Sanitary Sewer Overflow Estimation Technical Training Station

For many years the District, has made an attempt to determine the volume of a Sanitary Sewer Overflow (SSO) and the amount recovered. Historically, these estimates were a guesstimate by field staff. In 2002, as a member of the Collection System Collaborative Benchmarking Group, the District co-authored the Best Practices for Sanitary Sewer Overflow (SSO) Prevention and Response Plan, which included methods on how to estimate SSO volumes. The District started using those methods to estimate SSO volumes, until we realized that those methods did not always result in an accurate estimation of SSO flow rates. This could likely lead to under or over-estimation of spill volume, which the District did not want. The tools that were being used were developed using manhole covers that were dissimilar to the ones used by the District. A project was undertaken to research and develop new tools that better met the needs of the District to measure the volume of an SSO. After careful consideration a plan was developed to construct a Sanitary Sewer Overflow Estimation Technical Training Station (SSOETTS). The SSOETTS comprises four manholes, piping, valves, and digital meters. The SSOETTS can now produce simulated SSOs up to 200GPM. The District now has a useable training tool for estimating an SSO. Estimations that are based on pictures of manhole covers overflowing are now based on existing District covers. Confidence in estimating the volume of SSOs has significantly increased. Instruction on using the new tool and other approved methods has been completed on nineteen CSWs and two management employees.