A Water Tunnel on Time and Under Budget
Nov. 10, 2014
By General Manager Jeffrey Kightlinger
Big water projects – even miles-long tunnels – can be built within their budgets. The latest case in point is a very similar (yet on a somewhat smaller scale) project to the tunnels proposed by the Bay Delta Conservation Plan. The project is the first-ever tunnel under San Francisco Bay, built to convey a reliable water supply to millions of residents. The project met its deadline and came in nearly 8 percent below its original budget. For those following BDCP, this is a project worth noting.
The agency behind the Hetch Hetchy project, the San Francisco Public Utilities Commission, confronted a very similar challenge to that now facing Metropolitan with the State Water Project. Potential damaging earthquakes put the reliability of both long-time projects at risk. And part of the solution for both included tunnels.
An aging SFPUC water pipeline on the floor of San Francisco Bay was identified as vulnerable in a large earthquake. As part of a broader upgrade project, the utility constructed a five-mile tunnel under the Bay, much like those proposed for the BDCP intake/tunnel project. Likewise, the soil profile under the Bay is quite similar to that under the Sacramento-San Joaquin Delta, making it an important test case for this kind of project and technology.
Construction began in 2010. The tunnel is now in service. Originally estimated to cost $313 million, the actual cost turned out to be $288 million. And nearly all of the material excavated during the tunnel boring process was reused nearby, including for restoration (another parallel with BDCP).
This is one notable success story for a major water project, but there are many. The largest reservoir in Southern California, Metropolitan’s Diamond Valley Lake in southwest Riverside County, was constructed on time and within 5 percent of its original budget. Completed in 1999, Diamond Valley is now helping to provide an important drought-year supply for the Southland. It’s a reminder that the cost to society of not upgrading basic infrastructure can be far greater than each generation making the right investments. The new tunnel under San Francisco Bay is an important protection for that region’s water supply. BDCP is about protecting a vital water supply for California and restoring an equally threatened Delta ecosystem.
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June 18, 2014 - On Several Fronts, Promising Signs of Water Progress
May 22, 2014 - Conservation: Lowering Use is Key in Warm Weather
Mar. 13, 2014 - Ops: Surviving the 1977 Drought
Feb. 24, 2014 - Surviving a Zero Allocation – Leave it to the “Ops” team
Jan. 16, 2014 - What MET's Looking for
Dec. 17, 2013 - Water Progress in Northern California
Nov. 1, 2013 - A State Water Action Plan That Fits the Times
Oct. 23, 2013 - It’s dry out there, so watch your water use