1123 RAINIER AVE 2018-01-01 MF Import

STORM DRqINAGE ltGPORT THE MEADOWS U Overview: A 51 unit, 4-story apartment complea wir1� associated pazking is proposeJ for a 1.24 acre parcel located on Rainier Avenue between Poplar and 12�' Street and approximately 1 mile south of the .4merican Legion Memorial Park & Golf Course. More generally tl�e site is located with the SE �/. of the NW Y. of Section 17, 'fownship 27N, and Range SE of the Willamette Meridian. Existine Conditions The site is undeveloped with urban unmaintained grass cover. It is located within the 36'" Street Combined Drainage Basin. A portion of an existing building straddles the south propeny line at the SE corner of the site. The site slopes 1-2 % downward frum east t� west. Current drainage from the site flows westward to Rainier Avenue where it enters the combine sewedstorm drain system. Dev I e i ndi i ns Construction of the apartment complex and the associated parking will create 0.85 acres of impervious azea. Runofffrom these impervious surfaces will be directed to a 48" CMP detention pipe. In accordance with the City of Everett Standards, the detention pipe is desibned to detain the 10 year storm and release at the pre-developed ]0 yeaz rate. The discharge flows out of the pipe will be controlled by a flow restructure / oil pollution control device (FROP). The chart below list relevant discharge rates. ___ _ _._._._ ___ DESIGN PRE-DEV Qp STORI�t 10-YEAIt, 24 Hr. . � ( DEV. Qp DEV. Qp IN OUT .46 .16 Flow exiting the detention system will be routed to a SSMH within the Rainier Ave. ROW and continue through the public Sanitary Sewer System.