North County site: Team continues to investigate Coldwater Creek

U.S. Army Corps of Engineers (USACE), St. Louis District, Formerly Utilized Sites Remedial Action Program (FUSRAP)
Published March 31, 2023
A view of Coldwater Creek and environs Monday, March 23, 2020. Coldwater Creek corridor (banks and sediment) and adjacent properties from New Halls Ferry in Florissant to Westminster in North St. Louis County make up a stretch of CWC being sampled in 2020.

Photo of Coldwater Creek.

The approach to Coldwater Creek is to first eliminate the sources of contamination. The U.S. Army Corps of Engineers is currently remediating properties adjacent to CWC from upstream to downstream.

The approach to Coldwater Creek is to first eliminate the sources of contamination. The U.S. Army Corps of Engineers is currently remediating properties adjacent to CWC from upstream to downstream.

The U.S. Army Corps of Engineers (USACE), St. Louis District, Formerly Utilized Sites Remedial Action Program (FUSRAP) continues to investigate Coldwater Creek (CWC), completing approximately 13 miles of the creek and collecting over 34,000 samples as of March 16. Currently, USACE is performing investigative sampling from Highway 367 to the Missouri River.

Each 1-mile section of the creek equals to 30 to 150 acres of the 10-year floodplain adjacent to the creek that needs investigation and sampling. The investigation includes 14.2 miles of the creek corridor (banks and sediments) and adjacent properties within the 10-year floodplain. Sampling is conducted at various depths between 0 to 10 feet below ground surface, depending on the target sample location, and may be deeper in order to reach native soil. 

Low-level radiological contamination has been found in isolated areas along the creekbanks and within the 10-year floodplain. The contamination found is typically below ground surface and doesn’t pose an immediate risk to the public in its current configuration. The FUSRAP team performs follow-up investigation on areas of CWC where contamination was found as well as delineation for remedial-design purposes.

After the initial investigation is completed, USACE sends preliminary status letters to property owner, informing the property owner of the status of the property. A letter notifies the property owner of one of the following:

- Preliminary results indicate no contamination was found on their property.

- Contamination was found on their property and more investigation is needed.
(A letter to a property owner with contamination present on the property asks that the property owner notify USACE if the soil will be disturbed in that area, so that USACE may provide appropriate support and protection during the activity.)

- No contamination was found on the property, but contamination was found adjacent to their property in the banks of CWC. 

For properties where no contamination was found, USACE prepares a Pre-Design Investigation Report (PDIR)/Final Status Survey Evaluation (FSSE). This document provides the final documentation and sampling data that states no contamination was found on that property, and the property is released for beneficial use. USACE sends a final letter of notification to the property or business owner with this information.

USACE samples CWC year-round in all weather conditions. The FUSRAP team sometimes has difficulties sampling the creek. Challenges include:

- Obtaining a right of entry from the property owner;

- Identifying changes in the creek, such as filled-in historic meanders;

- CWC flooding;

- Inclement weather;

- Deep soil sampling 8 to 10 feet below ground surface on creekbanks, in backyards and in the creek;

- Finding a place to safely enter the creek and heavily wooded areas with sampling equipment and drill rigs;

- Longer distance to reach the creek as sampling continues farther down the creek with fewer access locations.

The “Coldwater Creek Sampling Pace Fact Sheet” discusses and identifies the many steps taken to sample the creek. More than 100 people are working daily on completing the creek investigation. A read-only version of the fact sheet is available at https://www.mvs.usace.army.mil/Portals/54/docs/fusrap/factsheets/CWC_Sampling_Timeline_Pace_Fact_Sheet_508.pdf. If you wish to print the fact sheet in letter size, go to https://www.mvs.usace.army.mil/Portals/54/docs/fusrap/factsheets/CWC_Sampling_Timeline_Pace_Fact_Sheet_printLETTER.pdf. If you wish to print it in tabloid size, go to https://www.mvs.usace.army.mil/Portals/54/docs/fusrap/factsheets/CWC_Sampling_Timeline_Pace_Fact_Sheet_printTABLOID.pdf.