10025 9TH AVE W 2016-01-01 MF Import

DVE Coawltents, Inc. This development proposes the construction of 7 mulri family units, or a total of 32 ccndominiums. It is located at the southeast comer of the intersection of 100'� St SW and 9'� Ave W. In the undeveloped condition, the site is overgrown with 2°� growth forest nnd some brush. There is one eacistiag home on the site. The site's terrain is genUe, draining to the northwest. Per the Soil Survey of Snohomish county this azeu is classified as Alderwood Urban Land Complex. Hydrologic So�_s group C. llESIGN OVERVIEW Since there is only one basin, only one conveyance/ detention / water quality facility will be used to drain the site. This facility will be made up of two elements, an under ground detenrion and settling pond and an exposed wettand cell. Both will be concrete. DESIGN STANDARDS Per the City of Everett Stormwater management guide the basis for design is as follows; A. All conveyance systems will be designed using the rational method with capacity for the 25 yr. storm event. See City of Everett Stormwater Manual section 1-5 B. To prevent downstream erosion all storm water collected will be infiltrated or detained and released at a controile3 rate to match rates cansistent with the undeveloped condirion. C. Settlement and water quaL'ty condirions must be built into the system. 3ee City of Everett Stormwater Manual sections 3-3 Unless otherwise note�, all numbered references are to the Ciri of Everett Stormwater Management Manual CONVEYANCE PIPES Per City Stds., all conveyance pip in ihe R/W is a m+nimum 12" in diameter. The smallest slope for any run in the system is 0.5% which has a capacity of 2.73 cfs. This capacity is sufficient to cany the runoff voliune any single run in the system should have to convey: Q=CiA C=0.50 I = 2.29 A= 1.93 � 2.20 cfs for the total basin Drainege Report, Bush Gardens, Job l� 98022 C:\My Documents�DRN. REPT198051.docLast printed 10/02i98 9:32 AM �