$EPA
www.epa.gov/nhsrc
technical BR
EPA's Water Security Modeling and
Simulation Research
Helping Water Utilities Provide Clean, Safe Drinking Water through
Advanced Computer Technology
Water distribution networks deliver drinking water to consumers through a system
of pipes, valves, pumps, and tanks. These
networks are vulnerable to accidental or
intentional contamination.
As part of U.S. EPA's Office of Research and
Development, the National Homeland Security
Research Center (NHSRC) provides products and
expertise to improve our nation's ability to respond
to environmental contamination caused by terrorist
attacks on our nation's water infrastructure,
buildings and outdoor areas.
NHSRC conducts research related to:
• Detecting and containing contamination from
chemical, biological, and radiological agents
• Assessing and mitigating exposure to
contamination
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contamination
• Developing risk-based exposure advisories
• Decontaminating and disposing of
Detecting contamination in distribution networks is difficult
because of the spatial extent of the systems, rapid flow rates,
and natural variability in water quality. In addition, distribution
systems are looped, resulting in mixing, dilution, and spread of
contaminants. The water industry needs technology that can
rapidly identify the presence of contamination in distribution
systems and guide decisions that minimize public health and
economic impacts and restore service to customers.
EPA's Water Security Modeling and Simulation Research
Program is developing technological innovations to meet the needs of the water industry. The program
is providing tools to help the water industry throughout the continuum of a water contamination incident:
rapidly detecting and interpreting changes in water quality, evaluating different response scenarios, and
assessing how best to decontaminate a distribution system. The program has released three software
tools and has plans to release additional tools. Available products include TEVA-SPOT (Threat
Ensemble Vulnerability Assessment Sensor Placement Optimization Tool), CANARY Event Detection
Software, and EPANET-MSX (a Multiple Species extension to the EPANET hydraulic and water quality
software). EPANET-RTX (a Real-Time extension to EPANET) is currently being piloted. A response
and decontamination toolkit is being developed and assessed for feasibility and sustainability.
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TEVA-SPOT
TEVA-SPOT is used by water utilities to optimize the number
and location of contamination detection sensors so that
economic and/or public health consequences are minimized.
TEVA-SPOT (Toolkit and Graphical User Interface) is
interactive, allowing a user to specify the minimization
objective (e.g., the number of people exposed, the time to
detection, or the extent of pipe length contaminated). It also
allows a user to specify constraints. For example, a TEVA-
SPOT user can employ expert knowledge during the design
process by identifying either existing or unfeasible sensor
locations. Installation and maintenance costs for sensor
placement can also be factored into the analysis. TEVA-
SPOT has been piloted to design sensor networks for the five cities participating in EPA's Water
Security Initiative.
The figure shows sensor locations (dots)
recommended by TEVA-SPOT to be added
to a water utility distribution system (lines).
CANARY Event Detection Software
CANARY enables water utilities to use water quality sensors for indicative
parameters (e.g., free chlorine, total organic carbon, and electrical A /CANARY
conductivity) to indirectly detect contamination incidents. The software "^^S^-^'^^^ljB^
uses mathematical and statistical techniques to identify the onset of abnormal water quality patterns.
Drinking water utilities use the software in conjunction with a network of water quality sensors to rapidly
detect contamination and to more accurately assess when and how they need to respond. The software
distinguishes between natural variations in water quality and unnatural variations that point to likely
contamination, and it sends an alarm when water utilities should investigate and respond. In addition to
achieving homeland security goals, CANARY can be used to detect operational problems such as
sensor failure or pipe breaks. CANARY was recognized as one of the top 100 new technologies of
2010 by R&D Magazine. It has been running continuously for more than two years at two large water
utilities.
EPANET-MSX
EPANET is a widely used computer program for modeling water flow and quality in drinking water
pipes. Its water quality component, however, is limited to tracking a single chemical species. In the real
world, chemicals and biological organisms react with substances in the water and on the pipe walls.
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EPANET-MSX was developed to model the complex interactions of multiple reaction species, thus
providing a more realistic prediction of water quality in a distribution system. EPANET-MSX enables
users to model reactions of interest to water utility operators such as chlorine loss, the formation of
disinfection byproducts, nitrification dynamics, disinfectant residuals, and adsorption to pipe walls.
Homeland security researchers are particularly interested in modeling the fate and transport of toxic
contaminants in drinking water distribution systems.
EPANET-RTX
Real-time modeling integrates hydraulic and water quality models with real-time field data to provide the
ability to forecast, hind-cast, and estimate current conditions at any point within a distribution system.
These conditions include such things as system pressures, flow rates and water quality. The ability to
accurately identify conditions in a distribution system and predict conditions given different operational
or contamination scenarios will help utilities meet operational, emergency response, and water system
planning goals.
A survey of its members conducted by the American Water Works Association indicated a high interest
in the ability to model in real time, and that many utilities will have the capability to use such software
when it becomes available. EPANET-RTX is currently being piloted at a water utility.
Response Toolkit
Water utilities need to evaluate response options following detection of a contamination event. A
common response to contamination in a water system is to open hydrants and flush poor quality water
from the system. However, some contaminants might not be
easily flushed from a water system, since they could bind with
biological films or adhere to corrosion products on the pipe
walls. As such, flushing alone may not decontaminate a water
distribution network. The proposed Response Toolkit would
provide utility operators with software to evaluate different
response and decontamination strategies. Components of the toolkit will likely include methods to
identify:
• Most probable location for the source of the contamination
• Best hydrant locations to flush contaminated water out of the system
• Best booster station locations to inject chlorine or other decontaminants
• Best sampling locations to pinpoint contaminated regions of the network and verify cleanup
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The Response Toolkit project is in the early stages. Researchers are evaluating the feasibility of the
different components of the toolkit for applicability in real-time contamination situations. Under
evaluation are the computational requirements required to run the software, real-time response
capabilities (coupling with EPANET-RTX), the ability to pre-plan response actions for water utilities
without real-time response capabilities, and the impacts of multi-species water quality modeling
(utilization of EPANET-MSX).
Summary
The Water Security Modeling and Simulation Research Program is developing products to help water
utilities detect contaminants and respond to incidents. The software tools are free to the public under
an open-source license and are made available via the EPA website (www.epa.gov/nhsrc). In addition,
several research and technical assistance reports are available on this website to assist users.
Contact Information
Technical Contacts:
Terra Haxton (haxton.terra@epa.gov)
Robert Janke (janke.robert@epa.gov)
Regan Murray (murray.regan@epa.gov)
General Feedback/Questions: Kathy Nickel (nickel.kathv@epa.gov)
July 2011
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