The Detroit Water and Sewerage Department (DWSD) Wholesale Customer Outreach Public Education Work Group is continuing to monitor and share information about the performance of the wastewater and storm water infrastructure system tributary to the Detroit Wastewater Treatment Plant. The 21 combined sewer overflow (CSO) retention treatment basin (RTB) facilities that operate throughout the Detroit wastewater service area, shown in Figure 1, play a major role in protecting water quality. From January through March 2012, these RTBs prevented more than 1 billion gallons of combined sewage from overflowing into our waterways. Of this total, 892 million gallons or 87% of the total flow was captured, transported to and treated at the Detroit Wastewater Treatment Plant (WWTP), while the remaining 130 million gallons were treated and discharged from RTBs. These treated discharges meet federal and state National Pollutant Discharge Elimination System (NPDES) permit requirements and are deemed protective of public health.
The mild winter of 2011/2012 saw above normal temperatures and near average precipitation. Though snowfall was considered normal, higher temperatures melted it quickly. This lack of a sustained snowpack contrasts sharply from the active winters of the last several years when RTB facilities have handled larger volumes of rain combined with snow melt. March went on the record books as the warmest in Michigan with an average of 50.7 degrees in the Detroit area. RTBs went into operation on 12 out of 91 days, or 13% of the time and only 5 of the 15 RTBs tributary to the Detroit sewer system discharged. Treated and captured volumes of combined sewage for the first quarter of 2012 are shown in Figure 2.
Because RTBs operate intermittently, preventive maintenance is critical to make sure the facilities are ready to go into operation when needed. RTB operators and staff remained busy exercising equipment and performing maintenance and repairs. For example, the Oakland County Water Resources Commissioner staff completed maintenance activities at all four of their facilities. Pumps were rebuilt at the George W. Kuhn and Bloomfield Village RTBs and various repairs were performed at the Acacia Park and Birmingham RTBs.
Operation Clean Water features articles on how DWSD and its suburban wholesale customers manage our water and sewer infrastructure to protect public health and the environment. It was created by the DWSD Wholesale Customer Outreach Public Education Work Group that includes individuals from wholesale customers (Macomb, Oakland and Wayne Counties), DWSD, MDEQ and SEMCOG and consultants.