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May 21, 2021
Case Road Fish Barrier Removal
Location: Thurston County
General contractor: Granite Construction
This project started with significant challenges. To their surprise, as well as the owner’s, Granite crews discovered that some underground utilities were in conflict with the temporary traffic detour phasing. These utilities were supposed to be relocated by others out of the construction limits prior to starting the project, but were not done correctly, severely restricting the usable footprint on the west side of the project. To the east side of the project, there was a federally protected sensitive environmental area. The project included permit requirements with a short window to complete in-water work. At the time of this discovery, Granite was pushing up against this in-water work window, risking a year-long work suspension. Granite’s team of experienced fish-passage professionals went to work finding a proactive best-fit solution, instead of just waiting for the owner’s direction. The team changed the design of the structure footings to precast units from cast-in-place concrete, and worked with the culvert supplier to create a different structural plate layout, allowing for full sections to be pre-assembled outside of the excavation and seamlessly connect once placed. These two innovations allowed an accelerated installation timeframe, shaving weeks off of the duration of the original installation plan. As a result of the accelerated installation period, the Thurston County team was able to gain approval for a short-term roadway closure, which greatly mitigated the utility and sensitive area risks impacting the traffic detour phasing. By moving forward with the new plan and executing changes efficiently on the fly, Granite completed the culvert installation in less than the allotted closure time, minimizing impacts to the traveling public and providing both schedule and budget savings. Environmental impacts were also minimized. Granite’s quick installation plan meant less time pumping/bypassing the creek, limiting potential impacts to aquatic species. Streambed sediments are a tricky part of any fish barrier restoration. Depending on the material specified, restored streambeds can often go subterranean and require additional sediments to correct. Granite premixed and tested the permeability of the sediments, adjusting the blend to get the desired performance. This ensured a one-time installation, benefiting both the environment and project interests. The project was completed with zero rework and a minimal punch list.