Effectiveness of Wastewater Collection System Rehabilitation to Reduce Infilration and Inflow Feb 2004

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Monitoring Prog ra m The City of Eugene and MWMC began a monitoring program in the late 1980s using Marsh McBirney Flo-Tote brand meters. At that time, the City owned several meters that were employed in the pre-treatment program. These meters were used to monitor flows from entities required to perform pre-treatment of wastewater prior to discharge to the City's sanitary sewer system. These meters measure depth only and apply that depth to a pre- calibrated rating curve to determine flow. That program has grown to the point that the City owns 42 Flo-Tote meters. Generally, one individual, who collects and reviews data for quality, administers the program. A crew of two performs the fieldwork, usually two days per week to check and calibrate meters and to relocate meters when necessary. Recently, the MWMC contracted with MGD Technologies, Inc. of San Diego, CA to install Acoustic Doppler Flow Monitors (ADFM) at 6 locations on larger diameter pipe segments. This is a 3-year program nearing completion of the first year. These ADFM meters serve to quantify flows on some major interceptors that are outside the range of applicability of the City's FLO-TOTES meters. Flow data are used mainly to support design purposes and to form the basis for assessing the effectiveness of system rehabilitation to reduce infiltration and inflow. Concentrated flow metering is also used for detailed study of problem areas. Two recent examples included focused monitoring in the Glenwood area to identify the basis for unusually high flows and to support the design measures to remove the sanitary sewer overflow at the intersection of 10th and Tyler Streets. The monitoring program has reached a solid equilibrium in terms of equipment and personnel. The current plan is to maintain the program as-is. Because it is funded through sewer fees and not the City's General Fund, it is a relatively stable program. 8