Rainfall Derived Inflow and Infiltration (RDI/I) Study
Metropolitan Sewer District of Greater Cincinnati
EMH&T completed a Rainfall Derived Inflow and Infiltration (RDI/I) study in five separate sewer areas for the Metropolitan Sewer District of Greater Cincinnati (MSDGC), Cincinnati / Hamilton County, OH. As part of their commitment to addressing an EPA Global Consent Decree, MSDGC is required to complete rehabilitation projects to reduce RDI/I and eliminate Sanitary Sewer Overflow (SSO) activations during a typical year. The objective of the studies was to develop I/I reduction and capacity enhancement recommendations. Using data from previous reports, maintenance records, field investigations, flow monitoring data, and a hydraulic analysis, our team was able to provide recommendations without engaging in an exhaustive sanitary sewer evaluation survey. The RDI/I program was outlined as one of the recommended capacity sustaining programs and a key ingredient to success in the separated sewer areas. As such, protocols were needed to guide decisions, capture best practices, and apply consistent standards across the program. The District anticipated that due to the numerous sources of RDI/I, and the diversity of site-specific conditions found, a robust set of solutions for RDI/I control would be required. It then resulted in the development of specific RDI/I projects, and an overlay of existing maintenance, rehabilitation, and capital improvement programs to prioritize investments to areas of operational deficiencies (i.e. SSOs and SBUs) in a preventative, asset management approach.