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HomeMy WebLinkAbout95221 RLGrr uEo NOV 1 J 3 1995 QEVEC TY� ON 1NG CONCEPT ENGINEERING, INC. 455 Rainier Boulevard North,Suite 200 Issaquah, Washington 98027 (206)392-8055 Fax: (206)392-0108 LEVEL 1 DRAINAGE ANALYSIS for RON CARVER 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:\WPDOCS195221.DOC 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). 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 Lake 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). C:\WPDOCS\95227.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. CAWPD0CS195221.D0C Page 2 SUMMARY 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. Sincerely, CONCEPT ENGINEERING, INC. p•�- CA/V q' 1W36 O W ,eF, F"STEa�' � OMAL Env wum 6-25-S— 1 Carl Cangie, P.E. C:\WPDOCS\95221.DOC Page 3 ------------------------ ROJEC"r NO. 95221 CONCEPT ENGINEERING, INC. RAINIER HOUIEVARD NORTH, SUITE 200 DATE 9=25=95 - 455 ISSAQUAH, WASHINGTON 9802.7 _SUBJECT Level 1 Drainage Analysis for Ron Carver (206) 392-13055 FAX (206) 392-0108 SHEET / ` NE so I y Q SE _Z6_ ST 1 lui N SE 76TH a N� PLLIN < N w S l I. 1 1j �N ,n 1 N�43RD�...i SE 80TH 79iii ST LLj �, 11200 f � SE 3RD H STr _. N 40TH ST ._40 rI 1300 vNell rH ST w a N 3�Tl1 51 o LN SE,86TH ST 5T. �Q SE_87TH ST 36TH 3 N ^ 36TH S 35TH Sr 100 H 34TH a' ST "` `rtr�O� 'ti�� �W S 8 x Wz 33RD PL � - a N 33RD ST ' NE 33RD ST SI l0 N 31ST ST 2 3 TH Q T sr f T 2 MAY N 29TH ST 1300 e CREEK pARK m N 28TH PL Mtn NE 28TH __S?_ -NE _ ST v FIGURE 1.0 (Vicinity Map) NTS C:\WPDOCS\95221.DOC NW 1/41 SEC 321 TWN 24N, RNG 5E .TR aUS 10' /1PPLE 'FIR GARAGE �Fp 14• ONE�Y++PEEAR �+� EXISTING j ( 1 10' PEAR �r s� `� _4GQ� HOUSE �„J �.,,J [4�A� L4nGV �Dlii. � » APPLE 10' WALNUT 1Y SPRING APPLE HOUSE 1 =50 18'AP LE 8. D WN BY: M I M CONCEPT ENGINEERING, INC. EXISTING TOPOGRAPHY DSG BY: 1456 Reinter Boulevard North, Suite 200 Iswush. Weshlnpt., 98027 FIGURE 2.0 DATE: 9-25-95 (2061392-8055 JOB NO.: 95221 PROJECT NO. 95221 CONCEPT ENGINEERING, INC. _ 455 RAINIER BOULFVARn NORM, SUIIF 200 DATE 9-25-95 ISSAWAII, WASHINGTON 98027 (206) 392-8055 FAX (206) 392--0108 SUBJECT Level 1 Drainage Analysis for Ron Carver --"- -- " -- _ SHEET / • . . ■ \ ■ Agc a . a Kennydale ' ' •• .■ agc !a •■ . .. • !nc■ AkF • ,■ loss . • aas ' r ■■ it was ■ a a monsoonal a • i■ ■a '■ • NO ■■ ■ ■■a sass `• • • • •, ■■ • t■ • as • , • ' • • ■ ` • • ' ■• a■ a .. .. . ; .N i . ■a■ ■ ■ AkF la■ . •. • .. • • ■ \ ' a �-- — — ---- i : �, D •. • B M• so: • Z • / • a , 1 • •• ' • • INS FIGURE 3.0 (SCS Soils Map) 1" = 1000' C:\WPDOCS\95221.DOC PROJECT NO. 95221_ CONCEPT ENGINEERING, IN_C. DATE .9'25-95 455 RAINIER ROULEVARO NORM, SUNE 7( _ ISSAQUAH, WASHINCION 98077 _ (206) 392-©O55 rAX (206) 392-Oros SUBJECT Level 1 Drainage Analysis for Ron Carver SHEET / D3 3C4-3 3 4- �� 4-1 3, 4- 3,C -s N t 3 TH 3X 7 31C 1 -6 3 4-5 3,C4-4 3,p4 C5- !/ I FIGURE 4.0 1" =200' C:AANPDOCSV95221.DOC 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1