STUDY AND DESIGN OF CONNER CREEK PILOT CSO CONTROL FACILITY

The Detroit Water and Sewerage Department (DWSD) developed a Long-Term Combined Sewer Overflow (CSO) Control Plan (Plan). The Plan addresses CSO outfalls, which discharge to the Detroit River and the Rouge River. One component of the Plan is the Conner Creek Pilot CSO Control Facility (Facility). This Facility will accept CSO from three outfalls, which currently discharge to the Detroit River via Conner Creek and have a combined estimated peak flow of 13,262 cubic feet per second (cfs) for the 10- year, 1-hour storm. The Facility is a “pilot” because it will be designed based on providing 5 minutes of retention time at the 10-year, 1-hour peak flow instead of 30 minutes, which is the Michigan Department of Environmental Quality's (MDEQ's) presumptive criteria for adequate treatment. DWSD's National Pollutant Elimination System (NPDES) Permit requires that the Facility provide skimming, settling, and disinfection to meet the daily and monthly fecal coliform limits of 400 and 200 colony forming units (cfu) per 100 milliliters (ml), respectively.The Facility will consist of a headworks area that will contain screening and disinfection facilities. The screening facilities will include ten mechanically cleaned catenary bar screens and two belt conveyors. The Facility will utilize sodium hypochlorite for disinfection and these facilities will include: four rubber lined and insulated steel storage tanks; ten magnetically driven, centrifugal feed pumps, ten low-flow diffusers; and sixty high speed submersible mixers. Following the headworks area will be a 30-million gallon (MG) retention basin that will be divided into four parallel compartments. A scum baffle at the end of the retention basin will retain floatables that will not be removed by the screening facilities. The solids that will be retained in the retention basin will be cleaned with a flushing gate system and pumped to the interceptor for ultimate treatment at the Detroit Wastewater Treatment Plant (WWTP). Influent and effluent sampling systems will be provided, which will consist of submersible sample pumps and multi function refrigerated samplers for discrete and composite sampling. Odor control will be provided with a carbon adsorption system.