1808 MERRILL CREEK PKY 2016-01-01 MF Import

WETLAND PONDS Rele�se Rntes , The wedand pond is a series of two main cells that combined, provide detention and water quality measures. The wetland pond has been sized per the volume and release rate requirements provided by the City of Everett. The allowable release rate was determined by adjusting the release rate received from the City of Everett's SWMM model. The SWMM model was based on a total area of 5.23 acres. Using the tributary areas, an adjusted release rate was determined for the revised area of 6.65 acres: 0.15 cfs x cfs X = 0.19 cfs [Adjusted allowable release rate] �5.23 Ac� �6.65 Ac� The two main cells are separated Uy a log weic There is also a log weir located at the outlet of the lower (north) cell. Botli log �veirs have notches which have been sized.to ensure the discharge from the facility does not exceed the allo�vable release rate during the design stonn. For larger storni events, the tops of the logs act as weirs to discharge the larger flows. Pond Inilow (Pre-Develoned Conditions) Please refer to the Devcloped Conditions Map located in the Appendix. There is approximately 6.65 acres of area tributary to the ��etland ponds. The time of concentration and curve numbers are as justified in the letter to the City of Everett, included within the Appendix. The curve numbers are based on the Curve Number Table located in die Appendix. The drainage basin characteristics used ro generate th� inflow hydrographs are listed below: TOTAL AREA: 6.G5 Acres BASL-FLOWS: 0.00 cfs RAINFALL TYPE: Type IA TIME INTERVAL: 10.00 min TIME OF CONC: 45.97 min ABSTRACT. COEFF: 0.20 PLRVIOUS AREA IMPERVIOUS AREA ARGA: 6.65 Acres ARGA: 0.00 Acres CN: 81.00 CN: 98.00 STORM DRAINAGE REPORT FOR INTItA�\'EST-SEAWAY - PAGE 10