Continuous Calibration Promises Significant Savings in Meeting Wet Weather Compliance Requirements

The City of Columbus, Ohio Department of Public Utilities, Division of Sewerage and Drainage (DOSD) is undertaking a sanitary sewer system inflow and infiltration (I/I) remediation project in the Early Ditch Relief area on the west side of the City of Columbus. This project evaluates the area's sewerage and drainage systems to make specific recommendations regarding the removal and/or control of I/I to a ten-year level of service. The City has been concerned with the level of conservatism inherent in applying event-based design storms to predictive models. This paper summarizes the assumptions, procedures and modeling results that were used to develop a unique approach for hydraulic modeling of the sanitary sewer system, which has the potential to reduce the size and cost of capital improvement projects to correct the problems. The continuous calibration approach and how it was applied to the Early Ditch I/I Remediation Project is discussed and the estimated cost savings are presented.