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Home My WebLink About03372 - Technical Information Report - Addendum � 1ZEEDS�IAW PLAT . n' Renton, Washingfon m m Technical Information Report Addendum Prepared For: �roy Schmeil CALLIDID� DEVELO�ME�VT IIVC. 16838 SE 43�d Street Issaquah, WA 98027 � Phone: (425) 818-8829 Fax: (425) 818-8843 Prepared by: Pacific Engineering Design, LLC. 15445 53RD Avenue S., Seattle, WA 98188 Phone: (206) 431-7970 Fax: (206) 388-1648 ��01�G �, .�� a� w�s�� 5h�; �., j�� s' o , ' �o -� � � ��I4 TER �� `�I��VAL Dg/��Zol Z August 9, 2012 Pacific Engineering Job No. 12007 �,� 3 3 �� , , TABLE OF CONTENTS Narrative of addendum The proposed Reedshaw Plat has been changed from 13 lots to 12 lots. Lot 1 to lot 3 rernains the same. The lot lines of original lot 11 to 13 remains the same. Lot 12 is renamed as lot 10 and lot 13 is renamed as lot 12. Lot 4 and 7 is combined as new lot 4. Lot lines of lot 4 to lot 9 are adjusted to form 4 uniform lots 5, 6, 8 and 9. The original lot 8 is replaced with a larger lot 7. Limited infiltration and porous pavements are used as flow control BMPs. The detention,�wet vault is replaced by a detention pond for Flow control and a StormFilter manhole with 2 ZPG 27"high 11.3 gpm cartridges is used for water quality treatment for the new pollution generating impervious and pervious areas. Structural design of the retaining wall for the detention pond will be included in a separate submittal as building permit requirements. IV. FLOW CONTROL / WATER QUALITY FACILITY ANALYSIS ANDDESIGN.................................................................................................... 3 V. CONVEYANCE SYSTEM ANALYSIS................................................... 14 Reedshaw Plat PED Job number: 12007 � li/ F�OViI CO(VTRO� / 1IV�►TER C��IALII'Y �ACILITY ' AN�►Ll(�I� AND DE�IGN IV.1 HYDRAULIC ANALYSIS The drainage analysis used King County Runoff Time Series (KCRTS) software version 4.2. The on-site soils are (AgC)Alderwood Series KCRTS Soil Group Till. The proposal is located in Sea-Tac rainfall region with a scale factor of 1.0. iV.2 EXiSTIiVG CONDITIONS The Site of the proposed ReedShaw Subdivision encompasses approximately 2.25 acres. Excluding 0.37 acres utility easement, total drainage area is 1.88 acres. Per 2009 KCSWDM, assume 1.88 acres of till forest under existing condition. Total drainage area = 1.88 acres Total impervious area = 0.00 acres Total pervious area = 1.88 acres (till forest) K�_ng County Rurqff Tim2 Series Progran Vers-on 4.42b ------------------------------------------------------------------------------- KCRTS Corunand CREF.TE a new Time Series ------------------------ Frodi:ction of Runoff Iime Series Project Location : Sea-Tac Computing Series : predev.tsf R.e�-ona1 Scale Factor : 1.00 Data Type : Reduced �=eating Hourly Time Series File Loading Time Series File:C:\KC SWDM\KC DATA\STTF60R.rnf 8 Iiil Forest 1.88 acres Scaling Yr: 8 Loading 7ir�e Series F_le:C:�KC SWDM\KC DATP.\STE160R.rnf 8 Inper,.�ious 0.00 acres Adding Yr: 8 -------------- Total Area : 1.88 acres Pea:{ �ischarge: .,.2C4 C,S at 9:.,� cr Jar 9 in Year 8 �toring Time Series File:predev.tsf 8 T-�me S2�-es Computed Existing condition peak flows: Q 2y = 0.052 cfs. Q 10y = 0.091 cfs. 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I � :: ;sta t-n-os. 7 - i<: �� s'c � �`' n'r, � ata e� z�:- , � � � ��7 , J ; o�ns000aa �'�t.� �\ 1� / / p �L . �+� � ;'�N�b� � � � ' lass w� � S' ( j zza•e �� \\ 1 � ��t�a� .; � � i �� 1 acnae-rat�i'_4'�r' �"�° \`�� \ 1 ��ceE c"w+iic:=`'. ,:..; ; �I ;i� ' �w"w'~`4zs:s((i221�fj O�p . �� 1 1 I � __ FNC. / � � 1 WY-�425.43(125) .�:� N L45 S� .� PoY��33.87 WH�42S13�1?N) s4•o -�� _: � l � � cn ��,14 �T`5�'. � wv-snzz�� J ( - \ � l s �vi�K _ � n+wsa.0 I °:��8'° \ \� \r�oo�o � ) ' �` � I c an�r, \ \� \ ,1 � � ! rai+u uaH.w cn� � ur+x�r+ce� irr �\ � \ 1� / �:ic ux.� , ` � Hsim'-z�-os i4��• � `�_--_�\ \ \ J 1'� � N } .. _.._ 1 } pa ;�. .< SrEn� �I a�E � �\ ��+�, ,i r'i°�Ce TP.ACT 'B" l c� �; � m ` � i.�,0_�`�;. r: o.�s's Qo�s \t\ \\ 1 �%/(l 'S_ cns�sn� � �` t8 ,'i � umi.4e� 4�..i � -- : Y!Er' :•t �Y�426.08(iZt1) � I �d E ....23'7' � 223.7_� � tF ,� MV-426.18(72S) . , I_•�� I �_ , I �� /`,r,� ��I . � . �,H ', �xtsT►Nc� c:o�td1`t}oN ScAL� . (" =.60' Q 100y = 0.151 cfs. Flow Fr� ,�2ncv �.ra _ '_- Time Series File:predev.ts` Project Location:Sea-Tac ---Annual Peak Flow Rates-- �-oJ� Fre�-�erc�✓ Anal�,�s=s- Flow Rate Rank Time of Peak - - 2eaks - - Rark neturn crob (CFSj (CFS) Period 0.118 2 2/a9/O1 18:OC 0.151 1 10�.00 0.99� 0.032 7 1/06/02 3:00 0.118 2 25.00 G.°5� 0.088 4 2/28/03 3:OQ 0.091 3 10.00 0.90C 0.0�3 8 3/24/04 20:00 0.�88 4 5.�0 C.8G0 0.052 E 1/05/05 8:�0 0.�77 5 3.00 0.65� 0.091 3 1/18/06 20:�0 0.052 6 2.00 0.5�0 0.077 5 11/24/06 4:00 0.032 7 1.30 0.2�"_ G.=51 1 1/09!OS 9:�0 C.�G3 E 1.1C 0..,._ �o�n�uted Pea:�s ".-4G �O.u� C�.yB� IV.3 DEVELOPED CONDITIONS The ReedShaw Subdivision proposed 12 single-family homes. Impervious area for roadway and sidewalk in Redmond Avenue NE is 0.38 acre. Total lot size of the 12 lots is 1 .27 acres. Flo�nr control �I�IPse 1. Porous asphalt or porous concrete pavements are used for the 12 driveways to each lot. 2. Limited infiltrations are used to handle roof areas from the 12 lots. Onsite soil can be classified as fine sand/loamy sand (SM) according to the geotechnical report. Every 1000 square feet of tributary impervious area requires 75 feet of gravel infiltration trench or 230 cubic feet of dry well.Assume that each lot will has 1750 sf of impervious area (roofs, walkways, driveways, etc.). Impervious areas in the 12 lots will be approximately 12 * 1750 = 21,000 sf. Limited infiltration and permeable pavement (fvr walkway and driveway in each lot)will be used to handle the impervious areas in the 12 lots. After apply the 50% impervious area, 50% grass credit. Total impervious areas in the 12 lots can be counted as 21,000 '` 0.5 /43560 = 0.24 acres. Asphalt pavement for three private access driveways (NE 14th Place, NE 14�n Street and driveway to lot 12 and detention pond) is 6,940 sf = 0.16 acres. Impervious area on top the proposed detention pond is approximately 0.03 acre. Total impervious area will be approximately 0.38 + 0.24 + 0.16 + 0.03 = 0.81 acres. The remaining area is 1.88 — 0.81 = 1.07 acres and is assumed to be till lawn. Total drainage area = 1.88 acres Reedshaw Plat PED Job number: 12007 4 TOTAL DRAINAGE AREA = 1.88 AC. TOTAL IMPERVIOUS AREA = 0.81 AC. r � __ -" TOTAL PERVIOUS AREA = 1.07 AC. (TILL GRASS) _____ _ ---- - -- - - -�� - -------- �G'��- = - ' ��__—�" — — �---- — � � _ — :— j ,__.- - , '- ;� _ _ _---��-� - -_ - , _ -��, - "� / __ - —� _ — — � � __ - ---' ��-i�-`._- - - _ _--_-- -'-- l� - _ ��E'�_.� �t� I , /�-___L - - � " �DMOIm PL!� � '� /_ --- - __�--'��_ _sav. s�on�i �\ i�_ � � ' �� _ ____..,�- __ _ _ _ __ �eoe--,\ 1 �� _ ; . /i sroP scN __..----- , � 55 'X3 � �.�-'- /_ - ___ --- -r'' .�'"__�\� � �'� � j _ �.�-_s � -� -T- 11 _...��._'�--�`'� �-i ----- j-�'_�'__. 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I REQUIRED LIYE � r ,,I � � _ .�`i ;ACG�'SS/llTL '� '� . � r � r � U7L EuMT. �� `. ,,srae�cF=�cF Cf4 / i 1 :� � i � �' � PRONDfD' � � �--� � ; �-�' ^ r,- � - � l N ; � ystauc� s.s2o cFs'Hf�NNYI � �� snNc�� m N � .i � i � , r �i � J J Cj` I I CHAlN�LINK F6aEE ry� p m ��•�p � � ��.I / \� ! Z Z ��V I � AROUND PON�," e,�v _e,'1 p � � "� �� I / � � I I��., i i �, . � d � r . DEVELOPED CONDITION NOTE: SCALE: 1" - 40' LIMITED INFILTRATION IS USED FOR ALL THE 12 LOTS. 75 LF OF GRAVEL INFILTRATION TRENCH OR 230 CF OF DRY WELL IS REQUIRED FOR EVERY 1000 SF OF TRIBUTARY IMPERVIOUS AREA. Total impervious area = 0.81 acres Total pervious area = 1.07 acres (till grass) King Coun`y R�Zrcff Tir�.e Series _rocran Version 6.00 K�RTS Command �..�'aT� a new Time Serie= ------------------------ Pr��ctior. cf R.Lno�f i1T.E Ser'es Proje�t Location : Sea-Tac Computing Series : dev.ts� R�gional Scale Factor : 1.50 Data Type : Reduced �reating Hourly Time Series Fi:e Loading Time S�r'_,._= Fi=e:C:'�.K� S�ti�A�i'�.KC ��A�,,ST�G'c0=.._r.' 8 T_11 Grass 1.07 acres Scal_r.� �'r: � Loading Time Series File:C:\KC SWDhf\KC D�TF.\STE=50R..rnf � =:n�sr-rious 0.81 aCres A�^ ac �r: E -------------- Total Area : 1.88 acres Pe3:�: D_sc'�arg�: .,.52� �FS at F:,,,, on �ar. ? in Y2,r � S�orinc ,i:r:e Series Fi'_e:3e-,�.�sf E' ^_..- ..�__�� T:�uted Developed condition peak flows before detention: Q 2y = 0.271 cfs. Q10y = 0.322 cfs. Q100y = 0.609 cfs. Flow Freq-sency Ar.a1,s-s =ine Series File:dev.ts� Prc-,ect Location:Sea-Tac ---F.nnual Peak Flow Rates--- -----clow Frequency Analys_s------- zlo��; Rate Rank Time of Peak - - Peaks - - Rank Return Prcb (��FS) (CFS) Period C.292 5 2/09/O1 2:00 0.609 1 140.00 0.99� C.222 7 1/05/02 16:00 0.355 2 25.00 0.96C 0.355 2 2/27/03 7:00 0.322 3 10.00 0.90C 0.222 8 8/26/04 2:00 0.308 4 5.00 0.8G0 0.271 6 10/28/04 16:00 �.292 5 3.00 Q.cS? ��.308 4 1/18/06 16:00 0.271 6 2.00 O.��C� �.322 3 10/26/06 0:00 0.222 7 1.30 0.23'_ �.6�9 1 1/09/08 6:Q0 0.222 8 1.10 0.09: ��cputed Peaks 0.52� 5C.CQ 0.98C IV.4 DETENTION ROUTING CALCULATIONS The City of Renton requires that Level 2 Flow Control Standard be applied to this project. This standard requires "maintaining the durations of high flows at their predevelopment levels for all flows greater than one-half of the 2-year peak flow Reedsha«�Plat PED Job number: 12007 5 up to the 50-year peak flow." Also, the pre-developed peak flow rates for the 2-year and 10-year runoff events are also maintained when applying the Level 2 flow control standard. Using the appropriate release rates, the developed time-series were modeled in a pond with 8.5 feet of water depth for live storage and a bottom of 945 square feet. A control structure with three orifices is designed to meet the release rates and frequency duration standards. These calculations have been included. Based on our calculation the volume required to meet the Level 2 Flow Control ', Standard for the site is 19,368 cf(using an 8.5 feet design depth for live storage). ' Available live storage of the pond is 19,520 cf > 19,368 cf. o.k. Re�ention'Deten�ion Fac'_l-�y 'Iy�e ot Facility: �e�ention Ponc I� Side Slope: 1.82 H:1V �� P�nd Bottom Length: 47.00 ft I -ond Bottom Width: 20.00 ft ' Pond Bottom Area: 940. sq. ft ', ^op Area at 1 `t. FB: 4453. sq. ft ' C.102 acres E`-ective Storage Depth: 8.50 ft Staae 0 �'_evation: 0.00 ft ', S�oraae Volume: 19512, cu. ft Q.448 ac-ft =.-ser Head: 5.50 ft Riser Diam.eter: 12.00 inches Pd��-.��er of orifices: 3 Full Head Pipe �rifice # Height Diameter Discharge Diameter (ft) (in) (CFS) (in) 1 �.00 0.63 0.031 2 5.75 1.25 0.070 4.0 3 7.25 0.88 0.023 4.0 ' Top Notch Weir: Nor.e Out�-ioa� �catir.g Cu_ve: Ncre Stac2 E_eva=ior, Storac� Disc�arc= P2rco�_aticr. Surf Ar2a (ft) (_t) (cs. ft) (ac-f�) (cfs) (cfs) (sq. ft) 0.00 0.00 0. 0.000 O.00C Q.O�� 940. 0.01 0.01 9. Q.000 0.001 Q.00 942. ' C.02 0.02 19. 0.000 0.001 0.00 945. C.C3 0.03 28. 0.001 0.002 G.00 957. 0.04 O.C4 38. 0.001 0.002 0.00 950. �.05 �.05 47. 0.001 0.002 O.QO 952. 0.22 0.22 213. 0.005 0.005 0.00 994. 0.39 0.39 385. 0.009 C.007 0.00 1037. 0.55 0.55 555. 0.013 0.008 0.00 1078. 0.72 0.72 742. 0.017 0.009 0.00 1122. 0.89 0.89 936. 0.021 0.010 0.00 1168. 1.05 1.05 1127. 0.026 0.011 0.00 1211. '.22 1.22 1336. 0.031 0.012 0.00 1257. -.39 i.39 1554. 0.036 0.012 0.00 1305. =.55 1.55 1766. 0.041 0.013 0.00 1350. �.72 1.72 2000. 0.046 0.014 a.00 '_399. 1.89 1.�9 2242. 0.051 0.015 0.00 1448. Reedshaw Plat PED Job number: 12007 6 2.05 2.G5 2478. 0.057 G.Oi5 C.00 149c. 2.22 2.22 2736. 0.063 0.016 0.00 1547. 2.39 2.39 3003. 0.069 O.C16 Q.00 1599. 2.55 2.55 3263. 0.075 0.017 0.00 1648. 2.72 2.72 3548. 0.081 0.017 0.00 1701. 2.89 2.89 3842. 0.088 0.018 0.00 1755. 3.05 3.05 4127. 0.055 0.�19 0.40 i807. 3.22 3.22 4439. O.lQ2 0.019 G.00 1863. 3.39 3.39 4760. Q.109 0.019 0.00 1919. 3.55 3.55 5071. G.116 0.020 �.00 1973. 3.72 3.72 5412. 0.124 0.020 0.00 2031. 3.89 3.89 5762. 0.132 C.021 0.00 2039. 4.05 4.a5 6101. �.14C 0.021 0.0a 2145. 4.22 4.22 6470. �.149 Q.022 0.00 2205. 4.39 4.39 6850. 0.'_57 a.022 O.00 2266. 4.55 4.55 7218. 0.166 0.023 0.0a 2324. 4.72 4.72 7618. 0.175 0.023 0.0a 2386. 4.89 4.89 8029. 0.184 O.Q23 0.00 2449. 5.a5 5.05 842E. 0.193 0.a24 0.00 2509. 5.22 5.22 8858. 0.203 0.024 0.0� 2574. � 5.39 5.39 9301. 0.214 0.025 0.00 2639. 5.55 5.55 9728. 0.223 0.025 0.00 2702. 5.72 5.72 10193. Q.234 0.025 0.00 2768. 5.75 5.75 10276. a.236 0.025 0.00 2780. 5.76 5.76 10304. 0.237 0.026 0.00 2784. 5.78 5.78 10360. d.238 0.027 0.00 2792. 5.79 5.79 10388. 0.238 0.028 0.00 2796. 5.80 5.80 10916. 0.239 a.031 0.00 2800. 5.82 �.82 10472. 0.24C 0.034 0.00 2808. 5.83 5.83 10500. 0.241 0.037 0.00 2812. 5.84 5.84 1a528. �.242 0.038 0.00 2816. 5.85 5.85 1a556. 0.242 �.039 0.00 2820. 6.02 6.02 11041. 0.253 0.048 O.00 2888. 6.19 6.19 11538. 0.265 0.054 0.00 2957. 6.35 6.35 12017. 0.276 0.060 0.00 3023. 6.52 6.52 12537. 0.288 0.064 0.0� 3093. 6.69 6.69 13069. 0.3C0 0.068 Q.00 3165. ; 6.85 6.85 13580. 0.312 0.072 0.00 3232. �, 7.02 7.02 14136. 0.325 0.076 0.00 3305. ', 7.19 7.19 14704. 0.338 0.079 0.00 3378. � 7.25 7.2� 14908. 0.342 0.080 0.00 3405. 7.26 7.26 14942. 0.343 0.081 0.00 3409. 7.27 �.27 14976. 0.344 0.081 0.00 3413. 7.28 7.28 15010. 0.345 0.082 0.�0 3418. 7.29 7.29 15044. 0.345 0.084 0.00 3422. 7.30 7.30 15078. 0.346 0.086 O.Oa 3426. 7.31 7.31 15113. 0.347 0.087 0.0a 3431. 7.32 7.32 15147. 0.348 0.087 0.00 3435. 7.49 7.49 15737. G.361 0.�95 0.00 3510. 7.66 7.6E 16340. 0.375 0.101 0.40 3585. 7.82 7.82 16920. 0.388 0.106 0.00 3657. 7.99 7.99 17548. 0.403 �.111 0.00 3734. 8.16 fi.16 18190. 0.418 Q.116 0.00 3812. 8.32 8.32 18805. 0.432 0.120 0.00 388c. 8.49 8.49 19473. 0.447 0.124 0.00 3965. 8.50 8.50 19512. C.4S8 0.124 0.00 397C. 8.60 8.60 19912. a.457 0.435 0.00 401�. 8.70 8.70 24316. 0.466 1.000 0.00 400�. 8.80 8.80 20725. 0.476 1.730 O.OQ 4112. 8.90 8.90 21138. 0.485 2.530 O.OG 4160. 9.00 9.00 21557. 0.495 2.810 0.0� 4208. 9.10 9.i0 21980. 0.505 3.070 0.00 4257. Reedshaw Plat PED Job number: 12007 7 9.20 9.20 22408. 0.514 3.300 �.00 4305. 9.30 9.30 22841. 0.524 3.520 0.00 4354. 9.40 9.40 23279. 0.534 3.730 O.QO 4403. 9.50 9.50 23722. 0.545 3.930 0.00 4453. 9.60 9.60 24169. 0.555 4.110 0.00 4502. 9.70 9.70 24622. 0.565 4.290 0.00 4552. ' 9.80 9.80 25080. 0.576 4.46G 0.00 4603. 9.90 9.90 25543. 0.586 4.630 0.00 4653. 10.00 10.00 26011. 0.597 4.790 0.00 4704. 10.10 i0.10 26483. 0.608 4.94G 0.00 4755. 10.20 i0.20 26961. 0.619 5.090 O.QO 4806. 1�.30 �0.30 27445. 0.630 5.230 0.00 4858. Hyd Inflow Outflow Peak Storage Target Calc Stage Elev (Cu-Ft) (Ac-Ft) 1 0.61 0.15 0.12 8.�6 8.46 19368. G.445 2 p.2g ******* 0.11 7.83 7.83 16959. 0.389 3 0.29 0.09 0.08 7.07 7.07 14300. a.328 4 0.35 ******* 0.08 7.05 7.05 14226. 0.327 5 0.31 ******* 0.06 6.41 6.41 12192. 0.280 6 0.18 Q.05 0.04 5.87 5.87 1�622. 0.244 7 0.22 ******* 0.02 5.18 5.18 8744. Q.201 8 0.22 ******* 0.02 3.52 3.52 5005. Q.115 ---------------------------------- Route Time Series through Facility Inflow Time Series File:dev.tsf O��tflow Time Series File:rdo•st2 ' Inflow/Outflow Anaiysis Peak Inflow Discharge: 0.609 CrS at 6:OC on Jar. 9 in Year 8 Peak Outflow Discharge: 0.123 CFS at 13:00 on Jan 9 in Year 8 Peak Reservoir Stage: 8.46 Ft Peak Reservoir Elev: 8.46 Ft Peak Reservoir Stor�ge: 19368. Cu-Ft . 0.445 P.c-F� Flow Freqaency Analysis Time Series File:rdout2.tsf � Project Location:Sea-Tac � ---Annual Peak _1o�r Rates--- -----Flow Frequency Ar:a�ys�_s------- F1ow Rate Rank Time of Peak - - Peaks - - Rar.k Return Pro� (CFS) (CFS) (ft) Period 0.106 2 2/09/O1 21:00 C.123 8.46 1 100.00 0.990 II 0.024 7 12/29/O1 11:OC 0.106 7.83 2 25.00 0.96C �I 0.076 4 3/06/03 22:00 0.077 7.07 3 10.00 0.90� I Q.02� 8 8/26/04 7:00 0.076 7.05 4 5.60 0.80� O.OS� 6 1/68/�5 1:00 0.061 6.41 5 3.�0 0.6E� lil 0.061 5 1/19/�6 2:00 �.040 5.87 6 2.00 0.50� I 0.077 3 11/24/�6 9:00 �.a24 5.1fi 7 1.30 0.23i I 0.123 1 1/09/08 13:00 �.020 3.52 8 1.10 0.091 I� Computed Peaks 0.118 8.23 �O.QO 0.980 , Flow Duration from Time Series File:rdout2.ts` I, Cutoff Count Freauer.cy CDF Exceedence_Probabi�ity �I CFS � a $ 0.002 35979 58.674 58.674 41.326 0.413E+G0 0.005 5090 8.301 66.975 33.025 0.33�E-G�� 0.008 3841 6.264 73.239 26.761 0.268E-GO 0.011 4240 6.915 80.153 19.847 0.198E-G0 0.013 3867 6.300 86.46G 13.540 0.135�+G� Reedshaw Plat PED Job number: 12007 8 0.016 3053 4.979 91.438 8.562 0.856E-01 0.019 1979 3.227 94.666 5.334 0.533E-01 �.022 14Q5 2.291 96.957 3.043 0.304E-Oi 0.025 1401 2.285 95.242 6.758 0.758E-02 0.028 54 0.088 99.330 0.670 0.670E-02 0.031 13 0.021 99.351 0.649 Q.649E-02 �.034 32 0.052 99.403 0.597 0.597E-02 G.037 16 0.026 99.429 0.571 0.571E-02 ��.04� 34 0.055 99.485 0.515 0.515E-02 �.043 27 0.044 99.529 0.471 0.471E-02 0.046 22 0.036 99.565 0.435 0.435E-D2 O.C49 30 0.049 99.614 0.38E 0.386E-02 0.052 22 0.036 99.649 0.351 0.351E-02 0.055 23 0.038 99.687 0.313 0.313E-02 G.058 14 0.023 99.710 0.290 0.290E-02 G.061 22 0.036 99.746 0.254 0.254E-02 Q.064 37 0.060 99.806 0.194 0.194E-�2 G.067 25 0.641 99.847 0.153 0.153E-02 �.070 10 0.016 99.863 0.137 C.137E-02 �.073 16 0.026 99.889 0.111 0.111E-02 �.076 15 0.024 99.914 0.086 0.864E-03 �.Q79 18 0.029 99.943 0.057 0.571E-03 �.G82 6 0.010 99.953 0.047 0.473E-03 �.G85 0 0.000 99.953 0.447 0.473E-03 O.G88 3 0.0a5 99.958 0.042 0.424E-03 0.091 6 0.010 99.967 0.033 0.326E-03 0.093 4 0.007 99.974 0.026 0.261E-03 0.096 2 0.003 99.977 0.023 0.228E-03 0,099 3 0.005 99.982 0.018 0.179E-03 G.1�2 4 �.007 99.989 0.011 0.114E-03 G.105 4 O.Q07 99.995 Q.005 0.489E-Q4 ��r=_tion Comparison Anaylsis Base File: predev.tsf tdew File: rdou`�2.tsf �•a�o'f U�:its: Discharge in CFS -----Fraction of Time----- ---------Check of Tolerance------- �L�c_� Base New $Char.ge Probability Base New °�Change �.C26 I 0.94E-02 0.74E-02 -21.4 I 0.94E-02 0.�26 0.025 -3.6 G.033 I 0.63E-G2 0.62E-02 -1.6 ', 0.63E-02 0.033 0.032 -2.3 �.CaO I 0.50E-02 0.52E-02 3.9 I 0.50E-02 O.G40 0.042 3.5 �.047 I 0.37E-02 0.42E-02 12.3 I 0.37E-02 O.G47 0.050 5.4 � .C54 I 0.28E-G2 0.32E-02 12.6 I 0.28E-02 0.054 0.058 7.5 �.062 I 0.22E-Q2 0.24E-02 8.1 I 0.22E-02 0.062 0.063 1.8 �.a69 i 0.15E-G2 0.14E-02 -3.3 I 0.15E-02 0.�69 0.068 -0.8 �.a76 I O.10E-02 0.86E-03 -14.5 I O.10E-02 0.076 0.074 -2.5 �.083 I 0.62E-03 0.47E-03 -23.7 I 0.62E-03 0.083 0.078 -6.4 �.090 I 0.34E-03 0.33E-03 -4.& I 0.34E-03 0.090 0.090 -0.2 �.097 I 0.23E-03 0.21E-03 -7.1 I 0.23E-03 0.097 0.097 -0.5 �.104 i 0.16E-03 0.98E-04 -40.0 I 0.16E-03 0.104 D.101 -3.2 ' �.111 i 0.11E-43 O.00E+00 -100.0 � 0.11E-03 C.111 0.103 -�.2 ' �.118 I 0.16E-04 O.00E+00 -100.0 � 0.16E-0� C.1=� Q.iG6 -1C.2 ':ax_m;,�m positive excursion = 0.003 cfs ( 7.7%) �c�urring at 0.043 c`s on the Base Data:predev.tsf a-d at �.047 cfs on tne New Data:rdout2.tsf Maximum negative excursion = 0.004 cfs (-1�.4�) occurring at 0.029 cfs on the Base Data:predev.�sf and at 0.025 cfs on the New Data:rdout2.tsf Developed condition peak detention pond release rates: Reedshaw Plat PED Job number: 12007 9 Q 2y = 0.040 cfs. < 0.052 cfs (Ex. 2 year peak) o.k. Q10y = 0.077 cfs. < 0.091 cfs (Ex. 10 year peak) o.k. Q100y = 0.123 cfs. < 0.151 cfs (Ex. 100 year peak) o.k. The 100 year 15 minute developed peak flow: Q100y-15min = 1.47 cfs King �oLnty :�incfi Tirce Ser�_es Pr�gra:n Version 6.00 KCRTS Command CREe:�E a new Time Series ------------------------ =_oduction of Runoff iime Series Froject L�ca�ior : Sea-Tac CoR.putir.g Series : dev.tsf F.e�ional Scale Factor : 1.00 Data Type : Reduced �reating 15 Minute Time Series File Loading ^_itr:e Series File:C:\KC SWDM.\KC DATA\S^tTG60R.rnf 8 =i11 Grass 1.07 acres Scaling Yr: 8 Loading Time Series File:C:\KC SWDM\KC DATA\STE160R.rnf 8 =rr.�er-•,�iou= 0.81 acres Adding Yr: 8 -------------- �otal Area : 1.8fi acres _�ai: �i=c'r.arge: 1.�7 CFS a; 6:OC cn Jan 9 in Year 8 Storing Time Series File:dev-15.tsf 8 "-��r.2 Series �omouted F1ow Frequency Analysis Tirie Series File:dev-15.tsf P=oject Locatior.:Sea-Tac ---Annual Peak Flow Rates--- -----F1ow Frequency Analysis------- Flow Rate Rank Time of Peak - - Peaks - - Rank Return Prob (CFS) (CFS) Period 0.386 6 8/27/O1 18:40 1.54 1 100.00 0.990 G.304 8 1/05/02 15:C0 0.9E4 2 25.40 0.960 0.964 2 12/OS/02 17:'5 0.666 3 1�.00 0.9�0 0.311 7 8/26/04 0:45 0.558 � 5.00 0.800 �.066 3 11/17/09 5:00 0.502 5 3.00 0.667 �.502 5 10/27/05 10:45 0.386 6 2.00 0.500 G.558 4 10/25/06 22:45 0.311 7 1.30 0.231 ' 1.50 1 1/09/OH 6:30 0.304 8 1.10 6.091 �o:np�s`ed Peaks 1.32 50.00 0.980 Primary overflow: The 12° riser in the flow control structure provides the primary overtlow I At head = 0.3' over the riser over flow elevation �� Reedshaw Plat PED Job number: 12007 I 10 I Qweir = 9.739 * D * H ** (312} = 9.739 * 1 * 0.3 ** 1.5 = 1.60 cfs > 1.50 cfs o.k. The 12" riser has the capacity to handle the 100 year 15 minute developed peak. Sec�roclary inle# #o the controB �#ruc#ure: Secondary inlet to the control structure is provided by a grated opening {"jailhouse windown) in the control structure. Q = C * (L - 0.2 *H) * H ** (3/2) L = Q / (C * H ** 1.5) + 0.2 * H = 1.50 / (3.284 * 0.3 ** 1.5) + 0.2 * 0.3 = 2.84' Assume H = 0.3' P = 8.5' C = 3.27 + 0.4 * H /F' = 3.27 + 0.4 * 0.3 / 8.5 = 3.284 Use 3' long x minimum 6" high grated opening. Emergency overflow path: Rectangular emergency overFlow weir: The pond has a rectangular emergency overflow weir at the concrete retaining wall. Assume H = 0.2' Required length of the weir: L = Q100/(3.21 * H ^ 1.5) = 1.50 / (3.21 * 0.2 ^ 1.5) = 5.22' < 6' UseL = 6' A 6' long weir will be used. Rip rap swale: A rip rap swale will be installed from the emergency overflow weir to the back of the sidewalk along Sunset Boulevard. A catch basin located at the end of the rip rap swale will pick up the overflow runoff and conveys it to the drainage system along Sunset Boulevard. The proposed rip rap swale has a cross section of bottom width 1', top width 5', side slopes 2:1, and rock depth 2'. Longitudinal slope of the rip rap swale is approximately 13%, capacity of the swale with 0.3' water depth is: Q = 1.49 * A * R ** (2/3) *SQRT(S) / n A = wetarea = 1 * 0.3 + 2 * 0.3 * 0.3 = 0.48sf. R = Hydrulic radius = wet area/wet perimeter = 0.48/(1+ 2 * 0.3 * SQRT (1 + 2 *2)) = 0.20ft. N = manning's coefficient = 0.04 Q = 1.49 * 0.48 * 0.2 ** (213) * SQRT(0.13)10.04 = 2.24cfs > 1.50cfso.k. Rip rap shall be reasonably well graded with gradation as follows: Maximum stone size: 24 inches (nominal diameter) Median stone size: 16 inches Minimum stone size: 4 inches Reedshaw Plat PED Job number: 12007 11 � N O � �%f I�IJI O o - R, o �. � `a ro o -�-�� V `�� a � rn 4 N � V �- � �. � ! � �1, ,r N _ O O O I "0 5 � I 10 � iC 3 10 � 10 ' 10° Protability 6cce=GerKe � Figure 1 Flow durations chart F•,Lr�P9nCC x xi � aa, ioo m • V � � < � � • r � r i i . . . IO 70 .'J Y .. r,�; M . si 5S 9B '.7 ., a_. .•X.�N Figure 2 Peak flows chart Reedsha�� Plat PED Job number: 12007 12 I _ � 0 N � 6Z �O bl 133F-PS alod ' '�H e�oa rJ�J�JcJ-tiZti-OUB-� �'�" �� `xH aaoa �Ia f10A 3a0�38 �� Mo�a�ito.t�N3�r�w3 �vnoxaav uoa saavar�vis ui� ol Sbf10H 8ti llt/� m av,a�+�a-nnrn-wiaeo90 Q�QN3AI➢[O��I 3JNVIldWO� 210j 43WJ3H� � 4 1�tZL��—!1 ��,,, �,�� 9 � 81N A �i �Q-�N�LL�3S'� aNOd/1��uN3L�a � � � � 00'Olt-77YM!0 o1D1 �au�a8 QrV 9 �� rvor.�.�".�.'� avod n�oc�N�a � Nv�d allod �,- �. os•aor=n�a�x � NOLLN3L� i 11'l l�-I�I I�L I�I�I�I� �- i '11-11 II�lF��' I�I�I II��I�� _;F i _�I��i-�� Ir ��II�I-I��i ll If1�- � � �I�III ,I� I ��J I i��l�ll- li_ �`1I..� �'�-��R IC I I I� �I�II `IH I II' III� 1�1�' r� i d a s (r�l-� I I�I��I I �� u l_� �I ��-L��I I ��I-��f_��1 i� �� I=I '-��l i-��1 1�!I I zWt/eo/90 ��naa i33Hs -III I�ii-�ii �I I�j�l �!I-1 i��l-1= I ��1� 1�1 'II I�I 1-I11� �I� � I '-I I� r. ,�1F11) � i�-II� I i i I�I ' �i� I�� I-i I-I� I I_I I I-�i�I _ 1 �'��I I-�i �-�I q L�I L I' I I- 90/s;p/'L A �va 3nssi - 1-I � I�I�I�_I I �_ �I��I II� - I i_� ��I�� I 1�-1�- I I i �I I I I I�I I�I I I�li--i l�� ,� �_ - - � � , � � �� II�!'�II I � �I I� I I ��1�11=1�� ,J� - ��--,HIE � � a : ��I 1=� �i-�'F �_,,_ � � � � -i'__T i i �-� i �i._- � I�`�JI ��- c� r 9f`O/til.L Ae wnvaa �ir�l I��I�L'-,I�i II�� II I I -1�11��I " � I�ICI � �1 I� _�'I� � �= I-I 1��.�11-,IE �I ��- ��i�l i � LOOZ� �'oH i�3road ��I I I��H I�- I�;-11k�1�-i � II -f-1-I � I��II�I�I� � � � J I� I I II�II- � ��I� I_I�� ~�Ipl �I I��r__ � � �1� � I�'�11�1�-+ =i '�I-II��I�IGII��I IP ,_ L�1�11��F��TF�� I-I I�� I-I I b��I-�I I- I r �I I _ I I I I f-�I=�IJ I 'I1-�' I I-i I� � I 1-1� r �raols�n,sB '�Il� ��ll�ll�il�l�l�il-. � � �x "' I�-_ �f I ,� � �I�I-'_ I �1�I�iir-�.. � � �'mo,o� LI�I,��I-1,-l�l I�il_FL1�- I_I I I! !�I_I��Ir�'- �vao�s3nrt.sB ,II-��- i m m a o � �--I�� i i r�n-i �i-�! i =�i �i i- �� -I�!_I I I I I��i_I I� I I�,=��,J I_-' �� an� $ � � g>mr� � ��I�-:�,_. �II�'I I�i li-ii_�' ' 13BWf18�1 Q g � ��- ` i I_I-I I�I II_if-I'i 1=11�1' � � s � � � 0 .t-.t �I I I �I-I!I II�� IE�,.1�' �,i A S m r�n m .s'! + I I I I-I:-111�1 I l- I�I 11=' � .S c� m � .U.`2a� � ��—I�T��I��'��- � p � � OSBor=sx tuool f ��I I I-�I_ � I� m c m� (n �'q �I��I� os'aor=5M aaooi , m r I f�11-�-I�_I 1- ` M/a mo�p = oo•oir-nvM�o do1 ��; D ��o��-,rM� � � � � �,, 'swePue�s yMdVIlOoSM Bugaaw dW��aa{s paz�uwnle�dW�wnu�wn�e p peprtqsua�a9 p��l '8 d' T D '�i�4l!M P�114 s�uieeq y�e�uayi,�ssa�e�nollg � Z X n ap spnen pue�uq oy ssanx se pasn sairy�nqs u�sBuru�eDDel I�qJ!PPe Bl�ol 'B ��Sk � � A � 'uMals se a�ueiea��wnwiuµi ap�naM ol,iiessa�au se(SLoI�!+�MWI�el�l 'L I � � ' �.� � � � I \ 1� fTl ro � (dx�eds I�!Si�.O-£wnwaew) / I i � `� 1 � � � m � �le�n alanum W Dao4aie Iwpe�9 liodd�w eBeB O80'X.E�Ke�l le eP!wrd '9 / i ' 1 �I Q .� l �� ,� \ 1 S'9 L�=a b'd � i �. � m •.{�a�i��a i��a•o i � 1/'YS3 � Y Q � ,% .1 " � 1 '� � ,� „ S1N w�«�8�„ea��w�:�� `{ %� ; ), 1 \ t Zi� � \ � � � M31A N�ld d w�o��wiub w�„� �s �L(1 SS��b' ' �' i - -----------_ �a .4an�o�ean s�awei� .� 1/ �� 1� v j � —�� 3�N3!1�IN�7l�IdFPT F�Y---`--- —�\\ D EE �; -a�euw�� -i----� ' � `� 2 s• � �,��,�o,�:��a-aweo�a 1 i , i -- �- _ I �\ ; La � ,�a aoi Wo,��a!�,,s��ea��e�y (3� ds rt3do) � i , 1 �� ,0� _ .l 3lt+�S�. � / viw,Z le�ap aas :as�asgo sdais io�appe�l l�e�� y /� g r.�� 11// 1 � � OS"B06=�j21l15 2131 dM 21d3A 00! � �� mOL'66E=Mll L a�ou aas \ 10�a''A0v° p e y d se a n e y o�s y�e d edW p a z iu e rye� SZ'�OY�ANI MOBI3.4 � 1 � 5L��NI�- 1 �-I� 0� g � / ,Oes�au 3dOldl , , /I Pl'�1{f= � --------\ -------- \ E se a 'P�Yad sUed paauenR'J�N i .SLB'4=VI�3�LiW0 Q2K' I { BJ 1 a 7�sv��R�d Ie7aW 'f �SL'SOf�1 N1 MO \\� y \�� I �'ti � \ t - -�y,---------- � 0 1 ,c ��u�a sz�irrb�c�rao oNz �,- -�'- - � _ Z I � P�N�P�A�OL ��lalY�O 'Z OQiB6�'=73 / �OY � _ I �O. 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'^ — — _vo�0o� . p � �`------ �- 0 � �m 4�f4.9 z�+q�£ '�..91 Wawe�d 8Hl17 NllS7X3 .. 1 �-� �' --�_��_ � � uw, 1S � 00(n ££'Ol4-ryR! �Pm'I L .Ll 7�— � �� _ D , �� ao: szo-z'zzo-z�P sue�d�ad uope�e � — 1S,8! X3 �� '-��__ SaON 4 6 a�ou aas 'aw,z — � � — 1 0 - -�_ Eu ' -� �aa a�a�iPaagv� a�meuya� Q^79 � —s� � ` n v UZo zt � �ysisY;°js w°°�e'"a�ye�a"°' � —'�KIS�V ,'1 �J � — � � � � '^ � i � sta o sz'mr .r ��iao aae ' - - SL": SL'406 ./ 3�L�R10ONZ � � ' � 2i3.13N1H10 �MlIM0913 M313WM0 � � � �o ti 3�IjldO MOBl3 � /3 �11� d� 'IN'M `l�br� 5 �JNb'i� `H1b10N EZ �IHSNMO� `� NOI�� `1�/t �'� `�/L '�'� 3H1 �O N011�1Od � + N m 3,2.2 KCRTS/RUNOFF FILES METAOD—GENERATING TIME SERIES _- ,_.. - TABLE 33.2.B EQUIVt�,ENCE BETWEEN SCS SOIL TYPES A1VD KCRTS SOIL TYPES SCS Soil Type SCS 6(CRTS Soi9 Notes �oNS��G SO�L Hydrologic Group Soil Group Alderwood (Ag6, gC AgD) C Til! Arents,Alderwood Materiai(AmB,AmC) C Till ; Arents, Everett Material (An) B Outwash 1 Beausite(BeC, BeD, BeF) C Till 2 Bellingham (Bh) D Till 3 Briscot(Br) D Till 3 Buckley(Bu) D Till 4 Earlmont (Ea) D Tiil 3 Edgewick(Ed) C Till 3 Everett (Ev6, EvC, EvD, EwC) A/B Outwash 1 Indianola (1nC, InA, InD) A Oufwash 1 Kitsap(Kp6, KpC, KpD) C Till Klaus (KsC) C Outwash 1 Neilfon (NeC) A Outwash 1 Newberg (Ng) B Till 3 Nooksack(Nk) C Till 3 Norma (No) D Till 3 Orcas (Or) D Wetland Oridia(Os) D Till 3 Ovall (OvC, OvD, OvF) C Till 2 Pilchuck(Pc) C Till 3 ' Puget(Pu) D Till 3 Puyallup(Py) B Till 3 Ragnar(RaC, RaD, RaC, RaE) B Outwash 1 Renton (Re) D Till 3 Salal (Sa) C Till 3 Sammamish (Sh) D Till 3 ' Seattle (Sk) D Wetland ! Shatcar(Sm) D Till 3 I Si(Sn) C Till 3 ' Snohomish (So, Sr) D Till 3 Sultan(Su) C Till 3 ', Tukwila (Tu) D Till 3 ' Woodinville (Wo) D Till 3 ' Notes: 1. Where�utwash soils are saturated or underlain at shallow depth(<5 feet)by glacial till, they should I be treated as till soifs. I 2. These are bedrock soils, but calibration of HSPF by King County DNRP shows bedrock soils to have similar hydrologic response to till soils. 3. These are alluvial soils,some of which are underlain by glacial till or have a seasonally high wafer table. In the absence of detailed study,fhese soils should be treated as till soils. 4. Buckley soils are formed on the low-permeabifity Osceola mudflow. Hydrologic response is assumed to be similar to that of till soils. 2Q09 Surface Water Design Manual 1/9/2009 3-25 SECTION 3.2 RUNOFF COMPUTATION AND ANALYSIS METHODS FIGURE 3.2.2.A RAINFALL REGIONS AND REGIONAL SCALE FACTORS ST '9.0/ ST 1.0 �q p,g LA 0.9 �-p► �•� LA 'f.2 ST1�� ' - � SNONONISNCOIINTY = r�i� : u'�icd`' �'"a f �oori�na - r RFsj•r ��,-'��l �� t . �n -XING C011N7Y �� u _ � � _ ' ��f � .. r ` �,' = - i .� �' � 1,� ;�� _ �� _ _ � � �:�" - � � , - - � � > - - -EJ f r�°ro�° � � �. � - '� ��' f � t 1 - R14u� � ' "� " �. �J - f,/.t` RE .OND�. "�� r -- _ ' � - : f ! = - ` ! ' ��° _ ,� � �� . . ;' � , `,fi - �"l. �. _ - - � _ _t,� w � . 1^ - V� Y { _ _ ,{ .£�u.J _ __ � .`^� � _ _ A y.__ EO _.�- . _ -- .•E LE UE . �� . Ei�oR-:- � � I. Q� - _ - Ery-: - �� ° -rme��' a_, . ,= _' : :' . ,- __ ' u tu�� '/�., - i . : . '. � - MERCE0. � S4=� �/ - __ - _ fL�MG ��"'� _� � -`` . P _- " " ._�, � � i0%L _ :`� - �' `; � ro��_ - � `-,. "s �E- � • ' - t P;�,a d, �,�� - xflrc 'te�-.� I n r a � ` r__� _ _� u . � �� rowr � \ aou _ ` � i � � - u � � .t . wrrn�� 0 - �xFa�wv 'f_ . x _ _ _ .F ENTO - �e o� �� _ # , .�s i p �" �'i.�1 _ -_ e mtw r �1�N�� ' ' Q . �� . -� � �/�� awowt��_ � � � I - i + � : 1' Y_\ _. . _ �1A'R�RY Y "S 7ACi .! � i �Y - K£PH.IOH .' � '' - = ' r�=� ` ; Q �, LANDSBURG ', _ ,h.1w� _ '`L-: 4 �A�JE . . . �,�0 , �.i � - _ - � � � .. � N.= / - - Y. IIFNf:� Q - � ' a _ .. '. - '- % `�� - - ... �, - ' - _ -� - `! ` ! . � . - '.�.� - � � -. _ = P4aLT- - � ! � '.�i IAFD:OUPG _ _ - Soond _- Q� _ /:�..'{ . .,� - KEx11 . _ _ _ _ �J.'1 �_ ��f�—��, f_ . �� ' r. - " '�'Je � r 1'� � `� 7 � ; .�.�,�' D �.a �x I � ouu xo sr �.� ��.� ��a �' � - i _�`` '!� ��: A ,, �_ �� _.� . . �' �•� ,%IiuGo'cduxir� .. �� . �O .. VIERCE COUNTi� � � � . - ST 1 A � � euucu• � . � Rainfali Regions and �ao.$f ~� � Regional Scale Factors �a o.s L.-=a Incorporated Area LA 1.0 LA 1.2 ._.c.� River/Lake Major Road 1/9/2009 2009 Surface Water Desib Manual 3-22 SECTION C.2 FLOW CONTROL BMPs C.2.3.5 MAINTENANCE INSTRUCTIONS FOR LIMITED INFILTRATION If tbe iimited infiltration flow control BMP is proposed for a project,the following maintenance and operation instructions must be recorded as an attachment to the required declaration of covenant and grant of easement per Requirement 3 of Section C.1.3.3 (p. C-18). The intent of these instructions is to explain to future property owners,the purpose of the BMP and how it must be maintained and operated. These instructions are intended to be a minimum;DDES may require additional instructions based ou site- specific conditions. Also,as the County gains more experience with the maintenance and operation of these BMPs,future updates to the instructions will be posted on King County's Strrface Water•Desigra Manual website. � TEX�'OF IM��'RllCTIONS Your property contains a stormwater management flow control BMP(best management practice)called "limifed infiltration,"which was instailed to mitigate the stormwater quantity and quality impacts of some or all of the impervious surfaces on your property. Limited infiltration is a method of soaking runoff from impervious area(such as paved areas and roofs}into the ground. Infiltration devices, such as gravel filled trenches, drywelis, and ground surface depressions,facilitate this process by putting runoff in direct contacf with the soii and holding the runoff long enough to soak most of it info the ground. To be successfu{,the soil condition around the infiltration device must be abie to soak water into the ground for a reasonable number o#years. The infiltration devices used on your property include the foflowing as indicated on fhe flow control BMP site plan:�(gravel filied trenches, ❑drywells. The size, placement, and composition of fhese devices as depicted by the flow control BMP site plan and design details must be maintained and may not be changed without wriften approval either from the King CoWnty Water and Land Resources Division or through a future development permit from King County. Infiltration devices must be inspecfed annually and after major storm events to identify and repair any physical defects. Maintenance and operation of fhe system should focus on ensuring the system's viability by preventing sediment-laden flows from entering the device. Excessive sedimentation will result in a plugged or non-functioning facility. If fhe infiltration device has a catch basin, sediment accumufation must be removed on a yearly basis or more frequently if necessary. Prolonged ponding around or atop a device may indicate a plugged facility. If the device becomes plugged,it must be replaced. Keeping the areas that drain to infiltration devices well swept and clean will enhance the longevity of these devices. For roofs, frequent cleaning of gutfers wilM reduce sediment loads to these devices. i/9/2009 2009 Surface�TJater Desib Mamial—Appendix C G50 C.2.2 FULL INFILTRATION FIGURE C.2.2.A TYPICAL TRENCH INFILTRATION SYSTEM roof drain PLAN VIEW NTS 4"rigid or 6"flexfble perforated pipe t ; � •------------------------------------------------ infiltration trench sump w/solid lid PLAN VIEW roof drain NTS overflow 4"rigid or 6"flexible splash block perforated pipe � r h��'y�Y?�,�i�` :i,�y��. 6�� . /?l./../ / /,�i/i i i, i� ;, ��!.�:Cv _�,._... .......................••--..... �.o ' 6�� oo Q V �� p � � Do 0 a d� C 1'min 5,0'min „ washed rock 12 ;, E= 1 1/2"-3/4° •" �" Q o c °; 1'min . -•........ ......................�Q.s..n.°°�r. I fine mesh � CB sump w/solid lid crrcan varies A filier fabric �compacted backtill �>, -_�;�_-��= , 6�� - - . . _./' + � 4"�igid or 6"flexible 0 0 0 °o o� pe�forated pipe 24" °9 0 °9 0 o Da o �� 9°�o �o p washed rock 12" � po Q o oQ�p�a 1 1/2"-314" y p o°� o a ��`�•�%�' �—24"—�I SECTION A NTS 2009 Surface Water Design Manual-Appendix C 1/9/2009 C-45 SECTION C.2 FLOW CONTROL BMPs FIGURE C.2.2.B ALTERNATIVE TRENCH INFILTRATION SYSTEM from roof grass 6"min �overflow � ��\�i\�j/� / ��2��-3�4�� QaQ °p°oDo � washed rock %;a a QQ q oo a NOTE: Same length dimensions 18" min � =o ,o 0 0°a va and site limitations as typical system / eQ � a v�o � °a 4 n 9° p° n � 2' min I- 15' min X-SECZION NTS filter strip grass 5' min I drtvewaY overflow �'6" min ✓� � � 1 \1\\\11\'�; � �`�tE11i1��/i o pO i �� '��j2��-3�4'� a a °v°�o a washed rock %�a a ° oo o , NOTE: Same length dimensions •\ ;� ao�Q o 0 0 18' min and site limitations as t y pical s ystem v oD o � � Q� � p pOQ �°p� o �° Q° o � 2' min � X-SECTION NTS 1/9/2009 2009 Surface Water Design Manual—Appendix C C-46 � C.2.2 FULL INFILTRATION F`IGURE C.2.2.0 TYPICAL DRYWELL INFILTRATION SYSTEM �Roof Downspout House Catch Basin �(Yard Drain) / �Roof fl_� Downspout � DRY WELL 48 Inch Diameter Hole Filled with PLAN VIEW 1�/2-3"Washed Drain Rock NTS Roof Downspout Mark Center of Hole with 1"Capped PVC House Overflow or Other means Splash Block Topsoil Flush with Surface = � �l � ,l 1 =�_,:.: - 1' min. - =_- _� xn.�:,sa,�� l-, � ,cr��;��=� p •a,o`� :.J;. a�,,u 110�/ Jc,p�� gL_`�I�Sf��q�.-�i�-�C_c L �`�y'�S�L`°�J�i��'�1,�J`�OQ�_``. Fine Mesh Screen I Min.4"dia. �'�--o�c�= �.,� ,�_•°, n PVC Pipe '�°_:�;'�;=-��—��a. a C� ��y j Catch Basin ��y �``�`' O�� `1'� ' (Yard Drain) ? �� 48 Inch Diameter � Varies Sides of Hole ,�� Hole Filled with � Lined with �s 1�/2-3"Washed � Fiiter Fabric �G� Drain Rock ��, 15' min. �'` -'�- � i.� f`P,,�'��'i:r�D`'o°^�:--1_ �.,°,��J«,,�r°].��o;��C��- Min. 1'above Seasonal DRY WELL High Groundwater Table SECTfON � NTS 2009 Surface WaterDesign Manual—Appendix C 1/9/2009 C-47 SECTION C.2 FLOW CONTROL BMPs FIGURE C.2.2.D TYPICAL GROUND SURFACE DEPRESSION INFILTRATION SYSTEM from roof grass o�rf�ow 12"min f—�, ��t�•-��.�� waterstora e ,� �'`" � � .,t,.,,�� .,, g ,,,�- :,,��y��y,� ,,,. ,,,. 6«minimum �.,�;u,.,: ,�.,,�,�., ,,�,,,,•:1.,�'"�_`l, freeboard � � I � �. �, i t 15'min � infilration X-SECTION MTS grass driveway overfiow 12"minimum ,�r�� -f-- ,,...�t-�`� . ,,,,,,x,.,��.�.;, f..,,��..,,,.,,,,,��.,, ,. �waterstorage .,,:.� 6" minimum `��%-- y,�,,.�...�� filter freeboard f �•,,,�r�.,,,��..•.,,,;.,.. .�� l 5S�P T � � � , Infilration X-SECTI�N NTS 1/9/2009 2009 Surface Water Design Manual—Appendix C C-48 IV.5 WATER QUALITY VOLUME Basic water quality treatment is required for this project. StormFilter is used to provide the basic water quality treatment. The StormFilter manhole is located downstream of the Level 2 detention pond. Presettling is provided by the Level 2 detention pond. 27" 11.3 GPM ZPG cartridges are used. Water quality flow rate is the 2 year release rate of the detention pond Qwq = Q 2 year = 0.040 cfs. Peak flow of the StormFilter manhole is the 100 year release of the detention pond Qpeak = Q100 year = 0.123 cfs. Total area to be treated = 1.32 acres Total impervious area to be treated = 0.54 acres Total pervious area to be treated Nflow = 0.78 acres (grass) Onsite soil: 67.5% sand, 16.25°/a silt and 16.25% clay per Geotechnical report TSS removal efficiency estimate REe = (%Sand * Csand) + (°/aSilt * Csilt) + (%Clay * Cclay) _ (0.675 * 0.96) + (0.1625 * 0.80) + (0.1625 * 0.15) = 0.80 Flow rate based sizing: Required number of cartridges = Qwq * 449 (gpm/cfs) /Q per cart. = 0.040 * 449 /11.3 = 1.59, Use 2 cartridges. Mass based sizing: Annual average rainfall P = 37 inches Agency required % removal = 80% Percent capture = 90% EMC = 60 mg/L Vt = P * C * A * % capture = 37/12 * (0.9 * 0.54 + 0.10 * 0.78) * 43560 * 0.90 = 68176 cf. Total annual mass , Mtotal = Vt * EMC * (28.3 L/cf) * (1 E-6 kg/mg) * (2.2046 Ibs/kg) , = 68176* 60* 28.3 *1 E-6 * 2.2046 ' = 255.20 Ibs ' Pre-treatment removal efficiency Epre = 50% (Level 2 detention pond) Mpre = Mtotal * Epre = 255.20 * 0.50 = 127.60 Ibs ', Mpass1 = Mtotal — Mpre = 255.20 — 127.60 = 127.60 Ibs Efilter = 60%, REe > Efilter, o.k. to use Qcart = 11 .3 gpm '� Mfilter = 127.60 * 0.60 = 76.56 ' Q cart = 11.3 gpm ', M Cart = 54 Ibs/per cart Required number of cartridges Nmass = 76.56 / 54 = 1.42, use 2 cartridges. Both method require use finro 27" 11.3 gpm ZPG cartridges. Reedshaw Plat PED Job number: 12007 13 Determining Number of ,�V, g �.��NTE �"� Cartridges for Systems ENGINEERED SOLUTIONS Downstream of Detention CONTECH Stormwater Solutions Inc. Engineer: MAZ Date 6/12/2012 Site Information Project Name Reedshaw Plat Project State Washington Project Location Renton Drainage Area,Ad 1.32 ac Impervious Area, Ai 0.54 ac Pervious Area, Ap 0.78 % Impervious . 41% Runoff Coefficient, Rc 0.42 Upstream Detention System Peak release rate from detention, Qrelease peak 0.12 cfs Treatment release rate from detention, Qrelease Veat 0.04 cfs Detention pretreatment credit 50% (from removal e�ciency calcs) Mass loading calculations Mean Annual Rainfall, P 37 in Agency required % removal 80% Percent Runoff Capture 90% Mean Annual Runoff,V� 66,725 ft' Event Mean Concentration of Pollutant, EMC 60 mg/l Annual Mass Load, Mtota� 249.78 Ibs Filter System Filtration brand StormFilter Cartridge height 27 in Specific Flow Rate 1.0 gpm/ftz Number of cartridges -mass loading Mass removed by pretreatment system, Mpfe 124.89 Ibs Mass load to filters after pretreatment, MPass� 124.89 Ibs Estimate the required filter efficiency, Ef�ter 0.60 Mass to be captured by filters, Mfi�ter 74.93 Ibs Allowable Cartridge Flow rate, C�art 11.25 Mass load per cartridge, M�rt(Ibs) 54.00 Ibs Number of Cartridges required, Nmass 2 Treatment Capacity 0.05 cfs Determine Critical Sizing Value Number of Cartridges using Qrelease Veat+ Nflow 2 Method to Use: MASS-LOADING SUMMARY Treatment Flow Rate, cfs 0.05 Cartridge Flow Rate, gpm 11.3 Number of Cartridges 2 1 of 1 C=d�oNTECH� ENGlNEERED 50LUTIONS Size and Cost Estimate Pre,�ared by Mark Zeman on June 12, 2012 Reecishaw Plat — �torrnwater �reatr�en# Systern Renton, WA Information provided: • Total contributing area = 1.32 acre • Impervious area = 0.54 acre e Detention release rate, Qt�eat = 0.041 Cfs • Presiding agency = City of Renton, WA Assumptions: • Media = ZPG cartridges o Per cartridge flow rate = 11.25 gpm • Drop required from inlet to outlet = 3.05' minimum Size and cost estimates: The StormFilter is a flow-based system, and therefore, is sized by calculating the peak water quality flow rate associated with the design storm. However, when the StormFilter is placed downstream of detention the flow rate generated at the water quality storm is not always representative of the total volume of water that will go through the system or type of pollutant-loading the system may experience in one year. For this site, Contech Engineered Solutions LLC recommends using a 48" Manhole StormFilter with (2) 27" cartridges (see attached detail). The estimated cost of this system is 12 700, complete and delivered to the job site. This estimate assumes that the vault is 6 feet deep. The final system cost will depend on the actual depth of the unit and whether extras like doors rather than castings are specified. The contractor is responsible for setting the StormFilter and all externat plumbing. Typically, precast StormFilters have internal bypass capacities of 1.8 cfs. If the peak discharge off the site is expected to exceed this rate, we recommend placing a high-flow bypass upstream of the StormFilter system. Contech Engineered Solutions could provide our high-flow bypass, the StormGate, which provides a combination weir-orifice control structure to limit the flow to the StormFilter. The estimated cost of this structure is $4,000. The � final cost would depend on the actual depth and size of the unit. 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(CfTY OF RFNTCW f159) BELOW RfP RAP �¢3 N Q 405. �i��- � -�-- - -- -- -�- ---- ---YrfTEIP END------- - -- -�-� - �,` - ��4tSs5 � m�=v � � c� i .. � ~ OF PIPE. i. ;...�...... . .. . OVEI�LO � a , ..� ° F�RAP WPATH W Oro�w � � � � � � I ..... . . `� � '.. � ......�. ..... � BASIS OF BEAfiIlYC scu.e r-=s� W ��°a o w < d � � i m�x � a a � s ;..... . .... �. .�... � �om_� �-- '- --- �- - - - a - e�.vs oF eEaaixcs rs a.ar oF Hu�+aorN� J a 400. i � . ..�.. ... . .,.. ..... . I . . � .... . -- IXV(570N ll(AK.A.CREENFiE1D If). 4T1L. 216 P6. � Q 85LF:12-LCPE 5�0.0869 t i � : -� .. . .. ...... � ..... ..l 1 i 30 9TE AREA ��9808267 SF. OR 2?5.. 15 YW N90E ASFHALT AGLESS ROAQ . .. . ..... . . . ... -.. q � . I.. .. .i ... ;.. .' ... .... .. _ .. i.. f I ACRES+/- ' , PROJECT N .. 12007 � � 395. . .... ..... .. ...... i - WV=400.00 .---INY 400.00 ..- -- . _ -" ' ---i --- ----. _ �I 1 I DRAWN BY:� �E� ! . _ � --T- � I W � m ..i... . �... ... ..i........ ... . � . 'f1LF�t2 LCPE . ... - .... .... '... ... .I ..(1 - , . , �. . �, \, . ��. �_. x .... �..... ..� ... . ! .�. , 6g : .6LF 12 ST .531F.12 .�CPE... ... . ;'?i/."�. �,:'/.';�/..//,l/2%/..//..//ii/, ISSUE DATE: 12�05/OB � j ': . 5 0 0072 5�0.038D . ... .�...... ...i ........ � . ... .�..... �..5 . . ! . . ...... tOLF'lY'iCPE .. 2"HMA CLASS f/Y =0 00 I � ' I � SHEET REV.: 09/09/2012 ...� .. ..... ( .. . ...... . .. ...:.... .. ..... . �... .. ... _ .. . ...... Sy0.0551. ..., . .i . �4'HMA G2A55 3/4'OR Y �.. i 390. ....,.,.I�.. ..f........ � ...... ... .. ...... ------ -....�CB��--. � _ ... fAMPACTED SLBGRADE � .... . ...... ..�.. ..�.. : . ..?.. ..�.. .... ..�.. .... �..........�..... . ................................i........ .`..........i..........i...... '+. ....'.. � I , I f.E. 1� W-493.4� f� ( $TORM LJPE � . ...... ...... ...... ........l........ ...... ........I........ ...... ; ...-I.E�1E'Na39275.�p��.... . .... .... .... ..:.. .. . i � i �� a ....'..............................:..........�....................;..........�..........�..........�......4.E.�i2�5E=394.�.........`.. ��a� � : ; ; I � , ASPHALT P011�ACCESS ROAD �e Z 385. ..-r...................!.......... .. ......I....-1-.. .�. ....� ....... ...... �---.�...--+ ......F. ...... ` . t. Nl MAINUNE S70RA/PIPE SFlALL BE ADS N-i2 Wf!B SM007H W7WOR SCALE: i'm5' CALL 48 HOURS TFHOUC�i i : . ._ ; ' ; ! WALL PlPE UNL£SS OTHERN75E NOiED. 7HE MA/N AND FlTi]NGS N71L NEED p�'@�7�ON � � ;.. _................:....-� : ! .......... �....... ; ......_E......... , BEFORE YOU DIG W S �j� T(J BE AfR TESTABLE PER ASTL F1417 WATERTIGHT FIEtQ TEST. �� . . .... . .. ... . � . . . ...., . . . ....... �. . z w .. .�.. .. ; , .. ..... : . 4 rc ..!.. . .. � ......!. . .. ........ .:..... ..i .... ..�. . .,.. . '�.. ...... i ..... : . ..... . 2 AtL 6'AND 8'DfAMfTER STCMM P1PE 9fALL BE PVC ASTM 3034 SOR 35. 0 380 R_�72�3 1-800-424-5555 � � N o � N N �oucnce u�orr w�is aEanr��Far�tt Pr�xohr tFss na.aH 2'oF aeo�snoa�aa.owc c� m �ai �a �a �n �cv Wn �n Nm ga �n � COVEH. W o o;o 0 0 0°0 0 0 �^a �o ri^o o�` o o � CHECKED FOR COMPUANCE RECOMMENDED a a g a e a a g g a n a n+ g� w g a� g g TO CITY STANDARQS FOR APPROVAL Date BY: �� 0+00 4+20 0+40 0+60 �+80 1+00 1+20 1+40 1+60 1+80 2+00 Y�-2p 2+40 Date BY: � cV Z Date SHEET 13 OF 29 � �� The conveyance analysis included in this report at construction document submittal (see attached tables). The system will be designed to convey the 25-year peak flows and checked for flooding conditions at the 100-year event per 2009 King County Surface water Design Manual. Reedsha�v Plat PED Job number: 12007 14 � 3.2.1 RATIONAL METHOD - . . . , TABLE 33.i.A RUNOFR COEFFICIE�ITS-"C"VALUES F�R T�IE RATIONr�I:IlZETI�OD 6eneral Land Covers Single Family Residential Areas� Land Cover C Land Cover Density C Dense forest 0.94 0.20 DU/GA(1 unit per 5 ac.) 0.17 Light forest 0.15 0.40 DU/GA(1 unit per 2.5 ac.) 0.20 Pasture 420 0.80 DU/GA(1 uni#per 1.25 ac.) 0.27 Lawns 0.25 1.00 DUIGA 0.30 Playgrounds 0,30 1.50 DiJ/GA 0.33 Gravel areas 0.80 2.00 DU/GA 0.36 Pavement and roofs 0.90 2.50 DU/GA 0.39 Open water(aond, lakes, 1.00 3.00 DU/GA 0.42 wetlands) 3.50 DUIGA 0.45 4.00 DUJGA 0,48 4.50 DUIGA 0.51 5.00 DU/GA 0.54 5.50 DU/GA 0.57 6.00 DUIGA 0.60 �Based on average 2,500 square feet per lot of impervious coverage. For combinations of land covers lis#ed above, an area-weighted"C�:x Al'sum should be computed based on the equation C�: x A,_(C�x A,)+ (CZ x AZ)+ ...+(C„x A„},where AB=(A�+AZ+ ...+,q„),the total drainage basin area, _ '- TABI,E 3.2.I.B C��'�'ICIEN�S�OR THE RATIaNAI,lYiETHai3"i�"EQUATION . Design Storm Return Frequency aR bR 2 years 1.58 0.58 5 years 2.33 0.63 10 years 2.44 0.64 25 years 2.66 �.65 50 years 2.75 0.65 100 years 2.61 0.63 TABLE 3 21 C_-kR YALITES FOR T,USING THE RATIONAL METHOD - = _ - Land Cover Category kR Forest with heavy ground litter and meadow 2.5 Fallaw or minimum tiilage cultivation 4.7 Short grass pasture and lawns 7.0 Neariy bare ground 10,1 Grassed waterway 15.0 Paved area(sheet flow)and shallow gutter flow 20.0 2009 Surface Water Design Manua[ 1/9!2009 3-13 ' SECTION 3.2 RUNOFF COMPUTATION AND ANALYSIS METHODS FIGURE 3.2.1.0 25-YEAR 24-HOUR ISOPLWIALS �S — SN MONISN COUNTY 'j � _- -� �._ .� 1 ..-..` 3� . � _ _p' �_'�� . 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' �F � � � � ; �� I�I - '�`�� i I -y^ �� r _ ` �i " � '`� -� .J `� - `; l�i� ' : r }� ' �� E� k �- '� - l�=,', � i � � \� \ �s�� / ,' .� � _ , t � � 1 FD �_ �: _ - � � ,� .. � t t t� � �—� � - � �,\_ ' � Z`: 5.0 - Ul1 �F��' �i - �� \ - � .✓ �I - _i `�\�� '� � ' - - ,�� +. �\ � _ � `s - �� i � �' -_� .� . � �-�1 y—� � � ,_ � _ _- � � � � � �...--- . � { `� _'` � ' f --� �; _:+.�� I — � v1�i.� , - � ��.,�-- ; � , =� ,... � o�i� �.�:. �3'�' . � � - � - _- -� .�l � .R� , } �.I�f -� � q ' a � 4� _ _ i � �.-jJi` �rr' � 1� - �-� � - -- �� i- .�J�� % __ '_"� i �. : .� = - � r__.� � � �' � _ f � � _ � t'�' �f. _ - �� Q �.� r Q _ - '�� i i _ �_ . l. - i �"� �. _� a ` � y � 1. l ,� �=�j ' � a _ � ; i��'� , '° I -- - ! ;, t 5 � � — � --�_�- -- �_ 5; ._ �, - - - M �:: = Y,�� _ � �-- .\\ �i� `.. ��T.L � _ �. � _\ � ♦ . �• I . 1. .. ��i� A —.�� C I • � . :: j � ` ; �b `�� '�o�i� `�,�"� 1 —� ' r = �• ^ (n � / ; �� '- J "'� . (0 '+ � � �' adxe � �,� .� � : M� �• c+�� / � 4- �`�,^ =.� F'� �� KIKG COUNTY \ O�� "°�'�`� --- =----- I (y PIER�E COUNTY l�� '".7 �\ WESTERN ,� ''��,� � i K1NG CDUNTY �,��. -.--:�°��« Ss \_ •� n •` � 25-Year 24-Hour ' � � � �'S,�. � � , Precipitation �� -�, ,_,,�� in Inches °�'n`1es �. � �,�-- 1/9`2009 2009 Surface�Vater Desien Manual 3-16 � 3.2.1 RATIONAL IvfETHOD FIGURE 3.2.1.D 100-YEAR 24-HOUR ISOPLUVIALS lj��Jr 'I .. �� ` - �_� �__ _—_ __ _�_ N O � C O U N T Y I� } � � y N COVNTY 3�F = �sxo e �i +\ 1 `� t'y el ' �� . {J . •9 7 1 \jf� j� 3� _ � . � � / � Iv� L '\�3 ' �I �_ `� _ � �� `�� , �-_,� 1 ��` � a; � _�� ' ' ` I 1= J Iir � ,j ��I � ' ' 1 -_- ` e , � � a � .='�i�i f � - � : ,� �:3�� , � '_ � �:� aa �9 �—�`� � ��` ; -- � { �! < t� 0 ' � � t 1 '" ��r�-; '- M 4 7 =}�! .�: f- � � � ={� . ,..�( `� _ � . �T �^ � / E � �� `�'�� '��I =� 4 "- � I��cy � —'1 � S �� a i ' � � � � � �s �3 �` ,�\ � ,, � � m�, f �'.� �l f; 1-�. �, ' - J f « I _-'r✓i�/ �- � �° ~ �_' - :� a .(_,r 4 t : � i� � � t � �� i "� � �� . � 1 \(�- � c.�erue I �� 1 .� - T -1 � I � _ � _ \ , I � "_ ��/ I r 1 � � - \ � �` � �� \ i � ` �,�!�i ` � '��` � � _ I � �� - ��I N � ,�I \ l - 1 ' � _ E I — � �.� � � . 1`�� 1� F � 7 ` - ,�i l l � l. - . ( f~J�. � � '_ �I�ir\E \�I�I�� l / � �� ,� \\ �_��1� 1 \ � •� �� '1'� -� � ' � _ �_ / _ ' __ ___ _ _ \l r �� F ; t'� _ � - - - -� ,�\��, �_ , �, �l � —� 9 , � � � ,, ' ' \� �.,. � � _�� , , - � � � • _ , :T-� . _s � .�'<,. - � ;'7```"' � _ � � � _i \_; j �� ''� � :. ==� ' - �I -- / � �. , � - - } � � � ' � _. p� - ":�:� s� .i� 1 "t� r: 9 � CT1 -j/ o � i...., �. �- �.` !j �4 : ` � - -J , / / �- � � ,.�/ ..�� il. '�-,� � � � �� ._ :_ � �� .. ��.' � �--� '� �' '�� \ - � �� / � t - i �,�t ��. - � '\ �i �� ` _} r- i Y'� � ., \,�� } f, ti � — - m' R �3 , _ �� = 1� = � �. � � � ��1 ` i� _� _�Yo ��. � �1.1� ,..L—_ _—j'� F� - :'3 = -.-_ -�� L.i _ . �� :.� � � � � � � fi f � a'�� - ' � ��-� \\�-\ � / ''� - - - �� ` gs�� _ _ � �� - - �� _ i ya `� � { _ ,I "__ r- Z _ t _ � /� `(�� `� � } --� � � � - � -_ � � •� °••i � ;,'y�`' 1 � ,' ' '� , � ; o : �_� ° l� .�1,!�� I� � , _ \ �1 � r ° _ _; � � � � 1 fylll� �:_`�_ _K G COUNTY \ - ,� � i� PIE CE COUIiTY �1 WE�TERN o� `� � '��. I� `�� , _. 1 6.5 KIIl�G COUI�TY �o ,, ,,, -- ._:.�C ,w_ s.o N b• �, _.�-= -,� 5.5 100-Year 24-Hour °� �'� � ' � �� Precipitation °`�� a -�� ,_.��_`� � in Inches 0 2�4Miles h. h� 2009 Surface Water Design Manual 1/9/2009 3-17 AREAS CALCULA710NS SUMMARY OF CALCULATIONS AREA TOTAL TOTAL PERVIOUS IMPERVIOUS PERVIOUS IMPERVIOUS RUNOFF NAME AREA(SF) AREA(AC) AREA(SF) AREA(SF) AREA(AC) AREA(AC) COEFFICIENT TOTAL 98082.0000 2.2517 81 19606.0 0.450 5881.80 13724.20 0.135 0.315 0.317 0.71 62 782.0 0.01 a 78.20 703.80 0.002 0.016 0.015 0.84 B3 3440.0 0.079 344.00 3096.00 0.008 0.071 0.066 0.84 B4 2864.0 0.066 286.40 2577.60 0.007 0.059 0.055 0.84 B5 13274.0 0.305 3982.20 9291.80 0.091 0.213 0.215 0.71 B6 17552.0 0.403 5265.60 12286.40 0.121 0.282 0.284 0.71 67 1398.0 0.032 139.80 1258.20 0.003 0.029 0.027 0.84 B8 7296.0 0.167 729.60 6566.40 0.017 0.151 0.140 0.84 B9 1586.0 0.036 396.50 1189.50 0.009 0.027 0.027 0.74 B10 5460.0 0.125 1310.40 4149.60 0.030 0.095 0.093 0.74 TRACT A 7070.0 0.162 3393.60 3676.40 0.078 0.084 0.095 0.59 TRACT D 1400.0 0.032 1400.00 0.00 0.032 0.000 0.008 0.25 0.00 0.00 TOTAL 81728.0 1.876 23208.1 58519.9 0.533 1.343 I f I Project: REEDSHAW PLAT JOB#06085 CALCS BY:TLR DATE: 7/19/2072 I RATIONA�METHOD PEAK RAINFALL INTENSITY Q=CIRA -....- _-- -- design storm (years) 25 Enter 10 or 25 - _....-_ 24 hr.precip.(in.) 3.5 LOCATION AREA cum.A Tc i, I, Q, pipe dia slope n Q�„ii Vr�u Q�Qrun V at Q, ipe leng travel tim from to (acres) C AC (min) (cfs) (in.) (ft!ft) (cfs) (ft/s) (ft/s) (ft) (min) B1 CB#1 0.450 0.71 0.320 0.320 6.3 0.80 2.81 0.90 --- --. ___- --- CB#1 CB#3 12 0.0265 0.012 6.30 8.02 0.14 4.97 103 0.3 -- - -- - B2 CB#2 0.018 0.84 0.015 0.015 6.6 0.78 2.72 0.04 CB#2 CB#3 12 0.0052 0.012 2.79 3.55 0.01 0.93 31 0.6 B3 CB#3 0.079 0.84 0.066 0.401 7.2 0.74 2.58 1.03 CB#3 CB#5 12 0.0443 0.012 8.15 10.37 0.13 6.23 134 0.4 ___ _._. __ ---- 64 CB#4 0.066 0.84 0.055 0.055 6.3 0.80 2.81 0.16 _.._._____.----__ _ ._._......_- CB#4 CB#5 12 0.0052 0.012 2.79 3.55 0.06 1.57 31 0.3 -_ - - --- 65 CB#5 0.305 0.71 0.217 0.673 7.6 0.71 2.50 1.68 CB#5 CB#7 12 0.0222 0.012 5.77 7.34 0.29 5.26 67 0.2 66 CB#6 0.403 0.71 0.286 0.286 6.3 0.80 2.81 0.81 - ---.._........_ - --- --.._...._. CB#6 CB#7 12 0.0206 0.012 5.55 7.07 0.15 4.40 53 0.2 - -........_.. - ---....._ B7 CB#7 0.032 0.84 0.027 0.986 7.8 0.70 2.45 2.42 -...._ . _ --- CB#7 CB#9 12 0.0317 0.012 6.89 8.78 0.35 6.59 28 0.1 , - - -_- _.__.._. B8 CB#8 0.167 0.84 0.140 0.140 6.3 0.80 2.81 0.39 CB#8 CB#9 12 0.0049 0.012 2.71 3.45 0.15� 2.15 43 0.3 B9 CB#9 0.036 0.74 0.027 1.153 7.8 0.70 2.44 2.81 I CB#9 CB#10 12 0.1055 0.012 12.57 16.01 0.22 10.90 104 0.2 610 CB#1Q 0.125 OJ4 0.093 1.245 8.0 0.69 2.41 3.00 _ � . ---..............-- --__..._ CB#10 POND 12 0.0869 0.012 11.41 14.53 0.26 10.19 34 0.1 12 0.3000 0.012 21.20 26.99 0.00 4.63 6 0.0 . 8 . . . � 15445 53RD AVE.S.,SEATTLE,WA 98188 PHONE(206)431-7970; FAX:(206)388-1648 l�� pl P�S H,QV�, ?H� �fl PA C 1?`� -Ta co�v v�y TN� z.5 yL-�1 R P�1K F�.vW � - -- ___ � Project: REEDSHAW PLAT JOB#06085 CALCS BY:TLR DATE: 7/19/2012 , - .. _ _ __.. _ - _� __...... _ _......_ RATIONAL METHOD PEAK RAINFALL INTENSITY Q=CIRA design storm (yeai R= 100 Enter 2 or 100 24 hr.precip.(in.) PR= 3.g - - LOCATION AREA Sum Tc i, I� Q� pipe dia slope n Q�,ii Vr„ii Q/Qi„�i V at Q, ipe leng travel tim from to (acres) C C-A C-A (min) (cfs) (in.) (ft/ft) (cfs) (ft/s) (ft/s) (ft) (min) B1 CB#1 0.450 0.71 0.320 0.320 6.3 0.82 3.19 1.02 -- -- - .- - --. - CB#1 CB#3 12 0.0265 0.012 6.30 8.02 0.16 5.13 103 0.3 ---- _ - _ __- 62 CB#2 0.018 0.84 0.015 0.015 6.6 0.79 3.09 0.05 CB#2 CB#3 12 0.0052 0.012 2.79 3.55 0.02 0.96 31 0.5 63 CB#3 0.079 0.84 0.066 0.401 7.2 0.75 2.94 1.18 _. _ ...._ _ ._..__ _._. CB#3 CB#5 12 0.0443 0.012 8.15 10.37 0.14 6.45 134 0.3 ---- - - _... 64 CB#4 0.066 0.84 0.055 0.055 6.3 0.82 3.19 0.18 _..__.._ _.._.. __ _ _ CB#4 CB#5 12 0.0052 0.012 2.79 3.55 0.06 1.66 31 0.3 B5 CB#5 0.305 0.71 0.217 0.673 7.5 0.73 2.86 1.92 CB#5 CB#7 12 0.0222 0.012 5.77 7.34 0.33 5.43 67 0.2 B6 CB#6 0.403 0.71 0.286 0.286 6.3 0.82 3.19 0.91 ---- _. CB#6 CB#7 12 0.0206 0.012 5.55 7.07 0.16 4.53 53 0.2 B7 CB#7 0.032 0.84 0.027 0.986 7.7 0.72 2.81 2.77 -_ ___ ---- CB#7 CB#9 12 0.0317 0.012 6.89 8.78 0.40 6.87 28 0.1 � 68 CB#8 0.167 0.84 0.140 0.140 6.3 0.82 3.19 0.45 CB#8 CB#9 12 0.0049 0.012 2.71 3.45 0.17 2.21 43 0.3 � ---...___ -- - - - - - 69 CB#9 0.036 0.74 0.027 1.153 7.8 0.72 2.79 3.22 CB#9 CB#10 12 0.1055 0.012 12.57 16.01 0.26 11.17 104 0.2 �.. .___ _---- ___ B10 CB#10 0.125 0.74 0.093 1.245 7.9 0.71 276 3.44 - - -- - - CB#10 POND 12 0.0869 0.012 11.41 14.53 0.30 10.48 34 0.1 A .6 . 5 8.0 0.70 2.75 3.42 Detention pond primary overflow path '� 100 year pond overflow Q 1.47 --. __ _ - ..._ SF#1 CB#11 12 0.0380 0.012 7.55 9.61 0.19 6.38 57 0.1 1.47 -- - - - -- _--- -- __ - -.. -- CB#11 EX.CB 12 0.0551 0.012 9.09 11.57 0.16 7.39 10 0.0 15445 53RD AVE.S.,SEATTLE,WA 98188 PHONE(206)431-7970; FAX:(206)388-1648 �LL Pl PC S MAVL �'H� G�(P�G f-� 7v Go7V✓�y ?H L !vD Y�i2 ��I� FLc�W . i - — - — -- ��,:,,. , _ _ , , , - aoo - - 11� ` � nin� -r corv�r — - — - � - � �o�. t�ox � �� _- _ _- -__. �i i0l_E � - --- __ _ � M� 1 --- -t= s�. � - vtna - -a_m p �IG A - 1 N � I � at --�� :i �s�'��j -- -� �� _ �h1ANDH�LE � �� --._1 s�_ s-�� - , � ' ' -g.� _�._� �' �I i � �� - 4001 -_ � - --- --A. _� _�� $3 � �'� � _.,,_. 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Mf'E_ i S89'00'23"E 723.12", n -I -N-- IP 1I * � = � � 1 ,' ,r�c� t " � �� - -- 436�� '� v,�y, m � i � mlc�'i �1 4 i � � � - - �� '' �m , , , � 1 i ' � � - - 438 — � - - - - � _ ?'z1 �,��i _ II_ � t DA Planning, Engineering, Project Management �, Land Development Advisors, LLC 12865 SE 47th Place • Beilevue, WA 98006 �'� 425-466-5203 February 8, 2013 Ms. Kayren Kittrick City of Renton 6th Floor 1055 South Grady Way Renton, WA 98057 RE: Reed Shaw Plat Detention Pond Modifications LDA Job No. CALX-003 Dear Kayren, l I have been retained by the builder/developer (Callidus Development) of this project to , prepare building permit applications. In preparing the background information to prepare individual lot drainage plans, we reviewed the TIR prepared in August 2012 by Pacific Engineering Design, LLC ("PED"). Their analysis assumed 1,750 square feet ("sf') of impervious area for each lot. In addition, limited infiltration and pervious � pavement driveways were assumed that converted 0.24 acres ("ac") of impervious area to grass for purposes of the detention calculations. The various areas and assumptions are further detailed in their TIR (attached). We have re-analyzed the pond and outlet structure and with some minor modifications to the control structure, the detention facility will accommodate 1,750 sf of impervious for each lot. Modifications include raising orifice elevations, changes to orifice � diameters and raising the overflow elevation about an inch. Details follow. ' Developed Conditions The following tables summarize the areas and developed runoff used in the original PED design and those used in this analysis ("Proposed"). Full KCRTS printouts are attached. Table 1 — Developed Areas Area PED ac Pro osed ac Total Site 1.88 1 .88 Impervious 0.81 total 1.05 total Private drives 0.16 0.16 Roads 0.38 0.38 ' On-lot 0.24 0.48 Pond 0.03 0.03 Lawn 1.07 0.83 , � Ms. Kayren Kittrick February 8, 2013 Page 2 Table 2 - Developed Runoff Storm Event - ear PED cfs) Proposed cfs 100 0.61 0.67 50 0.52 0.58 25 0.36 0.40 10 0.32 0.40 2 0.27 0.33 Routinq Calculations The values used in the PED analysis for the pond dimensional parameters were utilized to redesign the control structure to accommodate the additional impervious area. Resulting KCRTS output for the facility with control structure modifications is: Retention/Detention Facility Type of Facility: Detention Pond Side Slope: 1.82 H:1V Pond Bottom Length: 47.00 ft Pond Bottom Width: 20.00 ft Pond Bottom Area: 94C. sq. ft Top Area at 1 ft. FB: 9�02. sq. ft 0.103 acres Effective Storage Depth: 8.60 ft Stage 0 Elevation: 0.00 ft Storage Volume: 19912. cu. ft 0.457 ac-ft Riser Head: 8.60 ft Riser Diameter: 12.00 inches Number of orifices: 3 Full Head Pipe Orifice # Height Diameter Discharge Diameter (ft) (in) (CFS) (in) i 0. 00 0.62 0.031 2 6.40 1.00 0.040 4.0 3 7.05 0.93 0.029 4.0 Top Notch Weir: None Outilow Rating Curve: None ?.�ute Time Series through Facility '�, Inflow Time Series File:reeddev.tsf I� �utflow Time Series File:REE�� DCUT Inflow/Outflow Analys_s Peak Inflow Discharge: ;1. 5�2 �FS a- F; GO o-� J�-� ° `� Y�ar 8 Peak Outflow Discharge: �.424 CFS a_ =�:G� o� Ja� ° _� Yea� � I Feak Reservoir Stage: 8.70 Ft , ?eak Reservoir Elev: 8.70 Ft P�ak Reservoir Storage: 20327. Cu-^t . 0.467 Ac-Ft 3�,,d Inflow Outflow Feak St�rag� . ' Ms. Kayren Kittrick February 8, 2013 Page 3 Target CGlc S�a,e E-_ev (Cu-Ft) (:�c-_t) 1 0. 67 0.15 0.92 8.70 8.70 20327. 0.46? 2 0.33 0. 12 0.10 8.57 8.57 19805. 0.955 3 0.40 0. 09 0.08 7.87 7.87 17111. 0.393 10 yrok 4 0.40 ******* 0.08 7.85 7.85 17018. 0.391 5 0.35 ******* 0.05 7.10 7.10 14398. 0.3?= 6 0.34 0.05 0.04 6.54 6.54 12593. 0.28? 2 yrok 7 0.26 ******* 0.03 5.67 5. 67 10055. 0.231 8 0.28 ******* 0.02 4.43 4.43 6945. 0. 1�� Duration analysis results confirm the pond with modifications meets the level 2 flow control duration criteria. N p '________ �________ti_ . . . . � , . ... • �-'! � i, R + o - ---- • � os • '� N o ....w. LL �, � U ? ♦ m o ♦ rn � o � � OOO • y ♦ � Q O ♦♦ l i p ♦ 1 00 � ♦. _ N _ O O I O I O � � I i i �� , �0 3 �� z �� L Probabfiity Ezceedence D��ration Ccmpar�son Anaylsis Base F�le: reedex.tsf New File: reedr dout.tsf Cutoff Units: Discharge in ��F� -----Fraction o= T-�ne----- ---------Chec;� o� Tclerar.c2------- Cutoff Base '_Vew �Change Prc:�a�i=-ty �ase New %C=�a�ce 0.026 � 0.94�-02 0.1_E-01 18.6 � C.94E-02 0.026 0.026 0.4 50% ofthe 2 year , 0.033 � 0.63E-02 0.64E-02 2.1 I C.63E-02 0.033 0.034 3.� values are equal, 0.040 I 0.50E-02 0.49=-02 -1.6 � 0.50E-02 0.090 0.040 -1.0 no change. 0.047 � 0.37E-C2 G.31E-02 -17.5 I 0.37E-02 0.047 0.045 -�.8 C.054 I 0.28E-02 0.23E-02 -2C.7 � 0.2�E-G2 �.C54 0.049 -1Q.� O.G62 I 0.22E-02 0.18E-02 -17.0 I 0.22�-02 0.062 0.055 -1G.1 0.069 i 0.15E-02 O.laE-02 -6.7 I 0.15E-02 0.069 0.067 -2.�3 0.076 I O.�OE-OL 0.'lE-C2 4.8 I O.10E-02 0.076 0.077 1.8 0.083 I 0. 62E-03 0.57E-C3 -7.9 I C.62E-03 0.�83 D.062 -0.^ 0.�9� � �.34E-03 0.28E-03 -19.0 � C.3�E-03 C.090 0.�9R -1. 9 _ . _�- , = ._3E-C_ S._�_-. - -� , ._ I � .��E-C� � . _�� _ ,:�,y� - _ ,h. � Ms. Kayren Kittrick I�, February 8, 2013 ', Page 4 ! �.104 , 0.16E-�3 �.CCE+O� -lOC.O � �."_6E-C3 0.104 0.095 -.. .� ' 0.111 � 0.11E-03 O.COE+00 -100.0 I 0.11�-03 O.11l 0.097 -13.2 0.? 18 I 0.16E-04 O.GCE+00 -100.0 � 0.�6�-�� .l"�8 0.099 -16.,� Maximum positive excursion = 0.001 cfs ( 4.30) < 10%, O K occurring at 0.033 cfs or the ?ase Data:reedex.tsf and at 0.035 cfs on the New Data:-eedr dout.tsf Maximu_n negative excursion = 0.019 cfs (-15.1�) occurring at 0.118 cfs on the Base Da�G:reedex.tsf and at O.C99 cfs on tr2 Ne�a Data:reed- dou�.�sf Table 3 - Detention Pond/Control Structure Comparision Element PED Proposed Riser Hei ht 8.5' 8.6' Orifice No. 1 0.63"/0.00' 0.62"/0.00' no chan es Orifice No. 2 1.25"/5.75' 1.00"J6.40' Orifice No. 3 0.88"/7.25' 0.93"/7.05' Primarv Overflow The original riser required 0.3' to pass the 100 year flow as calculated by KCRTS using 15-minute time steps. With the additional impervious area, the 100 year flow is 1.66 cfs. Flow Frequer.cy Analys��s ^_ir.te Series File:reeddevl5.tsf Froject Location:5ea-Tac ---Annual Peak Flcw Ra�es--- -----Flow Frequercy A�alysis------- Flcw Rate Rank Time of Peak - - Peaks - - Ran.�c Return Prob (CFS) (CFS) Feriod 0.50� 6 8/2�/C1 18:00 1.66 1 �OC.CO 0.990 0.367 8 1105/02 15:G0 1.13 2 25.00 0.960 1.13 2 12/08/02 17:'_5 0.7Q6 3 iO.00 �.900 0.403 7 8/23/04 14:30 0.688 4 �.00 0.800 0.688 4 1'/17/04 5:00 0.614 5 3.00 0.667 0.614 5 10/27/05 10:4� �.500 6 2.00 0.500 0.706 3 10/25/06 22:4� 0.403 7 i.3G 0.231 1.66 1 1/C9/08 6:3C 0.367 8 _.'0 0.091 Computed Peaks 1.48 50.00 0.980 The height over the riser is 0.3' as shown on the attached Riser Inflow Curve. With the additional riser height, the maximum water surface is 0.3'+0.1' or 0.4' higher than originally designed. Since it is less than the 0.5' minimum freeboard required over the original riser, this is sufficient. ' Ms. Kayren Kittrick February 8, 2013 Page 5 Secondarv Overflow The PED rectangular weir was designed to pass 1.5 cfs in a required length of 5.22'. A higher flow of 1.66 cfs would require a length of 1.66 cfs/1.5 cfs(5.22') = 5.78'. There was 6' of weir provided, so ok. Secondarv Inlet to Control Structure The original "jailhouse window" required a 3.28' long x 0.3' depth opening to pass 1 .5 cfs. A 0.5' deep opening was provided that would nearly double it's capacity. By inspection, the additional 0.16 cfs will not have a negative impact to the function of the inlet. � Ms. Kayren Kittrick February 8, 2013 Page 6 APPENDIX i