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New York CityWater Supply System
Professor ChangCIEN E3004
Final Project ReportApril 30, 2013
Group 10: Nida Dangra, Nikita Gupta, Luke Henderson, and Jakub Karas
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Executive Summary
This report provides description, issues and solutions of the New York City Water Supply
System. There were several key questions which were asked in the planning portion of this
project and these included the financing of the system, the transportation of water from its source
to the taps, the treatment it receives during that voyage, and the threats and vulnerabilities which
it faces every day.
The system is financed based on revenue bonds issue by one of the institutions involved
in the O&M of the system: the NYC Municipal Water Finance Authority (NYW). Since
conception, the NYW is also responsible for paying off the general obligation bonds issued years
ago to build the system.
The Underground Network section describes the issues with the current piping between
the reservoirs in upstate New York and taps in NYC. As its discussed, the current piping is
constantly monitored and replaced by portions as the need arises. Thats also why the cost of
replacing the aging infrastructure to raise the standards will be spread out over time and will not
be too great to bear.
Next the singular characteristics and treatment of water are discussed. In this case it had
been found that NYC water is only minimally treated but multibillion dollar investments have
been made to prepare the city for the need to treat its water in the future.
Lastly, vulnerabilities and threats to the system have been investigated. From among
those, two major ones have been discussed: terrorism and climate change. The DEP responded to
the first one with increased monitoring of the system and preparation of post-attack plans while
the second one has been improved via integration with other infrastructure systems to ensure a
quick response to a weather crisis.
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Table of Contents
Introduction Page 1Institutional Issues Page 1Underground Network Page 3
Water Filtration Page 7Vulnerabilities Page 9Conclusion Page 12References Page 13Appendices Page 15
Appendix A
Figure 1. New York Citys Water Supply System Page 15Figure 2. New York City Distribution Page 15Figure 3. Water and Sewer Service Line Page 15
Figure 4. Automated Underwater Vehicle Page 15Figure 5. Geology along Delaware Aqueduct Page 16Figure 6. Accessibility of Wawarsing and Roseton Page 16Figure 7. Sectional View of Tunnel and Potential Leak Pathways Page 16Figure 8. Planned Internal Grout Repair Page 16Figure 9. Internal Grout Repair Process Page 16Figure 10. Bypass Tunnel Page 17Figure 11. Elements and vulnerable points in a general water supply system Page 17
Appendix B
Table 1. Natural hazards and human related threats to a water supply system Page 17
Appendix C
PowerPoint Presentation Page 18
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Introduction
The New York City Water Supply System is one of the largest and most functional in the
world. It dates as far back 1776 when the first reservoir was constructed. Since then it had grown
steadily and, as it stands today, it serves 9 million people with over 1.2 billion U.S. gallons of
minimally treated water daily. It is managed by 3 agencies, which work independently of the
New York City government. The purpose of this paper is to examine different issues associated
with this system and to relate them to some of the concepts covered in class. Our group decided
to focus on four issues, none of which is independent of each other. These topics include
institutional issues and the financing of the system, underground network and the transportation
of water from the reservoirs to our taps, filtration and treatment of water, as well as
vulnerabilities and various threats to this system.
Institutional Issues
There are three main institutions responsible for the operation, maintenance, and
financing of the New York Citys Water Supply System. The largest of them is the New York
City Water Department of Environmental Protection (DEP). It is responsible for the operation
and maintenance of all the assets (bridges, reservoirs, aqueducts, etc.) to ensure the delivery of
drinking water to over 8 million inhabitants of the Greater New York area. The financing is
performed by The New York City Municipal Water Finance Authority (NYW). This entity
provides the funding necessary for O&M and new construction projects through the issuance of
bonds, commercial paper and other obligations.1The last agency involved is the New York City
Water Board whose responsibility is to set the rates for water and sewer usage as dictated by the
costs of operation and maintenance. The Water Board is also responsible for collecting the
payments from the users. With this kind of varied institutional power, the issue to be discussed
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would be the discrepancy between the funding needed (NYW) and the amount of taxes/rates put
on people and maintaining the balance between the two.
Initially all the components of the water and sewer system were under the control of
NYCs government and in the same bag with all other investments such as roads, airports,
transportation system, etc. Back in the day the financing of all these components was based on
general obligation (GO) bonds. These bonds are generally repaid based from the taxes and other
revenue generated by all the infrastructure nodes in a given municipality (in this case NYC). This
changed after 1984 when the authority on the system changed over to NYW and the Water
Board. This was a pretty big change for the customers who switched from paying a fixed price
based on frontage and number of piping fixtures to paying for the amount of water actually used.
In terms of finance, the GO bonds were replaced by the revenue bonds which are meant to pay
for the expenses of the water system and sewer system and be repaid based on the revenue
generated by the system alone. This redirection of power created a problem, however: what to do
with all the repayments on the GO bonds issued before 1984? Which entity should take care of it
and in what way?2
The issue was solved on the promise that a portion of the water and sewer system revenue
will be handed over to NYCs government to pay for the GO bonds. The amount of the
transferred revenue became problematic and remains unclear until this day. It had been agreed
that the City will get either the debt service of the GO bonds or 15% of the debt service of the
revenue bonds. This formula worked fairy well for about a decade but became controversial in
the last few years when the NYC government started making millions of dollars on the revenue
since the debt service of the GO bonds decreased over time.3What is the solution in a situation
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where a large portion of the water and sewage revenue goes to the government based on a 30
year old law?
An obvious solution has been proposed by the New York City Comptroller who argued
that the government is not entitled to all that revenue and that it should be split between new
investment in water and sewage system or lowering the rates for the customers. The government
disagreed and the problem has remained. Without knowing all the facts it appears, as its often
the case where money is involved, that the government acted selfishly and, unless the money has
been put into major works of utmost importance, it has bit its own tail. This revenue, totaling
about $500 million could be utilized for much needed repairs on this aging water supply system.
It could also be put aside for future works or used to repay the debts of the water and sewer
system. Thus, as it stands and from the point of view of the water system, the money had is being
wasted when it could be used in more worthwhile ways.
Underground Network
Water supply in New York City comes from three individual sources and they are the
Catskill/Delaware supply system, the Croton supply system, and the groundwater supply in
southeastern Queens. Water from the reservoirs comes to New York City through three main
pipelines, the New Croton Aqueduct, the Catskill Aqueduct, and the Delaware Aqueduct (Figure
1). Water is distributed throughout New York City through three water mains. Tunnel No. 1 and
Tunnel No. 2 were put into service in 1917 and 1936 respectively. Tunnel No. 3 is still under
construction. Stage 1 of Tunnel No. 3 is expected to go into service by the end of 20134(Figure
2). Tunnel No. 1 and Tunnel No. 2 have not been inspected or repaired since the first time they
were put into service. One of the big reasons for the construction of Tunnel No. 3 is to allow the
DEP to maintain the performance of the drinking water system so that there will be no
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interruption to service while Tunnel No. 1 and Tunnel No. 2 are being rehabilitated. Tunnel No.
3 will also provide expanded distribution as the population of the city is expected to increase by
1.1 million between 2000 and 2030.5Overall, the reliability of the New York City Water Supply
System will increase.
There have been allegations made that the New Croton Aqueduct, which is over 100
years old is in serious need of repairs.6Statements from the DEP supporting or refuting such
claims have not been found. However, more than 90% of the water comes from the Delaware
and Catskill Aqueduct, so the New Croton Aqueduct may not be considered critical. Also, in
2011, 100% of the citys drinking water came from the Catskill/Delaware Supply.
7
There can be
multiple reasons for this. The three aqueducts were designed and built with multiple
interconnections to allow flexibility and exchange of water. Other than redundancy, in case of
pipe leaks and breaks, this allows for mitigation in case of localized droughts or excess water.
Either the DEP was taking from the Catskill/Delaware supply to recover reservoir levels in the
other supplies or was conducting reviews and checks on the other systems. There was a press
release in November 2011 stating that the reconstruction of five dams in the Croton Watershed
had been completed.8 Since the DEP does not state in the 2011 Drinking Water Supply and
Quality Report, the reason for only the Catskill/Delaware supply being the source of drinking
water in 2011, it may be any combination of above stated reasons or something else entirely. It
can be said though, that the New Croton Aqueduct, which may be in serious need of repair, is
currently not experiencing heavy usage.
It is important to correct leaks in the systems as soon as possible. Leaks can contribute to
increased flow into wastewater systems, can reduce level of water in reservoirs unnecessarily,
and if left unattended, lead to severe water damage such as pipe bursts and erosion of
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surrounding and supporting earth foundation. For customers it can lead to a spike in the water
bill. In NYC, homeowners are responsible for service lines that run from the building to the
municipal service lines in the street (Figure 3). DEP has a program for electronic alerts in case of
a spike in water usage and a Water and Sewer Service Line Protection Program or insurance
program in case of damage. For municipal service lines, the DEP has the Leak Detection
Program. Every neighborhood gets checked at least once every three years. Sophisticated
listening equipment is used to check every water main for leaks by listening to the flow of water
in water mains. Leaks can be identified by a distinctive noise pattern that is produced in water
flow. Approximately 500 leaks are found each year.
9
For leaks, proper operation and
maintenance is important to prevent high future capital costs in repairing pipes or foundations.
One huge leak repair project is the Delaware Aqueduct Leak plan. The DEP has been
monitoring leaks in the Delaware Aqueduct Rondout-West Branch Tunnel for more than a
decade through geological investigations, well monitoring, tunnel flow monitoring, surface
expressions monitoring, and Automated Underwater Vehicle (AUV) inspections (Figure 4). The
Delaware Aqueduct passes through a series of rock layers at 30 oangles (Figure 5). The cracking
occurs at two points along the aqueduct, Wawarsing and Roseton (Figure 7). The cracking areas
are located near and at the limestone layers. Limestone is considered poor geologysince it is
relatively soft and water/acid soluble when compared with shale or sandstone.10The Wawarsing
Public Advisory Committee considered several concepts and ruled out the ones that were
unfeasible or unreliable. Repairing from exterior would be unreliable since it involves excavation
and then filling, which may not be done properly. A parallel tunnel would be very expensive,
take decades, and would be unnecessary. Repair from interior would involve stopping water
traffic and would be under a time constraint. A bypass would be feasible but exact locations of
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leakages are unknown so no guarantee that whole leakage area is bypassed. The Wawarsing area
has 485 linear feet of cracking. It can be easily accessed and there is no risk to tunnel flooding
(Figure 6). Internal grout repair would therefore be used for Wawarsing. Internal grout repair
would involve unwatering the tunnel, drilling grout holes, and injecting grout (Figures 8, 9). In
the Roseton area there is 5200 feet of cracking, which is a significantly larger area and would
require shutting down water traffic for a much longer time if repaired internally. It also has poor
tunnel access and a risk of flooding since it is at a low point in the tunnel (Figure 6). This led to
the bypass tunnel solution in Roseton (Figure 10).10The Delaware Aqueduct carries more than
50% of NYCs drinking water.During the connection to the bypass tunnel, the city will need an
alternate source of water. The groundwater supply system in Queens will be reactivated before
2020 when the connection is planned to be made. Before reactivation, the groundwater facilities
will be upgraded and repaired to achieve reliable operation, maximum capacity, and drinking
water quality standards.11
The total cost of the project has been estimated to be $1.19 billion. A simple analysis can
be done to see how many days it will take after the completion of the project for the project to
pay for itself. The current water rate is $3.39 per 100 cubic feet or approximately 748 gallons.12
It will be assumed that the water rate charged will increase in time due to inflation and thus the
future value of water in present terms will be the same as the present value of water. 13An
optimistic approach will be taken to this analysis and it will be assumed that the project saves 35
million gallons of water every day. So the amount of money saved every day will be:
(35,000,000 / 748) $3.39 = $158,622.99. So the number of days till the project will be
completely paid for: $1,190,000,000 / $158,622.99 = 7,502.06 days or about 20 and years.
This may seem like a long time, however the Delaware aqueduct has been in use since 1945 or
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68 years. If the service life of the aqueduct can be significantly extended by this project then
hopefully it will last longer than 20 years so the project can be justified. It should be noted that
if the leaks arent fixed they could potentially damage the pipe structure as well and increase
leakage. This potential for disaster avoidance was not considered in the analysis.
Construction projects regarding the system of pipes and shafts that were discussed and
mentioned by the DEP never indicate a complete replacement of a tunnel or aqueduct. The
advantage in the construction of a network of pipes is that it can be replaced or constructed in
parts compared to replacing a bridge, where most of the work has to be done all at once and
continuously. For this reason, the term service life may not apply to such systems. Any length of
piping that seems to be failing in performance or reliability can be replaced without disrupting
the whole system. It can be said that new technology or standards in piping and aqueducts may
require a complete overhaul of the system, but even this can be done in parts. For example, if a
portion of the old technology system fails, replacement by the new technology can be limited to
that portion with sufficient connection between the two types of piping. Thus replacement of the
old system will be gradual and the high initial cost of complete replacement will be spread out
over a longer period of time.
Water Filtration
With a volume of over one billion gallons of water delivered each day, it comes as no
surprise that water treatment and filtration is no trivial detail for the city; any minute
contamination of the water would affect millions in the city and around.14Astonishingly enough,
despite this huge responsibility, New York City is the largest of the few major cities in the
United States, which does not treat its water before distribution (though it does undergo basic
processes such as chlorine addition). This is made possible by a couple of factors such as the
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citys long standing record in water purity and a series of preventive measures put in place to
assure the continuation of this record. Despite these measures and the natural quality of the
water, there is an understanding that tightening water quality standards as well as development in
and around the watersheds will eventually lead to the mandatory treatment of incoming water,
and the city is already preparing for future requisites.
In order to stay exempt from filtration/treatment, every year New York Citys DEP must
submit to the New York State Department of Health a petition to be exempt from water
filtration.15This petition is backed by careful analysis and data samples of water quality, proving
that the untreated water attains the set standards for purity, turbidity, and cleanliness. This
natural purity comes from the natural quality of the water in the watersheds, which in turn is
conserved by conservation measures put in place by the DEP.16 These measures include the
acquisition, by the state, of land around the watersheds which drain directly into the lakes and
rivers, the close monitoring of pollution levels in the area to pinpoint pollutants if they are
present, and cooperation with private land-owners in the area who have agreed to take particular
caution with their use of chemicals and the run-offs from their lands. These measures have so far
been effective in keeping the water quality above standard, even in periods of draught, where
low water levels tend to raise average pollution levels.
One exception to this flawless record has recently been found in the oldest of the
watersheds: the Croton watershed. Indeed, in recent years (starting in 1998) it has been found
that under drought conditions, the reservoir systems water has yielded sub-benchmark water
clarity.17Though having no impact on health, water clarity remains an important consideration in
quality control as it affects taste and confidence in the water. 18To deal with this problem, the
city had to build its first permanent water treatment plant to service water coming from the
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Croton aqueduct. It is about to become fully operational. This move seems to be reflective of the
gradual shift to treated water on the citys behalf.
Indeed, with the continued urbanization of the watershed areas and thus the disruption of
the local water cycles, the city is predicted to continue this gradual transition to filtered water.
Already, the city has invested a staggering $2.8 billion in the construction of the Croton system
treatment plant and has plans to build a set of UV water treatment plants for the other two
reservoirs in Westchester at a cost of $104.6 million. 19 These treatment plants would use
powerful UV illumination to kill most pathogens in the water. These new treatment plants would
have the capacity to treat up to 2 billion gallons of water a day, more than enough to catch up
with the citys water needs by 2014.
As we have seen, New York City benefits from access to uncharacteristically pure water,
which it uses daily without the need for filtration. However, guided by foresight and caution,
massive investments have been made in the last decade to prepare the city for a switch from
untreated to treated water. These expenses, though costly, should help assure the continuation of
clean water supply to the city for decades to come.
Vulnerabilities
The New York City water supply system is also vulnerable to certain external factors that
include terrorist attack or sabotage, as well as climate changefactors that are currently
relevant. The September 11thattacks on the World Trade Center in New York City was a major
turning point for the security of water infrastructure, as attention was drawn to the security of
many institutions, facilities, and systems, including water supply systems and water quality
infrastructures. These systems have long been recognized as being potentially vulnerable to
terrorist attacks of various types, including physical disruption, bioterrorism, chemical
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contamination, and cyber attack.20For example, there was a reported threat to contaminate the
water supply of New York City with nerve gas in 1972 that never actualized; this shows terrorist
attacks were always a concern, but became a heightened concern after 2001.
With sabotage and terrorist attacks being a growing concern, research was conducted on
water supply systems in order to understand and control vulnerabilities because water is a
fundamental resource that society and human welfare depends on. A typical water supply
system, such as the one in New York City, consists of water sources, raw water transmission
pipes, water treatment plants, and water distribution networks.21Considering this, five vulnerable
areas were identified as opportunities for both natural and human-related influences due to their
accessibility, as shown in Figure 11: (1) water sources (e.g., river); (2) water treatment plant that
removes impurities and harmful agents and makes water suitable for all uses; (3) water
distribution pipelines that deliver clean water; (4) storages (tanks); and (5) other facilities the
water is transported to.22
The numerous types of risks and threats that New York City, or any city, could be
affected by are shown in Table 1 and can be categorized into natural hazards and human-related
threats. These varied threats show that any water infrastructure system is also highly linked with
other infrastructures, especially electric systems that control power and its restoration and
chemical plants that treat the waterconnecting the security of all of these systems to the overall
security of the water supply system. One advantage that New York City has in situations of
power loss, though, is that 95% of the total water supply is supplied by gravity and only about
5% of the water is regularly pumped to maintain the desired pressure.23
After the terrorist attacks of 2001 brought to attention the vulnerability of the water
infrastructure in New York City, water system security recommendations were made by state and
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local governments. Interestingly, in the aftermath of these attacks, research shows that the
citizens of the city believed that it was not following through with post-September 11
recommendations to increase security for its water supply system, leaving it vulnerable to
possible terrorist attacks, according to a report from a state legislative committee.24Perhaps not
directly in response to this, the DEP increased security over New York Citys water system, even
though an attack on the water supply is believed to be less likely than other attacks due to the
difficulty of carrying it out. The risk is mitigated by the purification process and detection of
toxins near the upstate reservoirs, before the water actually reaches the New York City
reservoirs. Nevertheless, the DEP restricted access to water supplies and supply system
components (such as tunnels and aqueducts), barred all fishing and hunting, and monitored and
patrolled restricted areas by helicopter and fixed-wing aircraft.25Despite these precautions, it
was believed that the number of police officers was not enough to patrol the watershed, which
extends 125 miles north of the city.26Thus, over the course of five years, the number of positions
was increased from 39 to 142. The NYC government also increased the number of daily water
samples it takes.27
In the aftermath of the attacks, to help restrict access to sensitive areas, DEP actively
sought to acquire the property surrounding those areas and has a large police force and contracts
for security guard services. In August of 2002, the Bioterrorism Act was signed and this included
the creation of an emergency response plan and an analysis of vulnerability to terrorist attacks. In
New York State, all community water systems that serve more than 3,300 people are required by
State Public Health Law to prepare and submit a water supply emergency plan (ERP). As stated
by the New York State Department of Health, ERPs need to be complete, up to date, organized
to find important information quickly, and readily available when needed. Emergency response
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plans must include an assessment of vulnerability to water supply contamination and disruption,
including the possibility of terrorist attack.28The NYC government increased its monitoring in
2006 with tiny fish called bluegills that react rapidly to minute changes in water purity.29
Climate change is another recently relevant topic that highlights the vulnerabilities of the
New York City water supply system. Although climate change affects wastewater management
in the city more than it does the water supply system, the city has started thinking about
precautions to take with the sea level rise, increased coastal flooding, more frequent and intense
rainstorms, and increased annual precipitation. 30 The NYC government has started to take
precautions included in the 2007 city plan by considering integration of the water supply system
with other regional systems to increase flexibility in the event of localized disruptions, as well as
adding construction of increased redundancy in the water supply infrastructure.31
Conclusion
Since Roman times, there has been an understanding that water supply regulation and
infrastructure is a necessity for any large city to prosper. With 8 Million people, New York City
stands as one of the worlds largest cities, and quenching its thirst daily falls to a complex
network of interdependent infrastructure and cooperating institutions. To continue to operate on
a daily basis, yielding an average of 1.2 billion gallons a day, this system has to be constantly
serviced, surveyed and studied to minimize vulnerabilities and assure its sustainability for
tomorrows generation and the next, allowing the city to continue its economic growth without
having to pause for a drink.
References
1"About NYW." The Official Home Page of The NYC Municipal Water Finance Authority. NewYork City Water Board. Web. 28 Apr 2013. .
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2Jain, Rahul, Maria Doulis, and Charles Brecher. "New York Cit'ys Water and Sewer System: Isthe Rent Too Damn High?." (December 2011): Web. 21 Apr. 2013..3Jain, Rahul, Maria Doulis, and Charles Brecher. "New York Cit'ys Water and Sewer System: Is
the Rent Too Damn High?." (December 2011): Web. 21 Apr. 2013..4"City Water Tunnel No. 3."NYC Department of Environmental Protection. N.p.. Web. 27 Apr2013. .5The City of New York. Department of City Planning. New York City Population Projections byAge/Sex & Borough, 2000-2030. 2006. Print..6"Threats to NYC's Tap Water."Riverkeeper: NY's clean water advocate. N.p.. Web. 27 Apr2013. .7The City of New York. Department of Environmental Protection. New York City 2011Drinking Water Supply and Quality Report. Web..8"DEP Rebuilds Five Dams in the Croton Watershed." NYC Department of EnvironmentalProtection. N.p., 15 Nov 2011. Web. 27 Apr 2013..9"DEP Announces Leak Detection and Catch Basin Cleaning Locations for July."NYCDepartment of Environmental Protection. N.p., 08 Jul 2004. Web. 27 Apr 2013..10The City of New York. Department of Environmental Protection.Delaware Aqueduct LeakAction Plan. Wawarsing Public Advisory Committee: 2010. Web..11The City of New York. Department of Environmental Protection. New York City 2011Drinking Water Supply and Quality Report. Web..12The City of New York. New York City Water Board. Water and Wastewater Rate Schedule.2012. Web. .13Randall, Judy. "New York City seeking 5.6 percent water rate increase; Staten Island publichearing April 29." Silive. N.p., 05 Apr 2013. Web. 27 Apr 2013..14"About Watershed Protection."About Watershed Protection. NYC DEP, n.d. Web. 25 Apr.2013.15"Croton Water Filtration Plant." Croton Water Filtration Plant. NYC DEP, n.d. Web. 25 Apr.2013.16"Regulatory Background."Regulatory Background. NYC DEP, n.d. Web. 25 Apr. 2013.17"History of New York City's Water Supply System."History of New York City's Water SupplySystem. NYC DEP, n.d. Web. 25 Apr. 2013.18"The Croton Water Filtration Plant Project." The Croton Water Filtration Plant Project. NYCDEP, n.d. Web. 25 Apr. 2013.19Risinit, Michael. "Westchester Aims to Join NYC on Water Plant for UltravioletTreatment." The Journal News. Journal News, 26 Sept. 2012. Web. 25 Apr. 2013.20"Attacks on Water Supplies." Terrorism Research & Analysis Consortium. Web. 27 Apr 2013..
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21Saadati, Sara. "Vulnerability Assessment and Risk Reduction of Water Supply Systems." N.p.,n.d. Web. 27 Apr 2013.22Saadati, Sara. "Vulnerability Assessment and Risk Reduction of Water Supply Systems." N.p.,n.d. Web. 27 Apr 2013.23
http://www.nyc.gov/html/dep/html/drinking_water/history.shtml24"Report: NYC water system still vulnerable." CNN.com. CNN, 19 May 2002. Web. 27 Apr2013. .25Lloyd, Emily. "Security Over New York Citys Water System." State of New York, 25 Apr2006. Web. 27 Apr 2013. .26Worth, Robert. "New Concern About Security Of the Water Supply." The New York Times,14 Oct 2001. Web. 27 Apr 2013. .27Gleick, Peter. "Water and Terrorism." Pacific Institute, 14 Aug 2006. Web. 27 Apr 2013..28"Preparing Emergency Response Plans - Drinking Water Systems." Department of Health.Web. 27 Apr 2013..29Zeranski, Todd. "NYC Uses Fish to Guard Water Supply From Terrorists."Bloomberg.com.N.p., 23 Aug 2006. Web. 27 Apr 2013..30Levine, Larry. "New Report Highlights Vulnerability of NYC Water Infrastructure to ClimateChange -- and the Citys Efforts to Prepare." SWiTCHBOARD. N.p., 26 Jul 2011. Web. 27 Apr2013. .31"Local government perspective on adapting water management to climate change." WorldWater Council. N.p.. Web. 27 Apr 2013..
Appendix A
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Figure 1. New York Citys Water Supply System Figure 2. New York City Distribution
Figure 3. Water and Sewer Service Line
Figure 4. Automated Underwater Vehicle
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Figure 5. Geology along Delaware Aqueduct
Figure 6. Accessibility of Wawarsing and Roseton
Figure 7. Sectional View of Tunnel and Potential Leak Pathways Figure 8. Planned Internal Grout Repair
Figure 9. Internal Grout Repair Process
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Figure 10. Bypass Tunnel
Figure 11. Elements and vulnerable points in a general water supply system31
Appendix B
Table 1. Natural hazards and human related threats to a water supply system31
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Appendix C
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