INNOVATIVE TECHNOLOGIES OF DETROIT'S LARGE CSO CONTROL FACILTY

The Detroit Water and Sewerage Department (DWSD) developed a Long-Term Combined Sewer Overflow (CSO) Control Plan (Plan) which addresses control of discharges from CSO outfalls to the Detroit River and the Rouge River. One component of the Plan is the Conner Creek CSO Control Facility.The 187 million, Conner Creek CSO screening and disinfection facility, the largest in Michigan, is designed to operate as an “unmanned” facility with five minutes of contact time at the ten-year, one-hour peak flow of 13,262 cubic feet per second (cfs). The storage capacity of the facility is 30 million gallons (MG). Discussions between DWSD and the State of Michigan Department of Environmental Quality (MDEQ) resulted in an agreement to construct a pilot CSO treatment facility to achieve daily and monthly fecal coliform limits of 400 and 200 colony forming units per 100 milliliters (cfu/100 ml), respectively, with five minutes of contact time at the afore-mentioned peak flow. Additional acceptance criteria to meet water quality standards include screening and skimming to reduce the impacts of overflows on physical aesthetics including the presence of turbidity and oil.The objective of this paper is to present the innovative technologies investigated and/or implemented on this project and the unique challenges associated with their construction. The paper will focus on the following:Facility design requirementsHydraulic/capacity considerations including design peak flow rates, hydraulic modeling, reuse of existing infrastructure, storage optimization/effluent launders, and Conner Creek dredging/widening, and mitigation of the state water,Treatment considerations including 5-minute contact time, screening, settling, high-rate disinfection, and skimming,Operation and maintenance considerations including basin dewatering and flushing,Implementation status including unique challenges associated with the construction of the Conner Creek CSO facility, including off-site construction of a fish habitat pond at a Maheras Park overlooking the Detroit River.