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19-105596
4% RECEIVED. PERMIT APPLICATION CITY OF L 'i ► 019 PERMIT CENTER + 33325 8�h Avenue South +Federal Way, WA 98003-6325 Fe d era I Wayi'fU NOVY L 253-835-2607 + FAX 253-835-2609 + nermilcenleicill oitederahrar.eoln G17Y OF �EDIwRAL WAY' r;QMML'"1;ty DEVELOPMENT PERMIT NUMBER 1 I— _ I J�Q _S —5.1 a _ TARGET DATE SITE ADDRESS SUITE/UNIT R Parcel #292104-9157 (South 359th Street), Federal Way, WA ATION ZONING ASSESSOR'S TAX/PARCEL # $ 51,0je7,000 RS 35.0 2 9 2 1 0 4- 9 1 5 7 TYPE OF PERMIT X BUILDING DO PLUMBING IN MECHANICAL DO DEMOLITION [K ENGINEERING CK FIRE PREVENTION NAME OF PROJECT Sanitary Sewer Pump Station 33B Lakehaven W tw Sewer district's PS 33B ro'ect-inc des the constructs ,n of a 6,432 PROJECT DESCRIPTION Detailed description of work to gallo r minute m submersible sewe p station and de • n • in gga4tation on the same site. T w pump station site Include a electrical be included on this permit only building, et well, vault, and three (3) equipment pads. PRIMARY PHONE City of Federal Way 253-835-2607 PROPERTY OWNER MAILING ADDRESS 33325 8th Avenue South E-MAIL permitcenter@cityoffederalway.com CITY Federal Way STATE WA ZIP 98003-6325 NAME TBD PHONE MAILING ADDRESS E-MAIL CONTRACTOR CITY STATE ZIP FAX WA STATE CONTRACTOR'S LICENSE A EXPIRATION DATE FEDERAL WAY BUSINESS LICENSE �— NAME Lakehaven Water & Sewer District PRIMARY PHONE 253-946-5405 APPLICANT MAILINGADDRESS 31627 1 st Ave S E-MAIL kmiller@lakehaven.org CITY Federal Way STATE WA ZIP 98003 FAX 253-946-9552 PROJECT CONTACT NAME Ken Miller Y PHONE 253 946 5405 MAILING ADDRESS Same as a lieant pp E-MAIL kmiller@lakehaven.org (The individual to receive and respond to all correspondence CITY STATE ZIP FAX 253-946-9552 concerning this application) PROJECT FINANCING NAME N/A ® OWNER -FINANCED When value is $5,000 or more (RCW 19.27.095) MAILING ADDRESS, CITY, STATE, ZIP PHONE I certify under penalty of perjury that I am the property owner or authorized agent of the property owner. I certify that to the best of my knowledge, the irk&rmation submitted in support of this permit application is true and correct I certify that I will comply with all applicable City of Federal Way regulations pertaining to the work authorized by the issuance of a permit. I understand that the issuance of this permit does not remove the owner's responsibility for compliance with local, state, or federal laws regulating construction or environmental laws. I further agree to hold harmless the City of Federal Way as to any claim (including costs, expenses, and attorneys' fees incurred in the investigation and defense of such claim), which may be made by any person, including the undersigned, and,filed against the city, but only where such claim arises out of the reliance of the city, including its officers and employees, upon the accuracy of the Wormation supplied to the city as apart of this application. w- ` SIGNATURE: F--- r DATE PRINT NAME: ��'� \� Q_r Bulletin # 100 —January 29, 2016 Page 1 of 2 k:\Handouts\Pennit Application a� I MECHANICAL PERMIT T$ VALUE OFMECHANICAL WORK 57,000 Indicate how many of each (qpe a Lure to be installed or relocated as art o project. roct. Do not include existfn fixtures to remain. 2 AIR HANDLING UNITS 2 FANS GAS PIPE OUTLETS 3 OTHER (Describe) 1 AIR CONDITIONER ]FIREPLACE INSERTS HOODS (commercial) Unit Heaters BOILERS FURNACES HOT WATER TANKS (cars) COMPRESSORS GAS LOG SETS REFRIGERATION SYST DUCTING GAS PIPING WOODSTOVES VALUE OF PLUMBING WORK PLUMBING PERMIT $ 7,200 Indicate how many of each type offixture to be installed or relocated as part of this project, Do not include edsting flxtures to remain. BATHTUBS (or Tub/shower combo) LAVS (Hand Sink.) 1 TOILETS I WATER PIPING DISHWASHERS RAINWATER SYSTEMS URINALS 4 OTHER (Describe) 2 DRAINS SHOWERS VACUUM BREAKERS Cleanouts DRINKING FOUNTAINS SINKS (Kitchen/utility) 1 WATER HEATERS (Electric) HOSE BIBBS SUMPS WASHING MACHINES 10 TOTAL FIXTURES GENERAL INFORMATION CRITICAL AREAS ON PROPERTY? WATER PURVEYOR SEWER PURVEYOR VALUE OF EXISTING IMPROVEMENTS Yes Lakehaven Water Lakehaven Water & Sewer District & Sewer District $ N/A EXISTING/PREVIOUS USE LOT SIZE (In Square Feet) EXISTING FIRE SPRINKLER SYSTEM? PROPOSED FIRE SUPPRESSION SYSTEM? Vacant/Pump Station Easement = 9,511 SF ❑ Yes X No ❑ Yes D( No (See Site Plan) RESIDENTIAL - NEW OR ADDITION N/A AREA DESCRIPTION (in square feet) EXISTING PROPOSED TOTAL FOR OFFICE USE BASEMENT FIRST FLOOR (or Mobile Home) SECOND FLOOR COVERED ENTRY DECK GARAGE ❑ CARPORT ❑ OTHER (describe) Area Totals EKISTINGPROPOSED TOTAL "NEW HOMES ONLY** ESTIMATED SELLING PRICE $ # OF BEDROOMS COMMERCIAL— NEW/ADDITION AREA DESCRIPTION Area in Square Feet Occupancy Group(s) Construction a # of Stories Additional Information NEW BUILDING 763 F-1 II-B 1 Electrical Building ADDITION N/A COMMERCIAL —REMODEL/TENANT IMPROVEMENTS N/A AREA DESCRIPTION Area in Square Feet Occupancy Group(s) Construction a # of Stories Additional Information TOTAL BUILDING TENANT AREA ONLY PROJECT AREA ONLY Bulletin # 100 — January 29, 2016 Page 2 of 2 k:\Handouts\Permit Application RESUBMITTED Engineers... Working Wonders With Water® January 24, 2020 Cole Elliot City of Federal Way 33325 8th Ave S Federal Way, WA 98003 JAN 2 8 2020 CITY OF FEDERAL WRY COMMUNITY DEVFLbpME 1218 Third Avenue, Suite 1600, Seattle, Washington 98101 P. 206 684 6532 F. 20E96"419 co Subject: File #19-105596-00-CO, Commercial Permit Review No.1 Comment Letter Responses Dear Mr. Elliot: In the building permit review letter dated December 3, 2019, with subject: File #19-105596-00-CO, Commercial Permit Review No. 1, LAKEHAVEN PUMP STATION #33B, 200 South 359th Street, Federal Way, the City provided review comments following their review of our building permit application. These comments have been addressed and are listed below, along with their corresponding responses. The proposed pump station is a relocated essential public facility located on the City of Federal Way Open Space property. The existing pump station at the project site must be replaced to prevent sanitary sewer overflows that could occur as wastewater flows rise and the station's capacity is exceeded. Our goal is to provide a more efficient sewer pump station to service the existing and proposed developed areas while limiting the impacts to the adjacent sensitive areas (e.g. wetlands and creek). The facility's close proximity to the road will also provide a more visible and secure site. The properties to the south and north of S 359th Street surrounding the existing and proposed pump station is designated Open Space and will not be developed. The comments below were reviewed with City staff at a meeting on Tuesday, January 71h, at Federal Way City Hall. The below responses reflect our understanding of the agreed upon solutions to the received comments. We appreciate the City taking time to meet with us and look forward to continuing to work with you on this Project. Public Works— Develol2ment Services Division Technical Information Report 1. Section 2.1.8 Core Requirement #8: Water Quality— a statement that Water Quality is not required is only true if the design meets all of the requirements of King County Surface Water Design Manual (KCSWDM) Sections 1.2.9.2.1 and C.2.1.1. Response: Acknowledged. Our project meets the requirements of Sections 1.2.9.2.1 and C.2.1.1 for full dispersion and is therefore exempt from Core Requirement #8 (less than 5,000 square feet of new plus replaced PGIS that is not fully dispersed will be created AND less than 3/4 acre of new PGPS that is notfully dispersed will be added). As discussed with the City, we will also utilize a Contech Stormfilter for treatment of all runoff from the paved area prior to dispersal. 2. Section 2.1.9 Core Requirement #9 Flow Control BMP —references KCSWDM 1.2.9.2.1 but this section states that the feasibility and applicability of full dispersion must meet C.2.1. Section C.2.1.1 Project No 10581A.10 I 'WAT E R Lakehaven_Building Perm it_ResubmittaI Letter.docx OUR FOCUS OUR BUSINESS OUR PASSION O tJ1 Ci7 t® M Cole Elliot City of Federal Way January 24, 2020 Page 2 states that the total of impervious plus non-native pervious cannot exceed 35-percent of the site. How does this design meet this requirement? Response: Per Sheet C04, the total impervious plus non-native pervious area of the site is 7,519 sf. This is approximatly 79% of the total lift station site area (9,500 sf). The "site area", however, is an easement on an existing 1,837,360 sf parcel (Parcel #2921049157) that is owned by the City of Federal Way and will be preserved as a natural area. Per prior discussions with the City of Federal Way, the easement itself was minimized to limit effects to this natural area. With this in mind, the toytaI imperviiqus plus non -native ++pp�ervious area of the site is approximate) 0.4% of the site. r � �L[ [ �'"[ r1 � 11Yr+ S ►'—C @ AS r-a+ �S L A 4 �i { � (Z)" y� � � tng --3, Section 2.2.3 Basin Plans —must acknowledge review and compliance with the 1991 King County Surface Water Management Executive Proposed Basin Plan Hylebos Creek and Lower Puget Sound. Response: TIR updated to acknowledge review of the referenced basin plan (see Section 2.3.3 of the TIR). 4. Section 3 Offsite Analysis — based upon the information presented in this TIR the City does not have sufficient data to concur that "the project will not have an adverse impact on downstream and/or upstream drainage." Response: The downstream ow path of over 100 feet of native vegetation for the site will be left unaffected and our stormwater calculations show that there will be no increase in runoff peak flows or volumes. Upstream flows consist only of roadway runoff. These minor flows will be infiltrated in the roadside landscaped area or conveyed to the energy dissipation structure for dispersion. We do n t anticipat any adverse impact on downstream or upstream drainage. ya{,.r � +cy.s �4CS No"i 1n�ae i o� .nrh rvkA, vt �lcr.��,� t) -i), i�hR,l'2�vrg, 5. Page 9, Table 4.3 Proposed Developed Site Runoff Areas —The total area of Porous Asphalt, Structures and Retaining Walls equals 7,519 sq. ft. of a 9,500 sq. ft. site. This seems to indicate that 79-percent of the site is impacted which exceeds the requirements of C.2.1.1 as stated above. Response: Per Sheet C04, the total impervious plus non-native pervious area of the site is 7,519 sf, This is approximatly 79% of the total lift station site area (9,500 sf). The "site area", however, is an easement on an existing 1,837,360 sf parcel (Parcel #2921049157) that is owned by the City of Federal Way and will be preserved as a natural area. Per prior discussions with the City of Federal Way, the easement itself was minimized to limit effects to this natural area. With this in mind, the total impervious plus non-native pervious area of the site is approximately 0.4% of the site. 6. Section 4.2, Page 10 indicates the flow path is between 17 and 3.5 feet but in accordance with C.2.4.5 the minimum flow path is 10-feet and preferred is 25 feet. In addition, per C.2.4.1.2.d a wetland is identified drainage feature which must meet the minimum separation requirements. Response: Please refer to the end of Section 4.2. Exemptions to various SWDM parameters are required forthis site, including the requirements referenced here. These exemptions were previously discussed with the City. Without these exemptions and/or the granting of a larger easement by the City, the requirements of the manual cannot be met at the site. Drainage will sheet flow from the existing road and onsite dispersion, maintaining the hydrology of the buffer/wetland. carollo.com Cole Elliot City of Federal Way January 24, 2020 Page 3 7. Section 4.2, per the KCSWDM the length of dispersion trench requires the use of V-notch weir for equal dispersion across the trench. The information provided at the bottom of page 10 fails to include a discussion on the V-notch weir. Response: A V-notch weir is included with the design (see Sheet C06). The SWDM's standard detail for a dispersion trench with a V-notch weir was utilized. A discussion has now been added in Section 4.2 of the TIR to convey this. 8. Section 4.2, Paragraph 1 on page 13 states the conservative infiltration rate of 0.01 inches per hour has been used for the pervious surface but the Geotechnical Report indicated the native soil's infiltration rate is 0.0025 inches per hour. Please clarify where the un-infiltrated storm flow will be stored. Response: Section 4.2, Paragraph 1 on page 13 states that a conservative infiltration rate of 0.01 inches per hour has been used for the com acted site back ill. The top 7-feet of the existing soils at the site will be removed and replaced with quarry spalls perthe geotechnical report and drawings (Sheet C01). The entire site will then be raised 1 to 6 feet with a structural backfill material, from the existing grade to the proposed grade. The TIR has been updated to explain this. The model does not utilize this material for storage or calculate its capacity to store runoff; it only considers its ability to slowly infiltrate water stored in the porous pavement section. Water that does infiltrate through this material will slowly make its way to the native soils for infiltration or to the retaining wall underdrain for dispersion. While all water that initially infiltrates through the porous pavement may not infiltrate to the native soil, its travel time will significantly increase (i.e. site peak flow will significantly decrease). This is what is represented in our calculations. References to the native infiltration rate and hydraulic conductivity rate have been removed from the TIR since we are not considering them for this Project. The storage represented in the calculations is provided within the porous pavement section only. The infiltration rate for flows through the porous pavement section to the compacted site backfill is calculated based on the input pour space values for the various materials within the section (see Appendix C, page 7). We have increased the permeable ballast layerthickness to 24-inches in order to provide further storage at the site. 9. Section 4.3 Performance Standards statement is only true if sufficient storage is available in the proposed 18-inches of permeable ballast to provide storage for the difference in the infiltration rates of the native soil (0.0025 in/hr) and the proposed design infiltration rate (0.01 in/hr) for the 2-, 5-, and 10-year storms. Response: Section 4.2, Paragraph 1 on page 13 states that a conservative infiltration rate of 0.01 inches per hour has been used for the compacted site bac idf. The top 7-feet of the existing soils at the site will be removed and replaced with quarry spalls per the geotechnical report and drawings (Sheet C01). The entire site will then be raised 1 to 6 feet with a structural backfill material, from the existing grade to the proposed grade. The TIR has been updated to explain this. The model does not utilize this material for storage or calculate its capacity to store runoff; it only considers its ability to slowly infiltrate water stored in the porous pavement section. Water that does infiltrate through this material will slowly make its way to the native soils for infiltration orto the retaining wall underdrain carollo.com Cole Elliot City of Federal Way January 24, 2020 Page 4 for dispersion. While all water that initially infiltrates through the porous pavement may not infiltrate to the native soil, its travel time will significantly increase (i.e. site peak flow will significantly decrease). This is what is represented in our calculations. References to the native infiltration rate and hydraulic conductivity rate have been removed from the TIR since we are not considering them for this Project. The storage represented in the calculations is provided within the porous pavement section only. The infiltration rate for flows through the porous pavement section to the compacted site backfill is calculated based on the input pour space values for the various materials within the section (see Appendix C, page 7). We have increased the permeable ballast layerthicknessto 24-inches in order to provide further storage at the site. 10. Section 4.4 Flow Control the results of the WWHM2012 model results are only true if the site can actually infiltrate 20.378 ac-ft as assumed. Response: Section 4.2, Paragraph 1 on page 13 states that a conservative infiltration rate of 0.01 inches per hour has been used for the!o acted site backfill. The top 7-feet of the existing soils at the site will be removed and replaced with quarry spalls per the geotechnical report and drawings (Sheet C01). The entire site will then be raised 1 to 6 feet with a structural backfill material, from the existing grade to the proposed grade. The TIR has been updated to explain this. The model does not utilize this material for storage or calculate its capacity to store runoff; it only considers its ability to slowly infiltrate water stored in the porous pavement section. Water that does infiltrate through this material will slowly make its way to the native soils for infiltration or to the retaining wall underdrain for dispersion. While all water that initially infiltrates through the porous pavement may not infiltrate to the native soil, its travel time will significantly increase (i.e. site peak flow will significantly decrease). This is what is represented in our calculations. References to the native infiltration rate and hydraulic conductivity rate have been removed from the TIR since we are not considering them forthis Project. The storage represented in the calculations is provided within the porous pavement section only. The infiltration rate forflows through the porous pavement section to the compacted site backfill is calculated based on the input pour space values forthe various materials within the section (see Appendix C, page 7). We have increased the permeable ballast layerthickness to 24-inches in order to provide further storage at the site. 11. Section 4.5 Water Quality makes a broad -brush statement about some studies showing that porous asphalt provides some reduction of pollutants but fails to meet the requirements for water quality treatment for the site. Response: Section 4.5 states "Efforts to quantify or prove pollutant reduction are not included in the scope of this project report." There was no intent to prove pollutant reduction, this was simply to point out that there are potential benefits in regards to pollutant removal. This section has been revised to only state "Runoff from the site will be fully dispersed and is therefore not subject to the water quality facility requirements of the SWDM." carollo.com Cole Elliot City of Federal Way January 24, 2020 Page 5 12. Section 8, #9 Flow Control states, "...the existing soils are porous enough that elevated storm flows during construction are not anticipated." Please explain the logic behind this statement, based upon the geotechnical report this statement appears false. Response: Acknowledged. This statement was mistakenly left in the document and has been removed. The project area is deemed small enough that elevated storm flows during construction are not anticipated. Onsite depressions will be constructed as necessary during construction to prevent overloading of the perimeter protection and sediment -laden water from leaving the site. In the event storm flows exceeded the capacity of the onsite depressions, the detained storm water will be pumped to settling tanks then discharged via the proposed temporary discharge structure. 13. Page 3 of the WWHM2012 Project Report please clarify how the pre-existing condition has 0.031 acre of roads? Development Services would expect the Pre-existing condition to assume the entire 0.218 acre site in forested, flat slope. Response: The model results show the existing conditions. The model has now been updated to reflect the pre-existing (i.e. historical site conditions). 14. Page 7 Mitigated Routing again how can you justify using an infiltration rate of 0.01 in/hr when the native soils is 0.0025 inches per hour? Additionally, it appears the model assumes 94.72 percent infiltrated and a total volume infiltrated of 20.378 ac-ft. Please justify. Response: Section 4.2, Paragraph 1 on page 13 states that a conservative infiltration rate of 0.01 inches per hour has been used for the compacted site back 0. The top 7-feet of the existing soils at the site will be removed and replaced with quarry spalls per the geotechnical report and drawings (Sheet C01). The entire site will then be raised 1 to 6 feet with a structural backfill material, from the existing grade to the proposed grade. The TIR has been updated to explain this. The model does not utilize this material for storage or calculate its capacity to store runoff; it only considers its abilityto slowly infiltrate water stored in the porous pavement section. Water that does infiltrate through this material will slowly make its way to the native soils for infiltration orto the retaining wall underdrain for dispersion. While all waterthat initially infiltrates through the porous pavement may not infiltrate to the native soil, its travel time will significantly increase (i.e. site peak flow will significantly decrease). This is what is represented in our calculations. References to the native infiltration rate and hydraulic conductivity rate have been removed from the TIR since we are not considering them for this Project. The storage represented in the calculations is provided within the porous pavement section only. The infiltration rate for flows through the porous pavement section to the compacted site backfill is calculated based on the input pour space values for the various materials within the section (see Appendix C, page 7). We have increased the permeable ballast layerthickness to 24-inches in order to provide further storage at the site. 15. Page 17 LID Report includes statement that 19.58 ac-ft of storm water are infiltrated on -site. Provide justification. Response: This is a calulation performed by the WWHM model. This volume represents the volume carollo.com Cole Elliot City of Federal Way January 24, 2020 Page 6 of water infiltrated to the compacted site backfill, as described in the response to comment #8 above. With the changes to the porous pavement design previously mentioned this value is now 20.648 ac-ft. Plan Sheets General 16. Add the City Approval Block to all sheets containing information on right-of-way and storm improvements. City permit number is 19-105596-CO. Response: The City Approval Block has now been added to all sheets. Sheet C01 17. Add cut and fill quantities to the plan set. Response: Cut and fill quantities have now been added to Sheet C01. 18. Roadway monuments for PC, and PT will need to be installed along S 3591h Street. Submission of the Standard Drawing 3-37 will be required. Response: We walked S 359th Street and could not find any existing roadway monuments. Per discussions with the City, no new monuments will be installed. If buried monuments are discovered during construction they will be brought to grade. If monuments are disturbed during construction they will be replaced in -kind per WAC requirements. Sheet CO2 19. Street improvements (curb gutter, sidewalk, storm and street lights) are required for Commercial Improvement permits. In accordance with FWRC 19.135.030, you may apply for a Street Modification. The modification request can only be reviewed and granted underthe four reasons indicated on the attached hand-out. The fee for 2019 is $334 but will increase after January 1, 2020. Response: This is a relocated essential public facility. There are no habitable structures and the site will only be visited approximately once a week. During the preapplication conference meeting there was no requirement for frontage improvements due to the proposed use as pump station and the Open Space designation of the surrounding property. Additionally, any improvements would not be harmonious with the existing street that currently has no sidewalk, curb, storm system, or other improvements and is not in or adjacent to any residential areas. Per discussions with the City, no street improvements will be required for this Project. 20. Overlay/replacement may need to be extended west of construction site depending upon the condition of the roadway when compared is made of pre- and post -construction. Response: Acknowledged. We have added a pavement overlay to extend from the limits of the carollo.com Cole Elliot City of Federal Way January 24, 2020 Page 7 replaced pavement to SR 99. A pre -construction inspection and condition documentation will be performed so that, if needed, pavement damaged during construction beyond the limits of the Project to the east can be identified and repaired. Sheet C04 21. Per KCSWDM C.2.4.4 #2 a 25-foot minimum flow path is required before the wetland (KCSWDM 1.2.3.2.C.3.d). Response: See response to comment #6 above. 22. Per KCSWDM C.2.4.1 #2b the flow path must be on -site or in an off -site tract or easement reserved for dispersion. Response: See response to comment #6 above. Sheet C06 csrc 23. Detail 7, per Development Standards Section 3.2.18 all backfill within the right-of-way shall be @9BE. Modify accordingly. Response: As discussed with the City, gravel borrow will be used for backfill of longitudinal trench excavations. The pipe would be bedded with crushed surfacing. The short sections of perpendicular piping at the site frontage will utilize CSTC for backfill as requested. Please contact me at 206-684-6532 with any questions. Sincerely, CAROLLO ENGINEERS, INC. Brian Sliger, P.E. Engineer cc:Ken Miller & Molly Du — Lakehaven Water and Sewer District carollo.com 0 fo$ Lakehaven Water & Sewer District Sanitary Sewer Pump Station 33B Site Plan Permit Review TECHNICAL INFORMATION REPORT FINAL (REVISED) 1 January 2020 RESUBMITTED JAN 2 8 2020 CITY OF FEDERAL WAY COMMUNfiY DEVEL(pk[W 4C Cj*rAM #lam® Lakehaven WATER &SEWER DISTRICT Lakehaven Water & Sewer District Sanitary Sewer Pump Station 33B Site Plan Permit Review TECHNICAL INFORMATION REPORT FINAL (REVISED) 1 January 2020 TIR I PUMP STATION 33B I LAKEHAVEN WATER & SEWER DISTRICT Contents Section 1 1 Project Overview 1 1.1 Site Location 1 1.2 Drainage Basin & Site Characteristics 2 1.3 Soils 4 Section 2 5 Conditions and Requirements Summary 5 2.1 Core Requirements 5 2.1.1 Core Requirement #1: Discharge at the Natural Location 5 2.1.2 Core Requirement #2: Offsite Analysis 5 2.1.3 Core Requirement #3: Flow Control 5 2.1.4 Core Requirement #4: Conveyance System 5 2.1.5 Core Requirements #5: Erosion and Sediment Control (ESC) 5 2.1.6 Core Requirement #6: Maintenance. and Operations 5 2.1.7 Core Requirement #7: Financial Guarantees and Liability 6 2.1.8 Core Requirement #8: Water Quality 6 2.1.9 Core Requirement #9: Flow Control BMP 6 2.2 Special Requirement #1: Other Adopted Area -Specific 6 2.2.1 Critical Drainage Areas 6 2.2.2 Master Drainage Plan 6 2.2.3 Basin Plans 6 2.2.4 Salmon Conservation Plans (SCPs) 6 2.2.5 Stormwater Compliance Plans (SWCPs) 6 2.2.6 Lake Management Plans (LMPs) 7 2.2.7 Flood Hazard Reduction Plan Updates (FHRPs) 7 2.2.8 Shared Facility Drainage Plans (SFDPs) 7 2.3 Special Requirement #2: Floodplain / Floodway Delineation 7 2.4 Special Requirement #3: Flood Protection Facilities 7 2.5 Special Requirement #4: Source Controls 7 2.6 Special Requirement #5: Oil Control 7 C FINAL I JANUARY 202011 p\-::1ACaFDIIC/DoCumentstChent�/bVA/Lakchaven/10581A10/Delive,aoleslTl Rl ask'_30_TIR_Lal_chaven P533B doer LAKEHAVEN WATER & SEWER DISTRICT I PUMP STATION 33B I TIR Section 3 7 Offsite Analysis 7 Section 4 8 Flow Control and Water Quality Facilities 8 4.1 Pre -Existing Site Hydrology 8 4.2 Developed Site Hydrology 9 4.3 Performance Standards 13 4.4 Flow Control 14 4.5 Water Quality 14 Conveyance system Analysis and Design 14 Section 5 14 Special Reports and Studies 14 Section 6 15 Other Permits 15 Section 7 15 Erosion and Sedimentation Control Analysis and Design 15 Section 8 17 Bond Quantities, Facility Summary, and Declaration of Covenant 17 8.1 Bond Quantities 17 8.2 Facility Summaries 17 8.3 Declaration of Covenant 17 Section 9 17 Operations and Maintentance Manual 17 Appendices AppendixA Technical Information Report Checklist Appendix B Draft Geotechnical Report Appendix C WWHM2012 Results Appendix D Erosion and Sediment Control (ESC) Plan Appendix E Declaration of Covenant Appendix F Operations and Maintenance (O&M) Manual ii I JANUARY2020 I FINAL C PRELIMINARY TIR I PUMP STATION 33B I LAKEHAVEN WATER & SEWER DISTRICT Appendix G Site Drainage Plan Appendix H Critical Areas Report Tables Table 4.1 Existing Site Runoff Areas Table 4.2 Existing Site Flow Frequency Return Periods Table 4.3 Proposed Developed Site Runoff Areas Table 4.4 Proposed Site Flow Frequency Return Periods Figures Figure 1.1 Site Location Map Figure 1.2 Existing Site Land Cover Figure 1.3 Site Drainage Pattern Map Figure 4.1 Proposed Site Land Cover Figure 4.2 Dispersion Trench Flow Path Figure 4.3 Proposed Site Drainage System Figure 4.4 Proposed Porous Asphalt Cross Section 8 8 9 13 2 3 4 10 11 12 13 C ^" FINAL I JANUARY 2020 1 iii TIR I PUMP STATION 33B I LAKEHAVEN WATER & SEWER DISTRICT Abbreviations AC acre BMP best management practices CAO Critical Area Ordinance cfs cubic feet per second District Lakehaven Water and Sewer District ESC Erosion and Sedimentation Control FHRP Flood Hazard Reduction Plan gpm gallons per minute KCC King County Code KCSWDM King County Surface Water Design Manual LID Low Impact Development LF linear feet LMP Lake Management Plan NPDES National Pollutant Discharge Elimination System NPGIS Non -Pollutant Generating Impervious Surface NPGPS Non -Pollutant Generating Pervious Surface NRCS Natural Resources Conservation Service OHWM ordinary high water mark PS 33B Pump Station 33B PVC polyvinyl chloride RMC Redondo Milton Channel ROW right-of-way SCP Salmon Conservation Plan sf square feet SFDP Shared Facility Drainage Plan SWCP Stormwater Compliance Plan SWDM Washington Surface Water Design Manual TIR Technical Information Report WWHM2012 Western Washington Hydrology Model 2012 C FINAL I JANUARY 2020 I v TIR I PUMP STATION 33B I LAKEHAVEN WATER & SEWER DISTRICT Section 1 PROJECT OVERVIEW Lakehaven Water and Sewer District (District)'s Sanitary Sewer Pump Station 33B (PS 3313) project includes the construction of a 6,432 gallon per minute (gpm) submersible sewer pump station with an approximate 14-foot by 18-foot rectangular wet well on an existing easement, plus the installation of 100 linear feet (LF) of 10/14-inch force main and 385 LF of 48-inch diameter storage pipe in the right-of-way (ROW). The pump station will be constructed adjacent to existing wetlands and the site will be regraded flat, requiring a retaining wall. This project will meet all applicable drainage standards, codes, and requirements as set forth by the 2016 King County Washington Surface Water Design Manual (SWDM) and the City of Federal Way's January 8, 2017 Addendum to the SWDM. A copy of the City of Federal Way's Technical Information Report (TIR) Checklist is provided in Appendix A for reference. All stormwater runoff from the site will be dispersed via a dispersion trench and is therefore not subject to the flow control and water quality facility requirements of the SWDM. In an effort to provide a greater factor of safety against any potential adverse impacts to the proposed site and implement Low Impact Development (LID) techniques, the project will utilize porous asphalt to reduce peak flows and potentially provide additional water quality benefits. Catch basins will be utilized to collect porous asphalt overflow for conveyance to the proposed dispersion trench. See Sections 4 and 5 for additional information regarding the proposed drainage system. 1.1 Site Location The project site is located on South 359th Street in the City of Federal Way, Washington. The site is on King County Parcel #2921049157, which is owned by the City of Federal Way. The project will be constructed within an existing easement granted to the District by the City of Federal Way. The approximate project limits are shown in Figure 1.1 below. C C+�r���'�" FINAL I JANUARY 2020 I 1 LAKEHAVEN WATER & SEWER DISTRICT I PUMP STATION 33B I TIR Figure 1.1 Site Location Map 1.2 Drainage Basin & Site Characteristics The existing project site is approximately 0.218 acres (9,500 square feet [sf7) and contained within a single drainage basin. The site is predominately wooded/vegetated (approximately 8,154 sf) and includes an existing asphalt access road to the District's existing pump station (approximately 1,346 sf) along its west boundary. Pre-existing conditions are assumed to have been all wooded/vegetated (9,500 sf). Existing sheet flow runoff from the access road and South 359th Street is dispersed to the adjacent vegetated areas. Runoff not infiltrated or dispersed onsite sheet flows in a south-east direction to Hylebos Creek. Figure 1.2 below illustrates existing site land cover areas and Figure 1.3 illustrates existing and proposed drainage patterns. The site's proposed drainage is further described in Section 4.2. 2 1 JANUARY 2020 1 FINAL C Carte"^ TIR I PUMP STATION 33B I LAKEHAVEN WATER & SEWER DISTRICT I i ! I I + I I i ! I I I ! I I I EX I5' SEWER EASEMENT ! I I Pre -Existing Site Area Wooded/Vegetated 9,500 sf Figure 1.2 Pre -Existing Site Land Cover C C.�i`�'���' FINAL JANUARY2020 13 LAKEHAVEN WATER & SEWER DISTRICT I PUMP STATION 33B I TIR Figure 1.3 Site Drainage Pattern Map 1.3 Soils In general, geotechnical explorations encountered approximately 0 to 7 feet of very soft silt deposit that underlies the site. This soft layer is underlain by dense to very dense silty sand or hard silt to approximately 37 feet. At a depth of 37 feet, sand and gravel with an unusually high piezometric head is present. An artesian groundwater aquifer known as the Redondo Milton Channel (RMC) was encountered approximately 37 feet below the ground surface. The aquifer has an extremely high permeability and storage capacity. The piezometric head of the RMC water table is currently 19 feet above the existing ground surface. The groundwater pressure within the top 30 feet of the ground surface has a piezometric head of 0 to 4 feet above the existing ground surface. Hydraulic conductivity testing performed as part of site geotechnical investigations found rates between 0.005 and 0.030 feet per day. These low hydraulic conductivity rates are due to the high moisture content of the soils, likely a result of the site's proximity to the adjacent wetland. A draft copy of the project geotechnical report, including soil maps, is included for reference in Appendix B. 4 1 JANUARY 2020 1 FINAL C Ca0wN8^ TIR I PUMP STATION 33B I LAKEHAVEN WATER & SEWER DISTRICT Section 2 CONDITIONS AND REQUIREMENTS SUMMARY The proposed project is classified as requiring "Full Drainage Review" perthe SWDM. Therefore, all nine core requirements and five special requirements will be addressed per Section 1.1 of the SWDM. 2.1 Core Requirements 2.1.1 Core Requirement #1: Discharge at the Natural Location According to Core Requirement #1 (Discharge at the natural location), where no conveyance system exists at the abutting downstream property line and the natural (existing) discharge is unconcentrated, any runoff concentrated by the proposed project must be discharged as follows: IF the 100-year peak discharge is less than or equal to 0.5 cubic feet per second (cfs) under existing conditions and will remain less than or equal to 0.5 cfs under developed conditions, THEN the concentrated runoff may be discharged through a dispersal trench or other dispersal system provided the applicant can demonstrate that there will be no significant adverse impact to downhill properties or drainage systems. Modeling performed for the existing and proposed site conditions shows these flow rates are obtained and Core Requirement #1 is met. See Appendix C for modeling results. 2.1.2 Core Requirement #2: Offsite Analysis This core requirement is addressed in Section 3 of this report. This project is exempt from the offsite analysis requirement. VoT Tr-�„ L�,Q �, y q,,� CAO �r"7i�coec v�� Fpt.s kcSWt0A 1,z,z o0 2.1.3 Core Requirement #3: low Control Runoff from the site will be fully dispersed and is therefore not subject to the flow control facility requirement of the SWDM. See Section 4.4 for further discussion on proposed flow control. 2.1.4 Core Requirement #4: Conveyance System Site runoff will be fully dispersed. Conveyance to the dispersion trench will be oversized as described in Section 5.0 of this report. 2.1.5 Core Requirements #5: Erosion and Sediment Control (ESC) The proposed erosion and sedimentation control best management practices (BMPs) have been designed to meet the requirements and design standards in Appendix D of the 2016 King County Surface Water Design Manual (KCSWDM). See Section 8 - ESC Analysis and Design. The project ESC plan is provided as Appendix D of this report. 2.1.6 Core Requirement #6: Maintenance and Operations The District will be responsible for maintenance of the onsite pervious pavement, catch basins, storm drains, and the dispersion trench system, as discussed further in Section 10.0 of this report. An operations and maintenance manual is provided in Appendix F of this report. The C FINAL I JANUARY 2020 15 LAKEHAVEN WATER & SEWER DISTRICT I PUMP STATION 33B I TIR manual includes procedures for cleanup of drips and spills on the pervious pavement to prevent pollutants from running offsite. 2.1.7 Core Requirement #7: Financial Guarantees and Liability A bond quantities worksheet is not required as there are no proposed improvements to City of Federal Way facilities within the ROW, and minimal onsite drainage facilities are being constructed. Roadway work will consist of restoration only. 2.1.8 Core Requirement #8: Water Quality Runoff from the site will be fully dispersed apd is therefore not subject to the water quality facility requirements of the SWDM. )�eS i� t, dok% ncAwA%== R t~ Ll a� 4 k.r4fl- V47 ax 2.1.9 Core Requirement #9: Flow Control BMP • Z • g -- I - v d C• Z• . j ��' `-�" `� `"S ��4'� �, IJQ The proposed site falls under the Small Lot BMP Requirements of the SWDM (see Section 1.2.9.2.1 of the SWDM). Runoff from the site will be fully dispersed and therefore meets �� t the requirements for small lots (option one in Section 1.2.9.2.1 of the SWDM). See Section 4 of this documr�ent for further discuss' io the pr9poseg dipersiorl technique f f.�osr pe4- kcS,4.b r,ti-��.r,, aa,)- C]I•1; I. 2.2 Special Requirement #I.Other Adopted Area -Specific 2.2.1 Critical Drainage Areas Per King County's iMAP of the project area, the Critical Area Ordinance (CAO) basin condition is low and it is not in a landslide or aquifer recharge area. 2.2.2 Master Drainage Plan Not applicable. 2.2.3 Basin Plans The Project site is within the West Branch Hylebos Creek Sub -Basin and is included in the 1991 King County Surface Water. Management Executive Proposed Basin Plan Hylebos for Creek and Lower Puget Sound. Per this basin plan, the project site is within a Locally Signifcant Resource Area (LSRA) and adjacent to Problem Area 2B. Problem Area 2B is described as a road washout event at the Hylebos Creek crossing with 3591h St. Per Table 2.3.2 of the document, this issue will be remedied with an enlarged culvert and overflow structure. This Project will not affect this Problem area. All requirements of the Basin Plan related to the Project site are met, with the following exceptions: 1. The required stream buffer of 150 feet from the OHWM is not met, as further explained in this document and justified in the Critical Areas Report (Appendix H). 2. The required wetland buffer of 100 feet from the OHWM is not met, as further explained in this document and justified in the Critical Areas Report (Appendix H). 2.2.4 Salmon Conservation Plans (SCPs) Not applicable. 2.2.5 Stormwater Compliance Plans (SWCPs) Not applicable. 6 1 JANUARY 2020 1 FINAL C Carw�r^ TIR I PUMP STATION 33B I LAKEHAVEN WATER & SEWER DISTRICT 2.2.6 Lake Management Plans (LMPs) Not applicable. 2.2.7 Flood Hazard Reduction Plan Updates (FHRPs) This project is not within a floodplain and is not within an area with an applicable Flood Hazard Reduction Plan. Therefore, additional requirements from a Flood Hazard Reduction Plan do not apply. 2.2.8 Shared Facility Drainage Plans (SFDPs) Not applicable. 2.3 Special Requirement #2: Floodplain / Floodway Delineation This project is not located within the 100-yearfloodplain. 2.4 Special Requirement #3: Flood Protection Facilities As this project is not located within a 100-year flood plain there are no levees, revetments, or berms within the project. 2.5 Special Requirement #4: Source Controls These requirements are not applicable as the project is not a commercial, industrial or multi -family development. 2.6 Special Requirement #5: Oil Control This requirement does not apply because the project is not a commercial or industrial development nor is it expected to have more than 1S,000 vehicles per day. Section 3 OFFSITE ANALYSIS The proposed project site receives little to no run-on from adjacent properties and will have minimal runoff once developed. There is no existing stormwater infrastructure in the site vicinity and runoff from adjacent impervious surfaces is managed by dispersal to adjacent vegetated areas. Section 1.2.2 of the SWDM identifies exemptions to the requirement for performing an offsite analysis, waiving the requirement if one of the following is true: 1. The City determines there is sufficient information for them to conclude that the project will not have a significant adverse impact on the downstream and/or upstream drainage system, OR 2. The project adds less than 2,000 sf of new impervious surface, AND less than 3/4 acre of new pervious surface, AND does not construct or modify a drainage pipe/ditch that is 12 inches or more in size/depth orthat 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 landslide, steep slope, or erosion hazard area as defined in King County Code (KCC) 21A.06, OR 3. The project does not change the rate, volume, duration, or location of discharges to and from the project site (e.g., where existing impervious surface is replaced with other C FINAL I JANUARY 2020 17 LAKEHAVEN WATER & SEWER DISTRICT I PUMP STATION 33B I TIR impervious surface having similar runoff -generating characteristics, or where pipe/ditch modifications do not change existing discharge characteristics). Forth is project, the amount of new impervious surface being added exceeds 2,000 (due to porous asphalt being defined as an impervious surface for the sake of this threshold determination). However, due to the small site area, proximity to the downstream discharge point, and considering that all runoff will be fully dispersed, the project is not anticipated to have a significant adverse impact on the downstream and/or upstream drainage system, making numbers 1(upon City concurrence) and 3 above true. For these reasons, this project is exempt from SWDM Core Requirement #2. Section 4 FLOW CONTROL AND WATER QUALITY FACILITIES 4.1 Pre -Existing Site Hydrology A forested, moderately sloped (-7 percent), Natural Resources Conservation Service (NRCS) hydrologic soil group D was assumed for the existing site's vegetated area. While the soils encountered onsite may lend themselves to higher infiltration rates under dry conditions, hydraulic conductivity and soil moisture testing (water table at ground surface) has shown that the existing site soils hydrological function is most aligned with soil group D. Site runoff areas for the existing site are presented in Table 4.1 below. Table 4.1 Existing Site Runoff Areas Feature Area (sf/acres) Wooded/Vegetated (7% Slope)(') 9,500/0.218 Total Existing Site Area 9,500/0.218 Notes: (1) Pervious, non -pollutant genereting pervious surface (NPGPS). The Western Washington hydrology model 2012 (WWHM2012) was utilized to estimate the existing site's runoff flow rates. Flow frequency return period can be found in Table 4.2 below while full model results can be found in Appendix C. Table 4.2 Pre -Existing Site Flow Frequency Return Periods Return Period l Flow (cfs) 1 1 5 year 0.0346 10 year 0.0476 25 year 0.0628 50 year 0.0727 100 year 0.0813 8 1 JANUARY 2020 1 FINAL `+arw11VI.. p TIR I PUMP STATION 33B I LAKEHAVEN WATER & SEWER DISTRICT 4.2 Developed Site Hydrology The developed site will consist of porous pavement, a retaining wall, above ground structures, buried structures (with concrete/impervious lids), and landscaped/retained vegetated areas. Table 4.3 lists the proposed site's runoff area/land coverage. Figure 4.1 illustrates the proposed site and these runoff areas. Table 4.3 Proposed Developed Site Runoff Areas Feature Area (sf/acre) Porous Asphalt(:) _ 4,050/0.093 Structures (Impervious) 2,801/0.064 Retaining Wall(Z) 668/0.015 Landscaping/Vegetated 1,981/0.046 Total Developed Site Area 9,500/0.218 Notes: (1) Pervious, NPGPS (low traffic count). (2) Impervious, NPGIS. (3) Pervious, NPGPS. C FINAL I JANUARY 2020 19 LAKEHAVEN WATER & SEWER DISTRICT I PUMP STATION 33B I TIR Figure 4.1 Proposed Site Land Cover The proposed site drainage system will consist of porous asphalt, catch basins to collect porous asphalt overflow, storm drain piping, and a 38-foot long dispersion trench. Dispersion requirements for basic dispersion via gravel -filled trench were adhered to, including the use of a v-notch weir for even dispersion (See Appendix G for the Site Drainage Plan that includes the SWDM's standard detail for dispersion trenches and v-notch weirs). The dispersion trench's vegetated flow path includes between 17 and 3.5 feet of vegetated area before reaching the wetland buffer boundary and over 100 feet of vegetated area before reaching Hylebos Creek's ordinary high water mark (OHWM). Figure 4.2 illustrates the dispersion trench flow path. 10 1 JANUARY2020 I FINAL 4c J• TIR I PUMP STATION 33B I LAKEHAVEN WATER & SEWER DISTRICT 38' D1SP1 TRENCH Figure 4.2 (TYP) /71 % HYLEBOS CREEK 4 OHWM (TYP) J 41 m \ o N n o t2 a APPROXIMATE FLOW PATH ARROWS (TYP) � IW 1" 0 WETLAREA Dispersion Trench Flow Path Section C.2.4.4 of the SWDM dictates that a ratio of 10 feet of trench per 700 square feet of impervious surface (or 5,000 square feet of non-native pervious surface) should be used to size the dispersion trench. This equates to approximately 40 feet of trench for the 2,801 square feet of impervious area routed to trench (structures) and an additional 8 feet of trench for the 4,050square feet of non-native pervious surface (porous asphalt). The impervious retaining wall surfaces disperse via sheet flow and are a NPGIS. Total required trench length is therefore 48 feet. Due to site constraints, the following project exemptions from the requirements of the SWDM are required: 1. Section C.1.2.3.2.C.3.d: Required flow path length is not provided before reaching wetland, however, dispersion trench location mimics natural drainage and is placed in the best possible location. 2. Section C.2.4.4.1: Reduce trench length to maximum possible, 38 feet. This length maintains a minimum 1 foot separation from the site easement lines and retaining wall toe. It also allows the trench to be aligned better with existing contours and mimic natural runoff flow patterns. The onsite impervious surface (structures) runoff is also C FINAL I JANUARY 2020 111 LAKEHAVEN WATER & SEWER DISTRICT I PUMP STATION 33B I TIR discharged directly to the onsite porous asphalt, which will further reduce peak flow rates and overall volumes. Section C.2.4.4.5: Reduce setback from retaining wall to 1 foot. This was found to be an acceptable distance for this application and the Project Geotechnical Report sees no issue with locating the dispersion trench at the base of the retaining wall (See Geotechnical Report, Appendix B). Section C.2.4.4.5: Reduce setback from easement line to 1 foot. The downstream property is City of Federal Way owned property that will be maintained as a wetland and will not be developed. Figure 4.3 illustrates the proposed drainage system for the site while Figure 4.4 provides across section of the proposed porous asphalt. Figure 4.3 Proposed Site Drainage System 12 1 JANUARY 2020 1 FINAL C Car"I,-% 11, TIR I PUMP STATION 33B I LAKEHAVEN WATER & SEWER DISTRICT Figure 4.4 Proposed Porous Asphalt Cross Section Per the geotechnical report, fill below 2 feet of finished grade will be compacted to a minimum 90 percent of dry density. Therefore, a conservative infiltration rate of 0.01 inches per hour (or less than 1 inch per 4 days) was assumed forthe compacted site backfill. This compacted site backfill will consist of 1 to 6 feet of structural backfill, underlain by 7 feet of quarry spalls. The top 7 feet of existing soil at the site will be removed to allow for this installation of the quarry spalls. Storage volume at top of pavement to the bottom of the proposed pavement section is calculated to be equal to approximately 0.190 acre-feet (8,276 cubic feet). Flow frequency return periods can be found in Table 4.4. Full WWHM2012 results forthe project site are presented in Appendix C. Forthe evaluation of the proposed site, the retaining wall area, landscaped areas, and existing pervious/vegetated area were included but were not routed to the porous asphalt. Those surfaces are non -pollutant generating and will continue to sheet flow off site and disperse to the adjacent wetland. Table 4.4 Proposed Site Flow Frequency Return Periods Return Period Flow 2 year 0.0061 5 year 10 year 25 year 50 year 0.0169 0.0301 0.0577 0.0895 100 year 0.1347 4.3 Performance Standards Runoff from the site will be fully dispersed and is therefore not subject to the flow control or water quality facility requirements of the SWDM. However, the proposed porous pavement will provide peak flow reduction for the 2-, 5-,10-, and 25-year storms. C. FINAL I JANUARY 2020 113 LAKEHAVEN WATER & SEWER DISTRICT I PUMP STATION 33B I TIR 4.4 Flow Control Runoff from the site will be fully dispersed and is therefore not subject to the flow control facility requirements of the SWDM. Porous asphalt is being implemented to enhance flow control benefits beyond requirements and advance the District's and City's goal to implement LID technologies. As the project's WWHM2012 results illustrate, runoff rates forthe proposed site will remain below the majority of existing condition runoff rates (2-, 5-,10-, and 25-year storms). 4.5 Water Quality Runoff from the site will be fully dispersed and is therefore not subject to the water quality facility requirements of the SWDM. The site will, however, have a single cartridge Contech Stormfilter system installed to treat all runoff from the site's paved area priorto dispersal. This system will be sized to treat up to and slightly exceeding the site's 10-year flow. See the O&M Manual in Appendix F for additional information. CONVEYANCE SYSTEM ANALYSIS AND DESIGN There is no existing storm drainage conveyance system onsite. The proposed storm drainage system will consist of two catch basins and 8-inch diameter polyvinyl chloride (PVC) pipe. The system will act as an overflow system to convey any overflow from the porous asphalt to the proposed dispersion trench. This system will also manage runoff in the event of porous asphalt failure. The 8-inch diameter PVC pipe will be installed at a 2 percent slope providing a capacity of approximately 2.46 cfs, well above the model results of 0.22 cfs forthe proposed site's 100-year flow. This will provide additional capacity to handle emergency flows in the event of porous asphalt failure. See Appendix G for a copy of the site drainage plan. Section 5 SPECIAL REPORTS AND STUDIES In addition to the project's geotechnical report (Appendix B), a critical areas report was completed forthe project. The full critical areas report is included in Appendix H. 14 1 JANUARY 2020 1 FINAL C TIR I PUMP STATION 33B I LAKEHAVEN WATER & SEWER DISTRICT Section 6 OTHER PERMITS Q Land Use Permit Building Permit(s). Right -of -Way (ROW) Use Permit. Demolition Permit Section 7 EROSION AND SEDIMENTATION CONTROL ANALYSIS AND DESIGN The erosion and sedimentation control (ESC) plan is provided in Appendix D. The ESC plan addresses the 13 ESC Standards required by the SWDM (Section D.2.1) as follows: 1. Clearing Limits_ Clearing and grading limit extents of the project will be marked with silt fencing prior to any other work being conducted. The boundary limits of sensitive areas and their buffers will be left undisturbed. Cover Measures: Temporary cover will be installed if an area is to remain unworked for more than seven days during the dry season (May 1 to September 30) or for more than two consecutive working days during the wet season (October 1 to April 30). It is not anticipated that disturbed areas on the small project site will remain unworked for longer than two days. Provisions are provided within the ESC plan for covering of soil stockpiles that may remain unworked. 3. Perimeter Protection: Silt fence will provide perimeter protection and prevent sediment laden construction runoff from leaving the site. Straw waddle will be utilized during the proposed work within the ROW on S 359th Street to capture sediment -laden runoff from trenching operations. 4. Traffic Area Stabilization: A stabilized construction entrance will be utilized to reduce the amount of sediment transported onto paved roads by motor vehicles or runoff. The entrance will be relocated as necessary to facilitate the work and maintained during construction. 5. Sediment Retention: The project area is deemed small enough that construction runoff can be treated solely with perimeter protection. The provided perimeter protection consists of silt fence and straw waddle. 6. Surface Water Co[lection: The project area is deemed small enough that construction runoff can be treated solely with perimeter protection. The provided perimeter FINAL I JANUARY 2020 115 LAKEHAVEN WATER & SEWER DISTRICT I PUMP STATION 33B I TIR protection consists of silt fence and straw waddle. Untreated construction runoff will not be directed offsite. 7. Dewatering Control: Discharge of sediment -laden water from dewatering activities to surface and storm waters will be prohibited. The ESC plan designates a dewatering discharge area and the construction of an energy dissipation/settling structure to treat dewatering flows prior to discharge. 8. Dust Control: Dust control will be implemented when exposed soils are dry to the point that wind transport is possible and roadways, drainage ways, or surface waters are likely to be impacted. Water will be the preferred method of dust control unless additional measures are deemed necessary. Flow Control: The project area is deemed small enough that elevated storm flows during construction are not anticipated. Onsite depressions will be constructed as necessary during construction to prevent overloading of the perimeter protection and sediment - laden water from leaving the site. In the event storm flows exceeded the capacity of the onsite depressions, the detained storm water will be pumped to settling tanks then discharged via the proposed temporary discharge structure. 10. Control Pollutants. All pollutants, including waste materials, that occur onsite will be handled and disposed of in a manner that does not cause contamination of stormwater. a. Cover, containment, and protection from vandalism will be provided for all chemicals, liquid products, petroleum products, and non -inert wastes present on the site. b. Onsite fueling tanks will include secondary containment. c. Maintenance and repair of heavy equipment and vehicles involving oil changes, hydraulic system drain down, solvent and de -greasing cleaning operations, fuel tank drain down and removal, and other activities which may result in discharge or spillage of pollutants to the ground or into stormwater runoff will be conducted using spill prevention measures, such as drip pans. d. Contaminated surfaces will be cleaned immediately following any discharge or spill incident. 11. Protect Existing and Pro osed Flow Control BMPs: There are no existing flow control BMPs. The proposed dispersion trench will be constructed after paving is complete to prevent sediment build up or other damage to the facility. 12. Maintain BMPs: BMPs will be maintained per the ESC plan to prevent sediment -laden water from leaving the site for the duration of the project. 13. Manage the Project: Coordination and timing of site development activities relative to ESC concerns and timely inspection, maintenance and update of BMPs will be utilized for the duration of the project. 16 1 JANUARY 2020 I FINAL C Car�#1 TIR I PUMP STATION 33B I LAKEHAVEN WATER & SEWER DISTRICT Section 8 BOND QUANTITIES, FACILITY SUMMARY, AND DECLARATION OF COVENANT 8.1 Bond Quantities A bond quantities worksheet is not required as there are no proposed improvements to City of Federal Way facilities within the right-of-way and minimal onsite drainage facilities are being constructed. Roadway work will consist of restoration only. 8.2 Facility Summaries Not applicable. 8.3 Declaration of Covenant A declaration of covenant and grant of easement is required for the proposed flow control BMPs and will be included as Appendix E of this report after review, approval, and recording. The necessary covenant exhibits, and maintenance instructions associated with the flow control BMP type, will be included with the declaration of covenant. All such documents will be signed and recorded at the office of King County Records and Elections before any permit is approved. Section 9 OPERATIONS AND MAINTENTANCE MANUAL A stormwater operations and maintenance manual is provided in Appendix F of this report. C rFINAL JANUARY2020 117 TIR I PUMP STATION 33B I LAKEHAVEN WATER & SEWER DISTRICT Appendix A TECHNICAL INFORMATION REPORT CHECKLIST G'.' �""��"� FINAL I JANUARY2020 `CITY OF Federal Way Public Works TECHNICAL INFORMATION REPORT (TIR) CHECKLIST (Based on KCSWDM & Federal Way Addendum) Project Name: Sanitary Sewer Pump Station 33B (PS 33B) Date: Project No.: SECTION I — PROJECT OVERVIEW ➢ Figure 1— TIR Worksheet ➢ Figure 2 — Site Location ➢ Figure 3 — Drainage Basins ➢ Figure 4 — Soils Map SECTION II — CONDITIONS AND REQUIREMENTS SUMMARY SECTION III — OFF -SITE ANALYSIS 11/15/18 By: Brian Sliger SECTION IV — FLOW CONTROL AND WATER QUALITY FACILITIES ➢ Part A — Existing Site Hydrology ➢ Part B — Developed Site Hydrology ➢ Part C — Performance Standards ➢ Part D — Flow Control System ➢ Part E — Water Quality System SECTION V — CONVEYANCE SYSTEM ANALYSIS AND DESIGN SECTION VI — SPECIAL REPORTS AND STUDIES SECTION VII — OTHER PERMITS SECTION VIII — ESC ANALYSIS AND DESIGN SECTION IX — BOND QUANTITIES, FACILITY SUMMARY AND DECLARATION OF COVENANT SECTION X — OPERATIONS AND MAINTENANCE MANUAL Technical Information Report (TIR) Checklist Rev. 07/17 Page 1 of 5 Circ%d items need to be addressed. Checked Etitems are complete. GENERAL: The TIR should be a comprehensive supplemental report containing all technical information and analysis necessary to develop the site improvement plan. This report should contain all calculations, conceptual design analysis, reports, and studies required and used to construct a complete site improvement plan. X 1. Table of contents with page numbers provided. X 2. Stamped and dated by a licensed civil engineer registered in the State of Washington. SECTION I — PROJECT OVERVIEW X 1. Narrative - Pre & Post Development. X 2. Figure 1— TIR Worksheet. X 3. Figure 2 — Site Location. X 4. Figure 3 — Drainage Basins, Sub -Basins, & Site Characteristics: a. Acreage of sub -basins. b. Existing discharge points to and from site. c. Routes of existing, construction and future flows at all discharge points and downstream hydraulic structures. d. Minimum USGS 1:2400 topo map base. e. Show (and cite) length of travel from farthest upstream end of proposed storm system in development to any proposed flow control facility. X 5. Figure 4 — Soils Map: SEE GEOTECHNICAL REPORT a. Project site. b. Area draining to site. c. Drainage system downstream of site for distance of the downstream analysis. SECTION II — CONDITIONS & REQUIREMENTS SUMMARY x 1. Pre -approval conditions and applicable requirements pertaining to site engineering: a. SEPA mitigations. b. Environmentally sensitive area requirements. c. Variances and adjustments. d. Conditions of plat approval. SECTION III — OFF -SITE ANALYSIS NIA 1. City of Federal Way maps at 1" = 100' used for delineation of upstream tributary area to the site and to the downstream system (1" = 200' CFW drainage maps with contours also acceptable). N/A 2. Narrative - General make up of drainage system. Pipe size, channel characteristics and drainage structures. NIA 3. Downstream analysis. a. Study area definition and maps (min. of 1-mile downstream from discharge point). Technical Information Report (TIR) Checklist Rev. 07/17 Page 2 of 5 b. Resource review (basin plans, drainage studies, basin recon, maps, FEMA maps, other offsite studies, environmental studies, and wetland inventories). c. Field inspection. d. Drainage system description and problem descriptions (all existing and potential problems). e. Mitigation of existing or potential problems (for problem type 1, 2, and 3). NIA 4. Review Level 1 analysis and determine if a Level 2 or 3 analyses is warranted. SECTION IV -- FLOW CONTROL AND WATER QUALITY ANALYSIS AND DESIGN Part A — Existing Site Hydrology X 1. Narrative — Assumptions and site parameters used in analysis. X 2. Acreages, soil types, land covers, and basin maps. __X_- 3. Basin maps, graphics, exhibits for each sub -basin affected. X 4. Delineation and acreage of onsite areas and areas contributing runoff to the site, flow control facility location, outfall and overflow route shown on topographic map. X 5. Sub -basins labeled and KCRTS parameters referenced. NIA 6. 100-year floodplain delineated along closed depressions, streams, lakes and wetlands. Part B — Developed Site Hydrology X 1. Narrative — Assumptions and site parameters used in analysis. X 2. Acreages, soil types, land covers, roadway layouts and all constructed drainage facilities. X 3. Basin areas and flows depicted on a map, referenced to a computer printout or calc. sheets with areas highlighted and tabulated in a listing of all developed sub -basin flows. X 4. Sub -basins labeled, and KCRTS parameters referenced. Part C — Performance Standards X 1. Area specific flow control standard from flow control applications map and any modifications to standard, to address onsite or offsite drainage conditions. X 2. Conveyance system capacity standards. (Per Section 1.2.4.) N/A 3. Area specific water quality treatment menu per CFW adopted map and applicable special requirements for source control or oil control. Part D — Flow Control System 1. Sketch — Flow Control Facility and appurtenances with dimension and volume calculations from zero to maximum head; orifice sizes and head relationships; control structures/restrictor orientation to the facility. X 2. Volume Sizing — Provide electronic version and computer printouts, equations, calculations, tables, graphs and other data to support volume of storage facilities. NIA 3. Each single family lot contributing to the detention pond must be assumed to have 4000 sqft of impervious minimum. (Section 3.2.2 KCSWDM) N/A 4. Volumetric factor of safety used. Technical Information Report (TIR) Checklist Rev. 07/17 Page 3 of 5 N/A 5. Emergency spillway calculations provided. Part E — Water Quality System X 1. Sketch — Water quality facilities, source controls, oil controls and appurtenances, overall dimensions orientation, location of inflow, etc. N/A 2 Provide electronic version and computer printouts, calculations, equations, references, and graphs necessary to substantiate design. SECTION V — CONVEYANCE SYSTEM ANALYSIS AND DESIGN X 1. Detailed analysis of existing and proposed system. Labeling of elements conforms to engineering plans. X 2. If design results are on a computer printout, provide summary tabulation of performance. X 3. Pipe flow tables, flow profile computation tables, nomographs, charts, graphs, detail drawings, sub basins, other aids used to design and confirm performance. SECTION VI — SPECIAL REPORTS AND STUDIES Examples include: Anadromous Fisheries Impacts Floodplains Fluvial Geomorphology Geology Geotechnical/Soils Groundwater Hydrology Slope Protection/Stability Structural Design Structural Fill Water Quality Wetlands SECTION VII — OTHER PERMITS 1. List other permits by title, the agency requiring permit and requirements that affect the drainage plan. (WSDOT, WSDOE, NPDES, WSDOE — Dam Safety, etc.) SECTION VIII — ESC ANALYSIS AND DESIGN X 1. Narrative — How proposed ESC measures comply with ESC standards in Appendix "D" and Core Requirement No. 5: a. Clearing limits. b. Cover measures. c. Perimeter protection. d. Traffic area stabilization. e. Sediment retention -(sediment traps or pond), show location. f. Surface water controls. N/A 2. Hydrologic and hydraulic information used to analyze and size ESC facility. N/k. Special measures for high erosion areas. Technical Information Report (TIR) Checklist Rev. 07/17 Page 4 of 5 N/A 4. ESC recommendations in special reports. N/A 5. Proposed exceptions or modifications and rationale/supporting documentation. SECTION IX — BOND QUANTITIES, FACILITY SUMMARIES AND DECLARATION OF COVENANT N/A 1. Bond Quantities Worksheet completed. (Not required for preliminary TIR.) N/A 2. Flow control and water quality facility summary sheet and sketch. NIA 3. Declaration of Covenant, for privately maintained systems only, record prior to building permit. SECTION X — OPERATIONS AND MAINTENANCE MANUAL X 1. Maintenance and operation manual submitted specific to the project. Include a brief description of the flow control facility and water quality facilities, what they do, and how they work. Note Storm Filter Facilities may have a maintenance contract. Technical Information Report (TIR) Checklist Rev. 07/17 Page 5 of 5 TIR I PUMP STATION 33B I LAKEHAVEN WATER & SEWER DISTRICT Appendix B GEOTECHNICAL REPORT C FINAL I JANUARY2020 s ROBINSON NOBLE January 17, 2019 Mr. Ken Miller Lakehaven Water and Sewer District Post Office Box 4249 Federal Way, Washington 98063-4249 Revised Geotechnical Engineering Report Lakehaven Pump Station 33B Federal Way, Washington RN File No. 1529-058A Dear Mr. Miller - This letter serves as a transmittal for our revised report for the Lakehaven Pump Station 33B project, located on the south side of South 3591h Street just east of Pacific Highway South in Federal Way, Washington. We encountered a significant artesian aquifer at a depth of 37 feet below grade. The water head is about 19 feet above the ground surface and has greatly impacted the temporary and permanent design. Project plans are to install a pump station approximately 19 feet below the ground surface with a planned finished floor elevation of 154 feet. The approximate inside dimensions will be 14.33 feet by 18.33 feet. You also plan to construct a building to house a generator and electric panels and a separate double contained diesel tank on a slab. The overall site will be raised to create a level area and to add additional confining pressure to the artesian aquifer. We appreciate the opportunity of working with you on this project. If you have any questions regarding this report, please contact us. Sincerely, E-11� - SSUMAMM Rick B. Powell, PE Principal Engineer RBP:JRW:am Thirteen Figures Appendices A, B and C 2105 South C Street 17625 1301 Avenue NE, Suite 102 Tacoma, Washington 98402 www.robinson-noble.com Woodinville, Washington 98072 P: 253.475.77111 F: 253.472.5846 P: 425.488.0599 1 F: 425.488.2330 TABLE OF CONTENTS EXECUTIVESUMMARY...........................................................................................................................1 INTRODUCTION..........................................................................................................................................1 PROJECTDESCRIPTION.............................................................................................................................1 SCOPE..........................................................................................................................................................1 SITECONDITIONS.......................................................................................................................................2 SurfaceConditions..................................................................................................................................2 Geology.................................................................................................................................................... 2 Explorations.....................................................................................,...................................................... 3 SubsurfaceConditions...........................................................................................................................4 LaboratoryTesting..................................................................................................................................4 HydrologicConditions.............................................................................................................................4 MonitoringWells..................................................................................................................................4 HydraulicConductivity Testing................................................---...................................................----.5 GroundwaterGradient.........................................................................................................................5 Pipe Driving and Pressure Test .......................... ....5 GeologicHazards.....................................................................................................................................6 ErosionHazard..................................................................................................................................... 6 SeismicHazard.....................................................................................................................................6 CONCLUSIONS AND RECOMMENDATIONS...........................................................................................6 General..................................................................................................................................................... 6 SitePreparation and Grading.................................................................................................................7 StructuralFill...........................................................................................................................................8 General............................................................................................................................................. 8 Materials...............................................................................................................................................8 FillPlacement....................................................................................................................................... 9 Mechanical Stabilized Earth (MSE) Retaining Wall..............................................................................9 BuildingMat Foundations.......................................................................................................................9 Construction Methods for the Wet Well..............................................................................................10 General................................................................................................................................................10 LateralLoads..........................................................................................................................................12 Slabs-On-Grade.....................................................................................................................................13 Drainage.................................................................................................................................................13 Utilities....................................................................................................................................................13 PavementSubgrade..............................................................................................................................14 REVIEW AND CONSTRUCTION OBSERVATION SERVICES..................................................................15 USEOF THIS REPORT............................................................................................•..................................15 Robinson Noble, Inc. EXECUTIVE SUMMARY A geotechnical exploration program has been completed for the pump station and supporting structures. Based on the information obtained from our subsurface explorations, the site can be developed for the proposed project. The following geotechnical considerations were identified. Groundwater: An artesian groundwater aquifer known as the Redondo Milton Channel (RMC) was encountered approximately 37 feet below the ground surface. The aquifer has an extremely high permeability and storage capacity. The piezometric head of the RMC water table is currently 19 feet above the ground surface. The groundwater pressure within the top 30 feet of the ground surface has a piezometric head of 0 to 4 feet above the ground surface. • Site Soils: The subsurface soils consisted of layers of very soft silt, dense silty sand, hard silts, very dense silty sand and finally very dense sand and gravel. • Temporary Excavation: The groundwater levels and the subsurface soils observed have created challenging temporary excavation conditions. It is crucial a safe excavation be made to allow construction of the pump station to occur. • Seismic: The 2015 International Building Code (IBC) references Chapter 20 of ASCE 7 and the seismic site classification for this site is D. ■ Conventional Spread Foundations: Conventional spread footings bearing on medium dense native soils or structural fill appear adequate for building support. Allowable bearing pressures of 2,000 psf may be used for foundation supported on properly prepared subgrades. We recommend the soft silt at the surface be overexcavated and replaced with structural fill. • Mat Foundations: Mat footings under the Electrical Transformer, Odor Control System and Diesel Fuel Tank should be placed on medium dense native soils or structural fill extending to these soils. Allowable bearing pressures of 1,500 psf may be used for bearing support. We recommend the soft silt at the surface be overexcavated and replaced with structural fill. • Concrete Slabs: Floor slabs may be supported on properly prepared native or structural fill subgrades. Areas where the soft silts are not overexcavated will have a greater potential for settlement. This geotechnical executive summary should be used in conjunction with the entire report for design and/or construction purposes. It should be recognized that specific details were not included or fully developed in this summary, and the report must be read in its entirety for a comprehensive understanding of the items contained herein. Robinson Noble, Inc. INTRODUCTION This report presents the results of our geotechnical engineering investigation at your proposed sewer pump station project, in Federal Way, King County, Washington. The site is located on the south side of South 359th Street just east of Pacific Highway South, as shown on the Vicinity Map in Figure 1. The site is underlain by a confined aquifer and a high groundwater table. Wetlands have been identified to the east and west of the site. The confined aquifer is located approximately 37 feet below the ground surface and has a head of approximately 19 feet above the existing ground surface. The confined aquifer is known by our hydrogeologic staff and the Lakehaven Water and Sewer District (Lakehaven) as the Redondo Milton Channel (RMC). The subsurface soils from 0 to 30 feet in depth have a groundwater head ranging from 0 to 4 feet above the ground surface as identified later in this report. PROJECT DESCRIPTION The project will consist of constructing a below -grade sewer pump station with multiple outbuildings, to house a generator, diesel tank and electrical equipment. The sewer pump station will consist of a concrete vault with inner dimensions of 14.33 feet by 18.33 feet. A 48- inch diameter sewer line will be connected to the concrete structure. The pump station finished floor will have an elevation of 154 feet. The outside dimension of the diesel tank slab will be approximately 10 feet by 15 feet. We understand that the diesel tank foundations will require a bearing capacity of 2,000 pounds per square foot (psf) with allowable settlement less than 1 inch total and 1/2 inch differential. The outside dimensions of the generator/electrical panel slab will be approximately 31 feet by 36 feet. SCOPE The purpose of this study is to explore and characterize the subsurface conditions and present recommendations for site development. Specifically, our scope of services as outlined in our Services Agreement, dated January 5, 2016, includes the following: a Review of available geologic maps for the site. • Explore the subsurface soil and groundwater conditions in the area of the planned pump station by drilling one boring with a mud -rotary drill rig to a depth of 60 feet or into a less permeable soil layer, whichever is shallower. ■ Explore the subsurface soil and groundwater conditions in the area of the buildings with one borings to a depth of 15 feet. ■ Install piezometers to measure the water table in the area of the planned sewer pump station. • Evaluate pertinent physical and engineering characteristics of the soils encountered in the borings. ■ Complete laboratory tests consisting of grain -size curves and moisture contents. Attend design meetings with Lakehaven or the design team. ■ Provide consultation and review of different shoring methods. This could include discussion with contractors regarding potential designs. Robinson Noble, Inc. Revised Geotechnical Engineering Report Lakehaven Pump Station 33B Federal Way, Washington January 17, 2019 RN File No. 1529-058A Page 2 ■ Prepare a geotechnical report containing the results of our subsurface explorations, and our conclusions and recommendations for geotechnical design elements of the project. Expanded Scope: After completing the above services and identifying the large artesian pressure below the subject site, we recommended the following scope of services: ■ Retain the pile driving contractor to install three pipe piles to a depth of 31.5 feet. The pipes were closed ended and were pressure tested at the completion to verify that they could be used for ground freezing. The pipes will be left in place and used if they are located in the ground freezing area. • We plan to install two borings to a depth of 30 feet in the area of the shoring walls and one additional boring will be completed above the silt layer at approximately 20 feet in depth. • Observe the installation of two water monitoring wells to measure the water table in the area of the planned sewer pump station. • Complete laboratory tests consisting of moisture contents as necessary. • Complete hydraulic conductivity tests with the existing monitoring wells. This is contingent on the head pressure being low enough to complete the test. SITE CONDITIONS Surface Conditions The roughly rectangular shaped project site easement area is about 0.22 acres in size and has average dimensions of approximately 95 feet in the east -west direction and 100 feet in the north -south direction. However, due to wetlands, stream and property setbacks, usable area for the pump station and appurtenances (electrical building, odor control system, etc.) is about 0.11 acres. Access to the site is provided by an existing driveway, extending southward from South 359th Street. The site is bordered by South 3591h Street to the north and wetlands to the east and west, and an existing sewer pump station to the south. A layout of the site is shown on the Site Plan in Figure 2. The ground surface within the site is generally gently sloping down to the south/southeast. The site is vegetated mostly with blackberry bushes, and contains a few small- to- medium sized trees. Wetlands have been identified by others on the east side of the site and west of the access roadway. The north branch of Hylebos Creek is located to the east of the site and water from the east wetland seeps towards the creek. Geology Most of the Puget Sound Region was affected by past intrusion of continental glaciation. The last period of glaciation, the Vashon Stade of the Fraser Glaciation, ended approximately 14,000 years ago. Many of the geomorphic features seen today are a result of scouring and overriding by glacial ice. During the Vashon Stade, areas of the Puget Sound region were overridden by over 3,000 feet of ice. As the glaciers retreated low areas carved out from the glaciers became large river valleys. Over time collected soil from the flowing water was deposited and size of Robinson Noble, Inc. Revised Geotechnical Engineering Report Lakehaven Pump Station 33B Federal Way, Washington January 17, 2019 RN File No. 1529-058A Page 3 soil particles deposited was dependent on the flow rates of the river. These deposits are referred to as Alluvium. Large sand and gravel was deposited within faster moving water and fine grained soils were deposited in slow to stagnant water. As more deposits were placed the river channels became more confined to the paths they currently exist in. Alluvial deposits were not compacted by the weight of the glaciers and may exhibit less strength and density compared to soils that were. Part of a typical glacial sequence within the area of the site includes the following soil deposits from newest to oldest: Artificial Fill (af) — Fill material is often locally placed by human activities, consistency will depend on the source of the fill. The thickness and expanse of this material will be dependent on the extent of fill required to grade land to the desired elevations. Density of the fill will depend on earthwork activities and compaction efforts made during the placement of the material. Recessional Outwash (Qvr) —These deposits were derived from the stagnating and receding Vashon glacier and consist mostly of stratified sand and gravel, but include unstratified ablation and melt -out deposits. Recessional deposits were not compacted by the glacier and are typically not as dense as those that were. Vashon Till (Qvt) — The till is a non -sorted mixture of clay, sand, pebbles, cobbles and boulders, all in variable amounts. The till was deposited directly by the ice as it advanced over and eroded irregular surfaces of previously deposited formations and sediments. The till was well compacted by the advancing glacier and exhibits high strength and stability. Drainage is considered very poor in the till. Advance Outwash (Qva) — The advance outwash typically is a thick section of mostly clean, pebbly sand with increasing amounts of gravel higher in the section. The advance outwash was placed by the advancing glaciers and was overridden and well compacted by the glacier. The geologic units for this area are mapped on the Geologic Map of the Poverty Bay Quadrangle, King and Pierce Counties. Washington, by D.B. Booth, H.H. Waldron, and K.G. Troost (U.S. Geological Survey, 2004). The site is mapped as being underlain by a deposit of glacial till. Our site explorations encountered glacial drift/till and alluvial soils. Glacial drift is similar to glacial till, but may exhibit more sorting of various soil grain sizes. Explorations We explored subsurface conditions within the site on February 25, 2016, by drilling two borings with a track mounted mud rotary drill rig, and on May 2, 2016, by drilling three borings with a track mounted drill rig. The borings were drilled to depths of 15 to 43 feet below the ground surface. Samples were obtained from the borings at 5-foot intervals by driving a split spoon sampler with a 140-pound hammer dropping 30 inches. The number of blows required for penetration of three 6-inch intervals was recorded. To determine the standard penetration number at that depth the number of blows required for the lower two intervals are summed and then corrected to Nso. If the number of blows reached 50 before the sampler was driven Robinson Noble, Inc. Revised Geotechnical Engineering Report Lakehaven Pump Station 33B Federal Way, Washington January 17, 2019 RN File No. 1529-058A Page 4 through any 6-inch interval, the sampler was not driven further and the blow count is recorded as 50 for the actual penetration distance. The borings were located in the field by an engineer from this firm who also examined the soils and geologic conditions encountered, and maintained logs of the borings. The approximate locations of the borings are shown on the Site Plan in Figure 2. The soils were visually classified in general accordance with the Unified Soil Classification System, a copy of which is presented as Figure 3. The logs of the borings are presented in Figures 4 through 11. Subsurface Conditions A brief description of the conditions encountered in our explorations is included below. For a more detailed description of the soils encountered, review the Boring Logs in Figures 4 through 11. In general, we encountered about 0 to 7 feet of very soft silt deposit that underlies the site. This soft layer is underlain by dense to very dense silty sand or hard silt to approximately 37 feet. At a depth of 37 feet, we encountered sand and gravel with an unusually high piezometric head. Laboratory Testing We completed a few laboratory tests on various soil samples. These tests consist of the following: Moisture contents • Atterberg limit tests ■ Grains size distribution curves The laboratory results are included on the Boring Logs and within Appendix A. Hydrologic Conditions Monitoring Wells We installed five 2-inch diameter monitoring wells. Water was observed flowing above existing grades from the wells. The piezometric water levels were recorded by attaching additional pipes on top of the monitoring wells above the ground surface and allowing the water to equalize. All of the monitoring wells have a water level that is above the ground surface (ags). Monitoring Well _ B1 B2 B3 Depth of Well (ft) 37 15 30 B3a 21 B4 27.5 Groundwater Level/Piezometric Head (ft) +19.0 ags +0.3 ags +4.3 ags +0.4 ags +1.1 ags Robinson Noble, Inc. Revised Geotechnical Engineering Report Lakehaven Pump Station 33B Federal Way, Washington January 17, 2019 RN File No. 1529-058A Page 5 Hydraulic Conductivity Testing We completed additional testing of the hydraulic conductivity of the soil units. These values were calculated by completing slug tests on the monitoring wells with a lower piezometric head. The slug tests were monitored with pressure transducers and a curve of the groundwater rebound was recorded. Select tests are shown in Figure 12. These values should be considered only estimates because the permeability was relatively low. The summary of the results is shown in the following table: Monitoring Well Well Screen Length (ft) Hydraulic Conductivity (ft/day) 131 10 267* B2 10 0.02 to 0.03 B3 2 0.005 to 0.015 133a 2 0.015 to 0.025 B4 2 0.005 to 0.015 *This value was used from a pump test completed by Terracon on the RMC approximately 1,000 feet to the west. The estimated hydraulic conductivities have been correlated with the soil types in Figure 2.7 of "Seepage, Drainage and Flow Nets", by Harry R. Cedergren (1989). The hydraulic conductivities provided in the document are consistent with the soil conditions we are testing. Groundwater Gradient The groundwater levels for the confined aquifer at depth were determined by using the water level in B-1 and the water level in well LUD 15 located to the north on the same day. The distance between LUD 15 and B-1 is approximately 2,700 feet. We also used our regional groundwater level maps and have correlated the gradient to be downward in a northeast to southwest direction. This reduces the horizontal length of the groundwater flow to 2,054 feet. The piezometric head change between LUD 15 to B-1 is 23.1 feet. Therefore the expected gradient of the lower confined aquifer is 1.1 %. Our hydrogeology department has provided us with long-term data that shows this aquifer piezometric head has been rising to the current state. We also measured the groundwater gradient difference between B-3 and B-4. This groundwater level is directly below the clayey silt layer approximately 30 feet below the surface. We expect the gradient is in a downward direction similar to the surface grade from north to south. The horizontal length is approximately 48 feet and the groundwater elevation difference is 5.05 feet. Therefore the gradient is approximately 10.5%. We expect the groundwater gradient in the upper 20 to 25 feet is approximately the ground surface, which is approximately 12%. Pipe Driving and Pressure Test Three 3-inch diameter pipes were driven at the site in the area of the proposed pump station to determine if they could penetrate the dense and hard subsurface layers. A test program was established to drive three pipes to a depth of 30 feet. We completed these tests on May 23, Robinson Noble, Inc. Revised Geotechnical Engineering Report Lakehaven Pump Station 33B Federal Way, Washington January 17, 2019 RN File No. 1529-058A Page 6 2016. The pipes were also pressure tested after they were driven. The pipes could be easily driven to a depth of about 26 feet and then slowed down in the very dense silty sand material below the clayey silt layer. If these piles are not needed for construction, the piles should be removed or cut off and the holes grouted with bentonite to adequately seal the aquifer. Geologic Hazards Erosion Hazard: The erosion hazard criteria used for determination of affected areas includes soil type, slope gradient, vegetation cover, and groundwater conditions. The erosion sensitivity is related to vegetative cover and the specific surface soil types (group classification), which are related to the underlying geologic soil units. We reviewed the Web Soil Survey by the Natural Resources Conservation Service (NRCS) to determine the erosion hazard of the on -site soils. The site surface soils were classified using the SCS classification system as Bellingham silt loam. The corresponding geologic unit for these soils is alluvium, which is in agreement with the soils encountered in our site explorations. The erosion hazard for the soil is listed as being slight for the gently sloping conditions at the site. Seismic Hazard: It is our opinion based on our subsurface explorations that the Soil Profile in accordance with the 2015 International Building Code (IBC) and ASCE 7 is Site Class D with Seismic Design Category D. We used the US Geological Survey program "U.S. Seismic Design Maps Web Application." The design maps summary report for the 2015 IBC is included in this report as Appendix B. We have completed a liquefaction analysis of the soil in the area of the planned sewer pump station. It is our opinion there is a low potential for liquefaction because of the density of the soil and the underlying impermeable layers. There is a potential for slope stability issues during a large seismic event because of the underlying artesian pressure. The rock trench and MSE wall described below help protect the improvements from slope stability concerns during a large seismic event. CONCLUSIONS AND RECOMMENDATIONS General It is our opinion that the site is compatible with the planned development, but extreme caution should be used to avoid puncturing the lower aquifer. The 19 feet of artesian pressure ags at a depth of approximately 37 feet has created a significant design and construction constraint. We have evaluated several methods to construct the pump station. The design team has chosen a sink -in -place caisson type construction. This method was selected to maintain the factor of safety to reduce the risk of affecting underlying artesian pressures. Recommendations for the caisson construction is provided in the Construction Methods for the Pump Station subsection below. The underlying medium dense or firmer glacially consolidated soils are capable of supporting the planned structures and pavements. We recommend that the foundations for the structures extend through any fill, topsoil, loose, or disturbed soils, and bear on the underlying medium dense or firmer native glacial soils, or on structural fill extending to these soils. Based on our Robinson Noble, Inc. Revised Geotechnical Engineering Report Lakehaven Pump Station 33B Federal Way, Washington January 17, 2019 RN File No. 1529-058A Page 7 site explorations, we anticipate these soils will be encountered at approximately 7 feet below existing ground surface. The underlying 7 feet of soil should be replaced with structural fill or rock spalls. We recommend that the entire pad in the areas of improvement be overexcavated. This process will need to occur in small sections to reduce the chance of affecting the underlying aquifers. The small section should not be more than 25 Cubic Yards total with a depth of about 7 feet exposed at any one time. If only portions of the underlying soils are removed, it should be understood that long term differential settlement will occur between the areas overexcavated and those areas not overexcavated. Repairs will need to be made as the underlying clayey silt consolidates. If the excavation breached the confining layer with a 20-foot diameter excavation we expect the flow rate could be hundreds and possibly thousands of gallons per minute (gpm). It is critical that even small excavations or pile penetration into the underlying lower artesian aquifer be avoided. Therefore, we have tried to make recommendations to construct the pump station without extending the main excavation or any other elements below 23 feet bgs to reduce the chance of penetrating the aquifer. The buoyant factor of safety for existing conditions from the lower aquifer is 1.32. The District has accepted that the long term overall buoyant loads can be less than 1.5 with the understanding that the piezometric head (water level) would have to reach 212 feet (roughly 45 feet above ground surface) before failure occurred and that fact that the planned conditions will increase the overall factor of safety for buoyant conditions to 110%. Since the nearby creek is lower in elevation, we expect eventually the underlying aquifer will break and water will leak into the creek if the water table continues to rise. We also recommend that each step of the construction process maintain a Factor of Safety of 1.5 from buoyant pressures for each step of construction. If the District or contractor chooses to design or construct below this factor of safety, additional risk of "blowing out" the lower aquifer increases. It is important to note that the exact soil conditions are not known and some degree of unknown risk already exists. Because of the significant cost to seal the broken aquifer, we have recommended that a factor of safety of 1.5 be used in design and this has been discussed with the District and design team. Site Preparation and Grading We understand that the site's surface elevation is to be raised approximately 4 feet. The first step of site preparation should be to strip the vegetation and topsoil. Areas where structures will be constructed should be overexcavated to medium dense or firmer soils. We anticipate medium dense or firmer soils to be encountered approximately 7 feet below the existing ground surface. We recommend that up to 7 feet of fill in the excavated area consist of 2 to 4 inch quarry spalls or other approved free -draining material to allow for the high groundwater table to flow freely to the wetland. No more than 25 Cubic Yards shall be removed at a time prior to backfilling. This will maintain a consistent surcharge pressure on the underlying aquifer. Use of steel sheets between the wetland and the excavation could be used to allow a Robinson Noble, Inc. Revised Geotechnical Engineering Report Lakehaven Pump Station 33B Federal Way, Washington January 17, 2019 RN File No. 1529-058A Page 8 near vertical cut to be made in the excavation. The rock spalls should be placed to an elevation above the water in the excavation and then capped with granular structural fill to reduce the chance of fines entering the voids of the rock spalls. Placement of fabric, such as Mirafi 180N may be needed between the rock spalls and the structural fill. Use of a typical structural fill material around the wet well, value vault, flow meter vault and manhole #1 may benefit the shoring process. Overexcavating the soft clayey silt and replacement with rock spalls in only portions of the pump station pad could allow for significant differential settlement as the underlying clay silt consolidates. We understand that this may be acceptable to the District because of the additional time available prior to constructing all the improvements. If these soils are left in place, long term maintenance to relevel the site should be expected. A temporary average site elevation of 174 will be required in a 30 foot spacing around the wet well. This is approximately 2 feet higher than the planned grade. We expect the edges of the fill will be sloped to the MSE wall face. The additional fill will provide some additional surcharge to the planned grade and could be later used as granular backfill for the utility lines if organized by the contractor Structural Fill General: All fill placed beneath buildings, pavements or other settlement sensitive features should be placed as structural fill. Structural fill, by definition, is placed in accordance with prescribed methods and standards, and is observed by an experienced geotechnical professional or soils technician. Field observation procedures would include the performance of a representative number of in -place density tests to document the attainment of the desired degree of relative compaction. We recommend that the site grade be capped with a granular structural fill material that would allow for a workable construction surface for heavy construction equipment. The granular material could consist of a crushed rock type material or quarry shot rock (rock spalls). These methods can be evaluated at the time of construction but are expected to be part of the raised building pad. Materials: Imported structural fill for the top 4 feet or finished grade elevation, whichever is greater, should consist of a good quality, free -draining granular soil, free of organics and other deleterious material, and be well graded to a maximum size of about 3 inches. Imported, all- weather structural fill should contain no more than 5 percent fines (soil finer than a Standard U.S. No. 200 sieve), based on that fraction passing the U.S. 3/4-inch sieve. The imported structural fill for the excavated areas should consist of a good quality, free - draining granular material, free of organics and other deleterious material. We recommend the use of 2 to 4 inch quarry spalls within the overexcavated portion below the groundwater table. Use of control density fill (CDF) could be considered around the wet well. This would allow the wet well to be tied into the weight of the CDF. On -site soil should not be used as structural fill unless approved by the geotechnical engineer. Robinson Noble, Inc. Revised Geotechnical Engineering Report Lakehaven Pump Station 33B Federal Way, Washington January 17, 2019 RN File No. 1529-058A Page 9 Fill Placement: Following subgrade preparation, placement of the structural fill may proceed. Fill should be placed in 8- to 10-inch-thick uniform lifts, and each lift should be spread evenly and be thoroughly compacted prior to placement of subsequent lifts. All structural fill underlying building areas, and within a depth of 2 feet below pavement and sidewalk subgrade, should be compacted to at least 95 percent of its maximum dry density. Maximum dry density, in this report, refers to that density as determined by the ASTM D1557 compaction test procedure. Fill more than 2 feet beneath pavement subgrades should be compacted to at least 90 percent of the maximum dry density. The moisture content of the soil to be compacted should be within about 2 percent of optimum so that a readily compactible condition exists. It may be necessary to overexcavate and remove wet surficial soils in cases where drying to a compactible condition is not feasible. All compaction should be accomplished by equipment of a type and size sufficient to attain the desired degree of compaction. Mechanical Stabilized Earth (MSE) Retaining Wall The entire site is being raised to an approximate final elevation 173 feet on the north end and 171 feet on the south end. The average site grade will be elevation 172. A MSE retaining wall is planned around the perimeter of the site to accommodate grade changes. Since the retaining walls will be supporting buildings or other equipment, the base should be prepared as described in the Site Preparation and Grading section of this report. The entire area below the MSE wall should be overexcavated approximately 5 feet (7 feet total) and filled with rock spalls and/or structural fill, as shown in Figure C2. The spalls should be capped with a 2"-minus crushed rock product to prevent migration of the fines from the reinforced soils above. This will provide a stronger foundation base and will help prevent lateral spreading during seismic events. The wall will also be reinforced with geosynthetics. We recommend using Tensar UX140OMSE or equivalent that extends a minimum of 8 feet from the face of the blocks. The wall was evaluated for local and global stability using computer programs MSEW 3.0 by ADAMA Engineering, Inc. and Slide, version 6.0, by Rocscience. Planned conditions were used to calculate static and dynamic stability of the wall. Global stability was the main driving force for determining the extent of overexcavation necessary for stability of the planned retaining wall, as shown in Appendix C. We used the measured existing water levels from our explorations as the water surface in our analysis. Factors of safety against failures were above 1.5 and 1.15 for static and dynamic conditions, respectively. A detail of the retaining wall and calculations are attached to this report within Appendix C. Building Mat Foundations Conventional shallow spread foundations should be founded on undisturbed, medium dense or firmer soil. If the soil at the planned bottom of footing elevation is not suitable, it should be overexcavated to expose suitable bearing soil. Footings should extend at least 18 inches below the lowest adjacent finished ground surface for frost protection. Minimum foundation widths should conform to IBC requirements. Standing water should not be allowed to accumulate in footing trenches. All loose or disturbed soil should be removed from the foundation excavation Robinson Noble, Inc. Revised Geotechnical Engineering Report Lakehaven Pump Station 33B Federal Way, Washington January 17, 2019 RN File No. 1529-058A Page 10 prior to placing concrete. We recommend a setback of 5 feet from the toe of the wall face to any foundation. For conventional building foundations constructed as outlined above, we recommend an allowable design bearing pressure of 2,000 pounds per square foot (psf) be used for the footing design. IBC guidelines should be followed when considering short-term transitory wind or seismic loads. Potential foundation settlement using the recommended allowable bearing pressure is estimated to be less than 1-inch total and �h-inch differential between footings or across a distance of about 30 feet. Higher soil bearing values may be appropriate with wider footings. Mat footings under the Electrical Transformer, Odor Control System and Diesel Fuel Tank should be placed on medium dense native soils or structural fill extending to these soils. Allowable bearing pressures of 1,500 psf may be used for bearing support. IBC guidelines should be followed when considering short-term transitory wind or seismic loads. The lateral pressures may be resisted by friction at the base of the footing and passive resistance against the foundation. A coefficient of friction of 0.45 may be used to determine the base friction in the structural fill pad. An equivalent fluid density of 200 pcf may be used for passive resistance design. To achieve this value of passive pressure, the foundations should be poured "neat" against the native dense soils, or compacted fill should be used as backfill against the front of the footing. The soil in front of the wall should extend a horizontal distance at least equal to three times the foundation depth. A resistance factor of 0.5 has been applied to the passive pressure to account for required movements to generate these pressures. The friction coefficient does not include a factor of safety. Construction Methods for the Wet Well General The bottom of the excavation is approximately 20 feet below the ground surface. This total depth includes the footing thickness and a subsurface layer of drainage rock. We have evaluated several alternatives to complete the excavation without damaging the confining layer above the artesian sand and gravel aquifer. It is our opinion that all systems should be less than 23 feet bgs if possible. This gives at least a 14 foot confining layer from the bottom of the construction to the lower aquifer. It is our opinion dewatering the lower aquifer is not an option. The Robinson Noble hydrogeologists have indicated that it would require the pumping of an extreme amount of water to lower the aquifer even 1 foot. Some dewatering in the upper 30 feet is required to maintain appropriate buoyant factors of safety for the upper and middle aquifer. The design team has provided detailed recommendations for a sink -in -place caisson type construction method. No other methods are recommended, unless the contractor shows a method and calculations how the pump station will be installed and by maintaining a factor of safety acceptable to the district. Robinson Noble, Inc. Revised Geotechnical Engineering Report Lakehaven Pump Station 33B Federal Way, Washington January 17, 2019 RN File No. 1529-058A Page 11 Construction Sequence for Sink -in -Place Caisson Step One: Prepare the entire site existing grade. ■ Overexcavate the site in the area of the planned buildings, MSE wall, and other structures. We expect the overexcavation process as described above will be at least 7 feet deep to remove the soft soils. Some excavation outside of the wall footprint will be required or additional wall design recommendations will be required. • Overexcavation shall be limited to less than 25 cubic yards at a time prior to backfilling. It is important to maintain the normal effective stresses on the underlying confining layers. The intent is to excavate and backfill in a sequencing method. • Fill the site to a temporary grade of elevation 174 or higher within a distance of 30 feet around the perimeter of the wet well. This would roughly be 80 feet by 80 feet. • Overexcavation of the entire site should be considered by the District to reduce long- term settlement concerns. Step two: Install the Sink -in -place caisson with dimensions specified for the wet well. • It will be the contractor's responsibility to maintain a buoyant loading condition Factor of Safety of 1.5 of greater from the upper, middle and lower aquifers. The water elevation in these are aquifers and recorded on the logs are as follows: o Lower Aquifer @ elevation 132 and below — Piezometric Pressure 188.0 feet o Middle Aquifer @ elevation 143 to 140 - Piezometric Pressure of 174.1 feet o Upper Aquifer @ elevation 168 to 146 - Piezometric Pressure of 170 feet • Excavate or predrill the edges of the caisson to allow for easy installation through the very dense sand (Glacial till). The excavated or predrill material should be left in the lower portions of the excavation. • As the center of the caisson is excavated, the factor of safety of blow out of the bottom decreases due to uplift forces. A water level of 166 feet needs to be maintained inside the caisson to counter the uplift forces. This water level needs to be maintained until the structural mud slab is poured that transfers the uplift to the concrete caisson. Step Three Dewater the Upper and Middle Aquifer • The upper aquifer as defined as the depth between 168 to 146 feet shall be lowered to elevation 156 feet or lower • The middle aquifer as defined as the depth between 143 to 140 feet shall be lowered to elevation 158 feet of lower. • This can be done with one dewatering system or multiple systems. Step Four Install the 1 foot of sand and gravel and the 2 foot structural mud mat. Robinson Noble, Inc. Revised Geotechnical Engineering Report Lakehaven Pump Station 33B Federal Way, Washington January 17, 2019 RN File No. 1529-058A Page 12 • These will have to be installed in the wet. The water elevation inside the caisson will need to be 166 feet or higher. • The uplift pressure on the inside area of caisson from the lower aquifer on the mud mat and underlying rock will be 327 psf to maintain a Factor of Safety of 1.5 (weight of mud mat and 1 foot of rock has reduced the uplift pressure). • Divers will be needed to install the reinforcing for the mud mat. • Grouting the exterior annulus between the soil and caisson exterior is recommended but not included in design values. We recommend that no side friction can be used for the structural design for long-term uplift. Step Five Install wing foundations that extend out from the caisson. Soil placed on these wing foundations will resist uplift in the final design. • The bottom of the wing foundations will be on three sides of the structure and will extend from the caisson at elevation 164 feet. The foundations will extend out 3.5 feet minimum from the caisson. • The caisson will need to be filled full with water during this period. Backfill the wing walls with compacted fill (135 pcf). Step Six Install the finished floor slab • Pump the water out of the caisson • Install a structural slab tied into the caisson walls. The connection from the structural slab to the caisson walls shall be designed to resist the uplift load on the interior slab. The uplift load is 1,100 psf and has included the weight of the slab to maintain a Factor of Safety of 1.5. Step Seven Finishing touches Install the equipment Install the concrete cap Lower site grade to approximately Elevation 172 feet Lateral Loads The lateral earth pressure acting on the pump station walls, temporary shoring, and retaining walls is dependent on the nature and density of the soil behind the wall, the amount of lateral wall movement, which can occur as backfill is placed, and the inclination of the backfill. Walls that are free to yield at least one -thousandth of the height of the wall are in an "active" condition. Walls restrained from movement by stiffness or bracing are in an "at -rest" condition. Active earth pressure and at -rest earth pressure can be calculated based on equivalent fluid density. The pressure diagram is shown in Figure 13. Equivalent fluid densities for active and at -rest earth pressure are in units of pounds per cubic foot (pcf). These values assume that the on -site soils or imported granular fill are used for Robinson Noble, Inc. Revised Geotechnical Engineering Report Lakehaven Pump Station 33B Federal Way, Washington January 17, 2019 RN File No. 1529-058A Page 13 backfill. We understand that the traffic surcharge load will be designed with an H-20 loading condition. We have included in our pressure diagram in Figure 13 a formula to correlate the Weight of the H-20 loading condition to a horizontal force to be applied to the structures. The presented values do not include the effects of other surcharges, such as due to foundation loads. Surcharge effects should be considered where appropriate. Seismic lateral loads are a function of the site location, soil strength parameters and the peak horizontal ground acceleration (PGA) for a given return period. The drained active and at -rest values should be increased by a uniform pressure of 9H and 14H psf, respectively, when considering seismic conditions. H represents the wall height. Slabs -On -Grade Slab -on -grade areas should be prepared as recommended in the Site Preparation and Grading subsection. Slabs should be supported on medium dense or firmer native soils, or on structural fill extending to these soils. Medium dense or better soils are expected to exist at about 7 feet bgs. We understand that some level of settlement may be acceptable for slabs. The amount of settlement will be proportionate to the amount of loose soils left under the slab. Full, partial or no overexcavation will be related to the amount of settlement to be expected. Where moisture control is a concern, we recommend that slabs be underlain by 6 inches of pea gravel for use as a capillary break. A suitable vapor barrier, such as heavy plastic sheeting, should be placed over the capillary break. An additional 2-inch-thick damp sand blanket can be used to cover the vapor barrier to protect the membrane and to aid in curing the concrete. This will also help prevent cement paste bleeding down into the capillary break through joints or tears in the vapor barrier. The capillary break material should be connected to the footing drains to provide positive drainage. Drainage We recommend that runoff from impervious surfaces, such as roofs and access roadways, be collected and routed to an appropriate storm water discharge system. The finished ground surface should be sloped at a gradient of 5 percent minimum for a distance of at least 10 feet away from the buildings, or to an approved method of diverting water from the foundation, per IBC Section 1804.3. It is our opinion a dispersion trench on the south side of the project will help control the surface water. The dispersion trench would allow for a sheet flowing affect to avoid the concentration of water. The dispersion trench would model the existing conditions the best and will be constructed at the base of the MSE wall. We also understand that Lakehaven would like to place permeable pavement to allow for water filtration to occur. It is our opinion that permeable pavement could be used on this project considering the structural fill that will be placed to raise the grade of the site Utilities Temporary dewatering: We anticipate that dewatering will be needed to install utilities into the sewer pump station. The groundwater encountered may be handled with pumps within the Robinson Noble, Inc. Revised Geotechnical Engineering Report Lakehaven Pump Station 33B Federal Way, Washington January 17, 2019 RN File No. 1529-058A Page 14 trenches but a deeper dewatering system may be more beneficial to allow for the pumping of clean water and therefore easy discharge of the water to the nearby creek. The groundwater level in the area of the pump station is near ground surface. We have reported, in the hydraulic testing subsection of this report, some slug test results to estimate the permeability of the soil. Other groundwater dewatering methods will need to be considered in the field during construction. We understand that two influent sewer manholes will be 9 foot inside diameter and will be excavated into the ground near the wet well structure and in the roadway. We also know the value vault and the flow meter vault will have to be constructed. These excavations can be made provided that the upper and middle aquifers water elevations are lowered to the base of the respected excavations. The contractor shall not excavate more than 150 Cubic Yards from each individual excavation after the upper and middle aquifer have been lowered. We also strongly encourage that the material removed from the excavation be stockpiled on the building pad close the excavation to maintain the weight of the soil on the underlying aquifers. Removal of the soil from the site will reduce the factor of safety. A larger or deeper excavation must be approved by the geotechnical engineer "prior" to making the excavation. Other options are available such as installing the manhole in the wet or having additional surcharge confining pressure around the manhole. Uplift forces on the manholes and vaults: The permanent manholes and vaults need to be designed to resist buoyant forces from uplift. We recommend that the manhole or vault be designed to resist water pressure below the structure, as shown in Figure 13. This uplift can be counteracted (weighed down) by using the weight of the manhole structure, the slab in the manhole, the cover over the manhole, the soil and pavement over top of the concrete cover, and/or additional wing walls with soil weight outside of the manhole diameter. Shoring: Temporary shoring will be required to install the utilities at this site. Large open cuts will not be allowed if the amount of material exceeds the 150 Cubic Yards. The shoring system can be designed per the pressure diagram as shown in Figure 13. In order to protect the underlying lower aquifer, we recommend the use of deep foundation system be limited to a 25 foot depth into the ground without specific approval by the geotechnical engineer. Pavement Subgrade The performance of roadway pavement is critically related to the conditions of the underlying subgrade. We recommend that the subgrade soils within the roadways be prepared as described in the Site Preparation and Grading subsection of this report. Prior to placing base material, the subgrade soils should be compacted to a non -yielding state with a vibratory roller compactor and then proof -rolled with a piece of heavy construction equipment, such as a fully - loaded dump truck. Any areas with excessive weaving or flexing should be overexcavated and recompacted, or replaced with a structural fill or crushed rock. Any fill should be placed and compacted in accordance with recommendations provided in the Structural Fill subsection of this report. New asphalt pavements should conform to City of Federal Way standards. The minimum Robinson Noble, Inc. Revised Geotechnical Engineering Report Lakehaven Pump Station 33B Federal Way, Washington January 17, 2019 RN File No. 1529-058A Page 15 pavement sections should be: Minimum ravement Layer I MCKness for % inch HMA Layer Material Thickness (inches) Light Duty Heavy Duty Asphalt* 3 4 Crushed Aggregate Base** 4 6 *1/2- inch nominal aggregate hot -mix asphalt (HMA) per WSDOT 9-03.8 ** Crushed Surfacing Base/Top Course per WSDOT 9-03.9(3) Porous asphalt is being considered for this project. Porous asphalt would allow the water to flow through the pavement surface and into the underlying sandy fill soils. The asphalt thickness for porous pavement would be the same as the regular asphalt. REVIEW AND CONSTRUCTION OBSERVATION SERVICES We should be retained to review the contractor's construction submittal .prior to mobilizing to the site. Our intent would be to help the District decide if an adequate construction plan has been developed for the temporary excavation. We should also be retained to provide observation and consultation services during construction to confirm that the conditions encountered are consistent with those indicated by the explorations, and to provide recommendations for design changes, should the conditions revealed during the work differ from those anticipated. As part of our services, we would also evaluate whether or not earthwork and foundation installation activities comply with contract plans and specifications. USE OF THIS REPORT We have prepared this report for Lakehaven Water and Sewer District and its agents, for use in planning and design of this project. The data and report should be provided to prospective contractors for their bidding and estimating purposes, but our report, conclusions and interpretations should not be construed as a warranty of subsurface conditions. The scope of our services does not include services related to construction safety precautions, and our recommendations are not intended to direct the contractors' methods, techniques, sequences or procedures, except as specifically described in our report, for consideration in design. There are possible variations in subsurface conditions. We recommend that project planning include contingencies in budget and schedule, should areas be found with conditions that vary from those described in this report. Within the limitations of scope, schedule and budget for our services, we have strived to take care that our services have been completed in accordance with generally accepted practices followed in this area at the time this report was prepared. No other conditions, expressed or implied, should be understood. Robinson Noble, Inc. Revised Geotechnical Engineering Report Lakehaven Pump Station 33B Federal Way, Washington January 17, 2019 RN File No. 1529-058A Page 16 We appreciate the opportunity to be of service to you. If there are any questions concerning this report or if we can provide additional services, please call. Sincerely, Robinson Noble, Inc. �y u sf�� :� .Grp"+s _ •'p � "�' NIL, Rick B. Powell, PE Principal Engineer RBP:JRW:am Thirteen Figures Appendices A, B and C Robinson Noble, Inc. +I I I -3 J y �- I VALVE VAULT B-3A I� ae• ss I I I I I � L--------- WET WElL �� GENERATOR TELECTRCAL ROOM OOM B 4 RETAINING WALL w 1 Note: Basemap taken from Enlarged Site Plan PM: RBP ROBINSON" prepared by Carollo September 2018 dated May 2018. 1529-058A NOBLE 'WIDE ACCESS DETAIL XX, SHEET 1� V _ ELECTRICAL X I TRANSFORMER x;x"3/ X f EXISTING PUMP STATION EASEMENT ON PARCEL NO f + li 2921049157 al B-1 I - ODOR CONTROL SYSTEM � f ABOVEGROUND r' DIESEL FUEL TANK I I I I I ?Cr i LEGEND �K -- ----� T-0" WIDE AREA RE FENCENEHICLE R PROVIDED BY BETA B-1 WALL DESIGN E R Number and Approximate Location of Soil Boring Approximate Location of 3" Pipe Piles that should be Removed and the Hole Grouted 0 20 40 Approximate Scale 1" = 20' Figure 2 Site Plan Lakehaven Utility District: Pump Station 33(B) n UNIFIED SOIL CLASSIFICATION SYSTEM MAJOR DIVISIONS GROUP GROUP NAME SYMBOL GRAVEL GW WELL -GRADED GRAVEL, FINE TO COARSE GRAVEL COARSE- CLEAN GRAVEL GP POORLY -GRADED GRAVEL GRAINED MORE THAN 50% OF COARSE FRACTION GRAVEL GM SILTY GRAVEL SOILS RETAINED ON NO.4 WITH FINES SIEVE GC CLAYEY GRAVEL SAND CLEAN SAND SW WELL -GRADED SAND, FINE TO COARSE SAND MORE THAN 50% SP POORLY -GRADED SAND RETAINED ON NO. 200 SIEVE MORE THAN 50% OF COARSE FRACTION SM SILTY SAND PASSES NO.4 SIEVE SAND SC CLAYEY SAND WITH FINES FINE - SILT AND CLAY INORGANIC ML SILT GRAINED CL CLAY SOILS LIQUID LIMIT LESS THAN 50% ORGANIC OL ORGANIC SILT, ORGANIC CLAY SILT AND CLAY INORGANIC MH SILT OF HIGH PLASTICITY, ELASTIC SILT MORE THAN 50% CH CLAY OF HIGH PLASTICITY, FAT CLAY PASSES NO. 200 SIEVE LIQUID LIMIT 50% OR MORE ORGANIC OH ORGANIC CLAY, ORGANIC SILT HIGHLY ORGANIC SOILS PT PEAT NOTES: SOIL MOISTURE MODIFIERS * 1) Field classification is based on Dry -Absence of moisture, dusty, dry visual examination of soil in general to the touch accordance with ASTM D 2488-93. * 2) Soil classification using laboratory Moist- Damp, but no visible water tests is based on ASTM D 2487-93. Wet- Visible free water or saturated, 3) Descriptions of soil density or usually soil is obtained from consistency are based on below water table interpretation of blowcount data, visual appearance, of soils, and/or test data. * Modifications have been applied to ASTM KEY TO BORING LOG SYMBOLS methods to describe sit and clay content. VGround water level N. = NM*CE*CB*CR*CB 0 Blows required to drive NM = blows/foot, measured in field sample 12 in. using SPT (converted to Nso) CE = ER J60, convert measured hammer energy to 60% for comparison with design charts. MC ([:_) _ %Moisture = 3Ym1&af water] CB = adjusts borehole diameter (weight of dry soil) CR = rod length, adjusts for energy loss in rods DID = Dry Density Cs = Sample liner = 1.0 — Letter symbol for soil type sM Contact between soil strata — (Dashed line indicates approximate ML contact between soils) — Letter symbol for soil type NOTE: The stratification lines represent the approximate boundaries between soil types and the transition may be gradual FPM: RBP Figure 3 ROBINSON September 2018 NOBLE 1529-058A Lakehaven Utility District: Pump Station 33(B) Date 2/25/2016 Hole diameter 6 _ a� Standard Penetration Resistance B-1 Logged by KHB Hole depth 43 > (140 Ib. weight, 30" drop) Driller Gregory Well diameter 2.0 �i U `�U) a� �' ♦ SPT N60 (blows/ft) Page 2 of 2 Elevation (ft) 169.1 Well depth 37.0 °C 3 0 `O Moisture Content (%) Sample Liner Yes Hammer Eff. 86% a in o LITHOLOGY / DESCRIPTION cn o z 0 10 20 30 40 50 60 65+ -------17-----»---?•------------ 26 27 Gray silty fine to medium sand with gravel (very dense, SM 10/15 20 28 moist) 24 29 32 Slow drilling 30 31 32 Gray silty fine to coarse sand with gravel (very dense, SM 15/18 24 33 moist) 25 ■ 34 25 Slow drilling 35 36 ------------ 37— Gray fine to coarse sand with gravel and silt (very SP-SM 10/12 31 38 ■ dense, moist) 50/6" Slow drilling 39 40 Mud not heavy enough to maintaing integrity of boring hole, resulting in approximately bottom 6 feet 41 to cave. Driller believes its due to ground water flow 42 No sample driven Boring refusal at 43.0 feet on 2/25/2016 due to caving 43 Well installed to 37.0 feet below ground surface Well screen from 27 to 37 feet 44 Well bedded in sand from 24 to 37 feet Remaining 24 feet bedded with bentonite chips 45 46 47 48 49 50 Phone: 425-488.0599 Fax: 425-488-2330 Lakehaven Utility District - S 359th Street Pump ROBINSON 17625 - 130th Avenue Northeast, Suite 102 NOBLE Woodinville, Washington 98072 1529-058A Figure 5 Date 5/2/2016 Hole dia. (in) 6 _ a) Standard Penetration Resistance B-$ Logged by KHB Hole depth ft 30 a)(140 lb. weight, 30" drop) - Driller Holocene Well dia. (in) 2 0 0 L U `�° a�`� °' ♦ SPT N60 (blows/ft) Page 1 of 2 Elevation (ft) 170.1 Well depth 30 m c o � a Moisture Content W Sample Liner Yes Hammer Eff. 86% a o m g o 0 LITHOLOGY / DESCRIPTION cn o z n 0 10 20 30 40 50 60 65+ v per level measured at +4.L5 teet on May z, 1U1 ti I lil� jlil� 1 O soil I+ Gp i jL 5 Brown sandy silt (very stiff, moist) ML 1/18 4 II it `Blow counts overstated, driving on root 7 11 11 6 11 III II ------?------------- ? ----- -- --- -- III III 7 }� 11 8 Gray silty fine sand with gravel (very dense, moist) SM 12/18 14 " 10 31 II II III 11 35 II II III III III 12 III III III 13 III IIII 14 Gray silty fine to medium sand with gravel and mottling SM 6/18 25 it III 15 (very dense, moist to wet) III I' 16 26 III II III II 17 11 11 II 18 1 1 19 No recovery -?-------------r---- -- 0/5 - 50 1 fIFI ii 20 Gray fine sandy silt with gravel (hard, moist) ML 10/18 17 MM 21 21 11 22 27 I1 ��I� Gray clayey sandy silt trace gravel (hard, moist) ML 6/18 26 23 35 i�i� I{�� 38 M 24 Gray clayey sandy silt (hard, wet) ML 6/12 36 j 11 50/6 fill 25 0 ■ ■ Phone: 425-488-0599 �] Fax: 425ABB-2330 Lakehaven Utility District - S 359th Street Pump ROBINSON 17625- 130th Avenue Northeast, Suite 102 1529-058A Figure 7 NOBLE Woodinville, Washington 98072 Date 5/2/2016 Hole diameter 6 — a) Standard Penetration Resistance „s B-$ ,- Logged by KHB Hole depth 30 > � r a) P (140 lb. weight, 30" drop) Driller Gregory Well diameter 2 ci a) v `��,° • SPIT N60 (blows/ft) Page 2 of 2 Elevation (ft) 170.1 Well depth 30.0 aa) °C c 3 0 E= Moisture Content (%) Sample Liner Yes Hammer Eff. 86% m m z p z 0 10 20 30 40 50 60 65+ LITHOLOGY / DESCRIPTION o INo recovery 0/10 47 !1' I'll' _______ _ 50/4 n1 III nVI it 26 Gray silty fine sand with gravel (dense, SM 9/18 14 I'll' I'll I„ moist) 16 �'f u1 27 19 +!i o i� Gray silty fine sand with gravel (very SM 12/18 7 iiti of 28 dense, moist) 26 27 29 Gray silty fine to coarse sand (very dense, moist) SM 4/6 50/6 30 Boring was completed at 30 feet on 4/29/2016 Well screen was installed from 28' to 30' 31 Sand from 28' to 30' and 2-inch diameter PVC Pipe 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49J. 50 ` ! Phone: 425-488-0599 Fax: 425-488-2330 Lakehaven Utility District - S 359th Street Pump ROBINSON 17625- 130th Avenue Northeast, Suite 102 1529-058A Figure 8 NOBLE Woodinville, Washington 98072 Date 5/2/2016 Hole dia. (in) 6 2 U) Standard Penetration Resistance B-3A Logged by KHB Hole depth ft 21 > — (140 lb. weight, 30" drop) Driller Holocene Well dia. (in) 2 ci � v `QU) �' ♦ SPT N60 (blows/ft) Page 1 of 1 Elevation (ft) 169.7 Well depth 21 D c o o cc Q © Moisture Content M Sample Liner Hammer Eff. a a m : o LITHOLOGY / DESCRIPTION Vn o z n 0 10 20 30 40 50 60 65+ Drilled -3 feet south of boring B-3 No samples were taken Installed 2-inch diameter PVC pipe with screen from 19' to 21' and sand from 19' to 21' Water level measured at +0.4 feet on May 2, 2016 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16- 17- 18- 19• 20 21 22 23 24 25 Phone: 425-488-0599 Fax: 425-488-2330 Lakehaven Utility District - S 359th Street Pump IROBINSON 17625- 130th Avenue Northeast, Suite 102 NOBLE Woodinville, Washington 98072 1529-058A Figure 9 Date 5/2/2016 Hole dia. (in) 6 -- a Standard Penetration Resistance B-4 ,- Logged by KHB Hole depth ft 27.5 0 FU o (140 lb. weight, 30' drop) Driller Holocene Well dia. (in) 2 b U ; ai ♦ SPT N60 (blows/ft) Page 1 of 2 Elevation (ft) 166.9 Well depth 27.5 `n °C c 3 0 _ Moisture Content M Sample Liner Yes Hammer Eff. 86% a � m g � p zcn 0 10 20 30 40 50 60 65+ LITHOLOGY /DESCRIPTION cn o Water level measured at +2.4 feet on May 2, 2016 I } Topsoil II III II II 1 IIII III 2 I} } }I I 3- 4- 5— Blue-gray clayey silt (soft, moist) ML 8/18 3 ' } 1 2 If }I III 11 6 --------?-----------?•------ -- --- -- I#I IIII 7 III III II I 8 I} }II I1 9 III III 10 Gray silty fine sand with gravel (dense, moist) SM 12/18 20 II ill Several pieces of quartz 21 II II 11 r 28 II II IIIIll I II IIII 12 I } III '{ 13 I1I 4I 14 I1 I}I 15 Gray silty fine sand with gravel and cobbles (?) SM 13/18 25 III (very dense, moist) 25 }I I 16 ■ 36 {}il I}I II II III` 17 I I� 18 I 41 n 19 IIII 20 No recovery 0 18 / 31 }III II 41 III IIII 21 ?-----------?----- - - --- 38 1I ,I4 v Gray silt with fine sand (hard, moist) ML 15/18 43 IIII 22 28 29 IIII I44 23 Gray silt with gravel (hard, moist) ML 12/18 28 IIII II 48 II I 24 39 II --.__.----------------.------ — --- -- 25 Phone: 425-488-0599 �� Fax: 425-488-2330 Lakehaven Utility District - S 359th Street Pump ROBINSON 17625 - 130th Avenue Northeast, Suite 102 1529-058A Figure 10 NOBLE Woodinville, Washington 98072 Date 5/2/2016 Hole diameter 6 c Standard Penetration Resistance B-4 Logged by KHB Hole depth 27.5 °' (140 lb. weight, 30" drop) Driller Gregory Well diameter 2 b a U U) ♦ SPT N60 (blows/ft) Page 2 of 2 Elevation (ft) 166.9 Well depth 27.5 o o co a Moisture Content M Sample Liner Yes Hammer Eff. 86% m g 0 a) LITHOLOGif / DESCRIPTION o z �;, 0 10 20 30 40 50 60 65+ Gray silty fine to coarse sand with gravel (very dense, moisl SM 10/18 13 41 26 ■ 38 Gray silty fine to coarse sand with gravel (very dense, SM 6/12 38 moist) 50/6 27 28 Boring was completed at 27.5 feet on 4/26/2016 Well screen was installed from 25.5' to 27.5', sand from 25.5' to 27.5' and 2-inch diameter PVC pipe 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 Phone: 425-48&0599 IBM Fax: 425-48&2330 Lakehaven Utility District - S 359th Street Pump ROBINSON 17625 -130th Avenue Northeast, Suite 142 1529-058A Figure 11 NOBLE Woodinville, Washington 98072 I O O O O O O O O O O O O O O O O O O O O Iq O U1 O V1 O VY O Lq O Li O Lq O V1 O Ln O LO RTI-* m M N N ri r4 O O m m co co 1, 1- 10 lO n n ^ n n n n n n n n w w w w w w w w ri r-1 r-I r-1 r'1 r-I r-I ri ri H H ri ri ri ri r-1 r♦ a-1 r-I (4) uollenal3 8 O N 14 O O O pO N O N N O T 1rcu _0) CY) Cl) LL. � E a L a) 3 a) U) U �L co 0 }1 0 C i a) Y fu J O 0 N Q m N O d Cn Lateral Soil Pressure QW = 13O pCT 0=38' Soft crey05 pcf 6 b = 33 pcf (=17' C = 100 psf Wig= 24° _. . Silty sand 6w = 135 pcf 6b=73pcf 0=38' Clayey silt 6w = 120 pcf 6b=58pcf (=28' c=250psf_ Silty sand 6w = 135 pcf 6b=73pcf (=32' c = 1,000 psf 0. = 36' Planned grade (0' to 4') EFWa = 33 pcf Ska = UH pst EFWo = 53 pcf Sko = 14H psf Ground surface = 0' _A_ _ . _7, EFWa = 18 pcf* EFWo = 26 pcf* Ska = 9H psf Sko = 14H psf —-----22' — — i _ _ -37' *Buoyant condition 6w = estimated unit weight of soil 6b = estimated buoyant weight of soil 0 = estimated friction angle c = estimated cohesion (should not be used for side friction) (DR = estimated friction angle with 0 cohesion EFWa = estimated equivalent fluid weight - active condition EFWo = estimated equivalent fluid weight - non -yielding condition Ska = seismic kicker - active Sko = seismic kicker - non -yielding ROBINSON- NOBLE PM: RBP September 2018 1529-058A Detail A Stress Caused by Point Load Determine Q from H-20 loading QP (Point Load) for m < 0.4 QH (H2/t+CP) (0.16 +znz)3 for m > 0.4 1 77mZnZ QH (H2/QP) =(m2 + n2)3 Q'H= 6HCOS 2(1.16) Reference: Figure 11 NAVFAC DM7.02 page 74. (A) 62.4 x 34.3' = 2,140 psf ©62.4 x 56.3' = 3,513 psf Groundwater Pressure Diagram 4.3' Fill Soft clayey silt Planned grade (0' to 4') \ — — — — — — — — — — — — — — — -7' Silty sand — 62.4 pcf — --22' Clayey silt--T--__�— __----- --------- -28' Silty sand ----- -- --- ---- --- -30' 200 pcf — Sand and gravel -37' 62.4 pcf Figure 13 Pressure Diagrams Lakehaven Water and Sewer District: Pump Station 33(B) Appendix A Laboratory Testing Atterberg Limits Date Received: Project: 1529-058A Sample #: Location: Federal Way Sample ID: Boring #: B-1 Source: Depth: 23.00 ASTM D-2487, Unified Soils Classification System No Data Provided Liquta uirmy metermmauon #1 #2 #3 #4 #5 #6 Weight of Wet Soils +Pan: 18.80 16.30 19.70 Weight of Dry Soils + Pan: 17.30 15.50 18.20 Weight of Pan: 11.00 11.10 11.00 Weight of Dry Soils: 6.30 4.40 7.20 Weight of Moisture: 1.50 0.80 1.50 % Moisture: 23.8 % 18.2 % 20.8 % N: 16 39 22 Liquid Limit @ 25 Blows: 21.1 % Plastic Limit: 17.8 % Plasticity Index, Ip: 3.3 % Plastic Limit Determination #1 Weight of Wet Soils + Pan: 14.30 Weight of Dry Soils + Pan: 13.80 Weight of Pan: 11.10 Weight of Dry Soils: 2.70 Weight of Moisture: 0.50 % Moisture: 18.5 % #2 #3 #4 14.30 16.30 16.20 13.80 15.60 15.40 11.10 11.10 11.10 2.70 4.50 4.30 0.50 0.70 0.80 18.5 % 15.6 % 18.6 % #5 #6 Plasticity Chart r Liquid Limit 30% 25% 5% - 0% •1 - 10 Number of Blows, "N" 100 80.0 Rio 70.0 % 60.0 % "U" Line 'K Un6 x 50.0 % f d a c ! CH or OH �. 40.0 % W - d 30.0 % MH or OH 20.0 % rrn CL or OL 10.0 % I 0.0 % 0.0% 10.0% 20.0% 30.0% 40.0% 50.0% 60.0% 70.0% 80.0% 90.0% 100.0% 110.0% Liquid Limit Page 1 U.S. Standard Sieve Opening in Inches U.S. Standard Sieve Numbers Hydrometer Results 100% 20 15 4 8 1h 'A 1S % #4 10 16 20 30 40 50 100 200 0% 90% 10% 80% 20% 70% Z M 30% t 60% - 40% 'm 50% rn c 50% 40% � 60% M a 30% 0 N 70% Ix 20% 0 80% 10% 90% 0% 100% 1000 100 10 1 0.1 0.01 0.001 Grain Size in Millimeters Gravels San Cobbles Date: 04 9 i D10= 0.04 LISCS Classification % rave /o an HydrometerResrrlls Sample #: D30 = 0.24 SM, Silty Sand with Grav 36.5% 44.9% Size, mm % Pawing Sample ID: D60 = 3.97 Specifications 0.074 #N/A Source: Cc = 0.36 No Specs 0.050 #N/A Project: Pump Station Cu- 98.52 Sample Meets Specs % Silt & Clay 0.020 #N/A Location: Lakehaven Liquid Limit= n/a No 18.6% 0.005 #N/A Boring #: 3 Plastic Limit-- n/a Fineness Modulus % Silt - % Clay 0.002 #N/A Depth: 10.00 Plasticity Index-- n/a 3.78 #N/A #N/A 0.001 #N/A Coarse ctua interpolated roes clue Interpolated Section Cumulative Cumulative Section Cumulative Cumulative ]eve Size Percent Percent pets pets leve ixe Percent Percent pets pets US Metric Passing Passing Max Min US Metric Passing Passing Max Min 6.0 " 156.00 IO /o #4 4.750 63.5% 63.5% 4.00" 100.00 100.0% #8 2.360 52.8% 3.00" 75.00 100.0% #10 2.000 51.2% 51.2% 2.50" 63.00 100.0% #16 1.180 45.7% 2.00" 50.00 100.0% #20 0.850 43.4% 43.4% 1.75" 45.00 100.0% #30 0.600 39.8% 1.50" 37.50 100.0% #40 0.425 37.2% 37.2% 1.25" 31.50 100.0% #50 0.300 32.5% 1.00" 25.00 100.0% #60 0.250 30.7% 30.7% 7/8" 22.40 100.0% 100.0% #80 0.180 26.5% 3/4" 19.00 90.4% 90.4% #100 0.150 24.6% 24.6% 5/8" 16.00 84.8% #140 0.106 21.1% 1/2" 12.50 78.1% #170 0.090 19.8% 3/8" 9.50 72.5% #200 0.075 18.6% 18.6% 1/4" 6.30 66.4% #270 0.053 #4 4.75 63.5% 63.5% CopynghtlSpears sngitt rft & Technical Srnices PS, 1996-2005 ds Silts Clays Coarse Fine Coarse Medium Tine Appendix B USGS Design Maps Summary Report 5/21/2018 Design Maps Summary Report � Design Maps Summary Report User -Specified Input Building Code Reference Document 2012/2015 International Building Code (which utilizes USGS hazard data available in 2008) Site Coordinates 47,278990N, 122.32109'W Site Soil Classification Site Class D — "Stiff Soil" Risk Category I/II/III - - Keffl - i�jJ[a �ul�'�tti11<' JY - Federal Way. rA RPM c 4 a - 5ity Ptac+� w �` _ Pwan p USGS--Provided Output Ss = 1.279 g 5Ms = 1.279 g SIDS = 0.853 g SI = 0.492 g SMI = 0.742 g SDI = 0.495 g For information on how the SS and S1 values above have been calculated from probabilistic (risk -targeted) and deterministic ground motions in the direction of maximum horizontal response, please return to the application and select the " 2009 NEHRP" building code reference document. MCE,t Response Spectrum 1,41 11.30 ] 17 1111 U.yl � D.Y71 � nas Ir. oS2 nay l�lt� VAN' 11.2- n.L- am obi 11■1 I -a' J.4• Ib. 120• 3ftl Pcrw. ? Iscrt DesIgn Response Spectrum o:n IM oat U T2 UN `( CUM 4J 0.45 036 o.� u.IN nl>+ UPI- m.31 u.1I• mir- DO, Ifx, 121- IA- J101 1.4- 2m Although this information is a product of the U.S. Geological Survey, we provide no warranty, expressed or Implied, as to the accuracy of the data contained tnerein. This tool Is not a substitute for technical subject -matter knowledge. h tips J/earthquake.usgs, gov/cn i/desig n ma ps/usfsumma ry.php7 template=minimal&latitude=47.27899&longitude=-122.32109&sileclass=3&riskcategory=0&edition= Appendix C MSE Wall Design SPECIFICATIONS FOR REINFORCED SOIL RETAINING WALL WITH MESA BLOCK FACING General: 1. The contractor shall have an approved set of plans and specifications on site at all times during the construction of the wall. The wall layout is the responsibility of the contractor. 2. A professional engineer or representative should observe and monitor the construction of the wall. 3. Tensar UX1400MSE, or equivalent shall be used for this project. All geosynthetic reinforcement and facing materials shall be approved by the geotechnical engineer prior to installation. 4. Mesa Blocks shall be used in all of the walls. Other block type must be approved by the geotechnical engineer if considered. The reinforcement lengths are measured from the front face of the block. 5. The contractor may use longer geosynthetic reinforcement lengths than the design sections for ease of construction. The reinforcement lengths may not be shorter unless approved by the geotechnical engineer. Subgrade Preparation: 1. The ground should be prepared by removing surficial unsuitable soil, down to medium dense, inorganic, native soils as approved by the geotechnical engineer. 2. The cross section detail shows the 2 to 4 inch quarry spalls backfill if the geotechnical engineer determines additional excavation is required. 3. The excavation shall be cleaned of all excess material and protected, as necessary, from construction traffic to maintain the integrity of the subgrade. 4. The top of the spalls should be capped with appropriate graded material to prevent migration of soils above. 5. A leveling pad consisting of compacted crushed rock or concrete, shall be used under the blocks. 6. The base of the excavation should be deep enough to satisfy the minimum embedment of 2 feet. Geosynthetic Reinforcement Placement: 1. The reinforcement shall be rolled out, cut to length, and laid at the proper elevation, location, and orientation. Orientation of the reinforcement is of extreme im- portance since geosynthetic reinforcements vary in strength with roll direction. The contractor shall be responsible for the correct orientation. 2. Geosynthetic reinforcement shall be at the top of the bottom block and then every 1.33 feet thereafter. The top layer shall be a minimum of 2 feet below the final surface grade. The reinforcement length is measured from the front face of the Mesa Block. 3. Geosynthetic reinforcement shall be fastened between the facing blacks. Prior to placing the fill, the reinforcement shall be pulled to remove the slack and stretched by hand until taut and free of wrinkles. 4. Geosynthetic reinforcement and facing material shall be placed in accordance with the manufacturer's recommendations. Fill Placement: 1. Structural fill, consisting of granular import soils or on -site material with no greater than 3/4 inch in size, would then be placed upon the subgrade and geosynthetic reinforcement. If larger rock is used in the fill, additional layers of reinforcement may need to be used in the reinforcement. The contractor shall prevent damage to the geosynthetic reinforcement by placing the first lift of structural fill with at least a 1-foot thickness. The geotechnical engineer shall approve the material to be placed in the reinforced zone, before placement. 2. Structural fill should have parameters equal to or better than those stated for the reinforced wall fill. 3. Soil density tests should be performed as designated by the geotechnical engineer. 4. Fill soils in the wall area shall be compacted to at least 95% of the Maximum Dry Density (MDD) as determined by ASTM D-1557 Maximum Dry Density. 5. The soil shall be placed in relatively uniform horizontal lifts not exceeding 10 or 12 inches in thickness. The lift thickness shall not exceed the manufacturer's recom- mended depth for the compactive device used on the project. Drainage: 1. Drainage of reinforced wall is critical to the design. A specific drainage system is shown on the plans. Changes to the drainage system should be approved by the engineer prior to placement. 2. A drainage blanket with a minimum width of 12 inches should be installed directly behind the blocks and shall consist of 5/8-inch crushed rock or angular free -draining material. All of the drainage material shall have a fines content no greater than 5% passing the number 200 sieve. 3. Surface water shall not be allowed to pond in or near the reinforced fill zone during or after construction. Design Parameters: Reinforced Wall Fill; 0 =38 degrees, y = 135 PCF, c = 0 Retained Backfill; m = 38 degrees, y = 135 PCF, c = 0 Foundation Soil; m=45 degrees, y = 135 PCF, c = 0 External Loading: 2,000 PSF for 5.0' from wall face Seismic Acceleration = 0.44g (lateral deflection estimated to be about 4 inch) Factor of Safety per AASHTO 2015 Inspection: The construction shall be periodically inspected under the direction of an engineer registered in the state of Washington with experience in the design of reinforced earth retaining walls. PM: RBP September 2018 1529-058A PLACE TWO MESA STANDARD CONNECTORS AT EVERY MESA STANDARD UNIT WHERE A GEOGRID LAYER IS NOT ATTACHED, ORIENTED FOR NEAR VERTICAL ALIGNMENT TRIM FINGERS IN FRONT OF TRANSVERSE BAR I 1 MESA STANDARD CONNECTOR i I DRIVE CONNECTOR FINGERS THROUGH THE GEOGRID APERTURES BEHIND THE NOMINAL SETBACK 1116" 1 I I I FIRST TRANSVERSE BAR TENSAR STRUCTURAL GEOGRID MESA STANDARD UNIT LPLACE TRANSVERSE BAR AGAINST MESACONNECTOR SHIM BETWEEN BLOCK COURSES AS NECESSARY TO MAINTAIN PROPER VERTICAL AND HORIZONTAL ALIGNMENT. SEE GEOGRID ORIENTATION DETAIL FOR SHIMMING DETAILS. MESA STANDARD UNIT AND GEOGRID CONNECTION DETAIL FOR NEAR VERTICAL ALIGNMENT NOT TO SCALE Figure C1 Block Wall Details ROBINSON` NOBLE Lakehaven Utility District: Sewer Pump Station c� w5; J (.0 Q OO 2' MIN TYPICAL BLOCK WALL CROSS-SECTION (not to scale) 5/8-INCH CRUSHED ROCK- - MESA BLOCK (PER MANUFACTURER 1 RECOMMENDATION) -- - - SEE CONNECTION DETAIL, 16 FIGURE C1 SUBDRAIN OUTLETTO DISCHARGE POINT - -------__ COMPACTED CRUSHED ROCK LEVELING PAD--- _5' TO BE DETERMINED IN FIELD STEEL SHEET PLATES COULD BE USED TO SEPARATE WETLAND FROM EXCAVATION - — - - -- - 1 PM: RBP ROBINSON September 2018 NOBLE 1529-058A --6' HIGH FENCE E GEOSYNTHETIC REINFORCEMENT LENGTH = 8 FEET 1 1 2,000 PSF 5' MINIMUM 7�r " . BACKFILL: GRANULAR SOIL (D= 38 --- - . - C - ff ��- STRUCTURAL FILL -`a 135 psf _ -- - - - - TENSAR UX140OMSE REINFORCEMENT OR EQUIVALENT- PLACED EVERY 2 BLOCKS (1.33') :co QQo 6„ (max) ❑" v U P 3 U v� v� u a ti 4 00 az)oa 000 °De a o �a 4 Oa a 24" (min) 1 ❑ d QD°d' c a'&G' 'moo° 17ooaQ�a°QoDn00 adocjc na0Dn00c) a0c)300 z3bo p�Oa o�Qo p�0a oaao 07M OEM 0WO 07�00 01}C o ❑ Op QC] d� �� d� og d� �a d� rap do op Oe �aad oQ O` Q q°°°°qt �D�00Q a0Q 000 v0QOv00a000 E?0C) v0Q E?C)O zjOooa0oa�0aoo0aobOoa�Oa0�Ocoa0ar)a0aoIjc o9 - ap'O- a❑"dam Q0 0 `g '�no°oo°ao°000469° �° ° ° co0a00- °09t VERY DENSE SITLY SAND 2TO 4 INCH QUARRY SPALLSTO BE PLACED ON THE UNDERLYING GRAY SILTY SAND AND CAPPED WITH GRANULAR SOIL. FILTER FABRIC IS REQUIRED ON THE SIDES OFTHE EXCAVATION IF COMPLETE PAD OVEREXCAVATION DOES NOT OCCUR. GEOTECHNICAL ENGINEER SHALL APPROVE BEARING SOIL. 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Pavement Width: 50.00 ft. Pavement slope 1:0.02 To 1 Pavement thickness: 0.5 Pour Space of Pavement: 0.25 Material thickness of second layer: 0.1667 Pour Space of material for second layer: 0.3 Material thickness of third layer: 2 Pour Space of material for third layer: 0.4 Infiltration On Infiltration rate: 0.01 Infiltration safety factor: 1 Total Volume Infiltrated (ac-ft.): 20.648 Total Volume Through Riser (ac-ft.): 0.735 Total Volume Through Facility (ac-ft.): 21.384 Percent Infiltrated: 96.56 Total Precip Applied to Facility: 0 Total Evap From Facility: 3.461 Element Flows To: Outlet 1 Outlet 2 Permeable Pavement Hydraulic Table Stage(feet) Area(ac.) Volume(ac-ft.) Discharge(cfs) Infilt(cfs) 0.0000 0.093 0.000 0.000 0.000 0.0419 0.093 0.001 0.000 0.000 0.0837 0.093 0.003 0.000 0.000 0.1256 0.093 0.004 0.000 0.000 0.1674 0.093 0.006 0.000 0.000 0.2093 0.093 0.007 0.000 0.000 0.2511 0.093 0.009 0.000 0.000 0.2930 0.093 0.010 0.000 0.000 0.3348 0.093 0.012 0.000 0.000 0.3767 0.093 0.014 0.000 0.000 0.4185 0.093 0.015 0.000 0.000 0.4604 0.093 0.017 0.000 0.000 0.5022 0.093 0.018 0.000 0.000 0.5441 0.093 0.020 0.000 0.000 0.5859 0.093 0.021 0.000 0.000 0.6278 0.093 0.023 0.000 0.000 0.6696 0.093 0.024 0.000 0.000 0.7115 0.093 0.026 0.000 0.000 0.7533 0.093 0.028 0.000 0.000 0.7952 0.093 0.029 0.000 0.000 0.8370 0.093 0.031 0.000 0.000 0.8789 0.093 0.032 0.000 0.000 0.9207 0.093 0.034 0.000 0.000 0.9626 0.093 0.035 0.000 0.000 1.0045 0.093 0.037 0.000 0.000 1.0463 0.093 0.038 0.000 0.000 1.0882 0.093 0.040 0.000 0.000 1.1300 0.093 0.042 0.000 0.000 1.1719 0.093 0.043 0.000 0.000 LS33B_porous asphalt -Site model -historical site 12/10/2019 4:09:49 PM Page 8 1.2137 0.093 0.045 0.000 0.000 1.2556 0.093 0.046 0.000 0.000 1.2974 0.093 0.048 0.000 0.000 1.3393 0.093 0.049 0.000 0.000 1.3811 0.093 0.051 0.000 0.000 1.4230 0.093 0.052 0.000 0.000 1.4648 0.093 0.054 0.000 0.000 1.5067 0.093 0.056 0.000 0.000 1.5485 0.093 0.057 0.000 0.000 1.5904 0.093 0.059 0.000 0.000 1.6322 0.093 0.060 0.000 0.000 1.6741 0.093 0.062 0.000 0.000 1.7159 0.093 0.063 0.000 0.000 1.7578 0.093 0.065 0.000 0.000 1.7996 0.093 0.067 0.000 0.000 1.8415 0.093 0.068 0.000 0.000 1.8834 0.093 0.070 0.000 0.000 1.9252 0.093 0.071 0.000 0.000 1.9671 0.093 0.073 0.000 0.000 2.0089 0.093 0.074 0.000 0.000 2.0508 0.093 0.075 0.000 0.000 2.0926 0.093 0.076 0.000 0.000 2.1345 0.093 0.077 0.000 0.000 2.1763 0.093 0.078 0.000 0.000 2.2182 0.093 0.079 0.000 0.000 2.2600 0.093 0.080 0.000 0.000 2.3019 0.093 0.081 0.000 0.000 2.3437 0.093 0.082 0.000 0.000 2.3856 0.093 0.083 0.000 0.000 2.4274 0.093 0.084 0.000 0.000 2.4693 0.093 0.085 0.000 0.000 2.5111 0.093 0.086 0.000 0.000 2.5530 0.093 0.087 0.000 0.000 2.5948 0.093 0.088 0.000 0.000 2.6367 0.093 0.089 0.000 0.000 2.6785 0.093 0.093 0.000 0.000 2.7204 0.093 0.097 0.000 0.000 2.7622 0.093 0.101 0.000 0.000 2.8041 0.093 0.105 0.120 0.000 2.8460 0.093 0.109 0.371 0.000 2.8878 0.093 0.112 0.701 0.000 2.9297 0.093 0.116 1.095 0.000 2.9715 0.093 0.120 1.543 0.000 3.0134 0.093 0.124 2.039 0.000 3.0552 0.093 0.128 2.580 0.000 3.0971 0.093 0.132 3.161 0.000 3.1389 0.093 0.136 3.781 0.000 3.1808 0.093 0.140 4.436 0.000 3.2226 0.093 0.144 5.125 0.000 3.2645 0.093 0.148 5.847 0.000 3.3063 0.093 0.151 6.600 0.000 3.3482 0.093 0.155 7.382 0.000 3.3900 0.093 0.159 8.193 0.000 3.4319 0.093 0.163 9.032 0.000 3.4737 0.093 0.167 9.898 0.000 3.5156 0.093 0.171 10.79 0.000 3.5574 0.093 0.175 11.70 0.000 3.5993 0.093 0.179 12.64 0.000 LS33B_porous asphalt site model historical site 12/10/2019 4:09:49 PM Page 9 3.6411 0.093 0.183 13.61 3.6830 0.093 0.187 14.60 3.7248 0.093 0.190 15.61 LS336_porous asphalt —site model historical site 12/10/2019 4:09:49 PM Page 10 Analysis Results POC 1 0 0.06 RB 0.04 0 IL 0.02 — 00i10E5 10E-4 10E-3 10E-2 WE 1 10 100 Percent Time Exceeding + Predeveloped Predeveloped Landuse Totals for POC #1 Total Pervious Area: 0.218 Total Impervious Area: 0 Mitigated Landuse Totals for POC #1 Total Pervious Area: 0.061 Total Impervious Area: 0.156975 c.er�axsr� o1 001 oat c ooe I` 099� . I a o991 9 a9o1 0.5 1 9 10 .'0 ]J >a H 90 x Mitigated Flow Frequency Method: Log Pearson Type III 17B Flow Frequency Return Periods for Predeveloped. POC #1 Return Period Flow(cfs) 2 year 0.015551 5 year 0.034565 10 year 0.047629 25 year 0,062811 50 year 0.072714 100 year 0,081339 Flow Frequency Return Periods for Mitigated. POC #1 Return Period Flow(cfs) 2 year 0.006096 5 year 0.016888 10 year 0.030086 25 year 0.057664 50 year 0.089505 100 year 0.134683 Annual Peaks Annual Peaks for Predeveloped and Mitigated. POC #1 Year Predeveloped Mitigated 1949 0.014 0.004 1950 0.044 0.062 1951 0.047 0.051 1952 0.012 0.004 1953 0.008 0.018 1954 0.022 0.006 1955 0.032 0.008 1956 0.028 0.039 1957 0.009 0.003 1958 0.013 0.004 LS33B_porous asphalt —site model —historical site 12/10/2019 4:09:49 PM Page 11 1959 0.016 0.020 1960 0.027 0.007 1961 0.026 0.030 1962 0.000 0.001 1963 0.015 0.004 1964 0.021 0.028 1965 0.038 0.009 1966 0.008 0.003 1967 0.046 0.058 1968 0.007 0.002 1969 0.024 0.006 1970 0.010 0.003 1971 0.016 0.004 1972 0.043 0.040 1973 0.017 0.005 1974 0.016 0.016 1975 0.024 0.006 1976 0.021 0.006 1977 0.007 0.002 1978 0.004 0.002 1979 0.011 0.003 1980 0.002 0.006 1981 0.005 0.002 1982 0.025 0.006 1983 0.010 0.003 1984 0.025 0.006 1985 0.002 0.001 1986 0.003 0.002 1987 0.021 0.006 1988 0.000 0.001 1989 0.006 0.002 1990 0.014 0.004 1991 0.049 0.011 1992 0.005 0.002 1993 0.002 0.001 1994 0.000 0.001 1995 0.016 0.005 1996 0.042 0.052 1997 0.032 0.020 1998 0.018 0.005 1999 0.026 0.047 2000 0.026 0.006 2001 0.001 0.001 2002 0.015 0.015 2003 0.012 0.004 2004 0.012 0.004 2005 0.021 0.006 2006 0.029 0.038 2007 0.073 0.077 2008 0.051 0.012 2009 0.035 0.009 Ranked Annual Peaks Ranked Annual Peaks for Predeveloped and Mitigated. POC #1 Rank Predeveloped Mitigated 1 0.0734 0.0768 2 0.0510 0.0624 3 0.0489 0.0576 LS3313_porous asphalt -Site model historical site 12/10/2019 4:10:31 PM Page 12 4 0.0469 0.0523 5 0.0458 0.0511 6 0.0444 0.0469 7 0.0431 0.0397 8 0.0423 0.0391 9 0.0378 0.0380 10 0.0354 0.0297 11 0.0320 0.0284 12 0.0318 0.0204 13 0.0292 0.0195 14 0.0283 0.0182 15 0.0275 0.0158 16 0.0259 0.0147 17 0.0256 0.0120 18 0.0256 0.0114 19 0.0250 0.0090 20 0.0250 0.0087 21 0.0239 0.0078 22 0.0239 0.0068 23 0.0225 0.0064 24 0.0214 0.0063 25 0.0213 0.0063 26 0.0212 0.0061 27 0.0210 0.0061 28 0.0182 0.0060 29 0.0173 0.0058 30 0.0164 0.0056 31 0.0162 0.0056 32 0.0161 0.0056 33 0.0156 0.0048 34 0.0152 0.0047 35 0.0149 0.0045 36 0.0145 0.0044 37 0.0143 0.0043 38 0.0133 0.0041 39 0.0125 0.0041 40 0.0116 0.0038 41 0.0116 0.0037 42 0.0115 0.0035 43 0.0098 0.0035 44 0.0097 0.0034 45 0.0095 0.0032 46 0.0081 0.0031 47 0.0080 0.0030 48 0.0070 0.0027 49 0.0066 0.0025 50 0.0058 0.0023 51 0.0055 0.0023 52 0.0047 0.0023 53 0.0042 0.0020 54 0.0030 0.0019 55 0.0024 0.0017 56 0.0022 0.0015 57 0.0020 0.0014 58 0.0015 0.0013 59 0.0005 0.0011 60 0.0004 0.0011 61 0.0004 0.0010 LS33B_porous asphalt -site mode l_historicaI site 12/10/2019 4:10:31 PM Page 13 LS33B_porous asphalt —site model —historical site 12/10/2019 4:10:31 PM Page 14 Duration Flows Flow(cfs) Predev Mit Percentage Pass/Fail 0.0078 1948 1944 99 Pass 0.0084 1717 1778 103 Fail 0.0091 1518 1632 107 Fail 0.0097 1354 1490 110 Fail 0.0104 1209 1377 113 Fail 0.0111 1079 1261 116 Fail 0.0117 980 1181 120 Fail 0.0124 886 1087 122 Fail 0.0130 793 1003 126 Fail 0.0137 718 941 131 Fail 0.0143 657 881 134 Fail 0.0150 591 825 139 Fail 0.0156 541 765 141 Fail 0.0163 486 714 146 Fail 0.0170 432 681 157 Fail 0.0176 389 646 166 Fail 0.0183 352 611 173 Fail 0.0189 325 572 176 Fail 0.0196 300 534 178 Fail 0.0202 280 500 178 Fail 0.0209 260 470 180 Fail 0.0216 232 435 187 Fail 0.0222 207 402 194 Fail 0.0229 188 373 198 Fail 0.0235 168 343 204 Fail 0.0242 149 317 212 Fail 0.0248 139 302 217 Fail 0.0255 129 283 219 Fail 0.0261 119 263 221 Fail 0.0268 109 249 228 Fail 0.0275 102 234 229 Fail 0.0281 93 217 233 Fail 0.0288 87 202 232 Fail 0.0294 76 196 257 Fail 0.0301 65 180 276 Fail 0.0307 61 167 273 Fail 0.0314 59 155 262 Fail 0.0320 54 140 259 Fail 0.0327 50 133 266 Fail 0.0334 44 117 265 Fail 0.0340 41 104 253 Fail 0.0347 37 97 262 Fail 0.0353 35 87 248 Fail 0.0360 32 82 256 Fail 0.0366 30 76 253 Fail 0.0373 28 69 246 Fail 0.0379 24 66 275 Fail 0.0386 20 61 305 Fail 0.0393 20 52 260 Fail 0.0399 17 47 276 Fail 0.0406 16 42 262 Fail 0.0412 14 41 292 Fail 0.0419 14 36 257 Fail 0.0425 10 32 320 Fail LS33B_porous asphalt -Site model historical site 12/10/2019 4:10:31 PM Page 15 0.0432 7 32 457 Fail 0.0439 7 32 457 Fail 0.0445 6 29 483 Fail 0.0452 6 27 450 Fail 0.0458 6 26 433 Fail 0.0465 5 24 480 Fail 0.0471 4 22 550 Fail 0.0478 4 20 500 Fail 0.0484 4 15 375 Fail 0.0491 3 15 500 Fail 0.0498 3 14 466 Fail 0.0504 3 14 466 Fail 0.0511 2 13 650 Fail 0.0517 2 11 550 Fail 0.0524 2 10 500 Fail 0.0530 2 10 500 Fail 0.0537 2 10 500 Fail 0.0543 2 10 500 Fail 0.0550 2 8 400 Fail 0.0557 2 8 400 Fail 0.0563 2 7 350 Fail 0.0570 2 7 350 Fail 0.0576 2 6 300 Fail 0.0583 2 6 300 Fail 0.0589 2 6 300 Fail 0.0596 2 6 300 Fail 0.0603 2 6 300 Fail 0.0609 2 6 300 Fail 0.0616 2 5 250 Fail 0.0622 2 4 200 Fail 0.0629 1 3 300 Fail 0.0635 1 3 300 Fail 0.0642 1 3 300 Fail 0.0648 1 3 300 Fail 0.0655 1 3 300 Fail 0.0662 1 3 300 Fail 0.0668 1 3 300 Fail 0.0675 1 3 300 Fail 0.0681 1 3 300 Fail 0.0688 1 3 300 Fail 0.0694 1 2 200 Fail 0.0701 1 2 200 Fail 0.0707 1 2 200 Fail 0.0714 1 2 200 Fail 0.0721 1 2 200 Fail 0.0727 1 2 200 Fail The development has an increase in flow durations from 1/2 Predeveloped 2 year flow to the 2 year flow or more than a 10% increase from the 2 year to the 50 year flow. The development has an increase in flow durations for more than 50% of the flows for the range of the duration analysis. LS33B_porous asphalt site model historical site 12/10/2019 4:10:31 PM Page 16 Water Quality Water Quality BMP Flow and Volume for POC #1 On-line facility volume: 0 acre-feet On-line facility target flow: 0 cfs. Adjusted for 15 min: 0 cfs. Off-line facility target flow: 0 cfs. Adjusted for 15 min: 0 cfs. LS33B_porous asphalt —site model historical site 12/10/2019 4:10:31 PM Page 17 LID Report LID Technique Used for Total Volume Volume Infiltration CumulatIve Percent WaterQuallty Percent Comment Treatment? Needs Through Volume Valume Wlume WaterQuaiity Treatment Facility (ac-1t) Infittration Infiltrated Treated (ac-rl) (ac-t) Credit Permeable Pavement 1 PQC 13 19.46 13 96.56 Total Vol ume InfrltraW 19.46 0.00 ff.00 96.56 0.00 0% No TreaL Credit eomphzwee with L 11) Duration Standard 4N or 2-yr }0 5G=mb 01 Analysis 2_yr Result = Failed LS33B_porous asphalt site model historical site 12/10/2019 4:10:31 PM Page 18 Model Default Modifications Total of 0 changes have been made. PERLND Changes No PERLND changes have been made. IMPLND Changes No IMPLND changes have been made. LS336_porous asphalt site model historical site 12/10/2019 4:11:04 PM Page 19 Appendix Predeveloped Schematic n LS33B_porous asphalt —Site model historical site 12/10/2019 4:11:04 PM Page 20 Mitigated Schematic LS33B_porous asphalt —Site model —historical site 12/10/2019 4:11:04 PM Page 21 P-developed UCI File RUN GLOBAL WWHM4 model simulation START 1948 10 01 END 2009 09 30 RUN INTERP OUTPUT LEVEL 3 0 RESUME 0 RUN 1 UNIT SYSTEM 1 END GLOBAL FILES <File> <Un#> <----------- File Name ------------------------------ >*** <-ID-> *** WDM 26 LS33B—porous asphalt_site model site.wdm MESSU 25 PreLS33B_porous asphalt_site —historical model site.MES 27 PreLS33B_porous asphalt_site model —historical site.L61 28 PreLS33B_porous asphalt_site model —historical historical site.L62 30 POCLS33B_porous asphalt_site model historical sitel.dat END FILES OPN SEQUENCE INGRP INDELT 00:15 PERLND 20 COPY 501 DISPLY 1 END INGRP END OPN SEQUENCE DISPLY DISPLY-INFO1 # - #<---------- Title ----------- >***TRAN PIVL DIG1 FIL1 1 Basin 1 MAX END DISPLY-INFO1 END DISPLY COPY TIMESERIES # - # NPT NMN *** 1 1 1 501 1 1 END TIMESERIES END COPY GENER OPCODE # # OPCD *** END OPCODE PARM # # K *** END PARM END GENER PERLND GEN-INFO PYR DIG2 FIL2 YRND 1 2 30 9 <PLS ><------- Name ------- >NBLKS Unit -systems Printer *** # - # User t-series Engl Metr *** in out *** 20 SAT, Forest, Mod 1 1 1 1 27 0 END GEN-INFO *** Section PWATER*** ACTIVITY <PLS > ************* Active Sections ***************************** # - # ATMP SNOW PWAT SED PST PWG PQAL MSTL PEST NITR PHOS TRAC *** 20 0 0 1 0 0 0 0 0 0 0 0 0 END ACTIVITY PRINT -INFO <PLS > ***************** Print -flags ***************************** PIVL PYR # - # ATMP SNOW PWAT SED PST PWG PQAL MSTL PEST NITR PHOS TRAC ********* 20 0 0 4 0 0 0 0 0 0 0 0 0 1 9 END PRINT -INFO LS3313_porous asphalt site model historical site 12/10/2019 4:11:04 PM Page 22 PWAT-PARM1 <PLS > PWATER variable monthly parameter value flags *** # - # CSNO RTOP UZFG VCS VUZ VNN VIFW VIRC VLE INFC HWT *** 20 0 0 0 0 0 0 0 0 0 0 0 END PWAT-PARM1 PWAT-PARM2 <PLS > PWATER input info: Part 2 *** # - # ***FOREST LZSN INFILT LSUR SLSUR KVARY 20 0 4 2 100 0.01 0.5 END PWAT-PARM2 PWAT-PARM3 <PLS > PWATER input info: Part 3 # - # ***PETMAX PETMIN INFEXP 20 0 0 10 END PWAT-PARM3 PWAT-PARM4 <PLS > PWATER input info: Part 4 # - # CEPSC UZSN NSUR 20 0.2 3 0.5 END PWAT-PARM4 AGWRC 0.996 *** INFILD DEEPFR BASETP AGWETP 2 0 0 0.7 *** INTFW IRC LZETP *** 1 0.7 0.8 PWAT-STATEI <PLS > *** Initial conditions at start of simulation ran from 1990 to end of 1992 (pat 1-11-95) RUN 21 *** # - # *** CEPS SUBS UZS IFWS LZS AGWS 20 0 0 0 0 4.2 1 END PWAT-STATEI END PERLND IMPLND GEN-INFO <PLS ><------- Name ------- > END GEN-INFO *** Section IWATER*** Unit -systems Printer *** User t-series Engl Metr *** in out *** ACTIVITY <PLS > ************* Active Sections ***************************** # - # ATMP SNOW IWAT SLD IWG IQAL *** END ACTIVITY PRINT -INFO <ILS > ******** Print -flags ******** PIVL PYR # - # ATMP SNOW IWAT SLD IWG IQAL ********* END PRINT -INFO IWAT-PARM1 <PLS > IWATER variable monthly parameter value flags *** # - # CSNO RTOP VRS VNN RTLI *** END IWAT-PARM1 IWAT-PARM2 <PLS > IWATER input info: Part 2 *** # - # *** LSUR SLSUR NSUR RETSC END IWAT-PARM2 IWAT-PARM3 <PLS > IWATER input info: Part 3 *** # - # ***PETMAX PETMIN END IWAT-PARM3 IWAT-STATEI <PLS > *** Initial conditions at start of simulation # - # *** RETS SURS END IWAT-STATEI GWVS 0 LS3313_porous asphalt site model historical site 12/10/2019 4:11:04 PM Page 23 END IMPLND SCHEMATIC <-Source-> <Name> # Basin 1*** PERLND 20 ******Routing****** END SCHEMATIC <--Area--> <-Target-> MBLK <-factor-> <Name> # Tbl# 0.218 COPY 501 12 NETWORK <-Volume-> <-Grp> <-Member-><--Mult-->Tran <-Target vols> <-Grp> <-Member-> *** <Name> # <Name> # #<-factor->strg <Name> # # <Name> # # *** COPY 501 OUTPUT MEAN 1 1 48.4 DISPLY 1 INPUT TIMSER 1 <-Volume-> <-Grp> <-Member-><--Mult-->Tran <-Target vols> <-Grp> <-Member-> *** <Name> # <Name> # #<-factor->strg <Name> # # <Name> # # *** END NETWORK RCHRES GEN-INFO RCHRES Name Nexits Unit Systems Printer *** # - #<------------------ >< --- > User T-series Engl Metr LKFG *** in out *** END GEN-INFO *** Section RCHRES*** ACTIVITY <PLS > ************* Active Sections ***************************** # - # HYFG ADFG CNFG HTFG SDFG GQFG OXFG NUFG PKFG PHFG *** END ACTIVITY PRINT -INFO <PLS > ***************** Print -flags ******************* PIVL PYR # - # HYDR ADCA CONS HEAT SED GQL OXRX NUTR PLNK PHCB PIVL PYR ********* END PRINT -INFO HYDR-PARM1 RCHRES Flags for each HYDR Section *** # - # VC Al A2 A3 ODFVFG for each *** ODGTFG for each FUNCT for each FG FG FG FG possible exit *** possible exit possible exit * * * * * * * * * * * * * * *** END HYDR-PARM1 HYDR-PARM2 # - # FTABNO LEN DELTH STCOR KS DB50 *** <------ ><-------- ><--------><--------><--------><--------><--------> *** END HYDR-PARM2 HYDR-INIT RCHRES Initial conditions for each HYDR section *** # - # *** VOL Initial value of COLIND Initial value of OUTDGT *** ac-ft for each possible exit for each possible exit <------><-------- > <---><---><---><---><---> *** <---><---><---><---><---> END HYDR-INIT END RCHRES SPEC -ACTIONS END SPEC -ACTIONS FTABLES END FTABLES EXT SOURCES <-Volume-> <Member> SsysSgap<--Mult-->Tran <-Target vols> <-Grp> <-Member-> *** <Name> # <Name> # tem strg<-factor->strg <Name> # # <Name> # # *** WDM 2 PREC ENGL 1 PERLND 1 999 EXTNL PREC WDM 2 PREC ENGL 1 IMPLND 1 999 EXTNL PREC WDM 1 EVAP ENGL 0.76 PERLND 1 999 EXTNL PETINP LS33B_porous asphalt site model —historical site 12/10/2019 4:11:04 PM Page 24 WDM 1 EVAP ENGL 0.76 IMPLND 1 999 EXTNL PETINP END EXT SOURCES EXT TARGETS <-Volume-> <-Grp> <-Member-><--Mult-->Tran <-Volume-> <Member> Tsys Tgap Amd *** <Name> # <Name> # #<-factor->strg <Name> # <Name> tem strg strg*** COPY 501 OUTPUT MEAN 1 1 48.4 WDM 501 FLOW ENGL REPL END EXT TARGETS MASS -LINK <Volume> <-Grp> <-Member-><--Mult--> <Target> <-Grp> <-Member->*** <Name> <Name> # #<-factor-> <Name> <Name> # #*** MASS -LINK 12 PERLND PWATER SURO 0.083333 COPY INPUT MEAN END MASS -LINK 12 END MASS -LINK END RUN LS33B_porous asphalt site model historical site 12/10/2019 4:11:04 PM Page 25 Mitigated UCI File RUN GLOBAL WWHM4 model simulation START 1948 10 01 END 2009 09 30 RUN INTERP OUTPUT LEVEL 3 0 RESUME 0 RUN 1 UNIT SYSTEM 1 END GLOBAL FILES <File> <Un#> <----------- File Name ------------------------------ >*** <-ID-> *** WDM 26 LS33B—Porous asphalt site model —historical site.wdm MESSU 25 MitLS33B_porous asphalt_site model site.MES 27 MitLS33B_porous asphalt_site model —historical site.L61 28 MitLS33B_porous asphalt_site model —historical historical site.L62 30 POCLS33B_porous asphalt_site model historical sitel.dat END FILES OPN SEQUENCE INGRP INDELT 00:15 IMPLND 17 PERLND 41 PERLND 20 IMPLND 16 RCHRES 1 COPY 1 COPY 501 COPY 601 DISPLY 1 END INGRP END OPN SEQUENCE DISPLY DISPLY-INFO1 # - #<---------- Title ----------- >***TRAN PIVL DIG1 1 Permeable Pavement 1 MAX END DISPLY-INFO1 END DISPLY COPY TIMESERIES # - # NPT NMN *** 1 1 1 501 1 1 601 1 1 END TIMESERIES END COPY GENER OPCODE # # OPCD *** END OPCODE PARM # # K *** END PARM END GENER PERLND GEN-INFO FIL1 PYR DIG2 FIL2 YRND 1 2 30 9 <PLS ><------- Name ------- >NBLKS Unit -systems Printer *** # - # User t-series Engl Metr *** 41 A/B, Lawn, Flat 20 SAT, Forest, Mod END GEN-INFO *** Section PWATER*** in out *** 1 1 1 1 27 0 1 1 1 1 27 0 ACTIVITY <PLS > ************* Active Sections ***************************** # - # ATMP SNOW PWAT SED PST PWG PQAL MSTL PEST NITR PHOS TRAC *** 41 0 0 1 0 0 0 0 0 0 0 0 0 LS3313_porous asphalt —Site model historical site 12/10/2019 4:11:04 PM Page 26 20 0 0 1 0 0 0 0 0 0 0 0 0 END ACTIVITY PRINT -INFO <PLS > ***************** Print -flags ***************************** PIVL PYR # - # ATMP SNOW PWAT SED PST PWG PQAL MSTL PEST NITR PHOS TRAC ********* 41 0 0 4 0 0 0 0 0 0 0 0 0 1 9 20 0 0 4 0 0 0 0 0 0 0 0 0 1 9 END PRINT -INFO PWAT-PARM1 <PLS > PWATER variable monthly parameter value flags *** # - # CSNO RTOP UZFG VCS VUZ VNN VIFW VIRC VLE INFC HWT *** 41 0 0 0 0 0 0 0 0 0 0 0 20 0 0 0 0 0 0 0 0 0 0 0 END PWAT-PARM1 PWAT-PARM2 <PLS > PWATER input info: Part 2 *** # - # ***FOREST LZSN INFILT LSUR SLSUR KVARY AGWRC 41 0 5 0.8 400 0.05 0.3 0.996 20 0 4 2 100 0.01 0.5 0.996 END PWAT-PARM2 PWAT-PARM3 <PLS > PWATER input info: Part 3 *** # - # ***PETMAX PETMIN INFEXP INFILD DEEPFR BASETP AGWETP 41 0 0 2 2 0 0 0 20 0 0 10 2 0 0 0.7 END PWAT-PARM3 PWAT-PARM4 <PLS > PWATER input info: Part 4 *** # - # CEPSC UZSN NSUR INTFW IRC LZETP *** 41 0.1 0.5 0.25 0 0.7 0.25 20 0.2 3 0.5 1 0.7 0.8 END PWAT-PARM4 PWAT-STATEI <PLS > *** Initial conditions at start of simulation ran from 1990 to end of 1992 (pat 1-11-95) RUN 21 *** # - # *** CEPS SURS UZS IFWS LZS AGWS GWVS 41 0 0 0 0 3 1 0 20 0 0 0 0 4.2 1 0 END PWAT-STATEI END PERLND IMPLND GEN-INFO <PLS ><------- Name ------- > Unit -systems Printer *** # - # User t-series Engl Metr *** in out *** 17 PARKING/MOD LAT 1 1 1 27 0 16 Porous Pavement 1 1 1 27 0 END GEN-INFO *** Section IWATER*** ACTIVITY <PLS > ************* Active Sections ***************************** # - # ATMP SNOW IWAT SLD IWG IQAL *** 17 0 0 1 0 0 0 16 0 0 1 0 0 0 END ACTIVITY PRINT -INFO <ILS > ******** Print -flags ******** PIVL PYR # - # ATMP SNOW IWAT SLD IWG IQAL ********* 17 0 0 4 0 0 0 1 9 16 0 0 4 0 0 0 1 9 END PRINT -INFO LS33B_porous asphalt site model historical site 12/10/2019 4:11:04 PM Page 27 IWAT-PARM1 <PLS > IWATER variable monthly parameter value flags *** # - # CSNO RTOP VRS VNN RTLI *** 17 0 0 0 0 0 16 0 0 0 0 0 END IWAT-PARM1 IWAT-PARM2 <PLS > IWATER input info: Part 2 *** # - # *** LSUR SLSUR NSUR RETSC 17 400 0.05 0.1 0.08 16 400 0.01 0.1 0.1 END IWAT-PARM2 IWAT-PARM3 <PLS > IWATER input info: Part 3 *** # - # ***PETMAX PETMIN 17 0 0 16 0 0 END IWAT-PARM3 IWAT-STATEI <PLS > *** Initial conditions at start of simulation # - # *** RETS SURS 17 0 0 16 0 0 END IWAT-STATEI END IMPLND SCHEMATIC <-Source-> <--Area--> <-Target-> MBLK *** <Name> # <-factor-> <Name> # Tbl# *** Impervious Structures*** IMPLND 17 0.6884 IMPLND 16 53 Retaining Wall*** PERLND 41 0.1613 IMPLND 16 54 PERLND 41 0.1613 IMPLND 16 55 IMPLND 16 0.093 RCHRES 1 5 Basin 1*** PERLND 20 0.046 COPY 501 12 PERLND 20 0.046 COPY 601 12 PERLND 20 0.046 COPY 501 13 PERLND 20 0.046 COPY 601 13 ******Routing****** IMPLND 17 0.6884 COPY 1 15 PERLND 41 0.1613 COPY 1 12 PERLND 41 0.1613 COPY 1 13 RCHRES 1 1 COPY 501 16 END SCHEMATIC NETWORK <-Volume-> <-Grp> <-Member-><--Mult-->Tran <-Target vols> <-Grp> <-Member-> *** <Name> # <Name> # #<-factor->strg <Name> # # <Name> # # *** COPY 501 OUTPUT MEAN 1 1 48.4 DISPLY 1 INPUT TIMSER 1 <-Volume-> <-Grp> <-Member-><--Mult-->Tran <-Target vols> <-Grp> <-Member-> *** <Name> # <Name> # #<-factor->strg <Name> # # <Name> # # *** END NETWORK RCHRES GEN-INFO RCHRES Name Nexits Unit Systems Printer *** # - #<------------------ >< --- > User T-series Engl Metr LKFG *** in out *** 1 Permeable Paveme-004 2 1 1 1 28 0 1 LS336_porous asphalt —Site model historical site 12/10/2019 4:11:04 PM Page 28 END GEN-INFO *** Section RCHRES*** ACTIVITY <PLS > ************* Active Sections ***************************** # - # HYFG ADFG CNFG HTFG SDFG GQFG OXFG NUFG PKFG PHFG *** 1 1 0 0 0 0 0 0 0 0 0 END ACTIVITY PRINT -INFO <PLS > ***************** Print -flags ******************* PIVL PYR # - # HYDR ADCA CONS HEAT SED GQL OXRX NUTR PLNK PHCB PIVL PYR ********* 1 4 0 0 0 0 0 0 0 0 0 1 9 END PRINT -INFO HYDR-PARM1 RCHRES Flags for each HYDR Section *** # - # VC Al A2 A3 ODFVFG for each *** ODGTFG for each FUNCT for each FG FG FG FG possible exit *** possible exit possible exit * * * * * * * * * * * * * * *** 1 0 1 0 0 4 5 0 0 0 0 0 0 0 0 2 2 2 2 2 END HYDR-PARM1 HYDR-PARM2 # - # FTABNO LEN DELTH STCOR KS DB50 *** <------><--------><-------- ><-------- ><-------- ><-------- ><-------- > *** 1 1 0.02 0.0 0.0 0.5 0.0 END HYDR-PARM2 HYDR-INIT RCHRES Initial conditions for each HYDR section *** # - # *** VOL Initial value of COLIND Initial value of OUTDGT *** ac-ft for each possible exit for each possible exit <------><-------- > <--- ><--- ><--- ><--- ><---> *** <--- ><--- ><--- ><--- ><---> 1 0 4.0 5.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 END HYDR-INIT END RCHRES SPEC -ACTIONS END SPEC -ACTIONS FTABLES' FTABLE 1 90 5 Depth Area Volume Outflowl Outflow2 Velocity Travel Time*** (ft) (acres) (acre-ft) (cfs) (cfs) (ft/sec) (Minutes)*** 0.000000 0.092975 0.000000 0.000000 0.000000 0.041852 0.092975 0.001556 0.000000 0.000938 0.083704 0.092975 0.003113 0.000000 0.000938 0.125557 0.092975 0.004669 0.000000 0.000938 0.167409 0.092975 0.006226 0.000000 0.000938 0.209261 0.092975 0.007782 0.000000 0.000938 0.251113 0.092975 0.009339 0.000000 0.000938 0.292966 0.092975 0.010895 0.000000 0.000938 0.334818 0.092975 0.012452 0.000000 0.000938 0.376670 0.092975 0.014008 0.000000 0.000938 0.418522 0.092975 0.015565 0.000000 0.000938 0.460374 0.092975 0.017121 0.000000 0.000938 0.502227 0.092975 0.018678 0.000000 0.000938 0.544079 0.092975 0.020234 0.000000 0.000938 0.585931 0.092975 0.021791 0.000000 0.000938 0.627783 0.092975 0.023347 0.000000 0.000938 0.669636 0.092975 0.024904 0.000000 0.000938 0.711488 0.092975 0.026460 0.000000 0.000938 0.753340 0.092975 0.028017 0.000000 0.000938 0.795192 0.092975 0.029573 0.000000 0.000938 0.837044 0.092975 0.031130 0.000000 0.000938 0.878897 0.092975 0.032686 0.000000 0.000938 0.920749 0.092975 0.034243 0.000000 0.000938 0.962601 0.092975 0.035799 0.000000 0.000938 1.004453 0.092975 0.037356 0.000000 0.000938 1.046306 0.092975 0.038912 0.000000 0.000938 LS33B_porous asphalt site model historical site 12/10/2019 4:11:04 PM Page 29 1.088158 0.092975 0.040469 0.000000 0.000936 1.130010 0.092975 0.042025 0.000000 0.000938 1.171862 0.092975 0.043582 0.000000 0.000938 1.213714 0.092975 0.045138 0.000000 0.000938 1.255567 0.092975 0.046695 0.000000 0.000938 1.297419 0.092975 0.048251 0.000000 0.000938 1.339271 0.092975 0.049808 0.000000 0.000938 1.381123 0.092975 0.051364 0.000000 0.000938 1.422976 0.092975 0.052921 0.000000 0.000938 1.464828 0.092975 0.054477 0.000000 0.000938 1.506680 0.092975 0.056034 0.000000 0.000938 1.548532 0.092975 0.057590 0.000000 0.000938 1.590384 0.092975 0.059147 0.000000 0.000938 1.632237 0.092975 0.060703 0.000000 0.000938 1.674089 0.092975 0.062260 0.000000 0.000938 1.715941 0.092975 0.063816 0.000000 0.000938 1.757793 0.092975 0.065372 0.000000 0.000938 1.799646 0.092975 0.066929 0.000000 0.000938 1.841498 0.092975 0.068485 0.000000 0.000938 1.883350 0.092975 0.070042 0.000000 0.000938 1.925202 0.092975 0.071598 0.000000 0.000938 1.967054 0.092975 0.073155 0.000000 0.000938 2.008907 0.092975 0.074322 0.000000 0.000938 2.050759 0.092975 0.075490 0.000000 0.000938 2.092611 0.092975 0.076657 0.000000 0.000938 2.134463 0.092975 0.077824 0.000000 0.000938 2.176316 0.092975 0.078797 0.000000 0.000938 2.218168 0.092975 0.079770 0.000000 0.000938 2.260020 0.092975 0.080743 0.000000 0.000938 2.301872 0.092975 0.081716 0.000000 0.000938 2.343724 0.092975 0.082688 0.000000 0.000938 2.385577 0.092975 0.083661 0.000000 0.000938 2.427429 0.092975 0.084634 0.000000 0.000938 2.469281 0.092975 0.085607 0.000000 0.000938 2.511133 0.092975 0.086580 0.000000 0.000938 2.552986 0.092975 0.087552 0.000000 0.000938 2.594838 0.092975 0.088525 0.000000 0.000938 2.636690 0.092975 0.089498 0.000000 0.000938 2.678542 0.092975 0.093389 0.000000 0.000938 2.720394 0.092975 0.097280 0.000000 0.000938 2.762247 0.092975 0.101172 0.000000 0.000938 2.804099 0.092975 0.105063 0.120421 0.000938 2.845951 0.092975 0.108954 0.371469 0.000938 2.887803 0.092975 0.112845 0.701695 0.000938 2.929656 0.092975 0.116737 1.095262 0.000938 2.971508 0.092975 0.120628 1.543242 0.000938 3.013360 0.092975 0.124519 2.039681 0.000938 3.055212 0.092975 0.128410 2.580243 0.000938 3.097064 0.092975 0.132301 3.161580 0.000938 3.138917 0.092975 0.136193 3.781011 0.000938 3.180769 0.092975 0.140084 4.436323 0.000938 3.222621 0.092975 0.143975 5.125648 0.000938 3.264473 0.092975 0.147866 5.847385 0.000938 3.306326 0.092975 0.151758 6.600138 0.000938 3.348178 0.092975 0.155649 7.382678 0.000938 3.390030 0.092975 0.159540 8.193912 0.000938 3.431882 0.092975 0.163431 9.032858 0.000938 3.473734 0.092975 0.167322 9.898630 0.000938 3.515587 0.092975 0.171214 10.79042 0.000938 3.557439 0.092975 0.175105 11.70749 0.000938 3.599291 0.092975 0.178996 12.64917 0.000938 3.641143 0.092975 0.182887 13.61462 0.000938 3.682996 0.092975 0.186779 14.60386 0.000938 3.724848 0.092975 0.190670 15.61575 0.000938 END FTABLE 1 END FTABLES EXT SOURCES <-Volume-> <Member> SsysSgap<--Mult-->Tran <-Target vols> <-Grp> <-Member-> *** <Name> # <Name> # tem strg<-factor->strg <Name> # ## <Name> # # *** LS3313_porous asphalt site model historical site 12/10/2019 4:11:04 PM Page 30 WDM 2 PREC ENGL 1 PERLND 1 999 EXTNL PREC WDM 2 PREC ENGL 1 IMPLND 1 999 EXTNL PREC WDM 1 EVAP ENGL 0.76 PERLND 1 999 EXTNL PETINP WDM 1 EVAP ENGL 0.76 IMPLND 1 999 EXTNL PETINP WDM 1 EVAP ENGL 0.76 RCHRES 1 EXTNL POTEV END EXT SOURCES EXT TARGETS <-Volume-> <-Grp> <-Member-><--Mult-->Tran <-Volume-> <Member> Tsys Tgap Amd *** <Name> # <Name> # #<-factor->strg <Name> # <Name> tem strg strg*** COPY 1 OUTPUT MEAN 1 1 48.4 WDM 701 FLOW ENGL REPL COPY 501 OUTPUT MEAN 1 1 48.4 WDM 801 FLOW ENGL REPL COPY 601 OUTPUT MEAN 1 1 48.4 WDM 901 FLOW ENGL REPL END EXT TARGETS MASS -LINK <Volume> <-Grp> <-Member-><--Mult--> <Target> <-Grp> <-Member->*** <Name> <Name> # #<-factor-> <Name> <Name> # #*** MASS -LINK 5 IMPLND IWATER SURO 0.083333 RCHRES INFLOW IVOL END MASS -LINK 5 MASS -LINK 12 PERLND PWATER SURO 0.083333 COPY INPUT MEAN END MASS -LINK 12 MASS -LINK 13 PERLND PWATER IFWO 0.083333 COPY INPUT MEAN END MASS -LINK 13 MASS -LINK 15 IMPLND IWATER SURO 0.083333 COPY INPUT MEAN END MASS -LINK 15 MASS -LINK 16 RCHRES ROFLOW COPY INPUT MEAN END MASS -LINK 16 MASS -LINK 53 IMPLND IWATER SURO IMPLND EXTNL SURLI END MASS -LINK 53 MASS -LINK 54 PERLND PWATER SURO IMPLND EXTNL SURLI END MASS -LINK 54 MASS -LINK 55 PERLND PWATER IFWO IMPLND EXTNL SURLI END MASS -LINK 55 END MASS -LINK END RUN LS33B_porous asphalt —Site model historical site 12/10/2019 4:11:04 PM Page 31 Predeveloped HSPF Message File LS33B_porous asphalt site model historical site 12/10/2019 4:11:04 PM Page 32 Mitigated HSPF Message File LS3313_porous asphalt site model historical site 12/10/2019 4:11:04 PM Page 33 Disclaimer Legal Notice This program and accompanying documentation are provided 'as -is' without warranty of any kind. The entire risk regarding the performance and results of this program is assumed by End User. Clear Creek Solutions Inc. and the governmental licensee or sublicensees disclaim all warranties, either expressed or implied, including but not limited to implied warranties of program and accompanying documentation. In no event shall Clear Creek Solutions Inc. be liable for any damages whatsoever (including without limitation to damages for loss of business profits, loss of business information, business interruption, and the like) arising out of the use of, or inability to use this program even if Clear Creek Solutions Inc. or their authorized representatives have been advised of the possibility of such damages. Software Copyright © by: Clear Creek Solutions, Inc. 2005-2019; All Rights Reserved. Clear Creek Solutions, Inc. 6200 Capitol Blvd. Ste F Olympia, WA. 98501 Toll Free 1(866)943-0304 Local (360)943-0304 www.clearcreeksolutions.com LS3313_porous asphalt site model historical site 12/10/2019 4:11:04 PM Page 34 TIR I PUMP STATION 33B I LAKEHAVEN WATER & SEWER DISTRICT Appendix D ESC PLAN FINAL I JANUARY2020 A 6 a m C 0 y a E 'o i 0 10' 20' 30' W UM LIU = 111-M CTR STRUCTURE 1.5' SW IE 12" PVC NW, S = 163.1' (REV 11/20109) rr1 K LIUl I 0.qy CTR STRUCTURE 1.5' N IE 12" PVC N. S. SE= 1625 aw ac o ` c 4 n OFCC 1 S' SE W ER EASEMENT i0O' STREAM BUFFER (TYP) 8 ,ND PROPOSED' W a 80' TEMPORARY CONSTRUCTTON STAGING AREA _-r r 1 1 � v EW MAN CTR uo = 158.87' CTR STRUCTURE I.& NIN f IE 12'.FVC N. ; S = W. 3' I + VYETLAHD LIMITS PP)" ;< t a a WZ.I AREA w I c ' aw PERMIT REVIEW SUBMITTAL NOT FOR CONSTRUCTION DESCRIPTION SAS DRAW DE A-1ECK6T TJW DATE MAY 2019 B 1 7 _1 is LEGEND SF SILT FENCE PER DETAIL C1C57YP —o--o STRAW WATTLE PER DETAIL C106(TYP STABILIZED CONSTRUCTION ENTRANCE PER DETAIL C107(TYP STAGING AREA WITHIN TEMPORARY CONSTRUCTION STAGING AREA OVEREXCAVATION AREA. SEE KEYNOTES 9 & 10 0-L1J-LJ-LJ-L-LI=1 TEMPORARY CONSTRUCTION ACCESS AREA CATCH BASIN TYPE-2 RM= 169.41'(TOP OF GRATE 2.5 HIGHER) CTR GRATE = CTR STRUCTURE IE 60" CMP SW =15BA (REV 11120/09) IE 18" HOLE NE = 158.7' (REV 11120109) SUMP=157.9' (REV 11120109) GCWER MANHOLE �- CTIR L" CTR STRUCTURE 1.6 S IE 12'PVC E,NW=184.9 IE 60"CMP=157.09 t1{ l m o m 1 F I � V 0 f v / > 2 SS 3595 _u w�.IV rux.c. Iroll (16 Lakehaven WATER & SEWER DISTRICT Providing water and sewer services to communities in South King County IV 1 _ KEY NOTES = O 1 STRAW WATTLE TO BE PLACED AT EDGE OF ROADWAY PRIOR TO BEGINNING EARTH DISTURBING ACTIVITIES WITHIN RIGHT-OF-WAY FOR INSTALLATION OF SS MAIN AND MANHOLES. STRAW WADDLE TO REMAIN IN PLACE UNTIL ALL SOIL WITHIN RIGHT-OF-WAY IS STABILIZED. 2 REMOVE AND REPLACE SILT FENCING AS NEEDED DURING CONSTRUCTION TO ACCOMMODATE SITE ACCESS. FENCE SHALL BE RESTORED TO DELINEATE THE PROJECT SITE BY THE END OF EACH WORKING DAY. 3 RELOCATE AND MAINTAIN CONSTRUCTION ENTRANCE AS NECESSARY DURING CONSTRUCTION TO PREVENT TRACKOUT 4 MAINTAIN DRIVABLE ACCESS TO EC PS33 FOR DMTRICT PERSONNEL DURING CONSTRUCTION. ORDINATE ACCESS CLOSURE WITH DISTRICT PRIOR TO RETAINING WALL CONSTRUCTION 5 SPAN WETLAND AREA WITH STEEL PLATES TO PROTECT EXISTING VEGETATION. NO TREES OR SOILS SHALL BE DISTURBED IN THIS AREA DURING CONSTRUCTION. PROVIDE PLANTING MITGATION PER L SHEETS FOLLOWING CONSTRUCTION. 8 CONSTRUCTION STAGING AND ACTIVITIES SHALL REMAIN OUTSIDE OF STREAM BUFFER AND WETLAND AREA EXCEPT AS OTHERWISE INDICATED ON THIS DRAWING. 7 TEMPORARY DEWATERING DISCHARGE AREA. PROTECT WETLAND FROM SCOUR, EROSION, SEDIMENTATION, AND OTHER DAMAGE. CONTRACTOR TO DESIGN AND INSTALL TEMPORARY ENERGY DISSIPATOR TURBIDITY OF DISCHARGE TO WETLAND SHALL NOT EXCEED 50 NTU. RESTORE PER L SHEETS AND SPECIFICATIONS FOLLOWING CONSTRUCTION, INCLUDING REMOVAL OF DEPOSITIED SEDIMENT. ~ 8 ROUTE TEMPORARY DEWATERING DISCHARGE �- PI PING AS NECESSARY TO REACH DEWATERING DISCHARGE AREA. PIPING SHALL BE INSTALLED SUCH THAT MINIMAL AREA IS DISTURBED OUTSIDE OF PROJECT SILT FENCE AND DEWATERING DISCHARGE AREA RESTORE AFFECTED AREA PER L SHEETS AND SPECIFICATIONS FOLLOWING CONSTRUCTION- 9 OVEREXCAVATE TO TBELOW EXISTING GROUND SURFACE TO REMOVE UNSUITABLE MATERIALS, EXCAVATING NO MORE THAN A 100 SQUARE FEET AREA (OR 25 CUBIC YARDS OF MATERIAL) AT A TIME. BACKFILL EXCAVATION WITH QUARRY SPALLSTO PROVIDE SITE BASE SEE DETAIL D, SHEET S02 FOR BACKFILL AT RETAINING WALLS. SEE GEOTECHNICAL REPORT AND CONSTRUCTION SEQUENCING FOR ADDITIONAL DETAILS. 10 FOLLOWING REPLACEMENT OF UNSUITABLE MATERIALS, PROVIDE TEMPORARY SITE ELEVATION OF 174 WITHIN 30 FEET OF THE NORTH, EASTAND SOUTHERN SIDES OF THE PROPOSED WET WELL STRUCTURE. PROVIDE A TEMPORARY SITE ELEVATION OF 174 WITHIN 17 FEET OF THE WEST SIDE QF THE WET WELL STRUCTURE (EDGE OF PROPOSED RETAINING WALL). SEE GEOTECHNICAL REPORT AND CONSTRUCTION SEQUENCING FOR ADDITIONAL DETAILS. FROSION CONTROL GENERAL NOTES 1. APPROVAL OF-MISEROSIONAND SEDIMENTATON CONIR04 (ESC) PLAN DOES NOT CONSTITUTE AN APPROVAL OF PERMANENT ROAD OR DRAINAGE DESIGN IE-Q, SIZE AND LOCATION OF ROADS. PIPES, RESTAICTORS. CHANNELS. RETENTION FACILITIES, UTILITIES, ETC.). 2. THE IMPLEMENTATMN OF THESE ESC PUNS AND TH E CONSTRUCTION. MAINTENANCE, REPLACEME NT, AND UPGRADING OF THESE FACILITIES IS THE RESPONSIBILITY OF THE APPLICATIONIESC SUPERVISOR UNTIL ALL CONSTRUCTION IS APPROVED. 3. THE BOUNDARIES OF THE CLEARING LIMITS SHOWN ON THIS PLAN SHALL BE CLEARLY FLAGGED BY SURVEY TAPE OR FENCING, IF REQUIRED, PRIOR TO CONSTRUCTION(SWDM APPENDIX D).DURING THE CONSTRUCTIONPERIOD, N O DISTURBANCE BEYON D THE CLEARING LIMITS SMALL BE PERMITTED -Tuts CLEARING LIMITS SHALL BE MAINTAINED BY THE APpUCATiOWESC SUPERVISOR FOR THE DURATION OF CONSTRUCTION. 4. STABILIZED CONSTRUCTION ENTRANCES SHALL BE INSTALLED AT THE BEGINNING OF THE CONSTRUCTION AND MAINTAINED FOR THE DURATION OF THE PROJECT. ADDITIONAL MEASURES. SUCH AS CONSTRUCTED WHEEL WASH SYSTEMS OR WASH PADS, MAY BE REQUIRED TO ENSURE THAT ALL PAVED AREAS ARE KEPT CLEAN AND TRACK OUT TO THE ROAD RIGHT OF WAY DOES NOT OCCUR FOR THE DURATION OF THE PROJECT, F, THE ESC FACILITIES SHOWN ON THIS PLAN MUST BE CONSTRUCTED PRIOR TO OR IN CONJUNCTION WITH ALL CLEARING AND GRADING SO AS TO ENSURE THAT THE TRANSPORT OF SEDIMENT TO SURFACE WATERS, DRAINAGE SYSTEMS. FLOW CONTROL BMP LOCATIONS (EXISTING AND PROPOSED). AND ADJACENT PROPERTIES IS MINIMI2ED• 6. THE ESC FACILITIES SHOWN ON THIS PLAN ARE THE MINIMUM REQUIREMENTS FOR ANTICIPAM SITE CONDITIONS, DURING THE CONSTRUCTION PERIOD, THESE ESC FACILITIES SHALL BE UPGRADED AS NEEDED FOR UNEXPECTED STORM EVENTS AND MODIFIED TO ACCOVNT FOR CHANGING SITE CONDITIONS (E.G. ADDITIONAL COVER MEASURES, ADDITIONAL SUMP PUMPS, RELOCATION OF DITCHES AND SILT FENCES, PERIMETER PROTECTION ETC.) AS DIRECTED BY KING COUNTY. 7. THE ESC FACIUM ESSHALL BE INSPECTED DAILY BY THE APPUCANTlESC SUPERVISOR AND MAINTAINED TO ENSURE CONTINUED PROPER FUNCTIONING. WRITTEN RECORDS SHALL BE KEPT OF WEEKLY REVIEWS OF THE ESC FACILITIES. B. ANY AREAS OF EXPOSED SOILS, INCLUDING ROADWAY EMSJWKMENTS, THAT WALL NOT BE DISTU REED FOR TWO CONSECUTIVE DAYS OUR ING THE WET SEASON OR SEVEN DAYS DURING THE DRY SEASON SHALL BE IMMEDIATELY STABILIZED WITH THE APPROVED ESC METHODS (E.G.. SEEDING, MULCHING, PLASTIC COVERING, ETC.). 9, ANY AREA NEEDING ESC MEASURES THAT DO NOT REQUIRED IMMEDIATE ATTENTIONSWALLBE ADDRESSED WITHIN SEVEN (7) DAYS. 10. THE ESC FAC IL ITIES ON INACTIVE SITES SHALL BE INSPECTED AN D MAINTAINED A MINIMUM OF ONCE A MONTH DUR1 NG THE DRY SEASON. BI-MONTHLY OUTING THE WET SEASON, OR WITHIN TWENTY FOUR (24) HOURS FOLLOWING A STORM EVENT 11. COVER MEASURES WILL BE APPLIED IN CONFORMANCE WITH APPENDIX D OF THE KING COUNTY SURFACE WATER DESIGN MANUAL. 12 PRIORTO THE BEGINNING OF THE WET SEASONS TOCT. 1), A LLDISTURBEO AREAS DENTIFYWHICHONESCANBESEEDEDIN BE REVIEWED PREPARATION FOR THE WINTER RAINS, DISTURBED AREAS SHALL BE SEEDED WITHIN ONE WEEK OF THE BEGINNING OF THE WET SEASON. A SKETCH MAP OF THOSE AREASTO BE SEEDED AND THOSE AREAS TO REMAIN UNCOVERED SHALL BE SUBMITTED OT THE DPER INSPECTOR. 13. UNLESS DIRECTEDOTHERWISE, ALLTESC MEASURES AND BMPS SHALL BE REMOVED UPON FINAL SITE STAB ILIZATIONIRESTORATION LAKEHAVEN WATER & SEWER DISTRICT SANITARY SEWER PUMP STATION 33B CIVIL EXISTING SITE AND EROSION CONTROL PLAN 1n 1 11 1 1 1—r 1 "`""` 10581A10 BAR IS ONE INCH ON DRAWING NO. ORIGINAL DRAWING 01" C01 IF NOT ONE INCH ON SHEET NO. THIS SHEET. ADJUST SCALF,SACCORDLN'CLY 22 OF 74 PRn.IF(.TNn 105Al AlO FII F NAMF• 105R1A10nnonniAnn 2 1 3 4 1 5 1 s 7 1 Ea ■ IM* RADIUS Z-0" TOOLED EDGE AC PAVING 3 1" B FORPDRAWINGS AVEW II &,IT -AMR I R. SECTION a AB U.- GUTTER 12" („ NOTES: 1 PROVIDE 31C EXPANSION JOINTS AT ENDS OF CONCRETE PLACEMENT ATPOINTS OF CURVATURE• AT INTERSECTIONS, AND AT MAXIMUM SPACING OF 30 F!?ET. EXPANSION e' VSEE BI 5rLL USS alWIFIBEREX WITH lie RADIUSOINT CONCRETE EDGES AT BOTH SIDES OF JOINT. 2. DO NOT PASS REINFORCING BARS THROUGH EXPANSION JOINTS. 3 PROVIDE WEAKEN 2D RPLANE JOINTS EDGAT 10 FEET OC E EACH SIDE AT MAXIMUM. AT FRONT, TOP AND BACK FACESC104 CROSS GUTTER AND VALLEY GUTTER TYP J 07/25113 E F n 5 _LL WIDTH OF INGRESS/EGRESS AREA NOTE: 1. DRIVEWAY SHALL MEET THE REQUIREMENTS OF THE PERMITTING AGENCY 2. CROWN ENTRANCE SO THAT RUNOFF DRAINS OFF THE PAD C1071 STABALIZED CONSTRUCTION ENTRANCE V TYP 10I11I18 PERMIT REVIEW SUBMITTAL NOT FOR CONSTRUCTION _. BAS` DRAWN RCP CHECKEI BJE DESCRIPTION DATE MAY 2019 2"x2" 14 GA WIRE OR EQUIVALENT, IF STANDARD STRENGTH FABRIC USED JOINTS IN FILTER FABRIC SHALL BE SPLICED AT POSTS, MIN 6" OVERLAP. USE MIN 1" STAPLES, WIRE RINGS OR EQUIVALENT TO ATTACH TO POSTS 6' NWC WI GREATER THAN STANDARD STRE1!G'H FABRIC ~ $' MAX IF WIRE BACKING USED FILTER FABRIC FENCE NOTES -- A THE FILTER FABRIC SHALL BE PURCHASED IN A CONTINUOUS ROLL CUT TO THE LENGTH OF THE BARRIER TO AVOID USE OF JOINTS. B. THE FILTER FABRIC FENCE SHALL BE INSTALLED TO FOLLOW THE CONTOURS WHERE FEASIBLE WHEN JOINTS ARE NECESSARY, FILTER CLOTH SHALL BE SPLICED TOGETHER ONLY AT A SUPPORT POST, BOTH ENDS SECURELY FASTENED TO THE POST A MAXIMUM OF 6 FEET APART AND DRIVEN SECURELY INTO THE GROUND. C. WHEN STANDARD STRENGTH FILTER FABRIC IS USED, A WIRE MESH SUPPORT FENCE SHALL BE FASTENED SECURELY TO THE UPSLOPE SIDE OF THE POSTS. D. THE STANDARD STRENGTH FILTER FABRIC SHALL BE STAPLED OR WIRED TO THE FENCE FILTER FABRIC SHALL NOT BE STAPLED TO EXISTING TREES. FENCE POST FILTER FABRIC O Z¢ WIRE MESH LL w - n r LL �z a � Z MIN 12"02" TRENCH. o BACKFILL W/ NATIVE c SOIL OR W TO 1 Y"O WASHED GRAVEL E WHEN EXTRA -STRENGTH FILTER FABRIC AND CLOSER POST SPACING ARE USED, THE WIRE MESH SUPPORT FENCE MAY BE ELIMINATED. IN SUCH A CASE, THE FILTER FABRIC IS STAPLED OR WIRED DIRECTLY TO THE POSTS WITH ALL OTHER PROVISIONS OF THE STANDARD NOTES APPLYING. R FILTER FABRIC FENCES SHALL BE REMOVED WHEN CONSTRUCTION ACTIVITY IS COMPLETE AND THE UPSLOPE AREA HAS BEEN PERMANENTLY STABILIZED. G. FILTER FENCES SHALL BE INSPECTED DAILY AND IMMEDIATELY AFTER EACH RAINFALL. DURING PROLONGED RAINFALL ANY REQUIRED REPAIRS SHALL BE MADE IMMEDIATELY, FC-10-51 FILTER FABRIC FENCE TYP J 10/11/18 NOTES: 1 STOCKPILE SHALL BE COVERED WITH VISQUEEN PLASTIC (MIN. 6 MIL) IF IT IS TO REMAIN UNWORKED FOR MORE THAN 12 HOURS DURING THE WET SEASON (OCT. 1 - APRIL 30) AND FOR MORE THAN 7 DAYS DURING THE DRY SEASON (MAY 1 - SEPT. 30). 2 DURING THE WET SEASON, MATERIAL REQUIRED TO COVER STOCKPILE MUST BE STORED ON SITE. 3. STOCKPILE SHALL NOT BE PLACED IN AN AREA WITH A SLOPE GREATER THAN 20% 4 STOCKPILE AREA SHALL HAVE FILTER FABRIC FENCE INSTALLED AROUND ENTIRE AREA. AN OPENING ACCESS SHALL BE LOCATED ON THE UPHILL SIDE, AND SHOULD BE CLOSED WITH FILTER FABRIC FENCE WHEN NOT IN USE B SMM)f/// {25 ■ 23MM} NOTE: 1, STRAW ROLL INSTALLATION REQUIRES THE PLACEMENT AND SECURE STAKING OF THE ROLL IN TRENCH, 3" - 5" (75-125mm) DEEP, DUG ON CONTOUR RUNOFF MUST NOT BE ALLOWED TO RUN UNDER OR AROUND ROLL. FC-1-06-1 STRAW WATTLE TYP 10MI118 WELD ON CONCRETE PAVEMENT 4"0 GALV SCH 40 STEEL POST. PAINT SAFETY YELLOW PER I ! 1/2"BITUMINOUS ANSI Z535.1- FIBER EXP JOINT MATERIAL ALL AROUND (UNLESS FINISHED GRADE 1 OTHERWISE INDICATED OR AC PAVEMENT. ON THE DRAWINGS) SEE DRAWINGS, AT CDNC B \ PAVEMENT it ti I 4 • M i 5"0 SCHEDULE 80 PVC PIPE SLEEVE CLASS "C" CONCRETE - - rare B NCR E T I F I A AC PAVEMENT OR FINISHED GRADE C108 STOCKPILING DETAIL FC1411 EXTRUDED CURB I C161 1 REMOVAULL UUAKL7 ruo I TYP 1v1v1$ TYP J 1onv16 TYP J N 01I13/14 LAKEHAVEN WATER & SEWER DISTRICT VERIFY SCALE 10581os a10 D W BAR IS ONE INCH ON - ♦ Lakehaven SANITARY SEWER PUMP STATION 33B ORIGINAL DRAWING DRAWING NO. C�o �" TC01 WATER &SEWER DISTRICT CIVIL it CCIVIL TYPICAL DETAILS - 1 F IS SHEONE ,ADJUS SHEET NO. Providing water and sewer services THIS SHEET, ADJUST IO communities in South King County. SCALES ACCORDINGLY g OF 74 5 6 7 8 �o ii 4z T3 PRO.IFCTNO 1nsAIA10 Fit FNAMP 105R1A1n TCfll rinn TIR I PUMP STATION 33B I LAKEHAVEN WATER & SEWER DISTRICT Appendix E DECLARATION OF COVENANT (FUTURE) L'a/'^off^" FINAL I JANUARY 2020 TIR I PUMP STATION 33B I LAKEHAVEN WATER & SEWER DISTRICT Appendix F STORMWATER O&M MANUAL C FINAL I JANUARY 2020 Stormwater Management Facility Operation and Maintenance (O&M) Manua! For Lakehaven Water & Sewer District Pump Station 33B Located at: King County Parcel #2921049157, Federal Way, WA 98003 Prepared by: Carollo Engineers 1218 Third Ave Seattle, WA 981ol Lakehaven Water & Sewer District - Pump Station 33B Stormwater Management Facility Operation and Maintenance (O&M) Manual Table of Contents I. Contact Information II. Maintenance III. Preventative Measures to Reduce Maintenance Costs IV. Safety V. General Location and Description of Stormwater Management Facilities VI. Maintaining Stormwater Management Facilities VII. Maintenance Documentation Appendices Appendix A— Stormwater Facility Maintenance Activity Log Appendix B — Stormwater Facility Annual Maintenance Cost Estimate Appendix C — Stormwater Facilities Plan Appendix D — Maintenance Standards Appendix E — Contech Stormfilter Plans & Maintenance Standards Stormwater Management Facility Operation and Maintenance (O&M) Manual I. Contact Information Owner Lakehaven Water & Sewer District Phone Email Maintenance Responsible Party Lakehaven Water & Sewer District Phone Email Emergency Contact Lakehaven Water & Sewer District Phone Email The above contact information shall be updated any time that the information changes. II. Maintenance Maintenance Manuals shall be provided to the property owner and kept onsite at all times. This O&M manual and any supporting materials will be kept onsite in the facility's main office. Maintenance logs shall be provided to the City of Federal Way's Public Works Director or his/her designee upon request. A sample maintenance log is provided in Appendix A. III. Preventative Measures to Reduce Maintenance Costs The most effective way to maintain your water quality facility is to prevent the pollutants from entering the facility in the first place. Common pollutants include sediment, trash & debris, chemicals, dog wastes, runoff from stored materials, illicit discharges into the storm drainage system (like car wash or pressure washing runoff) and many others. A thoughtful maintenance program will include measures to address these potential contaminants, and will save money and time in the long run. Key points to consider in your maintenance program include: • Educate property owners to be aware of how their actions affect water quality, and how they can help reduce maintenance costs. ■ Keep properties, streets and gutters, and parking lots free of trash, debris, and lawn clippings. • Ensure the proper disposal of hazardous wastes and chemicals. • Plan lawn care to minimize the use of chemicals and pesticides. • Sweep paved surfaces and put the sweepings back on the lawn. ■ Be aware of trucks and vehicles leaking fluids. Use absorbents such as cat litter to soak up drippings — dispose of properly. ■ Re -vegetate disturbed and bare areas to maintain vegetative stabilization. • Clean out the upstream components of the storm drainage system, including inlets, storm sewers and outfalls. • Do not store materials outdoors (including landscaping materials) unless properly protected from runoff. • Close the covers on dumpsters to prevent liquids from leaking into the storm system. IV. Safety Never enter a confined space (outlet structure, manhole, etc.) without proper training and equipment. A confined space should never be entered without at least one additional person present. If a toxic or flammable substance is discovered, leave the immediate area and call gii. Potentially dangerous (e.g., fuel, chemicals, hazardous materials) substances found in the areas must be referred to the local Fire Department immediately for response by the Hazardous Materials Unit. The emergency contact number is 91i. Vertical drops may be encountered in areas located within and around the facility. Avoid walking on top of retaining walls or other structures that have a significant vertical drop. If any hazard is found within the facility area that poses an immediate threat to public safety, call gii immediately. V. General Location and Description of Stormwater Management Facilities The site has five primary stormwater system components, all of which require periodic maintenance to continue functioning properly overtime. These components are: ■ Stormwater Conveyance Pipe • Catch basins • Contech Stormfilter Catchbasin ■ Porous Asphalt/Permeable Pavement • Dispersion Trench Conveyance Pipe connects the different stormwater management facilities onsite Catch basins are located throughout the site and collect smaller drainage area before conveying them to the proper stormwater facility for treatment and/or discharge. These basins collect debris washed from the surface and must be cleared periodically to allow for proper functioning. A Contech Stormfilter is installed on the site to treat all runoff prior to dispersal from the site. Stormwater run through a filter cartridge within this structure. This catchbasin must be cleaned periodically and the filter must be replaced periodically as described in the attached Contech O&M manual (Appendix Q. Porous Asphalt/Permeable Pavement covers the majority of the onsite area and allows rainfall to soak into the underlying soils. In the event of rainfall rates exceed the infiltration capacity of the pavement, any runoff is directed to the onsite catchbasins. All runoff that enters the onsite catchbasin is directed to the graveled filled dispersion trench at the edge of the site. The dispersion trench allow stormwater flows to soak into the existing soils and/or sheet flow offsite to the adjacent vegetated area, mimicking nature flow patterns. Maintenance personnel may use the stormwater facilities plan located in Appendix C to identify the locations of the stormwater management facilities. Maintenance requirements for each stormwater system feature are presented in Appendix D. VI. Maintaining Stormwater Management Facilities Stormwater management facilities must be properly maintained to ensure that they operate correctly and provide the water quality treatment for which they were designed. Routine maintenance performed on a frequently scheduled basis, can help avoid costlier rehabilitative maintenance that results when facilities are not adequately maintained. Minimum maintenance requirements are contained in Appendix D. These requirements should be updated to reflect changes and updates to these facilities. An estimate of annual maintenance costs for the site and its individual stormwater facilities is included in Appendix B. Routine Preventative Maintenance Much of this work consists of inspection, weed control, and trash and debris pickups for stormwater management facilities during the growing season. This includes items such as the removal of debris/material that may be clogging the outlet structure and weed control. These activities normally will be performed numerous times during the year. Minor Corrective Maintenance This work consists of a variety of isolated or small-scale maintenance and work needed to address operational problems. Most of this work can be completed by a small crew, with minor tools, and small equipment. Ma or Corrective Maintenance This work consists of large-scale maintenance and major improvements needed to address failures within the stormwater management facilities. This work may require an engineering design with construction plans to be prepared for review and approval by the City. This work may also require more specialized maintenance equipment, surveying, construction permits or assistance through private contractors and consultants. These items require prior correspondence with City of Federal Way and may be subject to permits. VII. Maintenance Documentation The Stormwater Management Facility Maintenance Activity Form provided in Appendix A provides a record of maintenance activities. Maintenance standards for each facility type are provided in Appendix D. Maintenance shall be completed by the contractor completing the required maintenance items. The form shall then be reviewed by the property owner or an authorized agent of the property owner and kept on site and submitted to the City of Tacoma upon request. Appendix A Stormwater Facility Maintenance Activity Log I Q W z Q U N w � � {0 � ~ c dl y E O v ua r O Z NI �7 a m k W o r R a V � 9 d v d a NI C c E d d = 0+ E H O c.� d {0 tea+ Uc� cd a O o U 'C O 4 O O 4-1 u _ U O cd O O 41 A. 'd u V. 4+ O f.' O 'n Cm4-1 4-4 O 4-4 Cco) �`o O bA o � 0 Q U "U . cud as o o 1 o U• � � 0 i a� O O OvR V u p °� O U art .ti L' c� O C U � O U +� y ¢ a� o � u U a -d In�, a a Cd 0 �° o O y J U ^j a� Cz o Z U 4 G O 0 U N 0 m I � 0 'd +� v) N U CO . U)oU� c o t (U U o +�b y c o 2.tiC/) �UWU CU Appendix B Stormwater Facility Annual Maintenance Cost Estimate .X Q Q. -N L Q O O 0 O--t 0 0 O 0 a0 In N 0 M 0 O 0 00 0 O 0 O 0 O 0 O 0 O 0 00 Ln Ln N N N-t N N N-* N 0) y N a N in in V> Vn V� V} in -In O O 0-t O O 0 O 00" In O O O0 O 000 O O O O O O Or4 O O O o0 J O in0 N IN IN 0 •V O U V� V} Vn V)- Vn -In V) Vi to n in In i/� to V� 07 Ln N m N O N m N O N" m O M In N O N m N O N In N In N m N O N LL V N u a m m Vi V? V> -In -In V� V} V? V� V} V? V� W--t 00 N 00 r-I a I W 't 00 O 00 W CO 'cl- O •M Lno CO �' C M= •V C aN. •In Ln ul In Ln 4.0 L 2 2 U 2 U 2 w 2 U 2 U 2 2 2 U M 47 H mtr C i L L L L L L L L L L L L v L a�i L v v v a�i a�i N a�i N v a�i ct >- >- >- � N •L O H O V L M 3 N ++ :u0QOQ f6 f0 L = H M D -0 Ln O -0 J ,n O L O a f6 _ f0 ciy Q O `—n - m L p O O. L O O Q W L c: O 0A C G0 C M C 00 C L J f0 Ln 0 -0 m Ln Gi +� f0 ++ c� c N c a� c v c v O J -W l6 > O j O O E Q cn U U U U , E O E>> N p p J �0 >> O O L= cc + E E J E E a1 {H NJ > L Vl m 'n m V1 m v7 m �+ iz a' i� }+ w 4 N a) cu C a) OC E E i 'L ._ O M �.( 4S ++ 4S ++ f6 Qi fC v � � � � � CIO Y Q V u U U U U c% cn U-)cl a U J a) a1 t U L U L u L U t U Q a CL s C v C aJ C v C v C v y� f 41 m ++ m a) V) V) c H �` H H t Q t Q t Q U C L) C .a Fn co ,rA m L +C+ L +O+ C p C O C O C O C O Q Q Q co m iF � •L •L •L aJ •L v •L a) N 'n N > > U U O L L p_ `n Q `n p. `" 0-Q L O O O �i Q O U O U M U M U 4 Ul cn 0 55 E a� a s Appendix C Stormwater Facilities Plan Appendix D Maintenance Standards APPENDIX A MAINTENANCE REQUIREMENTS FOR FLOW CONTROL, CONVEYANCE, AND WQ FACILITIES NO.5 - CATCH BASINS AND MANHOLES Maintenance Defect or Problem Condition When Maintenance is Needed Results Expected When Component Maintenance is Performed Structure Sediment Sediment exceeds 60% of the depth from the Sump of catch basin contains no bottom of the catch basin to the invert of the sediment. lowest pipe into or out of the catch basin or is within 6 inches of the invert of the lowest pipe into or out of the catch basin. Trash and debris Trash or debris of more than '/2 cubic foot which No Trash or debris blocking or is located immediately in front of the catch basin potentially blocking entrance to opening or is blocking capacity of the catch basin catch basin. by more than 10%. Trash or debris in the catch basin that exceeds No trash or debris in the catch 1/3 the depth from the bottom of basin to invert basin. the lowest pipe into or out of the basin. Dead animals or vegetation that could generate No dead animals or vegetation odors that could cause complaints or dangerous present within catch basin. gases (e.g., methane). Deposits of garbage exceeding 1 cubic foot in No condition present which would volume. attract or support the breeding of insects or rodents. Damage to frame Corner of frame extends more than % inch past Frame is even with curb. and/or top slab curb face into the street (If applicable). Top slab has holes larger than 2 square inches Top slab is free of holes and cracks. or cracks wider than % inch. Frame not sitting flush on top slab, i.e., Frame is sitting flush on top slab. separation of more than 3K inch of the frame from the top slab. Cracks in walls or Cracks wider than '/z inch and longer than 3 feet, Catch basin is sealed and is bottom any evidence of soil particles entering catch structurally sound. basin through cracks, or maintenance person judges that catch basin is unsound. Cracks wider than '/2 inch and longer than 1 foot No cracks more than 1/4 inch wide at at the joint of any inlet/outlet pipe or any the joint of inlet/outlet pipe. evidence of soil particles entering catch basin through cracks. Settlement/ Catch basin has settled more than 1 inch or has Basin replaced or repaired to design misalignment rotated more than 2 inches out of alignment. standards. Damaged pipe joints Cracks wider than '/2-inch at the joint of the No cracks more than %-inch wide at inlet/outlet pipes or any evidence of soil entering the joint of inlet/outlet pipes. the catch basin at the joint of the inlet/outlet pipes. Contaminants and Any evidence of contaminants or pollution such Materials removed and disposed of pollution as oil, gasoline, concrete slurries or paint. according to applicable regulations. Source control BMPs implemented if appropriate. No contaminants present other than a surface oil film. Inlet/Outlet Pipe Sediment Sediment filling 20% or more of the pipe. Inlet/outlet pipes clear of sediment. accumulation Trash and debris Trash and debris accumulated in inlet/outlet No trash or debris in pipes. pipes (includes floatables and non-floatables). Damaged Cracks wider than '/2-inch at the joint of the No cracks more than %-inch wide at inlet/outlet pipes or any evidence of soil entering the joint of the inlet/outlet pipe. at the joints of the inlet/outlet pipes. 2016 Surface Water Design Manual — Appendix A 4/24/2016 A-9 APPENDIX A MAINTENANCE REQUIREMENTS FLOW CONTROL, CONVEYANCE, AND WQ FACILITIES NO, CATCH SAS AND MANHOLES Maintenance Defect or Problem Condition When Maintenance is Needed Results Expected When Component Maintenance is Performed Metal Grates Unsafe grate opening Grate with opening wider than '/e inch. Grate opening meets design (Catch Basins) standards. Trash and debris Trash and debris that is blocking more than 20% Grate free of trash and debris. of grate surface. footnote to guidelines for disposal Damaged or missing Grate missing or broken member(s) of the grate. Grate is in place and meets design Any open structure requires urgent standards. maintenance. Manhole Cover/Lid Cover/lid not in place Cover/lid is missing or only partially in place. Cover/lid protects opening to Any open structure requires urgent structure. maintenance. Locking mechanism Mechanism cannot be opened by one Mechanism opens with proper tools. Not Working maintenance person with proper tools. Bolts cannot be seated. Self-locking cover/lid does not work. Cover/lid difficult to One maintenance person cannot remove Cover/lid can be removed and Remove cover/lid after applying 80 lbs. of lift. reinstalled by one maintenance person. 4/24/2016 2016 Surface Water Design Manual — Appendix A A-10 APPENDIX A MAINTENANCE REQUIREMENTS FOR FLOW CONTROL, CONVEYANCE, AND WQ FACILITIES NO.6 - CONVEYANCE PIPES AND DITCHES Maintenance Defect or Problem Conditions When Maintenance is Needed Results Expected When Component Maintenance is Performed Pipes Sediment & debris Accumulated sediment or debris that exceeds Water flows freely through pipes. accumulation 20% of the diameter of the pipe. Vegetation/roots Vegetation/roots that reduce free movement of Water flows freely through pipes. water through pipes. Contaminants and Any evidence of contaminants or pollution such Materials removed and disposed of pollution as oil, gasoline, concrete slurries or paint. according to applicable regulations. Source control BMPs implemented if appropriate. No contaminants present other than a surface oil film. Damage to protective Protective coating is damaged; rust or corrosion Pipe repaired or replaced. coating or corrosion is weakening the structural integrity of any part of pipe. Damaged Any dent that decreases the cross section area Pipe repaired or replaced. of pipe by more than 20% or is determined to have weakened structural integrity of the pipe. Ditches Trash and 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 accumulation design depth. sediment and debris so that it matches design. Noxious weeds Any noxious or nuisance vegetation which may Noxious and nuisance vegetation constitute a hazard to County personnel or the removed according to applicable public. regulations. No danger of noxious vegetation where County personnel or the public might normally be. Contaminants and Any evidence of contaminants or pollution such Materials removed and disposed of pollution as oil, gasoline, concrete slurries or paint. according to applicable regulations. Source control BMPs implemented if appropriate. No contaminants present other than a surface oil film. Vegetation Vegetation that reduces free movement of water Water flows freely through ditches. through ditches. Erosion damage to Any erosion observed on a ditch slope. Slopes are not eroding. slopes Rock lining out of One layer or less of rock exists above native soil Replace rocks to design standards. place or missing (If area 5 square feet or more, any exposed native Applicable) soil. 2016 Surface Water Design Manual — Appendix A 4/24/2016 A-11 APPENDIX A MAINTENANCE REQUIREMENTS FLOW CONTROL, CONVEYANCE, AND WQ FACILITIES NO.27 -GRAVEL FILLED DISPERSION TRENCH BMP Maintenance Defect or Problem Conditions When Maintenance is Needed Results Expected When Component Maintenance is Performed Preventative Blocking, obstructions Debris or trash limiting flow to dispersion trench Dispersion trench able to receive full or preventing spreader function. flow prior to and during wet season. Site Trash and debris Trash or debris that could end up in the No trash or debris that could get into dispersion trench is evident. the dispersion trench can be found. Pipes Inlet is plugged The entrance to the pipe is restricted due to The entrance to the pipe is not sediment, trash, or debris. restricted. Vegetation/roots Vegetation/roots that reduce free movement of Water flows freely through pipes. water through pipes. Plugged Sediment or other material prevents free flow of Water flows freely through pipes. water through the pipe. Broken joint or joint Damage to the pipe or pipe joints allowing water Pipe does not allow water to exit leaks. to seep out. other than at the outlet to the trench. Cleanout caps Cleanout caps are broken, missing, or buried. Cleanout caps are accessible and intact. Structure Flow not reaching Flows are not getting into the trench as designed. Water enters and exits trench as trench designed. Perforated pipe Flow not able to enter or properly exit from Water freely enters and exits plugged perforated pipe. perforated pipe. Flow not spreading Outlet flows channelizing or not spreading evenly Sheet flow occurs at the outlet of the evenly at outlet of from trench. trench. trench Cleanout/inspection The cleanout/inspection access is not available. Cleanout/inspection access is access does not allow available. cleaning or inspection of perforated pipe Filter Media Filter media plugged Filter media plugged. Flow through filter media is normal. Inspection Frequency Annually and prior to and following significant Inspect dispersion trench system for storms. any defects of deficiencies. 4/24/2016 2016 Surface Water Design Manual — Appendix A A-36 APPENDIX A MAINTENANCE REQUIREMENTS FLOW CONTROL, CONVEYANCE, AND WQ FACILITIES NO.30 - PERMEABLE PAVEMENT BMP Maintenance Defect or Problem Conditions When Maintenance is Needed Results Expected When Component Maintenance is Performed Preventative Surface cleaning/ Media surface vacuumed or pressure washed No dirt, sediment, or debris clogging vegetation control annually, vegetation controlled to design porous media, or vegetation limiting maximum. Weed growth suggesting sediment infiltration. accumulation. Porous Concrete, Trash and debris Trash and debris on the pavement interfering No trash or debris interfering with Porous Asphaltic with infiltration; leaf drop in fall season. infiltration. Concrete, and Permeable Pavers Sediment Sediment accumulation on the pavement Pavement infiltrates as designed; accumulation interfering with infiltration; runoff from adjacent adjacent areas stabilized. areas depositing sediment/debris on pavement. Infiltration rate Pavement does not infiltrate at a rate of 10 Pavement infiltrates at a rate greater inches per hour. than 10 inches per hour. Ponding Standing water for a long period of time on the Standing water infiltrates at the surface of the pavement. desired rate. Broken or cracked Pavement is broken or cracked. No broken pavement or cracks on pavement the surface of the pavement. Settlement Uneven pavement surface indicating settlement Pavement surface is uniformly level. of the subsurface layer. Moss growth Moss growing on pavement interfering with No moss interferes with infiltration. infiltration. Inflow Inflow to the pavement is diverted, restricted, or Inflow to pavement is unobstructed depositing sediment and debris on the and not bringing sediment or debris pavement. to the pavement. Underdrain Underdrain is not flowing when pavement has Underdrain flows freely when water been infiltrating water. is present. Overflow Overflow not controlling excess water to desired Overflow permits excess water to location; native soil is exposed or other signs of leave the site at the desired location; erosion damage are present. Overflow is stabilized and appropriately armored. Permeable Pavers Broken or missing Broken or missing paving blocks on surface of No missing or broken paving blocks pavers pavement. interfering with infiltration. Level surface Uneven surface due to settlement or scour of fill Pavement surface is uniformly level. in the interstices of the paving blocks. Compaction Poor infiltration due to soil compaction between No soil compaction in the interstices paving blocks. of the paver blocks limiting infiltration. Dead grass Grass in the interstices of the paving blocks is Healthy grass is growing in the dead. interstices of the paver blocks. Inspection Frequency Annually and after large storms, and as needed Permeable pavement is functioning seasonally to control leaf drop, evergreen normally. needles etc. 4/24/2016 2016 Surface Water Design Manual — Appendix A A-38 Appendix E Contech Stormfilter Plans & Maintenance Standards C►NTECH® ENGINEERED SOLUTIONS StormFilter Inspection and Maintenance Procedures ,�0 The Stormwater Management StormFilter, Maintenance Guidelines The primary purpose of the Stormwater Management StormFilter® is to filter and prevent pollutants from entering our waterways. Like any effective filtration system, periodically these 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 many effective maintenance options, we believe the following procedure to be efficient, using common equipment and existing maintenance protocols. The following two-step procedure is recommended:: 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 maintenance 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, during dryer months in late summer to early fall. Maintenance Frequency The primary factor for determining frequency of maintenance for 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. The average maintenance lifecycle is approximately 1-5 years. 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. Regulatory requirements or a chemical spill can shift maintenance timing as well. 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.. 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 Engineered 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 the forebay, 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 req u i red. 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 above cartridge bottom for more than 24 hours after end of rain event, maintenance is required. (Catch basins have standing water in the cartridge bay.) 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. 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 Engineered Solutions. Warning: In the case of a spill, the maintenance personnel should abort maintenance activities until the proper guidance is obtained. Notify the local hazard control agency and Contech Engineered Solutions immediately. To conduct cartridge replacement and sediment removal maintenance: 1. If 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 lbs. 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). Disconnect each filter cartridge from the underdrain connector by rotating counterclockwise 1/4 of a turn. Roll the loose cartridge, on 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 Engineered Solutions for suggested attachment devices. 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. 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. 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). Disconnect each filter cartridge from the underdrain connector by rotating counterclockwise 1/4 of a turn. Roll the loose cartridge, on edge, to a convenient spot beneath the vault access. B. Unscrew the cartridge cap. C. Remove the cartridge hood and float. D. At location under structure access, tip the cartridge on its side. E. Empty the cartridge onto the vault floor. Reassemble the empty cartridge. F. Set the empty, used cartridge aside or load onto the hauling truck. G. Continue steps a through a 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. 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 of the accumulated materials in accordance with applicable regulations. Make arrangements to return the used em t cartridges to Contech Engineered Solutions. Related Maintenance Activities - Performed on an as -needed basis StormFilter units are often just one of many structures in a more comprehensive 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. VIA 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). Areas 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. Date: Personnel: Location: System Size: System Type: Vault ❑ Cast -In -Place ❑ Linear Catch Basin ❑ Manhole ❑ Other Sediment Thickness in Forebay: Date: Sediment Depth on Vault Floor: Structural Damage: Estimated Flow from Drainage Pipes (if available): Cartridges Submerged: Yes ❑ No ❑ Depth of Standing Water: StormFilter Maintenance Activities (check off if done and give description) ❑ Trash and Debris Removal: ❑ Minor Structural Repairs: ❑ Drainage Area Report Excessive Oil Loading: Yes ❑ No ❑ Source: Sediment Accumulation on Pavement:. Yes ❑ No ❑ Source: Erosion of Landscaped Areas: Yes ❑ No ❑ Source: Items Needinq Further Work: Owners should contact the local public works department and inquire about how the department disposes of their street waste residuals. Other Comments: Review the condition reports from the previous inspection visits. Date: — _Personnel. _ Location: System Size: System Type: Vault ❑ Cast -In -Place ❑ Linear Catch Basin ❑ List Safety Procedures and Equipment Used: System Observations Months in Service: Oil in Forebay (if present): Sediment Depth in Forebay (if present): Sediment Depth on Vault Floor: Structural Damage: Yes ❑ No ❑ Drainage Area Report Excessive Oil Loading: Yes ❑ No ❑ Source: Sediment Accumulation on Pavement: Yes ❑ No ❑ Source: Erosion of Landscaped Areas: 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 (estimate?): Minor Structural Repairs: Yes ❑ No ❑ Details: Residuals (debris, sediment) Disposal Methods: N otes: Manhole ❑ Other ❑ C-ATECH• ENGINEERED SOLUTIONS 02016 CONTECH ENGINEERED SOLUTIONS LLC. 800-338-1122 www.ContechES.com All Rights Reserved. Printed in the USA. Contech Engineered Solutions LLC 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 offerings, visit contech-cpi.com or call 800.338.1122. Support • Drawings and specifications are available at www.conteches.com. • Site -specific design support is available from our engineers. NOTHING IN THIS CATALOG SHOULD BE CONSTRUED AS AN EXPRESSED WARRANTY OR AN IMPLIED WARRANTY OF MERCHANTABILITY OR FITNESS FOR AN Y PARTICULAR PURPOSE. SEE THE CONTECH STANDARD CONDITIONS OF SALE (VIEWABLE AT WWW.CONTECHES.COM /COS) FOR MORE INFORMATION . StormFilter Inspection and Maintenance Procedures 8/2016 800.338.1122 www.conteches.com C%ov-NTECH' ENGINEERED SOLUTIONS CatchBasin StormFilterTM Important: These guidelines should be used as a part of your site stormwater plan. Overview The CatchBasin StormFilterTM (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 both 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 with 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 lighter solids and soluble pollutants are directed under the baffle and into the cartridge chamber through a port between the baffle and the overflow weir. OPERATION AND MAINTENANCE Once in the cartridge chamber, polluted water ponds and percolates horizontally through the media in the filter 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. Page 1 URBANGREENT`' Starmwater Soluliorns from Contech' Qi www.ContechES-com/stormwater 800-338-1122 © 2013 Contech Engineered Solutions C : z: d NTECH° ENGINEERED SOLUTIONS CatchBasin StormFilterT" Maintenance Guidelines Maintenance procedures for typical catch basins can be applied to the CatchBasin StormFilter (CBSF). 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 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 for cleaning. 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 as appropriate. Materials required include a lifting cap, vactor truck and fresh filter cartridges. Contact Contech 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 on an exchange basis. Contact the maintenance department of Contech at 503-258-3157 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. OPERATION AND MAINTENANCE 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. 3. Use of larvicides containing Bacillus thuringiensis israelensis (BTI). 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 CatchBasin 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://www. 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://www.ucmrp.ucdavis.edu/ publications/ma nag ingmosquitoesstormwater8125. pdf URBANGREEN'," ' Stormwater Solutions from Contech® ry'lf Page 2 www.ContechES.com/stormwater 800-338-1122 © 2013 Contech Engineered Solutions ACCESS COVER r17!_7�1A1�� { L 2-4—�� L 2-4" INSIDE RIM INSIDE RIM 6'-2" PLAN VIEW PRECAST CONCRETE TOP SLAB TO MEET HS25 LOADING VANED INLET GRATE (SOLID COVER OPTIONAL) STORMFILTER Ji I i� OUTLET PIPE WEIR WALL L __ �_� __ FLOATABLES BAFFLE fil lip lip } j I (OPTIONAL) INLET PIPES PLAN VIEW WITHOUT TOP SLAB STORMFILTER CARTRIDGE PERMANENT POOL ELEVATION CARTRIDGE SUPPORT FLOW KIT B �1 SECTION A -A OPTIONAL -OPED LID CLEANOUT .. ESS PLUG ON WEIR WALL STORMFILTER CONCRETE CATCHBASIN DESIGN NOTES STORMFILTER TREATMENT CAPACITY IS A FUNCTION OF THE CARTRIDGE SELECTION AND THE NUMBER OF CARTRIDGES. 1 CARTRIDGE CATCHBASIN HAS A MAXIMUM OF ONE CARTRIDGE. SYSTEM IS SHOWN WITH A 18" CARTRIDGE, AND IS ALSO AVAILABLE WITH AN 27" CARTRIDGE. PEAK HYDRAULIC CAPACITY PER TABLE BELOW. IF THE SITE CONDITIONS EXCEED PEAK HYDRAULIC CAPACITY, A DOWNSTREAM BYPASS STRUCTURE IS REQUIRED. CARTRIDGE SELECTION CARTRIDGE HEIGHT 27" 18" 18" DEEP RECOMMENDED HYDRAULIC DROP (H) 3.05' 2.3' 3.5' SPECIFIC FLOW RATE (gpm/sf 2 gpmisf 1,67'gpm1sfj 1 gpmisf 2 gpmisf 1.67' gpmisf 1 gpmisf 2 gpmisf 1.67*gpmlsfl 1 gpmisf CARTRIDGE FLOW RATE (gpm) 22.5 18.79 11.25 15 12.53 7.5 15 12.53 7.5 PEAK HYDRAULIC CAPACITY 1.0 1.0 1.8 INLET PERMANENT POOL LEVEL (A) 1'-7" 1'-7" 2-4" OVERALL STRUCTURE HEIGHT (B) 5'-0" 4%(r 5-0" 1.67 gpmisf SPECIFIC FLOW RATE IS APPROVED WITH PHOSPHOSORB ® (PSORB) MEDIA ONLY GENERAL NOTES 1. CONTECH TO PROVIDE ALL MATERIALS UNLESS NOTED OTHERWISE. 2. FOR SITE SPECIFIC DRAWINGS WITH DETAILED STORMFILTER CATCHBASIN STRUCTURE DIMENSIONS AND WEIGHTS, PLEASE CONTACT YOUR CONTECH ENGINEERED SOLUTIONS LLC REPRESENTATIVE. www.ContechES.com 3. STORMFILTER CATCHBASIN WATER QUALITY STRUCTURE SHALL BE IN ACCORDANCE WITH ALL DESIGN DATA AND INFORMATION CONTAINED IN THIS DRAWING. 4. INLET SHOULD NOT BE LOWER THAN OUTLET. INLET (IF APPLICABLE) AND OUTLET PIPING TO BE SPECIFIED BY ENGINEER AND PROVIDED BY CONTRACTOR. 5. CONCRETE STRUCTURE TO BE MANUFACTURED OF PRECAST CONCRETE TO MEET HS25 LOAD RATING. CASTINGS SHALL MEET AASHTO M306 LOAD RATING. 6. FILTER CARTRIDGES SHALL BE MEDIA -FILLED, PASSIVE, SIPHON ACTUATED, RADIAL FLOW, AND SELF CLEANING. RADIAL MEDIA DEPTH SHALL BE 7-INCHES. FILTER MEDIA CONTACT TIME SHALL BE AT LEAST 38 SECONDS. 7. SPECIFIC FLOW RATE IS EQUAL TO THE FILTER TREATMENT CAPACITY (gpm) DIVIDED BY THE FILTER CONTACT SURFACE AREA (sq ft). INSTALLATION NOTES A. ANY SUB -BASE, BACKFILL DEPTH, AND/OR ANTI -FLOTATION PROVISIONS ARE SITE -SPECIFIC DESIGN CONSIDERATIONS AND SHALL BE SPECIFIED BY ENGINEER OF RECORD. B. CONTRACTOR TO PROVIDE EQUIPMENT WITH SUFFICIENT LIFTING AND REACH CAPACITY TO LIFT AND SET THE CATCHBASIN (LIFTING CLUTCHES PROVIDED). C. CONTRACTOR TO TAKE APPROPRIATE MEASURES TO PROTECT CARTRIDGES FROM CONSTRUCTION -RELATED EROSION RUNOFF. FLOATABLES BAFFLE PERMANENT POOL ELEVATION FINISHED GRADE (OPTIONAL) INLET PIPES L 2'-O• 2-91 SECTION B-B FILTRATION BAY INLET a i_ m — WEIR WALL IN FLOW OUTLET}PIPE OUTLET FROM FILTER 1-CARTRIDGE CATCHBASIN STORMFILTER DATA STRUCTURE ID XXX WATER QUALITY FLOW RATE cfs X.XX PEAK FLOW RATE <1 Cfs X•XX RETURN PERIOD OF PEAK FLOW rs XXX CARTRIDGE HEIGHT 27", 19% 18" DEEP XX CARTRIDGE FLOW RATE m XX MEDIA TYPE PERLITE, ZPG, PSORSJ XXXXX RIM ELEVATION XXx.xx' PIPE DATA: I.E. DIAMETER INLET STUB XXX•XX' I XX" OUTLET STU B XXx•XX' I xx" CONFIGURATION OUTLET OUTLET INLET d I( )I I( ]I pINLET INLET INLET SLOPED LID YES1NO SOLID COVER YESkNO NOTES/SPECIAL REQUIREMENTS: TiM Sfamw.fe�/Aana 5tormFi lter" TIR I PUMP STATION 33B I LAKEHAVEN WATER & SEWER DISTRICT Appendix G SITE DRAINAGE PLAN FINAL I JANUARY 2020 0 ! m 0 5' 10, W C 2 3 TOP OF WALL (TOW) 173.8 TOW 173-6 TOW STEP (TYP) . TOW 1731. ' 1 26 Tow 173.1 I TOW 1724 I TOW = 1724--�_ TOW=171.7� D S02 CB pt PE I CB TY rn RIM = 171.00 " B" INV OUT = 167.0(E) a TOW=171.7- E 5 6 7 r --173.6 7 -- VALVE BOX _ (TYP) u 5 172.9 172.7 3 27 jJ/�L 10 12: e TOW = 173.1 14 _ w ❑- .. ` �! + \ \ \ o -44 1s C7 C� it O N w O oP f4 TOW o- 172 22El 70W=771 TOW=171.0- L_171.0 5 8 SO q! TOW I y�`t 'VW'Y_ YY11 CB #2 STORMFILTER CB RIM = 171.0 B" INV IN = 165.7(W) 8" INV OUT = 165.6(E) WNG BLOCK WALL 7 TOW = 171.7 l / i CB #3 SEE DETAIL 5/C06 0• TYPE 1 CB W/ SOLID COVER (LOCKING) 164.0 (ADJUST TO GRADE) B' NV IN- 162.0 (W) 8" INV OUT = 161,3 (NE) 8" INV OUT =161.3 TOW = 171,0 1 ENLARGED PLAN SCALE: I'm 1W FILE: 105B1A100000101 y eii GENERALNOTES LEGEND 1. ITEMS ENCOUNTERED ON SITE (INCLUDING BELOW GRADE) NOT SHOWNONTHE DRAWINGS SHALL BE POROUS ASPHALT INSTALLED BROUGHT TO THE ATTENTION OF THE OWNER'S PER DETAIL4/C06 REPRESENTATIVES IMMEDIATELY. 2 THE LOCATION OF EXISTING UTILITIES SHOWN ON THE DRAWINGS IS APPROXIMATE AND MAY VARY IN THE FIELD. ADDITIONAL UTILITIES MAY EXIST ON SITE THAT ARE NOT SHOWN ON THE DRAWINGS VERIFY THEACTUAL LOCATION OF ALL UTILITIES BEFORE ANY CONSTRUCTION ACTIVITIES COMMENCE THE CONTRACTOR SHALL NOTIFY THE ENGINEER OF ANY PERIMMING INFOR A I DIFFERENCES OF CONSEQUENCE. TOTAL SITE AREA= 9,500 SF(0218 ACRES) 3• MAINTAIN T-O'MINIMUM COVER OVER ALL PIPING. EXISTING IMPERVIOUS AREA= 1.3465F(0.031 ACRES) THIS IS TYPICAL UNLESS 01HEIIM SE NOTED ON THE PROPOSED POROUS ASPHALT = 4.050 SF (0,099 ACRES) DRAWINGS PROPOSED IMPERVIOUS AREA = 7,519 SF (%l73 ACRES) A MAINTAIN 10'-0" HORIZONTAL AND 18" VERTICAL PIPE -TO -PIPE SEPARATION BETWEEN POTABLE INCLUDES POROUS ASPHALT P ER CODE WATER AND NON -POTABLE PIPING UNLESS OTHERWISE NOTED ON PLANS, POTABLE WATER LINES SHALL PASS OVER NON -POTABLE PIPING UNLESS OTHERWISE NOTED ON PLANS. PUMP STATION 33B COMINMES 5. SEE SPECIFICATIONS FOR ADDITIONAL MATERIAL POINTS NORTHING EASING DESCRIPTION N: 55704.93 E: 71 D41.28 ELECTRICAL / GENERATOR BLDG WALL CORNER / REF S05 2 N: 55670-51 E: 71007-65 ELECTRICAL I GENERATOR BLDG WALL CORNER / REF S05 N: 55737.66 E: 71009L 17 VALVE VAULT CORNER REF S03 N: 5570922 E: 71030.73 T WELL CORNER I REF S03 �FL.WWWETER CD N: 55759.52 E: 71026,49 VAULT CORNER I REF SOB N: 55744-59 E: 71011,74 FLOW METER VAULT CORNER / REF S08 �B N: 55765.59 E: 70999A3 N:5576559 E:71010.46 10 N: 55751.49 E: 71049.46 11 N: 55756.19 E: 71051,16 12 N: 55746.55 E: 71071.95 19 N: 55745.12 E: 71075.92 14 N: 55727.14 E: 71058 86 15 N: 55712 85 E: 7109.47 16 N: 55714.01 E: 7071,06 17 N: 55710-12rE: 074.95 18 N: 5571242046.52 19 N: 55706.250SUll 20 N: 55692.02065,79 N: 55698L96 :074,64 22 N: 55605,55 E: 71050.27 23 N: 55672-93 E: 7105EL72 24 N: 55664A6 E: 71063,79 O N: 70991.70 1 E: 55666.45 26 N: 55737.13 E: 701193,65 27 N: 55740.70 E: 70998.75 PESUBMIITTALW uc aA5N Qrp}WAS SIC } NOT FOR CONSTRUCTION O DEN CHECKED�►�r�lloLakehaVen � 2 01116/20 BAS CITY OF FEDERAL WAY: BUILDING PERMIT RESUBMITTAL TJW 9� ems Piovidiny :valci and services 1 09/19/19 BAS CITY OF FEDERAL WAY: LAND USE PERMIT RESUBMITTAL 17AT'E `0fo® Ip colnniunllies In South King Cot;nty. g REV DATE BY DESCRIPTION MAY 2019 1 2 3 4 5 6 7 B 9 PRO.IFrT NO 10.RR1A10 FII F NAMF- 105RIAlonoco d Ann AND INSTALLATION REQUIREMENTS 6, CATCH BASINS SHALL BE TYPE I CB'S PER WSDOT STANDARD PLAN B-5.20-02, EXCEPT AS OTHERWISE NOTED IN THE CONTRACT DOCUMENTS 7, PAVEMENT IMMEDIATELY ADJACENT TO GENERATORIELECTRICAL BUILDING, VAULT LIDS, MANHOLE LIDS, AND CONCRETE PADS SHALL BE SLOPED TO DRAIN WAY FROM THESE STRUCTURES. KEY NOTES = O 1 PROVIDE PENETRATION IN RETAINING WALL FOR 8" SD. PER MANUFACTURES RECOMMENDATIONS 2 PROVIDE 8' TEE FOR DROP CONNECTION TO CB 03. FIT VERTICAL END WITH CLEANOUT ADAPTER AND CLEANOUT PLUG, 3 PROVIDE VALLEY GUTTER AT PROPERTY LINE PER DETAIL C104/TYP. 4 INSTALL 18" THICK RIP -RAP AT VALLEY GUTTER OUTLET- 5 SLOPE8"SDATZO 6 INSTALL DISPERSION TRENCH PER DETAIL 5/CO6. PROVIDE MINIMUM 1' SEPERATION WITH I INE. 7 GRADE TO DRAIN TO LANDSCAPING. Q1 D V R. ❑ 2 9 E CI I TI _ 5_ 6 OR STORMFILTER CATCHBASINREOUIREMENTS, NOTE: THIS APPROVAL IS VOID 1 (ONE) YEAR AFTER APPROVAL DATE THE CITY WILL NOT BE RESPONSIBLE FOR ERRORS AND/OR OMISSIONS ON THESE PLANS. FIELD CONDITIONS MAY DICTATE CHANGES TO THESE PLANS AS DETERMINED BY THE CITY ENGINEER PERMIT NO. 19-105596-00-CO APPROVED DATE LAKEHAVEN WATER & SEWER DISTRICT SANITARY SEWER PUMP STATION 33B CIVIL PAVING, GRADING AND DRAINAGE PLAN in 1 11 1 12 Joe N . MRIFY SCALES 1ose1alo BAR IS ONE INCH ON ORIGINALDRAWING DRAWING NO. O�1° C04 IFNOTONEINCHON SHEET NO, T]ie4611EET.A UST SCALES mmmul04Y 25 OF 74 a l4 oA z CONTROL STRENGT (CLSM)PE B E � I EX 60" CMP NOTES: CULVERT 1. THE CLSM BLANKET SHALL EXTEND LONGITUDINALLY TO THE FIRST JOINT BEYOND THE PROPOSED PIPE'S TRENCH EXCAVATION, TO A MAXIMUM OF 4' BEYOND THE PROPOSED PIPE TRENCH EXCAVATION ON EITHER SIDE 3 CLSM BLANKET FOR PIPE CROSSING CO2 SCALE: NTS FILE: - (SIDE VIEW) 121111 ELECTRICAL WFIAPPED FOR CENT" BACKF•LOW LHEATTAPE [INCL.OUPLEX RECEPTACLE]. PREVENTER IN ENCLOSURE 'HOT ].STALL HEAT TAPE FORFREEIE EHp.C$URE 3- PROTECTION. BOX- MODEL 75 SEE ELECTRICAL. OR EQUAL FINISHED CONNECT TO WATER METER IMMEDIATELY ADJACENT TO 5 6 � ✓� � r� PIPE 11-0" END CAP OR PLUG 1B O.0 2- b.D. _ _ POROUS HOT ASPHALT (PHMA) IX TT6" CLEAN OUT WYE FROM PIPE CHOKER COURSE ACING 2V-2' r PERFORATED SDR-26 PVC PIPE 24" PERMABLE BALLAST NOTCHES LAID FLAT/LEVEL NOTES: ff 1 /�% SEE NOTEFILTER BRIC 1. THIS TRENCH SHALL BE CONSTRUCTED SO TO PREVENT POINT DISCHARGE AND(OR EROSION. 2. TRENCH AND GRADE BOARD MUST BE LEVEL.f— _ SUBGRADE R r$TUCTURAL FILL COMPACTED PER ALIGN TO FOLLOW CONTOURS OF SRE. �� X\��. SPECIFICATIONS) 3. SUPPORT POST SPACING AS REQUIRED BY SOIL CONDITIONS TO ENSURE GRADE BOARD INFLUENT PIPE REMAINS LEVEL A A NOTES: 1. FILTER FABRIC SHALL EXTEND VERTICALLY TO 1" BELOW FINISHED SURFACE AT ALL LIMITS OF PAVING. 2, SEE SECTION DIS02 FOR PLACEMENT OF GEOGRID REINFORCEMENT TYPE 1 CB WISOLID 2 COVER (LOCKING) 3. SEE SECTION 32_12_43 R COMPACTION AND OTHER POROUS ASPHALT REQUIREMENTS. POROUS ASPHALT PAVEMENT SECTION NOTCHED GRAD rLEA9 OUT WYE SCALE. NTS BOARD 2" x 2' PLAN FROM NOTCHES 1B' O.C. PIPE FILE: - GALVANIZED BOLTS r,ty, PIPE 5'-0' Q D. Y v1.4 II ., /I I �L 4' MIN CONCRETE PAD PER CABLEISI IN RIGID MANUFACTURER CONDUIT PER ELECTRICAL �SLE'EVE (ryp.) -POLY T'Yn x COPPER. GRASS. OR APPROVED EQUAL NOTES: 1. THE ASSEMBLY MUST BE PROTECTED FROM FREEZING, OTHER SEVERE WEATHER, AND FROM ACCIDENTAL DAMAGE. 2. DRAIN SHALL BE SIZED IN ACCORDANCE WITH AW WA CROSS CONNECTION CONTROL MANUAL 6-8. 3. RPRA MUST BE ON WASHINGTON STATE DOH APPROVED LIST, MUST BE TESTED UPON INSTALLATION BY A WASHINGTON STATE CERTIFIED BACKFLOW ASSEMBLY TESTER, AND MUST BE TESTED ANNUALLY THEREAFTER. RPBASHALL GE FEBCQMODEL 825Y OR EQUAL- 4. ENCLOSURE MUST BE PAD LOCKABLE. CLEAN( %FINES) 1112'-314'WASHED ROCK WPERFORATED SDR-26 PVC PIPE i LAID FLATILEVEL 2' x 12" PRESSURE TREATED 10 FILTER FABRIC 4' x 4" PRESSURE TREATED SUPPORT POST @ 6'-O" QC. MIN 7 5 DISPERSION TRENCH 3" HMA OR MATCH - SCALE: NTS EXISTING THICKNESS, FILE: - WHICHEVER IS GREATER 2" CSTC COMPACTED TOA MINIMUM 4856 0E ITS MAX DRY DENSfYY (PERASTM 07557) COMPACTED TO A oo RY DENSITY [PER ASTM 015W) SUBGF+/+DE PREPARED PER SPECIFICAYIONS NOTES: 1. SEE SECTION 32_01_16 AND 32_12_15 FOR ADDITIONAL PAVING REQUIREMENTS. 2. SEE SECTION 31_05_15 FOR ADDITIONAL AGGREGATE AND COMPACTION REQUIREMENTS. 3. EXISTING ROADWAY MARKINGS (SHOULDER LINES, LANE DIVIDERS, ETC) SHALL BE REPLACED IN -KIND PER SECTION 32_17_23 FOLLOWING PAVING. S359TH (LOCAL STREET) 6 REDUCED PRESSURE BACKFLOW ASSEMBLY RPBA ? ROADWAY REPLACEMENT SECTION SCALE: NTS SCALE' NTS FILE: - FILE: - DESIGNED PERMIT REVIEW BAS tiPH A. St�0 SUBMITTAL LakehaVen NOT FOR CONSTRUCTION O DE CHECKED N m^go �roJlo WATER &SEWER DISTRICT 2 12112119 BAS CITY OF FEDERAL WAY: BUILDING PERMIT RESUB TJW it a �Q Providing water and sewer services 09/19119 BAS CITY OF FEDERAL WAY: LAND USE PERMIT RESUBMITTAL DATE 1� `k� l0 communities in South King County MAY 2019 REV DATE BY DESCRIPTION s»nt c 1 1 2 3 4 5 6 7 6 9 PRO.IFCT NO 105n1A1n FIIFNAMF: ln5R1A1nnnC00fi Ann LAKEHAVEN WATER & SEWER DISTRICT SANITARY SEWER PUMP STATION 33B CIVIL DETAILS - II A -A NOTE: THIS APPROVAL IS VOID 1 (ONE) YEAR AFTER APPROVAL DATE. THE CITY WILL NOT BE RESPONSIBLE FOR ERRORS AND/OR OMISSIONS ON THESE PLANS, FIELD CONDITIONS MAY DICTATE CHANGES TO THESE PLANS AS DETERMINED BY THE CITY ENGINEER PERMIT NO. 19-105596-00—CO APPROVED 12 JOB o. JERIFY SCALES 1o5B1A.1A.10 BAR IS ONE INCH ON DRAWING NO. ORIGINAL DRAWING 0 •�� 1" C06 IF NOT ONE INCH ON SHEET NO. THIS SHEET, ADJUST SCALES ACCORDINGLNI 27 OF 74 I 4 2"x2" 14 GA WIRE OR EQUIVALENT, IF STANDARD STRENGTH FABRIC USED 7 a POST N 0 N z T s a X F 114' RADIUS 2,-0' TOOLED EDGE AC PAVING /— 3 r 1" SEE DRAWINGS FOR PAVEMENT SECTION #4@12-- m NOTES: 1_ pROVIDE V4' EXPANSION JOINTS AT ENOS OF CONCRETE PLACEMENT, AT POINTS OF CURVATURE, AT INTERSECTIONS, AND AT MA%[MUM SPACING OF 30 FEET. EXPANSION JOINTS SHALL BE 314' WIDE WITH 1/4' RADIUS CONCRETE EDGES AT BOTH SIDES Of JOINT. USE BITUMINOUS FIBER EXPANSION JOINT MATERIAL 2. DO NOT PASS REINFORCING BARS THROUGH EXPANSION JOINTS. 3. PROVIDE WEAKENED PLANE JOINTS AT 10 FEET OC MAXIMUM. AT FRONT, TOP AND BACK FACES, PROVIDE 1/2-RAOIUSEO EDGE EACH SIDE AT JOINTS. C104 CROSS GUTTER AND VALLEY GUTTER TYP J 07/25/13 NOTE: 1. DRIVEWAY SHALL MEET THE REQUIREMENTS OF THE PERMITTING AGENCY 2 CROWN ENTRANCE SO THAT RUNOFF DRAINS OFF THE PAD C107 STABALIZED CONSTRUCTION ENTRANCE J 10111/18 PRO.IFCT NO 105M A10 LL WIDTH OF INGRESS/EGRESS AREA JOINTS IN FILTER FABRIC SHALL BE SPLICED AT POSTS, MIN 6" OVERLAP. USE MIN 1"STAPLES. WIRE RINGS OR EQUIVALENT TO ATTACH TO POSTS. 8" MAX IF WIRE BACKING USED FILTER FABRIC FENCE NOTES: A- THE FILTER FABRIC SHALL BE PURCHASED IN A CONTINUOUS ROLL CUT TO THE LENGTH OF THE BARRIER TO AVOID USE OF JOINTS. B. THE FILTER FABRIC FENCE SHALL BE INSTALLED TO FOLLOW THE CONTOURS WHERE FEASIBLE. WHEN JOINTS ARE NECESSARY, FILTER CLOTH SHALL BE SPLICED TOGETHER ONLY AT A SUPPORT POST, BOTH ENDS SECURELY FASTENED TO THE POST A MAXIMUM OF 6 FEET APART AND DRIVEN SECURELY INTO THE GROUND. C WHEN STANDARD STRENGTH FILTER FABRIC IS USED, A WIRE MESH SUPPORT FENCE SHALL BE FASTENED SECURELY TO THE UPSLOPE SIDE OF THE POSTS. D. THE STANDARD STRENGTH FILTER FABRIC SHALL BE STAPLED OR WIRED TO THE FENCE. FILTER FABRIC SHALL NOT BE STAPLED TO EXISTING TREES. FILTER FABRIC Q xm WIRE MESH t 4 LL n� LL MIN 12'x12" TRENCH. BACKFILL W/ NATIVE SOIL OR 3YV TO 1 V0 WASHED GRAVEL E, WHEN EXTRA -STRENGTH FILTER FABRIC AND CLOSER POST SPACING ARE USED, THE WIRE MESH SUPPORT FENCE MAY BE ELIMINATED. IN SUCH A CASE, THE FILTER FABRIC IS STAPLED OR WIRED DIRECTLY TO THE POSTS WITH ALL OTHER PROVISIONS OF THE STANDARD NOTES APPLYING. F. FILTER FABRIC FENCES SHALL BE REMOVED WHEN CONSTRUCTION ACTIVITY IS COMPLETE AND THE UPSLOPE AREA HAS BEEN PERMANENTLY STABILIZED. G. FILTER FENCES SHALL BE INSPECTED DAILY AND IMMEDIATELY AFTER EACH RAINFALL DURING PROLONGED RAINFALL ANY REQUIRED REPAIRS SHALL BE MADE IMMEDIATELY. C105 FILTER FABRIC FENCE TYP J 10/11118 NOTES: 1. STOCKPILE SHALL BE COVERED WITH VISQUEEN PLASTIC (MIN. 6 MIL) IF IT IS TO REMAIN UNWORKED FOR MORE THAN 12 HOURS DURING THE WET SEASON (OCT. 1 -APRIL 30) AND FOR MORE THAN 7 DAYS DURING THE DRY SEASON (MAY 1 - SEPT. 30). 2. DURING THE WET SEASON, MATERIAL REQUIRED TO COVER STOCKPILE MUST BE STORED ON SITE, 3. STOCKPILE SHALL NOT BE PLACED IN AN AREA WITH A SLOPE GREATER THAN 20 % . 4. STOCKPILE AREA SHALL HAVE FILTER FABRIC FENCE INSTALLED AROUND ENTIRE AREA AN OPENING ACCESS SHALL BE LOCATED ON THE UPHILL SIDE, AND SHOULD BE CLOSED WITH FILTER FABRIC FENCE WHEN NOT IN USE. C108 STOCKPILING DETAIL TYP J 10/11/1 B PERMIT REVIEW - "` BAS"CI SUBMITTAL DRAWN NOT FOR CONSTRUCTION RCP CHECKED BTEDATEDESCRIPTION MAY2019 2 3 4 Fit F NAMF- 10591A1n TC01 rinn o' C141 EXTRUDED CURB C161 REMOVABLE GUAR! TYP TYP J 10/11/18 N .CP LAKEHAVEN WATER & SEWER DISTRICT LakehaVen SANITARY SEWER PUMP STATION 33B WATER & SEWER DISTRICT CIVIL Providing water and sewer services CIVIL TYPICAL DETAILS - 1 to communities in South King County. a 4 10 f 1.1 �! Vx 1'STAKE (28 x �5MM I NOTE: 1. STRAW ROLL INSTALLATION REQUIRES THE PLACEMENT AND SECURE STAKING OFTHE ROLL IN TRENCH, 3• - 5" (75-125mm) DEEP, DUG ON CONTOUR RUNOFF MUST NOT BE ALLOWED TO RUN UNDER OR AROUND ROLL, FC-1-06-1 STRAW WATTLE TYP J 10/11/18 WELD ON CAP 1 i ETE PAVEMENT 4"0 GALV SCH 40 STEEL POST. PAINT SAFETY YELLOW PER TUMINOUS ANSI Z535.1. EXP JOINT II oIAL ALL AROUND (UNLESS FINISHED GRADE WISE INDICATED OR AC PAVEMENT. E DRAWINGS) SEE DRAWINGS. AT CONC B '_PIP JAR PAVEMENT 5"0 SCHEDULE 80 „l + PVC PIPE SLEEVE .v I � CLASS 'C" CONCRETE NOSE OVAL IS VOID 1 (ONE) YEAR AFTER APPROVAL A RESPONSIS L"—"—IFIELD ON THESE CONDITIONS MAY DICTATE CHANGES TO THESE PLANS AS DETERMINED BY THE CITY ENGINEER. A AC PAVEME NO. 19-105596-00—CO FINISHED APPROVED POST DATE VIIl JIl4 I—. ' 10581A.10 BAR IS ONE INCH ON ORIGINAL DRAWING DRAWING NO. D 1" TC01 IF NOT ONE INCH ON SHEET NO. THIS SHEET, ADJUST SCALES ACCORDINGLY 9 OF 74 B C TIR I PUMP STATION 33B I LAKEHAVEN WATER & SEWER DISTRICT Appendix H CRITICAL AREAS REPORT Carty/I.1„ FINAL I JANUARY 2020 LAKEHAVEN WATER AND SEWER DISTRICT PUMP STATION 33B Critical Areas Report and Conceptual Mitigation Plan Prepared for Lakehaven Water and Sewer District Federal Way, Washington March 2019 ERN Pump Station 33B Critical Areas Report CONTENTS 1.0 Project Authorization and Scope of Work......................................................................................1 2.0 Project Overview and Description..................................................................................................1 SITEDESCRIPTION................................................................................................................................................1 PROJECTDESCRIPTION..........................................................................................................................................1 2.1.1 Pump Station 33b..................................................................................................................1 2.1.2 Gravity Sewer Line and Force Main.......................................................................................2 3.0 Exisitng Conditions..........................................................................................................................2 STREAMS............................................................................................................................................................ 2 WETLANDS.........................................................................................................................................................2 WELLHEADPROTECTION AREAS ...................... ......................................................................................................... 3 4.0 Results of Field Investigation..........................................................................................................3 WETLANDDETERMINATION...................................................................................................................................4 4.1.1 Wetland D..............................................................................................................................4 4.1.2 Wetland E..............................................................................................................................4 4.1.3 Wetland F..............................................................................................................................5 STREAMS............................................................................................................................................................ 5 4.1.4 North Fork West Hylebos Creek.............................................................................................5 OTHERWILDLIFE HABITATS....................................................................................................................................5 5.0 Project Impacts and regulatory Requirements.............................................................................. 6 BUFFERIMPACTS..................................................................................................................................................6 6.0 Buffer Mitigation Plan..................................................................................................................... 7 MITIGATIONSEQUENCING.....................................................................................................................................7 6.1.1 Avoiding Impacts through Construction BMPs......................................................................8 6.1.2 Construction Dewatering.......................................................................................................8 BUFFERMITIGATION STRATEGY..............................................................................................................................9 6.1.3 Mitigation Goals, Objectives, and Performance Standards.................................................11 6.1.4 Mitigation Construction Plan...............................................................................................11 MONITORING....................................................................................................................................................12 6.1.5 Schedule...............................................................................................................................12 6.1.6 Data Collection....................................................................................................................12 6.1.7 Reporting 13 MAINTENANCE..................................................................................................................................................13 CONTINGENCY...................................................................................................................................................13 7.0 Limitations.....................................................................................................................................13 8.0 References.....................................................................................................................................14 FIGURES......................................................................................................................................................17 APPENDIXA: METHODS...........................................................................................................................A-1 APPENDIX B: COMMON AND SCIENTIFIC NAMES OF PLANTS AND THEIR WETLAND INDICATORSTATUS..................................................................................................................... B-1 APPENDIX C: WETLAND DETERMINATION DATA SHEETS AND RATING FORMS....................................C-1 APPENDIXD: SITE PHOTOGRAPHS...........................................................................................................D-1 ESA page March 2019 Pump Station 33B Critical Areas Report LIST OF TABLES Table 1. Summary of Wetlands and Streams Identified in the Pump Station 33b Study Area....................3 Table 2. Buffer Mitigation Plant Species.......................................................................................................9 LIST OF FIGURES 1 Vicinity Map 2 Critical Areas Map 3 Priority Habitats and Species Map 4 Soils Map 5 Wetland and Stream Survey Map 6 Project Impacts and Conceptual Mitigation Plan page ii March 2019 ESA Pump Station 33B Critical Areas Report 1.0 PROJECT AUTHORIZATION AND SCOPE OF WORK The Lakehaven Water and Sewer District (District) is proposing to construct a new sewer pump station (Pump Station 33B) and pipelines to serve existing development and increased growth in the City of Federal Way (City), Washington. At the request of the District, Environmental Science Associates (ESA) delineated wetland boundaries and streams and prepared this technical report and mitigation plan for the proposed project. This report is organized to meet the requirements of the City's critical areas code, Chapter 19.145 — Environmentally Critical Areas. Other critical areas regulated by the City include critical aquifer recharge areas, wellhead protection areas, geologically hazardous areas, and lakes. ESA's scope of work for this project is limited to wetlands and streams; however, other types of critical areas regulated by the City and present in the project vicinity are briefly discussed. 2.0 PROJECT OVERVIEW AND DESCRIPTION The project location is east of State Route (SR) 99 (NE % of Section 29, Township 21N, Range 4E; Figure 1) in Federal Way, WA. The project area and site for this critical areas study is located south of S 359tn Street. The project will occur on Parcels 2921049152 and 2921049157 and within City right-of-way. Site Description The site lies within the Hylebos Creek watershed (WRIA 10). The North Fork West Hylebos Creek crosses the eastern edge of the study area (Figure 1). This stream joins with the main stem West Hylebos Creek approximately 0.75-mile south of the project area and the water eventually enters Puget Sound in approximately 4 miles. The site generally slopes from the northwest to southeast toward the North Fork West Hylebos Creek (Figure 1). An approximately 450-foot paved driveway is located on the west side of this study area that facilitates access to the existing sewer pump station. The pump station is surrounded by a cyclone fence and consists of one building built on a paved turn -out. Adjacent to both sides of the paved driveway, mowed grass occupies an approximately 10-foot swath. Beyond the grass, closed -canopy forest exists to the west, south, and east. Project Description The District proposes to construct a sewer pump station and appurtenances (Pump Station 33B) along with a new gravity sewer line and force main. The proposed facilities will be located in public road rights -of -way and easements dedicated to the District. 2.1.1 Pump Station 33B The pump station will include a rectangular wet well and valve vault with approximate dimensions of 28 feet by 23 feet by 23 feet deep and separate flow meter vault with approximate dimensions of 17 feet by 14 feet by 11 feet deep. Other facilities will include an electrical building to house electrical ESA page 1 March 2019 Pump Station 33B Critical Areas Report equipment and a standby generator, an aboveground diesel fuel storage tank, packaged odor control system, transformer, and terminal enclosures, influent manholes, and related facilities. All of these structures will be surrounded by a retaining wall set atop a quarry spall base. 2.1.2 Gravity Sewer Line and Force Main The project includes approximately 380 feet of 48-inch gravity sewer line and approximately 110 feet of 10-inch force main. The new 10-inch force main will be constructed within the permanent pump station easement and within the right of way. The force main and the gravity line will be 6 to 8 feet deep on average. The deepest portion of the gravity line (15 feet) will be located at the pump station site. 3.0 EXISITING CONDITIONS Critical areas regulated by the City and mapped within the study area include one stream (North Fork Hylebos Creek), wetlands, and wellhead protection areas (Figure 2). Existing information about these critical areas and applicable City code requirements is provided below. Streams The Washington Department of Fish and Wildlife (WDFW) Priority Habitat and Species (PHS) identifies both winter steelhead trout and coho salmon in the North Fork West Hylebos Creek (PHS, 2019; Figure 3). Salmonscape maps also show both of these species in addition to fall Chinook salmon, fall chum salmon, and pink salmon (odd year) in this stream and in West Hylebos Creek located to the west of the study site (Salmonscape, 2019). The latest critical areas mapping shows North Fork West Hylebos Creek on this site (Federal Way, 2016). Wetlands ESA reviewed existing literature to determine the likely presence of wetlands including soils maps from the Natural Resources Conservation Service (NRCS), National Wetland Inventory (NWI) maps, and City critical area inventories. ESA reviewed NRCS soil inventory maps and identified one soil type mapped in the project area (Figure 4; NRCS 2013): Bellingham Silt Loam. Bellingham silt loam consists of very deep, poorly drained soil in depressions on terraces. This soil type forms in a mixture of loess, alluvium, and glacial deposits. Bellingham silt loam is listed as a hydric soil (NRCS, 2013). The City's critical areas maps show a large wetland system (in part labeled Spring Valley Open Space) extending along the North Fork West Hylebos Creek. This wetland system encompasses part of the study area (Figure 2). The National Wetland Inventory (NWI) maps also show wetlands within the project area (USFWS, 2019). The City categorizes wetlands based on the Washington Department of Ecology wetland rating system (FWRC 19.145.420(1)). Wetland buffers are based on the category of the wetland and the number of habitat points scored by the wetland during the wetland rating (FWRC 19.145.420(2)). Page 2 ESA March 2019 Pump Station 33B Critical Areas Report Wellhead Protection Areas The study area lies within a designated 100-year wellhead protection area (Figure 2). Wellhead protection areas are based on proximity to and travel time of groundwater to the City's public water source wells. City code regulates activities in these areas involving hazardous materials or other uses that could affect the water supply (FWRC 19.145.470 and 19.145.490). 4.0 RESULTS OF FIELD INVESTIGATION The following sections describe the results of the field investigation conducted by ESA biologists on February 10, February 13, and December 23, 2015. These sections describe critical areas identified and delineated on the site, including wetlands and streams. Methods used to identify these critical areas are included in Appendix A. Common plant names are used throughout this report; scientific names are provided in Appendix B. Wetland delineation data forms and rating forms are provided in Appendix C. The study area for this project is shown on Figure 5. The boundaries of the study area were established based on maps provided to the District. ESA identified one stream (North Fork West Hylebos Creek) and three wetlands designated as Wetlands D, E and F within the study site (Figure 5)1. The wetland boundaries and stream ordinary high water marks (OHWM) were flagged in the field and located by licensed surveyors. Wetland and stream characteristics are summarized in Table 1 and described below. Table 1. Summary of Wetlands and Streams Identified in the Pump Station 33B Study Area Wetland/ Area Stream ID <0.1 acre on site Wetland D (>30 acre located offsite) Wetland E 0.88 (onsite portion only) Hydrogeomorphic Vegetation (HGM) Class Community Types Depressional PFO Slope PFO City of Buffer Federal Way Requirement Rating/Typeb (feet) Category 1 225 Category III I 165 Wetland F 0.01 Depressional PEM Exempt Exempt NF West ` Hylebos — -- F 100 L Creek a PFO = palustrine forested; PSS = palustrine scrub -shrub; PEM = palustrine emergent. b Wetland categories are described in FWRC 19.145.420. Stream categories are provided in FWRC 19.145.260. Wetland buffers are listed in FWRC 19.145.420(2). Stream buffers are listed in FWRC 19.145.270. 1 A fourth wetland is located offsite, north of S 359th Street. This wetland is not discussed further in this report; however, the wetland's presence is noted should the project alignment change. ESA page 3 March 2019 Pump Station 33B Critical Areas Report Wetland Determination 4.1.1 Wetland D Wetland D is located southwest of the intersection of SR 99 and S 359th Street (Figure 5). The wetland slopes down to the south and is part of a large wetland complex (> 30 acre) that extends as far south as South 373rd street. Data Plot 8 characterizes the wetland and DP-11 characterizes the adjacent upland. Wetland data forms are in Appendix C. Site photographs are shown in Appendix D. Hydrology. Wetland D primarily receives water from a high groundwater table and exhibits characteristics of a depressional wetland. During the February 10, 2015 site visit, soil within a large portion of the wetland was saturated to the surface with a water table at 10 inches below the surface. Soils. Soil within Wetland D met requirements for hydric soil indicator All, Depleted Below Dark Surface. A black (10 YR 2/1) loam layer above a dark grayish brown (2.5YR 4/2 with 10 percent redox 10YR 4/6) was observed throughout the wetland. Vegetation. Wetland D is a palustrine forested wetland with a mixed canopy of deciduous and evergreen trees. Many of the trees are quite large and include red alder, black cottonwood, and western red cedar in the wetter areas and western hemlock and Douglas fir on raised hummocks. The dominant shrubs are red -osier dogwood, vine maple and salmonberry, which provide moderately dense cover. Skunk cabbage, creeping buttercup, large -leaved avens, and giant horsetail are the dominant herbaceous plants. Himalayan blackberry and reed canarygrass are common along the perimeter of the wetland. Wetland Category and Buffers. According to FWRC 19.145.420, Wetland D rates as a Category I wetland, with an overall rating score of 24 points and 9 Habitat points. Completed rating forms are in Appendix C. The wetland rates high overall because it has dense vegetation, an ability to improve water quality and reduce flooding, and provides multiple habitat functions. Category I wetlands with 9 Habitat points have a standard buffer width of 225 feet in Federal Way. 4.1.2 Wetland E Wetland E is located along the western stream bank of North Fork Hylebos Creek, south of S 359th Street (Figure 5). The wetland slopes down to the southeast to the stream and appears to extend offsite and on the east side of the stream. Data Plot 12 characterizes the wetland and DP 13 the adjacent upland. Wetland data forms are in Appendix C. Site photographs are shown in Appendix D. Hydrology. Wetland E primarily receives water from a high groundwater table and exhibits characteristics of the slope wetland. During the December 2015 site visit, wetland soil was saturated to the surface, had a water table at 10 inches below the surface, and had a hydrogen sulfide odor. Water leaves the wetland primarily by draining to the stream. Soils. Soil within Wetland E met requirements for hydric soil indicator F6, Redox Dark Surface. A black (10 YR 2/1) gravelly loam layer greater than 16 inches deep was observed throughout the wetland. Page 4 ESA March 2019 Pump Station 33B Critical Areas Report Vegetation. Wetland E is a palustrine forested wetland. The tree canopy consists primarily of red alder over the majority of the wetland. Lady fern, giant horsetail, and Himalayan blackberry are the dominant plants in the understory. Wetland Category and Buffers. According to FWRC 19.145.420, Wetland E is considered a Category III wetland, with an overall rating score of 16 points and 6 Habitat points. Completed rating forms are in Appendix C. The wetland provides moderate water quality (e.g., proximity of pollution generating surfaces) and floodwater attenuation (e.g., proximity of surface flooding downgradient) functions. Category III wetlands with 6 Habitat points have a standard buffer width of 165 feet in Federal Way. 4.1.3 Wetland F Wetland F is located adjacent to the east side of the driveway, between Wetlands D and E (Figure 5). The approximately 450 square -foot depressional wetland contains an emergent plant community and does not have a surface water connection to other wetlands or streams. Due to its small size Wetland F is exempt from buffer requirements under FWRC 19.145.420(3). The project will avoid direct impacts to all wetlands including Wetland F. Streams 4.1.4 North Fork West Hylebos Creek North Fork West Hylebos Creek is approximately 2 to 6 feet wide within the study area. The stream flows within a culvert beneath S 359th Street and then along the eastern boundary of Wetland E (Figure 5). The stream discharges to the main channel of West Hylebos Creek approximately 4,500 feet south of the study area. An overstory of red alder and understory dominated by salmonberry, provide significant riparian cover over the stream. Cobbles and gravels dominate the stream channel, forming riffles and glides within the channel. The West Fork is documented to support anadromous salmonids as discussed in Section 3.1. The City classifies streams in accordance with the Washington Department of Natural Resources water typing system (WAC 222-16-030). The North Fork West Hylebos Creek is classified as a Type F stream (i.e., supports fish habitat). The standard buffer width of Type F streams is 100 feet (FWRC 19.145.270(1)). Other Wildlife Habitats The study area contains primarily closed -canopy forest. The tree canopy consists of western red cedar, Douglas fir, western hemlock, red alder and black cottonwood. Many of these trees are quite large and together with a sub -canopy of small trees and dense understory of shrubs provide quality wildlife habitat. ESA page 5 March 2019 Pump Station 33B Critical Areas Report 5.0 PROJECT IMPACTS AND REGULATORY REQUIREMENTS The project was designed to avoid impacts to wetlands and streams. Impacts to buffer area are unavoidable because all areas outside of wetlands on the project site are within regulated buffers (Figure 6). Wetlands and streams are protected at the federal, state, and local levels and the City regulates the associated buffers of these resources. Buffer areas are regulated at the local level by the City. Public utilities are allowed within wetland buffer, provided no practical alternative with less impact on the critical area(s) exists (FWRC 19.145.120(1)). In addition, the specific location and extent of the intrusion into the buffer must constitute the minimum necessary encroachment to meet the utility's requirements and not pose an unreasonable threat to the health, safety, or welfare on or off the subject property. Critical area functions and values must be protected and mitigated. The City requires mitigation for impacts to buffers, which is discussed below. Buffer Impacts As discussed above, complete avoidance of buffer impacts is not possible on this site because the entire area within the project site is either wetland or regulated buffer. Requests for reduction of the buffer width are considered by the City following process III in Chapter 19.65 FWRC. Buffer reduction requests must demonstrate that the proposed project meets the following criteria: (a) It will not adversely affect water quality; (b) It will not adversely affect the existing quality of the wetland or buffer wildlife habitat; (c) It will not adversely affect drainage or stormwater retention capabilities; (d) It will not lead to unstable earth conditions nor create erosion hazards; (e) It will not be materially detrimental to any other property or the city as a whole; and (f) All exposed areas are stabilized with native vegetation, as appropriate. The proposed project would result in permanent buffer impacts of 9,511 square feet (Figure 6). Impacts would result where the new pump station and associated facilities are installed. The functions of the impacted buffer area are currently low because it consists of primarily disturbed habitat dominated by invasive plant species (Himalayan blackberry) and a few red alder trees. Functions related to water quality improvement and wildlife habitat are low in the existing buffer because of the overall simple vegetation structure. Site conditions are shown in photographs of the proposed construction areas in Appendix D. Temporary buffer impacts will occur in an approximate 6,384 square foot construction staging area located immediately south of the new pump station (Figure 6). This area is largely covered by grasses Page 6 ESA March 2019 Pump Station 33B Critical Areas Report and invasive Himalayan blackberry, but does contain some red alder trees along the south end. Temporary impacts will also occur in an approximately 3,006 square foot area along a temporary construction access road west of the proposed pump station site (Figure 6). This area contains buffer and wetland and is covered by mowed grasses and invasive Himalayan blackberry. The portion of the wetland in this area is low functioning and of low value due to the condition as maintained lawn adjacent to the paved driveway. Following construction, the soil will be de -compacted in all temporary impact areas and native trees and shrubs will be planted. A third area of temporary impact is in the buffer to the northeast of the proposed pump station site (Figure 6). Two existing red alder trees are very close to the construction area and will be removed for construction safety reasons. After construction has been completed, two conifers (western red cedar) will be planting in this same area to replace the two red alder removed. 6.0 BUFFER MITIGATION PLAN The proposed project will impact wetland and stream buffer, requiring mitigation. This section describes the mitigation sequencing, proposed conceptual mitigation actions, goals and objectives, and performance standards associated with the proposed project. Mitigation Sequencing The City requires that applicants who proposed to alter wetlands or their buffers must follow a mitigation sequencing process, in the following order of preference (FWRC 19.145.130): (1) Avoiding the impact altogether by not taking a certain action or parts of an action; (2) Minimizing impacts by limiting the degree or magnitude of the action and its implementation, by using appropriate technology or by taking affirmative steps, such as project redesign, relocation, or timing, to avoid or reduce impacts; (3) Rectifying the impact to the critical area by repairing, rehabilitating, or restoring the affected environment to the conditions existing at the time of the initiation of the project; (4) Reducing or eliminating the impact over time by preservation and maintenance operations during the life of the action; (5) Compensating for the impact by replacing, enhancing, or providing substitute resources or environments; and (6) Monitoring the hazard or other required mitigation and taking remedial action when necessary. ESA page 7 March 2019 Pump Station 33B Critical Areas Report 6.1.1 Avoiding Impacts through Construction BMPs Direct impacts to wetlands or streams have been entirely avoided through site selection and design considerations. Wetland and stream impacts will be further avoided and minimized during construction by directing staging areas and construction access points away from wetlands, streams, and their buffers to the greatest extent possible and by using construction best management practices (BMPs). BMPs include erosion and water quality control measures to prevent negative impacts to wetlands and downstream areas. Construction access points will use existing paved surfaces to the greatest extent possible. Standard construction access pads consisting of rock or wood chip mulch will minimize the tracking of mud and debris onto roadways and paved surfaces. Water quality BMPs may include silt fencing, straw bales, plastic covering, and grass seeding. Final exposed cut and fill slopes will be grass seeded. A spill prevention and control plan will also be prepared to prevent any petroleum, chemical, or other deleterious substances from entering aquatic habitats in case of an accident during construction. 6.1.2 Construction Dewatering The project will require lowering of the groundwater table to accommodate construction of pump station components including flow meter vault, force main, gravity sewer piping and manholes and other miscellaneous on -site piping. Shallow groundwater exists year round in this area. The groundwater supporting the wetlands in the vicinity of the project is plentiful and flows through the site generally from north to south. During wetland delineation field work we observed water in soil observations pits within a few inches of the surface and extending to a depth of at least 20 inches. The amount of groundwater observed is on the high end of what is typically seen in slope wetlands in the Puget Sound area. Groundwater likely provides some hydrologic support for the North Fork Hylebos Creek; however, hydrologic support for the creek is primarily from the channel north of South 359th Street. Construction plans include detaining dewatering effluent in holding tanks (Baker tanks) to allow sediments to fall out. Clean water from the holding tanks will be discharged through energy dissipaters in the portion of Wetland A to the southeast of the construction area. The flow rate from the dissipaters will be monitored and adjusted to prevent potential sediment from entering the North Fork Hylebos Creek. Based on geotechnical analyses prepared by Robinson Noble, a maximum dewatering rate of 25 gallons per minute is estimated at the site (Robinson Noble, 2018). Dewatering of the construction site is expected to last for a maximum of 16 weeks during the drier summer months. There is potential for the flow rate in a short portion of North Fork Hylebos Creek to be temporarily reduced by the dewatering activity; however, it is not expected to be measureable due to the large amount of in -stream water entering the site from north of 3591h Street. Groundwater removed for the pump station's construction is expected to flow southeast from the discharge point, spread out into the wetland, and support in -stream flows to the south. There may also be potential for dewatering to temporarily affect the hydrology of portions of Wetland A. However, due to large amounts of Page 8 ESA March 2019 Pump Station 33B Critical Areas Report groundwater supporting the wetland, it is anticipated that sufficient water will still remain to support wetland vegetation. After dewatering is discontinued, the natural groundwater levels are expected to reestablish in the wetlands and in North Fork Hylebos Creek. Buffer Mitigation Strategy The proposed buffer mitigation strategy for this project is to restore and enhance a total of 11,447 square feet of regulated wetland and stream buffer to compensate for 9,511 square feet of buffer impacts. The buffer restoration (7,805 square feet) will be accomplished by removing the paved driveway, existing pump station, and hardscape associated with the existing pump station (Figure 6). After the pavement and pump station facilities are removed, soil will be amended (e.g., de -compaction, application of organic material) and native tree and shrub species will be installed. The buffer restoration area does not fully replace the area of buffer impact at a 1:1 ratio, therefore, an additional area is designated for buffer enhancement (See Figure 6). The buffer enhancement area (3,461 square feet) has a forested cover consisting of primarily red alder and salmonberry. The strategy for this area (greater than 2:1 ratio) includes enhancing by underplanting with native conifers to improve wildlife habitat and structural diversity in the plant community. The existing condition of most of the buffer restoration area is pavement and therefore does not provide buffer functions. Precipitation falling on the pavement is not retained since there is little or no vegetation. Wildlife habitat is non-existent in the proposed buffer restoration area because of the lack of food sources and nesting habitat. The addition of natural soil surface and native vegetation to replace the existing pavement would improve the functional attributes of the wetland buffer and provide additional protection to wetland functions and values. Natural surface will allow for the infiltration of precipitation that can contribute to groundwater recharge and stormwater retention. Re-establishing native vegetation will improve the erosion protection and water quality improvement functions of the buffer area by slowing flows and trapping sediments. Native vegetation will also add wildlife habitat to the buffer area that currently does not provide usable habitat. The native trees and shrubs chosen for the planting plan (Table 2) will provide nesting materials, nesting locations, and food sources for native birds and small mammals. Native trees and shrubs planted in the buffer area will also add a more complex vegetation structure and increase species diversity. Conifers planted in the buffer enhancement areas will add structural complexity, species richness, and wildlife nesting and feeding opportunities. Proposed plant species and associated spacing are detailed in Table 2. Table 2. Buffer Mitigation Plant Species Scientific Name Common Name Size Spacing Picea sitchensis Sitka spruce 1 gal I 12' OC* Psuedotsuga menziesii Douglas fir 1 gal 12' OC* Pinus contorts I Lodgepole pine 1 gal 12' OC ESA March 2019 page 9 Pump station 33B Critical Areas Report Thuja plicata Western red cedar Red -osier dogwood 1 gal 1 gal 12' OC 6' OC Corpus sericea Rubus spectabilis I Salmonberry J 1 gal I 6' OC Rubus parviflorus I Thimbleberry 1 1 gal I 6' OC Lonicera involucrata I Black twinberry 1 1 gal I 6' OC Physocarpus capitatus I Pacific ninebark 1 1 gal ' 6' OC *OC=on-center The buffer mitigation plan as described in this report will compensate for proposed buffer impacts and result in improved buffer conditions. The project and mitigation plan meet the requirements in Chapter 19.65 FWRC, based on the following criteria: (a) It will not adversely affect water quality; Construction BMPs and stormwater control design will limit the risk of water quality impacts from the new pump facility. Construction will be undertaken during the dry summer months to reduce the likelihood of adverse effects to water quality. Dense planting of native trees and shrubs will improve the water quality improvement functions of the buffer. (b) It will not adversely affect the existing quality of the wetland or buffer wildlife habitat; The portion of the buffer planned for the new pump facility is primarily covered by invasive plants (Himalayan blackberry) and provides only limited wildlife habitat functions. The loss of functions from this buffer area will be more than off -set by restoration of buffer where the existing paved access road and existing pump station are located. The result of the buffer mitigation is expected to be an overall increase in buffer functions by increasing the quality of the habitat structure for wildlife. (c) It will not adversely affect drainage or stormwater retention capabilities; Drainage and stormwater retention capabilities of the buffer area will not be adversely affected. Replacing the existing paved area with native woody plant species is expected to improve the overall drainage and stormwater retention functions in the buffer. (d) It will not lead to unstable earth conditions nor create erosion hazards; Page 10 ESA March 2019 Pump Station 33B Critical Areas Report The project will not lead to unstable earth conditions nor create erosion hazards. The design includes a retaining wall along the south, east, and west sides of the project area to create a level pad for the pump facility and stabilize the ground. Construction BMPs and revegetation will ensure no erosion hazard is created. (e) It will not be materially detrimental to any other property or the city as a whole; and The pump facility will improve the sewage conveyance in this portion of the city and the buffer mitigation plan will improve wildlife habitat functions within the watershed. (f) All exposed areas are stabilized with native vegetation, as appropriate. As described in the buffer mitigation plan above, all buffer areas outside of the pump facility will be planted with native trees and shrubs. 6.1.3 Mitigation Goals, Objectives, and Performance Standards The overall goal of the mitigation project is to restore and enhance the wetland buffer to improve buffer functions following construction. Mitigation objectives and performance standards are as follows: Objective 1: Improve buffer functions in restored buffer areas by removing pavement and existing pump station facilities, amending with topsoil, and replanting the restored areas and enhanced buffer areas with native tree and shrub species. Performance Standard 1a:100 percent survival of installed native woody species 1 year after installation. Survival will be determined using a complete plant count. Performance Standard 1b: Year 2—At least 20 percent coverage of native woody species in the buffer mitigation area (installed and desirable volunteers). Performance Standard 1c: Year 3—At least 30 percent coverage by native woody plant species in the buffer mitigation area (installed and desirable volunteers). Performance Standard 1d: Year S—At least 70 percent coverage by native woody plant species in the buffer mitigation area (installed and desirable volunteers). Objective 2: Remove non-native, invasive vegetation in wetland buffer mitigation area. Performance Standard 2a: Himalayan blackberry, English ivy, reed canarygrass, and other noxious weeds will not exceed 20 percent coverage in planting areas throughout the monitoring period. Invasive knotweed (Polygonum spp.) will be eradicated from all mitigation areas. 6.1.4 Mitigation Construction Plan Figure 6 depicts the location of the proposed mitigation area. Detailed plant lists and specifications are shown on mitigation plan sheets (Appendix E). The sequence of steps during construction includes: ESA March 2019 page 11 Pump Station 33B Critical Areas Report 1. Remove driveway pavement and base material, pump station and associated facilities, and pavement associated with the pump station. 2. Clearly mark the boundaries of the buffer restoration area. 3. De -compact soil and remove gravel and other incompatible surfacing materials from planting areas. 4. Apply soil amendments as needed. 5. Install plant materials in accordance with approved plans. 6. Seed disturbed soil areas with an appropriate herbaceous seed mix. 7. Apply mulch rings around installed woody plantings. Monitoring The City requires five years of monitoring for mitigation projects (FWRC 19.145.140(8)). The main objective for mitigation monitoring is to document the level of success in meeting the project's performance standards. The following describes the preliminary monitoring approach to be refined and updated during development of the final mitigation plan. 6.1.5 Schedule An initial stem count of the installed shrubs and trees will be conducted following construction (an as - built count). Monitoring of mitigation areas will continue annually for five years after installation. A qualified biologist or landscape designer will conduct the monitoring. The as -built plan will be used as the basis for monitoring of plant survival. Monitoring will begin with Year 1, the first full growing season after construction is complete and the plants have been installed and continue for Years 2, 3, and 5. 6.1.6 Data Collection Shrub and tree cover will be evaluated quantitatively and qualitatively each of the four monitoring years. Data collection will occur during the late summer (i.e., September -October). The following information will be recorded during each of the monitoring site visits: • Survival rates of installed vegetation during plant warranty period. • General plant health assessment and plant aerial coverage from established sampling points and transects (e.g., line -intercept). • Documentation of the presence of undesirable plants (weedy and/or non-native species) with estimated percent cover. • Photo documentation of site conditions from established photo points. • Impacts to the wetland buffer from human use (e.g., dumping of debris). ■ Signs of wildlife use. Page 12 ESA March 2019 Pump Station 33B Critical Areas Report Results of the annual monitoring events will be discussed in a yearly monitoring report prepared for the City. 6.1.7 Reporting Monitoring reports will be prepared by a qualified biologist or landscape designer for review and approval by the City. The reports will compare the performance standards described in the mitigation plan to the field observations, and will recommend species replacements or other maintenance activities, if necessary (see Maintenance section below). Reports will present data collected during the monitoring site visit and document successes in meeting specific performance standards. Photographs will be included to illustrate and document site conditions. Monitoring reports will be submitted before December 31st each monitoring year. Maintenance Maintenance of the mitigation area will begin after completion of the project and continue, as needed, for five years. After the initial planting acceptance by the project biologist, the landscaping contractor will be responsible for plant survival for a period of 1 year. The District will provide maintenance, as necessary. Maintenance could include, but may not be limited to the following: a Irrigate during dry periods (minimum June — September). • Remove non-native or invasive plant species. • Add soil amendments and/or mulch. o Install fencing around woody plants to prevent animal damage. o Construct fencing to prevent vandalism or damage caused by humans. • Install supplemental plantings as needed. Contingency If any portion of the mitigation is not successful, a contingency plan will be implemented. Such plans are prepared on a case -by -case basis to remedy any aspects of the mitigation that do not meet the performance standards. The plan, if required, would be developed in cooperation with the City. 7.0 LIMITATIONS Within the limitations of schedule, budget, scope -of -work, and seasonal constraints, we warrant that this study was conducted in accordance with generally accepted environmental science practices, including the technical guidelines and criteria in effect at the time this study was performed, as outlined in the Methods section. The results and conclusions of this report represent the authors' best professional judgment, based upon information provided by the project proponent in addition to that obtained during the course of this study. No other warranty, expressed or implied, is made. ESA page 13 March 2019 Pump Station 33B Critical Areas Report 8.0 REFERENCES Brinson, M. 1993. A Hydrogeomorphic Classification for Wetlands. U.S. Army Corps of Engineers, Wetlands Research Program. Corps (U.S. Army Corps of Engineers). 2005. Regulatory Guidance Letter No. 05-05: Ordinary High Water Mark Identification. December 7, 2005. Corps (U.S. Army Corps of Engineers). 2010. Regional Supplement to the Corps of Engineers Wetland Delineation Manual: Western Mountains, Valleys, and Coast Region (Version 2.0), ed. J.S. Wakeley, R. W. Lichvar, and C. V. Noble. ERDC/EL TR-10-3. Vicksburg, MS: U.S. Army Engineer Research and Development Center. Corps (U.S. Army Corps of Engineers). 2016. National Wetland Plant List, Version 3.3. Accessed at: http:/(wetland-plants.usace.army.mil. U. S. Army Corps of Engineers, Engineer Research and Development Center. Cowardin, L.M., V. Carter, F.C. Golet, and E.T. LaRoe. 1979. Classification of Wetlands and Deepwater Habitats of the United States. FWS/OBS-79/31. U.S. Fish and Wildlife Service. Ecology (Washington State Department of Ecology), U.S. Army Corps of Engineers Seattle District, and U.S. Environmental Protection Agency Region 10. 2006a. Wetland Mitigation in Washington State, Part 1: Agency Policies and Guidance. Version 1, March 2006. Publication # 06-06-011a. Ecology (Washington State Department of Ecology), U.S. Army Corps of Engineers Seattle District, and U.S. Environmental Protection Agency Region 10. 2006b. Wetland Mitigation in Washington State, Part 2: Developing Mitigation Plans. Version 1, March 2006. Publication # 06-06-011b. EPA (Environmental Protection Agency) and Corps (US Army Corps of Engineers). June 5, 2007. Clean Water Act Jurisdiction Following the US Supreme Court's Decision in Rapanos v.United States & Carabell v. United States. Federal Register. 1986. 33 CFR Parts 320 through 330: Regulatory Programs of the Corps of Engineers; Final Rule. Vol. 51, No.219, pp. 41206-41260. U.S. Government Printing Office, Washington, DC. Hruby, T. 2014. Washington State Wetland Rating System for Western Washington — Revised. October 2014. Ecology publication number 14-06-029. Olympia, WA. Munsell Color. 2000. Munsell Soil Color Charts. GretagMacbeth, New Windsor, New York. NRCS (Natural Resources Conservation Service). 1995. Hydric Soils List for Washington. Revised December 15, 1995. NRCS. 2013. Custom Soil Resource Reportfor King County Area, Washington - Lakehaven Utility District. Accessed February 14, 2013. Page 14 ESA March 2019 Pump Station 33B Critical Areas Report Robinson Noble. Revised Geotechnical Engineering Report- Lakehaven Pump Station 33B. September 24, 2018. Vepraskas, M.J. 1999. Redoximorphic Features for Identifying Aquic Conditions. Technical Bulletin 301. North Carolina Agricultural Research Service, North Carolina State University, Raleigh, North Carolina. ESA March 2019 page 15 Pump Station 33B Critical Areas Report FIGURES ESA March 2019 page 17 Pump Station 33B Critical Areas Report APPENDIX A: METHODS ESA Appendix A March 2019 Pump Station 33B Critical Areas Report ESA reviewed existing information and conducted an on -site investigation to identify and assess streams and wetlands. REVIEW OF EXISTING INFORMATION ESA reviewed existing literature, maps, and other materials to identify wetlands or site characteristics indicative of wetlands in the study area. These sources can only indicate the likelihood of the presence of wetlands; actual wetland determinations must be based upon data obtained from field investigations. Key sources of information included the following: ■ U.S. Geological Survey (USGS), 1961— Poverty Bay, WA. Topographic map; ■ National Wetland Inventory (NWI) Wetland Mapper (U.S. Fish and Wildlife Service [USFWS], 2016); ■ WDFW Priority Habitats and Species (PHS) on the Web ■ WDFW Salmonscape ■ City of Federal Way critical areas mapping (May 2016). WETLAND DEFINITION AND DELINEATION Wetlands are formally defined by the U.S. Army Corps of Engineers (Corps) (Federal Register 1982), the Environmental Protection Agency (EPA) (Federal Register 1988), the Washington Shoreline Management Act (SMA) of 1971 and the Washington State Growth Management Act (GMA) as follows: ... those areas that are inundated or saturated by surface or groundwater at a frequency and duration sufficient to support, and that under normal circumstances do support, a prevalence of vegetation typically adapted for life in saturated soil conditions. Wetlands generally include swamps, marshes, bogs, and similar areas (Federal Register, 1982, 1986). In addition, the SMA and the GMA definitions add: Wetlands do not include those artificial wetlands intentionally created from non - wetland site, including, but not limited to, irrigation and drainage ditches, grass -lined swales, canals, detention facilities, wastewater treatment facilities, farm ponds, and landscape amenities, or those wetlands created after July 1, 1990 that were unintentionally created as a result of the construction of a road, street, or highway. Wetlands may include those artificially created wetlands intentionally created from non -wetland areas to mitigate the conversion of wetlands. Methods defined in the Western Mountains, Valleys, and Coast Regional Supplement (Corps, 2010) to the U.S. Army Corps of Engineers 1987 Wetlands Delineation Manual (Manual) were used to determine the presence and extent of wetlands in the study area. These methods are also consistent with state ESA Appendix A-1 March 2019 Pump Station 33B Critical Areas Report requirements in WAC 173-22-035. The methodology outlined in the manuals is based on three essential characteristics of wetlands: (1) hydrophytic vegetation, (2) hydric soils, and (3) wetland hydrology. Field indicators of these three characteristics must all be present in order to determine that an area is a wetland (unless problem areas or atypical situations are encountered). These characteristics are described below. The "routine on -site determination method" was used to determine wetland boundaries that had not been previously delineated. Formal data plots were established where information regarding each of the three wetland parameters (vegetation, soils, and hydrology) was recorded. This information was used to distinguish wetlands from non -wetlands. If wetlands were determined to be present within the study area, wetland boundaries were delineated with sequentially numbered colored pin flags or flagging. Data plot locations were also marked with colored flagging. Data sheets for each of the formal data plots evaluated for this project are provided in Appendix C. Vegetation Plants must be specially adapted for life under saturated or anaerobic conditions to grow in wetlands. The U.S. Fish and Wildlife Service (USFWS) has determined the estimated probability of each plant species' occurrence in wetlands and has accordingly assigned a "wetland indicator status" (WIS) to each species. Plants are categorized as obligate (OBL), facultative wetland (FACW), facultative (FAC), facultative upland (FACU), and upland (UPL). Definitions for each indicator status are listed below. Species with an indicator status of OBL, FACW, or FAC are considered adapted for life in saturated or anaerobic soil conditions. Such species are referred to as "hydrophytic" vegetation. Key to Wetland Indicator Status codes: OBL Obligate: species that always occur in standing water or in saturated soils. FACW Facultative wetland: species that nearly always occur in areas of prolonged flooding or require standing water or saturated soils but may, on rare occasions, occur in nonwetlands. FAC Facultative: species that occur in a variety of habitats, including wetland and mesic to xeric non -wetland habitats but commonly occur in standing water or saturated soils. FACU Facultative upland: species that typically occur in xeric or mesic non -wetland habitats but may frequently occur in standing water or saturated soils. UPL Upland: species that rarely occur in water or saturated soils. Areas of relatively homogeneous vegetative composition can be characterized by "dominant" species. The indicator status of the dominant species within each vegetative stratum is used to determine if the plant community may be characterized as hydrophytic. The vegetation of an area is considered to be hydrophytic if more than 50% of the dominant species have an indicator status of OBL, FACW, or FAC. The Regional Supplement provides additional tests for evaluating the presence of hydrophytic Appendix A-2 ESA March 2019 Pump Station 33B Critical Areas Report vegetation communities including the prevalence index, morphological adaptations, and wetland nonvascular plants. The Supplement also addresses difficult situations where hydrophytic vegetation indicators are not present but hydric soils and wetland hydrology are observed. soils Hydric soils are indicative of wetlands. Hydric soils are defined as soils that are saturated, flooded, or ponded long enough during the growing season to develop anaerobic conditions in the upper part of the soil profile (Federal Register, 1994). The Natural Resources Conservation Service (NRCS), in cooperation with the National Technical Committee for Hydric Soils, has compiled lists of hydric soils (NRCS, 1995). These lists identify soil series mapped by the NRCS that meet hydric soil criteria. It is common, however, for a map unit of non -wetland (non-hydric) soil to have inclusions of hydric soil, and vice versa. Therefore, field examination of soil conditions is important to determine if hydric soil conditions exist. The NRCS has developed a guide for identifying field indicators of hydric soils (NRCS, 2010). This list of hydric soil indicators is considered to be dynamic; revisions are anticipated to occur on a regular basis as a result of ongoing studies of hydric soils. In general, anaerobic conditions create certain characteristics in hydric soils, collectively known as "redoximorphic features," that can be observed in the field (Vepraskas,1999). Redoximorphic features include high organic content, accumulation of sulfidic material (rotten egg odor), greenish- or bluish -gray color (gley formation), spots or blotches of different color interspersed with the dominant or matrix color (mottling), and dark soil colors (low soil chroma) (NRCS, 2010; Vepraskas, 1999). Soil colors are described both by common color name (for example, "dark brown") and by a numerical description of their hue, value, and chroma (for example, 10YR 2/2) as identified on a Munsell soil color chart (Munsell Color, 2000). Soil color is determined from a moist soil sample. The Regional Supplement provides methods for difficult situations where hydric soil indicators are not observed, but indicators of hydrophytic vegetation and wetland hydrology are present. Hydrology Water must be present for wetlands to exist; however, it need not be present throughout the entire year. Wetland hydrology is considered to be present when there is permanent or periodic inundation or soil saturation at or near the soil surface for more than 12.5 percent of the growing season (typically 2 weeks in lowland Pacific Northwest areas). Areas that are inundated or saturated for between 5 percent and 12.5 percent of the growing season in most years may or may not be wetlands. Indicators of wetland hydrology include observation of ponding or soil saturation, water marks, drift lines, drainage patterns, sediment deposits, oxidized rhizospheres, water -stained leaves, and local soil survey data. Where positive indicators of wetland hydrology are observed, it is assumed that wetland hydrology occurs for a sufficient period of the growing season to meet the wetland criteria. The Regional Supplement provides methods for evaluating situations in wetlands that periodically lack indicators of wetland hydrology but where hydric soils and hydrophytic vegetation are present. ESA Appendix A-3 March 2019 Pump Station 33B Critical Areas Report CLASSIFYING WETLANDS Two classification systems are commonly used to describe wetlands. The hydrogeomorphic (HGM) system describes wetlands in terms of their position in the landscape and the movement of water in the wetland (Brinson, 1993). The USFWS classification system (Cowardin et al., 1979) describes wetlands in terms of their vegetation communities; these include, for example, emergent, scrub -shrub, and forested community types. ASSESSING WETLAND FUNCTION The City of Federal Way specifies the use of Ecology's Washington State Wetland Rating System for Western Washington —Revised (Hruby, 2014) for rating wetlands. This rating system was developed by Ecology to differentiate wetlands based on their sensitivity to disturbance, their significance, their rarity, our ability to replace them, and the beneficial functions they provide to society. Although this system is designed to rate wetlands, it is based on whether a particular wetland performs a particular function and the relative level to which the function is performed. An assessment of wetland functions is inherent in the rating system. Appendix C provides additional information about the rating system wetland categories and completed rating forms for the Project. The rating system was designed to differentiate between wetlands based on their sensitivity to disturbance, their significance, their rarity, our ability to replace them, and the functions they provide. In addition to rating a particular wetland, the rating system also provides a qualitative assessment of several wetland functions, including water quality improvement, flood flow alteration, and wildlife habitat. Wetlands are given points based on a series of questions regarding water quality, hydrologic, and habitat functions, and then scored into four categories: Category I (highest score) through Category IV (lowest score). Because detailed scientific knowledge of wetland functions is limited, evaluations of the functions of individual wetlands are somewhat qualitative and dependent upon professional judgment. IDENTIFYING STREAMS ESA marked the locations of the ordinary high water (OHWM) of streams in the study area with blue and white striped flagging. For purposes of determining its lateral jurisdiction under the Clean Water Act (33 CFR 328.3(e)), the U.S. Army Corps of Engineers defines the OHWM as: "that line on the shore established by the fluctuations of water and indicated by physical characteristics such as a clear, natural line impressed on the bank, shelving, changes in the character of soil, destruction of terrestrial vegetation, the presence of litter and debris, or other appropriate means that consider the characteristics of the surrounding areas" (Corps, 2005). Other physical characteristics that should be used to determine the OHWM include wracking; vegetation matted down, bent, or absent; sediment sorting; leaf litter disturbed or washed away; scour; deposition; multiple observed flow events; bed and banks; water staining; and a change in plant community (Corps, 2005). Appendix A-4 ESA March 2019 Pump Station 33B Critical Areas Report APPENDIX B: COMMON AND SCIENTIFIC NAMES OF PLANTS AND THEIR WETLAND INDICATOR STATUS ESA Appendix 8 March 2019 Pump Station 33B Critical Areas Report PLANT SPECIES LIST FOR THE LAKEHAVEN WATER AND SEWER DISTRICT PUMP STATION 33B PROJECT IDENTIFIED DURING FEBRUARY AND DECEMBER 2015 COMMON NAME SCIENTIFIC NAME WETLAND INDICATOR STATUS* Trees Black cottonwood Populus balsamifera FAC Big -leaf maple Acermacropyllum FACU Douglas fir Pseudotsuga menziesii FACU red alder Alnus rubra FAC Western hemlock Tsuga heterophylla FACU Western red cedar Thujo plicata FAC Shrubs common snowberry Symphoricarpos albus FACU Hardhack (Douglas' spiraea) Spiraea douglasii FACW Himalayan blackberry Rubus bifrons (Rubus armenicus) FACU Indian plum Oemleria cerasiformis FACU Nootka rose Rosa nutkano FAC Red elderberry Sambucus racemosa FACU Red -osier dogwood Cornus sericea (Cornus alba) FACW Salmonberry Rubus spectabilis FAC Willow Salix sp. FACW Herbs American speedwell Veronica americana OBL Bentgrass Agrostis sp. FAC Bittercress Cardamine sp. FAC common velvetgrass Holcus lanatus FAC creeping buttercup Ranunculus repens FAC false -lily -of -the -valley Maianthemum dilatatum FAC giant horsetail Equisetum telmateia FACW Lady fern Athyrium filix femina FAC Mannagrass Glyceria sp. OBL reed canarygrass Phalaris arundinacea FACW Skunk cabbage Lysichiton americanum OBL Small -fruited bulrush Scirpus microcarpus OBL stinging nettle Urtica dioica FAC Timothy grass Phleum pratense FAC Water parsley Oenanthe sarmentosa OBL Youth -on -age Tolmiea menziesii FAC ESA Appendix 8-1 March 2019 Pump Station 33B Critical Areas Report APPENDIX C: WETLAND DETERMINATION DATA SHEETS AND RATING FORMS ESA March 2019 Appendix C 1 A- v a µ Pump Station 33B Critical Areas Report ESA March 2019 APPENDIX D: SITE PHOTOGRAPHS Appendix D Pump Station 33B Critical Areas Report Photo 1: Google Earth street view image from October 2016. Looking southeast at proposed location for pump station 33B. Paved driveway that provides access to existing pump station is on right of photo. Wetland D is located to the right of the driveway. Wetland E is located behind the trees to the left. o, l Earth math 3a ESA March 2019 Appendix D-1 Pump Station 33B Critical Areas Report Photo 3: Interior of Wetland D. Photo taken February 2015. ESA March 2019 Appendix D-3