You are here:
DEVELOPMENT OF SANITARY SEWER OVERFLOW ANALYSIS AND PLANNING (SSOAP) TOOLBOX
Citation:
LAI, DENNIS, S. VALLABHANENI, C. CHAN, E. H. BURGESS, AND R. FIELD. DEVELOPMENT OF SANITARY SEWER OVERFLOW ANALYSIS AND PLANNING (SSOAP) TOOLBOX. Presented at WEF 2006 Collection Systems Conference, Detroit, MI, August 06 - 09, 2006.
Impact/Purpose:
To inform the public
Description:
Rainfall Derived Infiltration and Inflow (RDII) into sanitary sewer systems has long been recognized as a source of operating problems in sewerage systems. RDII is the main cause of sanitary sewer overflows (SSOs) to basements, streets, or nearby streams. RDII can also cause serious operating problems at wastewater treatment facilities. Thus, there is a need to develop proven methodologies and computer tools to assist SSO communities in developing an optimal capital improvement program that is in line with the projected annual capital budget and provides flexibility in future improvements. The Nation’s sanitary-sewer infrastructure is aging, with some sewers dating back over 100 years. Nationwide, there are more than 19,500 municipal sanitary sewer collection systems serving an estimated 150 million people and about 40,000 sanitary sewer overflow (SSO) events per year. Because of concerns of potential health and environmental risks associated with poor performance of many of these systems, the U.S. Environmental Protection Agency (USEPA) had plans to add control and mitigation of SSOs to the existing National Pollutant Discharge Elimination System (NPDES) permit requirements. Though not yet formally adopted, the proposed Capacity, Management, Operation, and Maintenance (CMOM) program for collection and treatment systems is being widely accepted as good practice by many municipalities. To assist municipalities in developing plans to mitigate SSO problems, the USEPA signed a cooperative research and development agreement (CRADA) with Camp, Dresser, and McKee, Inc. (CDM) to develop a public-domain Sanitary Sewer Overflow Analysis and Planning (SSOAP) Toolbox. The CRADA will also prepare a technical guide for analyzing infiltration/inflow, performing capacity analyses of sanitary sewer systems, and developing SSO control plans using the toolbox. The toolbox is largely developed and the USEPA plans to release a beta version to the public in early 2007. The SSOAP Toolbox integrates the existing database of a sanitary sewer system and contains five functional tools for: Database Management, RDII Analysis, RDII Hydrograph Generation, SSOAP-SWMM5 Interface, and Sewer Flow Routing (SWMM5). The Database Management Tool serves as the command center of the toolbox. It provides interface with several external data sources (sewer systems, sewer flow and rainfall data), and interacts with other SSOAP tools and exchange data. The RDII Analysis Tool currently includes only the “RTK” method as used in the USEPA SWMM4 and SWMM5. The method uses up to three triangular unit hydrographs to estimate the fast, medium, and slow RDII responses. The R parameter is the fraction of rainfall volume entering the sewer system as RDII, T is the time to peak, and K is the ratio of time of recession to T.