Dec. 29, 2020: I-90 Sunset Creek - Fish Passage. To comply with United States, et al. vs. Washington, et al. No. C70-9213 Subproceeding No. 01-1 dated March 29, 2013 (a federal permanent injunction requiring the State of Washington to correct fish barriers in Water Resource Inventory Areas [WRIAs] 1-23), WSDOT is proposing a project to provide fish passage at the I-90 crossing of Sunset Creek at Mile Post 10.52. This existing structure on I-90 has been identified as a fish barrier by WDFW and WSDOT Environmental (Site ID 996251) due to water surface drop at the culvert outlet. The proposed project will replace both the existing 36-inch and 48-inch culverts with a bridge providing a minimum hydraulic opening of 53 feet to improve fish passage while providing a safe roadway for the traveling public. This proposed bridge is designed to meet the requirements of the federal injunction utilizing the bridge design criteria. The length of the Sunset Creek crossing is approximately 565 feet, and the proposed channel grading extents are 864 feet long. The tie-in points were chosen in the field with stakeholder input and were purposely extended to encompass and remediate armored riprap sections of the existing channel. The Sunset Creek proposed channel geometry has a bottom width of 9 feet with a 5 percent slope to the centerline to create a thalweg that is 3 inches deep. The banks slope at 2H:1V for 1. Habitat features, including large wood material be provided for habitat enhancement.
May 10, 2021: Completed.
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