EP-1 11ep(h 5' - GRAVEL with sand,silt Wt. Of wet sample + Tare 2006.83 Wt. of Dry Sam le +Tare 1879.93 Moisture % $ 0 Wt. of Tare 298,22 Wt. of [] Sam ie 1581.71 After Wash Wei ht +Tare 1421.03 Specification Fla uirarr Slave No. 3.5 3 2.5 2 1,5 1 314 3/6 #4 #8 #10 #20 #40 #60 # 100 "^^^ Diam_ mm 90 75.1 64 50.8 38.1 25.4 19 9.51 4.76 2,38 2 0.85 0.42 0.25 0.149 074 Wt. Retained 0 0 0 0 0 90.71 25052 449.85 604.14 686,08 701.84 765Ai 837.77 931,65 1033.99 1 115 58 % Retained 0.0 0,0 0.0 0.0 0.0 5.7 15.8 28.4 38.2 43.4 44.4 48.4 53.0 58.9 65.4 70 5 % PaEs7ing 1 MCI 100.0 100.0 100,0 100.0 94.3 84.2 71.6 61.8 56.6 55.6 51.6 47.0 41.1 34.6 1 29.5 Minimum Ma 1 1 1 1 100 80 c 60 ii 1= U Q1 40 n. 20 0 100 0. us s-rANDARD SIEVE NOS. 3° 34" NO 4 NO 16 NO-40 NO 200 is um 10 1 0A 0,01 Grain Size, mm ASSOCIATED EARTH SCIENCES, INC. 911 5Eh Ave . Suile 100 Kirkland. WA 98033 425-827-7701 FAX 42"27-5424 GRAIN SIZE ANALYSIS - MECHANICAL Date Project Project No. Soil Description 1/30/2008 Panther Lake E. KE050647B 'rested By Location EB/EP No I Depth GRAVEL with sand few silt MS ❑nsite EP-5 4' Wt. Of wet sample +Tare 2158.77 Wt. of Dry Sample + Tare 2058.02 Wt- o€Tare 296.06 .Moisture% 5.7 Wt of Dry Sample 1761.96 ,After Wash Weight +Tare 1957.38 Specification Reauirements Sieve No. Dim. mm Wt. }retained % Retained % Passinq (Minimum Maximum 15 90 0t 0.0 100,0 3 76.1 0 0,0 100.0 2.5 64 0 0.0 100.0 2 50,8 () 0.0 100.0 1.5 36.1 0 0,0 100.0 1 25.4 305.32 17.3 82.7 3/4 19 666,07 37.9 62.1 3/8 9.51 993.31 56.4 43.6 94 4,76 1165.14 66,1 33.9 #8 2.38 1281.27 72.7 27.3 #10 2 1305-83 74.1 25.9 #20 0.85 1399.43 79.4 20.6 #40 0.42 1490.09 85.0 15.0 #60 0.25 1583.85 89.9 10.1 #100 0,149 1632.68 92.7 7.3 #200. 0.074 1658.97 94.2 5,8 100 80 20 0 100 US STANDARD SIEVE NOS. 9" 3/4." N04 N0,16 NO,40 NO.200 10 1 0.1 Grain Size, mm ASSOCIATED EARTH SCIENCES, IlvC< 911 51h Ave . Suiie 100 Kirkland. WA $B033 4E5.827-7701 FAX 425-827.5424 0,01 GRAIN SIZE ANALYSIS - MECHANICAL Date Project Project No. Soil Description 113012008 Panther Lake E. KE050647B EB1EP No 14' Depth GRAVEL with sand little slit Tested By Location MS Onsite EP-3 WL. Of wet sa►nple + Tare 2212.31 Moisture 0/6 6.7 Specification Requirements WL of Dry Sam 1e +Tare 2105.94 Wt. of Tare 511.65 Wt. of Dry sample 1594.29 After Wash Weight + Tars 1903.23 8ie�e No. Diam. mm WL Retained % Retained % Passing_Minimum Maximum 3.5 90 0 0.0 100.0 3 76.1 0 0.0 100.0 2.5 64 0 0.0 100.0 2 50.8 0 0.0 100.0 1.5 38.1 {I 0.0 100.0 1 25.4 1 211.28 13.3 86.7 314 19 473,54 29.7 70.3 318 9.51 312.11 50.9 49.1 :#4 4.76 9911.51 62.2 37,8 #8 2-38 1081.06 67.8 32.2 #1 D 2 1095.26 68.7 31.3 1#20 0.85 1140.27 71.5 28.5 #40 0.42 1194.71 74.9 25.1 #60 0.25 1267.54 79.5 20.5 #100 0-149 1331.3 83.5 16.5 #200 0.074 1385.71 86.9 13.1 US STANDARD SIEVE NOS, 3" 3/4' NOA NO 16 NO.40 NO 200 100 80 #4 Ilwllw'iss. I)•Ilw�■■E■n�l•111•w a ASSOCIATED A ARTH SCIENCES, INC. 9.11 51h Ave., Suite 100 Kirkland, WA 96033 425.827-7701 FAX 425-327.5424 Associated Earth Sciences, Inc. Moisture Content 4 ASTM D 2216 Ld Date Sampled Project Project No. Soft Description 113012008 Panther Lake Elementary KL050647B Various Tested By Location EBlEP No. Depth MS ❑nsite Sample ID EP1-5' EP2-4' EP"3-4' Wet Weight + Pan 20068 1487,6 2212.3 Dry Weight + Pan 1879.9 451.1 2105,9 Weight of Part 298-0 98,7 511.7 Weight of Moisture 126.9 36,4 106.4 Dry Weight of Sail 1581.9 352.4 1594.3 % Moisture 8.0 10.3 6.7 Sample ID EP4.5' EP5-4' EP6-4' Wet Weight + Pan 521.1 2158.6 51.7 1 Dry Weight+ Pan 483.9 20580 4733 Weight of Pan 99.9 296.1 1009 V' -ht of Moisture 37.2 100,8 43.8 U eight of Soil 3€14.0 1762.0 372,4 % Moisture 9.7 5.7 11.8 ASSOCIATED .EARTH SCIENCES, INC. 911 6th Ave , &HO 100 KWand, WA 9803 425-827-7701 FASCO2 27-5424 Scorn 7--tether Permits Water and sewer permits will be required from Lakehaven Watei and Sewer E3istrid for wieet and sewer installation These .permits will b°-e acquired priorto construction, MI �I Panther Lake Blem.eniary Sckobl TIR 14 - • otak %;'•prnjc.rl3 E M0131.F�7r11Re{ran s177Rti'S'rxr.�lee Section Eight Section 8— Construction Stormwater Pollution Prevention Plan (CSWPPP) Analysis and Design _l An Erosion and Sediment Control Plan is included with the construction plan set. A CSWPPP is included in Appendix F. This TESL plan includes temporary erosion and sediment control measures in compliance with Appendix D, Erosion and Sediment Control Standards, and Core Requirement #5, Erosion and Sediment Control, of the 2005 King County Surface Water Design Manual. The following items are addressed: • Clearing Limits ■ Cover Measures a Perimeter Protection _ a Traffic Area Stabilization Y Sediment Retention E Surface Water Control Dust Control ■ Spill Control 0 Wet Season Construction Maintenance - • Final Stabilization _I Bast Basin. - A temporary sediment basin has been designed to treat the onsite stormwater .runoff from the east basin. The sediment basin will be located near the east property line and will be used during the period of time that the new school is under construction to meet NPDES requirements and until the existing school is razed, and reestablished as a performance sports field to control peak stormwater runoff. See Appendix E.2 for 1 sediment pond sizing information_ The existing stormwater outfall for the adjacent King County Library site will be re- directed around a proposed wall and areas of disturbance during the TESL condition, A temporary 87 foot 18-inch diameter pipe will convey flow, and will discharge along the existing drainage course, at a location near the east property line. Outlet protection per the 1998 KCSWDM will be used at the pipe outfall. Panther Lake Elementary School TIR 25- _J of8k Ke\pr,ipa\11!00IJ!!47Ali ",n-,V'PI€ V1'mr.dac Section 8—Construction Stormwater Pollution Prevention Plan (CSWPPP) Analysis and Design Continued A conservative approach was used to show that the temporary sediment pond would be of adequate size for all phases of construction. Exposed soil during constructioncan be .modeled as till grass, and construction vehicle access areas can be modeled as impervious. The storm event runoff values used in sizing the temporary sediment pond. are conservative because .final grade areas for the developed east basinwereused. East TESC Pond Sizing. Areas Total east basin area (acres) = 3.13 Impervious area (acres) = 1.47 Pervious area (acres) = 1.67 This assumption is a worst case scenario for all phases of construction. See Appendix E for area delineation exhibit, temporary sediment pond, principle spillway, and emergency overflow spillway calculations. The required sediment pond volume was computed for the east sediment :basin using the 1998 KCSWDM equation D.4.5.2. Here the required surface area was computed for the 10-year runoff event. This surface area was then .multiplied by the 3,5-foot setting depth and a. required volume was computed. The proposed sediment pond includes 1.5-feet of sediment storage and 1-foot of freeboard.. Sediment SA Pond I lsfy EAST POND 1 1171 Setting depth Required Vol (f �) M 35 4099 Panther Lake Elementary Scbool TZR K\.proircr\31€O6\.3ID 7A\Repons\T1KNText.tioc. Provided Vol (cf) .oe• 26 otak Section 8—Construction Stormwater Pollution Prevention Plan (CSWPPP) Analysis and Design Continued Nest Basin i The existing 90 LF of 72-inch detention pipe, as well as the proposed 128 LF of 54-inch -1 detention pipe will be used as sediment basins during the period of time that the new school is under construction to meet NPDES requirements and until the existing school is razed, and reestablished as a performance sports field to control peak storrnwater runoff. The tributary areas to each sediment basin are shown below. See Appendix E for sediment pond sizing information. The storm event runoff values used in sizing the temporary sediment pond are conservative because final grade areas for the developed west basin were used. TESC Areas to Existing West Detention Tank Total west basin area (acres) = 0.808 Impervious area (acres) = 0.73 Pervious area (acres) = 0.078 ` TESC Areas to Proposed West Detention Tank Total -lest basin area (acres) = 1.07 Impervious area (acres) — 0.92 I Pervious area (acres) = 0.15 - S This assumption is a worst case scenario for all phases of construction. See Appendix E for area delineation .exhibit; temporary sediment pond, principle spillway, and ` emergency overflow spillway calculations. 1 Panther Lake Elernentary School 7'IR 27 otak K:\gojen131dOfl�tliirA\Repairs\'I"IR1Texs.dx 1I J Section 8—Construction Stormwater Pollution Prevention Plan (CSWPPP) Analysis and Design Continued The required sediment tank volume was computed.for each sediment basin using the 1998 KCSWDM equation D.4,5,2. Here the required. surface area was computed for the 2-year runoff event. This surface area was then multiplied by the 3.5-foot setting depth and a required volume was computed.. Each of the proposed sediment tanks includes 0.5-feet of sediment storage and 0.5-feet of freeboard, as used in the permanent condition. Sediment SA Setting Required Provided Pond (sf depth (ft) Vol (cf) Vol (cf) EXIST Tank 440 3.5 1538.54 2342 NEW Tank 492 3.5 1720.83 1826** 1699 CF provided in 128 LF of 54-inch diameter detention pipe, and additional 127 CF is provided by the two 54_inch manholes, each with 4-foot sumps. Panther Lame Elementary School TIR K:tprajrc[\31100a 311.17A\RcpattsMMTm.dw 28 otak Appendix E.I West Sediment Tank Sizing Calculations Pond Sizing (D.4.5.2, KCSWM 1998) - FWSD Panther Lake Elementary Max .side slopes = 3:1 = 2 x Q21(0.00096 ft/s) = (2080 ft/s) x Qz (measured at the top of the riser pipe) where Q2 = peak discharge from the developed 2-year runoff event from the contributing drainage area Site Input Parameters Iculate SA:' Sed FS VS Q7 SA Pond W-EXIST 2 0.00096 0.21. 440 W-NEW 2 0.00096 0.24' 492 Sed SA" Length Width L:W Ratio Pond W-EXIST 440 40 11 164 W-NEW 492 40 12 3.25 *measured at top of riser pipe" * runoff was calculated using KCRTS Sed Setting .depth Required Provided Pond SA (sib (ft) Val .(af) Vol (on W-EXIST 440 8.5 1588-54 2342 W-NEW 492 345 1720.83• 1826** " 1699 CF provided .in 128 LF of 54-inch diameter detention pipe, and additional 127 CIF is provided key the two 54-inch manholes, each With i 4-foot sumps Panther Lake Elementary Otak K:lproject131100131147A1WaterRes\TESCISedimejit.xis Pdrltft 10f1312008 Principle Spillway (Riser Pipe Diameter)** **A permenant control structure may be used instead of a temporary riser. Qwair 9.739 D H"2 Qodfirs _ 3.782 D? W"2 H �1 ft Sed Q10* ! DorHrce Dminitnurn Pond (cfs) DWOiF (#) (ft) (ft) _ W-EX STI 0.26 0.03 1 0.50 0.50 W-NEW 0.29. _ 0.03 1 0.53 _ 0.53 * runoff was calculated using KCRTS Ernergency Overflow Spillway Q = C*(2g)1r2*L(W3)L*H3r2+ (8/15)*TAN(T)*H52] where: C= 0.6 and Tan(T) = 3 (for 3:1 slopes) Therefore, Q = 3.21 *LL*H312 + 2.41 *H5121 Sed Pond Q10o.* (cfs) H (ft) L (ft) Q100 design (ft) W-EXISTS [?. 1 0_1_7.._ 0.50 6.00 8.18 W-NEW 6 U0 5.66 * runoff was calculated using KCRTS Panther Lake Elementary K:Iproject131100131147A1W aterRes\TESCISediment.xls Otak Printed: 10/13/2008 watering Orifice A. (2h)o s 0.6 (3600) Tg°.s Ao = orifice area (sq ft) k = pond surface area (sq ft) h = head of water abover orifice (height of riser in feet) T = dewatering time (24 hours) g = acceleration of gravity (32.2 feetlsecon.d2) ©- orifice diameter (in) =13.54 A " Dt= minimurn perforated tube size (in) SO Pond h (ft) Ao (sq ft) D (in) Dt (in) W-EXIST 5 0.0047 0.93 2.93 VV-NEW .3.5 0.0044 0190 2 90 Panther Lake Elementary otak Mproject131100131147A1W aterRes\TESC\Sediiment.xls Printed: 10113/.2008 Appendix E.2—East Sediment Pond Sizing Calculations Pond Sizing (D.4.5.2, KCSWM 1998) - Panther Lake Elementary Site East Basin Max side slopes = 3*1 SA = 2 x W(4.00096 ft/s) = (2080 NO x Q2 (measured at the top Of the riser pipe) where 02 = peak discharge from the developed 2-year runoff event from the contributing drainage area flats .SAS ..i FS Sod V. 010 1 SA Pond 1 2 :. OA0096 1171 Sod Pond SA** ;Length ' Width L:W Ratio 1 I 1171 66 ! 18 3.72 *-010=10-yr peak flow rate for the east basin used to provide a hlgher level of downstream protection per section the 1098 KCSWDM section D.4.5.2 **measured at top of riser pipe 3,5 foot miry depth .Panther Lake_Elementary Otak K3project%31IOQ131147ANW.aterR9s\TESC\tESC Pond.xis, Printed: 10113/2000 Principle Spillway (Riser Pipe Diameter)' **A permenant control structure may be used instead of a temporary riser. QWak 9.739 D H3'2 QariiTce 3.782 D2 H112. 1 ft H Sod Pond Q10* (cfs) dweir (ft) Dorifice DmPnimum (ft) (ft) 0.39 0,39 1 `` u6 _; 0.06 *Qjo = 10-yr peak flow rate for the east basin Emergency Overflow Spillway Q = C*(2g)"2*[(2/3)L*H" t (8/15)*TAN(T)*H-9"'] where: C= 0.6 and Tan(T) = 3 (for 3:1 slopes) Therefore, Q = 3.21 *[L*H3/2 + 2.41 *HW21 Sed Pond QI60** (cfs) H (ft) L (ft) Q100 design (ft) 1 W 0..97. j 0.30 6.00 3.55 'QjQQ =100-yr peak flow rate for the east basin => use 1.5 ft Panther Lake Elementary Ptak K:t3rojed\31I00131147A1WaterRes\TESCITESC Pond.xls Printed; 10/13/2008 sed_east,pks Flnw Frequ:enCy Analysis Time series Fi7e:sed_east.tsf Project Location:Sea-Tac ---Annual Peak FloW Rates•--- ------Flow Frequency Analysis------- FlowRate hank Tire Of Peak - - Peaks - - Rank Return Prob (CFS) (CFS) Period 0.478 .5 2/09/01 2:00 0.969 1 100.00 0.990 0.374 ..8 1/05/02 16:00 0.572 2 25.00 0.960 0.572 .2 2/27/03 7:00 0.562 3 10.00 0.900 `1 0.387 7 8/26/04 2:00 0.508 4 5.00 0.800 ` 0.468 6 10/28/04 16:00 0.478 5 3.00 0.667 0.508 4 1/18/06 16:00 0.468 6 2.00 0.500 0.562 10/26/06 0:00 0.387 7 1.30 0.231 0.969 .3 1 1/09/08 6:00 0.374 8 1.10 0.091 computed Peaks 0.837 50.00 0.980 Page East Sediment Pond Volume Calculation ELEV CELL1 TOTAL AREA VOLUME CHANGE VOLUME TOTAL ft sq ft Cu ft Cu ft BOTTOM 250.50 173 Bottom TOP SED 252,00 836 1 0 0 253.00 1,406 1,121 1,121 254.00 2,072 1,739 2,860 255.00 2813 2,443 5,303 'WQ WSE 255.50 3,213 1,507 6,869 SPILLWAY WEIR 256.50 1 4,047 3,630 10,439 Required Volume (10-yr storm), cu ft = 4,099 Design Volume, cu ft = 6,809 Panther Lake Elementary K:1projedl13110D131147A1WaterResITESCIPONDVOLxis Otak Volume Printed: 11/10/2008 Appendix F—Construction Stormwater Pollution Prevention Plan CSWPPP in Stormwater Pollution Prevention Plan For Panther Lake Elementary School Prepared For -1 Northwest Regional Office 3190 - 160th Avenue SE Bellevue, WA 98008-5452 425-649-7000 I Owner . Developer Operator/Contractor Roes Leland .Rod Leland Rod Leland 1066 South 320th Street 1066 South 320th Street 1066 South 320th Street Federal -Way, WA 98003 Federal Way, WA 98003 Federal Way, WA 98003 Project Site Location A portion of the SW Quarter of Section 20, Township 21 North, Range 4 East, King County, Washington, at 34424 1 st Avenue South, Federal Way Certified Erosion and Sediment Control Lead Ray Smalling J 425-822-4446 1 SWPPP Prepared By 1 Ottak, Inc. 10230 NE Points Drive, Suite 400 Kirkland, WA 98033 425-822-4446 Veronica Sackett, Engineering Designer SWPPP Preparation Date August 20, 2)008 Approximate Project Construction Dates September 01, 2008 September 08, 2009 n 7.1.4 Updating the SWPPP ................................................ ......................... ....... ....32 7.2 Reporting ... :.....:.........:..... ..,.......... .:......................... .................. ....... ............................ ..:32 7.2.1 Discharge Monitoring Reports........... .................................. ............--32 7.2.2 Notification of Noncompliance.. ........................................ ................... ...... 32 AppendixA — Site Plans...............4................................................... ..... ........... ............. 34 Appendix. B Construction BMPs........................................................................................35. Appendix C — Alternative BMPs......................................................................... ...............36 Appendix D — General :Permit....................................................................................... ..39 Appendix E — Site.Inspection Forms (and Site log) .................................... ............. .............. 40 Appendix F — Engineering Calculations.................................................................................49 Appendix A Site plans Vicinity map (with all discharge points) �! Site plan with TTSC measures Appendix L' Construction BMPs ■ Possibly referennce in BMPs, but likely it will be a consolidated list so that the app:Iicant can photocopy from the list from the SW1 IM. Appendix C Alternative Construction BMP list TList: of BMPs not selected, bat can be referenced if needed in each of the 12 elements Appendix D General Permit Appendix . +' Site Log Vinci Inspection Forms Appendix.F Engineering Calculations (ifrlecessary) ■ Flows, ponds, etc... iii , StorMWater Pollution Prevention Plan 1.0 Introduction This Stormwater Pollution Prevention Plan WPM bas been prepared as part of the NPDES stormwater permit requirements for the Panther Lake Elementary School construction project in King County, Washington. The site is located at 34424 0 Avenue South, Federal Way, WA. The existing I I.1 S acre site is the location of the existing Panther Lake EIementary School. The proposed development consists of the construction of new school buildings, parking and drive aisles, and fire access. It also includes the installation of utilities, landscaping, and detention, pre-treatment, and water quality facilities. Constriction activities will include the construction of a temporary sediment pon , constructor of temporary interceptor ditches and rock check dams, clearing and grabbing, grading, Iinstallation of storm drainage improvements, installation of a temporary storm drainage system to be used with T.E.S.C. measures, installation of water and sewer utilities, construction of fire access, installation of fratichise (dry) utilities, excavation for building foundations, construction Iof new school buildings, demolition of existing school building, construction of parking and drive aisles, installation of landscaping, and installation of detention, pre-treatment, and water- quality facilities. The purpose of this SWPPP is to describe the proposed construction activities and. a]1 temporary and permanent erasion and sedixnent can trol (TESC) ni.castires, pollution prevcnhoil measures, inspectiOn/moatitosiag activities, and recordk.ceping that will be implemented during the.proposed coszstructnit project. The objectives of the SWPPP are to: . Implement Best ItImagcmcnt Practices (B1v[Ps) to prevent erosion and sedimentation, and to identify, reduce, eliminate or prevct)t stormwater cont�.uniration and water pollution frorrr constriction activity. _J 2, Prevent violations of surface water quality, ground water- quality, or sediment management Standards. 3. Prevent, dwitag the construction phase, adverse water quality impacts including impacts on beneficial uses of the receiving water by controlling peak flow rates and volialies of storniwater runoff` at the Perna.i.ttee's outfa.11s and downstream of the outfalls. This SVJPPP was prepared using the Ecology SWPPP Template downloaded from the Ecology ,vebsite on April 22, 2008. This SWPPP was prepared based on the requirements set forth in the Construction Stornawater General Penrait, Stornivvater lVIat2agonent 114'anual for YYestern ' Rlashingron (SWNN WW 2005). The report is divided into seven main seetioils with several appendices that include stosmwater related reference materials. The topics presented in the each of the main sections are: +� Section I INTRODUCTION. This section provides a summary description of the project, acid the organization of the SWPPP document. 5tormwater Pollution Prevention Plan 2.0 Site Description 2,1 Existing Conditions The proposed site is located at 34424 1"Avenue South, Federal Way, WA. A site vicinity .map is provided in Appendix A, The existing 11.15 acre site is the location of the existing Panther Lake Elementary School. The geotechnical investigation findings show that lodgement till make up the onsite soils. There are two separate threshold discharge: areas onsite, which flow east and west before joining together approximately 0.8 .miles downstream of the site, a location within the Hylebos Wetland Park, which is located south of the site. The east basin is composed of a portion of the north parking and drive lane around the east side of the building, grassy open spaces arid non -pollution generating rooftops, sidewalks and paved playgrounds. Storinwater generally sheet Flows east across the site flowing into a non - jurisdictional wctland located adjacent to the site. The west. basin is composed of rion- poll ution generating, rooftops and sidewalks in addition to three parking lets, "flee s.ou.thern parking lot passes through a Storiniilter catch basitrwith a cartridge before discharge. The middle bus drop-off parking lot, built in 2003, passers through a pair of Storm. lter catch basins then through a twin 72" diameter CMP by 42. L.F. flow control tank before discharge west to a catch balsln 111 I,'t Avenue. The north girl" ing lot is 11'ee draining to 1`rt AVen11e'Sc) Ith without treatment- 2.2 Proposed Construction Activities The proposed development consists of the construction of new school buildings located on the north portion of the site, and associated parking, drive aisles and fire access. Proposed development also includes the installation of utilities to the buildings, landscaping, a 54" underground detention pipe, two CDS pretreatment catch.basins, a 72"d.iaineter Stormfitter manhole with sdven cartridges, and an 8-foot by 16-foot Stortnfilter,vault. Constriction activities will include site preparation, TESL installation, construction of a temporary sediment pond, construction of temporary interceptor ditches and rock check darns, clearing and grubbing, grading, installation of storm drainage improvements, installation of a temporary storm drainage system to be used. with T.E.S.C. measures, installation of water and sewer utilities, construction of -fire access, installation of franchise (dry) utilities, excavation for building foilticlations, construction of new school buildings, demolition of existing school building, construction of parking and drive aisles, installation of landscaping, and installation of detention, pre-treatment, and water quality facilities. .The schedule and phasing of BMPs during construction is provided in Section 4.0. Stormwater Pollution PrMhtion Plsn The following summarizes details regarding site. areas: ■ Total site area: 11.15 acres K percent itnpervious area before construction: 30.50 % ■ percent impervious area after construction: 31.21 % r Disturbed area during construction: 7.2 acres Disturbed area that is characterized as impervious (i.e., access roads, staging, parking): 3.5 acres ■ 2-year stormwater runoff pear flow prior to construction (existing): l:t?4 cfs ■ 10-year stormwater runoff pear flow prior to construction (existing): 1.39 cfs 0 2-year stormwater nuloffpeak flow dutzrig construction. 1.15 efs ■ 10-year stormwater runoff peak flow dining con.Struction: 1.53 cfs 11 2-ye-ar storinwater runoff peak flow after construction: 1.15 cfs ■ 10-year stomwater nrnofrpeak flow after construction3: 1.53 cfs All stommater flow calculations are provided in Appendix F. Stormwater Pollution Prevention Plan 3,0 Construction Stormwater BMPs 3.1 The 12 BMP Elements 3.1.1 Element 91— Mark Clearing Limits To protect adjacent properties and to reduce the area of soil exposed to construction, the limits of' construction will be clearly marked before land -disturbing activities begin. Trees that are to be preserved, as well as all' -sensitive areas and their buffers, shall be clearly delineated, both in the field and on the plans. In general, natural vegetation and native topsoil shall be retained in an -undisturbed state to the maximum extent possible. The BMPs relevant to marking the clearing III -nits that will be applied for this project include: Preserving Natural Vegetation (BMP C101) • High Visibility Plastic or Metal Fence (BMP Cl 03) The Site Demolition Plan Sheet C1.01 shows tlac locations of existing trees to be protected. The T,E.S.C. Plan Sheet C2.01 delineates the clearing limits and. shows the construction fence and the combined corastrrrction fence with rill fence locations around the project heri.nieter. This fencing shall be if] stall ed prior to the start of Construction, Alternate BNl.Ps forrnarking cleraind limits are inclr.rded in Appendix C as a quick reference tool for the onsite inspector in the event the BNP(s) listed above are deemed ineffective or inappropriate during construction to satisfy the requirements set forth in the General NPD S Permit (Appendix D). To avoid potential erosion and sediment central issues that may cause a violation(s) of the NPDTS Construction Stormwater pennit (as provided in Appendix D), the Certified Erosion and Sediment Control Lead will promptly initiate the implementation of one or more of the alternative BMPs listed in Appendix C after the first sign that existing BMPs are ineffective or failing. 3.1.2 Element #2 — Establish Construction Access Construction access or activities occurring on unpaved areas shall be ininirnized, yet where necessary, access points shall be stabil[zed to minimize the tracking of sediment onto public roads, and wheel washing, street sweeping, and street cleaning shall be employed to prevent sediment from entering state waters. All wash wastewater shall be controlled on site. The specific BMPs related to establishing construction access that will be used on this project include-. -• Stabilized Construction Entrance (BMP C105) Stormwater Pollution Prevention Plan r 3.1.4 Element #4 — install Sediment Controls All stormwater runoff from disturbed areas shall pass through an appropriate sediment removal BMP before leaving the Construction site or prior to being discharged to an infiltration facility. The specific BMPs to be used for controlling sediment on this project include: ■ Silt Fence (Blt••TP C233) ■ Storm Drain inlet Protection (BMP C220) • Temporary Sediment Pond (BMP C241) The T,E.S.C. Plan Sheet C2.01 shows the silt fence and the combined construction fence with silt fence locations around the project perimeter, and it shows the locations of the catchbasins requiring inlet protection, The fencing and the inlet protections shall be installed prior to the start of construction. Plan Sheet C2.01 also shows the location of the, temporary sediment pond. This shall be installed prior to beginning inass grading operations. J Alternate sediiTient control BN4Ps are included in Appendix C as a quick reference too], for they onsite inspector in the event the BMP(s) listed above are deemed ineffective or inappropriate 3 during construction to satisfy the requirements set forth in the General NPDES Permit (Appendix D). To avoid potential erosion and sediment control issues that may cause a violati.vn(s) of the NI'DES Construction StOl-11M cr permit (as providers in Appendix D), the C:ertifed rrcrsion M'd Sediment Control Lead will premptl,, initiate the im.pleruexztatio.n of one ox inure of the alternative BNTPs listed in Appendix C aft..r the first sign that existing BMPs are ineffective, or failing. _ In addition, sediment will be removed from paved areas in and adjacent to construction work areas manually or using mechanical sweepers, as needed, to minimize tracking of sediments on ' vehicle: tires away from the site and to minimize washoff of sediments from adjacent streets in _ 1 runoff. 1 Whenever possible, sediment laden water shall be discharged into onsite, relatively level, vegetated areas (BMP C240 paragraph 5, page 4-102). In some cases, sediment discharge in concentrated runoff can be controlled using permanent stormwater B?VfPs (e.g,, infiltration swales, ponds, trenches). Sediment loads can limit the effectiveness of some permanent stormwater BMPs, such as those used for infiltration or l biofiltration; however, those BMPs designed to remove solids by settling (wet ponds or detention 1 ponds) can be used during the constnEetion phase. When permanent stointwater BMPs will be used to control sediment discharge during construction, the structure will be protected from excessive sedimentation with adequate erosion and sediment control BMPs. Any accumulated - sediment shall be removed after construction is complete and the pennnnnt storni�vater BMP 13 Stormwater Pollution Prevention Plan In general, cut and fill slopes will be stabilized as soon as possible and soil stockpiles will be temporarily covered with plastic sheeting. All stockpiled soils shall be stabilized from erosion; protected with sediment trapping measures, and where possible, be located away from storm drain inlets, waterways, and drainage channels. 3,1.6 Element #6 — Protect Slopes All cut and fill slopes will be. designed, constructed, and protected in a manner than raininaizes erosion. The following specific BMPs will be used to protect slopes for this project: Temporary and Permanent Seeding (BMP C120) i Interceptor Dike and Swale (BMP C200) • Check Dams (BMP C207) The, T.E.S.C. Plan Sheet C2,01 shows the locations of temporary seeding and mulching. In addition, all disturl)ed slopes shall lie seeded and mulched immediately following final grading. Plan Shect- C2.01 also shows the locations of temporary interceptor ditches and rock check clams. These shall be installed prior to beginning mass grading operations. Alternate slope protection BNI-Ps are: included in Appendix C'. as it quick reference tool for the onsite Haspector in the event the BMP(s) listed above are deetrred rneltective or inappropriate during construction to satisfy the requirements set forth in the General NPDES Permit (Appendix D). To avoid potential erosion and sediment control issues that may cause a violation(s) of the NPDES Construction Storrnwater permit (as provided in Appendix D), the Certified .Erosion and Sediment Control Lead will promptly initiate the implementation of one or more of the alternative .BMPs listed in Appendix C after the first sign that existing BMPs are ineffective or failing. 3.1.7 E+'leanest #7 — Protect Drain brlets All Storm drain inlets and culverts made operable during construction shall be protected to prevent unfiltered or untreated water from entering the drainage conveyance systern. however, the first priority is to keep all access roads clean of sediment and keep street wash water separate from entering storrn drains until treatment can be provided. Storm Drain Inlet Protection (BMP C220) will be impki-nented for all drainage inlets and culverts that could potentially be impacted by sediment -laden runoff on and near the project site. The following; inlet protection measures will be applied on this project_ 15 I Stormwater Pollution Prevention Plan well organized, and free of debris. if required, BMPs to be implemented to control specific sources of pollutants are discussed below. Vehicles, construction equipment, and/or petroleum product storage/dispensing: ■ All vehicles, equipment, and petroleum product storage/dispensing areas will be inspected regularly to detect any leaks or spills_, and to identify i-iaintenance needs to prevent leaks or spills. N On -site fueling tanks and petroleum product storage containers shill include secondary containment. a Spill prevention treasures, such as drip pans, will be used when conducting maiiitewmce and repair of vehicles or equipment. ■ In order to perform emergency repairs on site, temporary plastic will. be placed beileath cuid, if raining, over the vehicle. M Contaminated surfaces shall be cleaned immediately following any discharge or spill incident. Chciuical storage; :1ny chemicals Stored in t11e curtstrUCtian areas Will conform to the appropriate source control BMPs listed iu Volume IV of the l=cology slonnwater manual. In Western WA, all chetnic als shall huvc cover, containment, and protection provided on site, per 13MP Cl 53 for N-laterial Delivery, Storage and Containment in SWMI•fiWV4' 2005 ■ Application of agricultural eheaxucals, including, Fertilizers and pesticides, shall be conducted in a manner and at application rates that will not result in loss of cbecnical to storinwater runoff Manufacturers' recommendations for application procedures and rates shall be followed. IDemolition: J Dust released from demolished sidewalks, -buildings, or structures will be controlled rising Dust Control measures (B.NIP C140). * Storm drain inlets vulnerable to storinwater discharge carrying dust, soil, or debris will be protected using Storm Drain Inlet :Protection (BMP C220 as described above for Element 7). Process water and slurry resulting front sawcutting and surfacing operations will be prevented from entering the waters of the State by 17 Stormwater Pollution Prevention Plan 3.1.12 Element #12 —Manage the Project Erosion and sediment control BMPs for this project have been designed based on the following principles: ■ Design the project to fit the existing topography, soils, and drainage patterns. Emphasize erasion control rather than sediment control. a Minimize the extent and duration of the area exposed. • Keep runoff velocities low. ■ Retain sediment on site. r Thoroughly monitor site and maintain all ESC measures. in Schedule major earthwork during the day season, In addition, project management will incorporates the key components listed below: As this project site is located west of the Cascade.Mountain Crest, the project will be .managed according to the following key project coniponents. Phasing of Construction The construction project is being phased to the extent practicable in order to prevent soil erosion, and, to the snaxirnum extent possible, the transport of sediment from: the site during construction. Revegetation of exposed areas and maintenance of that vegetation shall be an integral part of the clearing activities during each phase of construction, per the Scheduling BMP (C 162). Seasonal Work .Limitations From October 1 through April 30, clearing, grading, and other soil disturbing activities shall only be permitted if shown to the satisfaction of the local permitting authority that silt -laded runoff will be prevented from leaving the site through a combination of the following: ❑ Site conditions including existing vegetative coverage, slope, soil type, and proximity to receiving waters; and. 19 _ I Stormwater Pollution Prevention Plan ■ Whenever inspection anchor monitoring reveals that the BMPs identified in this SWPPP are inadequate, due to the actual discharge of or potential to discharge a significant arnount of any pollutant, appropriate BMPs or design changes shall be implemented as soon as possible. Maintaining an Updated Construction SWPPP ■ This SWPPP shall be retained on -site or within reasonable access to the site. �1 a The SWPPP shall be modified whenever there is a change in the design, construction, operation, or maintenance at the construction site that has, or could have, a significant effect on the discharge of pollutants to waters of the state. - 1 ■ The SWPPP shall be modified if, during inspections or investigations conducted by the owner/operator, or the applicable local or state regulatory authority, it is dctermincd that the SWPPP is ineff'ectiie in _ eliminating or significantly niiiiimiz4ig pollutants in stormwater J tliscliarges from the site. The SWPPP shall be inodil=ied as necessary to include additional or uiodified,BlvlPs designed to correct problems l identihed, lZevisions to the SWPPP shall be completed within seven (7) days following the: inspecti0ii, _ 3.2 Site Specific SNIPS Site specific BMPs are shown on the TESL Plan Sheets and Details in Appendix A. These site specific plan sheets will be updated annually. 3.3 Additional Advanced BMPs ` For BMP 250 written pre -approval through Ecology is required (see S' MMWW 20,05). J 2t J Stormwater Pollution Prevention Plan 4,0 Construction Phasing and BMP Implementation The BMP implementation schedule will be driven by the construction schedule.. The following provides a sequential list of the proposed constniction schedule milestones and the corresponding BMP implerrientation schedule. The list contains key -milestones such as wet season construction. The BMP implementation schedule listed below .is keyed to proposed phases of the construction project, and reflects differences in BMP installations anti inspections that relate to wet season construction. The project site is located west of the Cascade Mountain Crest. As such, the dry season is considered to be from May 1 to September 30 and the wet season is considered to be from October I to April 30. ■ Estimate of Construction. Start Date: 0.9/01/08 • Estimate of Construction Finish Date: 09/08/09 ■ Mobilize Equipment on Site: 09/01/08 • Mobilize and Store all ESC and Soil Stabilization Products: tl9/01/08 ■ Install FSC Measures: 09/02/08 Install Stabilized Construction Entrances: 09/02/08 + Construct Temporary Sediment Pond: 09/03/08 Construct Temporary Interceptor Ditches and Rock C'.lieck Danis: 09/03/08 • Clearing and Grubbing: 09/15/ 08 • Grading: 0.9/15/08 • Install Storm Drainage Improvements and Detention, Pre - Treatment, and Water Quality Facilities (Leave out Cartridges): 09/15/08 • Wet Season Starts: 10101/08 • Install Temporary Storm Drainage System: 10/06/08 • Install Water and Sewer Utilities: 10/15/08 • Construct Fire- Access: 11/05/08 Install/Prepare Site for Franchise (Dry) Utilities: 11/19/08 • Excavate for Building Foundations: 11/19/08 ■ Construct New School Buildings: 12/22/08 • Dry Season Starts. 05/01/09 • Demo Existing School Building: 06/22/09 • Construct Parking and Drive Aisles: 07/06/09 • install Landscaping; 08/24/09 ■ Install Cartridges: 09/07/0.9 23 1 _.l 5tormwater Pollution Prevention Plan f 5.0 Pollution Prevention Team 5.1 Roles and Responsibilities ! The pollution prevention tearer consists of personnel responsible for implementation of the ! Mx M, including the fol lowing: i j ■ Certified Erosion and Sediment Control Lead (CESCL) — primary } contractor contact, responsible for site inspections (BMPs, visual monitoring, sampling, etc.); to be called upon in case of failure of any ' ESC measures. ■ Resident Engineer -- For projects will, engineered structures only 1 (sediment ponds/traps, said filters, etc.): site representative for the owner that is the prof ect`s supervising engineer responsible- for inspections and issuing instructions and drawings to the contractor's site supervisor or 1 representative ■ Emergency Ecology Contact— individual to be contacted at Ecology in case of emergency. 1 Emergency Owner Contact - individual that i.5 the site owner or - representative of the site Owner to he contacted in the case of are emergency. 1 Non -Emergency Ecology Contact — Mdiuidual at Ecology that call be contacted if required. " Monitoring person„ zel — personnel responsible for conducting water duality monitoring; for i„ost sites this person is also the Certified Erosion and Sediment Control Lead. 25 N Stormwater Pollution Prevention Plan 6.0 Site Inspections and Monitoring Monitoring includes visual inspection, monitoring for water duality parameters of concerti, and documentation of the inspection and monitoring findings in a site log book. A site log book will be maintained for all on -site construction activities and wil.l include: A record of the inlphanentation of the SWP'PP and other periritt requirements, R Site inspections; and_, Stormwater quality monitoring. For convenience, the inspection -form and water quality monitoring forms included in this SWPPP include the required information for the site log book. This SWPPP may function as the site logbook if desired, or the forms -may be separated and included .in a separate site log book. However, if separated, the site log 1),00k but rnust -be rnaintai-ned on -situ or within reasonable access to the site and be made available upon rCCjUest to Ecology or the local jurisdiction. 6.1. Site Inspection All 1:31v11's will be impeded, maintained. and repaired as nceded to assure continued perfoi-rnanc.e. of their intended function. The inspector will be a Certified Erosion and Secdinient Control Lead (CESCL) :per HIvIP C160The name and contact information 1c)r the CESCL is provided in Section 5 of this SAMPPP, Site inspection will occur in all areas disturbed by construction activities and at all Stormwater discharge points. Stormwater will be examined for the presence of suspended sediment, turbidity, discoloration, and oily sbeen. The site inspector will. evaluate and document the effectiveness of the installed BTMPs and cletermine if it is necessary to repair- or replace arty of the BMPs to improve the duality Of storrrAwater discharges. All maintenance and repairs will be documented in the site log book or forn-rs provided in this document. All new BMPs or design changes will be documented in the S WPPP as soon as possible. 6.1.1 Site Inspection Frequency Site inspectio s will be conducted at least once a week and within 24 Hours following any rainfall event which causes a discharge of stormwater from the site. For sites with temporary stabilization measures, the site inspection frequency can be reduced to once every month, 27 - , Storm►water Pollution Prevention Plan 2. Continue daily sampling until the turbidity is less than 25 NTU (or transparency is greater than 32 cm). 3. Initiate additional treatment BMPs such as off -site treatment, infiltration, filtration and chemical treatment within 24 hours of the first 250 NTU exceedance. 4. Emplenient additional treatment BMPs as soon as possible, but within 7 days of the first 250 NTU exceedance. S. Describe inspection results and remedial actions taken in the site log book 1 and in monthly discharge monitoring reports as described in Section 7.0 of 1 this SIAI. l'F. 6.2.2 pH Sampling 5tonnrwater runoft-Nvill be monitored for pH starting on the first day of any activity that includes more than 40 yards of poured or recycled concrete, or after- the application of "Engneered Soils" such as, Portland cement treated base, cement kiln dust, or fly ash. This does not include fertilizers. For concrete work, pH monitoring will start the first day concrete is poured and continue until 3 weeks afer the last pour. For engineered soils, the pH monitoring period begins when engineered soils are :first exposed to precipitation and continue lind I the area is fully stabilized. _ 1-Stortirwater samples will be collected daily from all points of discharge from the site and measured for PH usyng a calibrated pH meter, pll test kit, or wide range pi -I indicator paper, if the nicasured pH is. 8.5 or greater, the following steps will be conducted: 1. prevent the High pl-f water from entering storm drains or surface water. _ 2. Adjust or neutralize the high PH water if necessary using appropriate technology such as CO2 sparging (liquid or dry ice). ! 3. Contact Ecology if chemical treatment other than GOz sparging is planned. 29 Stormwater Pollution Prevention Plan 7.0 Deporting and. Recordkeeping 7.1 Recordkeeping 7.1.1 Site Log Book A site log book will be maintained for all on -site construction activities and will include: A record of the implementation of the SWPPP and other pernut requirements; " Site inspections, and, a St.ormwater quality monitoring, For convenience, the inspection form and water quality monitoring fon-as included in this SWPPP include the required information for the site log book. The site log boot( will be separate from the SWPPP because of the duration of the project and the monitoring requirements: 7.1.2 Records Retentio n Records ofall monitoring ufonnatioii (site log book, inspection reports/checklists, etc.); this Stortriwater PollLTtion Prevention Plan, and any other documentation of compliance with penilit requirements will be retained during, the life of the construeiion project surd for a rninimurn of three years following the termination of permit coverage in accordance with permit condition S5:G. 7J.3 Access to Plans and Records The SWPPP, General Pcrinit, Notice of Authorization letter, and Site Log Book, will be retained can site or within reasonable access to the site and will be made immediately available, upon request to Ecology or the local jurisdiction. A copy of this SWPPP will be provided to Ecology within 14 days of receipt of a written .request for the SWPPP from Ecology. Any other hiform4on requested by Ecology will be submitted within a reasonable time. A copy of the SWPPP or access to the SWPPP will be provided to the public when requested in writing 111 accordance with permit condition 85,G. 31 _., Siormwater Pol[uiion Revention Plan In accordance with permit condition S4.F.6.b, the Ecology regional office will he notified if chemical treatment other than CO2 sparging is planned for adjustment of high pH water (see Section 5.0 of this SWPP for contact inform- ation): In accordance with permit condition S2.A, a complete application farm will be submitted to Ecology and the appropriate local jurisdiction (if applicable) to be covered by the General Permit_ 33 5tormwater Potlotion Prevention Plan Appendix B — Construction BM. Ps Preserving Natural Vegetation (BMP C101) I High Visibility Plastic or Metal Fence (BMP C103) " T I Stabilized Construction Entrance (BMP C105) W13eel Wash (BMP C106) 1 TemporatySediment Pond '(BMP C241) Silt Fence (BMP C233) Storm Drain Tnlet.Protection (BMP C220) Temporary and Permanent Seeding (BMP C 120) j Mulching: (BMP C12I ) Interceptor Dike and Swale (BMP C200) 1 Check Danis (BIAP C207) Outlet Prote.ctioti (B1v1P C209) 35 system protects a tree from a raised grade. The the systern should be laid out on the original grade leading froze a dry well around the tree trunk. The system should then be covered with small stones to allow air to circulate over the root area. Lowering the natural ground level can seriously damage trees and shrubs. The highest percentage of the plant roots are in the upper 12 inches of the soil and outs of only 2-3 inches can cause serious injury. To protect the roots it may be necessary to terrace the immediate area around the plants to be saved. If roots are exposed, construction of retaining walls .may be needed to keep the soil in place. Plants can also be preserved by leaving them on an undisturbed, gently sloping mound_ To increase the chances for survival, it is best to limit grade changes and other soil disturbances to areas outside the dripline of the plant. Excavations - Protect trees and other plants when excavating for drainfields, power., water, and sewer lines. Where possible, the trenches. should be routed around trees and large shrubs. When this is not possible; it is best to tunnel under them. This can be done with hand tools or with power augers. If it is not possible to route the trench around plants to be saved, then the following should be observed: Cut as few roots as possible. Whcrr you have to cut, ccrt clean. Paint cut root ends with a wood dressing like asphalt base paint.. BackfilI thee trench as soon as possible_ Tunnel beneath root systems -as close to the ce>>ter of the. rnain trnnlc to preserve most of the important feeder roots. Some problems that can be encoun.[erect with a &w specific trees fre: • Maple, Dogwood, Red alder, Western, herntock, Western red cedar, and Douglas. fir do not readily adjust to changes in environment and special care should be taken to protect these trees. • The windthrow hazard of Pacific silver fir and madronna is high, while that of 'Western hen -Jock is moderate. The danger of windthrow increases -where dense stands have been thinned. Other species (unless they are on shallow, wet soils less than 20 inches deep) have a lour windthrow hazard, • Cottonwoods, maples, and willows have water -seeking roots. These can cause trouble in sewer lines and infiltration fields. On the other hand, they thrive in high moisture conditions that other trees would not. • Thinning operations in pure or mixed stands of Grand fir, Pacific silver fir, Noble fir, Sitka spruce, Western red cedar, Western hemlock, February 2005 Volume 11— Construction Stormwater Pollution Prevention 4-3 BMP C103: High Visibility Plastic or Metal Fence Purpose Fencing is intended to: (1) restrict clearing to approved limits, (2) prevent disturbance of sensitive areas, their buffers, and other areas required to be left undisturbed; (3) limn construction traffic to designated construction entrances or roads; and, (4) protect areas where marking with survey tape may not provide adequate protection. Conditions of Use To establish clearing lunits, plastic or metall fence may be used: At the boundary of sensitive areas, their buffers, and other areas required to be left uncleared. As necessary to control vehicle access to and on the site. Design and • High visibility plastic fence shall be composed of a high -density Installation polyethylene ntaterial and shall be at least four feet in height. Posts Specifications for the fencing shall be steel or wood and placed every 6 feet on center (maximum) or as needed to ensure rigidity. The fencing shall be fastened to the post every six inches with a polyethylene tie. On long continuous lengths of fencing, a tension wire or rope shall be used as a top stringer to prevent sagging between posts. The fence color Aall be high visibility orange. The fence tensile strength shall be 360 lbs,/ft. using the ASTM D4595 testing method. • Metal fences shall be designed and installed according to the. manufacturer's specifications. Metal fences shall be at least 3 feet high and must be highly visible. • Fences shall not be wired or stapted to trees. Maintenance • If the fence has been dammed or visibility reduced, it shall be Standards repaired or replaced irnmedia>tely and visibility restored. q_g Volume 11— Construction Stormwater Pollution Prevention February 2005 Whenever possible, the entrance shall be constructed on a firm, compacted subgrade. This can substantially increase the effectiveness of the pad and reduce the need for maintenance. Maintenance . Quarry spalls (or hog fuel) skull be added if the pad is no longer in Standards accordance with the specifications. • If the entrance is not preventing sediment from being tracked onto pavement, then alternative measures to keep the streets free of sediment shall be used. This may include street sweeping, an increase in the dimensions of the entrance, or the installation of a wheel wash.. • Any sediment that is tracked onto pavement shall be removed by shoveling or street sweeping. The sediment collected by sweeping shall be removed or stabilized on site. The pavement shall not be cleaned by washing down the street, except when sweeping is ineffective and there is a threat to public safety. if it is necessary to wash the streets, the construction of a small sump shall be considered. The sediment would then be washed into the sump where it can be controlled. At Any quarry spalls that are loosened from ttie pad, which end up on the roadway shall be removed immediately. • if vehicles are entering or e,.nting the site at points other than the construction entrance(s), fencing (see 131v1Ps C103 and C104) shall be installed to control traffic. UJ oii project cornpletion and site stabilization, all construction accesses intended as permanent access for maintenance shall be t)ermanently stabilized. 'POO � I ki%%M ddWw2W [111NIrr N dMl'8 h a �a4dside ditch pres¢n! V-8" quarry spans �eoleYtiln I Z' Alin. thic knrc - Mile -By s11911 n5e_L Ilse raglArzman's ur flee pPmming ageISGY if is reeommenclO trw the Wrl nna be Gfnwned so thsl r4r4# dralm o)t Ike pad Pr Oda fWl width of MgreWagrass area Figoro 4,2 — Stabilized Construction Entrance February 2005 Volume !1- Construction Stormwater Pollution Prevention 4-9 Figure 4.3 Wheel Wash Bates: 1. Asphalt construction entrance 6 in. asphalt treated base (ATB). 2. 3-inch trash pump with floats on the suction hose. 3. Midpolnt spray nozzles. it needed. 4, 6-inch sewer pipe with butterfly valves. Bottom one is a drain. Locate top pipe's invert 1 foot. above bottom of wheel wash. 5. 8 foot x 8 foot sump with 5 feet of catch. Build so can be cleaned with trackhoe. 6_ Asphalt curb on the low road side to direct water back to pond. 7. 6-inch sleeve under road. 8. Ball valves. 9. 15 foot. ATB apron to protect ground from splashing water_ February 2005 Volume 11— Construction Stormwater Pollution Prevention 4-11 • The seedbed should be firm and rough. All soil should be roughened no matter what the slope. If compaction is required for engineering purposes, slopes must be track walked before seeding. Backblading or smoothing of slopes greater than 4:1. is not allowed if they are to be seeded. New and more effective restoration -based landscape practices rely on deeper incorporation than that provided by a simple single -pass rototilling treatment. Wherever practical the subgrade should be initially ripped to improve long-term permeability, infiltration, and water inflow qualities. At a minimum, permanent areas shall use soil. amendments to achieve organic matter and permeability performance defined in engineered soil/landscape systems. For systems that are deeper than 8 inches the rototilling process should be done in multiple lifts, or the prepared soil systorh shall be prepared properly and then. placed to achieve the specified depth. • Organic matter is the most appropriate form of `fertilizer" because it provides nutrients (including nitrogen, phosphorus, and potassium) in the least water-soluble form, A natural systern typically releases 2-10 percent of its nutrients annually. Chemical fertilizers have since been formulated to simulate what organic matter does naturally. In general, 10-4-6 N-P-K (rri.trogen-phosphorrts-potassiumn) fertilizer can be used at a rate of 90 pounds per acre. Slow -release fertilizers should always be used because they are more efficient and have fewer environmental impacts. It is recommended that areas being seeded for final landscaping conduct soil tests to determine the exact type and quanrity of fertilizes -needed. This will prevent the over -application of fertilizer. herrtilizer should riot be added to the lIV(IXomulcYr machiDc and agitated more than 20 mirmtes before it is to be used. If agitated too much, the slow -release coating is destroyed. There are numerous products available on the market -that take the place of chemical fertilizers. These include several with seaweed extracts that are beneficial to soil microbes and organisms. If .100 percent cottonseed meal is used as the mulch in hydroseed, chemical fertilizermay not be necessary. Cottonseed meal is a good source of long-term, slow -release; available nitrogen. Hydroseed applications shall include a minimum of 1,500 pounds per acre of mulch with 3 percent tackif er. Mulch may be made up of 100 percent: cottonseed meal.; fibers made of wood, recycled cellulose, hentp, and kenaf, compost; or blends of these. Tackifer shall be plant - based, such as guar or alpha plantago, or chemical -based such as polyacrylainide or polymers. Any mulch or tackifier product used shall be installed per manufacturer's instructions. Generally, mulches corne in 40-50 pound bags. Seed and fertilizer- are added at time of application. 4-14 Volume 11 — Construction Stormwater Pollution Prevention February 2005 This technique works with standard hydromulch (1,500 pounds per acre minimum) and BFMIMBFMs (3,000 pounds per acre minimum). Areas to be permanently landscaped shall provide a healthy topsoil that reduces the need for fertilizers, improves overall topsoil quality, provides for better vegetal health and vitality, improves hydrologic characteristics, and reduces the need for irrigation. This can be accomplished in a number of ways. -1 Recent research has shown that the best method to improve till soils is f to amend these soils with compost. The optimum mixture is approximately two parts soil to one part compost. This equates to 4 inches of compost mixed to a depth of 12 inches in till soils. Increasing the concentration of compost beyond this level can have negative effects on vegetal health, while decreasing the concentrations can ' reduce the benefits of amended soils. Please note: The compost should meet specifications for Grade A duality compost in Ecology Publication 94-038. Other soils, such as gravel or cobble outwash soils, ma_v require ,differe-at approaches. Organics and lines easily migrate Llirough the loose structure of these soils. Therefore, the importation of at least 5 inches of quality topsoil, underlain by some type of filter fabric to prevent the migration of Fines, niay be more appropriate for these soils. 1 Areas that already have good topsoil, such as undisturbed areas, do not require Soil an1Cndillents. • .'u-cas that will be seeded only and not landscaped may need compost or meal -based mulch included in the hydroseed in order to establish vegetation. Native topsoil should be re -installer] on the disturbed soil surface before application. Seed that is installed as a temporary measure may be installed by hand if it will be covered by straw, mulch, or topsoil. Seed that is installed ^4 as a permanent measure may be installed by hand on small areas (usually less than l acre) that will be covered with mulch, topsoil, or erosion blankets. The seed mixes listed below include recon mended mixes for both temporary and permanent seeding. These mixes, with the exception of the wetland mix, shall be applied at a rate of 120 pounds per acre. This rate can be reduced if soil amendments or slow - release fertilizers are used. Local suppliers or the local consen ation district should be consulted for their recommendations because the appropriate mix depends on a variety of factors, including location, 1 exposure, soil type, slope, and expected foot traffic. Alternative seed mixes approved by the local authority may be used. 1 4-16 Volume 1! — Construction Stormwater Pollution Prevention February 2006 The seed mix shown in Table 4.5 .is a recommended low -growing, relatively non-invasive seed mix appropriate for very wet areas that are not regulated wetlands. Other mixes may be appropriate, depending on the soil type and hydrology of the area. recent research suggests that bentgrass (agrostis sp.) should be emphasized in wet -area seed mixes. Apply this mixture at a rate of 60 pounds per acre. Table 4.5 Wet Area Seed Mix* % Wei hr % Purit %Germivaflvu Tall or meadow fescue 60-70 98 90 Festuca arundinacea or Festuca elatior SeasidelCreepiugbentgrass 10-15 98 85 d rostts lustris _ Meadow foxtail 10-15 90 80 AleppoGurus ratensis Alsike clover 1-6 98 90 Tri oliurn h hridum Redtop bentgrass 1-6 92 85 Agrostis alba * Uodiijied Briar[;reei, Inc, Hj�dmsecding Guide IVetlancis Seed h1-71C The meadow seed mix in Table 4.6 is recornrnended for areas that will be maintained infrequently or not at all and where colonization by native plants is desirable_ Ukely applications include rural road and utility right - of way. Seeding should talcs place in September or eery early October in order to obtain adequate establishment prior to the winter months. 'Ilse appropriateness of clever in the mix may need to be considered, as this Carl be a fairly invasive species. If tile soil is ainendcd_ the addition ol.'clover may not be necessary. Table 4.6 Meadow Seed Mix % Weight % Purity % Germination Redtop or Oregon bentgrass 20 92 85 mstfs alba or .4 rostis oregonensis Red fescue 70 98 90 Festuca rubra White dutch clover 10 98 90 Tri olfu►n repens Maintenance r Any seeded areas that fail to establish at least 80 percent cover (100 Standards percent cover for areas that receive sheet or- concentrated flows) shall be reseeded. If reseeding is ineffective, an alternate method, such as sodding, mulching; or nets/blankets, shall be used. If winter weather prevents adequate grass growth, this tame limit may be relaxed at the discretion of the local authority when sensitive areas would otherwise be protected. 4-18 Volume 11— Construction Stormwater Pollution Prevention February 2005 BMP C121: Mulching ,Purpose The purpose of mulching soils is to provide immediate temporary protection from erosion. Mulch also enhances plant establishment by conserving moisture, holding fertilizer, seed, and topsail in place, and moderating soil temperat€tres_ There is an enormous variety of mulches that can be used. Only the most common types are discussed in this section. Conditions of Use As a temporary cover measure, mulch should be used: • On disturbed areas that require cover measures for less than 30 days. • As a cover for seed during the wet season and during the hot summer months. • During the wet season on slopes steeper than 3H:1 V with more than 10 feet of vertical relief: • Mulch may be applied at any time of the year and must be refreshed periodically. Design and For mulch 'Materials, application rates, and specifications, see Table 4.7. Instaitation Note: Thicknesses may be inereased.for disturbed areas in or near Specifications sensitive areas or other areas highly susceptible to erosion. Mulch used within the ordinary high-water maa-k of sknrface waters should be selected to minimize potential flotation of organic matter. C'orriposted organic materials have higher specific gravities (densities) than straw, wood, or chippCd material. Maintenance • The thickness of the cover must be maintained. Standards . Any areas that experience erosion shall be remulcltecl and/or protected with a net or blanket. If the erosion problem is drainage related, then the problem shall be fixed and the eroded area remulched. 4_20 Volume N — Construction Sformwater Pollution Prevention February 2005 4.2 Runoff Conveyance and Treatment BMPs BMP C200: Interceptor Dike and Swale Purpose Provide a ridge of compacted soil, or a ridge with an upslope swale, at the top or base of a disturbed slope or along the perimeter of a disturbed construction area to convey stormwater. Use the dike and/or swale to intercept the runoff from unprotected areas and direct it to areas where erosion can be controlled. This can prevent storm runoff from entering the work area or sediment -laden runoff from leaving the construction site_ Conditions of Use Where the runoff from an exposed site or disturbed slope must be conveyed to an erosion control facility which can safely convey the stormwater. ■ Locate upslope of a construction site to prevent runoff from entering disturbed area. When placed horizontally across a disturbed slope, it reduces the amount and velocity of runoff flowing down the slope. Locate downslope to collect runoff from a disturbed area and direct it to a sediment basin. Design and • Dike and/or Swale and channel must be stabilized with temporary or InstaMation permanent vegetation or other channel protection during construction. ,4pecrfic«tio►s.r Channel _requires a positive grade for drainage: steeper grades require channel protection and check dams. • Review construction for areas where overtopping may occur. • Can be used at top of new fill before vegetation is established. • Nla.y be used as a permanent divcrs.io.n channel to cai-ry the runoff. • Sub -basin tributary area should be one acre or less. • Design capacity for the peak flow from a 10-year, 24-hazer storm, assuming a Type 1 A rainfall distribution, for temporauy facilities. Alternatively, use 1.6 times the 10-yeas, 1-hour flow indicated by an approved continuous ninoff model. For facilities that will also serve on a permanent basis, consult the local govenitnent's drainage requirements. Interceptor dikes shall meet the following cntena: Top Width 2 feet minimum. Height 1.5 feet minimum on berm. Side Slope 2:1 or flatter. Grade Depends on topography, howeveu, dike system minimiun is 0.5%, maximuun is 1°!0. Compaction Minimum of 90 percent ASTM D698 standard proctor. February 2005 Volume it — Construction Stormwater Pollution Prevention 4-57 BMP C207: Check Dams Purpose Construction of small dams across a swale or ditch reduces the velocity of concentrated flow and dissipates energy at the check darn. Conditions of Use Where temporary channels or permanent channels are not yet vegetated, channel lining is .infeasible, and velocity checks are required. • Check dams may not be placed in streams'unless approved by the State Department of Fish and Wildlife. Check dams may not be placed in wetlands without approval from a permitting agency. • Check dams shall not be placed belo-w the expected backwater from any salmonid bearing water between October 1 and May 31 to ensure that there is no loss of high flow refuge habitat for overwintering juvenile salmonids and emergent salmonid fry. Design and Whatever material is used, the dam should form a triangle when viewed Astallation from the side. This prevents utidercutting as water flows over the €ace of Specifications the dam rather than falling directly onto the ditch bottom. Check dams in association with sumps work more effectively at slowing flow and retaining sediment than just a check dam alone. .A deep sump should be- provided immediately upstream of the check dam. • In some cases, if carefully located and designed, check dams can remain as permanent installations with very minor regrading. They may be left as either spillways, in which case accumulated sediment would be graded and seeded, or as check darns to prevcnit further se-dirricnt from leaviiib the site. • Check dams can be constructed of either rock m pea -gravel filled bags. 1 Numerous ne'x products are also available for this purpose. They tend to be re -usable, quick and easy to install, effective, and cost efficient. • Check dams should be placed perpendicular to the flow of water. • The maximum spacing between the dams shall be such that the toe of the upstream dam is at the same elevation as the top of the downstreafn darn. • Keep the maximum height at 2 feet at the center of the dam_ • Keep the center of the check dam at least 12 inches lower than the outer edges at natural ground elevation. • Keep the side slopes of the check dam at 2:1 or flatter. • Key the stone into the ditch banks and extend it beyond the abutments a minimum. of 18 inches to avoid washouts from overflow around the dam, JFebruary 2005 Volume 11 — Construction Stormwater Pollution Prevention 4-75 View Looking Upstream NOTE: Key stone into channel banks and extend it beyond the abutments a minimum of i 6" (0.,5m) to prevent flow around dam. Section A - A FLoW A18" (0,5m) — i 12" (150intn) A I rha� 0 Spacing Between Check Dams 'L' = the distance such'that points '.A' and 'B' are of equal elevation. ;c. I�QINT'A' fWM� Figure 4.13— Check Dams February 2005 Volume It — Construction Stormwater Pollution Prevention f 24" (0.6rrt) POINT �i3' •-, 4','{ NOT TO SCALE 4-77 high flows. Sank stabilization, bioengineering, and habitat features may be required for disturbed areas. See Volume V for more information on outfall system design. Maintenance , Inspect and repair asneeded- Standards• Add rack as needed to maintain the intended function. • Clean energy dissipater if sediment builds up. February 2005 Volume 11— Construction StortnWater Pollution Prevention 4481 Design and Excavated .Drop Inlet Protection - An excavated impoundment around the Installation storm drain. Sediment settles out of the stonnwater prior to entering the Specifications storm drain. • Depth 1-2 ft as measured from the crest ofthe inlet structure. • Side Slopes of excavation no steeper than 2:1. • Minimum volume of excavation 35 cubic yards. • Shape basin to fit site with longest dimension oriented toward the longest inflow area. • Install provisions for draining to prevent standing water problems. • Clear the area of all debris. • Grade the approach to the inlet uniformly. • Drill weep holes into the side of the inlet.. • Protect weep holes with screen wire and washed aggregate. Seal weep holes when removing structure and stabilizing area. • It may be necessary to build a temporary dike to the down slope side of the structure to prevent bypass flow. Block and Gravel Filter - A barrier formed around the storm drain inlet with standard concrete blocks and gravel. See Figure 4,14.. • Height 1 to 2 feet above inlet. • Recess the first row 2 itrches into the ground for stability. • Support subsequent caurses by placing a 2x4 thiougb the block opceing, • Do not use mortar. Lay some blocks In the bottom row on tlie.ir side for dewaiering the pool. • Place hardware cloth or comparable wire mesh with %z-in.chopenings over all block. openings. Place gravel just below the top of blocks on slopes of 2:1 or flatter. • An alternative design is a gravel donut. + Inlet slope of 3:1. • Outlet slope of 2:1. • 17foot hide level stone area between the structure and the inlet. • ,Inlet slope stones 3 inches in diameter or larger. • Outlet slope use gravel f2- to'/d-inch at a minimum thickness of 1-foot. February 2005 Volume li— Construction Stormwater Pollution Prevention 4-83 Catchbasin Filters - Inserts should be designed by the rnanufacturet• for use at construction sites. The limited sediment storage capacity increases the amount of inspection and maintenance required, which may be daily for heavy sediment loads. The maintenance requirements can be reduced by combining a catchbasin filter with another type of inlet protection. This type of inlet protection provides flow bypass without overflow and therefore may he a better method for inlets located along active rights -of - way. 5 cubic feet of storage. Dewatering provisions. High -flow bypass that will not clog under normal use at a construction site. The catchbasin filter is inserted in the catchbasin just below the grating. Curb Inlet Protection with Wooden Weir - Barrier formed around a curb inlet with a wooden frame and gravel. Wire mesh with %2-inch openings. • Extra strength filter cloth. 1 Construct a frame. 1 Attacb the wire and :filter fabric to the frame. • Pile coarse washed aggregate against wire/fabric. • Place weight on frarzre anchors. Block and Gravel Curb Inlet Protection — Barrier formed around all inlet with concrete blocks and gravel. See'Figure 4.14. • Wire mesh with!/2-inch openings_ Place two concrete blocks on their sides abutt�rlg the curb at either side of the inlet opening. These are spacer blocks_ Place a 2x4 stud through the outer holes of each spacer block to align the front blocks. • Place blocks on their sides across the front of the valet and abutting the spacer blocks. Place wire mesh over the outside vertical face. _ • Pile coarse aggregate against the wire to the top of the barrier. Crab and Gutter Sediment Barrier— Sandbag or rock (riprap and aggregate) 3 feet high and 3 feet wide in a horseshoe shape_ See Figure 4.16. • Construct a horseshoe scraped berm, faced with coarse aggregate if using riprap, 3 feet high and 3 feet wide, at least 2 feet from the inlet. • Construct a horseshoe shaped sedimentation trap on the outside of the berm sized to sediment trap standards for protecting a culvert inlet. February 2005 volume 11— Construction stormwater Pollution Prevention 4-65 Plan View Back of Sidewalk A Catch Basin W Wood Stud B ack of Curb — Concrete Block Curb Inlet GQ Q �� n4 - •�V• V 4 V a� ��Cp��. a �W!{i/��� Q�.Q 'Y'] spy, �<� , 6 p' A •¢ .. "• A. A. .� O q. Zi blare Screen Filter FaUrk; A Concrete Block Section A- A1 Df31n CUraV21 Drain Gravel (20mm) Ponding Height Concrete Block ovQ ��_ Curb Inlet f�\ r Wire Screen or % \% Filter Fabric 1 Catch Basin Wood Stud 1\/ (100x59 Timber Stud)r NOTES: 1 Use block and gravel type sediment barrier when curb inlet is located in gently sloping street segment, where water can pond and allow sediment to separate from runoff, 2. Barrier shall allow for overflow from severe stom7 event. 3_ Inspect barriers and remove sediment after each storm event. Sediment and gravel must be removed from the traveled way immediately. Figure 4.15 - Block and Gravel Curb Inlet Protection February 2005 Volume 11- Construction Stormwater Pollution Prevention 4-87 BMP C233: Slit Fence Purpose Use of a silt fence reduces the transport of coarse sediment from a construction site by providing a temporary physical barrier to sediment and reducing the mnoff velocities of overland flow. See Figure 4.19 for details on silt fence construction. Conditions of Use Silt fence may be used downslope of all disturbed areas. • Silt fence is not intended to treat concentrated flows, nor is it intended to treat substantial amounts of overland flow. Any concentrated flows must be conveyed through the drainage system to a sediment pond. - The only circumstance in which overland flow can be treated solely by a silt fence, rather than by a sediment pond, is when the area draining to the fence is one acre or less and flow rates are less than 0.5 cfs. • Silt fences should not be constructed in streams or used in V-shaped ditches. They are not an adequate method of silt control for anything deeper than sheet or overland flow. .Joints in filler Fabric shall be spliced at posts. Use staples, wire rings or equivalent to attach fabric to posts II ii 2"x2" by 14 Ga. wire or equivalent, if standard - strength labric used Filter fabric-- - i ��--8' rnaY— — �i � !'•. Minimum a"xl" trenci� BackfifV trench with native sot: I'ost spacing may be inoreased or 3/4"-1 S" washed gravol i ed to $ rf wire, 6acking s us 2"x2" wood posts, ster31 fence posts, or equivalent I i i Figure 4.1 V — Wit rence Design and • Drainage area of 1 acre or less or in combination with sediment basin XiWallaiion in a larger site. Specifications ■ Maximum slope steepness (normal (perpendicular) to fence line) 1.1. • Maximum sheet or overland flow path length to the fence of 100 feet, • No flows greater than 0.5 cfs. The geotextile used shall meet the following standards. All geotextile properties listed below are minimum average roll values (i.e., the test result for any sampled roll in a lot shall meet or exceed the values shown in Table 4.10): 4_94 Volume 11— Construction Stounwa€er Pollution Prevention February 2005 The geotextile shall be attached on the up -slope side of the posts and support system with staples, wire, or in accordance with the manufacturers recommendations. The geotextile shall be attached to the posts in a manner that reduces the potential for geotextile tearing at the staples, wire, or other connection device. Silt fence hack -up support for the geotextile in the form of a wire or plastic mesh is dependent on the properties of the geotextile selected for use. if wire or plastic back-up mesh is used, the rnesh shall be fastened securely to the up -slope of the posts with the geotextile being up -slope of the mesh back-up support. The geotextile at the bottom of the fence shall be buried in a trench to a mini:nautn depth of 4 inches below the ground surface. The trench shall be backfiiled and the soi 1 tamped in place over the buried portion of the geotextile, such that no flow can pass beneath the fence and scouring cm not occur. When wire or polymeric back-up support mesh is used, the wire or polymeric mesh shall extend into the trench a niinimlun of 3 inches. The fence posts shall be placed or driven a minimum of 18 inches. A minimum depth of 12 inches is allowed if topsoil or other soft subgrado soil is not present and a minimum depth of 18 inches cannot be reached.. Fence post depths shall be increased by 6 inches if the fence is located on slopes of 3:1 or steeper and the slope is perpendicular to the fence, if required post depths cannot be obtained, the posts shall be adequately secured by bracing or guying to prevent overturning of the fence due to sediment loading. Silt fcnr:es shall he located on contour- as inucli as possible, except at the ends of the fence, where the fence shall be turned uphill such that the silt fence captures the rnnoffwater and prevents water from flowing around the end of the fence. If the fence must cross contours, with the exception of the ends of the fence, gravel check darns placed perpendicular to the back of the fence shall be used to minimize concentrated flow and erosion along the back of tlae fence. The gravel check dams shall be approximately 1- foot deep at the back of the fence. It shall be continued perpendicular to the fence at the sane elevation until the top of the check darn intercepts the ground surface behind the fence. The gravel check dams shall consist of crushed surfacing base course, gravel backfill for walls, or shoulder ballast. The gravel check dams shall be located every 10 feet along the fence where the fence must cross contours. The slope of the fence lire where contours must be crossed shall not be steeper than 3:1. Wood, steel or equivalent posts shall be used. Wood pasts shall have manimutn dimensions of 2 inches by 2 inches by 3 feet minimum length, and shall be free of defects such as knots, splits, or gouges. 4-96 Volume 11 — Construction stormwater Pollution Prevention February 2005 Any damage shall be repaired immediately. Maintenance If concentrated flows are evident uphill of the fence, they must be Standards intercepted and conveyed to a sediment pond. It is important to check the uphill side of the fence for signs of the fence clogging and acting as a barrier to flow and then causing channelization of flows parallel to the fence. If this occurs, replace the fence or remove the trapped sediment. • Sediment deposits shall either be removed when the deposit reaches approximately one-third the height of the silt fence, or a second silt fence shall be installed. • If the filter fabric (geotextile) has deteriorated due to ultraviolet breakdown, it shall be replaced. Pondlhp h jhl POSTSPAGING; max 4' T m+ac on apart runs _..--.._..... .. ............... Tog of FaExfc v msim ■h Peeling areas " FIe1E JkTMCh TAM% W upFdrYh fkl0 Of post14 g' RANI--� arse. ar.+ *"h .11l..f Faq-T MPTR: •Ill ftW.7lna UF.rf+ r As much below around rAfh d.A.4 a mint' f ae14%41rle Ah....Around Oa F.aA. "r yR�t.f f f ❑4 rg—:n wt—hR WK Ica%canWell fgah cempeCHon da.Waa SL'wly.h. lg I g;Lt \ ++T►eerue+rfTARS: fr,•�i if, � f f �� J �� \� \ • Garha fabda al posts. E nnMad. a Ilurhn aces Uhsper pas. aG wNhln kcP a_f�8sy�41cak p6ddc rt aedl 6o dlag nnuy, P`� Y a n+Gertcrrr of 1'spun. * Havg arch tla an a pall i+ WO orW tlOM" Y No more than 24" of a W fabric use coma am (6ftW or w Lw+a• is aitowed abovil ground. Ron of silt fend. y.rr� Qppratiars Pax instagod else, camp ctkan Fa*iC SIR Fence �j Sl��rid 54 t 4 } 1iol�orv+flrbCdpafnt SAtlgW4de (76 asxn tt B rnrrl +,Idtlf) Ibmpleted brvaalddan Vlbratbg plow is nmt accigii ble because of raW>ntal Carhpactfon Figure 4.20 — Silt Fence Installation by Slicing Method 4_98 volume 11— Construction Stormwater Pollution Prevention February 2005 Determine the required surface area at the top of the riser pipe with the equation: V = 2 x Q710.00096 or 2080 square feet per efs of inflow See BW C240 for more information on the derivation of the surface area calculation. The basic geometry of the pond can now be determined using the following design criteria: • Required surface area SA (from Step 2 above) at top of riser. • Minimum 3.5=foot depth from top of riser to bottom of pond. • Maximum 3:1 interior side slopes and maximum 2:1 exterior slopes. The interior slopes can be increased to a maximum of 2:1 if fencing is provided at or above the maximum water surface. • One foot of freeboard between the top of the riser and the crest of the emergency spillway. • Flat bottom.. • Minimum 1-foot deep spillway. • Length -to -width ratio between 3:1 and 6:1. • Sizing of Discharge Ntechanisrns_ The outlet for the basin consists of a combination of principal and emergency spillways, bese outlets mustpass the peak runoff expected from the contributing drainage area for. a 100-year storm. If, due to site conditions and basin geornetry, a separate emergency spill -way is not feasible, the principal spillway must pass the entire. peak rtmoff expected fro17] the 100-year sturna. t-l.owever, an attempt to provide a separate emergency spillway should always be made. The runoff calculations ,should be based on the site conditions during construction. The flow through the dewatering orifice cannot be utilized when calculating the 100-year storni elevation because of its potential to become clogged; therefore, availablc spillway storage must begin at the principal spillway riser crest. The principal spillway designed by the procedures contained in this standard will result in some reduction in the peak rate of runoff. However, the riser outlet design will not adequately control the basin discharge to the predevelopment discharge limitations as stated in Minimum Requirement #7: Flow Control. However, if the basin for a permanent storm -water detention pond is used for a temporary sedimentation basin, the control structure for the permanent pond can be used to maintain predevelopment discharge Iimitations. The size of the basin,, the expected life of the construction prbject, the anticipated downstream effects and the anticipated weather conditions during construction, should be considered to determine the need of additional discharge control. See Figure 4.28 for riser inflow curves. 4-106 Volume 11 — Construction Stormwater Pollution Prevention February 2005 Figure 4.2.7 — Riser Inflow curves -108 Volume !l — Construction Stormwater Pollution Prevention February 2005 this provision are allowed as long as the divider is permeable, structurally sound, and designed to prevent erosion under or around the barrier. To aid in determining sediment depth, one -foot intervals shall be prominently marked on the riser. If an embankment of more than f feet is proposed, the pond must comply with the criteria contained in Volume .11T regarding dam 'safety for detention BMPs. The most common structural failure of sedimentation basins is caused by piping. Piping refers to two phenomena: (1) water seeping through fine-grained soil, eroding the soil grain by grain and forming pipes or tunnels; and, (2) water under pressure flowing upward through a. granular soil with a head of sufficient magnitude to cause soil grains to lose contact and capability for support. The most critical construction sequences to prevent piping will be: 1. Tight connections between riser and barrel and other pipe connections, 2_ Adequate anchoring of riser. 3. Proper soil compaction of the embankment and riser footing_ 4. Proper construction of anti -seep devices. Maintenance t Sediment shall be removed from the pond when it reaches 1—foot in Standards deptli- a Any damage: to the pond embankments or slopes shall be repaired.. 4.110 Volume 11— Construction Stormwater Pollution Prevention February 2005 Stormwater Pollution Prevention Plan ❑ Dust Control (BMP C 140) ❑ Small Project Construction Stormwater Pollution (BMP C180) ❑ Early application of gravel base on areas to be paved ❑ Materials on Hand (BNiP C150) ❑ Alternative BMP not included in the SWMM'1W (2005) Eternent #b - Protect Slopes Surface Roughening (BMP .C130) Q Gradient Terraces (BMP C131) Q Grass -Lined Channels (BMP C201) ❑ Channel Lining (BMP C202) Q Pipe Slope Drains (BMP C204) ❑ Subsurface Drains (BMP C205) ❑ Level Spreader (BMP C206) ❑ Triangular Silt Dike (Geotextile-Encased Check Dam; BMP C208) ❑ Straw Wattles (BIv1P C235) ❑ Materials on Hand (-BMP C 150) ❑ Alternative B.MP not included in the SVVMINI WW (2005) Element #7 — Protect Drain Inlets (Drop Inlet) ❑ Excavated Drop inlet Protection ❑ Block and Gravel Drop Inlet ProteCtio❑ ❑ Gravel and Wire Drop Inlet Protectioll 0 Alte niative. BMP not included in the SWMM WW (2005) Element #8 - Stabilize Channels mid Outlets - ❑ Grass -Lined Channels (BMP C201) ❑ Channel Lining (BMP C202) ❑ Level Spreader (I3MP C206) Q Check Darns (BMP C207) ❑ Triangular Silt Dike (Geotextile-Encased Check Dam -- BMP C208) ❑ Materials on Hand (BMP C150) ❑ Alternative BMP not included in the SWl1/IMWW (2005) 37 Stormwater Pollution Prevention Plan r ' _1 Appendix D -- General Permit _} 39 Stormwater Pollution Prevenfion Plan I remedial actions required to bring the site back into compliance, as well as a schedule of implementation, i. Name, title, and signature of person conducting the site inspection; and the following statement: "I certify under penalty of law that this report is true, accurate, and complete, to the best of my knowledge and belief'. When the site inspection indicates that the site is not in compliance with any terns and conditions of the NPD.ES permit, the Perinittee shall tape immediate action(s) to: stop, contain, and clean up the unauthorized discharges, or otherwise stop the noncompliance; correct the problem(s); implement appropriate Best Management Practices (BMPs), and/or conduct maintenance of existing BMPs; and achieve compliance with all applicable standards and permit conditions. In addition, if the noncompliance causes a threat to human health or the environment, the Permittee shall comply with the Noncompliance Notification requirements in Special Condition S5.17 of the permit. Ell Stormwater Pollution Provention Plan EIrmen13: Control]Imv Rattles BMP-: Y 8mp- Location Bm,p:, Aid Iy BM 11! Problem,'Corrective Action y N. I y N.., Nit, BIM P: L.Oclilif,qji Bmfl. Location Inspected Fqnctimnng Y IN y N Funchoallig Nip. L TIM N 43 ProbloiniGotro�;Iivt� ActICIII VOCOV, (�iiw Mtibri Action StorMwater Poltutibn Prevanfion Plan Eiletnew 7: Plrofevr &ain: Mkig Rmp: N- W.d -Y i OR& Location fjj�p y -I ratiOnT9 Location 7,1 Probfo mi /ConlectiveActioz) N INTP B-NI.P: Location 11-Isppuo� . V. - ,Lim.. —I A ." r AMAl'on L-'Ietlient 8: ,IVtabiliz,.,e Chwowls awl Outlets Prob leffl/Correctl vc M I I V 11 y B M I-: Ja.Inspected Func 101I.Ing. Actiou . .1 .-. . . . . - 4��.g, Y, b _. InspocUid JLosotion V N Y- —NOV B MP fco-rrefivo Ac tioti L 1 .45 i 7m+ye! Pollution evef!¢n Plan / - Ob.\ y .w- © prohl /§//yip ActIO vY �\| � - S� 6n hoc G± ]iKG± 2 lk:o9QR§@n a 47 Slormwater PollutionProventiort Plan J J J 'i J Appendix F — Engineering Calculations See the Panther Lake Elmentary School Technical Information Report for Ongineening calculations, 49 J Figure 7—Sediment Basin Areas 0-1c 50 Pb .hvd COMM 4hTR-"I AS fry �51 k Ta2iD11 E 3 )JM, THIS PLAN 115 MKTFFlUAL BUILDINGS, LOT 1 LAYOUTS AND WP'R4VEMOM SROWN ARE REPREE ITATNE OF THE TYPES OF KVELOPNENF TINT 6 PROP05 , BUT IN WM CASES, 7HEY WE NOT d KEN DMCNED OR ON TRUCTED. THE FINAL PLAN AIRY DFM FROM THIS ODNCEPFUAL PIRA. THE DE1'E3APSR RE.SF3hn THC MW To Iy1KE C w#= AS THE PLAN IS I'TNAIDIiD NO NPii O TEA 4 _ .tt:!i0asi �1' r2 $2`45'52' E '_53 :C LEGEND WEST SEDBAENT BASIN FOR COSTING TMIK D A WEST SEDIMENT WIN FOR PPOPOJ ED TANK EAST SEDIMENT BASIN FOR PROP09E.D PLAID a DA7AL H Y� W V 1 11 in V) It It 0- �+i I �x U to � Iyj Z d Ld :2 --7 W In �V w m For Review Only W � z Preliminary M Z W LIJ 86' a 50' i OO ■ HORIZONTAL SCALE IN FEET fannrpnrated I= III Tob $ WK lee 499 Klrklmn Imb[ajlaa W33 Pboar. 421) In-" Fa M BZ!-II'm lut r L• "WAtA=N Admnsirotian alfcec: 31047A.003.001.DS Fedmil Way 31405 - 18th Ave. S. "`' Fr:.ral Woy, WA 4800.] Project No- J,sAwt)GeSdoals Phone: (253)945 2600 FIGURE 7 CALL BEFORE YOU DIG I k5 X(M 61M Taus-f3T; Sl ' No, 1-SOD-424-5555 e w JW 0 m zv'= E sh.at 2 aT 3 Section Nine -, Section 9—Bond Quantity Worksheet, Facility Summaries and Declaration of Covenant Bond Quantity Worksheets A Bond Quantity Worksheet has not been included with this submittal. It will be prepared and submitted prior to the pre -construction meeting. Flow Control and Water Quality Facility Summary Sheet and Sketch Flow Control and dater Quality Facility Summary Sheets for each of the proposed facilities are included in Section. 3, Appendices A.2, A.3 and B.1. Declaration of Covenant Portions of this project. are located within public right-of-way or include publicly maintained drainage facilities. A Declaration of Covenant will be provided for all public drainage facilities. 1 Panther Lake Elementary Scbool TIR 29 o W k f;:iprojtex�l I I'J3l31147A Vtepf�rts\TIR�Ttyt.2iac Section Ten This page left intentionally blank for double -sided printing. 'Section I 0—Maintenance and Operations Manual The owner is responsible for maintaining the facility. Drainage facilities will be, maintained and operated in compliance with Ding County maiintenance standards, included in Appendix G.1. Stormfilter munteftante requirelnents. ate included in Appendix G.2 and G—J. anther Lake -Clement ry School TIR 30 otak XApt6jft\31 IQ0'IaIV17A%KcpcmMRVImt.&c Appendix G. I --- Maintenance Requirements for Flow Control, Conveyance, and WQ Facilities KING COUNTY, WASHINGTON, SURFACE WA'1ER DESIGN MANUAL APPENDIX A MAINTENANCE REQUIREMENTS FOR FLOW CONTROL, CONVEYANCE, AND WQ FACILITIES NO. 1— DETENTION PONDS Maintenance Defect or Problem Conditions When Maintenance Is Needed Remeson ts Expected t P Whened Is Component General Trash & Debris Any trash and debris which exceed 1 cubic foot Trash and debris cleared from site. per 1,000 square feet (this is about equal to the amount of trash it would take to fill up one standard size office garbage can). In general, there should be no visual evidence of dumping. Poisonous Vegetation Any poisonous or nuisance Vegetation which may a hazard to County personnel or the No danger of poisonous vegetation el or the personnel ee Countmight or Noxious Weeds constitute public. public Coordination with Seattle -King County Health Department Contaminants and Oil, gasoline, or other contaminants of one gallon or more, or any amount found that could: No contaminants present other than a surface film. (Coordination with Pollution 1) cause damage to plant, animal, or marine life; Seattle[King County Health 2) constitute a fire hazard: or 3) be flushed Department) downstream during rain storms. Unmowed Cover If facility is located in private residential area, is needed when grass exceeds 18 When mowing is needed, grasslground cover should be Grass/Ground mowing inches in height. In other areas, the general mowed to 2 inches in height, policy is to make the pond site match adjacent Mowing of selected higher use areas ground cover and terrain as Fong as there is no interference with the function of the facility. rather than the entire slope may be acceptable for some situations, Rodent Holes Any evidence of rodent holes if facility is acting Rodents destroyed and dam or berm repaired. (Coordination with as a dam or berm, or any evidence of water piping through dam or berm via rodent holes or SeattleXing County Health other causes. Department) Insects When insects such as wasps and hornets interfere with maintenance activities. Mosquito litsects destroyed or removed from site. Mosquito control: Swallow compialrrts accompanied by presence of high nesting boxes or approved larvicide mosquito larvae concentrations (aquatic phase). applied. Tree Growth Tree growth threatens integrity of berms acting or Trees do not hinder maintenance activities. Harvested trees should as dams, does not allow maintenance access, Interferes with maintenance activity (i.e.. siape be recycled into mulch or other mowing, sill removal, vectoring, or equipment beneficial uses (e.g., alders for movements). If trees are a threat to berm firewood). integrity or not interfering with access, leave trees alone. 1 /24/2005 20GS Surface Water Design Nhinual — Appendix A A -I APPENDIX A. MAINTENANCE REQUIR NIEN7'S FLOWN COTi'I'ROL, CONVEYANCE, AND WQ FACILI'flES NO. I - DETENTION PONDS Maintenance Defect or Problem Conditions When Maintenance is Needed Results Expected When Component, Maintenance Is Performed Side Slopes of Pond Erosion Eroded damage overt inches deep where cause Slopes should be stabilized by using of damage is still present or where there is appropriate erosion control potential for continued erosion. measure(s); e.g., rock reinforcement, planting of grass, Any erosion observed on a compacted berm compaction. embankment. If erosion is occurring on compacted berms a licensed civil engineer should be consulted to resolve source of erosion. Storage Area Sediment Accumulated sediment that exceeds 10% of the Sediment cleaned out to designed designed pond depth. pond shape and depth; pond reseeded if necessary to control erosion. Liner Damage Liner is visible and has more than three'/4-inch Liner repaired or replaced. (If Applicable) holes in It. Pond Berms (bikes) Settlement Any part of berm that has settled 4 inches lower Dike should be built back to the than the design elevation. Settling can be an design elevation, indication of more severe problems with the berm or outlet works, A licensed civil engineer should be consulted to determine the source of the settlement. Emergency Tree Growth Tree growth on emergency spillways create Trees should be removed. If root Overflowl5pillway blockage problems and may cause failure of the system is small (base less than 4 and Berms over berm due to uncontrolled overtopping. inches) the root system may be left feet in height. Tree growth on berms over 4 feet In height may in place, Otherwise the roots should removed and the berm restored, lead to piping through the berm which could lead A licensed civil engineer should be A to failure of the berm, consulted for proper berm/spillway restoration. Emergency Rock Missing Only one layer of rock exists above native soil In Replace rocks to design standards. Overflow/Spillway area five square feet or larger, or any exposure of native soil at the top of out flow path of spillway. Rip -rap on inside slopes need not be replaced, 1/24/2005 2005 Surface Water Design Manual — Appendix A A-2 j APFFNDIX A MAINTENANCE REQUIRENIENTS FOR FLOW CONTROL, CONVEYANCE, AND WQ FACiLITIES NO.2 - iNFILTRATION FACILITIES Maintenance Component Infiltration Pond General Infiltration Pond Side Slopes Infiltration Pond Emergency Clvertlaw Spillway and Berms over 4 feet in height. infiltration Pond Emergency Overflow Spillway Infiltration Facility Storage Area Infiltration Facility Rock Filters (if Applicable) Infiltration Facility Sump infiltration Facility Filter Bags (if Applicable) Defect or Problem Trash & Debris Poisonous Vegetation or Noxious Weeds Contaminants and Pollution Unmowed Grass/Ground Cover Rodent Holes Insects Erosion Tree Growth Rock Missing Conditions When Maintenance Is Needed See "Detention Ponds" Table No. 1 See "Detention Ponds" Table No. 1 See "Detention Ponds" Table No, 1 See "Detention Ponds" Table No 1 See "Detention Ponds" Table No 1 See "Detention Ponds" Table No, 1 See "Detention Ponds" Table No. 1 See "Detention Ponds" Table No. 1 See "Detention Ponds" Table No. 1 Sediment A percolation test pit (ponds) or test of facility indicates facility is only working at 90% of its designed capabilities: If two inches or more sediment is present, remove. Sediment and Debris By visuai inspection, little or no water flows through filter during heavy rain storms Sump Filled with Any sediment and debris filling vault to 10% of Sediment and Debris depth from sump bottom to bottom of outlet pipe (If Applicable) or obstructing flow into the connector pipe. _ Filled with Sediment Sediment and debris fill bag more than lf2 full, and Debris Results Expected When Maintenance Is Performed See "Detention Ponds" Table No. 1 See "Detention Ponds" Table No, 1 See "Detention Ponds" Table No 1 See "Detention Ponds` Table No, 1 See "Detention Ponds" Table No. 1 See "Detention Ponds" Table No. 1 See "Detention Ponds" Table No. 1 See "Detention Ponds" Table No. 1 See "Detention Ponds" Table No. 1 Sediment is removed and/or facility is cleaned so that infiltration system works according to design. Ponds are reseeded if necessary to control erosion. Replaced gravel in rack filter, Clean out sump to design depth. Replaced fitter bag or redesign system infiltration Facility Sediment Remove when 6" or more. Sediment cleaned out to designed Pre -settling Ponds pond shape and depth or sediment and Vaults is removed from vault. Ponds are reseeded if necessary to control erosion. Note: Sediment accuMulatfoh of more than 0, 25 inches per year may indicate excessive erosion is occurring upstream of the facility or that conveyance systems are not being properly maintained. The contributing drainage area should be checked for erosion problems or inadequate maintenance of conveyance systems if excessive sedimentation is noted in an infiltration facility. Check twice a year during first 2 years of operation; once a year thereafter. Clean manholes/catch basins, repaFr damaged intetsloutlets, clean trash racks. 2005 Surface Water Design Manual — Appendix A A-3 1/24/2005 APPEtiDl A M- AINTENANCE REQtRR ,;rv[EiVTS FLOW CONTROL, CONVEYANCE, AND WQ FACILITIES NO. 3 - DETENTION TANKS AND VAULTS Maintenance Defect or Problem Conditions When Maintenance is Needed Results Expected When Component Maintenance is Performed Storage Area Plugged Air Vents One-half of the cross section of a vent is blocked Vents free of debris and sediment at any point with debris and sediment. Debris and Sediment Accumulated sediment depth exceeds 1011% of All sediment and debris removed the diameter of the storage area for'! length of from storage area. storage vault or any point depth exceeds 15% of diameter, Example, 72-inch storage tank would require cleaning when sediment reaches depth of 7 inches for more than ! length of tank. Joints Between Any crack allowing material to be transported into All joint between tank/pipe sections Tank/Pipe Section facility. are sealed Tank Pipe Bent Out of Any part of tank/pipe is bent out of shape more Tanklpipe repaired or replaced to Shape than 10% of its design shape. design. Vault Structure Damage to Wall, Cracks wider than 'l-inch and any evidence of Vault replaced or repaired to design Frame, Bottom, soil particles entering the structure through the specifications. andlor Top Slab cracks, or maintenance inspection personnel determines that the vault is not structurally sound. Damaged Pipe Joints Cracks wider than at the joint of any No cracks more than'/ -inch wide at inlet/outlet pipe or any evidence of soil particles the joint of the Inlet/outlet pipe. entering the vault through the walls. Manhole Cover Not in Place Cover is missing or only partially in place. Any Manhole is closed. open manhole requires maintenance. Locking Mechanism Mechanism cannot be opened by one Mechanism opens with proper tools. Not Working maintenance person with proper tools. Botts into frame have less than'h inch of thread (may not apply to self-locking lids.) Cover Difficult to One maintenance person cannot remove lid after Cover can be removed and Remove applying 80lbs of lift. Intent is to keep cover from reinstalled by one maintenance sealing off access to maintenance. person. Ladder Rungs unsafe King County Safety Office and/or maintenance Ladder meets design standards, person judges that ladder is unsafe due to Allows maintenance person safe missing rungs, misalignment, rust, or cracks, access Large access Gaps, Doesn't Cover Large access doors not flat and/or access hole Doors closes flat and covers access doors/plate Completely not completely covered, NOTE howeverthat hole completely. grated doors are acceptable. Lifting Dings Missing, Lifting rings not capable of lifting weight of door Lifting rings sufficient to remove lid Rusted or lid. 1/24/2005 2ti05 Surface Water Design Manuat —Appendix A A-4 J APPENDIX A 1'AAINT1:NANCE RE.QUIItEMENTS FOR FLOW CONTROL, CON VL•YANCE, AND WQ FACILITIES NO.4 - CONTROL STRUCTUREIFLOW RESTRICTOR Maintenance Defect or Problem Component l General Trash and Debris (Includes Sediment) Structural Damage Damaged or Missing Cleanout Gate Orifice Plate Damaged or Missing Obstructions Overflow Pipe obstructions Manhole See "Detention Tanks and Vaults" Condition When Maintenance Is Needed Distance between debris build-up and bottom of orifice plate is less than 1.5 feet. Structure is not securely attached to manhole wall and outlet pipe structure should support at least 1,000 Ibs of up or down pressure, Structure is not in upright position (allow up to 1o%from plumb). Connections to outlet pipe are not watertight and show signs of rust. Any holes —other than designed holes —in the structure. Cleanout gate is not watertight or is missing, Gate cannot be moved up and down by one maintenance person. Chainlrod leading to gate is missing or damaged. Gale is rusted over 50% of its surface area Control device is not working properly due to missing, out of place, or bent orifice plate. Any trash, debris, sediment, or vegetation blocking the plate: _ Any trash or debris blocking (or having the potential of blocking) the overflow pipe. See "Detention Tanks and Vaults" Table No. 3 2005 Surface Water Design Manua{— Appendix A A-5 Results Expected When Maintenance is Performed All trash and debris removed. Structure securely attached to wall and outlet pipe. Structure in correct position Connections to outlet pipe are water tight; structure repaired or replaced and works as designed. Structure has no holes other than designed holes. Gate is watertight and works as designed. Gate moves up and down easily and is watertight. Chain is in place and works as designed. Gate is repaired or replaced to meet design standards. Plate is in place and works as designed Plate is free of all obstructions and works as designed, Pipe is free of all obstructions and Works as designed. See "Detention Tanks and Vaults" Table - No. 3 1 /24/2005 APPENDIX A MAIN"I'ENANCI: REQUIIZEA4E�NTS PLOW CONTROL, CONVEYANCE, AND WQ FACILYrIES NO.5 - CATCH BASINS Maintenance Defect or Problem Conditions When Maintenance Is Needed Results Expected When component Maintenance is performed General Trash & Debris Trash or debris of more than '/S cubic foot which No Trash or debris located (Includes Sediment) is located immediately in front of the catch basin immediately in front of catch basin opening or is blocking capacity of the basin by opening. more than 10°7v- No trash or debris in the catch basin. Trash or debris (in the basin) that exceeds 113 the depth from the bottom of basin to invert the lowest pipe into or out of the basin. Trash or debris in any inlet or outlet pipe blocking more than of its height. Inlet and outlet pipes free of trash or debris. Dead animals or vegetation that could generate No dead animals or vegetation odors that could cause complaints or dangerous present within the catch basin. gases (e.g., methane). Deposits of garbage exceeding 1 cubic foot in No condition preterit which would volume: attract or support the breeding of insects or rodents. Structure Damage to Comer of frame extends more than 3/ inch past Frame is even with curb. Frame and/or Top curb face Into the street (If applicable). Slab Top slab has holes larger than 2 square Inches Top slab Is free of holes and cracks. or cracks wider than % inch (intent is to make I sure all material is running Into basin). Frame not sitting flush on top slab, i,e., Frame is sitting flush on top slab. separation of more than % inch of the frame from the top slab. Cracks in Basin Cracks wider than Y= inch and longer than 3 feet, Basin replaced or repaired to design Wall&/Bottom any evidence of soil particles entering catch standards, basin through cracks, or maintenance person fudges that structure is unsound, Cracks wider than "/2 inch and longer than 1 foot No cracks more than 114 inch wide at at the joint of any inletloutlet pipe or any the joint of inlet/outlet pipe. evidence of soil particles entering catch basin through cracks. settlement Basin has settled more than 1 inch or has rotated Basin replaced or repaired to design Misalignment more than 2 inches out of alignment. standards. Fire Hazard Presence of chemicals such as natural gas, oil No flammable chemicals present. and gasoline. Vegetation Vegetation growing across and blocking more No vegetation blocking opening to than 10% of the basin opening. basin, Vegetation growing in inlet/outlet pipe joints that No vegetation or root growth is more than 6 inches tall and less than 6 inches present. apart. Nonflammable chemicals of more than'/z cubic No pollutlon present other than Pollution foot per three feet of basin length. surface film Catch Basin Cover Cover Not in Place Cover is missing or only partially in place. Any Catch basin cover is closed open catch basin requires maintenance. Lacking Mechanism Mechanism cannot be opened by on Mechanism opens with proper tools. Not Working maintenance person with proper tools. Bolts into frame have less than '/2 inch of thread. Cover Difficult to One maintenance person cannot remove lid after Cover can be removed by one Remove applying BR lbs. of lift; intent is keep cover from maintenance person. sealing off access to maintenance. Ladder Ladder Rungs Unsafe Ladder is unsafe due to missing rungs, Ladder me design standards and misalignment, rust, cracks, or sharp edges. allows maintenance person safe access. 1/24/2005 2005 Surface Water Design Manual — ,Appendix A A-6 APPENDIXA MAINTENANCE R-EQUIREMENTS FOR FLOW CONTROL, CoN- VE.YANCE, AND WQPACILITIES NO.5 - CATCH BASINS Maintenance Defect or Problem Component Metal Grates Unsafe Grate (If Applicable) Opening Trash and Debris Damaged or Missing. Conditions When Maintenance is Needed Grate with opening wider than 715 inch Trash and debris that is blocking more than 20% of grate surface. Grate missing or broken member(s) of the grate. NO.6 - DEBRIS BARRIERS (E.G., TRASH RACKS) Maintenance Defect or Problem Condition When Maintenance is Needed Component �- General Trash and Debris Trash or debris that is plugging more than 20% of the openings in the barrier Metal Damaged/Missing Bars are bent out of shape more than 3 inches. Bars. Bars are missing or entire barrier missing. Bars are loose and rust is causing 50% deterioration to any part of barrier. NO.7 - ENERGY DISSIPATERS Maintenance ^ Defect or Problem Conditions When Maintenance is Needed Component External: Missing or Moved Only one layer of rock exists above native soil in Rock Pad Rock area five square feet or larger. Of any exposure of native soil. Pipe Plugged with Accumulated sediment that exceeds 20% of the Dispersion Trench Sediment design depth. Not Discharging Visual evidence of water discharging at Water Properly concentrated point along trench (normal condition is a `sheet ftovW' of water along trench) Intent is to prevent erosion damage. Perforations Plugged. over of perforations in pipe are plugged with debris and sediment. Water Flows Out Top Maintenance person observes water flowing out of "Distributor' Catch during any storm less than the design storm or Basin, its causing or appears likely to cause damage Receiving Area Over- Water in receiving area is causing or has Saturated potential of causing landslide problems. Internal Worn or Damaged — Structure dissipating flow deteriorates to % or ManholelChamber Post, Baffles, Side of original size or any concentrated worn spot Chamber exceeding one square foot which would make structure unsound. 2005 Surface Water Design Manual —Appendix A A-7 Results Expected When Maintenance Is performed Grate opening meets design standards. Grate free of trash and debris Grate is in place and meets design standards. Results Expected When Maintenance is Performed. Barrier clear to receive capacity flow. Bars in place with no bends more than % inch. Bars in place according to design. Repair or replace barrier to design standards. Results Expected When Maintenance is Performed. Replace rocks to design standards. Pipe cleaned/flushed so that it matches design. Trench must be redesigned or rebuilt to standards. Clean or replace perforated pipe. Facility must be rebuilt or redesigned to standards. No danger of landslides. Replace structure to design standards. U24/2005 J APPENDIX A la YUNTENANCE REQU11ZEMENTS FLOW CONTROL, CONVEYANCE, AND WQFACIL.ITIES NO.8 - FENCING Maintenance Component Defect or Problem r Conditions When Maintenance is Needed Results Expected When Maintenance Is Performed General Missing or Broken Any defect in the fence that permits easy entry to Parts in place to provide adequate Parts a facility, security, Erosion Erosion more than 4 inches high and 12-18 No opening under the fence that inches wide permitting an opening under a fence. exceeds 4Inches in height. Wire Fences Damaged Parts Post out of plumb more than 6 inches. Post plumb to within 1'K inches. Top rails bent more than 6 inches. Top tail free of bends greater than 1 inch. Any part of fence (including post, top rails, and Fence is aligned and meets design fabric) more than 1 foot out of design alignment: standards. Missing or loose tension wire. Tension wire in place and holding fabric. Missing or loose barbed wire that is sagging Barbed wire in place with less than more than 2'/ inches between posts '/. inch sag between post. Extension arm missing, broken, or bent out of Extension artn in place with no shape more than 1'/2 inches, bends larger than'/ inch. Deteriorated Paint or Part or parts that have a rusting or scaling Structurally adequate posts or parts Protective Coating condition that has affected structural adequacy. with a uniform protective coating. Openings in Fabric Openings in fabric are such that an 8-inch No openings in fabric. diameter ball could fit through. NO, 9 - GATES Maintenance Defect or Problem Conditions When Maintenance is Needed Results Expected When Component Maintenance is Performed General Damaged or Missing Missing gate or locking devices. Gates and Locking devices in place. Members Broken or missing hinges such that gate cannot Hinges intact and lubed. Gate is be easily opened and closed by a maintenance working freely. person. Gate is out of plumb more than 6 inches and Gate is aligned and vertical, more than 1 foot out of deslgn alignment. Missing stretcher bar, stretcher bands, and ties. Stretcher bar, bands, and ties in place. Openings in Fabric See "Fencing' Table No. 8 See "Fencing" Table No. 8 1/24/2005 2005 Surface Water Design Manual— Appendix A A-tt APPENDiX A IvIAWTENANCE REQUIREIVIENTS FOR I I,OW CONTROL, COf 1VEyr11`iC h7 AND WQ FACILITIES NO.10 - CONVEYANCE PIPES AND ©ITCHES Maintenance Defect or Problem Conditions When Maintenance is Needed ResultsWhen Mai tenancpe is Performed Component Sediment & Debris Accumulated sediment that exceeds 20% of the i e.cleaned of all sediment and pipe Pipes diameter of the pipe. Vegetation Vegetation that reduces free movement of water All vegetation removed so water flows freely through pipes. through pipes. Damaged protective coating is damaged; rust is causing Pipe repaired or replaced, more than 50% deterioration to any part of pipe. Any dent that decreases the cross section area Pipe repaired or replaced. of pipe by more than 2W 14. Open Ditches Trash & Debris Trash and debris exceeds 1 cubic foot per 1,000 Trash and debris cleared from square feet of ditch and slopes, ditches. Sediment Accumulated sediment that exceeds 20% of the Ditch cleaned/flushed of all sediment and debris so that it design depth. matches design. Vegetation Vegetation that reduces free movement of water Water flows freely through ditches, through ditches, Erosion Damage to See "Detention Ponds" Table No, 1 See "Detention Ponds" Table No, 1 Slopes Rock Lining Out of Maintenance person can see native soil beneath Replace racks to design standards. Place or Missing (if the rock lining. Appllcable). N0.11 - GROUNDS (LANDSCAPING) Maintenance Defect or Problem Conditions When Maintenance is Needed Results Expected When Maintenance is Performed Component Generat Weeds -- Weeds growing €n mora than 24°�° of the Weeds present in less than 5% o the landscaped area. (Nonpoisonous, not landscaped area (trees and shrubs only) noxious) Safety Hazard Any presence of poison ivy or other poisonous No poisonous vegetation present in vegetation. landscaped area. Trash or Litter Paper, cans, bottles, totaling more than 1 cubic Area clear of litter. foot within a landscaped area (trees and shrubs only) of 1,000 square feet. l Trees and Shrubs Damaged split r which affects more than 25% of the total b okenor Trees and shrubs with less than o/° of total foliage with split or broken foliage of the tree or shrub. limbs. Trees or shrubs that have been blown down or Tree or shrub in place free of injury. knocked over. Trees or shrubs which are not adequately Tree or shrub in place and supported or are leaning over, causing exposure adequately supported; remove any of the roots, dead or diseased trees. I 2005 Surface Water Design Manual — Appentfjx A A 3 I /2d12005 APPENDIX A MAINF NANCI TZUQUIIiEMENTS FLOW CONTROL, CONVEYANCE, AND WQ FACILITIES NO. 12 — ACCESS ROADS Maintenance Defect or Problem Condition When Maintenance is Needed Results Expected When Component Maintenance is Performed General Trash and Debris Trash and debris exceeds 1 cubic foot per 1,000 Roadway free of debris which could square feet (Le., trash and debris would fill up damage tires. one standards size garbage can). Blocked Roadway Debris which could damage vehicle tires (glass Roadway free of debris which could or metal). damage tires, Any obstruction which reduces clearance above Roadway overhead clear to 14 feet road surface to less than 14 feet. high: Any obstruction restricting the access to a 10- to Obstruction removed to allow at 12-foot width for a distance of more than 12 feet least a 12-foot access. or any point restricting access to less than a 10- foot width. Road Surface ` Settlement, Potholes, When any surface defect exceeds 6 inches in Road surface uniformly smooth with Mush Spots, Ruts depth and 6 square feet in area.. In general, any no evidence of settlement, potholes, surface defect which hinders or prevents mush spots, or ruts. maintenance access.. Vegetation in Road Weeds growing in the road surface that are more Road surface free of weeds taller Surface than 6 inches tall and less than 6 inches tall and than 2 inches. less than 6 inches apart within a 400-square foot area. Modular Grid Build-up of sediment mildly contaminated with Removal of sediment and disposal Pavement petroleum hydrocarbons. in keeping with Health Department recommendations for mildly contaminated soils or catch basin sediments. Shoulders and Erosion Damage Erosion within 1 foot of the roadway more than B Shoulder free of erosiorr and Ditches inches wide and 6 inches deep. matching the surrounding road. Weeds and Brush Weeds and brush exceed 18 inches in height or Weeds and brush cut to 2 inches in hinder maintenance access. height or cleared in such a way as to allow maintenance access. I/24/2005 2005 Surface Water Design Manual — Appehdix A. A-I0 AI TENDIX A Iv1AINTKNANCE RL•QUIRBMEKI S FOR 1TOW CONTROL, CONVEYAI ICE, AND WQ FACILI"rILS NO.13 - BASIC BIQFILTRATION SWALE Maintenance Component Swale Section Inlet/Outlet Flow Spreader Defect or Problem j Condition When Maintenance is Needed Sediment Sediment depth exceeds 2 inches Accumulation on Grass Standing Water When water stands in the Swale between storms and does not drain freely. Recommended Maintenance to Correct Problem Remove sediment deposits on grass treatment area of the bioswale. When finished, Swale should be level from side to side and drain freely toward outlet. There should be no areas of standing water once inflow has ceased. Any of the following may apply: remove sediment or trash blockages, improve grade from head to foot of Swale, remove clogged check dams, add underdrains or convert to a wet biofiltration sale, Constant Baseflow flow When h thel8wale. even when it haster been dry for Add a low-flowa -gravel drain length of the Swale or bypass the e weeks, and an eroded, muddy channel has baseflow around the Swale. formed in the sale bottom. Poor Vegetation When grass is sparse or bare or eroded patches Determine why grass growth is poor condition, Coverage occur in more than 10% of the swale bottom. nharrecthat Re-plant rom geofgoepl slope: plant In the swate bottom at 8-inch inteNals, or re -seed Into loosened, fertile soil. Defedfive Vegetation When the grass becomes excessively tall (greater than 10 inches) or when nuisance weeds Mow vegetation or remove nuisance vegetation so that flow not impeded. and other vegetation starts to take over. Grassto a 1ght s be of 4 inches. Remove grass clippings. Excessive Shading Grass growth is poor because sunlight does not If possible, trim back over -hanging limbs, remove brushy vegetation on reach Swale. adjacent slopes. Trash and debris accumulated lh the bioswale, movetrash and debris from Trash and Debris ti Accumulation — —� ErosionlScouring Eroded or scoured Swale bottom due to flow For ruts or bare areas less than 12 inches wide, repair the damaged channelization, or higher flows. area by filling with crushed gravel. The grass will creep in over the rock In time. If bare areas are large, generally greater than 12 inches wide, the swaie AOUld be regraded and re -seeded, For smaller bare areas, overseed when bare spots are evident, or take plugs of grass from the upper slope and plant in the Swale bottom at 8-inch intervals. Inlet/outtet areas clogged with sedimen1-and/:or Remove material so that there is no clogging or blockage in the inlet and Sediment and Debris debris outlet area. Concentrated Flow Flow spreader uneven or clogged so that flows are not uniformly detributed through entire Swale Level the spreader and clean so that flows are spread evenly over entire width. Swale width. 2005 Surface Water Design Manual —Appendix A A-] I 1 /24/2005 J APPENDIX A ;VIA]NTENANCE, REQUIREMhNTS FLOW CONTROL, CONV.FYj\NCE, AND "K FACILITIES NO. 14 -WET B[OFILTRATION SWALE Maintenance Defect or Problem Condition When Maintenance is Needed Recommended Maintenance to Component Correct Problem Swale Section Sediment Sediment depth exceeds 2 inches in 10% of the Remove sediment deposits in Accumulation Swale treatment area. treatment area. Water Depth Water not retained to a depth of about 4 inches Build up or repair outlet berm so that during the wet season. water is retained In the wet Swale. Defective Wetland Vegetation becomes sparse and does not Determine cause of lack of vigor of Vegetation provide adequate filtration, OR vegetation is vegetation and correct. Replant as crowded out by very dense clumps of cattail needed, For excessive cattail Which do not allow water to flow through the growth, cut cattail shoots back and clumps, compost offsite. Note; normally wettand vegetation does riot need to be harvested unless dle-back is causing oxygen depletion in downstream waters. Trash arid Debris Trash and debris accumulated in the wet swale. Rernove trash and debris from wet Accumulation Swale, Erosion/Scouring Swale has eroded or scoured due to now Check design flows to assure Swale channelization, or higher flows. is large enough to handle flows. Bypass excess Flows or enlarge Swale, Replant eroded areas with fibrous -rooted plants such as Juncus effusus (soft rush) in wet areas or snowberry (Symphorlcarpos albus) in dryer areas. Inlet/Outlet Sediment and Debris inlet/Outlet area clogged with sediment and/or Remove clogging or blockage in the debris. inlet and outlet areas. NO.15 - FILTER STRIP Maintenance } Defect or Problem { Condition When Maintenance is Needed Component Grass Strip I Sediment I Sediment depth exceeds 2 inches. I` Accumulation on Grass Flow Spreader Defective Vegetation I When the grass becomes. excessively tail (greater than 10 inches) or when nuisance weeds and other vegetation starts to take over. Trash and Debris Trash and debris accumulated on the filter strip. Accumulation Erosion/Scouring Eroded or scoured areas due to flow channeliization, or higher flows. Concentrated Flow Flow spreader uneven or clogged so that flows are not uniformly distributed through entire filter width. Recommended Maintenance to Correct Problem Remove sediment deposits, re -level so slope is even and flows pass evenly through strip. Mow grass, control nuisance vegetation such that flow not impeded. Grass should be mowed to a height between 3.4 inches. Remove trash and debris from filter. For ruts or bare areas less than 12 inches wide, repair the damaged area by filling with crushed gravel. The grass will creep In over the rock in time. if bare areas are large, generally greater than 12 inches wide, the filter strip should be re- graded and re -seeded. For smaller bare areas, overseed when bare spots are evident. Level the spreader and clean so that flows are spread evenly over entire filter width, 1 f24/2005 2005 Surface Water Design Manual — Appendix A A-12 APPENDIX A NLAINfENANCE REQ111REMENTS FOR FLOW CONTROL, CONVEYANCE, AND WQ F ACII-ITIL-S J NO.16 - WETPOND I Maintenance Defector Problem Component Pond Area i Water Level Condition When Maintenance Is Needed Recommended Maintenance to Correct Problem First cell empty, doesn`t hold water. Line the first cell to maintain at least 4 feet of water. Although the second cell may drain, the first cell must remain full to control turbulence of the incoming flow and reduce sediment resuspension.. Detective Vegetation vegetation such as grass and weeds need to be Vegetation should be mowed to 4 to snowed when it starts to impede aesthetics of 5 inches in height. Trees and pond. Mowing is generally required when height bushes should be removed where exceeds 18 inches. Mowed vegetation should be they are interfering with pond removed from areas where it could enter the maintenance activities. that is, at tha pond, either when the pond level rises: or by inlet, outlet and near engineered rainfall runoff. structures. Algae Mats When algae mats develop over more than 10% of the water surface, they should be removed. Algae mats that cover more than 10% of the surface of any cell Also remove mats in the late summer before fall should be removed. A rake or rains, especially in 5ensitrve Lake Protection mechanical device should be used Areas. Excessive algae mats interfere with a to remove the algae. Removed algae can be left to dry on the pond dissotved oxygen content in the water and pose threat to downstream lakes if excess nutrients slope above the 100-year water are released, surface. Trash and Debris Sediment Accumulation Oil Sheen on Water Erosion Pond Dike/Berm Settlement internal Berm I concentrated Flow InletiOutiet Pipe I Sediment and Debris Overflow Spillway I Rock Missing Accumulation that exceeds 1 cubic foot per 1000 Trash and debris removed from square foot of pond area. pond. Sediment accumulations In pond bottom that Removal of sediment from pond exceeds the depth of sediment zone plus 6 bottom. inches, usually in the first cell. Prevalent and visible oil sheen. Remove oil from water by use of oil - absorbent pads or by vactor truck. Refer problem to locate source and correct If chronic law levels of oil persist, plant wetland plants such as Juncus e/Fusus (soft rush) which. can uptake small concentrations of oil. Erosion of the pond's side slopes and/or Slopes should be stabilized by using scouting of the pond bottom, that exceeds 6 proper erosion control measures, inches, or where continued erosion is prevalent. and repair methods. Any part of these components that has settled 4 Dike/berm is repaired to inches or lower than the design elevation, or specifications. inspector determines dikelberm is unsound. Berm dividing cells should be level. Iniet/Outlet pipe clogged with sediment and/or debris material. Rock is missing and soil is exposed at top of spillway or outside slope. Build rip low areas of berm or lower high areas so that the berm surface Is level and water flows evenly over the entire length of the berm from the first cell to the second. No clogging or blockage in the inlet and outlet piping Replace rocks to specifications. 1/24/2005 2005 Surfncc Water Design Manual — Appendix A A-13 APPENDIX A MAINTEN:1NCE REQUIREIVIENIS FLOW C'ONI`ROL, CONVEYANCE, AND WQ FACILITI.ES NO,17 - MTVAULT Maintenance Defect: or Problem Condition When Maintenance is Needed Recommended Maintenance to Component Correct Problem Vault Area Trash/Debris Trash and debris accumulated in vault (includes Remove trash and debris. Accumulation floatables and non-floatables), Sediment Sediment accumulation in vault bottom exceeds Remove sediment from vault. Accumulation the depth of the sediment zone plus 6 inches. Ventilation Ventilation area blocked or plugged Remove or clear blocking material from ventilation area. A specified % of the vault surface area must provide ventilation to the vault interior (seep. 6-82 for required %). Vault Structure Damage to Wall, Cracks wider than'/rinch and any evidence of Vault replaced or repaired to design Frame, Bottom, soil particles entering the structure through the specifications. and/or Top Slab cracks, or maintenance inspection personnel determines that the vault is not structurally sound. Damaged Pipe Joints Cracks wider then Mr -inch at the joint of. any No cracks More than %.-.inoh wide at Inlet/outlet pipe or any evidence of soil particles the joint of the inlet/Outlet pipe. entering the vault through the walls. Baffles DamagediDefective Baffles corroding, cracking, warping and/or Repair or replace baffles to showing signs of failure as determined by specifications. maintenance/inspection staff. Inlet/Outiet Damaged Pipes Inletioutlet piping damaged or broken and in Pipe repaired and/or repfaced. need of repair. TrashlDebiis Trash and debris accumulated in pipe or Remove trash and debris. Acaimulatlon inlet/outlet (includes floatables and non- fioatables). Access Cover Damaged/Not Cover cannot be opened or removed, especially Pipe repaired or replaced to proper Working by one person. working specifications. Access Ladder Damaged Ladder is corroded or deteriorated, not Ladder replaced or repaired to functioning properly, missing rungs, has cracks specifications, and is safe to use as and/or misaligned. Confined space warning sign determined by inspection personnel. missing, Replace sign warning of confined space entry requirements, 1/24/2005 2005 Surface Water Design Manual — Appendix A A-I4 AFPEN[XX A MANI FFNANCb REQZ JIREMLNI'S FOR FLOW CON`i"ROL, C09VEYA.NCE. AND WQ FACILITIES �NO. '18=SAND FILTER POND Maintenance Defect or Problem Component Pond Area Sediment Accumulation on top layer Trash and Debris Accumulation Defective Vegetation (Note. grass is optionab Erosion Damage to Slopes Clean -Outs Sediment/Debris Sand Filter Media ! Plugging Prolonged flows Short Circuiting Rock Pad Missing or Out of Place Flow spreader Concentrated Flow Pipes Damaged Condition When Maintenance is Needed Sediment depth exceeds 1/2-inch. Trash and debris accumulated on sand filter bed. When the grass becomes excessively tall (greater than 6 inches) or when nuisance weeds and other vegetation starts to take over. Erosion over 2 inches deep where cause of damage is prevalent or potential for continued erosion is evident, When the clean -outs become full or partially plugged with sediment and/or debris. Drawdown of water through the sand filter media, takes longer Shan 24 hours. and/or flow through the overflow pipes occur. frequently. Sand is saturated for prolonged periods of time (several weeks) and does not dry out between storms due to continuous base flow or prolonged flows from detention facilities. When flows become concentrated over one section of the sand filter rather than dispersed Sol! beneath the rock is visible. Flow spreader uneven or clogged so that flows are not uniformly distributed across sand filter. Any part of the piping that is crushed or deformed more than 20% or any other failure to the piping 2005 Surface Water Design Manual — Appendix A A 15 Recommended Maintenance to Correct Problem No sediment deposit on grass layer of sand filter that would impede permeability of the filter section. Trash and debris removed from sand filter bed. Mow vegetation and/or remove nuisance vegetation. Slopes should be stabilized by using proper erosion control measures. Sediment removed from the clean - outs Usually requires scraping of top several inches of sand. May occasionally require replacement of entire sand filter depth, depending on extent of plugging. A sieve analysis is helpful to determine if the lower sand has too high a proportion of fine material. Limit the low, continuous flows to a small portion of the facility by using a low wooden divider or slightly depressed sand surface Flory and percolation of water through the sand filter is uniform and dispersed across the entire filter area. Replace or rebuild the rock pod to design specifications. Level the spreader and clean so that flows are spread evenly over sand filter. Pipe repaired or replaced. 1 /24/2005 J A€'I'ENDiX A MAINTENANCE REQUII2EMFN S rLOW CONTROL, CONVEYANCE, AND WQ FACILITIES NO. 19 -SAND FILTER VAULT Maintenance Defector Problem condition When Maintenance is Needed Recommended Maintenance to Component Correct Problem Sand Media Section Sediment Sediment depth exceeds %'-inch. Remove sediment deposits on send Accumulation filter section, which would impede permeability of the filter section. Trash/Debris Trash and debris accumulated in vault, or pipe Trash and debris removed from Accumulation inlet/outlet (floatables and non-floatables) vault, and inlet/outlet piping, Short Circuiting When seepage/flow occurs along the vault walls Sand filter media section re-laid and and corners. Sand eroding near inflow area. compacted along perimeter of vault to form a semi -seal. Add erosion protection to dissipate force of incoming flow and curtail erosion. Pre -Settling Section Sediment Sediment accumulation in vault bottom exceeds Remove sediment deposit in the first Accumulation the depth of the sediment zone plus 6 inches. chamber of the vault, Drain Sediment When drain pipes, cleanouts became full with Remove the material from the Pipes/Cleanou€s Accumulation sediment and/or debris, facilities. Inlet/outlet Pipes Trash/Debris Trash and debris accumulated in inletfoutlet Trash and debris removed from Accumulation pipes (floatables and nonAbatables) vault, and inlet/outlet piping. Damaged Inlet or outlet piping damaged or broken and in Pipe repaired and/or replaced. need of repair. Vault Structure Damaged to Wall%, Cracks wider than %Anch and any evidence of Vault replaced or repaired to design Frame, Bottom and/or soil particles entering the structure through the specifications. Top Slab. cracks, or maintenance/inspection personnel determines that the Vault is not structurally sound. Damaged Pipe Joints Cracks wider than %-inch at the joints of any No cracks more than 1/4-inch wide at inlet/outlet pipe or any evidence of soil particles the joint of the inlet/outlet pipe entering the vault through the walls. Ventilation Ventilation area blocked or plugged Remove or clear blocking material. from ventilation area. A specified of the vault surface area must provide ventilation to the vault interior (see p. 6-122 for required Baffles/Internal Damaged Baffles orwalls corroding, cracking, warping Repair or replace baffles or walls to Walls and/or showing signs of failure as determined by specifications. maintenance/inspection person. Access Cover Damaged/Not Cover cannot be opened, corrosion/deformation Cover repaired to proper working Working of cover_ specifications or replaced. Ladder replaced or repaired to Access Ladder Damaged Ladder is corroded or deteriorated, not functioning properly, missing rungs, cracks, arld specifications, and is safe to use as misaligned determined by inspection personnel. I/24/2005 2005 Surface Water Design Manual—AppendixA A-16 APPENDIX A MAINTENANCE REQUIRE1v1ENTS FOR I=LOVV CONTROL, CONVEYANCE, AND WQ FACILITIES 1 NO.2© - STORMFILTER° Maintenance Defect or Problem Component Media Section Sediment Accumulation on Media. Trash/Debris Accumulation Sediment First Chamber Accumulation Drain Pipes Clean- Sediment Outs Accumulation Condition When Maintenance is Needed Sediment depth exceeds 0.25 inches. Trash and debris accumulated on compost filter bed. Sediment depth exceeds 6 inches in first chamber. When drain pipes, clean -outs, become full with sediment and/or debris. NO.21 - STORMFILTER& (CARTRIDGE TYPE) Maintenance Defect or Problem Condition When Maintenance is Needed Component Plugged Drawdown of water through the media takes longer than 1 hour, and/or overflow occurs Compost Media frequently. Short Circuiting Flows do not property enter filter cartridges, Damaged Any part of the pipes that are Crushed, da.rnaged due to corrosion and/or settlement, Pipes Damaged/Not Working Damage to Wall, Frame, Bottom, and/or Top Slab Cover cannot be opened, one person cannot open the cover, corrosionideformation of cover. Cracks wider than Yz-inch and any evidence of soil particles entering the structUM through the cranks, or maintenancelinspection personnel determines that the vault is not structurally Access Cover Vault Structure sound. Damaged Pipe Joints Cracks wider than %-inch at the joint of any inlet/outlet pipe or any evidence of soil particles entering the vault through the walls, Damaged Baffles corroding, cracking warping, and/or showing signs of failure as determined by Baffles maintenancelinspection person. Damaged Ladder is corroded or deteriorated, not functioning properly, missing rungs, cracks, and Access Ladder misaligned, 2005 Surface Water Design \hamual•— Appendix A A-l7 Recommended Maintenance to Correct Problem No sediment deposits that would impede permeability of the compost media. Trash and debris removed from the compost fitter bed. No sediment deposits in vault bottom of first chamber. Remove the accumulated material from the facilities. Recommended Maintenance to Correct Problem Replace media cartridges, Replace filter cartridges. Pipe repaired and/or replaced. Cover repaired to proper working specifications or replaced, vault replaced or repaired to design specifications, No cracks more than'/, -inch wide at the joint of the inlet/outlet pipe, Repair or replace baffles to specification. Ladder replaced or repaired and meets specifications, and is safe to use as determined by inspection personnel. 1/24i2005 APPENDIX .A MAIXI'FNANCE REQUIREMENTS I'I;OW CONTROL, CONVEYANCE, AND WQ. FACI I,ITIFS NO.22 - BAFFLE OIUWATER SEPARATOR Maintenance Defect Condition When Maintenance is Needed Results Expected When Component Maintenance is Performed. Vault Area Monitoring Inspection of discharge water for obvious signs Effluent discharge from vault should of poor water quality, be clear with out thick visible sheen. Sediment Sediment depth in bottom of vault exceeds 6 No sediment deposits on vault Accumulation inches in depth- bottom which would impede flow through the vault and separation efficiency. Trash and Debris Trash and debris accumulation in vault Trash and debris removed from Accumulation (floatables and non-floatables). vault, and inletloutlet piping, Oil Accumulation Oil accumulations that exceed 1 inch, at the Extract ail from vault by vactoring. surface of the water Disposal in accordance with state and Iocat rules and regulations. Vault Structure Damage to Wall, Cracks wider than '/,Inch:or evidence of.soil Vault replaced or repaired to design Frame, Bottom, particles entering the structure through the specifications, andfor Top Slab cracks, or maintenance/inspection personnel determines that the vault is not structurally sound. Damaged Pipe Joints Cracks wider than %Anch at the joint of any No cranks more than %finch wide at inlet/outlet pipe or any evidence of soil particles, the joint of the inleVoutlet pipe. entering the vault through the walls. Baffles Darnaged Baffles corroding, cracking, warping and/or Repair or replace baffles to showing signs of failure as determined by specifications. rnaintenahcel€nspection person. Inlet/Outlet Pipes Trash and Debris Trash and debris accumulation in tnleboutlet Trash and debris removed from Accumulation (floatables and non-floatables), vault, and inlevoutlet piping. Damaged Pipes Inlet or outlet piping damaged or broken and in pipe repaired or replaced, need of repair. Access Cover Damaged/Not Cover cannot be opened. Corrosionldeformation Cover repaired to proper working Working of cover, specifications or replaced: Access Ladder Damaged Ladder is corroded or deteriorated, hot Ladder replaced or repaired and functioning property, missing rungs, cracks, and meets specifications, and is safe to Misaligned. use as determined by inspection personnel. 1124/2005 2005 Surface Water Design. Manual -- Appendix A A-19 APPENDIX A MAINI'ENANICE RLQUIPCIENIENTS FOR FLOW CONTROL, CONVEYANCE. AND WQ FACILITIES NO.23 - COALESCING PLATE OIUWATER SEPARATOR Maintenance Defect Condition When Maintenance Is Needed Component Results Expected When Maintenance is Performed Vault Area Monitoring Inspection of discharge water for obvious signs of poor water quality. Effluent discharge from vault should be clear with no thick visible sheen. Sediment Sediment depth in bottom of vault exceeds 5 Inches in depth andlar visible signs of sediment No sediment deposits on vault bottom and plate media, which Accumulation on plates. would impede flow through vault and separation efficiency. Trash and Debris Trash and debris accumulated in vault, or pipe Trash and debris removed from vault, and inlet/outlet piping. Accumulation inlet/outlet, floatables and non-floatables. Oil Accumulation oil accumulation that exceeds 1 inch at the water from ult by vactoring methodsllCle n coallescing plates surface. by thoroughly rinsing and flushing. Should be no visible oil depth on water - Coalescing Plates Damaged Plate media broken, deformed, cracked and/or pack depending mediapack or ent re plat portion showing signs of failure. severity of failure. Vault Structure I Darriage to Wall, Cracks wider than Yrinch and any evidence of soil entering the structure through the Vault replaced or repaired to design specifications. Frame, Bottom, and/or Top Slab particles cracks, or maintenance inspection personnel determines that the vault is not structurally sound. Damaged Pipe Joints Cracks wider than `Frinch at the joint of any inlet/outlet pipe or any evidence of soil particles No cracks more than %-inch wide at the joint of the inlet/outiet pipe. entering the vault through the walls, Baffles Damaged Baffles corroding, cracking, warping andlar Repair or replace baffles to specifications. showing signs of failure as determined by maintenance/inspection person. Inlet/Outlet Pipes I Trash and Debris Trash and debris accumulation in inlet/outlet Trash and debris removed from vault, and inlet/outlet piping. Accumulation (floatables and non-floatables), Damaged Pipes Inlet or outlet piping damaged or broken and in Pipe repaired or replaced. need of repair. Access Cover Damaged/Not Cover cannot be opened. Corrosion/deformation Cover repaired to proper working specifications or replaced. Working of cover. Access Ladder Damaged Ladder is corroded or deteriorated, not functioning properly, missing rungs, cracks, and Ladder replaced or repaired and meets specifications, and is safe to misaligned. use as determined by inspection personnel 1 /24/2005 2005 Surface Water Design Manual — .Appendix A A-19 APPENDIX A MAINTENANCE REQUIRIs'NIENIS FLOW CONTROL, CONVEYANCE, AND WQ ]'ACILITIES NO.24 - CATCHBASIN INSERT Maintenance Defect or Problem Conditions When Maintenance is Needed Results Expected When Component Maintenance is Performed Catch Basin Inspection Inspection cfinedia insert is required. Effluent waterfrom media insert is free of oils and has no visible sheen. Sediment When sediment forms a cap over the insert No sediment cap on the insert Accumulation media of the insert and/or unit. media and its unit. Trash and Debris Trash and debris accumulates on insert unit Trash and debris removed from Accumulation creating a blockagelrestriction. insert unit. Runoff freely flows into catch basin. Media Insert Water Saturated Catch basin insert is saturated With water, which Remove and replace media insert no longer has the capacity to absorb. Oil Saturated Media oil saturated due to petroleum spill that Remove and replace media insert drains into catch basin. Service Life Exceeded Regular interval replacement due to typical Remove and replace media at average life of media insert product, regular intervals, depending on insert product 1 /24/2005 2005 Surface Water Design Manual —Appendix A A-20 Appendix G.2— Catch Basin Stormfilter Operation and Maintenance ♦► ��ji�rlT�►Il,�J° ■ Maintenance ����•'� ••r - -- Operation and STORMWATER SOLUTIONSr CatchBasin StormFilter"" important. These guidelines should be used as a part of your site stormwater pian. overview The CatchBasin StormFilterT" (CBSF) consists of a multi -chamber steel, concrete, or plastic catch basin unit that can contain up to four StormFilter cartridges. The steel CBSF is offered moth as a standard and as a deep unit. The CBSF is installed flush with the finished grade and is applicable for both constrained lot and retrofit applications. It can also be fitted with an inlet pipe for roof leaders or similar applications. The. CBSF unit treats peak water quality design flows up to 0.13 cfs, coupled witin an internal weir overflow capacity of 1.0 cfs for the standard unit, and 1.8 cfs for the deep steel and concrete units. Plastic units have an internal weir overflow capacity of 0.5 cfs_ Design Operation The CBSF is installed as the primary receiver of runoff, similar to a standard, grated catch basin. The steel and concrete CBSF units have an H-20 rated, traffic- bearing lid that allows the filter to be installed in parking lots, and for all practical purposes, takes up no land area.. Plastic units can be used in landscaped areas and for other non -traffic -bearing applications. The CBSF consists of a sumped inlet chamber and a cartridge chamber(s). Runoff enters the. sumped inlet chamber either by sheet flow from a paved surface or from an inlet pipe discharging directly to the unit vault. The inlet chamber is equipped with an internal baffle, which traps debris and floating oil and grease, and an overflow weir. While in the inlet chamber, heavier solids are allowed to settle into the deep sump, while fighter solids and soluble pollutants are directed under the baffle and into the cartridge chamber through a port between the baffle and the overflow weir. Once in the cartridge chamber, polluted water ponds and percolates horizontally through the media in the fitter cartridges. Treated water collects in the cartridge's center tube from where it is directed by an under -drain manifold to the outlet pipe on the downstream side of the overflow weir and discharged. When flows into the CBSF exceed the water quality design value, excess water spills over the overflow weir, bypassing the. cartridge bay, and discharges to the outlet pipe. Applications The CBSF is particularly useful where small flows are being treated or for sites that are flat and have little available hydraulic head to spare. The unit is ideal for applications in which standard catch basins are to be used. Both water quality and catchment issues can be resolved with the use of the CBSF. Retro-Fit The retrofit market has many possible applications for the CBSF. The CBSF can be installed by replacing an existing catch basin without having to "chase the grade," thus reducing the high cost of re- piping the storm system. 02006 CONTECH Stormwater Solutions ToVree: 800.548.4667 contechstorrwater.cotn CatchBasin StormFilter Operation and Maintenance Guidelines Maintenance Guidelines Maintenance procedures for typical catch basins can be applied to the CatchBasin StormFilter (CBS'F). The filter cartridges contained in the CBSF are easily removed and replaced during maintenance activities according to the following guidelines. 1. Establish a safe working area as per typical catch basin service activity. 2. Remove steel grate and diamond plate cover (weight ;t� 100 lbs. each). 3. Turn cartridge(s) counter -clockwise to disconnect from pipe manifold. 4. Remove 4" center cap from cartridge and replace with lifting cap. 5. Remove cartridge(s) from catch basin by hand or with vactor truck boom. 6. Remove accumulated sediment via vactor truck (.min. clearance 13" x 24"). 7. Remove accumulated sediment from cartridge bay. (min. clearance 9.25" x 11") 8, Rinse interior of both bays and vactor remaining water and sediment. 9. Install fresh cartridge(s) threading clockwise to pipe manifold, 10. Replace cover and grate. 11. Return original cartridges to CONTECH Stormwater Solutions for cleaning and media disposal. Media may be removed from the filter cartridges using the vactor truck before the cartridges are removed from the catch basin structure. Empty cartridges can be easily removed from the catch basin structure by hand. Empty cartridges should be reassembled and returned to CONTECH Stormwater Solutions, as appropriate. Materials required include a lifting cap, vactor truck, and fresh filter cartridges. Contact CONTECH Stormwater Solutions for specifications and availability of the lifting cap: The vactor truck must be equipped with a hose capable of reaching areas of restricted clearance. The owner may refresh spent cartridges. Refreshed cartridges are also available from CONTECH Stormwater Solutions on an exchange basis. Contact the maintenance department of CONTECH Stormwater Solutions at (505) 240-3393 for more information. Maintenance is estimated at 26 minutes of site time. For units with more than one cartridge, add approximately 5 minutes for each additional cartridge. Add travel time as required. ©2006 CONTECH Stormwater Solutions .� Toll -tree: 800,648.4667 2 of 3 contecnsto'rmwater.com CatchBasin StormFilter Operation and Maintenance Guidelines Mosquito Abatement In certain areas of the United States, mosquito abatement is desirable to reduce the incidence of vectors In BMPs with standing water, which could provide mosquito breeding habitat, certain abatement measures can be taken. 1. Periodic observation of the standing water to determine if the facility is harboring mosquito larvae. 2. Regular catch basin maintenance 8. Use of larvicides containing Bacillus thuringiensis israelensis (STI). BTi is a bacterium toxic to mosquito and black fly larvae. In some cases, the presence of petroleum hydrocarbons may interrupt the mosquito growth cycle. Using Larvicides in the GatchBasin StormFilter Larvicides should be used according to manufacturer's recommendations. Two widely available products are Mosquito Dunks and Summit B.t,i. Briquets. For more information, visit http.,/ANww.summitchemical.com/mos—ctrl/d efault.htm. The larvicide must be in contact with the permanent pool. The larvicide should also be fastened to the CatchBasin StormFilter by string or wire to prevent displacement by high flows. A magnet can be used with a steel catch basin. For more information on mosquito abatement in stormwater BMPs, refer to the following: http;llwwvv-ucmrp.ucdevis.edu/publications/ managingrnosquitoesstormwater8125. pdf .�—r_ .R-f�- 62006�CbNTECH 5fom�watsr 5oluticins Tolkree; 800.548.4667 conlachstormwateccom CatchSasin StormFilter operation and Maintenance Guidelines Appendix G.3-- Stormfilter Inspection and Maintenance Procedures Maintenance Guidelines The primary purpose of the Stormwater Management StormFilter® is to filter out and prevent pollutants from entering it waterways. Like any effective filtration system, periodically se pollutants must be removed to restore the StormFilter to its full efficiency and effectiveness. Maintenance requirements and frequency are dependent on the pollutant load characteristics of each site. Maintenance activities may be required in the event of a chemical spill or due to excessive sediment loading from site erosion or extreme storms. It is a good practice to inspect the system after major storm events. Maintenance Procedures Although there are likely many effective maintenance options, we believe the fallowing procedure is efficient and can be implemented using common equipment and existing maintenance protocols. A two step procedure is recommended as follows: 1.Inspection Inspection of the vault interior to determine the need for maintenance. 2. Maintenance Cartridge replacement Sediment removal Inspection and Maintenance Timing At least one scheduled inspection should take place per year with intenance following as warranted. First, an inspection should be done before the winter season. During the inspection the need for maintenance should be determined and, if disposal during maintenance will be required, samples of the accumulated sediments and media should be obtained. Second, if warranted, a maintenance (replacement of the filter cartridges and removal of accumulated sediments) should be performed during periods of dry weather. In addition to these two activities, it is important to check the condition of the StormFilter unit after major storms for potential damage caused by high flows and for high sediment accumulation that may be caused by localized erosion in the drainage area. It may be necessary to adjust the inspection/ maintenance schedule depending on the actual operating conditions encountered by the system. In .general, inspection activities can be conducted at any time, and maintenance should occur, if warranted, in late summer to early fall when flows into the system are not likely to be present, Maintenance Frequency The primary factor controlling timing of maintenance of the StormFilter is sediment loading. A properly functioning system will remove solids from water by trapping particulates in the porous structure of the filter media inside the cartridges. The flow through the system will naturally decrease as more and more particulates are trapped. Eventually the flow through the cartridges will be low enough to require replacement It may be possible to extend the usable span of the cartridges by removing sediment from upstream trapping devices on a routine as -needed basis in order to prevent material from being re -suspended and discharged to the StormFilter treatment system. Site conditions greatly influence maintenance requirements. StormFilter units located in areas with erosion or active construction may need to be inspected and maintained more often than those with fully stabilized surface conditions. The maintenance frequency may be adjusted as additional monitoring information becomes available during the inspection program. Areas that develop known problems should be inspected more frequently than areas that demonstrate no problems, particularly after major storms. Ultimately, inspection and maintenance activities should be scheduled based on the historic records and characteristics of an individual StormFilter system or site. It is recommended that the site owner develop a database to properly manage StormFilter inspection and maintenance programs, Prior to the development of the maintenance database, the following maintenance frequencies should be followed: Inspection One time per year After major storms Maintenance As needed, based on results of inspection (The average maintenance lifecycle is approximately 1-3 years) Per Regulatory requirement In the event of a chemical spill Frequencies should be updated as required. The recommended initial frequency for inspection is one time per year. StormFilter units should be inspected after major storms. Sediment removal and cartridge replacement on an as needed basis is recommended unless site conditions warrant. Once an understanding of site characteristics has been established, maintenance may not be needed for one tothree years, but inspection is warranted and recommended annually. Inspection Procedures The primary goal of an inspection is to assess the condition of the cartridges relative to the level of visual sediment loading as it relates to decreased treatment capacity. It may be desirable to conduct this inspection during a storm to observe the relative flow through the filter cartridges. If the submerged cartridges are severely plugged, then typically large amounts of sediments will be present and very little flow will be discharged from the drainage pipes. If this is the case, then maintenance is warranted and the cartridges need to be replaced. Warning: In the case of a spill, the worker should abort inspection activities until the proper guidance is obtained. Notify the local hazard control agency and CONTECH Stormwater Solutions immediately. To conduct an inspection: Important: Inspection should be performed by a person who is familiar with the operation and configuration of the StormFilter treatment unit. 1. if applicable, set up safety equipment to protect and notify surrounding vehicle and pedestrian traffic. 2. Visually inspect the external condition of the unit and take notes concerning defects/problems- 3. Open the access portals to the vault and allow the system vent. 4. Without entering the vault, visually inspect the inside of the unit, and note accumulations of liquids and solids, 5, Be sure to record the level of sediment build-up on the floor of the vault, in theicirebay, and on top of the cartridges. -If flow is occurring, note the flow of water per drainage pipe. Record all observations. Digital pictures are valuable for historical documentation. 6, Close and fasten the access portals. 7. Remove safety equipment. 8, If appropriate, make notes about the local drainage area relative to ongoing construction, erosion problems, or high loading of other materials to the system. 9. Discuss conditions that suggest maintenance and make decision as to weather or not maintenance is needed. Maintenance Decision Tree The need for maintenance is typically based on results of the inspection. The following Maintenance Decision Tree should be used as a general guide. (Other factors, such as Regulatory Requirements, may need to be considered) 1, Sediment loading on the vault floor. a, If >4" of accumulated sediment, maintenance is required. 2, Sediment loading on top of the cartridge. a, If > 1/4" of accumulation; maintenance is required.. 3, Submerged cartridges. a. If >4" of static water in the cartridge bay for more that 24 hours after end of rain event, maintenance is required. 4, Plugged media, a. If pore space between media granules is absent, maintenance is required, 5, Bypass condition, a. if inspection is conducted during an average rain fall event and StormFilter remains in bypass condition (water over the internal outlet baffle wall or submerged cartridges), maintenance is required. 6, Hazardous material release. a, if hazardous material release (automotive fluids or other) is reported, maintenance is required. 7. Pronounced scum line. a, if pronounced scum line (say -� 1/4" thick) is present above top cap, maintenance is required. 8. Calendar Ufecyde. a. If system has not been maintained for 3 years maintenance is required. 1 u� Assumptions • No rainfall for 24 hours or more • No upstream detention (at least riot draining into 5tormFilter) -tructure is online cutlet pipe is clear of obstruction - t nnstruction bypass is plugged Maintenance Depending on the configuration of the particular system, maintenance personnel will be required to enter the vault to perform the maintenance. Important: If vault entry is required. OSHA rules for confined space entry must be followed. Filter cartridge replacement should occur during dry weather. It may be necessary to plug the filter inlet pipe if base flows is occurring. Replacement cartridges can be delivered to the site or customers facility. Information concerning how to obtain the replacement cartridges is available from CONTECH Stormwater Solutions. Warning: In the case of a spill, the maintenance personnel should abort maintenance activities untilthe proper guidance is obtained. Notify the local hazard control agency and CONTECH Stormwater Solutions immediately, To conduct cartridge replacement and sediment removal maintenance: f applicable, set up safety equipment to protect maintenance personnel and pedestrians from site hazards. 2. Visually inspect the external condition of the unit and take notes concerning defects/problems. 3. Open the doors (access portals) to the vault and allow the system to vent. 4. Without entering the vault, give the inside of the unit, including components, a general condition inspection. 5. Make notes about the external and internal condition of the vault. Give particular attention to recording the level of sediment build-up on the floor of the vault, in the forebay, and on top of the internal components. 6. Using appropriate equipment offload the replacement cartridges (up to 150 Ibs, each) and set aside. 7. Remove used cartridges from the vault using one of the following methods: Method 1: A. This activity will require that maintenance personnel enter the vault to remove the cartridges from the under drain manifold and place them under the vault opening for lifting (removal), Unscrew (counterclockwise rotations) each filter cartridge from the underdrain connector, Roll the loose cartridge, an edge, to a convenient spot beneath the vault access. Using appropriate hoisting equipment, attach a cable from the boom, crane, or tripod to the loose cartridge. Contact CONTECH Stormwater Solutions for suggested attachment devices, Important: Note that cartridges containing leaf media (CSF) do riot require unscrewing from their connectors. Take care not to damage the manifold connectors. This connector should remain installed in the manifold and could be capped during the maintenance activity to prevent sediments from entering the underdrain manifold, B. Remove the used cartridges (up to 250 lbs. each) from the vault, Important: Care must be used to avoid damaging the cartridges during removal and installation. The cost of repairing components damaged during maintenance will be the responsibility of the owner unless CONTECH Stormwater Solutions performs the maintenance activities and damage is not related to discharges to the system. C. Set the used cartridge aside or load onto the hauling truck. D, Continue steps a through c until all cartridges have been removed. Method 2: A. Enter the vault using appropriate confined space protocols. B. Unscrew the cartridge cap. C. Remove the cartridge hood screws (3) hood and float. D. At location under structure access, tip the cartridge on its side. important: Note that cartridges containing media other than the leaf media require unscrewing from their threaded connectors. Take care not to damage the manifold connectors. This connector should remain installed in the manifold and capped if necessary. D. Empty the cartridge onto the vault floor. Reassemble the empty cartridge. E. Set the empty, used cartridge aside or load onto the hauling truck, F. Continue steps a through e until all cartridges have been removed. 8, Remove accumulated sediment from the floor of the vault and from the forebay. This can most effectively be accomplished by use of a vacuum truck. 9. Once the sediments are removed, assess -the condition of the vault and the condition of the connectors. The connectors are short sections of 2-inch schedule 40 PVC, or threaded schedule 80 PVCthat should protrude about 1" above the floor of the vault. Lightly wash down the vault interior. a. If desired, apply a light coating of FDA approved silicon lube to the outside of the exposed portion of the connectors. This ensures a watertight connection between the cartridge and the drainage pipe. b. Replace any damaged .connectors. 10. Using the vacuum truck boom, crane, or tripod, lower and install the new cartridges, Once again, take care not to damage connections, 11, Close and fasten the door. 12. Remove safety equipment. 13, Finally, dispose atthe accurnuiated materials in accordance with applicable iegulation5. Make arrangements to return the used emote cartridges to CONTECI I Stormwater Solutions. Related Maintenance Activities - Performed on an as -needed basis StormFilter units are often just one of many structures in a more Tnprehensive stormwater drainage and treatment system. in order for maintenance of the StormFilter to be successful, it is imperative that all other components be properly maintained The maintenance/repair of upstream facilities should be carried out prior to StormFilter maintenance activities. In addition to considering upstream facilities, it is also important to correct any problems identified in the drainage area. Drainage area concerns may include: erosion problems, heavy oil loading, and discharges of inappropriate materials. �'+ RECYCLED ti) PAM Material Disposal The accumulated sediment found in stormwater treatment and conveyance systems must be handled and disposed of in accordance with regulatory protocols. It is possible for sediments to contain measurable concentrations of heavy metals and organic chemicals (such as pesticides and petroleum products). Arcas with the greatest potential for high pollutant loading include industrial areas and heavily traveled roads. Sediments and water must be disposed of in accordance with all applicable waste disposal regulations. When scheduling maintenance, consideration must be made for the disposal of solid and liquid wastes. This typically requires coordination with a local landfill for solid waste disposal. For liquid waste disposal a number of options are available including a municipal vacuum truck decant facility, local waste water treatment plant or on -site treatment and discharge. 1Wy ;i&ft_r^.�f 4;I'S w V.- rl S"UN'hvAiF�c `�-- kCililD?35 800.925.5240 contechstormwater,com Support • Drawings and specifications are available at contechstormwater.com. • Site -specific design support is available from our engineers, @2007 CONTECH Stormwater Solutions CONTECH Construction Products Inc, provides site solutions for the civil engineering industry. CONTECH's portfolio includes bridges, drainage, sanitary sewer, stormwater and earth stabilization products. For information on other CONTECH division 'ferings, visit contech-cpi.com or call 800.338,1122 Nothing in this catalog should be construed as an expressed warranty or an implied warranty of merchantability or fitness for any particular purpose. See the CONTECH standard quotation or acknowledgement for applicable warranties and other terms and conditions of sale. inspectionReport Date: Personnel: Location: System Size; System Type: Vault ❑ Cast -In -Place ❑ Linear Catch Basin ❑ Manhole ❑ Other El Sediment Thickness in Forebay: Date: Sediment Depth on Vault Floor: i� ! Structural Damage: Estimated Flow from Drainage Pipes (if available): f Cartridges Submerged; Yes ❑ No [] If Depth of Standing Water: StormFilter Maintenance Activities (check off if done and give description) ❑ Trash and Debris Removal: Minor Structural Repairs: Q Drainage Area Report f Excessive Oil Loading: Yes ❑ No ❑ Source: Sediment Accumulation on Pavement; Yes ❑ No ❑ Source: Erosion of Landscaped Areas: Yes ❑ No ❑ Source: Items Needing Further Work: Owners Should contact the local public works department and inquire about how the department disposes of their street waste residuals. Other Comments: fi I` If r� I4 II +1 1 Review the condition reports from the previous inspection visits. D' Personnel: _. Location: System Size: _ System Type: vault ❑ Cast -In -Place ❑ List Safety Procedures and Equipment Used: System Observations Months in Service: Oil in Forebay: Sediment Depth in Forebay: Sediment Depth on vault Floor: Structurai Damage: Drainage Area Report Excessive Oil Loading: c - tent Accumulation on Pavement: Ew.ion of Landscaped Areas: rote Report Linear Catch Basin ❑ Manhole ❑ Other ❑ Yes ❑ No ❑ Yes [J- No ❑ Source: Yes [] No ❑ Source: Yes ❑ No ❑ Source: StormFilter Cartridge Replacement Maintenance Activities Remove Trash' and Debris: Yes ❑ No ❑ Details: Replace Cartridges: Yes ❑ No ❑ Details: Sediment Removed: Yes ❑ No ❑ Details: Quantity of Sediment Removed (estimate7): Minor Structural Repairs: Yes ❑ No ❑ Details: Residuals (debris, sediment) Disposal Methods: Notes: