HomeMy WebLinkAboutRS_Drainage Assessment_Lot 14_190402_v3
425.455.2900
14725 Southeast 36th Street, Suite 200, Bellevue WA 98006 quadranthomes.com
1/29/19
City of Renton
Community Development Services
1055 S Grady Way
Renton, Washington 98057
RE: Written Drainage Assessment
Lakeview Crest Lot 14
3921 Park Ave N
Lakeview, Lot 14 is a new single family residential project. This lot is 7586 square feet and is currently vacant. The
proposed improvements will include the addition of a new single-family residence. The area of disturbance will
not exceed the lot lines and will be equal to the house footprint, driveway, patio and walkway construction.
There are no wetlands or any steep slope hazard areas on this lot.
The lot is less than 22,000 square feet, so it is subject to the Small Lot BMP Requirements in Appendix C of the
2009 Renton Surface Water Design Manual. The drainage requirement for this lot will be met by using C.2.3.4
Drywells for limited infiltration to mitigate an impervious area equal to at least 10% of the site/lot for site/lot sizes
up to 11,000 square feet. The soil type is sandy loam and therefore the required volume is 380 cubic feet per
every 1,000 square feet, based on the stormwater manual C.2.3.4. Lot 14 is 7586 SF with the drywell design to
mitigate 758.6 SF for stormwater runoff. The drywell on lot 14 will be 8’ diameter and 5.75’ in depth, holding a
volume of 289 cubic feet.
There is also a 10’ section of perforated pipe connection to the storm line as shown on the BMP site plan.
Perforated pipe connections are intended to convey concentrated runoff from impervious surfaces (usually roof
runoff) directly to a local drainage system while providing some infiltration of that runoff in the process per C.2.11.
EROSION AND SEDIMENT CONTROL MEASURES:
In order to prevent erosion and trap sediments within the project site, the following BMP’s will be used
approximately as shown in the ESC details on the CSWPP plan:
· Clearing limits will be marked by fencing or other means on the ground.
· The driveway will be constructed and graveled immediately. A rocked construction entrance will
be placed at the end of the driveway. Dispersion trenches will be placed according to flow
control requirements.
· Runoff will not be allowed to concentrate, and no water will be allowed to point discharge onto
the slopes. Silt fencing will be placed along slope contours at the down slope limit of clearing.
· Mulch will be spread over all cleared areas of the site when they are not being worked.
Sincerely,
Tatyana Sirotinsky
Assistant Product Development Manager
425-646-8309
tatyana.sirotinsky @quadranthomes.com
PR16000315
B18006362-V3REVISION
Received: 04/15/2019 / lwalker
BUILDING DIVISION
PR16000315
B18006362-V3REVISION
Received: 04/15/2019 / lwalker
BUILDING DIVISION
PR16000315
B18006362-V3REVISION
Received: 04/15/2019 / lwalker
BUILDING DIVISION
PLAN VIEW OF PARCEL
TO STORM DRAINSYSTEMRIGHT-
OF-WAYGENERAL
NOTES:1.INFILTRATION TRENCHES LIMITED TO ROOF RUNOFF FROM SINGLE-FAMILY OR DUPLEX HOMES OR TO
CONTROL BASEMENT FLOODING. CONSULT WA DEPARTMENT OF ECOLOGY REGULATIONS FOR UNDERGROUND
INJECTION CONTROL PROGRAM (UIC) FOR OTHER TYPES OF RUNOFF
MANAGEMENT.2.IMPERVIOUS AREAS LARGER THAN 10,000 SF AND NON-NATIVE PERVIOUS AREAS LARGER THAN 35,000 SF MAY
REQUIRE LARGER PIPE AND SHOULD BE DESIGNED BY A CIVIL
ENGINEER.3.THE PERFORATED PIPE MAY NOT BE PLACED IN A CRITICAL AREA BUFFER OR ON SLOPES STEEPER THAN
25%.4.SEE CONSTRUCTION PLANS FOR SPECIFIC PROJECT
REQUIREMENTS.24"
MIN.18"
MIN.MIN. 1' ABOVE SEASONAL
HIGH GROUNDWATER
TABLE 6"
MIN.1 1/2" - 3/4"
WASHED DRAIN
ROCK NON-WOVEN GEOTEXTILE FOR
SEPARATION ON TOP AND SIDES OF TRENCH PER
WSDOT SPECIFICATIONS SECTION 9-33.2(1) TABLE
3 COMPACTED TOPSOIL OR OTHER CLEAN
FILL 6" MIN.
PVC PERFORATED
PIPE PER ASTM
D1785 10' MIN. LEVEL TRENCH
WITH PERFORATED PIPE, SEE NOTE
1 DOWNSPOUT WITH
CLEANOUT FILTER, SEE
DETAIL ASECTION
A
NOTES:1.TRENCH LENGTH TO BE 10 FEET IN LENGTH FOR EVERY 5,000 SF OF CONTRIBUTING IMPERVIOUS SURFACE, OR 35,000
SF OF NON-NATIVE PERVIOUS SURFACE, OR PORTION
THEREOF.
5'
MIN.
5'
MIN.TO STORM DRAIN
SYSTEM
5'
MIN.
5'
MIN.
A DOWNSPOUT WITH CLEANOUT FILTER, SEE
DETAIL 10' MIN. LEVEL TRENCH
WITH PERFORATED PIPE, SEE NOTE
1 CONFIGURATION ON FLAT
GROUND CONFIGURATION ON SLOPING
GROUND UNDISTURBED NATIVE
SOIL CLEANOUT PER STD. PLAN 226.
00 CLEANOUT
PER STD. PLAN 226.
00 FILTER
SCREEN 2'-5'
TO
GROUND
SOLIDS/
LEAVES TYPICAL
DOWNSPOUT FILTER
DETAIL FOOTING DRAIN
BYPASS CLEANOUT
PER STD. PLAN 226.
00 PERFORATED STUB-
OUT
CONNECTION PUBLIC
WORKS
DEPARTMENT
APPROVED:DATEGregg
Zimmerman Public Works
Administrator UNLESS OTHERWISE NOTED, DRAWING IS NOT TO SCALE (
NTS)STD. PLAN - 263.
40 DocuSign Envelope ID: 6EECF5B6-602A-4E4A-B436-
A317AA638878 9/28/2018 | 9:45 AM
PR16000315
B18006362-V3REVISION
Received: 04/15/2019 / lwalker
BUILDING DIVISION
PR16000315B18006362-V3REVISION Received: 04/15/2019 / lwalkerBUILDING DIVISION
PR16000315B18006362-V3REVISION Received: 04/15/2019 / lwalkerBUILDING DIVISION