auxiliary water supply system (awss) study

Fina l Rep or t

Auxiliary Water Supply System(AWSS) Study

Prepared for

Capital Planning CommitteeCity and County of San Francisco

January 23, 2009

Prepared by

1390 Market Street, Suite 1100, San Francisco, CA 94102

Acknowledgments

This report represents a significant effort by many staff in San Francisco’s Capital PlanningProgram, Department of Public Works, Fire Department and Public Utilities Commission.Many thanks go out to them for their assistance and contribution to the success of thisproject.

EXECUTIVE SUMMARY

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Contents

Contents................................................................................................................................... iiAcronyms and Abbreviations .............................................................................................. viExecutive Summary..............................................................................................................vii1.0 Introduction.................................................................................................................1

1.1 Background ......................................................................................................11.2 Purpose.............................................................................................................21.3 Project Scope....................................................................................................31.4 Water Supply Sources Available for Firefighting in San Francisco............3

1.4.1 Low Pressure Domestic Water System............................................31.4.2 Auxiliary Water Supply System.......................................................31.4.3 Portable Water Supply System.........................................................41.4.4 Deployment of Water Supply Sources ............................................4

2.0 Existing AWSS ............................................................................................................62.1 System Description .........................................................................................6

2.1.1 AWSS Facilities ..................................................................................82.1.2 High Pressure Distribution Piping System ..................................112.1.3 Underground Cisterns.....................................................................122.1.4 PWSS .................................................................................................12

2.2 System Operations ........................................................................................123.0 Usage and Needs of Existing AWSS.......................................................................14

3.1 Non-Earthquake Conditions ........................................................................143.2 Post-Earthquake Conditions........................................................................15

3.2.1 Probability of Future Earthquakes.................................................163.2.2 Post Earthquake Conflagration Potential......................................173.2.3 Reliability of the Domestic Water System....................................183.2.4 1989 Loma Prieta Earthquake .........................................................19

4.0 Water Supply for Firefighting in Other Cities ......................................................214.1 Water Supply for Firefighting in Other Cities ............................................214.2 Summary ........................................................................................................27

5.0 Condition Assessment of Existing AWSS Facilities.............................................305.1 Condition Assessment of Existing Facilities ..............................................30

5.1.1 Twin Peaks Reservoir......................................................................305.1.2 Ashbury Tank...................................................................................305.1.3 Jones Street Tank .............................................................................335.1.4 Pump Station No. 1 ..........................................................................345.1.5 Pump Station No. 2 ..........................................................................35

5.2 AWSS Pipelines............................................................................................365.2.1 Age and Condition...........................................................................365.2.2 Seismic Vulnerability......................................................................40

6.0 Geographic Coverage of the AWSS........................................................................466.1 AWSS Service Area Characteristics.............................................................46

6.1.1 Geographical Coverage ...................................................................476.1.2 Population.........................................................................................48

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6.1.3 Land Use ........................................................................................... 506.1.4 Building Construction Material..................................................... 516.1.5 Building Values ............................................................................... 526.1.6 Peak Ground Acceleration.............................................................. 536.1.7 Liquefaction Susceptibility ............................................................ 546.1.8 Greater Alarm Fire Incidents.......................................................... 56

6.2 Expansion of the AWSS............................................................................... 566.2.1 Potential AWSS Expansion Areas.................................................. 566.2.2 Storage Capacity Assessment......................................................... 596.2.3 AWSS Expansion Summary ........................................................... 61

7.0 AWSS Expansion Efforts with SFPUC Recycled Water Project.......................... 627.1 Definition of Recycled Water ..................................................................... 627.2 San Francisco Recycled Water Program and Westside Recycled Water

Project ............................................................................................................ 627.3 AWSS – Recycled Water Coordination Opportunities............................ 63

7.3.1 Coordination Concept 1: Common Trenching ............................ 637.3.2 Coordination Concept 2: Supplying Recycled Water to AWSS 657.3.3 Coordination Concept 3: Distribution of Recycled Water Through

the AWSS.......................................................................................... 657.4 Summary ....................................................................................................... 66

8.0 Improvements Required to Meet the Current and Future Needs....................... 678.1 AWSS Existing Facility Improvements....................................................... 67

8.1.1 Improvements to Above Ground Facilities .................................. 678.1.2 Improvements to Pipelines............................................................. 688.1.3 Fireboat Headquarters..................................................................... 708.1.4 Cost Estimate.................................................................................... 70

8.2 AWSS Expansion Projects........................................................................... 728.3 Benefits of AWSS......................................................................................... 72

9.0 Conclusions and recommendations ....................................................................... 749.1 Conclusions................................................................................................... 749.2 Recommendations........................................................................................ 75

List of TablesTable ES-1. Potential Building Damage Due to Earthquake ............................................xTable ES-2. Facility Deficiencies Identified During Site Visits ......................................xiTable ES-3. Improvements to Existing Facilities ............................................................ xivTable ES-4. Pipeline Improvement Recommendations...................................................xvTable ES-5. AWSS Expansion Areas and Costs .............................................................. xviTable 3-1: AWSS Use for Greater Alarm Firefighting ...................................................... 14Table 3-2: Number of Fires Estimates due to San Andreas Fault Earthquakes ............. 17Table 4-1: Cities contacted regarding auxiliary water supply systems.......................... 21Table 4-2: auxiliary water supply systems of other cities................................................ 28Table 5-1: Twin Peaks Reservoir – Observations and Suggested Improvements ......... 31Table 5-2: Ashbury Tank – Observations and Suggested Improvements...................... 32Table 5-3: Jones Street Tank – Observations and suggested Improvements ................. 33Table 5-4: Pump Station No. 1 – Observations and suggested Improvements.............. 34Table 5-5: Pump Station No. 2 – Observations and suggested Improvements.............. 35

EXECUTIVE SUMMARY

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Table 5-6: Study Area Earthquake Damage Results..........................................................43Table 6-1: Population Growth of San Francisco, 1900 – 2000 ...........................................48Table 6-2: Population Growth of San Francisco, 1900 - 2000............................................49Table 6-3: Potential Fire Flow Scenarios and Storage Assessment for Non-Earthquake

Conditions..................................................................................................................60Table 6-4: Potential Fire Flow Scenarios for Earthquake Conditions .............................61Table 6-5: AWSS Expansion Components..........................................................................61Table 7-1: Recycled Water Coordination Concepts ...........................................................66Table 8-1: AWSS Facility Improvements Cost Estimate ...................................................71Table 8-2: AWSS Distribution Piping Improvements Cost Estimate..............................71Table 8-3: AWSS Proposed Expansion Cost Estimate.......................................................72Table 9-1: Improvements to Existing Facilities ..................................................................76Table 9-2: Pipeline Improvements Recommendations .....................................................77Table 9-3: AWSS Expansion Areas and Costs ....................................................................78

List of Figures

Figure es-1: Existing Auxiliary Water Supply System .....................................................viiFigure 1-1: City of San Francisco 1906 Earthquake Burned Area.......................................2Figure 1-2: Water Sources Available for Fighting Fires ......................................................5Figure 2-1: Existing Auxiliary Water Supply System..........................................................7Figure 2-2: Schematic of Auxiliary Water Supply System Components...........................8Figure 3-1: Greater Alarms Incidents for 2002 to 2007.......................................................15Figure 3-2: Probability of Future Earthquakes in the Bay Area.......................................16Figure 4-1 : City of Vancouver dedicated fire protection system (dfps) layout .............27Figure 5-1: AWSS Pipeline age ............................................................................................37Figure 5-2: Pipeline remaining useful life..........................................................................38Figure 5-3: Infirm Soil Areas................................................................................................42Figure 6-1: San Francisco City Neighborhoods Used for AWSS Study ..........................46Figure 6-2: AWSS Distribution Piping Installation ..........................................................47Figure 6-3: Existing AWSS Distribution Network and Average Population Density by

Neighborhood Area ..................................................................................................50Figure 6-4: Existing AWSS Distribution Network and Land Use....................................51Figure 6-5: Existing AWSS Distribution Network and Wood Construction Buildings52Figure 6-6: Existing AWSS Distribution Network and Private Building Value............53Figure 6-7: Existing AWSS Distribution Network and PGA ...........................................54Figure 6-8: Existing AWSS Distribution Network, Liquefaction Susceptibility ...........55Figure 6-9: Proposed AWSS Expansion ..............................................................................57Figure 7-1: Recycled Water Coordination Opportunities .................................................64

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Appendices

A References

B Locations of Pipeline Repairs in Marina Following Loma Prieta (USGS, 1992)

EXECUTIVE SUMMARY

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Acronyms and Abbreviations

AWSS Auxiliary Water Supply System

AWWA American Water Works Association

BART Bay Area Rapid Transit

DFPS Dedicated Fire Protection System

DPH Department of Public Health

GIS Geographic Information System

GPM Gallons per minute

LAFD Los Angeles Fire Department

MDFPS Mobile Disaster Fire Protection System

MMI Modified Mercalli Intensity

MWSS Municipal Water Supply System

PGA Peak Ground Acceleration

psi Pounds per square inch

PWSS Portable Water Supply System

RWMP Recycled Water Master Plan

RWP Recycled Water Project

SCADA System Control and Data Acquisition

SFDPW San Francisco Department of Public Works

SFED Single Family Equivalent Dwellings

SFFD San Francisco Fire Department

SFGOV City and County of San Francisco

SFPUC San Francisco Public Utilities Commission

ULDH Ultra large diameter hose

USGS United States Geological Services

WRWP Westside Recycled Water Project

Auxiliary Water Supply System StudyJanuary 23, 2009

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Executive Summary

Background

The auxiliary water supply system (AWSS) is a water distribution system operated andmaintained by the San Francisco Fire Department (SFFD). The AWSS delivers water underhigh pressure for fire fighting and is independent from San Francisco’s (City) domesticwater system. Figure ES-1 shows the two pump stations, two water storage tanks, onereservoir, 172 cisterns and approximately 135 miles of pipes in the AWSS. Not shown onthe map, but also part of the AWSS are several other facilities which allow drafting directlyfrom San Francisco Bay. There are 52 suction connections along the north eastern waterfront which allow fire engines to pump water from the Bay. Two fire boats can supplysaltwater to the AWSS by pumping into any of five manifolds connected to the AWSS pipes.

FIGURE ES-1: EXISTING AUXILIARY WATER SUPPLY SYSTEM


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The AWSS was constructed in 1913, shortly after the 1906 earthquake. The fire thatfollowed the earthquake is the largest in U.S. history. It was responsible for destroying 80percent of the 28,000 buildings lost, and was uncontrollable largely due to lack of watersupply. The AWSS was constructed so that the City would not suffer such devastationagain in the event of another earthquake.

Purpose

The purpose of this study is to assess the need for improvements to the aging AWSS anddetermine the funding requirements to accomplish them. This study therefore includes thefollowing work:

Evaluate the usage and determine the importance of the AWSS during day-to-day andpost-earthquake conditions.

Evaluate the geographical coverage of the system and determine the need to expand thecurrent service area to the west and south sides of the City where the AWSS is notavailable.

Assess the condition of existing facilities and identify improvements needed tomaintain the system in a state of good repair.

Findings and Conclusions

Assessment of the Importance of the AWSS

The concept of a supplemental fire fighting system is not unique to San Francisco. In 2003,the City of Vancouver, Canada constructed a very similar system to provide a redundantfire fighting supply to its downtown core. The City’s AWSS served as a model for theVancouver system, which includes two saltwater pump stations and seven miles ofpipelines. The City of Oakland, California also had a redundant fire distribution system inthe downtown area. The independent system of pipelines was supplied by a pump stationat Lake Merritt. The system was shut down during the construction of Bay Area RapidTransit, but has not been returned to service since. Oakland does currently maintain fourhose wagons with equipment similar to SFFD’s Portable Water Supply System (PWSS).Other cities, including Berkeley, California and Seattle, Washington have also equippedsome vehicles with portable water supply hoses and fittings. Like San Francisco, these citiesare subject to high earthquake hazards. Earthquake risks are a major reason they havedeveloped auxiliary fire fighting systems and have looked to the City’s AWSS as a model.

Following the Loma Prieta earthquake, damage to the domestic water pipes in the MarinaDistrict impaired the water supply to the domestic hydrants in the area. The fire boatPhoenix and the Portable Water Supply System (PWSS) were used together to prevent alarge fire from becoming a conflagration in this area. The AWSS was largely functional afterthe earthquake. Communication systems and valving capability issues which hampered theimmediate implementation of the AWSS have since been addressed.


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The SFPUC is currently seismically upgrading the domestic water system. Pump stations,tanks, reservoirs and critical transmission pipelines are being replaced or retrofitted toimprove their reliability in the next major earthquake. These types of facilities often requiresignificant time and resources to restore when they fail after an earthquake. Therefore,improving these facilities now maximizes seismic reliability and significantly improves therecovery capability of the domestic system.

By their nature, domestic water mains are more vulnerable to earthquake damage.Numerous service connections and the jointed construction that is the industry normcontribute to their vulnerability. However, as demonstrated following the Loma Prietaearthquake, the SFPUC is able to make numerous water main repairs and restore water toits customers in the days following an earthquake.

Fire suppression will be critical immediately following an earthquake. The design elementsof the AWSS, such as restrained pipeline joints, make it more resistant to earthquakedamage. Because the AWSS pipes are designed to overcome some of the vulnerabilities ofstandard water pipes, it is more likely that they will be serviceable after an earthquake. Thedesign features which strengthen them against seismic forces include fewer branches andservice connections as well as restrained joints.

The USGS estimates a 62 percent probability of a magnitude 6.7 or greater earthquake in theBay Area by the year 2032. This earthquake is likely to be centered closer to Bay Area urbancenters. By comparison, the Loma Prieta earthquake was a magnitude 6.9 event centered 60miles south of San Francisco. The 1906 earthquake was the impetus for constructing theAWSS. Earthquake readiness remains one of the primary concerns of the City and the mainreason for maintaining the AWSS. The Marina District fire following the Loma Prietaearthquake illustrated the value of backup water supply systems.

A report by the Applied Technology Council (ATC, Draft, 2005) described building valuesand potential earthquake losses in San Francisco. The total estimated value of the privatelyowned building stock in San Francisco is approximately $104 billion, which does not includebuildings owned by City, State and Federal agencies. The potential damage to buildingsfrom earthquake shaking, shown in Table ES-1, is estimated to range from $8.5 billion to$29.1 billion, for a 6.9 magnitude event on the Hayward fault and 7.9 magnitude event onthe San Andreas fault, respectively. Fire following earthquake would increase these lossesto $16.3 and $37.9 billion, respectively. This represents $8 billion in potential fire damagefollowing an earthquake. Approximately 20 to 50 percent of the total earthquake damagewould be caused by fire.

These estimates account for the water supply redundancy provided by the AWSS. Whilemany factors may prohibit a direct comparison, recall that without the AWSS, firecontributed to 80% of the total losses in 1906. ATC did not analyze conditions without theAWSS, but the losses would be expected to be higher. Experience in the 1906 earthquakeand again in Loma Prieta has shown that redundancy in water supply for fire fighting isneeded to protect the City. Probability statistics on future earthquakes indicate that there isa strong possibility that the AWSS will be needed during a major earthquake within the next24 years.


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TABLE ES-1. POTENTIAL BUILDING DAMAGE DUE TO EARTHQUAKE

HaywardEarthquake

Magnitude 6.9

San AndreasEarthquake

Magnitude 6.5


Magnitude 7.2


Magnitude 7.9($ billion) ($ billion) ($ billion) ($ billion)

Building DamageDue to Shaking $8.5 $11.8 $18.6 $29.1

Building DamageDue to Shaking andFire

$16.3 $20.1 $27.3 $37.9

Source: ATC, 2005

The AWSS is an important asset to the City of San Francisco. Continued maintenance of thisinvestment is prudent for the following reasons:

It protects the lives, homes and business of the City from what could be a substantialloss.

A catastrophic fire destroyed much of San Francisco in the 1906 earthquake. Thesystem was constructed to prevent such an event from happening again.

The conflagration risk in parts of San Francisco today is just as great as it was in1906. The value of the system in mitigating this risk has not diminished.

There is a high likelihood that a major earthquake will occur in the not too distantfuture. Preparedness for this known risk is crucial.

Rehabilitation of Above Ground Facilities

All of existing above-ground facilities and roughly half of the pipelines are of the originalconstruction completed in 1913. They are all approaching 100 years old. These facilitieshave been in service for a long time and remain operational due to the diligent maintenanceof the SFFD. However, the physical condition of the facilities compromises the system’sreliability. Site visits to the pump stations, tanks and the reservoir were conducted inFebruary 2008 and the deficiencies observed are described in Table ES-2.

Condition of Buried Pipelines

There is not much information on the physical condition of the pipes in the system, exceptthat pipe leaks are repaired at a frequency of about two per year. While the age of theAWSS pipelines are known, their physical condition is relatively unknown. Pipe conditionscan vary widely because of the many factors that can affect pipeline deterioration, such assoil settlement, corrosive soil chemistry, exposure to bay water tidal fluctuations and straycurrents. Pipes in some areas may be in good condition despite their age, while others maybe substantially deteriorated. The amount of AWSS pipeline that needs replacement and


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the time frame is best determined through a comprehensive condition assessment andreplacement program.

TABLE ES-2. FACILITY DEFICIENCIES IDENTIFIED DURING SITE VISITS

Facility DeficienciesAshbury Tank Tank and pump station building do not meet current seismic codes and

are likely to be damaged after a major earthquake.Tank has served beyond the typical useful life.Mechanical and electrical equipment is old and in need of replacement.

Jones Street Tank Tank anchorage is inadequate and does not conform to current seismiccodes.Cracking and deterioration of tank walls observed.Tank has served beyond the typical useful life.

Twin PeaksReservoir

Drops in water levels suggest that reservoir liner may need repair.Reservoir conditions below water level need to be inspected.

Pump Station No. 1 Settlement problems in the basement slab have compromised supportfor equipment and floor plates.Mechanical and electrical equipment is old and in need of replacement.

Pump Station No. 2 Pump building does not meet current seismic codes and is likely bedamaged after a major earthquake.Supporting walls and beams in the basement have deteriorated andtheir structural integrity have been compromised.Mechanical and electrical equipment is old and in need of replacement.

However, based on generalized estimates of useful life, the 77 miles of original AWSSpipeline constructed in 1913 may be nearing the end of its useful life. Some or all of thisoriginal pipe may require replacement over the next 50 years. This equates toapproximately 1.5 miles of pipe per year over the next 50 years. The 58 miles of pipeconstructed after 1913 may similarly require replacement thereafter.

The cost of installing AWSS pipe is significantly higher than that for typical domestic waterpipe. Each mile of AWSS costs approximately $20 million to install, vs. approximately $3.7million for domestic water pipe. This comparison is based on 20-inch diameter pipe. Thereare several factors that contribute to the higher cost. Pipe fittings and hydrants are speciallycast, making them costly to procure. There is a single foundry that produces thesecomponents. For example, an AWSS hydrant costs approximately $20,000 vs. $3,000 for astandard domestic hydrant. A 45-degree elbow costs approximately $5,100 vs. $2,800 for thesame component of the domestic water system. The pipe joints for domestic water pipes aretypically rubber gasketed joints which may be pushed on in the field. AWSS pipes use thesesimilar types of joints, but in addition, at thrust points, the joints are restrained against pull-out using stainless steel tie rods. The restrained joints increase the cost of both material andinstallation for AWSS pipe. At the unit costs indicated above, replacement of 1.5 miles peryear would cost approximately $30 million annually.


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Upgrading Domestic System Pipes In-Lieu of Replacing AWSS Pipes

Upgrading select portions of the domestic system in lieu of replacing AWSS pipes mayappear to have multiple benefits – adding reliability to both the domestic system and theAWSS. However, the advantages may be offset by several factors. To provide the samelevel of reliability as the current AWSS, upgrades to the domestic system pipes would needto be in accordance with AWSS specification, likely negating potential cost savings.Ensuring reliable supply to a domestic hydrant may require retrofitting the entire length ofpipe from the hydrant back to the water source, usually a tank or reservoir. This has thepotential to increase the total length of pipe that must be upgraded. An aspect of the AWSSthat increases its reliability is the minimal number of branches and service connections.Significant pipe network reconfiguration effort could be required to achieve a similar levelof reliability in the selected portions of the domestic system.

Optimizing the AWSS Pipe Network

The annual expenditures for pipe replacement are directly related to the amount of agingpipe in the system. The current pipe network configuration requires a significant annualexpenditure to maintain the system in a state of good repair. Optimizing the pipe networkwould reduce the long-term expenditures and result in other benefits to the system, such asimproving reliability and flexibility. Optimization involves evaluating current developmentand firefighting needs. The piping layout and density would be modified to moreefficiently meet those needs.

For example, the density of piping in the Downtown area is approximately 110 feet of pipeper acre. By comparison, the density of piping in the North Beach, Pacific Heights andMarina Districts is approximately 50 – 70 feet of pipe per acre. The optimization process inthe Downtown area would evaluate whether the firefighting needs could be met with abackbone system. A backbone system consists of a streamlined network of larger diameterpipes spaced farther apart. This is in contrast to the current configuration of smaller pipesspaced much closer together. Service would be extended to either side of the backboneusing the PWSS.

An optimized pipe network may have multiple benefits:

An optimized pipe network is more financially sustainable. Because the overall lengthof pipe is reduced, the long-term cost of maintaining the system is reduced.

A backbone system is also more seismically reliable. A reduction in branches andoverall pipe length result in fewer opportunities for pipe breaks in the system in anearthquake.

In a backbone system, the function of a portion of the buried pipe network is replacedwith PWSS capability. Expanding the PWSS enhances the flexibility of the system.PWSS is portable and scalable to meet the needs of each incident. In an earthquake,additional mobile capability will increase SFFD’s ability to bring resources to locationswhere they are needed most.

Additional work would be required to fully develop the approach and to analyze where thesystem could be optimized. This process would involve the following steps:


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Evaluate the firefighting needs in each area

Develop system criteria

Analyze hydraulics and develop the backbone system

Define the PWSS requirements

The analysis would be conducted together with development of a condition assessment andlong-term pipe replacement program. The data from the optimization process would helpdefine how much pipe would be replaced and where.

Expansion of the AWSS Service Area

Although the AWSS was constructed primarily to supplement the domestic system in anearthquake, it is also used frequently during non-earthquake conditions. In the event ofgreater alarm fires (two or more alarms) the AWSS hydrants are generally tapped if they areavailable. It is estimated that the AWSS has been used as frequently as 30 times a year.

As shown in Figure ES-1, the AWSS primarily covers the north east portion of the City. Thiswas the most developed portion of the City in 1913. Since then, the western and southernportions of the City have fully developed. But, these areas do not have a similar level ofAWSS coverage as the downtown area. The prevalence of wood construction, moderate tohigh population density and moderate to high building values in the western and southernportions of the City warrant consideration of expanding the AWSS service area. Furtherevaluation of AWSS expansion needs may be conducted concurrently with optimization ofthe existing system.

The SFPUC is planning to construct facilities to treat and deliver recycled water tocustomers on the west side of San Francisco. There may be opportunities to save costs bycoordinating the construction of recycled water and AWSS pipelines. Where it is feasible toconstruct these pipelines along the same alignment and at the same time, costs may bereduced by up to 25%. Other coordination opportunities between these two projects wereidentified, including supplying recycled water to the AWSS and use of the AWSS todistribute recycled water. These other opportunities require much more evaluation and willbe evaluated further in future phases of the Recycled Water Program.

Recommendations:

The recommendations of this study are presented below in three main areas, in order ofpriority:

1. Rehabilitation of existing facilities2. AWSS pipelines3. AWSS expansion


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1. Rehabilitation of Existing FacilitiesRehabilitate/replace pump stations, tanks and reservoir to bring them to a state of goodrepair and ensure that they will be operational after an earthquake. Table ES-3 lists theneeded improvements and planning-level cost estimates.

TABLE ES-3. IMPROVEMENTS TO EXISTING FACILITIES

Facility Needed Improvement Cost Estimate(Planning-Level)

Ashbury Tank Replace tank and pump station $10,900,000

Jones Street Tank Replace tank and retrofit building $10,200,000

Twin Peaks Reservoir Perform dive inspection and replacereservoir liner if needed $11,400,000

Pump Station No. 1Retrofit basement slab and floor supportsReplace all mechanical and electricalequipment

$29,700,000

Pump Station No. 2 Replace pump station $16,100,000

Fireboat Headquarters Replace Pier and Building (Phase II) $8,400,000

Total $86,700,000

2. AWSS Pipelines:There are several recommended actions related to the AWSS pipelines. Therecommendations are described below and the estimated costs are shown in Table ES-4.

Evaluate optimal configuration of the AWSS pipe network.This evaluation would involve evaluating the firefighting needs throughout the City,developing system criteria, analyzing the hydraulics of the system and defining thebackbone pipe network. Development of a hydraulic model of the system as the primaryanalytical tool should be included in this work.

In the optimized system, the PWSS would play an integral part in providing AWSScoverage. Therefore, identifying needs and expanding PWSS capability is included in thisrecommendation. Following the Loma Prieta earthquake, the SFFD responded to theMarina District fire using the PWSS. In the event of a major earthquake in the Bay Area,multiple fires may occur and require simultaneous response using PWSS equipment. Ifanalysis shows that additional PWSS equipment is needed, funding should be secured topurchase additional hose tenders and associated equipment. PWSS may serve as an interimreadiness measure prior to expansion of the AWSS to the western and southern areas of theCity.


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The result from the optimization should be a plan that defines a backbone system that meetsthe City’s needs through the planning horizon. The plan will provide input to the long-termpipe repair/replacement program.

Implement a pipeline condition assessment and repair/replacement program. Thisprogram should include the following elements:

- Field testing plan that includes investigations such as inspection, ultrasonic wallthickness measurement, corrosivity testing and pressure testing.

- Analysis of field data to assess condition of pipelines in terms of serviceability,remaining useful life and replacement priority

- Funding for long-term pipe repair/replacement. The amount of annual funding willdepend on the results of the field investigations and the definition of the optimizedpipe network.

Implement an emergency pipeline repair, readiness and response program. This programwould increase the capability of the SFFD to quickly restore AWSS pipelines to service afteran earthquake. The program may be modeled after similar programs developed by theSFPUC for the City’s potable water system. The program should include:

- Development of emergency pipe break response procedures- Stockpile of pipe and fittings- Establishing emergency access to equipment and resources to quickly effect repairs.

Implement initial phase of pipeline replacements. This program should includereplacement of the pipelines adjacent to those above ground facilities that are replaced orretrofitted. This improves the reliability of the connection between these new facilities andthe rest of the pipe network.

TABLE ES-4. PIPELINE IMPROVEMENT RECOMMENDATIONS

Improvement Component Planning-level CostEstimate

AWSS Pipe Network Optimization- Develop Hydraulic Model- Optimization Analysis

$250,000$500,000

Condition Assessment and Repair/ReplacementProgram- Allowance for Field Testing- Analyze Field Data- Develop Repair/Replacement Program

$1,000,000

Develop Emergency Repair, Readiness, and ResponseProgram

$150,000

Pipeline Replacements Phase 1 - Initial phase of pipeline replacements - Replace pipelines adjacent to newly constructedfacilities

$11,400,000


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Total $13,300,000

3. AWSS Service Area Expansion:Further evaluate the need to extend AWSS pipelines to the west and south sides of the City.Because of the development that has occurred in these areas, they present a high risk of lossand may require a level of fire protection similar to the northeastern part of the city. Initialalignments for pipeline extensions have been proposed in previous studies. Table ES-5presents the cost estimates for these initial expansion concepts. Further evaluation ofexpansion needs should be performed together with the optimization effort, to be consistentwith the goal of streamlining the system and increasing fiscal sustainability,.

TABLE ES-5. AWSS EXPANSION AREAS AND COSTS

Expansion Area Cost Estimate

Westside Extension

Sunset Pipeline Extension $ 94,490,000

Richmond Pipeline Extension $ 62,370,000

New Westside Storage Tank $ 9,950,000

New Westside Pump Station $ 8,740,000

New Saltwater Pump Station $ 23,060,000

Southside Extension

Silver Avenue Pipeline Extension $ 56,220,000

Hunter's Point Pipeline Extension $ 52,460,000

Bayshore Pipeline Extension $ 13,160,000

New Southside Storage Tank $ 11,860,000

Total AWSS Expansion $ 332,400,000


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1

1.0 Introduction

1.1 BackgroundThe 1906 San Francisco earthquake (Magnitude 8.3) is considered to be one of the mostsevere earthquakes in recent history. Approximately 80 percent of San Francisco’s(City’s) total loss was caused by the fires following the earthquake (ATC, 2005).Separate major fires broke out at several locations to become a large conflagration,engulfing the northeast quadrant of the City (Figure 1-1).

The earthquake and fire resulted in approximately 3,000 deaths and destroyed about28,000 buildings. The total estimated property loss was approximately $524 million in1906 dollars (Scawthorn et al., 2006). The National Fire Protection Association hasestimated the fire losses to be $7.8 billion in 2006 dollars (NFPA, 2007). The domesticwater system was severely damaged, sustaining more than 300 breaks on water mainsand 23,000 breaks on service connections. There was virtually no water available forfirefighting. Approximately 50 fire events occurred throughout the city, mostly in thedowntown. When the fire was finally extinguished several days later, almost all of thedowntown was destroyed (Figure 1-1).

A study was conducted in 1908 to evaluate the need for a dedicated water system for firefighting in the City. Due to the high seismic risk in the San Francisco Bay Area andvulnerability of the domestic water system, City leaders approved the construction of anindependent fire protection system, known as Auxiliary Water Supply System (AWSS).The AWSS is a high pressure water supply system consisting of pipelines, reservoir andstorage tanks and saltwater pump stations. Construction of the AWSS was completed in1913 (SFFD, 1996) at a cost of $5.2 million in 1908 dollars.

The original AWSS construction provided additional level of fire protection to the highlydeveloped northeast portion of the City including downtown. Subsequently, the AWSShas been expanded and improved through several Bond measures. At nearly 100 yearsold, its physical condition is deteriorating and it is in need of replacement and/orrehabilitation.

1.0 INTRODUCTION


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FIGURE 1-1: CITY OF SAN FRANCISCO 1906 EARTHQUAKE BURNED AREA

1.2 PurposeThe purpose of this study is to identify the system deficiencies and assess the need forexpanding the system to the west and south side of the City. The primary objectives ofthis study are to:

Evaluate the added benefits provided by the existing system and determine theneed for continuing operation and maintenance of the system in the future.

1.0 INTRODUCTION


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Assess the current condition of AWSS facilities and identify improvements includingreplacement and/or rehabilitation.

Evaluate the need to extend the AWSS into areas of the City where AWSS is notavailable.

Develop an implementation strategy for the system improvements and expansion,and indentify potential funding needs to include in the 2009 Bond Issue.

1.3 Project ScopeThe scope of this study includes the following main tasks:

Assess the current usage and need for the existing AWSS system. Evaluate thegeographic coverage of the system and the need to expand to other areas of theCity.

Perform a condition assessment of the existing AWSS facilities, and defineimprovements required to bring the existing AWSS to a state of good repair.

Estimate cost of rehabilitation and expansion of the AWSS, and develop animplementation strategy.

1.4 Water Supply Sources Available for Firefighting in SanFrancisco

Presently, the water supply sources available to the SFFD for firefighting include: thelow pressure domestic water system operated by the San Francisco Public UtilitiesCommission (SFPUC) and the AWSS and the Portable Water Supply System (PWSS)operated by the San Francisco Fire Department (SFFD).

1.4.1 Low Pressure Domestic Water System

The San Francisco Public Utilities Commission supplies potable water to meet thedomestic water needs of the city and provides the primary supply for fire fighting.Water is supplied through the domestic distribution system at a pressure that typicallyranges from 50 to 70 psi. Water from the domestic system is provided for firefightingvia hydrants (with white tops) on the distribution mains.

1.4.2 Auxiliary Water Supply SystemThe AWSS is an independent system owned and operated by the SFFD exclusively forfirefighting. Water stored in one reservoir (Twin Peaks Reservoir) and two tanks(Ashbury and Jones Street tanks) is supplied at a high pressure of up to approximately

1.0 INTRODUCTION


4

300 psi via hydrants with black, red, or blue tops. The colors of the hydrant’s toprepresent the location of the hydrants in three distribution zones of the AWSS. Othercomponents of the AWSS, which are described in more detail in Section 2, includecisterns, salt water pump stations and fire boats. The pump stations and fire boatssupply saltwater from San Francisco Bay. Where it is available, the AWSS is the backupto the domestic water system, providing additional fire protection to City businessesand residents.

1.4.3 Portable Water Supply System

The Portable Water Supply System (PWSS), developed in the 1980s, is an above groundlarge diameter hose system used to supply water for greater distances from a watersource to where it is needed. The water source can include fireboat, cisterns, open waterbodies such as Lake Merced, or domestic system and AWSS hydrants. A hose tendertruck carries approximately 5,000 feet of 5-inch hose, portable hydrants and variousvalves and fittings. The PWSS is the second redundancy in terms of fire suppressioncapability.

1.4.4 Deployment of Water Supply Sources

The water supply that is used will vary with each fire event. However, supplies that canbe deployed most quickly are typically used first. This is because initially, rapidresponse is needed to prevent fire spread. Additional water supplies are subsequentlycalled upon depending on the flow and pressure needs of the fire. Figure 2-1 illustratesthe water supplies available for fighting fires.

Engines may carry up to 500 gallons of water on board. This source is often used firstbecause hoses can be quickly connected directly to the engine. This source may also bethe closest to the fire. The on-board storage provides an immediate but very shortduration supply while hoses are connected to the domestic system.

The domestic system hydrants are typically tapped next. Hoses connected directly tohydrants may be used to put water on the fire or to replenish an engine’s on boardsource. The domestic supply represents a reliable extended duration supply.

Should higher flow and/or water pressures be needed, such as for aerial operations, theAWSS would be used where available. Additional steps and more time are required todeploy the AWSS. Additional valving at the high-pressure hydrants as well asattachment of a pressure reducing Gleeson valve and associated fittings are needed toconnect hoses to the AWSS supply. The AWSS is also a reliable extended durationsupply. The system contains approximately 11 million gallons of storage which can bereplenished on a continual basis using the domestic supply.

PWSS is used to extend the service range of the domestic system or AWSS as well asutilize other water sources. Other sources may include surface water such as ponds orlakes, water from the San Francisco Bay or cisterns throughout the City. PWSS hose is

1.0 INTRODUCTION


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deployed from a hose tender truck which must be called to the scene of the fire. LayingPWSS hose requires more time than standard hose because it is generally drawn fromthe back of the hose tender truck as it moves from the water source to the location of thefire. The size and weight of PWSS hose is also greater than standard hose. Engines maybe required at the beginning and end of the hose run to boost pressure and pumpswould be needed to draw water from open water sources. Because of the time requiredto set up the PWSS, up to 60 minutes from the time the hose tender is called to the scene,it may be implemented strategically, after more immediately available sources are used.

FIGURE 1-2: WATER SOURCES AVAILABLE FOR FIGHTING FIRES


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2.0 Existing AWSS

2.1 System DescriptionThe existing AWSS is a gravity system that consists of high pressure water mains andhydrants, a storage reservoir, tanks, emergency saltwater pump stations, fireboats andcisterns (Figure 2 1). The AWSS has four water supply sources:

1) Water supply for the existing AWSS is provided by the Twin Peaks Reservoirand Ashbury and Jones Street tanks. These facilities are located at higherelevations in the city and pressurize the entire AWSS distribution system bygravity.

2) Two saltwater pump stations, located on the San Francisco Bay side can pumpbay water directly into the distribution system and AWSS storage tanks.

3) Two fireboats, anchored at Pier 22 ½ can supply bay water to City’s east sidewaterfront, to the AWSS distribution system via five manifolds located along thebay and to PWSS hoses.

4) Approximately 177 underground cisterns located throughout the city (Figure 2-1)can also be used as an emergency water source. Cisterns are not connected to thepiping system and water must be pumped from them using engine pumpers.

Another system, the PWSS, can also provide water for firefighting. This system is notconsidered part of AWSS, however, the SFFD can use it as second line of defense. ThePWSS is an above ground portable system consisting of large diameter hoses, pressurereducing valves and portable hydrants. The PWSS can be used to transport water overlong distances when pipelines are not available.

The existing AWSS is divided into two zones, the Lower Zone and the Upper Zone(Figure 2-2). The lower zone comprises the AWSS components and city areas locatedbelow 150-ft elevation including saltwater pump stations, fireboats, manifolds, and otherdistribution system components. The upper zone comprises the AWSS components andcity areas located above the 150-ft elevation, including Twin Peaks Reservoir, AshburyTank, Jones Street Tank, and other distribution system components. The two zones areisolated by eight gate valves. Under normal operations, Jones Street Tank serves thelower zone and Ashbury Tank serves the upper zone. Twin Peaks Reservoir canpressurize both zones when needed.

The AWSS facilities and the PWSS are discussed in further detail in the followingsections:

2.0 EXISTING AWSS


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FIGURE 2-1: EXISTING AUXILIARY WATER SUPPLY SYSTEM

2.0 EXISTING AWSS


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FIGURE 2-2: SCHEMATIC OF AUXILIARY WATER SUPPLY SYSTEM COMPONENTS

Source: City and County of San Francisco, 2008

2.1.1 AWSS Facilities

The primary water storage facilities of the AWSS are Twin Peaks Reservoir, AshburyTank, and Jones Street Tank. The saltwater pump stations, fireboats and suctionconnections can be used to supply Bay water when the primary storage is exhausted orbecomes unavailable.

2.0 EXISTING AWSS


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Twin Peaks Reservoir

Twin Peaks Reservoir, constructed in 1911, is the primary water supply source for theAWSS. This is a 10.5 million gallon storage reservoir located on Twin Peaks at MarviewDrive at an elevation of approximately 760 feet. The reservoir bottom is lined with 6-inch thick reinforced concrete.

The reservoir is divided into two equal bays, east side and west side. The two bays areisolated from each other to prevent the loss of the entire storage volume. This reservoiris supplied with potable water via a 6-inch connection to the City's domestic system.Two 20-in. outlet pipes lead from the reservoir to the distribution system. Two newmotorized control valves were installed at the reservoir in 2005 to control the outflow.The drainage or overflow pipe from the reservoir discharges to a nearby sewer to thesouth of the reservoir.

A Supervisory Control and Data Acquisition (SCADA) system is installed at thereservoir to check the water level in the reservoir and control the outflow. The reservoirwater level is observed by the SFFD staff daily and filled manually.

Twin Peaks Reservoir can fill both Ashbury and Jones Street tanks but under normaloperation only Ashbury Tank is filled by the reservoir weekly.

Ashbury Tank

Ashbury Tank, constructed in 1911, is located at the intersection of Clayton Street andTwin Peaks Boulevard. It is a 500,00 gallon circular tank constructed of riveted steel.The base of the tank is at an elevation of approximately 450 feet and supplies water toareas of the City that are above the 150-foot elevation. This tank is normally filled fromTwin Peaks Reservoir but can also be filled via an 8-in connection to the City’s domesticwater system. The tank is typically filled to its highest level (28-ft) on a weekly basis.

Two multi-stage turbine pumps at this facility may be used to fill Twin Peaks Reservoirfrom Ashbury Tank. An emergency diesel engine generator is also provided to powerthese pumps during power outage situations.

Jones Street Tank

Jones Street Tank, constructed in 1911, located on Jones Street between Clay andSacramento streets. It is a 750,000 gallon circular reinforced concrete circular tank. Thebase of the tank is at appoximately 330 feet elevation and supplies the lower zone, below150 feet.

This tank can be filled by the domestic water system via an 8-in. line. A hydraulicallyoperated altitude valve controls the filling operation. The tank is connected to thesystem through two 18-in effluent pipes and outflow is controlled through two manualdischarge valves. This tank has SCADA system for water level, and is typically filledevery day up to approximately 31-ft level.

2.0 EXISTING AWSS


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A control building adjacent to the Jones Street Tank houses the inflow and outflowcontrol valves, and discharge valves to Ashbury Tank. Motorized valves throughout thesystem can be remotely operated from this facility.

Pump Station No. 1

Two emergency saltwater pump stations, Pump Station No. 1 and Pump Stations No. 2can be used to supply water from San Francisco Bay to the AWSS.

Pump Station No. 1, built in 1911, is located in the basement of the SFFD Headquarterson the corner of 2nd and Townsend streets. The SFFD Headquarters building was builton top of the existing Pump Station No. 1 floor in 1998.

The pump station contains four diesel-driven pumps, each with a pumping capacity of2,700 gallons per minute (gpm) at 300 psi. Approximately 1,100-foot concrete intaketunnel located underneath the pump station floor and runs along the Townsend Street,conveys seawater from the Bay to the pumps. This pump station is manually operated.A backup generator powers the electrical systems at the pump station in the event of apower outage. The pumps were originally steam powered but were converted to dieselin 1970’s.

Pump Station No. 2

Pump Station No. 2 pumps saltwater from the San Francisco Bay to the AWSS. PumpStation No. 2 is located at the foot of Van Ness Avenue near Fort Mason.

This pump station also contains four diesel-driven pumps, each with a pumpingcapacity of 2,700 gallons per minute (gpm) at 300 psi. Approximately 160-foot concreteintake tunnel located underneath the pump station floor conveys seawater from the Bayto the pumps. A backup generator powers the electrical systems at the pump station inthe event of a power outage. The pumps were originally steam powered but wereconverted to diesel in 1970’s.

This pump station connects directly to the Ashbury Tank and Jones Street Tank.However, the connection from the pump station to the Ashbury Tank is normally closed,and the connection to the Jones Street Tank is normally open.

Fireboats

The SFFD has two fireboats, the Phoenix (built in 1954) and the Guardian (built in 1950).The fire boats assist with fire suppression in several ways. They can suppress fires onthe eastside waterfront by directly applying water to fires through their nozzles. Theycan pump bay water into the AWSS distribution system via manifolds along the bayside. Additionally the fireboats can pump bay water into a PWSS hose line. The Phoenixhas three pumps with pumping capacity of 9,600 gpm at 150 psi. The Guardian has fivepumps with pumping capacity of 24,000 gpm at 150 psi. Both fireboats are stationed atPier 22 ½ near Embarcadero and Harrison Streets. The motorized control valves of theAWSS can be remotely operated from the fireboats using laptop computers.

2.0 EXISTING AWSS


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Bay Suction Connections

SFFD has fifty-two suction connections along the eastside waterfront of the city. Fireengines can connect to these suction connections to draft bay water and serve thewaterfront area.

2.1.2 High Pressure Distribution Piping SystemThe AWSS high pressure distribution piping system is a network of specially designeddistribution mains, approximately 1,900 high pressure hydrants and gate valves.

Distribution Mains

The existing AWSS pipeline network consists of 135 miles of 8 to 20-inch cast and ductileiron pipe. Pipes installed prior to 1960s consist of special extra-heavy pit cast iron belland spigot pipe. The joints are special double-beaded lead construction. Double-spigotpipe with cast sleeves are used in specific areas of poor soil and artificial fill. Restrainingrods and longitudinal bolts are installed across joints at all turns and other points ofstress to resist joint pullout.

Beginning in 1960’s, standard specification was changed to ductile iron pipe with push-on rubber-gasket joints. Ductile iron was selected for its improved strength, ductilityand durability. Rubber gasket joints are easier to install and provide improved leakageprotection and joint flexibility. Bolts and tie rods are now specified in stainless steel toprovide high corrosion resistance.

High Pressure Hydrants

The AWSS hydrants with three 3.5-inch male threaded outlets are designed to supply sixlarge hoses. Due to the high pressure in the system, these hydrants provide higher flowat a greater reach without using a pumper engine. If the system pressure is too high, apressure reducing valve may be secured to the hydrants before connecting the hose.

Valves

Isolation gate valves are located throughout the system and are used to isolate portionsof the AWSS in the event of damage. These isolation gate valves can be operated via atruck mounted actuator. Additionally, the 1986 Bond provided funding to motorize andenable remote operation of 34 of these isolation valves, mostly in the infirm soil areas(SFPUC, 2003).

Remote operation allows SFFD to close valves much more quickly in response to pipebreaks. In an emergency such as an earthquake, this will reduce the loss of stored water.Remotely operated valves are monitored and operated from the Jones Street Tankcontrol building, and can also be operated from the SFFD Headquarters and fireboats.

2.0 EXISTING AWSS


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2.1.3 Underground CisternsCisterns are small underground water storage tanks. There are 177 cisterns, mostlylocated in the northeast quadrant of the City. Those installed in the late 1800’s and early1900s were constructed of brick, while a majority of the later construction is ofreinforced concrete. The storage volumes of the cisterns range from approximately75,000 gallons to 200,000 gallons. There are no pipe connections to cisterns. To use thewater, it must be pumped from the cistern using an engine pumper. Water levels in thecisterns are checked periodically and they are filled manually, usually with water from anearby low-pressure hydrant. Cisterns are the last water resource of SFFD.

2.1.4 PWSS

The Portable Water Supply System (PWSS) was implemented in the 1980s. This systemprovides additional fire protection capability in the City and is valuable for the SFFD. Itis an above ground mobile water supply system that can provide water to any locationwithin one mile of a water source.

PWSS unit includes a hose tender carrying approximately 1 mile of 5-inch diameter hosesystem and portable hydrants and pumps, and other accessories. The portable pump ofthe system can pump water from any water bodies such as various lakes and ponds in theCity, bay water or from the cisterns and fireboats or domestic water system and AWSShydrants.

2.2 System OperationsDuring the normal operations, the two AWSS zones operate independently to providewater supply for firefighting. However, these zones can be connected to provide waterfrom the upper zone to the lower zone.

The lower zone is supplied by the Jones Street Tank (elevation 330 ft) which pressurizesthe lowest elevation water mains (i.e. city’s east and southeast bay side) up to a staticpressure of approximately 140 psi. Ashbury Tank (elevation 450 ft) supplies the upperzone.

If higher pressure is required in the lower zone, eight gate valves located at Jones StreetTank are opened, and Ashbury Tank is connected to the lower zone. This increases thepressure in the lower zone to approximately 200 psi. If even more pressure is required,the Twin Peaks Reservoir can be connected to the lower zone to increase the pressure toapproximately 330 psi. Twin Peaks Reservoir can also supply the upper zone whenneeded.

If the Twin Peaks Reservoir and/or Ashbury and Jones Street tanks exhaust or fail oradditional water is required, one or both of the saltwater pump stations can be used topressurize the system, supply bay water to the distribution system and fill Ashbury andJones Street tanks. Additionally, if saltwater pump stations are not available or

2.0 EXISTING AWSS


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additional water is required, the fireboats can pump into the AWSS distribution systemvia connection to the five manifolds. Approximately 52 suction connections located onthe eastside waterfront allow engine pumpers to draw water directly from the bay.When necessary, water can be pumped from the cisterns to serve firefighting needs of anarea around the cisterns.


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3.0 Usage and Needs of Existing AWSS

3.1 Non-Earthquake ConditionsThe AWSS is generally used for day-to-day greater alarm incidents and for someworking fires, if the incidents occur within the AWSS service area. The AWSS is able toserve an area that extends approximately 1,000 feet to either side of the pipelines.

Figure 3-1 shows the locations of the greater alarm fires (2 through 5-alarm) in the Cityfrom 2002 through 2007 (San Francisco Department of Emergency Management).Approximately 250 greater alarm fires were logged during this 6-year period, or anaverage of 41 per year. Of these, approximately 190 greater alarm fires were within theservice area of the AWSS (Table 3-1), or an average of 32 per year.

This estimate reflects significant AWSS utilization during day-to-day firefightingoperations. It shows that the AWSS could be used in approximately 75% of the greateralarm fires within San Francisco. This estimating method was used because records ofAWSS usage were not available at the time of this study.

TABLE 3-1: AWSS USE FOR GREATER ALARM FIREFIGHTING

Year Number Of Greater AlarmIncidents

Estimated Number Of GreaterAlarm Incidents Within AWSS

Service Area2002 55 382003 34 302004 42 362005 47 362006 34 252007 34 26Total 246 191

Average/year 41 32

3.0 USAGE AND NEEDS OF EXISTING AWSS


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FIGURE 3-1: GREATER ALARMS INCIDENTS FOR 2002 TO 2007

3.2 Post-Earthquake ConditionsThe need for the AWSS following an earthquake is dependent on several factors to bediscussed in this section, including:

The likelihood that a large earthquake will occur in the future

The likelihood and severity of fires following a large earthquake

The need for the AWSS in fighting post-earthquake fires. This is dependent onthe anticipated ability of the domestic water mains to provide water immediatelyfollowing an earthquake.



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3.2.1 Probability of Future EarthquakesThe United States Geological Survey (USGS) conducted a study in 2003 that estimated a62 percent chance of a magnitude 6.7 or greater earthquake in the San Francisco BayArea before 2032. According to the study, the next large earthquake can strike at anytime, and would likely be centered in a populated urban area between San Jose andSanta Rosa on either side of the Bay (USGS OFR 03-214). Figure 3-2 shows themagnitudes of past earthquakes in the Bay Area and probability of a large earthquake inthe future. Put in perspective with recent earthquakes, this represents a high probabilityof an earthquake similar to or greater than the 1989 Loma Prieta event occurring close toSan Francisco in the next 24 years.

FIGURE 3-2: PROBABILITY OF FUTURE EARTHQUAKES IN THE BAY AREASource: (USGS, 2003)



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3.2.2 Post Earthquake Conflagration Potential

A conflagration is a fire with the potential to rapidly spread to adjoining areas andstructures. Conflagration is an important concern in San Francisco because of itslocation in a seismically active region and the prevalent wood building constructionthroughout the City. A number of studies and simulation models have been developedto determine the potential for conflagration following an earthquake. The followingstudies were reviewed to determine the conflagration potential in San Franciscofollowing a strong earthquake.

Modeling of Fire Following Earthquake. (Scawthorn, 1986)

Fire Following Earthquake – Conflagration Potential in the Greater Los Angeles,San Francisco, Seattle and Memphis Areas. (Scawthorn,1992)

San Francisco’s Earthquake Risk – Draft Report on Potential Earthquake Impactsin San Francisco, (ATC, 2005)

Earthquake Engineering Handbook, CRC. (Scawthorn, 2003)

Emergency Planning for Earthquake Safety (Eidinger, 1996)

Potential Number of Fires

Scawthorn (1986) estimated the number of fires for various earthquake scenarios on theSan Andreas fault with epicentral distance of 8 miles from downtown San Francisco.Table 3 2 shows the number of fires for these earthquake scenarios ranging frommagnitude 5.3 to 8.3.

TABLE 3-2: NUMBER OF FIRES ESTIMATES DUE TO SAN ANDREAS FAULT EARTHQUAKES

San Andreas Fault Earthquake Magnitude No. of Fires

5.3 16.0 46.5 127.0 237.5 328.3 40

Source: Scawthorn (1986)

In a subsequent study, Scawthorn (2003) estimated the number of fires as a function ofearthquake shaking intensity on the Modified Mercalli Intensity scale (MMI). The



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number of fires ranged from 13 for MMI 6 (moderate shaking, objects fall from shelves,but no structural damage) to 51 fires for MMI 9 (violent shaking, significant damage tobuildings, damage to underground utilities). At the upper range of estimated number offires, a study performed by FEMA (2006) estimated that there may be up to 100 fires inthe City as a result of a repeat of the 1906 San Francisco Earthquake.

Potential for Fire Spread and Structures Burned

The growth and spread of fires following earthquake is a function of building materials,density, street width, wind, water supply, and firefighting operations. Scawthorn (1992)estimated fire growth and spread as a function of one of these factors, wind speed. Fortypical dense residential development, 10 to 15 buildings may be consumed by fireunder calm wind conditions (0 mph) 20 minutes after initial spread. At 10 mph windconditions, total buildings burned increases to 20 to 25. This represents a high potentialfor spread and could lead to conflagration after an earthquake. Scawthorn (1986)estimated that if an earthquake larger than magnitude 6.5 occurred on the San Andreasfault near the City of San Francisco, fires could become uncontrollable in the initial 24 to72 hours. Should a magnitude 7.8 earthquake occur on the north San Andreas Fault, it isestimated that fire damage in San Francisco could be $5.9 billion in 1992 dollars(approximately $8.5 billion in 2006 dollars), or 6% of the City’s property value.

3.2.3 Reliability of the Domestic Water SystemThe SFPUC is currently seismically upgrading the domestic water system. Pumpstations, tanks, reservoirs and critical transmission pipelines are being replaced orretrofitted to improve their reliability in the next major earthquake. These types offacilities often require significant time and resources to restore when they fail after anearthquake. Therefore, improving these facilities now maximizes seismic reliability andsignificantly improves the recovery capability of the domestic system.

By their nature, domestic water mains are more vulnerable to earthquake damage.Numerous service connections and the jointed construction that is the industry normcontribute to their vulnerability. However, as demonstrated following the Loma Prietaearthquake, the SFPUC is able to make numerous water main repairs and restore waterto its customers in the days following an earthquake.

Fire suppression will be critical immediately following an earthquake. Because theAWSS pipes are designed to overcome some of the vulnerabilities of standarddistribution piping, it is more likely that they will be serviceable after an earthquake.The design features which strengthen them against seismic forces include fewerbranches and service connections as well as restrained joints.

A high-level seismic vulnerability assessment was performed on the distribution mainsin the domestic system. Pipeline data including diameter, length and material was usedtogether with seismic fragility curves to estimate the number of pipe breaks that mayoccur after a major San Andreas earthquake. The analysis accounted for both groundshaking and liquefaction hazards.



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The fragility curves are based on break rate data from historical earthquakes. Themethods used to estimate pipeline damage were developed by seismic/pipeline expertsand are commonly used for seismic analysis. The methods and fragility data were fromASCE (1999), ALA (2001), FEMA (1999) and O’Rourke (2004). The analysis was appliedto distribution mains 6 inch and greater in diameter. The results of the analysis indicatethat breaks on the domestic system following a magnitude 7.9 earthquake on the SanAndreas fault would impair the ability of the domestic system to deliver water to fightfires. In areas where the AWSS is available, a supplemental source of water could besupplied for firefighting.

3.2.4 1989 Loma Prieta EarthquakeThe 1989 Loma Prieta earthquake was the largest earthquake in northern Californiasince the construction of the AWSS in 1913. It was centered about 60 miles south of SanFrancisco in the Santa Cruz Mountains.

Following the earthquake, approximately 69 main breaks and 54 service connectionbreaks were documented on the domestic water system in Marina District. Additionalrepairs that were not documented may have also occurred. The repairs were spreadthroughout the area bounded by Marina Boulevard and Chestnut Street to the north andsouth and by Buchanan and Baker Streets to the East and West (USGS, 1992). The breaksin the system impaired the water pressure and flow to the domestic water systemhydrants. The AWSS sustained one leaking joint at Scott and Beach Street (USGS, 1992).Several other breaks occurred in other parts of the AWSS system, including one majorbreak in a 12-in AWSS main on the south of Market Street. These breaks resulted indepletion of Jones Street Tank within approximately 15 minutes, and loss of pressure inthe lower zone.

Due to inadequacy of communications systems and the valving capability, AshburyTank, Twin Peaks Reservoir and the saltwater pump stations were not used to re-pressurize the lower zone. After the broken main was isolated, the lower zone was re-pressurized several hours later using the saltwater pump stations.

Meanwhile, a large fire in the Marina District continued to grow due to the lack of water,to the point where an entire city block was threatened (Scawthorn, 1992). The PWSS wasdeployed, fed by the Fireboat Phoenix, to supply the water to fight the fires. The fireboat supplied over 6,000 gpm for approximately 18 hours until the fires were controlled.The estimated damage from this fire was approximately $7.4 million (1989 dollar value)(Scawthorn, 1992).

The events of the Loma Prieta earthquake illustrate several points regarding the need forthe AWSS following a major earthquake in the future:

The domestic system pipes will sustain damage in certain areas of the City,which will impair the ability to deliver water for fire fighting.



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Due to the design features of the AWSS, it is likely to be more serviceable after anearthquake. However, it may still sustain some damage after an earthquake.

Multiple redundancies in fire water supply system are necessary. In the LomaPrieta earthquake, the third line of defense, the PWSS, and fireboat, weresuccessful in suppressing the fire in the Marina District.

4.0 WATER SUPPLY FOR FIREFIGHTING IN OTHER CITIES


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4.0 Water Supply for Firefighting in OtherCities

4.1 Water Supply for Firefighting in Other Cities

While the AWSS is often considered a unique system, various components of the systemhave been implemented by other cities. Like San Francisco, these other cities haveconsidered their seismic hazards, identified vulnerabilities in their fire water supplysystems, and have concluded that an auxiliary water supply is necessary to fight thefires following earthquakes.

A reconnaissance of several cities was performed to assess the prevalence of auxiliarywater supply systems. The cities were selected based on criteria including totalpopulation, population density and seismic hazard. The largest cities in California alongthe West Coast were selected. In addition, the City of Seattle, the largest city inWashington State and Vancouver, the largest City in the Province of British Columbia,Canada were also selected. Table 4-1 lists the cities considered and those contacted.

TABLE 4-1: CITIES CONTACTED REGARDING AUXILIARY WATER SUPPLY SYSTEMS

City Population RankingPop.

Density Contacted(pop./sq

mi)Los Angeles 4,045,873 (1) #1 in California 8,627San Diego 1,336,865 (1) #2 in California 4,126San Jose 989,496 (1) #3 in California 5,687San Francisco 824,525 (1) #4 in California 17,924Long Beach 492,642 (1) #5 in California 9,853Fresno 486,171 (1) #6 in California 4,675Sacramento 475,743 (1) #7 in California 4,905Oakland 420,183 (1) #8 in California 7,503Berkeley 106,697 (1) #60 in California 10,670Seattle 592,800 (2) #1 in Washington 7,075

Vancouver 611,869 (3) #1

in BritishColumbia,Canada 13,901

(1) 2008 estimate, California Department of Finance



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(2) 2008 estimate, State of Washington Financial Management Department

(3) 2007, BC Stats, central statistical agency of the Province of British Columbia

Los Angeles, California

The Los Angeles Fire Department (LAFD) in Southern California serves the greater LosAngeles area, with a service area population of approximately 4 million. The servicearea is highly urbanized, although the development is generally not as dense comparedto San Francisco. Population density is approximately 8,600 persons per square mile.This is considered moderate relative to the other cities surveyed and compared to thehigh density of approximately 17,900 persons per square mile in San Francisco. Theearthquake hazard in Los Angeles is similar to the San Francisco Bay Area. LAFD doesnot have any auxiliary water supply systems for firefighting, and relies solely on thecity’s domestic water system.

On January 17, 1994, a magnitude 6.7 earthquake occurred in the Northridge area. Theearthquake damaged lifelines such as gas, water, power and communication utilities aswell as local transportation systems. Approximately 77 fires were reported in the LAFDservice area. More than 70% of fires occurred in single- and multi- family residences(Scawthorn et al., 1998). Approximately 1,400 water system leaks, and damage to pumpstations and storage tanks resulted in lack of pressure in the hydrants in the west andnorth areas of the San Fernando Valley, forcing LAFD to use water tankers andalternative water supply sources including a number of swimming pools in the area.

San Diego, California

The City of San Diego in Southern California has a population of 1.3 million and adensity of 4,100 persons per square mile. The domestic water system is the only watersupply for fire fighting and no auxiliary supplies or infrastructure is in place. To ensureadequate volume for emergencies, raw water storage facilities are maintained at 60percent of annual usage.

San José, California

San José is located in the San Francisco Bay Area approximately 45 miles southeast ofSan Francisco. The population is estimated at 989,000 and population density isapproximately 5,700 persons per square mile. The San José Fire Department relies onthe domestic water system for firefighting. While no auxiliary water supplies orinfrastructure exist for fire, engines do have the ability to draft from open water bodiessuch as swimming pools, lakes or ponds if necessary.



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Long Beach, California

The City of Long Beach is located in Southern California and has a population of493,000. Its population density, approximately 9,900, is moderate compared to the othersurveyed. The City of Long Beach’s emergency auxiliary water supply system consistsof approximately 2 miles of emergency pipeline which may be deployed in the event ofservice interruption due to failure of the domestic system. The pipe is 5-inch diameteraluminum pipe that is portable and is used to bridge breaks by interconnecting firehydrants. This system is owned by the State of California but maintained by the LongBeach Fire Department. The Fire Department also maintains two fireboats, each with10,000 gpm capacity.

Oakland, California

The City of Oakland is located on the east side of San Francisco Bay approximately 10miles from San Francisco. Its population in 2008 is estimated to be approximately420,000. Like San Francisco, Oakland has many highly developed residential andcommercial areas, including a downtown area. Population density is low to moderate atapproximately 7,500 persons per square mile.

Shortly after the 1906 earthquake, Oakland constructed an auxiliary water supplysystem similar to that of San Francisco1 to reduce the risk of conflagration following anearthquake. This system covered 370 acres of the valuable business district in thedowntown area.

The main component of the system was a 2,000 gpm pump station located on the shoreof Lake Merritt and approximately 3.6 miles of pipelines. Pipes extended along 14th,Washington, Franklin, 2nd and Webster Streets, with the line along Webster extendingout to a fire boat manifold at the waterfront. The system was shut down at the time ofconstruction of Bay Area Rapid Transit (BART) through Oakland and was never putback in service. Many of the components had aged and deteriorated by that time andthe City of Oakland did not invest in renewal and ongoing operation and maintenanceof the system.

After the 1989 Loma Prieta earthquake, the City of Oakland once again saw the need todevelop an auxiliary water supply system. City of Oakland purchased an above groundPWSS similar to San Francisco’s PWSS in 1994. This system could provide water to alarge portion of downtown through a network of hoses, engines and fireboat. Oaklandcurrently has four hose wagons, each carrying over 5,000 ft of 5-inch diameter hose. ThePWSS has been used on several fire events, including a large six-alarm warehouse fire inwhich the water supply was limited and fire hydrants were too far away to be accessedby the fire engines.

1 Personal communication with Oakland Fire Department Historian, 4/29/08



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Berkeley, California

City of Berkeley, located on the east side of San Francisco Bay, has a population ofapproximately 106,000. Compared to many of the other cities surveyed, Berkeley’spopulation density of 10,700 persons per acre is relatively high. Due to the history ofwildland fires, high probability of earthquakes in the San Francisco Bay area, andpredicted failure of the municipal water supply system, the City of Berkeley planned anauxiliary underground piping and saltwater pumping system for fire protection in 1992.This system was not implemented for several reasons. The cost of the system wasdetermined to be more than the City of Berkeley could afford, communities opposed theproject due to various construction issues, and as conceived, the system only providedprotection to the lower elevations of the city and did not satisfy all of the firefightingneeds (City of Berkeley, 2007).

As an alternative to the buried piping system, a plan for the Mobile Disaster FireProtection System (MDFPS) was authorized and funded by a ballot measure in Fall 2000.The MDFPS would provide water for firefighting during a disaster event if the existingdomestic fire hydrants are inoperable or unable to provide adequate water supply forfire suppression. The MDFPS could provide coverage anywhere in the city. Studieswere performed to assess the number of fires that might occur after an earthquake, thefire volumes required and the expected damage to the domestic water system. Thisinformation supported the decision to implement the MDFPS.

The MDFPS will consist of four pump modules, each with a capacity of 6,000 gpm.Water will be transported via approximately six miles of ultra large diameter hose(ULDH) of 12 inches in diameter. Each module and hose system will be transported in alarge truck. Total cost of the system is estimated to be $4,700,000.

Seattle, Washington

The City of Seattle is located in western Washington. It has a population of 593,000 witha density of approximately 7,100 persons per square mile. This area of the State hasexperienced many significant earthquakes. More recently, on February 28, 2001, theM6.8 Nisqually earthquake struck the Puget Sound area in the western region of theState, approximately 60 km southwest of Seattle. The earthquake caused approximately$2 billion in damage. Most of the damage was due to strong ground shaking.Fortunately, there was only one fire following the earthquake. However, several waterlines were damaged, with one major break causing the depletion of a storage tank andlocal flooding (Filiatrault et al., 2001). The City of Seattle had relied solely on itsdomestic system for firefighting.

Following the 2001 Nisqually earthquake, and several strong earthquake events in otherparts of the world, City of Seattle realized the impact that a major earthquake may haveon its domestic water system. The city assessed their fire water supply system anddeveloped a fire water supply improvement project. In November 2003, votersapproved the Fire Facilities and Emergency Response Levy to fund enhancement to the



25

fire protection capabilities of the Seattle Fire Department. The program started in 2004and was to be completed over a nine-year period. Two water supply improvements andenhancement programs were included in the Levy program, Emergency FireSuppression Water Supply System, and the purchase of two new fireboats. TheEmergency Fire Suppression Water Supply System program consists of the followingprojects2:

Hardened hydrants were planned to be installed at city’s nine domestic waterreservoirs and one storage tank. The hardened hydrants are standard fire hydrantsthat are placed close to the reservoirs and upstream of service connections to reducetheir vulnerability in the event of an earthquake. In addition, these hydrants provideeasier access to the reservoir and allow drafting without contaminating the storedwater which would occurs when a pump or suction line is lowered into thereservoir.

All fire engines are to be equipped with light-weight hard suction hoses and floatingstrainers that allow drafting of water from water bodies such as lakes and PugetSound. In addition, all the fire engines are to be standardized with large diameterhose.

These projects will improve firefighting ability by providing sufficient water to thecritical areas and by increasing the capability of using water from any of the city’savailable water sources such as reservoirs, lakes, or saltwater. The cost of these projectswas estimated to be approximately $820,000.

The other alternative systems for providing fire water supply are an above-groundportable main system and fireboats. The portable above-ground water main system canprovide water from a source to a location up to approximately one mile away. Existingfireboats stationed in Elliott Bay and Lake Union can pump water to approximately 400feet from the waterfront.

The Seattle Fire Department has two existing fireboats. Under the Fire Facilities andEmergency Response Levy, the department will retrofit one fireboat, purchase twoadditional fireboats, and retire the older existing fireboat. The new fireboats will havepumping capacities of 22,000 gpm and 5,000 gpm. The retrofitted fireboat will have apumping capacity of 10,000 gpm.

Vancouver, British Columbia, Canada

The City of Vancouver, British Columbia in Canada has a population of 612,000. Thepopulation density of Vancouver is 13,900 persons per square mile, the highest of all ofthe cities surveyed and closest to San Francisco’s 17,900. The city is located in thesouthwestern corner of the district. As with San Francisco, Vancouver is subject tosignificant earthquake hazard. Following the 1989 Loma Prieta earthquake, the City ofVancouver evaluated the need to provide an auxiliary water supply for firefighting. Thedomestic water system in the downtown area was inadequate to meet fire flow

2 Personal communication with Seattle Fire Department, 4/22/2008



26

requirements. Potential solutions included improving the domestic system orconstructing a separate fire system. Construction of an independent fire protectionsystem supplied by saltwater pumping facilities was selected as the preferred solution.

The city’s Engineering and Fire and Rescue Services departments developed a DedicatedFire Protection System (DFPS). The system was modeled after San Francisco’s AWSS.Construction of Phase 1 of the system was completed in 2003 at a cost of $52M (CAD).The completed phase protects the downtown and neighboring residential areas ofVancouver.

As shown in Figure 4-1, the DFPS consists of a “backbone” pipe network ofapproximately 7 miles of pipeline and two saltwater pump stations. The combinedcapacity of the two pump station is approximately 20,000 gpm at high pressure (300 psi).The DFPS service area, shown by the light-green shading, extends several blocks toeither side of the pipelines. This provides coverage between and beyond the pipes in thenetwork, covering the entire downtown area as well as portions of the Fairview andKitsilano neighborhoods. This coverage is provided by a 5-inch diameter portable hosesystem that is capable of extending up to approximately 3,000 feet.

All of the facilities have been designed and constructed to remain operational followinga large earthquake. Facilities have multiple redundancies to ensure reliability. TheDFPS has been used to control multiple alarm fires during non-earthquake conditions aswell. An example in 2005 includes a four-alarm fire in the Kitsilano Neighborhoodwhich threatened an entire block of historical structures.

Ongoing emergency preparedness efforts related to water supply include investigationof additional drafting capabilities from lakes and rivers at other locations within the cityas well as expansion of the DFPS eastward from the current service area. A newdrafting station has been constructed on the Fraser River to allow fire engines to draftfrom the river.



27

FIGURE 4-1 : CITY OF VANCOUVER DEDICATED FIRE PROTECTION SYSTEM (DFPS) LAYOUT

Source: City of Vancouver

4.2 Summary

The issues and concerns regarding water supply reliability for fire fighting are shared byother cities along the western coast of North America which have similar earthquakehazards. The concept of developing a supplemental fire system to mitigate thesehazards is not unique to San Francisco. Several of the cities surveyed have consideredimplementing systems which range from permanent buried pipe networks to portable



28

hose systems. Some of the factors that affect municipal decisions to construct andmaintain auxiliary systems include financial resources, ability to provide adequategeographical coverage and community acceptance. Table 4-2 lists the cities contacted inorder of descending population density and summarizes the results of the survey. Thedata show that the population density of San Francisco is significantly higher than all ofthe other cities. The second most densely populated city, Vancouver, has an auxiliarypipe network as well as a portable hose system. The trend for the cities with moderate(Berkeley, Long Beach and Los Angeles) and lower (Oakland, Seattle, San José, and SanDiego) population densities do not appear conclusive. Some of these cities havesupplemental portable hose system, while others do not.

As recently as 2003, the City of Vancouver invested in an independent fire systemsimilar to the AWSS. In other cases, such as Oakland and Berkeley, portable auxiliarysystems were determined to better suit the financial and fire fighting needs of the city.One element, however, that the cities surveyed do not share with San Francisco is thehistory of a devastating post-earthquake fire. This history is a reminder of the potentialrisk and remains a consideration in the planning of fire systems in San Francisco.

TABLE 4-2: AUXILIARY WATER SUPPLY SYSTEMS OF OTHER CITIES

City PopulationPopulation

RankingPop.

Density

AuxiliaryPipe

Network

PortableHose

System(pop./sq

mi)San Francisco 824,525 (1) #4 in California 17,924

Vancouver 611,869 (3) #1

in BritishColumbia,Canada 13,901

Berkeley 106,697 (1) #60 in California 10,670Long Beach 492,642 (1) #5 in California 9,853Los Angeles 4,045,873 (1) #1 in California 8,627

Oakland 420,183 (1) #8 in California 7,503(no longer in

service)

Seattle 592,800 (2) #1 in Washington 7,075San Jose 989,496 (1) #3 in California 5,687San Diego 1,336,865 (1) #2 in California 4,126

(1) 2008 estimate, California Department of Finance

(2) 2008 estimate, State of Washington Financial Management Department

(3) 2007, BC Stats, central statistical agency of the Province of British Columbia



29

5.0 CONDITION ASSESSMENT OF EXISTING AWSS FACILITIES


30

5.0 Condition Assessment of Existing AWSSFacilities

5.1 Condition Assessment of Existing FacilitiesVisual site inspections of the AWSS facilities including Twin Peaks Reservoir, Ashbury andJones Street tanks, and Pump Stations No. 1 and No. 2 were performed to assess the currentconditions of these facilities. A high-level condition assessment and identification of neededimprovements was performed based on the site observations. Engineering analysis such asstructural calculations or field testing was not performed. The assessment of pipelines isbased on the age of pipelines and information from previous studies. The results of thecondition assessment are summarized in this section.

5.1.1 Twin Peaks ReservoirThe visual inspection was performed on the exterior structure of the reservoir, andassociated mechanical and electrical components. Internal conditions of the reservoirincluding the reservoir lining could not be inspected as the reservoir was full at the time ofinspection. Table 5-1 summarizes the major observations and suggested improvements.

Because most of the major components of the reservoir are below the water surface, aninspection of these components is needed. Since there are likely to be fire safety issuesassociated with draining the reservoir, a dive inspection can be considered. Due to theobserved daily drop in reservoir level, there are leakage concerns. Replacement of theconcrete reservoir lining may be required.

5.1.2 Ashbury TankThe visual inspection was performed on the tank exterior, and associated mechanical andelectrical components, and pump station building adjacent to the tank. Internal condition ofthe tank was not inspected. Table 5-2 summarizes the major observations and suggestedimprovements.



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TABLE 5-1: TWIN PEAKS RESERVOIR – OBSERVATIONS AND SUGGESTED IMPROVEMENTS

Observed Deficiencies Suggested ImprovementsStructural

Reservoir logs indicate that reservoirleaks approximately 1.5-in. per day.

The reservoir divider wall and baseslab/membrane integrity isunknown.

Concrete fence columns are crackedand portions of the steel fence aredeteriorated.

An isolation test should be run to evaluate theoccurrence of leaks.

Perform an inspection of the reservoir lining.Replace entire liner as necessary.

Replace fence columns and steel fence in itsentirety.

Mechanical

The top portion of the intake screenexhibits evidence of corrosion.Discharge pipe condition could notbe determined.

Perform detailed inspection of the dischargepipes and intake screens.

Geotechnical

Some tension cracks observed at thetop of the hillside are indicative ofsoil creep.

Subsurface drainage system couldnot be observed.

The need for permanent slope repair should beevaluated. A slope protection plan should bedeveloped and implemented.

Tracer tests or camera inspection should beused to evaluate the condition of thesubsurface drainage system.



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TABLE 5-2: ASHBURY TANK – OBSERVATIONS AND SUGGESTED IMPROVEMENTS

Observed Deficiencies Suggested Improvements

Structural

The tank appears unanchored to the ground.

Base plate has deteriorated significantly andhas been previously repaired with asphalt.

There is evidence of rust on the tank inseveral places.

Tank roof appears to be in poor condition.There is evidence that some of the roof hasblown off in the wind.

Pump station building does not meet currentseismic standards.

It is recommended that the tank andpump station building be replaced.

Mechanical

Pump equipment is very old.

Internal conditions of piping and valvescould not be determined.

Discharge lines at tank have rubberexpansion joints with a sheet metal covering.

Non-flexible couplings are used at pipeconnections to pumps and generators.

Replace pump equipment.

Inspect and replace the valves andpiping as necessary.

Inspect rubber expansion joints andreplace if necessary.

Replace with flexible couplings.

Electrical

The generator is old and shows sign ofrusting.

Replace generator based on testing andevaluation.

Overall the tank and associated components are considered to be beyond their useful lifefrom an age and condition standpoint. In addition, the tank and pump station building donot meet current seismic standards. Because the gain in service life is not likely to justify thecost of refurbishment and seismic retrofit, it is recommended that this facility be replaced.Interim measures to mitigate the seismic vulnerability of the tank may be investigated whilelong-term replacement planning progresses.



33

5.1.3 Jones Street TankThe visual inspection was performed on the tank exterior, and associated mechanical andelectrical components, and control building adjacent to the tank. Internal condition of thetank was not inspected. Table 5-3 summarizes the major observations and suggestedimprovements.

TABLE 5-3: JONES STREET TANK – OBSERVATIONS AND SUGGESTED IMPROVEMENTS


Structural

Internal condition of the tank is unknown.

The thin metal roofing is separate andappears to rest upon the top of the tank wall.

The tank wall to footing interaction isprovided by a key. This key appears to havebeen repaired with asphalt on the inside ofthe tank, which has seeped outside.

Maze cracking was observed throughouttank and site retaining wall.

Anchorage of generator components appearsto be inadequate.

SFFD staff stated that approximately 8-ft ofwater is lost per day from the AWSS.

Tank control building does not meet currentseismic standards.

It is recommended that the tank bereplaced.

Tank control building should beretrofitted to conform to the currentseismic standards.

Site retaining wall should be replaced.

MechanicalInternal condition of piping and valvescould not be determined.

Tank outlet has inflexible couplings.

Piping and valves should be inspected,and repaired or replaced if necessary.

Flexible couplings should be provided.Electrical

Diesel generator is old shows sign ofrusting.

Generator should be replaced.

Overall the tank and associated components are considered to be beyond their useful lifefrom an age and condition standpoint. Because the gain in service life is not likely to justifythe cost of refurbishment and seismic retrofit, it is recommended that tank and associatedcomponents be replaced. The control building is in need of seismic retrofit to conform to



34

current codes and standards. Interim measures to mitigate the seismic vulnerability of thetank may be investigated while long-term replacement planning progresses.

5.1.4 Pump Station No. 1The visual inspection of pump station building structure, and associated mechanical andelectrical components was performed. Table 5-4 summarizes the major observations andsuggested improvements.

TABLE 5-4: PUMP STATION NO. 1 – OBSERVATIONS AND SUGGESTED IMPROVEMENTS


StructuralThe internal condition of the tunnel couldnot be inspected. Deterioration of thestructural components including the floor,concrete above the tunnel, steel supports fortunnel were also observed.

Perform detailed inspection of thetunnel.Consider improvements such asconstructing a new tunnel within theexisting tunnel.

Anchorage of the equipment is inadequate. Replace anchor bolts for all equipmentas necessary.

Foundation deterioration is unknown.Pumps have settled approximately 3”-4” inplaces. There is a significant amount ofspalled concrete, and rusting at the baseplate of the pumps and engines.

Further investigation to determine thestructural integrity of the base slab isrequired. Required improvements mayinclude replacement of the base slaband floor support system.

Mechanical

The pumps, engines and all associatedequipment are very old.

It is recommended that all mechanicalequipment be replaced.

Engine exhaust piping passes through theceiling to the exhaust system on the firstfloor and to the roof. There have beencomplains about the exhaust smell.

The diesel exhaust system should beinspected for leaks and repaired.

Suction channel intake screen exhibitsignificant corrosion and debris.

Clean and inspect screens and replaceas necessary.

The diesel fuel tank, located below gradeoutside the building, could not be observed.

Perform inspection of the fuel tank andpiping and replace as necessary.

Electrical

Emergency generator shows signs of rusting. It is recommended that all electricalequipment be replaced. Testing shouldbe performed to confirm the conditionof any equipment or wiring that is notreplaced.



35

The mechanical and electrical equipment at the pump station appear to be well maintained.However these components have exceeded their useful life and are recommended forreplacement. The pump station building that serves as the SFFD headquarters has beenseismically retrofitted recently. However, it is unclear whether the basement and tunnelportions of the pump station were addressed in that effort. The foundation settlementproblems may indicate problems with the base slab, although additional investigation isrequired. Condition of the intake tunnel could not be determined but it is likely thatsignificant deterioration of the tunnel lining has occurred. Potential improvements mayinclude construction of a new tunnel wall within the existing tunnel.

5.1.5 Pump Station No. 2The visual inspection of pump station building structure, and associated mechanical andelectrical components was performed. Table 5-5 summarizes the major observations fromthe visual site inspections and suggested improvements required to bring the facility to anas-designed condition.

TABLE 5-5: PUMP STATION NO. 2 – OBSERVATIONS AND SUGGESTED IMPROVEMENTS

Observed Items Suggested Improvements

StructuralPump Station No. 2 appears to have similartunnel type/issues as Pump Station No. 1

See Pump Station No. 1

Anchorage of the equipment is inadequate. See Pump Station No. 1

The pump station building and westretaining wall exhibit cracking. The buildingdoes not meet current seismic codes andstandards.

An evaluation of the structural integrityof the retaining/building wall should becompleted

Replacement of the entire pump stationbuilding may be considered.

Several components in the basementincluding a concrete beam, steel supports,and a bearing wall have deteriorated.

Shore beam and install temporary barrierin surrounding area.

MechanicalThe pumps, engines and all associatedequipment are very old.


The diesel fuel tank, located below gradeoutside the building, could not be observed.


ElectricalEmergency generator shows signs of rusting. See Pump Station No. 1



36

The mechanical and electrical equipment at this pump station appear to be well maintained.However these components have exceeded their useful life and are recommended forreplacement. It appears that no seismic or structural improvements have been made to thebuilding since its construction. Structural components in the basement have deteriorated tothe point where their structural integrity has been compromised. Condition of the intaketunnel could not be determined but it is likely that significant deterioration of the tunnellining has occurred. Potential improvements may include construction of a new tunnel wallwithin the existing tunnel. Engineering evaluation will be required to determine the level ofstructural retrofit required. However, due to the current age of the facility, the gain inservice life must be evaluated against the cost of refurbishment and retrofit. It isrecommended that replacement of this facility be considered.

5.2 AWSS Pipelines5.2.1 Age and ConditionThe analysis in this section is based on review of previous corrosion studies and age profileof the AWSS pipelines. Inspection or testing information on the AWSS pipeline network isnot available, and field work is beyond the scope of this project.

General Construction

The original 77-mile AWSS pipeline network was constructed in 1913 and has since beenexpanded to 135 miles of 8 to 20-inch cast and ductile iron pipe. Of the 135 miles ofpipeline, approximately 103.5 miles are cast iron, 26.5 are ductile iron and the remaining 5.5miles are of unknown construction.

Age

Pipeline material and construction data were collected from the SFDPW GIS database. Thisdata was used to characterize the age of the AWSS pipelines. Figure 5-1 displays abreakdown of the lengths of pipeline by installation date, grouped into 5-year increments.The original 77 miles of cast iron pipelines are now approaching about 100 years in age.



37

Length of Pipelines - By Install Year

77.2

5.3

22.4

0.0 0.0 2.2 1.2 1.2 0.23.7

7.32.3 3.5

6.90.1 2.1

0

10

20

30

40

50

60

70

80

90

Pre-

1930

1931

-193

519

36-1

940

1941

-194

519

46-1

950

1951

-195

519

56-1

960

1961

-196

519

66-1

970

1971

-197

519

76-1

980

1981

-198

519

86-1

990

1991

-199

519

96-2

000

Unkn

own

Year Installed

Leng

th (M

iles)

FIGURE 5-1: AWSS PIPELINE AGE

Remaining Useful Life

According to the American Water Works Association (AWWA) (May 2001), the oldest castiron drinking water pipes, dating to the late 1800’s, have an average life expectancy of about120 years.

The pipes laid in the 1920’s have an average life expectancy of about 100 years, while thoseinstalled after the World War II era have an average life expectancy of about 75 years.Determination of pipeline useful life is difficult because there is significant influence fromlocalized conditions such as soil conditions and utility interactions. Therefore, the estimatedaverage life expectancies are very general. The design of AWSS pipes is more robust thantypical water distribution piping. However, the performance requirements of the AWSSdistributing piping are also much greater, including higher operating pressure, transport ofhighly corrosive saltwater, and exposure to highly corrosive environments in areas whereAWSS pipes cross through sewer lines.

Figure 5-2 displays a breakdown of the estimated remaining useful life, grouped into 10-year increments. The pipelines in the “Pre-1930” category were assumed installed in 1912for this analysis. Approximately 77 of the 135 miles of pipelines have an estimatedremaining useful life of less than 10 years. Inspection and testing is needed to confirm thecondition of this group of pipelines and identify those that need replacement. This group ofpipes should be addressed within the next 10 to 50 years.



38

Length of Pipelines - By Remaining Useful Life

77.2

2.0

29.5

3.0

11.3 9.2

1.3 0.0 2.1

0

10

20

30

40

50

60

70

80

90

<10

11-2

0

21-3

0

31-4

0

41-5

0

51-6

0

61-7

0

>80

Unkn

own

Estimated Remaining Useful Life

Leng

th (M

iles)

FIGURE 5-2: PIPELINE REMAINING USEFUL LIFE

Potential Corrosion

A condition assessment and corrosion study were performed by SFDPW and documentedin a report titled “Auxiliary Water Supply System (AWSS) Improvements Study” (BryanDessaure, City and County of San Francisco Bureau of Engineering, DPW; December 30,1992). For this study, visual inspections were conducted at nine sites, and various soilcorrosivity tests were performed at over 80 locations along the AWSS pipeline network.

The study found that portions of the AWSS pipeline are at high risk to corrosion and maysuffer from deterioration at these locations. Specific findings included:

29% of pipelines were located in corrosive to very corrosive soils.

Portions of pipe near Muni traction systems may be significantly corroded, due tostray electrical currents.

Potential for accelerated corrosion may exist at 141 locations in which AWSS pipepasses inside of sewers.

Tie rods installed in the period of 1950 to the late 1980’s were made of carbon steelwhich has led to significant corrosion problems.

Severe chloride concentrations exist at three locations: Bryant St and Alameda St,Fourth St and Berry St, and Geary St and Taylor St.

Pipe-to-soil potential tests found that 6% of pipeline suffered active corrosion, while70% suffered minor corrosion.



39

The study found that in general, the following corrosion factors contribute to thedeterioration of AWSS pipeline:

Primary factor is stray current interference.

Secondary factors include pH, chloride concentration, and soil resistivity.

Remote factors include pipe-to-soil potential, years in service, and sulfateconcentrations.

Use of seawater.

Pipe Leaks

SFFD and SFDPW staff have indicated that the AWSS system experiences approximately 2leaks each year that require repair work. The causes of the leaks vary, including influencessuch as settlement and impacts from utility interferences. In addition, other smallerundetected leaks may exist in the system. Based on discussions with SFFD operations staff,water levels in the Jones Street Tank drops approximately 8 feet per day, including thosedays when the AWSS is not used for firefighting. This equates to a loss of approximately0.17 MG per day. There has not been any study to determine the causes of these losses. It ispossible that some of these losses may be attributed to undetected leaks in the pipelines.

Conclusions

There is currently insufficient information to assess the site-specific condition of theAWSS pipelines.

Pipeline age data indicates that the pipelines constructed in 1912 in the originalAWSS construction are approaching 100 years old, some of these pipes may bereaching the end of their useful life.

The study of the corrosion conditions along AWSS pipelines indicate that highlycorrosive conditions exist along some of the pipeline that would accelerate corrosionof pipe barrels and appurtenances and reduce their useful life.

Operational information indicates that approximately 0.17 mgd of water isunaccounted for. Some of this volume may be due to pipeline leakage.

Recommendations

Pipeline age or installation date and construction material data in the GIS database shouldbe checked and confirmed. This would provide more reliable assessments of the remaininguseful life of the AWSS pipelines.

Detailed leak records should be maintained in a GIS format to assist with ongoingassessment of pipeline condition, identifying corrosion hot-spots and estimating actualAWSS-specific pipeline life expectancy.



40

A thorough pipeline inspection and testing program should be developed, including:

Listing and prioritizing the high-risk sites identified in V&A, 1989.

Perform initial inspection and perform pipe wall thickness measurement at high-risksites to determine corrosion rates to date.

Analyze current serviceability at high risk sites, extrapolate future serviceabilitybased on observed corrosion rates.

Formulate long-term inspection and testing plan based on analysis results.

Formulate long-term pipeline replacement plan based on initial inspection, testingand analysis and update periodically based on results from long-term inspectionprogram.

The 77 miles of original pipeline construction should be addressed within the next 10to 50 years. This is equivalent to replacing approximately 2 miles per year.

A program should be implemented to test for leaks in the system and analyze the reason forthe observed unaccounted for water. This program would help identify potential leaks andproblem areas in the system and reduce water losses. The program could include thefollowing elements:

Systematically valving off portions of the system and documenting drops inpressures and water levels. This would help identify sections of the system withpotential leak problems.

Pressure testing portions of the system to more accurately identify potentiallyleaking reaches of pipe.

Install leak detection devices at strategic locations to identify potentially leakingreaches of pipe. These devices could be rotated throughout the system to providebroad coverage of the network.

Perform an audit to determine reasons for the observed unaccounted for water.

5.2.2 Seismic Vulnerability

Infirm Areas

In the 1906 and 1989 earthquakes ground failures resulted in considerable damage tobuildings and lifeline facilities with heaviest damage in reclaimed areas along the shore andfilled-in land areas, commonly known as the infirm areas. These areas consist of sandy soilsexcavated from nearby sand dunes and used to cover soft bay sediments and creek andmarsh regions. It is predicted that future earthquakes would likely cause severe damage inthese areas. Figure 5-3 shows the locations of the Infirm Areas. The AWSS pipe network is



41

provided with isolation valves to minimize loss of water pressure and flow in case offailures in the system.

Ground movement in the infirm areas can result in various pipeline failure modesincluding, bending, pipe/joint compression and extension, tension and joint rotation. Theproblems caused by differential movement are exacerbated where AWSS mains cross overor through pile-supported sewers. At these locations, the difference in settlement of theAWSS pipe and the pipe-supported sewer puts bending stresses on the AWSS pipes.

Loma Prieta Damage

During the 1989 Loma Prieta earthquake, the AWSS suffered damage due to liquefactionand lateral earth spread. There was one 12-inch main break in the South of Market (SOMA)area at 7th St and Natoma St, and four fire hydrant breaks, with three located in SOMA andone in the Foot of Market area. In addition, two leaks were discovered in the Marina districtand on Folsom St in the Mission District. As expected, all AWSS damage was concentratedin the infirm areas. Damage in these areas could not be isolated due to loss of power to theisolation valves. While the majority of the AWSS network remained intact, some specificportions of the system became inoperable as a result of the breaks.



42

FIGURE 5-3: INFIRM SOIL AREAS

Potential Damage in San Andreas Earthquake

In a series of studies performed by Harding Lawson Associates, Dames & Moore,Kennedy/Jenks/Chilton, and EQE Engineering, “Liquefaction Study North Beach,Embarcadero Waterfront, South Beach and Upper Mission Creek Area, San Francisco, FinalReport” and “Liquefaction Study Marina District and Sullivan Marsh Area, San Francisco,California, Final Report” (HLA 1991/1992), the effects of liquefaction resulting from amagnitude 8.3 earthquake on the San Andreas fault was analyzed. The study addressed thefollowing five specific study areas within the City of San Francisco:

Marina

Sullivan Marsh (South of Market)



43

North Beach

Embarcadero Waterfront/South Beach

Upper Mission Creek

These studies estimated the number of pipeline breaks that may occur in a San Andreasearthquake event. Pipeline damage was estimated using historical correlations betweenpipeline damage rates and permanent ground displacement. Table 5-6 lists the actualbreaks in the 1989 Loma Prieta earthquake and estimated number breaks that may occur ina San Andreas M8.3 earthquake.

TABLE 5-6: STUDY AREA EARTHQUAKE DAMAGE RESULTS

Length of PipeMagnitude 7.1

Loma PrietaActual Breaks

Magnitude 8.3San Andreas

Estimated BreaksStudy Area

Feet Miles KMNumber

ofBreaks

BreaksperKM

Numberof

Breaks

BreaksperKM

Marina 8,150 1.54 2.48 0 0 11 4.43Sullivan Marsh(South of Market) 27,000 5.11 8.23 5 0.61 84 10.21

North Beach 9,700 1.84 2.96 0 0 7 2.37EmbarcaderoWaterfront& South Beach 37,500 7.10 11.43 0 0 50 4.37

Upper Mission Creek 15,300 2.90 4.66 0 0 25 5.36

Study Area Total 97,650 18.49 29.76 5 0.17 177 5.95

The results from HLA (1991/1992) indicate that a significant number of pipeline breaks mayoccur in the five study areas following a major San Andreas earthquake. It is likely thatwater will not be available through the AWSS in these specific areas. Use of the portablewater supply system (PWSS), cisterns and connection to hydrants outside of the high-liquefaction areas may be necessary to obtain water for firefighting. Some pipeline damagemay occur outside of the infirm areas, however, damage is expected to be less severe due tolower liquefaction susceptibilities.

A separate study by the National Center for Earthquake Engineering Research developedestimates for breakage rates for AWSS pipelines in a San Andreas earthquake (”AnEvaluation of Seismic Serviceability of Water Supply Networks with Application to the SanFrancisco Auxiliary Water Supply System”, Markov, Grigoriu, O’Rourke; 1994). In thisstudy, a repair rate of 5 to 10 repairs/km were estimated for a magnitude 7.9 San Andreasearthquake, comparable to the value of 5.95 estimated in HLA (1991/1992).



44

Recommendations

HLA (1991/1992) identified a list of options to mitigate seismic hazards affecting the AWSS,including:

1. Installation of flexible joints at main crossing at pile-supported sewers

2. Improvement of hydrant foundations in infirm areas

3. Subdivision of upper and lower zones north/south

4. Replacement of corroded tie rods

5. Expansion of Portable Water Supply System (PWSS)

6. Provide full operational capability of both fireboats following an earthquake

7. Improve reliability of Marina fireboat manifold corridor

8. Implement operational procedures to start AWSS pumps following an earthquake

9. Designate a water supply officer

10. Implement automated leak detection and isolation capability along AWSS pipelines

11. Replace cast iron mains in infirm areas

12. Install flexible joints at hydrant branches in infirm areas

13. Review and revise infirm area boundaries

Some of these recommended actions have been fully or partially implemented. Themitigation measures that are essentially procedural or organizational in nature potentiallyhave the lowest cost and implementation time and should be completed as soon as possible.These include items 3, 6, 8 and 9. The study recommended in item 13 is a lower costmeasure that could be implemented immediately and would help identify other potentiallyvulnerable areas of the AWSS pipeline network.

Items 1, 2, 10 and 12 have intermediate implementation costs and time frames. Makingthese improvements to the system will require some planning work prior toimplementation. Item 5, expansion of the PWSS may provide significant benefit to SFFD inthe event of an earthquake. It has been demonstrated through both engineering analysesand actual course of events that the AWSS may not be available for firefighting in the infirmareas. The PWSS has the advantage of providing some extension of the AWSS supply intoareas not currently covered by the pipeline network.

Items 4, 7 and 11 are larger capital investments into the AWSS pipeline network. Thesetypes of improvements are generally programmatic and implemented over a long-termperiod. As the pipelines in the AWSS system reach the end of their useful lives, these



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improvements would be implemented along with a long-term main replacement program.Since the cast iron pipes are the oldest pipes in the system, they would be replaced sooner inthe program.


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6.0 Geographic Coverage of the AWSS

6.1 AWSS Service Area CharacteristicsThis section describes the geographic coverage of the existing AWSS and the characteristicsof the service area. The characteristics evaluated include population density, land use,building construction, building value per acre, peak ground acceleration, and soilliquefaction susceptibility. For presentation purposes, the City was divided into theneighborhoods shown in Figure 6-1. Demographic and statistical information throughoutthis section is aggregated and presented based on these neighborhoods.

FIGURE 6-1: SAN FRANCISCO CITY NEIGHBORHOODS USED FOR AWSS STUDY

6.0 NEEDS FOR EXPANSION OF THE AWSS


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6.1.1 Geographical CoverageFigure 6-2 shows the coverage of the city provided by the original AWSS system and howthe system has been expanded over time.

The existing AWSS covers nearly all of downtown, North Beach, Marina, Pacific Heights,Mission Bay, Mission and Western Addition. Small portions of the Sunset and Richmondare also covered. The majority of the western and southern parts of the City, such as OuterSunset, Outer Richmond and Excelsior Districts are not covered by the existing AWSS.These areas have developed since construction of the original AWSS.

FIGURE 6-2: AWSS DISTRIBUTION PIPING INSTALLATION

There is a wide range in the density of AWSS pipes throughout the City. The Downtownarea has the highest density of approximately 115 ft/acre. The Marina, Mission, Mission



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Bay, North Beach, Pacific Heights and Western Addition have moderate density rangingfrom 33 to 74 ft per acre. The remaining areas have densities of less than 20 ft per acre.Table 6-1 shows the density of AWSS pipes throughout the City.

TABLE 6-1: POPULATION GROWTH OF SAN FRANCISCO, 1900 – 2000

AreaPipe

Coverage(ft pipe/ac)

Bayview 16Downtown 115Excelsior 3Golden Gate Park 4Ingleside 6Marina 60Merced 0Mission 33Mission Bay 37North Beach 74Pacific Heights 51Presidio 0Richmond 10Sunset 8Twin Peaks 8Western Addition 43

6.1.2 PopulationSince the construction of the AWSS, the population in San Francisco has nearly doubledfrom 417,000 to 777,000 (U.S. Census 2000). Table 6-2 shows the population of San Franciscofrom 1900 to 2000. Development of the City has grown west and south of the central coreareas. While the Year 2000 census reports that there are 777,000 residents in San Francisco, italso estimates the daytime population to be approximately 945,000. This represents aroughly 22% increase in the population. It is expected that a significant portion of thistemporal population increase occurs in the downtown area.



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TABLE 6-2: POPULATION GROWTH OF SAN FRANCISCO, 1900 - 2000

Census Year Population

1900 342,782

1910 416,912

1920 506,676

1930 634,394

1940 634,536

1950 775,357

1960 740,316

1970 715,674

1980 678,974

1990 723,959

2000 776,733

2010 (projection) 809,200

Source: Metropolitan Transportation Commission/Association of Bay Area Governments

Figure 6-3 shows the current population density (population per acre) by neighborhood inSan Francisco based on U.S. Census 2000 records. The map shows that the AWSS extends tomost of the densely populated areas in the eastern parts of the City but does not extend intothe Sunset and Richmond districts on the west side and the Excelsior District in the south.These areas have moderately high population densities.



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FIGURE 6-3: EXISTING AWSS DISTRIBUTION NETWORK AND AVERAGE POPULATION DENSITY BY NEIGHBORHOOD AREA

6.1.3 Land UseFigure 6-4 shows the land use within the City in relation to the existing AWSS pipelines(SFGOV, 2005). Land use data has been aggregated into five major categories: residential,industrial, commercial, mixed use, and parks/open space. Generally, residential land usemakes up a large percentage of San Francisco. Commercial and industrial land use isconcentrated in the downtown, Mission Bay and Bayview Districts. Although some districtssuch as the Sunset and Richmond are primarily residential, they areas also contain pocketsof neighborhood commercial zones.



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FIGURE 6-4: EXISTING AWSS DISTRIBUTION NETWORK AND LAND USE

6.1.4 Building Construction MaterialThe prevalence of wood construction throughout San Francisco is a significant concern dueto fire vulnerability and potential for conflagration. A study on San Francisco’s EarthquakeRisk (ATC, 2005) estimated that more than 90 percent of private building stock in SanFrancisco is of wood construction. The estimated percentage of wood construction in eachneighborhood is shown in Figure 6-5.

The North Beach, Downtown and Mission Bay areas have a relatively lower percentage ofwood construction. The remaining areas of the City have a very high percentage of woodconstruction, greater than 85%. While some of these areas are covered by the AWSS, manyare not.



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FIGURE 6-5: EXISTING AWSS DISTRIBUTION NETWORK AND WOOD CONSTRUCTION BUILDINGS

6.1.5 Building ValuesIn addition to protecting human lives, another purpose of a fire protection system is toprevent the loss of structures to fire and the associated economic loss. Figure 6-6 showsprivate building value in million dollars per acre by neighborhood (ATC, 2005). This mapgives an indication of the potential for fire losses in each area. Most of the higher valuedistricts in the City, areas of $3-5 million/acre or higher, are covered by the existing AWSS.The only exception is the Richmond District, where only the eastern most portion is covered.



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FIGURE 6-6: EXISTING AWSS DISTRIBUTION NETWORK AND PRIVATE BUILDING VALUE

6.1.6 Peak Ground AccelerationPeak ground acceleration (PGA) is a measure of the shaking intensity that would occurduring an earthquake. It is measured as a percentage of the acceleration of gravity (% g).Figure 6-7 shows the PGAs that would be experienced in the City if an earthquake ofmagnitude 7.9 occured on the San Andreas Fault (USGS, 2003). Overall, the entire City willexperience significant ground shaking from such an earthquake. The eastern portions of theCity would be subjected to PGAs of approximately 0.3 g while the western portions wouldexperience approximately 0.6 g. The PGAs shown in Figure 6-7 do not account for localizedsoil conditions, so the shaking in some specific areas may be much higher.



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FIGURE 6-7: EXISTING AWSS DISTRIBUTION NETWORK AND PGA

6.1.7 Liquefaction SusceptibilitySoil liquefaction occurs when the loose sand and silt grains with high moisture contentbehave like a liquid when shaken by an earthquake. When liquefaction occurs, the strengthof the soil is reduced and it loses its ability to support structures.

Figure 6-8 shows soil liquefaction susceptibility in San Francisco (USGS, 2006), ranging fromvery low to very high susceptibility. The eastern bay side of San Francisco is particularlyvulnerable to liquefaction where development has occurred on reclaimed land. There arealso sections of highly liquefiable soils along the western portions of the City near the coast.

One of the impacts of liquefaction is damage to buried pipelines. More damage is expectedin the highly liquefiable areas. For example, following the Loma Prieta earthquake,



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considerable damage occurred to the domestic water system in the Marina District, an areawith a very high liquefaction susceptibility. The loss of water supply significantly impactedfirefighting efforts. It is likely that the next large earthquake will result in similar damage tothe domestic system. Those areas that are served by the redundant AWSS are more likely tohave a working water supply for firefighting. Fortunately, the AWSS is available in most ofthe highly liquefiable zones in the northeast areas of the City. However, it is not available inportions of the southeastern and western areas along the coast.

FIGURE 6-8: EXISTING AWSS DISTRIBUTION NETWORK, LIQUEFACTION SUSCEPTIBILITY



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6.1.8 Greater Alarm Fire IncidentsAs discussed in Section 3, the AWSS is generally used where available for greater alarmfires. AWSS is also used at times for working fires if necessary. This day-to-day usage ofthe AWSS helps reduce the time required to control a fire, and the amount of damage andrisks of conflagration. Figure 3-1 in Section 3 shows the location of greater alarm fires withrespect to the existing coverage of the AWSS. The figure shows that while most of the areaswith higher frequency of greater alarm fires are covered by the AWSS, approximately 10-15% of the greater alarm fires for the 2002 - 2007 period occurred in areas without AWSS.

6.2 Expansion of the AWSSThe purpose of the AWSS is to provide a redundant and reliable water supply for firefighting in the highly developed areas of San Francisco. The AWSS pipeline networkreflects the development of the City in 1913. Over time, the system has been expanded toattempt to keep pace with growth. While these areas have developed significantly overtime, they do not have the same level of AWSS coverage as the northern and eastern areas.

Many of the hazards that affected the City prior to construction of the AWSS are still presentin the western and southern areas of the City. These hazards include seismic vulnerabilityof the domestic system, dense development, prevalence of wood construction and reliancesolely on the domestic system for fire fighting. In the event of a large earthquake, risk ofconflagration in these areas may be similar to 1906 conditions. The Loma Prieta earthquakeconfirmed the conflagration risk from a moderate earthquake. Statistical evidence indicatesthat a similar or larger event is likely to occur in the not too distant future. These riskssuggest that expansion of the AWSS should be considered.

6.2.1 Potential AWSS Expansion AreasThere are four major areas of the City that are not covered by the system. These include theRichmond and Sunset areas in the west side, and Hunter’s Point and Silver Avenue areas inthe south side. Expansion into these areas has been proposed at various times since the 1986Bond issue. The previous proposals also identified pipeline alignments, shown in Figure6-9. The alignments were developed to extend the service area and considered the ease ofrunning pipe along wider streets. The pipelines are laid out to provide a backbone systemin the four expansion areas. The alignments are considered preliminary, but are adequatelydefined for the pre-planning level purposes of this study. As expansion efforts progress,more detailed evaluation is needed to refine these alignments.

Further evaluation of expansion needs should be performed in conjunction with anoptimization of the existing pipe network. As shown in Table 6-1, the range in pipe densityvaries widely throughout the City. Optimization balances the pipe densities, better matchesdensity to current fire fighting needs and reduces the asset management costs of the system.Expansion increases the amount of pipe in areas with lower density. Similarly, the potentialto reduce the pipe density in existing areas should be evaluated.



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FIGURE 6-9: PROPOSED AWSS EXPANSION



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Proposed Richmond Loop Expansion

The existing AWSS pipeline serves the Richmond District only as far west as 12th Avenue.The proposed Richmond Loop Expansion would extend the AWSS westward from 12th

Avenue to 43rd Avenue along California Street and Geary Boulevard. The loop would thenrun south along 43rd through Golden Gate Park to Lincoln Way. The loop would thenconnect to the proposed Sunset Loop Expansion. The total pipeline length of the proposedRichmond Loop Expansion would be approximately 17,000 ft.

Proposed Sunset Loop Expansion

The existing AWSS pipeline serves the Sunset district as far west as 19th Avenue on IrvingStreet. The proposed Sunset Loop Expansion would create two new loops. The first loopbeings on 19th Avenue at Noriega Street, runs west to 41st Avenue, and then north to connectto the new Richmond Loop Expansion at Lincoln Way and 41st Avenue. The second loopwould begin at Noriega Street and run south along Sunset Boulevard to Sloat Boulevard.The line turns to run east on Sloat Boulevard and Ocean Avenue. At 19th Avenue, thepipeline runs north to connect to the existing AWSS line at Ulloa. The total pipeline lengthof the proposed Sunset Loop Expansion would be approximately 30,000 ft.

Proposed Silver Avenue Expansion

The existing AWSS serves Mission Street as far south as Ocean Avenue. The proposed newpipeline would run east from Mission Street and Silver Avenue and eventually connect backinto the existing AWSS at Oakdale Avenue. To cross Highway 101, the proposed pipelinewould first run south on San Bruno, and cross the highway at Bacon Street and returnnorthward back to Silver Avenue along Bayshore Boulevard. The total pipeline length of theproposed Silver Avenue Expansion would be approximately 15,000 ft.

Proposed Hunters Point/Bay View Expansion

Three main extensions are proposed for the Hunters Point/BayView Expansion. The firstpipeline would run east on Revere Avenue, north on Access Road to Crisp Road and east onCrisp Road to the old Hunters Point Naval Shipyard area. The second expansion wouldbegin from Evans Avenue, running south along Middle Point Road and east along InnesAvenue and would end on Donahue Street. The third expansion would run east on GilmanAvenue beginning from Ingalls Street, following the Hunters Point Expressway toCandlestick Point State Park. The total pipeline length of the proposed Hunters Point/BayView Expansion would be approximately 14,000 ft.

Proposed Bayshore Boulevard Connection

The existing AWSS pipeline in the Bayview District along 3rd Street has a dead end on 3rd

Street at Salinas Avenue. An extension is proposed along Bayshore Boulevard beginning atthe dead end on 3rd street and connecting with the proposed Silver Avenue expansion atBacon Street. This connection will improve the supply reliability to the Hunters Point area



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by eliminating the dead end and supplying flow to the area from two directions. The totalpipeline length of the proposed Bayshore Boulevard connection would be approximately3,500 ft.

6.2.2 Storage Capacity AssessmentTwin Peaks Reservoir, Ashbury Tank and Jones Street Tank provide 11.75 Mgal of waterstorage. This storage serves the existing areas of the City covered by AWSS. Should theAWSS be expanded, additional storage capacity may be needed. This section describes theinitial comparison of fire flow estimates to the current storage. This analysis gives anindication whether additional storage may be required, although a more detailed fire flowanalysis would be necessary during the design of storage facilities.

Storage Volumes for Non-Earthquake Conditions

Fire flow estimates for several fire scenarios were developed in the draft report titled“Reclaimed Water/Fire Protection Dual Use system, Analysis of Hydraulic and ReliabilityAspects” (PWSS/EQE, 1994). Fire flows were estimated for the west and south sides of theCity. The fire scenario in each area was developed based on historical data and consists ofone or two greater alarm fires. Table 6-3 lists the fire scenarios and the fire flow volumes.PWSS/EQE (1994) did not develop a fire flow scenario for the northeast side of the City. Forthe purposes of this study, a scenario was assumed for the northeast side consisting of threegreater alarm fires, listed in Table 6-3. These fires are actual events that occurred over thetwo-day period of January 15-16, 2002.

Table 6-3 compares the total fire volume to the total storage for each area of the City. It isassumed that the storage in Twin Peaks Reservoir would be shared among the three areas.The potential additional storage required in each area is calculated as the total fire volumeminus existing reservoir and tank storage. The comparison indicates that if the total firevolume is to be met by AWSS storage, approximately 1.0, 1.4 and 0.5 MG of storage may berequired in the west, south and northeast areas of the City, respectively.



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TABLE 6-3: POTENTIAL FIRE FLOW SCENARIOS AND STORAGE ASSESSMENT FOR NON-EARTHQUAKE CONDITIONS

Fire Scenario2 Existing Storage

Area FireEvent(s) Fire flow Duration

of fire

Totalfire

watervolume

Twin PeaksReservoir 3

ExistingTank

Storage

AdditionalStorage

Required

(GPM) (hours) (MG) (MG) (MG) (MG)

West Side5th Alarm 10,000 6 3.6 2.6

(25%) 0 1.0

South Side 5th Alarm 10,000 64th Alarm 8,000 3

5.0 3.6(34%) 0 1.4

Northeast1 5th Alarm 10,000 6

3rd Alarm 6,000 4

2nd Alarm 4,000 4

6.0 4.3(42%) 1.25 0.45

Total 14.6 10.5 2.8

Notes:1. Based on the actual events from 1/15/02 to 1/16/02 (assumed flow and duration).2. Based on PWSS/EQE (1994).3. Twin Peaks storage allocated proportional to total fire water volume.

Storage Volume Assessment for Earthquake Conditions

In the event of an earthquake, the fire flow volume and duration requirements would besignificantly higher, depending on the intensity and location of the fire, and weatherconditions. PWSS/EQE (1994) developed fire following earthquake scenarios in the westand south sides of the city. Those fire scenarios and water volume requirements arepresented in Table 6-4. The post-earthquake fire flow volumes for the northeast portion ofthe City would be expected to be higher than the west and south sides, but have not beenestimated.

The fire water volume estimates presented in Table 6-4 are much higher than non-earthquake conditions. All of the AWSS water sources, including storage, pump stationsand fireboats, may be required to help meet these flows. It is uncertain whether all of thesesources would be able to meet flow requirements for the northeastern, western andsouthern areas. Additional study is needed to determine the earthquake fire flowrequirements for the northeast. Longer-term system capacity planning should consider thefacilities needed to meet these large anticipated fire flows.



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TABLE 6-4: POTENTIAL FIRE FLOW SCENARIOS FOR EARTHQUAKE CONDITIONS

Service Zone Number offires Duration of fires Total fire water

volumeHours MG

Richmond 2 17 18Sunset 2 14 12South/Outer Mission 2 10 8South/Mission Bay 5 24 28

6.2.3 AWSS Expansion Summary

As discussed above, the expansion of the AWSS may also require new storage tanks andpump stations on the west and south sides. The facilities needed for expansion aresummarized in Table 6-5.

TABLE 6-5: AWSS EXPANSION COMPONENTS

Components Description Size/Capacity

Sunset Expansion Pipeline 5.7 miles

Richmond Expansion Pipeline 3.2 miles

Silver Avenue Expansion Pipeline 2.8 miles

Hunter’s Point Expansion Pipeline 2.6 miles

Bayshore Boulevard connection 0.6 miles

Pipeline

Subtotal Pipeline 15.0 miles

New Storage Tank (Westside) 1.0 Mgal

New Storage Tank (Southside) 1.5 MgalNew Saltwater Pump Station (Westside) 10,000 gpm

Other Facilities

New pump station for new storage tank (Westside) 4,300 gpm


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7.0 AWSS Expansion Efforts with SFPUCRecycled Water Project

The SFPUC is planning to construct facilities to treat and deliver recycled water tocustomers in San Francisco. There may be opportunities to save costs by coordinating theconstruction of recycled water and AWSS facilities. There may also be the potential tosupply recycled water to the AWSS. The SFFD and SFPUC explored several coordinationconcepts in this study. This section describes these concepts and the findings regardingwhich may be feasible at this time.

7.1 Definition of Recycled Water

Recycled water is wastewater that has been highly treated to strict standards set by the CaliforniaDepartment of Public Health (DPH). These standards have been developed to protect public healthand safety. Some of the uses of disinfected tertiary recycled water allowed in California include:

Irrigation (including landscaping and food crops)Toilet flushingIndustrial processesStructural fire fightingDecorative fountainsAutomated commercial car washesCooling towersRecreational impoundments

7.2 San Francisco Recycled Water Program and WestsideRecycled Water Project

In 2006, the San Francisco Public Utilities Commission (SFPUC) developed the RecycledWater Master Plan (RWMP). The RWMP identified recycled water users, their quantity andquality requirements and evaluated project alternatives. The plan identified a long-termprogram to deliver recycled water to customers throughout the City, and focused onimplementation of the first phase of the program. Phase 1 consisted of four projects:

Westside Baseline Project

Harding Park/Lake Merced Project

Expanded Westside Baseline Project

Marina Corridor Project.

The SFPUC is in the planning phase of the Westside Baseline Project, now titled theWestside Recycled Water Project (WRWP). Project alternatives have been analyzed and the

7.0 AWSS EXPANSION EFFORTS WITH SFPUC RECYCLED WATER PROJECT


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environmental review process is beginning. Both the environmental review and designphases are expected to be completed in 2010 and construction is planned for completion in2013.

The project will serve an estimated annual average demand of 2.0 mgd to irrigationcustomers on the Westside of the City. Figure 7-1 shows the preliminary location offacilities in this project. Transmission piping along Sunset Blvd. or 41st Avenue will transmitwater along the west side of the City to Golden Gate Park. Recycled water will be stored ina storage facility at the site of an existing 2 MG reservoir in Golden Gate Park. Pipelines willthen transmit recycled water north to users in the Richmond District. One or more pumpstations may be required along the transmission system to boost pressure and lift water tohigher elevations.

7.3 AWSS – Recycled Water Coordination Opportunities

Several meetings were held with the SFPUC, SFFD, SFDPW and the Capital PlanningProgram to identify and discus potential coordination opportunities between the RecycledWater Program and the AWSS. Three incremental were discussed:

Common trenching during pipeline construction

Supplying recycled water to AWSS storage facilities

Using the AWSS as a distribution system for recycled water

7.3.1 Coordination Concept 1: Common TrenchingThe preliminary pipeline alignments for the recycled water project and AWSS expansion arethe same or very close to one another in the Westside. Construction costs and impacts maybe reduced if recycled water and AWSS pipelines were installed simultaneously. Thepipeline systems would remain independent. The projects would share costs such asexcavation, paving and traffic controls. Neighborhood disruption due to constructionactivities would also be reduced. Preliminary cost estimates indicate that commontrenching could result in 25% savings in construction costs.

Additional study is needed to identify which pipeline alignments can be installed togetherand if modifications to alignments are needed. Project schedules also need to be evaluatedto determine if pipeline construction can occur at the same time. It was concluded by theSFPUC, SFFD, SFDPW and the Capitol Planning Program that Coordination Concept 1provides benefits to the RWP and AWSS expansion efforts. This concept will beincorporated into AWSS expansion recommendations.



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FIGURE 7-1: RECYCLED WATER COORDINATION OPPORTUNITIES



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7.3.2 Coordination Concept 2: Supplying Recycled Water to AWSSThe water in the AWSS system is considered non-potable. Therefore, it may be possible userecycled water in the AWSS for fire fighting. As described previously, the water usage ofthe AWSS has been estimated to be approximately 0.2 mgd. To fully meet this demand,recycled water must be delivered to all parts of the system. One way to accomplish this is todeliver water to Twin Peaks Reservoir, where it can then flow by gravity to all parts of thesystem. Transporting recycled water to Twin Peaks Reservoir would require additionalinfrastructure, including pipelines and pumps to move water from RWP facilities to TwinPeaks Reservoir.

The advantages of supplying the AWSS with recycled water include a reduction in usage ofpotable water and redundant water supply to the AWSS. Disadvantages include the cost ofadditional infrastructure. Additional work is needed to plan out where the systems wouldbe connected, the locations of facilities and coordination of the operations of the twoprojects. It is estimated that the current WRWP could be delayed approximately 18 monthsto accommodate this concept.

Because Coordination Concept 2 requires additional study it is not recommended at thistime. However, this does not preclude delivery of recycled water to the AWSS in the future.SFFD and SFPUC will continue planning and engineering work related to this concept. Inthe interim, the current WRWP must continue so that this important water supply projectcan be completed on schedule. Other broader City-wide planning efforts such as the SewerSystem Master Plan will continue to evaluate this concept.

7.3.3 Coordination Concept 3: Distribution of Recycled Water Through theAWSS

The third concept discussed includes using the AWSS as a distribution system for recycledwater throughout the City. Recycled water customers on both the east and west sides of theCity could be served. Recycled water would be used for fire fighting as well as other usessuch as irrigation. Therefore, the amount of recycled water delivered could be much largerthan in Concept 2.

The advantage of this concept is that recycled water can be delivered to a larger number ofcustomers throughout the City using existing pipe systems. A greater reduction in potablewater use could be achieved and the cost of constructing pipelines may be reduced.

Using the AWSS to distribute recycled water presents some challenges that would need tobe solved prior to implementing this concept. Some examples include:

Ensuring water supply priority for fire fighting purposes

Managing the pressure difference between the high pressure for fire fighting andlower pressures for other recycled water customers.

Managing emergency scenarios when salt water must be pumped into the AWSS.

Maintaining seismic reliability of the AWSS system by minimizing the impact ofservice connections.



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Additional planning and engineering work is needed to fully develop this concept before itcan be recommended. Longer-term planning can continue, and implementing Concept 1 atthis time does not preclude implementation of Concept 3 in the future. Other broader City-wide planning efforts, including the Sewer System Master Plan, will further analyze thisconcept in conjunction with subsequent phases of the Recycled Water Program.

7.4 Summary

The relative cost, complexity, and time frame of the concepts are summarized in Table 7-1At this time, it is recommended that Common Trenching (Concept 1) be implemented whereappropriate during construction of recycled water and AWSS pipelines. It may result incost savings to the City during construction. This recommendation is abased on the initialscreening of the three coordination concepts and input from SFFD and SFPUC. Planningwork to further develop Concepts 2 and 3 should continue so that they may be implementedwith future phases of the RWP if found to be feasible.

TABLE 7-1: RECYCLED WATER COORDINATION CONCEPTS

Concept Cost Complexity Time FrameConcept 1: Common Trenching Low Low Short-termConcept 2: Supplying Recycled Water to AWSS Medium Medium Mid-termConcept 3: Use of AWSS for Recycled WaterDistribution High High Long-term


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8.0 Improvements Required to Meet the Currentand Future Needs

This section summarizes the major improvements required to meet the current and futureneeds of the AWSS. Most of the existing AWSS facilities need to be retrofitted or replaceddue to the excessive age. Extension in the AWSS pipeline network is required to provideadequate water supply in highly developed areas of the City which currently do not have anauxiliary water supply for fire protection.

8.1 AWSS Existing Facility Improvements8.1.1 Improvements to Above Ground FacilitiesThe improvements required in the existing AWSS facilities are identified in Section 5 andare further refined in this section. As mentioned in Section 5, complete replacement of someof the existing AWSS facilities is identified to be more cost effective than retrofitting. Theseimprovements are briefly discussed below.

Ashbury Tank

The entire facility components are considered to be beyond their useful life due to the age.The facility may not meet the current seismic standards. The Tank and pump stationbuilding, and all mechanical, electrical, and structural components, and site retaining wallwould be replaced. Some site improvements are also required.

Jones Street Tank

The tank and electrical components located outside of the control building including theemergency generator are considered to be beyond their useful life. The control building maynot meet the current seismic standards. The site retaining wall is also towards the end of itsuseful life span. The tank, emergency generator and associated components, and siteretaining wall would be replaced. The control building would be seismically retrofitted.


The reservoir liner may have been significantly deteriorated. This is evident from the dailywater loss from the reservoir. Complete replacement of the reservoir liner is required. Diveinspection for the assessment of reservoir’s internal condition is also required. The inlet andoutlet piping and concrete fence post and iron fencing would also be replaced due to severedeterioration.

Pump Station No. 1

The mechanical and electrical components of the pump station, and intake tunnel areconsidered to be beyond their useful life span and need to be replaced. It is also required toreplace the floor slab and retrofit the floor supports to mitigate foundation settlement issues.

9.0 CONCLUSIONS AND RECOMMENDATIONS


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Pump Station No. 2

The entire facility needs to be replaced. The mechanical and electrical components of thepump station, and intake tunnel are considered to be beyond their useful life span and needto be replaced. In addition, the pump station building does not appear to meet the currentseismic standards and would be replaced.

8.1.2 Improvements to PipelinesPotential Long-Term Replacement Needs and Costs

As previously indicated, the condition and useful life of buried pipelines are verydependent on site-specific conditions and can be highly variable. The amount of AWSSpipeline that needs replacement and the time frame is best determined through acomprehensive condition assessment and replacement program.

However, based on generalized estimates of useful life, the 77 miles of original AWSSpipeline constructed in 1913 may be nearing the end of its useful life. Some or all of thisoriginal pipe may require replacement over the next 50 years. This equates toapproximately 1.5 miles of pipe per year over the next 50 years. The 58 miles of pipeconstructed after 1913 may similarly require replacement thereafter.

The cost of installing AWSS pipe is significantly higher than that for typical domestic waterpipe. Each mile of AWSS costs $19 million to install, vs. approximately $3.7 million fordomestic water pipe. This comparison is based on 20-inch diameter pipe. There are severalfactors that contribute to the higher cost. Pipe fittings and hydrants are specially cast,making them costly to procure. There is a single foundry that produces these components.For example, an AWSS hydrant costs approximately $18,000 vs. $3,000 for a standarddomestic hydrant. A 45-degree bend costs approximately $5,100 vs. $2,800 for the samecomponent of the domestic water system. The pipe joints for domestic water pipes aretypically rubber gasketed joints which may be pushed on in the field. AWSS pipes use thesesimilar types of joints, but in addition, at thrust points, the joints are restrained against pull-out using stainless steel tie rods. The restrained joints increase the cost of both material andinstallation for AWSS pipe. At the unit costs indicated above, replacement of 1.5 miles peryear would cost approximately $30 million annually

Upgrading Domestic System Pipes In-Lieu of Replacing AWSS Pipes

Upgrading select portions of the domestic system in lieu of replacing AWSS pipes mayappear to have multiple benefits – adding reliability to both the domestic system and theAWSS. However, the advantages may be offset by several factors. To provide the samelevel of reliability as the current AWSS, upgrades to the domestic system pipes would needto be in accordance with AWSS specification, likely negating potential cost savings. Reliablesupply to domestic hydrants may require retrofitting pipes from the hydrant back to thewater source, usually a tank or reservoir. This has the potential to increase the total lengthof pipe that must be upgraded. An aspect of the AWSS that increases its reliability is theminimal number of branches and service connections. Significant pipe networkreconfiguration effort could be required to achieve a similar level of reliability in theselected portions of the domestic system.



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Optimizing the AWSS Pipe Network

The annual expenditures for pipe replacement are directly related to the amount of agingpipe in the system. The current pipe network configuration requires a significant annualexpenditure to maintain the system in a state of good repair. Optimizing the pipe networkwould reduce the long-term expenditures and has other benefits as well.

The current pipe network was configured for conditions at the time of original constructionof the AWSS in 1908. Optimizing the pipe network involves evaluating today’s firefightingneeds and refining the layout and density of piping with the objective of reducingmaintenance costs and improving reliability and flexibility.

For example, the density of piping in the Downtown area is approximately 110 feet of pipeper acre. By comparison, the density of piping in the North Beach, Pacific Heights andMarina Districts is approximately 50 – 70 feet of pipe per acre. Optimization in theDowntown area would include evaluating whether the firefighting needs could be met witha backbone system. A backbone system consists of a streamlined network of largerdiameter pipes spaced farther apart. This is in contrast to the current configuration ofsmaller pipes spaced much closer together. Service would be extended to either side of thebackbone using the PWSS.

An optimized pipe network has multiple benefits:

An optimized pipe network is more financially sustainable. Because the overall lengthof pipe is reduced, the long-term cost of maintaining the system is reduced.

A backbone system is also more seismically reliable. A reduction in branches andoverall pipe length result in fewer opportunities for pipe breaks in the system in anearthquake.

In a backbone system, a portion of the buried pipe network is essentially replaced withPWSS capability. Expanding the PWSS to serve the areas between backbone pipesenhances the flexibility of the system. PWSS is portable and scalable to meet the needsof each incident. In an earthquake, additional mobile capability will increase SFFD’sability to bring resources to locations they are needed most.

Additional work would be required to fully develop the approach and to analyze where thesystem could be optimized. This process would involve the following steps:

Evaluate the firefighting needs in the each area

Develop system criteria

Analyze hydraulics and develop the backbone system

Define the PWSS requirements

The analysis would be conducted together with development of a condition assessment andin pipe replacement program. The data from the optimization process would help definehow much pipe would be replaced and where.



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8.1.3 Fireboat HeadquartersAn assessment of the fireboat headquarters building and pier structure was conductedpreviously under a separate effort. This assessment found structural problems with thesefacilities. The cost of the improvements has been estimated to be $10.7 million, $8.4 millionof which would come from proposed bond funding (City and County of San FranciscoCapital Plan, 2009-2018). This $8.4 million is included in the estimated costs forrehabilitation of existing facilities.

8.1.4 Cost Estimate

Table 8-1 summarizes the planning-level cost estimate for the improvements to the existingAWSS facilities and Table 8-2 summarizes a conceptual-level cost estimate for the analyzingthe pipe network and developing a condition assessment and repair/replacement program.

The cost estimate is based on the preliminary information and assumptions. The costs arebased on 2008 data. The various components of the cost estimates are described below.

Total Construction Cost includes demolition cost where applicable, raw constructioncost, contractor’s overhead, design and estimating contingency and environmentalmitigation allowances.

Construction Contingency (20%), planning (15%), design (15%), constructionmanagement (15%), and project contingency (15%) are assumed based on the severalother Bay Area project’s cost data.

Total Project Cost is the sum of the total construction cost and construction andproject contingency, planning and design, and construction management costs.



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TABLE 8-1: AWSS FACILITY IMPROVEMENTS COST ESTIMATE

TotalConstruction

Cost

ConstructionContingency Planning Design Construction

ManagementProject

Contingency Total ProjectCost Total Cost

1 2 3 4 5 6 720% 15% 15% 15% 15%

$10,900,000Replace Tank $3,140,000 $590,000 $560,000 $560,000 $560,000 $820,000 $6,230,000Replace Pump Station building $460,000 $90,000 $90,000 $90,000 $90,000 $130,000 $950,000Equipment $1,350,000 $260,000 $250,000 $250,000 $250,000 $360,000 $2,720,000Site Improvements $480,000 $90,000 $90,000 $90,000 $90,000 $130,000 $970,000

$10,200,000Replace Tank $3,690,000 $690,000 $660,000 $660,000 $660,000 $960,000 $7,320,000Retrofit Tank Control Building $470,000 $90,000 $90,000 $90,000 $90,000 $130,000 $960,000Equipment $260,000 $50,000 $50,000 $50,000 $50,000 $70,000 $530,000Site Improvements $680,000 $130,000 $130,000 $130,000 $130,000 $180,000 $1,380,000

$11,400,000Replace Reservoir Liner $2,930,000 $550,000 $530,000 $530,000 $530,000 $770,000 $5,840,000Replace Inlet/Outlet Structures $250,000 $50,000 $50,000 $50,000 $50,000 $70,000 $520,000Site Improvements $550,000 $110,000 $100,000 $100,000 $100,000 $150,000 $1,110,000Slope Protection/Erosion Control $1,800,000 $340,000 $330,000 $330,000 $330,000 $470,000 $3,600,000Testing and Analysis $130,000 $30,000 $30,000 $30,000 $30,000 $40,000 $290,000

$29,700,000Structural Retrofitting of Floor $320,000 $60,000 $60,000 $60,000 $60,000 $90,000 $650,000Retrofit Intake Tunnel $11,880,000 $2,220,000 $2,120,000 $2,120,000 $2,120,000 $3,070,000 $23,530,000Equipment $2,290,000 $430,000 $410,000 $410,000 $410,000 $600,000 $4,550,000Site Improvements $470,000 $90,000 $90,000 $90,000 $90,000 $130,000 $960,000

$16,100,000Replace Pump Station Building $3,920,000 $740,000 $700,000 $700,000 $700,000 $1,020,000 $7,780,000Retrofit Intake Tunnel $1,620,000 $310,000 $290,000 $290,000 $290,000 $420,000 $3,220,000Equipment $2,230,000 $420,000 $400,000 $400,000 $400,000 $580,000 $4,430,000Site Improvements $290,000 $60,000 $60,000 $60,000 $60,000 $80,000 $610,000

Portion funded by G.O. Bond (CCSF Capital Plan 2009-2018) $8,400,000

Total Improvements to Existing AWSS Facilities $86,700,000

Pump Station No. 2

Fireboat Headquarters

Jones Street Tank


Pump Station No. 1

Facility/Component

Ashbury Tank

TABLE 8-2: AWSS DISTRIBUTION PIPING IMPROVEMENTS COST ESTIMATE

Improvement Component Planning-levelCost Estimate


$250,000$500,000

Condition Assessment and Repair/Replacement Program- Allowance for Field Testing- Analyze Field Data- Develop Repair/Replacement Program

$1,000,000

Develop Emergency Repair, Readiness, and Response Program $150,000Pipeline Replacements Phase 1 - Initial phase of pipeline replacements - Replace pipelines adjacent to newly constructed facilities $11,400,000

Total $13,300,000



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8.2 AWSS Expansion ProjectsThe need for AWSS expansion and the potential AWSS expansion projects are discussed inSection 6.2. These projects would involve construction of new AWSS pipelines in the areaswhich currently do not have auxiliary water supply.

The proposed AWSS expansion would require a total of approximately 80,000 feet of newpipeline and associated components, one new saltwater pump station, and one pumpstation for the Westside expansion, one storage tank to serve the Westside expansion areasand one for the southeast side expansion areas (Table ).

A planning level cost estimate for these expansion projects is provided in Table 8-3 . The costestimate is based on the preliminary information and assumptions. The costs are based on2008 data.

TABLE 8-3: AWSS PROPOSED EXPANSION COST ESTIMATE

TotalConstruction

Cost

ConstructionContingency Planning Design Construction

ManagementProject

Contingency Total ProjectCost Total Cost

(1) (2) (3) (4) (5) (6)20% 15% 15% 15% 15%

$198,700,000Sunset Expansion Pipeline $47,740,000 $8,920,000 $8,500,000 $8,500,000 $8,500,000 $12,330,000 $94,490,000Richmond Expansion Pipeline $31,510,000 $5,890,000 $5,610,000 $5,610,000 $5,610,000 $8,140,000 $62,370,0001.0 Mgal Storage Tank $5,010,000 $940,000 $900,000 $900,000 $900,000 $1,300,000 $9,950,000Saltwater Pump Station $11,630,000 $2,180,000 $2,080,000 $2,080,000 $2,080,000 $3,010,000 $23,060,000Westside Pump Station $4,400,000 $830,000 $790,000 $790,000 $790,000 $1,140,000 $8,740,000

$133,700,000Silver Avenue Expansion pipeline $28,400,000 $5,300,000 $5,060,000 $5,060,000 $5,060,000 $7,340,000 $56,220,000Hunter's Point Expansion Pipeline $26,500,000 $4,950,000 $4,720,000 $4,720,000 $4,720,000 $6,850,000 $52,460,000Bayshore Blvd. Connection Pipeline $6,630,000 $1,240,000 $1,190,000 $1,190,000 $1,190,000 $1,720,000 $13,160,0001.5 Mgal Storage Tank $5,980,000 $1,120,000 $1,070,000 $1,070,000 $1,070,000 $1,550,000 $11,860,000

Total AWSS Expansion $332,400,000

Expansion Area

Westside Expansion

Southside Expansion

8.3 Benefits of AWSSThe importance of maintaining and expanding the AWSS can be tied to the risk of fire lossesin the City. During day-to-day fire fighting operations, the AWSS supplements thedomestic system. Following an earthquake, however, the AWSS may become the primarywater supply for fire fighting. It is under these conditions that much of the value of thesystem will be realized. Therefore, the risk of fire losses can be brought to light byconsidering 1) the potential fire damage after an earthquake and 2) the likelihood that amajor earthquake will occur.

The potential fire damage after an earthquake is significant. The value of the privatebuilding stock in the City is estimated at $104 billion (ATC 2005), which does not include thevalue of buildings owned by public agencies. Following a magnitude 7.9 earthquake on theSan Andreas fault, the damage due to ground shaking is estimated to be approximately$29.1 billion. Ensuing fires would increase the amount of damage by 30 percent, or $8.8



73

billion. Business closures, loss of jobs, and loss of property and sales tax revenues wouldincrease the economic impacts even further.

These estimates already account for the redundancy provided by the AWSS. The fire lossesthat could result if the City did not have the AWSS have not been estimated. There arefactors that may prohibit a direct comparison of losses between the 1906 and a similarearthquake in the future. However, bear in mind that without the AWSS in 1906, ensuingfires increased the amount of damage over ground shaking alone by 400 percent.

Conditions remain in San Francisco that leave the City vulnerable to conflagration after anearthquake. The Loma Prieta clearly demonstrated that portions of the City will havelimited fire fighting capability as a result of damage to domestic water pipes. Wind, narrowstreets, building density and wood construction make some parts of the City as vulnerableto conflagration as they were in 1906 (Scawthorn/O’Rourke/Blackburn, 2005). The AWSSplays vital role in reducing these vulnerabilities.

Given the statistical estimates by the USGS, there is a relatively high likelihood that a majorearthquake will occur in the Bay Area. An earthquake with a magnitude 6.7 or greater has a62 percent probability of occurring within the next 24 years. This earthquake is expected tobe centered closer to Bay Area urban population centers. By comparison, the Loma Prietaearthquake was a magnitude 6.9 event centered 60 miles south of San Francisco. The USGShas determined that these estimates represent a high probability of a damaging earthquakethat puts Bay Area lives, housing and infrastructure at risk (USGS, 2003). While there isalways uncertainty associated with such statistical information, the USGS considers theseprobabilities appropriate for seismic planning purposes. It is therefore critical that theearthquake disaster planning for the City of San Francisco, including mitigation for post-earthquake fire, consider the high potential level of damage and high likelihood ofoccurrence.


74

9.0 Conclusions and recommendations

9.1 Conclusions1. The concept of a supplemental fire fighting system is not unique to San Francisco.

Other cities have implemented system similar to the AWSS and PWSS. Like SanFrancisco, earthquake risks are a major reason they have developed auxiliary firefighting systems and have looked to the City’s AWSS as a model.

2. Fragility analysis and experience following Loma Prieta indicate that the domesticwater pipes will experience damage after a large earthquake. In the hours followingan earthquake, the SFFD may rely heavily on alternative water supplies for firefighting. While the AWSS pipelines will sustain some damage in a majorearthquake, they are expected to experience fewer breaks than the domestic waterpipelines.

3. The USGS estimates a 62 percent probability of a magnitude 6.7 or greaterearthquake in the Bay Area by the year 2032. The 1906 earthquake was the impetusfor constructing the AWSS. Earthquake readiness remains one of the primaryconcerns of the City and the main reason for maintaining the AWSS. The MarinaDistrict fire following the Loma Prieta earthquake illustrated the need for analternative water supply for firefighting following an earthquake.

4. There is a significant risk of fire loss following an earthquake. ATC (2005) estimatedthe potential damage from fire following earthquake to be approximately $8 billion.This accounts for the redundancy provided by the AWSS. Fire losses without theAWSS would be expected to be higher.

5. All of existing above-ground facilities and roughly half of the pipelines are of theoriginal construction completed in 1913. They are all approaching 100 years old.These facilities remain operational due to the diligent maintenance of the SFFD.However, the physical condition and seismic vulnerability of the facilitiescompromises the system’s reliability. The above ground facilities requirerehabilitation and in many cases complete replacement.

6. There is not much information available on the physical condition of the pipes in thesystem. While the age of the AWSS pipelines are known, their physical condition isrelatively unknown. Pipe conditions can vary widely because of the many factorsthat can affect pipeline deterioration, such as soil settlement, corrosive soilchemistry, exposure to bay water tidal fluctuations and stray currents. Aprogrammatic approach to pipeline condition assessment is needed.

7. There is a significant quantity of pipe that may be nearing the end its useful life overthe next 50 years. The cost of maintaining the AWSS in its current configuration



75

includes replacing this pipe over time, at a cost of approximately $30 million peryear. There may be opportunities to optimize the AWSS pipe network, includingmoving to a backbone-type system in some areas of the City. This type ofconfiguration has the benefits of reducing long-term maintenance costs, andimproving reliability and flexibility.

8. Although the AWSS was constructed primarily to supplement the domestic systemin an earthquake, it is also used frequently during non-earthquake conditions. In theevent of greater alarm fires (two or more alarms) the AWSS hydrants are generallytapped if they are available. Over the past five years, it is estimated that the AWSShas been used as frequently as 30 times a year.

9. The AWSS primarily covers the north east portion of the City. This was the mostdeveloped portion of the City in 1913. Since then, the western and southern portionsof the City have fully developed. But, the AWSS pipelines have not been extendedto these areas. The level of protection for these areas is less than the downtown areawhere the AWSS is available. The prevalence of wood construction, moderate tohigh population density and moderate to high building values in the western andsouthern portions of the City warrants consideration of expanding the AWSS servicearea.

10. The SFPUC is planning to construct facilities to treat and deliver recycled water tocustomers on the west side of San Francisco. There may be opportunities to savecosts by coordinating the construction of recycled water and AWSS pipelines. Othercoordination opportunities including supplying recycled water to the AWSS and useof the AWSS to distribute recycled water require additional evaluation.

9.2 RecommendationsThe recommendations of this study are presented below in four areas, AWSS pipelines,AWSS expansion, rehabilitation of existing facilities and evaluation and enhancement ofPWSS capability.

Rehabilitation of Existing Facilities

Rehabilitate/replace pump stations, tanks and reservoir to bring them to a state of goodrepair and ensure that they will be operational after an earthquake. Table 9-1 lists theneeded improvements and planning-level cost estimates.



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TABLE 9-1: IMPROVEMENTS TO EXISTING FACILITIES

Facility Needed Improvement Cost Estimate(Planning-Level)

Ashbury Tank Replace tank and pump station $10,900,000

Jones Street Tank Replace tank and retrofit building $10,200,000

Twin Peaks Reservoir Perform dive inspection and replacereservoir liner if needed

$11,400,000

Pump Station No. 1 Retrofit basement slab and floor supportsReplace all mechanical and electricalequipment

$29,700,000

Pump Station No. 2 Replace pump station $16,100,000Fireboat Headquarters Replace Pier and Building (Phase II) $8,400,000

Total $86,700,000

AWSS Pipelines

There are several recommended actions related to the AWSS pipelines. Therecommendations are described below and the estimated costs are shown in Table 9-2.

Implement a pipeline condition assessment and repair/replacement program. Thisprogram should include the following elements:

- Field testing plan that includes inspection, ultrasonic wall thickness measurement,corrosivity testing and pressure testing.

- Analysis of field data to assess condition of pipelines in terms of serviceability,remaining useful life and replacement priority

- Funding for long-term pipe repair/replacement at a rate determined from analysis offield data. An initial-year allocation to repair/replace one mile of pipeline issuggested.

Evaluate optimal configuration of the AWSS pipe network. The work would involveevaluating the firefighting needs in different areas of the City, developing system criteria,analyzing the hydraulics of the system, developing the backbone pipe network anddefining the PWSS requirements. Development of a hydraulic model of the system as theprimary analytical tool should be included in this work.

Implement an emergency pipeline repair, readiness and response program. Thisprogram would increase the capability of the SFFD to quickly restore AWSS pipelines toservice after an earthquake. The program may be modeled after similar programsdeveloped by the SFPUC for the City’s potable water system. The program shouldinclude:



77

- Development of emergency pipe break response procedures- Stockpile of pipe and fittings- Establishing emergency access to equipment and resources to quickly effect repairs.

Implement initial phase of pipeline replacements. This program should includereplacement of the pipelines adjacent to those above ground facilities that are replaced orretrofitted. This improves the reliability of the connection between these new facilities andthe rest of the pipe network.

TABLE 9-2: PIPELINE IMPROVEMENTS RECOMMENDATIONS

Improvement Component Planning-levelCost Estimate


$250,000$500,000

Condition Assessment and Repair/Replacement Program- Allowance for Field Testing- Analyze Field Data- Develop Repair/Replacement Program

$1,000,000

Develop Emergency Repair, Readiness, and Response Program $150,000Pipeline Replacements Phase 1 - Initial phase of pipeline replacements - Replace pipelines adjacent to newly constructed facilities $11,400,000

Total $13,300,000

AWSS Service Area Expansion

Extend AWSS pipelines to the west and south sides of the City. Because of the developmentthat has occurred in the western and southern areas of the City, expansion of the AWSS intothese areas should be considered. Table 9-3 presents the conceptual cost estimates forexpansion of the AWSS.



78

TABLE 9-3: AWSS EXPANSION AREAS AND COSTS

Expansion Area Cost Estimate

Westside Extension

Sunset Pipeline Extension $ 94,490,000

Richmond Pipeline Extension $ 62,370,000

New Westside Storage Tank $ 9,950,000

New Westside Pump Station $ 8,740,000

New Saltwater Pump Station $ 23,060,000

Southside Extension

Silver Avenue Pipeline Extension $ 56,220,000

Hunter's Point Pipeline Extension $ 52,460,000

Bayshore Pipeline Extension $ 13,160,000

New Southside Storage Tank $ 11,860,000

Total AWSS Expansion $ 332,400,000

Evaluation and Enhancement of PWSS Capability

Following the Loma Prieta earthquake, the SFFD responded to the Marina District fire usingthe PWSS. In the event of a major earthquake in the Bay Area, multiple fires may occur andrequire simultaneous response using PWSS equipment. Current SFFD capability to deployPWSS to multiple fires should be evaluated. If analysis shows that additional PWSSequipment is needed, funding should be secured to purchase additional hose tenders andappurtenant equipment. PWSS may serve as an interim readiness measure prior toexpansion of the AWSS to the western and southern areas of the City. The portable systemwould allow drafting from open water bodies in the areas where there are no AWSShydrants.

Implementation Plan

Implementation of improvements to the AWSS system involves further planning,coordination with funding activities and coordination with other City Departments. Figure9-1 shows a flow chart of the sequence of decision, planning and implementation steps foradvancing improvements to the AWSS. Activities shown in the chart include both criticalshorter-term and longer-term planning activities.



79

Figure 9-1. Decision, Planning and Implementation Activities for AWSS Improvements

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Appendix AReferences

1. Applied Technology Council (ATC), March 1, 2005. San Francisco’s Earthquake Risk”Report on Potential Earthquake Impacts in San Francisco,Obtained from website:http://www.pbs.org/newshour/indepth_coverage/science/1906quake/atc-report.pdf

2. Bendimerad F., Bouabid, J.; “Seismic Reliability Assessment of Water Systems”; LifelineEarthquake Engineering: Proceedings of the Fourth U.S. Conference; edited by O’RourkeM.; August 1995.

3. City of Berkeley May 2007. Mobile Disaster Fire Protection System. Action Calendar.4. City and County of San Francisco, January, 2008. Capital Planning Program, FY-2009 –

2018 Capital Plan.http://www.sfgov.org/site/uploadedfiles/cpp/meetings/cpc/supporting/2008/CCSF

_09_18_Cap_Plan_Debt_Summary.pdf5. “Dawn of the Replacement Era: Reinvesting in Drinking Water Infrastructure”;

American Water Works Association; May 2001.6. DPW, December 30, 1992. Auxiliary Water Supply System (AWSS) Improvements Study,

Bureau of Engineering.7. Eidinger, J., Avila, E.; “Guidelines for the Seismic Evaluation and Upgrade of Water

Transmission Facilities”; Technical Council on Lifeline Earthquake Engineering; January1999.

8. FEMA, November, 2006. “HAZUS-MH Used to Support San Francisco Bay AreaEarthquake Exercise”.

9. Filiatrault, A., Uang, C., Folz, B., Chrstopoulos, C., Gatto, K., March, 2001. ReconnaissanceReport of the February 28, 2001 Nisqually (Seattle-Olympia) Earthquake. Department ofStructural Engineering, University of California, San Diego.

10. Geotechnical Board, National Research Council; “Practical Lessons from the Loma PrietaEarthquake”; 1994.

11. Markov, I., Grigoriu, M., O’Rourke T.; “An Evaluation of Seismic Serviceability of WaterSupply Networks with Application to the San Francisco Auxiliary Water SupplySystem”; Technical Report NCEER-94-0001; January 21, 1994.

12. Mickelson, P., Moore, D.E., August 1995. City of Vancouver Dedicated Fire protectionSystem Underground Piping Design Consideration. Technical Council on LifelineEarthquake Engineering of the American Society of Civil Engineers, Monograph No. 6,Published by ASCE.

13. Odeh, D., Khater, M., Scawthorn, C., Blackburn, F., Kubick, K; “Reliability Analysis of aDual Use Fire Protection/Reclaimed Water System, San Francisco, CA”; LifelineEarthquake Engineering: Proceedings of the Fourth U.S. Conference; edited by O’RourkeM.; August 1995.

14. Proposed $97,000,000 Bond Issue, March 1992. Modernization of Fire Protection Systems,SFFD, Division of Support Services.

15. PWSS Co. Ltd., April 1993. Preliminary Report and Recommendations AWSS/ReclamationWater Project.

16. San Francisco Department of Building Inspection Community Action Plan for SeismicSafety (CAPSS); “San Francisco’s Earthquake Risk: Report on Potential EarthquakeImpacts in San Francisco”; Applied Technology Council; March 1, 2005.

17. San Francisco Department of Public Works; “Auxiliary Water Supply SystemRehabilitation Program: Condition Assessment of Underground Piping”; prepared byVillalobos & Associates; October 1989.

http://www.pbs.org/newshour/indepth_coverage/science/1906quake/atc-report.pdf

http://www.sfgov.org/site/uploadedfiles/cpp/meetings/cpc/supporting/2008/CCSF


2

18. Scawthorn, C., O’Rourke, T.D., Blackburn, F.T., April 2006. The 1906 San FranciscoEarthquake and Fire – Enduring Lessons for Fire Protection and Water Supply, EarthquakeSpectra, Volume 22, No. S2, pages S135 – S158.

19. Scawthorn, C.R., August 24, 1986. Modeling of Fire Following Earthquake. U.S NationalConference On Earthquake Engineering, August 24, 1996.

20. Scawthorn, C.R., 1992. Fire Following Earthquake – Conflagration Potential in the Greater LosAngeles, San Francisco, Seattle and Memphis Areas, EQE International, prepared for NaturalDisaster Coalition.

21. Scawthorn, C.R., 2003. Fire Following Earthquake, Earthquake Engineering Handbook,CRC Press LLC.

22. SFFD, Division of Support Services, March 1996. Proposed $51.9 Million Bond Issue,Improvement of Fire Protection Facilities and Systems.

23. SFFD, Division of Support Services, August 2002, Revised January 31, 2005, RevisedOctober 18, 2006. Proposed $ 117.4 Million Bond Issue, Maintenance and Improvement ofthe Auxiliary Water Supply System.

24. Scawthorn, C.R., Cowell, A.D., Borden, F., March 1998. Fire Related Aspects of NorthridgeEarthquake, National Institutes of Standards and Technology, NIST-GCR-98-743, EQEInternational, Inc. San Francisco.

25. SFPUC, December 2003. Draft Wastewater System Reliability Assessment Baseline FacilitiesReport.

26. USGS, 1999. Earthquake Probabilities in the San Francisco Bay Region: 2000 to 2030 – ASummary of Findings. Open File Report 99-517, Online Version 1.0.http://geopubs.wr.usgs.gov/open-file/of99-517/

27. USGS, 1992, The Loma Prieta, California, Earthquake of October 17, 1989 – MarinaDistrict, USGS Professional Paper 1551-F, O’Rourke, T.D, Editor.

28. Van Dyke, S. (Superintendent, Bureau of Engineering and Water Supply, San FranciscoFire Department); “San Francisco Fire Department Water Supply System”; VirtualMuseum of the City of San Francisco; 1997.

29. National Fire Protection Agency (NFPA), October 2007. 25 Largest Fire Losses in U.S.History (in 2006 dollars).http://www.nfpa.org/itemDetail.asp?categoryID=954&itemID=23352&URL=Research%20&%20Reports/Fire%20statistics/Deadliest/large-loss%20fires

http://geopubs.wr.usgs.gov/open-file/of99-517/

http://www.nfpa.org/itemDetail.asp?categoryID=954&itemID=23352&URL=Research

Appendix B

auxiliary water supply system (awss) study

Documents