Friday, October 14, 2016

Remembering Loma Prieta – And Preparing for the Next Big One

Monday, October 17th is the 27th anniversary of the Loma Prieta Earthquake. The 6.9 magnitude quake shook the earth for 15 seconds, took the lives of 67 people and injured almost 3,000 more. There was an estimated $6 billion in property losses. We here at the San Francisco Public Utilities Commission have been preparing for the next big quake ever since.

As the owner and operator of the Hetch Hetchy Regional Water System that serves water to 2.6 million people in four Bay Area counties, we have worked for more than 10 years to repair, replace, and seismically upgrade vulnerable portions of this system as part of the $4.8 billion Water System Improvement Program (WSIP). The program itself is more than 90% complete. Our water system is safer and more reliable today than it was 10 years ago, let alone 27 years ago. Our promise is that we can deliver minimum demand to our customers within 24 hours after a major earthquake. We can make good on that promise because of WSIP.

Here’s just a few reasons why:

* The Bay Tunnel is a seismic lifeline carrying water under San Francisco Bay. It was brought into service on time and under budget in October 2014.

* The New Irvington Tunnel carries water between our East Bay and Hetch Hetchy supplies and our Bay Area Customers. Located between the Calaveras and Hayward Earthquake faults, this seismically designed tunnel allows us to take the existing 88 year-old tunnel out of service for maintenance.

* A new Bay Division Pipeline #5 connects to both of these new tunnels in the East Bay and on the Peninsula to provide greater delivery reliability to our customers. It replaces two pipes that were constructed in 1926 and 1935.

Wait, that’s not all!

Our Harry Tracy Water Treatment Plant treats water from the Crystal Springs and San Andreas Reservoirs for more than one million customers in northern San Mateo and San Francisco counties. Upgrades at the plant include new filters, a new 11 million gallon treated water reservoir, and various other hydraulic, mechanical and electrical upgrades. The Harry Tracy Water Treatment Plant can now reliably provide 140 million gallons of water per day, for 60 days within 24 hours of a major earthquake.


The new 11.5 million gallon treated water reservoir is one of the improvements at the Harry Tracy Water Treatment Plant on the Peninsula.

Our Peninsula customers are served by several large water transmission pipelines, some of which are the oldest and most crucial parts of the system. The Peninsula Pipelines Seismic Upgrade Project addressed this issue by upgrading the most vulnerable portions of several of these pipelines.


Crews install a pipe segment in the Peninsula to improve the pipeline’s reliability, especially during an earthquake.

This work is never done. We will continue to replace and upgrade our system pipelines, pump stations, and treatment plants even after the WSIP is complete. We’ll worry about your water so you won’t have to.

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