Location:
Earth Tech, in a joint venture (JV), has been successfully providing CSO control services to the Milwaukee Metropolitan Sewerage District (MMSD) since 1997. The project scope encompasses full engineering services from study and preliminary/conceptual design, to inspection, to final design and construction management. Work has included interceptor sewers, large tunnels and CSO pumping stations.
For the Northwest Side Relief Sewer project, the JV performed a preliminary engineering study to relieve excessive surcharging during wet weather for existing sections of MMSD’s metropolitan interceptor sewer (MIS) system. Ultimate flow conditions were projected to exceed capacity by 60%. The study’s scope included structural inspection, capacity assessment, preliminary design and alternatives analysis, construction sequencing, compliance with regulatory requirements and inter-agency coordination with city, county, state and private utilities concerns. In addition, the JV supported the District’s public information program.
The preferred alternative included a 25,000-foot rock tunnel and dewatering pump station. MMSD elected to modify the recommended alternative and extend the proposed relief sewer to an inline storage system dropshaft, which eliminated the proposed pump station. MMSD also elected to increase the sewer tunnel size to 20-foot-diameter to provide additional wet-weather storage to the inline storage system.
To evaluate and recommend an alignment for the NWSRS extension project, the JV completed a Phase I environmental assessment of sewer alignment, an archaeological survey, geotechnical investigations and evaluations of alignment, hydraulic modeling, fact finding meetings with affected municipalities and governmental agencies and property ownership/easement investigations.
The JV was also responsible for overall project coordination, the project management plan, planning and scheduling, budget and cost management, design contract preparation, design consultant management services, construction contract preparation, QA/QC plans, project safety, communications plans, regulatory agency and state historical office review, risk management/evaluation, constructibility review and funding assistance
Under a separate contract, Earth Tech was one of a consortium of engineering firms contracted to study, design and build a $2.2 billion CSO abatement project featuring an inline storage system. The deep tunnel project consisted of a series of 17-foot to 32-foot diameter tunnels, 300 feet below the surface and totaling 19.5 miles in length. Twenty-four dropshaft/collector systems were constructed to divert flow from the existing sewers to the deep tunnels. These systems included collector sewers, remotely controlled diversion structures, junction chambers, trash racks, odor control facilities, approach channels, flow measuring devices, dropshafts, dearation chambers, air vent shafts, and connecting tunnels. In addition, relief sewers were built elsewhere in the system to relieve overloaded portions of the system.
Earth Tech participated in and provided personnel for all aspects of the oversight and administration of these challenging construction projects. Earth Tech provided program-wide administrative overview and quality control, establishing and monitoring budgets, supervising field office support staff, guiding resident engineers, and coordinating program funding acquisition. Earth Tech also provided contract administration, claims management, and scheduling.
