Satellite Sewer System Modeling

The Milwaukee Metropolitan Sewerage District (MMSD) provides wastewater and flood management services for 28 municipalities (Figure 1 on the following page) within its 411-square-mile planning area. One of the challenges faced by MMSD was the need to understand the timing and volume of flow contributed by each of these municipalities through their local sewer systems to the MMSD's Metropolitan Interceptor Sewer (MIS). The MIS is the regional sanitary sewer system operated by MMSD that connects local municipal sanitary sewer systems to the two regional wastewater treatment plants and regional Inline Storage System servicing the Milwaukee metropolitan area. In 2004, MMSD began development of limited satellite municipality System Evaluation and Capacity Assurance Plans (SECAP) for each of the satellite municipalities it serves. The SECAP hydraulic evaluations were limited in that only those portions of the local sanitary sewer systems necessary to provide required information for the 2020 Facilities Plan project were analyzed. The 2020 Facilities Plan is the most recent generation of facilities planning undertaken by MMSD to determine what MMSD facilities are required to meet the needs of the region through the year 2020. Specifically, the SECAP project was to: 1 Identify satellite municipality system capacity deficiencies. 2 Estimate satellite municipality system bypass volumes and flow rates for selected wet weather events. 3 Summarize peak flows delivered to the MIS system for a selection of wet weather events.