Early Monday morning, and based on preliminary data, a cloudburst of approximately 3.9 inches of rain over six hours fell on south St. Louis County. This rainwater made its way into the sewer system leading to MSD’s Fenton Wastewater Treatment Plant, located in Fenton, MO. The rainwater inundated the treatment processes at the plant and flooded the ultraviolet light disinfection building located at the rear of the treatment facility. While the primary and secondary treatment processes are fully functioning, ultraviolet light treatment is offline. MSD is currently evaluating the extent of the damage to the ultraviolet light treatment facilities; the feasibility of temporary steps to replicate or replace the function of ultraviolet light treatment; and the timeline for repairs.
While there is no immediate threat to the public’s health or safety, the public is advised to avoid contact with the Meramec River from Fenton, Missouri, to the Mississippi River. Signs have been posted in areas where the public may readily come into contact with this section of the river. If anyone should come into contact with the river in this area, it is recommended they immediately and thoroughly wash with soap and water.
Wastewater services to area homes and businesses will not be interrupted.
Pictures of the flooded disinfection building are available @ https://www.dropbox.com/sh/3inr5fy6a7igocj/AACDSkJK_O8Wg7L9voe6KH_ga?dl=0
Primary treatment is the first step in the treatment process when any treatment plant is fully operating. Primary treatment involves the removal of solids from the wastewater. The next step of a fully functioning treatment process is called secondary treatment. This step utilizes biological processes to remove pollutants from the wastewater. The third step, in effect at the Fenton Plant from April 1 through October 31, is the ultraviolet light treatment process.
The Fenton Wastewater Treatment Plant is designed to handle 6.75 million gallons of wastewater per day during dry conditions. During wet weather conditions, the plant can handle up 24 million gallons per day.
MSD has notified the Missouri Department of Natural Resources about the situation at the Fenton Wastewater Treatment Plant, as required by law. Additionally, MSD has been in contact with various governmental agencies and drinking water utilities located along the Meramec River in both Jefferson County and St. Louis County.
MSD will share further information on this situation as it becomes available.