Program: San Diego County Water Supply & Management
Program Chair Roy Henderson introduced our Speaker Nathan Faber from the San Diego County Water Authority, where he is the Operations and Maintenance Manager for Regional Water Infrastructure and Rehabilitation. Nathan Faber has a degree in Mechanical Engineering from University of California Santa Barbara, and a Masters in Civil Engineering from Cal State Long Beach.
Nathan Faber gave us a highly engaging presentation using a Google Earth interactive slide show and his Power Point presentation. Putting our water supplies and infrastructure in perspective, he explained that 80% of our water is imported from outside the County, with 60% coming from the Colorado River Aqueduct, another 20% from the State Water Project (Northern California) and the remaining 20% being local in source.
Water storage includes north of the County Diamond Valley Lake, and water treatment at Lake Skinner.
The San Diego County Water Authority is responsible for some 310 miles of pipe, with two main aqueducts, all buried. The general flow is North to South, principally via gravity. Some water is sent in the other direction (north), such as from San Vicente Reservoir, and is pumped, and other water comes from the Carlsbad Desalination Plant and is pumped to Twin Oaks and Valley Center.
The Authority is responsible for $5 billion in replacement value of assets, which include 36 inch pipes to member agencies, the Olivenhain Reservoir, the Twin Oaks Water Treatment Plant, two Hydro-Electric plants including the Hodges storage, and pumping stations.
He demonstrated the workings of the Asset Management Program which manages risk of failure and staged replacement of pipes. While they do not have unlimited monies to spend, they cannot risk pipe failures, especially where other infrastructure and housing is located adjacent to the pipes, because of the severity of the consequences of pipe failure. They monitor the health of the pipes by remote field testing and fiber optic cable detection of corrosion and failure of wires within the concrete pipes.
The Water Authority’s Board of Directors took the decision to rehabilitate certain areas of pipes by placing steel liners inside the existing pre-stressed concrete pipes – essentially relining them. This is done in stages, removing only two sections of pipe at either end, pressing the collapsible steel-liners through the pipe and expanding them, then welding the seams.
Mr. Faber was asked many good questions from the audience, including the sources of funding for the rehabilitation of the pipes, which costs about $5-8 million per mile. The Water Authority has a total of 274 employees, with 80 people or so operating the system. The relining work is done in Winter from October through April. The supply is managed by pipeline redundancy and storage.
Other questions concerned the threat of earthquakes from the three main faults, the Authority’s response to the Twin Tunnel proposal for the Bay Area Delta, the life span of the steel liners (75 years) and the lawsuit with the Metropolitan Water District (heading for the California Supreme Court). The Carlsbad Desalination Plant contributes about 7 – 10% of the water supply to the County.