Alta Sierra Reservoir Replacement Project

The existing 3 million gallon (3 MG) treated water Alta Sierra Reservoir was constructed in 1976, replacing the raw water storage reservoir originally constructed in 1965. The existing reservoir was constructed as a covered potable water storage reservoir with a Hypalon lining. Rehabilitation and repairs have been made on the reservoir, including a surface water collection system. However, the Hypalon lining is continuing to deteriorate and is nearing the end of its useful life. Continued operation of the existing reservoir in its deteriorated condition would increase the risk of contamination resulting from leaks in the liner and would require increasing maintenance in the future.

Two new water storage tanks, aeration blowers and mixers would be constructed within the footprint of the existing reservoir. The exact size, height, and configuration has not yet been determined and will be refined through the initial project processes. The tanks would be sized so that each tank can be taken out of service periodically for cleaning and maintenance. The new tanks are proposed to be concrete. The roof of the tanks would be approximately 30 feet high, which would be approximately 14 feet above the berm. A third tank is not proposed to be constructed at this time, but the space will be reserved for it.

To blend the tanks into the surrounding area, the District will re-landscape the surrounding berms and review staining the tanks a neutral color to blend with the surrounding environment. This would be coordinated with nearby residents.