Tag Archive for 'earthquake'

Protecting Bay Area’s Water Supply in Event of Major Earthquake

Published on 04/18/2012 in levees and management. 0 Comments Tags: , , , , .

Retrieved from: Llnl

“One day before the 106th anniversary of the San Francisco Earthquake of 1906, Mayor Ed Lee was in San Mateo County on Tuesday to mark a major milestone in securing the region’s water supply in the event of a future major earthquake.

“Lee joined San Francisco Public Utilities Commission general manager Ed Harrington and San Mateo County Supervisor Adrienne Tissier on the banks of the Lower Crystal Springs Reservoir, where improvements to the 124-year-old Crystal Springs Dam have just been completed.

“The dam improvements — which doubled the width of the main spillway and raised the height of a parapet on top of the structure by 9 feet — were part of the SFPUC’s $4.6 billion Water System Improvement Program, which consists of 81 seismic improvements to water delivery pipelines, dams and reservoirs from Hetch Hetchy to San Francisco.

“Harrington said the seismic upgrades “virtually guarantee” the reliability of safe drinking water for 2.6 million Bay Area residents within 24 hours of a major earthquake.

“These projects now serve as our reinforced lifeline to deliver Hetch Hetchy water around the Bay,” Harrington said.

“Five years ago we would not have had the same reliability we have today,” he said.

Read more: Bay citizen

sammykayed

Water tunnel work begins in Sunol

Published on 04/08/2011 in solutions and outreach, water diversions and water shortage. 0 Comments Tags: , , , , , , .

Retrieved from: Blog Spot

“Work has begun on a tunnel that is part of a project to safeguard the drinking water supply of more than 2 million San Francisco Bay area residents in case of an earthquake.

“The 3.5-mile New Irvington Tunnel will run from Sunol to Fremont’s Mission San Jose district. Officials say the existing Irvington Tunnel, which connects several pipelines bringing water from the Sierras, is susceptible to heavy damage during an earthquake.

“The Oakland Tribune reports that crews have so far tunneled about 100 feet at a rate of 22 feet per day. The $227 million tunnel is expected to be completed in 2014.

“It is part of the San Francisco Public Utilities Commission’s $4.6 billion effort to upgrade the system that draws water from Yosemite National Park’s Hetch Hetchy Reservoir and serves 2.4 million customers in four Bay area counties.”

Read more: Mercury News

sammykayed

USGS estimates higher risk to Delta levees from quakes

Published on 02/01/2011 in agriculture, dams, desalination and policy. 0 Comments Tags: , , , , , , , , .

Retrieved from: a change in the wind

“The potential for earthquakes to cause massive levee failures in the Delta is probably greater than previously estimated, seismic experts reported Friday.

“In a presentation to the Delta Stewardship Council, scientists from the U.S. Geological Survey said prior studies made “very, very unrealistic” assumptions about ground motion in the Delta.

“Those studies assumed soils are relatively uniform across the region, said David Schwartz, USGS earthquake geologist. As a result, the ground shaking assumed in those studies was likely low.

“Yet those earlier surveys still predicted dire effects: Dozens of levee breaks could occur simultaneously, flooding numerous islands

“There are 1,100 miles of levees in the Sacramento-San Joaquin Delta, and almost none meet the 100-year-flood standard set by the federal government as minimum protection for urban areas. Delta levees, built to protect farms, are much smaller.

“Islands in the Delta are actually like bowls. A century of farming has caused island peat soils to degrade and subside below sea level, creating giant voids ringed by levees.

“The Delta quake threat is a statewide concern, because the estuary is a freshwater supply for 25 million Californians. If several islands flooded at once, salt water would rush in from San Francisco Bay to fill those voids.

“State water officials previously estimated this scenario could cut off freshwater deliveries from the Delta for more than a year.”

Read more: Sacbee

sammykayed