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HomeMy WebLinkAboutSWP272856(2) BRIERE CREEK Renton, Washington Technical information Report Prepared For: Briere Enterprises i Prepared By: •off, �,` tv�.z Pacific Engineering Design, Inc. �S+'t]yp LLB 9 ZL�z EXfil�J i:!./ May 19, 2000 PEDI Job No. 99043 TECHNICAL INFORMATION REPORT BRIERE CREEK RENTON, WASHINGTON May 19, 2000 PREPARED FOR BRIERE ENTERPRISES 1944 Duvall Avenue NE Renton, WA 98059 (425) 228-7170 PREPARED BY PACIFIC ENGINEERING DESIGN, INC. 4800 S. 188T" STREET, SUITE 360 SEATTLE, WASHINGTON 98188 (206) 431-7970 TABLE OF CONTENTS Page I. PROJECT OVERVIEW 1 - 8- 8 Ii. PRELIMINARY CONDITIONS SUMMARY......................................................9 - 11 m. OFFSITE ANALYSIS .....................................................................................12 - 24 IV. RETENTION/DETENTION ANALYSIS AND DESIGN...................................25 - 39 V. CONVEYANCE SYSTEM ANALYSIS AND DESIGN............................................40 VI. SPECIAL REPORTS AND STUDIES....................................................................41 VII. BASIN AND COMMUNITY PLANNING AREAS...................................................42 VIII. OTHER PERMITS.................................................................................................43 IX. EROSION/SEDIMENTATION CONTROL DESIGN..............................................44 X. BOND QUANTITIES WORKSHEET, RETENTION/DETENTION FACILITY SUMMARY SHEET AND SKETCH, AND DECLARATION OF COVENANT...................................................................45 - 55 XI. MAINTENANCE AND OPERATIONS MANUAL...........................................56 - 69 PAProject Files\99043\9943 drainage report.doc I. PROJECT OVERVIEW PAProject Files\99043\9943 drainage report.doc I Project Narrative — Briere Creek Preliminary Plat The Briere Creek Preliminary Plat is located on a parcel of land encompassing 3.68t acres of land approximately 300 feet north of the intersection of NE 18th St. and Duvall Ave NE on the east side of Duvall, directely across from the entrance to the May Creek Highlands development. The Brieres live in the existing residence located on proposed lot 1, and run their construction business from the existing residence located on proposed lot 18. Also located on the site is a large workshop, detached garage and storage shed. Numerous items from the Briers construction business are stored about the site. The site is zoned Residential - 8 Dwelling units per acre (R-8). The surrounding properties consist of single family to the north, the Plat of Summerwind to the east, a vacant lot to the south and single family homes on large lots to the west (May Creek Highlands). The vacant lot to the south is being developed by William's brother; Gerald Briere. The project is known as Briere Plat (City of Renton Permit No. C990249). As of May 2000, construction of roads and utilities is underway. It is anticipated that this construction will be completed by the end of June. The site is mostly open in the front 1/3 and back 1/3 with a band of many small to medium size trees located in the middle 1/3. The site slopes off into a green belt tract on the east that also serves to convey storm runoff from a Summerwind division to the northeast to a regional detention pond to the southeast. The east property line is covered with thick brush and scattered small to medium size trees. The parcel slopes gently to the north and east and the present drainage pattern consists of sheet flow. Soils on site have been classified by the Soil Conservation Service as Alderwood Series (AgC) slopes of 0- 5% and Hydrologic Group C. A majority of the existing trees on site will be removed in preparation for construction of the plat infrastructure. The proposal is to subdivide the parcel through the platting process into 18 single-family residential lots with a public street and utilities serving each of the new lots. Building height will be limited to two stories - 30' dwellings and 15' for detached accessory structure. Offsite improvements will consist of dedicating 12' of property along Duvall Ave NE for roadway widening and installation of new curbs, gutters and sidewalks. Utility lines consisting of franchised utilities (power, gas, telephone and cable T.V.), along with sanitary sewer, water mains and storm drainage will also be extended as necessary to serve this development. Installation of the road and utility infrastructure will involve minimal excavation and embankments. At this time it is estimated the quantity of earthwork required to achieve grades proposed on the plans will require approximately 3000 c.y. of import. Additional yard fills may be needed when homes are constructed on each lot. 2 The portion of the site containing the public road and utilities will be dedicated to the City of Renton through the platting process, as public property. Utility lines across lots/private property will be within easements. �J Pagel of 2 King County Building and Land Development Division TECHNICAL INFORMATION REPORT (TIR) WORKSHEET Project Owner �1E �IZE-el�e�ECS Project NameIE C �- Address NVE• OEa reed 98G Location Z3 1 Phone - 2'Zf5 'TtlU i Township �,, � Range �'� Project Engineer 3 Company ?V-- iyic C-JgiJeSV- Jq Section Cj4 � Project Size it�0/ ��F AC 3:Cott Address Phone ��S, lb?, ST. �� Upstream Drainage Basin Size AC Subdivision DOF/G HPA 0 Shoreline Management (] Short Subdivision (] COE 404 Rockery Grading DOE Dam Safety Structural Vaults Q Commercial 0 FEMA Floodplain (� Other Q Other COE Wetlands HPA Community V E)JT00 J(,41g4i L\'.dos) Drainage Basin =- .. 0 River _ E-J Floodplain F-1 Stream 0 Wetlands ---- — 0 Critical Stream Reach 0 Seeps/Springs Depressions/Swales High Groundwater Table (� Lake Groundwater Recharge Steep Slopes _____ ____ i=] Other i n Lakeside/Erosion Hazard So!! Typ-2 Slor,:?s Erosion Potential E(CS-ve Velocities ___ ; Additional Sheets Attatched Page 2 of 2 King County Building and Land Development Division TECHNICAL INFORMATION REPORT (TIR) WORKSHEET PART 8 DEVELOPMENTUM ITATIONS REFERENCE LIMITATIOWSITE CONSTRAINT' (� Ch.4-Downstream Analysis F-] a a a 0 Additional Sheets Attatched -ESC REQUIREMENTS' MINIMUM ESC REQUIREMENTS MINIMUM ESC REQUIREMENTS DURING CONSTRUCTION FOLLOWING CONSTRUCTION Sedimentation Facilities Stabilize Exposed Surface Stabilized Construction Entrance Remove and Restore Temporary ESC Facilities Perimeter Runoff Control Clean and Remove All Silt and Debris E:J Clearing and Grading Restrictions Ensure Operation of Permanent Facilities (� Cover Practices Flag Limits of NGPES Construction Sequence Other _ ID Other Grass Lined Channel 1:J Tank Infiltration _ Method of Analysis Pipe System X Vault 0 Depression CJ Open Channel 0 Energy Dissapator CJ Flow Dispersal Compensation/Mitigation Dry Pond. 0 WoUand 0 Waiver of Eliminated Site Storage Wet Pond _ Stream Regional Detention I Brief Description of System Operation N-Aeo -5y-m o V-60zeD TO \1PCL' T 0 Q n -ram lo'-nLZC� 5L-Nry -E. Tkyp�TtCX1SCtc�St�b�-SizE� Facility Lim Related Site Limitations 0 Additional Sheets Attatched Reference Facility itation II LIM Drainage Easement 14 Cast in Place Vault E:�] Other IxAccess Easement 0 Retaining Wall Native Grov,lh Protection Easemen; Rockery>4'High 0 Tract Structural on Steep Slope Other • 7-1 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 bost of my knowledge the information provided JC t here is accurate. A PORTION OF SECTION 3, TOWNSHIP 23 NORTK RANGE 5 EAST., W.M. L. , \I OF A 4 j�d BCALE a CITY r-3 - � tt ar NfMTI)MW AEr wslm sawn AT N4l Da*"ar ccwoirl[PMO so o 1.6 worn ro.A71 Ifne a K me Or NL"m sr. IEE 42146 12'CGNC.S � �, ry� CB � ttAV�4A IE:423.77 8'CONC.E RIN ELEV-425.98 CITY Or A&MN IN MW PC"r V,num C8 N0.tI(TYPf F487 jgt-g TroAel C�`' RIM ELEY-426.43 ��E!423.86 8"CONC.W MN OLIMOA[I[AtN TAIX N AIL.L cur AT NIX gi.413D try Or tSM'ACIAN AT%X r ON south PRO►LA B Or SLAMET KIOU AW L1u1MIL A1C A.S. MY.(t27-4n.38 [t[Y.w4.>t a.�i wv a»01 a"-40L3S t 1 ROCKED OUTrALL f( NY.(12'}418.76 wt�aRSYaE�C�T ai tE-417.t' W SNGLE FAMILY AW-42s.s u•CONC. Q C8 1 I EXIST.PP 70 O.F,.420m tE ♦16.2' RIN ELEV.425.78 I 3 ,�BE RELOCATED sm(w)-417,50 12'CONc. E-42267 12"CONC.NW I •iv I h r ._._•-_ _---_- - IE.422.63 12"CONC.S `F3 ` - '---�-- -_ �_p-_-..----C--P- -p _ _.p. P -p _ _W-- W- -_ -__==1�_' '�tEp-__ "�C- ---'--w--�-=fie'- Fw1W 2"BRASS DISC SET IN TOP CDNC NON 1 _ _ fPH1 04'OOAN AT INI%OF NE \ 10111 Pl.8:pUVALL AVE NE ` / 1 C.O.R. 1641• .� -EJOB WA iEN METER �, r--------------�- - I (2-2-426.41 EXISVAULT TES. L>, _ I STA8f03.00, t d PIT \• -- - '" (2-24-98} VAULT I \ 12'CONC. POST I. 'r• AW 424�L �,�'._ ce RISER I b'ST.HOUSEt c' _ RIY ELEV.125.35 1 I ,� •_ I NY.6'}11176 IE-422.43 12"CONC.N I t0 REMAIN I EYV,(12'�.{16. _ ram \` IE•422.43 12'CONC.S ! q T / 'b'4m- '1\ �+�+{�� LOT IVLar 14 Lc(1' LOT (, LOT Z. -- - i' \, \1 S-0.0067 SIX OCTAL S�F t "i 1� fa 6R-iR6 R� MD`4W PAD-4 ,pl PAD-4MS • '�,' IS h SNEET C-12 j :4 .st Lowe aefdna- j Lbw 7 _ T.SIN NOW \ f RCD �s�Twr(�'} 1 LL PoM ELEV.421 70 - `l L 'r EXIST.MAIL BO C.422.37 12'CDNC.NW 73V Y IE 1+26.44(N.E.19TH 5T.) .422.35 12'C.C,s OHAVF,I.AREA C - ( \tr.• \ ..� STA 14a10.42(DUVALL AVE,N ■ SfA. 1 F cloOUND R. NON IN CASE Ci 199d'CNTRL NETWORI( ` t. .1 i •••• ° ,.�.-1 _ L .1�'\ i \ y` (2-24-98)---- _...L;..._..._� I y Y-1 Z Z 1 ' w I LOlq am*mrT 7 lowovELENT7IN.W� ..'. I•'0 FOR W J WM1LL AW.M[ �,. J.M i F1C IIINLL Wi IS O LI� \ ` I i .". NIY�PE 16.0' T 1t LAT4 I Ii 110Ta• �' .� I $ o co. n O RIN ELEV-424,95 -,a II2Q MOiM6 LE BOTTOM EV Sl E =420.49 --SD { STAY+80.0q MC Lr Cll E-421. 1YCONC N r I - n1'+p4 U NV.�IP}.41t.7S \` .421 66 86 12'CONC E RI ELEV-424.116N f' °�'.. _ F"-- T-`_ _---�---- 1 `�I_ .JI \`t 1 IE.421.45 12'CSP N,W i 111 W \• IE•42t.26 12'CSP S (T) �•� IE 422.49 6"PVC E .. i I •� r- LW2 I LGQiI •,LATELOT 9 ! /rrLOT 1 ! A'POMt�� l• a p�p.,Y6p 1� PAD-AM I'•. 8 }``���\ (T77 I sSSS i \ Q II •r3I I !f(t.. I \_I CONNECT p [ Y\TO S!+TA[[H 7b At co N01(04t'�C4I1Rtj Emw FEES,107H 1EET AVOID iStiOP AREA RFREBOAMfl&tW.65tE Ex15T.H PLAT E. Na'C OX TGRENAtNSE J { 7 /2` L ?tl' 1 Ra4 N\ i F 'O -.XI>'f. WATER uE lEa-` t I I I y III I.-'E i w aruht'r ntLo4 M a7c11sYY r 2PO.7E' CM E I l t -EXIST PP TO 3 = 'C''� I 8E RELOCATED I 7 FENCE CORNER __ L� 1 s0.32 Sr h FOUND t/2 HEBAR ) I (' 1 i I ` I ✓ O E W/TA (•_ _IIER ff0 I 2 I ' E�PEAR Sya \6 I i! : I ' PRUP CDR.F..: I' -I (2--25 98r y ; I !' - F I I PLAT ` \ I •TRIAO' i a--1 L L11 c_ '�"' p SWQLE FAMILY 1 _J BPoERE PLAT L m ce II L� V RIM ELEV-42314r--- L.W nt o. Q) -41604 WC IESP / OIIAJ m •Y V L OWWACYM R7 MAIFOIN Ir 1M6Y CfMANCl FROM OAF MAN 70 ALL WW E1LC6WCAL,PTILK t CABLE SCRWM a LINES ALL NOW PDWOMMfD AND MAt[/iK3 NAS PROECT LlS MIN AOu►pt P"7EC7NN 201C f O ALL Omm www u1UK1 70 K PUT ILL K UOEHCIgM. OONSmxom U=9WL K N AOCORDAACE ISM COWMACIOR SHALL INSTALL A LIMM fDf K 610`AL Is 16WC OAT[ OF WM FRANCPW UnUM3 WLW K NSYCim t CITY Or fiew M'SLUADAAD PLAN: SHALL PER KNO COUNTY OUOfINE& (A"AWL K ET L ALL ON-JIM S70001 PIE SMALL K AWF Al(Of EWkUj L4ASii APPWO WD 6Y A Ott DF ADIM PUNW oDWS DAnm 01/21h7, aT01 3Q-40 NL Mf1lWANCE OR CLAY ILL ma / ORO U K NORD ON K PEAML NYCC/LM PWLW TO AEOM04 Or K K IN PUT, •0-•FLIER SIlWZ MAL.D[ET C12 TOIL SPECS 6H[ET PILN610N 0 SALL VMW AtM aAML K PIIDECIW PAW CO4iIt XKN PER K LOGIKM Pm*m utLITICS"LL K DES1049 N __ T1DgARY OIOEKN OOMRIOI PLAN VIOL 41[YCCRK µWWWRIL N GDMXAL.AEDA40 GECI(ED MR110MID D 0y*GPID DWG u1rFo4o4LAc CO4Nf AAO PI[KRJCLTO CM STANDAM ca. 4IDS NO LWERO aA D LIA ISES N OVMW.AK INK KEN SWW IRAIWWIERL AMCDO/AL7Q'f,L1G NEL K / FROY K AN)S1 CI.46OIT MpY41401 KE.AWM.A IT PWL K K G RD N M LOG LANDSCAPE EAL L140E1(SKINNK OR N O6(A O Y OOYA IMU REWO/�UTY 10 LG OS OIE ALL OA4 UR/KL M Lt W AU W IU404T OaVUDO4CH NOT CUCT WIN BY: U) •{ •4A111 OR NOT,PNIOR 10 ocom"cow711LCRON UPNOVM WIIER SANITARY WWX 0R STORM DNAN D E DO(N BYt 9 PACIFIC ENGINEERING DESIGN INC. o CML ENGINEERING AND PLANNING CONSULTANT8 E CT Ir PIERI ,�D / o ;-•111SZi i �o� PI RCE AV NE PL OUEEI NE rmn RECMpryp AV NE128TH AV SEREDMOND Nse IAV NE N r'3SHELTON AV m oN7ACORA -{ NE oti^� o oz 1_ OT AV SE AV NE Z o 39 L3 1 L�-�.7 CDI Tj m -�� ASHON = Z m S VASHON y 9f CT NE rn ASHON CT ^ C1 E A VASypy UNION CT I TMAh ry WHITHAN CT NE Y = C) m AV NE CT NE W[ N ANACORTES �y NI \� S 'aCTME ? NZZ3N A nY�p N 3N AY z r rn r_HE AV NE CORTE AV HE FS AV NE m = BREMERTON A NE _AV NE N �i-- z ry m o m m o~ m Z nt N Z - { AV Cc u � r+' �= m �o �m4f - o (DUVALL AV) - x "V Sm7 138TK �4 ;2 AVCD o "4 IELO AV p FIELD AVM, x roll x L AV N ^AV SE � HDOUTAN EllI AFi AV NE 14[ND PL NE AV NE aY m w / C7 11s D z We HOIU AN 143RV of CT NE ti AV SE co -AV NE � o 144TH ,y`c (? o� AV SE 145TH AV m ^� " �sE r� 145TH PLo m� LYONS y `� AV 46TH AV-5�r � _ _ -A •-Il- _ G-� 147TH AV o �N �i 147TH�� AY SE y r' SE to -i 148TH F �. A .- ------ 148TH ti E -- —��"' '- om SE -- 42 I BeC --�— AgC r iVewpo AgD i BeC ' Ur Hills BeC AgC --� I -C) Ur 32'30" BeD I Akp a AgC BeC Ur BM BeC ///���--------- Q New �i93 • BeD r--i l •`\ I E. • I IC BeD •eC I \\• �� B h �j, r •� AgC I AgC j 9°00 AgB OvD I con BM ---- -- ------ — ------- — ——————— —-————————————-A-- BMA ABM --- 690 692 I 7B BeC h ••AgC No l \ AgC 1 BM I 1 n _ AgC 1 605 OvD I � \ o Soil.. ' Sr" vv AgC U 1 { \• l p BeC A ev- 4/ ; 1 AgD erl \: AgD 34 1 )3 BeD AgC • EvB AkF I OvD AgC I BeG EvC I GRA VEL A♦•C I PIT J 306 j —'' N—'--=--- AgC I — .hm T. 24 N. �- T 23 N. OvC " a EvO AgD Bh v` u AgC r --- BM _ RdC \ n AkF BeD AMC ABC •I_ 0 M •� S1 1 AgD e �EvC' i •� ��• •� ' EvB •, = I AgC• - { •'(ll JSm Tu AmC C• • . •� 'r• I• R®ry ir. d •` •I�' L G•I,•• Trailer arks m = BM --�-�- BM iJL. BM RdC I o • fj T, I j�,T' EvC T % L•SL.• 7�4�� ...• - 4 „ — n r ' J� 11L�LiV s.AgC 1� �g m •i mh:t, I a_ JfA �O AgC i RdC 10, 47030' 122°07'30" N ��r- ZbQQ1 Orthophotobase compiled in 1970 by USGS. Planimetric 2 Miles detail obtained from USGS 71/z minute series maps. 10000 Feet Polyconic projection. 1927 North American datum. 10,000•foot grid based on Washington coordinate system, north zone. SHEET NO. 5 a II. PRELIMINARY CONDITIONS SUMMARY PAProject Files\99043\9943 drainage report.doc 9 Core Requirements: 1. Discharge at the Natural Locations: The project slopes naturally to the north and east. Drainage then enters an existing swale traveling south along the east property line. The proposed discharge point of the bioswale is on the east property line into the existing swale. Therefore this core requirement will be satisfied. 2. Off-Site Analysis: A Level 2 Analysis of the offsite drainage basin was done for Briere Plat immediately to the south. Both Briere Creek and Briere Plat share the same offsite drainage basin. That report has been included herein under Section III. The analysis showed no downstream drainage capacity or erosion problems. 3. Runoff Control: The proposal will utilize an underground concrete detention vault with metering orifices to limit the developed conditions peak rates of runoff to the predevelopment peak rates for the 2-year and 10-year storms and routing the 100-year storm. Bio-filtration will be provided in a bio-filter swale downstream of detention. The bio-filter swale has been sized to treat the 2-year/24-hour storm. 4. Conveyance System: The conveyance system is analyzed for the 25-year storm event based on the Rational Method. The offsite drainage system has been reviewed under the Level 2 analysis and found to be adequate for this development. 5. Temporary Erosion and Sedimentation Control: The construction plans for the site improvements contain a grading, clearing and erosion/sedimentation control plan. These plans shall include BMP's which will minimize erosion and sedimentation onto adjacent properties. Special Requirements: Special requirements 1-10 do not apply to this proposal. Requirement 11 (Geotechnical analysis and Report) and Requirements 12 (Soils Analysis and Report) have been waived by city staff. Id 1� all New �1. filly �� • �� at ■ man I. s III. OFF-SITE ANALYSIS PAProject Files\99043\9943 drainage report.doc 12 LEVEL II OFF-SITE ANALYSIS As part of doing the site topography for Briere Plat, Triad Associates took shots along the centerline of the downstream open channel drainage course to establish its horizontal and vertical location, and, as well as, the piping system immediately downstream of it. The downstream drainage course crosses the property to the north at a southeasterly direction about 140 feet north of the northeast corner of the site. From this point it meaders southeast through Tract "A" approximately 303 LF before entering a 12-inch concrete pipe. The 12-inch pipe flows southerly 12 feet to a large drainage structure covered with a spillway trash screen 10 feet long by 3 feet wide. An 18-inch pipe discharges from the structure southerly to a Type II Catch Basin in Field Avenue NE. From the slope of the 18-inch pipe, it has an open channel full flow of 7.94 cfs. With the proposed on-site storm detention vault, the peak rate of discharge for the 100-year event is Qloo = 0.89 cfs. The existing drainage basin (excluding the project site) flowing undetained to the discharge point comprises 7.53 acres. In addition, detained flow from the plats of Summerwind Div. I & II discharges to the same point. Adding the undetained flow to the detained flows for this site and Summerwind Div. I & II yields a peak rate of discharge for the 100-yr. event of Q1oo = 4.61 cfs. Under a system failure where the detention systems are overflowing the peak rate of discharge for the 100-yr. event would be approximately Q 100 = 12.31 cfs. I. Existing Conditions (Briere Plat) Total On-Site Area= 2.278 Acres Area of Road Right-of-Way = 0.494 Acres Tc 370 LF @ S = 1.216% CN - 85 (Meadow or Pasture) Bypass= 33 x 50 = 0.038 acres Il. Developed Conditions (Briere Plat) Total On-Site Area= 2.278 Bypass = 0.038 Acres - Impervious P2 = 2.10 P 10 = 2.95 2.278 = 0.038 = 2.240 Acres P 100= 3.95 Grass = 1.162 CN = 86 Roadways = 0.456 CN = 98 Homes = 0.622 CN = 98 2.240 PAProject Files\99043\9943 drainage report.doc �� Existing Rates: = (Ex. —Bypass) = (Ex. Bypass) =Total Existing Discharge 2 yr. (existing) = 0.263 + 0.008 = 0.271 cfs 10 yr. (existing) = 0.531 + 0.015 = 0.546 cfs 100 yr. (existing) = 0.888 + 0.025 = 0.913 cfs Release Rates: =Total Existing Discharge—Developed By Pass = Allowable Release Rate from Detention Vault 2 yr. (Dev) = 0.271 - 0.020 = 0.251 cfs 10 yr. (Dev) = 0.546 - 0.029 = 0.517 cfs 100 yr. (Dev) = 0.913 - 0.039 = 0.874 cfs Note: To Reviewer At the time these storm detention calculations were done for Briere Plat, there was a small by- pass area which had to be accounted for in sizing the detention vault. The by-pass has since been eliminated making the calculations more conservative, with the detention vault slightly larger than it would otherwise need to be. We will leave the calculations as they are. Richard A. Klein, P.E. PAProject Files\99043\9943 drainage report.doc 14 rL ' J I r� Oh ------ low All tt �, 1, r V, \ 1 C ;. ' SvI IN l' 12/4/98 10 : 19 : 41 are Pacific Engineering Design Inc _ BRIERE PLAT - JOB NO .98016 DRAINAGE CALCULATION`, BASIN SUMMARY BASIN ID: DEV100 NAME : 100-YR . DEV LESS BYPASS SBUH METHODOLOGY TOTAL AREA . . . . . . . : 2 .24 Acres BASEFLOWS : 0 .00 cfs RAINFALL TYPE . . . . : KC24HR DERV IM PRECIPITATION . . . . : 3 .95 inches AREA . . : 1 .16 Acres 1 .0- TIME INTERVAL . . . . : 10 .00 min, CN . . . . : 86 .00 98 .00 TC . . . . : 5 .00 min 5 .00 ABSTRACTION COEFF : 0 .20 PEAK RATE : 1 .92 cfs VOL : 0 .58 Ac-ft TIME : 470 min - �✓ e ���4 5;� e ICn PACIFIC E NCUNEERINQ EDE31QN INC. " gy-/e"e, re, CIVIL ENGINEERING AND PLANNING CONSULTANTS SHEET NO. OF �( CALCULATED BY J Y/i�/2_DATE _ 7. scs _ . f 5z) x ¢fix 3 e . ...... ....... 3o�a f G t�� ><- �� ->j- Zoo u - ..�3 / d :.......... 5,3 ....... ... . ......i... ._... ._ .. _r-...... ........ . __ ZGy _ ......._.... . 1 r '....... .:. .... . w s�Pr �3 P 130 ANDOVER PARK EAST, SUITE 300 SEATTLE, WASHINGTON 98188 (206) 431-7970 FAX:431-7975 12/4/98 10 : 17 : 30 am Pacific Engineering Design Inc BRIERE PLAT - JOB NO .98016 DRAINAGE CALCULATIONS BASIN SUMMARY BASIN ID: OFF-100 NAME : OFF-SITE 100-YR . EX . TO CULV . SBUH METHODOLOGY TOTAL AREA . . . . . . . : 7 .53 Acres BASEFLOWS: 0 .00 cfs RAINFALL TYPE . . . . . KC24HR PERV IM'' PRECIPITATION . . . . : 3 .95 inches AREA . . : 7 . 17 Acres 0 .36 TIME INTERVAL . . . . 10 .00 min CN . . . . : 85 .25 98 .00 TC . . . . : 37 .01 min 37 .01 ^. ABSTRACTION COEFF : 0 .20 TcReach - Sheet L : 300 .00 ns :0 . 1500 p2yr : 2 . 10 s : 0 .0164 TcReach - Shallow L : 200 .00 ks : 11 .00 s :0 .O180 TcReach - Channel L : 410 .00 kc : 20 .00 s : 0 .0113 PEAK RATE: 3 .09 cfs VOL : 1 .57 Ac-ft TIME : 480 min PACIFIC ENQINEERINQ DESIQN INC. JOe �r�`�'�e pe� /G� CIVIL ENGINEERING AND PLAN NINO CONSULTANTS SHEET NO. OF CALCULATED ev �-/ �r L�'7 DATE /Z-J3_ / U Ll Lam` 72- (0. 17?)Z.�. 0., 025 .. .... -. ..... ✓ .. ._....... a"1...a►'p i e. . ,.?2 �_`► _. i . 2, 9 ?_... y .Z .... Avr ... ... 9iv = �� Z l3 f a, 1¢Z = D �5 ,5 c fs pp-/�(: 2,_��1 _ J, ` ?s �l 2 3, o- ...�. 7 .... _. 3_.''.:. . _ f-=-- - 'D►(�2-(�a LG �•v¢ ,.e n 19 130 ANDOVER PARK EAST, SUITE 300 SEATTLE, WASHINGTON 98188 (206) 431-7970 FAX:431-7975 1:='/4/98 10 : 4 . 34 am Pacific Engineering Deign, Inc BRIERE PLAT -- JOB NO .98O16 DRAINAGE CALCULATIONS STAGE DISCHARGE TABLE MULTIPLE' ORIFICE ID No . 1 Description: DISCHARGE ORIFICE ASSEMBLY Outlet Elev : 411 .48 EI-_v : 409 .48 ft Orifice Diameter : 2 . 125O in . Elev : 413 .10 ft Orifice 2 Diameter : 2 .2000 in . Elev: 414 .40 ft Orifice 3 Diameter : 2 .7900 in . STAGE (--DISCHARGE---) STAGE (--DISCHARGE---) STAGE (--DISCHARGE---) STAGE (--DISCHARGE---) (ft) ---cfs-- ------- (ft) ---cfs-- ------- (ft) ---cfs-- ------- (ft) ---cfs-- ------- ------------------------------------- 411.48 0.0000 412.70 0.1354 414.00 0.3191 415.30 0.6347 411.50 0.0173 4!2.80 0.1408 414.10 0.3297 415.40 0.6536 411.60 0.0424 412.90 0.1460 414.20 0.3399 415.50 0.6707 411.70 0.0575 413.00 0.1511 414.30 0.3497 415.60 0.6878 411.80 0.0693 413.10 0.1560 414.40 0.3592 415.70 0.7044 411.90 0.0794 413.20 0.2022 414.50 0.4352 415.80 0.7205 412.00 0.0884 413.30 0.2241 414.60 0.4718 415.90 0.7361 412.10 0.0965 413.40 0.2417 414.70 0.5017 416.00 0.7514 412.20 0.1040 4!3.50 0.2572 414.80 0.5281 416.10 0.7663 412.30 0.1110 413.60 0.2713 414.90 0.5522 416.20 0.7809 412.40 0.1175 413.70 0.2843 415.00 0.5746 416.23 0.7852 412.50 0.1238 413.80 0.2965 415.10 0.5956 412.60 0.1297 413.90 0.3081 415.20 0.6156 )Q,�,4y,c4.� , 20 12/4/98 10 : 28 : 16 am Pacific Engineering Design Inc a_ BRIERS PLAT - JOB NO .98016 DRAINAGE CALCULATIONS BASIN SUMMARY BASIN ID : SUMMER NAME : 100-YR . DEV . FLOW - SUMMERWIND SBUH METHODOLOGY TOTAL AREA . . . . . . . : 4 .69 Acres BASEFLOWS : 0 .00 cfs RAINFALL TYPE . . . . KC24HR PERV IM PRECIPITATION . . . . : 3 .95 inches AREA . . : 2 .58 Acres 2 . 1 '_ TIME INTERVAL . . . . 10 .00 min CN . . . . - 86 .00 98 .00 TC . . . . : 10 .00 min 10 .00 r ABSTRACTION COEFF : 0 .20 PEAK RATE : 3 .59 cfs VOL : 1 .19 Ac-ft TIME : 480 min. MAN-MADE CHANNELS VARIABLES LIST: Y - FLOW DEPTH B - CHANNEL BOTTOM WIDTH S - CHANNEL SLOPE Q - FLOWRATE M - CHANNEL SIDE SLOPE N - CHANNEL ROUGHNESS VARIABLE TO BE SOLVED (Y, Q, B,M, S OR N) ? Y Q (CFS) ? 17 .21 RESULTS B (FT) ? 8 M (FT/FT) ? 3 Y= 0 .53 FT S (FT/FT) ? . 014 A= 5. 04 SF N (FT-1/6) ? . 030 P= 11 . 33 FT V= 3 . 42 FPS F= 0 . 90 SUB-CRITICAL -FLOW <Shift> <Prt Sc> print <Return> repeat <Space Bar> back to menu. ------------------------------------------------------------------------------- �►�IY�Ct CouY� � q � 22 CULVERTS RESULTS DIAMETER (IN) ? 18 HEADWATER (FT) FLO<WRATE (CFS) LENGTH (FT) ? 100 102.50 IC 7.61 FRICTION COEFF (FT^1/6) ? .013 103.00 IC 9.83 ENT+EXIT COEFF ? 0.5 103.50 IC 11.63��� 3 INLET CONTROL COEFF ? 0.62 104 .00 IC 13.19 104 .50 IC 14 .58 INV ELEV OUT (FT) 100.00 105.00 IC 15.85 INV ELEV IN (FT) ? 101.00 105.50 IC 17.03 TAILWATER ELEV (FT) ? 101.00 106.00 IC 18. 13 ELEV INCREMENT (FT) ? 0.5 106.50 IC 19. 16 107.00 IC 20. 15 107.50 IC 21.00, 108.00 IC 21.98 108.50 IC 22.84 109.00 IC 23.67 109.50 IC 24 . 48 I10.00 IC 25.25 <Shift> <Prt Sc> print <Return> repeat <Space Bar> back to menu ------------------------------------------------------------------------------- Z$ KING COUNTY, WASHINGTON, SURFACE WATER DESIGN INIANUAL FIGURE 4.3.5C HEADWATER DEPTH FOR SMOOTH INTERIOR PIPE CULVERTS WITH INLET CONTROL 180 to,000 168 8.000 EXAMPLE (2) (3)6. ENTRANCE TYPE 156 6,000 0.42 inches (3.5 feet) — 6_ —_ o•Izo cts ---- SQUARE EDGE ,'ITH 144 5,000 5. HEAD'04ALL 4,000 6. 5. MW� NW 132 o feet 3,000 5. 4. (t) 2.5 f1.8 4. 120 I l - 2,000 ' (3) 2.2 7.T 108 3. I ' `0 in feet 3. 96 1 000 3. PLAN \1 GROOVE ENO WITH Boo __.. HEADWALL 84 500 � ' 2.0 �� 1 Jz �. 72 400 w �Q� = 300 */� 1.5 1.5 U z 60 v 200 i� F 1.5 PLAN (2) ti3 GROOVE END 54 o C / a PROJECTING or /W / 100 W 48 0 80 44 o a 50 HW S ALE ENTRANCE 1.0 40 D TYPE _ w 36 9 ►- 30 (1) Sguars edge .iln 3 9 w 33 heod.all a a Q 20 (21 Groove end.tn a laJ 30 Aead.oll = .8 .8 (3) Groove end •B - 2 7 projecting r- 10 .7 7- 24 8 .7 6 To use scale (2) or (3) project 21 5 horizontally to scale (I),then 4 ute straight inclined line through 0 and o $tales,or rtrerse ae .6 3 illustrarsd. 6 6 18 i 2 15 t .5 .5 .5 1.0 12 �Iv� _ 2,0 = tTZ- CFs D Tct r--:: i - " Ifu i _ 4.3.5-11 1/90 24- IV. RETENTIONMETENTION ANALYSIS & DESIGN PAProject Files\99043\9943 drainage report.doc �� DRAINAGE DESIGN The Briere Creek Preliminary Plat is located on a parcel of land encompassing 3.68± acres of land approximately 300 feet north of the intersection of NE 18th St. and Duvall Ave NE on the east side of Duvall, directely across from the entrance to the May Creek Highlands development. The Brieres live in the existing residence located on proposed lot 1, and run their construction business from the existing residence located on proposed lot 18. Also located on the site is a large workshop, detached garage and storage shed. Numerous items from the Briers construction business are stored about the site. The site is zoned Residential - 8 Dwelling units per acre (R-8). The surrounding properties consist of single family to the north, the Plat of Summerwind to the east, a vacant lot to the south and single family homes on large lots to the west (May Creek Highlands). The project consists of road and utility improvements both on-site and off-site. Utilities will include sanitary sewer, storm drainage, water and franchised utilities. Storm drainage will include an underground storm detention vault for drainage control and a biofiltration swale for water quality control. When completed, there will be 18 single-family residential lots. Drainage flow is generally towards the northeast into an existing off-site drainage course flowing into Tract "A" of the Summerwind Div. 4 Plat. The open drainage course discharges into a piped conveyance system flowing south under Field Avenue NE. The project will comply with Core Requirements 1-5. None of the Special Requirements from 1-12 appear to apply to this project. Calculations to size a storm drainage detention vault were done using the WATERWORKS program based on the SBUH/SCS hydrograph method. Adjusting for a small by-pass area, the pre-developed 2-year and 10-year/24 hr. storm events were matched with the post-developed 2- year and 10-year/24 hr. events to determine the required storm detention vault volume (see attached calculations). The vault is designed to route the 100-year storm without detaining per the 1990 KCSWM. Calculations for the bio-filtration swale were done based on the 2-year/24 hr. pre-developed discharge rate (see attached calculations). Flow depths were also calculated for the 10-year and 100-year events. A wetpond is not required on this project due to the fact that the impervious area subject to vehicular use and/or storage of chemicals is less than 1 acre (0.74 acres). That area includes roads, sidewalks and driveways. PAProject Files\99043\9943 drainage report.doc 2CO 4/28/00 8 : 0 : 16 am Pacific Engineering Design Inc page 2 Briere Creek BASIN SUMMARY BASIN ID: Pre-E10 NAME : Pre Dev 10yr flowing east SBUH METHODOLOGY TOTAL AREA. . . . . . . : 2 . 89 Acres BASEFLOWS : 0 . 00 cfs RAINFALL TYPE. . . . : KC24HR PERV IMP PRECIPITATION. . . . : 3 . 00 inches AREA. . : 2 . 89 Acres 0 . 00 Acres TIME INTERVAL. . . . : 10 . 00 min CN. . . . : 86 . 00 0 . 00 TC. . . . . 35 . 20 min 0 . 00 min ABSTRACTION COEFF: 0 . 20 TcReach - Sheet L: 165 . 00 ns : 0 . 1300 p2yr: 2 . 10 s : 0 . 0363 TcReach - Sheet L: 65 . 00 ns : 0 . 1300 p2yr: 2 . 10 s : 0 . 0308 TcReach - Sheet L: 70 . 00 ns : 0 . 1300 p2yr: 2 . 10 s : 0 . 0090 TcReach - Shallow L: 40 . 00 ks : 5 . 00 s : 0 . 0090 TcReach - Channel L: 100 . 00 kc : 5 . 00 s : 0 . 0090 PEAK RATE : 0 . 77 cfs VOL: 0 . 40 Ac-ft TIME : 480 min BASIN ID: Pre-E100 NAME : Pre Dev 100yr flowing east SBUH METHODOLOGY TOTAL AREA. . . . . . . : 2 . 89 Acres BASEFLOWS : 0 . 00 cfs RAINFALL TYPE. . . . : KC24HR PERV IMP PRECIPITATION. . . . : 4 . 10 inches AREA. . : 2 . 89 Acres 0 . 00 Acres TIME INTERVAL. . . . : 10 . 00 min CN. . . . : 86 . 00 0 . 00 TC. . . . . 35 . 20 min 0 . 00 min ABSTRACTION COEFF: 0 . 20 TcReach - Sheet L: 165 . 00 ns : 0 . 1300 p2yr: 2 . 10 s : 0 . 0363 TcReach - Sheet L: 65 . 00 ns : 0 . 1300 p2yr: 2 . 10 s : 0 . 0308 TcReach - Sheet L: 70 . 00 ns : 0 . 1300 p2yr: 2 . 10 s : 0 . 0090 TcReach - Shallow L: 40 . 00 ks : 5 . 00 s : 0 . 0090 TcReach - Channel L: 100 . 00 kc : 5 . 00 s : 0 . 0090 PEAK RATE : 1 . 30 cfs VOL: 0 . 64 Ac-ft TIME : 480 min BASIN ID: Pre-E2 NAME : Pre Dev 2yr flowing east SBUH METHODOLOGY TOTAL AREA. . . . . . . : 2 . 89 Acres BASEFLOWS : 0 . 00 cfs RAINFALL TYPE . . . . : KC24HR PERV IMP PRECIPITATION. . . . : 2 . 10 inches AREA. . : 2 . 89 Acres 0 . 00 Acres TIME INTERVAL. . . . : 10 . 00 min CN. . . . : 86 . 00 0 . 00 TC. . . . . 35 . 20 min 0 . 00 min ABSTRACTION COEFF: 0 . 20 TcReach - Sheet L: 165 . 00 ns : 0 . 1300 p2yr: 2 . 10 s : 0 . 0363 TcReach - Sheet L: 65 . 00 ns : 0 . 1300 p2yr: 2 . 10 s : 0 . 0308 TcReach - Sheet L: 70 . 00 ns : 0 . 1300 p2yr: 2 . 10 s : 0 . 0090 TcReach - Shallow L: 40 . 00 ks : 5 . 00 s : 0 . 0090 TcReach - Channel L: 100 . 00 kc : 5 . 00 s : 0 . 0090 PEAK RATE : 0 . 38 cfs VOL: 0 . 22 Ac-ft TIME : 490 min Z' 4/28/00 8 : 0 : 16 am Pacific Engineering Design Inc page 1 Briere Creek BASIN SUMMARY BASIN ID: Dev-E10 NAME : Post Dev 10yr Flowing East SBUH METHODOLOGY TOTAL AREA. . . . . . . : 3 . 16 Acres BASEFLOWS : 0 . 00 cfs RAINFALL TYPE . . . . : KC24HR PERV IMP PRECIPITATION. . . . : 3 . 00 inches AREA. . : 1 . 85 Acres 1 . 31 Acres TIME INTERVAL. . . . : 10 . 00 min CN. . . . : 86 . 00 98 . 00 TC. . . . . 11 . 24 min 2 . 00 min ABSTRACTION COEFF: 0 . 20 TcReach - Sheet L: 100 . 00 ns : 0 . 1500 p2yr: 2 . 10 s : 0 . 0240 impTcReach - Shallow L: 110 . 00 ks : 27 . 00 s : 0 . 0150 impTcReach - Channel L: 258 . 00 kc :42 . 00 s : 0 . 0050 PEAK RATE : 1 . 81 cfs VOL: 0 . 56 Ac-ft TIME: 470 min BASIN ID: Dev-E100 NAME : Post Dev 100yr Flowing East SBUH METHODOLOGY TOTAL AREA. . . . . . . : 3 . 16 Acres BASEFLOWS : 0 . 00 cfs RAINFALL TYPE. . . . : KC24HR PERV IMP PRECIPITATION. . . . : 4 . 10 inches AREA. . : 1 . 85 Acres 1 . 31 Acres TIME INTERVAL. . . . : 10 . 00 min CN. . . . : 86 . 00 98 . 00 TC. . . . . 11 . 24 min 2 . 00 min ABSTRACTION COEFF: 0 . 20 TcReach - Sheet L: 100 . 00 ns : 0 . 1500 p2yr: 2 . 10 s : 0 . 0240 impTcReach - Shallow L: 110 . 00 ks : 27 . 00 s : 0 . 0150 impTcReach - Channel L: 258 . 00 kc :42 . 00 s : 0 . 0050 PEAK RATE : 2 . 69 cfs VOL: 0 . 83 Ac-ft TIME : 470 min BASIN ID: Dev-E2 NAME : Post Dev 2yr Flowing East SBUH METHODOLOGY TOTAL AREA. . . . . . . : 3 . 16 Acres BASEFLOWS : 0 . 00 cfs RAINFALL TYPE . . . . : KC24HR PERV IMP PRECIPITATION. . . . : 2 . 10 inches AREA. . : 1 . 85 Acres 1 . 31 Acres TIME INTERVAL. . . . : 10 . 00 min CN. . . . : 86 . 00 98 . 00 TC. . . . : 11 . 24 min 2 . 00 min ABSTRACTION COEFF: 0 . 20 TcReach - Sheet L: 100 . 00 ns : 0 . 1500 p2yr: 2 . 10 s : 0 . 0240 impTcReach - Shallow L: 110 . 00 ks : 27 . 00 s : 0 . 0150 impTcReach - Channel L: 258 . 00 kc :42 . 00 s : 0 . 0050 PEAK RATE : 1 . 12 cfs VOL: 0 . 35 Ac-ft TIME : 470 min r� 4/28/00 8 : 0 : 17 am Pacific Engineering Design Inc page 9 Briere Creek HYDROGRAPH SUMMARY PEAK TIME VOLUME HYD RUNOFF OF OF Contrib NUM RATE PEAK HYDRO Area cfs min. cf\AcFt Acres 1 0 . 380 490 9708 cf 2 . 89 2 0 . 769 480 17441 cf 2 . 89 3 1 . 297 480 27665 cf 2 . 89 4 1 . 116 470 15124 cf 3 . 16 5 1 . 809 470 24328 cf 3 . 16 6 2 . 691 470 36088 cf 3 . 16 11 0 . 380 530 15124 cf 3 . 16 12 0 . 769 510 24328 cf 3 . 16 13 0 . 349 540 15124 cf 3 . 16 14 0 . 683 520 24328 cf 3 . 16 15 2 .484 490 36088 cf 3 . 16 2,�l 4/28/00 8 : 0 : 17 am Pacific Engineering Design Inc page 10 Briere Creek STORAGE STRUCTURE LIST RECTANGULAR VAULT ID No. v Description: vault before f . s Length: 48 . 00 ft . Width: 24 . 00 ft . voids : 1 . 000 RECTANGULAR VAULT ID No. v2 Description: vault with 30% f .o. s . Length: 58 . 00 ft . Width: 26 . 00 ft . voids : 1 . 000 4/28/00 8 : 0 : 17 am Pacific Engineering Design Inc page 11 Briere Creek STAGE STORAGE TABLE RECTANGULAR VAULT ID No. v Description: vault before f . s Length: 48 . 00 ft . Width: 24 . 00 ft . voids : 1 . 000 STAGE <----STORAGE----> STAGE <----STORAGE----> STAGE <----STORAGE----> STAGE <----STORAGE----> (ft) ---cf--- --Ac-Ft- (ft) ---cf--- --Ac-Ft- (ft) ---cf--- --Ac-Ft- (ft) ---cf--- --Ac-Ft- 416.90 0.0000 0.0000 418.20 1498 0.0344 419.50 2995 0.0688 420.80 4493 0.1031 417.00 115.20 0.0026 418.30 1613 0.0370 419.60 3110 0.0714 420.90 4608 0.1058 417.10 230.40 0.0053 418.40 1728 0.0397 419.70 3226 0.0740 421.00 4723 0.1084 417.20 345.60 0.0079 418.50 1843 0.0423 419.80 3341 0.0767 421.10 4838 0.1111 417.30 460.80 0.0106 418.60 1958 0.0450 419.90 3456 0.0793 421.20 4954 0.1137 417.40 576.00 0.0132 418.70 2074 0.0476 420.00 3571 0.0820 421.30 5069 0.1164 417.50 691.20 0.0159 418.80 2189 0.0502 420.10 3686 0.0846 421.40 5184 0.1190 417.60 806.40 0.0185 418.90 2304 0.0529 420.20 3802 0.0873 421.50 5299 0.1217 417.70 921.60 0.0212 419.00 2419 0.0555 420.30 3917 0.0899 421.60 5414 0.1243 417.80 1037 0.0238 419.10 2534 0.0582 420.40 4032 0.0926 421.70 5530 0.1269 417.90 1152 0.0264 419.20 2650 0.0608 420.50 4147 0.0952 421.80 5645 0.1296 418.00 1267 0.0291 419.30 2765 0.0635 420.60 4262 0.0979 421.90 5760 0.1322 418.10 1382 0.0317 419.40 2880 0.0661 420.70 4378 0.1005 J 4/28/00 8 : 0 : 17 am Pacific Engineering Design Inc page 12 Briere Creek STAGE STORAGE TABLE RECTANGULAR VAULT ID No . v2 Description: vault with 30o f .o . s . Length: 58 . 00 ft . Width: 26 . 00 ft . voids : 1 . 000 STAGE <----STORAGE----> STAGE <----STORAGE----> STAGE <----STORAGE----> STAGE <----STORAGE----> (ft) ---cf--- --AC-Ft- (ft) ---cf--- --Ac-Ft- (ft) ---cf--- --AC-Ft- (ft) ---cf--- --Ac-Ft- 416.90 0.0000 0.0000 418.20 1960 0.0450 419.50 3921 0.0900 420.80 5881 0.1350 417.00 150.80 0.0035 418.30 2111 0.0485 419.60 4072 0.0935 420.90 6032 0.1385 417.10 301.60 0.0069 418.40 2262 0.0519 419.70 4222 0.0969 421.00 6183 0.1419 417.20 452.40 0.0104 418.50 2413 0.0554 419.80 4373 0.1004 421.10 6334 0.1454 417.30 603.20 0.0138 418.60 2564 0.0589 419.90 4524 0.1039 421.20 6484 0.1489 417.40 754.00 0.0173 418.70 2714 0.0623 420.00 4675 0.1073 421.30 6635 0.1523 417.50 904.80 0.0208 418.80 2865 0.0658 420.10 4826 0.1108 421.40 6786 0.1558 417.60 1056 0.0242 418.90 3016 0.0692 420.20 4976 0.1142 421.50 6937 0.1592 417.70 1206 0.0277 419.00 3167 0.0727 420.30 5127 0.1177 421.60 7088 0.1627 417.80 1357 0.0312 419.10 3318 0.0762 420.40 5278 0.1212 421.70 7238 0.1662 417.90 1508 0.0346 419.20 3468 0.0796 420.50 5429 0.1246 421.80 7389 0.1696 418.00 1659 0.0381 419.30 3619 0.0831 420.60 5580 0.1281 421.82 7419 0.1703 418.10 1810 0.0415 419.40 3770 0.0865 420.70 5730 0.1316 7 4/28/00 8 : 0 : 17 am Pacific Engineering Design Inc page 13 Briere Creek ------------- DISCHARGE STRUCTURE LIST COMBINATION DISCHARGE ID No. c Description: combo Structure : o Structure : Structure : r Structure : Structure : MULTIPLE ORIFICE ID No. o Description: orifice Outlet Elev: 416 . 90 Elev: 414 . 90 ft Orifice Diameter : 3 . 2695 in. Elev: 418 . 70 ft Orifice 2 Diameter: 3 . 0820 in. RISER DISCHARGE ID No. r Description: Riser Riser Diameter (in) : 12 . 00 elev: 419 . 82 ft Weir Coefficient . . . : 9 . 739 height : 421 . 90 ft Orif Coefficient . . . : 3 . 782 increm: 0 . 10 ft 4/28/00 8 : 0 : 17 am Pacific Engineering Design Inc page 14 Briere Creek STAGE DISCHARGE TABLE COMBINATION DISCHARGE ID No. c Description: combo Structure : o Structure : Structure : r Structure : Structure : STAGE <--DISCHARGE---> STAGE <--DISCHARGE---> STAGE <--DISCHARGE---> STAGE <--DISCHARGE---> (ft) ---CfS-- ------- (ft) ---CfS-- ------- (ft) ---CfS-- ------- (ft) ---CfS-- ------- 416.90 0.0000 418.20 0.3308 419.50 0.6983 420.80 4.6904 417.00 0.0917 418.30 0.3432 419.60 0.7212 420.90 4.8929 417.10 0.1297 418.40 0.3553 419.70 0.7432 421.00 5.0866 417.20 0.1589 418.50 0.3669 419.80 0.7644 421.10 5.2727 417.30 0.1835 418.60 0.3782 419.90 1.0052 421.20 5.4520 417.40 0.2051 418.70 0.3892 420.00 1.5484 421.30 5.6251 417.50 0.2247 418.80 0.4814 420.10 2.2669 421.40 5.7928 417.60 0.2427 418.90 0.5255 420.20 3.1240 421.50 5.9555 417.70 0.2595 419.00 0.5616 420.30 3.4812 421.60 6.1137 417.80 0.2752 419.10 0.5933 420.40 3.7591 421.70 6.2676 417.90 0.2901 419.20 0.6222 420.50 4.0150 421.80 6.4177 418.00 0.3042 419.30 0.6491 420.60 4.2535 421.90 6.5643 418.10 0.3178 419.40 0.6743 420.70 4.4779 lb 4 4/28/00 8 : 0 : 17 am Pacific Engineering Design Inc page 15 Briere Creek STAGE DISCHARGE TABLE MULTIPLE ORIFICE ID No. o Description: orifice Outlet Elev: 416 . 90 Elev: 414 . 90 ft Orifice Diameter : 3 . 2695 in. Elev: 418 . 70 ft Orifice 2 Diameter : 3 . 0820 in. STAGE <--DISCHARGE---> STAGE <--DISCHARGE---> STAGE <--DISCHARGE---> STAGE -DISCHARGE---> (ft) ---cfs-- ------- (ft) ---cfs-- ------- (ft) ---cfs-- ------- (ft) ---cfs-- ------- 416.90 0.0000 418.20 0.3308 419.50 0.6983 420.80 0.9464 417.00 0.0917 418.30 0.3432 419.60 0.7212 420.90 0.9625 417.10 0.1297 418.40 0.3553 419.70 0.7432 421.00 0.9783 417.20 0.1589 418.50 0.3669 419.80 0.7644 421.10 0.9938 417.30 0.1835 418.60 0.3782 419.90 0.7848 421.20 1.0091 417.40 0.2051 418.70 0.3892 420.00 0.8047 421.30 1.0241 417.50 0.2247 418.80 0.4814 420.10 0.8239 421.40 1.0389 417.60 0.2427 418.90 0.5255 420.20 0.8427 421.50 1.0535 417.70 0.2595 419.00 0.5616 420.30 0.8610 421.60 1.0679 417.80 0.2752 419.10 0.5933 420.40 0.8788 421.70 1.0820 417.90 0.2901 419.20 0.6222 420.50 0.8962 421.80 1.0960 418.00 0.3042 419.30 0.6491 420.60 0.9133 421.90 1.1098 418.10 0.3178 419.40 0.6743 420.70 0.9300 35 4/28/00 8 : 0 : 17 am Pacific Engineering Design Inc page 16 Briere Creek STAGE DISCHARGE TABLE RISER DISCHARGE ID No . r Description: Riser Riser Diameter (in) : 12 . 00 elev: 419 . 82 ft Weir Coefficient . . . : 9 . 739 height : 421 . 90 ft Orif Coefficient . . . : 3 . 782 increm: 0 . 10 ft STAGE <--DISCHARGE---> STAGE <--DISCHARGE---> STAGE <--DISCHARGE---> STAGE <--DISCHARGE---> (ft) ---CfS-- ------- (ft) ---CfS-- ------- (ft) ---CfS-- ------- (ft) ---CfS-- ------- 419.82 0.0000 420.40 2.8803 421.00 4.1083 421.60 5.0458 419.90 0.2204 420.50 3.1187 421.10 4.2788 421.70 5.1856 420.00 0.7437 420.60 3.3402 421.20 4.4428 421.80 5.3217 420.10 1.4430 420.70 3.5478 421.30 4.6010 421.90 5.4545 420.20 2.2813 420.80 3.7440 421.40 4.7539 420.30 2.6202 420.90 3.9304 421.50 4.9020 4/28/00 8 : 0 : 18 am Pacific Engineering Design Inc page 17 Briere Creek LEVEL POOL TABLE SUMMARY MATCH INFLOW -STO- -DIS- <-PEAK-> STORAGE <--------DESCRIPTION---------> (cfs) (cfs) --id- --id- <-STAGE> id VOL (cf) Pre2 - Dev2 .................. 0.38 1.12 v 0 418.61 11 1972.38 cf Pre10 - Dev10 ... ............. 0.77 1.81 v 0 419.82 12 3368.99 cf Pre2 - Dev2 .................. 0.38 1.12 v2 c 418.35 13 2181.17 cf Pre10 - Dev10 ................ 0.77 1.81 v2 c 419.44 14 3826.84 cf Pre100 - Dev100 ........... ... 0.00 2.69 v2 c 420.13 15 4863.75 cf PACIFIC ENOINEERINGI LESION INC. = "' 'E)o,c:-eiE Ceeey_- r ` `C43 CIVIL ENGINEERING AND PLANNING CONSULTANTS SHEET NO. OF 1 CALCULATED BY �� �` •I DATE VOL: C��io. �'tV""�aa,"�tb�� . PZC't'��'S� `;Lope �•Cv?°Ie� �, U a C�a ...... .. ... .. ... .. .. .... b ...Y._...0 33 .. ! ©�_35 .. 0�020 F�fT" t,. .. ..� .. 1Z . . ...... .... 1,4`� . ... .. . q2 ..... (0 5}.. . 3` Y 3 I 1,49-Jg b a.o C4) 4,0 ... . .. OT�b 11A W ITti 4,O' ........ ..r . __ . �.oW _ri' c�.33' .C 4:' .� off. ��tt�� "-� ► .. ... .... .. Q A C �.CY�' ' ►tn Cy_ )2 (4�(a,33� (3�Co: 2 �" t_. .......4 '2. .... . �/..= d 232 ' �s � ok .... .. . di 54...0 {023 ..} --... 125...E FT ..............--a► 2vv' oV�_ ?....................... ok� T = Z . l sEc. 14 3� rn �, s,I�E �cE T�ritE b 232 3a . 4B00 S. I BBTH ST., SUITE 360, SEATTLE, WASHINGTON JB 1 8B 206/431-7970 FAX/431-7J75 PACIFIC ENOINEERINO DESION INC. 'OB CIVIL ENGINEERING AND PLANNING CONSULTANTS SHEET NQ OF CALCULATED BY .. .. ... ... .. _. �Jlbta .. .... ..........>.... ..>...........: ... .... ...... .. ....:.. ..:... ..:. b, 7 ct t� 20 �- o.ofrT h 4,0 ` :..........:.....e .ld............ .. .. ...... ........ . o �. .............>...................... .............. . Iz................._.....;.......i........... . .......... _..Y_:......... .. { .:.. o.5c�` �- C,'' s ............<.................................................................... ... ...... A o,5c �J.... © �5e Z.'T�'FT 2 .. ............:............:.............:............:.. ,?.:............... ........ 2 V = ........ .. .....t. ............._........ ............. .. .. ................ ...... .. .. .. b .............. ...._,..........;........................a .. .... ....ton. .`-........_2_ �`� Cf'`� .. ZU -. pc�co"7 F ��".. Qr.,��... .. ..... .... b, ................................ ..........a................ , II; ctati.... 2,c� , y - 1 oc� x . 12:.� 1 t4� .. d,00 �i... 4 .........:.............:....................................................................... ..... . :............:....... .. ............. .. 4.C d .�- .'3 C e cx��2 �.. c, T 2 v;- ..._........... ...... -� ........... . 2 YeW 0,33 , .,� . ... ... oJc, st. ?E o ,ocaco7 �r� ..... .. .. ... 1.. 4800 S. 1 BETH ST., SUITE 360, SEATTLE, WASHINGTON 981 88 206/431-7970 FAX/431-7J75 V. CONVEYANCE SYSTEM ANALYSIS & DESIGN Considering the small site, and piping system, by inspection the conveyance system is adequate. Check (by Waterworks) A = 3.16 Ac Pervious: A=1.85acres, CN = 86.0, Tc=11.24 Impervious: A=1.85acres, CN = 98.0, Tc=2.00 P25= 3.4"/hr For 25-year storm, Q = 2.21 cfs The flow going into the detention vault is split between three pipes, with the least slope of the three being 1.0%. QF= .463/n d8/3sI12 = .463/.013 (1)8/3(.01)1/2 = 3.56 cfs> 2.21 4o PAProject Files\98016\9816-drarpt.doc VI. SPECIAL REPORTS & STUDIES Not Applicable PAProject Files\99043\9943 drainage report.doc 4-' VII. BASIN & COMMUNITY PLAN AREAS Not Applicable PAProject Files\99043\9943 drainage report.doc 42 VIII. OTHER PERMITS Not Applicable PAProject Files\99043\9943 drainage report.doc 43 IX. EROSION/SEDIMENTATION CONTROL DESIGN A. 1550 LF of silt fence will be installed around the perimeter of the site to prevent silt laden water to exit the property. B. A 24' x 100' x 12" rocked construction entrance of 4"dia. — 8"dia. quarry spalls will be installed at the west entrance to the site (NE 19th Street) from Duvall Ave NE. C. A Temporary Sediment Trap will be installed near the northeast corner of the site to be sized as follows: Per K.C.S.W.M. 1990 (94 Update) Section 5.4.5.1 Required Surface Area = 2 x Q2/0.00096 Q2 = 0.38/cfs (Per Drainage Report) 2 x 0.38/0.00096 = 791.67 SF Top of Berm = 420.0 Weir Elevation = 419.0 Surface Area Required = 792 SF Surface Area Provided = 832 SF Bottom of Trap = 416.5 The overflow spillway weir will be directed eastward towards the bio-filtration swale. 1100 LF of 'V' Ditch Interceptor with rock check dams set at prescribed intervals will route silt laden runoff to the sediment trap. PAProject Files\99043\9943 drainage report.doc 44 X. BOND QUANTITIES WORKSHEET RETENTION/DETENTION FACILITY SUMMARY SHEET AND SKETCH, AND DECLARATION OF COVENANT 45 PAProject Files\99043\9943 drainage report.doc PUBLIC WORKS CONSTRUCTION PERMIT INSPECTION/APPROVAL FEE CALCULATION WORKSHEE"I' 50% INSPECTION/APPROVAL FEES PER ORDINANCE NO. 4345 Estimate the total cost of offsite and onsite improvements for water lines, sewer lines, s!ormwater facilities, and roadway improvements for your project. Enter estimated costs in itcnls (A)through (D) below. (A) Water (B) Sewer (i:) Stormwater C)3 (Includes On-Site Pavement) (ID) Roadway $ �� •70 00 (Street, sidewalks, street lighting, etc.) (E) Total Improvements (A)+(B)+(C)+(D)=(E 2. Cilculate 50% inspection/approval fee for total improvements, as follows: (F) 2.5% of First$100,000 of(E) $ 2. ,S00 , U U (G) 2% of over$100,000 but $ 0 yy oc) less than $200,000 of(E) (1-1) 1.5%of over$200,000 of(E) 2 S' Total 50% Inspection/Approval /cc Co , Fee: (F)+ (G)+(H)=(1) :. isreakduwn of 50% Inspection/Approval Fees is performed as follows: (J) 50% Water Fee S t 44 . 14'Co 401/343.90.00.02 ((A) \ (E))x(I)_(J) (K) 50% Sewer Fee 5'� r� 401/343.90.00.01 ((B) \ (E))x(1)_(K) (L) 50% Stormwater Fee 401/343.90.00.03 ((C) \ (E))x (1)= (L) — (M) 50% Roadway Fee: $ `�1 '�'�; • 000/343.20.00.00 ((D) \ (E))x(I)=(M) Check: Make sure(J)+(K)+(L)+(M) _ (1) SYS1Y1W\98BLDGCS\W30.DOC Revision Date: June 11, 1997 PACIFIC ENQINEERINQ DE31QN INC. 'O8 . �`��� CIVIL ENGINEERING AND PLANNING CONSULTANTS SHEET NO. t OF CALCULATED BY L ' �^� t� DATE CST .... vt . wA-z- , _.. ............ ......... .. ........ L, a" a,I, 554. ��. 35a �L _ I"I 30 ►oo 3. 3� 12'' FiTTIJ, I G C000��/ C , 00 .. ...:5,1 fir (�A7E Y.P<Lvet - 1 G o, 00. .. . j( ILA 2q.na .......... ....... ... T. Fits ..�t�oe,�.�1t.. .... ..I �° 1500 �t-�. ..... . I I ��� a� . NA ....................... ..... To�L wz' - 34� �� , coo ........:.... ..... .... .............:..... ..........:._. .. ... .. ... .. ...... ..... ... .... .. ._...................... ......._. .. ..... .>. . .._ .... .. �.... .... .. _.. .. .. ..._ .. .. ...._ ._.. .. _.._ ... ..... 41 i 4800 S. 188TH ST., SUITE 360, SEATTLE, WASHINGTON 961 89 206/431-7970 FAX/431-7975 PACIFIC ENQINEERINQ DESIQN INC. '108 ' � CIVIL ENGINEERING AND PLANNING CONSULTANTS SHEET NO. OF _ CALCULATED BY �` ` '*���'t' DATE . ... C�` T ...... TI tu �`t`� . .. Spri ITV '` . slob :... ... 2 8" �/G 4$I�l... I$ f L 8, Za4 ,a�. .. . `- .... 3 pl' .1�C......:. Cot 3 �.� @' / L� - ...'�S(a o 0 ............................:...........;.............:. . . .. .._.... 4 ; 8" c� uzs 1 25c�`` - - 2so .©d ............e.. .. ........ :. ... . T oz.��. S�.i�� � ,o0 2 ... i 3 o .. .. .. 4800 S. 1 BBTH ST., SUITE 360, SEATTLE, WASHINGTON 981 B8 206/431-757O FAX/431-7J75 PACIFIC ENQINEERINQ LESION INC. t C.ses`g. CIVIL ENGINEERING AND PLANNING CONSULTANTS SHEET NQ 1 OF CALCULATED BY `` 'S� DATE .. ... . ... .. ..... _. Ca�T Ca T r �-r Toemi cs> a 1. T z- .cc M + 3C� 1?00= f 1. 1 , Goo , .: .... ..... , 2, Tz .._co,- -c$AI 11 c �5c 1 ... ........................................... . a i " �-toerA C . 2�, t80 �'F@ 1$°"r� 1 � U4o ,oQ ............... ......... ... F v ...... ... 5, �,I c . �c�v�'S Zoo - 3,G,o01 oa r........ ....... .. to , 0E�`CjTlac, � wr�� ^ww� 4U , boQ oc . . .. f=.tt_ZC-�? sw 20o LIF GJ.. 2��1,�- ...... ......... ....... ... . ..... Totem Z'oetu `�(c� 83U .or> .. . ........... ....... __ 41 4800 S. 1 BETH ST., SUITE 360, SEATTLE, WASHINGTON 981 88 206/431-7970 FAX/439-7975 PACIFIC ENQINEERINO DESIQN INC. aoB �et G� 1�- M CIVIL ENGINEERING AND PLANNING CONSULTANTS SHEET NO. ( } OF CALCULATED By " , �'`� vf" DATE TE . .. . m' ... P�DtPs`� �O 1Z'E .....;..... . I . 7 . � .. 23So -av 22 vv�s� 51 ! o 40 , ov .. .. .. . .. Y .... .... . 4ZP7 LIB�tZ S S �- cE->a 'Z4 .. ,o« ,o 0 . .. ...................................... ........ ,., .......................... ..... . ... ; . ,. ...Q.o�W� T'ozPct . . 5a . . : 4800 S. 1 88TH ST., SUITE 360, SEATTLE, WASHINGTON 981 88 206/431-7570 FAX/431-7J75 KING COUNTY, WASHINGTON, SURFACE WATER DESIGN MANUAL RETENTION/DETENTION SUMMARY SHEET ��► cy.E�y-.. S/tg�oc� Development Date Location 0UV"LL PAVE, �_1c— 15 0,E. nu, ,=-)T ' HICt t..�' ENGINEER DEVELOPER Name Lou Name_�51L.L 4 1 Firm PACirc Firm PieiEQE Address 4500 S- ISS r� ST # 3L'—' y Address 1944 Q'011�1,LL TWE I S -EAZTLE I WA. 151SS (?C-t.Tod, LJN, 9Sa59 Phone 2e-xv-43 I 19-7a Phone 425- 228 - 71-70 • Developed Site acres Number of Lots I8 • Number of Detention Facilities On Site • Detention provided in regional facility F-1 Regional Facility location • No detention required 0 Acceptable receiving waters • Downstream Drainage Basins Immediate Major Basin Basin A SurnwrEeWlL1r� EEcilaL� t ('oJ�) Basin B Basin C Basin D TOTAL INDIVIDUAL BASIN Drainage Basin(s) A B C D Onsite Area Off site Area Yruc-r Type of Storage Facility Live Storage volume 4,4(4v4•FT3 Predeveloped Runoff Rate 2year v,3S 10year Postdeveloped Runoff Rate 100 year 130 2 year 10 year Developed Q 100 year 2•Co`1 Type of Restriction Size of Orifice/Restriction Orifice/Restriction No.1 3�Z7"(o) No.2 No.3 -- No.4 No.5 nn_i t� r i i i r\ ax+D unnnc E c�Dvcn utn 6Q'Lg A.DlF4F {ROCxMrG nOL US [D'Gn.uri 1. To,C.as a- yp n tra.units anal ire conalr.<t<e in occwaoner..in IT, --thn.n to � ELEVATION (SEE DwG E BRi91 To,Calm ea•4 i 2,si m�nimam alwnel«. c� w• �-'��b- u MAXIMUM OPENING HAn011OLOS z. Fa detols"Oe'"grade ring,lade«.steP%hendtaas.end lop atom,see Slantfwd Pion OF CATE -HANDLE WITH LOCK PIN8 ZYiae4lmeous CotN Bnsin a•taYi.WN T6' Ax 3. Ppa Cuppwts ona usUiet«/upwolw shall Oa of l!t•tam•motbid.and 04 cnwW of3'ma.imom•pochg by 5/8-ale stainless st.a expansion eats««nbedded 2'1.+al. ADJUSTABLE LOCK HOOKFco.EWI_.ELEV 4. The restrict«/sepwat«met be fe«4ated Hem.060'duminum.or.064 aNmw:w steel. WITH LOCK SCREW ry51.hOARD GALVANIZEDTO?ROMOEOErzNnONEVSTEEL UDOER/STEPS «.061'gdwnirsd aloel pipe: Inoatweonc.+iln AA5Hi0 Y 36.4 198,an0 M 174.Ae Sc,A'IS t1oN I _ acl.•snl:ea'I.0 shce now Treatment I LIFT HANDLE SHALL BEPEA vLAxz ATTACHED PER MANUFACTURER'S 1" ROD OR TUBING, s Q.14t analbe correct.,t4 caw i or aL«be PipeOf w a storeere cowl nq Cana l« ' f RECOMMENDATIONS VARIA13LE LENGTH p cwmgotea madpia•,«grwad No tno bee of oanu•4 pipe Y YIN 6. The wrticel rl•.r st.m el the rest,icl«/sewatm shell be the eons diameter m IM hoAsontotwt4t pipe,+Itn an 8•mini a e4m.l«. HOTS 3)075'A A iNUM; Os�a.YErz:et f;SEAR GATE 7. Frane and Iwde,or steps ere to be oNsa so that:u»•srzEi (SEE osc NAPE D-27) A. oeanwt gate is ,isnle front too LIFT_HANDLEco 9. Oinb-dp W.C.I.Near of rf.er d pole. rj)rt y�OU_TLET PIPE WL+T Ppc C. frame 4 dew of Curb(it any w.isls) NDTES- a. J NOTES 5.6 WAPES9. 4010-orifice dbora may b•located as Now.,w dl on one side of riser to awra lode« I. $HEAR CATS$HW cloore . Siy.of dba.a and oi.,-nt to be dirt«minsd by Ue Engines. ALL BE ALUMINUM ALLOY PER ASTY 8-26-2C-J20 OR i4 ! CAST IRON ASTM A48 CLASS 308 AS REWIRED.W PsREP! SV. 9. R•atrktw pty.+Rh ed tide in ato be h the d end ct pone dolt pate If 1«d1ti? WYFR�µ a Po•UUon avy, Sp.dAw epeninq to b+wl.Dana ona.mein. 2. GATE SHALL BE 8'DtAMETER FOR PIPE 12 INCHES OR LESS IN DIAMETER, „�� P[[RR t0. p•anwt/Sher gate: 12'DIAMETER FOR PIPES CNLAIER THAN 12'. W -ATumbx,m Buoy per ASM 8-26-ZO-33e o.coal Yon ASTY A48 you]OB Is r.y'q 3. GATE SHALL BE JOINED TO TEE SECTION BY HOI.NNC THROUGH FLANGE. j -Ne Nana.olm«said«wiring with edu.teble hotel,mti a.rep Y.a. -SIX EVENLY SPACED HOLES FOR ; G -Heopr.nery;abb«Oa.Ih.a,equYw ire:+iron r4«nhwntinq nange one get.nenge. BOLTING TO FLANGE CONNECTION j S•'uW b -Mathq feces f Lid no body to ire machined TO,proper fit. 4. LIFT ROO: AS SPECIFIED BY MFR. WITH HANDLE EXTENDING 70 WTTHW ONE FOOT • O:AYErzA « -Fwn9e mwnting Doha shop be 3/8'diameter.tdn4u at.M. RczimctOA PLATE OF COVER AND ADJUSTABLE HOOK LOCK FASTENED TO FRAME OR UPPER HANOHO D. sen,ORIFICE 1 ... 11 AI:•mo4 e4an t shirr t to the sea g ice (SEE NOT.[9 I w/ qa.s ign 0...on d+ 0-27 ere a 1ae4.Drovided SECTION A-A they moot ha' mot✓c •pa,tion,on.aDow and now o ai.bat.10]/8'bolt Ind.f« - S. GATE SHALL NOT OPEN BEYOND THE CLEAR OPENING OY LIMITED HINGE MOVEME-.NT, baling to the nongo W s ecl4A j`� "••� STOP TAB.OR SOME OTHER DEVICE -- _--- 12 �4mput Mole vital not opM beyond the ey«weninq as elto.n w'Yo'Opening of Gat: 0/� O 6. NEOPRENE RUBBER GASKET REQUIRED BETWEEN RISER MOUNTING FLANGE REMOVABLE dwq.DN05 by I4nllhq ninq.nne-ent. lop tab,or own.other de.io.. t wA7ER-neNT - t AND GATE FLANGE. aUPIP+c ' 7. MATING SURFACES OF ITD AND BODY TO BE MACHINED FUR PROPER FIT. FLAW RESI'RICTOR/OIL POL(.UTION A u ! ' \>a� i` CONTROL TEE TYPE % S. FLANGE MOUNTING :A BOLTS SHALL EE Sj8'DAME TER STAINLESS SILEL. w O OE At �, ,'•) Y `A w ADOPTED O ` O 9. ALTERNATE SHEAR GATES TO THE DESIGN SHOWN ARE ACCEPTABLE. PROVIDED v a IEc•EA5 Dery or ReNTOK :•j�.:' THEY MEET THE MATERIAL SPECIFICATIONS ABOVE. ORTFi SPECIREa Ela,.�._ TAI ----- • STANIMRD PLAINS 0 - F- 8 W ;j MIT DATE:12/26 _PLAN VIEW W �c I U g1 DATE R :1 N _ 8Y_MPR'- DWG. NAME:BR-04 SP PAGE:B029 s � F-0 T SIDS PIVOTING SHEAR GATE DETAIL o. To O ADOPTED 1 n w CITY OF RENTON 4 et 'll a STANDARD PEWS 9 N EST DATE 4/97 0.01 4 97 EBIT NOTE S DCV 0T Z 12 96 REFORMAT TO 11'.17' -I DCV DT� RRS4 AT REVISI N BY _ PR'T DWG. NAME: BR05 SP PAGE:803.3 FRAMES, GRATE,AND ROAD �y 1 'AT SOLID COVERS MARKED INLET PIPE 'DRAIN'WITH LOCKING � 24'0 ACCESS RISER BOLTS, SEE STD OIL IBR29 TYP. 2 PECS) O ,p ' Fu I�� 9999 i m S 1 N 7{ in C4 DETENTION VAULT: 24'WIDE r 62'LONG Tr 4'DEEP(I.D.) VOLUME REQUIRED: 4.380 OF'(INCLUDES 30x SAFETY 28' FACTOR) U. ' u (INSIDE VOLUME PROVIDED: 4.464 CF '^ DIMENSION) BOTTOM OF LID-421.00 W O g @y TOP OF DESIGN WATER«420.50 f0 0 1 i 3 S BOTTOM OF M OFF VAULT- 417.00 407.50 W z m a i Q L{ U Z> b 12 C 1 2'H LOW 6 j Z g�7 6 FREEBOARD 6'OVERFLOW 'CMP ELBOW W p O DEPTH(MIN.) 423.5 /W FZ- z m 0.50'FREEBOARD N- .. - k� ,1_ ,.I,I .� �)yr-ti.-7d S.. �:T, - r .- p LL T W u .ql - 422.Ot; �. L4-g ®r Vie'. 423.0 � W m � .i - 'i 1 . E�(' .. ROCKERY OVERFLOW V=42050 b II2 -- \IF7E0�8IIt9 ORIFICE FICE .d,.. lE+414TOTAL DEPTH 9.25 12 ST O IE.417.50 M IJ.00'LIVE STORAGE b dh 417.00 IE-417 50 99043 SLF 12 ST4 DEAD S IMAGE :x d4��� d TLi T' Y L ,r• t rll;&. ' sy f '.7'� L 5 PIS 0.0050�:: t2'CUP RISER PROJECT NO. MY, 7tii..:L Ifl. m, '3..:L�a.�J' 'IL'a:hl A! .r AN T Ai d SHEAR GATE, �-"`_ I.' 413.50 RECOMMENDED JGC I 8.OIAMETER MIN r .- ,,,y JP FOR APPROVAL DRAWN BY rc IE.415.50t7T �.��.11-11 !1!•`e����iy7,1.1''}'"-I I 62' INSIDE DIMENSION DRfll A J2 lr ry y + y'IT BY: ISSUE DATE HOLE!N A 12 GA.METAL PLATE WELDED TO BY: BOTTOM OF RISER PIPE ,l\ BY. SHEET REVISION CB NO.13(TYPE II-54"7/ CHECKED FOR COMPLIANCE eeaDOTo6Owo TO CITY STANDARDS STORM WATER DETENTION TANK WITH ORIFICE CONTROL Dote ' Z SCALE: 1'- 5' (PWATE) SCALE: I.er 5' Dote " Date PACIFIC ENGINEERING DESIGN INC. o CIVIL ENGINEERING AND 5Z PLANNING CONSULTANTS After recording return to: DECLARATION OF COVENANT IN CONSIDERATION OF the approved King County permit for application No. relating to real property legally described as follows: The undersigned as Grantor(s) , declares that the above described property is hereby subject an easement for a natural or constructed conveyance system and hereby dedicates, covenants and agrees as follows: 1 . King County shall have the right to ingress and egress over those portions not contained in Exhibit "A" to access such easement area for inspec- tion of and to reasonably monitor the system for performance, operational flows, or defects in accordance with and [as presented in King County Code Section 9.04.120] . 2. If King County determines that maintenance or repair work is required to be done to the system, the Manager of the Surface Water Management Division of the Department of Public Works shall give notice of the specific maintenance and/or repair required pursuant to K.C.C. 9.04.030. The Manager shall also set a reasonable time in which such work is to be completed by the Grantor(s) , its heirs, successors or assigns. If the above required D8:Mi16 - 1 - 5b maintenance and/or repair is not completed within the time set by the Manager, the County may perform the required maintenance and/or repair. Written notice will be sent to the Grantor(s) stating the County's intention to perform such maintenance. Maintenance work will not commence until at least seven (7) days after such notice is mailed. If, within the sole discretion of the Surface Water Management Division Manager, there exists an imminent or present danger, said seven (7) day notice period will be waived and maintenance and/or repair work will begin immediately. 3. If at any time King County reasonably determines that any existing retention/detention system creates any of the conditions listed in K.C.C. 9.04.030 and herein incorporated by reference, the Surface Water Management Division Manager may take measures specified therein. 4. The Grantor(s) shall assume all responsibility for the cost of any maintenance and for repairs to the system. Such responsibility shall include reimbursement to the County within thirty (30) days of the receipt of the invoice for any such work performed. Overdue payments will require payment of interest at the current legal rate as liquidated damages. If legal action ensues, the prevailing party is entitled to costs or fees. 5. The Grantor(s) is (are) hereby required to obtain written approval from the Surface Water Management Division Manager of the King County Department of Public Works prior to filling, piping, cutting, or removing veg- etation (except in routine landscape maintenance) in open vegetated drainage facilities (such as swales, channels, ditches, ponds, pond, etc. ) , or perform- ing any alterations or modifications to the drainage facilities contained within said drainage easement. Any notice or consent required to be given or D8:MI16 - 2 - 54 otherwise provided for by the provisions of this Agreement shall be effective upon personal delivery, or three (3) days after mailing by Certified Mail , return receipt requested. 6. This Agreement constitutes the entire agreement between the parties, and supersedes all prior discussions, negotiations, and all agreements whatso- ever whether oral or written. This covenant is intended to protect the value of desirability of the real property described above, and shall insure to the benefit all the citi- zens of King County, and shall be binding on all heirs, successors and assigns. OWNER OWNER STATE OF WASHINGTON ) COUNTY OF KING ) ss. On this date personally appeared before me: , to me known to be the individual (s) described in and who executed the within and foregoing instru- ment and acknowledged that they signed the same as their free and voluntary act and deed, for the uses and purposes therein stated. Given under my hand and official seal this day of , 199 NOTARY PUBLIC in and for the State of Washington, residing at My Commission Expires: D8:MI16 - 3 - 55 IX. MAINTENANCE & OPERATIONS MANUAL PAProject Files\99043\9943 drainage report.doc KING COUNTY, WASHINGTON, SURFACE WATER DESIGN MANUAL APPENDIX A MAINTENANCE STANDARDS FOR PRIVATELY MAINTAINED DRAINAGE FACILITIES NO. 1 - DETENTION PONDS Maintenance Defect Conditions When Maintenance Results Expected When Component Is Needed Maintenance Is Performed General Trash&Debris Any trash and debris which exceed 1 cubic foot Trash and debris cleared from site. per 1,000 square feet(this is about equal to the amount of trash it would take to fill up one standard size office garbage can). In general, there should be no visual evidence of dumping. Poisonous Vegetation Any poisonous or nuisance vegetation which No danger of poisonous vegetation may constitute a hazard to County personnel or where County personnel or the the public. public might normally be. (Coordination with Seattle-King County Health Department) Pollution Oil,gasoline,or other contaminants of one No contaminants present other than gallon or more or any amount found that could: a surface film. (Coordination with 1)cause damage to plant,animal,or marine life; Seattle/King County Health 2)constitute a fire hazard;or 3)be flushed Department) downstream during rain storms. Unmowed Grass/ 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 Mowing of selected higher use ground cover and terrain as long as there is no areas rather than the entire slope interference with the function of the facility. may be acceptable for some situations. Rodent Holes Any evidence of rodent holes if facility is acting Rodents destroyed and dam or as a dam or berm,or any evidence of water berm repaired. (Coordination with piping through dam or berm via rodent holes. Seattle/King County Health Department) Insects When insects such as wasps and hornets Insects destroyed or removed from interfere with maintenance activities. site. Tree Growth Tree growth does not allow maintenance access Trees do not hinder maintenance or interferes with maintenance activity(i.e.,slope activities. Selectively cultivate trees mowing,silt removal,vactoring,or equipment such as alders for firewood. movements). If trees are not interfering with access,leave trees alone. Side Slopes of Pond Erosion Eroded damage over 2 inches deep where Slopes should be stabilized by cause of damage is still present or where there using appropriate erosion control is potential for continued erosion. measure(s);e.g.,rock reinforcement,planting of grass, compaction. Storage Area Sediment Accumulated sediment that exceeds 10%of the Sediment cleaned out to designed designed pond depth. pond shape and depth;pond reseeded if necessary to control erosion. Pond Dikes Settlements Any part of dike which has settled 4 inches lower Dike should be built back to the than the design elevation. design elevation. Emergency Rock Missing Only one layer of rock exists above native soil in Replace rocks to design standards. Overflow/Spillway area five square feet or larger,or any exposure of native soil at the top of out flow path of spillway. Rip-rap on inside slopes need not be replaced. 1998 Surface Water Design Manual 911/98 3 A-1 APPENDIX A MAINTENANCE STANDARDS FOR PRIVATELY MAINTAINED DRAINAGE FACILITIES NO.2- INFILTRATION Maintenance Defect Conditions When Maintenance Results Expected When Component Is Needed Maintenance Is Performed General Trash&Debris See'Ponds'Standard No.1 See'Ponds'Standard No. 1 Poisonous Vegetation See'Ponds'Standard No. 1 See'Ponds'Standard No. 1 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 indicates Sediment is removed and/or facility facility is only working at 90%of its designed is cleaned so that infiltration system capabilities. If two inches or more sediment is works according to design. present,remove. 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%of Clean out sump to design depth. Sediment and Debris depth from sump bottom to bottom of outlet pipe (If Applicable) or obstructing flow into the connector pipe. Filter Bags Filled with Sediment Sediment and debris fill bag more than 1/2 full. Replace filter bag or redesign and Debris system. 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 Pond Erosion See'Ponds'Standard No. 1 See'Ponds'Standard No. 1 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 property 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. 9/1/98 1998 Surface Water Design Manual 5a A-2 APPENDIX A MAINTENANCE STANDARDS FOR PRIVATELY MAINTAINED DRAINAGE FACILITIES NO. 3-CLOSED DETENTION SYSTEMS(PIPES/TANKS) Maintenance Defect Conditions When Maintenance is Needed Results Expected When Component Maintenance is Performed Storage Area Plugged Air Vents One-half of the cross section of a vent is blocked at Vents free of debris and any point with debris and sediment sediment Debris and Accumulated sediment depth exceeds 10%of the All sediment and debris Sediment diameter of the storage area for 1/2 length of storage removed from storage area. vault or any point depth exceeds 15%of diameter. Example:72-inch storage tank would require cleaning when sediment reaches depth of 7 inches for more than 1/2 length of tank. Joints Between Any crack allowing material to be transported into All joint between tank/pipe Tank/Pipe Section facility sections are sealed Tank Pipe Bent Any part of tank/pipe is bent out of shape more than Tank/pipe repaired or replaced Out of Shape 10%of it's design shape to design. Manhole Cover Not in Place Cover is missing or only partially in place.Any open Manhole is closed. manhole requires maintenance. Locking Mechanism cannot be opened by one maintenance Mechanism opens with proper Mechanism Not person with proper tools.Bolts into frame have less tools. Working than 1/2 inch of thread(may not apply to self-locking lids.) Cover Difficult to One maintenance person cannot remove lid after Cover can be removed and Remove applying 80lbs of lift. Intent is to keep cover from reinstalled by one maintenance sealing off access to maintenance. person. Ladder Rungs King County Safety Office and/or maintenance person Ladder meets design standards Unsafe judges that ladder is unsafe due to missing rungs, allows maintenance person safe misalignment,rust,or cracks. access. Catch Basins See"Catch Basins"Standards No.5 See"Catch Basins"Standards No.5 1998 Surface Water Design Manual 9/1/98 5 1 A-3 APPENDIX A MAINTENANCE STANDARDS FOR PRIVATELY MAINTAINED DRAINAGE FACILITIES NO.4- CONTROL STRUCTUREIFLOW RESTRICTOR Maintenance Defect Condition When Maintenance is Needed Results Expected When Component Maintenance is Performed General Trash and Debris Distance between debris build-up and bottom of All trash and debris removed. (Includes Sediment) orifice plate is less than 1-1/2 feet. Structural Damage Structure is not securely attached to manhole wall Structure securely attached to and outlet pipe structure should support at least wall and outlet pipe. 1,000 Ibs of up or down pressure. Structure is not in upright position(allow up to Structure in correct position. 10%from plumb). Connections to outlet pipe are not watertight and Connections to outlet pipe are show signs of rust. water tight;structure repaired or replaced and works as designed. Any holes--other than designed holes—in the Structure has no holes other structure. than designed holes. Cleanout Gate Damaged or Missing Cleanout gate is not watertight or is missing. Gate is watertight and works as designed. Gate cannot be moved up and down by one Gate moves up and down easily maintenance person. and is watertight. Chain leading to gate is missing or damaged. Chain is in place and works as designed. Gate is rusted over 50%of its surface area. Gate is repaired or replaced to meet design standards.. Orifice Plate Damaged or Missing Control device is not working properly due to Plate is in place and works as missing,out of place,or bent orifice plate. designed. Obstructions Any trash,debris,sediment,or vegetation Plate is free of all obstructions blocking the plate. and works as designed. Overflow Pipe Obstructions Any trash or debris blocking(or having the Pipe is free of all obstructions potential of blocking)the overflow pipe. and works as designed. Manhole See"Closed Detention Systems"Standards No.3 See"Closed Detention Systems' Standards No.3 Catch Basin See"Catch Basins"Standards No.5 See'Catch Basins"Standards No.5 9/1/98 1998 Surface Water Design Manual CnU A-a APPENDIX A MAINTENANCE STANDARDS FOR PRIVATELY MAINTAINED DRAINAGE FACILITIES NO. 5-CATCH BASINS Maintenance Defect Conditions When Maintenance is Needed Results Expected When Component Maintenance is performed General Trash&Debris Trash or debris of more than 1/2 cubic foot which is No Trash or debris located (Includes Sediment) located immediately in front of the catch basin immediately in front of catch opening or is blocking capacity of the basin by basin opening. more than 10% Trash or debris(in the basin)that exceeds 1/3 the No trash or debris in the catch depth from the bottom of basin to invert the lowest basin. pipe into or out of the basin. Trash or debris in any inlet or outlet pipe blocking Inlet and outlet pipes free of more than 1/3 of its height. trash or debris. Dead animals or vegetation that could generate No dead animals or vegetation odors that could cause complaints or dangerous present within the catch basin. gases(e.g.,methane). Deposits of garbage exceeding 1 cubic foot in No condition present which volume would attract or support the breeding of insects or rodents. Structure Damage to Comer of frame extends more than 3/4 inch past Frame is even with curb. Frame and/or Top Slab curb face into the street(If applicable). Top slab has holes larger than 2 square inches or Top slab is free of holes and cracks wider than 1/4 inch(intent is to make sure cracks. all material is running into basin). Frame not sitting flush on top slab,i.e.,separation Frame is sitting flush on top of more than 3/4 inch of the frame from the top slab. slab. Cracks in Basin Walls/ Cracks wider than 1/2 inch and longer than 3 feet, Basin replaced or repaired to Bottom any evidence of soil particles entering catch basin design standards. through cracks,or maintenance person judges that structure is unsound. Cracks wider than 1/2 inch and longer than 1 foot No cracks more than 1/4 inch at the joint of any inlet/outlet pipe or any evidence wide at the joint of inlet/outlet of soil particles entering catch basin through pipe. cracks. Sediment/ Basin has settled more than 1 inch or has rotated Basin replaced or repaired to Misalignment more than 2 inches out of alignment. design standards. 1998 Surface Water Design Manual 9/1/98 C.p 1 A-S APPENDIX A MAINTENANCE STANDARDS FOR PRIVATELY MAINTAINED DRAINAGE FACILITIES NO. 5-CATCH BASINS (CONTINUED Maintenance Defect Conditions When Maintenance is Needed Results Expected When Component Maintenance is performed Fire Hazard Presence of chemicals such as natural gas,oil and No flammable chemicals gasoline. present. Vegetation Vegetation growing across and blocking more than No vegetation blocking opening 10%of the basin opening. to basin. Vegetation growing in inlet/outlet pipe joints that is No vegetation or root growth more than six inches tall and less than six inches present. apart. Pollution Nonflammable chemicals of more than 1/2 cubic foot No pollution present other than per three feet of basin length. surface film. Catch Basin Cover Cover Not in Place' Cover is missing or only partially in place.Any open Catch basin cover is closed catch basin requires maintenance. Locking Mechanism Mechanism cannot be opened by on maintenance Mechanism opens with proper Not Working person with proper tools.Bolts into frame have less tools. than 1/2 inch of thread. Cover Difficult to One maintenance person cannot remove lid after Cover can be removed by one Remove applying 80 lbs.of lift;intent is keep cover from maintenance person. sealing off access to maintenance. Ladder Ladder Rungs Ladder is unsafe due to missing rungs,misalignment, Ladder meets design standards Unsafe rust,cracks,or sharp edges. and allows maintenance person safe access. Metal Grates Grate with opening wider than 7/8 inch. Grate opening meets design (If Applicable) standards. Trash and Debris Trash and debris that is blocking more than 20%of Grate free of trash and debris. grate surface. Damaged or Grate missing or broken member(s)of the grate. Grate is in place and meets Missing. design standards. NO. 6 DEBRIS BARRIERS (E.G.,TRASH RACKS) Maintenance Defect Condition When Maintenance is Needed Results Expected When Components Maintenance is Performed. General Trash and Debris Trash or debris that is plugging more than 20%of Barrier clear to receive capacity the openings in the barrier. flow. Metal Damaged/Missing Bars are bent out of shape more than 3 inches. Bars in place with no bends more Bars. than 3/4 inch. Bars are missing or entire barrier missing. Bars in place according to design. Bars are loose and rust is causing 50%deterioration Repair or replace barrier to to any part of barrier. design standards. 9/l/98 1998 Surface Water Design Manual A-6 L. APPENDIX A MAINTENANCE STANDARDS FOR PRIVATELY MAINTAINED DRAINAGE FACILITIES NO. 7- ENERGY DISSIPATERS Maintenance Defect Conditions When Maintenance is Needed Results Expected When Components Maintenance is Performed. External: Rock Pad Missing or Moved Only one layer of rock exists above native soil in Replace rocks to design Rock area five square feet or larger,or any exposure of standards. native soil. Dispersion Trench Pipe Plugged with Accumulated sediment that exceeds 20%of the Pipe cleaned/flushed so that it Sediment design depth. matches design. Not Discharging Visual evidence of water discharging at Trench must be redesigned or Water Properly concentrated points along trench(normal condition rebuilt to standards. is a"sheet flow"of water along trench).Intent is to prevent erosion damage. Perforations Over 1/2 of perforations in pipe are plugged with Clean or replace perforated pipe. Plugged. debris and sediment. Water Flows Out Maintenance person observes water flowing out Facility must be rebuilt or Top of"Distributor" during any storm less than the design storm or its redesigned to standards. Catch Basin. causing or appears likely to cause damage. Receiving Area Water in receiving area is causing or has potential No danger of landslides. Over-Saturated of causing landslide problems. Internal: Manhole/Chamber Worn or Damaged Structure dissipating flow deteriorates to 1/2 or Replace structure to design Post.Baffles,Side original size or any concentrated worn spot standards. of Chamber exceeding one square foot which would make structure unsound. Other Defects See"Catch Basins"Standard No.5 See"Catch Basins"Standard No. 5 1998 Surface Water Design Manual 9/1/98 Co3 A-7 APPENDIX A MAINTENANCE STANDARDS FOR PRIVATELY MAINTAINED DRAINAGE FACILITIES NO. 8- FENCING Maintenance Defect Conditions When Maintenance is Needed Results Expected When Components Maintenance is Performed General Missing or Broken Any defect in the fence that permits easy entry Parts in place to provide adequate Parts to a facility. security. Erosion Erosion more than 4 inches high and 12-18 No opening under the fence that inches wide permitting an opening under a exceeds 4 inches in height. fence. Wire Fences Damaged Parts Post out of plumb more than 6 inches. Post 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 post,top rails,and Fence is aligned and meets design fabric)more than 1 foot out of design alignment. standards. Missing or loose tension wire. Tension wire in place and holding fabric. Missing or loose barbed wire that is sagging Barbed wire in place with less than more than 2-1/2 inches between posts. 3/4 inch sag between post. Extension arm missing,broken,or bent out of Extension arm in place with no shape more than 1 1/2 inches. bends larger than 3/4 inch. Deteriorated Paint or Part or parts that have a rusting or scaling Structurally adequate posts or Protective Coating condition that has affected structural adequacy. parts with a uniform protective coating. Openings in Fabric Openings in fabric are such that an 8-inch- No openings in fabric. diameter ball could fit through. NO. 9-GATES Maintenance Defect Conditions When Maintenance is Needed Results Expected When Component Maintenance is Performed General Damaged or Missing Missing gate or locking devices. Gates and Locking devices in Members place. Broken or missing hinges such that gate cannot Hinges intact and lubed.Gate is be easily opened and closed by a maintenance working freely. person. Gate is out of plumb more than 6 inches and Gate is aligned and vertical. more than 1 foot out of design alignment. Missing stretcher bar,stretcher bands,and ties. Stretcher bar,bands and ties in place. Openings in Fabric See"Fencing"Standard No.8 See"Fencing"Standard No.8 9/l/98 1998 Surface Water Design Manual A-8 �4 APPENDIX A MAINTENANCE STANDARDS FOR PRIVATELY MAINTAINED DRAINAGE FACILITIES NO. 10-CONVEYANCE SYSTEMS(PIPES & DITCHES) Maintenance Defect Conditions When Maintenance is Needed Results Expected When Component Maintenance is Performed Pipes Sediment&Debris Accumulated sediment that exceeds 20%of the Pipe cleaned of all sediment diameter of the pipe. and debris. Vegetation Vegetation that reduces free movement of water All vegetation removed so water through pipes. flows freely through pipes. Damaged Protective coating is damaged;rust is causing Pipe repaired or replaced. more than 50%deterioration to any part of pipe. Any dent that decreases the cross section area of Pipe repaired or replaced. pipe by more than 20%. Open Ditches Trash&Debris Trash and debris exceeds 1 cubic foot per 1,000 Trash and debris cleared from square feet of ditch and slopes. ditches. Sediment Accumulated sediment that exceeds 20%of the Ditch cleaned/flushed of all design depth. sediment and debris so that it matches design. Vegetation Vegetation that reduces free movement of water Water flows freely through through ditches. ditches. Erosion Damage to See"Ponds"Standard No. 1 See"Ponds"Standard No.1 Slopes Rock Lining Out of Maintenance person can see native soil beneath Replace rocks to design Place or Missing(If the rock lining. standards. Applicable). Catch Basins See"Catch Basins:Standard No.5 See"Catch Basins"Standard No.5 Debris Barriers See"Debris Barriers"Standard No.6 See"Debris Barriers"Standard (e.g.,Trash Rack) No.6 NO. 11 -GROUNDS (LANDSCAPING) Maintenance Defect Conditions When Maintenance is Needed Results Expected When Component Maintenance is Performed General Weeds Weeds growing in more than 20%of the landscaped Weeds present in less than 5% (Nonpoisonous) area(trees and shrubs only). of the landscaped area. Safety Hazard Any presence of poison ivy or other poisonous No poisonous vegetation vegetation. present in landscaped area. Trash or Litter Paper,cans,bottles,totaling more than 1 cubic foot Area clear of litter. within a landscaped area(trees and shrubs only)of 1,000 square feet. Trees and Shrubs Damaged Limbs or parts of trees or shrubs that are split or Trees and shrubs with less than broken which affect more than 25%of the total 5%of total foliage with split or foliage of the tree or shrub. broken limbs. Trees or shrubs that have been blown down or Tree or shrub in place free of knocked over. injury. Trees or shrubs which are not adequately supported Tree or shrub in place and or are leaning over,causing exposure of the roots. adequately supported;remove any dead or diseased trees. 1998 Surface Water Design Manual 9/1/98 G5 A-9 APPENDIX A MAINTENANCE STANDARDS FOR PRIVATELY MAINTAINED DRAINAGE FACILITIES NO. 12-ACCESS ROADS/EASEMENTS Maintenance Defect Condition When Maintenance is Needed Results Expected When Component Maintenance is Performed General Trash and Debris Trash and debris exceeds 1 cubic foot per 1,000 Roadway free of debris which square feet i.e.,trash and debris would fill up could damage tires. one standards size garbage can. Blocked Roadway Debris which could damage vehicle tires(glass Roadway free of debris which or metal). could damage tires. Any obstruction which reduces clearance above Roadway overhead clear to 14 feet road surface to less than 14 feet. high. Any obstruction restricting the access to a 10 to Obstruction removed to allow at 12 foot width for a distance of more than 12 feet least a 12 foot access. or any point restricting access to less than a 10 foot width. Road Surface Settlement, Potholes, When any surface defect exceeds 6 inches in Road surface uniformly smooth Mush Spots,Ruts depth and 6 square feet in area.In general,any with no evidence of settlement, surface defect which hinders or prevents potholes,mush spots,or ruts. maintenance access. Vegetation in Road Weeds growing in the road surface that are Road surface free of weeds taller Surface more than 6 inches tall and less than 6 inches than 2 inches. tall and less than 6 inches apart within a 400- square foot area. Modular Grid Build-up of sediment mildly contaminated with Removal of sediment and disposal Pavement petroleum hydrocarbons. in keeping with Health Department recommendations for mildly contaminated soils or catch basin sediments. Shoulders and Erosion Damage Erosion within 1 foot of the roadway more than 8 Shoulder free of erosion and Ditches inches wide and 6 inches deep. matching the surrounding road. Weeds and Brush Weeds and brush exceed 18 inches in height or Weeds and brush cut to 2 inches hinder maintenance access. in height or cleared in such a way as to allow maintenance access. 9/1198 1998 Surface Water Design Manual �� A-10 APPENDIX A MAINTENANCE STANDARDS FOR PRIVATELY MAINTAINED DRAINAGE FACILITIES NO. 13-WATER QUALITY FACILITIES A.) Biofiltration Swale Maintenance Defect Condition When Maintenance is Needed Results Expected When Component Maintenance is Performed Biofiltration swale Sediment Accumulation Sediment depth exceeds 2-inches No sediment deposits on grass on Grass Layer layer of the bio-swale,which would impede filtration of runoff. Vegetation When the grass becomes excessively tall Vegetation is mowed or nuisance (greater than 10-inches);when nuisance weeds vegetation is eradicated,such that and other vegetation starts to take over. flow not impeded.Grass should be mowed to a height between 4 inches and 9 inches. Inlet Outlet Pipe Inlet/outlet pipe clogged with sediment and/or No clogging or blockage in the inlet debris. and outlet piping. Trash and Debris Trash and debris accumulated in the bio-swale. Trash and debris removed from Accumulation bioswale. Erosion/Scouring Where the bio-swale has eroded or scoured Bioswale should be re-graded and the bottom due to flow channelization,or higher re-seeded to specification,to flows. eliminated channeled flow. Overseeded when bare spots are evident. NO. 13-WATER QUALITY FACILITIES (CONTINUED) B.) Grasslined Filter Strips Maintenance Defect Condition When Maintenance is Needed Results Expected When Component Maintenance is Performed Filter Strip Sediment Accumulation Sediment depth exceeds 2 inches. No sediment deposits on grass on Grass Layer layer of the filter strip,which would impede filtration runoff. Vegetation When the grass becomes excessively tall Vegetation is mowed or nuisance (greater than 10-inches);when nuisance weeds vegetation is eradicated,such that and other vegetation starts to take over. flow not impeded.Grass should be mowed to a height between 4 inches and 9 inches. Trash and Debris Trash and debris accumulated on the filter Trash and Debris removed from Accumulation strip. filter. Erosion/Scouring Where the filter strip has eroded or scoured Strip should be re-graded and re- due to flow channelization,or higher flows. seeded specification,to eliminate channeled flow.Overseeded when bare spots are evident. V-Notch Pipe Weir When the V-Notch pipe becomes damaged or Cleaned and properly functioning clogged with sediment/debris. weir,such that flows uniformly spread. 1998 Surface Water Design Manual 9/1/98 C 7 A-11 APPENDIX A MAINTENANCE STANDARDS FOR PRIVATELY MAINTAINED DRAINAGE FACILITIES C.)Wetponds Maintenance Defect Condition When Maintenance is Needed Results Expected When Component Maintenance is Performed Wetpond Vegetation Vegetation such as grass and weeds need to be Vegetation should be mowed to mowed when it starts to impede aesthetics of pond. 4 to 5 inches in height. Trees Mowing is generally required when height exceeds and bushes should be removed 18-inches.Mowed vegetation should be removed where they are interfering with from areas where it could enter the pond,either pond maintenance activities. when the pond level rises,or by rainfall runoff. Trash and Debris Accumulation that exceeds 1 CF per 1000-SF of Trash and debris removed from pond area. pond. Inlet/Outlet Pipe Inlet/Outlet pipe clogged with sediment and/or No clogging or blockage in the debris material. inlet and outlet piping. Sediment Sediment accumulations in pond bottom that Removal of sediment from pond Accumulation in Pond exceeds the depth of sediment zone plus 6-inches, bottom. Bottom usually the first cell. Oil Sheen on Water Prevalent and visible oil sheen. Removal of sediment from pond bottom. Erosion Erosion of the pond's side slopes and/or scouring of Slopes should be stabilized by the pond bottom,that exceeds 6-inches,or where using proper erosion control continued erosion is prevalent. measures,and repair methods. Settlement of Pond Any part of these components that has settled 4- Dike/berm is repaired to Dike/Berm inches or lower than the design elevation,or specifications. inspector determines dike/berm is unsound. Rock Window Rock window is clogged with sediment. Window is free of sediment and debris. Overflow Spillway Rock is missing and soil is exposed at top of Replace rocks to specifications. spillway or outside slope. 9/1/98 1998 Surface Water Design Manual (a A-12 APPENDIX A MAINTENANCE STANDARDS FOR PRIVATELY MAINTAINED DRAINAGE FACILITIES NO. 13-WATER QUALITY FACILITIES(CONTINUED) D.)Vyetvaults Maintenance Defect Condition When Maintenance is Needed Results Expected When Component Maintenance is Performed Wetvault Trash/Debris Trash and debris accumulated in vault,pipe or Trash and debris removed from Accumulation inlet/outlet,(includes floatables and non- vault. floatables). Sediment Accumulation Sediment accumulation in vault bottom that Removal of sediment from vault. in Vault exceeds the depth of the sediment zone plus 6- inches. Damaged Pipes Inlet/outlet piping damaged or broken and in Pipe repaired and/or replaced. need of repair. Access Cover Cover cannot be opened or removed,especially Pipe repaired or replaced to Damaged/Not Working by one person. proper working specifications. Vault Structure Vault:Cracks wider than 1/2-inch and any No cracks wider than 1/4-inch at Damaged evidence of soil particles entering the structure the joint of the inlet/outlet pipe. through the cracks,or maintenance/inspection Vault is determined to be personnel determines that the vault is not structurally sound. structurally sound. Baffles Baffles corroding,cracking,warping and/or Repair or replace baffles to showing signs of failure as determined by specifications. maintenance/inspection staff. Access Ladder Damage Ladder is corroded or deteriorated,not functioning Ladder replaced or repaired to properly,missing rungs,has cracks and/or specifications,and is safe to misaligned. use as determined by inspection personnel. 1998 Surface Water Design Manual 9/1/98 �C) A-13