10430 ROSEWOOD AVE 2018-01-02 MF Import

HYDRAULIC PROJECT APPROVAL State of Washington Doa,buntaf RCW 77.55.100 - appeal pursuant to Chapter 34.05 RCW Department of Fish and Wildlife FISHmd Region 4 Office 16018 Mill Creek Boulevard Mill Creek, Washington 98012 DATE OF ISSUE: May 24 2002 LOG ;1VIRER: 00-F1439-02 7. The stormwater detention facility shall consist of a detention vaults and biofiltration swales which are sized according to calculations and requirements described in " Drainage. Report for Rosewood Park" dated November 30, 2001 and revised February 20, 2002, and submitted to the Washington Department of Fish and Wildlife in conjunction with the Hydraulic Project Application. 8. The stormwater detention facility shall be constructed with restrictive orifices set at'/Z of the pre -developed two- year, 24-hour, design storm and set at the pre -developed 10-year and 100-year predeveloped, design storms. 9. Wastewater from the project activities and de -watering shall be routed to an upland area for removal of fine sediments and other contaminants. Only clean, unpolluted water shall leave the site. 10. The detention facilities shall be maintained as necessary to assure they function to design specifications. 11. Extreme care shall be taken to ensure that no petroleum products, hydraulic fluid, fresh cement, sediments sediment - laden water, chemicals, or any other toxic or deleterious materials are allowed to enter or leach into the stream. 14. All bare earth shall be protected from erosion and appropriately revegetated prior to final inspection or completion of the project. 15. The biofiltration swales shall be vegetated with water tolerant plants and grasses. Culvert Installation 16. The culvert shall be placed on a <1 % gradient with the bottom of the culvert placed below the level of the streambed a minimum of 20 percent of the culvert diameter for a round culvert, and 20 percent of the culvert's rise for an elliptical culvert. The 20 percent placement below the streambed shall be measured at the culvert outlet. 17. The culvert width at the streambed shall be equal to or greater than the average width of the streambed. 18. The culvert shall be installed to maintain structural integrity to the 100-year peak flow with consideration of the debris likely to be encountered. 19. Fill associated with the culvert installation shall be protected from erosion to the 100-year peak flow. 20. The culvert shall be installed and maintained to avoid inlet scouring and to prevent erosion of stream banks downstream of the project. 21. The culvert shall be installed in the dry or in isolation from the stream flow by the installation of a bypass flume or culvert, or by pumping the stream flow around the work area. 22. The culvert shall not exceed 42 feet in total length. 23. Disturbance of the streambed and banks shall be limited to that necessary to place the culvert and any required channel modification associated with it. Affected streambed and bank areas outside the culvert and associated fill shall be restored to preproject configuration following installation of the culvert. Within one year of project completion, the banks shall be revegetated with native or other approved woody species. Vegetative cuttings shall Page 2 of