EAST LAKE SAMMAMISH PARKWAY DRAINAGE IMPROVEMENTS
The objectives for this project include: - Construct two 12 foot wide x 8 foot tall box culverts, one 25 feet long under the East Lake Sammamish Trail and the other 95 feet long under SE 51st Street west of the intersection with East Lake Sammamish Parkway to improve conveyance capacity through the corridor and reduce flooding impacts. The culverts will need to be fish passible because the storm drainage system connects to Park Hill Creek, a fish bearing stream. - Remove invasive vegetation within 1,700 feet of ditch, and design a channel planted with native plants to provide fish habitat, prevent invasive vegetation regrowth, and improve channel efficiency. - Upsize 8 catch basins from type 1 structures to type 2 structures along East Lake Sammamish Parkway, between SE 51st Street and SE 56th Street, and upsize corresponding stormwater conveyance pipes that connect to the conveyance ditch on the west side of the roadway. - Install 5 sediment collection zones downstream of select catch basins scheduled to be replaced, to minimize maintenance impacts within an active fish bearing stream and wetland system and create zones where reed canary grass and other invasive species will find it harder to re-establish. - Plant native trees and shrubs including willow and salmon berry within the 1,700 foot linear ditch system and surrounding wetlands.
