Recognizing the water quality problems associated with combined sewer overflows, and consistent with the goals of the Clean Water Act, the US Environmental Protection Agency issued a National Combined Sewer Overflow Control Strategy in 1989. The strategy reaffirmed that CSO’s are point source pollution discharges and subject to the requirements of municipal NPDES permits. The Strategy was expanded in 1994 to better facilitate implementation compliance by States and Municipalities and the Indiana Department of Environmental Management adopted this strategy in 1996. The Federal and State CSO control policies are divided into two separate phases with the first Phase being lower cost measures which can be implemented by municipalities to reduce the frequency, magnitude and duration of CSO’s. The Phase I measures are commonly referred to as the “Nine Minimum Controls” and consist of the following CSO reduction measures:
The City of Terre Haute completed a combined sewer overflow operational plan to determine how to effectively implement these nine minimum controls in the system in 1996. The plan was intended to provide a new baseline to evaluate the impact of CSO’s on the City’s receiving waters during the evaluation and implementation of the Phase II requirements which are included in the CSO Long Term Control Plan. The City staff has through its operational practices implemented the recommendations of the CSO Operational Plan which was updated in 2006. These practices include simple things such as cleaning inlets and sewers to ensuring the peak amount of flow is processed through the treatment facility before CSO’s occur. The operational plan is required to be updated through the implementation of the LTCP. The CSO Operational Plan is provided in the Resources Section.