Meramec River Advisory Lifted

Ultraviolet Light Treatment Restored at Fenton Wastewater Treatment Plant

Lower Meramec River Update

We’re excited to share that the most recent water quality data has allowed the Metropolitan Sewer District (MSD) to lift the Meramec River Advisory.  Operation Clean Stream is a go, with the exception of George Winter Park (read about that here.)  We encourage you to read and share MSD’s press release below….

For Immediate Release

Contact:  Lance LeComb @ (314) 517-8803 / llecomb@stlmsd.com

Ultraviolet Light Treatment Restored at Fenton Wastewater Treatment Plant

Meramec River Advisory Lifted                         

(August 24, 2016)— Metropolitan St.  Louis Sewer District (MSD) crews and contractors have restored the ultraviolet light (UV) treatment process at the Fenton Wastewater Treatment Plant (WWTP) and the facility is meeting regulatory requirements for wastewater treatment.  Accordingly, the advisory to avoid contact with the Meramec River from Fenton, Missouri, to the Mississippi River has been lifted and signs placed in public access areas along the Meramec have been removed.

The Fenton WWTP has three UV treatment units.  Two of these units have been operating since Friday, August 19, and the third unit became operational on Tuesday, August 23.  The third unit is utilized during rainstorms, when the treatment plant handles higher flows.

A temporary chemical based process that replicates the function of the UV treatment process was put in place late last week/over the weekend, in the event the UV treatment units could not be fully restored.  This chemical based process will remain in place and available until full repairs to the UV treatment units are completed.

On Monday, August 15, a cloudburst of nearly four inches of rain fell on south St. Louis County over six hours.  This rainwater made its way into the sewer system leading to MSD’s Fenton WWTP, located in Fenton, MO.  The rainwater inundated the treatment processes at the plant and flooded the UV treatment building located at the rear of the treatment facility.  During this time, the primary and secondary treatment processes remained online and fully functional.

While the rains of August 15 did not cause the same amount of damage to the Fenton WWTP as the rains and flooding of December 2015/January 2016 – when record floodwaters from the Meramec River topped the plant’s flood protection levee, covered the facility in six feet of water, and took the treatment facility offline until April 8, 2016 – final repairs from the flooding were still being completed.  This ongoing recovery from the flooding contributed to the flooding of the UV treatment building on August 15.  Due to the very high volume of rainwater that came into the Fenton WWTP on August 15, MSD is also working to identify if a potential break or damage to the sewer system occurred during the August 15 rains.

While the UV treatment process was being repaired, MSD conducted weekly water quality monitoring of the Meramec River near the Fenton WWTP.  As shown below, one sample is taken upstream of the Fenton WWTP and several more samples are taken downstream of the plant.  These results are impacted by a number of factors aside from the functioning of the treatment plant, including the volume of the river at the time of the tests; the timing, amount, and locations of recent rainfalls; turbidity of the river; the amount of sunlight the river is exposed to; and other environmental factors.  The most recent results are below.


Wastewater service to area homes and businesses has not and will not be interrupted.

Pictures of the flooded UV treatment 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 WWTP from April 1 through October 31, is the ultraviolet light treatment process.

The Fenton WWTP 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 and been in constant contact with 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.