Rough River Dam New Outlet Works and Cutoff Wall Project

This presentation will provide a status update on the Phase 2 Dam Safety Modification Project (Phase 2 Project). The purpose of the project is to reduce risks posed to the dam from internal erosion failure mechanisms present near the existing outlet conduit. The Phase 2 Project will construct a new left abutment outlet works followed by a cutoff wall that will extend fully across the dam foundation. The existing outlet conduit will be abandoned in place. The cutoff wall will then be constructed to extend across the dam foundation and through the existing outlet conduit. Dam restoration includes construction of a downstream filter, abandonment of the existing retreat channel, and relocation of the state highway back to the dam crest. This paper will provide an overview of the key construction features and sequences required to complete the project. The project is anticipated to be awarded in late 2025 and will take approximately 6 years to complete.