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Water Supply System Review

The Auxiliary Water Supply System (AWSS) was designed to protect San Francisco from fires following earthquakes by City Engineer Marsden Manson beginning in 1908, and expansion of the system continues at this time.

The lower zone, which supplies water by gravity to hydrants from sea level to 150 feet elevation, suffered five breaks in the South-of-Market area because of liquefaction and lateral earth spread.

The upper zone of the AWSS, however, functioned normally through the earthquake period, and was used to suppress earthquake-caused fires.

Two pump stations associated with the Auxiliary Water Supply System functioned as designed, and at 5:20 p.m., operators at both stations reported to the attendant at Jones Street Tank that they were standing by to pump saltwater into the system. Pump stations No. 1 and No. 2 went on line in tandem at 8 p.m. to fill Jones Street Tank and to supply water to High Pressure hydrants in the Marina District. Further, as again envisioned by Marsden Manson, the fireboat Phoenix supplied saltwater to large-diameter hose and associated valves at the Marina District fire.

1. Breaks in the domestic mains in the Marina District severely hampered fire suppression operations.

2. One 75,000-gallon cistern at Fifth and Harrison streets developed a leak at the cold joint between the roof and sidewall due to earthquake damage and lost 20 percent of its water, leaving 60,000 gallons for fire suppression purposes.

3. Falling structures destroyed one High Pressure hydrant and damaged another.

4. Placing the Utility and Valve Units out-of-service hampered the Department's ability to quickly close off leaks in the High Pressure system.

Water Supply System Recommendations

1. Damage assessment of the High Pressure system must be accomplished quickly to allow restoration of water service for fire suppression purposes. Technical improvements such as seismic valves to be installed as required by the 1986 bond issue may improve the system's survivability during major earthquakes.

2. The use of large-diameter hose and associated valves should be expanded, with a commensurate increase in the number of hose tenders, and the amount of five-inch hose and and associated valves.

3. Status of the fireboat Phoenix should be clarified.

4. In-service firefighters should be trained in the emergency operation of the High Pressure system valves to be able to quickly isolate main breaks.

5. An agreement with the Department of Public Works should be drawn up for immediate post-earthquake inspection of all cisterns.

6. The Utility and Valve units should be stored at fire stations for emergency use.

Division of Training Review
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