May 29, 2020: COBU Factoria Conveyance Improvements. The project proposes to replace an existing 3.3- by 5.3-foot storm drain pipe running along the east side of Factoria Boulevard SE with a larger capacity stormwater conveyance pipe that flows into the inlet channel of Richards Creek adjacent to Factoria Village commercial area just south of I-90. A new outfall structure consisting of two 60-inch pipes with fish exclusion and two 24-inch overflow pipes two feet above OHWM is proposed to replace the existing pipe. The stormwater conveyance improvements include approximately 413 feet of 9-foot-wide by 4-foot-high concrete box conveyance; 229 feet of 5-foot wide by 2-foot-high box storm drain; two new laterals with five new 18-inch pipes across Factoria Boulevard at the Formula-1 Fast Lube and two new 18-inch pipes crossing at the 7-Eleven store. Fifteen new inlets and improvements to eight existing inlets will be located along Factoria Boulevard SE. A City water and sanitary sewer line, along with a Puget Sound Energy (PSE) gas line may need to be relocated because of conflicts with the proposed improvements in the project area. Mitigation has been developed for the permanent impacts to Richards Creek below OHWM and temporary construction impacts to complete the project. Enhancement of the Richards Creek channel and riparian buffer will be completed as mitigation for the projects impacts. The project is expected to begin construction in 2021 and continue in phases with completion in Fall 2022.
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