Initiating Sewer System Real Time Controls in Cincinnati

This paper summarizes the development and implementation of the Ross Run Real Time Control Project. The Metropolitan Sewer District of Greater Cincinnati (MSDGC) investigated sewer system real time controls as one of the alternatives in the long term control planning for combined sewer overflows (CSOs). The investigation revealed that real time controls had the potential to significantly reduce the frequency and volume of overflows at selected locations, but would not provide sufficient control to fully achieve CSO planning objectives; e.g. wet weather volumetric control above 85 percent. Nevertheless, when MSDGC negotiated a Consent Decree governing overflow reductions, it was agreed to assess and implement real time controls at priority sites. MSDGC staff were reluctant to commit significant resources to a technology, real time control of sewers, with which they had no experience and which had not been proven in the local sewer system. They selected one site, the Ross Run site, where the preliminary studies projected significant potential for overflow reduction with comparatively uncomplicated real time control technology. A local consultant, BBS Corporation, teamed with others (XCG Consultants and CH2M HELL) to bring international experiences to this initial test in southwestern Ohio. This paper discusses the range of questions raised by those making planning and design decisions essential to implementing the first local real time controls. The paper explains questions by the planners interested in long term cost benefit to those of the operator wondering how often the facilities and instrumentation would require maintenance and calibration for reliable service. The questions were addressed through research of experiences elsewhere, coupled with discussion of how those experiences apply in constructing and operating the MSDGC real time sewer controls. The Ross Run real time control design is scheduled to bid in late 2006 and be constructed in early 2007.