Objectives of the project were: Define the characteristics of combined sewer overflow; Investigate the feasibility of high-rate filtration for treatment of combined sewer overflow; and Develop and evaluate alternative methods of solution. Investigative activities included: Review of pertinent reports and technical literature; Field monitoring of combined sewer overflows and separated storm water discharges at three sites; Laboratory studies of ultra-high-rate filtration of combined sewer overflow; Hydrological analysis; and Evaluation of feasible alternatives (based on conceptual design, preliminary cost estimates, and other factors). Reservoir Storage, Treatment at Overflow Points, Conveyance Tunnels and Mined Storage, and Sewer Separation were the approaches considered sufficiently promising for detailed evaluation. Tunnels and Mined Storage with treatment at the Blue Plains plant and at Kingman Lake after subsidence of the storm is recommended. Estimated capital costs (based on the 15-year storm) are $318,000,000 with annual operation and maintenance costs of $3,500,000. This approach also was preferable to the others on the basis of systematic evaluation of reliability, flexibility, public convenience and other non-quantifiable factors. (Author)