9620 19TH AVE SE 2018-01-02 MF Import

erosion untrol hydroseeding of the swale area, which is not the specified seed mix. The attached detail showing the cross-section of the biofiltration/grass swale should be included on the storm drainage plans and the landscape plans. The detail will help clarify swale construction. Open ends of pipes 12" or greater should be equipped with trash racks. Miscellaneous• The discharge location of roof drains should be shown to ensure that roof runoff is routed tc the detention system. The top and toe elevations of all rockeries adjacent to or associated with stormwater facilities must be given. The City is concerned about designing situations with water either flowing or standing near the base of rockeries and retaining walls. A sheet is attached that gives specifications for situations where rockeries and/or retaining walls are adjacent to surface ponds or vegetated swales. The appropriate detail should be given on the plans. It is important to leave enough horizontal room for construction of the rockeries. City of Everett inspectors indicate that 4 feet is typically necessary. The plans need to show this distance. The plans show the biofiltration swale discharging to an existing drainage course that is not adequate to convey the flow from this site. The site drainage must be conveyed to the wetland system that exists to the west of this site. A completely tightlined system may be used or a ditch may be constructed with a catch basin and pipe outlet providing the final drop to the wetland. If the system must cross private property, an easement will be required. Appropriate energy dissipation will be required at the pine outlet to prevent erosion. The outlet to the wetland mus.. be constructed between June 15 and September.• 15, during dry weather only.