Sanitary Sewer Interceptor Corrosion Modeling and Corrosion Control Pilot Testing at Casper, Wyoming

The City of Casper operates an extensive wastewater conveyance system that includes the North Platte Sanitary Sewer Interceptor (NPSSI). The City and CH2M HILL developed a cost-saving tiered approach to assessing the NPSSI’s current condition. Following the assessment phase, the risk levels and remaining service life of the alignment were determined using CH2M HILL's SCREAM™ software from inspection information collected. Based on the data analysis, pipeline rehabilitation was prioritized for the various segments of the NPSSI. Corrosion control analysis was also performed to determine the feasibility of implementing a corrosion control program to extend the service life for pipeline segments which did not warrant immediate rehabilitation. Corrosion control chemical addition was bench-scale and full-scale pilot tested to determine the cost-effectiveness of a corrosion control program for minimization of capital expense for pipeline rehabilitation. Implementing a corrosion control program will save the City $5,000,000 over the life of the interceptor.