The Lemont Water Reclamation Plant (LWRP) is the smallest of the MWRD’s seven water treatment facilities. This Plant began operations in 1961 and consists of three primary buildings; the main building, pump house and digester building. Unlike the other plants whose tanks are located at ground level, the Lemont tanks are located above ground.
Wastewater arrives at the plant and passes through coarse screens to filter out large debris. Then it is pumped up from sewer level and flows by gravity throughout the treatment plant. In primary treatment, aerated grit tanks use physical and mechanical means to remove fats and oils and also work to separate solids from the water. The separated solids are pumped away to undergo their own treatment process and eventually become biosolids, a sustainable alternative to chemical fertilizers. By the end of primary treatment, 60 to 80 percent of the solids have been removed.
In secondary treatment, a community of microorganisms help remove organic material from the wastewater. The microbes need oxygen to thrive, so air is pumped through the water in secondary aeration tanks. Next, the water enters the final settling tanks where remaining solids settle to the bottom and clean water flows out the top. The clean water is released from the Lemont WRP into the Chicago Sanitary and Ship Canal. It only takes an average of six hours for wastewater to be converted from raw sewage to clean water.
In 2015, the Lemont WRP unveiled the Wet Weather Treatment Facility and Reservoir. The project increased the size of the 18-inch interceptor sewer entering the plant site from the village of Lemont's combined sewer area. A wet-weather treatment facility was also constructed to provide primary treatment followed by disinfection, which is now large enough to treat up to 10 times the volume of dry weather flow (approximately 6.8 million gallons per day). A five-million gallon equalization reservoir was also constructed to store and buffer the peak wet weather flows from Lemont’s separate sewer area. The Construction Industry Service Corporation (CISCO) honored the new facility with a Project of the Year award in 2016. During storms in recent years, the Lemont WRP has received high flows from the tributary sewer systems resulting in bypasses to the Chicago Sanitary and Ship Canal. Working with the Illinois Environmental Protection Agency, the MWRD created the Wet Weather Treatment Facility and Reservoir project, and in the process created a way to protect the local waterway and improve area water quality downstream.
To learn more about Lemont WRP, visit here.