Detailed Sewer System Characterization to Support SSO Remediation

The City of Columbus, Department of Public Utilities, Division of Sewerage and Drainage (DOSD) has initiated the Northwest Alum Creek Inflow and Infiltration (I/I) Remediation Project, which is a detailed study of the project area's sanitary sewer collection system. The goals of the project are to identify and provide solutions to mitigate sewerage overflows out of manholes, sanitary reliefs, sewerage system surcharging, and sewerage backups into basements. Critical to the objectives is having an accurate understanding of the wastewater collection system so that the causes of the problems can be understood which will lead to reliable remediation alternatives and, ultimately, a solution that can be recommended with confidence. A plan was developed and implemented that builds upon the existing documentation and understanding of the system and expands to a detailed, up-to-date characterization of both the public and private sewer system infrastructure. This paper describes the data being gathered and the general approach to efficiently gather the data to provide the detailed characterization needed to achieve the objectives of the study as well as how the data will be used.The detailed characterization is categorized into the following six major field related tasks; 1) CCTV and sewer cleaning, 2) flow and rainfall monitoring, 3) customer questionnaires, 4) a detailed drainage reconnaissance, 5) wet-weather quick response observations, and 6) dye-testing. The kind of information that has been or is being gathered is presented along with a brief description of the approach used to gather the information. A brief discussion is provided on the efficient means to gather the data and how to gather quality data.Extensive information has been gathered and continues to be gathered that is providing a detailed characterization of the sewer system condition on both the public and private side. These data will be correlated to each other as well as to results from a detailed hydraulic model that will lead to an accurate understanding of the causes of the system problems. About 500,000 feet of sanitary sewers has been cleaned, CCTVed, and PACP coded, about 9,000 customer questionnaires have been mailed, about 9,000 parcels have been surveyed for drainage characteristics, 46 flow monitors are collecting 5-minute data, a select set of homes will be dye-tested, and wet-weather flow response teams will observe conditions for a handful of rainfall events.