Sanitary-Sewer Overflow Control Strategy

This paper presents a strategy for the abatement of pollution from storm-generated sanitary-sewer overflows (SSO). Because of the great lengths of sanitary-sewer systems and their associated vast number of house-service laterals or building connections, it is often less expensive and more feasible to use alternatives to sewerline rehabilitation for infiltration/inflow (1/1) and SSO control. Extensive sanitary-sewer-system rehabilitation can: (1) be relatively costly; (2) take a long time to complete; and (3) be extremely disruptive to traffic, businesses, and property owners. 1/1 control studies have found that just correcting 1/1 in street sewers will not necessarily correct the problem because building connections contribute as much as 60% of the infiltration load. Building connection rehabilitation can be infeasible economically because of the shear number of connections or impractical because of the difficulty in dealing with property owners. Inflow elimination or reduction, cost-effective sewer rehabilitation, and collection system inspection with associated clean out and repair must be performed in all cases. In addition, an integrated economic and feasibility analysis using a combination of maximizing flow to the wastewater treatment plant and maximizing treatment capacity must be considered for controlling the remaining SSO. SSO can be abated using combined-sewer overflow (CSO) control methods. SSO and CSO are both mixtures of municipal sewage, stormwater, and ground water.