6414 HARDESON RD 2018-01-02 MF Import

nRAINAGE CONCEPT The ProjecdViking Site is located just upstream of the City uf EveretYs regional detention facility for the 550-acro regional basin. Therefore, only a water qualiry facility is roquired. A single wet pond/detention pond has been designed te provide water quality for the Project (i.e., all 3 lots) and has been situated in a drainage tract (Tract C) south of the Viking Site. The wet pond/detention pond has bcen designed to the City of Everett's standards for a two-celled wet pond. Although the Project is only required to provide wata qudity enhancement, the pond was sized to provide detention to minimiu the impact on the regional detention facility and in order to meke more deten6on nvailable for other sites within the rogional basin. To detertnine the live storage volume, the pond was sized to maximize the area allotted for the stortn water faciliry inside of Tract C. The SBUH methodology with a Type lA rainfall distribution was used to create the 2- year, 10-year, 25-year, and 100-year hydrographs using the Water Works computer hydrograpfi modeling program. The drainage basin characteristics and summary of the results have been provided in the Drainage Calculations section oP this report and are supplemented by the additional information in t'.;e Appendix. STORM DRAINAGE REPORT FOR VIKING FREIGHT/tviERRII,L CREEK PAGE 2