Laserfiche WebLink
I <br /> D. STORMWATER FLOW CONTROL <br /> The is to construct a three-story residential building with an underground <br /> proposal <br /> parking garage. The total proposed impervious surfaces will be 9,875 SF. The access to the <br /> parking garage will be from the alley in between Rockefeller Ave and Oakes Ave. <br /> The project site is legally served by a combined storm and sanitary sewer system, in <br /> P J g Y <br /> ' which case the stormwater standards shall be as determined by Public Works Department <br /> policy. The existing basin was modeled as existing conditions per section 6-10 of the City <br /> Design and Construction Standards and Specifications. Flow control requirements will be <br /> met by a 19LF 4-foot diameter detention pipe on the south side of the building. <br /> DETENTION ANALYSIS <br /> Total Site Area =0.30 Acres <br /> ' From the NRCS of Snohomish County, the site contains Alderwood Soils that has a <br /> hydrologic classification of"C". <br /> Existing Conditions: <br /> ' Existing Basin Area = 0.30 Acres <br /> Impervious area: <br /> t Existing Roof Existing sidewalk =0.07 Acres (3,038 SF) <br /> =0.04 Acres (1,750 SF) <br /> Total Impervious =0.11 Acres (4,788 SF) <br /> Pervious area= 0.30 Acres - 0.11 Acres=0.19 Acres <br /> The pervious area was modeled as existing condition (Lawn). <br /> ' Refer to the Existing Basin Map & WWHM Report attached later in this section for <br /> more details. <br /> 1 <br /> ' Insight Engineering Co. -Stormwater Site Plan 12/30/20 <br /> - <br />