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04-101053
Ke Peterson - RE: Northshore Plaza Retail Sewer connection From: "Brian Asbury" <BAsbury@lakehaven.org> To: "Kevin Peterson" <Kevin.Peterson@cityoffederalway.com>, <jtaflin@AHBL.com> Date: 7/15/2004 2:48:48 PM Subject: RE: Northshore Plaza Retail Sewer connection Kevin and Janelle, Sorry for all the confusion, but getting to the point - There is a newly constructed, 6" side sewer stub on the east side of Hoyt Road and that is the location that the Northshore Plaza Retail needs to connect to. If the Northshore Plaza developer desires to avoid any Hoyt Road construction and/or overlay, they'll need to contact the developer of the property on the east side of Hoyt Road to have the 6" SS stub abandoned at the main. If the other developer is agreeable to stub abandonment, then the Northshore Plaza developer can proceed with a sewer main extension adjacent to and west of Hoyt Road (outside of ROW). This extension can terminate at the north property line, and does not need to extend south thru the property as there is another 6" SS stub constructed by the other developer on the east side of Hoyt Road. If the other developer is not agreeable to stub abandonment, then we will require Northshore Plaza to make its sewer connection at that point on the east side of Hoyt Road. I suspect it would be difficult to perform that connection without affecting Hoyt Road asphalt, but I'll defer to the developer's consultants on that issue. Brian Asbury Engineering Technician III Lakehaven Utility District http://www.lakehaven.org FAX 253-529-4081 NOTE: Lakehaven does not verify, nor is responsible for, the accuracy of any drawings provided. -----Original Message ----- From: Kevin Peterson [mailto: Kevin. Peterson@cityoffederalway.com] Sent: Thursday, July 15, 2004 1:52 PM To: jtaflin@AHBL.com Cc: Brian Asbury Subject: Northshore Plaza Retail Sewer connection Janelle, As you know, per your previous design, the City will not allow parallel open -cutting of Hoyt Road for the Sanitary Sewer Extension, unless the applicant is willing to provide a full -width asphalt overlay. And, as discussed earlier today, the City would prefer that you connect to the existing Chevron sewer line, to keep out of the paved area of Hoyt Road. Apparently, that option was discussed with, and denied by, Mary Young (formerly) with Lakehaven Utility District . I've attached a marked -up sketch of what the City would prefer to see, which (I hope) is similar to what you had originally approached Mary Young with (and if not, I apologize for my presumption, and if you could, please clarify the differences). Brian, Kevin Peterson - RE. Northshore Plaza Petail Sewer connection - Page 2 - N ... - _ .. .. .-.. .._�F .. .. ... ..............: .. '1 As you know, the City is pretty stringent on parallel open -cuts of streets, and requiring overlays when it is allowed. And we would prefer to not cut across the street if it looks like other options are available. Please see the attached sketch, which shows the previous proposed sewer extension alignment, the current proposal (cut directly east across Hoyt), and the City's preferred alternative, which stays out of the Hoyt Rd pavement, but is within the driveway area that will be re -constructed as part of this project. I don't presume to be at all knowledgeable of Lakehaven's requirements for connecting to sanitary sewer, or the reason the city preferred option wouldn't or couldn't be allowed. So any feedback would be appreciated. Thanks for your help in this matter. Kevin Kevin Peterson City of Federal Way Engineering Plans Reviewer Ph. (253) 661-4037 Fax (253) 661-4129 kevin.peterson@cityoffederalway.com CC: "John Jensen" <JJensen@lakehaven.org> t `1 14M=393.6 ; 1 6 ` �`. ° �,1 ; 8° PVC- E W `' n I.E.CL CHA EL�3.92'SSMH LADDER SE I.0 B• PVC S 383:34' 8" PVC W 383-21' r f * I V.E. 8" PVC N 383.11' 6 4 ii ; LADDER EAST SS SS SS SS SS I. SS SS .. 7 6 1 3 ID" r-,6 V" EL 386.57' M/W/m 6 `Z • �'. � f f� r.j r Z�D j � 55MH RIM=394.45 cn 383.53 SSMH TYPE 1-48 f i, f.l{. 8" N —• �f. �f/ f , �f/�� � !/� _—...__.._ — _ I PVC ;' / /rf • , !!• t, r/ ftll�_392.50t_., �,�..$ PVGE 383.50' (MATCH GRADE) ti 4 y y 3 l LADDER WEST IE 387.66 N85'40 ] W :.: �• ;;i f f /; s, i' 4 - u t� # Ri I f II voI li�'C C- 1 �6 i {� I SSMH '1-48° r ry c 4 RIM 343.00 IE 385;001(8" NW) nn A A ° s IE 385H O (6, W,S) DS rJ ,7 �, • 9 SSW386.86 ¢ IE 386.20t 4 5CQ IE IE 387.84 4 y9 SSCO } 1 ' a _ :�7,rl r /fi//r ;1 EW BUILDING 4,100 SF - � � • d i -- °393 ►: ;I 'x ' - •85.40.'i 5�— 164.69'f .� I 2 7 _ ` 9 RIGHT-OF-WAY DEDICATION o SSCO 4 iff I uL-/IZ/1004 15:17 FAX 253 471 13232 CUII'YEIRCIAL EXMJ[ [a 022 SIGHT DIST.Ui_E:^kND YIEW EASEMENT R/W 371 1270 k(2) e THIS INDENTURE ➢iITNESSETH: that -L 4 3r�1r1� F� :n•• :c:. J +;�^ a; Eli "Grricr a e proper y erezna er escr „e . or an n srdere can ono a sus of $1..03 and other good and valuable consideration in hand paid by the County of King, Stati! of Nlr,shington, the--cceipt of which is hereby acscnowledged, have granted and do hereby ;vast unto King County the perpetual right and privilege to mainUin the following descrfl+e^ propel-W adjacent to streat intersections and designated as tight distance easemLisi, areas, and the County is granted the right under such easement to Construct such slopies and cuts and to remove, at any time, arty vegetation, materials. or obstructions ov imy 11atwre as rwy be necessary to provide for unobstructed Yiew Over an4 across the herein designated sight distance easement areas at and above an elevation which is higher that: 2 (two) feet above the pavement surface of the centerlines of the adjacent improved st;rFe ~s. That portion of Government Lot 2, Section 2:1, Township 21 llor•tn, range 3 East, y W.M.; County of King, State of Washin11t.11n, being more particularly described as follows: Beginning at a Ibint of intersection a'➢ time south line of the north 100.00 feet s as measured along the east line of Tril!;i: 76 of Hannon's half acres, as recor::ad CM in Yo14@e 16 Of plats, page Z8, record! of I(Ing CoutlLyit'k!shington, with the: 41' - ' westerly margin of Hoyt Road Svuthkesi:, a 60.00 foot rght-of-way; thence f^ westerly 8.00 fE+et along said south 1•la.e of 'the north 100.00 feet as Tract 75; thence nort2n est:erly 102.00 feet n!ore or ➢esa to tho south line of Tract 74; thence easterly MOO feet more or 'de!;!i to :sitid westerly margin of Hoyt Road �- C d] Southwest; thence southeasterly along -aftoiesterly margin 102.00 feet more or less to the Point of Beginning. m Together with Or subject to the following rights, obligations, covenants, and conditions as follows: a� (a) It is understood and agreed that ne7iiher the owner, the owner's successors or assigns, nor any occupant of private property •above described sh311 construct or place any structure, property, materials, nr ohs -ruction of any nature on any designated sight distance area; provided, hover, that nnJorg herein shall prohibit the placenw_nt or G growing of plants clnd vegetation up to a Height of 2 (two, feet. (bi It is covenanted and agreed that t:hn owners or occupants of property shall be obligated at their expense to remove any uuavthorized obstruction to sight distance which ray be placed or constructed on a designwU!d sight distance area, and to keep all plants and vegetation on the designated sight dln-.anc+e area trimmed below the elevation of the above described plane, and upon the failtll'r! of any such owner or occupant so to do, the County shall have the right at any time, w1thout notice, to enter upon such easement area and remove any and all plants and vegeta•;inn and any and all other obstructions and encroachments exis'A ng on such area in v•Ir:+lation of the terms and conditions of this Casement. and the owner of the property on which such obstructions are removed by the e County shall be I able for any costs the (uunty may incur in the removal of such sight obstructions. (c) The agreement!-- and covenants here -In contained shall apply to and insure to the C benefit of and be binding upon the Count_i and the owner ai!d their respective successors and assigns as if so specifically expres,ed throughout and shall be covenants running with the land. L► IN WITNESS WHEREOF, havf hereunto subscribed +eiff`r names a' �e cis n an, s v STATE OF WASHI➢IGT011) 1 ss. COUNTY OF PIERCE ) �] OSiZ2 40362 e �► REC-D F" .00 �**. as On this day of u�. 19 ,!fir• . *Ve��e, the un�c'� - siifyned, sop c in br I—;i;[� of_ia-Tingto"n`,. duly commissioned and sworn, per 1: �'_ s-�• �y�{, c' k�Y n i�i L to r1 v e s dcserili� Zgo-ng an o xecvte e-o ns r. , an that they signed !cid sealed the said instrument as their free and *+ v or the uses ami purposes therein vireiiti oned. d fficial Seel hrm::la3 affikeu the dak and year in this certificate ... i L-1 tie '�iauc�l: tsryd��="it�ea or ate o For RA�crd at T I shington, p4sidir.g at - -+ (7t3f3o � King Countyk1?>f1ion.:-(➢ieis,�on--- 7 7 1 U11L ■q�� RESUBMITTED Q M A - 5 E A T i L E MAY 2 7 ?00�, Technical Information Report PREPARED FOR: The Northshore Plaza Federal Way, Washington PROJECT: The Northshore Plaza Retail Center 203517.10 PREPARED FOR: Helix Architecture 6021 12t" Street East, Suite 201 Fife, WA 98424 PREPARED BY: Jenelle Coye Project Engineer REVIEWED BY: J. Matthew Weber, P.E. Senior Project Manager Sean Comfort, P.E., Principal March 2004 Revised May 2004 Civil Engineers • Structural Engineers • Landscape Architects • Community Planners • Land Surveyors • Neighbors I EXPIRES: 2 / 6 / Fl.'% i I hereby state that this Technical Information Report for the Northshore Plaza Retail Building has been prepared by me or under my supervision and meets the standard of care and expertise that is usual and customary in this community for professional engineers. I understand that the City of Federal Way does not and will not assume liability for the sufficiency, suitability, or performances of drainage facilities prepared by me. Technical Information Report PREPARED FOR: The Northshore Plaza Federal Way, Washington PROJECT The Northshore Plaza Retail Center 203517.10 PREPARED FOR: Helix Architecture 6021 12th Street East, Suite 201 Fife, WA 98424 PREPARED BY. Jenelle Coye Project Engineer REVIEWED BY: J. Matthew Weber, P.E. Senior Project Manager Sean Comfort, P.E., Principal March 2004 Revised May 2004 TABLE OF CONTENTS SECTION PAGE 1. Project Overview.........................................................................................................................................3 1.1 Purpose and Scope.................................................................................................................................3 1.2 Existing Conditions................................................................................................................................3 1.3 Post -Development Conditions.............................................................................................................4 2. Conditions and Rcquirernents Summary.................................................................................................4 2.1 Core Requirements.................................................................................................................................4 2.1.1 C.R. #1 - Discharge at the Natural Location............................................................................4 2.1.2 C.R. #2 — Off -site Analysis..........................................................................................................4 2.1.3 C.R. #3 - Flow Control................................................................................................................5 2.1.4 C.R. #4 - Conveyance System.....................................................................................................5 2.1.5 C.R. #5 - Erosion and Sediment Control. 2.1.6 C.R. #6 - Maintenance and Operations.....................................................................................5 2.1.7 C.R. #7 - Financial Guarantees and Liability............................................................................6 2.1.8 C.R. #8 - Water Quality ................................................................................................................6 3. Off -Site Analysis.......................................................................................................................................... 6 3.1 Downstream Analysis............................................................................................................................ 6 3.1.1 Task 1— Study Area Definition and Maps................................................................................6 3.1.2 Task 2 — Resource Review........................................................................................................... 6 3.1.3 Task 3 — Field Inspection.............................................................................................................6 3.2 Upstream Analysis.................................................................................................................................. 8 4. Flow Control and Water Quality Facility Analysis and Design...........................................................7 4.1 Flow Control.......................................................................................... 4.1.1 Existing Site Hydrology.................................................................................................................8 4.1.2 Developed Site Hydrology...........................................................................................................8 4.1.3 Flow Control System....................................................................................................................8 4.2 Water Quality ........................................................................................................................................... 8 5. Conveyance System Analysis and Design...............................................................................................9 6. Special Reports And Studies......................................................................................................................9 7. ESC Analysis and Des' 9 8. Operations and Maintenance Plan ..........................................................................................................10 9. Conclusion..................................................................................................................................................10 Appendices Appendix A* Appendix B Appendix C Exhibits Figure 1 - TIR Worksheet Figure 2 — Site Location Figure 3 - Existing Conditions Map Figure 4 - Developed Conditions Map Figure 5 - SW 340'h Regional Detention Facility Basin Map Downstream Analysis Figure 1- Level 1 Downstream Drainage Analysis by Barghausen Consulting Engineers, July 1996 Hydrologic Analysis Exhibit 1 - Flow Control Calculations Exhibit 2 - Water Quality Calculations Exhibit 3 - Conveyance Calculations Appendix D Geotechnical Report Appendix E Site Improvement Bond Quantity Worksheet Facility Summary Sheet Appendix F Operation and Maintenance Manual 1. PROJECT OVERVIEW 1.1 Purpose and Scope The Northshore Plaza Retail Center project proposes to construct a 4,100 square -foot retail building and associated parking on a half -acre site located south of SW 340'h Street and west of Hoyt Road SW in the City of Federal Way, Washington. Off -site improvements to Hoyt Road SW along the project site frontage will also be constructed as part of this development. This report, which accompanies the grading, drainage and utility plans, describes the analysis and design of the stormwater facilities. The stormwater facility design conforms to the criteria outlined in the City of Federal Way Addendum to King County Surface Water Design Manual (KCSWDM). 1.2 Existing Conditions The project site is comprised of a half -acre of previously developed land located south of SW 340" Street and west of Hoyt Road SW in the City of Federal Way (see Figure 2, Appendix A for the Site Location Map). Surrounding uses include the Northshore Chevron and Car Wash to the north, the SW 340`' Street Regional Storage Facility across Hoyt Road SW to the east and single-family residences to the west and south. The existing site consists of two abandoned single-family homes with a shared asphalt -paved driveway. The remainder of the site consists of grass and brush. Zipper Zeman Associates, Inc. performed a geotechnical study of the site and found that the site consists of silty sand, underlain by medium dense to dense sand and gravel with variable silt. Please see Appendix D for the full geotechnical report. AHBL conducted a topographic survey of the site, which was used as a base map to delineate the project drainage sub -basins. It is included as Figure 3, Existing Conditions Map, in Appendix A. In general, stormwater runoff from the on -site portion of the proposed project improvements sheet flows westerly onto the residential properties located along the western boundary of the site. The downstream drainage path through the residential properties is coincident with the downstream drainage path for the Northshore Chevron and Car Wash located to the north of our project site at the time of its construction. Barghausen Consulting Engineers prepared a detailed Level 1 Downstream Drainage Analysis that describes this downstream path as field - verified by AHBL. We have included the Barghausen report in Appendix B as reference for the downstream drainage path description and analysis for this project. Stormwater runoff from the off -site portion of the proposed project improvements sheet flows to a shallow ditch along the western side of Hoyt Road SW. A catch basin is located approximately 165 feet south of the southeast corner project site. This catch basin is part of the conveyance system of the SW 340" Street Regional Storage Facility, which is located to the east of the project site. The onsite and offsite portions of the project improvements are, therefore, located in two separate sub -basins. 1.3 Post -Development Conditions Upon completion of construction, the Northshore Plaza Retail Building will include the following constructed facilities: a 4,100-square foot retail building, improvements along Hoyt Road SW, parking, landscaping and storm drainage features. As part of this construction, stormwater flow control and water quality facilities will be designed and constructed to mitigate the impacts of the project on the downstream systems. Refer to Figure 4 in Appendix A for the Developed Conditions Map. Public street improvements are also required as part of the development. Hoyt Road SW will be improved to a three -lane road with a 6-foot wide planter and an 8-foot wide sidewalk along the project site frontage. Per our discussions with City staff, the on -site and off -site portions of the project shall remain in their respective sub -basins and not be combined. Therefore, the existing offsite runoff patterns will be preserved. r The existing driveway entrance into the Northshore Chevron property will be reconfigured to provide additional access to the Northshore Plaza Retail Center. As part of this reconfiguration, the existing catch basin located at the low point of the driveway will be demolished and replaced by a new catch basin located within the area of the new street improvements. The new catch basin will be reconnected to the Northshore Chevron drainage system, thereby, maintaining the existing drainage patterns. The runoff from the remaining off -site improvements will continue to flow southerly to the conveyance system of the SW 340th Street Regional Storage Facility. 2. CONDITIONS AND REQUIREMENTS SUMMARY 2.1 Core Requirements 2.1.1 C.R. #1-Discharge at the Natural Location Currently, the on -site and off -site portions of the project site discharge to two sub -basins, as described above. Stormwater runoff from the on -site and off -site areas will continue to flow to their respective sub -basins. Off -site flows will not increase as a result of the improvements on Hoyt Road SW and on -site flows will be treated, detained and control -released to the existing downstream system. 2.1.2 C.R. #2 — Off -site Analysis In January and February 2004, AHBL staff conducted two field reviews of the project site. We concluded that the downstream drainage path of the on -site portion of the project improvements was coincident with the downstream drainage path of the Northshore Chevron and Car Wash as described by Barghausen Consulting Engineers, Inc. in their Level 1 Downstream Drainage Analysis report dated July 1996. Their report is included in Appendix B for reference. Stormwater runoff from the off -site portion of the proposed project improvements sheet flows to a shallow ditch or flowline along the western side of Hoyt Road SW to a catch basin located approximately 165 feet south of the southeast corner project site. The runoff then enters this catch basin and is conveyed to the SW 340`h Street Regional Storage Facility, which is located to the east of the project site. Please refer to the design reports for this storage facility for further information. 2.1.3 C.R. #3 - Flow Control The project site is located in a Level 1 Flow Control area per the City of Federal Way Flow Control map and pre -application correspondence with City staff. Level 1 Flow Control requires that detention be provided for onsite excess stormwater runoff, such that flows from the developed site match flows from the existing site for the 2- and 10-year storm events. This requirement is proposed to be met by use of a 55-foot long, 72-inch diameter detention pipe. Refer to Section 4 for further information on the proposed detention system. With regards to the off -site portion of the project improvements, it appears from our site visits and review of the survey information that runoff from the off -site improvements does not flow onto the project site. Instead, the off -site runoff flows southerly to a catch basin located on the western side of Hoyt Road SW approximately 165 feet south of the southern end of the project site. This catch basin is part of the conveyance system for the SW 340th Street Regional Storage facility as shown in Figure 5, Appendix A. The on -site and off -site portions of the project improvements are, therefore, located in two separate sub -basins. In our discussions with Ann Dower of the City of Federal Way Public Works Department, the City would like to see that the runoff from the on -site and off -site portions of the project remain in their respective sub -basins and not be combined. We propose, therefore, that the runoff generated from the off -site improvements be allowed to flow as it currently does in the existing condition to the conveyance system of the SW 340th Street Regional Storage Facility. This option is the most feasible option for the control and treatment of this runoff particularly since the total area of the offsite improvements is quite small. In fact, the total off -site improvement area is less than the 5,000-sf threshold for the requirement to provide both flow control and treatment. 2.1.4 C.R. #4 - Conveyance System The conveyance system consists of 8-inch and 12-inch conveyance pipes. Please refer to Section 5 of this report for further information. 2.1.5 C.R. #5 - Erosion and Sediment Control An erosion and sediment control plan has been developed for this site in accordance with the City of Federal Way Amendment to the King County Surface Water Design Manual. Measures include limiting the area to be disturbed, silt fencing, catch basin inlet sediment barriers and proper cover practices. Please refer to Section 7 of this report for further information. _ J 2.1.6 C.R. #6 - Maintenance and Operations A Maintenance and Operations Manual is included in Appendix F. _J _J 5 2.1.7 C.R. #7 - Financial Guarantees and Liability This project will comply with the City of Federal Way financial guarantee requirements. 2.1.8 C.R. #8 - Water Quality The project site is subject to "Resource Stream Protection water quality treatment according the City of Federal Way Water Quality Area map and discussions with city staff. This treatment requirement is proposed to be met with a treatment train consisting of a Stormgate Separator and a 3-cartridge Leaf Compost Filter. Water quality facility design is discussed further in Section 4. 3. OFF -SITE ANALYSIS 3.1 Downstream Analysis 3.1.1 Task 1— Study Area Definition and Maps The Northshore Plaza Retail Center project proposes to construct a 4,100 square -foot retail building and associated parking on a half -acre site located south of SW 340`h Street and west of Hoyt Road SW in the City of Federal Way, Washington. Off -site improvements to Hoyt Road SW along the project site frontage will also be constructed as part of this development. 3.1.2 Task 2 — Resource Review The following resources were reviewed to discover any existing or potential problems in the study area: 1. Adopted Basin Plans: AHBL staff reviewed the Executive Proposed Basin Plan for Hylebos Creek and Lower Puget Sound to discover any documented existing or potential drainage problems and to check for additional detention and water quality standards. This plan, which was prepared by King County Surface Water Management Division staff in 1991, requires that supplemental detention requirements be applied. Per our discussions with City of Federal Way staff, these supplemental detention requirements are not necessary for the development of this project site. 2. Off -site analysis reports: The Level 1 Downstream Drainage Analysis for McDonald's/Chevron prepared by Barghausen Engineers in July 1996 was also reviewed. This commercial development is located directly north of the project site, off of South 341't Street. The downstream drainage path of our project site is coincident with the downstream of the Chevron property. AHBL staff field -verified the findings of Barghausen during our site visits in January and February of 2004. The Barghausen report is included in Appendix B for reference. 3. FEMA Map: A FEMA map was consulted and the site does not he within a floodplain. 4. Critical Areas Map and Wetlands Inventory Map: A sensitive area review was conducted for the project site, which revealed that the project site does not he within a critical area nor does it contain any wetlands. Soils Information: Zipper Zeman Associates, Inc. performed a geotechnical study of the site and found that the site consists of silty sand, underlain by medium dense to dense sand and gravel with variable silt. Please see Appendix D for the full geotechnical report. We have also contacted the King County Department of Natural Resources regarding drainage complaints. None have been reported. 3.1.3 Task 3 —Field Inspection In January and February 2004, AHBL staff conducted two field reviews of the project site. In general, stormwater runoff from the on -site portion of the proposed project improvements sheet flows westerly onto the residential properties located along the western boundary of the site. Ultimately, the project site drains into the lower branches of Joe's Creek. The downstream drainage path through the residential properties is coincident with the downstream drainage path for the Northshore Chevron and Car Wash located to the north of our project site at the time of its construction. Barghausen Consulting Engineers prepared a detailed Level 1 Downstream Drainage Analysis that describes this downstream path as field - verified by AHBL. We have included the Barghausen report in Appendix B as reference for the downstream drainage path description and analysis for this project. With regards to the off -site portion of the project improvements, it appears from our site visits and review of the survey information that runoff from the off -site improvements does not flow onto the project site. Instead, the off -site runoff flows southerly to a catch basin located on the western side of Hoyt Road SW approximately 165 feet south of the southern end of the project site. This catch basin is part of the conveyance system for the SW 340th Street Regional Storage facility as shown in Figure 5, Appendix A. The on -site and off -site portions of the project improvements are, therefore, located in two separate sub -basins. 3.2 Upstream Analysis It appears from our field reviews and topographic survey that there are no upstream areas that are tributary to our project site. 4. FLOW CONTROL AND WATER QUALITY FACILITY ANALYSIS AND DESIGN 4.1 Flow Control 4.1.1 Existing Site Hydrology The project site drains approximately 0.48 acres of on -site area. Of this area, approximately 0.37 acres is vegetated (till grass) while 0.11 is impervious. The soils in this area are Alderwood association, which is classified as "till" for KCRTS modeling purposes. The Existing Conditions Map is included as Figure 3 in Appendix A. 4.1.2 Developed Site Hydrology The developed on -site area consists of 0.11 acres of landscaping (till grass) and 0.37 acres of impervious surface. The finished surface will be graded to facilitate drainage to catch basins which will drain to the water treatment and flow control structures. The Developed Conditions Map is included as Figure 4 in Appendix A. 4.1.3 Flow Control Flow control will be provided by a 72-inch corrugated metal detention pipe sized per the Level 1 Flow Control Requirement. KCRTS methodology was employed to design a detention system such that flows from the developed site will match flows from the existing site for the 2- and 10-year storm events. The detention pipe is calculated to be 55 feet in length. The associated downstream control structure includes a 12" riser with one restrictor orifice with a 1.02" diameter. The detention pipe will be placed 6" below the 36" inlet and outlet pipes in order to provide sediment storage. See Appendix C for detention pipe and control structure sizing calculations. 4.2 Water Quality The project site is subject to "Resource Stream Protection water quality treatment according the City of Federal Way Water Quality Area map and discussions with City staff. To meet the requirements of the City of Federal Way Amendment to the King County Surace Water Deign Manual, a treatment train is proposed consisting of a Stormgate Separator, and a 3-Cartridge Leaf Compost Filter, both manufactured by Stormwater Management, Inc. The water quality facilities have been designed to treat incoming flow for up to 60% of the 2- year, 24-hour storm event for the developed site. That flow rate has been determined to be 0.0804 cfs as determined by KCRTS methodology. Roof, sidewalk and landscape drainage, not requiring treatment, will bypass the system and discharge directly to the detention system. The Stormgate Separator provides oil and sediment removal and serves as a presettling basin for the compost filter. The separator was designed based on the incoming flow rate. The 1100 model was chosen, with a recommended fl««r rate of 0.32cfs (maximum of 0.48 cfs). The developed flow rate for the site, excluding roof and landscape areas not tributary to the treatment facilities, is 0.32 cfs; therefore, no bypass for higher flows will be necessary. Nevertheless, a high -flow bypass weir is provided as a standard appurtenance. Upon sediment removal, stormwater is discharged directly to the compost filter. The compost filter provides suspended pollutant removal and additional sediment removal. As directed by the KCSWDM and the City of Federal Way, the design adheres to the criteria established by the manufacturer, Stormwater Management, Inc. Per discussions with the City, the manufacturer's recommendation of 15 gallons per minute (gpm) per filter is adequate to provide pollutant removal. The design flow rate of 0.0804 cfs is equivalent 36.08gpm. At 15gpm each, three filters can provide a total capacity of 45gpm; therefore, a 3- cartridge system should be adequate. An overflow weir is also provided within this system in the event of higher flows. Upon treatment, all flows are discharged to the detention system. See Appendix C for KCRTS modeling and manufacturer's specifications. 5. CONVEYANCE SYSTEM ANALYSIS AND DESIGN The on -site stormwater network will be sized to adequately convey the 25-year storm event, as stipulated by the City of Federal Way Amendment to the King County Surface Water Design Manual. The main conveyance system for the project site is downstream of the detention area. A backwater analysis of the on -site conveyance system was performed using KCRTS methodology to ensure that the system can adequately convey the developed 25-year, 24-hour storm event as required. A backwater analysis of the off -site conveyance system was also performed to demonstrate that the off -site system has sufficient capacity. Please refer to Appendix C for the conveyance calculations.. 6. SPECIAL REPORTS AND STUDIES A Geotechnical Engineering Report was prepared for the project site and is included in Appendix D. 7. ESC ANALYSIS AND DESIGN The proposed development shall comply with guidelines set in the City of Federal Way Amendment to the King County Surface Water Design Manual. The plan will include erosion/sedimentation control features designed to prevent sediment -laden runoff from leaving the site or adversely affecting critical water resources during construction. The following measures will be used to control sedimentation/erosion processes: • Clearing limits — all areas to remain undisturbed during the construction of the project will be delineated prior to any site clearing or grading. • Cover measures — disturbed areas shall be covered as required in Section D.4.2 of the KCSWDM. • Construction entrance — a stabilized construction entrance consisting of quarry spalls will be used during construction of the project. ■ Perimeter protection - filter fabric fences for ditch and site runoff protection will be provided at the downstream site perimeter. • Catch basin inlet sediment protection — filter fabric protection will be provided on all new and existing catch basins downstream of construction activities. Due to the nature of the site, perimeter silt fencing will be the primary erosion control element. No sediment traps will be necessary as the site is small (less than'/z-acre), relatively flat and the construction timeframe is expected to be brief. 8. OPERATIONS AND MAINTENANCE PLAN Operations and maintenance will be the responsibility of the owner. All drainage facilities shall be maintained and operated in compliance with the City of Federal Way and King County maintenance standards. The Operation and Maintenance Manual for the privately - maintained drainage facilities is included in Appendix F. 9. CONCLUSION This site has been designed to meet the City of Federal Way Amendment to the King County Surface Water Design Manual guidelines for stormwater management. The site incorporates water quantity and quality facilities for stormwater flows. Flow calculations/modeling utilized the Federal Way standards for sizing stormwater detention and treatment facilities and for sizing conveyance networks. It was determined utilizing these criteria that: • A detention facility is required for the project. • Water quality facilities are required at the Stream Protection Level. • Pipe networks are to be of adequate size to effectively convey the 25-year storm. This analysis is based on data and records either supplied to, or obtained by, AHBL, Inc. These documents are referenced within the text of the analysis. The analysis has been prepared utilizing procedures and practices within the standard accepted practices of the industry. We conclude that this project, as proposed, will not create any new problems within the existing downstream drainage system. This project will not noticeably aggravate any existing downstream problems due to either water quality or quantity. AHBL, Inc. JEC/lak March 2004 Revised May 2004 517tir040318.doc 10 APPENDIX A Exhibits Figure 1— TIR Worksheet Figure 2 — Site Location Figure 3 — Existing Conditions Map Figure 4 — Developed Conditions Map Figure 5 - SW 340' Regional Detention Facility Basin Map King County Department of Development and Environmental Services TECHNICAL INFORMATION REPORT (TIR) WORKSHEET Part 1 PROJECT OWNER AND PROJECT ENGINEER Project Owner Address Phone 253- 026 - 9455 Project Engineer - le (71ye,97' Company P"4, INC. Address/Phone 2 - 3 3 —Z�f22 Part 3 TYPE OF PERMIT APPLICATION ❑ Subdivison ❑ Short Subdivision ❑ Grading Commercial ❑ Other Part 2 PROJECT LOCATION AND j DESCRIPTION Location Township Range 3� ..........Section 23 /Vo # 3o8R'60 Part 4 OTHER REVIEWS AND PERMITS ❑ DFW HPA ❑ Shoreline Management ❑ COE 404 ❑ Rockery ❑ DOE Dam Safety ❑ Structural Vaults ❑ FEMA Floodplain ❑ Other ❑ COE Wetlands Part 5 SITE COMMUNITY AND DRAINAGE BASIN Community CIA/ Or & Drainage Basin l ovier `7uy�� S�L1hG1 Part 6 SITE CHARACTERISTICS ❑ River ❑ Floodplain ❑ Wetlands _ Part 7 SOILS Soil Type Slopes ldkoya" B 2 - a '/. ❑ Additional Sheets Attached Part 8 DEVELOPMENT LIMITATIONS REFERENCE ❑ Ch. 4 — Downstream Analysis El El El ❑ Additional Sheets Attached Part 9 ESC REQUIREMENTS MINIMUM ESC REQUIREMENTS DURING CONSTRUCTION Sedimentation Facilities R Stabilized Construction Entrance Perimeter Runoff Control ❑ Clearing and Graing Restrictions ❑ Cover Practices R" Construction Sequence ❑ Other Erosion Potential Erosive Velcoties S1OIN LIMITATION/SITE CONSTRAINT MINIMUM ESC REQUIREMENTS AFTER CONSTRUCTION Stabilize Exposed Surface ❑ Remove and Restore Temporary ESC Facilities 0' Clean and Remove All Silt and Debris [►� Ensure Operation of Permanent Facilities ❑ Flag Limits of SAO and open space preservation areas ❑ Other Part10 SURFACE WATER SYSTEM ❑ Grass Lined Channel Pipe System ❑ Open Channel ❑ Dry Pond ❑ Wet Pond wank ❑ Vault ❑ Energy Dissapator ❑ Wetland ❑ Stream ❑ Infiltration ❑ Depression ❑ Flow Dispersal ❑ Waiver Regional Detention Brief Descripti n of System Operation 07-ol/C a(G on -AWM4 .; -�` ,,,filler Ac1I1fie-19�- Facility Related Site Limitations Reference Facility Limitation I Part 11 STRUCTURAL ANALYSIS ❑ Cast in Place Vault ❑ Retaining Wall ❑ Rockery > 4' High ❑ Structural on Steep Slope ❑ Other Method of Analysis A'C,f rs Compensation/Mitigati on of Eliminated Site Storage 1110e 5 AA!M 17 Part 12 EASEMENTS/TRACTS ❑ Drainage Easement ❑ Access Easement ❑ Native Growth Protection Easement ❑ Tract ❑ Other Part 13 SIGNATURE OF PROFESSIONAL ENGINEER I or a civil engineer under my supervision my supervision have visited the site. Actual site conditions as observed were incorporated into this worksheet and the attachments. To the best of my knowledge the information provided here is accurate. r � +AHSL IN a r � SW 320TH S _ L _ o � N SHORE PKWY a `� u7 SW 340TH ST S 348 ST S 356TH ST SIT y h NOT TO SCALE im [BOB NORTHSHORE PLAZA RETAIL TACOMA • SEATTLE FIG. 2 2215 North 30th Street, Suite 300, Tacoma, WA 9S403 2533932422 TEL SITE LOCATION Occide d Avenue South, Suite 32D, Seattle, WA 98104 N6 267 2425 is WL TACOMA • SEATTLE 2215 North 301A Street, Surle 300, Tacoma, WA 96403 253 3832422 TEL 316 Ooidmtel Avenue South, Sole 320, Seattle, WA 96104 20B2672425 TEL 1 r P��ITAIre �lj IMIM00 T A C O M A - S E A T T L E 2215 Vojwx�m-WOOW3 75 3M.24223E LI) IbL� Lp co LJ Jr n rz., / �� = L 0 0 Li 15kV 75 Control Structure Ir 11.3 Acre -Foot---' Storage ffoyr ow E�p W. 342ND Sr 77 0 GWEW- mmom T A C O M A - S E A T T L E 2215Narth301hStram.SL4le300,Taawna,WA,9UD2 2533632422TEL 316 OccidenW Avmw So^ Sate 32D. Seatk *A 96 104 206 267 2425 TEL APPENDIX B Downstream Analysis Figure 1— Level 1 Downstream Drainage Analysis for McDonald's/Chevron, prepared by Barghausen Engineers, Inc., July 1996 n OUR JOB NO. 5869 JULY 1996 Prepared By: BARGHAUSEN CONSULTING ENGINEERS, INC. 18215 72ND AVENUE SOUTH KENT, WASHINGTON 98032 (206) 251-6222 EXPIRES 4JJI a CIVIL ENGINEERING, LAND PLANNING, SURVEYING, ENVIRONMENTAL SERVICES SEE POP - - 14 :W-•;$: f� _-.....-�_�--� _.._—.,»-_�—.jam-._....__—_.--� e r� E _ i Sv 296iM ST h k pow": AD Ur A a v W RIM Si r �)IOUND A. ST f^'� LAIC all 6 � •��• a ]0kS i ali25 ���w '.�A:vi" Y� C At ]01,4 a �* r � r• 304rV K' TINt rw FL jAX ¢ iSTS G i +� i SM p1iK n 30 ~4t M a imam. -- _ �_-aY x p r. � r ram+ . ?^-T •' 111 N' i .y PI n[PN K y��� JJ 1 !r i 1i.i11 r� it ylisp rr .wlw sY j+•• vy` i" y, „ O 6Sif Sir y Z 31m ST ~- n IM1•. milt rl 1 at ry S� Sr r w • Sf Q� d r 6 G K r •r a 7SK L9i7) ,p� �rw � _ � lidW r sr ]IS1Y !� 1 S : N' a* 1 >% .3 i x y }!R ��l q e � �0p n " 4A a 5T 5 3'm $ .w SY my ST aan �'�f ,yi AI ]til0 1c a r . - .. � r ■fR ¢`'r { 57 • it � .. � r � 4 3i'SRD ST � R r. y R � � ` _i� - ti K d .S".(a� too r + •` . •' GQ'/ n � � .3 +� SSA r d ■ a[1t 1• r rro •` �. Q 1 Y } .Sy,,!`' r 's * r• r mAfY _ ; - w SR nW r � � SS fa � y 1U �a � ,e S[ k ry i 17 sw r. irW € ■ � I�ITlY IS SY K r •� ;' '+ x 1 -c � • ,fir ^'i' rt V fS "'4 !Sgo It Ear �.•-.•. '4c � ti � !'�•c>:;•�. ;,ms � N, � ".rA • r� `.rn H Mfi • �� ' • a w * .un . _� sr , �'RN[:- 7. t;' f ,fAff YS 5 rw CH Sw 1LA Rica F E � ERA L - ■ e' ;il " ,r.rKra + r n � :Aare 1:.; t Jt Ai' rva si dl y 19 i.,•Jy�tUff r 11 Sr @ y qq $ F. '_� �l � SY ]{iTK ST SY ]M1N F l+tn .+„�• x w ,pRrk ` < i AI 3[fT,l Si , r '4 A >r �, a S OLF R x ' r ST e rn r rn i r 7 _ Fi AI }la'Tli 1� d AI r c ' [ . v,. ` s • yr wiR Y r r A: p y lrRm CT S 3187O S c . � AI 3a9TH n r R .� e3•!: SEE naP McDONALUS/CHEVRON FEDERAL WAY, WA SITE LOCATION MAP 1" = 2400' BCE 5869 7/01/96 I. INTRODUCTION/GENERAL INFORMATION . The proposed 2.1-acre MGDonald'S/Chevron site is located in the northeast quarter of Section 23, Township 21 North, Range 3 East, W.M., King County, Washington. The site lies at the southwest corner of S.W. 340th Street and Hoyt Road S.W. within the City of Federal Way. The site is bordered to the south and west by residential properties. The southwest property line forms the boundary between Federal Way in King County and the City of Tacoma in Pierce County. The site is bordered to the east by Hoyt Road S.W., which runs roughly along a north/south ridge. Hoyt Road S.W. and S.W. 340th Street (North Shore Parkway in Tacoma/Pierce County) prevent any off- site/upstream drainage from entering the site. H. EXISTING CONDITIONS The grades on the relatively flat site generally fall to the west at approximately 0.5 percent to 3 percent. Topography maps indicate runoff from a small portion (0.20 acres t) of the southeast corner of the site flows toward the south property line and/or Hoyt Road S.W. Runoff from the remainder of the property clearly flows west and exits the site along the southwest property line. A copy of the topographic survey showing on -site flow characteristics has been included in the appendix of this report. The site is currently undeveloped and contains no structures or impervious area. Existing ground cover consists of heavy brush and grasses with widely scattered significant trees. The soils consist of Alderwood gravelly sandy loam according to the King County Soils Survey. Most on -site drainage sheet flows to the west and is collected by a 2- to 3-foot wide shallow ditch running from the southwest property corner along the property line to the northwest for approximately 200 feet. At this point, runoff tends to spread out and flow west off the property. The northeast corner of the site contains one small closed depression. Overflow from this depression would sheet flow to the west. No other defined drainage courses are apparent on site. The site investigation was performed on Saturday, June 29, 1996, between 12:00 and 2:00 p.m. under mostly sunny skies and warm temperatures. M. DOWNSTREAM ANALYSIS As drainage exits the site across fHe west property line, it actually leaves the City of Federal Way and enters the City of Tacoma. All points described in the following paragraphs are located within the City of Tacoma. Site runoff sheet flows over the property line to the west into a portion of a residential plat currently nearing the completion of construction located at the east end of 45th Street N.E. The new plat is called Hawthorne Hills and appears to have no provisions to intercept upstream runoff and route the runoff through the site or bypass the runoff around the site. Prior to the development of Hawthorne Hills, drainage would generally flow to the west by means of sheet or shallow concentrated flow through brushy and forested conditions. It would ultimately reach the low area now occupied by a lake on the Northshore Golf Course that will be described in detail later in this report. In current conditions, our site inspection revealed that flow would continue toward the west between houses fronting 44th Street N.E. and 45th Street N.E. within the Hawthorne Hills plat. Although there were no defined drainage ditches or conveyance systems found along the eastern most 200 f feet of the 5869.001 [KWLks/csl plat, it is apparent that runoff sheet flows at approximately 2 percent between the homes, stepping down �1 approximate 3-foot slopes between lots. It did not appear that the minimal flow expected during storm . events would pose a threat to the newly constructed homes, due to the nature of the grades sloping away from the homes. The ground is currently bare due to recent grading, but appears to have been prepared for planting of grass. Please refer to Sections A and B in the appendix for a profile representation of this area. A ditch has been constructed between the homes approximately 300 feet west of the property line that appears to catch the site flow as well as roof and yard drainage from the new plat. The ditch flows approximately 100 to 150 feet west before bending to the northwest and discharging into a low manmade closed depression. The ditch is 2 to 4 feet wide and shallow. The closed depression appears to be a temporary retention pond and is currently dry. The pond has no outlet structure. A 6-inch PVC pipe discharges over the newly constructed southern curb and gutter of 45th Street N.E. The 6-inch pipe appears to be a pond overflow pipe. The inlet end of the pipe in the pond, however, is buried, and was not found during the site investigation. Drainage continues to the west down the south gutter of 45th Street N.E. at a grade leveling from approximately to to 2 percent for 200t feet before dropping into a catch basin and being tightlined into a 12-inch storm drainage system approximately 300 feet west to 45th Avenue N.E. At 45th Avenue N.E., the drainage is turned and runs approximately 350 feet in a series of pipes and locked -cover manholes toward 44th Street N.W. The conveyance system consists of a 12-inch concrete pipe, at approximately 1 percent, which serves 45th Street N.E. and a small portion of 45th Avenue N.E. At 44th Street N.E. the conveyance system turns toward the northwest and runs in a storm drainage easement through the east portion of the On -the -Green Apartment complex. By this time, the conveyance system also serves over 2,000 lineal feet of 45th Avenue N.E. as well as several side streets to the east of 45th Avenue N.E. The system consists of a 21-inch concrete pipe and Type H catch basins with solid locked lids. Slopes range from 2.5 to 16 percent. After crossing through the apartments, the drainage is conveyed due north in a 24-inch concrete pipe beneath a fairway of Notthshore Golf Course, at a slope of approximately 1 percent. This system discharges into the south end of a lake located on the golf course. This discharge into the lake is approximately 2,000 feet downstream of the proposed Chevron/McDonald's site. The lake is irregularly shaped, approximately 700 feet long and 50 feet to 150 feet wide. The lake also functions as a detention pond for the On -the -Green Apartment complex. Controlled release is discharged from the north end of the lake into a 15-inch concrete pipe flowing roughly northeast at 1 t percent. No construction or visible problems were observed at the inlet end or outlet end of the lake. Drainage continues to be conveyed northeasterly beneath Nonlishore Parkway in a 15-inch concrete pipe. The pipe size is increased to 21-inch concrete at a manhole located within the street. The 21-inch concrete pipe outfalls north of the right-of-way into a well-defined creek channel. The outlet into the creek channel is by means of a double -concrete head wall. A second 21-inch pipe discharges at the same head wail. It appears this pipe is from North.shore Parkway to the northwest. The 21-inch concrete pipe from the lake has no sediment buildup at the outlet. The second 21-inch concrete pipe however, is approximately one-half silted at the outlet. 5869.001 RCWL"Csl p j IV. CONCLUSIONS/RECOM ENDA'I'IONS Based on our field investigation and research of downstream drainage systems, we feel the only potential problem runoff from the site is to the east portion of the Hawthorne Hills plat where flow currently exits the site. To avoid this potential problem following construction, we recommend that drainage be tightli,ned to the existing storm drainage conveyance system located in Northshore Parkway, if this system contains sufficient capacity. The site is located within the south lower Puget Sound sub -basin. Retention requirements in this sub -basin consist of releasing water from the site at a peak rate of 70 percent of the 2-year pre -developed peak nuioff rate and providing storage to detain the 100-year storm event. Due to these restrictions, the impact on downstream systems following development should be minimal, if not insignificant. 5869.001 UCWLIWCsl ANALYSIS OF SEVEN CORE REQUIREMENTS 1. Discharge at the Natural Location The site will continue to drain into the same drainage basin that it currently does after the development occurs. However, because of the absence of an immediate defined downstream drainage course, the overflow discharge point is to an existing storm drain in S.W. 340th Street. The low level storms will be infiltrating into the sub -soils as required by, the City, with the additional overflow discharge into the existing pipe system within S.W. 340th Street. 2. Off -site Analysis An off -site analysis has been completed per the Level I Drainage Study. 3. Runoff Control The runoff from the developed area of this project is being controlled per the approval of the stormwater control plans. This will include storing the 100-year storm event while releasing no more than 70 percent of the 2-year pre -developed peak flows. 4. Conveyance System i A conveyance system has been proposed to collect and route all the developed stormwater flows into the stormwater discharge system. S. Temporary Erosion and Sedimentation Control Prior to construction plan approval, a detailed erosion control plan will be prepared in conformance to City standards. 6. Maintenance and Operation In the final drainage report, requirements for the maintenance and operation of the stormwater systems will be identified. 7. Bonds and Liability Required bonds necessary for construction plan approval will be done in conformance to City standards. 5869.001 [KWI.Ji CSl ANALYSIS OF SPECIAL REQUIREMENTS 1. Critical Drainage Areas The site is located within the Executive Proposed Basin Plan for Hylebos Creek and Lower Puget Sound. The design of the detention system is in conformance with this plan. 2. Compliance with an Existing Master Drainage Plan As mentioned above, the proposed design of the system meets the criteria established in the Master Drainage Plan. 3. Conditions Requiring a Master Drainage Plan This section is not applicable due to the size of the project. 4. Adopted Basin or Community Plans The proposed project is within an RS9600 zone. However, it has been proposed to be redesignated to a BN designation. 5. Special Water Quality Controls This project does not meet the threshold requiring special water quality controls. 6. Coalescing Plate Oil/Water Separators This project does not meet the threshold requiring this installation. 7. Closed Depression This project does not have a closed depression located on -site and does not meet the threshold requiring this analysis. 8. Use of Lakes, Wetlands, or Closed Depressions for Runoff Control This project does not meet the threshold requiring this analysis. 9. Delineation of the 100-Year Flood Plain The proposed project does not lie within or near a 100-year flood plain associated with a stream or body of water. 5869.001 R{WlJt CSI 10. Flood Protection Facilities for Type 1 and 2 Streams This project does not meet the threshold requiring analysis or special facilities to be built. 11. Geotechnical Analysis and Report A geotechnical report has been prepared for the project and is being submitted for information. 12. Soils Analysis and Report This project does have a soils report prepared for the project even though the threshold for this condition does not necessitate the requirement. 5869.001 [KWLAdcsl 6 uchi O U 0 w u u Yl o O U O U .r 3 yd U A v] o p 0 x v z p U x � •�. ��: 2 5 °° O O .+ d G M e �oE c o ou�0 �) q O °) • :5-�d z° w w z A o z a 0 � s� $ 5 q p y bu�yy {u{yy l7 � c a a ��d•° & w a a a a a G a a qu y 0>3 0 o z °' M. o z 0 z 0 z 0 z 0 z 0 z 0 z ❑ U oa N z oa N Q 8 8 S 1 (� VV" C � cV 'y C••j N M M M cn O N h ww O` O O N N N O N —4 tr1 N c3 e� E o aui ►a lu cn i° u O CL o a y y V .+ 'd � a •V N y u > 5+G a b 3 0 o •y .� %0 cps 'A coy ba u b b chi A v A q h N M �3 N u u cbo c o 3 a u -.M U y. � N O y u O tE � u N A $ Vn v3 v� u y� c7 � y APPENDIX C Hydrologic Analysis Exhibit 1— Flow Control Calculations Exhibit 2 — Water Quality Calculations Exhibit 3 — Conveyance Calculations �x&IFir / L) u Q u u u c Li .- F— m CL m _ •— F' 6. 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I; 0 1 :1-- u . . . . . . . . r-I k 1 p-..00000CDa� �4 rl $-1 1 p r=4 E- P4 1 r-1 F- I74 I --I �X4 V C) Retention/Detention Facility Type of Facility: Detention Tank Tank Diameter: 6.00 ft Tank Length: 55. ft Effective Storage Depth: 5.00 ft Stage 0 Elevation: 0.00 ft Storage Volume: 1392. cu. ft Riser Head: 5.00 ft Riser Diameter: 12.00 inches Number of orifices: 1 Full Head Pipe Orifice # Height Diameter Discharge Diameter (ft) (in) (CFS) (in) 1 0.00 1.02 0.063 Top Notch Weir: None Outflow Rating Curve: None Stage Elevation Storage Discharge Percolation (ft) (ft) (cu. ft) (ac-ft) (cfs) (cfs) 0.00 0.00 0. 0.000 0.000 0.00 0.01 0.01 3. 0.000 0.003 0.00 0.02 0.02 5. 0.000 0.004 0.00 0.03 0.03 8. 0.000 0.005 0.00 0.04 0.04 10. 0.000 0.006 0.00 0.05 0.05 13. 0.000 0.007 0.00 0.06 0.06 15. 0.000 0.007 0.00 0.07 0.07 18. 0.000 0.008 0.00 0.08 0.08 20. 0.000 0.008 0.00 0.18 0.18 46. 0.001 0.012 0.00 0.28 0.28 73. 0.002 0.015 0.00 0.38 0.38 100. 0.002 0.018 0.00 0.48 0.48 129. 0.003 0.020 0.00 0.58 0.58 158. 0.004 0.022 0.00 0.68 0.68 187. 0.004 0.023 0.00 0.78 0.78 217. 0.005 0.025 0.00 0.88 0.88 248. 0.006 0.027 0.00 0.98 0.98 279. 0.006 0.028 0.00 1.0& 1.08 310. 0.007 0.029 0.00 1.18 1.18 342. 0.008 0.031 0.00 1.28 1.28 374. 0.009 0.032 0.00 1.38 1.38 406. 0.009 0.033 0.00 1.48 1.48 439. 0.010 0.034 0.00 1.58 1.58 472. 0.011 0.036 0.00 1.68 1.68 505. 0.012 0.037 0.00 1.78 1.78 538. 0.012 0.038 0.00 1.88 1.88 571. 0.013 0.039 0.00 1.98 1.98 604. 0.014 0.040 0.00 2.08 2.08 637. 0.015 0.041 0.00 2.18 2.18 670. 0.015 0.042 0.00 2.28 2.28 703. 0.016 0.043 0.00 2.38 2.38 736. 0.017 0.044 0.00 2.48 2.48 769. 0.018 0.044 0.00 2.58 2.58 802. 0.018 0.045 0.00 2.68 2.68 834. 0.019 0.046 0.00 2.78 2.78 866. 0.020 0.047 0.00 2.88 2.88 898. 0.021 0.048 0.00 2.98 2.98 930. 0.021 0.049 0.00 3.08 3.08 961. 0.022 0.050 0.00 3.18 3.18 992. 0.023 0.050 0.00 3.28 3.28 1022. 0.023 0.051 0.00 3.38 3.38 1052. 0.024 0.052 0.00 3.48 3.48 1081. 0.025 0.053 0.00 3.58 3.58 1109. 0.025 0.053 0.00 3.68 3.68 1137. 0.026 0.054 0.00 3.78 3.78 1164. 0.027 0.055 0.00 3.88 3.88 1191. 0.027 0.056 0.00 3.98 3.98 1216. 0.028 0.056 0.00 4.08 4.08 1240. 0.028 0.057 0.00 4.18 4.18 1264. 0.029 0.058 0.00 4.28 4.28 1286. 0.030 0.058 0.00 4.38 4.38 1307. 0.030 0.059 0.00 4.48 4.48 1326. 0.030 0.060 0.00 4.58 4.58 1344. 0.031 0.060 0.00 4.68 4.68 1360. 0.031 0.061 0.00 4.78 4.78 1374. 0.032 0.062 0.00 4.88 4.88 1385. 0.032 0.062 0.00 4.98 4.98 1392. 0.032 0.063 0.00 5.00 5.00 1392. 0.032 0.063 0.00 5.10 5.10 1392. 0.032 0.372 0.00 5.20 5.20 1392. 0.032 0.935 0.00 5.30' 5.30 1392. 0.032 1.670 0.00 5.40 5.40 1392. 0.032 2.460 0.00 5.50 5.50 1392. 0.032 2.740 0.00 5.60 5.60 1392. 0.032 3.000 0.00 5.70 5.70 1392. 0.032 3.230 0.00 5.80 5.80 1392. 0.032 3.450 0.00 5.90 5.90 1392. 0.032 3.660 0.00 6.00 6.00 1392. 0.032 3.850 0-00 6.10 6.10 1392. 0.032 4.040 0.00 6.20 6.20 1392. 0.032 4.210 0.00 6.30 6.30 1392. 0.032 4.380 0.00 6.40 6.40 1392. 0.032 4.550 0.00 6.50 6.50 1392. 0.032 4.700 0.00 6.60 6.60 1392. 0.032 4.860 0.00 6.70 6.70 1392. 0.032 5.000 0.00 6.80 6.80 1392. 0.032 5.150 0.00 6.90 6.90 1392. 0.032 5.290 0.00 7.00 7.00 1392. 0.032 5.420 0.00 Hyd Inflow Outflow Peak Storage Target Calc Stage Elev (Cu-Ft) (Ac-Ft) 1 0.20 ******* 0.20 5.04 5.04 1392. 0.032 2 0.11 ******* 0.07 5.00 5.00 1392. 0.032 3 0.14 0.06 0.06 4.99 4.99 1392. 0.032 h'] 10 yr- 4 0.10 ******* 0.D6 4.11 4.11 1247. 0.029 Q 5 0.12 ******* 0.06 3.92 3.92 1202. 0.028 �T�lk 6 0.11 0.04 0.05 2.90 2.90 903. 0.021 7 0.08 ******* 0.04 1.78 1.78 536. 0.012 8 0.09 ******* 0.04 1.67 1.67 503. 0.012 ---------------------------------- Route Time Series through Facility Inflow Time Series File:dev.tsf Outflow Time Series File:rdout Inflow/Outflow Analysis Peak Inflow Discharge: 0.198 CFS at Peak Outflow Discharge: 0.198 CFS at Peak Reservoir Stage: 5.04 Ft Peak Reservoir Elev: 5.04 Ft Peak Reservoir Storage: 1392. Cu-Ft 0.032 Ac-Ft Flow Frequency Analysis Time Series File:rdout.tsf Project Location:Sea-Tac ---Annual Peak Flow Rates --- Flow Rate Rank Time of Peak (CFS) 0.057 4 2/09/01 19:00 0.038 7 1/05/02 17:00 0.056 5 2/27/03 10:00 0.037 8 8/23/04 20:00 0.048 6 10/28/04 19:00 0.072 2 1/18/06 20:00 0.063 3 11/24/06 5:00 0.198 1 1/09/08 7:00 Computed Peaks 6:00 on Jan 9 in Year 8 7:00 on Jan 9 in Year 8 -----Flow Frequency Analysis------- - - Peaks - - Rank Return Prob (CFS) (ft) Period 0.198 5.04 1 100.00 0.990 A0.07,2 5.00 2 25.00 0.960 ✓_0.063 4.99 3 10.00 0.900 0.057 4.11 4 5.00 0.800 056 3.92 5 3.00 0.667 2 0t11 ✓0.048 2.90 6 2.00 0.500 0.038 1.78 7 1.30 0.231 0.037 1.67 8 1.10 0.091 0.156 5.03 50.00 0.980 6XV7$1T 2 M, ca t� t) U u c) U U 0.. LU J r 4-01 0 i Li Li _ CL 4i 0 cn —J i O O qr- o O Un 3 1 Ci COI O <; r 7 o .E G) �LID 0 t� F-- i Q? U) c [r, co O s A �_ O O � O p a 0 �0 %Q � � N O O a CD 00 CD co ��iyy 1_ ) 4�14:2 A CD Q. 'l O O Iju. M O cq CAI I � O 7- KING COUNTY, WASHINGTON, SURFACE WATER DESIGN MANUAL 6.2 GENERAL REQUIREMENTS FOR WQ FACILITIES This section presents the general requirements for water quality (WQ) facilities. When detail in the WQ designs is lacking, refer to Chapter 5 for guidance. In cases where requirements are extremely costly, a less expensive alternative that is functionally equivalent in terms of performance, environmental effects, health and safety, and maintenance can be sought through the adjustment process (see Section 1.4). Use of Metal Materials Galvanized metals leach zinc into the environment, especially in standing water situations. High zinc concentrations, sometimes in the range that can be toxic to aquatic life, have been observed in the region-" Therefore, use of galvanized materials in stormwater facilities and conveyance systems is discouraged. Where other metals, such as aluminum or stainless steel, or plastics are available, they should be used. 6.2.1 WATER QUALITY DESIGN FLOWS Water Quality Design Flow The water quality design flow is defined as follows: Preceding detention: 60% of the developed two-year peals flow rate, as determined using the KCRTS model with 15-minute time steps calibrated to site conditions (see Chapter 3). Note: ff KCRTS is not being used on a project, the WQ designflow may also be estimated using 64% of the 2- year 24-hour precipitation in the SBUH model." Downstream of detention: The full 2-year release rate from the detention facility. The KCRTS model will typically be used to compute the WQ design flow. When examining the peak flow rates associated with various runoff volumes, it was found that detained flows and undetained flows must be described differently. However, unlike peak flows, the KCRTS model computation of volume of runoff is unaffected by whether or not the runoff is detained. Therefore, facilities such as wetponds, which are sized by a simple volume -based approach that does not route flows through a detention pond, are the same size whether they precede or follow detention. Note that facilities which are sized based on volume and which include routing of flows through a detention pond, such as the detailed sand filter method, are significantly smaller when located downstream of detention, even though the same volume of water is treated in either situation. This is because the detention pond routing sequence stores peaks within the pond and releases them at a slow rate, reducing the size of the sand filter pond subsequently needed (the volume needed to store the peaks need not be provided again in the sand filter pond). Flow Volume to be Treated When water quality treatment is required pursuant to the core and special requirements of this manual, it is intended that a minimum of 95% of the annual average runoff volume in the time series, as determined with the KCRTS model, be treated. Designs using the WQ design flow (as discussed above) will treat this minimum volume. Treatable Flows As stated in Chapter 1, only runoff from pollution -generating surfaces must be treated using the water quality facility options indicated in the applicable water quality menu. Pollution -generating impervious 10 Fnlayson, 1990. Unpublished data from reconnaissance of Metro Park and Ride lot stormwater characteristics. The Department of Ecology WQ design flow is based on the flow predicted by the SBUH model for 64% of the 2-year 24-hour precipitation. This is roughly equivalent to the WQ design flows given here for the KCRTS model. 1998 Surface Water Design Manual 6-17 9/1/98 (SEE NOTE 5) 3-CART. CATCHBASIN - PLAN VIEW SCALE.' N.T.S. (D SQUARE ACC\ESSSS ER INLET GRATE CONCRETE �4" 0 OPENING COLLAR )I (SEE NOTE 6) ffl A I — UNDERDRAIN MANIFOLD 2' /2'—B" 3'-8" INSIDE INSIDE INSIDE 8'-5" I CLEANOUT OUTSIDE 8" 0 OUTLET PIPE J ACCESS PLUG (SEE NOTE 5) 3-CART. CATCHBASIN - SECTION VIEW A -A SCALE. N.T.S. 4iEET DATE JOY IREVISION STEEL CATCHBASIN STORMFILTER 1/3 PLAN AND SECTION VIEW 1 STANDARD DRAWING - 3-CARTRIDGE UNIT ]DESIGNED BY:.Ha DRAWN BY: �R DATE: PROJECT NO.: DRAWING NAME: --- 1/1112/04 k7{x7( C85f-3-S.-DWG RWG RECTANGULAR ACCESS COVER STORMFILTER CARTRIDGE (TYP) THE STOWA.TKR MANAGKWKNT StorniAter R U.S. PATENT No. 5,322,620, No. 5,707,527. No. 6,027,630, No. 5,624,576, AND OTHER U.S. AND FOREIGN PATENTS PENDING SMRMWATM MANAffNENT /NC. (800) 5484667 ALTERNATE PIPE LOCATION ") OUTLET PIPE DIAMETER VARIES INLET PIPE DIAMETER VARIES -HOPE FLOW DIFFUSER ORIFICE BOX PE FLOW DUCT (TYP) A STORMGATE SEPARATOR 1100 - PLAN VIEW _, SCALE. N.T.S. 30'0 SMI MANHOLE TO GRADE STORMGATO ALL INLET OUTLET FRAME STORMGATE SEPARATOR 1100 - SECTION VIEW SCALE. N.T.S. SHEET DATE BY MG ADDED FLOW STORMGATE SEPARATOR 1100 1/2 PLAN AND SECTION VIEW STANDARD DRAWING SWMWWAm=v 1 DATE: PROJECT NO.: DRAWING FILE NAME. A NA i ill N T / III C . ESIGNED BY. M_ DRAWN BY: n�c 2 25 ❑3 Xxxx SG51900.DWG (800J5484667 GENERAL NOTES 1.) STORMGATE SEPARATOR BY STORMWATER MANAGEMENT INC., PORTLAND, OREGON 300/548-4667. 2.) PRECAST CONCRETE VAULT TO BE CONSTRUCTED IN ACCORDANCE WITH ASTM C857 AND C858. 3.) INLET AND OUTLET PIPING TO BE SPECIFIED BY ENGINEER AND PROVIDED BY CONTRACTOR. 4.) PRECAST STORMGATE SEPARATOR EQUIPPED WITH EITHER CORED OPENINGS OR KNOCKOUTS AT INLET/OUTLET LOCATION. 5.) SEE PRECAST STORMGATE SEPARATOR DATA BLOCK FOR MODEL NUMBER, ORIFICE BOX CONFIGURATION, AND WEIR SETTING. 6.) CONTRACTOR TO ADJUST WEIR TO DESIGN ELEVATION. WHEN SETTING SCREWS ON WEIR PLATE DO NOT EXCEED 5.0 FT-LBS TOURQUE. SEAL WEIR WITH SILICONE SEALANT AFTER FINAL ADJUSTMENT. 7.) ALL STORMGATE SEPARATORS REQUIRE REGULAR MAINTENANCE REFER TO OPERATION AND MAINTENANCE GUIDELINES FOR DETAILS. B.) DETAIL REFLECTS DESIGN INTENT ONLY. ACTUAL VAULT DIMENSIONS AND CONFIGURATION WILL BE SHOWN ON THE PRODUCTION SHOP DRAWING. STORMGATE SEPARATOR" DATA SGS MODEL NUMBER 1100 WATER QUALITY FLOW RATE (CFS) xxx PEAK FLOW RATE (CFS) xxx I.E. MATERIAL DIAMETER INLET PIPE #1 xxx xxx xxx INLET PIPE #2 OUTLET PIPE xxx xxx xxx ORIFICE BOX OPENINGS: NUMBER SIZE 2 3" VAULT DIMENSIONS (FT X FT) 6 x 10 RIM ELEVATION xxx WEIR ELEVATION xxx TOP OF BAFFLE WALL ELEVATION xxx TRANSFER HOLE ELEVATION xxx FLOOR ELEVATION xxx THE STORMGATE SEPARATOR' TYPICAL SIZING TABLE MODEL NUMBER STORAGE CAPACITY (US Gal.) OIL CAPACITY (US Gal.) SEDIMENT CAPACITY (US Gal.) VAULT DIMENSIONS (FT X FT) DEPTH BP O (FEET) ORIFICE BOX OF OR&I NO IFCES (IN —NO.) SGS 1100 1045 180 180 6 X 10 4.0 3"-2 SGS 1400 1353 180 180 6 X 10 5.0 3"-3 SGS 2000 2013 180 180 6 X 12 5.7 4"-2 SGS 2800 2745 360 360 6 X 12 7.7 5"-2 SGS 3300 3232 360 360 8 X 16 4.5 5"-2 SGS 4200 4125 360 360 8 X 16 5.8 5"-3 SGS 5500 5522 597 597 8 X 16 7.7 5"-3 SGS 6700 6705 628 628 8 X 18 8.1 6"-3 SGS 8200 8157 838 838 8 X 18 9.8 6"-3 SHEET IDATE BY REVISION STORMGATE SEPARATOR 1 100 2/2 PLAN AND SECTION VIEW STANDARD DRAWING $WRMWM 2 DATE: PROJECT NO.: DRAWING FILE NAME: YANA■ffAMENT INC. )ESIGNED BY:� DRAWN BY: 2/25/03 xXXx SGS1100.DWG (800J548-4667 Sizing the StormGate Separator 2. Size the StormGate Separator system using Table 1 below. a. Locate the water quality flow rate for your site. Important: To optimize your StormGate Separator system, select the model with a "Suggested flow rate" closest to your water quality flow rate. The "Suggested flow rate" is based on an optimized six -minute residence time. b. Find the corresponding StormGate Separator model number in the same table row where you found your flow rate. The model number and corresponding dimensions make up your StormGate Separator size. Table 1. StormGate Separator sizings MODEL VAULT TOTAL SEDIMENT OIL DEPTH SUGGESTED MAXIMUM NUMBER DIMENSIONS STORAGE STORAGE STORAGE BELOW FLOW RATE FLOW RATE (FT X FT) CAPACITY CAPACITY CAPACITY INLET PIPE 6-min residence 4-min residence US GAL US GAL US GAL FT tC.FS-}_ (CFS) 8t3S 4�IOORV `:, _ ;,6 x 81045 180 '18D ., , 5.9 0.3=. SGS 1400-V 6 x 12 1353 180 180 4.5 Q:44 0.65 SGS 2000-V 6 x 12 2013 180 180 5.7 0.68 1.02 SGS 2800-V 6 x 12 2745 360 360 7.7 0.89 1.33 SGS 3300-V 8 x 16 3232 360 360 4.6 1.07 1.60 SGS 4200-V 8 x 16 4125 360 360 5.8 1.40 2.10 SGS 5500-V 8 x 16 5522 597 597 7.7 1.83 2.74 SGS 6800-V 8 x 18 6705 628 628 7.1 2.26 3.39 SGS 8200-V 8 x 18 8157 838 838 8.6 2.72 4.08 Sizing example for the StormGate Separator: 1. Assume that a site has a Qjree of 0.65 cis. 2. Determine the StormGate Separator size by locating the flow rate in Table 1. Answer: For a site with a flow rate of 0.65 cis, the StormGate Separator SGS 20004, whicHs housed in a 6 x 12 vault, is required to achieve 6 minutes of residence time. Integrating the StormGate Separator into your site plans I Once you have sized your StormGate Separator, you can begin integrating it into your site plans. Receiving a cost estimate'1 Fe, 51 Before you begin working with your site plans, you can receive a cost estimate for the StormGate Separator from Stormwater Management based on the information that you provide about your site on your Project Information Sheet and based on the information about the StormGate Separator that you have sized. Stormwater Management can also provide you with a maintenance cost estimate upon request. Important: This is an estimate only, not a formal quote. Costs will vary with final depth and project location. SGS-2 T Determining the number of StormFilter cartridges Determining the number of StormFilter cartridges _ I The number of filter cartridges that you must use in your StormFilter system depends on agency requirements, the amount of stormwater runoff from your site that must be treated, pollutant loading to your system, and certain site -specific characteristics. Your local jurisdictional agency usually determines the requirements for treating runoff in your area. Typically your agency will specify one of two primary design methods, a flow -based method or a voiume-based method, that you should use to determine the amount of runoff that must be treated. If you do not know what the required method is in your area, contact the Stormwater Management Engineering Department at (800) 548-4667, and they will assist you with determining this information. Use the flow chart below to identify the set of calculations that you should use for the design method identified by your local jurisdictional agency. Step-by-step instructions for completing these calculations can be found on the following pages. Use design calculations for detention, p. SF-8 Use design calculations highly impervious sites, p. SF-5 Establish agency guideffnes Flow�based design method Volume -based design method Use volume -based design calculations, Is the p. SF-11 5tormFUter downstream of detention? Tie] fs the site highly impervious (�:70%)? NO Use design calculations for pervious sites, p. SF-6 Z p}f s t o rrnwa t enncc.., c -o;ri SF-3 Using the flow -based method Determining the number of cartridges for a highly impervious site To determine the number of StormFilter cartridges needed for a highly impervious site (>_ 70% impervious): 1. Calculate the peak flow rate from the water quality storm (Qtr,,t) for your site using the approved hydrologic models established by your local agency. If there are no agency guidelines, we recommend using the Santa Barbara Urban Hydrograph Method. 2. Calculate the number of cartridges required to treat the peak water quality flow rate (Nfl,„) for your site. Nflow = Qtreat (449 gpwars / Q.rt gprrdcart) Notes: • Assume Qcart = 15 gpmlcart, which is the maximum flow rate that an individual cartridge can treat. In some areas or situations, cartridges with a flow rate other than 15 gpm may be required, resulting in a different Qcart value. • If the number of cartridges is not a whole number, round the number of cartridges up to the next whole number. Example of cartridge number suing for a highly impervious site: 1. Assume that a site has a peak flow rate of 0.44 ds. 2. Determine the number of cartridges required to treat this flow rate.. * Ntk„ = (0.44 crs)(449 gprrdds / 15 gpmlcart) = 13.2 carwdps Answer: Rounding up to the next whole number, the number of required cartridges is 14. SF-5 �1/ SATE CON ✓&N- //WC� 5YST67Ai NORTHSHORE PLAZA RETAIL CENTER Our Job 203517.10 BACKWATER COMPUTER PROGRAM FOR PIPES Pipe data from file:onsite.bwp Surcharge condition at intermediate junctions Tailwater Elevation:378.67 feet Discharge Range:0.5 to 5. Step of 0.5 [cfs] Overflow Elevation:393.4 feet Weir:NONE Upstream Velocity:3. feet/sec JUNCTION BOX TO *SDMH (IN SW 340'�b St) *BEGIN OFFSITE CONVEYANCE CALCULATIONS SEPARATE (DIFFERENT DATUM) PIPE NO. 1: 15 LF - 1211CP @ 13.07% OUTLET: 377.67 INLET: 379.63 INTYP: 1 JUNC NO. 1: OVERFLOW -EL: 383.79 BEND: 90 DEG DIA/WIDTH: 2.5 Q-RATIO: 0.00 Q(CFS) HW(FT) HW ELEV. * N-FAC DC DN TW DO DE HWO HWI ******************************************************************************* 0.50 0.35 379.98 * 0.012 0.30 0.13 1.00 1.00 0.30 ***** 0.35 1.00 0.57 380.20 * 0.012 0.43 0.19 1.00 1.00 0.43 ***** 0.57 1.50 0.77 380.40 * 0.012 0.52 0.23 1.00 1.00 0.52 ***** 007 2.00 0.96 380.59 * 0.012 0.61 0.26 1.00 1.00 0.61 ***** 0.96 2.50 1.16 380.79 * 0.012 0.68 0.29 1.00 1.00 0.68 ***** 1.16 3.00 1.36 380.99 * 0.012 0.75 0.32 1.00 1.00 0.75 ***** 1.36 3.50 1.67 381.30 * 0.012 0.80 0.35 1.00 1.00 0.80 ***** 1.67 4.00 2.04 381.67 * 0.012 0.85 0.37 1.00 1.00 0.85 ***** 2.04 4.50 2.45 382.08 * 0.012 0.89 0.40 1.00 1.00 0.89 ***** 2.45 5.00 2.92 382.55 * 0.012 0.92 0.42 1.00 1.00 0.92 ***** 2.92 CAPACITY IS MORE THAN 5 CFS. EX CB 1 (TIE-IN) TO JUNCTION BOX PIPE NO. 2: 21 LF - 12"CP @ 0.24% OUTLET: 379.63 INLET: 379.68 INTYP: 1 JUNC NO. 2: OVERFLOW -EL: 384.80 BEND: 90 DEG DIA/WIDTH: 2.5 Q-RATIO: 0.00 Q(CFS) HW(FT) HW ELEV. * N-FAC DC DN TW DO DE HWO HWI ******************************************************************************* 0.50 0.48 380.16 * 0.012 0.30 0.36 0.35 0.35 0.36 0.48 0.42 1.00 0.71 380.39 * 0.012 0.43 0.52 0.57 0.57 0.56 0.71 0.63 1.50 0.94 380.62 * 0.012 0.52 0.68 0.77 0.77 0.76 0.94 0.83 2.00 1.20 380.88 * 0.012 0.61 0.90 0.96 0.96 0.97 1.20 1.03 2.50 1.55 381.23 * 0.012 0.68 1.00 1.16 1.16 1.20 1.55 1.22 3.00 1.94 381.62 * 0.012 0.75 1.00 1.36 1.36 1.43 1.94 1.42 3.50 2.48 382.16 * 0.012 0.80 1.00 1.67 1.67 1.79 2.48 1.74 4.00 3.11 382.79 * 0.012 0.85 1.00 2.04 2.04 2.21 3.11 2.10 4.50 3.82 383.50 * 0.012 0.89 1.00 2.45 2.45 2.69 3.82 2.52 5.00 4.62 384.30 * 0.012 0.92 1.00 2.92 2.92 3.22 4.62 2.98 CAPACITY IS MORE THAN 5 CPS. SDCB 2 TO EX CB 1 PIPE NO. 3: 85 LF - 12"CP @ 2.11% OUTLET: 379.68 INLET: 381.47 INTYP: 1 JUNC NO. 3: OVERFLOW -EL: 387.00 BEND: 90 DEG DIA/WIDTH: 4.0 Q-RATIO: 0.00 Q(CFS) HW(FT) HW ELEV. * N-FAC DC DN TW DO DE HWO HWI ******************************************************************************* 0.50 0.41 381.88 * 0.012 0.30 0.21 0.48 0.48 0.30 ***** 0.41 1.00 0.63 382.10 * 0.012 0.43 0.29 0.71 0.71 0.43 ***** 0.63 1.50 0.82 382.29 * 0.012 0.52 0.36 0.94 0.94 0.52 ***** 0.82 2.00 1.02 382.49 * 0.012 0.61 0.42 1.20 1.20 0.61 ***** 1.02 2.50 1.21 382.68 * 0.012 0.68 0.47 1.55 1.55 0.68 ***** 1.21 3.00 1.41 382.88 * 0.012 0.75 0.53 1.94 1.94 0.75 ***** 1.41 3.50 2.08 383.55 * 0.012 0.80 0.58 2.48 2.48 1.39 2.08 1.73 4.00 3.13 384.60 * 0.012 0.85 0.63 3.11 3.11 2.23 3.13 2.09 4.50 4.32 385.79 * 0.012 0.89 0.68 3.82 3.82 3.19 4.32 2.51 5.00 5.65 387.12 * 0.012 0.92 0.74 4.62 4.62 4.26 5.65 2.97 CAPACITY IS MORE THAN 5 CFS. SDCB 3 TO SDCB 2 PIPE NO. 4: 167 LF - 12"CP @ 1.00% OUTLET: 381.47 INLET: 383.14 INTYP: 1 JUNC NO. 4: OVERFLOW -EL: 388.50 BEND: 90 DEG DIA/WIDTH: 4.0 Q-RATIO: 0.00 Q(CFS) HW(FT) HW ELEV. * N-FAC DC DN TW DO DE HWO HWI ******************************************************************************* 0.50 0.41 383.55 * 0.012 0.30 0.25 0.41 0.41 0.30 ***** 0.41 1.00 0.63 383.77 * 0.012 0.43 0.35 0.63 0.63 0.43 ***** 0.63 1.50 0.83 383.97 * 0.012 0.52 0.44 0.82 0.82 0.52 ***** 0.83 2.00 1.02 384.16 * 0.012 0.61 0.52 1.02 1.02 0.61 ***** 1.02 2.50 1.22 384.36 * 0.012 0.68 0.59 1.21 1.21 0.68 ***** 1.22 3.00 1.42 384.56 * 0.012 0.75 0.67 1.41 1.41 0.75 ***** 1.42 3.50 2.47 385.61 * 0.012 0.80 0.75 2.08 2.08 1.78 2.47 1.73 4.00 4.15 387.29 * 0.012 0.85 0.86 3.13 3.13 3.25 4.15 2.10 **************** OVERFLOW ENCOUNTERED AT 4.50 CFS DISCHARGE ***************** ******** OVERFLOW CONDITIONS CALCULATED ASSUMING SURCHARGE CONDITIONS ********* 4.50 6.05 389.19 * 0.012 0.89 1.00 4.32 4.32 4.92 6.05 2.51 5.00 8.19 391.33 * 0.012 0.92 1.00 5.65 5.65 6.79 8.19 2.98 SDCB 4 TO SDCB 3 PIPE NO. 5: 147 LF - 1211CP @ 1.00% OUTLET: 383.14 INLET: 384.61 INTYP: 1 JUNC NO. 5: OVERFLOW -EL: 393.00 BEND: 90 DEG DIA/WIDTH: 4.0 Q-RATIO: 0.00 Q(CFS) HW(FT) HW ELEV. * N-FAC DC DN TW DO DE HWO HWI ******************************************************************************* 0.50 0.41 385.02 * 0.012 0.30 0.25 0.41 0.41 0.30 ***** 0.41 1.00 0.63 385.24 * 0.012 0.43 0.35 0.63 0.63 0.43 ***** 0.63 1.50 0.83 385.44 * 0.012 0.52 0.44 0.83 0.83 0.52 ***** 0.83 2.00 1.02 385.63 * 0.012 0.61 0.52 1.02 1.02 0.61 ***** 1.02 2.50 1.22 385.83 * 0.012 0.68 0.59 1.22 1.22 0.68 ***** 1.22 3.00 1.46 386.07 * 0.012 0.75 0.67 1.42 1.42 0.79 1.46 1.42 3.50 2.90 387.51 * 0.012 0.80 0.75 2.47 2.47 2.21 2.90 1.73 4.00 5.15 389.76 * 0.012 0.85 0.86 4.15 4.15 4.26 5.15 2.10 4.50 7.72 392.33 * 0.012 0.89 1.00 6.05 6.05 6.58 7.72 2.51 5.00 10.58 395.19 * 0.012 0.92 1.00 8.19 8.19 9.18 10.58 2.98 CAPACITY IS MORE THAN 5 CFS. SDCB 5 TO SDCB 4 PIPE NO. 6: 29 LF - 12"CP @ 1.00% OUTLET: 384.61 INLET: 384.90 INTYP: 1 Q(CFS) HW(FT) HW ELEV. * N-FAC DC DN TW DO DE HWO HWI 0.50 0.30 385.20 * 0.012 0.30 0.25 0.41 0.41 0.30 ***** 0.27 1.00 0.48 385.38 * 0.012 0.43 0.35 0.63 0.63 0.43 ***** 0.48 1.50 0.67 385.57 * 0.012 0.52 0.44 0.83 0.83 0.52 ***** 0.67 2.00 0.91 385.81 * 0.012 0.61 0.52 1.02 1.02 0.77 0.91 0.85 2.50 1.22 386.12 * 0.012 0.68 0.59 1.22 1.22 1.06 1.22 1.03 3.00 1.64 386.54 * 0.012 0.75 0.67 1.46 1.46 1.35 1.64 1.21 3.50 3.29 388.19 * 0.012 0.80 0.75 2.90 2.90 2.84 3.29 1.49 4.00 5.80 390.70 * 0.012 0.85 0.86 5.15 5.15 5.17 5.80 1.83 **************** OVERFLOW ENCOUNTERED AT 4.50 CFS DISCHARGE ***************** 4.50 8.65 393.55 * 0.012 0.89 1.00 7.72 7.72 7.82 8.65 2.21 5.00 11.84 396.74 * 0.012 0.92 1.00 10.58 10.58 10.78 11.84 2.64 TUVCT/cyv Bk�u — C 12 0 E }�}4 ..... - - -_� `3 TYPE 2--W 7 1t �L _:a [:x= IE it car SW 3e0ss' roc r , �:: ° 1Y aes r 11cTFt+ucw VVXT Zil'V TP.O OF ' 51W E 3KS2 C&TtR :ffE -sopPTa 71' ♦ lE 1 CP E 3!4 1� \ E 1 PP S 3B52d LINE TD-W 512E �! f19M 700 tF Ub74 FTAT YY. 4� 1 as IE Ir :ME seeor JE fY Cnn E.N7.90' 1E IE r VC .3ftSV se7.os' \q4'• �\ m rxr � 5Ew [ ` � � C r PVC W rP10E E IY MS "�'C r'• R 'N '.' IE a GUAIL 31W LAW Om I D J ' IE tY CPP ME 30.56' [ r POC E 36L2W PE 12" RCM W 3l7.5r (ELBOW) C. y SOW I7B \\ e r� YU 1CV4 .i G: L 7i5:f MOCT 'e�� D�-S/TE VY5 T47-" Existing Conveyance Capacity North Shore Plaza Retail Center Job 203517.10 BACKWATER COMPUTER PROGRAM FOR PIPES Pipe data from file:runl.bwp Surcharge condition at intermediate junctions Tailwater Elevation:332.63 feet Discharge Range:3. to 20. Step of 0.5 [cfs] Overflow Elevation:398.45 feet Weir:NONE Upstream Velocity:9.9 feet/sec �s,99 PIPE NO. 1: 334 LF - 12"CP @ 5.99% OUTLET: 325.50 INLET: 345.50 INTYP: 1 JUNC NO. 1: OVERFLOW -EL: 354.10 BEND: 180 DEG DIA/WIDTH: 4.0 Q-RATIO: 1.00 Q(CFS) HW(FT) HW ELEV. * N-FAC DC DN TW DO DE HWO HWI ******************************************************************************* 3.00 1.37 346.87 * 0.012 0.75 0.39 7.13 7.13 0.75 ***** 1.37 3.50 1.68 347.18 * 0.012 0.80 0.43 7.13 7.13 0.80 ***** 1.68 4.00 2.03 347.53 * 0.012 0.85 0.46 7.13 7.13 0.85 ***** 2.03 4.50 2.44 347.94 * 0.012 0.89 0.49 7.13 7.13 0.89 ***** 2.44 5.00 2.89 348.39 * 0.012 0.92 0.52 7.13 7.13 0.92 ***** 2.89 5.50 3.39 348.89 * 0.012 0.94 0.55 7.13 7.13 0.94 ***** 3.39 6.00 3.94 349.44 * 0.012 0.96 0.58 7.13 7.13 0.96 ***** 3.94 6.50 4.53 350.03 * 0.012 0.97 0.61 7.13 7.13 0.97 ***** 4.53 7.00 5.17 350.67 * 0.012 0.98 0.65 7.13 7.13 0.98 ***** 5.17 7.50 5.86 351.36 * 0.012 0.99 0.68 7.13 7.13 0.99 ***** 5.86 8.00 6.60 352.10 * 0.012 0.99 0.71 7.13 7.13 0.99 ***** 6.60 8.50 7.38 352.88 * 0.012 0.99 0.75 7.13 7.13 3.33 7.19 7.38 **************** OVERFLOW ENCOUNTERED AT 9.00 CFS DISCHARGE ***************** ******** OVERFLOW CONDITIONS CALCULATED ASSUMING SURCHARGE CONDITIONS ********* 9.00 9.62 355.12 * 0.012 1.00 0.79 7.13 7.13 5.29 9.62 8.22 9.50 12.18 357.68 * 0.012 1.00 0.83 7.13 7.13 7.37 12.18 9.10 10.00 14.89 360.39 * 0.012 1.00 0.89 7.13 7.13 9.55 14.89 10.02 10.50 17.74 363.24 * 0.012 1.00 1.00 7.13 7.13 11.85 17.74 11.00 11.00 20.72 366.22 * 0.012 1.00 1.00 7.13 7.13 14.26 20.72 12.02 11.50 23.84 369.34 * 0.012 1.00 1.00 7.13 7.13 16.78 23.84 13.09 12.00 27.11 372.61 * 0.012 1.00 1.00 7.13 7.13 19.42 27.11 14.21 12.50 30.51 376.01 * 0.012 1.00 1.00 7.13 7.13 22.16 30.51 15.38 13.00 34.05 379.55 * 0.012 1.00 1.00 7.13 7.13 25.02 34.05 16.59 13.50 37.72 383.22 * 0.012 1.00 1.00 7.13 7.13 27.99 37.72 17.85 14.00 41.54 387.04 * 0.012 1.00 1.00 7.13 7.13 31.08 41.54 19.16 14.50 45.50 391.00 * 0.012 1.00 1.00 7.13 7.13 34.27 45.50 20.51 15.00 49.59 395.09 * 0.012 1.00 1.00 7.13 7.13 37.58 49.59 21.92 15.50 53.83 399.33 * 0.012 1.00 1.00 7.13 7.13 41.00 53.83 23.37 16.00 58.20 403.70 * 0.012 1.00 1.00 7.13 7.13 44.53 58.20 24.87 16.50 62.71 408.21 * 0.012 1.00 1.00 7.13 7.13 48.17 62.71 26.41 17.00 67.36 412.86 * 0.012 1.00 1.00 7.13 7.13 51.93 67.36 28.01 17.50 72.15 417.65 * 0.012 1.00 1.00 7.13 7.13 55.80 72.15 29.65 18.00 77.07 422.57 * 0.012 1.00 1.00 7.13 7.13 59.78 77.07 31.34 18.50 82.14 427.64 * 0.012 1.00 1.00 7.13 7.13 63.87 82.14 33.07 19.00 87.35 432.85 * 0.012 1.00 1.00 7.13 7.13 68.07 87.35 34.86 19.50 92.69 438.19 * 0.012 1.00 1.00 7.13 7.13 72.39 92.69 36.69 20.00 98.17 443.67 * 0.012 1.00 1.00 7.13 7.13 76.82 98.17 38.57 PIPE NO. 3: 320 LF - 1211CP @ 6.97% OUTLET: 369.10 INLET: 391.40 INTYP: 1 Q(CFS) HW(FT) HW ELEV. * N-FAC DC DN TW DO DE HWO HWI ******************************************************************************* 0.75 0.37 391.77 * 0.012 0.37 0.19 0.79 0.79 0.37 ***** 0.19 0.88 0.40 391.80 * 0.012 0.40 0.20 0.89 0.89 0.40 ***** 0.20 1.00 0.43 391.83 * 0.012 0.43 0.22 0.98 0.98 0.43 ***** 0.22 1.13 0.45 391.85 * 0.012 0.45 0.23 1.08 1.08 0.45 ***** 0.23 1.25 0.48 391.88 * 0.012 0.48 0.24 1.17 1.17 0.48 ***** 0.24 1.38 0.50 391.90 * 0.012 0.50 0.25 1.25 1.25 0.50 ***** 0.25 1.50 0.52 391.92 * 0.012 0.52 0.26 1.36 1.36 0.52 ***** 0.26 1.63 0.55 391.95 * 0.012 0.55 0.28 1.51 1.51 0.55 ***** 0.28 1.75 0.57 391.97 * 0.012 0.57 0.29 1.67 1.67 0.57 ***** 0.29 1.88 0.59 391.99 * 0.012 0.59 0.30 1.84 1.84 0.59 ***** 0.30 2.00 0.61 392.01 * 0.012 0.61 0.31 2.03 2.03 0.61 ***** 0.31 2.13 0.63 392.03 * 0.012 0.63 0.31 2.22 2.22 0.63 ***** 0.31 2.25 0.65 392.05 * 0.012 0.65 0.32 2.43 2.43 0.65 ***** 0.32 2.38 0.66 392.06 * 0.012 0.66 0.33 2.65 2.65 0.66 ***** 0.33 2.50 0.68 392.08 * 0.012 0.68 0.34 2.88 2.88 0.68 ***** 0.34 2.63 0.70 392.10 * 0.012 0.70 0.35 3.13 3.13 0.70 ***** 0.35 2.75 0.72 392.12 * 0.012 0.72 0.36 5.44 5.44 0.72 ***** 0.36 2.88 0.73 392.13 * 0.012 0.73 0.37 9.33 9.33 0.73 ***** 0.37 3.00 0.75 392.15 * 0.012 0.75 0.38 13.40 13.40 0.75 ***** 0.38 3.13 0.76 392.16 * 0.012 0.76 0.39 17.65 17.65 0.76 ***** 0.39 3.25 2.04 393.44 * 0.012 0.78 0.39 22.06 22.06 2.04 1.02 0.39 3.38 6.80 398.20 * 0.012 0.79 0.40 26.65 26.65 6.80 5.82 0.40 **************** OVERFLOW ENCOUNTERED AT 3.50 CFS DISCHARGE ***************** 3.50 11.74 403.14 * 0.012 0.80 0.41 31.41 31.41 11.74 10.81 0.41 3.63 16.87 408.27 * 0.012 0.82 0.42 36.35 36.35 16.87 15.98 0.42 3.75 22.18 413.58 * 0.012 0.83 0.42 41.46 41.46 22.18 21.33 0.42 3.88 27.66 419.06 * 0.012 0.84 0.43 46.74 46.74 27.66 26.86 0.43 4.00 33.33 424.73 * 0.012 0.85 0.44 52.19 52.19 33.33 32.57 0.44 4.13 39.18 430.58 * 0.012 0.86 0.45 57.82 57.82 39.18 38.47 0.51 4.25 45.20 436.60 * 0.012 0.87 0.46 63.62 63.62 45.20 44.54 0.60 4.38 51.41 442.81 * 0.012 0.88 0.46 69.60 69.60 51.41 50.80 0.70 4.50 57.79 449.19 * 0.012 0.89 0.47 75.74 75.74 57.79 57.24 0.80 4.63 64.36 455.76 * 0.012 0.90 0.48 82.06 82.06 64.36 63.86 0.90 4.75 71.10 462.50 * 0.012 0.91 0.48 88.56 88.56 71.10 70.66 1.00 4.88 78.03 469.43 * 0.012 0.92 0.49 95.22 95.22 78.03 77.64 1.11 5.00 85.14 476.54 * 0.012 0.92 0.50102.06102.06 85.14 84.81 1.22 lviap vuLNut rage i or i �LVJ Home I News I Services I Comments By visiting this and other King County web pages, you expressly agree to be bound by terms and conditions of the site. 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APPENDIX D Geotechnical Report MAH-UU-04 MUN U3:j2 FM HELIX ARCH1.1'EUNHE FAX:2539226499 PAGE 2 z.y Z sway_ y f ZA Zpper Zeman Associates, Inc. Geotechnical and Environmental Consulting J-1781 January 20, 2004 4"'' Mr. Alex Spearman 320 East 132"d Street, Suite 507 Tacoma, Washington98404 t > Subject: Subsurface Exploration and Geotechnical Engineering Evaluation Retail Site �} 34029 Hoyt Load SW Federal Way, Washington Dear Mr. Spearman: Zipper Zeman Associates, Inc. (ZZA) has completed a geotechnical evaluation for the proposed retail development at 34029 Hoyt Road SW in Federal Way, Washington. This report presents the results of our subsurface exploration and geotechnical engineering study relative to foundation and construction considerations for the proposed project. Our services were Ij completed in general accordance with our. proposal, P-2166, as authorized on December 30, 2004. The purpose of the study was to establish general surface and subsurface conditions at the . site from which conclusions and recommendations regarding foundation and floor slab design, pavements, and construction considerations could be formulated. The scope of our services included a visual reconnaissance, field explorations, geotech-nical engineering analyses, and I preparation of this report. Our scope of services did not include sampling or testing of soil or water for regulated environmental contaminants. � SITE AND P1tOJECT DESCWPTION The site is located on the west side of the street with..a Chevron station and convenience market to the north. The neighboring areas to the south and west of the site are residential developments. The site currently contains an abandoned single -story house and separate garage. We understand that development plans include construction of an approximate 4,100 square foot retail building with associated paved ingress/egress and parking areas. We anticipate that conventional spread footings will be used for foundation support _with concrete slab -on - grade floors. SITE CONDITIONS y The site conditions for the project were evaluated by excavating three test pits on January 9, 2004. The approximate test pit locations are shown on Figure 1, Site and Exploration Plan. General surface and subsurface conditions are described below, with more detailed subsurface conditions presented on the attached test pit logs. y 5113 Pacific Highway East, #1-1), Fife, WA 98424 (253) 896-5082 Fax: (253) 896-5086 ` 03/08/04 MON 15:42 [TX/RX NO 76401 <- MAh-Ud-U4 MUA UJ:jj YM HELIX AHChIlIC1URE FAX:2539226499 PAGE 3 -7 w ZZA Hoyt Road Retail Federal Way, Washington J-1781 cur January 20, 2004 Page 2 Surface Conditions The surface of the site is relatively level and is covered with grass, brush, and short trees. y An existing turn -around asphalt driveway is located in the eastern portion of the site and connects with Hoyt Road. No standing water was observed while we were on site. Subsurface Conditions .Soil and groundwater descriptions presented in this report are based on the subsurface conditions encountered at the specific test exploration locations on the site. Variations in subsurface conditions may exist between the test locations and the nature and extent of variations -' may not become evident until construction. If variations then appear, it may be necessary to reevaluate the recommendations of this report. In general, the subsurface conditions observed in the test pits were consistent across the site. Grass was observed covering the surface at the test pit locations. In test pits TP-1 and TP-2, R y loose silty sand with some roots and trace gravel (topsoil) was observed to depths of 2 feet and 1.2 feet, respectively. In test pit TP-3, fill consisting of loose, gravelly silty sand with some roots 1 and was observed to a depth of approximately 3 feet, Underlying the topsoil and fill in all three test pits, was medium dense to dense, sand and gravel with variable silt. These granular soils extended to the bottom of the test pits between 5.5 and 10 feet below the surface. t., r Groundwater Perched groundwater was observed in the test pits near the topsoil or fill contact with the native medium dense sand and gravel, and at approximately 7.5 feet in test pit TY-1. This perched groundwater is anticipated to be present through the wet seasons of the year. The permanent groundwater table is at depths below the bottom of the deepest test pits. It should be y expected that groundwater conditions will vary due to seasonal precipitation patterns, site utilization, and other on- and off site factors. Seismic Criteria According to the Seismic .Zane Map of the United States contained in the 1997 Uniform j fhildiri6 Code, the project site lies within Seismic 'Lone 3. Based on soil conditions encountered in the test pit excavation at the site, the subsurface site conditions are interpreted to correspond to a seismic soil profile type Se as defined by Table 16-J of the 1997 Uniform Building Code. Soil j _r profile type S. applies to an average soil profile within the top 100 feet consisting predominantly of very dense soil characterized by Standard Penetration 'Pest blow counts greater than 50, a shear wave velocity of 1,200 to 2,500 feet per second, and an undrained shear strength greater jw� than 2,000 psf. -r 1-1781,012004 `1 03/08/04 MON 15:42 [TX/RX NO 76401 MAR-08-04 MUN 03:33 FM HELIX ARCHITECTURE FAX:2539226499 PAGE 4 =' ZZA Hoyt Road Retail y, Federal Way, Washington . + 1-1781 ^ � January 20, 2004 Page 3 c Liquefaction Potential Soil liquefaction is a condition wherein loose granular soils located below the ground water surface loose strength during ground shaking associated with an earthquake. Due to the ~1 V overall dense condition of the native soils and depth of the permanent groundwater table, the risk .. of liquefaction at this site is low. CONCLUSIONS AND RECOMIVIENDA170NS -Based on the subsurface conditions observed in the test pit, the site is considered suitable for construction of the planned structure. The following recommendations are based upon the subsurface conditions encountered at the test pit locations and our understanding of project plans. However, -it should be noted that the subsurface conditions across the site may vary, and can , change with time. Therefore, the specific site preparation operations will depend upon the weather and soil conditions encountered at the time of construction. We anticipate that final finish grade elevations will be near existing or street grades. We recommend that building foundations, floor slabs, and pavement sections be supported on the medium dense to dense sand and gravel soils observed in the test pits, or on a zone of structural fill that extends down to these competent soils. Site Preparation We recommend that the topsoil and existing loose fill be removed from building and pavement areas. This material can be exported from the site, or reused in landscaped or non- ' structural areas. Based on the subsurface conditions observed in the test pits, this will require on the order of 1 to 3 feet of removal of existing topsoil and/or fill. The exposed subgrade should consist of the native medium dense to dense sand and gravel. Following removal of the topsoil, existing fill, • and any deleterious material, we recommend that the exposed subgrade surface be proofrolled using a heavy truck or vibratory compactor. The purpose of proofrolling/compacti-ng is to detect the presence of unsuitable or - disturbed soils, and to provide a suitable base for additional structural fill (if required) and/or support of the building elements and pavement sections_ Proofrolling efforts should result in the subgrade surface being in a firm and non -yielding condition. If unsuitable or disturbed soils are T� encountered, they should be removed and replaced with compacted structural fill in accordance with the recommendations in this report for structural fill. We recommend that site preparation procedures including proofrolling be monitored by Zipper Zeman Associates, Inc. J f The contractor should protect the exposed subgrade soils in the building and pavement areas from disturbance during wet site conditions. Towards this end, it may be prudent to spread a Working surface of clean, well -graded sand and gravel or crushed rock over the exposed subgrade. 'We recommend that provisions be used to direct storm runoff away from building and utility excavations_ :y i-1781,O12ooa 03/08/04 NON 15:42 [TX/RX NO 76401 I\�J 4 Y r' t're MAR-08-04 MON 03:33 PM Z ZA HELIX ARCHITECTURE FAX:2539226499 PAGE 5 Structural Fill Materials Hoyt Road Retail Federal Way, Washington 1-1781 January 20, 2004 Page 4 The suitability of soils for structural fill use depends primarily on the gradation and moisture content of the soil when it is placed. As the amount of fines (that soil fraction passing the U.S. No. 200 sieve) increases, soil becomes increasingly sensitive to small changes in moisture content and adequate compaction becomes more difficult, or impossible, to achieve. Generally, soils containing more than about 5 percent fines by weight (based on that soil fraction passing the U.S. No. 4 sieve) cannot be compacted to a firm, non -yielding condition when the moisture content is more than a few percent from optimum, The optimum moisture content is that which yields the greatest soil density under a given compactive. effort. At the time of the subsurface evaluation, the site soils disclosed by the explorations appeared to have moisture contents substantially above their estimated optimum moisture content relative to their possible use as structural fill. Most of the site soils contain more than 5 percent fines, Consequently, use of the on -site soil as structural fall will require that the soils be dried back to eompaetable moisture contents and strict control of the moisture content be maintained during the grading process. Selective drying of over -optimum moisture soils may be achieved by scarifying or windrowing surficial materials during extended periods of dry weather. We recommend that all import structural fill placed during extended dry weather periods consist of material which meets the specifications for Common Borrow as described in Section 9-03.14(1) of the 2002 Washington State Department of Transportation Specifications for Road, Bridge, and Municipal Construction. (Publication M 41-10). The Common Borrow should be placed in horizontal lifts not exceeding 10 inches in loose thickness. Each lift must be conditioned to the proper moisture content and uniformly compacted to a firm, unyielding condition using mechanical equipment. Common Borrow fill must be protected from disturbance if exposed to wet conditions after placement. During wet weather, or for back ill on a wet subgrade or in areas exposed to groundwater seepage or surface water flow, import soil suitable for compaction in wet conditions should be provided. imported fill for use in wet conditions should generally conform to specifications for Gravel Borrow as described in Section 9-03.14(1) of the 2002 Washington State Department of Transportation Specifications for Road, Bridge, and Municipal Construction (Publication M 41- 10), with the modification that a maximum of 5 percent by weight shall pass a U.S. No. 200 sieve. u' It should be noted that the placement of structural fill is, in many cases, weather- dependent. Delays due to inclement weather are common,, even when using select granular fill. f We recommend that site grading and earthwork be scheduled for the drier months -1 G✓ J-178l,o L 2004 03/08/04 MON 15:42 [TX/RX No 76401 -C, MAH-Ud-Uq MUN U:M PM HELIX AHCHITECTUHE FAX:2539226499 PAGE 6 ZA Structural Fill Placement Hoyt Road Retail Federal Way, Washington J-1781 January 20, 2004 Page 5 We recommend that all structural fill be placed in lifts not exceeding 10 inches in loose measure. Structural fill material should be compacted to a minimum of 95 percent of the ASTM D-1557 test method in building and pavement areas. Fill should also be compacted to at least 95 percent of the maximum dry density per the ASTM D-1557 test method in utility trenches that underlie paved areas. Non-structural fill, such as in landscaping areas, need only be compacted to the extent required for trafficability of construction equipment. Final structural fill slopes should be no steeper than 2:1 (H: V). We recommend that all fill procedures include maintaining grades that promote drainage and do not allow for ponding within the fill area. The contractor should protect structural fill subgrades from disturbance during wet weather. In the event of rain during structural fill placement, the exposed fill surface should be allowed to dry prior to placement of additional fill. Alternatively, the wet soil can be removed and wasted. We recommend that consideration be given to protecting haul routes and other high traffic areas with free -draining granular fill material (i.e. sand and gravel containing less than 5 percent fines) or quarry spalls to reduce the potential for disturbance to the structural fill during inclement weather. We recommend that structural fill placement be observed and tested by a representative from our firm to determine that suitable compaction is being achieved, Spread Footings We recommend that all subgrade for support of spread footings be prepared as described in the Site Preparation and Structural Fill sections of this report. We recommend that footings for the building be supported on the native medium dense to dense sand and gravel, or on zone of structural fill above these competent soils. The structural fill, and the upper foot of exposed native soil subgrades, should be compacted to at least 95 percent of the maximum dry density per the ASTM D-1557 test method. The depth of embedment below lowest adjacent finished grade for all exterior and interior footings should be at least 18 inches and 12 inches, respectively. We recommend a minimum footing width of 18 inches for continuous wall footings and- 24 inches for isolated !; column footings, For footings designed and constructed according to the above criteria, we recommend an allowable bearing pressure of 2,500. pounds per square foot. This value applies to ' the total of all dead plus long-term live loads, exclusive of the weight of the footing and any overlying backfill. This value may be increased by one-third when considering wind or seismic = loads. We estimate that the total settlement of foundation members founded within the medium h_. dense to dense sand and gravel, or on a zone of structural fill prepared as described above will be - less than 1-inch. Differential settlement of foundations founded within the same soil type could approach 1/z inch. Settlements would occur rapidly as the loads are applied. Zones of 3-1781,012004 1 03/08/04 NON 15:42 ITX/RX NO 76401 MAH-08-04 MON 03:34 PM HELIX ARCHITECTURE FAX:2539226499 PAGE 7 Hoyt Road Retail Federal Way, Washington ]-1781 January 20, 2004 Page 6 inadequately compacted structural fill, or loose or disturbed soils not removed from footing excavations prior to pouring concrete, may result in increased settlement. Lateral loads applied to the footings could be resisted by a combination of passive earth pressure and frictional sliding resistance. We recommend that an allowable equivalent fluid weight of 250 pounds per cubic foot (pcf) be used for passive resistance. An allowable coefficient of friction equal to 0.35 could also be used along the base of the foundation. A factor of safety equal to at least 1.5 has been incorporated into these allowable values. Under no circumstances should the foundation elements be cast atop loose or soft soil, slough, debris, or surfaces bearing water. We recommend that a representative from our firm observe the condition of the foundation subgrade prior to placing concrete in order to verify that the bearing soils are undisturbed and that conditions are consistent with the recommendations contained within this report. Floor Slabs We understand that concrete slab -on -grade floors are planned. The subgrade to support the floor should be prepared in accordance with our previous site preparation recommendations. The slab -on -grade should be founded on either the medium dense to dense sand and gravel, or on a zone of structural fill compacted to at least 95 percent density (ASTM D 1557) that extends down to these competent soils. We recommend that the floor slab be underlain by at least 6 inches of clean, well -graded sand and gravel to function as a capillary break and working surface. The fines content of the capillary break material should be limited to 3 percent or less, when based on that soil fraction passing the U.S. No. 4 sieve. Above the capillary break, an impervious moisture barrier (Visqueen) should also be placed to provide additional protection against dampness above the capillary break. The impervious moisture barrier should be protected by two inches of fine, moist sand placed above the barrier_ The sand cover should provide protection for the membrane and should promote uniform curing of the slab concrete. The sand cover should be moistened and tamped prior to slab placement. Drainage Considerations Permanent site grades should be established so that water does not collect adjacent to the building. We recommend that the ground surface adjacent to the building be sloped to drain surface water away from the structure_ We recommend that perimeter footing drains with cleanouts be installed around the building. The drains should consist of a minimum 4-inch diameter perforated pipe embedded in at least a 24-inch wide envelope of clean, free -draining granular material containing less than 5 percent fines (material passing the U.S. No. 200 sieve). Footing drains should be directed toward J-1781,012004 03/08/04 MON 15:42 [TX/RX No 7640] MAR-08-04 MON 03:35 PM l ZZA 4(J HELIX ARCHI.1•ECTURE FAX:2539226499 PAGE 8 Hoyt Road Retail Federal Way, Washington 3-1781 January 20, 2004 Page 7 avpzonriate storm water drainage facilities. Roof drains should not be connected to the footing drains. Pavement Subgrade Preparation We recommend that new pavement subgrade areas be prepared as described in the Site Preparation section of this report. Soft, loose or otherwise unsuitable areas identified during proofxolling should be repaired as appropriate. New pavement areas should be supported on at least one foot of native gravelly sand or structural fill that has been compacted to a minimum of 95 percent of the maximum dry density per the ASTM D-1557 test method. We recommend that pavement subgrade areas be observed by a representative from our firm to assess the adequacy of subgrade conditions, and to identify areas needing remedial work. The recommended design pavement sections presented in the following paragraphs are based on the assumption that the existing subgrade soils will not be adversely disturbed by construction activities. A thicker pavement section will be required if the existing subgrade soils are excessively disturbed. The subgrade for pavement areas should be graded to provide positive drainage and reduce the potential for ponding of water below the pavement section. We recommend that the minimum design pavement section in automobile parking areas ' consist of 2-inches of Class B asphalt concrete over a minimum of 4 inches of crushed rock base course. In truck traffic areas and in entry drives subjected to repeat traffic, the thickness of Class B asphalt concrete and crushed rock base course should be increased to at least 3 and 6 inches, v respectively. The crushed rock base course should be compacted to at least 95 percent of the maximum dry density determined in accordance with the ASTM D-1557 test method. s •f Fv _ 1 CLOSURE .L, We have prepared this report for the exclusive use of Alex Spearman and Helix Architecture, P.S. for design and construction of the proposed retail facility at 34029 Hoyt Road SW in Federal Way, Washington. The data and report should be provided to prospective contrac- tors for bidding or estimating purposes, but our report, conclusions and interpretations should not be construed as a warranty of the subsurface conditions. The conclusions and recommendations presented in this report are based on the explorations accomplished for this study. The number, location, and depth of the explorations were completed within the site and scope constraints of the project to yield the information necessary to formulate our recommendations. If there are any changes in the loads, grades, J �y location or configuration of the proposed development, our firm should be notified so that we may confirm the geotechnical recommendations presented in this report, or modify these 1 y recommendations if appropriate. The plans for this project were in the preliminary stage at the time this report was written. Under the circumstances, it is recommended that we be provided the opportunity for general review of the project plans and specifications in order to confirm that the 1-1781,012004 03/08/04 MON 15:42 [TX/RX No 76401 MAH-UU-M MUN UJ:JS YM HELIX AHCHITECTUHE FAX:2539226499 PAGE 9 :r ZZA VA rA WIM Hoyt Road Retail Federal Way, Washington J-1781 January 20, 2004 Page 8 recommendations and design considerations presented in this report have been properly interpreted and implemented into the project design package:. The integrity and performance of foundation systems depend greatly on proper site preparation and construction procedures. Field judgement by a qualified engineer will be necessary in order to determine the adequacy of the foundation support systems. Therefore, because of our familiarity with the site soils, we recommend that Zipper Zeman Associates, Inc.: be retained to provide geotechnical engineering services during earthwork and foundation. construction. If variations in the subsurface conditions are observed at the time of construction, we would be able to provide additional geotechnical engineez'iug recommendations to the contractor and owner in a timely manner as the project construction progresses We trust this report meets your present needs. If you have any questions or if we can be of further assistance, please call. Respectfully submitted, Zipper Zeman Associates, Inc. Timothy H. Roberts, P.E., P.G Senior Engineer � John E. Zippe President IexP)Rds 1 22a / ,� Enclosures: Figure 1 — Site and Exploration Plan Appendix A -- Field Exploration Procedures and Logs and Laboratory Testing Procedures and Results cc: Bruce McKean - Helix Architecture 34781,012004 03/08/04 MON 15:42 [TX/RX NO 76401 MAR-08-04 MON 03:36 PM HELIX ARCHITECTURE - FAX:2539226499 PAGE 10 w RPM 0 04 of r .f EXPLANATION f=f =iffMfg — L I TP-1 TEST Prr NUMBER AND APPROXIMATE LOCATION NOTE: DRAWING NOT TO SCALE R&FERENcE: SITE PLAN TAUN FROM HELIX ARCHITECTURE FAX DA-rED 115/04 AND ZZA MEASUREMENTS. SITE AND EXPLORATION SKETCH ZIPPER ZEMAN ASSOCIATES, INC. Hoyt Road Retail Geotechnical and Environmental Consulting Federal Way, Washing2n 1. 5113 Pacific Highway East, # I -P Fife, Washington 98424 J-1781 9M) 896-5082 1 FIGURE I 03/08/04 MON 15:42 [TX/RX NO 76401 MAh-Ub-U4 MUN UJ:Jb FM HELIX Rhuftilhuiuht PRX:Y5J9226499 �7 Z ZA Zipper Zeman Associates Inc. Geotechnical and Environmental Consulting Cti J/ 1 APPENDIX A FIELD EXPLORATION PROCEDURES AND LOGS LABORATORY TESTING PROCEDURES AND RESULTS r 1 Our field explorations for this project included three test pits advanced on December 16, 2003. Approximate exploration locations are shown on the Site and Exploration Plan, Figure 1. Exploration locations were determined by measuring distances from existing site features with a tape relative to. a topographic map of the site. Exploration elevations were interpolated from contours on the referenced topographic plan. As such, the exploration, locations and elevations a' should be considered accurate to the degree implied by the measurement method. The following sections describe our procedures associated with the exploration. Descriptive. logs of the explorations are enclosed in this appendix. Test Pit Procedures uy Test pits were excavated with a rubber tired backhoe, operated by a contractor hired by the client. The test pits were continuously logged by a representative of Zipper Zeman Associates, Inc. The test pit logs presented in this appendix are based upon the excavation characteristics, cr observation of the samples secured, laboratory test results, and field logs. The various types of soils and the groundwater conditions are indicated as well as the depth where the soils or y characteristics of the soils changed. It should be noted that these changes may have been gradual, and if the changes were obscured, they were inferred. til _ J .A n A✓ k•� !'l y 5113 Pacific Highway.East, #1-P, Fife, WA 98424 (253) 896-5082 Fax: (253) 896-5086 03/08/04 MON 15:42 [TX/RX NO 76401 J MAH-UU-U4 MUN UJ:Jb YM PROJECT; Holt Road Retail X. Location: Federal Way, WA :T Depth}'{feet] Y 9 0.0-2.0 2.0-10.0 14 Depth feet 0.0-1.2 _ c.✓ 1.2-10.0 4y �r D th feett) ` ;. 0.0-3.0 t� 3.0-5.5 _ A LL HELIX AHUH1fEUTURE FAX:2539226499 JOB No. J-1781 I TEST PITS 1 • Test Pit TF-1 Material Descriiption Grass over loose, wet, dark brown to brown, silty SAND with some roots and trace gravel (Topsoil) Medium dense to dense, wet, mottled brown, silty gravelly SAND Test pit completed at 10 feet Heavy seepage observed at 2 feet and 7.5 feet at time of excavation No caving observed at time of excavation Test pit TP-2 Material Descri lion Grass over loose, wet, dark brown, silty SAND with some roots and trace gravel (Topsoil) Medium dense to dense, wet, mottled brown, gravelly silty SAND Test pit completed at 10 feet Severe seepage and iron oxide staining observed at 1 foot at time of excavation . No caving observed at time of excavation Test Pit TP-21 Material Descri lion Grass over loose, wet, brown, silty gravelly SAND (Fill) Medium dense to dense, wet, brown, sandy -GRAVEL with trace silt Vest pit completed at 5.5 feet Severe seepage and iron oxide staining observed at 3 feet at time of excavation No caving observed at time of excavation PAGE 12 PAGE 1 OF 1 Sample No. S-1 @ 1' S-2 @ 4' S-3 @ 9.5' Sample No. S-1 @ 1' S-2 @ 2' Sample No. S-1 @ 1,5' Zipper Zermatt Associates, Inc. TEST PIT LOG _ FIGURE 2_ Geoteehnical & Environmental Consulting Date Logged: 118/04 Logged by: JW 03/08/04 MON 15:42 [TX/RX NO 76401 MAH-U3-U4 MUN 03:37 FM HELIX AHUH11'ffI'URE FAX:2539226499 PAGE 13 Hoyt Road Retail Federal Way, Washington J-1781 January 20, 2004 Page A-2 LABORATORY TESTING PROCEDURES A series of laboratory tests were performed during the course of this study to evaluate the index and geotechnical engineering properties of the subsurface soils. Descriptions of the types of tests performed are given below. Visual Classification Samples recovered from the exploration locations were visually classified in the field during the exploration program. Representative portions of the samples were carefully packaged in moisture tight containers and transported to our laboratory where the field classifications were verified or modified as required. Visual classification was generally done in accordance with the Unified Soil Classification system. Visual soil classification includes evaluation of color, relative moisture content, soil type based upon grain size, and accessory soil types included in the sample. Soil classifications are presented on the exploration logs in Appendix A. Moisture Content Determinations Moisture content determinations were performed on representative samples obtained from the exploration in order to aid in identification and correlation of soil types. The determinations were made in general accordance with the test procedures described in ASTM: D-2216. The results are presented on the grain size analysis sheets. Grain Size Analysis A grain size analysis indicates the range in diameter of soil particles included in a particular sample. Grain size analyses were performed on representative samples in general accordance with ASTM D 422. The results of the grain size determinations for the samples were used in classification of the soils, and are presented in this appendix. J-1781,012004 T 03/08/04 MON 15:42 [TX/RX NO 76401 z. MHh-Ud-U4 MUN Uj:j'l fM hhL1X AHChl'1'ECTURE FAX:2539226499 PAGE; 14 z w as w _z LL 1— z W U w W a GRAIN SIZE ANALYSIS Test Results Summary ATDROMETER i 1000.000 100.000 10.000 1.000 0,100 0.010 0.001 PARTICLE SIZE IN MILLIMETERS Coarse Flne Coarse Medium Fine Slit Clay BOULDERS COBBLES GRAVEL SAND - FINE GRAINED Comments: Exploration Sample Depth (feet) Moisture (%) I Fines Description TP-3 S-1 1.6 14 17.8 silty gravelly SAND PROJECT ND: J-1781 PROJECT NAME: Zipper Zeman Associates. Inc. GATE pF TESTING: 11g104 Hoyt Rd. SW Retail Geotechnical and Enviroruuental Consulting 03/08/04 MON 15:42 [TX/RX NO 7640] i4 MUM U3: j I rm GRAIN SIZE ANALYSIS Test Results Summary T 0 .W m IL z LL F- Z W V w w a ntSLIA RAUhIlLUIUAL VRA:Z7J9216499 FRUE 17 1000.000 100,000 10.000 1.000 0.100 0.010 0.001 PARTICLE SIZE IN MILLIMETERS BOULDERS COBBLES Coarse Fine Coarse McEium Fine gilt Ctay GRAVEL SAND MNE GRAINED I Gamments: Exploration Sample Depth (feet) Moisture (°k) Fines (°r6) Description TP-2 S-2 2.0 13 45.3 gravellysatySAND PROJECT NO' J-1781 PROJECT NAME: Zipper Zeman Associates, Inc. DATE OF TESTING: 1/9/04 Hoyt Rd. SW Retail Creotecturical and Ettvllotunenta] Consulting 03/08/04 MON 15:42 [TX/RX NO 76401 APPENDIX E Site Improvement Bond Quantity Worksheet Facility Summary Sheet `CITY OF Federal Way PUBLIC WORKS DEPARTMENT BOND QUANTITIES WORKSHEET Project Name: Alcy'�6PhOre )0/1F20 e4C42W re"'071,ff'' Date: Project No.: 211&5'17- / fl Site Address: 2W ?�3404A �V• t f r4vG/ rdw d=26•oek By:. 3G,;ne�le P Fill in those items which pertain to this project and return to the Public Works Department ROAD CONSTRUCTION Clearing & Grubbing LS Bid Estimate Sawcutting LF 1.30 Excavation & Embankment CY 18.00 AC Pavement TN 40.00 (STC TN 16.00 Cement Concrete Curb/Gutter SY 10.00 Extruded Asphalt Curb LF 4.00 Concrete Sidewalk LF 22.00 Concrete driveway approach SY 35.00 Monument in case EA 155.00 Adjust ex. monument to grade EA 330.00 Adjust ex. cb to grade EA 400.00 DRAINAGE PIPE 6" Pipe LF 11.00 8" Pipe LF 25.00 12" Pipe LF 40.00 18" Pipe LF 40.00 24" Pipe LF 53.00 36" Pipe LF 92.00 48" Pipe LF 85.00 54" Pipe LF 106.00 60" Pipe LF 130.00 72" Pipe LF 214.00 CATCH BASINS Inlet & Grate EA 475.00 CB Type I & Grate EA 900.00 CB Type II 48" & Grate EA 1,900.00 CB Type II 54" & Grate EA 2,000.00 CB Type II 60" & Grate EA 3,200.00 CB Type II 72" & Grate EA 5,000.00 CB Type II 84" & Grate EA 9,100.00 CB Type II 96" & Grate EA Bid Estimate Round solid locking lid EA 360.00 Abandon exiting cb EA 325.00 Public Roadway Private On -Site Improvements Improvements Quantity Price Quantity Price Bond Quantities Price Schedule & Worksheet 3 Bond Quantities Price Schedule & Worksheet 3 RETENTION/DETENTION CONTROL Pond Excavation & Spillway CY 7.00 Restrictor/ parator EA 750.00 Vet =� P/PC EA Bid Estimate Gravel Access Road LF 15.00 Rip Rap Outfall Protection CY 17.00 Bollards EA 500.00 Fencing (around pond) LF 12.00 Infiltration Trench w/12" Perf LF 18.00 Flow Spreader LF 20.00 Trash Racks EA 200.00 WATER QUALITY Bioswale EA Bid Estimate weha+A -;Wm , EA Bid Estimate Stormi9lter Vault ✓ EA Bid Estimate Stormwater wetland EA Bid Estimate Sand Filter EA Bid Estimate Catch basin inserts EA 800.00 Oil/Water Separator EA Bid Estimate High Flow Bypass EA Bid Estimate RETAINING WALLS & STRUCTURES Retaining Walls SF 23.00 Bridges LS Bid Estimate TRAFFIC & LIGHTING Signalization LS Bid Estimate Channelization LS Bid Estimate Signs EA 100.00 Streetlights (City Center) EA 5,000.00 Streetlights (Standard) EA 3,000.00 RIGHT-OF-WAY LANDSCAPING Street Trees EA 250.00 Sod SF 1.00 Shrubs (City Center) EA 6.00 Tree Grates (City Center) EA 700.00 SITE STABILIZATION/EROSION CONTROL Quarry Spalls TN 75.00 Seeding/Mulch Acre 3,000.00 Silt Fence LF 4.00 Netting Jute Mesh SY 13.00 Sediment Pond Standpipe EA 200.00 Sensitive Area Fencing LF 3.00 Catch basin inserts EA 70.00 §iqffa'ture A"I- / /NC Firm Name 253 A65-2,422 Telephone Number Bond Quantities Price Schedule & Worksheet 4 THE FOLLOWING INFORMATION WILL BE COMPLETED BY THE CITY OF FEDERAL WAY PUBLIC WORKS DEPARTMENT: Public Roadway Improvements: $ Private On -Site Improvements: $ Erosion/Sedimentation Control: $ Subtotal_ CONTINGENCY (20%) TOTAL BOND AMOUNT Bond Quantities Price Schedule & Worksheet 5 KING COUNTY, WASHINGTON, SURFACE WATER DESIGN MANUAL STORMWATER FACILITY SUMMARY SHEET Development /M4h :1-Fh5re Date 36.0 y Location VW �qD �' '�G7- ?fY✓ ENGINEER DEVELOPER Name xPF m r , /PF Name, ' taw Firm l/YG. Firm ,4 iTI Address,'-W1f Af/ - Ato Address pGvlb S , F -rMo f-, Will g9403 aj W4-- 99424 Phone 2,:F -7 '3®3 Phone 2V3 — e96 � Sy Developed Site: Acres 451 -5, Number of detention facilities on site: ponds _ vaults tanks Number of lots" Number of infiltration facilities on site: ponds vaults tanks Flow control pro ded in regional facili Cove location} ��]brY�D � .�I�C '�I�l7A, 51d1A11C ��C. No flow control required Exemption number T)mmnctrenm Drainarre Basins Immediate Major Basin Basin A G1 S�T9/1� Basin B Basin C Basin D Number & type of water quality facilities on site: biofiltration swale (regular/wet/ or continuous inflow?) combined detention/WQ pond (WQ portion basic or large?) combined detention/wetvault compost filter -' 1�54vm '41e filter stripR flow dispersion farm management plan landscape management plan sand filter (basic or large?) sand filter, linear (basic or large?) sand filter vault (basic or large?) stormwater wetland wetpond (basic or large?) wetvault oil/water separator (baffle or coalescing plate?) basin in erts: n &rylrr pre -settling pond r/Vc 1998 Surface Water Design Manual 9/1/91 KING COUNTY, WASHINGTON, SURFACE WATER DESIGN MANUAL pre -settling structure: Manufacturer flow -sputter catchbasin DESIGN INFORMATION INDIVIDUAL BASIN A B C D Water Quality des flow cor- Water Quality treated volume or we and Vr 9/1/98 _ 1998 Surface Water Design Manual KING COUNTY, WASHINGTON, SURFACE WATER DESIGN MANUAL DESIGN TOTAL INDIVIDUAL BASIN INFORMATION, cont'd Drainage basin(s) A B C D Onsite area D ' 8 Offsite area Type of Storage Facility Live Storage Volume /$QZ Predeveloped Runoff 2-year Rate 10- ear 100-year Develo ed runoff rate 2-year 10- ear 100-year Type of restrictor 06 Ce Size of No. 1 orifice/restriction /2 y No. 2 No. 3 No. 4 FLOW CONTROL & WATER QUALITY FACILITY SUMMARY SHEET SKETCH L�P��� All detention, infiltra on and water quality facilities must include a sketch per the following criteria: 1. Heading for the drawings should be located at the top of the sketch (top right-hand corner). The heading should contain: • North arrow (point up or to left) • D9# • Plat name or short plat number • Address (nearest) • Date drawn (or updated) • Thomas Brothers page, grid number 2. Label CBs and MHs with the plan and profile designation. Label the control structure in writing or abbreviate with C.S. Indicate which structures provide spill control. 3. Pipes-- indicate: Pipe size Pipe length Flow direction Use s single heavyweight line 4. Tanks-- use a double, heavyweight line and indicate size (diameter) 5. Access roads Outline the limits of the road • Fill the outline with dots if the road is gravel. Label in writing if another surface. 6. Other Standard Symbols: • Bollards: • 000 MEMO ■ Rip rap 000000 000000 Fences--x--- x--- x--- x--- x--- x--- 1998 Surface Water Design Manual 3 9/1/9£ KING COUNTY, WASHINGTON, SURFACE WATER DESIGN MANUAL • Ditches—D--->-D--->-D--->'D 7. Label trash racks in writing. 8. Label all streets with the actual street sign designation. If you don't know the actual street name, consult the plat map. 9. Include easements and lot lines or tract limits when possible. 10. Arrange all the labeling or writing to read from left to right or from bottom to top with reference to a properly oriented heading. 11. Indicate c riveways or features that may impact access, maintenance or replacement. 9/1/98 1998 Surface Water Design Manual 4 APPENDIX F Operation and Maintenance Manual The Northshore Plaza Retail Building project proposes to construct a 4,100 square -foot retail building and associated parking on a half -acre site located south of SW 340`h Street and west of Hoyt Road SW in the City of Federal Way, Washington. Off -site improvements to Hoyt Road SW along the project site frontage will also be constructed as part of this development. Stormwater runoff generated on -site will sheet flow to a system of catch basins and associated piping and will be conveyed to an underground combination detention/sand filter vault for runoff control and treatment. The treated runoff will then be conveyed by a 12-inch pipe to the discharge point to SW 340`h Street located on the Northshore Chevron property to the north. See Figure 4 in Appendix A for the Developed Condition Map. Operation and maintenance will be the responsibility of the owner, Spearman Development Group. Mr. Alex Spearman is the main contact person and his contact information is as follows: Mr. Alex Spearman 3323 20'hStreet East Fife, WA 98424 PH: 253-896-4455 The Operation and Maintenance Manual shall be kept on -site at all times. Table 1 below shows the schedule of maintenance for the stormwater drainage system: Table 1: Schedule of Maintenance Structure inspection/maintenance Schedule Catch Basin Yearly Storm Drainage Pipes Yearly Detention Pie Yearly StormFilter/Storm ate Yearly The maintenance guidelines below describe the conditions when maintenance of the various stormwater structures is necessary and the results that may be expected from routine maintenance activities. CATCH BASINS Maintenance Defect Conditions When Maintenance is Needed Results Expected When Component Maintenance is performed General Trash & Debris Trash or debris of more than 1/2 cubic foot which is No Trash or debris located (Includes Sediment) located immediately in front of the catch basin immediately in front of catch opening or is blocking capacity of the basin by basin opening. more than 10% Trash or debris (in the basin) that exceeds 1/3 the No trash or debris in the catch depth from the bottom of basin to invert the lowest basin. pipe into or out of the basin. Trash or debris in any inlet or outlet pipe blocking Inlet and outlet pipes free of more than 1/3 of its height trash or debris. Dead animals or vegetation that could generate No dead animals or vegetation odors that could cause complaints or dangerous present within the catch basin. gases (e.g., methane). Deposits of garbage exceeding 1 cubic foot in No condition present which volume would attract or support the breeding of insects or rodents. Structure Damage to Comer of frame extends more than 3/4 inch past Frame is even with curb. Frame and/or Top Slab curb face into the street (If applicable). Top slab has holes larger than 2 square inches or Top slab is free of holes and cracks wider than 1/4 inch (intent is to make sure cracks. all material is running into basin). Frame not sitting flush on top slab, i.e., separation Frame is sitting flush on top of more than 3/4 inch of the frame from the top slab. slab. Cracks in Basin Walls/ Cracks wider than 1/2 inch and longer than 3 feet, Basin replaced or repaired to Bottom any evidence of soil particles entering catch basin design standards. through cracks, or maintenance person judges that structure is unsound. Cracks wider than 1/2 inch and longer than 1 foot No cracks more than 1/4 inch at the joint of any inlet) outlet pipe or any evidence wide at the joint of inlet/outlet of soil particles entering catch basin through pipe. cracks. Sediment/ Basin has settled more than 1 inch or has rotated Basin replaced or repaired to Misalignment more than 2 inches out of alignment. design standards. CATCH BASINS (CONTINUED) Maintenance Defect Conditions When Maintenance is Needed Results Expected When Component Maintenance is performed Fire Hazard Presence of chemicals such as natural gas, oil and No flammable chemicals gasoline. present. Vegetation Vegetation growing across and blocking more than 10% of the basin opening. Vegetation growing in inlelloutlet pipe joints that is more than six inches tall and less than six inches apart. Pollution Catch Basin Cover Cover Not in Place Locking Mechanism Not Working Cover Difficult to Remove Metal Grates (If Applicable) Trash and Debris Nonflammable chemicals of more than 1/2 cubic foot per three feet of basin length. Cover is missing or only partially in place. Any open catch basin requires maintenance. Mechanism cannot be opened by on maintenance person with proper tools. Bolts into frame have less than 1/2 inch of thread. One maintenance person cannot remove lid after applying 80 lbs. of lift; intent is keep cover from sealing off access to maintenance. Grate with opening wider than 7/8 inch. Trash and debris that is blocking more than 20% of grate surface. Damaged or Grate missing or broken member(s) of the grate. Missing. No vegetation blocking opening to basin. No vegetation or root growth present. No pollution present other than surface film. Catch basin cover is closed Mechanism opens with proper tools. Cover can be removed by one maintenance person. Grate opening meets design standards. Grate free of trash and debris. Grate is in place and meets design standards. CONVEYANCE SYSTEMS (PIPES & DITCHES) Maintenance Defect Conditions When Maintenance is Needed Results Expected When Component Maintenance is Performed Pipes Sediment & Debris Accumulated sediment that exceeds 20% of the Pipe cleaned of all sediment and diameter of the pipe. debris. Vegetation Vegetation that reduces free movement of water All vegetation removed so water through pipes. flows freely through pipes. Damaged Protective coating is damaged; rust is causing Pipe repaired or replaced. more than 50% deterioration to any part of pipe. Any dent that decreases the cross section area of Pipe repaired or replaced. pipe by more than 20%. Open Ditches Trash & Debris Trash and debris exceeds 1 cubic foot per 1,000 Trash and debris cleared from square feet of ditch and slopes. ditches. Sediment Accumulated sediment that exceeds 20 % of the Ditch cleaned/ flushed of all design depth. sediment and debris so that it matches design. Vegetation Vegetation that reduces free movement of water Water flows freely through through ditches. ditches. Erosion Damage to See "Ponds" Standard No. 1 See "Ponds" Standard No. 1 Slopes Rock Lining Out of Place Maintenance person can see native soil beneath Replace rocks to design or Missing (If the rock lining. standards. Applicable). Catch Basins See "Catch Basins: Standard No. 5 See "Catch Basins" Standard No. 5 Debris Barriers See "Debris Barriers" Standard No.6 See "Debris Barriers" Standard (e.g., Trash Rack) No. 6 CLOSED DETENTION SYSTEMS (PIPES/TANKS) Maintenance Defect Conditions When Maintenance is Needed Component Storage Area Plugged Air Vents One-half of the cross section of a vent is blocked at any point with debris and sediment Results Expected When Maintenance is Performed Vents free of debris and sediment Debris and Accumulated sediment depth exceeds 10% of the All sediment and debris Sediment diameter of the storage area for'/z length of storage removed from storage area. vault or any point depth exceeds 15% of diameter. Example: 72-inch storage tank would require cleaning when sediment reaches depth of 7 inches for more than''/: length of tank. Joints Between Any crack allowing material to be transported into All joint between tank /pipe Tank/Pipe Section facility sections are sealed Tank Pipe Bent Out Any part of tank/pipe is bent out of shape more than Tank/ pipe repaired or replaced of Shape 10% of irs design shape to design. Manhole Cover Not in Place Cover is missing or only partially in place. Any open Manhole is closed. manhole requires maintenance. Locking Mechanism cannot be opened by one maintenance Mechanism opens with proper Mechanism Not person with proper tools. Bolts into frame have less tools. Working than'/z inch of thread (may not apply to self-locking lids.) Cover Difficult to One maintenance person cannot remove lid after Cover can be removed and Remove applying 80lbs of lift. Intent is to keep cover from reinstalled by one maintenance sealing off access to maintenance. person. Ladder Rungs King County Safety Office and/or maintenance person Ladder meets design standards Unsafe judges that ladder is unsafe due to missing rungs, allows maintenance person safe misalignment, rust, or cracks. access. Catch Basins See "Catch Basins" Standards No. 5 See "Catch Basins" Standards No. 5 CONTROL STRUCTURE/FLOW RESTRICTOR Maintenance Defect Condition When Maintenance is Needed Results Expected When Component Maintenance is Performed General Trash and Debris Distance between debris build-up and bottom of All trash and debris removed. (Includes Sediment) orifice plate is less than 1-1/2 feet. Structural Damage Structure is not securely attached to manhole wall Structure securely attached to and outlet pipe structure should support at least wall and outlet pipe. 1,000 Ibs of up or down pressure. Structure is not in upright position (allow up to Structure in correct position. 10% from plumb). Connections to outlet pipe are not watertight and Connections to outlet pipe are show signs of rust. water tight; structure repaired or replaced and works as designed. Any holes —other than designed holes —in the Structure has no holes other structure. than designed holes. Cleanout Gate Damaged or Missing Cleanout gate is not watertight or is missing. Gate is watertight and works as designed. Gate cannot be moved up and down by one Gate moves up and down easily maintenance person. and is watertight. Chain leading to gate is missing or damaged. Chain is in place and works as designed. Gate is rusted over 50% of its surface area. Gate is repaired or replaced to meet design standards.. Orifice Plate Damaged or Missing Control device is not working properly due to Plate is in place and works as missing, out of place, or bent orifice plate. designed. Obstructions Any trash, debris, sediment, or vegetation Plate is free of all obstructions blocking the plate. and works as designed. Overflow Pipe Obstructions Any trash or debris blocking (or having the Pipe is free of all obstructions potential of blocking) the overflow pipe. and works as designed. Manhole See "Closed Detention Systems" Standards No. 3 See "Closed Detention Systems' Standards No. 3 Catch Basin See "Catch Basins" Standards No. 5 See 'Catch Basins" Standards No. 5 WATER QUALITY FACILITIES Stormfilter TM Maintenance Defect or Problem Condition When Maintenance is Needed Component Below Ground Sediment Vault Accumulation on Media. Sediment Accumulation in Vault Trash/ Debris Accumulation Sediment in Drain Pipes/Clean-Outs Below Ground Compost Media Cartridge type Short Circuiting Damaged Pipes Access Cover Damaged/ Not Working Sediment depth exceeds 625-inches. Sediment depth exceeds 6-inches in first chamber Trash and debris accumulated on compost filter bed. When drain pipes, ciean-outs, become full with sediment and/ or debris. Drawdown of water through the media takes longer than 1 hour, and/ or overflow occurs frequently. Flows do not property enter filter cartridges. Any part of the pipes that are crushed, damaged due to corrosion and/ or settlement Cover cannot be opened, one person cannot open the cover, corrosion/ deformation of cover. Recommended Maintenance to Correct Problem No sediment deposits which would impede permeability of the compost media. No sediment deposits in vault bottom of first chamber. Trash and debris removed from the compost filter bed. Remove the accumulated material from the facilities. Replace media cartridges. Replace filter cartridges. Pipe repaired and/ or replaced. Cover repaired to proper working specifications or replaced. Vault Structure Cracks wider than 1/2-inch and any evidence of Vault replaced or repaired to design Includes Cracks in soil particles entering the structure through the specifications. Wall, Bottom, cracks, or maintenance/ inspection personnel Damage to Frame determines that the vault is not structurally and/ or Top Slab sound. Cracks wider than 1/2-inch at the joint of any No cracks more than 1/4-inch wide at inlet/outlet pipe or any evidence of soil particles the joint of the inlet/ outlet pipe. entering the vault through the walls. Baffles Baffles corroding, cracking warping, and/ or Repair or replace baffles to showing signs of failure as determined by specification. maintenance/ inspection person. Access Ladder Ladder is corroded or deteriorated, not Ladder replaced or repaired and Damaged functioning properly, missing rungs, cracks, and meets specifications, and is safe to misaligned. use as determined by inspection personnel.