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HomeMy WebLinkAboutSWP272813 ' Shdrt Plat'(SHPL#' REQUEST FOR PROTECT# Prelim Plat (Ppu CAG# ) To: Technical Services Date 1 U—%q — / ! wo# �t}'/ Green# U Lff-oD(� From: Plan Review/Project Manager P/�r,f (. LV'vtil �i Project Name 5,0 /,J, /I T (0 charactus mu) Description of Project: ��'A1 S j` L4 ���`� o/G 9 S7��u.� L�C SEc�•�=,� 57/v'��.% 14T-f— t��✓ V,4V,dti-iZ47& Circle Size of Waterline: 8" 10" 12" Circle One: New or Extension Circle Size of Sewerline: G8.1 10" I2" Circle One: New or Extension Circle Size of Stoml.line: 12" 15" 18" C24 Circle One: New or Extension Address or Street Name(s) • Dvlpr/Contractor/Owner/Cnslu: C6AJT4 (70 charactus mu) Check each discipline involved in Project Ltr Dnvg of sheets per discipline XTrans-Storm ❑ X 13 (Roadway/Dr-.nagc) (Off sit-i.-tprovcmcnts)Cindudc basin name) (include TESC sheets) XTransportation (Sigtuli_a=on,aanndization,lighting) ❑ XWastewater Q X Sanitary Scwu?•Sain(include basin name) ❑ `crater (Mains,Valves,Hydrants) ❑ ❑ (Include composite Z Hori Lontal Ctrs ShCetS) v Suface Water Improvements (ALP ONLY)(includc basin name) TS Use Only T1fl-`W- -C•R D - t-' l — ;Q 4s l 3 -f -93 1&`13 ww¢-a-]- a�13 s-ag13 SvJp-a�- a�i3 -o-a� l3 -�- PROTECT CLOSING t!d Firm]Casf'Ja{u FINAL COST DATA AND U4VENI'ORY pad Intl enter CITY PROJECT NUMBERS: WTR- StJBJECT: — Wyyp- 0 l 2 Sva- Name of proje� T TEE- . D- TO: City ofRcnton FROM: Flan RtYie%v Section PlanninrJ'BWlding�ftlblis Works ¢�' �m 200 Mill Avcaue-SOU'h Renton,WA 98055 Di Per tl,c request of the City of Renton,the following information is famished concerning final costs for improvemeniti installed foi the above referenced project- W R SYS h4 CO 1STRUC ITON C OSTSt NOTi r� Length Size " T�rpe I-F.of WATSkMAIN L.F.of WATERNIAV -r L.F.of - "— WATFRMAIN -- L..F_of —� " WATERMAIN LEACH of �� GATE VALVES ' — 1~ACH of GATE VALVES EACH of " GATE VALVES EACH of �- " _ FIB=RANT A55EMBL1FS $ $ (Cost of Fire Hydrants must stparatcly) $ (Include Engin=ing alld Sales Tax if applicable TQTAI.COST FOR WATER SY5T12M $ STC)RM D GE SY. SATIITr1IY 5FWE8 SY ' ' h S a T pt STORM LLB L F.of S2 a T� SEWER MAiN L F,of /ai 5 rf�RM LINE SEWERMA q L.F.of ,� " $TDRML1It8 L.F.of " I�.1V'•- v MAlrl L.F.of a ._ L.F.of __�e_ EA of STORM Il�ILBTIOUTLET EA of rr D" ENETFA MAMOLES _ w / MR M CATCEJI3ASIl4 < " DIWB g?MA 4(-)t FAof L[�-E- EA o, — EA of 1 STORM CAT( ASii; fTnclu&rjg agin=mg and Sales Tax (lss9tuding En na wjT -`t� '� $ if Applicable) S if applicable) TOTAL{os-r FOR SANITARY S=rR SYSTEM $ TOTAL COST MR ST pM DRAINAGE SYS7'>- $ STpT'E7IMpRC)VEir1ENTS: (Including Curb,Gutter,Sidewalk,Asphalt Pavement u d Stre& kiting) SIGNALiZATION: (Including Eng.Dastgn Costs,City prrmit Fc cs,VIA St Sales Tax) STREET LIGHTING: (Including Eng-Design CoSM City Pernut T-ces,WA St Sales Tax) r` -r-- day phone rr FYint signatory name A RIRE) (Signatory m 1 aothorizcd agent (0mjsjcoSTDA7'•DQObh or owner of subyrct dcvcloptncm) 20010424000881 Return Address: CITY OF RENTON BS 9.00 PAGE 001 OF 002 City Clerk's Office 04/24/2001 11:33 City of Renton KING COUNTY, WA 1055 South Grady Way Renton,WA 98055 BILL OF SALE Z I Property Tax Parcel Number: Project File#:L��'4`�_��� Street Intersection: ly,,4,Y-1 3,- Address: vim,X,t, Reference Number(s)of Documents assigned or released:Additional reference numbers are on page Grantor(s): Grantee(s): 1. h1Tf�x t-�tavt�S� N�ll�7f'C G �i' City of Renton, a Municipal Corporation cx� 2. c' The Grantor,as named above,for,and in consideration of mutual benefits,hereby grants,bargains,sells and delivers to othe Grantee,as named above,the following described personal property: o WATER SYSTEM: Len Size Type u — L.F.of Water Main wf� L.F.of Water Main a L.F.of Water Main each of Gate Valves each of Gate Valves © each of Fire Hydrant Assemblies cv SANITARY SEWER SYSTEM: Length Size TType. _ �$)3 � L.F.of ��" V[i Sewer Main L.F.of Sewer Main -q7- O2— L.F.of V(J Sewer Main each of Diameter Manholes each of Diameter Manholes each of ✓ Diameter Manholes STORM DRAINAGE SYSTEM: Length Size T e _�g' 3 v2 2 L.F.of Storm Line L.F.of - 2_ Storm Line Z{-(/'r(p L.F.of Storm Line each of Storm Inlet/Outlet each of j Storm Catch Basin each of -L? p Manhole STREET IMPROVEMENTS: (Including Curb,Gutter,Sid ewa ,Asphalt P v Peiit)� Curb,Gutter,Sidewalk rj?JZGI L.F. S1 W--M—K % 55)C► ( Asphalt Pavement: 'q l�-' SY or L.F.of Width STREET LIGHTING: #of Poles By this conveyance,Grantor will warrant and defend the sale hereby made unto the Grantee against all and every person or persons,whomsoever,lawfully claiming or to claim the same. This conveyance shall bind the heirs,executors, administrators and assigns forever. op f -003 7a h e- H:\FILE.SYS\FRM\84RNDOUT\BILLSALE.DOC\MAB Page 1 Form 84 0001/bh IN WITNESS WHEREOF,I have hereunto set my hand and seal the day and year as written below. INDIVIDUAL FORM OFACKNOWLEDGMENT Notary Seal must be within box STATE OF WASHINGTON )SS COUNTY OF KING ) I certify that I know or have satisfactory evidence that signed this instrument and acknowledged it to be his/her/their free and voluntary act for the uses and purposes mentioned in the instrument - Notary Public in and for the State of Washington Notary(Print) My appointment expires: Dated: REPRESENTATIVE FORM OF ACKNOWLEDGMENT Notary Seal must be within box STATE OF WASHINGTON )SS COUNTY OF KING ) aI certify that I know or have satisfactory evidence that cc signed this instrument,on oath 0 o stated that he/she/they was/were authorized to execute the instrument and o acknowledged it as the and of to be the free and voluntary act of such cv party/parties for the uses and purposes mentioned in the instrument. 0 Notary Public in and for the State of Washington C= Notary(Print) My appointment expires: Dated: CORPORATE FORM OFACKNOWLEDGMENT Notary Seal must be within box STATE OF WASHINGTON )SS COUNTY OF KING ) On this 2—day of MAr(,,h ,before me personally appeared ��►��1`O `�l�'1 f'45 U1 to me known to F► a �t tt tj be �-rt�l 4er- of the corporation that ��....���'1r+ executed the within instrument,and acknowledge the said instrument to be the free and voluntary act and deed of said corporation,for the uses and purposes therein imentioned,and each on oath stated that he/she was authorized to execute said �jB`�c>, _ instrument and that the seal affixed is the corporate seal of said corporation. ����� 2 ; 1 oR WA �o; N ry Public in nd for the cSJtat`le H1of Washington t't �....��� tart'(Print)in A _ )QISl1Id�� My appointment expires: Dated: 3 �a • p� Page 2 9 )VINDSONG City of Renton, Washington Technical Information Report Revised August 4, 1999 Prepared By: Brett K. Pudists Reviewed By.- William W. Goggin, P.E. 1 AM � GO �O 28128IST Ww �SJONAL4����� EXPIRES: 1122101 TRIAD ASSOCIATES June 9 1999 Triad Job No . 95 - 244 • TABLE OF CONTENTS SECTION I : PROJECT OVERVIEW.......................................................................................................I DRAINAGECONCEPT...................................................................................................................................2 SECTION II : PRELIMINARY CONDITIONS SUMMARY.............................................................II-1 SECTION III : OFF-SITE ANALYSIS.................................................................................................III-1 SECTION IV: DETENTION ANALYSIS AND DESIGN..................................................................IV-1 EXISTINGCONDITIONS...........................................................................................................................IV-3 Existing Condition Hydrographs(Onsite Flows).............................................................................IV-3 Allowable Release Rates(Onsite Flows)..........................................................................................IV-3 DEVELOPEDCONDITIONS......................................................................................................................IV-4 Detained Area Hydrographs(Onsite Flows)....................................................................................IV-4 Bypass Area Hydrographs(Onsite Flows).......................................................................................IV-5 LEVEL POOL ROUTING(ONSITE FLOWS)...............................................................................................IV-5 UPSTREAMAREA..................................................................................................................................IV-6 UpstreamArea Hydrographs............................................................................................................1 V 6 COMBINEDFLOWS.................................................................................................................................IV-7 Allowable Release Rates(Combined Flows)....................................................................................IV-7 Pond Inflow Hydrographs(Combined Flows)..................................................................................IV-8 LEVEL POOL ROUTING(COMBINED FLOWS)..........................................................................................IV-8 TheoreticalPond..............................................................................................................................1V 9 ActualPond....................................................................................................................................IV-11 LIVESTORAGE....................................................................................................................................IV-12 WATERQUALITY.................................................................................................................................IV-12 OVERFLOWRISER................................................................................................................................IV-13 EMERGENCY OVERFLOW SPILLWAY....................................................................................................IV-13 SPILLWAYBETWEEN POND CELLS......................................................................................................IV-14 WETLANDRECHARGE.........................................................................................................................I V-15 Pre-Developed Flows to Wetland...................................................................................................IV-16 Post-Developed Flows to Wetland..................................................................................................IV-17 WetlandRecharge Summary...........................................................................................................IV-17 SECTION V: CONVEYANCE SYSTEM ANALYSIS AND DESIGN...............................................V-1 ONSITECONVEYANCE SYSTEM...............................................................................................................V-2 FRONTAGECONVEYANCE SYSTEM..........................................................................................................V-3 Flow Estimate-Hoquiam Avenue Ditch System............................................................................... V-3 Flow Estimate—NE 4'h Street Ditch System...................................................................................... V-4 SECTION VI : SPECIAL REPORTS AND STUDIES........................................................................VI-1 SECTION VII : BASIN AND COMMUNITY PLANNING AREAS...............................................VII-1 SECTIONVIII : OTHER PERMITS.................................................................................................VIII-1 SECTION IX : EROSION/SEDIMENTATION CONTROL DESIGN..............................................IX-I PHASEI OF CONSTRUCTION...................................................................................................................IX-1 PHASEII OF CONSTRUCTION.................................................................................................................IX-2 SECTION X : BOND QUANTITIES WORKSHEET...........................................................................X-I • DETENTION SUMMARY SKETCH..............................................................................................................X-1 SECTION XI : MAINTENANCE AND OPERATIONS MANUAL..................................................XI-I TECHNICAL INFORMATION REPORT FOR WINDSONG PAGE: i LIST OF SUPPLEMENTAL INFORMATION Note: Where applicable, supplemental information is located at the end of each section. Section I: Soils Map Soils Legend Figure 3.5.2A—Hydrologic Soil Group of the Soils in King County Section II: Mitigated Determination Non-Significance Section III: Level One Offsite Drainage Analysis and Preliminary Detention Concept Section IV: Table 3.5.213— SCS Western Washington Runoff Curve Numbers 2, 5, 10, 25, and 100-Year Isopluvial Maps Water Works Output(used for Detention Calculations) Pond Volume Calculations Figure 4.4.7-J—Riser Inflow Curves Wetland Tributary Area Exhibit Wetland Recharge Exhibit Section V: Conveyance System SBUH Flows Conveyance System Flow Calculations 25 and 100- Year Isopluvial Maps HGL Calculations Section IX: TESC Flow Rates Section X: Pond Plan Pond Sections Appendix Located at the End of This Report: Existing Conditions Exhibit Develop Conditions Exhibit Pipe Tributary Area Map Upstream Area Map • TECHNICAL INFORMATION REPORT FOR WINDSONG PAGE: ii / SECTION I PROJECT OVERVIEW SECTION I : PRO ECT OVERVIEW The proposed Windsong project is the construction of 68 single-family units on 11.56 acres of land in the City of Renton. The site is located at the intersection of NE 41h Street and Hoquiam Avenue NE (refer to the Vicinity Map located on the following page). In general, the site lies within the southwest quarter of Section 10, Township 23 North, Range 5 East W.M. in King County, Washington. In addition to the proposed onsite improvements, offsite improvements will be made along Hoquiam Avenue NE and NE 41h Street. Specifically, Hoquiam Avenue NE will be widened to 36 feet of travel way with curb, gutter and sidewalk across the Windsong frontage. Curb gutter and sidewalk will also be added to the north side of NE 41h Street along the site's frontage. Refer to the Existing and Developed Conditions Map located in the appendix of this report. The site will be constructed in two phases. During Phase I of construction, the portion of the site located west of Hoquiam Avenue will be developed. The frontage improvements associated with Phase I will also be constructed at this time. The portion of the site located east of Hoquiam Avenue NE, as well as the remainder of the frontage improvements, will be constructed during Phase II. Refer to the Road and Storm Drainage plans for this project for further detail on the construction phasing. The conveyance system and detention/water quality facility incorporated in this report were design assuming both phases of construction are complete. The temporary sedimentation and erosion control facilities incorporated within this report were designed based on the separate construction phases. A site visit was made on January 12, 1999, an overcast day with light rainfall. The site is bordered by a new shopping center to the west and lightly developed residential areas to the north and east. The site is divided by Hoquiam Avenue NE with approximately one third of the area located east and two-thirds located west of the existing roadway. The site contains three residences, each of which are currently occupied. With the exception of TECHNICAL INFORMATION REPORT FOR WINDSONG PAGE: I-1 the existing houses and associated driveways, the site is covered predominately with a mixture of underbrush and trees typical of second growth forests located in western Washington. Onsite soils are predominately Alderwood series that belong to the S.C.S. Type C hydrologic group (see Soils Map located in the appendix at the end of this section). In general, the site slopes to the southwest, with no slopes greater than 40%. An existing onsite wetland is located near the southwest corner of the site. DRAINAGE CONCEPT Refer to the Developed Conditions Map, located in the appendix, to aid in the following discussion. The proposed drainage system will consist of a curb and gutter roadway section with catch basins for the interception of runoff associated with onsite areas, including the improved section of Hoquiam Avenue NE. Roof and footing drains from each building will be tied into the conveyance system, which in turn will discharge to the proposed combination detention/water quality facility located near the southwest corner of the site. A portion of the stormwater discharge leaving the proposed detention/water quality facility will be directed to the onsite wetland while the remainder of the flow will be discharged to the proposed conveyance system associated with NE 4`h Street. A tightline conveyance system will replace the existing open ditch along the north side of NE 41h Street. Runoff tributary to this system, including upstream flows and runoff collected by the proposed curb, gutter and catch basins on the north side of NE 4`h Street, will be conveyed directly to the existing tightline system located near the southwest property corner. A separate tightline conveyance system, located along the east side of Hoquiam Avenue NE, will convey upstream flows associated with the 142°d Street ditch system north of the City boundary to the proposed system in NE 4`h Street, thus bypassing the onsite detention facility. TECHNICAL INFORMATION REPORT FOR WINDSONG PAGE: I-2 O REN — /�qov -9y cW SE 116TH ST e N W � Q � O � � j SE 128174 ST liilN r i AVK- Q � w � PARK h Cl TY OF RENTON Vicinity Map NTS TECHNICAL INFORMATION REPORT FOR WINDSONG PAGE: I-3 APPENDIX SHEET NO. 11 KING COUNTY AREA, WASHINGTON (RENTON QUADRANGLE) 41 1680000 FEET 122007'30" 47°30' .• AgD If '413� AgC �: C..• 'Bk •' , AgC 1 935 1: • Ag6 .1 • ____ * SITE •Trailgr .• •• iI: -Ev6 ark'. a II u .B B u 3 '• 424 .. .%6 ce 'n ..... I •'•' - ',� 180 000 • AgC �I FEET406 Fb AgC If u I -•^ � I I •JI I AkF � � •n •�i // 37 '•n Ev6 I --- '• ...__ wod' --^Ma ,• — .�Py N' Co sp 1 .u / /rCoo I it EvB rse I II- AkF J "• • Qom•' ,.+. \_ I 1 ". ° AkFPr 10 •�• F <� •, M tob-c >P O > {�1$p •.• :%• q' 6 AIV9 1• .Py Ma W ~` _` 1\+ "t qll I• •„• � Pc El lot . I u JI Py Rh W I J AkF a co== h •I. Ur Eta Q. 1 �\e) AkF Park Ng • F .ate .I ABC PY ■ EvC AgC I M I B AgD AkF 2 r• -- — �- _-_-_-- --- ———————— j -- -° - - °-- - -�- --- _ o BM 27'30„ A B I --°---A82--°_- AgC AgD C I AgD I AkF BMp 428 I F� ` PIPELINE AgC A8B i (1m6 AgB — --- J Ur I ` 27 1 2 I 492 I , F� NO �Ir 1 .,�o�„ SOILS MAP SOIL LFGEND , The first capitol letter is the initiol one of the soil name. A second capitol letter, A, B,C, D, E, or F, indicates the class of slope. Symbols without o slope letter o e those of nearly level soils. SYMBOL NAME AgB Alderwood gravelly sandy loam,0 to 6 percent slopes AaC Alderwood gravelly sandy loom,6 to 15 percent slopes AgD Alderwood gravelly sandy loam, 15 to 30 percent slopes AkF Alderwood and Kitsap soils,very steep AmB Arents,Alderwood material,0 to 6 percent slopes e A.0 Arents,Alderwood material,6 to 15 percent slopes e An Arents, Everett material e BeC Beausite gravelly sandy loam,6 to 15 percent slopes BeD Beausite gravelly sandy loam, 15 to 30 percent slopes BeF Beausit.gravelly•ardy-1 m;d0+o 75 perccot mlopec -- - _ Bh Bellingham slit loam Br .Briscot silt loam Bu Buckley silt loam Cb Coastal Beaches Ea Earlmont silt loam Ed Edgewick fine sandy loam EvB Everett gravelly sandy loam, 0 to 5 percent slopes EvC Everett gravelly sandy loam,5 to 15 percent slopes EvD Everett gravelly sandy loam, 1S to 30 percent slopes EwC Everett-Alderwood gravelly sandy looms,6 to 15 percent slopes InA Indianola loamy fine sand,0 to 4 percent slopes InC Indianola loamy fine sand,4 to 15 percent slopes InD Indianola loamy fine sand, 15 to 30 percent slopes KPB Kitsap slit loam,2 to 8 percent slopes KpC Kitsap silt loam,8 to 15 percent slopes KpD Kitsap slit loam, 15 to 30 percent slopes KsC Klaus gravelly loamy sand,6 to 15 percent slopes Ma Mixed alluvial land NeC Neilton very gravelly loamy sand, 2 to 15 percent slopes Ng Newberg slit loam Nk Nooksock silt loam No Norma sandy loam Or Orcas peat Os Oridia slit loam OvC Ovall gravelly loam,0 to 15 percent slopes OvD Oval[gravelly loam, 15 to 25 percent slopes OvF Oval[gravelly loam,40 to 75 percent slopes Pc Pilchuck loamy fire sand Pk Pilchuck fine sandy loam Pu Puget silty clay loam Py Puyallup fine sandy loam RaC Rognar fine sandy loam,6 to 15 percent slopes RcD Rognor fine sandy loam, 15 to 25 percent slopes RdC Ragnor-Indianola association,sloping* RdE Rognor-Indianola association,moderately steep• Re Renton silt loam Rh Riverwash Sa Solal silt loam Sh Sammamish silt loam Sk Seattle muck Sm Shalcar muck Sri Si silt loam So Snohomish silt loom Sr Snohomish silt loam,thick surface variant Su Sultan silt loam Tu Tukwila muck Ur Urban land Wo Woodinville silt loam • The composition of these units Is more variable than that of the others In the area,but It has been controlled well enough to interpret far the expected use of the soils. K ING COUNTY, WASHINGTON, SURFACE WATER DESIGN MAN (JAL (2) CN values can be area weighted when they apply to pervious areas of similar CN's (within 20 CN points). However, high CN areas should not be combined with low CN areas (unless the low CN areas are less than 15% of the subbasin). In this case, separate hydrographs should be generated and summed to form one hydrograph. FIGURE 3.5.2A HYDROLOGIC SOIL GROUP OF THE SOILS INKING COUNTY HYDROLOGIC HYDROLOGIC SOIL GROUP GROUP* SOIL GROUP GROUP' Alderwood C Orcas Peat D �Arents, Alderwood Material �� Oridia D Arents, Everett Material B Ovall C Beausite C Pilchuck C_ Bellingham D Puget D Briscot D Puyallup B" Buckley D Ragnar B Coastal Beaches Variable Renton D Earlmont Silt Loam D Riverwash Variable Edgewick C Sala[ C Everett A/B D Indianola A Seattle D Kitsap C Shacar D Klaus C Si Silt C Mixed Alluvial Land Variable Snohomish 0 Neilton A Sultan C Newberg B Tukwila D Nooksack C Urban Variable Normal Sandy Loam D Woodinville D HYDROLOGIC SOIL GROUP CLASSIFICATIONS A. (Low runoff potential). Soils having high infiltration rates, even when thoroughly wetted, and consisting chiefly of deep, well-to-excessively drained sands or gravels. These soils have a high rate of water transmission. B. (Moderately low runoff potential). Soils having moderate infiltration rates when thoroughly wetted, and consisting chiefly of moderately fine to moderately coarse textures. These soils have a moderate rate of water transmission. C. (Moderately high runoff potentiai). Soils having slow infiltration rates when thoroughly wetted, and consisting chiefly of soils with a layer that impedes downward movement of water, or soils with moderately fine to fine textures. These soils have a slow rate of water transmission. D. (High runoff potential). Soils having very slow infiltration rates when thoroughly wetted and consisting chiefly of clay soils with a high swelling potential, soils with a permanent high water table, soils with a hardpan or clay layer at or near the surface, and shallow soils over nearly impervious material. These soils have a very slow rate of water transmission. From SCS, TR-55, Second Edition, June 1986, Exhibit A-1. Revisions made from SCS, Soil Interpretation Record, Form #5, September 1988. </.. 3.S - 001110 SECTION II in CONDITIONS SUMMARY SECTION II : PRELIMINARY CONDITIONS SUMMARY A copy of the mitigated determination of non-significance is located in the appendix at the end of this section. A summary of how the drainage-related topics were addressed is provided below. Note: Numbering corresponds to the associated mitigation measure (see appendix). Summary of Mitigation Actions Relevant to Drainage: 1. A temporary sedimentation and erosion control plan was created. The plan contains notes stressing not only the installation of but also maintenance to the proposed TESC facilities. The notes also state that a report, addressing the condition of the TESC facilities, shall be presented to the public works inspector on a weekly basis. 2. The wetland buffer was increased to 50 feet as determined using buffer averaging methods. 3. The outer edge of the wetland buffer will be delineated prior to commencing with construction activities. 4. The storm water release rate from the detention facility was restricted as outlined. TECHNICAL INFORMATION REPORT FOR WINDSONG PAGE: II-1 APPENDIX CITY OF RENTON DETERMINATION OF NON-SIGNIFICANCE (MITIGATED) MITIGATION MEASURES APPLICATION NO(S): LUA-99-006,PP,ECF APPLICANT: Kenneth Krueger PROJECT NAME: Windsong Development DESCRIPTION OF PROPOSAL: Proposal to subdivide an 11.55 acre parcel into 70 single-family residential lots. The proposed lot sizes range between 3,755 sq. ft. and 5,667 sq. ft. Access to the lots would be provided from public streets constructed off 142nd Ave. SE (King County street name). The subject property is presently under review for annexation into the City of Renton. The Renton City Council has approved the annexation; however, final approval is required by the Boundary Review Board. The proposed subdivision is contingent upon successful completion of the annexation. The Renton City Council is responsible for approving City zoning of the site. The property is located within the Residential Options Comprehensive Plan designation, which is implemented by Residential-10 DU/AC (R-10) zoning. This zoning would allow for a maximum residential density of 10 dwelling units per acre. The net density of the proposed subdivision is 7.38 dwelling units per acre. There is a 10,514 sq. ft. Category 3 wetland identified in the southwest comer of the site. The proposal would not directly impact the wetland and a 25 foot wide buffer is maintained around the wetland. LOCATION OF PROPOSAL: NE 4th Street east of Duvall Avenue NE, 142nd Avenue SE (King County street) MITIGATION MEASURES: 1. Temporary Erosion Control shall be installed and maintained to the satisfaction of the representative of the Development Services Division for the duration of the project. Weekly reports shall be submitted on the status and condition of the erosion control plan with any recommendations of change or.revision to maintenance schedules or installation submitted by the Project Engineer of record to the Public Works Inspector. Certification of the installation, maintenance and proper removal of the erosion control facilities shall be required prior to Temporary Certificate of Occupancy. 2. The applicant shall revise the preliminary plat to provide a minimum 50 foot buffer width around Wetland A which is considered to be a Category 2 wetland. Revised plans shall be subject to the approval of the Development Services Division. 3. The applicant shall stake the outer edge of the wetland and buffer prior to initiating grading or construction activities on the project site. 4. The stormwater release rate for the developed site shall be limited to 50% of the predeveloped 2 year 24,,hour storm event through the 2 year storm event, with a safety factor of 10% in the detention volume. The release rates for the developed site shall be limited for the 5 year, 10 year and 100 year storm event to the predeveloped rates for those events, with a 30% safety factor for the 100 year storm event. 5. The applicant shall pay the appropriate Fire Mitigation Fee equal to $488 per new single family lot. The Fire Mitigation Fee is payable prior to recording the subdivision. Windsong Development LUA-99-006,PP,ECF Mitigation Measures (Continued) Page 2 of 2 6. The applicant shall be required to pay a Traffic Mitigation Fee of$75 for each average daily trip associated with the project. The traffic mitigation fee is estimated to be $47,992.50. This fee is payable prior to recording the subdivision. 7. The applicant shall pay a Park's Department mitigation fee of$530.76 per new single family lot. The required mitigation fee shall be paid prior to recording the subdivision. CITY OF RENTON DETERMINATION OF NON-SIGNIFICANCE (MITIGATED) ADVISORY NOTES APPLICATION NO(S): LUA-99-006,PP,ECF APPLICANT: Kenneth Krueger PROJECT NAME: Windsong Development DESCRIPTION OF PROPOSAL: Proposal to subdivide an 11.55 acre parcel into 70 single-family residential lots. The proposed lot sizes range between 3,755 sq. ft. and 5,667 sq. ft. Access to the lots would be provided from public streets constructed off 142nd Ave. SE (King County street name). The subject property is presently under review for annexation into the City of Renton. The Renton City Council has approved the annexation; however, final approval is required by the Boundary Review Board. The proposed subdivision is contingent upon successful completion of the annexation. The Renton City Council is responsible for approving City zoning of the site. The property is located within the Residential Options Comprehensive Plan designation, which is implemented by Residential-10 DU/AC (R-10) zoning. This zoning would allow for a maximum residential density of 10 dwelling units per acre. The net density of the proposed subdivision is 7.38 dwelling units per acre. There is a 10,514 sq. ft. Category 3 wetland identified in the southwest comer of the site. The proposal would not directly impact the wetland and a 25 foot wide buffer is maintained around the wetland. LOCATION OF PROPOSAL: NE 4th Street east of Duvall Avenue NE, 142nd Avenue SE (King County street) Advisory Notes to Applicant. The following notes are supplemental information provided in conjunction with the environmental determination. Because these notes are provided as information only, they are not subject to the appeal process for environmental determinations. BUILDING Demolition permits will be required for removal of existing structures. Compliance with all 1997 Uniform Codes required. FIRE 1. Fire Department access roadways require a minimum 20 foot paved roadway with a turning radius of 45 feet outside and 25 feet inside. Planter are not allowed in approved cul-de-sacs. 2. Project requires a secondary means of access by City Ordinance. 3. All building addresses shall be visible from the public street. PLAN REVIEW SEWER 1. The project will be required to extend the 24" sewer interceptor located in NE 4th Street (SE 128th Street) from Duvall Avenue NE to the east end of the site (approximately 1,320 feet), and a 12" sewer main installed in Hoquiam Avenue NE (142nd Avenue SE) from NE 4th Street to the north end of the site, approximately 620 feet. Sewers serving the plat will also be required, located in new internal streets within the development. Windsong Development LUA-99-006,PP,ECF Advisory Notes (Continued) Page 2 of 2 2. System Development Charges of $585 per single family house will be required at the time of construction permit issuance. 3. A special assessment for the East Renton Interceptor shall be required for each single family lot. The base amount as of 7/14/96 is $224.52 per lot, with a simple interest of 4.11% annually. WATER 1. The proposed site is within Water District#90 service area and would be served by the District for fire and domestic water service. DRAINAGE 1. The project will require erosion/sedimentation control plans designed in accordance with the 1990 King County Surface Water Design Manual (KCSWDM) as adopted by the City of Renton. 2. System Development Charges of$385 per building lot will be required at the time of construction permit issuance. STREET IMPROVEMENTS 1. The project will require full street improvements to include curb, gutter, sidewalks, street paving, street drainage, street lights and undergrounding of overhead utility lines. The new intemal streets will be a minimum of 32 feet curb-to-curb in width, with a 5 foot concrete sidewalk along both sides, vertical curbs with gutters, street drainage system and street lights. The street system will have names and addresses per the City's established street grid system as assigned by the Planning/Building/Public Works Departments. 2. All private streets located in the plat will be in 26 foot wide easements with a minimum pavement width of 20 feet. On the north end of the easterly site, a 25 foot wide right-of-way with a minimum 20 feet of pavement (half street improvement) and a 5 foot concrete sidewalk from Hoquiam Avenue NE to the east property line of the site (approximately 300 feet) will be required. _ 3. All lots on dead-end streets exceeding 500 feet or more in length will require sprinkler systems. GENERAL All required utility, drainage and street improvements will require separate plan submittals prepared according to City of Renton drafting standards by a registered Civil Engineer. The construction permit application must include a itemized cost estimate for these improvements. The fee for review and inspection of these improvements is 5% of the first $100,000 of the estimated construction costs; 4% of anything over $100,00 but less than $200,000, and 3% of anything over $200,000. Half of this fee must be paid upon application for building and construction permits, and the remainder when the permits are issued. There may be additional fees for water service related expenses. POLICE Once developed (and annexed), there would be approximately 51.80 CFS annually to this development. PARKS 1. Landscaping (street trees) along NE 4th Street to be recommended and coordinated with Parks. 2. A bicycle lane has been identified on NE 4th Street in the City's Trails and Master Plan. Street improvements should include a 5 foot wide bike lane. SECTION III OFF-SITE ANALYSIS SECTION Ill : OFF-SITE ANALYSIS Refer to the Level One Offsite Drainage Analysis and Preliminary Drainage Concept, located at the end of this section, for a detailed description of the offsite drainage components for this project. TECHNICAL INFORMATION REPORT FOR WINDSONG PAGE: III-1 • APPENDIX * WINDSONG City of Renton, Washington LEVEL ONE OFFSITE DRAINAGE ANALYSIS AND PRELIMINARY DRAINAGE CONCEPT Prepared By: Brett K. Pudists Reviewed By: William W. Goggin, P.E. TRIAD ASSOCIATES January 12 1999 Triad Job No . 95 - 244 * )VINDSONG City of Renton, Washington LEVEL ONE OFFSITE DRAINAGE ANALYSIS AND PRELIMINARY DRAINAGE CONCEPT Prepared By: 00 Brett K. Pudists 0 w Reviewed By: 8►20 William W. Goggin, P.E. �10 � EXPIRES f -2 -or TRIAD ASSOCIATES January 12 , 1999 Triad Job No . 95 - 244 Page 1 of 2 King County Building and Land Development Division TECHNICAL INFORMATION REPORT (TIR) WORKSHEET PROJECTPART 1 PROJECT OWNER AND PART 2 PROJECT LOCATION ENGINEER AND DESCRIPTION Project Owner Centex Homes Project Name Windsong Address 2320-130th Ave NE #200 Location Phone 425-882-361 1 Bellevue 9BM5 Township 23N Project Engineer William J. Goggin, PE Range 5E Company Triad Associates Section 10 Address Phone 1 1 81 4-1 1 5 th Ave NE Project Size 1 1 .6 AC Kirkland Wa 98034 4 5- - 48 Upstream Drainage Basin Size _7 AC i PART 3 TYPE OF • OTHER [Z] Subdivision E:�] DOF/G HPA Shoreline Management E:1 Short Subdivision 0 COE 404 ® Rockery ExE i Grading = DOE Dam Safety © Structural Vaults 0 Commercial 0 FEMA Floodplain Other F-1 Other 0 COE Wetlands HPA I COMMUNITYPART 5 SITE . DRAINAGE BASIN Newcastle Drainage Basin Lower Cedar River PART 6 SITE CHARACTERISTICS River Floodplain Stream Wetlands K.C. Wetland 150 near SW Critical Stream Reach F-1 Seeps/Springs corner Depressions/Swales = High Groundwater Table Lake = Groundwater Recharge 0 Steep Slopes Other 0 Lakeside/Erosion Hazard PART 7 SOILS Soil Type Slopes Erosion Potential Erosive Velocities Alderwood 6% 15% Low Low i Additional Sheets Attatched 1/90 Page 2of2 King County Building and Land Development Division TECHNICAL INFORMATION REPORT (TIR) WORKSHEET DEVELOPMENTPART 8 • REFERENCE LIMITATION/SITE CONSTRAINT Ch.4-Downstream Analysis ED 0 a Additional Sheets Attatched PART • ESC REQUIREMENTS MINIMUM ESC REQUIREMENTS MINIMUM ESC REQUIREMENTS DURING CONSTRUCTION FOLLOWING CONSTRUCTION �X Sedimentation Facilities ® Stabilize Exposed Surface l Stabilized Construction Entrance ® Remove and Restore Temporary ESC Facilities Perimeter Runoff Control E—X Clean and Remove All Silt and Debris Clearing and Grading Restrictions ® Ensure Operation of Permanent Facilities ® Cover Practices E:1 Flag Limits of NGPES ® Construction Sequence 0 Other Other PART 10 SURFACE WATER SYSTEM 0 Grass Lined Channel 1=1 Tank Infiltration Method of Analysis ® Pipe System ® Vault Depression SBUH Open Channel 0 Energy Dissapator 0 Flow Dispersal Compensation/Mitigation Dry Pond CI Wetland 0 Waiver of Eliminated Site Storage 0 Wet Pond C1 Stream Regional Detention Brief Description of System Operation Tightline System conveys flows to combined Detention/Water Quality Vault Facility Related Site Limitations Additional Sheets Attatched Reference Facility Limitation PART 11 STRUCTURAL ANALYSIS PART 12 EASEMENTS/TRACTS (May require special structural review) 0 Drainage Easement ® Cast in Place Vault ED Other = Access Easement 0 Retaining Wall EJ Native Growth Protection Easement 0 Rockery>4'High [ Tract Structural on Steep Slope Other I or'a civil engineer under my supervision have visited the site. Actual site conditions as observed were incorporated into this worksheet and the attatchments. To the best of my knowledge the information provided here is accurate. 1/90 TABLE OF CONTENTS INTRODUCTION........................................................................................................................................1 VICINITYMAP...........................................................................................................................................2 UPSTREAM DRAINAGE ANALYSIS......................................................................................................3 DOWNSTREAM DRAINAGE ANALYSIS...............................................................................................3 BACKGROUND............................................................................................................................................3 DOWNSTREAMANALYSIS...........................................................................................................................3 DOWNSTREAM DRAINAGE PROBLEMS........................................................................................................5 RESOURCES USED FOR ANALYSIS......................................................................................................6 CRITICALDRAINAGE AREAS......................................................................................................................6 SENSITIVEAREAS FOLIO............................................................................................................................6 FLOODPLAIN/FLOODWAY MAPS..............................................................................................................6 KING COUNTY WETLANDS INVENTORY......................................................................................................6 KING COUNTY BASIN RECONNAISSANCE PROGRAM...................................................................................6 SOILS SURVEY FOR THE KING COUNTY AREA............................................................................................6 KING COUNTY COMMUNITY PLANNING AREA...........................................................................................6 KING COUNTY WATER AND LAND RESOURCES DIVISION LOCAL DRAINAGE COMPLAINTS.......................7 DRAINAGECONCEPT..............................................................................................................................7 PRELIMINARY DETENTION CALCULATIONS .................................................................................8 COMBINATION DETENTION/WET VAULT.................................................................................................9 PRELIMINARY WATER QUALITY CALCULATIONS.......................................................................9 DEAD STORAGE..................................................................................ERROR! BOOKMARK NOT DEFINED. BIOFILTRATIONSWALE..............................................................................................................................9 CONCLUSION...........................................................................................................................................10 Offsite Analysis and Preliminary Drainage Concept for Windsong-Page i Appendix Upstream Area Map Downstream Drainage Map Offsite Analysis Drainage System Table Drainage Complaints Exhibit (KC WLRD) Excerpts from The King County Sensitive Areas Folio: Erosion Hazard Areas Coal Mine Hazard Areas Streams and 100 Year Floodplains Wetlands Landslide Hazard Areas Seismic Hazard Areas Flood Insurance Rate Map (FIRM/FEMA) Wetlands Inventory Exhibit Basin Reconnaissance Map Community Planning Map Soils Map Soils Legend Water Works Output (Detention Calculations) Table 3.5.2B—Western Washington Runoff Curve Numbers Washington State Isopluvial Maps Biofiltration Swale Calculations In pockets at end of appendix: Existing Conditions Map Developed Conditions Map Offsite Analysis and Preliminary Drainage Concept for Windsong-Page ii INTRODUCTION The proposed Windsong project is the construction of 70 single-family units on approximately 11.6 acres. The site is located at the intersection of SE 128"' Street and 142nd Avenue SE (refer to the Vicinity Map located on the following page). The site is located immediately east of the current City of Renton boundary however, as a part of this project, it is anticipated that the site will be annexed into the City of Renton. In general, the site lies within the southwest quarter of Section 10, Township 23 North, Range 5 East, in King County, Washington. In addition to the onsite improvements, offsite improvements will be made along 142nd Ave SE and SE 128' street. Specifically, 142nd Ave SE will be widened to 38 feet of travel way with curb, gutter and sidewalk along both sides of the improvements across the Windsong frontage. Curb gutter and sidewalk will also be added to the north side of SE 128`b Street along the site's frontage. Refer to the Existing and Developed Conditions Map located in the appendix of this report. A site visit was made on January 12, 1999, an overcast day with light rainfall. The site is bordered by a shopping center to the west and lightly developed residential areas to the north and west. The site is divided by 142nd Avenue SE with approximately one third of the site located east and two-thirds located west of the roadway. The site contains three residences, each of which are currently occupied. With the exception of the existing houses and associated driveways, the site is covered predominately with a mixture of underbrush and trees typical of second growth forests located in western Washington. The site generally slopes to the southwest, with no slopes greater than 40%. An existing wetland is located near the southwest corner of the site. Offsite Analysis and Preliminary Drainage Concept for Windsong—Page 1 0 Rent°n- /Ss W aq�ah < 5E I I Gth 5t z W c cn w 7 N Z _ Q Q o � � � m E 128th 5t W ark Site > Ln Park Renton Vicinity Map NTS Offsite Analysis and Preliminary Drainage Concept for Windsong—Page 2 UPSTREAM DRAINAGE ANALYSIS Refer to the Upstream Area Map, as well as the Existing Conditions Map, both of which are located in the appendix, to aid in the following discussion. Currently, there are approximately 3.75 acres of upstream residential area creating sheet flow that is tributary to the site. Also, there is approximately 14.65 acres of upstream residential area that drains to an existing ditch system that runs along both sides of 142nd Avenue SE. This ditch system conveys runoff south to the existing ditch located along the north side of SE 128 h Street. This ditch, in turn, conveys runoff west to a cross- culvert under SE 128 h Street located near the southwest corner of the site. DOWNSTREAM DRAINAGE ANALYSIS Background Barghausen Consulting Engineers, Inc prepared a level one downstream analysis, dated October 1997, for the Highland Market Place shopping center located west of the site. Runoff from the shopping center drains to the cross culvert located near Windsong's southwest property corner. From here, the downstream drainage course, known as Maplewood Creek, is identical for both projects. A copy of the "Level I Drainage Report for Highland Market Place" was received from Barghausen Consulting Engineers, Inc. A site visit was made on January 12, 1999, by Triad Associates, to field verify the downstream drainage portions of the report. Based on the site visit, it was determined that the report accurately reflects current field conditions. Downstream Analysis Refer to the Downstream Drainage Map as well as the Off-Site Analysis Drainage System Table to aid in the following summary of the downstream drainage system for the Windsong project. Offsite Analysis and Preliminary Drainage Concept for Windsong—Page 3 Runoff from the eastern portion of the site drains southwest where it is collected by an existing drainage ditch located along the east side of 142"d Avenue SE. This ditch conveys runoff south where it connects to an east to west flowing ditch located on the north side of SE 128`h Street. This ditch, which runs along the entire length of the site's frontage, conveys runoff to the cross culvert located near the southwest property corner. Runoff from the remainder of the site sheet flows to the SE 128' Street ditch or to the onsite wetland. Once at the southeast property corner, storm water runoff in the SE 128 ' Street ditch combines with flow leaving the wetland and is conveyed underneath SE 128' Avenue through and an 18-inch diameter concrete pipe (labeled as point #1 on the Downstream Drainage Map). The pipe empties to an open drainage channel (point #2) that conveys runoff south. The drainage channel flows through a marshy area identified as King County wetland 150 (point #3) before collecting in a detention facility approximately 950 feet downstream of the project (point #4). The pond discharges to an 18" concrete pipe that empties to a smaller open channel drainage course (point #5) that conveys runoff south, between two property lines, until it reaches SE 132"d Street. From here, runoff is directed a short distance east before reaching a point that is located one-quarter mile downstream of the site. From here, runoff is conveyed underneath SE 132"d Street and continues south through an 18-inch diameter tightline conveyance system. This tightline conveyance system is located in a series of drainage easements that run along the lot lines of several residential properties. Eventually, runoff is directed east to a new 36-inch diameter tightline system, located in 142"d Avenue SE, where it is then directed south until it outfalls into an open channel at the intersection of 142"d Avenue SE and SE 136' Street. The channel ultimately drains to the Cedar River several thousand feet downstream of the site. Offsite Analysis and Preliminary Drainage Concept for Windsong—Page 4 Downstream Drainage Problems According to complaints compiled by the King County Water and Land Resources Division(see appendix), past flooding has occurred in the vicinity of SE 133rd Street. Based on a telephone conversation with Wendy Kara at King County, the downstream conveyance system, from the detention facility (see Downstream Drainage Map) to the intersection of 142nd Avenue SE and SE 136" street, will be replaced with a 36-inch diameter tightline conveyance system. It is anticipated that this system, which is to be installed by April of 1999, will eliminate flooding problems in the area. Ms. Kara also mentioned that a large sedimentation pond, located at the mouth of Maplewood Creek, is nearing final construction. The pond was constructed in efforts to reduce sedimentation caused by erosion in the area. Aside from past flooding concerns, which are to be addressed by the proposed drainage improvements, and minor erosion in the drainage channel, it is not anticipated that the Windsong project will have adverse impacts on the downstream drainage system. Offsite Analysis and Preliminary Drainage Concept for Windsong—Page 5 RESOURCES USED FOR ANALYSIS Refer to the appendix for a copy of the following maps and figures. Critical Drainage Areas The site is not located within any of the Critical Drainage Areas listed in the 1990 King County Surface Water Design Manual (KCSWDM). Sensitive Areas Folio Maps from the King County Sensitive Areas Folio , dated December 1990, show that the site is not in a sensitive area with regards to erosion, landslides, or coal mines. The sensitive area folio does, however, depict an unclassified stream flowing near the southwest corner of the site. Also, the sensitive area folio identifies the onsite wetland as King County wetland#150. Flood Plain/Floodway Maps The site is not located within a flood plain as depicted by Maps provided by the Federal Emergency Management Agency (FEMA). King County Wetlands Inventory According to the 1990 King County Wetlands Inventory, Wetland #150 is located along the boundary between the proposed project and the neighboring Highland Market Place project. Refer to the Wetland Inventory Exhibit located in the appendix. King County Basin Reconnaissance Program According to the King County Basin Reconnaissance Program, the site is located within the Lower Cedar River drainage basin and drains to the east branch of Maplewood Creek (tributary 0303). Soils Survey for the King County Area The site is underlain with Alderwood gravelly sandy loam according to the Soils Survey for the King County Area. Refer to the appendix for a copy of the soils map. King County Community Planning Area The site is located within the Newcastle community planning area. Offsite Analysis and Preliminary Drainage Concept for Windsong—Page 6 0 King County Water and Land Resources Division Local Drainage Complaints P A list of drainage complaints compiled by the King County Water and Land Resources Division is located in the appendix. Complaints that are related to the proposed project have been underlined. Reports pertaining to each of these complaints can be requested from King County. DRAINAGE CONCEPT Refer to the Developed Conditions Map, located in the appendix, to aid in the following discussion. The proposed drainage system will consist of a curb and gutter roadway section with catch basins for the interception of runoff associated with onsite areas, including 142n1 Avenue SE. Roof and footing drains from each building will be tied into the conveyance system which in turn will discharge to the combined detention / water quality vault located near the southwest corner of the site. It is anticipated that some of the roof and footing drains will be directed to the onsite wetland in efforts to maintain wetland hydrology. Effluent leaving the vault will pass through a biofiltration swale prior to continuing to the existing tightline system located near the southwest property corner. A tightline conveyance system will replace the existing open ditch along the north side of SE 128 ' Street. Runoff tributary to this system, including upstream flows as well as runoff collected by the proposed curb, gutter and catch basins on the north side of SE 128`' Street, will be conveyed directly to the existing tightline system located near the southwest property corner. A separate tightline conveyance system, located along the east side of 142nd Avenue SE, will convey upstream flows associated with the 142nd Avenue ditch system to the proposed system in SE 128t' Street, thus bypassing the onsite detention facility. Offsite Analysis and Preliminary Drainage Concept for Windsong—Page 7 PRELIMINARY DETENTION CALCULATIONS A combination detention/wet vault has been preliminarily sized to provide storm water runoff control, as well as water quality enhancement, for this project. The proposed facility was preliminarily designed in accordance with the 1990 King County Surface Water Design Manual. Specifically, the allowable release rate for the 2-year, 24-hour developed storm is one-half of the peak rate from the 2-year, 24-hour pre-developed storm. Also, the allowable release rates for the developed 10-year and 100-year storms are the pre-developed peak rates from the 10-year and 100-year storm. In accordance with King County standards a 30% volume correction factor (factor of safety) was applied to the live storage volume. This factor of safety was then increased to account for inaccuracies that may occur during vault construction. The preliminary detention calculations were performed with the computer application Water Works using Santa Barbara Urban Hydrograph (SBUH) methodology with a User 1 (King County Type IA) rainfall distribution resolved to ten-minute time intervals. The site was modeled using separate curve numbers for pervious and impervious areas. A summary of the results of the detention calculations is provided below. Detailed output from the Water Works program (i.e. basin summaries, stage/storage tables, level pool routing tables, etc.) is located in the appendix of this report. Supporting documents used in the detention calculations, such as the Existing and Developed Condition maps along with Table 3.5.2B —W. Washington Runoff Curve Numbers and Washington State Isopluvial maps, are also located in the appendix. Offsite Analysis and Preliminary Drainage Concept for Windsong—Page 8 Combination Detention/Wet Vault The proposed combination detention / wet vault will treat the majority of the site's total runoff. Due to grade limitations, runoff from a portion of the frontage improvements associated with SE 128`h Street (labeled as `Bypass Area") could not be conveyed to the vault. The vault was therefore designed to over-detain flows in order to provide mitigation for the un-detained flows associated with the bypass area. Refer to the Water Works Output, located in the appendix, for a summary of the detention calculations. The vault was sized to accommodate approximately 64,000 cubic feet of live storage. PRELIMINARY WATER QUALITY CALCULATIONS Dead Storage Water quality enhancement will be provided through the use of dead storage in the vault. The volume of dead storage required is the amount of runoff from the 6-month / 24-hour developed conditions storm event using 2/3 of the 2-year precipitation (referred to as the water quality design storm event). Refer to the Water Works Output for the water quality hydrograph. As designed, the vault will provide a minimum of 13,000 cubic feet of dead storage. Biofiltration Swale Effluent leaving the combined detention / wet vault will pass through a biofiltration swale, prior to leaving the site, to provide additional water quality enhancement. The biofiltration swale was sized, according to the 1990 KCSWDM, to provide biofiltration treatment for runoff from the 2-year flow leaving the detention facility (0.39 cfs). The capacity of the swale was sized to accommodate the 100-year un-detained flow leaving the site (10.4 cfs). Refer to the appendix for a summary of the biofiltration swale sizing calculations. Based on preliminary design, the biofiltration swale will be 130 feet long with vertical side slopes, a longitudinal slope of 1.0% and a bottom width of 7 feet. Though the swale is shorter than the required 200 foot length, the bottom width has been adjusted so that the overall surface area at the 2-year flow matches the surface area of the 200 foot swale. Offsite Analysis and Preliminary Drainage Concept for Windsong—Page 9 CONCLUSION Runoff from onsite areas will be collected and conveyed to the combination detention / water quality vault located near the southwest corner of the site. Runoff leaving the proposed detention facility was designed to be at or below existing flow rates. Detained effluent from the vault will pass through a biofiltration swale before leaving the site. Runoff from upstream areas tributary to the site will be collected in separate conveyance systems that do not carry runoff to the proposed vault or biofiltration swale. The drainage system immediately downstream of the site (up to the quarter mile point) appears to have no major capacity or erosion problems. Improvements to the drainage system downstream of the quarter mile point are scheduled to be completed by April of 1999. Given the condition of the downstream drainage system, as well as the restrictive nature of the City of Renton detention standards, adverse impacts to the downstream drainage system are not anticipated at this time. Offsite Analysis and Preliminary Drainage Concept for Windsong—Page 10 I ^ I i P Li - _ • / IY I 4 X 464 , \ X 477 v _ 77 I I X Ixl i 71 4 a�� I .6 x x I i x 4 77 x a X 474 �BR . i.., T R I I 1��_ x X X - X, X---�C I 200 x x x—+x I ='=�,I I `L!' 472 � 1 I I I i o LLi� ❑ X 472 -- I I -IX ' S.J1121 sTJIJI_sT�`_— 'I 1 _ _ -�--j( 1468 (448 -- — -- 1 1463 WI II II I� I � Or� I I ❑ �zf `--- JI ❑ � � x li —[—� 469 L I I ZJ TRI =6 of X446 IX o 2 BRUSH 7 I I O ❑ \ 467 464 II © O X X X 466 X —_J LVr X k i x 63 WLLJCE] AREA TRIB.TO 142"d SYSTEM = 14.65 Ac \ 1 1 BR L AREA TRIB. TO SITE = 3.75 Ac _, --- _=_= 1 I 396 I I ❑ Li Lj AL / 4 � . 44 _ X X T s _� X 4 4 I� on X396 / I 451 TREES x\ � � ❑ f— I � 441 ^ / a \ �, SITE� p xa a i x x 1 y \ �x I � x I � I I I LI 446 El X x l 42, ;I \ — ----- -- -- _ I I 1 1 55KV I I RICH _- ---- - SE TREET __ SW CORNER OF TE -!p"'---� a X/c�' 8r9.•vim FAM 17-(M My A 017 6LO.Gl Scirv, xr 1321.28 1 36 2 b ,4 s2 fps S-Rd /7 45871`SE 128" STREET 87� S E 1 2 E /80.370 19 /3/ i 2 / ¢/. /35• 16 30 2 o i i Q co I� N N co � � A` 1 P` A I 3 9� ' CP o '9 3y � 9 �� ;� .q S �,, I 19155 /•¢/ .14 �j35 •1'1 G60.9S 3a - � 7; APPROXIMATE LOCATION OF DRAINAGE CHANNEL I F P P I I A Rc , o a N V$ 3 , o (j o o P { v qq ' 0.3� 'y1 A' 39430 'S I .r_�h s . - •^ NUMBERING CORRESPONDS TO OFFSITE _ _ ti ►� ANALYSIS DRAINAGE SYSTEM TABLE N• DETENTION FACILITY w I N a DE I � o M 40 tPj '30 'ESrr. t 11 _ /90 _ c c/, 30 /75 l90 /d 68- Z4• lI W /35 !101.55 30 Z N �o0 35 N d- 5 I I SCALE: 1" = 100' vi KC SP 881050 - 1820122OE36 I I m ' � W N %n ( h 4 C M o = LOT I N DRAINAGE CHANNEL LOT 4 ° m N M N n �j qm° `ti ►'-3 by • ONE-QUARTER MILE POINT ui to + tih \1 �^ /o0 f, to 3 /50.48 O Id5 7G•3l TIGHTLINE SYSTEM 11 • ' g y 5 �, •� N _ SE 132°d STREET 3 .- r� � 5 u Z SS.2G 7,¢ ., .. .. 002o r olp f l o"p df'' copo "t D y 1 � 0 0 � o 1. 1 /So./� i0/..fo [e- 5 6V..4'0 649 6D G o4 ro 70� � m APPENDIX • 0 9 OFF-SITE ANALYSIS DRAINAGE SYSTEM TABLE Basin: Cedar River Subbasin Name: _L,ower Cedar Creek Subbasin Number: ............ :.::.;:.;:.::.;:;:.;:::.;::.:.:::::..:::.:::::::::.::...:::;;:.::.:..: . . lxto a «:<:<::>::>;::::>: , <:.on ac ,<: »>:<::.>::>::>::;attao ctt�s ..................Sla >:. x ..:..:...........Pa .............. ........................ ..... . ........... .....:... .......... ....1�......�.......... 8 :::::._? mot. ................. ................ :.; ... .. ... .......... . . . . ....................................................... . ........ ...... .. .. .: : :. :: .........J . , . ..l R .... .r ............:;:;:;::;:;: . . .. .................... .... .. ; . . :. ..:........ ... .. . . n : . .. . .. .. See Map Type: sheet flow, Swale,stream, Drainage basin,vegetation,cover, % Ft Constrictions,under capacity,ponding, Tributary area, likelihood of problem; channel,pipe, depth,type of sensitive area,volume overtopping,flooding,habitat or organism overflow pathways, potential impacts pond; size,diameter, surface area destruction,scouring,bank sloughing, sedimentation,incision,other erosion 1 18 Inch Concrete Culvert under N.E. 4th Street 1 0 - 80 None None None observed. 2 Open Channel Vertical ss, 10' bw, 3' deep 1 80 - 580 Slight erosion Erosion Slight erosion of bank due to earth lined high flows. 3 Open Channel 10' bw, 3:1 ss, V deep, 1 580 - 930 None None None observed. marshy area 4 18 Inch Concrete Culvert Outlet on detention pond 1 930 - 980 None None None observed. 5 Open Channel 3' bw, 2:1 ss, 2' deep, grass 1 980 - 1280 None None None observed. 6 18 Inch Tightline Tightline lined through housing 1 1280 - Flooding Flooding Neighbor reports flooding due development 2000+ to downstream undersized culvert. King County to fix in summer of 1997. Note: The above table was taken from the "Level I Drainage Report for Highland Market Place" prepared by Harghausen Consulting Engineers, Inc. dated October 1997. The above referenced downstream drainage components were field verified on January 12, 1999 by Triad Associates. 6116.004 [BAH/knl JAN. 12. 1999 11:39AM KC WLRD N0.971 P.2i4 COMPLN TY PROBLEM TYPE OF NEW NUMBER PE- ,__-_ -- ADDRESS_-_-_ PROBLEM COMMENTS TH BR_ 75-0135 C 13921 SE 136TH PL FLOG SWAMP/SE 136TH PL/HIDEWAY HTS 656J2 81-0197 C 13832 SE 131ST ST/REN T DRNG . 6LKED 656J2 82-0341 C 14005 SE 133RD ST FLOG 656J2 82-0386 C 12808 136TH AVE SE DRNG It FLOG 656J2 82-0491 C 14009 SE 128TH ST FLOG MAPLEWOOD HTS 656JZ 82-0525 C 16935 116TH AVE SE DVR a SE 132ND/144TH AVE SE 656J2 83-0353 C 13224 144TH AVE SE FLOG 656J2 84-0221 C 14OXX SE 132ND ST DVR FLDG 656J2 85-1010 C 14100 SE 137XD ST DRNG SEE 84-1005/TO ROADS 656J2 86-01D9 C 14011 SE 132ND ST DRNG SURFACE WATER 656J2 86-01D9 C SEE YARN STUDY 656J2 86-0256 F 656J2 86-02S6 C 656J2 86-0256 S1 COMMITTED OATE:IST OTR 1989. 656J2 86-03A4 C 138TH AVE SE DRNG SYSTEM SILTED 656J2 86-03A4 E PROD CRTD. 656J2 86-0739 C 13323 146TH AVE SE FLOG WATER FROM SCHOOL 656J2 87-0255 C 14639 SE 132ND ST FLOG STANDING WATER & MUD 656J2 87-0328 C 13323 146TH AVE SE DRNG CO DIVERTED DRNG ONTO PROPERTY 656J2 87.0405 C 13025 138TH AVE SE FLOG SEE 87.0463 OVER STREET 656J2 87-0445 C 13837 SE 128TH ST FLOG FILLING OF LOT 656J2 87-0445 ER 13837 SE 128TH ST FLOG SEE 86-03A4 PENTON. 87-0707 656J2 1087-0463 X 13025 138TH AVE SE FLOG ON 138TN AVE SE 656J2 -88-0280 C 14106 SE 135TH ST DRNG STRORM DRAIN FAILURE 656J2 89-0036 C 14003 SE 132NO ST DEBRIS DEBRI ON RD TO DET POND 656J2 89-0113 C 13852 SE 128TH AVE DRNG DRAINAGE OF NEIGHBORS 656J2 FILL/ROAD CONST 89-0200 C 13120 138TH AVE SE SETTLING SINK HOLE IN YARD 656J2 a9-0461 S2 14011 SE 132ND ST FLDG/DVR SEE:86-0256 YAHN PH I 656J2 89-0472 X 14105 SE 133RD ST INOUIRY STATUS OF STUDY(YAHN STUDY) 656J2 89-0636 X 14103 SE 132ND ST DRNG YARN STUDY COMPLAINTS 656J2 90-0209 C 14639 SE 132ND ST FLOG DITCH OVERFLOW/STORM EVENT 656J2 90-0388 C 14105 SE 133RD ST DRNG FLOODING IN NBRHD 656J2 90-0512 C 13600 136TH AVE SE DRNG CROSS PIPE ERODING RAVINE 656J2 90-0556 C 13323 146TH AVE SE DRNG DITCH ENDS/DIVERTED WATER 656J2 90-0556 ER 13323 146TH AVE SE DRNG XPIPE AND POND/DITCH ENDS 656J2 90-0804 X 14105 SE 133RD ST FLOG COMPLETION OF STUDY 656J2 90-1511 X 14105 SE 133RD ST FLOG CAPACITY OF PLAT DRNG 656J2 91.0081 Y 14105 S 133RD ST DRNG CCF#191-32/YAHN STUDY/FLOODED 656J2 YARD 91-0081 SR_ 14105 S 133RD ST DRNG PUGET COLONY HOMES 656J2 91-0098 X F14105 SE 133RD ST DRNG CCF#SWM0124/DEVELOPEMENT 656J2 91.0098 SR 14105 SE 133RD ST DRNG CCF#SWM0124 PUGET COLONY HOMES 656J2 91-0246 F 14013 SE 133RD ST DRNG PLUGGED 656J2 91-0246 SR �14013 SE 133RD ST_ DRNG PLUGGED PUGET COLONY HOMES 656J2 91-0315 C 14011 SE 132NO FLOG DIVERSION/CULVERT OVERFLOW 656J2 91-0619 NDA 10403 147TH AVE SE DRAINAGE STORM EVENT - D/W FLOODING 656J2 *91,0636 X 14101 SE 113RD ST FLOG CCF#491-32/PLAT DRAINAGE 656J2 91-0636 NDA 14105 SE 133RD ST FLOG CCF#491-32 NOT NDA PUGET 656J2 � - COLONY HOMES 91-0650 X 14105 SE 133RD ST DRNG CCF#591-2 SAME OLD PROS 656J2 DRAINAGE COMPLAINTS JAN. 12. 1999 11:40RM KC WLRD N0.971 P.3i4 91.0650 NDA 14105 SE 133RD ST DRNG CCF#591.2 NOT NDA PUGET 656J2 COLONY HOMES 91-0682 CL 14105 SE 133RD ST FLDG CCF# 591-2 DUE JULY 656J2 91-0712 X 14103 SE 132ND ST DRNG CCF# SWM 0520 MANY COMP 656J2 91-0712 NDA 14103 SE 132ND ST DRNG CCF# SNM OS20 NOT NDA PUBET 656J2 COLONY HOME 91-0715 C 14105 SE 133RD ST DRAINAGE NEIGHBORHOOD FLOODING 656J2 91.0715 SR 14105 SE 133RD ST DRAINAGE PUGET COLONY HOMES 656J2 91-0729 X 14105 SE 133RD ST DRAINAGE CCF# 591-37 656J2 91-0723 SR 1410 SE 1 1-RDST DRAINAGE CCF# 591.37 PUGET COLONY HOMES 656J2 91-0732 C 14024 SE 1 RD ST DRAINAGE /LAMB (CLAIM) 656JZ 91-0732 SR 14024 BE 13 RD ST DRAINAGE /LAMB (CLAIM) NOT NDAP 656J2 91-0739 SR 14103 SE 132ND ST DRNG/FLD CCF# SUM-0610 NOT NDAP 656J2 91-0777 X 14103 SE 132ND ST FLOODING CCF# 591-39 656JZ 91-0777 NDA 14103 SE 132ND ST FLOODING CCF# 591-39 NOT NDA PUGET 656J2 COLONY 91-0812 C 14639 SE 132ND ST DRAINAGE 656J2 91.0868 X 14010 SE 1347H ST DRAINAGE CCF# SWM0279/PUGET COLONY 656J2 91-0868 SR 14010 SE_134TH ST DRAINAGE CCF# SWM0279 NOT NDAP 656J2 91-0885 X 13405 142ND AVE SE FLOODING CCF# SWM-0854/DRAINAGE 656J2 IMPROVEMENTS 91-0888 X 13800 SE 128TH ST FLOODING CCF# SWM-0852WETLAND PROBLEMS 656J2 91-08U SR 13800 SE 128TH ST FLOODING CCF#SWM-0852-NOT NDA-PUGET 656J2 COLONY HOMES 91.0946 X 14105 SE 133RD ST DRAINAGE CCF#: 91-0822/GRANTING 656J2 EASEMENTS 91-1214 X 14105 SE 133RD DRAINAGE CCF# SWM 1217/PROJECT SCHEDULE 656J2 93-0179 C 137XX 144TH AVE SE DIVERSON POSS CLEARING VIOLATION 656J2 93-0224 C 12217 148TH AV SE PONDING POSSIBLE SAO VIOLATION/DITCH 656J1 ENCROACH 93-0239 X 14105 SE 133RD ST INQUIRY INFO ONLY 656H2 93-1064 C 14400 SE 136TH ST FLDG GROUND WATER UNDER ROADWAY 656J2 93-1085 ER 14600 SE 132ND ST DRNG 656J2 93-1085 E 146DO SE 132ND ST DRNG CHKSTATBYCMDT 656J2 95-0763 C 14010 SE 134TH ST VACATION DRAINAGE IMPACT FROM VACATION 656H2 REQUEST 95-0788 C 14328 SE 128TH ST OISCHARG COMPLAINT REQU NO INV2 THIS 656J1 TIME 95-D991 WQC 12516 142ND AVE SE DUMPING APPARENT PROPERTY DISPUTE 656J1 96-0880 WOC 14328 SE 128TH ST EROSION 656J1 96-1283 C 140TH SE 132NO -135TH SE CIP REQUEST TO 00 ASSESSMENT OF 656H2 CONVEYANC[ 96-1291 C 128TH SE & 149TH AVE SE MPLWDTRB DOWNSTREAM IMPACT TO ROAD 656H1 CROSS CULVERT 96-1401 C SE 128TH B 142WD A SE FLDG MAINTENANCE OF EXISTING 656J1 CHANNNEL 97-0055 C 14105 SE 133RD ST FLDG PUGET COLONY HOMES 656J2 97-0055 R. 14105 SE 133RD ST FLDG PUGET COLONY HOMES 656J2 97-0055 NDA 14105 SE 133RD ST FLDG PUGET COLONY HOMES 656J2 97-0715 FCR 13845 SE 131ST ST R/D FENC TREE DAMAGED FENCE ROADS 656HZ FACILITY 97-1378 C 14004 SE 133RD ST DRAINAGE LOCALIZED DEPRESSION PUGET 656H2 COLONY HOMES 97-1378 R 14004 SE 133RD ST DRAINAGE LOCALIZED DEPRESSION PUGET 656H2 COLONY HOMES 97-1380 C 14005 SE 133RD ST DRAINAGE LOCALIZED DEPRESSION PUGET 656H2 COLONY HOMES 97-1464 C 132XX 140TH AVE SE DRAINAGE OFFSITE CONVEYANCE DRAIN QUEST 656H2 CHK SP 97-1625 WOA 14413 SE 128TH ST BMPIS 656J1 DRAINAGE COMPLAINTS JAN.12. 1999 11:40AM KC WLRD N0.971 P.4i4 98-0360 C 14454 SE 132NO ST DRAINAGE APPEARS PRE GRADING ACTIVITY 656J2 NO PERMIT 98-0534 WOC 13224 144TH AVE SE WASHWATE APPARENT GREY WATER DISCHARGE 656J2 98-0534 WOR 13224 144TH AVE SE WASHWATE APPARENT GREY WATER DISCHARGE 656J2 DRAINAGE COMPLAINTS RHO - Owl E !►�; r ral -•�=--' ram i, 7i iwi Am.� 411112 Los Qr um 4 �Mrnnu on mow, >na� r arcs- s m,. r ��tt�:i r�ls'9���,, �� �� � � i. � //' \ roc �- •� =s .. u WIN PAN s wtapi, low s .:a — I�'AN AnWOM Ric' i A WK � III vftW Is WA .�. 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'�11$14 ► �J �� MIA via Ali�. :� __ _ ='FASE SA -r e' ds MANy ` �■-,: nisi r UNA pe 1611S.,; Intl 0 - r16MI1r 4;,. 122°09'22" '30'00" JOINS PA CITY OF RENTON SOUTHEAST 116TH STREET KING COUNTY I� W Q 0 a � SOUTHEF 0 U I CITY OF RENTON 530088 SOUTHEA I SOUTHEAST 121ST STREET w Z 0 o z 10 N WI0 !r 0 U— U w 0 U zLu } Z _ ]G a U CITY OF RENTON 530088 SOUTHEAST 126TH STREET l000r U _1 SITE 0 a STREET SOUTHEAST Q x O N SOUTHEAST 129TH PLACE FEMA MAP i `1x a«x i v Y a. v ' pool" _ y- SF 128th St sv: � a F nr' Photo Date: 7/23/89 Inventory Date: 8/7/90 NA Scale: 1"=500' WETLAND: Lower Cedar River 150 COMMUNITY PLAN AREA: Tahoma/Raven Heights LOCATION BASIN OR (S,T,R): SW-SE 10, 23N,5E DRAINAGE: Cedar River ACREAGE: 11.0 SENSITIVE AREA MAP#: 4 CLASSIFICATION: Fish &Wildlife Service Common Name PSSI Palustrine Scrub-Shrub Broad- Scrub-Shrub leaved Deciduous (Hardhack) P> j1 Palustrine Forested Broad- Forested leaved Deciduous (Alder) NOTE: Wetland boundaries shown are approximate. rurtner field studies are necessary to confirm the actual delineation o1 the wetland according to the Federal Manual for Identifying and Delineating Jurisdictional Wetlands. WETLAND INVENTORY MAP Lower Cedar River 150 :.."SERVED SPECIES (refer to Appendix 1): 0 Trees: PT AR TP Shrubs: AC RP RV VP RS SX SD Herbs: MU RR UD TT SZ DF Sedges/Grasses/Ferns: AF CX DR LP Birds: AR BC Mammals: CT Fish: Other: HYDROLOGY: Inlet: Type: Undetermined. Condition: Outlet: Type: Culvert. Condition: Outflow enters: Undetermined. Water movement through wetland: Channel flow with some movement - standing flow. Observed water quality in wetland: Evidence of water level fluctuations and vernal wet spots. SIGNIFICANT HABITAT FEATURES: Numerous snags - some greater than 25 feet high. GENERAL OBSERVATIONS: Wetland extends north-south across heavily traveled road (SE 128th Street). The southern portion of the wetland (south of SE 128th Street) was partially filled approximately four years ago and some areas have been cleared the last year. Wetland has intermittent stream on western edge. Vernal ponds observed in spring. Additional information on this wetland has been collected by King County Surface Water Management Division. WETLAND RATING (see Introduction for criteria): 2 NOTE: Species fisted are only those observed during field visits. Further field studies are necessary to obtain a w►npletc►ist including rare, threatened,and/or endangered species. LOWER CEDAR RIVER BASIN Basin Boundary fi� y, ^T' " Subcatchment Boundary I . au ,. O Collection Point Stream SITE j 0299 Tributary Number s, I k "HV ,,,d, 03115 Proposed Project �y +I <+Q y c� = S X C � � ento 2 o,' z Miles X s x , r III ' y s July,1987 R • J 3105 26 \ ` e o LA 11 �l 3121 1 : 3116 3122 1 g' 0 P; n X :n V i, I sr e t 0 0 9 Trib. & Collect. Existing Anticipated Item River Mile Point Category Prop. PrOL Conditions and Problems Conditions and Problems Recommendations 16 0302 6 Geology Gully erosion from broken None. Culvert has been None. culverts. repaired. 17 0302 6 Geology Severe gullyerosion RM .60-.30 Continued erosion. Tightline flows to creating small valleys main stem. from daylight culverts. 14 0302 6 Habitat Stream channeled along While fish now use this RM.35 Add habitat diversity golf course road. No reach, lack of habitat will (e.g., structures, overhead overhead cover. No habi- eventually reduce popula- vegetation). Gain tat diversity. tions. easement to restore mean- ders, if possible. 19 0302 6 Hydrology Tributary drains down Problem will worsen as RM .45 Construct detention dam steep bluffs on north development upstream upstream of golf course, side of Cedar River, continues. carrying debris and tz flooding Maplewood Golf Course. 20 0302 6 Habitat Water supply dam. Full As impoundment fills, storm- Dredge pond and maintain RM .50 barier to upstream water will flood over bank. it as sediment catch. migration. Impoundment Structure may fail. is filling with sediment. 21 0302 6 Habitat Severe gullying from right Will continue to erode until - Tightline downslope. RM .90 bank corregated metal reaches till layer. - Add velocity attenuator at Z pipe. Heavy sediment stream. Zdelivery to stream. ^ P: LC.APC C 4 Trib. & Collect. Existing Anticipated Item River Mile Point Category Prop. Proi. Conditions and Problems Conditions and Problems Recommendations 10 0299.1A 21 Hydrology 3116 Frequent flooding of Road located on top of peat Elevate the road 34' by RM .08 county road caused by low bog and will continue to filling on top of the road embankment. settle, aggravating flooding present road embankment. problem. Also stabilize embankment. 11 0300 4 Geology Extensive channel and Problems will continue. Provide adequate R/D in RM .00-.40 bank erosion and numerous uplands. (See Project landslides due to 3119.) development-related stormwater. 12 0300 4 Hydrology 3119 Development-related peak Increased erosion on Construct detention dam in flows have caused sig- hillslopes below. deep, channelized reach of nificant bank erosion. Trib. 0300. 13 0300 4 Hydrology 3109 Collection point 4 has Degradation of Trib. 0300 RM 1.40 Construct berm and standard been nearly completely from RM .42 downstream. This control structure at outlet urbanized. section is very steep and to Wetland 3120 in Cascade susceptible to erosion. Park. 'Z 14 0302 6 Geology Channel downcutting and Will continue at same level Control storm flows from RM .50 bank erosion. or increase. uplands. 15 0302 6 Geology Bank erosion (medium den- Increasing erosion with Provide adequate R/D in RM .80-1.00 sity) at meanders and increasing flow from devel- uplands as area develops. O - obstructions. opments. '� P: LC.APC C-3 Trib. & Collect. Existing Anticipated Item River Mile Point Category _prop, Proi. Conditions and Problems Conditions and Problems Recommendations 22 0302 6 Habitat Trash in stream (auto, RM 1.00 Area adjacent to corridor, - Remove trash. tires, appliances). will continue to collect - Distribute educational trash and debris. Further materials to streamside worsening of water quality, residents. sedimentation, erosion. - Cite violators, if problem persists. 23 0302 6 Habitat Trash in stream. Water Area adjacent to corridor,RM 1.10 unlit problem, - Remove trash. quality P will continue to collect - Distribute educational unsightly. trash and debris. Further materials to streamside worsening of water quality. residents. Cite violators, if problem persists. 24 0303 6 Geology Extensive bank erosion in None. Increase R/D volumes, slow release upper portions of tribu- rate to nonerosive levels. tary. 25 0303 6 Habitat Habitat suitable for resi- S RM .25 Sediments will eventual)Y - Control stormwater volumes FBI dent fish. Sediment accu- cover gravels. Habitat and discharge rates from mulating. will become unsuitable for developments. Fey fish use. - Manually clean gravels [crJ when necessary. 26 0303 6 Habitat Trash and litter in Further decreases in water - Remove trash and litter. O RM .35 channel affecting water quality. - Distribute educational materials quality, causing erosion. to streamside residents. Z - Cite violators, if problem persists. 00 CA P: LC.APC C-5 it WNElkin awl 'F4 � b{ •r s. l yr. g- �.yltr mg 4 ¢ �y ';•+s*'7Ycdli>e4aa..C*, #a'. / 1 '\ ' U• (ram � i4c. �a y rPil's..!'Csxa2 . !° 40 k s Y$jwt -VU s ••4 E 1 mop, for gat i a �•� ; PIT Mir *Z4 - ► rj SHEET NO. i i KING COUNTY AREA, WASHINGTON (RENTON QUADRANGLE) 1680000 FEET 122' T30" 47'30' AgD •413� o AgC �� •.. 'BN AgC 1 9 5 E • Age .1 • •• ___ _ •• =SITE -Trailer .• •• ��; :Ev6 S; J. ark'.•• u I; II - . .B II ' B =. 3 •• 424 .. •I• 46 CID •.V ....... I •'•' r p I 180 000 • ASC •ti „`• FEET •406 III �``�p - \ •_ • � i _ • • III I \�\ ' --------I AgC I AkF I BMttt II I •• •,II•. 3 •II M Ev6 -- —t-------- a p._ PY " c I o •he f / Co..- 1 a�. Eve / se •AkFRh I J °• • Qc• , I ., AkF •�• F .^• Py e- I �. o II /C M e `. Pc •i• �/ >p I Ma clP•• ii ij/ d loNg I•• �• - ,Py W °I 0• �� II I• Q _�_\ + \iif' •II yFillOt Pc •Rh W Q. AkF I e.-- ur Eir Q o I se r a c) AkF Park IN 4 F AgC I Py EvC AgC I �I I B Q AgD AkF 2 __ __ ____ ] I - -- •- _ --�--- -----° BMo^ o BM 27'30„ 1 A B I °--- 82__°_-`4 _._. AgC I I ° AgD gC I AgD I AkF BMp 428 J I Age A B � I Age _ P/PELINE AgC Ur 27 1 , 2 ---- I q. � a921 SOILS MAP _= No I SOIL LFGEND , The first capital letter is the initial one of the soil name. A second capitol letter, A, B, C, O, E, or F, indicates the class of slope. Symbols without a slope letter are those of nearly level soils. SYMBOL NAME A98 Alderwood gravelly sandy loom,0 to 6 percent slopes AaC Alderwood gravelly sandy loam,6 to 15 percent slopes AgD Alderwood gravelly sandy loam, 15 to 30 percent slopes AkF Alderwood and Kitsap soils,very steep AmB Arents,Alderwood material,0 to 6 percent slopes AmC Arents,Alderwood material,6 to 15 percent slopes n An Arents, Everett material s BeC Beausite gravelly sandy loam,6 to 15 percent slopes BeD Beausite gravelly sandy loam, IS to 30 percent slopes BeF Beausite gravellysardy-loam,-AO-to 75 Perccnt mlapeo Bh Bellingham silt loam Br Briscot silt loam B. Buckley silt loam Cb Coastal Beaches Ea Earimont silt loam Ed Edgewick fine sandy loam EvB Everett gravelly sandy loam, 0 to 5 percent slopes EvC Everett gravelly sandy loam,5 to 15 percent slopes EvD Everett gravelly sandy loam, 1S to 30 percent slopes EwC Everett-Alderwood gravelly sandy looms,6 to 15 percent slopes InA Indianola loamy fine sand,0 to 4 percent slopes InC Indianola loamy fine sand,4 to 15 percent slopes InD Indianola loamy fine sand, 15 to 30 percent slopes KpB Kitsap silt loam,2 to 8 percent slopes KpC Kitsap silt loam,8 to 15 percent slopes KpD Kitsap silt loam, 15 to 30 percent slopes KsC Klaus gravelly loamy sand,6 to 15 percent slopes Ma Mixed alluvial land NeC Neilton very gravelly loamy sand, 2 to 15 percent slopes Ng Newberg silt loom Nk Nooksock silt loom No Norma sandy loom Or Orcas peat Os Oridia silt loam OvC Ovall gravelly loam,0 to 15 percent slopes OvD Ovall gravelly loom, 15 to 25 percent slopes O.F Ovall gravelly loam,40 to 75 percent slopes Pc Pilchuck loamy fine sand Pk Pilchuck fine sandy loam Pu Puget silty clay loam Py Puyallup fine sandy loam RaC Rognar fine sandy loam,6 to 15 percent slopes RaD Rognar fine sandy loam, 15 to 25 percent slopes RdC Rognar-Indianola association,sloping s RdE Rognar-Indianola association,moderately steep s Re Renton silt loam - Rh Riverwash So Sala[silt loam Sh Sammomish silt loom Sk Seattle muck Sm Shalcar muck So SI silt loam So Snohomish silt loam Sr Snohomish silt loam,thick surface variant Su Sultan silt loom Tu Tukwila muck Ur Urban land Wo Woodinville silt loam • The composition of these units is more variable than that of the others in the area,but It has.been controlled well enough to interpret for the expected use of the soils. KING COUNTY, WASIII NGTON, SURFACE WATER DESIGN MANUAL (2) CN values can be area weighted when they apply to pervious areas of similar CN's (within 20 CN points). However, high CN areas should not be combined with low CN areas (unless the low CN areas are less than 15% of the subbasin). In this case, separate hydrographs should be generated and summed to form one hydrograph. FIGURE 3.5.2A HYDROLOGIC SOIL GROUP OF THE SOILS INKING COUNTY HYDROLOGIC HYDROLOGIC SOIL GROUP GROUP* SOIL GROUP GROUP* Alderwood C Orcas Peat D -Arents, AI erwood Material —� Oridia D Arents, Everett Material B Ovall C Beausite C Pilchuck C Bellingham D Puget D Briscot D Puyallup B" Buckley D Ragnar B Coastal Beaches Variable Renton D Earlmont Silt Loam D Riverwash Variable Edgewick C Salal C Everett A/B ',Sammamish D Indianola A Seattle D Kitsap C Shacar D Klaus C Si Silt C Mixed Alluvial Land Variable Snohomish D Neilton A Sultan C Newberg B Tukwila D 0 Nooksack C Urban Variable Normal Sandy Loam D Woodinville D HYDROLOGIC SOIL GROUP CLASSIFICATIONS A. (Low runoff potential). Soils having high infiltration rates, even when thoroughly wetted, and consisting chiefly of deep, well-to-excessively drained sands or gravels. These soils have a high rate of water transmission. B. (Moderately low runoff potential). Soils having moderate infiltration rates when thoroughly wetted, and consisting chiefly of moderately fine to moderately coarse textures. These soils have a moderate rate of water transmission. C. (Moderately high runoff potentiai). Soils having slow infiltration rates when thoroughly wetted, and consisting chiefly of soils with a layer that impedes downward movement of water, or soils with moderately fine to fine textures. These soils have a slow rate of water transmission. D. (High runoff potential). Soils having very slow infiltration rates when thoroughly wetted and consisting chiefly of clay soils with a high swelling potential, soils with a permanent high water table, soils with a hardpan or clay layer at or near the surface, and shallow soils over nearly impervious material. These soils have a very slow rate of water transmission. From SCS, TR-55, Second Edition, June 1986, Exhibit A-1. Revisions made from SCS, Soil Interpretation Record, Form #5, September 1988. BASIN SUMMARY BASIN ID: Al NAME:2 YEAR EXISTING SBUH METHODOLOGY TOTAL AREA..: 12.12 Acres BASEFLOWS 0.00 cfs RAINFALL TYPE..: USERI PERVIOUS AREA PRECIPITATION..: 2.00 inches AREA..: 11.48 Acres TIME INTERVAL..: 10.00 min CN..: 81.17 TIME OF CONC..: 52.78 min IMPERVIOUS AREA ABSTRACTION COEFF : 0.20 AREA..: 0.64 Acres CN..: 98.00 TcReach-Sheet L: 300.00 ns:0.4000 p2yr:2.00 s:0.0540 TcReach-Shallow L:215.00 ks:5.00 s:0.0960 TcReach-Channel L: 55.00 kc:42.00 s:0.0350 TcReach-Shallow L:240.00 ks:5.00 s:0.0350 TcReach-Channel L:440.00 kc:17.00 s:0.0420 RATE: 0.78 cfs VOL: 0.68 Ac-ft TIME: 490 min BASIN ID:A2 NAME: 10 YEAR EXISTING SBUH METHODOLOGY TOTAL AREA..: 12.12 Acres BASEFLOWS 0.00 cfs RAINFALL TYPE..: USERI PERVIOUS AREA PRECIPITATION..: 2.95 inches AREA..: 11.48 Acres TIME INTERVAL..: 10.00 min CN..: 81.17 TIME OF CONC..: 52.78 min IMPERVIOUS AREA ABSTRACTION COEFF : 0.20 AREA..: 0.64 Acres CN ....: 98.00 TcReach-Sheet L: 300.00 ns:0.4000 p2yr: 2.00 s:0.0540 TcReach-Shallow L:215.00 ks:5.00 s:0.0960 TcReach-Channel L: 55.00 kc:42.00 s:0.0350 TcReach-Shallow L:240.00 ks:5.00 s:0.0350 TcReach-Channel L:440.00 kc:17.00 s:0.0420 RATE: 1.99 cfs VOL: 1.38 Ac-ft TIME: 490 min BASIN ID: A3 NAME: 100 YEAR EXISTING SBUH METHODOLOGY TOTAL AREA..: 12.12 Acres BASEFLOWS 0.00 cfs RAINFALL TYPE..: USERI PERVIOUS AREA PRECIPITATION..: 3.95 inches AREA..: 11.48 Acres TIME INTERVAL..: 10.00 min CN..: 81.17 TIME OF CONC..: 52.78 min IMPERVIOUS AREA ABSTRACTION COEFF : 0.20 AREA..: 0.64 Acres CN. ...: 98.00 TcReach-Sheet L: 300.00 ns:0.4000 p2yr:2.00 s:0.0540 TcReach- Shallow L: 215.00 ks:5.00 s:0.0960 TcReach-Channel L: 55.00 kc:42.00 s:0.0350 TcReach-Shallow L: 240.00 ks:5.00 s:0.0350 TcReach-Channel L:440.00 kc:17.00 s:0.0420 PEAK RATE: 3.49 efs VOL: 2.20 Ac-ft TIME: 490 min File: 952440ut Windsong Water Works Output 1/6/99-bkp BASIN SUMMARY BASIN ID: B 1 NAME: 2 YEAR DETAINED AREA SBUH METHODOLOGY TOTAL AREA..: 11.82 Acres BASEFLOWS 0.00 cfs RAINFALL TYPE..: USERI PERVIOUS AREA PRECIPITATION..: 2.00 inches AREA..: 5.30 Acres TIME INTERVAL..: 10.00 min CN..: 86.00 TIME OF CONC..: 5.00 min IMPERVIOUS AREA ABSTRACTION COEFF : 0.20 AREA..: 6.52 Acres CN..: 98.00 PEAK RATE: 4.34 cfs VOL: 1.34 Ac-ft TIME: 470 min BASIN ID: B2 NAME: 10 YEAR DETAINED AREA SBUH METHODOLOGY TOTAL AREA..: 11.82 Acres BASEFLOWS 0.00 cfs RAINFALL TYPE..: USERI PERVIOUS AREA PRECIPITATION..: 2.95 inches AREA..: 5.30 Acres TIME INTERVAL..: 10.00 min CN..: 86.00 TIME OF CONC..: 5.00 min IMPERVIOUS AREA ABSTRACTION COEFF : 0.20 AREA..: 6.52 Acres CN..: 98.00 PEAK RATE: 7.24 cfs VOL: 2.19 Ac-ft TIME: 470 min BASIN ID: B3 NAME: 100 YEAR DETAINED AREA SBUH METHODOLOGY TOTAL AREA..: 11.82 Acres BASEFLOWS 0.00 cfs RAINFALL TYPE..: USERI PERVIOUS AREA PRECIPITATION..: 3.95 inches AREA..: 5.30 Acres TIME INTERVAL..: 10.00 min CN..: 86.00 TIME OF CONC..: 5.00 min IMPERVIOUS AREA ABSTRACTION COEFF : 0.20 AREA..: 6.52 Acres CN..: 98.00 PEAK RATE: 10.40 cfs VOL: 3.12 Ac-ft TIME: 470 min File: 952440ut Windsong Water Works Output 1/6/99-bkp BASIN SUMMARY BASIN ID: C 1 NAME: 2 YEAR BYPASS AREA SBUH METHODOLOGY TOTAL AREA..: 0.30 Acres BASEFLOWS 0.00 cfs RAINFALL TYPE..: USER1 PERVIOUS AREA PRECIPITATION..: 2.00 inches AREA..: 0.26 Acres TIME INTERVAL..: 10.00 min CN..: 86.00 TIME OF CONC..: 5.00 min IMPERVIOUS AREA ABSTRACTION COEFF 0.20 AREA..: 0.04 Acres CN..: 98.00 PEAK RATE: 0.07 cfs VOL: 0.02 Ac-ft TIME: 470 min BASIN ID: C2 NAME: 10 YEAR BYPASS SBUH METHODOLOGY TOTAL AREA..: 0.30 Acres BASEFLOWS 0.00 cfs RAINFALL TYPE..: USER1 PERVIOUS AREA PRECIPITATION..: 2.95 inches AREA..: 0.26 Acres TIME INTERVAL..: 10.00 min CN..: 86.00 TIME OF CONC..: 5.00 min IMPERVIOUS AREA ABSTRACTION COEFF 0.20 AREA..: 0.04 Acres CN..: 98.00 PEAK RATE: 0.14 cfs VOL: 0.04 Ac-ft TIME: 470 min BASIN ID: C3 NAME: 100 YEAR BYPASS SBUH METHODOLOGY TOTAL AREA..: 0.30 Acres BASEFLOWS 0.00 cfs RAINFALL TYPE..: USER1 PERVIOUS AREA PRECIPITATION..: 3.95 inches AREA..: 0.26 Acres TIME INTERVAL..: 10.00 min CN..: 86.00 TIME OF CONC..: 5.00 min IMPERVIOUS AREA ABSTRACTION COEFF 0.20 AREA..: 0.04 Acres CN..: 98.00 PEAK RATE: 0.22 cfs VOL: 0.07 Ac-ft TIME: 470 min File: 952440ut Windsong Water Works Output 1/6/99-bkp BASIN SUMMARY BASIN ID: WQ NAME: WATER QUALITY SBUH METHODOLOGY TOTAL AREA..: 11.82 Acres BASEFLOWS 0.00 cfs RAINFALL TYPE..: USER1 PERVIOUS AREA PRECIPITATION..: 0.67 inches AREA..: 5.30 Acres TIME INTERVAL..: 10.00 min CN..: 86.00 TIME OF CONC..: 5.00 min IMPERVIOUS AREA ABSTRACTION COEFF 0.20 AREA..: 6.52 Acres CN..: 98.00 PEAK RATE: 0.88 cfs VOL: 0.28 Ac-ft TIME: 470 min HYDROGRAPH SUMMARY DESCRIPTION HYD PEAK TIME VOLUME AREA NUM CFS Min CF Ac 2 YEAR EXISTING 1 0.780 490 29622 12.12 10 YEAR EXISTING 2 1.988 490 59907 12.12 100 YEAR EXISTING 3 3.492 490 95857 12.12 2 YEAR DETAINED AREA 4 4.337 470 58329 11.82 10 YEAR DETAINED AREA 5 7.238 470 95502 11.82 100 YEAR DETAINED AREA 6 10.404 470 136048 11.82 2 YEAR BYPASS AREA 7 0.071 470 1059 0.30 10 YEAR BYPASS AREA 8 0.141 470 1923 0.30 100 YEAR BYPASS AREA 9 0.221 470 2900 0.30 WATER QUALITY 10 0.879 470 12401 11.82 2 YEAR OUTFLOW 12 0.370 1460 48127 11.82 10 YEAR OUTFLOW 13 1.577 650 84776 11.82 100 YEAR OUTFLOW 14 3.411 520 125295 11.82 2 YR TOTAL RELEASE(HYD 7+HYD12) 18 0.381 1440 49186 12.12 10 YR TOTAL RELEASE(HYD 8+HYD13) 19 1.610 650 86700 12.12 100 YR TOTAL RELEASE(HYD 9+HYD 14) 20 3.486 520 128195 12.12 Note: The total release from the site is the sum of the detention facility outflow hydrographs and the sum of the bypass area hydrographs. For each storm event,the total release from the site does not exceed the allowable release rates from the site. File: 952440ut Windsong Water Works Output 1/6/99-bkp THEORETICAL STAGE/STORAGE/DISCHARGE TABLE RECTANGULAR VAULT ID No. V Description: Theoretical detention structure Length: 120.00 ft. Width: 50.00 ft. STAGE STORAGE STORAGE DISCHARGE [FT] [CF] [Ac-FT] [CFS] 100.00 0 0.0000 0.0000 100.50 3000 0.0689 0.1062 101.00 6000 0.1377 0.1502 101.50 9000 0.2066 0.1839 102.00 12000 0.2755 0.2124 102.50 15000 0.3444 0.2375 103.00 18000 0.4132 0.2601 103.50 21000 0.4821 0.2810 104.00 24000 0.5510 0.3004 104.50 27000 0.6198 0.3186 105.00 30000 0.6887 0.3358 105.50 33000 0.7576 0.3522 106.00 36000 0.8264 0.3679 106.50 39000 0.8953 2.0034 107.00 42000 0.9642 3.0436 107.20 43200 0.9917 3.3616 107.30 43800 1.0055 3.5087 MULTIPLE ORIFICE ID No. 0 Description: Outlet Elev: 100.00 Elev: 98.00 ft Orifice Diameter: 2.3525 in. Elev: 106.20 ft Orifice 2 Diameter: 10.4414 in. THEORETICAL LEVEL POOL TABLE SUMMARY Description Inflow Storage Dischrg P. Stage Volume Outflow P.Time CFS ID ID FT CF] [CFS] [Min 2 Year Outflow 4.34 V 0 106.06 36356 0.370 1460 10 Year Outflow 7.24 V O 106.37 38207 1.577 650 100 Year Outflow 10.40 V 0 107.23 *43401 3.411 520 *Theoretical volume of live storage=43,401 cubic feet. File: 952440ut Windsong Water Works Output 1/6/99-bkp K I N G COU N "I- Y. WAS 11 1 N G I' O N, S U R f= A C E W A '1' E; R DESIGN MAN U A L TABLE 3_5.28 SCS WESTERN 1VAS111NCTON RUNOFF CURVE NUMBERS SCS WESTERN WASHINGTON RUNOFF CURVE NUMBERS (Published by SCS in 1982) Runoff curve numbers for selected agricultural, suburban�and=urbannd use for Type 1A rainfall distribution, 24-hour storm duration. CURVE NUMBERS BY HYDROLOGIC SOIL GROUP LAND USE DESCRIPTION A B C D FMeadow nd(1): winter condition 86 91 94 95 en areas: low growing brush and grasslands 74 82 89 92 pasture: 65 78 85 89est land: undisturbed or older second growth 42 64 81est land: young second growth or brush 55 72 St 86 with cover crop 81 88 94 Open spaces, lawns, parks, golf courses, cemeteries, landscaping. good condition: grass cover on 75% fair condition: or more of the area 68 80 ® 90 grass cover on 50% to 75% of the area 77 85 90 92 Gravel roads and parking lots 76 85 91 Dirt roads and parking lots 72 82 89 • Impervious surfaces, pavement, roofs, etc. 98 98 98 98 Open water bodies: lakes, wetlands, ponds, etc. 100 100 T60 100 Single Family Residential (2) Dwelling Unit/Gross Acre % Impervious (3) 1.0 DU/GA 15 Separate curve number 1.5 DU/GA 20 shall be selected 2.0 DU/GA 25 for pervious and 2.5 DU/GA 30 impervious portion 3.0 DU/GA 34 of the site or basin 3.5 DU/GA 38 4.0 DU/GA 42 4.5 DU/GA 46 5.0 DU/GA 48 5.5 DU/GA 50 b;�5 6.0 DU/GA 52 6.5 DU/GA 54763 7.0 DU/GA 56 Planned unit developments, % impervious condominiums, apartments, must be computed commercial business and industrial areas. (1) For a more detailed description of agricultural land use curve numbers refer to National Engineering Handbook, Section 4, Hydrology, Chapter 9, August 1972, (2) Assumes roof and driveway runoff is directed into street/storm system. (3) The remaining pervious areas (lawn) are considered to be in good condition for these curve numbers. 3.5.2-3 1 I/9'' Flair AM All _ a opo- AIR Ik ._��. AV ,f 29 • w�=f o - G • 1 .+ CIE:■ �,'e�i �i�`, i���►�� �1 �::�•► �� Mm �! ,-yak VA F i of off t • t • � t „ • DIN , , , rw Poidin it ��� till 1 � � I CIO �qLv-Ne . lip lolllip a ail/,tl' 0. 1 `' ' f •� �� ... i Pax. Jjj �41P� ■i .� NMI � - ram/ ��• � - ;•. • MAR 1 _ low • • . � � • wM • WINDSONG Input Output Q (cfs) 0.00 0.39 n 0.350 0.350 B (ft) 4.52 4.52 Trap. LSSlope 0.00 0.00 RSSlope 0.00 0.00 y(ft) 0.33 0.33 S (ft/ft) 0.020 0.020 L (ft) 130.000 130.000 t(min) 0.000 8.276 _ A(sf) 1.491 Pw (ft) 5.177 V(ft/s) 0.262 R (ft) 0.288 Job: 95-244 Description: Design Biofiltration Swale -2 Yr Flow By: BKP Date: 1/13/99 0 0 BIOFILTRATION SWALE CALCULATIONS WINDSONG Input Ou tput utput Q (cfs) 0.00 0.39 n 0.027 0.027 B (ft) 7.00 7.00 Trap. LSSlope 0.00 0.00 RSSlope 0.00 0.00 y(ft) 0.06 0.06 S (ft/ft) 0.010 0.010 L (ft) 130.000 130.000 t (min) 0.000 2.488 A(sf) 0.449 Pw(ft) 7.128 V(ft/s) 0.871 R(ft) 0.063 Job: 95-244 Description: Actual Bioswale-2 yr flow By: BKP Date: 1/13/99 BIOFILTRATION SWALE CALCULATIONS WINDSONG Input Output Q(cfs) 0.00 10.40 n 0.027 0.027 B (ft) 7.00 7.00 Trap. LSSlope 0.00 0.00 RSSIope 0.00 0.00 y(ft) 0.48 0.48 S (ft/ft) 0.010 0.010 L (ft) 130.000 130.000 t(min) 0.000 0.700 A(sf) 3.359 Pw (ft) 7.960 V(ft/s) 3.096 R(ft) 0.422 Job: 95-244 Description: Actual Bioswale- 100 Year Flow By: BKP Date: 1/13/99 BIOFILTRATION SWALE CALCULATIONS IFSECTION IV voommumm" RETENTION/DETENTION ANALYSIS & DESIGN • SECTION IV : DETENTION ANALYSIS and DESIGN The drainage basin for this project, refereed to as the onsite drainage basin, is approximately 11.88 acres and is comprised of onsite areas as well as areas associated with Hoquiam Avenue NE. In addition to the 11.88-acre basin associated with the development of this project, runoff from approximately 3.75 acres of upstream offsite area is tributary to the site. In general, stormwater runoff from the drainage basin, as well as runoff from the 3.75 acres of upstream area, will be collected via a closed pipe network and discharged to the proposed detention/water quality pond. Refer to the Existing Condition, Developed Condition and Upstream Area exhibits located in the Appendix at the end of this report. Based on conversations with City of Renton Personnel (Paul Lumbert and Neil Watts), the live storage volume of the pond was determined based on methods outlined in the 1990 King County Surface Water Design Manual (KCSWDM). It was agreed that the e�rX of the combination detention/water quality pond could, however, be designed per the 1998 KCSWDM which allows for a more efficient pond layout. The detention calculations were performed using Engenious Systems Inc.'s hydrology program Water Works. Hydrographs were developed using S.B.U.H. methodology with a King County Type I-A (User 1) 24-hour rainfall distribution. Separate S.C.S. curve numbers were used for the impervious and pervious portions of the site. Using the onsite existing condition hydrographs, the onsite allowable release rates were determined for the site based on recommendations outlined in the Mitigated Determination of Non-Significance (SEPA) obtained from The City of Renton. Specifically, ...the 2-year/24-hour stormwater release rate for the developed site shall be limited to 50% of the pre-developed 2-year/24-hour flow rate. The release rate for • TECHNICAL INFORMATION REPORT FOR WINDSONG PAGE: IVA the developed site for the 5, 10 and 100 year /24-hour storm events shall be limited to pre-developed rates for these storm events. The onsite developed condition hydrographs were then routed through a theoretical structure to determine t1ap. theoretical volume of live storage. The theoretical volume of live storage was then increased by a 30% volume correction factor (factor of safety) to determine the volume of live storage required. Once the required detention volume was determined based on onsite flows, the hydrographs for the upstream area were added to the hydrographs for the onsite detained area and routed through the theoretical detention facility. The allowable release rates for the detention pond were then adjusted to take into account flows from the upstream area. The outflow control structure was redesigned to allow flows from the upstream area to . pass through the facility. Thus, the detention pond provides the required volume of live storage, as calculated based on detaining onsite flows, and has release rates based on the combined flows from the upstream and existing onsite areas. For design parameters, please refer to Table 3.S.2B — S.C.S. Western Washington Runoff Curve Numbers located in the appendix at the end of this section. Based on King County Isopluvial maps (see appendix) the total precipitation for the 2, 5, 10, and 100-year, 24- hour storm events are 2.00", 2.60, 2.95", and 3.95" reFnectively. A summary of the detention calculations is provided below. Output from the Water Works program is located in the appendix at the end of this section. Refer to Section X of this report for a copy of the Pond Plan and Pond Section sheets obtained from the Road and Storm Drainage plans for Windsong. TECHNICAL INFORMATION REPORT FOR WINDSONG PAGE: IV-2 EXISTING CONDITIONS Existing Condition Hydrographs (Onsite Flows) Total Area= 11.88 Ac Impervious Area = 0.64 Ac @ CN= 98 (existing road and houses) Pervious Area = 11.24 Ac @ CNW= 81.17 0.32 Ac @ CN = 87 (gravel road) 10.92 Ac @ CN = 81 (second growth forest) CN = 0.32x87+10.92x81 _81.17 '" 11.24 Time of Concentration = 52.78 minutes Reach 1: 300 ft Sheet Flow @ 5.4%, `n'= 0.40 (woodsibrush) Reach 2: 215 ft Shallow Concentrated Flow @ 9.6%,`ks'=5 (woodsibrush) Reach 3: 55 ft Pipe Flow @ 3.5%,`kc'=42 (cone. pipe) Reach 4: 240 ft Shallow Concentrated Flow @ 3.5%,`ks'=5 (woodsibrush) Reach 5: 440 ft Ditch Flow @ 4.2%,`kc'=17 (grass ditch) ExistingCondition H dro ra h Summaries Onsite Flows Storm Precip. Peak Flow Volume Time of Peak Event in] [CfSj Iftlmin. 2-Year 2.00 0.767 29088 490 %2 - 2 Year 2.00 0.384 14544 490 5-Year 2.60 1.483 47285 490 10-Year 2.95 1.951 58786 490 100-Year 3.95 3.426 94033 490 Allowable Release Rates (Onsite Flows) Using the existing condition hydrographs, the allowable release rates for the detention pond were determined. These release rates were then used to calculate the theoretical detention volume. The allowable release rates are as follows: 2-Year Allowable Release Rate = 1/2-2-yr Pre-developed flow = 0.38 cfs 5-Year Allowable Release Rate = 5-yr Pre-developed flow = 1.48 cfs 10-Year Allowable Release Rate = 10-yr Pre-developed flow = 1.95 cfs 100-Year Allowable Release Rate = 100-yr Pre-developed flow=3.43 cfs • TECHNICAL INFORMATION REPORT FOR WINDSONG PAGE: IV-3 • DEVELOPED CONDITIONS Due to grade constraints, a small portion of the site was not directed to the proposed detention facility and was therefore treated as stormwater bypass according to City of Renton Standards. As delineated on the Developed Conditions Exhibit, located in the appendix, the "Detained@rea" will be directed to the detention pond while the "Bypass Area" will continue to sheet flow offsite to the conveyance system located in NE 41h Street. The outflow control structure for the pond was designed so that the total flow leaving the site, which is the pond outflow hydrographs plus the bypass area hydrographs, is less than or equal to the onsite allowable release rates. Detained Area Hydrographs (Onsite Flows) Total Area = 11.65 Ac Impervious Area = 7.31 Ac @ CN = 98 (pavement, roofs) 0.58 Ac—pavement along Hoquiam Ave NE 1.94 Ac—onsite roadways 0.15 Ac—approximate surface area of the detention facility 4.60 Ac—60% of lot area(max. coverage per zoning) 0.04 Ac—Portion of sidewalk along NE 41h Street( Pervious Area =1.61 Ac @ CN= 86 (landscaping, lawns) Time of Concentration= 5.00 minutes (assumed minimum) Detained Area H dro ra h Summaries 'OnsiteFlows Storm Precip. Peak Flow Volume Time of Peak Event in cfs ft3 min. 2-Year 2.00 4.547 60458 470 5-Year 2.60 6.357 83777 470 10-Year 2.95 7.434 97653 470 100-Year 3.95 10.56 137987 470 i TECHNICAL INFORMATION REPORT FOR WINDSONG PAGE: IV-4 Bypass Area Hydrographs (Onsite Flows) Total Area = 0.23 Ac Impervious Area = 0.15 Ac @ CN = 98 (pavement) Pervious Area =1.61 Ac @ CN= 86 (landscaping, lawns) Time of Concentration= 5.00 minutes (assumed minimum) Bypass Area Hy dro ra h Summaries OnsiteFlows Storm Precip. Peak Flow Volume Time of Peak Event in cfs ft3 min. 2-Year 2.00 0.092 1,213 470 5-Year 2.60 0.127 1,676 470 10-Year 2.95 0.149 1,951 470 100-Year 3.95 0.210 2,749 470 LEVEL POOL ROUTING (ONSITE FLOWS) A theoretical detention pond was sized to determine the required depth and theoretical volume of live storage for the site. The following level pool table summary represents the results of routing the onsite detained area 2, 5, 10, and 100-year hydrographs through a theoretical detention pond. LEVEL POOL TABLE SUMMARY Theoretical Pond with Onsite Inflow Rates Description Inflow Storage Dischrg P.Stage Volume Outflow P.Time CFS ID ID FT CF CFS Min 2 Year Pond Release 4.55 THEO O 402.01 37587 0.370 1460 5 Year Pond Release 6.36 THEO O 402.17 39178 1.171 770 10 Year Pond Release 7.43 THEO O 402.21 39579 1.602 650 100 Year Pond Release 10.56 THEO O 402.71 45061 3.349 530 *The Theoretical Volume of Live Storage,based on detaining onsite flows, is 45,061 cubic feet. TECHNICAL INFORMATION REPORT FOR WINDSONG PAGE: IV-5 HYDROGRAPH SUMMARY TABLE(ONSITE FLOWS) DESCRIPTION HYD PEAK TIME VOL. AREA NUM CFS Min CF Ac 2 YEAR POND OUTFLOW 6 0.370 1460 50428 11.65 5 YEAR POND OUTFLOW 7 1.171 770 73123 11.65 10 YEAR POND OUTFLOW 8 1.602 650 86981 11.65 100 YEAR POND OUTFL 9 3.349 530 127263 11.65 2 YEAR BYPASS FLOWS 11 0.092 470 1213 1 0.23 5 YEAR BYPASS FLOWS 12 0.127 470 1676 0.23 10 YEAR BYPASS FLOWS 13 0.149 470 1951 0.23 100 YEAR BYPASS FLOWS 14 0.210 470 2749 0.23 2 YR RELEASE FROM SITE(HYD 6+HYD 11) 16 0.380 1440 51641 11.88 5 YR RELEASE FROM SITE(HYD 7+HYD 12) 17 1.192 770 74798 11.88 10 YR RELEASE FROM SITE(HYD 8+HYD 18 1.631 650 88931 11.88 13) 100 YR RELEASE FROM SITE(HYD 9+HYD 19 3.415 520 130012 11.88 14) Note: The total flows leaving the site(as highlighted in the above table)were calculated to be the flows leaving the detention pond plus the flows leaving the bypass area. Please note, in all cases,the total flow leaving the site does not exceed the allowable release rates(Onsite Flows)for the site. UPSTREAM AREA Upstream Area Hydrographs The upstream area consists of approximately 3.75 acres with a mixture of scattered buildings, lawns and second growth forest. One third of the pervious area was assumed to be second growth forest while the remainder was assumed to be landscaped. The percent impervious was determined from Table 3.5.2B—SCS Western Washington Runoff Curve Numbers. Refer to the Upstream Area Map, located in the appendix at the end of this section, to aid in the following calculations. Dwelling Units — 9 D.U. —2 4 Gross Acre 3.75 G.A. • TECHNICAL INFORMATION REPORT FOR WINDSONG PAGE: IV-6 Based on Table 3.5.213 (see appendix), 2.4 DU/GA corresponds to 29% impervious. Total Area= 3.75 Ac Impervious Area = 1.09 Ac @ CN = 98 (29%) Pervious Area = 2.66 Ac @ CN,= 84.33 0.89 Ac @ CN= 81 (second growth forest) 1.77 Ac @ CN = 86 (lawns/landscaping) Time of Concentration= 30.00 minutes (assumed) COMBINED FLOWS Allowable Release Rates (Combined Flows) The allowable release rates for the pond were re-determined by adding hydrographs for the existing onsite area to the hydrographs for the upstream area. The combined allowable release rates are as follows: HYDROGRAPH SUMMARY (COMBINED FLOWS) DESCRIPTION HYD PEAK TIME VOLUME AREA NUM CFS Min CF Ac 2 YEAR EXISTING ONSITE 1 0.767 490 29088 11.88 '/2-2 YEAR EXISTING ONSITE 2 0.384 490 14544 0.00 5 YEAR EXISTING ONSITE 3 1.483 490 47285 11.88 10 YEAR EXISTING ONSITE 4 1.951 490 58786 11.88 100 YEAR EXISTING ONSITE 5 3.426 490 94033 11.88 2 YEAR UPSTREAM 7 0.648 480 14364 3.75 5 YEAR UPSTREAM 8 1.001 480 21111 3.75 10 YEAR UPSTREAM 9 1.218 480 25225 3.75 100 YEAR UPSTREAM 10 1.869 480 37442 3.75 2 YR COMBINED RELEASE RATE 15 1.008 490 28908 3.75 5 YR COMBINED RELEASE RATE 16 2.440 490 68396 15.63 10 YR COMBINED RELEASE RATE 17 3.114 490 84011 15.63 100 YR COMBINED RELEASE RATE 18 5.203 480 131476 15.63 2-Year Combined Allowable Release Rate= 1.01 cfs = '/2 - 2 Yr. Onsite Existing Condition Hydrograph+ 2 Yr. Upstream Area Hydrograph • TECHNICAL INFORMATION REPORT FOR WINDSONG PAGE: IV-7 • 5-Year Combined Allowable Release Rate=2.44 cfs = 10 Yr. Onsite Existing Condition Hydrograph+ 10 Yr. Upstream Area Hydrograph 10-Year Combined Allowable Release Rate=3.11 cfs = 10 Yr. Onsite Existing Condition Hydrograph+ 10 Yr. Upstream Area Hydrograph rN 100-Year Combined Allowable Release Rate = 5.20 cfs = 100 Yr. Onsite Existing Condition Hydrograph+ 100 Yr. Upstream Area Hydrograph Pond Inflow Hydrographs (Combined Flows) The Upstream Area hydrographs were added to the Detained Area hydrographs to obtain the Pond Inflow hydrographs. A summary of the hydrograph additions is provided in the following table. POND INFLOW HYDROGRAPH SUMMARY TABLE COMBINED FLOWS HYD PEAK TIME VOL AREA DESCRIPTION NUM JCFSJ [Min] CF Ac 2 YEAR DETAINED AREA A 4.547 470 60458 11.65 5 YEAR DETAINED AREA B 6.357 470 83777 11.65 10 YEAR DETAINED AREA C 7.434 470 97653 11.65 100 YEAR DETAINED AREA D 10.560 470 137987 11.65 2 YEAR UPSTREAM E 0.648 480 14364 3.75 5 YEAR UPSTREAM F 1.001 480 21111 3.75 10 YEAR UPSTREAM G 1.218 480 25225 3.75 100 YEAR UPSTREAM H 1.869 480 37442 3.75 2 YR POND INFLOW(HYD A+HYD E) 1 5.071 470 74822 0.00 5 YR POND INFLOW(HYD B+HYD F) 2 7.174 470 104888 0.00 10 YR POND INFLOW(HYD C+HYD G) 3 8.432 470 122878 0.00 100 YR POND INFLOW(HYD D+HYD H) 4 12.105 470 175429 0.00 LEVEL POOL ROUTING (COMBINED FLOWS) The following level pool table summary represents the results of routing the combined 2, 5, 10, and 100-year hydrographs through the theoretical detention pond. The plan view dimensions of this theoretical detention pond were then increased by the required volume correction factor (factor of safety) to obtain the actual detention pond dimensions. Thus, the actual and theoretical structures provide the same depth however the actual structure's TECHNICAL INFORMATION REPORT FOR WINDSONG PAGE: IV-8 • volume has been increased to account for the factor of safety. A summary of the detention calculations for each of the facilities is provided on the pages that follow. Theoretical Pond The following level pool table summary represents the results of routing the combined flow 2, 5, 10, and 100-year hydrographs through the theoretical detention pond. Note that the detention volume calculated below (44,951 CF) is approximately equal to the detention volume required based on detaining onsite flows (45,061 CF). LEVEL POOL TABLE SUMMARY Theoretical Pond with Combined Inflow Rates Description E7.17 w Storage Dischrg P. Stage Volume Outflow P. Time ] ID ID [FT] [CF] [CFS] [Min] 2 Year Pond Outflow 7 THEO C 400.18 22926 0.922 790 5 Year Pond Outflow THEO C 400.72 27268 1.913 550 10 Year Pond Outflow 8.43 THEO C 401.23 31341 2.462 550 100 Year Pond Outflow 1 12.10 THEO C 402.70 1 *44951 3.795 540 . *Theoretical volume of live storage based on combined flows(upstream plus onsite flows)=44,951 cubic- feet. POND OUTFLOW HYDROGRAPH SUMMARY TABLE COMBINED FLOWS HYD PEAK TIME VOLUME AREA DESCRIPTION NUM JCFSJ [Min] CF Ac 2 YR BYPASS AREA 6 0.092 470 1213 0.23 5 YR BYPASS AREA 7 0.127 470 1676 0.23 10 YR BYPASS AREA 8 0.149 470 1951 0.23 100 YR BYPASS AREA 9 0.210 470 2749 0.23 2 YR POND OUTFLOW 11 0.922 790 74822 0.00 5 YR POND OUTFLOW 12 1.913 550 104888 0.00 10 YR POND OUTFLOW 13 2.462 550 122878 0.00 100 YR POND OUTFLOW 14 3.795 540 175429 0.00 2 YR RELEASE FROM SITE(HYD 6+HYD 11) 16 0.937 760 76035 0.23 5 YR RELEASE FROM SITE(HYD 7+HYD 12) 17 1.940 550 106564 0.23 10 YR RELEASE FROM SITE(HYD 8+HYD 13) 18 2.494 550 124828 0.23 100 YR RELEASE FROM SITE(HYD 9+HYD 14) 19 3.839 540 178178 0.23 Note: The total flows leaving the site (as highlighted in the above table) were calculated to be the flows leaving the detention pond plus the flows leaving the bypass area. Please note, in all cases, the total flow leaving the site does not exceed the allowable release rates(combined flows)for the site. • TECHNICAL INFORMATION REPORT FOR WINDSONG PAGE: IV-9 • OUTFLOW CONTROL STRUCTURE (Used with the Theoretical and Actual Ponds with the Combined inflow rates) COMBINATION DISCHARGE ID No. C Description: Combination discharge from detention pond Structure: 02 Structure:03 MULTIPLE ORIFICE"'ID No. 02 Description:Discharge to NE 4r''Street Outlet Elev: 396.20 Elev: 394.20 ft Orifice Diameter: 3.3750 in. Elev: 400.40 ft Orifice 2 Diameter: 5.7500 in. Elev: 401.90 ft Orifice 3 Diameter: 3.5000 in. MULTIPLE ORIFICE ID No. 03 Description: Discharge to Wetland Outlet Elev: 396.20 Elev: 394.20 ft Orifice Diameter: 2.3750 in. Elev: 400.25 ft Orifice 2 Diameter: 4.7500 in. THEORETICAL POND STAGE/STORAGE/DISCHARGE TABLE (Prior to Factor of Safety) • CUSTOM STORAGE ID No.THEO Description: THEORETICAL POND STAGE STORAGE STORAGE DISCHARGE FT CF] [Ac-FT] FS 396.20 0 0.0000 0.0000 396.50 1473 0.0338 0.2531 397.00 3927 0.0902 0.4134 397.50 6382 0.1465 0.5270 398.00 8836 0.2029 0.6201 398.50 11998 0.2754 0.7009 399.00 15159 0.3480 0.7734 399.50 18321 0.4206 0.8396 400.00 21482 0.4932 0.9009 400.50 25481 0.5850 1.5483 401.00 29480 0.6768 2.2378 401.50 33479 0.7686 2.6896 402.00 37478 0.8604 3.1631 402.50 42585 0.9776 3.6362 402.70 44941 1.0317 3.7947 • TECHNICAL INFORMATION REPORT FOR WINDSONG PAGE: IV-10 Actual Pond The following level pool table summary represents the results of routing the developed area 2, 5, 10, and 100-year hydrographs through the actual detention structure. For the actual detention structure the plan view dimensions of the theoretical pond were increased in order to accommodate extra volume associated with the City of Renton 30% factor of safety. An additional factor of safety was added to account for irregularities that may occur during pond construction. Refer to the Pond Volume Calculations exhibit, located in the appendix at the end of this section, for a summary of the surface and volume calculations. ACTUAL LEVEL POOL TABLE SUMMARY Actual Pond with Combined Inflow Rates Description Inflow Storage Dischrg P. Stage Volume Outflow P. Time [CFS ID ID [FT] [CF] [CFS] [Min] 2 Year Pond Outflow 5.07 ACT C 399.52 25651 0.842 900 5 Year Pond Outflow 7.17 ACT C 400.49 35256 1.495 690 10 Year Pond Outflow 8.43 1 ACT C 400.74 38059 1.931 660 100 Year Pond Outflow 12.10 ACT C 401.94 51423 3.057 570 • ACTUAL POND STAGE/STORAGE/DISCHARGE TABLE (With Factor of Safety) CUSTOM STORAGE ID No.ACT Description:ACTUAL DETENTION POND STAGE STORAGE STORAGE DISCHARGE [FT] [CF] [Ac-FT] [CFS] 396.20 0 0.0000 0.0000 396.50 2047 0.0470 0.2531 397.00 5459 0.1253 0.4134 397.50 8871 0.2036 0.5270 398.00 12282 0.2820 0.6201 398.50 16677 0.3829 0.7009 399.00 21072 0.4837 0.7734 399.50 25467 0.5846 0.8396 400.00 29861 0.6855 0.9009 400.50 35420 0.8131 1.5483 401.00 40979 0.9407 2.2378 401.50 46538 1.0684 2.6896 402.00 52096 1.1960 3.1631 402.50 59196 1.3589 3.6362 402.70 62470 1.4341 3.7947 i TECHNICAL INFORMATION REPORT FOR WINDSONG PAGE: IV-11 • LIVE STORAGE In accordance with City of Renton standards, a 30% volume correction factor was applied to the theoretical live storage volume to determine the required live storage volume. The theoretical live storage volume for the detention pond is 45,061 cubic-feet. The detention volume requiNd is therefore 58,579 cubic feet (1.30 x 45,061). A construction factor of safety was also added to the live storage volume to account for irregularities that may occur during construction of the detention pond. As designed, the detention pond provides 62,470 cubic feet of live storage. WATER QUALITY Water quality was provided through the use of dead storage. The required volume of • dead storage was calculated in accordance with Washington State Department of Ecology (DOE) standards. It should be noted that dead storage volumes calculated based on DOE standards are significantly larger than volumes calculated based on the 1990 King County Surface Water Design Manual. The larger dead storage volumes were therefore used for this project. A summary of the calculation is provided below. Per DOE standards, the required water quality volume is equal to the total runoff from the developed condition 24-hour design storm event using 64% of the 2-year, 24-hour precipitation. (0.64)(P2n) = (0.64)(2.00 in) = 1.28 inches Water Quali H dro ra h Summa Storm Precip. Peak Flow Volume Time of Peak Event in cfs Ac-Ft min. Water Quality 1.28 2.48 0.78 470 TECHNICAL INFORMATION REPORT FOR WINDSONG PAGE: I V-12 • The wetpond is divided into two cells by a five foot wide berm. The first cell contains approximately 25% (8,359 CF) of the required dead storage between the elevations of 397.00 and 402.35 as well as one foot of sediment storage depth. The second cell contains approximately 75% (25,894 CF) of the required dead storage between the elevations of 388.20 and 396.20 with 0.5 feet of sediment storage depth.. The required volume to be used for water quality storage is 33,977 cubic feet. As designed, the detention pond provides 34,253 cubic feet of water quality storage. OVERFLOW RISER The overflow riser was sized to convey the 100-year un-detained combined flow of 12.10 cfs (see combined flow hydrograph summary). The riser was designed assuming 0.56 feet of available head. Please reference the calculation below as well as Figure 4.4.7-J • Riser Inflow Curves located in the appendix at the end of this section. Qwei, = 9.739(D)(H)3i2 12.10= 9.739(D)(0.56)3i2 D = 2.96 feet = 35.52 inches The overflow riser was chosen to be 36 inches in diameter. EMERGENCY OVERFLOW SPILLWAY The emergency overflow spillway was sized to convey the 100-year un-detained combined flow of 12.10 cfs (see combined flow hydrograph summary). The spillway was designed assuming 0.40 feet of available flow depth over the weir. Please reference the calculation below. Q i oo = 12.10 cfs H = 0.40 feet TECHNICAL INFORMATION REPORT FOR WINDSONG PAGE: IV-13 • L = Qioo - 2.4H 3.21H3 2 L =13.94 feet As designed, the overflow spillway will be 15 feet long with 0.4 feet of available flow depth over the spillway and approximately 0.36 feet of freeboard. SPILLWAY BETWEEN POND CELLS A spillway was sized to convey flows from cell 1 of the detention facility to cell 2 of the detention facility. The spillway was sized to convey the 100-year un-detained combined flow of 12.10 cfs (see combined flow hydrograph summary). The spillway was designed assuming 0.35 feet of available flow depth over the weir. Please reference the calculation below. Qioo = 12.10 cfs H= 0.35 feet L = Qtoo - 2.4H 3.21Hs12 L =17.4 feet As designed, the spillway will be 21 feet at its crest and will extend to the bottom of Cell 2. The spillway will be shaped, with 0.5 feet high side slopes, to prevent water from overtopping the edges of the spillway. TECHNICAL INFORMATION REPORT FOR WINDSONG PAGE: IV-14 WETLAND RECHARGE In the pre-developed state, the onsite wetland located near the southwest corner of the property receives runoff from approximately 8.98 acres, as delineated on the Wetland Tributary Area exhibit located in the appendix at the end of this section. Due to development, runoff, which was previously tributary to the wetland, will now be collected in a tightline conveyance system and routed to the combination detention/water quality facility. In order to maintain wetland hydrology, a portion of the pond's stormwater discharge will be directed to the wetland. The outflow control structure for the detention facility was designed to direct a portion of the pond's discharge to the wetland. Specifically, the outflow control structure contains two standpipes with associated orifices. One standpipe directs discharge to the wetland while the other directs flows to the conveyance system located along NE 4th Street. • Santa Barbara Urban Hydrograph (SBUH) methodology was used to determine the peak flow and total volume of runoff tributary to the wetland in the pre-developed state. The primary goal of the wetland evaluation was to maintain pre-existing volumes of runoff to the wetland during the 2-year/24-hour design storm event in addition to not exceeding the pre-developed peak rate of runoff to the wetland. Calculations were provided for the 10 and 100-year/24-hour design storm events for reference. A summary of the flow and volume calculations is provided below. Refer to the Wetland Recharge exhibit located at the end of this appendix for additional information pertaining to the flow calculations. TECHNICAL INFORMATION REPORT FOR WINDSONG PAGE: IV-15 • Pre-Developed Flows to Wetland Onsite Area = 5.23 Ac Impervious Area = 0.07 Ac @ CN = 98 (existing road and houses) Pervious Area = 5.16 Ac @ CN,,,= 81.1 0.06 Ac a CN = 87 (gravel road) 5.10 Ac @ CN = 81 (second growth forest) CN = 0.06x87+5.10x81 _81.07 "' 5.16 Time of Concentration= 53.83 minutes Reach 1: 300 ft Sheet Flow @ 3.5%, `n'= 0.40 (woodsibrush) Reach 2: 70 ft Shallow Concentrated Flow @ 2.3%,`ks'=5 (woodsibrush) Upstream Area= 3.75 Ac Impervious Area = 1.09 Ac @ CN= 98 (29%) Pervious Area = 2.66 Ac @ CN,= 84.33 0.89 Ac @ CN = 81 (second growth forest) • 1.77 Ac @ CN= 86 (lawns/landscaping) CN _- 0.89x81+1.77x86 -84.33 w 2.66 Time of Concentration=30.00 minutes (assumed) Pre-Developed H dro ra h Summaries (Wetland Recharge) DESCRIPTION HYD PEAK TIME VOLUME AREA NUM CFS Min CF Ac 2 Year Upstream 1 0.648 4a0 14364 3.75 10 Year Upstream 3 1.218 480 25225 3.75 100 Year Upstream 4 1.685 490 37442 3.75 2 Year Onsite 5 0.290 500 11855 5.23 10 Year Onsite 7 0.793 490 24695 5.23 100 Year Onsite 8 1.431 490 40045 5.23 2 Year Total(H d 1 +H d 4) 10 0.911 490 26219 8.98 10 Year Total(H d 3+H d 6) 12 1.973 480 49920 8.98 100 Year Total(H d 4+H d 8) 1 13 3.117 490 77487 8.98 TECHNICAL INFORMATION REPORT FOR WINDSONG PAGE: IV-16 i Post-Developed Flows to Wetland In the post developed condition, flows from the detention pond are directed to the wetland through one of two outflow control structures located in the restrictor manhole (labeled CBI on the Pond Plan — See section X of this report). The following table is a summary of the flows which are conveyed to the wetland. Post-Developed H dro ra h Summaries (Wetland Rechar e DESCRIPTION HYD I PEAK TIME VOLUME AREA NUM JCFSI [Mi2j_ CF Ac 2 YR RELEASE TO WETLAND(RESTRICTOR 03) 6 0.305 790 24781 0.00 10 YR RELEASE TO WETLAND(RESTRICTOR 03) 7 0.950 550 46862 0.00 100 YR RELEASE TO WETLAND(RESTRICTOR 03) 8 1.349 540 65794 0.00 Wetland Recharge Summary • As shown in the fore mentioned hydrograph summary tables, the post developed volume that is conveyed to the wetland is reasonably similar to the volume tributary to the wetland in the pre-developed state. In addition, the post-developed peak rates of runoff entering the wetland do not exceed the pre-developed rates of runoff tributary to the wetland. It can be concluded that with the construction of the detention pond and associated dual outflow control restrictors post-developed wetland hydrology will be reasonable similar to pre-developed conditions. TECHNICAL INFORMATION REPORT FOR WINDSONG PAGE: IV-17 APPENDIX • 5/19/99 WINDSONG BKP HYDROGRAPH SUMMARY 2(COMBINED FLOWS) HYD PEAK TIME VOLUME AREA DESCRIPTION NUM JCFSJ [MiniCF Ac 2 YEAR DETAINED AREA A 4.547 470 60458 11.65 5 YEAR DETAINED AREA B 6.357 470 83777 11.65 10 YEAR DETAINED AREA C 7.434 470 97653 11.65 100 YEAR DETAINED AREA D 10.560 470 137987 11.65 2 YEAR UPSTREAM E 0.648 480 14364 3.75 5 YEAR UPSTREAM F 1.001 480 21111 3.75 10 YEAR UPSTREAM G 1.218 480 25225 3.75 100 YEAR UPSTREAM H 1.869 480 37442 3.75 2 YR POND INFLOW(HYD A+HYD E) 1 5.071 470 74822 0.00 5 YR POND INFLOW(HYD B+HYD F) 2 7.174 470 104888 0.00 10 YR POND INFLOW(HYD C+HYD G) 3 8.432 470 122878 0.00 100 YR POND INFLOW(HYD D+HYD H) 4 12.105 470 175429 0.00 2 YR BYPASS AREA 6 0.092 470 1213 0.23 5 YR BYPASS AREA 7 0.127 470 1676 0.23 10 YR BYPASS AREA 8 0.149 470 1951 0.23 100 YR BYPASS AREA 9 0.210 470 2749 0.23 2 YR POND OUTFLOW 11 0.922 790 74822 0.00 5 YR POND OUTFLOW 12 1.913 550 104888 0.00 10 YR POND OUTFLOW 13 2.462 550 122878 0.00 100 YR POND OUTFLOW 14 3.795 540 175429 0.00 2 YR RELEASE FROM SITE HYD 6+HYD 11) 16 0.937 760 76035 0.23 5 YR RELEASE FROM SITE(HYD 7+HYD 12) 17 1.940 550 106564 0.23 10 YR RELEASE FROM SITE(HYD 8+HYD 13) 18 2.494 550 124828 0.23 100 YR RELEASE FROM SITE(HYD 9+HYD 14) 19 3.839 540 178178 1 0.23 Note: The total flows leaving the site (as highlighted in the above table)were calculated to be the flows leaving the detention pond plus the flows leaving the bypass area. Please note, in all cases,the total flow leaving the site does not exceed the allowable release rates(combined flows)for the site. OUTFLOW CONTROL STRUCTURE(COMBINED FLOWS) COMBINATION DISCHARGE ID No. C Description: Combination discharge from detention pond Structure: 02 Structure: 03 MULTIPLE ORIFICE ID No. 02 Description: Discharge to NE 4 h Street Outlet Elev: 396.20 Elev: 394.20 ft Orifice Diameter: 3.3750 in. Elev: 400.40 ft Orifice 2 Diameter: 5.7500 in. Elev: 401.90 ft Orifice 3 Diameter: 3.5000 in. MULTIPLE ORIFICE ID No. 03 Description: Discharge to Wetland Outlet Elev: 396.20 Elev: 394.20 ft Orifice Diameter: 2.3750 in. . Elev: 400.25 ft Orifice 2 Diameter: 4.7500 in. File: 95244wworks Combined Flows Water Works Output 5/19/99 WINDSONG BKP COMBINATION DISCHARGE ID No. C Description: Combination discharge from detention pond Structure: 02 Structure: 03 STAGE DISCHARGE FT CFS 396.20 0.0000 396.50 0.2531 397.00 0.4134 397.50 0.5270 398.00 0.6201 398.50 0.7009 399.00 0.7734 399.50 0.8396 400.00 0.9009 400.50 1.5483 401.00 2.2378 401.50 2.6896 402.00 3.1631 402.50 3.6362 402.70 L 3.7947 MULTIPLE ORIFICE ID No. 02 Description: Discharge to NE 4 h Street Outlet Elev: 396.20 Elev: 394.20 ft Orifice Diameter: 3.3750 in. Elev: 400.40 ft Orifice 2 Diameter: 5.7500 in. Elev: 401.90 ft Orifice 3 Diameter: 3.5000 in. STAGE DISCHARGE FT CFS 396.20 0.0000 396.50 0.1693 397.00 0.2765 397.50 0.3524 398.00 0.4147 398.50 0.4688 399.00 0.5172 399.50 0.5615 400.00 0.6026 400.50 0.9247 401.00 1.3722 401.50 1.6526 402.00 1.9845 402.50 2.3335 402.70 2.4461 File: 95244wworks Combined Flows Water Works Output 5/19/99 WINDSONG BKP MULTIPLE ORIFICE ID No. 03 Description: Discharge to Wetland Outlet Elev: 396.20 Elev: 394.20 ft Orifice Diameter: 2.3750 in. Elev: 400.25 ft Orifice 2 Diameter: 4.7500 in. STAGE DISCHARGE [FT] [CFS] 396.20 0.0000 396.50 0.0838 397.00 0.1369 397.50 0.1745 398.00 0.2054 398.50 0.2321 399.00 0.2561 399.50 0.2781 400.00 0.2984 400.50 0.6236 401.00 0.8656 401.50 1.0369 402.00 1.1786 402.50 1.3026 402.70 1.3486 i File: 95244wworks Combined Flows Water Works Output WINDSONG 95-244 Factor of Safety: 39% ACTUAL POND THEORETICAL POND elev Surface Area Inc. Vol. Total Vol. Surface Area Inc. Vol. Total Vol. 396.2 5,975 0 0 4299 0 0 398 7,672 12282 12282 5519 8836 8836 400 9907 17579 29861 7127 12647 21483 402 12328 22235 52096 8869 15996 37479 402.5 16,069 7099 59196 11560 5107 42587 402.7 16,677 3275 62470 11998 2356 44943 Note: Cell one contains live storage between the elevations of 402.50 and 402.70. To account for this in he above spreadsheet,the surface areas of cell one and cell 2 were added together(between 402.50 and 02.70)and placed in the above table. The surface area of the Theoretical Pond was increased by 39%,at each elevation listed in the above table, 0 obtain the Actual Pond. The Actual Pond is the pond to be constructed.For further pond information refer to the Road and Storm Drainage Plans for Windson . Bottom of Live = 396.20 MWS =402.70 File: 95244pondcalc.xls POND VOLUME CALCULATIONS KING COUNTY, WASI-IINGT' ON, SURFACE WATER DESIGN MANUAL FIGURE 4.4.7J RISER INFLOW CURVES Weir Flow Orifice Flow ------- 100 - - 36 33 30 c 27 o N 24 L U a 21 c CU U w 18 E C6 a 15 W /Z hHIM12 10 10 --i -- r 0.1 1.0 — 10.0 HEAD IN FEET (measured from crest of riser) SOURCE: USDA-SCS QWIER = 9.739 DHT2 QORIME - 3.782 D2Hv2 Q in cfs, D and H in feet 4A.7-10 1/9() K I N G (' O I I N '1' )'. WASH I N G "I` O N, S U RFACE W A 'I' E R DES IGN MAN U A L TABLF_3_5.2I3 SC, WESTERN NVASIIINGT'ON RUNOFF CURVE NUMBERS ------ F- SCS WESTERN WASHINGTON RUNOFF CURVE NUMBERS (Published by SCS in 1982) Runoff curve numbers for selected agricultural, suburban and urban land use for Type t A rainfall distribution, 24-hour storm duration. CURVE NUMBERS BY LAND USE DESCRIPTION HYDROLOGIC SOIL GROUP A B C D Cultivated land(1): winter condition 86 91 94 95 Mountain open areas: low growing brush and grasslands 74 82 89 92 Meadow or pasture: 65 78 85 89 Wood or forest land: undisturbed or older second growth 42 64 81 Wood or forest land: young second growth or brush 55 72 �81 86 Orchard: with cover crop 81 88 S2 94 Open spaces, lawns, parks, golf courses, cemeteries, landscaping. good condition: grass cover on 75% fair condition: or more of the area 68 80 O g0 grass cover on 50% to 75% of the area 77 85 90 92 Gravel roads and parking lots 76 85 89 91 Dirt roads and parking lots 72 82 87 89 Impervious surfaces, pavement, roofs, etc. 98 98 98 98 Open water bodies: lakes, wetlands, ponds, etc. 100 100 0 100 Single Family Residential (2) Dwelling Unit/Gross Acre % Impervious (3) 1.0 DU/GA 15 Separate curve number 1.5 DU/GA 20 shall be selected 2.0 DU/GA 25 for pervious and 2.5 DU/GA 30 3.0 DU/GA impervious portion 3.5 DU/GA 34 of the site or basin 4.0 DU/GA 38 4.5 DU/GA 42 46 5.0 DU/GA 48 5.5 DU/GA 50 6.0 DU/GA 52 6.5 DU/GA 54 7.0 DU/GA 56 Planned unit developments, % impervious condominiums, apartments, must be computed commercial business and industrial areas. (1) For a more detailed description of agricultural land use curve numbers refer to National Engineering Handbook, Section 4, Hydrology, Chapter 9, August 1972. (2) Assumes roof and driveway runoff is directed into street/storm system. - (3) The remaining pervious areas (lawn) are considered to be in good condition for these curve numbers. i 3.5.2-3 11/92 r � ilk; XqmL • l MBIA pylorlot.151 IMIMo UN s�� '�► � R M �h Lm ICI r s • s • � c • • 1.0 IRS 41 AIN ; 1 L �• lI err , ' • •Mal °�'"��ry • sue,,. � -� � 1 r - � r ram '�► r ►Ml� ' • e • 11111111211113c • •low e • •T Id17 , 7, ZION IR twig 119-010=17 NO All MA WO Mal •� i ailFlo Fill . - Er . • �_ WAN j ,IrQ _ ;inn, �' - �,�►. .y�� •� - � FA Wm 1 , ► "7 5/19/99 W INDSONG BKP BASIN SUMMARY BASIN ID: Al NAME: 2 YEAR EXISTING SBUH METHODOLOGY TOTAL AREA..: 11.88 Acres BASEFLOWS 0.00 cfs RAINFALL TYPE..: USERI PERVIOUS AREA PRECIPITATION..: 2.00 inches AREA..: 11.24 Acres TIME INTERVAL..: 10.00 min CN..: 81.17 TIME OF CONC..: 52.78 min IMPERVIOUS AREA ABSTRACTION COEFF : 0.20 AREA..: 0.64 Acres CN..: 98.00 TcReach-Sheet L: 300.00 ns:0.4000 p2yr: 2.00 s:0.0540 TcReach-Shallow L: 215.00 ks:5.00 s:0.0960 TcReach-Channel L: 55.00 kc:42.00 s:0.0350 TcReach-Shallow L: 240.00 ks:5.00 s:0.0350 TcReach-Channel L: 440.00 kc:17.00 s:0.0420 RATE: 0.77 cfs VOL: 0.67 Ac-ft TIME: 490 min BASIN ID: A2 NAME: 5 YEAR EXISTING SBUH METHODOLOGY TOTAL AREA..: 11.88 Acres BASEFLOWS 0.00 cfs RAINFALL TYPE..: USERI PERVIOUS AREA PRECIPITATION..: 2.60 inches AREA..: 11.24 Acres TIME INTERVAL..: 10.00 min CN..: 81.17 TIME OF CONC..: 52.78 min IMPERVIOUS AREA ABSTRACTION COEFF : 0.20 AREA..: 0.64 Acres CN..: 98.00 PEAK RATE: 1.48 cfs VOL: 1.09 Ac-ft TIME: 490 min BASIN ID: A3 NAME: 10 YEAR EXISTING SBUH METHODOLOGY TOTAL AREA..: 11.88 Acres BASEFLOWS 0.00 cfs RAINFALL TYPE..: USERI PERVIOUS AREA PRECIPITATION..: 2.95 inches AREA..: 11.24 Acres TIME INTERVAL..: 10.00 min CN..: 81.17 TIME OF CONC..: 52.78 min IMPERVIOUS AREA ABSTRACTION COEFF : 0.20 AREA..: 0.64 Acres CN..: 98.00 PEAK RATE: 1.95 cfs VOL: 1.35 Ac-ft TIME: 490 min File: 95244wworks Basin Summaries Water Works Output 5/19/99 WINDSONG BKP BASIN SUMMARY BASIN ID: A4 NAME: 100 YEAR EXISTING BASIN SBUH METHODOLOGY TOTAL AREA..: 11.88 Acres BASEFLOWS 0.00 cfs RAINFALL TYPE..: USERI PERVIOUS AREA PRECIPITATION..: 3.95 inches AREA..: 11.24 Acres TIME INTERVAL..: 10.00 min CN..: 81.17 TIME OF CONC..: 52.78 min IMPERVIOUS AREA ABSTRACTION COEFF : 0.20 AREA..: 0.64 Acres CN..: 98.00 RATE: 3.43 cfs VOL: 2.16 Ac-ft TIME: 490 min BASIN ID: B 1 NAME: 2 YEAR DETAINED AREA SBUH METHODOLOGY TOTAL AREA..: 11.65 Acres BASEFLOWS 0.00 cfs RAINFALL TYPE..: USERI PERVIOUS AREA PRECIPITATION..: 2.00 inches AREA..: 4.34 Acres TIME INTERVAL..: 10.00 min CN..: 86.00 TIME OF CONC..: 5.00 min IMPERVIOUS AREA ABSTRACTION COEFF : 0.20 AREA..: 7.31 Acres CN..: 98.00 PEAK RATE: 4.55 cfs VOL: 1.39 Ac-ft TIME: 470 min BASIN ID: B2 NAME: 5 YEAR DETAINED AREA SBUH METHODOLOGY TOTAL AREA..: 11.65 Acres BASEFLOWS 0.00 cfs RAINFALL TYPE..: USERI PERVIOUS AREA PRECIPITATION..: 2.60 inches AREA..: 4.34 Acres TIME INTERVAL..: 10.00 min CN..: 86.00 TIME OF CONC..: 5.00 min IMPERVIOUS AREA ABSTRACTION COEFF : 0.20 AREA..: 7.31 Acres CN..: 98.00 PEAK RATE: 6.36 cfs VOL: 1.92 Ac-ft TIME: 470 min File: 95244wworks Basin Summaries Water Works Output 5/19/99 WINDSONG BKP BASIN SUMMARY BASIN ID: B3 NAME: 10 YEAR DETAINED AREA SBUH METHODOLOGY TOTAL AREA..: 11.65 Acres BASEFLOWS 0.00 cfs RAINFALL TYPE..: USER1 PERVIOUS AREA PRECIPITATION..: 2.95 inches AREA..: 4.34 Acres TIME INTERVAL..: 10.00 min CN..: 86.00 TIME OF CONC..: 5.00 min IMPERVIOUS AREA ABSTRACTION COEFF : 0.20 AREA..: 7.31 Acres CN..: 98.00 PEAK RATE: 7.43 cfs VOL: 2.24 Ac-ft TIME: 470 min BASIN ID: B4 NAME: 100 YEAR DETAINED AREA SBUH METHODOLOGY TOTAL AREA..: 11.65 Acres BASEFLOWS 0.00 cfs RAINFALL TYPE..: USER1 PERVIOUS AREA PRECIPITATION..: 3.95 inches AREA..: 4.34 Acres TIME INTERVAL..: 10.00 min CN..: 86.00 TIME OF CONC..: 5.00 min IMPERVIOUS AREA ABSTRACTION COEFF : 0.20 AREA..: 7.31 Acres CN..: 98.00 PEAK RATE: 10.56 cfs VOL: 3.17 Ac-ft TIME: 470 min BASIN ID: C1 NAME:2 YEAR BYPASS SBUH METHODOLOGY TOTAL AREA..: 0.23 Acres BASEFLOWS 0.00 cfs RAINFALL TYPE..: USER1 PERVIOUS AREA PRECIPITATION..: 2.00 inches AREA..: 0.08 Acres TIME INTERVAL..: 10.00 min CN..: 86.00 TIME OF CONC..: 5.00 min IMPERVIOUS AREA ABSTRACTION COEFF : 0.20 AREA..: 0.15 Acres CN..: 98.00 PEAK RATE: 0.09 cfs VOL: 0.03 Ac-ft TIME: 470 min File: 95244wworks Basin Summaries Water Works Output 5/19/99 W INDSONG BKP 0 BASIN SUMMARY BASIN ID: C2 NAME: 5 YEAR BYPASS SBUH METHODOLOGY TOTAL AREA..: 0.23 Acres BASEFLOWS 0.00 cfs RAINFALL TYPE..: USER1 PERVIOUS AREA PRECIPITATION..: 2.60 inches AREA..: 0.08 Acres TIME INTERVAL..: 10.00 min CN..: 86.00 TIME OF CONC..: 5.00 min IMPERVIOUS AREA ABSTRACTION COEFF : 0.20 AREA..: 0.15 Acres CN..: 98.00 PEAK RATE: 0.13 cfs VOL: 0.04 Ac-ft TIME: 470 min BASIN ID: C3 NAME: 10 YEAR BYPASS SBUH METHODOLOGY TOTAL AREA..: 0.23 Acres BASEFLOWS 0.00 cfs RAINFALL TYPE..: USER1 PERVIOUS AREA PRECIPITATION..: 2.95 inches AREA..: 0.08 Acres TIME INTERVAL..: 10.00 min CN..: 86.00 TIME OF CONC..: 5.00 min IMPERVIOUS AREA ABSTRACTION COEFF : 0.20 AREA..: 0.15 Acres CN..: 98.00 PEAK RATE: 0.15 cfs VOL: 0.04 Ac-ft TIME: 470 min BASIN ID: C4 NAME: 100 YEAR BYPASS SBUH METHODOLOGY TOTAL AREA..: 0.23 Acres BASEFLOWS 0.00 cfs RAINFALL TYPE..: USERI PERVIOUS AREA PRECIPITATION..: 3.95 inches AREA..: 0.08 Acres TIME INTERVAL..: 10.00 min CN..: 86.00 TIME OF CONC..: 5.00 min IMPERVIOUS AREA ABSTRACTION COEFF 0.20 AREA..: 0.15 Acres CN..: 98.00 PEAK RATE: 0.21 cfs VOL: 0.06 Ac-ft TIME: 470 min File: 95244wworks Basin Summaries Water Works Output 5/19/99 W INDSONG BKP BASIN SUMMARY BASIN ID: UPI NAME: 2 YEAR UPSTREAM SBUH METHODOLOGY TOTAL AREA..: 3.75 Acres BASEFLOWS 0.00 cfs RAINFALL TYPE..: USERI PERVIOUS AREA PRECIPITATION..: 2.00 inches AREA..: 2.66 Acres TIME INTERVAL..: 10.00 min CN..: 84.33 TIME OF CONC..: 30.00 min IMPERVIOUS AREA ABSTRACTION COEFF 0.20 AREA..: 1.09 Acres CN..: 98.00 PEAK RATE: 0.65 cfs VOL: 0.33 Ac-ft TIME: 480 min BASIN ID:UP2 NAME: 5 YEAR UPSTREAM SBUH METHODOLOGY TOTAL AREA..: 3.75 Acres BASEFLOWS 0.00 cfs RAINFALL TYPE..: USERI PERVIOUS AREA PRECIPITATION..: 2.60 inches AREA..: 2.66 Acres TIME INTERVAL..: 10.00 min CN..: 84.33 TIME OF CONC..: 30.00 min IMPERVIOUS AREA ABSTRACTION COEFF 0.20 AREA..: 1.09 Acres CN..: 98.00 PEAK RATE: 1.00 cfs VOL: 0.48 Ac-ft TIME: 480 min BASIN ID: UP3 NAME: 10 YEAR UPSTREAM SBUH METHODOLOGY TOTAL AREA..: 3.75 Acres BASEFLOWS 0.00 cfs RAINFALL TYPE..: USERI PERVIOUS AREA PRECIPITATION..: 2.95 inches AREA..: 2.66 Acres TIME INTERVAL..: 10.00 min CN..: 84.33 TIME OF CONC..: 30.00 min IMPERVIOUS AREA ABSTRACTION COEFF : 0.20 AREA..: 1.09 Acres CN..: 98.00 PEAK RATE: 1.22 cfs VOL: 0.58 Ac-ft TIME: 480 min File: 95244wworks Basin Summaries Water Works Output 5/19/99 WINDSONG BKP BASIN SUMMARY BASIN ID:UP4 NAME: 100 YEAR UPSTREAM SBUH METHODOLOGY TOTAL AREA..: 3.75 Acres BASEFLOWS 0.00 cfs RAINFALL TYPE..: USERI PERVIOUS AREA PRECIPITATION..: 3.95 inches AREA..: 2.66 Acres TIME INTERVAL..: 10.00 min CN..: 84.33 TIME OF CONC..: 30.00 min IMPERVIOUS AREA ABSTRACTION COEFF : 0.20 AREA..: 1.09 Acres CN..: 98.00 PEAK RATE: 1.87 cfs VOL: 0.86 Ac-ft TIME: 480 min BASIN SUMMARY BASIN ID:WQ NAME: WATER QUALITY SBUH METHODOLOGY TOTAL AREA..: 11.65 Acres BASEFLOWS 0.00 cfs RAINFALL TYPE..: USERI PERVIOUS AREA PRECIPITATION..: 1.28 inches AREA..: 4.34 Acres TIME INTERVAL..: 10.00 min CN..: 86.00 TIME OF CONC..: 5.00 min IMPERVIOUS AREA ABSTRACTION COEFF : 0.20 AREA..: 7.31 Acres CN..: 98.00 PEAK RATE: 2.48 cfs VOL: 0.78 Ac-ft TIME: 470 min i File: 95244wworks Basin Summaries Water Works Output 5/19/99 WINDSONG BKP HYDROGRAPH SUMMARY 1 (ONSITE FLOWS) DESCRIPTION HYD PEAK TIME VOL. AREA NUM ICFS1 I [Mini JCFJAc 2 YEAR EXISTING ONSITE 1 0.767 490 29088 11.88 '/2-2 YEAR EXISTING ONSITE 2 0.384 490 14544 0.00 5 YEAR EXISTING ONSITE 3 1.483 490 47285 11.88 10 YEAR EXISTING ONSITE 4 1.951 490 58786 11.88 100 YEAR EXISTING ONSITE 5 3.426 490 94033 11.88 ALLOWABLE RELEASE RATES(ONSITE FLOWS) 2 Year Release Rate = Y 2 Year Existing Flow = 0.38 cfs 5 Year Release Rate = 5 Year Existing Flow = 1.48 cfs 10 Year Release Rate = 10 Year Existing Flow = 1.95 cfs 100 Year Release Rate = 100 Year Existing Flow =3.43 cfs HYDROGRAPH SUMMARY 2(ONSITE FLOWS) DESCRIPTION HYD PEAK TIME VOL. AREA NUM ICFS Min] JCFJ fAcl 2 YEAR DETAINED AREA 1 4.547 470 60458 11.65 5 YEAR DETAINED AREA 2 6.357 470 83777 11.65 10 YEAR DETAINED AREA 3 7.434 470 97653 11.65 100 YEAR DETAINED AREA 4 10.560 470 137987 11.65 2 YEAR POND OUTFLOW 6 0.370 1460 50428 11.65 5 YEAR POND OUTFLOW 7 1.171 770 73123 11.65 10 YEAR POND OUTFLOW 8 1.602 650 86981 11.65 100 YEAR POND OUTFLOW 9 3.349 530 127263 11.65 2 YEAR BYPASS FLOWS 11 0.092 470 1213 0.23 5 YEAR BYPASS FLOWS 12 0.127 470 1676 0.23 10 YEAR BYPASS FLOWS 13 0.149 470 1951 0.23 100 YEAR BYPASS FLOWS 14 0.210 470 2749 0.23 2 YR RELEASE FROM SITE(HYD 6+HYD 11) 16 0.380 1440 51641 11.88 5 YR RELEASE FROM SITE(HYD 7+HYD 12) 17 1.192 770 74798 11.88 10 YR RELEASE FROM SITE(HYD 8+HYD 13) 18 1.631 650 88931 11.88 100 YR RELEASE FROM SITE(HYD 9+HYD 14) 19 3.415 520 130012 11.88 Note: The total flows leaving the site(as highlighted in the above table)were calculated to be the flows leaving the detention pond plus the flows leaving the bypass area. Please note, in all cases,the total flow leaving the site does not exceed the allowable release rates(Onsite Flows)for the site. FLOW CONTROL STRUCTURE(ONSITE FLOWS) MULTIPLE ORIFICE ID No. O Description: Orifice Discharge Outlet Elev: 396.20 Elev: 394.20 ft Orifice Diameter: 2.3789 in. Elev: 402.10 ft Orifice 2 Diameter: 11.8125 in. File: 95244wworks Onsite Flows Water Works Output 5/19/99 WINDSONG BKP THEORETICAL STAGE/STORAGE/DISCHARGE TABLE(ONSITE FLOWS) (Prior to Factor of Safety) CUSTOM STORAGE ID No.THEO Description: THEORETICAL POND STAGE STORAGE STORAGE DISCHARGE FT CF] [Ac-FT CFS 396.20 0 0.0000 0.0000 396.50 1473 0.0338 0.0841 397.00 3927 0.0902 0.1374 397.50 6382 0.1465 0.1751 398.00 8836 0.2029 0.2060 398.50 11998 0.2754 0.2329 399.00 15159 0.3480 0.2570 399.50 18321 0.4206 0.2790 400.00 21482 0.4932 0.2994 400.50 25481 0.5850 0.3185 401.00 29480 0.6768 0.3365 401.50 33479 0.7686 0.3536 402.00 37478 0.8604 0.3699 402.50 42585 0.9776 2.7803 402.70 44941 1.0317 3.3246 LEVEL POOL TABLE SUMMARY(ONSITE FLOWS) Description Inflow Storage Dischrg P. Stage Volume Outflow P.Time CFS ID ID FT CF] [CFS] [Min 2 Year Pond Release 4.55 THEO O 402.01 37587 0.370 1460 5 Year Pond Release 6.36 THEO O 402.17 39178 1.171 770 10 Year Pond Release 7.43 THEO O 402.21 39579 1.602 650 100 Year Pond Release 10.56 THEO O 402.71 i 45061 3.349 530 *The Theoretical Volume of Live Storage,based on detaining onsite flows, is 45,061 cubic feet. File: 95244wworks Onsite Flows Water Works Output 5/19/99 WINDSONG BKP HYDROGRAPH SUMMARY 1 (COMBINED FLOWS) DESCRIPTION HYD PEAK TIME VOLUME AREA NUM CFS Min CF Ac 2 YEAR EXISTING ONSITE 1 0.767 490 29088 11.88 '/2-2 YEAR EXISTING ONSITE 2 0.384 490 14544 0.00 5 YEAR EXISTING ONSITE 3 1.483 490 47285 11.88 10 YEAR EXISTING ONSITE 4 1.951 490 58786 11.88 100 YEAR EXISTING ONSITE 5 3.426 490 94033 11.88 2 YEAR UPSTREAM 7 0.648 480 14364 3.75 5 YEAR UPSTREAM 8 1.001 480 21111 3.75 10 YEAR UPSTREAM 9 1.218 480 25225 3.75 100 YEAR UPSTREAM 10 1.869 480 37442 3.75 2 YR COMBINED RELEASE RATE 15 1.008 490 28908 3.75 5 YR COMBINED RELEASE RATE 16 2.440 490 68396 15.63 10 YR COMBINED RELEASE RATE 17 3.114 490 84011 15.63 100 YR COMBINED RELEASE RATE 18 5.203 480 131476 15.63 ALLOWABLE RELEASE RATES(COMBINED FLOWS) 2 Year Release Rate = %2 Year Onsite Existing Flow + 2 Year Upstream Flow = 1.00 cfs 5 Year Release Rate =5 Year Onsite Existing Flow+ 5 Year Upstream Flow =2.44 cfs 10 Year Release Rate = 10 Year Onsite Existing Flow+ 10 Year Upstream Flow =3.11 cfs 100 Year Release Rate = 100 Year Onsite Existing Flow + 100 Year Upstream Flow =5.20 cfs File: 95244wworks Combined Flows Water Works Output 5/19/99 WINDSONG BKP THEORETICAL STAGE/STORAGE/DISCHARGE TABLE(COMBINED FLOWS) (Prior to Factor of Safety) CUSTOM STORAGE ID No. THEO Description: THEORETICAL POND STAGE STORAGE STORAGE DISCHARGE FT CF] [Ac-FT CFS 396.20 0 0.0000 0.0000 396.50 1473 0.0338 0.2531 397.00 3927 0.0902 0.4134 397.50 6382 0.1465 0.5270 398.00 8836 0.2029 0.6201 398.50 11998 0.2754 0.7009 399.00 15159 0.3480 0.7734 399.50 18321 0.4206 0.8396 400.00 21482 0.4932 0.9009 400.50 25481 0.5850 1.5483 401.00 29480 0.6768 2.2378 401.50 33479 0.7686 2.6896 402.00 37478 0.8604 3.1631 402.50 42585 0.9776 3.6362 402.70 44941 1.0317 3.7947 THEORETICAL LEVEL POOL TABLE SUMMARY(COMBINED FLOWS) Description Inflow Storage Dischrg P. Stage Volume Outflow P.Time CFS ID ID FT CF] [CFS] [Min 2 Year Pond Outflow 5.07 THEO C 400.18 22926 0.922 790 5 Year Pond Outflow 7.17 THEO C 400.72 27268 1.913 550 10 Year Pond Outflow 8.43 THEO C 401.23 31341 11 .462 550 100 Year Pond Outflow 12.10 THEO C 402.70 44951 1 3.795 540 File: 95244wworks Combined Flows Water Works Output 5/19/99 WINDSONG BKP ACTUAL STAGE/STORAGE/DISCHARGE TABLE(COMBINED FLOWS) (With Factor of Safety) CUSTOM STORAGE ID No.ACT Description: ACTUAL DETENTION POND STAGE STORAGE STORAGE DISCHARGE [FT] [CF] [Ac-FT] [CFS] 396.20 0 0.0000 0.0000 396.50 2047 0.0470 0.2531 397.00 5459 0.1253 0.4134 397.50 8871 0.2036 0.5270 398.00 12282 0.2820 0.6201 398.50 16677 0.3829 0.7009 399.00 21072 0.4837 0.7734 399.50 25467 0.5846 0.8396 400.00 29861 0.6855 0.9009 400.50 35420 0.8131 1.5483 401.00 40979 0.9407 2.2378 401.50 46538 1.0684 2.6896 402.00 52096 1.1960 3.1631 402.50 59196 1.3589 3.6362 402.70 62470 1.4341 3.7947 ACTUAL LEVEL POOL TABLE SUMMARY(COMBINED FLOWS) Description Inflow Storage Dischrg P. Stage Volume Outflow P.Time [CFS] ID ID [FT] CF [CFS) [Min] 2 Year Pond Outflow 5.07 ACT C 399.52 25651 0.842 900 5 Year Pond Outflow 7.17 ACT C 400.49 35256 1.495 690 10 Year Pond Outflow 8.43 ACT C 400.74 38059 1.931 660 100 Year Pond Outflow 12.10 ACT C 401.94 51423 3.057 570 File: 95244wworks Combined Flows Water Works Output qb ON 10 'J j < < E < /,7 < 0 -A • .MVO-VU- ....3K......A......... ""-"X.............. .. ......416 El ozy tt" .... .....�418 Q ----420 C) .. .. C). 422 w. . .... ..... .... ... 0 (4 .......:>...... ti..-0-A ...... 'PE ry, C) 50 IIW E3 .. .... ..... . . . . . . . . . . ....... . . . . . . . . .. . . . . . . - . . . . . . . . . . . H ou M::p 'E.-.14 D- . . . . . . . . . . . . . . . . 0 . . . . . . . . . . . . . . . . .. AC E.- W . . . . . . . . . . . . . . . . . . . . .. . . . . . . . . CD 0 Fn > V) U) of 0 Ct 0 M Me • No• un m cz WETLAND TRIBUTARY AREA EXHIBIT M. In WINDSONG p ja ill CITY OF RENTON WASHINGTON BASIN SUMMARY BASIN ID: UPI NAME:2 YEAR UPSTREAM SBUH METHODOLOGY TOTAL AREA..: 3.75 Acres BASEFLOWS 0.00 cfs RAINFALL TYPE..: USER1 PERVIOUS AREA PRECIPITATION..: 2.00 inches AREA..: 2.66 Acres TIME INTERVAL..: 10.00 min CN..: 84.33 TIME OF CONC..: 30.00 min IMPERVIOUS AREA ABSTRACTION COEFF 0.20 AREA..: 1.09 Acres CN..: 98.00 PEAK RATE: 0.65 cfs VOL: 0.33 Ac-ft TIME: 480 min BASIN ID:UP3 NAME: 10 YEAR UPSTREAM SBUH METHODOLOGY TOTAL AREA..: 3.75 Acres BASEFLOWS 0.00 cfs RAINFALL TYPE..: USER1 PERVIOUS AREA PRECIPITATION..: 2.95 inches AREA..: 2.66 Acres TIME INTERVAL..: 10.00 min CN..: 84.33 TIME OF CONC..: 30.00 min IMPERVIOUS AREA ABSTRACTION COEFF 0.20 AREA..: 1.09 Acres CN..: 98.00 PEAK RATE: 1.22 cfs VOL: 0.58 Ac-ft TIME: 480 min BASIN ID: UP4 NAME: 100 YEAR UPSTREAM SBUH METHODOLOGY TOTAL AREA..: 3.75 Acres BASEFLOWS 0.00 cfs RAINFALL TYPE..: TYPEIA PERVIOUS AREA PRECIPITATION..: 3.95 inches AREA..: 2.66 Acres TIME INTERVAL..: 10.00 min CN..: 84.33 TIME OF CONC..: 30.00 min IMPERVIOUS AREA ABSTRACTION COEFF : 0.20 AREA..: 1.09 Acres CN..: 98.00 PEAK RATE: 1.69 cfs VOL: 0.86 Ac-ft TIME: 490 min FILE: 95244WETLAND WINDSONG WETLAND RECHARGE Page l of 5 BASIN SUMMARY BASIN ID: W 1 NAME:2 YR EXIST WETLAND FLOWS-ONSITE SBUH METHODOLOGY TOTAL AREA..: 5.23 Acres BASEFLOWS 0.00 cfs RAINFALL TYPE..: USER] PERVIOUS AREA PRECIPITATION..: 2.00 inches AREA..: 5.16 Acres TIME INTERVAL..: 10.00 min CN..: 81.10 TIME OF CONC..: 53.83 min IMPERVIOUS AREA ABSTRACTION COEFF : 0.20 AREA..: 0.07 Acres CN..: 98.00 TcReach-Sheet L: 300.00 ns:0.4000 p2yr:2.00 s:0.0350 TcReach- Shallow L: 70.00 ks:5.00 s:0.0230 PEAK RATE: 0.29 cfs VOL: 0.27 Ac-ft TIME: 500 min BASIN ID: W3 NAME: 10 YR EXIST WETLAND FLOWS-ONSITE SBUH METHODOLOGY TOTAL AREA..: 5.23 Acres BASEFLOWS 0.00 cfs RAINFALL TYPE..: USER1 PERVIOUS AREA PRECIPITATION..: 2.95 inches AREA..: 5.16 Acres TIME INTERVAL..: 10.00 min CN..: 81.10 TIME OF CONC..: 53.83 min IMPERVIOUS AREA ABSTRACTION COEFF : 0.20 AREA..: 0.07 Acres CN..: 98.00 TcReach-Sheet L: 300.00 ns:0.4000 p2yr:2.00 s:0.0350 TcReach-Shallow L: 70.00 ks:5.00 s:0.0230 PEAK RATE: 0.79 cfs VOL: 0.57 Ac-ft TIME: 490 min BASIN ID: W4 NAME: 100 YR EXIST WETLAND FLOWS-ONSITE SBUH METHODOLOGY TOTAL AREA..: 5.23 Acres BASEFLOWS 0.00 cfs RAINFALL TYPE..: USER1 PERVIOUS AREA PRECIPITATION..: 3.95 inches AREA..: 5.16 Acres TIME INTERVAL..: 10.00 min CN..: 81.10 TIME OF CONC..: 53.83 min IMPERVIOUS AREA ABSTRACTION COEFF : 0.20 AREA..: 0.07 Acres CN..: 98.00 TcReach-Sheet L: 300.00 ns:0.4000 p2yr: 2.00 s:0.0350 TcReach- Shallow L: 70.00 ks:5.00 s:0.0230 PEAK RATE: 1.43 cfs VOL: 0.92 Ac-ft TIME: 490 min FILE: 95244WETLAND WINDSONG WETLAND RECHARGE Page 2 of 5 WETLAND RECHARGE HYDROGRAPH SUMMARY(PRE-DEV ELOPED FLOWS) DESCRIPTION HYD PEAK TIME VOLUME AREA NUM JCFSJ [Min] CF Ac 2 Year Upstream 1 0.648 480 14364 3.75 10 Year Upstream 3 1.218 480 25225 3.75 100 Year Upstream 4 1.685 490 37442 3.75 2 Year Onsite 5 0.290 500 11855 5.23 10 Year Onsite 7 0.793 490 24695 5.23 100 Year Onsite 8 1.431 490 40045 5.23 2 Year Total(H d 1 +H d 4) 10 0.911 490 26219 8.98 10 Year Total(H d 3 +H d 6) 12 1.973 480 49920 8.98 100 Year Total(H d 4+H d 8) 13 3.117 490 77487 8.98 WETLAND RECHARGE HYDROGRAPH SUMMARY(POST DEVELOPED FLOWS DESCRIPTION HYD PEAK TIME VOLUME AREA NUM CFSI (Minj 1CF Ac 2 YR POND INFLOW 1 5.071 470 74822 0.00 10 YR POND INFLOW 3 8.432 470 122878 0.00 100 YR POND INFLOW 4 12.105 470 175429 0.00 2 YR RELEASE TO WETLAND(RESTRICTOR 03) 6 0.305 790 24781 0.00 10 YR RELEASE TO WETLAND(RESTRICTOR 03) 7 0.950 550 46862 0.00 100 YR RELEASE TO WETLAND(RESTRICTOR 03) 8 1.349 540 65794 0.00 2 YEAR RELEASE TO NE 4 (RESTRICTOR 02) 10 0.617 790 50042 0.00 10 YEAR RELEASE TO NE 4 (RESTRICTOR 02) 11 1.512 550 76016 0.00 100 YEAR RELEASE TO NE 4 (RESTRICTOR 02) 12 2.447 540 109635 0.00 2 YR POND OUTFLOW(HYD 6+HYD 10) 17 0.922 790 74822 0.00 10 YR POND OUTFLOW(HYD 7+HYD 11) 19 2.462 550 122878 0.00 100 YR POND OUTFLOW(HYD8+HYD12) 20 3.795 540 175429 0.00 OUTFLOW CONTROL STRUCTURE COMBINATION DISCHARGE ID No. C Description: Combination discharge from detention pond Structure: 02 Structure: 03 MULTIPLE ORIFICE ID No. 02 Description: Discharge to NE 4t'Street Outlet Elev: 396.20 Elev: 394.20 ft Orifice Diameter: 3.3750 in. Elev: 400.40 ft Orifice 2 Diameter: 5.7500 in. Elev: 401.90 ft Orifice 3 Diameter: 3.5000 in. MULTIPLE ORIFICE ID No. 03 Description: Discharge to Wetland Outlet Elev: 396.20 Elev: 394.20 ft Orifice Diameter: 2.3750 in. Elev: 400.25 ft Orifice 2 Diameter: 4.7500 in. FILE: 95244WETLAND WINDSONG WETLAND RECHARGE Page 3 of 5 COMBINATION DISCHARGE ID No. C Description: Combination discharge from detention pond Structure: 02 Structure: 03 STAGE DISCHARGE FT CFS 396.20 0.0000 396.50 0.2531 397.00 0.4134 397.50 0.5270 398.00 0.6201 398.50 0.7009 399.00 0.7734 399.50 0.8396 400.00 0.9009 400.50 1.5483 401.00 2.2378 401.50 2.6896 402.00 3.1631 402.50 3.6362 402.70 3.7947 MULTIPLE ORIFICE ID No, 02 Description: Discharge to NE 4`h Street Outlet Elev: 396.20 Elev: 394.20 ft Orifice Diameter: 3.3750 in. Elev: 400.40 ft Orifice 2 Diameter: 5.7500 in. Elev: 401.90 ft Orifice 3 Diameter: 3.5000 in. STAGE DISCHARGE [FTJ CFS 396.20 0.0000 396.50 0.1693 397.00 0.2765 397.50 0.3524 398.00 0.4147 398.50 0.4688 399.00 0.5172 399.50 0.5615 400.00 0.6026 400.50 0.9247 401.00 1.3722 401.50 1.6526 402.00 1.9845 402.50 2.3335 402.70 2.4461 FILE: 95244WETLAND WINDSONG WETLAND RECHARGE Page 4 of 5 MULTIPLE ORIFICE ID No. 03 Description: Discharge to Wetland Outlet Elev: 396.20 Elev: 394.20 ft Orifice Diameter: 2.3750 in. Elev: 400.25 ft Orifice 2 Diameter: 4.7500 in. STAGE DISCHARGE [FT] [CFS 396.20 0.0000 396.50 0.0838 397.00 0.1369 397.50 0.1745 398.00 0.2054 398.50 0.2321 399.00 0.2561 399.50 0.2781 400.00 0.2984 400.50 0.6236 401.00 0.8656 401.50 1.0369 402.00 1.1786 402.50 1.3026 402.70 1.3486 FILE: 95244WETLAND WINDSONG WETLAND RECHARGE Page 5 of 5 SECTION V \ CONVEYANCE SYSTEM ANALYSIS & DESIGN i i ! SECTION V : CONVEYANCE SYSTEM ANALYSIS and DESIGN The site contains two separate tightline conveyance systems. The Onsite System will convey runoff from onsite areas to the proposed detention facility located near the southwest corner of the site. The Frontage System will convey runoff from upstream areas, as well as runoff associated with the frontage improvements along NE 41h Street, to the existing 18" concrete culvert located near the southwest corner of the site. The Santa Barbara Urban Hydrograph (SBUH) method of analysis was used to calculate the peak rates of runoff for the 25 and 100-year design storm events. Refer to the Pipe Tributary Area Map, located at the end of this section, for delineation of the area tributary to each catch basin. The pervious and impervious areas for the site were determined based on the current site plan. Refer to the Conveyance System SBUH Flows exhibit as well as the Conveyance System Flow Calculations exhibit, located in the appendix at the end of this section, for the flow tributary to each catch basin. The tightline conveyance systems were designed, in accordance with the 1990 King County Surface Water Design Manual (KCSWDM), to provide a minimum of 0.5 ft of freeboard at each structure in the system during the 25-year design storm event. The system was then analyzed during the 100-year design storm event and overtopping did not occur at any of the structures within the system. Refer to the 25 and 100-year Isopluvial Maps located in the appendix at the end of this section. Pipe sizing and hydraulic grade line calculations for the conveyance systems were performed using Eagle Point Software's computer program Storm Sewers. The methodology used for non-uniform flow analysis is the standard step energy balance. This procedure was used to determine the hydraulic grade line throughout the pipe network and is identical to that used for any open channel water surface profile. The steady state energy equation (Bernoulli equation) is used between upstream and downstream sections of each pipe in the network. The friction slope is then calculated by TECHNICAL INFORMATION REPORT FOR WINDSONG PAGE: V-1 applying Manning's equation at the upstream and downstream ends and averaging the slope between them. The program then performs three iterations to pinpoint the hydraulic grade line. Computations begin at the most downstream pipe and continue in an upward direction. A summary of the hydraulic grade line calculations, for each conveyance system, is provided below. Actual Storm Sewer output is located in the appendix at the end of this section (see HGL Calculations exhibit). ONSITE CONVEYANCE SYSTEM The onsite conveyance system collects runoff from the onsite area as well as runoff from approximately 3.75 acres of upstream area and conveys it to the combination detention / water quality facility. Refer to the following tables for a summary of the available freeboard in each catch basin. An initial tailwater elevation of 402.70 feet, corresponding to the maximum water surface of the pond, was used in the backwater analysis for both the 25 and 100-year events. FREEBOARD TABLE ONSITE CONVEYANCE SYSTEM Catch Basin Rim Elev. HGL Elev. Freeboard HGL Elev. Freeboard II I CB 3 404.48 402.96 1.52 403.07 1.41 CB 4 407.01 403.10 3.90 403.20 3.81 CB 5 408.50 404.38 4.12 404.41 4.08 CB 6 404.11 403.04 1.06 403.18 .93 CB 7 404.25 403.44 0.81 403.73 .51 CB 8 409.36 406.76 2.60 406.98 2.37 CB 9 411.28 407.41 3.86 407.47 3.80 CB 10 411.20 408.05 3.14 408.08 3.12 CB 11 410.47 408.09 2.38 408.10 2.37 CB 12 419.65 416.36 3.28 416.61 3.03 CB 13 420.10 417.61 2.49 418.33 1.77 CB 14 420.20 418.45 1.75 419.49 0.70 CB 15 419.90 418.46 1.43 419.50 0.39 CB 16 428.48 423.34 5.14 423.36 5.12 CB 17 424.87 421.96 2.91 422.14 2.73 CB 18 424.45 421.96 2.49 422.14 2.31 CB 19 428.09 425.74 2.34 425.86 2.22 CB 20 428.30 425.74 2.56 425.87 2.43 TECHNICAL INFORMATION REPORT FOR WINDSONG PAGE: V-2 Catch Basin Rim Elev. HGL Elev. Freeboard CB 21 434.43 429.17 5.25 429.29 5.13 CB 22 432.56 429.32 3.24 429.41 3.14 CB 23 432.56 429.47 3.08 429.52 3.04 CB 23A 433.05 429.54 3.50 429.59 3.46 CB 24 441.44 437.21 4.23 437.28 4.16 CB 25 441.44 437.38 4.06 437.43 4.00 CB 25A 441.93 437.45 4.48 437.49 4.43 CB 26 452.90 446.90 6.00 446.93 5.96 CB 27 452.37 447.86 4.50 447.89 4.48 CB 28 452.53 447.86 4.66 447.89 4.63 CB 29 437.85 434.29 3.56 434.28 3.57 CB 30 1 437.85 1 434.58 3.27 434.60 3.25 FRONTAGE CONVEYANCE SYSTEM The Frontage Conveyance System collects runoff from the existing ditch system located north of the site (both sides of Hoquiam Avenue NE) as well as runoff from the ditch system located east of the site (north side NE 4th Street). In addition to runoff from the ditch systems, the Frontage Conveyance System collects stormwater runoff from the north half of NE 4`h Street. An initial tailwater elevation of 396.50 feet, corresponding to the overflow elevation of the onsite wetland (obtained from as-built plans for the neighboring "Highland Market Place"project) was used in the backwater analysis. A summary of the SBUH flow estimates from these areas is provided below. A table, displaying the available freeboard in each catch basin, is located on the pages that follow. Flow Estimate- Hoquiam Avenue Ditch System Refer to the Pipe Tributary Area exhibit as well as the Upstream Area exhibit, both located in the appendix at the end of this section, to aid in the following discussion. The following conservative assumptions were made in determining land use parameters for the upstream tributary area: ♦ Rooftop/driveway areas were estimated by assuming 3,000 square feet per building. The number of buildings was estimated from the Upstream Area exhibit. ♦ The impervious area associated with Hoquiam Avenue SE was measured based on the Upstream Area exhibit. TECHNICAL INFORMATION REPORT FOR WINDSONG PAGE: V-3 ♦ The Impervious area associated with significant driveways and side streets was measured based on the Upstream Area exhibit. ♦ The landscaped area was assumed to be two and one-half times the total rooftop area. ♦ The remainder of the upstream area was modeled as second growth forest. ♦ The time of concentration was estimated to be 50 minutes (conservative) Total Area= 14.65 Acres Impervious Area = 4.45 Ac at CN = 98 2.62 Ac of rooftop/driveway areas (38 Bldg. x 3,000 SF/Bldg.) 1.31 Ac of roadway area - Hoquiam Ave NE (2,370 feet x 24 feet) 0.52 Ac of misc. roadways in basin (1,130 feet x 20 feet) Pervious Area = 10.20 Ac at CNµ, = 84.2 6.55 Ac of Landscaped Area (2.5 x 2.62 Ac) 3.65 Ac Second Growth Forest (14.65 Ac —4.45 Ac —6.55 Ac) Hoquiam Ave Ditch System - Flow Summary Storm Precip. Peak Flow Event [in] [cfsl 25-Year 3.45 4.82 100-Year 3.95 5.86 Flow Estimate—NE 41h Street Ditch System Refer to the Pipe Tributary Area exhibit as well as the Upstream Area exhibit, both located in the appendix at the end of this section, to aid in the following discussion. The following conservative assumptions were made in determining land use parameters for the upstream tributary area: ♦ Rooftop/driveway areas were estimated by assuming 3,000 square feet per building. The number of buildings was estimated from the Upstream Area exhibit. ♦ The impervious area associated with NE 41h Street was measured based on the Upstream Area exhibit. ♦ The landscaped area was assumed to be two and one-half times the total rooftop/driveway area. ♦ The remainder of the upstream area was modeled as second growth forest. ♦ The time of concentration was estimated to be 50 minutes (conservative) TECHNICAL INFORMATION REPORT FOR WINDSONG PAGE: V•4 Total Area= 8.25 Acres Impervious Area = 1.16 Ac at CN = 98 0.48 Ac of rooftop area (7 Bldg. x 3,000 SF/Bldg.) 0.68 Ac of roadway area-NE 41h Street (900 feet x 33 feet) Pervious Area = 7.09 Ac at CN,,, = 81.9 1.21 Ac of Landscaped Area (2.5 x 0.48 Ac) 5.88 Ac Second Growth Forest (8.25 Ac - 1.16 Ac - 1.21 Ac) 1.21x86+5.88x81 CN W = 7.09 =81.9 NE 41h Street Ditch System - Flow Summary Storm Precip. Peak Flow Event [in] [cfsl 25-Year 3.45 2.17 100-Year 3.95 2.72 100-YEAR FREEBOARD TABLE FRONTAGE CONVEYANCE SYSTEM Catch Basin Rim Elev. HGL Elev. Freeboard CB 31 402.20 399.58 2.62 INLET 3 1 A 401.68 399.96 1.72 CB 1B 404.00 398.88 5.12 CB 32 415.50 412.32 3.18 INLET 32A 415.04 413.25 1.79 CB 33 424.50 418.74 5.75 CB 34 427.33 425.42 1.90 INLET 34A 426.77 425.42 1.34 CB 35 432.40 428.29 4.10 INLET 35A 431.84 429.84 2.00 INTAKE 35B 433.50 429.03 4.47 CB 36 430.10 426.70 3.40 CB 37 436.00 435.19 0.81 CB 38 450.00 447.85 2.14 Note: Since the Frontage Conveyance System provides a minimum of 0.5 feet of freeboard in each structure during the 100-year storm event, the system was not modeled during the 25-year storm event. i TECHNICAL INFORMATION REPORT FOR WINDSONG PAGE: V-5 • APPENDIX . • 6/9/99 WINDSONG BKP BASIN SUMMARY BASIN ID: ON25 NAME:ONSITE CONVEYANCE SYSTEM-25 YR SBUH METHODOLOGY TOTAL AREA..: 11.07 Acres BASEFLOWS 0.00 cfs RAINFALL TYPE..: USER1 PERVIOUS AREA PRECIPITATION..: 3.45 inches AREA..: 4.10 Acres TIME INTERVAL..: 10.00 min CN..: 86.00 TIME OF CONC..: 5.00 min IMPERVIOUS AREA ABSTRACTION COEFF : 0.20 AREA..: 6.97 Acres CN..: 98.00 PEAK RATE: 8.55 cfs VOL: 2.57 Ac-ft TIME: 470 min BASIN ID: ON100 NAME: ONSITE CONVEYANCE SYSTEM-100 YR SBUH METHODOLOGY TOTAL AREA..: 11.07 Acres BASEFLOWS 0.00 cfs RAINFALL TYPE..: USERI PERVIOUS AREA PRECIPITATION..: 3.95 inches AREA..: 4.10 Acres TIME INTERVAL..: 10.00 min CN..: 86.00 TIME OF CONC..: 5.00 min IMPERVIOUS AREA ABSTRACTION COEFF : 0.20 AREA..: 6.97 Acres CN..: 98.00 PEAK RATE: 10.04 cfs VOL: 3.01 Ac-ft TIME: 470 min Note: Refer to the Conveyance System Flow Calculations exhibit as well as the Pipe Tributary Area exhibit for further details. FILE: 95244convey Conveyance System SBUH Flows Page I of 5 6/9/99 WINDSONG BKP BASIN SUMMARY BASIN ID: FR25 NAME: FRONTAGE CONVEYANCE-25 YR SBUH METHODOLOGY TOTAL AREA..: 1.14 Acres BASEFLOWS 0.00 cfs RAINFALL TYPE..: USER1 PERVIOUS AREA PRECIPITATION..: 3.45 inches AREA..: 0.00 Acres TIME INTERVAL..: 10.00 min CN..: 86.00 TIME OF CONC..: 5.00 min IMPERVIOUS AREA ABSTRACTION COEFF : 0.20 AREA..: 1.14 Acres CN..: 98.00 PEAK RATE: 1.03 cfs VOL: 0.31 Ac-ft TIME: 470 min BASIN ID: FR100 NAME:FRONTAGE CONVEYANCE- 100 YR SBUH METHODOLOGY TOTAL AREA..: 1.14 Acres BASEFLOWS 0.00 cfs RAINFALL TYPE..: USER1 PERVIOUS AREA PRECIPITATION..: 3.95 inches AREA..: 0.00 Acres TIME INTERVAL..: 10.00 min CN..: 86.00 TIME OF CONC..: 5.00 min IMPERVIOUS AREA ABSTRACTION COEFF : 0.20 AREA..: 1.14 Acres CN..: 98.00 PEAK RATE: 1.18 cfs VOL: 0.35 Ac-ft TIME: 470 min Note: Refer to the Conveyance System Flow Calculations exhibit as well as the Pipe Tributary Area exhibit for further details. FILE: 95244convey Conveyance System SBUH Flows Page 2 of 5 6/9/99 WINDSONG BKP BASIN SUMMARY BASIN ID: UP5 NAME: 25 YEAR UPSTREAM SBUH METHODOLOGY TOTAL AREA..: 3.75 Acres BASEFLOWS 0.00 cfs RAINFALL TYPE..: USERI PERVIOUS AREA PRECIPITATION..: 3.45 inches AREA..: 2.66 Acres TIME INTERVAL..: 10.00 min CN..: 84.33 TIME OF CONC..: 30.00 min IMPERVIOUS AREA ABSTRACTION COEFF : 0.20 AREA..: 1.09 Acres CN..: 98.00 PEAK RATE: 1.54 cfs VOL: 0.72 Ac-ft TIME: 480 min BASIN ID: UP4 NAME: 100 YEAR UPSTREAM SBUH METHODOLOGY TOTAL AREA..: 3.75 Acres BASEFLOWS 0.00 cfs RAINFALL TYPE..: USER1 PERVIOUS AREA PRECIPITATION..: 3.95 inches AREA..: 2.66 Acres TIME INTERVAL..: 10.00 min CN..: 84.33 TIME OF CONC..: 30.00 min IMPERVIOUS AREA ABSTRACTION COEFF : 0.20 AREA..: 1.09 Acres CN..: 98.00 PEAK RATE: 1.87 cfs VOL: 0.86 Ac-ft TIME: 480 min Note: Refer to the Upstream Area Map for area delineation. FILE:95244convey Conveyance System SBUH Flows Page 3 of 5 6/9/99 WINDSONG BKP 0 BASIN SUMMARY BASIN ID: A25 NAME: AREA I-25 YEAR STORM SBUH METHODOLOGY TOTAL AREA..: 8.25 Acres BASEFLOWS : 0.00 cfs RAINFALL TYPE..: USERI PERVIOUS AREA PRECIPITATION..: 3.45 inches AREA..: 7.09 Acres TIME INTERVAL..: 10.00 min CN..: 81.90 TIME OF CONC..: 50.00 min IMPERVIOUS AREA ABSTRACTION COEFF : 0.20 AREA..: 1.16 Acres CN..: 98.00 PEAK RATE: 2.17 cfs VOL: 1.34 Ac-ft TIME: 490 min BASIN ID: A 100 NAME: AREA I- 100 YEAR STORM SBUH METHODOLOGY TOTAL AREA..: 8.25 Acres BASEFLOWS : 0.00 cfs RAINFALL TYPE..: USER] PERVIOUS AREA PRECIPITATION..: 3.95 inches AREA..: 7.09 Acres TIME INTERVAL..: 10.00 min CN..: 81.90 TIME OF CONC..: 50.00 min IMPERVIOUS AREA ABSTRACTION COEFF : 0.20 AREA..: 1.16 Acres CN..: 98.00 PEAK RATE: 2.72 cfs VOL: 1.63 Ac-ft TIME: 490 min Note: Area I corresponds to the area tributary to the existing ditch located along NE 4`h Street. Refer to the Upstream Area Map for area delineation. FILE: 95244convey Conveyance System SBUH Flows Page 4 of 5 6/9/99 WINDSONG BKP BASIN SUMMARY BASIN ID: B25 NAME:AREA II-25 YEAR STORM SBUH METHODOLOGY TOTAL AREA..: 14.65 Acres BASEFLOWS 0.00 cfs RAINFALL TYPE..: USER1 PERVIOUS AREA PRECIPITATION..: 3.45 inches AREA..: 10.20 Acres TIME INTERVAL..: 10.00 min CN..: 84.20 TIME OF CONC..: 50.00 min IMPERVIOUS AREA ABSTRACTION COEFF : 0.20 AREA..: 4.45 Acres CN..: 98.00 PEAK RATE: 4.82 cfs VOL: 2.82 Ac-ft TIME: 490 min BASIN ID: B100 NAME: AREA II - 100 YEAR STORM SBUH METHODOLOGY TOTAL AREA..: 14.65 Acres BASEFLOWS 0.00 cfs RAINFALL TYPE..: USER1 PERVIOUS AREA PRECIPITATION..: 3.95 inches AREA..: 10.20 Acres TIME INTERVAL..: 10.00 min CN..: 84.20 TIME OF CONC..: 50.00 min IMPERVIOUS AREA ABSTRACTION COEFF : 0.20 AREA..: 4.45 Acres CN..: 98.00 PEAK RATE: 5.86 cfs VOL: 3.37 Ac-ft TIME: 490 min Note: Area II corresponds to the area tributary to the existing ditch located along Hoquiam Avenue NE. Refer to the Upstream Area Map for area delineation. FILE: 95244convey Conveyance System SBUH Flows Page 5 of 5 5/26/99 WINDSONG BKP Total Area: 11.07 Ac "Total 25 Year Flow: 8.55 cfs "Total 100 Year Flow: 10.04 cfs Flows Used for Onsite Conveyance System Sizing CB# Tributary Area % of Total Area 25 Yr. Flow 100 Yr. Flow (Ac) (%) (cfs) (cfs) 2 0.37 3.34 0.29 0.34 3 0.66 5.96 0.51 0.60 4 0.44 3.97 0.34 0.40 5 0.58 5.24 0.45 0.53 6 0.38 3.43 0.29 0.34 7 0.07 0.63 0.05 0.06 8 0.84 7.59 0.65 0.76 9 0.78 7.05 0.60 0.71 10 0.51 4.61 0.39 0.46 11 0.07 0.63 0.05 0.06 12 0.47 4.25 0.36 0.43 13 0.35 3.16 0.27 0.32 14 0.08 0.72 0.06 0.07 15 0.6 5.42 0.46 0.54 16 0 0.00 0.00 0.00 17 0.09 0.81 0.07 0.08 18 0.17 1.54 0.13 0.15 19 0.09 0.81 0.07 0.08 20 0.62 5.60 0.48 0.56 21 0 0.00 0.00 0.00 22 0.34 3.07 0.26 0.31 23 0.11 0.99 0.08 0.10 23A 0.93 8.40 0.72 0.84 24 0.59 5.33 0.46 0.54 25 0.21 1.90 0.16 0.19 25A 0.82 7.41 0.63 0.74 26 0 0.00 0.00 0.00 27 0.44 3.97 0.34 0.40 28 0.03 0.27 0.02 0.03 29 0.15 1.36 0.12 0.14 30 0.23 2.08 0.18 0.21 37 0.05 0.45 0.04 0.05 SUM 11.07 100 8.55 10.04 "The total flow represents the SBUH flow calculated for the total area tributary to the entire onsite conveyance system. This flow was then distributed to each of the catch basins based on the area tributary to each catch basin. Refer to the Pipe Tributary Area Map. Note: The following offsite flows were added to the flow listed for CB 8 in the table above: 100 year offsite flow= 1.87 cfs 25 year offsite flow= 1.54 cfs File: 95244flows Onsite Conveyance System Conveyance System Flow Calculations 5/26/99 WINDSONG BKP Total Area: 1.14 Ac 'Total 25 Year Flow: 1.03 cfs *Total 100 Year Flow: 1.18 cfs Flows Used for Frontage Conveyance System Sizing CB # Tributary Area % of Total Area 25 Yr. Flow 100 Yr. Flow (Ac) (%) (cfs) (cfs) INLET 31A 0.46 40.35 0.42 0.48 INLET 32A 0.32 28.07 0.29 0.33 INLET 34A 0.26 22.81 0.23 0.27 INLET 35A 0.1 8.77 0.09 0.10 SUM 1.14 100 1.03 1.18 The total flow represents the SBUH flow calculated for the area tributary to the frontage conveyance system. This flow was then distributed to each of the structures based on the area tributary to each structure. Refer to the Pipe Tributary Area Map. File: 95244flows2 Frontage Conveyance System Conveyance System Flow Calculations a FIR, p"Irr, - 0102 .F��. �� �, /,�►''�!����,.�.-. .;ram_;, =74 WM It ; �ME till �'� ,ram lip 40 ONE Uddl - W;�__;•1:i-"ERR!r•� �►•-'�-t�� IN VA - ♦ tr� t 06/03/99 STORM SEWER SUMMARY REPORT 25 YEAR DESIGN FILE: ON25.STM RAINFALL FILE: RENTON98.RND 25 YEAR DESIGN STORM I = 10.180/ ( Tc + 0.000) ^ 0.630 'RWINE#I DESCRIPTION ZINC ARIRUNOFFCIINLTIMEIINLT IIINC CIAI INPUTQ IUNIFORMISIZE/IINVERT IPIPE I NVAL IHGLSLOPEIHYD GRD I VEL I DOWNLINE# ITOT ARIWEIGHTDI Tc ITOTL IITOT CIAI TOTALQ IFLOWCAPITYPE 1UP/DOWN ILEN IINVSLOPI JLC IUP/DOWN IUP/DOWN I I (ac) I C I (min) 1 (in/h) 1 (cfs) I (cfs) I (cfs) 1 (in) I (ft) 1 (ft) 1 (ft/ft) 1 (ft/ft) 1 (ft) I (ft/s) I I I I I I I I I I I I I I I 1 1 CB 2 1 0.01 0.901 5.001 3.691 0.001 0.291 1 24D1 399.181 361 0.0121 0.0011 402.731 3.19 1 DNLN = 0 1 0.01 0.001 18.461 1.621 0.001 10.031 17.31 24D1 399.001 1 0.0051 1.00 1 402.701 3.19 1 1 1 I 1 1 I I I 1 1 1 1 1 I 2 1 CB 3 1 0.01 0.901 5.001 3.691 0.001 0.511 1 12D1 400.461 561 0.0121 0.0011 402.921 1.66 1 DNLN = 1 1 0.01 0.001 7.921 2.761 0.001 1.301 2.71 12D1 400.181 1 0.0051 1.00 1 402.891 1.66 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 3 1 CB 4 1 0.01 0.901 5.001 3.691 0.001 0.341 1 12D1 402.491 1711 0.0121 0.0001 403.041 1.82 1 DNLN = 2 1 0.01 0.001 5.901 3.331 0.001 0.791 4.21 12D1 400.461 1 0.0121 1.25 1 402.961 1.01 I I I I I I I I I I I I I 1 1 4 1 CB 5 1 0.01 0.901 5.001 3.691 0.001 0.451 1 12D1 404.001 911 0.0121 0.0141 404.381 2.45 1 DNLN = 3 1 0.01 0.001 5.001 3.691 0.001 0.451 5.01 12D1 402.501 1 0.0161 1.00 1 403.101 0.91 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 5 1 CB 6 1 0.01 0.901 5.001 3.691 0.001 0.291 1 24D1 399.321 271 0.0121 0.0011 402.901 2.69 1 DNLN = 1 1 0.01 0.001 18.301 1.631 0.001 8.441 17.61 24D1 399.181 1 0.0051 1.25 1 402.891 2.69 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 6 1 CB 7 1 0.01 0.901 5.001 3.691 0.001 0.051 1 18D1 399.941 241 0.0121 0.0031 403.111 4.61 1 DNLN = 5 1 0.01 0.001 18.211 1.641 0.001 8.151 8.01 18D1 399.821 1 0.0051 1.00 1 403.041 4.61 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 7 1 CB 8 1 0.01 0.901 5.001 3.691 0.001 2.191 1 18DI 405.001 1451 0.0121 0.0181 406.091 5.91 1 DNLN = 6 1 0.01 0.001 17.751 1.661 0.001 8.101 21.31 18D1 399.941 1 0.0351 1.25 1 403.441 4.58 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 8 1 CB 9 1 0.01 0.901 5.001 3.691 0.001 0.601 1 12D1 406.821 631 0.0121 0.0081 407.251 3.20 1 DNLN = 7 1 0.01 0.001 10.381 2.331 0.001 1.041 5.61 12D1 405.501 1 0.0211 1.00 1 406.761 1.32 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 9 1 CB 10 1 0.01 0.901 5.001 3.691 0.001 0.391 1 12D1 407.701 321 0.0121 0.0201 408.051 2.34 1 DNLN = 8 1 0.01 0.001 5.001 3.691 0.001 0.391 6.41 12D1 406.821 1 0.0281 1.00 1 407.411 0.81 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 10 1 CB 11 1 0.01 0.901 5.001 3.691 0.001 0.051 1 12D1 407.971 2301 0.0121 0.0031 408.091 1.32 1 DNLN = 8 1 0.01 0.001 5.001 3.691 0.001 0.051 2.71 12D1 406.821 1 0.0051 1.00 1 407.411 0.10 I I I I I I I I I I I I I I I 11 1 CB 12 1 0.01 0.901 5.001 3.691 0.001 0.361 1 12D1 414.801 1831 0.0121 0.0491 415.721 6.47 DNLN = 7 1 0.01 0.001 17.271 1.691 0.001 4.871 8.71 12D1 405.501 1 0.0511 1.00 1 406.761 6.20 I I I I I I I I I I I I 1 1 12 1 CB 13 1 0.01 0.901 5.001 3.691 0.001 0.271 1 12D1 415.441 1071 0.0121 0.0071 417.101 5.74 1 DNLN = 11 1 0.01 0.001 16.961 1.711 0.001 4.511 3.01 12D1 414.801 1 0.0061 1.00 1 416.361 5.74 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 13 1 CB 14 1 0.01 0.901 5.001 3.691 0.001 0.061 1 12D1 415.721 461 0.0121 0.0061 417.891 5.40 1 DNLN = 12 1 0.01 0.001 16.811 1.721 0.001 4.241 3.01 12D1 415.441 1 0.0061 1.25 1 417.611 5.40 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 14 1 CB 15 1 0.01 0.901 5.001 3.691 0.001 0.461 1 12D1 416.401 591 0.0121 0.0001 418.461 0.59 1 DNLN = 13 1 0.01 0.001 5.001 3.691 0.001 0.461 4.11 12D1 415.721 1 0.0121 1.00 1 418.451 0.59 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 15 1 CB 16 1 0.01 0.901 5.001 3.691 0.001 0.001 1 12D1 420.571 1081 0.0121 0.0271 421.391 5.41 1 DNLN = 13 1 0.01 0.001 16.461 1.741 0.001 3.721 8.21 12D1 415.721 1 0.0451 1.25 1 418.451 4.74 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 16 1 CB 17 1 0.01 0.901 5.001 3.691 0.001 0.071 1 12D1 418.441 1301 0.0121 0.0001 421.961 0.25 1 DNLN = 15 1 0.01 0.001 7.951 2.761 0.001 0.201 2.71 12D1 417.791 1 0.0051 1.00 1 421.961 0.25 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 17 1 CB 18 1 0.01 0.901 5.001 3.691 0.001 0.131 1 12D1 421.451 471 0.0121 0.0001 421.961 0.32 1 DNLN = 16 1 0.01 0.001 5.001 3.691 0.001 0.131 2.71 12D1 421.221 1 0.0051 1.00 1 421.961 0.21 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 18 1 CB 19 1 0.01 0.901 5.001 3.691 0.001 0.071 1 12D1 424.371 581 0.0121 0.0201 424.921 7.24 1 DNLN = 15 1 0.01 0.001 14.231 1.911 0.001 3.221 5.51 12D1 423.211 1 0.0201 1.00 1 423.761 7.24 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 19 1 CB 20 1 0.01 0.901 5.001 3.691 0.001 0.481 1 12D1 424.801 421 0.0121 0.0001 425.741 0.63 1 DNLN = 18 1 0.01 0.001 5.001 3.691 0.001 0.481 3.91 12D1 424.371 1 0.0101 1.00 1 425.741 0.61 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 20 1 CB 21 1 0.01 0.901 5.001 3.691 0.001 0.001 1 12DI 428.151 961 0.0121 0.0321 428.841 4.60 1 DNLN = 18 1 0.01 0.001 13.831 1.951 0.001 2.671 7.71 12D1 424.371 1 0.0391 1.00 1 425.741 3.40 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 21 1 CB 22 1 0.01 0.901 5.001 3.691 0.001 0.261 1 12D1 428.681 531 0.0121 0.0001 429.161 2.83 1 DNLN = 20 1 0.01 0.001 5.281 3.571 0.001 1.061 3.91 12D1 428.151 1 0.0101 1.25 1 429.171 1.35 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 22 1 CB 23 1 0.01 0.901 5.001 3.691 0.001 0.081 1 12D1 428.961 281 0.0121 0.0011 429.341 2.93 1 DNLN = 21 1 0.01 0.001 5.071 3.661 0.001 0.801 3.91 12D1 428.681 1 0.0101 1.00 1 429.321 1.51 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 23 1 CB 23A 1 0.01 0.901 5.001 3.691 0.001 0.721 1 12D1 429.051 91 0.0121 0.0071 429.541 2.59 1 DNLN = 22 1 0.01 0.001 5.001 3.691 0.001 0.721 3.91 12D1 428.961 1 0.0101 1.00 1 429.471 1.78 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 24 1 CB 24 1 0.01 0.901 5.001 3.691 0.001 0.461 1 12D1 436.451 1861 0.0121 0.0421 436.991 3.74 I DNLN = 20 1 0.01 0.001 12.761 2.051 0.001 1.611 8.11 12D1 428.151 1 0.0451 1.00 1 429.171 2.05 I I I I I I I I i I I I I I I 25 1 CB 25 1 0.01 0.901 5.001 3.691 0.001 0.161 1 12D1 436.871 281 0.0121 0.0011 437.251 2.92 1 DNLN = 24 1 0.01 0.001 5.071 3.661 0.001 0.791 4.71 12D1 436.451 1 0.0151 1.00 1 437.211 1.24 File: ONSITE25SMRY ONSITE SYSTEM-25 YEAR HGL CALCUALTIONS 06/03/99 STORM SEWER SUMMARY REPORT 25 YEAR DESIGN FILE: ON25.STM RAINFALL FILE: RENTON98.RND 25 YEAR DESIGN STORM I = 10.180/ ( Tc + 0.000) ^ 0.630 INE#I DESCRIPTION IINC ARIRUNOFFCIINLTIMEIINLT IIINC CIAI INPUTQ IUNIFORMISIZE/IINVERT IPIPE I NVAL IHGLSLOPEIHYD GRD I VEL I DOWNLINE# ITOT ARIWEIGHTDI Tc ITOTL IITOT CIAI TOTALQ IFLOWCAPITYPE IUP/DOWN ILEN IINVSLOPI JLC IUP/DOWN IUP/DOWN I I (ac) I C I (min) I (in/h) I (cfs) I (cfs) I (cfs) I (in) I (ft) I (ft) I (ft/ft) I (ft/ft) I (ft) I (ft/s) I I I I I I I I I I I I I I I 26 1 CB 25A I 0.01 0.901 5.001 3.691 0.001 0.631 1 12D) 437.001 91 0.0121 0.0081 437.451 2.66 1 DNLN = 25 1 0.01 0.001 5.001 3.691 0.001 0.631 4.61 12D1 436.871 I 0.0141 1.00 1 437.381 1.57 I 1 1 1 1 1 I I I 1 1 1 I 1 1 27 I CB 26 1 0.01 0.901 5.001 3.691 0.001 0.001 1 12D1 446.541 2381 0.0121 0.0401 446.791 2.29 I DNLN = 24 1 0.01 0.001 9.981 2.391 0.001 0.361 7.91 12D1 436.451 1 0.0421 1.25 1 437.211 0.57 I 1 1 1 1 I I 1 1 I I I 1 1 1 28 I CB 27 1 0.01 0.901 5.001 3.691 0.001 0.341 1 12D1 447.501 1921 0.0121 0.0041 447.751 2.29 I DNLN = 27 1 0.01 0.001 8.261 2.691 0.001 0.361 2.71 12D1 446.541 I 0.0051 1.25 1 446.901 1.44 I 1 I 1 I I 1 1 1 I I I 1 1 1 29 1 CB 28 1 0.01 0.901 5.001 3.691 0.001 0.021 1 12D1 447.601 201 0.0121 0.0001 447.861 0.12 1 DNLN = 28 I 0.01 0.001 5.001 3.691 0.001 0.021 2.71 12D1 447.501 I 0.0051 1.00 1 447.861 0.08 I I I I I I I I I I I I I 1 1 ' 30 1 CB 29 1 0.01 0.901 5.001 3.691 0.001 0.121 I 12D1 433.671 2381 0.0121 0.0441 433.801 5.03 1 DNLN = 15 1 0.01 0.001 5.511 3.471 0.001 0.301 8.11 12D1 423.211 1 0.0441 1.25 I 423.341 5.03 1 I I I I 1 1 1 I 1 1 I 1 I I 31 1 CB 30 I 0.01 0.901 5.001 3.691 0.001 0.181 I 12D1 434.351 341 0.0121 0.0091 434.581 1.87 1 DNLN = 30 I 0.01, 0.001 5.001 3.691 0.001 0.181 5.51 12D1 433.671 1 0.0201 1.00 I 434.291 0.35 File: ONSITE25SMRY ONSITE SYSTEM-25 YEAR HGL CALCUALTIONS WINDSONG STORM SEWER CUSTOM REPORT 25 YEAR DESIGN Catch Basin Rim Elev. HGL Elev. Freeboard CB 3 404.48 402.96 1.52 CB 4 407.01 403.10 3.90 CB 5 408.50 404.38 4.12 CB 6 404.11 403.04 1.06 CB 7 404.25 403.44 0.81 CB 8 409.36 406.76 2.60 CB 9 411.28 407.41 3.86 CB 10 411.20 408.05 3.14 CB 11 410.47 408.09 2.38 CB 12 419.65 416.36 3.28 CB 13 420.10 417.61 2.49 CB 14 420.20 418.45 1.75 CB 15 419.90 418.46 1.43 CB 16 428.48 423.34 5.14 CB 17 424.87 421.96 2.91 CB 18 424.45 421.96 2.49 CB 19 428.09 425.74 2.34 CB 20 428.30 425.74 2.56 CB 21 434.43 429.17 5.25 CB 22 432.56 429.32 3.24 CB 23 432.56 429.47 3.08 CB 23A 433.05 429.54 3.50 CB 24 441.44 437.21 4.23 CB 25 441.44 437.38 4.06 CB 25A 441.93 437.45 4.48 CB 26 452.90 446.90 6.00 CB 27 452.37 447.86 4.50 CB 28 452.53 447.86 4.66 CB 29 437.85 434.29 3.56 CB 30 437.85 434.58 3.27 FILE:ONSITE25FBD ONSITE SYSTEM-25 YEAR HGL CALCULATIONS 06/03/99 WINDSONG STORM SEWER CUSTOM REPORT 100 YEAR DESIGN Catch Basin Rim Elev. HGL Elev. Freeboard CB 3 404.48 403.07 1.41 CB 4 407.01 403.20 3.81 CB 5 408.50 404.41 4.08 CB 6 404.11 403.18 .93 CB 7 404.25 403.73 .51 CB 8 409.36 406.98 2.37 CB 9 411.28 407.47 3.80 CB 10 411.20 408.08 3.12 CB 11 410.47 408.10 2.37 CB 12 419.65 416.61 3.03 CB 13 420.10 418.33 1.77 CB 14 420.20 419.49 0.70 CB 15 419.90 419.50 0.39 CB 16 428.48 423.36 5.12 CB 17 424.87 422.14 2.73 CB 18 424.45 422.14 2.31 CB 19 428.09 425.86 2.22 CB 20 428.30 425.87 2.43 CB 21 434.43 429.29 5.13 CB 22 432.56 429.41 3.14 CB 23 432.56 429.52 3.04 CB 23A 433.05 429.59 3.46 CB 24 441.44 437.28 4.16 CB 25 441.44 437.43 4.00 CB 25A 441.93 437.49 4.43 CB 26 452.90 446.93 5.96 CB 27 452.37 447.89 4.48 CB 28 452.53 447.89 4.63 CB 29 437.85 434.28 3.57 CB 30 437.85 434.60 3.25 FILE:ON SITE 100FBD ONSITE SYSTEM- 100 YEAR HGL CALCULATIONS 06/03/99 06/03/99 STORM SEWER SUMMARY REPORT 100 YEAR DESIGN FILE: ON100.STM RAINFALL FILE: RENTON98.RND 100 YEAR DESIGN STORM I = 10.180/ ( Tc + 0.000) ^ 0.630 'qvpFLi INE#I DESCRIPTION IINC ARIRUNOFFCIINLTIMEIINLT IIINC CIAI INPUTQ IUNIFORMISIZE/IINVERT (PIPE I NVAL IHGLSLOPEIHYD GRD I VEL I DOWNLINE# ITOT ARIWEIGHTDI Tc ITOTL IITOT CIAI TOTALQ IFLOWCAPITYPE IUP/DOWN ILEN IINVSLOPI JLC IUP/DOWN IUP/DOWN I I (ac) I C I (min) I (in/h) I (cfs) I (cfs) I (cfs) 1 (in) I (ft) 1 (ft) I (ft/ft) I (ft/ft) I (ft) I (ft/s) I I I I I I I I I I I I I I I 1 I CB 2 1 0.01 0.901 5.001 3.691 0.001 0.341 1 24D1 399.181 361 0.0121 0.0011 402.741 3.78 1 DNLN = 0 1 0.01 0.001 17.571 1.671 0.001 11.861 17.31 24D1 399.001 I 0.0051 1.00 1 402.701 3.78 1 I 1 I 1 1 I 1 1 I 1 I I I I 2 I CB 3 I 0.01 0.901 5.001 3.691 0.001 0.601 1 12D1 400.461 561 0.0121 0.0011 403.011 1.95 I DNLN = 1 I 0.01 0.001 7.821 2.791 0.001 1.531 2.71 12D1 400.181 I 0.0051 1.00 1 402.961 1.95 I I I 1 I I I 1 1 1 I I 1 1 I 3 1 CB 4 1 0.01 0.901 5.001 3.691 0.001 0.401 I 12Dt 402.491 1711 0.0121 0.0001 403.141 1.75 1 DNLN = 2 1 0.01 0.001 5.871 3.341 0.001 0.931 4.21 12D1 400.461 1 0.0121 1.25 1 403.071 1.18 1 1 1 1 1 1 1 I I I I 1 I 1 1 4 1 CB 5 1 0.01 0.901 5.001 3.691 0.001 0.531 I 12D1 404.001 911 0.0121 0.0131 404.411 2.57 1 DNLN = 3 1 0.01 0.001 5.001 3.691 0.001 0.531 5.01 12D1 402.501 1 0.0161 1.00 1 403.201 0.91 I I 1 1 1 1 I 1 1 I 1 1 1 1 1 5 I CB 6 I 0.01 0.901 5.001 3.691 0.001 0.341 I 24D1 399.321 271 0.0121 0.0011 402.991 3.18 I DNLN = 1 I 0.01 0.001 17.421 1.681 0.001 9.991 17.61 24D1 399.181 I 0.0051 1.25 1 402.961 3.18 I I 1 I I I I 1 I 1 I I 1 1 I 6 I CB 7 I 0.01 0.901 5.001 3.691 0.001 0.061 I 18D1 399.941 241 0.0121 0.0041 403.271 5.46 1 DNLN = 5 1 0.01 0.001 17.351 1.691 0.001 9.651 8.01 18D1 399.821 1 0.0051 1.00 1 403.181 5.46 1 1 1 1 1 1 1 1 1 I 1 1 I 1 1 7 1 CB 8 1 0.01 0.901 5.001 3.691 0.001 2.631 1 18D1 405.001 1451 0.0121 0.0171 406.181 6.42 1 DNLN = 6 1 0.01 0.001 16.941 1.711 0.001 9.591 21.31 18D1 399.941 I 0.0351 1.25 I 403.731 5.43 1 1 1 I 1 1 I I I 1 1 I 1 1 I 8 1 CB 9 1 0.01 0.901 5.001 3.691 0.001 0.711 1 12DI 406.821 631 0.0121 0.0051 407.291 3.39 1 DNLN = 7 1 0.01 0.001 10.111 2.371 0.001 1.231 5.61 12D1 405.501 1 0.0211 1.00 1 406.981 1.57 1 1 1 I I I 1 I 1 I I 1 I I 1 9 1 CB 10 I 0.01 0.901 5.001 3.691 0.001 0.461 1 12D1 407.701 321 0.0121 0.0191 408.081 2.46 1 DNLN = 8 I 0.01 0.001 5.001 3.691 0.001 0.461 6.41 12D1 406.821 1 0.0281 1.00 I 407.471 0.85 I I I 1 1 1 I 1 1 1 1 1 1 I I 10 I CB 11 1 0.01 0.901 5.001 3.691 0.001 0.061 1 12D1 407.971 2301 0.0121 0.0031 408.101 1.39 1 DNLN = 8 1 0.01 0.001 5.001 3.691 0.001 0.061 2.71 12D1 406.821 1 0.0051 1.00 1 407.471 0.11 I I I I I I I I I I I I I I I 11 1 CB 12 1 0.01 0.901 5.001 3.691 0.001 0.431 1 12D1 414.801 1831 0.0121 0.0481 415.751 7.43 I DNLN = 7 1 0.01 0.001 16.531 1.741 0.001 5.731 8.71 12D1 405.501 I 0.0511 1.00 I 406.981 7.30 I I I I I I I I I I I I I I 1 12 1 CB 13 1 0.01 0.901 5.001 3.691 0.001 0.321 1 12D1 415.441 1071 0.0121 0.0091 417.621 6.75 1 DNLN = 11 1 0.01 0.001 16.261 1.761 0.001 5.301 3.01 12D1 414.801 1 0.0061 1.00 1 416.611 6.75 1 1 I 1 1 1 I I 1 I I 1 I I I 13 1 CB 14 I 0.01 0.901 5.001 3.691 0.001 0.071 1 12D1 415.721 461 0.0121 0.0081 418.711 6.34 1 DNLN = 12 I 0.01 0.001 16.141 1.761 0.001 4.981 3.01 12D1 415.441 I 0.0061 1.25 1 418.331 6.34 1 1 I 1 1 1 1 1 1 1 1 1 1 1 1 14 1 CB 15 1 0.01 0.901 5.001 3.691 0.001 0.541 1 12D1 416.401 591 0.0121 0.0001 419.501 0.69 1 DNLN = 13 1 0.01 0.001 5.001 3.691 0.001 0.541 4.11 12D1 415.721 1 0.0121 1.00 1 419.491 0.69 1 I 1 I I I 1 1 I I 1 I I I I 15 I CB 16 1 0.01 0.901 5.001 3.691 0.001 0.001 1 12D1 420.571 1081 0.0121 0.0181 421.461 5.94 I DNLN = 13 1 0.01 0.001 15.831 1.791 0.001 4.371 8.21 12D1 415.721 I 0.0451 1.25 1 419.491 5.56 I 1 1 I 1 1 I 1 I 1 1 1 I 1 1 1 16 1 CB 17 1 0.01 0.901 5.001 3.691 0.001 0.081 1 12D1 418.441 1301 0.0121 0.0001 422.141 0.29 1 DNLN = 15 1 0.01 0.001 8.431 2.661 0.001 0.231 2.71 12D1 417.791 1 0.0051 1.00 1 422.141 0.29 1 I I 1 I 1 1 1 I 1 I 1 1 I I 17 1 CB 18 I 0.01 0.901 5.001 3.691 0.001 0.151 I 12D1 421.451 471 0.0121 0.0001 422.141 0.26 I DNLN = 16 I 0.01 0.001 5.001 3.691 0.001 0.151 2.71 12D1 421.221 1 0.0051 1.00 1 422.141 0.20 I I 1 I 1 1 I I 1 1 I 1 1 1 I 18 I CB 19 1 0.01 0.901 5.001 3.691 0.001 0.081 I 12D1 424.371 581 0.0121 0.0201 424.981 7.52 I DNLN = 15 1 0.01 0.001 13.101 2.011 0.001 3.791 5.51 12D1 423.211 I 0.0201 1.00 1 423.821 7.52 I 1 1 1 1 1 1 1 I I 1 I I 1 1 19 1 CB 20 I 0.01 0.901 5.001 3.691 0.001 0.561 I 12D1 424.801 421 0.0121 0.0001 425.871 0.71 1 DNLN = 18 I 0.01 0.001 5.001 3.691 0.001 0.561 3.91 12D1 424.371 1 0.0101 1.00 1 425.861 0.71 I I I I I I I I I I I I I I I 20 1 CB 21 1 0.01 0.901 5.001 3.691 0.001 0.001 1 12D1 428.151 961 0.0121 0.0321 428.901 4.97 I DNLN = 18 1 0.01 0.001 12.751 2.051 0.001 3.151 7.71 12D1 424.371 1 0.0391 1.00 I 425.861 4.01 I 1 1 1 1 I I 1 I 1 1 I I I I 21 I CB 22 1 0.01 0.901 5.001 3.691 0.001 0.311 I 12D1 428.681 531 0.0121 0.0001 429.291 2.50 1 DNLN = 20 1 0.01 0.001 5.271 3.571 0.001 1.251 3.91 12D1 428.151 1 0.0101 1.25 1 429.291 1.59 1 1 I 1 I 1 1 I 1 1 I 1 1 1 I 22 1 CB 23 I 0.01 0.901 5.001 3.691 0.001 0.101 1 12D1 428.961 281 0.0121 -0.0011 429.381 3.04 1 DNLN = 21 I 0.01 0.001 5.071 3.661 0.001 0.941 3.91 12D1 428.681 1 0.0101 1.00 I 429.411 1.53 I 1 1 I 1 I I 1 1 1 1 1 I I 1 23 I CB 23A 1 0.01 0.901 5.001 3.691 0.001 0.841 1 12D1 429.051 91 0.0121 0.0071 429.591 2.58 1 DNLN = 22 1 0.01 0.001 5.001 3.691 0.001 0.841 3.91 12D1 428.961 I 0.0101 1.00 I 429.521 1.86 1 I I I I 1 1 1 1 1 I 1 I 1 1 24 1 CB 24 I 0.01 0.901 5.001 3.691 0.001 0.541 1 12D1 436.451 1861 0.0121 0.0421 437.031 3.99 DNLN = 20 1 0.01 0.001 11.781 2.151 0.001 1.901 8.11 12D1 428.151 1 0.0451 1.00 1 429.291 2.42 I I I I I I I I I I I I I I I 25 1 CB 25 I 0.01 0.901 5.001 3.691 0.001 0.191 I 12D1 436.871 281 0.0121 0.0001 437.281 3.08 1 DNLN = 24 I 0.01 0.001 5.071 3.661 0.001 0.931 4.71 12D1 436.451 I 0.0151 1.00 1 437.281 1.33 File: OnsiteI00SMRY ONSITE SYSTEM- 100 YEAR HGL CALCULATIONS 06/03/99 STORM SEWER SUMMARY REPORT 100 YEAR DESIGN FILE: ON100.STM RAINFALL FILE: RENTON98.RND 100 YEAR DESIGN STORM I = 10.180/ ( Tc + 0.000) ^ 0.630 11WINE#1 DESCRIPTION IINC ARIRUNOFFCIINLTIMEIINLT IIINC CIAI INPUTQ IUNIFORMISIZE/IINVERT IPIPE I NVAL IHGLSLOPEIHYD GRD I VEL I DOWNLINE# ITOT ARIWEIGHTDI Tc ITOTL IITOT CIA I TOTALQ IFLOWCAPITYPE IUP/DOWN ILEN IINVSLOPI JLC IUP/DOWN IUP/DOWN I I (ac) I C I (min) I (in/h) I (cfs) I (cfs) I (cfs) 1 (in) I (ft) I (ft) 1 (ft/ft) 1 (ft/ft) I (ft) I (ft/s) I I I I I I I I I I I I I 1 1 26 I CB 25A I 0.01 0.901 5.001 3.691 0.001 0.741 1 12D1 437.001 91 0.0121 0.0071 437.491 2.81 I DNLN = 25 I 0.01 0.001 5.001 3.691 0.001 0.741 4.61 12D1 436.871 1 0.0141 1.00 1 437.431 1.65 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 27 1 CB 26 1 0.01 0.901 5.001 3.691 0.001 0.001 1 12D1 446.541 2381 0.0121 0.0401 446.821 2.41 1 DNLN = 24 1 0.01 0.001 9.161 2.521 0.001 0.431 7.91 12D1 436.451 1 0.0421 1.25 1 437.281 0.62 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 28 1 CB 27 1 0.01 0.901 5.001 3.691 0.001 0.401 1 12D1 447.501 1921 0.0121 0.0041 447.781 2.41 1 DNLN = 27 1 0.01 0.001 7.531 2.851 0.001 0.431 2.71 12D1 446.541 1 0.0051 1.25 1 446.931 1.51 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 29 1 CB 28 1 0.01 0.901 5.001 3.691 0.001 0.031 1 12D1 447.601 201 0.0121 0.0001 447.891 0.16 1 DNLN = 28 1 0.01 0.001 5.001 3.691 0.001 0.031 2.71 12D1 447.501 1 0.0051 1.00 1 447.891 0.11 I I I I I I I I I I I I I 1 1 30 1 CB 29 1 0.01 0.901 5.001 3.691 0.001 0.141 1 12D1 433.671 2381 0.0121 0.0441 433.821 4.91 1 DNLN = 15 1 0.01 0.001 5.481 3.491 0.001 0.351 8.11 12D1 423.211 1 0.0441 1.25 1 423.361 4.91 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 31 1 CB 30 1 0.01 0.901 5.001 3.691 0.001 0.211 1 12DI 434.351 341 0.0121 0.0091 434.601 1.96 1 DNLN = 30 1 0.01 0.001 5.001 3.691 0.001 0.211 5.51 12D1 433.671 1 0.0201 1.00 1 434.281 0.42 File: OnSitel00SMRY ONSITE SYSTEM- 100 YEAR HGL CALCULATIONS 06/08/99 STORM SEWER SUMMARY REPORT 100 YEAR DESIGN FILE: 95244OFF.STM RAINFALL FILE: RENTON98.RND 100 YEAR DESIGN STORM I = 10.180/ ( Tc + 0.000) ^ 0.630 IROPPLINE#1 DESCRIPTION ZINC ARIRUNOFFCIINLTIMEIINLT IIINC CIAI INPUTQ IUNIFORMISIZE/IINVERT IPIPE I NVAL 1HGLSLOPEIHYD GRD I VEL I DOWNLINE# ITOT ARIWEIGHTDI Tc ITOTL IITOT CIAI TOTALQ IFLOWCAPITYPE IUP/DOWN ILEN IINVSLOPI JLC IUP/DOWN IUP/DOWN I I (ac) I C I (min) 1 (in/h) 1 (cfs) I (cfs) I (cfs) 1 (in) I (ft) 1 (ft) 1 (ft/ft) 1 (ft/ft) 1 (ft) I (ft/s) I I I I I I I I I I I I I I I 1 1 CB 31 1 0.01 0.901 6.301 3.191 0.001 0.001 I 24D1 394.441 1671 0.0121 0.0041 397.161 6.96 1 DNLN = 0 1 0.01 0.001 9.101 2.531 0.001 21.861 17.41 24D1 393.601 1 0.0051 1.25 1 396.501 6.96 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 2 1 INLET 31A 1 0.01 0.901 6.301 3.191 0.001 0.481 1 12D1 399.481 51 0.0121 0.0761 399.961 4.23 1 DNLN = 1 1 0.01 0.001 6.301 3.191 0.001 0.481 5.51 12D1 399.381 1 0.0201 1.00 1 399.581 4.23 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 3 1 CB 1B 1 0.01 0.901 6.301 3.191 0.001 12.101 1 18D1 396.651 161 0.0121 0.0481 398.881 6.85 1 DNLN = 1 1 0.01 0.001 6.301 3.191 0.001 12.101 37.21 18D1 394.941 1 0.1071 1.00 1 398.101 6.85 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 4 1 CB 32 1 0.01 0.901 6.301 3.191 0.001 0.001 1 18D1 410.541 2921 0.0121 0.0471 411.701 6.32 1 DNLN = 1 1 0.01 0.001 8.261 2.691 0.001 9.281 26.31 18D1 394.941 1 0.0531 1.00 1 398.101 5.25 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 5 1 INLET 32A 1 0.01 0.901 6.301 3.191 0.001 0.331 1 12D1 412.851 41 0.0121 0.0801 413.251 3.92 1 DNLN = 4 1 0.01 0.001 6.301 3.191 0.001 0.331 5.51 12D1 412.771 1 0.0201 1.00 1 412.931 3.92 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 6 1 CB 33 1 0.01 0.901 6.301 3.191 0.001 0.001 1 18D1 417.001 2261 0.0121 0.0261 418.151 6.20 1 DNLN = 4 1 0.01 0.001 7.591 2.841 0.001 8.951 19.21 18DI 410.541 1 0.0291 1.00 1 412.321 5.06 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 7 1 CB 34 1 0.01 0.901 6.301 3.191 0.001 0.001 1 12D1 422.831 261 0.0121 0.0801 423.191 11.97 1 DNLN = 6 1 0.01 0.001 7.411 2.881 0.001 3.091 10.91 12D1 420.751 1 0.0801 1.00 1 421.111 11.97 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 8 1 INLET 34A 1 0.01 0.901 6.301 3.191 0.001 0.271 1 12D1 424.571 41 0.0121 0.0011 425.421 0.38 1 DNLN = 7 1 0.01 0.001 6.301 3.191 0.001 0.271 5.51 12D1 424.491 1 0.0201 1.00 1 425.421 0.35 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 9 1 CB 35 1 0.01 0.901 6.301 3.191 0.001 0.001 1 12D1 427.241 2021 0.0121 0.0131 427.951 4.71 1 DNLN = 7 1 0.01 0.001 6.611 3.101 0.001 2.821 4.51 12D1 424.491 1 0.0141 1.00 1 425.421 3.71 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 10 1 INLET 35A 1 0.01 0.901 6.301 3.191 0.001 0.101 1 12D1 429.641 41 0.0121 0.0441 429.841 2.51 1 DNLN = 9 1 0.01 0.001 6.301 3.191 0.001 0.101 5.51 12D1 429.561 1 0.0201 1.00 1 429.661 2.51 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 11 1 INTAKE 35B 1 0.01 0.901 6.301 3.191 0.001 2.721 1 12DI 428.001 761 0.0121 0.0101 429.031 4.64 112I DNLN = 9 1 0.01 0.001 6.301 3.191 0.001 2.721 3.91 12D1 427.241 1 0.0101 1.00 1 428.291 3.46 I CB 36 I I 1 I I I I I 0.01 0.901 6.301 3.191 0.001 0.001 I 12D1 923.991 2391 0.0121 0.0291 429.951 7.57 1 DNLN = 6 1 0.01 0.001 7.061 2.971 0.001 5.861 6.11 12D1 417.501 1 0.0251 1.00 1 418.741 7.46 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 13 1 CB 37 1 0.01 0.901 6.301 3.191 0.001 0.001 1 12D1 432.371 1221 0.0121 0.0511 432.971 11.97 1 DNLN = 12 1 0.01 0.001 6.891 3.021 0.001 5.861 8.71 12D1 426.101 1 0.0511 1.00 1 426.701 11.97 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 14 1 CB 38 1 0.01 0.901 6.301 3.191 0.001 5.861 1 12D1 446.001 2651 0.0121 0.0481 447.851 7.57 1 DNLN = 13 1 0.01 0.001 6.301 3.191 0.001 5.861 8.71 12D1 432.371 1 0.0511 1.00 1 435.191 7.46 File: FRONT100SMRY FRONTAGE SYSTEM HGL CALCULATIONS WINDSONG STORM SEWER CUSTOM REPORT 100 YEAR DESIGN Catch Basin Rim Elev. HGL Elev. Freeboard CB 31 402.20 399.58 2.62 INLET 3 1 A 401.68 399.96 1.72 CB 1B 404.00 398.88 5.12 CB 32 415.50 412.32 3.18 INLET 32A 415.04 413.25 1.79 CB 33 424.50 418.74 5.75 CB 34 427.33 425.42 1.90 INLET 34A 426.77 425.42 1.34 CB 35 432.40 428.29 4.10 INLET 35A 431.84 429.84 2.00 INTAKE 35B 433.50 429.03 4.47 CB 36 430.10 426.70 3.40 CB 37 436.00 435.19 0.81 CB 38 450.00 447.85 2.14 FILE:FRONT100FBD FRONTAGE CONVEYANCE SYSTEM HGL CALCULATIONS 06/08/99 / SECTION VI SPECIAL REPORTS & STUDIES SECTION VI : SPECIAL REPORTS and STUDIES Windsong Traffic Impact Analysis: March 31, 1999 by Transportation Planning and Engineering (TPE) Wetland Analysis Report (Windsong): January 15, 1999 by B-twelve Associates Inc. Subsurface Exploration and Geotechnical Engineering Report (Windsong Subdivision): February 1998 by Associated Earth Sciences, Inc. Copies of the above reports may be obtained upon request. TECHNICAL INFORMATION REPORT FOR WINDSONG PAGE: VI-1 - 991,110 SECTION VII ul BASIN & COMMUNITY PLAN AREAS 0 SECTION VII : BASIN and COMMUNITY PLANNING AREAS As identified in the Level One Offsite Drainage Analysis and Preliminary Drainage Concept for Windsong (refer to the end of Section III of this report), the site is located within the Lower Cedar River Drainage Basin and drains to the east branch of Maplewood Creek. According to the King County Surface Water Design Manual, the site is located within the Newcastle Community Planning Area. TECHNICAL INFORMATION REPORT FOR WINDSONG PAGE: VII-I SECTION VIII : OTHER PERMITS Determination of Non-Significance SEPA Threshold Determination — King County DDES TECHNICAL INFORMATION REPORT FOR WINDSONG PAGE: VIII-1 SECTION VIII OTHER PERMITS IVSECTION IX EROSION/SEDIMENTATION CONTROL DESIGN i i i SECTION IX : EROSION/SEDIMENTATION CONTROL DESIGN The temporary erosion and sedimentation control plan was designed to reduce the discharge of sediment-laden runoff from the site. The plan is comprised of temporary measures (rock construction entrance, filter fence, interim catch basin protection, etc.) as well as permanent measures (hydroseeding, landscaping, etc.). In general, runoff will sheet flow across cleared areas and into temporary interceptor swales that convey runoff to one of two proposed sediment retention facility. The sediment retention facilities were designed using the 1994 updates to the erosion control chapter of the 1990 King County Surface Water Design Manual. Generally, the sediment retention facilities were designed to settle out the design particle (medium silt, 0.02 mm) at a 2-year inflow rate. A summary of the calculations (flow estimates, overflow riser sizing and surface area calculations) used to size the sediment retention ponds are located on the pages that follow. Refer to the TESC Tributary Area Map, located in the appendix of this report, as well as the TESC Flow Rates exhibit, located in the appendix at the end of this section, to aid in the following discussion. PHASE I OF CONSTRUCTION During Phase I of construction, runoff will be collected and conveyed to the proposed water quality/detention facility, which will serve as the sediment retention pond in this case. Cleared Conditions Total Area = 7.10 Acres Impervious Area = 0.00 Ac @ CN = 98 Pervious Area = 7.10 Ac @ CN= 87 (bare dirt) Time of Concentration = 10.00 minutes Sediment Vault - H dro ra h Summar Storm Precip. Peak Flow Volume Time of Peak 2 Year Cleared 2.00 1.45 1 23,522 480 100 Year Cleared 3.95 4.68 1 66,646 480 TECHNICAL INFORMATION REPORT FOR WINDSONG PAGE: IX-1 Required Surface Area = 2(Q2yr,)/0.00096 Required Surface Area = 2 (1.45)/0.00096 Required Surface Area = 3,020 square feet As designed, the sediment pond provides approximately 9,907 square feet of surface area at an elevation of 400.00 (top of temporary riser). Temporary Riser Pipe The temporary riser was sized to convey the peak rate of runoff from the 100-year/ 24- hour design storm event assuming the site is cleared. Orifice = 3.782(DZ)(H)112 4.68 = 3.782(1.002)(H)1/2 H = 1.53 feet As designed, the temporary riser was selected to be 12 inches in diameter and set at an elevation of 400.00 which is 4.00 feet below the top of the pond berm (404.00). In addition to the temporary riser, the sediment pond will have an overflow spillway as outlined in Section IV of this report. PHASE II OF CONSTRUCTION During Phase H of construction, runoff will be collected and conveyed to the proposed sediment pond. Runoff leaving the sediment pond will discharge to the proposed conveyance system located in NE 41h Street. Cleared Conditions Total Area = 4.30 Acres Impervious Area = 0.00 Ac @ CN = 98 Pervious Area = 4.30 Ac @ CN= 87 (bare dirt) Time of Concentration = 10.00 minutes Phase II - H dro ra h Summar Storm Precip. Peak Flow Volume Time of Peak 2 Year Cleared 2.00 1 0.88 13,939 480 100- Year Cleared 1 3.95 1 2.84 40,510 480 Required Surface Area= 2(Q2yr.)/0.00096 Required Surface Area= 2 (0.88)/0.00096 Required Surface Area = 1,833 square feet TECHNICAL INFORMATION REPORT FOR WINDSONG PAGE: IX-2 As designed, the sediment pond provides approximately 2,084 square feet of surface area at an elevation of 425.5 (top of temporary riser pipe). Temporary Riser Pipe The temporary riser was sized to convey the peak rate of runoff from the 100-year/ 24- hour design storm event assuming the site is cleared. QWeir = 9.739(D)(H)3/2 2.84 = 9.739(1.25)(H)3/2 H = 0.38 feet As designed, the temporary riser was selected to be 15-inches in diameter and set at an elevation of 425.50 which is 1.5 feet below the top of the pond berm (427.00). TECHNICAL INFORMATION REPORT FOR WINDSONG PAGE: IX-3 APPENDIX • WINDSONG BASIN SUMMARY BASIN ID: T1A NAME: 2 YR TESC-PHASE I SBUH METHODOLOGY TOTAL AREA..: 7.10 Acres BASEFLOWS 0.00 cfs RAINFALL TYPE..: USER1 PERVIOUS AREA PRECIPITATION..: 2.00 inches AREA..: 7.10 Acres TIME INTERVAL..: 10.00 min CN..: 87.00 TIME OF CONC..: 10.00 min IMPERVIOUS AREA ABSTRACTION COEFF 0.20 AREA..: 0.00 Acres CN..: 98.00 PEAK RATE: 1.45 cfs VOL: 0.54 Ac-ft TIME: 480 min BASIN ID:T I B NAME: 10 YR TESC-PHASE I SBUH METHODOLOGY TOTAL AREA..: 7.10 Acres BASEFLOWS 0.00 cfs RAINFALL TYPE..: USER1 PERVIOUS AREA PRECIPITATION..: 2.95 inches AREA..: 7.10 Acres TIME INTERVAL..: 10.00 min CN..: 87.00 TIME OF CONC..: 10.00 min IMPERVIOUS AREA ABSTRACTION COEFF 0.20 AREA..: 0.00 Acres CN..: 98.00 PEAK RATE: 2.96 cfs VOL: 1.00 Ac-ft TIME: 480 min BASIN ID: TIC NAME: 100 YR TESC-PHASE I SBUH METHODOLOGY TOTAL AREA..: 7.10 Acres BASEFLOWS 0.00 cfs RAINFALL TYPE..: USERI PERVIOUS AREA PRECIPITATION..: 3.95 inches AREA..: 7.10 Acres TIME INTERVAL..: 10.00 min CN..: 87.00 TIME OF CONC..: 10.00 min IMPERVIOUS AREA ABSTRACTION COEFF : 0.20 AREA..: 0.00 Acres CN..: 98.00 PEAK RATE: 4.68 cfs VOL: 1.53 Ac-ft TIME: 480 min FILE:95244TESC TESC FLOW RATES WINDSONG BASIN SUMMARY BASIN ID: T2A NAME:2 YR TESC-PHASE II SBUH METHODOLOGY TOTAL AREA..: 4.30 Acres BASEFLOWS 0.00 cfs RAINFALL TYPE..: USERI PERVIOUS AREA PRECIPITATION..: 2.00 inches AREA..: 4.30 Acres TIME INTERVAL..: 10.00 min CN..: 87.00 TIME OF CONC..: 10.00 min IMPERVIOUS AREA ABSTRACTION COEFF : 0.20 AREA..: 0.00 Acres CN..: 98.00 PEAK RATE: 0.88 cfs VOL: 0.32 Ac-ft TIME: 480 min BASIN ID: T2B NAME: 10 YR TESC-PHASE II SBUH METHODOLOGY TOTAL AREA..: 4.30 Acres BASEFLOWS 0.00 cfs RAINFALL TYPE..: USERI PERVIOUS AREA PRECIPITATION..: 2.95 inches AREA..: 4.30 Acres TIME INTERVAL..: 10.00 min CN..: 87.00 TIME OF CONC..: 10.00 min IMPERVIOUS AREA ABSTRACTION COEFF : 0.20 AREA..: 0.00 Acres CN..: 98.00 PEAK RATE: 1.80 cfs VOL: 0.61 Ac-ft TIME: 480 min BASIN ID: T2C NAME: 100 YR TESC-PHASE II SBUH METHODOLOGY TOTAL AREA..: 4.30 Acres BASEFLOWS 0.00 cfs RAINFALL TYPE..: USERI PERVIOUS AREA PRECIPITATION..: 3.95 inches AREA..: 4.30 Acres TIME INTERVAL..: 10.00 min CN..: 87.00 TIME OF CONC..: 10.00 min IMPERVIOUS AREA ABSTRACTION COEFF : 0.20 AREA..: 0.00 Acres CN..: 98.00 PEAK RATE: 2.84 cfs VOL: 0.93 Ac-ft TIME: 480 min FILE:95244TESC TESC FLOW RATES Ir SECTION X \ BOND QUANTITIES WORKSHEET RETENTION/DETENTION FACILITY SUMMARY SHEET DECLARATION OF COVENANT SECTION X : BOND QUANTITIES WORKSHEET A bond quantities worksheet will be provided, upon request, at the time of final submittal. DETENTION SUMMARY SKETCH Copies of the pond plan and pond sections, obtained from the Road and Storm Drainage plans for Windsong, are located in the appendix at the end of this section. TECHNICAL INFORMATION REPORT FOR WINDSONG PAGE: X-1 APPENDIX • TYPE 11-54' k 26 OIL-WA TER SEPARATOR "a VA� a- CB 4 10 TRIAD ASSOCIATES a- Cm]Ep...., n 111d U,e PI...i.1 U.d..p DE TEN RON Pomg CA TE 11814 115th 1- T::--I.-- N.��ULWI -4 ;E IT - 1, -1 T I I-ww.q?m .......... 27 C RONS. ..... I -TH'PLA- 11111 TALL I*DOCK.12'WDC PLACE -0*1- EXISTING RIP RAP PRO C -I PRIVATE S I OM PT 25,6J vim.._ _I_ �`♦---1 ' O -I 0 BUILDING DRAINAGE USEMfNT TYP 28 ................ OUIFALL 2A KEY MAP TOP OF DEAD I.... .399.00 PUBLIC UTILITY NOT TO SCALE EAi EWENT TVP PROPOSED (ryp)ROCKERY SEE SHEET 17 FOR SECTIONS r 29 ♦ ♦ %♦ ♦ ;;bVIDE 2' a RIP RAP BERM IV A 2A a &WCF FLOWSN,70 POND BOFFOM %\ J0 HIGH OE NTION POND F QL FENCE PER j8 FENCING NOTES. SHEET TA) 4 I SCALE: 1" =20' NSIALL' N.A OT I 0 10 20 40 POND Borrow PER DETAIL, ju A -WEEF 20 J,PUBLIC STORM X rz F EX NO TE, DETENTION POND TO BEMAINTAJ TOP OF 5'WOE LL I L A ELEV 402.J5 81'THE CITY OF REM TON. HOUSE 0 ------- ------ 402.70' ....I--♦ --- --402= %1% 1 x I --------------i----- ----------- NOT ---------- 1. ALL DRAINAGE PIPING TO BE ADVANCED \% 398 ♦ DRAINAGE SYSTEMS(ADS)N-12 OR EQUAL. ♦X TOP OF GABFOW 2. AL TTE III ♦ WALL EL 494.50 L CA TCH BASINS TO BE TYPE I UNLESS ♦ ----k- OlkERMISr SPECIFIED. LAND it ♦ ♦ J. ALL GRATES TO BE VANED,LOCKING GRATES V-7 - - �f? - - - " U171GA --392------- YRA T 4. TYFE 9 CATCH BASINS HAW BEEN 92rD TO ------ MEET CURRENT*WO T KNOCKOUT REQUIREMENTS 7ON IRA r REOUIREMENTS USING ADS N-12 PIPE. CONTRACTOR MAY MIORK DIREC71Y WIN CATCH BE REWCEIA TED BASIN MANUFACTURER TO REDUCE CATCH BASIN FOR 0(PREPARED ♦ SIPS PROWDED KNOCKOUT REOLUREMENTS ARE �ey 0 ♦% S771-L MET us (�;ELL kv I so rrom EL.J87 70 C LOCA7701V OF EXIS77NG UnL177ES SHOWN IS APPROXIMATE AND MAY NOT BE ACCURATE OR ALL INCLUSIVE. IT IS THE CONTRACTOR 5 -L-W.AmAP.it PIE RESFON-981LI TY TO FIELD VERIFY LOCA 77ON TffOJECrmNAaTr INSTALL I' OF U77LI77ES PRIOR TO PROCEEDING WITH DESIGNED:III Goom PEIJ rflErnxx N RIP RAP PR01EC170M CADD: a CONSTRUCTION. YERrtuM TO POND BOTTOM u EMERGENCY OVERFLOW CHECKED: w Gowft PE. < EN DETAX, DATE: 61"9 < V 1. • INTAKE IA BENCHMARK AND DATUM DATUM,NAD 1983191(OA-';--D ON 77ES To CITY OF RENTON MONUMENTS NUMBERS SCAM: HOM,I"-20' TYPE 11-84" TAIL to VEIT, NIA 4 L I-I : 1851 AND 852) W/RLSTRIC70R AND CONTOUR WIERVAL 2' S=ruR x 55 VERTIC4 DAIU,1 NAVO 1988 -sI DRIGNA TING BENCHMARKS OVERFLOW IF T IA. CITY OF RLNT0N BENCHMARK 1852 BRASS SURFACE molvum,-mr AT THE 128TH STREET AND L Ex TP 147TRUSEAUNWUEDS IS ------- --- ELEVATION 454.77 FEET J. CITY OF RENTON BENCHMARK 1851-3 W-BRA SURFACE MONUMEN I AT THE 18'GONG IE 394.7 TP 6452 WDE OUZFALL I �Pl1 CD I[MA RACK a 0.50x TO SHEET L7 -1:1� 5 ------- ��:7AI;;�39ag'FEET DETAN-•SA&T 18-we T 17 ZNBA INSTALL[,;Z S Ex Pp 2LEF WALL Ory OF RENTON BENCHMARK 1 2119-BRASS SURFACE MONUMENT AT THE ------ 40D ------- I IAILI 0 WISRSECTION OF SE. t28M STREET AND 142ND A WNUE S. ----A-f ------ ---------------- --- 167-- CLEVA7701V 426.42 FEET ------- NAL 0 -—-------- -------- -------- -- ------- E�ES-2/0' 12'CONC IE J9J8 lu ---- ---- (DW --- EX SDMI EX IL- W B'WDE S Checked tor Cornplionce to City Standards ----------S5--- Ij 1 12'CONC IE 39J 7 - 9,,2, L--L -- SECITONS C ---j9.T7- - -48, STAMP NOT VAUD ;2"CONC W IE -- ----- I TYPE DATED 12"CONC E.IE 393.7 -L-SS ---- OUD LOCKIN L UNLESS SIGNED AND D a"CaN-S IE 393.6 A --- -27.A500.37-ZO t I , NE 4TH STREET NSTALL DRI PPRaA01 25 8"CONC N.IF 39J.7 PER I FAIL 1 19. • _ BOTT SIR 391.7 26 1AIL r 1A JOB NUMBER -SW,*LAC--WL� "1 27+65 00,32,20-LJ` 95-244 i 1 27 mn 28 SHEET NUMBER SS DETAIL,SHEET 2 LL I f I I I I C1999 TRIAD ASSOCIATES[J7 17 L ------------------------- ................. .......... ........................................................................................... .............. ..................... ... ............................................................. ESE POND PLAN, SHEET .................................................................................... .............. ..................... ......................................................................................... ........................................................................................................ h. ......... TRIAD ASSOCIATES -------------- 410: ................ ...................... 410 CL cl- ...................................... 410 -4-- 410 5'WIDE OVERFLOW L.,d ll��PI...ig - un -------- nd SIG D-g. ......................................... .......................—------- .?MLWA.��L_!02................. CELL/IPOINT ........._.. . ------------ KQ420-2100PE POINT CELL 12 11814 II51h All.NE Kwklmd,WA 9M-U2J Tel 4M.8211448 4n.921-34111 ....................... ............ .......... ................................... TO F- IOW—0F LiZ—STORili:40-2 M-- 5'-12- StOf F HINGE PROPOSED GRADE)DOD SLO-C HINGE POINT (TIP) FINISH 0 2.OOX SLO-1 HINGE POINT -- 00 LA?Sl7NG GROUND GROUND 4W ILI) Q) Y 64A IL;� EMBANKMENT IOY PRO7rc"O`v. LIE STORAGE POI4D BOTTOM39ZOO TOP OF DEAD 4 J96.00 DETAIL,94EE: 17 1..11.20 TOP 401.68 Q) 4W El 4 NO 17 v 11 SE AV Jv0I- .............------------------ .......................................... ............ ..................................................... ............ ......... .............-.................. . E BOTTOM OF DEAD ST RACE 388,10 C8 31 TYP -48' • POND BOTTOM EL 357.70 a' ID,LOCA ING LID 39"0 ........... wraV4`O2.2.f rc ;2"IE 399.38 S All cf) 1w7) ........... ........... CELL 12 81'Traw IE EL im. Is L J94. 24: 394.9444 LCI I_11PE�--Bl INTAKE?A Q Z '7:;7,AC-,A"JE'E0ACK,8';R VE1 T 18) 4 .70 o .................................................................................... ...................................................................... 12 1E 396.20'8.IE 396.20 P SEC TION A OND -A LXIS77NG GRADE cc LQ U. INTAKE IA TO CB 31 U • i —----------------- EE:P01VO Pt 4N. SHEET i ISEE POND PLAN, SHEET 151 ........... 50'WEILAND 550'WETLAND Wry w 3 L 410 -,!410 F w WEILAND ................------------------- ...................... --—---------- BBERM 3 BERM Tap.a, g .............. R 404.00 MWS 402. ;4W AtNff EL 402.70 TOP I F DEAD STOP,GE 402.50 4f-12'a 1.05X -------------------- ... ...... ....... ......... t Exis RNG 4 GROUND ------------------------ ---- W'ELMA' DUNLAP.F.PIC BOTTOM OF DEAD \64--1 V17.11TATED SWAGE e a5ox PER EL 396. STORAGE EL J97.FO EVS77NG YE 395.45 GROUND TOP D STORAGE DICIA11-SHEET 16 DESIGNED:w Gowft P-LIR Ptosrs OUTFAL4 IC c 1011111 SEOM T CkDD'. OL Me AM STORAGE 12 lE 3 77 (Srf DETAIL 94EET 20) W1 5',5'4'RfPRAP PAD mo CHECKED: Gowft PL. < 11-411- DATE: 61"19 a W/RE 7RICIOR AND 0 WRFL4 OW STRUCTURE SCAIE: HORIZ.:;: 20' m: < VERT.: 5- ............ �00 12T BorlDw OF DEAD I 18'OC P-70 STORAGE EL 8(irTOW EL 38770 al a'.'.SPENT—----------------I- A .......... ................................................................................... ------------------ ............. ........... ............... ...........-----------................... ........ .............; ............. POND SEC MON B-B POND SECTION C-C IST z TONAL 0 EXISTING GRADE CIS 1 TO WETLAND Llvs7wc GRADE (Typ) Checked/w Compliance to City Standards STAMP NOT VAUD UNLESS SIGNED AND DATED • NOTE.• POW BERMS TO BE KEYED INTO ACCEPTABLE SUBGRADE PER GEOTECHNICAL JOB NUMBER RECOMMENDA TIONS. SHEET NUMBER 17OF 95-244 CAGE: 1"= 20' HORIZ 0 Z 5' VERT, 01999 TRIAD ASSOCIATE'[ F~— ? FENCING NOTES.• o 3 _ �I 11- 1.FENCES SHALL BE A MINIMUM OF 6 FEET IN HEIGHT EXCEPRW: THE FENCE MAY BE A MINIMUM OF J FEET IN HEIGHT IF ME DEPTH OF THE IMPOUNDMENT (/7 1•--y Stormwater TMw DO11A Is le ow 4WR TO THE BOTTOM OF THEMEASURED FROM THE FENCED SLVATION IN THE OPE,UP TO THBEOEMERGENCY OVERFLO OF THE W WATER SURFACE)IS FIVENI,DIRECTLY 3T I I }1 76/8- �P�„P,4r.a•,rr...r FfErORLESS TRIAD ASSOCIATES o I I M" Storage Pond �� a NK��w r.�r^ 2.ACCESS ROAD GATES SHALL BE 16 FEET IN WDM CLNDSTMIC M9 SWNCING SECTIONS 8 FEET IN MDTH. Proj_mum—.1 LiN 24' J.PEDESTRIAN ACCESS GATES(IF NEEDED)SHALL BE 4 FEET IN WDM. Wd Sury , 4.FENCE MATERIAL SHALL BE N. 11 GAUGE CALVAN/ZED STEEL FABRIC WTH BONDED VINYL COATING, VINYL laud Uu Pl—im J-e COA 17NC SHALL BE CWPARBLF WTH THE SURRWNOINC fNVIRWMENT(E.G.,GREEN IN OPEN•GRASSY AREAS TAU.w ArchilecWrc %r iy..r�.y- ( ) AND BUCK ORBROFOMNJFEET IN W)QDEEPOEO AREAS). FENCE POSTS SNAIL BE GACVAHIZ£D STEEL. WIN TOP CAPS.AND sit,5eri1n S WALE DETAIL SET A MINIMUM IN COVOFErE. CROSS BARS SHALL CONNECT ADJACENT FENCE POSTS 11814 1154h Me.N6 Ih4hud,TA 990 -M NOT TO SCALE ALL POSTS CROSS BARS AND GATES SHALL BE PAINTED O7 COATED ME SAME COLOR AS THE VINYL CLAD Tel 425A21A441 I.425A21A411 FENCE FABRIC TA I—INNAURM _A.AA wc.mm 5. MOOD FENCES ARE ALLOADJACENT JACE D IN SUBDIVISIONSLTWIERE ME FENCE INT BE MAINTAINED REQUIRE BY ENS SHALL x CONASSDITION OF SU DII4 OEN r PROPERTY STA L07 OMNERS FENCE MAINTENANCE REQUIREMENTS SHALL IR A CWOBE EC SUBOVISIW AND A STA7EALNT DETAILING MAINTENANCE RESIPWS/BILIRfS AND REQUIREMENTS I MUST BE RECORDED. Q I 0 6. WOOD FENCES FOOTINGS SHALL HAVE PRESSURE TREATED(Gy GAL CONTACT)POSTS EITHER SET IN E E B DEEP (', BEE CEDAR FOOL RNCS QP ATTACHED TO OR HEMLOCK BY GALVANIZED BRACKETS RAMS AND FENCE BOARDS SHALL BE CEDAR O4 PRESSURE 7REA iEO FIR OR HEMLOCK. x Q - TYPE 9-84'CATCH BASH GRQUr(rYP.) •1-J. ~ / eraw aD3 e7ape8M,% L SPEC/F/CATIONS: S 8- FOR CATSW CONTROL SLIE.. 48-.24" ROD FOR OfANd/T/DRAIN. / QUTFALL PIPE Q SEE -0 1 R£NTW OMC. TO SPRINGLM/f O g NO.2-011 MATERIAL: .I73 GAUfZ ALUMNUM WRAP R/PRAP R4 / FACE' NON-REFLECRVE VINYL OR J COATS OUTDOOR ENAMEL(SPRAYED). OF PIPE rv, 1 Z I195.13-• 1/ LETIERAVa SILK SCREEN ENAMEL WNERE POSSIBLE,OR WNYL LETTERS -T, Q TA AR .ALIANIZfI r^ STEPS COLORS BEIGE BACKGROUND, DEAL LETTERS \ O ! J0�7J 28" 2• 4• 2• TYPE FACE: HEL 1f RCA CONDENSED. RTLE.'J^, SUB RTLE /I/2;� TEXT. 1; OUTER BORDER: I/B;BORDER OSTANCE FROM EDGE: 1/47. 8• ` ALL TEXT 16/8-FROM BORDER. `J m ET PIPE SI POSTS... PRESSURE TREATED.BEVELED TOPS. 1-1/2-HIGHER THAN GN. SECTION A-A Z 12 10579 JB- Q d i0 INS7ALLADW. SECURE SI CHAIN LINK FENCE/F AVAILABLE, TOP GRAE INSTALL ON TWE !\ 4-e4-POSTS PRESSURE POST TED.HOLES SMOUN(8-MI A TOP CRAP BED,INSTALLED IN R Q �! 2-6-CONCRETE FROM FILLED POST HOLES(8•MIN OA). TOP OF SIGN NO HIGHER O • MAN J"-6'fROM SERFAGE OF GROUND. O ~ t PLAMAIENr FACE SIGN IN DIRECTION OF PRIMARY VISUAL OR PHYSICAL ACCESS PLACE AT 2 \ LEAST 6*FROM PERIMETER OF SITE.DO NOT BLOCK ANY ACCESS ROAD.DO NOT Q. ELBOW PER PLAN WI NN 6.OF STRUCTURAL FACILITIES,EO MAN HOLES SWO CAGES ETC. y W DErAL, THIS SHEET y Qz PERMANENT SURFACE `UND ANK o K @` y ENBNKMENl PLAN WEW y WATER CONTROL POND SIGN _v y A 6•MIN. NOT TO SCALE y D % y OUTLET OF TEE SECTION SHALL REMOVABLE WATERTIGHT BE SMOOTH WALL METAL PIPE COUPLING OR MELD TO -V y WIN OUT9THAN INSIDE OAMDffR TER STANOPPF POND OVERFLOW INFORMATION y LESS MANCDIA DIAMETER \ Y{ CONNECTING PIPE M.W.S OF POND 402.70 f/�Y y it r \ /.E. SEE RESTRICTIM W� TOP OF RISER 402.70 3 o DETAL) o OVERFLOW WATER SURFACE •40126 €d 6-MIN. 6' EMERGENCY O.W.S 40.166 T/ YC NAX N TOP OF BERM 1p4.00 A� y S KID No7E; OQk7CEEDRILLED IN RP-RAP SHALL BE IN ACCORDANCE y WIN SECTION 9-111 O'THE y I I 11 CA ENO PLATE REASONABLY*ELL GRADEONDA RW 7HH ROCK DADA"ON AS SHALLFOLLOM2 y y 4' FLAT RIPRAP y —_ IOOS PASSING 8-INCH SQUARE SIEVE SPLASH I' B• SPLASH PAQ S OVERFLOW SIEVE STRUCTURE 4OX-60X PASSING 6-INCH SQUARE SIE \• +� DETAIL,SHEET 20. ELBOW DETAIL 0-10%PASSING 2-INCH SNARE SIEVE `1y I� NOT TO SCALE 2.2• 15' 1.2' y =00W F/N/SIf GRADE _ TOP BERM EL.404.00 316-- 70P OF RISER EL 402. T MAX. WATER SURFACE 9.3 �, y POND EL. 9VIN. 7NKXMESS BOTTOM MELD SOLID LID ON "1 RP-RAP PER NOTE NOTE:ROCK-LINE BERM(AT WDTH PLAN WE W VAJAAM■D NEAP.,dL.P.E. TOP OF 12 STANDPIPE SECURE ADJUSTABLE SHORN) C OUTSIDE BERM POND, TO 8 ORIFICE/2 s-J/sv `£C +ol oo H0.Y LOCK TO S EP ME BASE cr M£BERM PER SHEET 16. R/PRAP EMBANKMENT DESIGNED:I[awrwv PE. e EL 4aa4o OBRCE/2A,4-J/+-Y ALUMINUM FT ROD sEQ,RE PROTECT/ON DETA/L TO STEP EMERGENC Y O VERFL O W o"Da D d1rI11eALN ¢ EL 400.15 T NOT O SCALE lr� CHECKED: wow P.E n - STANDARD STEPS OR SPILL WAY DETAIL ¢ 3-x0.090 GAGE SUPPORT LADDER. ) BRACKET ANCHORING 12" NOT TO SCALE DATE: 6/9/99 STANDPIPE TO CA ICH G BASIN WALL CTEANOIT/B-SHEAR CA HEEL: NO x o SCALE: wm.:HORIZ:N A R 2•MM. J6• 3/4'pA.FRAME m I h IB'/E 3 0 V OR L 1 A. 14'x1'r5-S7RP5 I8-OU7ET 1B'INLET PIPE MELD TO J/4'OA.FRAME ON£A WLOOSE RIPRAP 17"OI/IL£T PPE ADAPT TO ADS N-II SPACE UNIFORMLY I•-J-AWN. WSOOi 9-IJ. I 70 M£RAND 6•A;F. 0 FLL TER BL AWEF/8'IE 396.20 N,Gray(rYP) O (CRUSHED SURFACE MATERIAL)ORIFICE/IA.7-J/8"Ir _ 7•MIK I WSDOT 9-0.;9(J) i EOR/F;C Arl.70,, L# \\ TYP/CAL RIPRAP SECTION rrPf n ce pER • o ze,ze ev EL 394.20 MAX NOT TO SCALE �E,r�T9TBRR'�G�� Z S/D.ONE.B079 � � NAI. O 43' A ¢ BOTrW OF STRUCTURE EL.39210 Pn y END 10 BE Checked for Can IUD ce to Cif Standards 1/4-r1 xs-57MP MELDED TO FRAME STAMP NOT VAUD ALL SIM PARTS MUST BE DIMENSION A' UNLESS SIGNED AND DATED GALVANIZED t ASPHALT FOR 18'/ 3--5- VIEW A GRATED(TREATMENT I 95-244 SECT/ON WE W OR BETTER) FOR14'4 s•-e- UpL� 1oD NUMBER FOR 30"" 7'-9- THIS DETWL APPLIES TO OUTLET PIPE ENDS UNLESS OMERWSE NOTED. CB 1, TYPE //-84" sxeer NurDeE FLOW RESTRICTOR W/ OIL WATER SEPARATOR OUTLET TRASH RACK DETAIL 18OF E O SCALE.' 1--2 NOT TO SCALE Z 01999 TRIAD ASSOCIATE, I'CH 7 „� SENSITIVE AREA 9 I'CHAMFER(FP) _ NEW SHELTER TOO ZING,EDGE ( ) ��t1 10'ACCESS ROAD ,I �- I"RAM/ IN! M RI NAM(n Di B°"DING pt INE W"". 1 INIH RfFLECnkE'CRAM«ES THIS UPLAND BUFFER IS (n J "r 1'fXPANSOV EXISIING/N£W CONCRETE SIDEWALK SL P FINISH GRAD TO DRAIN .XYNI NA7ERIAL VAINI IMP. EDGE M177/ 1 i J 1"EXPANSION J.5' I.JJ' 4.JJ' 1.lJ' 15' �1 AWAY FROM BDLLARD TRIAD ASSOCIATES LANDING PADMA AL 18OLLARD , ;, PROTECTED TO PROVIDE£CLWf E71 W NEW CONGAD I6'WIDE CONCRETE BANG WILDLIFE HABITAT AND LANDING PAD '1:E010 Su k CUTTER(TYPE A) NEW'CDGB '° (2)H REBAR,CONK MAINTAIN WATER QUALITY. °°d UrtS6- BIB". TIMBERIIAI/IISIL Art.R [vyl.ed,to it031-e9L1/-/,/_///_ PLEASE DO NOT DISTURBTIW AI 40 IY 4M.W1.A1t1 VARIES VAR/ES VARIES � TAM034-aMCOMPACTED 1-COMPACTED $Ef Of FAI J.p• Tell Tre<SUBGRAD£ AN«A BASE LEFT �\I se s� BASE COURSE THIS VALUABLE RESOURCE. DETAIL SECTION 'REMOVABLE COMPACT SUBGRADEBOIL 2 a= CURB DETAIL FOR METRO BUS PULLOUT BOLLARD LARD BARRIER DETA/L TYPICAL FIXED BOLLARD DETAIL PLEASE CONTACT KING Nor TO SCALE(SEE K.CO.O.T.STD.DWG NO.CI01) NOT'a SCALE AT 425-296-6640 SCALE NOT TO SCALE WITH QUESTIONS OR CONCERNS. y VARIES •SEE RECORDED PLAT FOR RES TRK.'TIONS 3 12 MIN. BOARDS BOLTS-.2 PER JOINT -7 _ Z;1 B'rT•OR 127x1' 112 xJ'LAG SCREWS � a .01MIN ° 'S GALL SENSITIVE AREA TRACT SIGN F' v NOT 70 SCALE Q O Q M1 O O NOTE: PROVIDE� N TO PROTECTION(AT MIDM SHOWN) TO BOTTOM OF POND. N c EMERGENCY SPILLWAY DETAIL Q Q 6 PLASTIC M£IER BOX a M CELL TotSCALE TO CELL 2 � uj POSTS 116"URI. MODEL BRIO Or jI?OOPRODUCTS p I I ,I MWILDODE(BROOKS11419O PRODUCTS REMOVABLE CAP 2 PRESSURE TREATED OR EQUAL) 2 Q 0 OR CEDAR PAINTED WHITE 6'. Q ,1 DRAIN GRA IF NOTES,' STRIPE NOTES: W TOPSHOWN EL AS (TO'NEW) I'-1' 7'-0' I'-1' WIDTH OF RAT[: B'MIN. -12-MAX. RED AND WHITE(PERMANENT) IS'BEND Q Q 2 SHOWN ON PLANS REFLECTOR/ZED T Q O LENGTH OF RAIL: 1'MIN. \ 2 11'CONCRETE• s SLANT OONNWARD,RIGHT OF LEFT.IN DIRECTION 6't 1 COCA TOP TWRE O W ` L/F/ HEIGHT.• 5'MIN. TRAFFIC HILL PASS. e ° u SLANT BOTH DIRECTIONS FROM MIDDLE IF TRAFFIC 6"I 6-0 I2'YIN 18"PLAIN -,II '' TYPE Or FRAME: POST OF SKIDS PASSES BOTH ENDS ( COMCRE PIPE t i ' t FIXXIB/LIFI.. ESSEN 77ALLY PERMANENT W107H 6"EXCEPT J"/F RAILS ARE LESS THAN J'LONG. NQPI T WI'£ RBCAL WYE O •� - A+-� SEE SECTION 5.07 KLRS AND MUTCD SECnON 6C-& FOP ROOF DRAIN FOR«EANOUT TER AND AIa(.—r I t CONNECTION � 1. • HARDWARE TO BE BY ME 7N0 1RAN5/T ,V 'i• U 6"MIN TYPE N BARRICADE (F/XEDI PVC ROOF DRAIN STUB CLEANOUT DETAIL 6-OR B'PVC NOT TO SCALE NOT TO SCALE OU&ET PIP£ C ' • , •. d m • ; r MI • PLAN VIEW I m i� CONCRETE NOTE $ 0 681 222224(CALL MEMO PAGER 99B-8510)CTION INSPECTOR PAUL MILLER THE FOOnNG TTA^OF BERM EL.I01.00 !!Y@ YARD DRAIN DETAIL co� is FORMED H BUT PRIDRNORC"CONCMETRO CA POUR. PLEASE YAJOMVM WATER SURFACE EL 40270 OW 72 HOURS NOTICE. METRO CANNOT INSTALL A \ N7 NOT TO SCALE PRIORSULIFER ON A PAD THAT HAS NOT BEEN INSPECTED • \ Q_ L__ PRIOR 70 CONCRETE M171RK. _ METRO BUS SHELTER-TYPE B11 DETAILNOT TO SCALE ,9T •,g \ ��i TOP OF DEAD STREET VERTICAL CURB %\ SIOPAGE EL.J96.M E- PRONDE MAINTENANCE ACCESS BY WELDING 1 — — c a _ CROSS BARS TO 1 VERTICAL BARS AS SHOWN. HINGE UPPER ENDS TWIN TEANGES/BDLTs ANO FREE DRAINING TOP O-GABIOM WALL EL 391.50 .aADEI�'.QK • MAILBOXES PROVIDE LOCKING MECHANISM(WITH PADLOCK) `� SIRUCIURAL FILL • • • LW LOWER END.LOCATE LADDER STEPS DIRECTLY PER GE07ECAVCAL WALL BAT7ER z • ' BELOW. '// REPORT 1 / B J" ————— — ——— ———— I• A} A \ MACCAFERM ZINC-COATED f0' DEWA K AS M NT ` GALVANIZED GAB/ON BASK£1S P� }r [p REQUIRED NN IN SIDEWALK (OP EOIXVALENT) S tl LENGTH ENCROACHES INTO LOT. \333 (Na OF BOXES r I) J 9"DIA. SM OTN AR / DESIGNED:K 4TXX.'IL PE £DUALLY SPA C£D(1'O.C.MAX.) // CADD: D MDIRAM SLLWE CUT PER WSHA POND BOTTOM EL 38770 CHECKED: WMLIi(Pl. n MAILBOX LOCATIONS REQUIREMENTS FOR _ AR NIN NAN PLACES EVENLY 15'(T�-) TYPE A SOILS �\ M"MM! DATE: 619/TJ9 O✓N EQUAL FOP ROD" SPACED.SEE SEE NOTE! DETAIL BELOW, \/j SCALE: RORR:NSA 6 O AN I-TIN �• PLAN VIEW AHRAn 14M FNIER FABRIC //�/ /�/\\ \ \ / VERT: N/A Y J. InnoonnnWIDE.FORMED TO FIT AN GROOVE(OP fWIVALENT) J• 2 OF L.B.RISER. MAXIMUM OVERHANG m / { '{I•- FIRM UNDISNRBED FOUNDAn«/ 1 BOXES MIN. - IO MAX. IJ' 24' SUBGRADE 70 BE WRN7ED BY 79 SEE NOTE I SOKS ENGINEER. ` W 2'-0 —},SS' J 1'TI/ICK x 1'ELL LONG T SMOOTH BARS M£(OED 70 V oQ R'A8y C 10 O UPPER AND LONER BANOS TM FACE OF CURB 4' (24 BARS EVENLY SPACED, 7 aZ SEE NOTE I) A*1 STEEL BAND 1 WIDE NU u. - RAW EL. 10270 CB I(POND) 1.GABI BASKET WALL MATERIALS AND CONSTRUCTION SHALL a� ELEVATION FROM STREET TYPE N-IB" CONFORM 70 SPEORCApONS GUMMED IN SECTION 6-09.3(6) �o aeae v SECT/ON ��GL NLfL_!2.70 0 ��\\r BRIDGE ANOOF THE 1 B7ACIcµDv°ASFDIRuc�nfavncA naNs Far ROAD. '`Es eDlsTegP'Oc,\`\ 2 GEACRAL NOTES BARS CO.RISER 7.REFER i0 pVIL DRAWINGS SHEET 16 AND i]LY M f0P WAIL ]ONA1, O ALIGNMENT AND CLEW RONS t0 I.MAILBOX UNIFORM BUST BE TYPE"WE WOO O A THE S#DEN nCA GENERAL"I EACH A ExwgES.+/i1/O+ w UNIFORM BOX STYLE AND METHOD d'ADDRESS IO£NTIACAnOM PER EACH ANCHORED 0 2 STANDARD. C.B.RISER \ GAB/ON BASKET WALL 1.LOCAVIEWS AN IS SLAYACCESS. 70 APPROVAL BY Mf COUNTY FOR PROIECilQN OF S IEPS Checked(OT Compliance /0 City Standards NEWS AND ACCESS HOOK CLAMP � NOT 7o SCALE P Y STAMP NOT VA110 UNLESS SIGNED AND DATED J. THE SKETCW77W DEPICTS A KING THE MINIMUM DI AND OIM£NSIDNAI.STANDARD /NNOVA ME DESIGNS MEETING 7E. MIN/MUM gM£NSIOMAL AND STRUCTURAL SECT/ON A-A /DR�E 95 244 REOVAPEMfN>S ARE ACCEPTABLE Af4�S 1.POST MUST GIVE FIRM SUPPORT BUT NOT TO EXCEED 1-1/2-DIAME7ER I.DIMENSIONS ARE FOR INSTALLATION ON 54'OUTSIDE DIA. TYPE N as. ASSOCIATE D AWN PAPE OR♦'XI'WOODEN POST. 2 AI PART& CORROSION Rf51SFANT, STEEL PARTS GALVANIZED,IN ACCORDANCE IMTH STET NUMBER 20. { ASTM A123(AASHTO MIII). EARTH ^� Z DOUBLE MA/LBOXNor TO LSTAND DETAIL OVERFLOW INLETESTRUCTUREHOT 10 SCIENCES INC C1999 TRIAD ASSOCIATES / SECTION XI ml MAINTENANCE & OPERATIONS MANUAL 0 0 0 SECTION XI : MAINTENANCE AND OPERATIONS MANUAL A Maintenance and Operations manual is provided on the pages that follow. TECHNICAL INFORMATION REPORT FOR WINDSONG PAGE: XI-1 KING COUNTY, WASHINGTON, SURFACE WATER DESIGN MANUAL MAINTENANCE REQUIREMENTS FOR I* ' PRIVATELY MAINTAINED DRAINAGE FACILITIES NO. 1 - PONDS Maintenance Conditions When Maintenance Results Expected When Component Defect Is Needed Maintenance Is Performed General Trash&Debris Any trash and debris which exceed 1 cubic Trash and debris cleared from foot per 1,000 square feet(this is about equal site. to the amount of trash it would take to fill up one standard size office garbage can). In general,there should be no visual evidence of dumping. Poisonous Any poisonous vegetation which may No danger of poisonous Vegetation constitute a hazard to County personnel or the vegetation where County public. Examples of poisonous vegetation personnel or the public might include: tansy ragwort,poison oak, stinging normally be. (Coordination with nettles,devils club. Seattle/King County Health Department) Pollution Oil, gasoline, or other contaminants of one No contaminants present other gallon or more or any amount found that than a surface film. (Coordination could: 1)cause damage to plant, animal, or with Seattle/King County Health marine life; 2)constitute a fire hazard;or Department) 3)be flushed downstream during rain storms. Unmowed Gress/ If facility is located in private residential area, When mowing is needed, Ground Cover mowing is needed when grass exceeds 18 grass/ground cover should be inches in height. In other areas,the general mowed to 2 inches in height. policy is to make the pond site match adjacent ground cover and terrain as long as there is no interference with the function of the facility. Rodent Holes Any evidence of rodent holes if facility is Rodents destroyed and dam or acting as a dam or berm, or any evidence of berm repaired. (Coordination with water piping through dam or berm via rodent Seatda/King County Health holes. Department) Insects When insects such as wasps and hornets Insects destroyed or removed interfere with maintenance activities. from site. Tree Growth Tree growth does not allow maintenance Trees do not hinder maintenance ac?ass or interferes with maintenance activity activities. Selectively cultivate fi.a.,slope mowing, sift removal,vectoring, or trees such as alders for firewood. equipment movements). If trees are not Interfering with access,leave trees alone. Side Slopes of Erosion Eroded damage over 2 inches deep where Slopes should be stabilized by Pond cause of damage is still present or where using appropriate erosion control there is potential for continued erosion. measure(s);e.g., rock reinforcement,planting of grass, compaction. Storage Area Sediment Accumulated sediment that exceeds 10%of Sediment cleaned out to designed the designed pond depth. pond shape and depth; pond reseeded if necessary to control erosion. Pond Dikes Settlements Any part of dike which has settled 4 inches Dike should be built back to the lower than the design elevation, design elevation. Emergency Rock Misaing Only one layer of rock exists above native soil Replace rocks to design Overflow/Spillway in are five square feet or larger, or any standards. exposure of native soil. A-1 11/94 KING COUNTY, WASHINGTON, SURFACE WATER DESIGN MANUAL NO. 2 - INFILTRATION Maintenance Conditions When Maintenance Results.Expected When Component Defect Is Needed Maintenance Is Performed General Trash& Debris See "Ponds" Standard No. 1 See "Ponds" Standard No. 1 Poisonous See "Ponds" Standard No. 1 See "Ponds" Standard No. 1 Vegetation Pollution See'Ponds"Standard No. 1 See "Ponds"Standard No. 1 Unmowed Grass/ See "Ponds"Standard No. 1 See"Ponds" Standard No. 1 Ground Cover Rodent Holes See"Ponds" Standard No. 1 See "Ponds" Standard No. 1 Insects See "Ponds"Standard No. 1 See "Ponds" Standard No. 1 Storage Area Sediment A percolation test pit or test of facility Sediment is removed and/or indicates facility is only working at 90%of its facility is cleaned so that designed capabilities. If two inches or more infiltration system works sediment is present, remove. according to design. Sheet Cover (If Sheet cover is visible and has more that three Sheet cover repaired or replaced. Applicable) 1/4-inch holes in it. Sump Filled with Any sediment and debris filling vault to 10% Clean out sump to design depth. Sedmiment and of depth from sump bottom to bottom of Debris (If Applicable) outlet pipe or obstructing flow into the connector pipe. Filter Bags Filled with Sediment and debris fill bag more than 1/2 Replace filter bag or redesign Sedmiment and full. system. Debris Rock Filters Sediment and Debris By visual inspection, little or no water flows Replace gravel in rock filter. through filter during heavy rain storms. Side Slopes of Erosion See "Ponds"Standard No. 1 See"Ponds" Standard No. 1 Pond Emergency Rock Missing See"Ponds" Standard No. 1 Overflow Spillway Settling Ponds and Sediment Remove when 6" or more. Vaults Note: Sediment accumulation of more than .25 inches per year may indicate excessive erosion is occurring upstream of the facility or that conveyance systems are not being properly maintained. The contributing drainage area should be checked for erosion problems or inadequate maintenance of conveyance systems if excessive sedimentation is noted in an infiltration facility. Check twice a year during first 2 years of operation; once a year thereafter. Clean manholes/catch basins, repair damaged inlets/outlets, clean trash racks. Ga A-2 11/94 KING COUNTY, WASHINGTON, SURFACE WATER DESIGN MANUAL NO. 3 - CLOSED DETENTION SYSTEMS (PIPES/TANKS) Maintenance Conditions When Maintenance Results Expected Component Defect Is Needed When Maintenance Is Performed Storage Area Plugged Alr Vents One-half of the cross section of a vent is Vents free of debris and sediment. blocked at any point with debris and sediment. Debris and Accumulated sediment depth exceeds All sediment and debris removed from Sediment 10%of the diameter of the storage area storage area. for 1/2 length of storage vault or any point depth exceeds 15%of diameter. Example: 724nch storage tank would require cleaning when sediment reaches depth of 7 inches for more than 1/2 length of tank. Joints Between Any crack allowing material to be All Joints between tank/pipe sections are Tank/Pipe Section transported into facility. sealed. Tank/Pipe Bent Any part of tank/pipe is bent out of shape Tank/pipe repaired or replaced to design. Out of Shape more than 10%of its design shape. Manhole Cover not in Place Cover is missing or only partially in place. Manhole Is closed. Any open manhole requires maintenance. Locking Mechanism cannot be opened by one Mechanism opens with proper tools. Mechanism Not maintenance person with proper tools. Working Bolts into frame have less than 1/2 inch of thread (may not apply to self-locking lids). Cover Difficult to One maintenance person cannot remove Cover can be removed and reinstalled by Remove lid after applying 80 pounds of lift. Intent one maintenance person. is to keep cover from sealing off access to maintenance. Ladder Rungs King County Safety Office and/or Ladder meets design standards and Unsafe maintenance person judges that ladder is allows maintenance persons safe access, unsafe due to missing rungs, misalignment, rust,or cracks. Catch Basins See 'Catch Basins' Standard No. 5 See'Catch Basins'Standard No. 5 A-3 I/90 KING COUNTY, WASHINGTON, SURFACE WATER DESIGN MANUAL NO. 4 - CONTROL STRUCTURE/FLOW RESTRICTOR SMaintenance Conditions When Maintenance Results Expected Component Defect Is Needed When Maintenance Is Performed General Trash and Debris Distance between debris build-up and All trash and debris removed. (Includes bottom of orifice plate is less than 1-1/2 Sediment) feet. Structural Damage Structure is not securely attached to Structure securely attached to wall and manhole wall and outlet pipe structure outlet pipe. should support at bast 1,000 pounds of up or down pressure. Structure Is not in upright position (allow Structure In correct position. up to 10%from plumb). Connections to outlet pipe are not Connections to outlet pipe are watertight; watertight and show signs of rust. structure repaired or replaced and works as designed. Any holes—other than designed holes— Structure has no holes other than In the structure, designed holes. Cieanout Gate Damaged or Cleanout gate Is not watertight or is Gate is watertight and works as designed. Missing missing. Gate cannot be moved up and down by Gate moves up and down easily and is one maintenance person. watertight. Chain leading to gate is missing or Chain is in place and works as designed. damaged. Gate is rusted over 50%of its surface Gate is repaired or replaced to meet area. design standards. �rifice Plate Damaged or Control device is not working properly Plate is in place and works as designed. Missing due to missing, out of place,or bent orifice plate. Obstructions Any trash,debris, sediment,or vegetation Plate is free of all obstructions and works blocking the plate. as designed. Overflow Pipe Obstructions Any trash or debris blocking (or having Pipe is free of all obstructions and works the potential of blocking)the overflow as designed. pipe. Manhole See 'Closed Detention Systems"Standard See"Closed Detention Systems' Standard No. 3. No.3. Catch Basin See 'Catch Basins" Standard No. 5. See'Catch Basins" Standard No. 5. A-4 1/90 KING COUNTY, WASHINGTON, SURFACE WATER DESIGN MANUAL NO. 5 - CATCH BASINS Maintenance Conditions When Maintenance Results Expected Component Defect Is Needed When Maintenance is Performed General Trash &Debris Trash or debris of more than 1/2 cubic No trash or debris located immediately in (Includes foot which is located Immediately in front front of catch basin opening. Sediment) of the catch basin opening or is blocking capacity of basin by more than 10%. Trash or debris On the basin)that No trash or debris in the catch basin. exceeds 1/3 the depth from the bottom of basin to invert of the lowest pipe into or out of the basin. Trash or debris in any inlet or outlet pipe Inlet and outlet pipes free of trash or blocking more than 1/3 of its height. debris. Dead animals or vegetation that could No dead animals or vegetation present generate odors that would cause within the catch basin. complaints or dangerous gases (e.g., methane). Deposits of garbage exceeding 1 cubic No condition present which would attract foot in volume. or support the breeding of insects or rodents. Structural Damage Corner of frame extends more than 3/4 Frame is even with curb. to Frame and/or inch past curb face into the street (if Top Slab applicable). Top slab has holes larger than 2 square Top slab is free of holes and cracks. inches or cracks wider than 1/4 inch Intent is to make sure all material is 0 running into the basin). Frame not sitting flush on top slab, i.e., Frame is sitting flush on top slab. separation of more than 3/4 inch of the frame from the top slab. Cracks in Basin Cracks wider than 1/2 inch and longer Basin replaced or repaired to design Walls/Bottom than 3 feet, any evidence of soil particles standards. entering catch basin through cracks, or maintenance person judges that structure is unsound. Cracks wider than 1/2 inch and longer No cracks more than 1/4 inch wide at the than 1 foot at the joint of any inlet/outlet joint of inlet/outlet pipe. pipe or any evidence of soil particles entering catch basin through cracks. Settlement/ Basin has settled more than 1 inch or has Basin replaced or repaired to design Misalignment rotated more than 2 inches out of standards. alignment. Fire Hazard Presence of chemicals such as natural No flammable chemicals present. gas, oil, and gasoline. Vegetation Vegetation growing across and blocking No vegetation blocking opening to basin. more than 10%of the basin opening. Vegetation growing in inlet/outlet pipe No vegetation or root growth present. joints that is more than six inches tall and less than six inches apart. Pollution Nonflammable chemicals of more than No pollution present other than surface 1/2 cubic foot per three feet of basin film. length. A-5 1/90 KING COUNTY, WASHINGTON, SURFACE WATER DESIGN MANUAL NO. 5 - CATCH BASINS (Continued) Maintenance Conditions When Maintenance Results Expected Component Defect is Needed When Maintenance Is Performed Catch Basin Cover Cover Not In Place Cover is missing or only partially in place. Catch basin cover is closed. Any open catch basin requires maintenance. Locking Mechanism cannot be opened by one Mechanism opens with proper tools. Mechanism Not maintenance person with proper tools. Working Bolts Into frame have less than 1/2 inch of thread. Cover Difficult to One maintenance person cannot remove Cover can be removed by one Remove lid after applying 80 lbs.of lift; intent is maintenance person. keep cover from sealing off access to maintenance. Ladder Ladder Rungs Ladder is unsafe due to missing rungs, Ladder meets design standards and Unsafe misalignment,rust,cracks,or sharp allows maintenance person safe access. edges. Metal Grates Grate with opening wider than 7/8 inch. Grate openings meet design standards. (if applicable) Trash and Debris Trash and debris that is blocking more Grate free.of trash and debris. than 20%of grate surface. Damaged or Grate missing or broken member(s) of Grate is in place and meets design Missing the grate. standards. A-6 1/90 KING COUNTY, WASHINGTON, SURFACE WATER DESIGN MANUAL NO. 6 - DEBRIS BARRIERS (e.g. Trash Racks) Maintenance Conditions When Maintenance Results Expected Component Defect Is Needed When Maintenance is Performed General Trash and Debris Trash or debris that Is plugging more Barrier clear to.reoeive capacity flow. than 20%of the openings in the barrier. Metal Damaged/ Missing Bars are bent out of shape more than 3 Bars in place with no bends more than Bars inches. 3/4 inch. Bars are missing or entire barrier is Bars in place according to design. missing. Bars are loose and rust is causing 50% Repair or replace barrier to design deterioration to any part of barrier. standards. s A-7 1/90 KING COUNTY, WASHINGTON, SURFACE WATER DESIGN MANUAL NO. 7 - ENERGY DISSIPATORS Maintenance Conditions When Maintenance Results Expected Component Defect Is Needed When Maintenance is Performed External: Rods Pad Missing or Moved Only one layer of rock exists above native Replace rocks to design standard. Rock soil in area five square feet or larger,or any exposure of native soil. Dispersion Trench Pipe Plugged with Accumulated sediment that exceeds 20% Pipe cleaned/flushed so that it matches Sediment of the design depth. design. Not Discharging Visual evidence of water discharging at Trench must be redesigned or rebuilt to Water Properly concentrated points along trench (normal standard. condition is a'sheet flow'of water along trench). Intent is to prevent erosion damage. Perforations Over 1/2 of perforations In pipe are Clean or replace perforated pipe. Plugged plugged with debris and sediment. Water Rows Out Maintenance person observes water Facility must be rebuilt or redesigned to Top of'Distributor" flowing out during any storm less than standards. Catch Basin the design storm or it is causing or appears likely to cause damage. Receiving Area Water in receiving area is causing or has No danger of landslides. Over-Saturated potential of causing landslide problems. Internal: Manhole/Chamber Worn or Damaged Structure dissipating flow deteriorates to Replace structure to design standards. Posts, Baffles, 1/2 or original size or any concentrated Sides of Chamber worn spot exceeding one square foot which would make structure unsound. Other Defects See "Catch Basins"Standard No.5 See "Catch Basins" Standard No. 5 A-8 1/90 KING COUNTY, WASHINGTON, SURFACE WATER DESIGN MANUAL NO. 8 - FENCING Maintenance Conditions When Maintenance Results Expected Component Defect Is Needed When Maintenance Is Performed General Missing or Broken Any defect in the fence that permits easy Parts In place to provide adequate Parts entry to a facility. security. Parts broken or missing. Broken or missing parts replaced. Erosion Erosion more than 4 inches high and 12- No opening under the fence that exceeds 18 inches wide permitting an opening 4 Inches in height. under a fence. Wire Fences Damaged Parts Posts out of plumb more than 6 Inches. Posts plumb to within 1-1/2 Inches. Top rails bent more than 6 inches. Top rail free of bends greater than 1 inch. Any part of fence (including posts,top Fence Is aligned and meets design rails,and fabric)more than 1 foot out of standards. design alignment. Missing or loose tension wire. Tension wire in place and holding fabric. Missing or loose barbed wire that is Barbed wire in place with less than 3/4- ragging more than 2-1/2 inches between inch sag between posts. posts. Extension arm missing, broken,or bent Extension arm in place with no bends out of shape more than 1-1/2 inches. larger than 3/4 inch. Deteriorated Paint Part or parts that have a rusting or scaling Structurally adequate posts or parts with or Protective condition that has affected structural a uniform protective coating. Coating adequacy. Openings in Fabric Openings in fabric are such that an 8- No openings in fabric. inch-diameter ball could fit through. A-9 1/90 KING COUNTY, WASHINGTON, SURFACE WATER DESIGN MANUAL NO. 9 - GATES Maintenance Conditions When Maintenance Results Expected Component Defect Is Needed When Maintenance Is Performed General Damaged or Missing gate or k>cking devices. Gates and locking devices in place. Missing Members Broken or missing hinges such that gate Hinges Intact and lubed. Gate is working cannot be easily opened and dosed by a freely. maintenance person. Gate is out of plumb more than 6 Inches Gate is aligned and vertical. and more than 1 foot out of design alignment. Missing stretcher bar,stretcher bands, Stretcher bar, bands,and ties in place. and ties. Openings in Fabric See'Fencing'Standard No.8 See'Fencing'Standard No.8 A-10 1/90 KING COUNTY, WASHINGTON, SURFACE WATER DESIGN MANUAL NO. 10 - CONVEYANCE SYSTEMS (Pipes & Ditches) Maintenance Conditions When Maintenance Results Expected Component Defect is Needed When Maintenance Is Performed Pipes Sediment&Debris Accumulated sediment that exceeds 20% Pipe cleaned of all sediment and debris. of the diameter of the pipe. Vegetation Vegetation that reduces free movement of All vegetation removed so water flows water through pipes. freely through pipes. Damaged Protective coating is damaged; rust is Pipe repaired or replaced. causing more than 50%deterioration to any part of pipe. Any dent that decreases the cross section Pipe repaired or replaced. area of pipe by more than 20%. Open Ditches Trash &Debris Trash and debris exceeds 1 cubic foot Trash and debris cleared from ditches. per 1,000 square feet of ditch and slopes. Sediment Accumulated sediment that exceeds 20% Ditch cleaned/flushed of all sediment and of the design depth. debris so that it matches design. Vegetation Vegetation that reduces free movement of Water flows freely through ditches. water through ditches. Erosion Damage to See "Ponds"Standard No. 1 See "Ponds" Standard No. 1 Slopes Rock Lining Out of Maintenance person can see native soil Replace rocks to design standard. Place or Missing (If beneath the rock lining. 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 No.6 (e.g., Trash Rack) A-11 1/90 KING COUNTY, WASHINGTON, SURFACE WATER DESIGN MANUAL NO. 11 - GROUNDS (Landscaping) Maintenance Conditiona When Maintenance Results Expected component Defect is Needed When Maintenance Is Performed General Weeds Weeds growing in more than 20%of the Weeds present in less than 5%of the (Nonpoisonous) landscaped area (trees and shrubs only). landscaped area. Safety Hazard Any presence of poison ivy or other No poisonous vegetation present in a poisonous vegetation. landscaped area. Trash or Latter Paper,can,bottles,totalling more than 1 Area clear of litter. cubic foot within a landscaped area(trees and shrubs only)of 1,000 square feet. Trees and Shrubs Damage Umbs or parts of trees or shrubs that are Trees and shrubs with less than 5%of the split or broken which affect more than total foliage with split or broken limbs. 25%of the total foliage of the tree or shrub. Trees or shrubs that have been blown Tree or shrub In place free of injury. down or knocked over. Trees or shrubs which are not adequately Tree or shrub in place and adequately supported or are leaning over,causing supported; remove any dead or diseased exposure of the roots. trees. A-12 I/90 KING COUNTY, WASHINGTON, SURFACE WATER DESIGN MANUAL NO. 12 - ACCESS ROADS/EASEMENTS Maintenance Conditions When Maintenance Results Expected Component Defect is Needed When Maintenance Is Performed General Trash and Debris Trash and debris exceeds 1 cubic foot Trash and debris cleared from site. per 1,000 square feet,i.e.,trash and debris would fill up one standard size garbage can. Blocked Roadway Debris which could damage vehicle tires Roadway free of debris which could (glass or metal), damage tires. Any obstructions which reduce clearance Roadway overhead clear to 14 feet high. above road surface to less than 14 feet. Any obstructions restricting the access to Obstruction removed to allow at least a a 10-to 12-foot width for a distance of 12-foot access. more than 12 feet or any point restricting access to less than a 10-foot width. Road Surface Settlement, When any surface defect exceeds 6 Road surface uniformly smooth with no Potholes, Mush inches in depth and 6 square feet in area. evidence of settlement, potholes,mush Spots, Ruts In general, any surface defect which spots,or ruts. hinders or prevents maintenance access. Vegetation in Road Weeds growing in the road surface that Road surface free of weeds taller than 2 Surface are more than 6 inches tall and less than inches. 6 inches apart within a 400-square-foot area. Shoulders and Erosion Damage Erosion within 1 foot of the roadway more Shoulder free of erosion and matching Ditches than 8 inches wide and 6 inches deep. the surrounding road. Weeds and Brush Weeds and brush exceed 18 inches in Weeds and brush cut to 2 inches in height or hinder maintenance access. height or cleared in such a way as to allow maintenance access. A-13 1/90 • APPENDIX • • IP I Ik __x X 477 I - "I77 I X 464 6 x I X71 I /I 4 ^I I 76 X 477 X I I x v X 4'4 I I BR. 1 >< / • x x x x 1"=2009 xx x 'A x-----� 472 I ` _♦ l__ ❑ I - ❑ -- � WI X 472 —— `— S.E.) 21 sJlJl_STj�_— i -- X -,r--i -- - 1468 (448 � 463 I f i 1 1' 't- ---Q� -'.^�' I ❑ aI I --- J I ❑ ❑❑ I 469 Note: SE 128th St. is also referred to as NE 4`h St. and 142"d Ave SE is _s ❑ _, i — also referred to as Hoquiam Ave NE. 01 \ �I _a ❑ _ X 446 �� 8 R U S H i C 62] ❑ II � 467 464 I I ❑ O\ 7 x---x X X X 466 __J L ue_3 r X ❑ k-� � x Irr \ 63 W \ CE] \ , AREA TRIM O 142"d SYSTEM = 14.65 Ac j I -- ❑ I Fu TREES• BR AREA TRIB. TO --�SITE = 3.75 Ac ❑ __I i AREA TRIB. TO SE 128TH SYSTEM=8.25Ac .. 396 El o ❑_ . 4JL 44 X x T S X 4 ;.. ' X 3 96 i TREES x( • I I 451 [�] V O ) 441 x A SITE 0 441 x I 1 446 ❑ v�0 II I `_(111 ❑ ❑ � I ' it 3 9? x x 1 42. 55KV II ` SE 128h STREET /1 LIGH 11 7 \ 55 KV11