901 E MARINE VIEW DR 2016-01-01 MF Import

Walnut Ridge Storm Drainage Calculations Walnut Ridge is a proposed development of a 139 acre lot at 901 E. Marine View Drive in Everett. The existing site slopes at 14%to the northeast through dense blackberries. The existing storm drainage travels to relatively flat railroad trac!:s to the northeast and apparently infiltrates. The area does not have adequate downstream drainage so it is proposed to direct stormwater into a detention system and ultimately into the combined storm/sanitary sewer. The site is within tlie 36th Street Drainage Basin. The detention system is designed to match the ten-year existing with the ten-year developed storm. Following the City ofEverett's Draina��Calculation Form, total storage required is 1934.3 cf. A 121 LF of 4.5 foot detention pipe with 2.23-inch diameter orifice will satisfy the storage and release-rate criteria. The actual design will use 125 LF of4.5 foot detention pipe with a restrictor diameter of 2.25-inches.