CSO DISCHARGE REPORTING AND TRACKING

Like many combined sewer communities in the state of Indiana and across the United States, the city of Indianapolis is required to report combined sewer overflow (CSO) discharges to a state regulatory agency, the Indiana Department of Environmental Management (IDEM). The objective of this paper is to share how the city of Indianapolis used the sewer system hydraulic model to support preparation of CSO discharge monitoring reports (DMR), on a biannual basis, to meet National Pollution Discharge Elimination System (NPDES) permit reporting requirements. It also discusses how this approach significantly benefits tracking the progress of CSO reductions during and after implementation of the CSO long-term control plan (LTCP). The authors believe that the experience and techniques developed for Indianapolis can benefit other municipalities in addressing CSO control and compliance.