By Lizzie Jordan : sfgate – excerpt
In late December, the filtration tanks at a treatment plant in San Bruno were quietly filled with millions of gallons of raw water.
At the same time, water was drained out of Mountain Tunnel, the century-old artery connecting the Bay Area to Hetch Hetchy Reservoir, 175 miles away in Tuolumne County. From Tuesday through March 5, crews will traverse the 19-mile conduit making repairs and performing a rigorous inspection. Officials have known for years that the tunnel is at risk of catastrophic collapse.
The shutdown will help them decide whether the tunnel can be saved or will need to be entirely replaced… (more)