INTEGRATING INVESTIGATION METHODS TO CONDUCT AN OVERFLOW INVESTIGATION

During January, 2006, extended duration rain events resulted in sanitary sewer overflows in the Turner Creek Corridor in Hillsboro, Oregon. A study was already underway to design and construct a wet-weather pump station in the corridor that would pump high-flow events around the corridor to the Clean Water Services (District) Rock Creek Treatment Plant headworks. The ensuing overflow investigation conducted by District and the City of Hillsboro (City) involved CCTV inspection of manholes and sewer lines in the corridor and tributary areas, flow monitoring and rain gauge monitoring, flow modeling, record drawing investigation, smoke testing, and review of treatment plant influent pump station (IPS) operating procedures.As a result of the intensive investigations, short-term repairs, flow re-routing, maintenance activities, I/I reduction projects, short-term wet-weather procedures, and even treatment plant operational changes were implemented that resulted in cancellation of the 10 million, 13 MGD wet-weather pump station. This presentation will provide a case study focusing on the need to know your system and the need to conduct a thorough evaluation to appropriately address system deficiencies.