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Home My WebLink About03373 - Technical Information Report rr- T_ a� A � ` ► JAEGER E1`IGiNEERIhIG , � 9419 5. 204 PLACE - KENT, WASHINGTON 98031 + PHONE (253) 850-0934 F�4x (253) 850-0155 � � � � December 15, 2005 f�e�. S-Zz-o� TECHNICAL INFORMATION REPORT VVEBBER SHORT PLAT 7 LOTS 3819 NE 19te ST. RENTON, WA. PREPARED FOR: �� _ � I �"��'�� ,.�--',�,�"�'s.��,��:��:4 Cheryl Webber �.; �., a„ - "�,��,� I 5500 Rainier Ave. S. `��` `l�� ' '°`� � �. ��3� ' � Seattle, WA. 98118 i`� ~� �` �'a � (206) 650-4645 � ��'� ,�� $ �:��' �K� �'-�'�'.�j'`�,�.��.�'��'d� ��~t ��Y:��1��`� I �`:��:i-�r�� PREPARED BY: - �� , .�- w ' -,....��-�. James J. Jaeger, P.E. t � �21o� � r1�oo-� d �,1'�--f-� 3.�3 / -.-- __ __ _ _ _ -----� • .� .: �.�.:JLL Li `.�/I`I I LI v I.: I. OVERVIEW Ii. CORE DRAINAGE REQUIREMENTS III. OFFSITE DRAINAGE IV. PREDEVELOPED DRA!' ' ^ '�r V. DEVELOPED DRAINAC VI. CONVEYANCE SYSTEM VII. EROSION CONTROL . _ _.I � , I. OVERVIEW The proposed Webber Shorf Plat is an application for an 7 lot single family residential short subdivision situated on an existing large residential lot with an area of 1.86 acres. It is located on the south side of NE 19th St., between Shelton Ave. NE and Redmond Ave. NE (if extended). This project will require preliminary short plat approval and a SEPA determination by the City of Renton. The site is zoned R-8, residential. All of the proposed lots will be single family detached residences. The surrounding properties are also similarly zoned R-8. The site is currently has and existing residence and 3 accessory storage buildings. All of the existing structures/sheds will be removed. The existing house has a driveway that is connected to NE 19th St. The southern half of the site has gentle slopes that slope down to the south, to the Forestbrook Townhome Development and subsequently the Honey Creek drainage corridor. There is an 8' high rockery (this shorf plat on the high side) along the south properfy line that is part of the Forestbrook Property. A driveway area is south of the rockery. Honey Creek is located approximately 150 ff. south of the property. There are r : sensitive areas on this site. The slopes in the norfhern half of the properfy are very flat. The norfhern 150 ft. slope towards the northeast, to NE l9rn The steepest slope is approx. 10% near the middle of the western proper' line. The soils on the site are a fine sand with some gravel. The norfhern half (upper area) of the site displays a typical residential landscaping wi'r� few trees, tall grass, many shrubs. The landscoping hos not been well maintained. The southern half of the site is also mosfily cleared with tall grass ond mixed grass and gravel. There is a gravel driveway that extends almost the full length of the property. There are approx. 50 trees on the site, mostly along the east and south property lines. The existing drainage sheet flows across the property to the south. It flows onto the upper porfion of the rockery and is collected by the rockery. The rockery drain appears to discharge into an adjacent catch basin at the base of the rockery. This catch basin is then connected to the drainage system for the Townhomes. The proposed drainage system wilf use a subsurface concrete vault to provide detention and water quality enhancement. The proposed use of the properfy as an 8 lot residential shorf subdivision will be consistent with the surrounding developments. All of the surrounding properfies are developed. There is a potential for additional lots in an area west of the site, near the southern portion. This area is parf of the Dalpay Short Plat that is currently under construction. Access to the new lots will be from a new internal public street that runs north/south and - -`! � is connected to NE 19ih St. This street wiif be a dead-end public street thot - terminates with a turnaround bulb. The new street is proposed to be a 32' wide residential street with a 42' right-of-way. A sidewalk is not proposed for the east side of the new street because there are no proposed lots or pofiential fiuture lots along that side of the street. Landscaping wiil be installed in lieu of the sidewolk. The frontage along NE 19th St. wifl be improved with additionaf road paving, curb, gutter and sidewalk. A new water main and sewer main will be instolled in the new street. The water main will end at the cul-de-sac bulb. � _ � , � Page 1 of 2 ;' King County Building and Land Development Dlvislon � TECHNICAL INFORMATION REPORT (TIR) WORKSHEET • . . � - . . . . � . � . Projed Owner C 4-4�2`(L ��.� Project Name ��aF=� c�1-f�2�rLi¢� Address 55� Ra�nie.+r Se.a , 14 Location Phone ^��0� �S� - ��S ��19 7ownship Z3 ►� � Range 5 �= I Projecl Engineer 0.1Me S ��-� ¢ Q Secf ion i Company Project Size I� �CP AC Address Phone Q' � s� ��-�- (�, t� Upstream Drainage Basin Size )� �7 AC ; / '' v -U o6�3 t • • �- iI • • 7' • �- i� I � Su�ivision G' pOF/G HPA � S`�oref;ne �.:a;�agernent � ,�Short SuSdivision � COE 404 � Roa<ery ! � Gradirg � DOE Dam Safery � Structura!Vau;;s � Commerciai � FEM,A Floodplain � Other � Other � COE Wetlands � HPA «• �J,.i � �� - • i �I ICO;��m::rl;`,y � � � 1 �� I\�1�+ L`��. i j ' Draina�e 62sn � , --s�N�� ;=�-E''� ----- .. �-„ .� IC ��'E� i_ F�o�p?ain C' Stre�m (-i 1'Jetlands L_J Criticzl S:ream Reach `i SeepslSprings � DepressionsiSwaies � High Groundwater T�le ; I � Lake i; Grcundwater Recharge � SteepSlopes --- ---- �' 01t-�er — ------ - - - - - -_ j -1 �a}cesideiErosion Haz�;d :�• � ..:- - - ,� ! Sc�!T�,«? , �,cr.s Erosion Potenli�J Erosi��e L'e'ocities ;' (�c-�.i��I�l�'�-�-w�9----�_-_G��l.o— - ---��-��-- - ---5---�e,�—�-- � -�liy -- �---- - -- � Ad�iticn2l Sheets A7a:cred 1/*" � . .a:, :i � . "" Page 2 ot ^",;',�! I . King County Buliding and Land Development Dlviston I, v TECHNICAL INFORMATION REPORT (TtR) WORKSHEET � � . • � . REFERENCE LIMITATIOWSfTE CONSTRAINT � Ch.4-Downstream Anafysis < Y� d��h , � r ►�.�� 0 -S � a a 0 Additiona!Sheeis Attatched • ��i17 MINIMUM ESC REOUIREM,EtJTS ��11NIMUM ESC REQUIREMENTS DURING CONSTRUCTION FOLLOWING CONSTRUCTION � Sedimentafion Faali;ies ,� Stabilize Exposed Surface �Stabilized Construction Entrance Remove and Restore Temporary ESC Faalities � � Perimeter Runoff Cont�ol Clean and Remove All Silt and Debris � � Clea�ing and Grading Restrictions Ensure Operation of Permanent Fadfities i �Cover PraC,ices � Flag Limits of NGPES � Construction Sequence � Ofher Other , � « �- �� L� Grass Vnec Ch�^,nel � Tank i� (n!iltra;ion f.'�thod cf Ar2lysis '� �Pipe System ;�Vavit � Depression ��C�TS j � Open Channel �! Erercy Diss2.,�:or � Flow Dis�rsal CompensationR.4itigation � Dry Pond U ��Jetland 0 �'Jaiver of EIiN ated Site storage � � Wet Pond � Stream � Regional Detention � ; - �� ' r � ', Brief Description cf Sysiem O�ralion �� Cc�`—��S �' 1�l�1'n� � ��–v��'� Y Q� �i-,�,11 e�TV ew �i � Facility Related S�te Limitations � Addi�ional Sheets Atta:ched Reference Faality Liru�ation I i � �i�l� _ II. ' �� i ' _.�✓.I '�1 �� 1 . � Drainage E2sement Cast in Piace Vau!t � O;her �Access Easement O Retaining`rJa,l J Native Growlh Protect;on E�sement � 0 Rockery>4'H�gh I' � Tract , � Structur�J on Steep Slo� _ L � OtF�er — _ ___ __' . - • - -t� . � n �� I I or a civil engineer under my supervision have visited the site. Actual Isite condilions as observed were incorpors:ad into this woricsheet and the ni attatchment9. 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J �u I t�� o � n YY' a �� 5 . �S , e��.a awii ��.. e�sa �.,5 � � �I , 2 �+. ,7.aY l t Ip��Y JMw..� . � . r I W �tst+ro�w n W � ) ♦ W � 1 �• I � 0 � � V � W �. � r` I , I 4� �'2 � u.� W i� 3��. p •n ) 1 Zi' � ' ' ice. � i p �...- - : 4 � .�� ; � � ��•�� '�+\ �I � � � u,.,..,, � �i n t��1_ �2 ..� w.ve __ I� '�„� ' p ` � '�� i,-� �'� ,f I I -��' ; �� p��= � � �� ;� � �' � �i�. �� ,� � � IO 1 � �M �� t , w • � � � st.-.-. —N E.—— —�I2TN=�==%��ST.--=-- — — — — — ="'—�{;`q— � � �.. !1 I � � 1 � � � IEGEVD I'.^-�'w.^~__ _�__ _ __. ___ I A7LAS OF SEA7TLE ��1 c..w,..i.�.. r� .....�.,..., m cw+•a��eoaniei��o�. � �,,,"� � �,_,,,� _____ KROII rA7 GOMVANT,INC.SEATTLE w..f�..... O sM^+ f.�:��.. ][wiF �iHCH.]m�EFf I VI c� N iT� m�P ; 1 i , II. CORE DRAINAGE REQUIREMENTS 1. Discharge at Naturai Location: The existing site currently sheet flows across the property to the south and onfio the existing rockery along the soufih property line. There is a private drainage system within the Forestbrook Townhomes that col{ects the rockery drainage. The proposed drainage system will collect the runoff into the vault locoted a{ong the wesi properfy line and discharge inio a new pipe that will be connected directfy fo the existng catch basin that currently colfects the runoff from the rockery. The Townhouse drainage system discharges directly into Honey Creek. 2. Off-Site Analysis: � An �pstream ond downstream drainage anaiysis has been performed and is detailed in section III of this reporf. 3. Runoff Control: This project is providing a 1998 King County level 2 standard flow control. ' This matches storm duration for the haif 2 year through the 50 year storm I event. It matches peak flows for the half 2 year event. The flow control will be accomplished using a detention vault with an orifice type flow restric#or. 4. Conveyance System: The project will provide conveyance piping for the street drainage and , the lot roof downspouts. The piping will be sized to handle the 100 year � developed storm event. 5. Erosion and Sedimentation Control Plan: An erosion control plan will be prepared and wil{ be included with the engineering plans. This erosion control system will include silt fencing along the west and portions of the norfh and south properfy fines, construction entrance, seeding 8� mulching and clearing limits. A sediment pond will be designed as part of the initial grading and development of the site. 6. Maintenance and Operation: The improvements to this site will dedicated to the City and will be maintained by the City. The private driveways and drainage piping will be maintained joinfily by the applicable lots. 7. Sonds and Liability: The appropriate bonding and insurance forms will be secured prior to any construction on the site. " SPECIAL DRAINAGE REQUIREMENTS There are 12 special drainage requirements that may appiy to any project. In this case, none of them apply to this project. 89/06/2805 82:08 2e6-725-5793 �IELDYKEKt.�1 Y 1►�: r ,, . - '� . August 18, 2005 ' OFFICE OF THE fiEARING FXAM�'ER CITY OF ItENTON Minutes OW1�TF.RlA1'J'LICANT: Veldyke Realty, lnc. Cheryl Webber-Vcldyke S50 Rainier Avenue S Seactie, WA 981 t 8 CONTACT: Ale Kondclis CramcrNW,lnc. 945 N,Central #104 ' Kent, WA 98032 � Veldyke Short Plat ,. t LUA OS-a65, SHPL-H � LOCATION: 3 8]4 NE 1971 Street SL'MMARY OF RFQUEST: Hc�uing Examincr Short Plat approval for a ccvcn(7) 1ot subdivision of a 1.87-acre site. SLMMARY Or ACTin`v: Dcvelopment Services Recom.;�endation: Approve subiect to condrti0�5 DEVFI.OPME`T SER�'ICES REPORT' The De�•elopment Sen�ic:s Rcaort uas received by r};; F�a�niner on Jufy 12, 2005. PUBLIC 1y'EARI?�G: AFer review�ing the Devclepmc:�t Services Report, cx�:mi�in� available infonnation oti file w�ith the a�plicat�on,field checking the property and surrounding area; the Ex�miner ;cnductcd a F�b�ic hea:ir.g on thc suhjcct as fellow�s: .11P.1"L'TES The followurg min,rteS are a sumrnary of tJie luly 19,Z005 hearine. Th¢fegnlrecord rs recorded on CD. Tl�e hearing upened on Tuesday,Ju�y 19,2005,at 9;01 a.m. in the Council CI�ambe�o�i the se��enCh flovr �f the Renton Ciry Na11. Yarties wishing to tcstify were a�rmed by the Examincr. The foI)ow�ing exliibits wer+e entcrcd into the record: Exhibit]�o. �: Yellow file contair.ing the priginal Echibit I\o.Z: Neighborhood Detail'vSap application,prc�of�f posting,proof of publication znd other dpcuir,entation ertinent to tl:is uest. Ezhibit;�'o.3: Preliminary Short Plat Exhibif 1�'0.4: preliminflry Gra�ins& Tree Plan �: , Veldyke Short Plat Fiie No.: LUA-OS-065,SHPL-H August 18,200� Pxge 2 zhibit No.S: f'relimin Uraina e&Utili Plen xhibit No. 6: To o• a l� & '1'nee Surv Ptan zhibit No.7: Landsca Plan hibit No.8: Zunin Ma zhibit Na 9: C� of Dal a PJat Tht hearing opencd witli a prestntstion ofthe staffreport by Nancti WeiL Senior Ylannu,Devcl�nicnt Suvices,City of Renton, 1055 S Grady Wsy,Renton, Washington 96055. The site is located to the wcst of Union Avenue, north of Sunset and off of NE 19�'Strix�t to the south. Th�site is approximetcly 1.87�cres is prflposed to be dividai into sevcn(7)lots. "I'hcre is one cxia�ti��g residcncC on the site with acctssory structun;�and thtse are propos�d to br removtd prior to the building of the subdivision. The Zoning is Residentia!-8 (R-8)and all Ipts excacd che minimum requirements for thi�wne. Access is propostd offofNE 19°i Stret�a moditicstipn widtl�of42 feet has bun approvtc! to extend suutli to a cul-de-sac. A 2�-foot wide acctss easemern, over 7'ract A, i� proposzd offtha bur�or�he cu�-de-s9c co the W�sc. The site is relatively flat and no cri;ical are;is werc found. Env�,ro,�mental Review w•as not requ�red�i+�ce thcrti are no critical areas on tl�;s site. The prc�prr:y is cunsistent with thz Con:prehen�ive Plan for Reside��tia� Single-Family. T'he�ite is surrounded on thrtc�ides by�Res�den:ial Singlt-family s;ces, to the suuch is Commercial Arterid) witl� no access u:=ny ccnnection to that sita. "1'lie proposed site liss a net deasity uf 5.8 dw�alling units pzr ac,-e a�d does cornply w�i�i t}�e requireme:tits fur the K-8 zoning designation. .411 1ot�izes would bc.b�reater:han tl�e:nin;mum sta.ndard of 4,500 square feet for s;tes Src�ttr t6an ont scre. All IoCs appear to comply with t.he setback requirements and would be verified at the time of ind;vidual buildi:,g permit review, as well,alt lots comply r��ith arrsngement and uccess requinments of the Subdivision Regulatior.s. Fire,Traf�ie�nd Mitigation tees are to be irnposed as condition of short p;at approval. Tract 8 is proposed to be left as open space. Staff recommtnds that it be laz�dscaped�snd maintsined until su�h time as redevelopment of the adjacent property can be incorporated in some manner so th:it th�consistency of the loes may continue;o zlig;n with lots in diis proposed development. Trxct B will be ma:ntained by the homeowners association ss open, usefwl space for the exisiing homes unti!such time as the tract i�developcd. The proposed subeiivisio��will construct a new�ublie right-of-way intersertion with NL 19`h Suee� with a r5dius of 25 fret, excc+:ding the reyuir,:d 15 fect. Sien�a Terrace, �i existing single-fami(y develi�pment,;,buts lo;he caat oftl�e subjeci site,tl�er�fore the applieant shall install a 6-f�oc high w�ood privacy fence along the rast pruperty fine fur che length ufthe new strec.�t. 1�he concepwnl landscap�pl�n that w2s submitted planS fur landscapinb Tr�ct B as weU ai;street trezs along �oth sides and a minin�u�r of two trees per lot located within ttse front yard as a require�nznt ofthe Code. Lot 5 doz; not show�ny street trees,they were comp�nsTted by additiona] trtts elsewherc on the;i�e. ZZ/L0 3�d ��? ,�1,7J?� ?Y,�.Q��'1 EELS-SZL-9�?Z S0�Z5 S�E.Z/9e/E0 09/06/2005 82:88 ?e6-725-5793 VF1DYi� RERILTY INC , Vcldykc Short Plat .. Filc No.: LUA-US-(1G5, SH}'�-li Aueust I 8,2005 , Page 3 � Ms. Weil a.�ked that condition 5 he omitted fmm the staff report ac the conceptiia]la»dscape plan has been submitted. T1,e site is Ic,c.�tcd �xithin the botindsries of tl�e Renton Schc,ol Distriet The School Diserict l�as ind�c.�ted that they can accominoclate the additional studenLa. 'i7�e sitc is located in the Honey Creek drainage basin. A detention vault is proposcd to hc loc�led on Tract A in the southwest c�rner of thc site. in order to rcdt�ce tlu poi.entiai erocion and scdimentetion contr+ol to the sit� and adjacent pmj►crties the projcxt must cotnply�+�ith the Department of Ecology's Msnu�.l for Emsion Control. Staff recc+mmends the establ i5hment of a m�intenance agreement fo�a11 common improvemcnts,st:�rm draina¢e trac:.t,any utiliry easements and landseapin�. � The proper7�owner adjaccnt ta thc site. P�ul garflcnethe,asked to hsve noted on record that his water mctc.�r an;t ' etectrical lines may be impacted and need to be�e(ocated due to the construction of tl�e public right-af-K�ey improvcmuits for tf��c proposcd�ubdivision,and t?�at that wi1) he done not at I�;s cost. !A e Anna Kpndelis, Cram�r N W,lnc.,945 N Central, Suite I 04,Kent,WA 98032 statcd that she rzprescnts Sl�ercie Webber Veldyke. Regarding 7'ract 8, ii is ttu intent of Veldyke Realty that they would maintain contrul and maintenlnCe of tliat Tr�ct, it wouid not go into Ihe homeowner's asspciation ot have anything to do witt� tlieir maintenance o�intere�ts. The property would be meir,tained by the Veldyke Rcalry until the time of its evcntual development. llie Examiner�tatod that th8t would mean b'cld�•ke woald t�e s nmate property owner for a smal! trad of!and tliat would have its��u�n water meter,e!c. What exactly do tl�cy Izave proposed for tliis tract? ]�1s. Kondelis st��ted sl�c t�-aS not s�ire, �ut that whatever ncedet� to be donc:o maintain thc site would bc taken c�r�of. It w�ill be irrigatcd and maintain�d. 7�c homeowncrs wiJl not l�ave use of this tract Jzmes!aceer,Jregej•Eagircerin�, 9419 S 204'h place, Kent, 1��A 98031 sta+,ed ti�at he is t':c cngineer for the applicant. ReSarding Tract A,tl,e reason for a 20-foc�t easement ra:her lhan making il pzrt of I_ot 5, on tlie preliminary drainage and utifity plan, is becausc the detention vauft�oes right up to the easemern 1ine. If that a�as a Iot)ir,c there �vould be a five-foot setback invo(ved and the vault�+�ou1d havc to be smallet. at the present it is at t?ie m�nim�m size to handlc the seven lots. Secondly, if in tl�e future the vault needs t0 be expandcd to handle additional Ior.s on thc north end, it gives an arca to be able to do�tl�at. The vaults arc desi�ned to handle traffic loads. The eastern radius�urve on NL- 19d'has ]5-�eet oihaifTight-of-way currcnt3y fronting this property, an additional 10 feet are�oing to be dedicated for a total of 25-feet so the proper curvc radius�an be installed. On tlie east��de there is an cxi,ting 30-feet of ri�ht-of-way so tl,ere is plenty of room for an asphalt apron or wl�atever the City determines necescary to connect to the existing pavemet�t eanbound. !im T�21paY. PO Ro�c 243G, Re»ton,WA 98059 statcd that he lias develeped the property directly to the west of Tract A, and tliat the�e w•as no access to ihe rear of that property becauce c�f the steep ravine. He is in complete agreement witi� the present�lat and wi1(work with the developer in order to facilit�te die dctentic�n s}�stem and �ay a pruFortianate:;hare. They.vould like a 26-foo[casement for acCess. . Ct�ervl VJcbher Veldvke, SSOQ Rainier Arenuc R, Seattle. WA 98l 1$ stated that when she purchaced this (4nd slTe fiad ScverT� �nversaticrrtS w'ith the Dalpay family and to this date there 1�aa been no negotiations as far as compensation fer this easement. Mr.Ji�n Daipe,y 1r. nff,ered to sell one oF his three lots, ho��ever if he wxs:o � v�ldyke Short Plat � File No.:I.UA-OS-�65, StiPL-H Aubust 18,2005 P�ge 4 purchwe aq easement,he wanted to base it on ont lot thut did not seem fair. M$. Weil infcrmed me that my 20. fooi tasamant would only nllowtwo additionftl lots, ifs compensati�n forthe easement were reached. Therti is a 20-foot roxd and she would recommand that it remain a 24-toot road. The Examinzr stated that thst i�a private matter for the perti�s, if it's�20-foot r,risemant tt,�re ma� be somt limitations, if it is a 26-foot easement then there may be other limitati�ns or atlowances. Staff can outline that bofore any final judgments are made. This matter wou)d be a private discussion,similarly obv�uusly� it would b�die same wirh the tot adjacent to Tract S,which wsS also an issue in the Dalpay plac. if Ms.W�ber V�Idy{ce N'81115�O-fCCT IE1$T 15 W�LI!L VvII� bC.it is her properry. Jean Veld,vke,Jesn Veldyke Properties stated that sht repreunts W illiam Hurt,the property owner throu�h this process.� This issue of the easera�nt has cume up previously,ihe timing o!it is extrcmely important co complete this rrview and permittin;. Mr. FTurt is retirsd,they have movcd out of thr area��d thcy nced to have this completed Kavren Kittri�k Dcvelopment Servicc5 Division statcd that a 20-f'oot easanent is basically a joint ust drivewxy, 12-feet of paver�e��t snd so tw-o lot�total(Lot 5 a,id one additional)can access off of it. 30-frxt of�ve:ner.t allows up to tour lots nut Frontin6 an actur,l strezt,which would be a 26-foot easement with?0•ftet of pavcmcnt. The vauh would havc to be buitt�o sopport the traffic if it was tu be undemeath the easemr.nl. 7'he�xarn;ner inquired if the copography was such that,al�ng w�ith;lie scor,n drainage vau:t,w�hich would '.:;..� to taice in this water or would it drain itseJf into:he creek a:ea. MS. Kituick stated that it soppos�d}y would bo to the aouth,l�9r.laeger has made allowance so:hat if'tl�e llelpay's and tht ownra-s of th�;plat came to a��agreement that the sliort dist,xnce here, would be ebb:to teke tlie drainage K�ithout a laroer v�ult_ It would be a chall�ngt t�r:he Dalpay property�.i to��hat thcy wi�uld do with the extra storm w�ter. `i'hcre�-e hvo utilitie�t5�t are over this properry ihat serve the ad,jaccnt lot at the nonh end,the waler r��cter is locat�d in front of u5is psrcel ra;Jlei than che property t� the nor�h, by code it should be in fion[of the owner's property. Jt would have to be m�►•ed,or si»ce the water will have�o bt extended down thc str��t, an�eseiucnt could be put across and put in a new meter and forr:alize ii. They can pay the City to mo�•e it,or they cdn do it tl�emsclves. T1u elecuic lints would have:o be mcved as well. PSE hns just been movinb t}�e;.�to a»otlier pole in tl:e vicinity,either that or it wiU have to be put underground. PSE end th�develuper will have tu dtal wid� tliat issue. !t is not tlie owner'�responsib;lity, YSE or the property ow�ner of chis plat wiJl liave to take care of it. Mr_Wai stated that b�cause uf th�rcquired dedi�;xt;oii of a 42-foot mod;fied public street w gtt secess into this �ite, the residual property,Truct B,with a d�pth �f 38 feet at the closest point across and ihe unustial shape of it, basically laaves it not n:eeting de�•elopmeni recJuirements es a buildable lot, thc;-�fora retaining it as a"fracc for the pottntisl future development especially since the development ndjacent to Mt. Barfi�ac:ht's site t�as already bcen devEloped,the pvtentia!to get a more quality,)�igher density development out of this piece is enhanced by retaining this Traet_ ]f the property�wner does wish to retain and m8intain the Tract, it would be recomm�ndtd that it be landsc3ped,with xhe trtts that are sho�+�n along tlie aasttrn side rind to have it m�intainad as open spsez, grass, irrigated up to che point that it i�developed. Tl�ere should be a note on the face of tl�is plat dtsignating this Tract as opcn space,priv;:tely awned�for future development. The Exami�er cullecl For funlier testimony ragarding this projecr. "['here wa; nc�one else wishinb�:�sp�sk, and no fuither comme��ts from staii: T!�e hearing closed �i 9:53 a.m. ZT/P� �9�d ��:I �.1�'73� �vI,Q�?� E6LS-SLL-90Z 80�Z0 S60L/90/Ea e9/06/2085 82:88 2e6-725-579 � Veldvke Sl,ori Plat ' Filc No.: LUA-QS-065, SHF'L-N � AuguR I 8.�005 Pagc 5 � . FIl�TAIi�'GS,CONCLt1�STUNS 8c RECOMMEIr'DATION Havins review�d the record�n this mattcr,the Examiner now makcs and enters the fnllow;ng: F[TDINGS: 1. Tfu appl�ca��t,Vcld}�kc Rcalty. Inc.,filed a rec�ncst for an approvai of a seven lot short p(ai together with two tracts. 2. The velJow file containing the staff rLport�tlie State Envirpnmental Po'icy Act(SEPA)documentation and c�tber pertinent matcrials w•as entered into the r$cord as Fxhibit#1. • 3. Tl�c E;nviroom�ntsl Rcview Cummittee(ERC),tlie City's rcsp�ncible official detormined thst the pmposai is sxempt from em7ronmental review. While thert is e w�etland an the subject site, it w�c founc!to be heiow the tlireshold to trigger Critical Areas rtview. 4. Tiie suhjcct proposal wac re�iewed hy all departments•;�ith an intcrzst in the matter. 5. The subject site i5 located at 3819 NE 19t1i Street. The site �5 ioc..ted on the soutl�cide of NC 19th $treet. The sub,je�:t site is Incated two bl�ck5 wect �f Union Avenue Nr and onc bivck wcst of a :�t:��nent of Sh�lton Avenut T F. 6. The,nip element oFthe Comprehentive f'lan desi�nates the arca in H-hich the cutiject site is located as suitahle for the de��el�pment of single-family uses, b�rt does not manda:e st�ch dcvel�pmer.t u•:thout c�ncic�eration of'othcr paficies of thc Plan. 7. The svbject site is currently zoncd R-8 {5ingle Fa�nily- 8 dwelling units/acrc). 8. The�uhject site wac an�exed to the C�ty�+'ith;he adoption of Ordi��ancc 4070 c,iscted in June 1987, 9. The subl��t s�te is appmximate!y 1.87 acres or 81,457 square feet. Thc parcel is gcne;211y rectangular altliough it rarrows in a stairstep fasl�ion a{ong its northwesiern property line. Thc partel is approximace.ly 155 feet wide(��uth property line)by�pproximate;y 640 feet long(north to sou:h). l p. An cxisting residen;,e and c�utbuild;ng5 wo�ld be removed from t1�e w�ect.em sice of the 5ubject sitc if t}�e plat is apprv�•ed. 1 1. �rhe site sl�Pcs hently to the south with s1o;�c5 approaching approximztely 10 perce;;t at i:� :tcepest. 12. '�'Ae applic�nt proposes precerving some trees {ocated along thc,��cstern edge pf the pvice) but mc�st of the SO t;ees l��cated on the s;te wou(d be re^�oved. I 3. The applicarlt proposes dividing the subject site into seven lots. The lots would generally lie located �.•est and sotlth of a new cul-cie-sac public road. The 42-foot wide raad would begin at NE )9t� Screet and run c�uth along the eastern edge of the site and end in e SO-foot r�dius cul-de-��c. At the northern end�f tlie p�at Tract B would b�created. )t woufd be approxitrately 38 feet wicle and 247 feet long. Prupnsed Lots l to 4 w�uld be loca;ed along the�-este�,ecige of thc property w�hilc Pmposed Lotc S to 7 w��uld be located al�ng the southern ed�e. Trr.ct A woUld be a st�rmwater and �ccess tract located Veldyke Sh�R I'I�t � File Nn.: LUA-OS•OGS,SHPL-H Au6nist l R, ?On� Page 6 just�outh of Proposed Lot 4. The propoud locs would r$nge in size from 4,8!2 square teet to 6,655 square tcat. I4. The�pplicant proposes evzr►tually con�olidsting Tract B with adjoining property �n the wtst of the subject site. ?he s�u and narrow shape of this tract is definad by thC crtat;o��ot�the new aeeess roadway. As an uddly sh�pCd "remaindrr• parcel,the applicant proposes temporarily prrsFrving it az upen spau; with the liope of combining it with adjscent property and ro-diviJing it in the future. l5. Trt�ct A would provide taom for a stonn vault and a 20-foot wide ec..tss u�sement tltut would provide acces�to Proposed Lot 5 and to the rtar portion of a new plat w�st of the subject s�te. The rear or southern portion of this adjscent plat is s�parated by very sttep torrain from publ;c access. 'Ihia applicsnt can prov;de accxss to that area sinec the subject Site has much murt gtntle terrain. A 20-foot widt access e�scment c�uld only serve one�dditional iot. 16. I'he da:si�y for:he plat wauld be 5.8 dwell�ng units per scre after subtra��ting scre36e d�at would serve as r��adwnys. 17. f l:e subject site is located w�thin the Rcnton School llistrict. The projExt is expected to ge��:ra:e aPprnxi�uately 3 school abe chifdren. "1'hese stu�icr,ts would be spread across tht gra,�ies and would be a,�ig,�ed on a space available basis. 1 S. '1'ht de��elc�pmcnt u single-f�unily home� 19: AS�,oted above,�torir.Nat:1 ��:.L�4 �e �;IC::l:d Iu 8 �d'JlI O[1 i fcLl A. L.'..f(:17I'ty H,:.;;;{ �;;��,� i�C'-K.�, :J i:i,F south and then to a detenpon system locbtrd on third party property edjacent tu l Ioney Crrxk. The subjtct sitc is �n the Henzy Crzek drainag� basin 20. Sewer�nd w•e;er serv�ce would be provided by the C�ty. 21. 71�e City ha;created 3 fee structure based on appc�rt�oning thi;costs ofl�settina �he i^�pacts of new developinent on reads,fire se«�ices and pu:ks, "!'hat fet 5vucture �rovides a consiSienl iTle(hCd Gf mak;ng sure new development pays for its sharc of infrastructure. 22. Staff h:.s recommended tha�a fence be provided along tl�e zastem edge of thz new rofid to pro:ect :.h� �djacent pr�perty from impacts of 70 ncw vehicfe u�ps. ?3. TF�cul-de•s�c len�nh will:•en,uire humes alorg the so�thern excer.t to I,ave sprinkfers inat�il�d tor firc protec:ion. CONCL1;StONS: 1. 'I�ha proposed sl�o�t plat sppears tu srrve tl;e public use a�c1 interest. l�l�c applicai�t will he creatinp a ntw public su�eet m pruvide access cu the subjcct site and will e��en prov;de access for an sdditional lot �n s�ijactnt property to the we�t via an esseme,�t road. 2. The subdivision will crzate 2dditional housing opportunities in sn area �+�her� urt�an services such as water and se�vu zrc availablt. Thz creatio,�cf new ho��sinb will also i,�cre:sse th�tax bsse ofthe City. Zi!F� ?r,��, �?�I hl�=� 3>11�.Q��.� Ec c LS-_ZL-9�Z E9�Z0 S�QZ/90/60 09/06/2085 82:06 296-725-5793 �DYKE RE�LN INC Ya�t nailz _J . � Veld�•kc Short Piat - File Nc�.: Ll1A-�S-465,SHPL-H `� August 18,2005 � Page 7 � 3. Whi1e generally increasing the tax has�, ncw develo�ment does creatt additional burdens on roads, � parks and omer�ency services. State 1aw requirzs that�ew development make provicipn for par{cs, roads md othcr urban ccn�ices,therefore.the applicant will bc requircd to make provision for thosc I impacts by paying the appropriate fees, ' 4. The creation of Tract 8 as temporary open spaee chauld be clearly defin�d in the plat documents so that � rcsidents do not rEly on it for local reerutional needs. Als�. staff should draft requircmen4c for maintenance and monitor the nate of[his parcet s�nce it could become an evecore if it is not developed I in a resevn�ble timefrarne znd owned by a remote party. � ' S. Since tl�e aceeSs easement will serve both a property in this plat as we11 ac in a se�arate existing plat, ownership:�nd maintenance will require cpecific lan€uage assuring that the roadway is appropriate)y ' ,naintaincd. � G. The applicant will havc to dedicau the new madw4y. 7. In conclusion.the �roposed sf�ort plat appears to provide n reasonsble way to di��ide the cYisting larger acrea ee. � DECIslON: The proposcd shoR pla:is appro�ed subjcet to;he foUowirR�oadi:ions: ' l. The applicant shafl obtain a demolition per,nit and complete a11 inspectio�,s and appro�•a1s for all '' huild�n�s located on the proper.y prior to t!�e reeording of the fnal short plat. The sa:icfactic,�� of th;� rcquirement is subjeet m the review and approval of the Development Sorviccs Project Meiaeer Z. Tl,e�pplicai�t Shall rccord a restr�ctive covenant and have it noted on the face of the plat desi��;:n� Tract 6 as cpen cpace a;�d to ren:ein undevelr.ped until such time as t!�e abuttii;g westem prope.;y :� a�-a�lahle for censo�idati�n for future development. The saticfaction of this reqt,iremcnt ic subject t�thc rcview and�pro��sl of,he Devclopmert Services Project Manager prior to recording cf the short plat. 3. The applica��t cliall instail a 6-toot high solid wood privacy fence along the cast preperry line for tlic Icn�.rth of the»ew�;reet. The satisfaction of tliis requ;rement is cubject to thc review and approval of the Devel�pmcnt Serviccs Project Ma�acer. 4. T)�e appl ica��t shalJ pay the appropriate Transpvrtation Miti�ation Fee equal tc+$75.00 for eacl� new daily irip assoeiated wiU�the p-oject. Credit given for or�e existing:�esidence. Tlie Tranc�rtation Miti�ation Pec ch„II t+e paid prior to the recordinb of the shurt plat. S. Tlie arplicant�hall pay the;,ppropriatc 1=ire Mitigation Fee eqi�al to�4$8.�0 per ncw si,igle-family residencc. C'reJit�7�'ert for��ne exini�;g residence. Tl�e Fire :��i;igation Fee sh�li be paid prior to thc recordiiig�)F�he shart plat. G. Tl�e�ppticant�i�all have a note placed en the fAce of the final short plat stating the fire code requires i�of� 5.!and 7 to have sprinkler s;�stcros inscalled and maintained. The sstisfaeiion c�f this rec?uiremc»t is s��bject to the review and appmval of the Development Services Project ATan�er for rcvicw and apprnval prior to recording of thc shnrt plat. �'} ! _ Veldykr Shon Plat file No.: LUA-OS-065, SHPL•H A�gvst ]8,2005 Ya� 8 7. 7'be spplicant shall pay the appropriate Parks Mi�igation f'ee tqual w 5530.76 par i�ew sin6J�family I�l. Cr�dit givan for one existing residtnce. The fte shnil be paid pric�r tu the recording of the �Aort plat. $. 7?�e shcxt plat shall be rrquired to comply with the Department of Ecology's(DOE)erosion and sediment cuntrol requiremcnts in Volume 1! of tht 2W 1 Stormwater Msnagem�nt Manual. 9. A maintenance agraement or bomcowner'�as�ociation shall be created coi�current(y with thc racordinp of the�hort plat in ord�r to establish msintanance respunsibilities for al] sharcd improvamtnts, includi�ig utility easemcnis,st�rm dminage facilities.Tract�A and B, common Jandscaping dreas and fencing. Thc agreemtnt shnJl De placed on the faco of the fi:al shorl plat 10. Staf�shaU ii�rm�late a method of maintenance and monitoring th�state of Trsct B to xvoid its becoming an eycsore or nuisance. 1 l. Thera shall be language that appropriately sharts maintenance rcspons�bili,y for the easement:l�t serves Pr�poscd Lot 5 and:he aJjaca»t propercy to tl�e wcst. ORDE12t.11 TI-I;S I a`''day of August ZWS . ��' fRED�.xAUF � I HEARING EX P.�i�R TRANS?�'1lT`I`ED TI-1S 18"'day af August 2045 to the partics of rrcord: t�'anry 1�'zil Kayren Ki�rick Ve{clyke Rcalty, Ir.c ]O55 S Gr�dy Wsy 1055 S Grddy Way Cheryl W�bbcr Veld}�kc Renton,WA 58055 Renton, WA 98455 5500�iainier.4ve::uc S Seflttle,WA 98] f 8 Afe Anna Kondelis James)aeger . CrEmer N W, Inc. laeger Enb*inetring Jim Dalpay 945 N.Ccnval, Ste. 1 U4 94 I 9 S 2U4'"Place Y4 Box 2436 Kent,WA 98032 Kcnt, WA 98031 R�nton, 1UA 98059 Psul Bartknecht 3807 NE 19�'Street Rc:nton, W� 98056 TRANSMITTED TH1S I$`�day of August 2005 to the followin�: Mayor Kathy Keolker-1�`heeler St�n �ngler,l�ire ' Jay Covin�ton,Chief Administnrive Oi�icrr Larry Meckling,Building Officizl lulia Medzebian,Council ti3ison Planning Comrnission Larry W:i.rren, City Attor�ney Transportai:on Divisio�� Gregg 2immerm:�n,P13PW Admihistrator Utilities Division Al�x Pieuch, F.conumic Oevelopmznt Nt;l 1l'atts, D�velopme:;t Services ?T/TT 3��Cd �tJI h1�=N =y��413n E6LS-SZL-90Z �0�Z0 58@l/90/68 @9/B6/208 . - - Vetdykc Short Plat • F�1e No.: LUA-OS-OI��,St1PL-H ' Augi�st 13,2005 Page 9 lennifer�Ienninsy Development Services Janet C�nklin, Devclopmrnt 5ervices Stacy Tuckcr,Uevciopment Serviccs King County Journal I'ursuant tc+l�itle I�'.Chapter 8�Secti�n l 00Gof thc City's Code, rtaaest fo�reconsidcratiom m��t be fiicd in writine on or before 5:00�.m..Scptember 2.20(IS. Any aggrieved person feeling that the decisiun of the Facaminer is ambiguou5 ot ba5ed on erroneous proccdure,errors of law or fact,error in juagmcnt, or the discovery ofnew evidence which coald not be reaconably available at tFie prior hearing may make a writcen request Por a revie�v hy the Examiner within fourtean(14)days from the datc of the Exsminer's dccision. This reques2 shall set fortli tl�e spaific ambiguitiec or errocs disc:overcd by such appellant,and the Exarnir.er may, after rcview of the rceord,take furtlier action es he d�ems proper. An appeal to tl,e C�ty Counc:il is governed by Title fV,�hapter 8, Section 110,which requires that such appeal bc filed«�itlti�he Ciry Clerk,accompanying a filing fee of$75.OQ and meeting other specif�ecf requirements. ' Capies of thic ord�nancc are avaitable for inspection or purchxse in the Finance Deputment,first floor of City N�ll. An annea� mast be fited in rvritine on or before 5:00 v.m., SeDtember 1,200�. �f sbe Ex�min�r'a Recommendatioa or Aecision eont�ins the reqIIirement f�r Restrictive Co��enant9, the ezecoteel Covennnts�•ill bc�eenired txior to 9o�rcrval bq Citv Council or final nroceasinQ of the file. Yoo may contact thia of{ice for inforraatioo on f�rmatting covcnants. Tlie Appearance of Fairnecc�oct�ne provides that no ex partc{privatc one-on-onc)comrnunications may occur c�ncerning�ending iand use decisions. This me��ns that pxrties to a land use decisinn may not cr�m,mvnicate in private with any decisic+n-makcr concerning�he prepesaL Decision-makers in the land uce pmcess include both the Hearine E�2mi��cr and mcmbcrs of thc City Cc+uncil. All comrnunications conceming the proposal must be made in public. This public commiinication permits ail interestcd pzrticS to know;he contents of the communication end wou]d�Ilow them to openfy rebut the evidence. Any vipl,�tion of this doctrine weuld result in the invalidation of thc request by the Court. I T1te Doctrire�.pplies not only,o the initial public hearirg hut to aU Reques�c f4f RCG011�idCf�121011 3� H�ell as i Appea)c to the City Council. I ,� arr or RENrW� CITY OF RENTON SHORT p,�,qT k�roRO1NG N0, VOL./PAGC v � � SNORT PIAT No, 1r1pR 4'6LpyXE` REdy9'Y INC. . . K1kG COUNIT, WASNINGTON---- LOCATd'D 1N rtia N.s. r/s oF rxr s.s. ��, Sc"�: o,�to� �„�.,: ,��,,,. OF SBCT/ON �, 71DIINS}IIP 2J NDRTH, RANCB S EIST, fl'.1►f., � inch - �0 FT. XINC COUNTY, 1YAShcNCTON �0 � �o PORi1DN O�; N.[. 1/�, S.L, t/4, SCC. �, T. 21 NORTn, R. S C1Sf, M',11, � � _ _ IANU USC �ICTION NUl(BCk: l,�ftD RECORD NUTAHCR: "' �• — — LUA—XX—XXX—SNPL tKo—xx—xxxx � i .�,., - --�-- i �� - —.�. �r �` � �s� � �6 �� , � �� _�� i � � �� ; � v� S � � ' r � � � � R ' t � g 9 e r � e � �' � � � ; S e � � �w��sw � ; � � . K� �'� y L ec wn.n �-�r. a � a.ow �} y � d � �� .� .��r�ep� a� • � [�' u :� .wa ..,� .ns� .irw +.r .�a►ania ; s hIi �� 7 C 9� � �� _� p wo.sa.r a � C L � �c�� Y r B r � r b ' � p %'♦ 1 ! ', �,i.� � � � s,�K � y� �. .� �A q � a'� � K re € � � ♦W�r � � � ' F 1 � � �� A x �w k '� " """•"'• s r IJ ` � � � .l � � o t' �. _.....,o.n aea�M... Ipi t k a � 'a y! � �Q al• r t "-"- - � a A o 1 ' "-•"._... � i i� N � � --"-""'-' _ .r�c I � '-'----'-_ '+s � y '�' ru � x �r' `��l� 1 �i� ,�ura..u.�w ..rm ` ''�� t �� y Q � �: � �� ;p t � Y 5 � , �. ��pI Y r li � Mr h � �RF 1 .� � S . �1�'6`�r �� : � •t � � � rJ �� e �� ,� � � � mo �� , W '��r!'��.r1�: � � � K'I : R! 7 � Y � � Cramer Northwest I�c. �, �flIMlfPfl l4lk stpp�yrnr r,y,vCyq��,�,�,_,�,4 m Sun�ron ►lomm� t [npine�n � ��'^"'�'��uavrrwc.:u-r�.-.►a � � Y��N. R1(IRI�, S1[./1 W. [(M. WA YE037 I 1�'/K G1IA wL 1/4 1f,i�4�f:.�.1.l�r7Tl R!Wr.wr. \ _ m ` czLtHa:-<��o p...q ; o � t.��OLK51-o{��(�•II In.) �� 7G'�•rt u..`.Mo�. rt. !O�! :ovsMCGI °^ (iss1n�-�ne(r..� r � f-MNl1..r..,.,,.,,,..��„ �ICK[p tlY: SCJ,II� �[n� '" o.nic � r„ati . .c•n. �w � - .. .� ,. ..,.... �. �'�."''• � . .r�� .� .... � i r ilt. OFFSITE DRAINAGE A. UPSTREAM DRAINAGE There is no upstream off-site drainage tributary area for this project. The � highest property line is along the north property line, which is afso the NE , 19th St. R4W. This street has a C8 8� piping drainage system that infiercepts I ony runoff from the north and directs it to the west within the public ROW. The existing lot along the east property line and the west property line are generally at the same elevation as the subject site and would not flow ! onto the site. The south property line is the top of the slope and the site drains to this direction. B. DOWNSTREAM DRAINAGE The drainage from the site will be collected into fihe detention vault located near the west property line, near the southwest corner. The detention vault will discharge, via a flow resfirictor, into a 12" pipe within an easemeni. The d+scharge pipe will connnect to an existing type 1 catch basin located at the toe of the existing rockery, within the Forestbrook Townhome Development. This catch basin currently collects fihe drainage that flows onto fihe rockery from the subject property. This catch basin discharges into an 8" pipe that runs to the southeast at 4%. This pipe enters a type 1 CB that is located within a driveway aisle w+thin the Townhomes. This CB discharges into another 8" pipe thot runs to the south at 8%. This also enters a type i CB within a driveway. This CB discharges into a 12" pipe at a 13% slope. This pipe discharges into the 54" diamenter pipe detention system for the Townhomes. This pipe runs for approx. 200 ft. to a type 2 CB that includes the flow restrictor. This CB discharges infio a 12" pipe that runs for 90' to the south and into Honey Creek. Honey Creek is a class 2 stream with salmonids. The flows to the norfhwest and comes within 75' of the southwest corner of the property. The steep slope sensitive area tract will restrict all development to approx. 200' away from the creek, at the top of the slope. Honey Creek flows to the norfhwest and discharges into May Creek approx. 4000 ft. from the site. There are no road crossings between the site and May Creek. With fihe King County fevel2 detention requirement in place for this project, the developed runoff from the site should replicate the existing drainage and not alter the impact on the downstream drainage system. I understand that the level 2 requirement is a result of problems within the May Creek Basin, but will also mitigate impacts on the Forestbrook system. -� tl') c�. •�t��` ,' \ ,' ,, r�' ,,, , . � .. �� , — . .�� ' � , , v ' o.�� e.` i � i � I . � � ■ � - \� �.`.`.�\. . ` ; .`� .\ ,� �`� `. ` `. � ¢ .._ -- ��Othl�$� _ �� /��`� .�ey �\�� `�\�� SE_1Q5th�Pl .�s-i I..co a � •�-• + __ � � ` \` \ . � a Ino �5+ .. 4 ._--- \ . _ \ �` �\ .� , \_ �' \ � � � _ � y_[ -. _--' _. .. _ _ -- / V A ' � ^ - - _ _ - '� \ \\ • • \�ti `♦ /\�� \ � \\�\ \ \� y . .. I\ . ..��- � \ � `\ \ 1\\ ` ✓� ' _ �--'• ...-' � _..._ .._. ` ' , - .� �.`� . �� ,r' s�� N � �� . �� f�r . . � /'� ` i �. . .__ � ♦` � ♦ ��`�� \. �\ � ♦ � . � i � i A-10' ..... _.._ \� �7.� . . . .� _�__ � .;,�, __ .�a p.�_ — , _ � � �. . . ��__ ___: ,. ,. , , _ . , , � ,�_ , , . .�_ `_ . „ . . ��.,._ .-- l �-a �„ ,....-» __ o � ►o -- -- , , ,�. '� ;.,,� .;,,�, ,,,, ,, Y... � ;��, ,_ �, �� --= — a , , _ 4 , . ., ^,, ,r�-._. -�- .' , 1 � S -� �-- _�o- ,__ _ �� , ,�, � � � V . '`�� . � � ��! -i� � � � L_, _ .. e.66- c - � u /� � � ---- - ='.c-a-a��_... .� - - - _ ." '. � � T._._ ` �..� / \ ♦;�`; � \ �1 \ - ___ ...._ ' " " _ ' _ _ .. � 1 I � \\ \\ � ' ' '� ` ` ` 6th __._ . .• , ` _ G.-. \ , , �, � "�� c sE o _ ' '� _\��r -—_ ` ` � .�� S ' o,�w- - . -- � .`_ �� . � � �as i�.: — ••, � �� . �,` � `� �, __— - _-- ---_ Il. �... ,� � �, �, � � � ` . . , �. . ♦ ` ��( \�'\�\ �\� \� '1 ��JO Y1K 9: ._ _. ___ _. 6-�Z;--- -- -- ' �--- -� - - 1--ti.. 4--.��,�i-c i - _ _._ . -._. __ r.�\ , , , . � , . ,, . , , . _ _� �1 I .La�o ' -� .n- , �, - ' ''�`.\��,,, ,_. �,, ! _ _ __ _ _� • !1 _ 1K¢e --- \'� �.� tPlnn �. �1' � � �� r �. , .� �. .. _ - I_ , • H I !C6- � � ;��\�` `� __._ � � .�� I / .____ .� -� ____.. .l \ 1 - �.C�-It � l+.) � � \ 1 I ' . 11i _ 1 �- �.Cf tl ' � _ _ _.. \� 1 .��` .�. ' � ' �^./,.' .)/ � _ -1..1_ -" ._ -\ _� ...� . � U ,, . _ �I. � 1 1.\ � I � -I -.+' ��3� rb-�� °� N 17 h . . ,�,.� ��\. , � � ;r� ' - -- . �a�-� - - P _ .��-�• .a ,�. � ,`�' �� > - ` �; `_��_� ,'; '�,l' � � . �o o.�.-t �� ri µ_� �fa-e i, ; ��:. .\ �,�\- � i i � i i ��_ �4u-�_�y �-�� a'. -!� . it� � . 'y i `+\ . �\�`�\ , i�/�f'i�i� i � .__-._ �da.l I��-� �''?. �- -�--�-�= -.. .----- � . W- - �\ � `. \ _.\ � .`�� . � �' .... c. � � i . � �Iht _ i � . �� .�_��.�.� � � _ �"'�`I i i --- z _ � _ � , , '. � ` . ,rr '+� � - - . � y� , , ��' � �'' { __ -- - - - - -- - . ._ . _ �, _ --- Z ¢ . � -- •F�-' � --1 ` � .x,-. ."'-` _ .- __ I � � __ - - �' `-- �' ,;� �` ,^- -- -� �;tr`.�� --. _ ��=t � a��-��a�-� �.tf=� _ �� / % .�s�� •j�-� — .��z�' � ��"--==.��;. �_ ' --- L , � , - r ° � iV. PREDEVELOPED DRAINAGE The drainage from the existing site currently sheet flows towards the south and onto the existing rockery along the south property line. The existing site area to be developed is characterized by lawn, tall grass and shrubs, with a approx. 57 trees. Most of the trees are located afong the east and soufih property lines. Approx. 8 of the 57 trees will be saved. The project drainage area used the total site area less that small porfion of the site that drains to the northwest, onto NE 191h St. This area that drains to the north has a high poin# approx. 100' soufih of the norfh properfy line. The areo that drains to the norfhwest is approx. 8100 SF and includes the frontage area along NE 19th St. This area drains into the existing drainage system within the public street. There are no drainage improvements on the site itself. The existing frontage along NE 19th St. has an existing drainage sysfiem that picks up the existing pavement. The project drainage area of 1 .67 acres was used as the tributary drainage basin for fihe detention vaultlwetvault. The existing drainage analysis was performed using the "KCRTS" hyd�o'��l; . software and its summary tables and charfs are attached for referenc� The methods outlined in the 1998 King County Surface Water DrainagE Manuaf were used as guidelines. Folfowing this page are the data sh�.�� used for the computer input data. The computer summary sheets for peak flow and time of concentration cofculations are also attached. Below is a brief description of #he existing draina� 10 year peak flow: 0.13 CFS 100 year peak flow: 0.26 CFS total area: 1 .67 acr pervious area: 1 .51 acr ground cover: till past� impervious area: 0.16 acr� .� '� N.�'. 19Tf1 ST. r -- � - $rvr --�— 8 ,�'__"v.."'m_� O �. �_ 1' --- �n' � �'- •� - — � � .� �' t D' I . s�a'°n'w` i •� S is mv�eat o.rw ,P — — ' a•uv.0 cs rm , OVE DaST. 1 � � I' � No�-t 101.�xgfl � ; ° g ! � n�"' �As��. = �I o�.�— , ;�� N "�� 4.5 LWDSG ti i Il (�716 Q ; � n�sxe �' i � � � I I SO uT"t-t , � �o�n _ � Y •6 �PSS�►1 ,� _� �` I� � �::=� /� / a �' ' � � \ �Y11�• � � � `.�e�a� � `� f I �m"- � 4: o � ' �� ; \ ^i' �� . O-. � -� .a�s n �S � '_13{�.H.. i ;: �,c�� : ,� ,�.� � \ -- i $ �,�_, '�� 5--- - s 2 � � T. `� L7 � � . � I � L1� �� s: _ '113' �c•n � - - - � �,� 1'�� •�� / 0 3 _ � `�/ ��b ,.� i g _ / � —�3 --�.- � � ..'c' / E :�e T� 4 - - - - �i �.E/ � I � 1— ,�T/ � (�f�+�+'�,- �_ ' a :E� �1�✓ � ` �� . 5 �JR - '6` �— �� 59.2' R � ' \I � ,, .�r �\ '.C:iE � t5•�RUN I1 '� ——— I � �� i..547� i o I '�� 8 �� .,z �� 6 I�I � �I � � ��= gc7� ,,;�5 i 1 55' I 50' � --.,c ,_ - --- �ll 155.G1' — .c. �i'os _rg4P9 �p� PR�-�E�� D R� �� s� r.� s . � I i : �a�� S�-E°�2-r --��---- — -- --- ; _ , � � --- - --- -- �R�- - -�E�c,�c,_.c�_ P�_-� �f�R-,t� _ , - ---- , � . __��-- - --�.�;��a s�-� �-�.�. � o r„ � s� — �--- _ � , � Cp J�� _ ----- � b S��_ ��-o� v�n N o�r f--�n e�.� -- ' '� ��-��n s 'b 1/1 o r J1 W� ��--�-�e' —1�-a-t - g I o'cJ S� -- �- --��-`��— - Q�'�-��—�_ } � �c� — � = __�c��= -- --- ------� 1 � ---��o — — _ < < c� � r�G. --- --- ----- _ --� �Ro��o �� e __ --- .�--- - - � --- —� �m�� s � — - ------ ---�.- _ �,�-�� h�u-=�`�,-=��-i-,—cv�nG---�s - _ ---ZZI`�`.�_.��nc2��>--�``' - ---- --- - ��-Z S� < _.— _ ___ ----- - ��j�- �� -_ `" � 4-�� '�t Q�^ �- - � � p.,-�'cL. I t `� -- - - - -- - —--q - - - � -- —--- (�Z �'r� �� C.p.Je.r-e-d� �-� - -- - - ----- � �� 3 .s►= -- = p �� c � --- -_ � -�e�Viov� s — - -- ------1,��--o_,_� _ ----�- � �-�� -- - _U��_ 1� I i P�� ------------__--- -- - ------ ------ ------- _-----� . � k�'�2.i 5 __'?�` -��v. �,ws. -- ----- �� C'�Z = C�, O�� C�S ( o .o�-; b - � t33 �S --_ _--------- - ---- -�-a�=-_- ----�------ ----- ---------- ----- -- �� _ o. Z r� cc=s __ _ _ c� __��,�, = O,Z5�8__G�S_�_ Qz.� _ ��L�g WEBBER SHORT PLAT KCRTS PEAK PRE-DEVELOPED FLOWS TOTAL AREA: 1 . 67 ACRES IMPERVIOUS SUKr�ti(:�;: u. l� AC;K�S PERVIOUS SURFACE: 1 . 51 ACRES TILL, PASTURE Flow Frequency ?�r:alysis Time Series ciie:�;�e.�s� Pro�ect Locatio�:Sea-Tac ---Annual Peak Flcw Rates--- -----Flow Frequency Analysis------- Fl��.�r FR�tP ��nk Time pf ppak - - pPakc - - Rank Ratnrn Prnh ;CFS) (C�'S) Feriod 0. 133 3 2/09/Oi i5:00 0. i �00.00 0. 990 0.074 7 1/05/Q2 16:00 2 25.00 0. �60 0.138 2 2/27/03 7:00 .133 3 10.00 0.900 G.G4i� i's 8%�riius �:�u O.i�� 4 �.Gii u.�uu 0.079 6 1/�5105 6:00 0.125 5 3. Q0 0.667 � , -,� ��„ ,�. . �„ -, �., „ -.�.. z �� vi � G _G. v ,. . v.�� c _. ��J u..�.�i:v 0. 125 5 11/�S/C6 3:C0 C. �7S � 1.30 0.2�1 n,��R i iinain� ti�nn n_ ncti R i, in n. ng� Ccmputed Feaks 0.2�8 50.00 0. 980 . � . V. DEVELOPED DRAINAGE The developed project will include the new detention vault 8� wetvault located near the west property line, norfh of the southwest property corner. It will be located within a drainage tract that will be used as a private access easement for 1 of the lots. The site drainage will be routed into the vault using catch basins and pipes located within the new road. Each new lot will be furnished with a piped drainage stub that will be connected to the street drainage system or with a pipe in the rear yards of the lots. The area that was used for the developed drainage into the vault includes the 1.67 acre south basin plus the area of the new road in the north basin. This is an additional 0.1 ocres for a total developed basin area for the vault of 1 .77 acres. It should be noted that the allowable discharge from the vault was based on the pre-developed south basin only of 1 .67 acres. This will mitigate for the diversion of the road runoff from the north basin into the south basin/vault. There is a porfion of the frontage improvements along NE 19th St. that cannot be piped into the vault. This area will be connected to the existing drainage system within NE 19th St. at the norfhwest corner. This area is not detained or treated, but is only 930 SF. Of this area, 726 SF is subject to vehicular traffic. This bypass area is off-set by the 1500 SF of existing driveway that is being removed and replaced by the new road that is being piped into the vault. , The detention vault was sized to meet the performance criteria established by the King County Level 2 detention standard. This criteria is that the pond can only release at a rate not to exceed SO% of the 2 year pre-developed peak flow (from south basin only) while retaining 50% of the 2 year developed peak flow. This is the same for the 25 year peak , flows. Additionally, the storm event duration for the developed site conditions must match are be less than the pre-developed storm duration, for the 50% of the 2 year flow through the 50 year storm flow. This is the level 2 standard as specified in the 1998 King County Manual. A wetvault will be used to meet the water quality standards. The wetvault will utilize the detention vault area and will provide the required dead storage below the detention live storage. Similar to the existing condition, the KCRTS method was used to determine the peak flows for the various storm events. A duration curve comparison was performed to evaluate the vault performance. The computer data sheets for the developed flows follow this page as well as the works sheets and the time of concentration calculations. A brief summary of the developed drainage characteristics are: . 2 year peak fiow: 0.343 CFS 10 year peak flow: 0.412 CFS 100 year peak flow: 0.690 CFS total area: 1 .77acres pervious area: 0.56 acres ground cover: till grass impervious area: 1 .21 acres ground cover: impervious � \ 1 � � � � ' � � � � � 1 � � � � � � � f~ . . � �'I ` 0 O � � tu co to y �'' t . , `� •� i � � ' � , tD �` {,,,� (� Ua : (p c"� _ _ _ � j , 1 . 1 —c v -- c� � z � ; . , '' ` � �1 \ oa , 2 . ca _ , � `,. 1 � . ; �- �' � _: : � `�. '�, � , � � �; _ � , ` � �, =;. �. ,� ,, �� :� , .. / ` 1 , � � ' � g ,l' 4 f! �. 4�i. '� ..i'�fi k �'. � ' � . /� ' 1 �1 , I , . t ,� � � ttA < < �, + ,n F+' _� � � ' �'1� 5 1 i ;. �� ( ` ' � I ti 4' �r3 T ��j_.�y�� 1 �,~�;4►.4.s.'ri'r�v!'re, �i •.4. � � 4� 1 ' 49 � „+ a �,.� . t,. \ • i 4 �' � ' r'r'r �I N �ut � �+ r � � ': r �� ; ' �: ��`'�`'��P, ,�� .� ; • '�` '�' � ,�� rs��",i;��s�r� ,�,�; , � . 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" Computed Fea;cs 0. 611 50.00 0. : _ _ � r DETENTZON VAULT DESIGN . _,. �n,,,-.,•v ur•-,m� Facility Length: 45.00 _ _ racility h'idth: 40.00 ft ' Facility Area: 1800. s^. . Effective Storage Deptn: 9.50 f- Stage 0 Elevation: 900.00 r Stcrage Volume: 17100. c. Riser Head: . - Riser Diameter: _ Number cf orifices: Orifice # He_ght �iamet�= __��_.��:c __�._.��__ ;ft? (in) (CFS) (in) 1 0.00 C.80 0.053 2 7.00 1.9G 0.089 4 .0 Top Notch Heir: '�one Outflow Ratinq Curve: :�one Stage Elevation Storage Cischarge Fercolation (ft) (ft) ;cu. ft) (ac-ft) (cfs) (cfs) 0.00 500.00 0. 0.000 O.00O O.CO 0.01 400.Oi _8. 0.000 0.002 0.00 0.02 400.02 ?6. 0.001 0.002 0.00 0.03 400.03 59. 0.001 O. Q03 0.00 ' 0.04 900.09 -2. O.0O2 0. 009 0.00 0.05 900.05 9�. O.0O2 O. 009 0.00 0.06 900.06 1�8. 0.002 0.009 0.00 0.07 900.0? 1�5. C. 003 0.009 0.00 0.23 400.23 �'_4. �.010 0.008 0. 00 0.39 400.39 702. 0.016 0.011 0.00 0.55 400. 55 990. 0.023 0.013 C.00 0.71 400.71 1278. 0. 029 0.015 0.00 0.87 400.87 15E6. 0. 036 0.016 0.00 1.03 401.03 1859. 0. 043 0.018 0.00 1. 19 401.19 2142. 0.049 0.019 0.00 1.35 401.35 2430. 0.056 0.020 0.00 1.52 401.52 2736. C.063 0.021 O.CO 1. 68 401. 68 3029 . 0.069 0.022 Q.00 1. 84 901.89 3312. 0.076 0.024 0.00 2. 00 902.00 3600. 0.083 0.025 0.00 2. 16 402.16 3888. 0.089 0.026 0.00 2.32 402.32 9176. 0.096 0.026 0.00 2.48 402.48 4464. 0.102 0.027 0.00 2. 64 402. 69 4752. 0.109 0.028 0.00 2.80 902.80 5090. 0. 116 0.029 O.CO 2. 96 402. 96 5323. 0. 122 0.030 0.00 .� � 3. 13 403.13 5634. 0.129 0.031 0.00 3.29 403.29 5922. 0.136 0.031 0.00 3.45 403.95 6210. 0. 193 0.032 0.00 3.61 403.61 6998. 0. 149 0.033 0.00 3.77 903.77 6786. 0.156 0.034 0.00 3.93 903.93 7074. 0.162 0.034 0.00 4 .09 909 .09 7362. 0.169 0.035 0.00 9 .25 404 .25 7650. 0.176 0.036 0.00 9 .41 404 .41 7938. 0.182 0.036 0.00 4.58 409 .58 8244 . 0. 189 0.037 0.00 9 .74 409.79 8532. 0.196 0.038 0.00 9 .90 909 .90 8820. 0.202 0.038 0.00 5.06 405.06 9108. 0.209 0.039 0.00 5.22 405.22 9396. 0.216 0.090 0.00 5.38 405.38 9684. 0.222 0.040 0.00 5.54 505.54 9972. 0.229 0.091 0.00 5.70 405.70 10260. 0.236 0.091 0.00 5.86 405.86 10548. 0.292 0.092 0.00 6.02 406.02 10836. 0.299 0.043 0.00 6.19 406.19 11142. 0.256 0.043 0.00 6. 35 906.35 11930. 0.262 0.044 0.00 6.51 4C6.51 11718. 0.269 0.094 �.00 6.67 906.67 12006. �.276 0.095 0.00 6.83 406.83 12294 . 0.282 0.095 0.00 6. 99 406. 99 12582. 0.289 0.096 0.00 7.00 407.00 �2600. 0.289 O.OS6 0.00 7.01 407.01 i2618. 0.290 0.046 0.00 7.03 907.03 12659. 0.290 O.C48 0.00 7.C4 907.09 12672. 0.291 G.O50 0.00 7.06 907.06 12708. 0.292 0.052 0.00 i.07 4C7.07 12726. �.292 0.056 0.00 7.09 407.09 12762. 0.293 0.061 0.00 7. 10 407.10 1278�. 0.293 0.063 0.00 7.12 407. 12 128_6. n.294 0. 069 0.00 7.13 407.13 128�4 . 0.295 O.G66 0.00 7.29 407.29 13122. Q.301 0.076 0.00 7.95 407.45 1391C. 0.308 0.083 G.00 7.61 407.61 13E98. 0.314 0.090 0.00 7.78 407.78 14009. 0.32i 0.095 0.00 7. 94 407.94 14292. 0.328 0. 100 0.00 8. 10 408. 10 14��0. 0.335 0. 105 0.00 8.26 408.26 19868. 0.391 0. 110 0.00 8.42 408.42 15156. 0.358 0. 114 0.00 ' 8.�8 408.58 15944. 0.355 0.118 0.00 8.74 408.74 15732. 0.361 0.121 0.00 8. °0 408. 90 16020. C.368 0.125 0.00 9.06 409.06 16308. 0.374 0. 129 0.00 ' 9.22 409.22 16596. 0.381 0.132 0.00 9.39 409.39 16902. 0.388 0.135 0.00 9. 50 409.50 17100. 0.393 0.138 0.00 9. 60 409.60 17280. 0.397 0.947 0.00 9.70 409.70 17460. 0.9C1 1.010 0.00 9.80 909.80 17690. 0.405 1.740 0.00 9. 90 409.90 17820. 0.409 2.590 0.00 10.00 410.00 18000. 0. �13 2. 820 0.00 10. 10 410. 1C 18i80. 0.417 3.080 0.00 10.20 410.2C 18360. 0.421 3.310 0.00 '- 10.30 410.30 18590. 0.426 3.590 0.00 � 10.40 910.90 18720. 0.930 3.790 0.00 10.50 910.50 18900. 0.934 3.990 0.00 10. 60 910.60 19080. 0.938 9. 120 0.00 10.70 910.70 19260. 0.492 4.300 0.00 10.80 410.80 19490. 0.496 4.970 0.00 10. 90 410. 90 19620. 0.450 4. 640 0.00 11.00 411.00 19800. 0.455 9 .800 0.00 11. 10 411.10 19980. 0.459 4.950 0.00 11.20 411.20 20160. 0.963 5.100 0.00 11.30 411.30 20340. 0.967 5.290 0.00 Hyd Inflcw Outflow Peak Storage Target Ca Stage Elev (C�-Ft) (Ac-Ft) ��-`��i 0.69 ******* 0. 9.63 409. 63 17330. 0. 398 1>'��2 0.45 0. 19 . 4 5.77 405.77 10386. 0.238 3 0.91 **�}*** . 9 7.52 907.52 13530. 0.311 4 0.37 ******* 0.03 3.10 903.10 5578. 0.128 5 0.36 ******} O.C9 7.71 507.71 13874. 0.319 6 0.34 ******* 0. 19 9.98 409.48 17070. 0.392 7 0.31 **}**** 0.03 3.65 403. 65 6576. 0.151 8 0.28 T****** 0.09 9 .37 904.37 7861. 0.180 ---------------------------------- Route Time Se:ies thro�gh Facil�ty Inflcw Ti:-:e ceries ri�e:dev.tsf Outflow Ti.�:e Series File:rdout :�:flow/Outflcw F.nalysis Peak Zr.flow Discharge: 0. 690 CFS at 6:00 on Jan 9 in Year 8 'eak Outflow Discharge: 0. 605 CFS at 9:00 on Jan 9 in Year 8 ?eak Reservcir St�ge: 9.63 F� Feak Reservoir Elev: 409.63 Ft Feak Res2rvcir Storaae: 1i330. Cu-Ft . G.398 Ac-.� _'_ow Dur��on rrom Time Ser�es File:rdcu�.tsf �utoff Ccurt Frequer.cy CDF Exceecence Probability CFS % s ° 0.002 _8246 62.371 0'2.371 37. 629 0.3�'0E+00 0.006 5196 8.479 70.845 29.155 O.L9L�+00 0.010 9193 6.756 77.601 22.399 0.224E+00 0.014 3562 5.809 83.910 16. 590 0.166E+00 0.017 3353 5.468 88.878 11. 122 0.111E+00 0.021 2637 4.3C0 93.17� 6.�s22 O.E82E-01 0.025 i191 1.942 95. 121 4.879 0.48�E-01 0.029 1140 1.859 96. 980 3.Q20 0.302E-01 0.033 703 1.196 98.126 1.874 0. 187E-01 0.037 458 0.797 98.873 1.127 0.113E-01 0.040 346 0.564 99.437 0.563 0.563E-02 0.044 179 0.292 99.729 0.271 0.271E-02 0.048 61 0.099 99.829 0.171 0.171E-02 0.052 6 0.010 99.839 C.161 0.161E-02 0.056 2 0.003 99.842 0. ?58 0.158�-02 O.C60 3 0.005 99.847 0.153 0. 153E-02 0.069 1 0.002 99.848 0.152 0. 152E-02 � .� 0.067 6 0.010 99.858 0. 192 0. 142E-02 � Q.071 8 0.013 99.871 0.129 0.129E-02 0.075 6 0.010 99.881 0.119 0. 119E-02 0.079 9 0.015 99.896 0. 109 0.109E-02 0.083 11 0.018 99.914 0.086 0.869E-03 0.087 10 0.016 99.930 0.070 0.701E-03 0.090 4 0.007 99.936 0.069 0. 636E-03 . 0.099 6 0.010 99.946 0.059 0.538E-03 0.098 4 0.007 99.953 0.097 0.473E-03 0. 102 2 0.003 99.956 0.049 0.490E-03 0.106 2 0.003 99.959 0.091 0.406E-03 0.110 4 0.007 99.966 0.034 0.392E-03 0.113 3 0.005 99.971 0.029 0.299E-03 0.117 9 0.007 99.977 0.023 0.228E-03 0.121 3 0.005 99.582 0.016 0.179E-03 0.125 2 0.003 99.985 O.C15 0.147E-03 0.129 2 0.003 99.989 0.011 0.114E-03 0.133 2 0.003 99. 992 0.008 0.815E-04 0.137 4 0.007 99. 998 0.002 0.163E-04 Duration Comparison Anaylsis Base File: pre.tsf New File: rdout.tsf Cutoff Units: Discharae in CrS -----Fraction of Time----- ---------Check of Tolerance------ Cutoff Base New �Chance F�obability Base New `aC:,ar:ge 0.041 I C. 66E-02 0.53E-02 -20.7 I O.E6E-02 0.041 0.090 -2. 1 0.048 � 0. 98E-02 0..7E-02 -64.3 I 0.4BE-02 0.098 O.C41 -i�. � 0.056 � 0.36E-02 0.16E-02 -55.7 � 0.36E-02 0.056 0.043 -23. � 0.064 � 0.26E-02 0. 15E-02 -91.1 I 0.26E-02 0.069 0.045 -2°. 0 0.071 I 0. 17E-02 0. 1�E-G2 -23.3 I 0.17E-02 0.071 0.051 -2�.2 0.079 I 0.12E-02 O. 1GE-02 -15.8 I O.ZLE-OZ 0.079 0.073 -6. 6 0.086 I 0.98E-03 0.72E-C3 -26.7 I 0.98E-03 0.086 0.080 -7.7 0. 094 I 0.70E-03 0.59E-03 -23.3 I 0.7CE-03 0.094 0.088 -6.5 i 0. 101 I 0.55E-03 0.9EE-03 -17.6 I 0.55E-03 0.101 0.094 -7.7 � 0.109 I 0.33E-03 0.36E-03 10.0 I 0.33E-03 0.109 0. 111 2.0 'i 0. 116 I 0.21E-03 0.23E-03 7.7 I 0.21E-03 0. 116 0. 118 1.4 ' 0. 124 I 0. 13E-03 0.15E-03 12.5 � 0. 13E-03 0.129 0.128 3.2 0.132 � 0.82E-04 0.8��-C'-_ 0.0 ; 0.82E-09 �. 132 0. 133 0. 9 Maximum positive excursicn = C.CC8 cfs ( 6.3�) occurring at 0. 120 cfs cn the Base Data:pre.tsf and at 0.128 cfs on the `�ew Data:rdout.tsf i I�laximum neg�tive excursic� = 0.029 cfs (-34.6�) � cccurring at 0.070 cfs on the ?ase Data:pre.tsf and at 0.046 cfs on the I4ew Data:rdout.tsf .c0 � ' � rdout.dur �� pre.dur ,, ..fE� - :�� - :.�: 0 __�` -� , � � �. r �\ 'K N e— — O � .�;� I ;� � � � ; O � O � � � .,;� = U �, .� � a� � ; � �? � = c� � � v j �R�- l.7EV EL.D �{� � ��r � . . ��s�.+-t�Rc�� 0 � 00 `� , �, \��.. o ; ~�... , �--_, ; � � N I O � O �y.. .....��. . � F�r-' � � I i ! I � 1�1� 10 -5 10 � 10 -3 10 -2 10 -� 10° Probability Exceedence : � � � ;� = S ' � a � �' �S --- ------- ----- , �a-� n �—aw��o�� _- - ' ,-� _ � � � ---- - � �_ � �-- - - � � �� = �-��''c�' —��`—� � -- � — ��5��vra I "�� v�� , c`'�J�- -,p __ -- ----- - � .; T7�- 'a V� C� Q I � � � � +7----- ! � 00�� _ --- - 0012 � = a � o�a��a�—_� - i --�---- --- - — ----- — - -- ------- . �j on I Z = -� }\ _ -------� - -- - ___ --- -- --2� -------- ----- --- ----- ------- --- �� 'O��b�-b2 SZ' 4 �-�bO� ZS�_�� _ ��- - --- �.S �b�fiZ - � �. / o�—�-- -- - ---_�� S� `�,� _- -�- ---- �� , n - �r — � '�4�ZS = � --- - — - -- ---- — L� ,o_�--- z� _ a ---- ----- --- � sZ�o �- . o = -� _ __ _ , - .� � - `�^�' , -- --- Qre G� - �--__�►S�— . � —=J N ��.�S----- --��<1 xd 1��C''� I ---- ------ � — -- -- � a s ��1 - , _� VI. CONVEYANCE SYSTEM The piping system was sized to accommodate the 100 year developed flows, as calculated using the Modified Rational Method that is outlined in the 1998 King County SWM Manual. The pipes were designed to handle the 100 year flows without any backwater effect. The tributary area for each catch basin has been identified and shown on the attached catch basin tributary area map. The area for each basin was determined by scaling the plan and also by using the lot areas shown on the shorf plat plan. The runoff coefficients used were based on the area usage: 0.9 for roads only, 0.6 for lots and roads, and 0.3 for lots only. The initial segment time of concentration is assumed to be 6.3 minutes. The attached table and calculation sheets show the calcs for each catch basin area as well as the cumulative flows and respective pipe capacities and velocities. �b� o_-� � -��ii Lo• o = � - �2� � <2) bt� 1 ; �r1 �`� (�'`.'S'`��Sa� �e ��y ��. . 9� � S� a� ,o _ � 1 .� � ,o _ � �� _= as� -;-. ��.�s, _ __--_ ___ ; __ ---- , �� -�- �� '� _(�°w�_ � �-'°`-1 -�-�� -- - __ __ � �� __ ob� o_� ` �-� Lo' O = �S oS 1 � � <�) eSI _ � �� `�'�� .�° ��y � - L ��_ - ___ eb'o=� � " '�-�I �0 ' O = �s c�C_2 = <2 �c41 _-- � �� ,� �� a� . 11 �.�'J �b'o=� ' ��t °�o' p = � ��.2 3 �Z) ��f '. �1�1 --��'�d p.�.�':�,,�� t�y -�� . � � 1 � �� s�.a � �� ; � ��.� S�o� �o �cz.+ �c� �j � o = � �� s �oo.� �� b ' O = � 'S �s�Ll.c�U�+nS.s"n 'a C��O� ,� � �� .�-v�2 Y�I�a C.� �e V c1� � 1 _ �on w�� -��-�a C� "�-u"o� �v�� ' __ _ �`� � � `'�l-f-� -(J�'�' �'°�' � �� ' � � ___ _ _ '� sa.�,��y , __ _-- -- - `� -- - �o a.� . ��1r1 �v►;M o _ -� --- � _ _ _Q_ _ ___ __ � ----- n J�' � � ,,� _ _s - -- - - - S#,��1 � (��yl N1 S NOiL-�� `�1S�S ��d 1.�1��0� � � �. � . � --------- .. ----- - --- - _--- _ __ __---_ _ _ -_ __-- _ - _ �� , ----- -_ .. -- _ - -- --- ��- t��,�� of �R�v� _ � N� -� l�-�s � z � 3 : _ � � (Z�+ C��St .S�Sb _= 14`�� 4- � = 0� 3¢ r�c. � c=d.t.� --- -------------- _ _ ----- -- -- ----- - C�� --- _ _ - . `�f� ��I 6 + �,�s# �, � �� ;� � _ _ _ _ -- 3o(c�z�+ -�T S� + �S�o+�3 ro } Scxeo - 2�-��4 s� --- ---- __ _ -- = 0�.57 ►�� . � C -0. �0 . � �Z ' _ r�.�' � : _ - - --— -- ---T_ - --- -- --- - - --- -- �I-3g�3 51= � o. �� , C = o , �o �---------- ------------ _ --- --_ _ CP�r�-t—t �p�S��c �,�8 c�T��( A�FZ�,s � �, � � ^_ � �� ,_,��,„•� A PORTION of the S.E. 1 4, SECTION 4, TOYVNSHIP 23 N., RANGE 5 E., W.M. � I � " �r•au4�r� ' � 1 un wis.rtar/risa y;. i wsr � x.�"��I-M[1 n K:er � � � � ``>..Yyy I I •i�asa�r u � � sr��eb � �� ` I �r:.u.� � •lLl�L.....��' C�719 , I 1 I � -A�C:yY>'� --CCN7[R i�MNL YO%CL.STIiUCNRC— i I �0 --snrci wuc�a n Nree ae i.k)ty,: (SEE YAIF eox oeiu�s„Eer e) � � il "i xo'wr uo. (�n[r.1 .�° iui:s � ,.�� ;a r. toi-a . �� -. � '��cu ar a iur:a � � � '��,,' ior.i e � . �or:n "— � 9l1II-_I7K 1 ��0� ior 1� ' ',�. rp�Y � -=� /wr ii i°.u.my7/ ..�o�a�ier t�wni � ��:om rr a°� p�S;►.�e 1f r._ � �ni:� � .>v i, �� r.�a R i/ .�' � � � �s°u�e�•ni.�i��r ' wo�rcH¢° � i[:.t�.i nw:.ii W 6 � \'�� ' wiw:a�.n �,n / I �H - M � __. � 91103'12Y 61ID.b' a�.er /'� [MD iLNCC [»o ' ..�\ �LOEWNX ` �_—_ _"_' ' - S___ • ,�'''`�"�.�.s� ='� : ��•^� �— ' REDMOND AVE. NE � �� ur• _TNf�_ �� --i��' `\ �+ �.w . •"ise . �-'�'� � � I r�tw+� �,.�ru s _ _w��z.aEr Si ox ti�; -�.. -�:" +M� 7 � _ --- ��oema , i _ � _ � . T,'t� 1 r,r — -- �.�� – oinl q �: .. _ _.. a . _"'--.. . . " ;,�„ •.' .f-., --w . .�.�'— .. _— ."°: � �] i __ � - w- w _ _ �� - —_ - i�a-i]'a[n�7..K: _ � _ I ._._w. 1 1 ,' ,� �r � - � � � � 'i + pr��R��i4'�� ---�. ,�' �� '- _7---- -- - -_ owr 1 �mu nie '�� l � i �I 4 �c�7a� rn��-� r- - •�-�------- --- �'-°� L ic:s9o.�i � / _ ��.� M1. � / L aa� � sr"�-3.Mle�a � ." ; '..,..,r" i; / � - � ?@\ / � •-- � '� I—�'-t;,°�{ TRACT B �.r..�4,r.� �.w.rt —� _ �,�,,., / aze� � �� •.. �s' r:•n.e� �Y.w �'nc wr rt s.sa,r�t� �ct tlrt. - � wu in.a� T __—_ �r.-. --, '-1 e neuc o�bw y � �t�.67 y � !e'-�Y CrCP�1.of ! - '-� I T�, - � su wv � / � � �I �i �� t��o snwux[sr. �, 'ra PwanHc-�xrc uwc'- ., / �� a � I ------�---___- - _.�__ WS cels- i �' V �� il µ1 �� i¢_�-—a•i.a�.�r� �nl v3'i?f?il.a?' . W �e'-ix'crcr�9.xr� sr..e.ao... -s' r— ^ � � I i i��ro�i ys°a"`x a� �i 8 � � 4^ ew:.�oe � �� 1I ,I I I .'1' w ��.i�n�'� h' �0/2-T7F 1 (a, E:IOJ.S P � � i .t'-�r aro��.rn �-- -...... , . _ � �S � V w - t0 MOI.W�/ � �' . .. ...�I li�q'.lE.4 7Y.5 Ili�� 7� .X�� :�0 31.00' �^ rtW:��Dix.o a i�c uo�'1\ � I �� NOf'0372E ' � 3 � a'-u•crc'�i.drn- �� ' � � f. �� d q I � ""'� 1 / I ` , �-�� ' a�'�"�,�x � �a � v.,,1z.,�,�;�,b,.o�.' TR T� �r:•��.n . . :O !� 1 r.�n.o a.IN.L ui fQ! __... Y. ��N ^ .I�I R H�tb � __'_ �� I_" �2 �: 12 H4 w � s �� , � 5 5 I ,,,o . ��r�isn.casc uo: - Q � � 1 ' -;� � �' lOL10,LOLNIHO ROIIND .. .. 10� _ n Mw R1 �____--__------ . � -� . xo'._ W r.„�a•• „ ---------`------ °" �� ` .. _- c«..r� � , - -- - - -- -- - i ze �ar ' w �r� � , � I y "- „ roiw�zt n3.�� 1 i � lUl IY 9 1r -- ' 'NO PMNING-!IM Lu('YGx] '. U � ioi:a ` I - �n. ----- , ,� xo•�cass a unyn� �N ' i ` ,�, /�'e , a rwaruTr ro resi) a 2 1 i I � I 1,"N' 4�r �� '1 E�SE�[NI(lflN LOf 5 �. ��J� �� I !y w,•�V .,�., •_.------- • . .----- �I- __� ^" ' ' DRAINAGE DETENTION: ��y ��•' � ,~' � IFYEI Y DEIETION STANDARO �rs_� [p�TMC��Typ��) SUBSURFACE CONCRETE VAUL7 r. -hY�,)ra�1 �—� INSIOE WMENSIONS: �6.0'e f0.0' �� ,..,., . � .4 ,,'a.we.a • `�� ELEVA710NS: ..._ . ' ' • � , , , WebberShortPlat PIPE FLOW CALCULATOR(Courtesy of Barghausen Consultfng Engineers,Inc.) using the Rational Method 8 Manning Formula KING COUNTY DESIGN FOR 100 YEAR STORM JOf3 NAME: Webber Short Plal NOTF:ENTFR D[F�UI.1S AN�STORM UATA HEFORE E3EGINNING JOB#: DEFAULTS C= 0.9 ��= 0.012 REVISED: rl= 12 Tr.= 6.3 A=Contributing Area(Ac) ad=Design Flow(cfs) COEFFICIENTS FOR THE RATIONAL METHOD"Ir"-EQUATION C=Runoff Coefficient Q�Full Capacity Flow(cfs) STORM Ar E�r Tc=Time of Concentration(min) Vd=VeloGty at Design Flow(fps) 2YR 1.58 0.58 1=Intensity at Tc(in/hr) Vf=Velocity at Full Flow(fps) 10YR 2.44 O.G4 PRECIP= 3.9 d=Diameter of Pipe(in) s=Slope of pipe(°�) 25YR 2.6� O.GS Ar- 2.61 L=Length of Pipe(fl) n=Manning Roughness CoeffiCienl SOYR 2.75 0.65 Br- 0.83 D=Water Depth at Qd(in) Tt=Travel Time at Vd(min) 100YR 2.61 O.G3 FROM TO A s L d Tc n C SUM A A•C SUM A'C I Qd �f OdlQf Dld D W Vd Tt ==e==e xs=e== ==aeca ao==== _____ _=='==c=== ______ =e=_= ama�3a ==e=e sssaa�a�se�a=a saaa�a s�asa= a=az�e =eaa=e a=ev=a �Safia ases:■ :c=�ee 10 11 0.06 0.50 36 12 6.3 0.012 O.�J 0.06 0.05 0.05 3.19 0.17 2.73 0.06� 0.171 2.05 3.48 1.92 0.31 11 6 0.06 0.50 265 12 6.6 0.012 0.9 0.12 0.05 0.11 3.10 0.33 2.73 0.123 0.238 2.86 3.48 2.33 1.89 7 6 0.07 0.50 30 12 G.3 0.012 0.9 0.07 0.06 0.06 3.19 0.20 2.73 0.074 0.184 2.20 3.48 1.98 0.25 6 4 0.20 3.36 149 12 t3.5 0.012 O.G 0.39 0.12 0.29 2.64 0.77 7.07 0.108 0.223 2.68 9.01 5.8� 0.42 5 4 0.07 1.00 30 12 6.3 0.012 0.� 0.07 0.06 O.Ofi 3.19 0.20 3.86 0.052 0.156 1.87 4.92 2.57 0.19 4 2 0.34 9.58 78 12 8.9 0.012 0.6 0.8 0.20 0.55 2.57 1.41 11.94 0.118 0.231 2.77 15.22 9.58 0.14 3 2 0.57 0.62 65 12 G.3 0.012 0.6 0.57 0.34 0.34 3.19 1.09 3.04 0.369 0.421 5.05 3.87 3.48 0.19 j 2 vault 0.10 1.67 6 12 �3.1 0.012 O.G 1.47 0.06 0.95 2.53 2.40 4.99 0.481 0.490 5.88 6.35 6.03 0.02 vault 9 0.00 1.00 199 1'1 9.1 0.012 0 1.47 0.00 0.95 2.53 2.40 3.86 0.622 0.572 6.88 4.92 5.16 Page 1 v - �p w n.SI re.�� S"C- ' S1�� D►'GL�v1 � R - �-�i� P� � Ses�-��ne,w-�s : 1 . z� �- a" �� G c� 3, � 3� I, z . 7��_ �,� � � � � . `��% 3 �}'� — �Z'� C�P � I �. c�% 4 . 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'" .�` ` � J�,' ., �'.�, �,i�. / ,. �� P � , •,: � ��t"� p� 'y!�� • ,.,� ,a�� + S ti�.A ''I r�' �, ' . ; . :i �:., . i / / i�'. ., .� lr iu'-i.,: `,.'-�. � i i�i� ��. :� �.-� . �'ti « a.;v. � / �� I � 1 4�� . . � . -; '� :�� f S�'-�i:�`f'. � � �.� (.��, I .. �.�� 1 . . . . .��y�ii � `.' , rwl�,�� `J ��.'�'�ti,�. � � • ��` � (y I f• ;�. p 't�'T # ��, i� � 1 ' -� I .� / ;�' 4 . � .. / � � 1 �h�l. y� ��+�..� � � ' . � �. � (� �1 � ~ :�, , � % �� I �. .'� � " . 1 � � I J � - ,� � � . l.�' ` � � � , � 1 _� , � � ; 1 , _ �� I� I � � fl � � �` \ '�� , � � , , 1 ' � �' 1 ` I _ _ ' � 1 � \ \ � '� , � � � .. � �, � � ` � i � I . .. .�� . 1 � a�. --, t . VII. EROSION CONTROL SYSTEM The erosion control system was designed to eliminote any onsite runoff from entering the adjacent properfies or right-of-way. In order to accomplish this, an interceptor swale will be constructed south of the proposed new road. This swale will discharge into a sediment pond located near the southwest comer of the properfy. The permanent detention vault will eventually be constructed just norfh of the location of the sediment pond. The sediment pond will use the proposed off-site drainage discharge system as the outlet. Additionally, silt fencing will installed along the south and a porfion of the west property line which are the low properfy lines. There is an existing rockery along the south property line. The silt fence will be installed above the existing rockery. The proposed grading for this plat is well-defined and limited to the road and utility areos. The area disturbed will be minimized. The existing vegetation will be feff on the ground as much as possible during the site work. Disturbed areas will be covered with seed and mulch after disturbance. The erosion control plans also show the clearing limits and the locations for rock pad construction access points. .� - + . _ _ . . _ _ . _. _ . - - - - - --- — -- - - � � - ��o s�o�s c.oN�c-t�o� � , r- ��a� c c.v c-� o s s� � I'� -�� .� o o� c�cv i . = O, c`�-S v Q.�..._ s� ' . � - SF� = 2 � �o �,00�� (p S l J� o� � I) �. . D-2a . st-�m �t - � la !� 20�0 ��' = 7o SF r u �v' �. S �� r� �c� ' I l = r� i �c�= lr�' �j = ��o Si � �� C9. � a�� dD ,� - dS..� � 4,� +( 3 ,S' ��'+11�v�c��rn (� � �E 3�. �e. S S �� I e�.n ��n � w o� o ' l _ _Q� a- �� I u� �� I I � �- � �� I! 0� ��.; _ � v .s 1 0 � �3�a�� - � °-� �--- -�s = � r r�,c� = J(�� .S� = Q-1 � � �t$e.l'': - ,O� = � ��, �� 29�- hv�S --- --- ------------ --- o"-- 3-z.Z-- -— - -- ---- � -- -- -- ---- --- ------------ I�� -_ iI (II (f! �f� - ��) , I!I �!� (!{ �� I!f �!i � !',� - � ; �`I i�' j;i i ; i ,: - ;i �� :� I�I ra-� �.�o -e�Q t,�L• � �,� ' � �'I ��iQ L,� - �o'o � ' �. = �I _ ; f '{7-�1� � , = ro � I � � 1 c�' _ � �o Z'Z� -� �' ' � , 2 0$°1 � q ' _ . r`,.�' �-"Ya•'J'`�S _ I . w il r �� SbCI70N D.� ESC kff�SURES � '� — � � D.4S.2 SEDIMEIVT POT'D � • . n � : - Code: SP 5}�mbot: J Purpose � S�dimeat ponds remove sedisacat firom runoff originaung from distur�d arcas of the siu. Sedimcnt ponds ane rypicaIly designed to only rtmo��e sedi:nent as smaIl as rr�dium silt(0.02 mm� As a conscqncace,tbey usuaIty redua turbidiry only slightly. Conditions o! Use . � = A sedim�nt poad sball be usod R•bcre the cona�buring dninage arca is 3 acrrs or mo;e. � Design and instaftation Specifications l. Set Figure D.4.I,Figu.�t D.4J,and Figure D.4.K for details. , 2. If permaneat runoffco�tr�l`aciliDca�.-c pz^t of t5e projer�tbey should be us:d for s-.�ir�ent rezu»o� ", (see"Use of Pcnnaa:nt D:zinage FaczliDu'on�£e D•25). � Determining Pond Geometry ' ]. O�.zin tbe dischuge fro;n t�e hydraloeic c�]culz�ons of tht pc.�.k flow for tbe 2-��cu n:n�:f cvcnt �Q�. re��aycup-.�Y flon s�]be usad�f t�e projut s:ze, czpxtr,d �rnir.g a.�d d��on of icoascvcDon,or doa�as�zz�co��iDo�s W�^znt a higba Jc�•cl of protecDoa lf�o hv�.oloeic z.��s:s is;r�uired,c�e Rz�oral?�!c:bod may be usc,�(Soc�on 3.2.1 of tbe Surface ►t'c:cr Dcs'ga 1�cr,u:,). � 2. Dete.. � e;be rqi:ired st:.�zce�,-u u tb�tep of t�e riser p:pe v��the aua�o�: SA = 2 x Q�0.6�:6 or �USO squ��eet pu c,`s of ird7ow S� Sec�oa s�.4S.1 (p.D-:6)for no:r;:Jo.:..��en o�thc de.;�•�ion of L'�e surzce��u c�]c::?�ca. 3. T'�e b�sic geome�y of;be poDd can new be detc.�;tined usir.g L'�e;ollow•ing desi�-n cr:t:r:a: • Requi-e�sw-.`�e�.-u SA (�om Ste�2�e��e) at top of riser � • ?�iinini:r.�3.5`oot de�3 fro�to�of r'ser to bo<<o�of pond • Maximum 3:1 i�terioz side slopes �d r.�xir�um 2:1 extcrior slopcs. The i�:.:ior slop�s c�be i.�cmzsed to a rr.�xi.-n��ra ef 2:1 if fencing:s pro��ded at or above tha r�xin�ra u•zter s;:rfacc • O::e foet of fr�3o�d�n:�ecn Z':e:oa ef t.e riser�.�d Zhe crest ef the eme-ge�cy s;:1u��y • Flat bottom • ��inimu�cne:`ect c��spii]�.:a�• � • Lentth-to-widrh r�o be;ween 3:1 �d 6:1. Sizing of Discharge t►Rechanisms Prindpal Spill�ca�•:Deter.r:..-e L�,e requi:ed d:�-neter for the princ;p�l spillv��ay(riser�ipe). T?�e diz�-,e•wr sLz1 be tl-,e r.ti.-iimum r,ecess�ry to p2ss tbe pre-de�•eloped 10-year pezk flow(Q�o). Use Fi�:re 5.3.4.H (Sii'D?�1 Chap?er 5)to de;emine t};is di�-�eter(h =ene foot). l�'ore:A perrr.cr,er,t cor,7ol srrucr,�re rncy ce � used ir�stead of a terr.porery r��er. � . ;1 ;. -� S/11�'S E:csicn z�d ScC::,::.:t Co:�ol St�-,a,�'.-�s � D-:.8 i� �