By Thomas K. Pendergast
Plans to expand San Francisco’s high-pressure water system for fighting fires immediately after a major earthquake are beginning to take shape. The plans come following a Civil Grand Jury (CGJ) report in 2019 demanded that the City take action.
The report, titled “Act Now Before It Is Too Late: Aggressively Expand and Enhance Our High-Pressure Emergency Firefighting Water System,” questioned whether firefighters will have enough water pressure to fight conflagrations that would likely result after a major eartchquake. If a magnitude 7.8 or stronger earthquake happens sooner rather than later, neighborhoods in supervisorial districts 1, 4, 7, 8, 9 and 11 could be engulfed in a firestorm similar to the fire which destroyed much of the City in 1906.
The 1906 earthquake killed thousands, many of whom incinerated while trapped in rubble. The quake caused hundreds o f broken water mains and thousands of broken service connections. The system failures eliminated the water pressure needed to fight the ensuing firestorm.
In the years immediately following that devastation, the City built the Auxiliary Water Supply System – since renamed the Emergency Firefighting Water System (EFWS) – as a separate high-pressure water system composed of pipelines and sea-water pumps designed to withstand a massive earthquake and deliver enough water pressure to fight large fires.
At the time, most of the City’s residents lived on the east side, so the original system was only built out – with some later expansions – as far west as 12th Avenue in the Richmond District and eventually 19th Avenue in the Sunset District. As the City expanded, however, the high pressure pipes did not follow, leaving more than a dozen neighborhoods in the western and southern areas vulnerable to another devastating firestorm.
A March 2020 bond measure passed by voters allocates more than $153 million to expansion of the EFWS.
At a recent Government Audit and Oversight Committee meeting, District 4 Supervisor Gordon Mar brought together city officials to get an update on the progress in responding to the CGJ report.
“The expansion of the City’s Emergency Firefighting Water System is absolutely critical for ensuring that all neighborhoods and residents are protected in the event of a major earthquake and fire,” Mar said. “Our City is responding to several crises at the moment, and it’s difficult to think ahead about the impact of a large earthquake or the fires that are likely to follow from ruptured gas pipelines and electrical wiring. But ongoing action is needed to build resilient systems that would protect and save lives in the event of a natural disaster. The USGS (U.S. Geological Survey) has predicted a major earthquake of the magnitude of the 1906 quake or higher by 2032, causing widespread damage and devastation.”
John Scarpulla of the San Francisco Public Utilities Commission (SFPUC) gave an update on where they are now with addressing the CGJ report, which requested the generation and completion of two more reports: one giving a more detailed analysis of post-earthquake firefighting needs by neighborhoods; and the other a study analyzing additional EFWS seawater pump stations on the west side, which are not included in the bond money.
Both reports must be completed by June 30, 2021.
The CGJ report faulted the SFPUC for using maps that measured large areas, so that smaller neighborhoods within those areas might be more vulnerable than others immediately around them and yet might not show up on the current SFPUC maps used to determine how vulnerable different parts of the City are to fires after a major earthquake.
The SFPUC determined that they also need to update the data used by the maps to include building inventories and new construction and vegetation, none of which are incorporated into their current maps.
“Looking at the geotechnical factors in the city … for example: what’s in a liquefaction zone; what’s built on landfill; what’s built on bedrock; our building inventory materials; density; do they have sprinkler systems? Scarpulla asked. “Understanding the fire demands in each of the respective neighborhoods is a key step in how we upgrade the system,”
There is also the question about a seawater pump station.
“This is a high-level evaluation of a wide variety of categories that’s needed to look at when you’re talking about adding a seawater pump station,” he explained. “We’re looking at the regulatory and permitting requirements; siting considerations … obviously there’s sea level rise we need to deal with in San Francisco. There are lots of different engineering considerations, including the types of pumps we’re going to use…. Eventually that helps us determine capital costs, types of operations and maintenance activities that are required.”
The CGJ also requested a total of 20 “hose tender” pumps to distribute in the southern and western neighborhoods that are not adequately covered by EFWS hydrants. Each of those costs $1 million. The City is currently in the process of purchasing three of the 20 tenders that are needed to tap into underground cisterns scattered throughout the west side..
Mar mentioned that there is concern about tapping into the Sunset Reservoir because drinking water will be needed after the earthquake. He asked if seawater pumps would change that part of the plan.
“The more sources that we have, the more resilient the system’s going to be,” Scarpulla said. “And it also allows the fire department to utilize different water sources at different times to achieve better pressures. So flexibility is never going to be seen as a negative thing. I think it will really be (more important) how you prioritize these different sources.”
He noted that the Sunset Reservoir has two separate sections of 90 million gallons each, so their plan is to only draw from one of the two and leave the other for drinking water.
During public comment, however, Eileen Boken of the Coalition for San Francisco Neighborhoods said that only the north basin of the Sunset Revoir has been seismically retrofitted for large earthquakes “so the south basin could rupture in a seismic event.”
The two reports requested by the CGJ detailing the emergency firefighting needs and an analysis of the seawater pump stations are expected to be completed by the end of June.