SSO EVALUATION AND REDUCTION USING DATABASE PROCEDURES

In January 2001, the United States Environmental Protection Agency (EPA) published the “Proposed Rule to Protect Communities from Overflowing Sewers,” also known as the Sanitary Sewer Overflow (SSO) Rule. The foundation of the SSO Rule entails the assessment of capacity and implementation of management, operation and maintenance procedures in the sanitary sewer system to reduce SSOs.The City of Phoenix sanitary sewer system consists of approximately 4,000 miles of sewer mains with approximately 85% of which are 8-inch diameter. The City of Phoenix is located in a desert climate. The sewer system has been constructed with adequate capacity for normal peak flows. Infiltration or inflow is generally minor. The majority of the SSOs are the result of grease or roots, with a small percentage attributed to construction activities or vandalism.URS was contracted to perform a cMOM Risk Assessment for the City of Phoenix. The scope of this project included investigation of the SSOs that occurred from 1996 through 2002. Each of SSOs in this time frame was studied to determine the cause of the SSO and to develop proposed mitigation steps to prevent recurrence of the SSO.Geographic Information Systems (GIS) were used as a basis for the study. Databases were obtained or created to organize information related to the SSOs, the sewer system, and pretreatment devices.