The Chelan County Flood Control Zone District in partnership with the Public Works Department, invites consulting firms with expertise in providing professional services in the areas of structural/civil engineering design, geotechnical, hydraulic, environmental documentation, appraisal services, and construction management to submit their qualifications for developing the Twenty-Five Mile Creek Culvert Replacement Project, Phase 1. This project proposes to replace a dual box culvert with a new bridge to allow post-fire flood flow to pass under South Lakeshore Road in Chelan, Wash. Phase 1, the design phase, is estimated to start in February 2025 and be complete by May 2026. The project site is about 20 miles northwest of Chelan, Wash., where South Lakeshore Road crosses Twenty-Five Mile Creek. This roadway is the only north-south corridor for residents and emergency responders along the west side of Lake Chelan, one of the most popular tourist destinations in the state. South Lakeshore Road is a 35-foot-wide, two-lane road that has an average daily traffic count of more than 200 vehicles. The creek passes under the road through a double-barrel concrete box culvert that is 50 feet long and consists of two 8-foot-wide by 6-foot-high barrels. Existing utilities, including power and phone, are overhead. To reduce damage and traffic delays from post-wildfire debris flows created by the 2021 Twenty-Five Mile Fire, Chelan County will replace the dual box culvert with a concrete bridge that spans the creek, allowing post-fire flood flow to pass under South Lakeshore Road, not over it. The new bridge is expected to provide 12-foot-wide lanes with 7-foot-wide shoulders (38 feet curb to curb) to match adjacent roadway geometry east of the Twenty-Five Mile State Park entrance. The bridge length will allow for post-fire flood and debris flows to pass while also providing fish passage during all state-required fish passage flows. In addition, barrier heights shall be sufficient to protect bicycles using either a single-barrier system or a combination of concrete barriers with metal railing added to the top.
