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The Washington Suburban Sanitary Commission (WSSC), located in Montgomery County and Prince George's County, Maryland, is the sixth largest wastewater agency in the country. In 1995, the WSSC launched a 4.5-year, multimillion-dollar infiltration/inflow (I/I) analysis and sewer system evaluation survey (SSES) in a high profile, critical drainage basin. This basin, the Rock Creek Basin, has approximately 15,000 manholes, 595 miles of sewers ranging from 6 to 54 inches, a pump station, and the Rock Creek Storage Facility. Wastewater flow from the Rock Creek Basin discharges to the regional Blue Plains Wastewater Treatment Plant, located in the District of Columbia (D.C.). Occasionally, during wet weather conditions, Rock Creek's peak flow discharge limit of 56.6 million gallons per day (mgd) is exceeded.

The Rock Creek I/I Analysis project included traditional I/I and SSES elements — sewer mapping, computer modeling, flow monitoring, manhole inspection, smoke testing, flow isolation and measurement (I&M), television inspection, and cost-effectiveness analyses — but, it was unique in two regards: (1) the computerization of most project tasks and (2) the development of a Sewer Management Program (SMP) to facilitate the following:

Data collection, input, and analyses

Priority ranking of pipelines

Rehabilitation selection

Graphical output

The SMP included the development of a distinctive method for choosing the most economical rehabilitation methods based on current WSSC practice. This paper summarizes the results of the Rock Creek I/I Analysis project conducted by PEER Consultants, P.C., describes the tools that were developed to analyze the voluminous amount of data, and discusses the method that was used to prioritize and choose the most cost-effective solutions to repair all defective manholes and pipelines that were identified during the course of the project.

Document Type: Research Article


Publication date: 2000-01-01

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  • Proceedings of the Water Environment Federation is an archive of papers published in the proceedings of the annual Water Environment Federation® Technical Exhibition and Conference (WEFTEC® ) and specialty conferences held since the year 2000. These proceedings are not peer reviewed.

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