WHY ASSESSING TRUNK LINE CONDITIONS PRIOR TO HYDRAULIC MODELING FOR SSO MITIGATION IS CRITICAL

The City of Columbus, Ohio Division of Sewerage and Drainage, Inflow and Infiltration Program utilizes a comprehensive sewer system evaluation and hydraulic modeling approach to mitigate sanitary sewer overflow and water-in-basement occurrences. A preliminary engineering study underway in the northwestern section of the City involves the development of a SWMM hydraulic model of sanitary trunk sewers using field investigation findings, sewer maintenance service records, and historic record plans.The significant number of problem areas identified (e.g., an 84-inch diameter storm sewer crossing, not accurately reflected on the sewer as-built records, that impacts wet-weather pipe capacity; deteriorated pipe segments; construction debris; and heavy deposition) substantiated the cost and efforts devoted to comprehensive inspection of the trunk sewer serving the sewershed. By identifying these problems and incorporating them into the hydraulic model prior to SSO mitigation alternatives analysis, the City of Columbus will be able to effectively spend capital improvement and maintenance dollars to correct the verified problems in the collection system.