The project rehabilitates the deteriorating interior and failing exterior coated surfaces of the existing Reservoirs 2/2A steel potable water storage tanks. The project is located south of U.S. Highway 50 on approximately nine acres of EID-owned land along a private drive west of Snows Road in the Camino Community Region of El Dorado County.
The painted surfaces of both tanks are approximately 16 years old. The interior and exterior surfaces are in need of recoating to ensure compliance with the California Department of Public Health standards and regulations to provide a safe and reliable potable water supply.
Construction and inspection contracts were awarded in August 2020 to Advanced Industrial Services and MCS Inspection Group.
The recoating process requires the use of air compressors, media blasters, generators, truck and material handling equipment. Structural repairs to the interior of the tanks are incorporated as needed based on interior inspections.
As these tanks are critical to water service, EID is only able to take one tank offline for inspection and repair at a time. Reservoir Tank 2A was selected first given the external coating failure and was then drained. Once the tank was emptied for inspections, significant metal loss was found to various structural components of the tanks, including the earthquake straps, rafter clips, and the roof rafters. It was determined that the failure mode was occurring at bolted connections between the roof rafters along with failures of the original coating to all inside surfaces. This provided a location for corrosion to spread, and as result, all 215 straps were required to be replaced with welded angle iron to minimize future corrosion of not only the earthquake straps but also the roof rafters. The damage is much more significant than originally determined in preliminary inspections (before the tanks were emptied). Although Reservoir 2 cannot be inspected until Reservoir 2A goes online and Reservoir 2 can be drained, a similar effort and project schedule is anticipated for that tank.
The project was originally anticipated to be completed over a two-year period, but as significant additional damage to the metal structure has been found we anticipate the project may roll over into a third year (see Board Agenda Action Item No. 8 – Jan. 25, 2021).
Work is reliant on weather conditions as application of paint coatings are dependent on appropriate temperature and humidity.
Update project information as of December 2021.
