City staff have contained an overnight sludge spill into the Kalamazoo River at the Wastewater Treatment Plant, located on West River Road.
During a warmer season, the public would be warned against swimming in the river, and fishing downstream of the plant is discouraged. There is no additional public danger, and drinking water is not affected. Because the river is muddy, due to recent rains, the public likely will not notice a visual difference.
The incident happened at about 12:05 a.m. today, and was discovered at 6:20 a.m. when staff arriving for the day noticed an atypical smell in the area of the affected holding tank, in the northeast area of the plant. The spill was contained by 6:40 a.m.
Staff determined that 26,600 gallons of partially treated sludge and raw sludge overflowed from the storage tank, via an eight-inch overflow line. It then ran into a 12-inch storm sewer line, approximately 35-40 feet away, which runs directly into the North Branch of the Kalamazoo River. The river runs north of the plant.
The plant is staffed overnight, but there currently is not a notification alarm on the tank to alert staff to an overflow situation. The tank holds 650,000 gallons and the level is monitored electronically.
Wastewater staff currently are working on measures to redirect the sludge discharge from the tank’s overflow line to a holding area, to prevent future flows into the nearby storm sewer, and into the Kalamazoo River.
Staff have identified contributing factors to the overflow and spill, including recent rain, and the fact that the plant does not process sludge on the weekends, due to the landfill being closed. The waste stream from the city continues to flow to the plant, so the storage tank is designed to hold sludge over the weekends.
When operating, this holding tank pumps the sludge on to the plant’s centrifuges, which remove water from the sludge. The holding tank was installed in 2017.
Wastewater staff have notified the Michigan Department of Environmental Quality and Calhoun County Public Health Department, and are in the process of making additional notifications of the spill, as required.