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Home My WebLink AboutSWP272317 t ' RECFIVFD NnV 1 3 1995 t DEVELUrNo._N f PLANNING CITY OF RENTON 1 5wP - 27 ^ ?-5\1 CONCEPT ENGINEERING, INC. 455 Rainier Boulevard North, Suite 200 Issaquah, Washington 98027 t (206)392-8055 Fax: (206)392-0108 LEVEL 1 DRAINAGE ANALYSIS for RON CARVER , I ' Site Address: 3818 Lake Washington Blvd. N. Renton, Washington ' Prepared by: Maung Myat ' Reviewed by: Carl Cangie, P.E. ' September 25, 1995 Job No. 95221 C:\WPD0CS\95221.D0C ' CIVIL ENGINEERING/SURVEYING/LAND USE PLANNING 95221 Carver ' INTRODUCTION ' This analysis has been prepared for a 0.75 acre site located at 3818 Lake Washington Blvd. N, Renton in King County (see figure 1). The reason for this analysis is for a potential four lots short plat. The 1990 King County Surface ' Water Design Manual requires that a visual analysis be performed to determine the drainage elements both on-site and off-site. The site was visited on September 22, 1995 and the weather was warm and sunny. ' The 0.75 acre site is the western portion of Tract 86 of C.D. Hillman's Lake Washington Garden of Eden addition to Seattle No.2, situated in the northwest ' quarter of the northwest quarter of Section 32, Township 24 North, Range 5 East, Willamette Meridian, in King County, Washington. ' The site contains an existing house located at the western edge of the parcel, driveway, garage and two sheds (see figure 2). The main form of vegetation on site is grass with few decidious trees. Soils on site have been mapped by the SCS as Alderwood Series (see figure 3 . g } Topographically, the site slopes from the east property line towards Lake Washington Blvd. N. to the west. SENSITIVE AREAS ' The site is located in the East La ke Washington sub-basin of the Cedar River basin. The site was checked for sensitive areas using the King County Sensitive Areas ' map Folio, December, 1990. No sensitive areas were found on or adjacent to the site. ' UPSTREAM TRIBUTARY AREA ' Approximately 2.29 acre of off-site area contributes runoff onto the site. This area is fully developed with single-family residences. The runoff sheet flows across the east and south property lines towards the spring on site (see figure 4). ' CAMDOM95221.DOC Page 1 ' 95221 Carver ' ON-SITE DRAINAGE FEATURES ' Off-site runoff flows towards the spring that exists on site. A 12" ADS storm pipe intercepts the off-site runoff as well as the flows from the spring and conveys the runoff towards the roadside ditch on the east side of Lake Washington Blvd N. ' This pipe flows through the southwest corner of the adjacent property to the north before it daylights in the roadside ditch. A grass-lined swale also exist on-site and collects on-site runoff as well as some of the off-site runoff and conveys it to the same ditch mentioned above. Runoff from the southwest corner of the site discharges directly into the road side ditch (see figure 2). DOWNSTREAM ANALYSIS There are two drainage basins that this property drains to. The driveway of the property serves as this basin divide. Approximately 75% of the property drains north and the rest drains to the south (see figure 4). North Basin: The roadside ditch approximately 2-feet in width and 1-foot deep intercepts on-site runoff and conveys it north towards a storm manhole. From the manhole, storm runoff flows west in a 18" culvert which eventually drains into ' Lake Washington. ' South Basin: The same roadside ditch mentioned above intercepts runoff from approximately 25 % of the property and flows south. Runoff flows through three structures, two catch basins located at the intersection of Lake Washington Blvd. N ' and N 38th Street and one manhole located approximately 100-feet south of the above street intersection mentioned above. From the storm manhole, a 24" culvert conveys this runoff west towards the lake. ' The roadside ditches were full of debris from a lack of maintenance by the City. Apart from this there appears to be no downstream problem. ' C:\WPDOCS\95221.DOC Page 2 1 1 SUMMARY 1 In our opinion the downstream system for this site has adequate capacity. We have tried to be as clear and concise as possible in this analysis. Should any questions arise, please feel free to contact Mr.Maung Myat or myself at our office. 1 Sincerely, 1 CONCEPT ENGINEERING, INC. CA 0 " 1 w fQIsTEaE 1 'ONAIL Env maims 6-25- 1 u 1 Carl Cangie, P.E. 1 1 1 1 1 1 1 1 C:\WPDOCS\95221.DOC Page 3 1 PROJECT NO. _ 95221 CONCEPT ENGINEERING, INC_. 455 RAINIER ROULEVARO NORM. SUITE 200 ' DATE 9'25'95 _ ISSAQUAH, WASHINcrorl 98027 _ (206) 392-8055 VAX (206) 392-0108 SUBJECT Level 1 Drainage Analysis for Ron Carver -- SHEET / I NE 50 r > T uj .r... ST 1 1W Q N +^ SE 76THa 4 r ' s � I t I� � �>i SE , < N 43RD SE• I 80TH 19TN ST ( � .pL.2 .� _ i, SE 3RD SE,..,,,.,.,......... N ST N 40TH ST 40 ._ 1300 SE z.w _1 _. ... _ ._ z N .O � ' 8TH ST W N 37TH 51 o �- SE 86TH ST 1 ` ST LQ r, SE 87TH ST, ' 36TH N 36TH S 35TH ST a 1 00 V) 16 34TN ST V'i sF '�� W+ S 8 �► z Q 33Rb PL — _ E c N 33RD ST NE 33RD ST & N 31St ':ST 3' TH~ Q S a. T_ 2 MAY N9TH ST 1300 CD e CREEK 4 m N 28TH PL $ P 9TH N.. 28TklV`" - r NE 28TH ST — v .. ST- NE �7Tw cr �. ' FIGURE 1 .0 (Vicinity Map) NTS ' C:\WPDOCS\95221.DOC NW 1/4, SEC 321 TWN 24N, RNG 5E 4 TREE / ass r V / ' 'FIR / GARAGE eetArAA/// �fo 14' ONEYY PPEAR EXISTING Q HOUSE APPLE 12' APPLE IV7?� SPRING 1"=50' • 10' WALNUT HOUSE 18' AP L£ 8' APP D WN BY: M I M CONCEPT ENGINEERING, INC. EXISTING TOPOGRAPHY DSG BY: 455 Ralnler Boulevard North, Suite 200 Issaquah. Washington 98027 FIGURE 2.0 DATE: 9-25-95 (2061392-8055 JOB NO.: 95221 1( PROJEC i NO. 95221 CONCEPT ENGINEERING, INC. _. SATE -- 9-25-95 455 RAINIER AOWEVARD NORTH. SUIIE 200 ISSA(�UAlI, WA$IIINC;ION 48027 _ (206) 392-13055 TAX (206) 392-010p SUBJECT Level 1 Drainage Analysis for Ron Carver — _ --- -- SHEET / ii .■ • • d i • a ■ • . . , Kennydale •••• ' • -- i■ • . .. !n,. j f AkF 1 gal ' Poi n • . . ;•,•R ■ •i ■ ■■ • •■ • • • • ,• ,� AkF an B r gC Age r '• • BM•' 30: z • ' � • ' _ i ■ \\ • •.I • • I ' FIGURE 3.0 (SCS Soils Map) 1" = 1000' ' C:IWPDOCS195221.DOC PROJECT NO 95221 CONCEPT ENGINEERING, DATE 9-25-95 m 455 RAINIER BOULEVARD NORIM, 700 m ISSAQUAH, WAStIINGION 9807.7 (206) 392-6o55 rAX (206) 392-0108 Level I Drainage Analysis for Ron Carver SUBJECT SHEET ID3- > ' �'� N F- aC4-3 3 4- 3,D4-7 c) 3,C -8 3 TH 3,C 7 3,C4-5 3,C4=4 3D4 C5 ,/ 1 - ' -11 FIGURE 4.0 1 200' C:\WPDOCS\95221.DOC 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1