|Throughout MSD’s service area, there are hundreds of points where a combination of rainwater and wastewater discharges into local waterways from the sewer system during moderate to heavy rainstorms. These sewer overflow points act as relief valves when too much rainwater enters the sewer system, and without them, our community could experience thousands of basement backups and/or extensive street flooding. Depending on where sewer overflows are located within MSD’s system, they are classified as constructed separate sewer overflows — or — combined sewer overflows. If an overflow discharges or not is dependent upon a number of factors, including how much rain falls over a given period of time. The result is that not all overflows discharge every time it rains — in fact, some overflows will go months or years without discharging. Though both types of overflow points generally have the same function, the distinction between combined sewer overflows and constructed separate sewer overflows is made for engineering and regulatory purposes.
Many of the overflows that exist throughout MSD’s service area are a legacy of the way our wastewater systems were first built starting in the 1850’s. Even though most overflows predate the District’s creation in 1954, they are still MSD’s responsibility and efforts to address the issue must continue.
MSD is working to educate the public on the issue of overflows. Part of this education is the placement of signs in multiple areas that could be impacted by activated overflows. Required by the United States Environmental Protection Agency (EPA), the signs clearly state that the structure the placard is attached to is an overflow point and during rainfalls a combination of wastewater and stormwater might be discharged into the surrounding environment. For overflow points where no easily identifiable structure exists, the signage will be posted nearby.
EPA has ordered signs placed at all constructed separate sewer overflow points and a letter sent to all MSD customers regarding the signage. In addition to this letter to all customers, a separate letter and brochure has been sent to customers on whose property an overflow might exist. These letters and the brochure are available through the below links. In addition to these materials, a map showing the location of all sewer overflows in MSD’s service area and the Order from EPA are available through the below links.
The above mentioned materials have been posted to this webpage so the public may learn more about these important issues. If you have any questions about these materials, the signs that have been posted, or overflows in general, please contact MSD’s Customer Service Center at (314) 768-6260.
For more information on sewer overflows and their locations, please visit www.stlmsd.com or call (314) 768-6260.