The Association of State Dam Safety Officials (ASDSO) in the U.S. recently named the North Fork Spillway and Embankment Improvement project its 2021 National Dam Rehabilitation Project of the Year.
Each year, ASDSO honors individuals and organizations making exemplary contributions to the improvement of dam safety in the U.S. This award recognizes a unique remedial design, for a project of any size, that advances the state-of-the-art in the field of dam safety and exemplifies the professional engineering and construction standards that dam safety requires.
This reservoir and water treatment plant, owned by the City of Asheville, N.C., was constructed in 1955 and provides 70% of the city’s water supply. The dam design was based on industry standards and best practices at that time, which have since greatly improved. The city asked for an evaluation of the existing spillway system, and Schnabel Engineering provided alternatives for a larger-capacity spillway system that could better withstand severe storm inflows and potential seismic activity.
The Schnabel team worked with the contractor, Phillips & Jordan, over a nearly three-year-long period. Construction consisted of a new auxiliary spillway using Fusegates (Hydroplus), modifications to the main and saddle dams, soil nail and rock tie-back wall, upgrades to the intake tower, extension of the outlet works conduit, and rehabilitation of the principal spillway and chute.
These improvements created a safe, reliable solution for the community’s growing water needs, which improves the original structure and ensures it is prepared to withstand modern weather patterns and record rainfalls without failing the city’s water consumers. Multiple opportunities were found for value-engineering improvements, and construction was carefully planned and executed without disrupting water supply to the city and its surrounding areas.