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HomeMy WebLinkAboutSWP272304 DODDS ENGINEERS, INC. ® CIVIL ENGINEERING S U R V E Y I N G PLANNING ' TECHNICAL. INFORMATION REPORT ' LEXINGTON RIDGE APARTMENTS ' RENT+( N, WASHINGTON 1 1 t Prepared by: Kurt R. Stranne Approved by: Bruce J. Dodds, F.E. Z Date: October 1996 ' DEI#: 87075 " 4205 1 48TH AVE. N.E., SUITE 200 - BELLEVUE, WA 98007 (206) 885-7877 FAX: (206) 885-7963 TECHNICAL INFORMATION REPORT ' LEXINGTON RIDGE APARTMENTS RENTON, WA ' TABLE OF CONTENTS 1 I. PROJECT OVERVIEW 1 II. PRELIMINARY CONDITIONS SUMMARY ' III. OFF-SITE ANALYSIS IV. RETENTION/DETENTION ANALYSIS AND DESIGN ' IV.A. INFILTRATION SYSTEM DESIGN ' V. CONVEYANCE SYSTEMS ANALYSIS AND DESIGN VI. SPECIAL REPORTS AND STUDIES - SETTLEMENT AGREEMENT 1 VII. BASIN AND COMMUNITY PLANNING AREAS - NOT APPLICABLE ' VIII. OTHER PERMITS (NONE) IX. EROSION/SEDIMENTATION CONTROL CALCULATIONS ' X. BOND QUANTITIES WORKSHEET 1 XI. MAINTENANCE AND OPERATIONS MANUAL i 1 1 t 1 ' King County Building and Land Development Division Pago 1 of 2 TECHNICAL INFORMATION REPORT (TIR) WORKSHEET ' - - . DESCRIPTION Project Ownor j_-uylIU2-lc-jD,,Velopt={_Croup_ Project Name T,cxi nc3iQn_Ri dge Address131 SW 156th St, _Ste 100, Seattle Location ' Phone _(206) 241-4800 VZA 98166 Township_23N Project Engineer Bruce J. Dodds Range 5T Company Dodds L7iaineers. Inc. Section 17 ' Project Size 13 4 AC Address Phone 4205_L48_th Amo I - ,_StQ 20Q Bellevue WA 98007 Upstream Drainage Basin Size NA AC ' 7�=� Short • • • sion = DOF/G HPA Shoreline Management ubdivision = COE 404 ® Rockory g = DOE Dam Safety ® Structural Vaults J Commercial = FEMA Floodplain Other 0 Other COE Wetlands HPA Community City of Renton Drainage Basin Mount Olivet Sub-Basin, Tower Cedar River ' River Floodplain Stream Wetlands Critical Stream Reach Seops/Springs ' Depress ions/Swalos High Groundwater Table 0 Lake 0 Groundwater Recharge CTx Steep Slopes Adjoining 3rd St Other Lakeside/Erosion Hazard PART7`SOILS 1 Soil Typo Slopes Erosion Potonlial Erosive Velocities Everett 5-4 Q`i; Al.derwood 15-40% ' Urban 5-4 M CJ Additional Shoots Attatched 1/90 Page 2 of 2 King County Building and Land Development Division TECHNICAL INFORMATION REPORT (TIR) WORKSHEET ' PART 8 DEVELOPMENTLIMITATIONS REFERENCE LIMITATION/SITE CONSTRAINT ' nx Ch.4-Downstream Analvsis _5 � — s , ��ct to settic7ncnt agrecsnent O O ' Additional Shoots Attatched ' MINIMUM ESC REQUIREMENTS MINIMUM ESC REQUIREMENTS DURING CONSTRUCTION FOLLOWING CONSTRUCTION Sedimentation Facilities Ex] Stabilize Exposed Surface �] Stabilized Construction Entrance EE Remove and Restore Temporary ESC Facilities ® Perimeter Runoff Control ® Clean and Remove All Silt and Debris ® Clearing and Grading Restrictions F-K Ensure Operation of Permanent Facilities 0 Cover Practices Flag Limits of NGPES ® Construction Sequence 0 Other 0 Other ' Grass Lined Channel Tank © Infiltration Method of Analysis ® Pipe System Vault = Depression SBUH Open Channel Energy Dissapator = Flow Dispersal Compensation/Mitigation ' Dry Pond 0 Wetland = Waiver of Eliminated Site Storage 0 Wet Pond 0 Stream Regional Dotontion Brief Description of System Operation Facility Related Site Limitations [] Additional Sheets Attatched Reference Facility Limitation • 0 Drainage Easement Q Cast in Placo Vault Other Access Easement Retaining Wall 0 Native Growth Protection Easement ® Rockory>4'High Tract 0 Structural on Sloop Slope [=J Oth r I or a civil engineer under my•suporvision have visited the site. Actual site conditions as o6sorvod were incorporated into this worksh©et and the attatchmonts. To the best of my knowledge the information provided ' here is accurate. 5 ,, 1190 1 1 1 1 1 1 1 1 PROJECT nVLRY1F.W 1 1 1 1 1 1 1 1 ' I. PROJECT OVERVIEW ' Lexington Ridge is a 13.4 acre site located east of I-405 between 3rd and 4th Streets and west of Edmonds Avenue (see Figure 1 for Vicinity Map). The developer proposes to construct 19 apartment buildings and a recreational facility. See Figure 2 for Site Plan. rThe design criteria for the site's storm drainage facilities will conform to the Settlement Agreement between Lexington Ridge Realty and the City of Renton (see Settlement ' Agreement in Section VI). The Settlement Agreement establishes storm drainage criteria as follows: 1 . the post development flows from Lexington Ridge for the 2-year through the 100-year design events will not exceed the values given in the table below: Return Interval Increment above undeveloped flow (cfs 2 year 0.44 10 year 0.44 ' 25 year 0.50 100 year 0.50 ' • no volume safety factor will be added to detention volumes, • water quality storage shall be incorporated into the design of the detention vault, • the existing 8-inch diameter storm drain in Bronson Way at the intersection of ' N.E. 3rd will be replaced, 0 no biofiltration will be required. 1 r r r r r r UAL�K 1 NG-,.'CO. SE RAP Ba"M -4 _VAIMM v cli Eli V 7 Es A,—- m 3S 7- ltx 9L., �pv, to IW, 61r tit nj co t F t; c y ill i•p I4KfII T A'I­ flippi tJVT. ONJpTINNtrI 51 '"I) E;zg A A! AV , a . � , 71 11 AV 1111,, ; 0 , K7 In Ht vv� P; is CD 'Y C—D I 1 Z_ I Y":,af Cr_1 is Iel 13H AV NOW kv, 1z, I s,. 39 AV VWDNI AV Z_x AV NoII]NS 14b" tx AV wilm Wei t;j AV 1U621 A- 00991 S, "V! :AQ E,7. Avivv H.L E 005 H . R s I m 3N AV ULu) I - 1 4j0 4 A: .A sr \L %t : - • w C , 'A. A, U IZI AV, -r-A�3S 4p, 00991 N z _ M IS+ X3 K \* t 101. � 'errs _ A, ."I A 7� _ l 35 AV tin I ZI _ ON - owul tiZ C - J� AV0 e -,ill A, xlAr ozl Al V A V , 15 AV : Is tAY t A' t own art 1 KM A, l, II, v z`g ; I01r, isj _j a Il1[I + "I W_N AV I to RIFwl 33 A z IN 4- oil I I 4, 4 zi! I"Y I A,A.suall " Ark3S I- AV SjNCr , All tl! Ar 00, r DOE S AV R, 35 d "'4501 AT AV MOD A113d is AV 14t01 •os R 7e 4 AY UQLXLU (NIS NIYW 2!e-im-, AV u E Will 4- itTs 11311f1N F.' m W AN Ila uM A, S IN I it al. AVXT 'IN S Y.................. it cSC )I)nljvlts Ill 4 I I 011v A-- meaty AV t X ..v vgwy NI J"I ER „f C, A N.% it r5 I WIN J_h t7? VA t; M oop AV W UN 1 ;z 00, tn,4 Al AY -MS !I1 1>AV - y) 1 LI MS AV7 VWK D YJJN3 PS AV 9 GN11 galil P, YA , " 38 vd, 001 1Y iS AV 31 R, 001 "Ad -Ar-y ,ffil 4 Al 113ROd FIGURE I SA 'flog ------ Ill A�IIIDVI i ;v v t-4.— VICINITY MAP Vol 1r"//,7:M K61 11rJUdAd00 dVW\__J:J33s LE=GTON RIDGE DEI # 87075 A?h o2b IN&N. om n R m IR) 11T TY71 Aiiaimt 7Q ]()()C) = r an m m r m m m m m m m m � m m m m PS At 7W Imo.�. ,•,- _ �—�° -_ _ 1 .�may.—y �, .. i /.. .. - �. \ ♦� w N �078 ♦ ` 1• /// ^/ _1 a� � _ alb A, \ / � �� r .0 r �'%�: 700d b \ �I• •, •�� ,may/ � � i r,�/ �, ' / % 11 , 1.1 11 -� ! .! t !. !t /r" ♦ / � �wY,. ♦ • :r/•\`•. , 71, �i '/ 'r% \/ r �. /.�t / /ter '�• . > dr CA I-TI t? i N J �•3 ~ � zrN ❑. PRELIMINARY CONDITIONS SUMMARY 1 1 1 1 II. PRELIMINARY CONDITIONS SUMMARY Some years ago, a portion of the site was operated as a gravel pit. The site is currently covered with second growth forest and is uninhabited and undeveloped. The site generally slopes to the west at approximately 14% gradient (See Figure 3 for existing site ' topography.) The site's soil is classified as Everett series, (SCS hydrologic Group A). Below the Everett sand and gravel are glacial till layers 5 to 27 feet below existing ground surface. Borings show this till material to have varying thickness: some layers being as thin as 2 to 3 feet. Below the till layer lies clean, fine to medium, compact sands. The developer proposes to grade the site in a manner which will expose some of the ' glacial till, which is classified as hydrological group C soil. Where excavation will expose glacial till, areas have been calculated by using the existing contours, proposed contours (existing on Figure 3 and proposed on Figure 5) and the Outwash Isopach (Figure 4A and ' 4B). The developed drainage basins map (Figure 5) shows which areas are classified as type A soils (Everett series), and which are type C soils (glacial till). Since buildings Q, R and S (adjacent to the PSPL ROW) will not drain to the detention facility, an infiltration system will be installed to infiltrate storm drainage from these buildings (see Figure 5). The infiltration rate in this area was field tested by Golder tAssociates Inc. (see GAI report #953-1195, dated May 21, 1996). •L,4o..R.. CE NT R O N I DEGROSS AERIAL MAPF „• �02� ++tT4 . E.ME wITE Ioo sc� ,•_� S n B R!G HTO N RIDGE 7Z 17520 eR+n.[We,WE c•n000 1 v w. .. q Y CQ47O''"; TOPOGRAPHIC SURVEY ee+e.t arar. Semi r. . 7 LEGEND APPROXIMATE AREA K.l1 Ia.aLl TaL / e • al..•U)Cr Tali � ox omowvmo-.a � 'p� ••• -� f<Ka R!T • !/R Y1.4 � ' 4 A515 OF BEARINGS* --- •ssocl.T eo•4 e•mr•� f Ie..a n.i am �/�- _ � % `I � \OT WNlTa• 4o J4D!•R P ...aLT - oc a+e cou4TT,+I•s.+ oyF a.I�a aT�w� 1Y // j/. VERTICAL DATUM= - �• V /`I/ / j / I \ ~ or c4To4 ,a,T�c•L o• —R...N•„a• IY/ i \\ DENrCHMARK=.^.Rt —u� . ta.•c.! / � e •�`�- - -� 'I) 4 \1` A:�"`�"� wJ.<a uT To ecauTlD s�oo. � I � �/ � ♦�f i avT.Wo}] O•I eT:. '•� NOTE-DO... ,� ^IO•OT rD�ovcT T•I! ,b•w.t _ //A7�/ - . ' . e^u4O.W RVCT Ot re•RO eERTY. `' S/�/- ._ / I \ I ,•lI1 �. J.ca uu,e.cou•T..,4�.a Ea..aD / , SIB � � I � .- xcaeo awove of T.•a swloeEa,v / `� � '\� /� • COR ♦J.WG44, �,.NLT O<r1T} ) 4 \11 .1 1// •_ n1, . T..•.Jr w..res,o•1•aces•r4„o..eaove• '� _ ' e 4nX IouE 4 n Is suwlT � � ' ' I 11 -.. ` D a•rTlq[i.04 E eo4..wR,. LG .,,•, .�` - I4cs xTc 4�D e. t ekeR � � i �� �1, � �... /•� � Ilj ill/ )� - i / III - 4E•30•I TO OU TMC.R uTM;E'.', � /. // \ I 1 fI '� / •II I I WE U4.T O4 eu•R C TD T • / ``• _. I r / • I IC? IV Ilk PrI .+� IaM •,' -/ � �- / \ �j>I YTi -• tar ,eJ`" - ,; r •r/ 1 ~ - - FIGURE 3 XISTING SITE TOPOGRAPM LEXINGTON RIDGE DEI # 87075 _ �� August 29, 1996 t-R- .!.'. X -i v % rc t �"q athletic k 34 leica y &2i: :b ET ,wt� �A!i if • Now 10 r_vu Ito. m r6' • W. Ike 'GRAVEL i.x pl, owl., 73.2�j 7t±7 Rc' 01. EIV,t- jl&N Ps � � ..: �s '� �r4x �� : a.`}.,*,,,:;��r �«�4'. •1`� 1, ` ��.J .�•� aa*;o,c+w�.,y -mp ff,4AF_l + � ,,� � y �1e\�+`. :.a� >,�xa � ���41��';i • �+.15 ern O �.y��1,�j '�i KV_ ATM 5tvi jyvc "NMI -I GURE 4 ORA ..I ArnCt . boo JJ' ta Orr SOILS MAP t �710x,ry ,'AV' p � 01 LEXINGTON RIDGE, D H IA 87075 a��na3� ,0 ar o T C�b�!, �•v e�lns r / b -rcb fs6 / r / IX � hz•dl L-dJ- 'e . f ,S rolx 1 vo,ra,ai I \ , of j 8z•dL o k ,'L � �11': 'I c t? ?( LI•d1I I / /I �Z•� Z_d� r� I hi'd l 1' A, ,y 11-d1 • ,76 •i. Ct7 q r,/s>�l� I/yJo, 40#V OS - .taUl� li+✓.•} /0�7 " � < - urn po; •p��J•L T�57 p�D up Fa$bq y54M�r0 J to SS1ttY7'r�. /•{j 'S f•I� c / (� NI�S� I 55,,A 7/7, I�/1 rt�pnl � � 0 '14 O"u rxoa d I d / e 0 l 4v;107O1 fle+ fs��f n 7P �..� Cr t.v �P�Accl ,r�s�va u»•n��9 s�) r. .�7rr�.� N Oo \ O H �J�b�i �C+rr1 t( cvml -lo �a fSd4�7ry1 q J O �p -lON �i T 07,1 f �f fr► w 7 p w 7t N 1� T s�1 /� cr o I� Gr a -7 CA tri C) ,V n a • O . a E x r /g n ti f +'o r, 7O �i X ;rest Pit Nan, ber atn d'App YdX,',.,., f C C,7 � N 3 / OGH J-io 1 U �' T-hickhesS of rii/ InditAled (Th%ckhess hetw�Gr eXisf9r+�yrw, d� ��� � �+ � a A � FinoJ9rgdt 4 � fcs� piflocAfion • /I prv,Y!-aaAte /SO�v4E � �v�? �0krf of 7-ill rah, ck;+eSS No 1 I 1' .gyp L� •,, ( I p-I I r T'P9 i r / / TF02, / j0�/ / +cs'X/�// � •'rP•2t ono / / /x 0.75' -t-r z s x -r•p-z Izi� x c / TP-z z I I TP'13 / \ 'TP-I 8 1 TP•(� X I x 4.9' T 7�\ \�(&75' \ SI T P.5, N% X o. TP 3 x 1 `m-q o. \ TP•zq '('P•zs o .1 ,rJ �'9krC � ISovacL /:;'aan • Ti// �rroa•t / - S RCDUGED RoAW, � _EXPOSED `\ ✓ !�c ;��`, ♦�� \\ TYPO C So1L EITyj v ovs SUTZI=�CE n r I1✓ � pie. - '\ '. .. _ •�{. - -, A TdTAL ti \tl/ FIGURE 5 DEVELOPED DRAINAGE BASINS LEXINGTON RIDGE a DEI# 87075 August 29, 1996 i ' III. LEVEL ONE DOWNSTREAM ANALYSIS Surface drainage leaves the site either to the west into an existing 12-inch underground conveyance system in Vuemont Place N.E. or to the southeast into the 3rd Street conveyance system. That water which flows to Vuemont is routed into the Bronson Way conveyance system where it is carried to a connection with the 3rd Street system just east of I-405. The Bronson Way system is all l 2-inch pipe at slopes in excess of 5% except for the last pipe run in the sequence before 3rd. St., which is an 8 inch pipe. The Settlement ' Agreement contemplates the replacement of this 8 inch diameter pipe. From the point where the Bronson Way and 3rd Street systems connect, flows from both tsystems are carried in an 18-inch pipe to a manhole within the I-405 right-of-way immediately east of the highway on the north side of 3rd Street. From this point, the ' flows are carried to the Cedar River through a 30-inch concrete pipe which crosses to the west of I-405 at the Maple Valley Highway. The state highway flows connect into this system at the spill containment pond west of I-405 and south of the Maple Valley ' Highway. We have been told by Renton staff that overflows occasionally occur at the 3rd Street manhole where the 30-inch pipe begins. Flows approaching the magnitude of 60 to 80 cfs have been calculated to occur at this point during severe storm events. By limiting the increase in flow from the Lexington site to no more than 0.5 cfs, Renton and the site owner have agreed this limitation will adequately mitigate the project's drainage impacts to the downstream system. See Table 1 for a description of the downstream system in tabular form. Following this table are reduced copies of the WSDOT plans which portray the downstream systems. r� rr �- sr rr �r rr �r +r rr r� r� r� r irr r �■r r� �r rr OFF-SITE ANALYSIS DRAINAGE SYSTEM TABLE Surface eater Design Manual, Core Requirement;#2 Basin Cedar-River Subbasin Name: Lower Cedar R ver Subbasin'Number: Symbol Drainage Drainace Component lope Distance Existing Potential Observations of field inspector Component Type, Description from site Problems Problems resource reNies�er,or resident :Fame,and Size discharge ape:sheet tow.sup e, oonstncuor,s,under capacity,ponding. sec map suearn,chant],pipe, drain--ce basin,vegetntion,corer, °0 U4 mi=1,320 ft overtoppinz,flooding,habitat or orearism uibu'ta.-y area,lti.-elihaod of problem, pond Size:diameter, depth type of sensitise arcs,volume des ruction scouring bsn} sloughing, oserilow pathu a}s,po;mtiel impacts. surface area sedimentation,incision,other erosion 12 inch concrete Vuepoint Pl.N.E.s.•stem 0- 150' main drainage course through road center,not through CBs 12 inch concrete Bronson Way sx,stem 150'-S00' underground pipe seems to be operating sufficiently cun-es around bend 8 inch concrete intersection,6viih N.E.3rd street S00'-900' constriction from 12 8 inch line should be replaced t%ith inch to 8 inch line 12 inch line 18 inch concrete N.E.3rd system 900'- 1100' occasionally operating sufficiently undercapacity 24 inch concrete I 105 RO.W. 1100'-2700' occasionally (30 inch?) existing pipe undercapacity 42 inch concrete I-405 RO.W. 2700'-3300' none new pipe draining to Cedar River TABLE 1 61 60 ' .-- 59 56 55 54 53 51 150 49 I _ _ - _�1�= IOFISER Y1AY 5_—_—__�--- ... CST POND 48 - - �---- _ rr�=t==r"' SPILI CONiAI 147 45 ......-------'- - 30"GONG 3 3 e44 �y `� \ �•`' Y �� -- 43 42 �41 0 L - -- ----3 ---- �\ --- 4----- ------------- 5 -II -_ __ ---- 62-? ` - - 1�:-�� 40 LID -- - - _ _ Y ra\ -- - - ----7nri:.Tm�n SR 900 39 138 J ----- `------------- -------------- -------- ---,---y------- =------------------ `----- - nn n,_=_ - - -=- - c l - rn x - 37 Z 0 8 9 -LI�1E- -NIo 27� 6 -- -- ---�'- --- �'- - -, - �6 J 4 8 S Z n° \� ---- t ti/--- 2 --- ------- 0 Ln ~ 35 Q 4 = 8''C►1P - - 4Z . w - Z L 1 t -- -- - - --^- -- -- - --- _-- N 34 ------� 3 0 -- -------------L - ` �o C U � e,. >{P 3 - 0 --- 3°''u _ 4 6- --- --- g_---- L_ - --- - �a ° --- - p-- J - o -- -�--__J• i Z �31 1.8 " - _ .___ 3029 28 E? - ,C° 0 1 I 125 �.� I ----- -.\ 24 ! 23 _f2 I 20 A 19 18 17 16 - i 14 13 % __ja d - 2 FORLEGEND SEE SHEET D-1 i �uli I 10 1Qi l 0 50 1o0 7 SCALE IN FEET v ,"`NO TAT FED.AID PROJ.NO. RICH DESIGNED BY M. SENSOR WAY DIVISION W3 ENTERED BY S. SENSOR AN 10 WASH Washington State SR 405 . CHECKED BY C. YEBBER / Y. SENSOR - Deportment of Transportation SOUTH RENTON TO SUNSET BLYD.-HOY I-IR-405 3(783) �n �a urlER PROJ. ENGR. J. JOHNSON 12-6-91 ADDED DRAINAGE STRUCTURES RL 9Iwo97 015T. ADM. R.O. ANDERSON DRAINAGE PLAN i 1 10-21-91 ADDED DRAINAGE CODES RL cat" NO- re.�ai�nnn.x�tnoir ntN .0 57 _ i3 •_ �.. - w � ill ►��� 1 � .. .. _ 1 1 1 O is Lip:�.j T I 4T d1 1 p Y '-------------- - - - �\ -- ........-._.tea-aa�-,-- - -Y1_ _ ___ �,�..� - -_ Hri ,�rr_i _ i �r,>r ir_T il»ll>-T�/).>1/_r-•l T-.r_/-J/-/)__l l T1-T__i•?i/_)-)�Y�i-i iI1�_-_ Ii II ----=====3----1----_—o -SUNSET-BLVO. N-E.4 )O I� 1-_ --- -— -- _ --- l------- -_ -_�------_--- - - _ y.� ---_ _Tam-_��� L �•.r— — _ ———— -0 _'- -•_.-._ _ _ - / t l A -•-- �/� t (� T i i�.\ \ �: _p---� sir p 3 � — _ � -_'�_�':';,S�.a 2 •� \ 1 � / / / /.�:�/• O 1 It 37 t' •" .�.� 1, �\�\// / / j/ // AS?HALT I -:\_ 34 °--o-JOoCONC 0 "r ------------------- m W CCNC I o. I // // -_ 1 - - - «1 --- ---------- - - - _�z- D 2 -- --- - ---"-------_-Dj'•`9�_�..� o- v �l7cy ------------- 21 /• / E l °�h/ 9�/ CONC Cb of �. cli 14 1 �' ----------------- '�� !ram t ! i� t � � r r }~ _ �•♦ 111 It lui zi GEN rll/ , `E D SEE S: ��=D_1� _._._"-• 8 50 100 SCALE IN FEET -- _ - AECI Q"STATE FED.AID PROJ.NO. H IGHWAY DIVISION DESIGNED BY W. SENSOR 10 WASH _� wash i ngton State SR 405 0- NTERED BY S. STRASSMAN Department of Transportation SOUTH RENTON TO SUNSET BLVD.-HOV = NECKED BY G. VEBB R'/ V. SENSOR JO'"°�" I-IR-405-3(783) T�- PROJ. ENGR. J. JOHNSON 91W097 I� 1 DIST. ADN. R.Q. ANOERSON 10-21-SI ADDED DRAINAGE CODES RL MTIUCT a• DRAINAGE PLAN DATE DATE REVISION BY zc.�taoownl.o�Tv xwt lo= I _ ZJNa9Ro5Eo9W . Mo \ •\ �'Y�. ice-{_ I _'.� 1 I I 1 i1i� _O�•.` O .? is / _6 _ _ _. -� -•---------.. ----•-- - - -. ,� } - - - - - _� 17 cli N _ � ul N Zs PIII CONTAINIdENT POND'-_� uj 4 A 8"UD A 2 - -- -__ - 8"UD ----------------- � \ Y :E ........................................ __ _ ___ \ \ ♦ \ \\� �• FRONTAGE RD. - --- --- - ------ -- -- - ` Z\ r FOR LEGEND SEE SHEET D-1 SRR `N6 N o so ioo SCALE IN M-, STATO FED.AID PROJ.NO. ?ESICNEO BY w. SENSOR HIGHWAY p[VISION 10 WASH RED BY S. STRASSMaN AMW x >rashington State SR 405 0-� ED BY c. MEBBER / v. S NSOR Department of Transportation SOUTH RENTON TO SUNSET BLVD.-HOY -- -•-- - 17-6-91 Annelt nQATUArc CTD11rTnnce of 91W(1Q7 3(783) s-u ' IV. RETENTION/DETENTION ANALYSIS AND DESIGN 1 1 IV. RETENTION/DETENTION ANALYSIS AND DESIGN ' Design Criteria The Settlement Agreement has established the criteria to be used for design of the ' detention/water quality vault. As presented earlier, the detention volume will be calculated by allowing limited increases to the existing off site flow rates. The post development outflow increases from the Lexington Ridge site for the 2-year through the ' 100-year design events should not exceed the values given in the table below: ' Return Interval Increment above undeveloped flow(cfs 2 year 0.44 ' 10 year 0.44 25 year 0.50 100 year 0.50 Rates will be established by the SBUH method per the Kin Count Surface p g y Water Design Manual. ' Existing Conditions ' The precipitation for the 2-year, 10-year, 25-year, and 100-year 24-hour storm events, as taken from the 1990 King County Surface Water Design Manual, are as follows: ' P2 = 2.0 inches P,o = 2.9 inches P25 = 3.4 inches P100 = 3.9 inches The existing site, as shown on Figure 3, is divided into two basins; one discharging to Bronson and one to 3rd. We have combined the discharges from both basins into one as though they both drain to Bronson. The two outflows from the undeveloped site currently join less than one quarter mile downstream at 3rd and Bronson, which is where our ' developed site outflow will be discharged. This validates our approach to establishing one total outflow from the site. Also, since the existing improved Vuemont road will not be ' altered, and this analysis for detention and outflow limits is predicated on incremental increases, the Vuemont road below the detention system will be excluded from the calculations. MOM wo Idubg SOMICU911:1 IFTIV KING COUNTY, WASHINGTON, S URFACE WATER DESIGN MANUAL FIGURE 3.5.1E 10-YEAR 24-HOUR ISOPLUVIALS 2.1 2 _ - 24 26 .29 ww. �• t� rnel 3.0 Uj.. uE 1"0 ter• \ .l -1 wtew\• „t,,,a 32 33 ' / a Y— �r.r r—•�`.� `" *won _ '�. }• Kam•. ... lm r r /' 10-YEAR 24-HOUR PRECIPITATION r ISOPLUVIALS OF 10-YEAR 24-HOUR �'� �• � TOTAL PRECIPITATION IN INCHES ' 0 1 2 3 4 3 6 7 8 Mlle: �—o-_`—>— ram—'_t+_'--� �1• i w 'S=r. _•� KING COUNTY, WASHINGTON, SURFACE WATER DESIGN MANUAL FIGURE 3.5.1F 25-YEAR 24-HOUR ISOPLUVIALS 30 4 cp 5.5 Y- L -� - 1 .5-YEAR 24-HOUR PRECIPITATION SS 3.4 ISOPLUVIALS OF 25-YEAR 24-HOUR __,_.� ,W -- .y S.p�•' TOTAL PRECIPITATION IN INCHES 0 1 2 3 4 3 6 7 8 Mlles 3.5.1-11 �'�� Q =='`�°�-'•► 1:300.000 mat ME 9/ 6/96 Dodds Engineers, Incorporated page 6 DEI# 87075 LEXINGTON RIDGE ---------------- ------------------------------------- ' BASIN SUMMARY ' BASIN ID: EX002 NAME : Existing 2 year event SBUH METHODOLOGY TOTAL AREA. . . . . . . : 11 . 34 Acres BASEFLOWS : 0 . 00 cfs RAINFALL TYPE. . . . : USER1 PERVIOUS AREA PRECIPITATION. . . . : 2 . 00 inches AREA. . : 11 . 34 Acres TIME INTERVAL. . . . : 10 . 00 min CN. . . . : 55 . 00 TIME OF CONC. . . . . : 29 . 20 min IMPERVIOUS AREA ' ABSTRACTION COEFF: 0 . 20 AREA. . : 0 . 00 Acres CN. . . . . 98 . 00 TcReach - Sheet L: 300 . 00 ns : 0 .4000 p2yr: 2 . 00 s : 0 . 2000 ' TcReach - Shallow L: 300 . 00 ks :5 . 00 s : 0 . 1000 PEAK RATE: 0 . 04 cfs VOL: 0 . 01 Ac-ft TIME : 1440 min BASIN ID: EX010 NAME : EXISTING 10 YEAR - 1996 SBUH METHODOLOGY ' TOTAL AREA. . . . . . . : 11 . 34 Acres BASEFLOWS : 0 . 00 cfs RAINFALL TYPE . . . . : USER1 PERVIOUS AREA PRECIPITATION. . . . : 2 . 90 inches AREA. . : 11 . 34 Acres TIME INTERVAL. . . . : 10 . 00 min CN. . . . : 55 . 00 TIME OF CONC. . . . . : 29 . 20 min IMPERVIOUS AREA ABSTRACTION COEFF: 0 . 20 AREA. . : 0 . 00 Acres CN. . . . : 98 . 00 PEAK RATE: 0 . 19 cfs VOL: 0 . 16 Ac-ft TIME : 1440 min BASIN ID: EX025 NAME : EXISTING 25 YEAR - 1996 SBUH METHODOLOGY TOTAL AREA. . . . . . . : 11 . 34 Acres BASEFLOWS : 0 . 00 cfs RAINFALL TYPE. . . . : USER1 PERVIOUS AREA PRECIPITATION. . . . : 3 .40 inches AREA. . : 11 . 34 Acres TIME INTERVAL . . . . . 10 . 00 min CN. . . . . 55 . 00 TIME OF CONC. . . . . : 29 .20 min IMPERVIOUS AREA ABSTRACTION COEFF: 0 .20 AREA. . : 0 . 00 Acres CN. . . . . 98 . 00 PEAK RATE : 0 . 30 cfs VOL: 0 . 30 Ac-ft TIME : 1440 min ' BASIN ID: EX100 NAME : EXISTING 100 YEAR - 1996 SBUH METHODOLOGY TOTAL AREA. . . . . . . : 11 .34 Acres BASEFLOWS : 0 . 00 cfs RAINFALL TYPE . . . . : USER1 PERVIOUS AREA { PRECIPITATION. . . . : 3 . 90 inches AREA. . : 11 . 34 Acres TIME INTERVAL. . . . : 10 . 00 min CN. . . . : 55 . 00 TIME OF CONC. . . . . : 29 . 20 min IMPERVIOUS AREA ABSTRACTION COEFF: 0 .20 AREA. . . 0 . 00 Acres CN. . . . . 98 . 00 ' PEAK RATE : 0 .41 cfs VOL: 0 .46 Ac-ft TIME : 1440 min ' EXISTING SITE FLOW RATES ' The following existing flow rates were computed using the WaterWorks program. EVENT BASIN NAME PEAK RATE VOLUME ' 2-yr event XE002 0.04 cfs 0.01 Ac-ft 10-yr event XE010 0.19 cfs 0.16 Ac-ft 25-yr event XE025 0.30 cfs 0.30 Ac-ft 100-yr event XE 100 0.41 cfs 0.46 Ac-ft The data entered into the WaterWorks program for existing conditions was collected as ' follows: Area - scaled from a site map using a planimeter ' Time of Concentration - computed by entering the travel distance, existing surface conditions and travel mode (sheet, shallow, channel) into the program Pervious/Impervious Area - initially all area is assumed to be pervious ' Curve Number, CN - taken from the K.C. Surface Water Design Manual, Table 3.5.213 SCS WESTERN WASHINGTON RUNOFF CURVE NUMBERS (Published by SCS in 1982) Runoff curve numbers for selected agricultural, suburban and urban land use for Type 1A rainfall distribution, 24-hour storm duration. ' CURVE NUMBERS BY HYDROLOGIC SQ&GROUP LAND USE DESCRIPTION A B C D ' Cultivated land(1): winter condition 86 91 94 95 Mountain open areas: low growing brush and grasslands 74 82 89 92 Meadow or pasture: 65 78 85 89 Wood or forest land: undisturbed or older second growth 64 76 81 Wood or forest land: young second growth or brush 55 72 81 86 Orchard: with cover crop 88 92 94 Open spaces, lawns, parks, golf courses, cemeteries, landscaping. good condition: grass cover on 75% or more of the area 80 (�) 90 fair condition: grass cover on 50% to 75% of the area 77 85 90 92 Gravel roads and parking lots 76 85 89 91 Dirt roads and parking lots 72 82 87 89 ' Impervious surfaces, pavement, roofs, etc. 98 98 98 98 Open water bodies: lakes, wetlands, ponds, etc. 100 100 100 100 ' The following page contains print outs for the Existing 2, 10, 25 and 100 year storm event. ' Developed Conditions ' The developed site consists of four separate basins, totaling 13.4 acres (see Figure 5 for developed drainage basins). One area will completely infiltrate the stormwater from roofs and landscaped areas (Infiltration Basin). A small area on the south property line (Bypass Area) will remain in its natural condition and will continue to drain naturally to the south. Vuemont road has been discussed above in the Existing Conditions section. The infiltration, bypass area and Vuemont road flows have not been added to the detention ' calculations, since they will not be directed to the detention vault. The bulk of the site will drain to the wetvault/ detention vault. As outlined in Section II of this report, Preliminary Conditions Summary, the site will be graded to expose some of the glacial till. This requires the site to be modeled using type A soil for the outwash sand, type C for the exposed till and the remainder will be impervious surface (see Figure 5). BASIN AREA PERVIOUS AREA IMPERVIOUS AREA ' TOTAL SITE 12.7 AC 5.7 AC 7.7 AC INFILTRATION 1.0 AC 0.7 AC, CN= 68 0.3 AC, CN= 98 BASIN BYPASS AREA 0.5 AC 0.5 AC, CN= 55 0 AC DEVELOPED 11.3 AC 2.8 AC, CN= 68 6.94 AC, CN = 98 ' CONDITION 1.6 AC, CN = 86 (4.4 AC, AVG CN = 74.5 The areas in the above table were scaled from a site map using a planimeter ' DEVELOPED SITE FLOW RATES 1 The following developed flow rates were computed using the WaterWorks program. EVENT BASIN NAME PEAK RATE VOLUME ' 2-yr event DE002 3.28 cfs 1.16 Ac-ft 10-yr event DE010 5.36 cfs 1.86 Ac-ft 25-yr event DE025 6.58 cfs 2.27 Ac-ft ' 100-yr event DE 100 7.83 cfs 2.69 Ac-ft 6-month event DE6MO 0.85 cfs 0,27 Ac-ft The data entered into the WaterWorks program for developed conditions was collected as follows: Time of Concentration - computed by entering the travel distance, existing surface conditions and travel mode (sheet, shallow, channel) into the program Pervious/Impervious Area - initially all area is assumed to be pervious ' Curve Number, CN - taken from the K.C. Surface Water Design Manual, Table 3.5.213 The following pages contairL printouts for the Existing 2, 10, 25 and 100 year storm event. 9/ 6/96 page 2 ' DEI# 87075 LEXINGTON RIDGE --------------------------------------------------------------------- --------------------------------------------------------------------- BASIN SUMMARY ' BASIN ID: DE002 NAME : DEVELOPED 2 YEAR SBUH METHODOLOGY TOTAL AREA . . . . . . . : 11 . 34 Acres BASE17LOWS : 0 . 00 cfs RAINFALL TYPE . . . . : USER1 PERVIOUS AREA PRECIPITATION. . . . : 2 . 00 inches AREA . . : 4 . 40 Acres TIME INTERVAL . . . . : 10 . 00 min CN . . . . : 74 . 52 TIME OF CONC . . . . . : 9 . 74 min IMPERVIOUS AREA ABSTRACTION COEFF . 0 . 20 AREA . . : 6 . 9'4 Acres CN. . . . . 98 . 00 ' TcReach - Sheet L : 50 . 00 ns : 0 . 1500 p2yr : 2 . 00 s : 0 . 0200 TcReach - Shallow L : 100 . 00 ks : 27 . 00 s : 0 . 0700 TcReach - Channel L : 850 . 00 kc: 21 . 00 s : 0 . 0800 PEAK RATE : 3 . 28 cfs VOL : 1 . 16 Ac-ft TIME : 480 min ' BASIN ID: DE010 NAME: DEVELOPED 10 YEAR SBUH METHODOLOGY TOTAL AREA . . . . . . . . 11 . 34 Acres BASEFLOWS : 0 . 00 cfs RAINFALL TYPE . . . . : USER1 PERVIOUS AREA ' PRECIPITATION. . . . : 2 . 90 inches AREA. . : 4 . 40 Acres TIME INTERVAL . . . . : 10 . 00 min CN. . . . : 74 . 52 TIME OF CONC . . . . . : 9 . 74 min IMPERVIOUS AREA ABSTRACTION COEFF : 0 . 20 AREA. . : 6 . 94 Acres CN. . . . : 98 . 00 TcReach - Sheet L : 50 . 00 ns : 0 . 1500 p2yr : 2 . 00 s : 0 . 0200 ' TcReach - Sha.l. low L : 100 . 00 ks : 27 . 00 s : 0 . 0700 TcReach - Channel L : 850 . 00 kc : 21 . 00 s : 0 . 0800 PEAK RATE : 5 . 36 cfs VOL : 1 . 86 Ac-ft TIME : 480 min BASIN ID: DE025 NAME : DEVELOPED 25 YEAR ' SBUH METHODOLOGY TOTAL AREA . . . . . . . : 11 . 34 Acres BASEFLOWS : 0 . 00 cfs RAINFALL TYPE . . . . : USER1 PERVIOUS AREA PRECIPITATION. . . . : 3 . 40 inches AREA . . : 4 . 40 Acres TIME INTERVAL . . . . : 10 . 00 min CN. . . . : 74 . 52 TIME OF CONC. . . . . . 9 . 74 min IMPERVIOUS AREA ABSTRACTION COEFF : 0 . 20 AREA . . : 6 . 94 Acres ' CN. . . . : 98 . 00 TcReach - Sheet L : 50 . 00 ns : 0 . 1500 p2yr : 2 . 00 s : 0 . 0200 TcReach - Shallow L : 100 . 00 ks : 27 . 00 s : 0 . 0700 ' TcReach - Channe.1 L : 850 . 00 kc : 21 . 00 s : 0 . 0800 PEAK RATE : 6 . 58 cfs VOL : 2 . 27 Ac-ft TIME : 480 min ' 9/ 6/96 Dodds Engineers, Incorporated page 3 LEXINGTON RIDGE DEI# 87075 ! � BASIN SUMMARY ' BASIN ID: DEI00 NAME : DEVELOPED 100 YEAR SBUH METHODOLOGY TOTAL AREA . . . . . . . . 11 . 34 Acres BAST-FLOWS : 0 . 00 ci's RAINFALL 'TYPE . . . . : USER1 PERVIOUS AREA ' PRECIPITAT.ION. ,. . . : 3 . 90 inches AREA . . : 4 . 40 Acres TIME INTERVAL . . . . : 10 . 00 min CN . . . . : 74 . 52 TIME OF CONC. . . . . . 9 . 74 min IMPERVIOUS AREA ABSTRACTION COEFF: 0 . 20 AREA . . : 6 . 94 Acres CN. . . . : 98 . 00 TcReach - Sheet L : 50 . 00 ns : 0 . 1500 p2yr : 2 . 00 s : 0 . 0200 ' TcReach - Shallow L : 100 . 00 ks : 27 . 00 s : 0 . 0700 TcReach - Channel L : 850 . 00 kc: 21 . 00 s : 0 . 0800 PEAK RATE . 7 . 83 cfs VOL : 2 . 69 Ac-ft TIME : 480 min BASIN ID: DE6M0 NAME : DEVELOPED 6 MONTH ( 1/3 2 YR) SBUH METHODOLOGY TOTAL AREA . . . . . . . : 11 . 34 Acres BASE17LOWS : 0 . 00 cfs RAINFALI. TYPE . . . . : USER1 PERVIOUS AREA PRECIPITATION. . . . . 0 . 67 inches AREA . . : 4 . 40 Acres ' TIME INTERVAL . . . . : 10 . 00 min CN . . . . : 74 . 52 TIME OF CONC. . . . . : 9 . 74 min IMPERVIOUS AREA ABSTRACTION COEFF : 0 . 20 AREA . . : 6 . 94 Acres CN . . . . . 98 . 00 ' TcReach - Sheet L : 50 . 00 ns : 0 . 1500 p2yr : 2 . 00 s : 0 . 0200 TcReach - Shall.ow L : 100 . 00 ks : 27 . 00 s : 0 . 0700 TcReach - Channel L : 850 . 00 kc : 21 . 00 s : 0 . 0800 ' PEAK RATE : 0 . 85 cfs VOL: 0 . 27 Ac-ft TIME : 480 min i� A combined wetvault/detention vault will be located in the northwest corner of the site; southwest of the main (Vuemont) access road. This provides the lowest point for discharge and drainage to the existing drainage system in Vuemont Way. ' The wetvault has been designed to the specifications of the Kin Count Surface Water g p g Y ' Design Manual, section 4.6.3. A volume of dead storage (wetpond) must be equal to or greater than the volume of the annual storm(P2/3). As calculated in the WaterWorks stormwater model, the annual storm has a volume of 0.27 ac-ft or 11,761 CF. See Figure 6 for combined wetvault/detention vault design.. The detention criteria and required volumes are summarized below: 2 YEAR 10 YEAR 25 YEAR 100 YEAR EXISTING FLOW 0.04 CFS 0.19 CFS 0.30 CFS 0.41 CFS ' ALLOWED SITE FLOW 0.48 CFS 0.63 CFS 0.80 CFS 0.91 CFS BYPASS FLOW 0.00 CFS 0.01 CFS 0.02 CFS 0.02 CFS ' DESIGN FLOW 0.39 CFS 0.63 CFS 0.80 CFS 0.91 CFS DEVELOPED FLOW 3.43 CFS 5.60 CFS 6.87 CFS 8.17 CFS ROUTED FLOW 0.39 CFS 0.63 CFS 0.80 CFS 0.91 CFS DETENTION VOLUME 26,112 CF 43,209 CF 1 51,415 CF 1 62,388 CF The size of the vault was determined by taking the water quality storage of approximately 12,000 CF and adding that to the 100 year storm event requirement of 62,388 CF. This volume was checked with available surface area, to determine feasibility and design depth. The planned surface area of 40 feet by 200 feet and maximum depth for system drainage ' was developed into a stage storage. This stage storage, ID STAGE, was entered into the WaterWorks program, and all design storm events were routed through. Discharge from the vault was not to exceed the Design Flow listed in the table above. A multiple orifice ' discharge structure, ID ORIFI, was designed to achieve these results. See Figure 6 for vault dimensions and geometry. ' The Level Pool Table Summary shows the elevation and storage volume for each storm event. LEVEL POOL TABLE SUMMARY MATCH INFLOW -STO- -DIS- <-PEAK-> <--- -----DESCRIPTION---------> (Cfs) (cfs) --id- --id- <-STAGE> 2 YR . . . . . . . . . . . . . . . . . . . . . . . . . 0 .48 3 .28 STAGE ORIFI 182 .35 10 YR . . . . . . . . . . . . . . . . . . . . . . . . 0 . 63 5 .36 STAGE ORIFI 185 .20 25 YR 0 . 80 6 .58 STAGE ORIFI 186 .55 100 YR . . . . . . . . . . . . . . . . . . . . . . . 0 . 91 7 . 83 STAGE ORIFI 187 . 92 The following pages give a detailed stage storage and discharge report. ' 10/ 8/96 Dodds Engineers, Incorporated page 2 LEXINGTON RIDGE DEI# 87075 ' STAGE STORAGE TABLE CUSTOM STORAGE ID No. STAGE Description: ' STAGE <----STORAGE----> STAGE <----STORAGE----> STAGE <----STORAGE----> STAGE <----STORAGE----> (ft) ---cf--- --Ac-Ft- (ft) ---cf--- --Ac-Ft- (ft) ---cf--- --Ac-Ft- (ft) ---cf--- --Ac-Ft- 178.00 0.0000 0.0000 182.20 25200 0.5785 186.40 50400 1.1570 190.60 83800 1.9238 178.10 600.00 0.0138 182.30 25800 0.5923 186.50 51000 1.1708 190.70 84600 1.9421 178.20 1200 0.0275 182.40 26400 0.6061 186.60 51800 1.1892 190.80 85400 1.9605 178.30 1800 0.0413 182.50 27000 0.6198 186.70 52600 1.2075 190.90 86200 1.9789 178.40 2400 0.0551 182.60 27600 0.6336 186.80 53400 1.2259 191.00 87000 1.9972 ' 178.50 3000 0.0689 182.70 28200 0.6474 186.90 54200 1.2443 191.10 87800 2.0156 178.60 3600 0.0826 182.80 28800 0.6612 187.00 55000 1.2626 191.20 88600 2.0340 178.70 4200 0.0964 182.90 29400 0.6749 187.10 55800 1.2810 191.30 89400 2.0523 178.80 4800 0.1102 183.00 30000 0.6887 187.20 56600 1.2994 191.40 90200 2.0707 178.90 5400 0.1240 183.10 30600 0.7025 187.30 57400 1.3177 191.50 91000 2.0891 179.00 6000 0.1377 183.20 31200 0.7163 187.40 58200 1.3361 191.60 91800 2.1074 179.10 6600 0.1515 183.30 31800 0.7300 187.50 59000 1.3545 191.70 92600 2.1258 ' 179.20 7200 0.1653 183.40 32400 0.7438 187.60 59800 1.3728 191.80 93400 2.1442 179.30 7800 0.1791 183.50 33000 0.7576 187.70 60600 1.3912 191.90 94200 2.1625 179.40 8400 0.1928 183.60 33600 0.7713 187.80 61400 1.4096 192.00 95000 2.1809 179.50 9000 0.2066 183.70 34200 0.7851 187.90 62200 1.4279 192.10 95800 2.1993 ' 179.60 9600 0.2204 183.80 34800 0.7989 188.00 63000 1.4463 192.20 96600 2.2176 179.70 10200 0.2342 183.90 35400 0.8127 188.10 63800 1.4646 192.30 97400 2.2360 179.80 10800 0.2479 184.00 36000 0.8264 188.20 64600 1.4830 192.40 98200 2.2544 ' 179.90 11400 0.2617 184.10 36600 0.8402 188.30 65400 1.5014 192.50 99000 2.2727 180.00 12000 0.2755 184.20 37200 0.8540 188.40 66200 1.5197 192.60 99800 2.2911 180.10 12600 0.2893 184.30 37800 0.8678 188.50 67000 1.5381 192.70 100600 2.3095 ' 180.20 13200 0.3030 184.40 38400 0.8815 188.60 67800 1.5565 192.80 101400 2.3278 180.30 13800 0.3168 184.50 39000 0.8953 188.70 68600 1.5748 192.90 102200 2.3462 180.40 14400 0.3306 184.60 39600 0.9091 188.80 69400 1.5932 193.00 103000 2.3646 180.50 15000 0.3444 184.70 40200 0.9229 188.90 70200 1.6116 193.10 103800 2.3829 ' 180.60 15600 0.3581 184.80 40800 0.9366 189.00 71000 1.6299 193.20 104600 2.4013 180.70 16200 0.3719 184.90 41400 0.9504 189.10 71800 1.6483 193.30 105400 2.4197 180.80 16800 0.3857 185.00 42000 0.9642 189.20 72600 1.6667 193.40 106200 2.4380 ' 180.90 17400 0.3994 185.10 42600 0.9780 189.30 73400 1.6850 193.50 107000 2.4564 181.00 18000 0.4132 185.20 43200 0.9917 189.40 74200 1.7034 193.60 107800 2.4747 181.10 18600 0.4270 185.30 43800 1.0055 189.50 75000 1.7218 193.70 108600 2.4931 181.20 19200 0.4408 185.40 44400 1.0193 189.60 75800 1.7401 193.80 109400 2.5115 181.30 19800 0.4545 185.50 45000 1.0331 189.70 76600 1.7585 193.90 110200 2.5298 181.40 20400 0.4683 185.60 45600 1.0468 189.80 77400 1.7769 194.00 111000 2.5482 181.50 21000 0.4821 185.70 46200 1.0606 189.90 78200 1.7952 194.10 111800 2.5666 ' 181.60 21600 0.4959 185.80 46800 1.0744 190.00 79000 1.8136 194.20 112600 2.5849 181.70 22200 0.5096 185.90 47400 1.0882 190.10 79800 1.8320 194.30 113400 2.6033 181.80 22800 0.5234 186.00 48000 1.1019 190.20 80600 1.8503 194.40 114200 2.6217 ' 181.90 23400 0.5372 186.10 48600 1.1157 190.30 81400 1.8687 194.50 115000 2.6400 182.00 24000 0.5510 186.20 49200 1.1295 190.40 82200 1.8871 182.10 24600 0.5647 186.30 49800 1.1433 190.50 83000 1.9054 10/ 8/96 Dodds Engineers, Incorporated page 4 LEXINGTON RIDGE DEI# 87075 STAGE DISCHARGE TABLE MULTIPLE ORIFICE ID No. ORIFI Description: Outlet Elev: 178 . 00 ' Elev: 176 . 00 ft Orifice Diameter: 2 . 6300 in. Elev: 182 . 80 ft Orifice 2 Diameter: 1 . 7500 in. Elev: 185 . 30 ft Orifice 3 Diameter. 1 . 7500 in. ' STAGE <--DISCHARGE---> STAGE <--DISCHARGE---> STAGE <--DISCHARGE---> STAGE <--DISCHARGE---> (ft) ---Cfs-- ------- (ft) ---Cfs-- ------- (ft) ---Cfs-- ------- (ft) ---cfs-- ------- 178.00 0.0000 181.10 0.3305 184.20 0.5657 187.30 0.8662 178.10 0.0594 181.20 0.3358 184.30 0.5729 187.40 0.8742 178.20 0.0839 181.30 0.3410 184.40 0.5800 187.50 0.8820 178.30 0.1028 181.40 0.3461 184.50 0.5869 187.60 0.8897 178.40 0.1187 181.50 0.3512 184.60 0.5937 187.70 0.8973 178.51 0.1327 181.61 0.3161 184.71 0.6114 187.80 0.9048 ' 178.60 0.1454 181.70 0.3611 184.80 0.6070 187.90 0.9123 178.70 0.1570 181.80 0.3659 184.90 0.6135 188.00 0.9196 178.80 0.1679 181.90 0.3707 185.00 0.6199 188.10 0.9269 ' 178.90 0.1781 182.00 0.3754 185.10 0.6262 188.20 0.9341 179.00 0.1877 182.10 0.3801 185.20 0.6324 188.30 0.9413 179.10 0.1969 182.20 0.3847 185.30 0.6386 188.40 0.9483 179.20 0.2056 182.30 0.3892 185.40 0.6709 188.50 0.9553 179.30 0.2140 182.40 0.3937 185.50 0.6878 188.60 0.9622 179.40 0.2221 182.50 0.3982 185.60 0.7020 188.70 0.9691 179.50 0.2299 182.60 0.4026 185.70 0.7149 188.80 0.9759 ' 179.60 0.2374 182.70 0.4069 185.80 0.7269 188.90 0.9827 179.70 0.2447 182.80 0.4112 185.90 0.7383 189.00 0.9893 179.80 0.2518 182.90 0.4418 186.00 0.7491 189.10 0.9960 ' 179.90 0.2587 183.00 0.4569 186.10 0.7595 189.20 1.0025 180.00 0.2655 183.10 0.4694 186.20 0.7696 189.30 1.0091 180.10 0.2720 183.20 0.4806 186.30 0.7794 189.40 1.0155 180.20 0.2784 183.30 0.4909 186.40 0.7889 189.50 1.0220 ' 180.30 0.2847 183.40 0.5006 186.50 0.7981 189.60 1.0283 180.40 0.2908 183.50 0.5097 186.60 0.8072 189.70 1.0347 180.50 0.2968 183.60 0.5185 186.70 0.8161 189.80 1.0410 ' 180.60 0.3027 183.70 0.5270 186.80 0.8248 189.90 1.0472 180.70 0.3084 183.80 0.5352 186.90 0.8334 190.00 1.0534 180.80 0.3141 183.90 0.5431 187.00 0.8418 180.90 0.3196 184.00 0.5508 187.10 0.8501 181.00 0.3251 184.10 0.5584 187.20 0.8582 DDDDS ENGINEERS, INC. JOB NO. g_�O_pS CIVIL ENGINEERING S U R V EYING PLANNING -�E-P ,Jh 4205 146TH AVE. N.E., SUITE 200 DATE BELLEVUE. WA JB007 l/ (2061 665-7877 OR 454-3743 B Y -RS PROPOSED WE-TVPU(-"T- DE T-KMoN yFlULT T-N FL O W Wo STopA6C- ZZWO T►JELOW WEIR 12,000 cF ACCESS (rvP) LUnI FLOWS — e76AfrLF_ WO OUTFLOW t L 1\/E STU 2A C�E W E I _____J ' � wE)l2 - YI►�,�-I Lows A --- 2 00" �I ' LIVE PLA N STbRAC C C g wf-:l r EL )87.0a _ ICU vEFi1Z H 1 hH WA rt-rz 1 el.5 2 ' - LOW FLOW LNE 6. \AlO OVMLOW ' ST0RA6�63,000 cF w�R o.s % EL IS&.ZS ' DRAIN VALVES SECT ioN A- A E3 ' C ' --- — E L 190.0 n WO STOPAW — C� 16940 /�FlrTLe ' Uvr sro2nC,E RCST2ICT0R TNFLoW CL I P'o•u0:I: tr=T EL 17 .00 i --' EL 1-75,00 ° PPZA�NJ ' VALVES SECVON f3 - F3 SEC^flbl�l C_G C�U12� SHEET OF DETENTION VAULT OPERATION ' The wetvault/detention vault has been designed to provide water quality treatment and provide adequate storage for the 100 year storm event. The water quality portion of the vault is almost completely taken off line while handling large storm events. This is achieved by allowing water entering the vault to be directed into the water quality section up to the WQ event, above which, the water is diverted into through a side weirs to live storage. A baffle has been designed into the center of the water quality section, to assist ' with oil/water and debris separation and to eliminate short circuits. Water entering the live storage via the water quality outflow weir and via the live storage weir is discharged through the restrictor (see Figure 7). Drain valves and access hatches have been added to the vault to enable cleaning. The maximum water elevation for the 100 year storm event will be at 187.90. D O D D S ENGINEERS, INC. JOB NO. 8�1T1S CIVIL ENGINEERING SURVEYING PLANNING DATE �- SGT �6 4205 ,46TH AVE. N.E., SUITE 200 - BELLEVUE. WA 96007 (2061 865-7677 OR 454-3743 B Y ' — VAUt--1 70P n- 190 ,a. t_ 0 MAX W.5, _ E L I SS.00 METAL STRAP ©R)FICE EL I>�J5,3fl D)A ---'"� STANDARD ATE PS ' ORIFICE EL I SZ,00 0 DIA --�� ' I�. I�8 ,oo „ OR1F►C� a/ EL 17-7.00 2.625 n Al A HOLE 'T" PLATE ' 0 SUMP 1307MAA EL, 1-74,00 PRUPDSED WCTVAUL-T l i)cTc--v)-noNl VAUUT T?U ''T-)CTOR 1 RE SHEET ' KING COUNTY, WASHINGTON, SURFACE WATER DESIGN MANUAL FIGURE 4.4.7J RISER INFLOW CURVES ' Weir Flow Orifice Flow ----- 100 ' �. 36 33 30 27 C 0 24 c N a � 21 ` Cu a� 18 E ' Ta U Q 0 15 0 . 12 10 ' 10 1 — 0.1 .0 10.0 HEAD IN FEET (meas red from crest of riser) 1 + 0 .91 SOURCE: USDA-SCS WIER 0ORIFICE = 3.782 D2H'n Q-A(� Q in cfs, D and H in feet ' 4.4.7-10 1/90 IV.A. INFILTRATION SYSTEM DESIGN 1 ' INFILTRATION SYSTEM DESIGN ' As discussed earlier, Buildings Q, R and S will be equipped with an infiltration trench to handle storm drainage. The entire Infiltration Basin area of one acre will be infiltrated through the trench bottom. The following five pages show the infiltration trench design ' and location. DODDS ENGINEERS, INC. JOB NO. S-70-7S ' CIVIL ENGINEERING SURVEYING PLANNING IQ04205 148TH AVE. N.E., SUITE 200 - BELLEVUE. WA 98007 DATE ZS SEP 9G (2061 885-7877 OR 454-3743 BY K Q C ` �+ ' Lc-x) Nci^ToN - Fy\ST 11•lF)LT'RAT)ON s\/STDA/\ (6�DER Assoc-- rae po zT Do-mb MAV 2), )996) ' TP-2o 2. 3 MIN/-m = 26, 1 Ti) / F+ouR TP'2I3 3 , 4 AA)IIJ ) TQ = ) 7, 6 -rrJ / HouTz, A\)CRA C-,E 21, 8 Ta4-Hov R ' DES)6VQ TN F- I LMZA-no)�3 K1NE, LOAM SI)RfFIC� WA7M .LCSIG�J MANUAL ) 1996 DRAFT IJESIGN = TJVIEASURE'7�) x 1:;C5'T1NEi X (,EpMETRy x 'FPLUG6IAIt) FTr s-p►v ) _ EPA IVY c-M-o D = C,S O 1 4 b/w + O,OS D = 4 F-T- vnl = 4 F-r 4 (4)/4 -I D,DS = 4 ,0 WST ac >o.2s I.0 = ) , o FPLV66)N6) - 0 .9 I=D2 MED)UM SANDS rm/HouR =NF)LTRA-T)ON RENCI-1 ��-7SIC-1N S. 8 =1J/HOUR x TFr = 0,00023 FT SEC, 3600 s Fc/Hou2 12 r►�l 0 . 00023 r---,- ' SEC x 1 FY Z = O,OG1�2 3 FT3/SEC 10 yEAR STOP EVENT pEAI< RATE 0 .q ) cF G , ' TF AL. 2AIMFALL. 9-0 -PJFILTRtTn0M Fl2EA =s Tn 13c C0LLEc-rt-b , (SEE YNJ-'�RoGRnPH )s ) ' SHEET I OF ®j- DODOS ENGINEERS, INC. JOB NO. S7016 ' CI V I L E N GINE E RIN G S U R V E Y I N G P L A N N I N G DATE 26 SEP P 6 4205 '14BTH AVE. N.E.. SUITE 200 - BELLEVUE, WA 96007 (2061 BB5-7B77 OR 454-3743 BY KRS TN1-1 >-7TRRTION TRENICH LDES) 6nm (Co"7) ' UN)T L-EN67-H CALCULAT)ONS - WHICH WILL- 13E USCG TD DORM NE REC�U)RCb THEN)CH LE-N1671H . ' -TN IF 1 LTTcAT" om -})TROU 6H 7RE-mo-t BoTroM ONLY ' (0�000ZZ P7/sEc)(4 FTYL)Q1TFT) = D,CG0J2. CFS PIDZ L_1= - S7Z)r2AC) VOLUINE - US)N C-7 30 % VO)D RAT)O ' (4 FTXI P-T)(UNIT FTx0,30� = ).Z CIF PEZ LT:' �- (1Y(2rrT)-/4)(MIT FT) + ((2 FT14>=7xVN)7-F-r) - ' T Z 4 VN)T t'T 0.30)�'S1'(2f )� � �� 4 ,6 C>= PER L� (4 F-ry) FTXUN)T FTIC,30)= I,Z Cl-- PEA LF ' )H� EN-n RE too -YEAR s+ToRM LVEN-T OAK FLOW Foiz 71-1E TN1=1L772ATIoN APIZA (PE1zV)oUS AMD TM P-ERV)OUS WILL BE RZUTL-7D -MRO U6 H 1-)4 C TN 1=1 rRATI oN -MF_N LN - ' US)N 6 7-H E WATE1 W 0 a)/_.S P1F_a 6 RlAAA ) AN L - R)A L_ AND ER1ZO1z ) 714E -T'TZENC 4 LFN67il WAS CoMPUTE"D -m ZE 1 l-) 1_F, f3ELOW , AND DN THE NEXT 2 PAGES, is A),1 CUT1_11")I= C-F ZA-rA EI\37ER>✓D AN L Oyr P trr FROPA T�+E WATT=� Wo RZ)CS PRo GRA AA , ' -AREA - PE-ZV100S 0,295 ACQEZ / 'rMPC1zv)o0G o,los AmES DETE2M)AJL-j VS01,16 20 5(-ALi- I�2AW)NCI RIJD PlA>JIMCTEP, • CN FROM 7�CLE 3 .S.22 - K,C. SUrZ1=(-VE WATETZ pES)CIN ' Open spaces, lawns, parks, golf courses, cemeteries, A 3 G D landscaping. good condition: grass cover on 75% or more of the area 80 86 90 fair condition: grass cover on 50% to 75% of the area 77 85 90 92 ' Gravel roads and parking lots 76 85 89 91 Dirt roads and parking lots 72 82 87 89 Impervious surfaces, pavement, roofs, etc. 98 98 98 98 ' Open water bodies: lakes, wetlands, ponds, etc. 100 100 100 100 ' SHEET 2 OF �j- DODDS ENGINEERS, INC. JOB NO. S-70-1S C I V I L E N G I N E E R I N G S U R V E Y I N G P L A N N I N G D A T E 4205 14BTH AVE. N.E., SUITE 200 - BELLEVUE. WA 913007 8 Y KIPS [2061 B85-7B77 OR 454-3743 TN1=0RMAT10N F02 IS ' BASIN ID: EI100 NAME : EAST INFILTRATION SBUH METHODOLOGY TOTAL AREA. . . . . . . : 1 . 00 Acres BASEFLOWS : 0 . 00 cfs ' RAINFALL TYPE . . . . : USER1 PERVIOUS AREA PRECIPITATION. . . . : 3 . 90 inches AREA. . : 0 . 71 Acres TIME INTERVAL. . . . . 10 . 00 min CN. . . . . 68 . 00 TIME OF CONC. . . . . : 10 . 00 min IMPERVIOUS AREA ABSTRACTION COEFF: 0 . 20 AREA. . : 0 . 30 Acres CN. . . . . 98 . 00 ' PEAK RATE : 0 .41 cfs VOL: 0 . 16 Ac-ft TIME : 480 min )4']))R06RAPN 1S - 'P-aUTE.-i--) -MPoU6N STA6E S'T�)'2A6E ' WIT)-) CotJSTAN'T D)SCHA26E- (AS DUTERA1\1NCA `MP_o06 H TRIAL. AUD ERRDZ MET-Hob ON ppl6c 2 ) , LEVEL POOL TABLE SUMMARY MATCH INFLOW -STO- -DIS- <-PEAK-> STORAGE <--------DESCRIPTION---------> (cfs) (cfs) --id- --id- <-STAGE> id VOL (cf) ' - 100 YR 24 IN/4 FT ............ 0,41 0.41 ST244 DIS4 103,75 18 783.91 STP6C S701ZA6E -TQ TTZENCt-t CUSTOM STORAGE ID No. ST244 Description: 4 FEET WIDE, 24 INCH PIPE STAGE <----STORAGE----> STAGE <----STORAGE----> STAGE <----STORAGE----> STAGE <----STORAGE----> (ft) ---cf--- --Ac-Ft- (ft) ---cf--- --Ac-Ft- (ft) ---cf--- --Ac-Ft- (ft) ---cf--- --Ac-Ft- ' 100 00 0.0000 0.0000 101.10 166.95 0.0038 102.20 463.40 0.0106 103.30 721.00 0,0166 100.10 14.000 0,0003 101.20 193.90 0.0045 102.30 490.35 0,0113 103.40 735.00 0.0169 100.20 28.000 0.0006 101.30 220.85 0.0051 102.40 517.30 0.0119 103.50 749.00 0,0172 100.30 42.000 0,0010 101.40 24730 0.0057 102.50 544.25 0,0125 103.60 763.00 0,0175 100.40 56.000 0.0013 101.50 274.15 0.0063 102.60 571.20 0.0131 103.70 777.00 0,0178 _ E L 103.-75 100.50 70.000 0.0016 101.60 301.70 0.0069 102.70 598.15 0,0131 1103.80 791.00 0.0182 vo L 78 3 .9 1 C F ' 100.60 84.000 0,0019 101.70 328.65 0.0075 102,80 625.10 0,0144 103.90 805.00 0.0185 100.70 98.000 0,0022 101.80 355,60 0.0082 102.90 652.05 0,0150 104,00 819.00 0.0188 100.80 112.00 0,0026 101.90 382.55 0,0088 103.00 679.00 0,0156 104.00 819.00 0.0188 ' 100.90 126.00 0.0029 102.00 409.50 0.0094 103.10 693.00 0.0159 101.00 140.00 0.0032 102.10 436.45 0.0100 103.20 707.00 0,0162 ' SHEET 3 OF_4-- ®�- DvO D DINEERING G IURVE ENR S, IN . JOB NO. CIIL ' 4205 146TH AVE. N.E., SUITE 200 - BELLEVUE, '.)VA 98007 DATE ZC�{�(S+EP �C (2061 885-7B77 OR 454-3743 BY 1<1zS ' D 1 S C H A 2f� T1-I ROIL G N TRENC�--► t301TD N� DISCHARGE LIST ID No . DIS4 ' Description: 4 FEET WIDE BY FEET LONG * (O, 00092 CFS/LFX)1-1 UF:) = O, 10-76 C>=S ' STAGE <--DISCHARGE---> STAGE <--DISCHARGE---> STAGE <--DISCHARGE---> STAGE <--DISCHARGE---> (ft) ---cfs-- ------- (ft) ---cfs-- ------- (ft) ---cfs-- ------- (ft) ---cfs-- ------- 100.00 0.1076 101.10 0,1076 102.20 0,1076 103.30 0.1076 100.10 0,1076 101.20 0.1076 102.30 0.1076 103.40 0,1076 100,20 0,1076 101.30 0.1076 102,40 0.1076 103,50 0.1076 100.30 0.1076 101.40 0.1076 102.50 0.1076 103.60 0.1076 100.40 0.1076 101.50 0,1076 102.60 0.1076 103.70 0.1076 100.50 0.1076 101.60 0,1076 102.70 0.1076 103.80 0.1076 ' 100.60 0.1076 101.70 0.1076 102.80 0.1076 103.90 0.1076 100.70 0.1076 101.80 0.1076 102.90 0.1076 104.00 0.1076 100.80 0.1076 101,90 0.1076 103.00 0.1076 104.00 0.1076 ' 100,90 0.1076 102.00 0,1076 103.10 0.1076 101.00 0.1076 102.10 0.1076 103.20 0,1076 W 1TN AN TNP)Lll A-n0N -ME_Z,1C}1 11-7 FT LDN61 1 ' 4 ' WIDE ANC) 4' DE-EP 1 711E THE 100 \/EArZ STa r M EVENT F02 TN E ENT)RE 1 ACiZE SNF)LT}ZAT10N AR1EA W)LL BE ANt:) ' _TNT )LTTaxr - , THIS G)VES US A C0MF0TZTA13LE SAFE--TI/ F^CTOP, � S)NCE 0PlL-"I SOME OT- 111E 1zR)NFA LL WILL MA 1LE -L- - -M THE 7 ZENc H 'T-H 20tX-)N ROOT 1DRA I NS ^N D YARD DRAINS ' SHEET 0F� .! MOM ON SRI As IN MI MEN Mi 4 . MW bvA �� W W-d 0 ' V. CONVEYANCE SYSTEMS ANALYSIS AND DESIGN 1 V. CONVEYANCE SYSTEMS ANALYSIS AND DESIGN ' Storm water conveyance systems were designed using rational method. The design was checked using the backwater analysis. Spreadsheet for the conveyance and backwater can be found on the next two pages. 1 S j ORAL C6 j�t71.� �7 j S 1 EM DESIGN LOCATION: KLtiGCOUNTY 24-HRR1L1F4LL: 3.4 LICRES JOB NAME: LESLNGTON RIDGE JOB NUMBER: 87075 PREPARED BY: KRS DESIGN STORM: 25 YEAR INCRENIENTAL. RUNOFF LNIPER',TOUS. TIME OF RAINFALL- TRIBUTARY. PIPE PIPE PIPE ACTUAL TRAVEL PIPE CAPACITY SL'NMARY PIPE SEGMENT AREA COEFFICIENT AREA SUI�t OF CONC. INTENSITY FLOW MANNING'S DWMETER SLOPE LENGTH VELOCITY TIME Q(FULL) 5'(Fu-L ) Q(ACTMFULL) FROM TO (ACRES) "C" (A•C) (A•C)., (AI NUTES) (CiUR) (CFS) "n" (INCHES) (PERCENT) (FEET) (FT/SEC) {R1LN7r!'ESI 1CFS7 (FT SEC) (PERCENT) 26 25 0.9420 0.65 0.6123 0.612 10.00 2.02 1.240 0.014 12 10.600 143 9.64 0.28 10.771 13.71 11.5% 25 '_4 0.5177 0.65 0.3365 0.949 10.28 1.99 1.887 0.014 12 1.080 37 4.47 0.14 3.438 4.38 54.9"6 24 23 0.2313 0.65 0.1503 1.099 10.41 1.97 2.168 0.014 12 2.650 98 6.45 0.25 5.386 6.86 40.2% 23 VAL-LT 0.1739 0.65 0.1130 1.212 10.67 1.94 2.353 0.014 12 1.000 73 4.49 0.27 3.308 4.21 71.1% 22 _'1 0.4830 0.65 03140 0314 10.00 2.02 0.636 0.014 12 3.540 110 4.99 0.37 6.225 T93 102% 21 20 0.4306 0.65 0.2799 0.594 1037 1.98 1.174 0.014 12 6.900 93 7.36 0.21 8.690 11.06 13.5% 20A 20 0.3296 0.65 0.2142 0.214 10.00 2.02 0.434 0.014 6 1.000 60 2.83 0.35 0.521 2.65 83306 20 19 0.1792 0.65 0.1165 0.925 10.58 1.95 1.805 0.014 12 0.970 72 4.23 0.28 3.258 4.15 55.4% 19 9 0.0828 0.65 0.0538 0.978 10.86 1.92 1.877 0.014 12 9.200 49 9.65 0.08 10.035 12.78 18.7% 16 15 0.1414 0.65 0.0919 0.092 10.00 2.02 0.186 0.014 12 0.500 82 1.68 0.81 2.339 2.98 8.01 15 11 0.2495 0.65 0.1622 0.254 10.81 1.92 0.489 0.014 12 0.500 175 2.31 1.26 2.339 2.98 20.9% 14 13 0.3322 0.65 0.2160 0.216 12.08 1.79 0.387 0.014 12 0.500 61 2.16 0.47 2.339 2.98 16.506 13 12 0.4016 0.65 0.2611 0.477 12.55 1.75 0.833 0.014 12 2.000 259 4.32 1.00 4.679 5.96 17.8% 12 11 0.4786 0.65 0.3111 0.788 13.55 1.66 1.310 0.014 12 9.600 50 8.68 0.10 10.250 13.05 12.86 11A 11 0.2806 0.65 0.1824 0.182 10.00 2.02 0.369 0.014 6 4.870 117 5.18 0.38 1.150 5.86 32.1% 11 10 0.1453 0.65 0.0945 0.842 13.64 1.65 1.393 0.014 12 2.000 165 5.09 0.54 4.679 5.96 29.8 10 9 0.4692 0.65 03050 1.147 14.18 1.61 1.851 0.014 12 10.000 138 9.66 0.?4 10.462 1 13.32 17.7% 9 8 0.4017 0.65 0.2611 2387 14.42 L60 3.809 0.014 12 10.000 120 12.19 0.16 10.462 13.32 36.4% 8 7 0.8166 0.65 0.5308 2.917 14.58 1.58 4.622 0.014 12 6.900 125 11.18 0.19 8.690 11.06 53.296 7 2 0.1912 0.65 0.1243 3.790 14.77 1.57 5.955 0.014 18 0.500 53 4.16 0.21 6.897 3.90 86.3°6 2 VALLT 0.5015 0.65 0.3260 5.680 14.98 1.56 8.842 0.014 18 0.500 28 3.90 0.12 6.897 3.90 128.206 6A 6 0.1033 0.65 0.0671 0.067 10.00 2.02 0.136 0.014 8 0.500 50 1.65 0.51 0.793 2.27 17.1% 6 5 0.1136 0.65 0.0738 0.141 10.51 1.96 0.276 0.014 12 0.500 62 1.88 0.55 2.339 2.98 11.8% 5A 5 0.5533 0.65 0.3597 0.360 11.06 1.90 0.682 0.014 12 13.600 45 7.84 0.10 12.200 15.53 5.6% 5 4 0.3545 0.65 0.2304 0.731 11.15 1.89 1.379 0.014 12 0.500 148 3.10 0.80 2.339 2.98 58.906 4A 4 0.4899 0.65 0.3184 0.318 10.00 2.02 0.645 0.014 12 10.600 46 6.93 0.11 10.771 13.71 6.0°6 4 3 0.4879 0.65 0.3172 1.367 11.95 1.80 2.465 0.014 12 0.500 137 3.17 0.72 2.339 2.98 105.4% 3 2 0.3029 0.65 0.1969 1.564 12.67 1.74 2.715 0.014 12 1.760 51 5.88 0.14 4.389 5.59 61.9% 713 7A 0.4430 0.65 0.2880 0.288 10.00 2.02 0.593 0.014 12 9.000 51 638 0.13 9.425 12.64 5.996 7A 7 0.7083 0.65 0.4604 0.748 10.13 2.01 1.502 0.014 12 10.900 45 9.25 0.08 10.922 13.91 13.8% ri rr ar r r r r r r a■ r r r rr r� rr r r r BACKWATER CALCULATIONS JOB NAME: LEXINGTON RIDGE PREPARED BY: KURT JOB NUMBER: DESIGN STORMS: 25 YEAR ENTRANCE ENTRANCE EXIT OUTLET INLET APPROACH BEND JUNCTION PIPE PIPE MANNING'S OUTLET INLET PIPE FLOW VELOCITY TAILWATER FRICTION HGL HEAD HEAD CONTROL CONTROL VELOCITY HEAD HEAD HEADWATER FROM TO FLOW LENGTH DIA n ELEVATION ELEVATION AREA VELOCITY HEAD ELEVATION LOSS ELEVATION LOSS LOSS ELEVATION ELEVATION HEAD LOSS LOSS ELEVATION CB CB CFS) (FEET) N) VALUE (FEED (FEET) (SQ /SE EE EE EE E (FEET) (FEET) (FEET) HET) E% l(FEM (FEET) I (FEET) RIM EL 2 VAULI 8.8 28 18 0.012 182.00 185.10 1.77 5.00 0.39 186.55 0.17 186.72 0.08 0.191 156.99 IS'.05 0.39 0.00 000 IS6.16 192.00 7 2 6.0 53 12 0.012 185.10 185.40 0.79 7.58 0.89 186.16 1.25 187.41 0.18 0.45 I68.03 185.40 0.54 0.00 0.00 137.56 192. 8 7 4.6 125 12 0.012 185.40 194.00 0.79 5.83 0.54 187.86 1.77 195.00 0.11 0.27 195.38 196.75 0.37 0.00 0.00 1%.38 205.80 9 8 3.8 120 12 0.012 202.30 214.00 0.79 4.85 0.37 196.38 1.16 215.00 0.07 0.18 215.26 216.00 0.09 0.00 0.00 215.91 219.50 10 9 1.9 138 12 0.012 214.00 227.50 0.79 2.36 0.09 215.91 0.31 228.30 0.02 0.04 228.86 228.78 0.05 0.00 0.00 228.81 232.20 11 10 1.4 165 12 0.012 227.80 231.10 0.79 1.77 0.05 228.81 0-21 232.10 0.01 0.02 232.13 231.94 0.05 0.00 0.00 232.08 24C2 12 11 1.3 50 12 0.012 240.80 245.60 0.79 1.67 0.04 232.08 0.06 246.60 0.01 0.02 246.63 246.37 0.02 0.00 0.00 246.61 249.10 13 12 0.8 259 12 0.012 245.60 250.90 0.79 1.06 0.02 246.61 0.12 251.90 0.00 0.01 251.91 251.49 0.00 0.00 0.00 251.91 257.50 14 13 OA 61 12 0.0]2 230.90 251.20 0.79 0.49 0.00 251.91 0.01 252.20 0.00 0.00 232.20 25170 0.01 0.00 0.00 252.20 254.7 15 11 0.5 175 12 0.012 231.10 232.00 0.79 0.62 0.01 232.08 0.03 233.00 0.00 0.00 233.00 232.50 0.00 0.00 0.00 233.00 242.00 16 15 0.2 82 12 0.012 232.00 232.40 0.79 0.24 0.00 233.00 0.00 233.40 0.00 0.00 233.40 232.90 0.00 0.00 0.00 233.40 235.8 11A 11 0.4 117 6 0.012 240.80 246.50 0.20 1.88 0.05 232.08 0.43 247.00 0.01 0.03 247.04 246.94 0.04 0.00 0.00 247.00 254.00 3 2 17 51 12 0.012 155.10 186.00 0.79 3A6 0.19 186.10 0.25 187.00 0.04 0.09 187.13 197.40 0.13 0.00 0.00 187.25 197.50 4 3 2.5 137 12 0.012 IS6.00 196.70 0.79 3.14 0.15 187.25 0.55 187.80 0.03 0.09 187.91 188.00 0.05 0.00 0.00 187.95 202.10 5 4 1.4 148 12 0.012 186.70 187.40 0.79 1.76 0.05 187.95 0.19 ]88.40 0.01 0.02 188.43 187.95 0.01 0.00 0.00 188.42 ?02.2G 6 5 0.3 62 12 0.012 78'r.40 187.75 0.79 0.35 0.00 188.42 0.00 188.75 0.00 0.00 198.75 188.30 0.00 0.00 0.00 188.75 199.80 6A 6 0.1 50 8 0.012 187.75 188.00 0.35 0.39 0.00 188.75 0.01 198.75 0.00 0.00 188.76 188.33 0.00 0.00 0.00 183.76 194,90 YD 6A 0.0 50 6 0.012 188.00 188.50 0.20 0.00 0.00 188.76 0.00 189.00 0.00 0.00 189.00 188.75 0.01 0.00 0.00 188.99 NO 4A 4 0.6 46 12 0.012 186.70 200.40 0.79 O.S2 0.01 187.95 0.01 201.40 0.00 0.01 201AI 200.95 0.01 0.00 0.00 201.40 203.90 5A 5 IA 45 12 0.012 187.40 200.10 0.79 0.87 0.01 183.42 0.01 201.10 0.00 0.01 201.11 200.94 0.00 0.00 0.00 201.11 203.E 23 'AUL 0.1 73 12 0.012 132.00 183.00 0.79 3.00 0.14 186.55 0.2 i 186.82 0.03 0.07 186.92 183.20 0.00 0.00 0.00 196.92 189,00 24 23 0.0 98 12 0.012 183.00 195.60 0.79 2.76 0.12 188.99 0.31 189.30 0.02 0.06 189.38 185.70 0.00 0.00 0.00 189.38 1914.00 25 24 0.0 37 12 0.012 185.60 196.00 0.79 2.40 0.09 0.00 0.09 187.00 0.02 0.04 197.06 186.10 0.01 0.00 0.00 187.05 1967 26 25 0.6 143 12 0.012 186.00 201.20 0.79 1.58 0.04 201.40 0.15 202.20 0.01 0.02 202.23 201.75 0.00 0.00 0.00 202.23 204.70 YD 25 0.0 45 6 0.012 186.00 188.50 0.20 0.00 0.00 0.00 0.00 189.00 0.00 0.00 199.00 188.55 0.01 0.00 0.00 188.99 19L 19 9 0.7 49 12 0.012 214.00 218.50 0.79 2.39 0.09 201.11 0.11 219.50 0.02 1 0.04 219.56 219.05 0.00 0.00 0.00 219.56 225.3 20 19 1 0.0 72 12 0.012 218.50 219.20 0.79 Z30 0.08 219.36 0.16 220.20 0.02 0.04 220.26 219.30 0.14 0.00 0.00 220.12 230.50 21 20 1 2.4 93 12 0.012 224.00 230.40 0.79 IA9 0.03 220.12 0.09 231.40 0.01 0.02 231.42 231.60 0.12 0.00 0.00 231.48 234.4 22 21 2.2 110 12 0.012 2M040 234.30 0.79 0.81 0.01 23L48 0.03 235.30 0.00 0.01 235.31 235.40 0.09 0.00 0.00 235.31 238.30 20A 20 1.9 60 6 0.012 219.70 220.30 0.20 2.21 0.08 187.05 0.30 220.80 0.02 0.04 220.35 223.30 0.04 0.00 0.00 =3.26 224.50 7A 7 1.2 45 12 0.012 188.60 193.50 0.79 1.91 0.06 187.96 0.07 194.50 0.01 0.03 194.54 194.30 0.00 0.00 0.00 194.54 197.0- 7B 7A 1 0.0 51 12 0.012 193.50 198.10 0.79 0.74 0.01 158.99 0.01 1".10 0.00 0.00 199.11 198.20 0.09 0.00 0.00 199.02 202.10 10/"6 DODDS ENGINEERS,INC. PAGE 1 ' VI. SPECIAL REPORTS AND STUDIES SETTLEMENT AGREEMENT SETTLEMENT AGREEMENT THIS AGREEMENT is made between the City of Renton, a municipal corporation ("Renton") and Lexington Ridge Realty, Inc., a Washington corporation. RECITALS OF FACT 1. In 1987, Centron Equities Corporation, on behalf of Canada-America Associates, L.P., a Washington limited partnership, applied to the City of Renton for site plan approval for a multi-family development known as"Lexington Ridge" consisting of 360 units on approximately 13.4 acres located in the City of Renton. o 2. A draft Environmental Impact Statement for the Lexington Ride project was published in November, 1988. The final Environmental Impact Statement for the Lexington Ridge project was published in January, 1989. On June 15, 1989,'the Environmental Review Committee of the City of Renton issued its final decision imposing mitigation conditions on the Lexington Ridge project pursuant to a State ' Environmental Policy Act("SEPA"), RCW 43.21C. ' 3. On October 13, 1989, the Lexington Ridge site plan was approved by the City of Renton hearing examiner in file number SA-082-87. The hearing examiner's decision approving the site plan required the applicant to comply with the conditions imposed by the Environmental Review Committee. 4. On May 31 1990 a petition entitled In Re: Canada-America Associates Y P , L.P. was filed in the United States Bankruptcy Court for the Western District of Washington in Seattle and was assigned case number 90-03783. iLex Ridge Settlement Agreement page I of 8 a14311 14995-2 131103!.DOC 5/OR/95 EXHIBIT 1 5. On January 4, 1991, Grahame R. Ross (hereinafter"the Trustee") was appointed as Chapter 11 Trustee in case number 90-03783 and was given authority to administer the property of the bankruptcy estate including the Lexington Ridge property. ' 6. Grahame Ross as Trustee applied to the City of Renton for a building permit on September 17, 1991. This application was assigned building permit application ' plan review number 8810. ' 7. One of the conditions imposed by the Environmental Review Committee required the applicant to obtain approval by the City's Public Works Department of plans for a storm drainage detention system, in advance of the issuance of any building permits { for the Lexington Ridge project. 8. The Trustee was unable to obtain approval by the City's Publics Works Department of plans for a storm drainage.detention system for the Lexington Ridge project. September,In Se tember 1992,the City advised the Trustee that the Trustee's building permit application had expired pursuant to section 304(d) of the Uniform Butilding Code, i ' 1988 edition. 9. On September 16, 1992, the Trustee appealed to the Renton hearing examiner the City of Renton's decision to terminate the Trustee's building permit application. The appeal was assigned file number AAD-91-151. On November 10, 1992, a hearing was held before the Renton hearing examiner to consider the Trustee's appeal. On December 9, 1992, the Renton hearing examiner issued his decision upholding the decision not to approve the Trustee's conceptual design of the storm drainage system and to terminate the Trustee's building permit application number 8810. On December 23, 1992, the Trustee filed a Petition for Writ of Review and Complaint for Damages under Lex Ridge Seldement Agreement page 2 of 8 H 1431 1 14995-2 B IJ03!.DOC 5/03/95 King County Superior Court cause number 92-2-29569-5. On that date an Order was issued directing a writ of review. t10. On January 21, 1993, the Trustee filed an application for, and notice of, removal of the Superior Court action to the United States Bankruptcy Court for the Western District of Washington pursuant to 28 U.S.C. § 1452. ' 11. On or about May 12, 1994, the Trustee conveyed by Quit Claim Deed dated May 10, 1994, the Lexington Ridge property to Lexington Ridge Realty, Inc. under King County recording number 9405122166. On that same date, the Trustee assigned all of the interest of Canada-America Associates, L.P. in and to all permits, approvals and all other rights or claims including all causes of action against the City of Rento to Lexington Ridge Realty, Inc. 12. On August 31, 1994, the U.S. Bankruptcy Court entered an Order ' dismissing adversary proceeding number A92-10472 against the City of Renton and named individual defendants. On that same date, a stipulated order was ent ed remanding to King County Superior Court the case which was originally filed under cause number 92-2-29569-2 and substituting Lexington Ridge Realty, Inc. in place of the Trustee as the plaintiff in that action. 13. On September 28, 1994 the King County Superior Court entered an order in cause number 92-2-29569-5 substituting Lexington Ridge Realty, Inc. in place of the ' plaintiff in that action and directing that all further in that case be continued proceedings by and in the name of Lexington Ridge Realty, Inc. Lex Ridge Settlement Agreement page 3 of 8 #14311 14895-2 D1303!.DOC 5/08/95 r r 14. On October 12, 1994 an order amending the case schedule in King County cause number 92-2-29569-5 was entered providing, among other things, for a review ' hearing or trial on May 10, 1995. ' 15. It was agreed between representatives of Lexington Ridge Realty, Inc. and the City of Renton that all of the plaintiff's claims against the City of Renton could be rdismissed if an agreement could be reached on design criteria for the storm drainage rsystem on the Lexington Ridge site, a process for timely consideration of a new site plan and an agreement regarding the maximum allowable units on the site. It was therefore 1 agreed that the deadlines contained in the case schedule order for filing of briefs would be 1 adjusted by mutual agreement between the parties although the actual trial die would not , :v be stricken. j 16. On March 17, 1995 a stipulation and order was entered dismissing all of the plaintiffs claims against all of the individual defendants in King County cause number 92-2-29569-5. i ' AGREEMENT NOW, THEREFORE, in consideration of the covenants and conditions herein contained, the parties agree as follows: ' 1. Lexington Ridge Realty, Inc. (or its successors or assignee to the real property described in Exhibit A to this Agreement) agrees to submit within 180 days ' from the date of this agreement a new site plan for development of the Lexington Ridge property to the City of Renton for approval in accordance with the process agreed upon in Paragraph 3 of this Agreement. ' Lex Ridge Settlement Agreement page 4 of 8 N14311 14895-2 BIJ03!.DOC 5/08/95 2. The City of Renton agrees that the standards set forth in this paragraph shall apply to the drainage system for the Lexington Ridge site, and agrees to approve, pursuant to Section 4-22-16B of the Renton Municipal Code, a modification of the Storm ' and Surface Water Drainage Code standards for the Lexington Ridge site, as follows: (a) The performance goal for the Lexington Ridge drainage system ' will be to minimize or reduce the rate of water ace sur f flowing g into the Bronson Way ' conveyance system west and south(immediately downstream) of the point of connection of the Lexington Ridge System. (b) Water quality wet vaults shall be incorporated into the design of the detention vaults. The wet vault volume shall be in addition to the active si.iorage volume of the detention vaults. (c) The existing 8-inch diameter storm drain in Bronson Vkay at the i intersection of N.E. 3rd will be replaced. The determination of the final pipe size will be h' based on methods described in Section 4.3.4 of the 1990 King County Surfa�e Water ' Design Manual ("KCSWDM"). (d) The post development outflows from the Lexington Ridge site for 1 the 2-year through 100-year design events will not exceed the values given in the table ' below: 4\� ' Lex Ridge Selliemenl A reemen� S S page S of 8 H14311 14895-2 BIJ03MOC 5/OS/95 Return Interval Increment* (CFS) ' 2 year 0.44 10 year 0.44 ' 25 year 0.50 100 year 0.50 ' * Increment above "undeveloped" peak flow rate. "Undeveloped" conditions mean as of the date of this Agreement. ' This table is based on allowing increases for the developed peak rate of runoff for ' the site to not exceed 0.5 cfs above the undeveloped peak rates of runoff for the 2-year through the 100-year design storms. By only allowing a negligible increase in developed } peak rates of runoff from the site for the 2-year through the 100-year design storms and by performing the downstream improvements as specified in this Agreement the completed improvements will provide the equivalent surface water management controls as those required b the q y KCSwDM. (e) No volume safety factor will be added to detention volumes since ' the system is being designed for detention of a 100-year storm. (f) No biofiltration will be required. Equivalent water quality controls are being provided by the wet vaults referenced in section(b). ' 3. The City of Renton further agrees to process any new site plan for the Lexington Ridge site in a reasonably timely manner and in substantial conformance with the time table attached to this agreement as Exhibit B. ' 4. The City of Renton represents that the applicable zoning designation for the Lexington Ridge site is Multi-Family Infill District, with a maximum allowable dwelling Lex Ridge Settlement Ag1•ee11?e171 page 6 of s H14311 14895-2 131J031.DOC 5/08/95 MAY-09-1595 17:15 FROM H(LLIS CLARY, ET AL. TO 200120624= P.04 MAY- 0-05 TUE 10:13 VARREN, KELLOGG FAN NO, t2062555474 P. 03 unit density of 10 to z0 attics per aeerc,vs 25 units per acrL it afl'ordablo housing mCctlttg zoning codo requirements is provided, The City agtccs t4 alluw the mm dmum numbor c) dwelling units per acre on the Lcxingtna Ridge site,provided the site plan oomplies with aid;jppllcablc dcv+clopment otan&Wv, 5- Lexington Ridgc Realty,In-[;,agrccs to entry of a atipulatvd order dismissing with prejudice&Il renmin4%otc&as aphim tin Ci Ly of Renton undety-ing ' County SupQjor Court cacao number Wi -2-2950-5. ~ ' 40 'Venue and j ut'isdletlm to caforc a the provisions of this AgM=ant ehall bo In the King County Su*or Court. 7. This Agrcarntmt is the cnli,-c agrccrrncatbereen the parties. Its terms 1 - cannot be modified, Bxeept by a separate wilting httween the putics. (' $, Time is of lino csacmc in this Agcoazxtrt7L ' 9. This Agcecntent In intwtded to bind and inure to the benefit of tack puty'A hers,auugmom and asitigtts. ' 30, llils AgrccrrtMt rosy he CMMInd is coculta�pmt aliginals. A fW41MI10I ' signature of au party shalt be rccogmzed as an original signature. DATED: May 19S►S. ' LI3XINUVON RIDGE lt$ALTY,INC. ' Phillip S Lotnbaidi • Vice l�rc:aldent 'z Lax Rf Srt�LeruxtA eurx+vMt nao 7 of lf14311 i+8M.2 01M I M VOWS 1 MAY- 9-95 TUE 16:14 WARREN, KELLOGG FAX NO. 12062555474 P. 04 CITY,OF RENTON iBy Mayor Earl Clymer 1 Approvcd as to fonu; Attest: r City Attorney City Cler r I4 1 ' Lez Ridge Set!(eme►�1 Agreement page of-5 #14311 14895-2 B1703!.DOC 5/08/95 EXHIBIT A Legal Description ' PARCEL A: That portion of the northeast quarter of the northeast quarter and the northwest quarter of the northeast quarter of Section 17 , Township 23 North, Range 5 East, W.M. , in King County, Washington, lying easterly of Bronson Way "County Road No . 17411 , northerly of 3rd Avenue North extension as established by the City of Renton, anc ' westerly of the following described line : Beginning at the intersection of the westerly line of the 200 foot ' Puget Sound Power & Light Company right -of way, as delineated on the Plat of Windsor Hills Addition to Renton, acco:ding to the plat thereof recorded in Volume 38 of Plats, page 22, in King County, Washington, and the southerly line of Southeast 1 8th Street "County ' Road No. 174" as delineated on said plat; thence southwesterly along the southerly line of laid street• 265 . 70 feet to the northwest corner of Tract of land conveyed to the First Methodist - Church of Renton, by Deed recorded undex Recording Number 5911567, to the true point of beginning of the line herein described thence south 26049130" east 379 .30 feet; thence southwesterly 900 feet more or less, to the intersection of the .north line of 3rd Avenue North Extension as established by the City of Renton and the west -line of .the east 100 feet of the northwest LLartie(, of the northeast quarter of said Section and the q..__ terminus of said line; EXCEPT that portion conveyed to the City of Rentol by Deed recorded under Recording Number 4494467 described as follots : The south 425 feet of the northwest quarter of thL northeast quarter lying easterly of Bronson Way North, and north of Mt . Olivet Cemetery Road; EXCEPT the east 100 feet thereof; and ' EXCEPT the following described Parcels : "A" Commencing at the southeast corner of the northwest quarter of the northeast quarter of Section 17, Township 23 North, Range 5 ' East, W.M. , in King County, Washington; thence north 1011 ' 17" east along the east line of said subdivision, a distance of 425 . 04 feet ; thence north 89036141" west, parallel to and 425 . 00 feet distance from the south line of said subdivision, a distance of 100 . 01 feet to the true point of beginning; ,\� (legal description, continued) a I' ' LEGAL DESCRIPTION, continued : thence continuing north 89036141" west , a distance of 141 . 91 feet tc the easterly margin of Bronson Way North; thence north 31049 ' S7," east along said easterly margin, a distance 241 . 87 feet ; ' thence north 19021157" east a distance of 15 . 80 feet ; thence south 61016 ' 4.0" east a distance of 151 . 62 feet ; thence south 31*49157" west, a distance of 236 . 42 feet to a point on ' a line west of , parallel to and 100 . 00 feet distant to the east line of said subdivision; thence north 1011 ' 17" east, a distance of 52 . 83 feet to the true point of beginning, "B" Commencing at the southeast corner of the northwest quarter of the northeast quarter of Section 17, Township 23 North, Range 5 East, . W.M. , in King County, Washington; 4 thence north 1011 ' 17" east along the east line oftsaid subdivision, a distance of 425 . 04 feet; 1' thence north 89036141" west, parallel to and 425 . 60 feet distant from the south line of said subdivision, a distance of 141. 91 feet to the easterly margin of Bronson Way- North; thence along said margin north 31049157" east a distance of 241 . 87 ' feet; thence north 19021157" east a distance of 76. 60 feet to the true point of beginning; (p thence continuing north 19021157" east, a distanc4 of 72 . 82 feet; thence north 52016137" east a distance of 80 . 00 f ' et; thence south 37.043103" east, a distance of 138 . 40 feet; (� thence south 28043120" west, a distance of 89 . 86 7eet; C�2 thence north 61016140" west, a distance of 1- 47 . 00 feet to the true point of beginning. ll) PARCEL B : That portion of the north half of the northeast quarter of Section 17, Township 23 North, Range 5 East, W. M. , in King County, ' Washington, described as follows : Beginning at the intersection of the southwesterly line of right of way of Puget Sound Power & Light Company with the southerly line of Southeast 128th Street, as shown on Windsor Hills Addition to Renton, according to the plat thereof recorded in volume 38 of Plats, page 22 , in King County, Washington; ' thence south 26049 ' 30" east along said southwesterly line 450 . 00 feet to the true point of beginning; ( legal description,g p continued) LEGAL DESCRIPTION, continued: thence south 6301013011 west 250 . 00 feet ; thence southwesterly 900 feet, more or less, to an intersection with ' the north line of 3rd Avenue North extension as established by City of Renton and existing on September 26 , 1967 , with the west line of the east 100 . 00 feet of the northwest quarter of the northeast quarter of said Section; thence southerly along said west line to the south fine of the northwest quarter of the northeast quarter of said Section; thence easterly along the south line of the north half of the northeast quarter of said Section to the southwesterly line of said Puget Sound Power & Light Company right of way; thence north 26049 ` 30" west along said southwesterly line to true point of beginning; EXCEPT that portion of the northwest quarter of th4 northeast quarter of said Section lying south of the north 1�ne of a strip of land Deeded to City of Renton for street by Deed recorded under '- Recording Number 5947084 ; and EXCEPT that portion of the northeast quarter of the northeast quarter of said Section lying between the norther?y line of the more northerly strip .of land Deeded to City of Renton fbr street by Deed recorded under Recording Number 5684198 and the southerly line of the more southerly strip of land Deeded to City of Renton by said Deed; also EXCEPT that portion thereof lying south of the northerly line of Mt . Olivet Cemetary Road, as deeded to King County by eed recorded under Recording -Number 2722078 ; and t.{ EXCEPT that portion of the south 115 . 00 fee- of the northeast 'Ln quarter of the northeast quarter of said Section 17, lying east of Q said road; also d' EXCEPT that portion of the northeast quarter of the northeast quarter of said Section, deeded to City of Renton for street by Deed recorded under Recording Number 5947084 . TOGETHER WITH that portion of Mt . Olivet Cemetery Road, vacated ' under Ordinance Number 2329 of the City of Renton, which would attach to said premises by operation of law. -3- CITY OP RENTON REARING EXANI M ERI CTTY COUNCIL , REVIEW PROCESS EitC meeting Past Notices wring E=nittet City F ERC m d Decision&lur Council 12 i tof Env.Decision for Public Pub Recorttmees�dation 3Yfcetittg npplieaIioti Dot,-rminZtiOst Pubiisl�ed Hearlr o E�Og Appeal Pr�are Coin nux/Staff Appeal Ptciod Revievr ReQeri Appea3 L, —j 0 Period Emds Period 4--- s H 15 to 17 Days Approx. 6 Days Combined - t5 Days 13 Days 1�F Days 14 Days ApProx. ►-� 5 Day3 30 Days - x w CSty staff or otheragencks may request additional information Juriag tht revicwand 3ccision making process. Yt is irtrpottant that the applicant subdt dr,Tcqucsicd materW quickly to avoitidelaysinthepnocts Any i4wspentg26cringd2ta and/or additional dry revkv of revisions is not inrlWed in dhc ztcve dwt and will imreese the to:)c required to prc=m the, a pplicatioa. u'H.�asz.hF7�eb VII. BASIN AND COMMUNITY PLANNING AREAS ' N/A 1 1 t 1 1 ' VIII. OTHER PERMITS ' N/A 1 1 1 1 1 ' IX. EROSION/SEDIMENTATION CONTROL DESIGN 1 1 1 1 DODDS ENGINEERS, INC. JOB NO.157079 ' C I V I L ENGINEERING S U R V E Y I N G PLANNING DATE 1O 1 4205 1467H AVE. N.E., SUITE 200 - BELLEVUE. `NA 98007 BY E\ �1L�G] 12061 885-7877 OR 454-3743 SSA I�TI w t-t c IJ iW ' jl IJC " fit SAT-�V S kN7 kAS P SUN E "7D BASIN ID: DE002 NAME: DEVELOPED 2 YEAR SBUH METHODOLOGY TOTAL AREA. . . . . . . : 11 .34 Acres BASEFLOWS: 0.00 cfs RAINFALL TYPE. . . . : USER► PERVIOUS AREA PRECIPITATION. . . . : 2.00 inches AREA. . : 4.40 Acres TIME INTERVAL. . . . : 10.00 min CN. . . . : 74.52 TIME OF CONC. . . . . : 9.74 min IMPERVIOUS AREA ABSTRACTION COEFF: 0.20 AREA. . : 6.94 Acres CN. . . . : 98.00 ' TcReach — Sheet L: 50.00 ns:0. 1500 p2yr: 2.00 s:0.0200 TcReach — Shallow L: 100.00 ks:27.00 s:0.0700 TcReach — Channel L: 850.00 kc:21 .00 s:0.0800 PEAK RATE: 3.28 cfs VOL: 1. 16 Ac—ft TIME: 480 min ' 3. To determine the trap geometry, first calculate the design surface area (SA) of the trap, measured at the invert of the weir. Use the following equation: ' SA = FS(02Ns), where: ' 02 = Design inflow based on the peak discharge from the developed 2-year, 24-hour design storm from the contributing drainage area as computed in the hydrologic analysis. The 10-year, 24-hour design storm shall be used if the project size, expected timing and duration of construction, or downstream conditions warrant a higher level of protection. If no hydrologic analysis is required,the rational ' method may be used (Section 4.3.3). Vs = The settling velocity of the soil particle of interest. The 0.02 mm (medium silt) particle with an assumed density of 2.65 g/cm3 has been selected as the particle of interest and has a settling velocity (Vs) of 0.00096 ft/sec. ' FS = A factor of safety of 2 to account for non-ideal settling. Therefore, the equation for computing surface area becomes: SA =2 x 02/0.00096 or 2080 square feet per cfs of inflow SHEET 0F 1 DODDS ENGINEERS, INC. JOB NO. 1 _ CIVIL E N G I NE E RING S U RV E YING P L A N N I N G DATE ( O ( 96n 4205 148TH AVE. N.E., SUITE 200 - BELLEVUE. WA 98007 _ (206J 665-7e77 OR 454-3743 B Y . f^560PS 1 1 1 1 1 1 i 1 1 1 1 i SHEET OF X. BOND QUANTITIES WORKSHCCT 1 1 1 XI. MAINTENANCE AND OPERATIONS MANUAL