The City’s North Water Reclamation Facility has recently experienced two events that allowed partially treated wastewater to overflow into Lake Monroe. The City Commission and staff recognize the severity of the situation and the impact it has on our environment. The overflow is unacceptable. In the past, overflows were related to rain events because of an influx of stormwater into the system. The City has been spending about $1 million per year to solve that problem. The state provided a grant of $2.9 million this year to accelerate our work; however, the most recent overflows were caused by a malfunction in the plant itself.
The recent temperature drop reduced the efficiency of bacteria used to break down waste and also promoted the growth of a non-beneficial type of bacteria which negatively affected the treatment process. This caused the sand filters, the last step in the treatment process, to clog.
Making the problem worse, a slide gate broke, which does just what its name implies (moves or “slides” up and down adjusting the amount of flow through the plant), preventing staff from changing the flow through the plant that could have reduced the overflow. While awaiting the manufacture of a replacement slide gate, staff has temporarily fixed the broken slide gate. The treatment plant staff has cleaned and continues to reclean the sand filters to allow them to work again. The longer-term solution has been underway for about eight years. While keeping the plant running, the plant has been undergoing a complete rebuild with advanced technology. Part of that new technology is a system that will replace the sand filters and allow them to be used as a backup system. The addition of the new filter system, at a cost of $4.7 million dollars, is nearing completion and will provide greater capacity and more reliable operation. It is the same system that has worked well at the South Water Reclamation Center. The City apologizes for the overflow and will continue to do our best to prevent future events.