Preparing for CMOM; Challenges, opportunities and new approaches?

This paper will address the various aspects of the Sanitary Sewer Overflow (SSO) rule as it affects MSD and possibly other agencies / operators and municipalities with a focus on a new tool for estimating rainfall dependent inflow and infiltration (RDII). The statistical analysis will identify the principal factors that influence RDII such that they can be incorporated into the modeling and design efforts of relief or replacement sewers in a quantifiable manner. The method employed is a statistical model approach to predict RDII at any point in a collection system when applied to the principal sewershed characteristics. The model has stochastic and regression features in establishing RDII in a collection system when adequate resources are not available. With this model, the objective is to provide planners and designers with a tool to better estimate the RDII volumes, flows, and physical causes of excessive stormwater in a sanitary collection system. The United States Environmental Protection Agency (US EPA) is proposing in the new SSO rule comprehensive strategies in order to improve water quality from point source discharges. The SSO rule will require owners of the sanitary collection system to exercise decision-making skills so that the utility, agency or municipality will be in the best position possible to comply with the rule. These decisions will have significant impacts in both the near and far terms in regards to resources required from the local, state and federal governments and citizens. The SSO rule has four themes that will need to be a part of the owner's strategic approach: 1. Capacity Assurance, Management, Operations and Maintenance (CMOM) program 2. A management approach for each sewershed or treatment area 3. Prohibition provision for overflows. 4. Public notification, reporting and record keeping requirements.