United States
Environmental Protection
Agency
RESEARCH PROJECT
National Risk Management Research Laboratory
Water Supply and Water Resources Division
Urban Watershed Management Branch
CONDITION ASSESSMENT OF WASTEWATER COLLECTION SYSTEMS USING THE
SANITARY SEWER OVERFLOW ANALYSIS AND PLANNING (SSOAP) TOOLBOX
IMPACT STATEMENT
The Sanitary Sewer Overflow Analysis and Planning (SSOAP)
Toolbox can serve as the foundation of wastewater
collection system infrastructure research, among several
applications, for analyzing monitored flow data to prioritize
where to inspect, monitor, and to assess the performance of
rehabilitation activities. In addition, it will support program
offices in adding the conducting capacity, operation and
maintenance requirements to the National Pollutant
Discharge Elimination System (NPDES) permits and help
municipalities identify sanitary sewer overflow problems and
develop a sensible control plan to meet their NPDES permit
requirements.
BACKGROUND:
In 2002, the U.S. Environmental Protection Agency (EPA) entered into a cooperative research and development
agreement to develop a public domain computer analysis and modeling toolbox. The toolbox, SSOAP, contains a suite of
computer software tools to perform capacity analysis and quantify rainfall-derived infiltration and inflow (RDM) Analysis
in sanitary sewer systems. The current state of technology for condition assessment of sewer systems is by visual
examination of sewer conditions using rather time consuming and expensive field investigations employing the
conventional closed circuit television or newer emerging technologies (e.g., sonar, laser, ultrasonic, and infrared). The
RDM prediction methodology in the SSOAP Toolbox offers an effective means to design a focused condition assessment
program and maximize the success of field investigation efforts.
DESCRIPTION:
The National Risk Management Research Laboratory, of EPA's Office of Research and Development, has funded this
research project in support of its Aging Water Infrastructure (AWI) Research Program. The SSOAP Toolbox contains five
functional tools for Database Management, RDM Analysis, RDM Hydrograph Generation, SSOAP-Stormwater
Management Model 5 (SWMM5) Interface, and Sewer Flow Routing using SWMM5. SSOAP employs the RTK method (a
synthetic unit hydrograph method) to analyze the flow data collected within the sewer systems in both dry weather and
wet weather. This methodology uses three triangular unit hydrographs to represent the various ways that rainfall
contributes to RDM. The RDM volumes of three unit hydrographs are designated as Rl, R2, and R3. The total R-value is
the sum of Rl, R2, and R3. A high Rl value indicates that the RDM is primarily inflow driven. If more of the total R-value
is allocated to R2 and R3, this would indicate that the RDM is primarily infiltration driven. The distribution of R-values is
useful for establishing the relative sub-basin priorities and can be used to support the condition assessment and
subsequent system rehabilitation efforts.
National Risk Management Research Laboratory
Water Supply and Water Resources Division
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This project will (1) enhance the toolbox by adding a Global Information System interface to streamline and manage
data sewer systems and link inspection data with the geospatial location of a pipe and (2) demonstrate application of
SSOAP for condition assessment.
EPA GOAL: Goal #2 - Clean & Safe Water, Objective 2.1.1- Water Safe to Drink
ORD MULTI YEAR PLAN: Water Quality (WQ), Long Term Goal - WQ-3 Source Control
RESEARCH PARTNERS: Camp Dresser and McKee (COM), Inc.
EXPECTED OUTCOMES AND IMPACTS:
It is expected that this project will result in an increased acceptance of new and innovative technologies by decision
makers who adopt, regulate, and design infrastructure technologies. The expected outcomes and impacts of this project
also includes lowered cost and increased effectiveness of the design, operation, maintenance, rehabilitation, and
replacement of aging infrastructure; extended service life and functionality of existing conveyance systems; and reduced
life cycle cost.
OUTPUTS:
Current and expected project outputs include enhanced SSOAP; informational and hands-on workshops; peer-reviewed
journal articles; and conference proceedings.
RESOURCES:
Aging Water Infrastructure Research Program: http://www.epa.gov/awi/
Sanitary Sewer Overflow Analysis and Planning (SSOAP) Toolbox:
http://www.epa.gov/ednnrmrl/models/ssoap/index.html
EPA (2007). Computer Tools for Sanitary Sewer System Capacity Analysis and Planning (EPA/600/R-07/111)
http://www.epa.gov/nrmrl/pubs/600r07111/600r07111.pdf
EPA (2008). Review of Sewer Design Criteria and RDII Prediction Methods (EPA/600/R-08/010)
http://www.epa.gov/nrmrl/pubs/600r08010/600r08010.pdf
CONTACTS:
Dennis Lai, Principal Investigator - (732) 321- 6632 orlai.dennis@epa.gov
Steven Doub, Media Relations - (513) 569-7503 ordoub.steven@epa.gov
Michelle Latham, Communications - (513) 569-7601 or latham.michelle@epa.gov
National Risk Management Research Laboratory
Water Supply and Water Resources Division
www.epa.gov/nrmrl
EPA/600/F-09/042
October 2009
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