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Velsicol Chemical Corp. (formerly Michigan Chemical Corp.) produced various chemical compounds and products at its 54-acre main plant site in St. Louis, Mich., from 1936 to 1978. Products included the fire retardant polybrominated biphenyl (PBB) and the pesticide DDT. To address contamination discovered at the former plant site, Velsicol, EPA and the state of Michigan entered a consent agreement in 1982. Velsicol agreed to construct a slurry wall around the former plant site and put a clay cap over it. The Pine River, which borders the former main plant site on three sides, was significantly contaminated, which caused the state of Michigan to issue a no-consumption advisory for all fish species.

 From 1998 to 2006, actions taken at the site addressed contamination in the Pine River at a cost of over $100 million. From 1998 to 2006, EPA funded a sediment cleanup in the Pine River adjacent to the site. Over 670,000 cubic yards of DDT-contaminated sediment were removed and disposed of off-site in an approved landfill. DDT levels in fish have been reduced by over 98 percent, but the state plans to keep the fish advisory in place until the entire site has been cleaned up.

 In early 2000s, studies showed the slurry wall and clay cap at the main plant site were failing to keep contamination out of the river. In response, EPA and Michigan's Department of Environmental Quality (MDEQ) launched a remedial investigation and feasibility study at the main plant site. The resulting report stated that soil and groundwater were contaminated. The study identified areas with high concentrations of contaminants known as “potential source areas.” EPA evaluated different cleanup alternatives to address contamination at the site and, in June 2006, selected a remedy that included a comprehensive cleanup of the main plant site and a residential soil cleanup. During the residential cleanup, EPA excavated and disposed of 50,000 tons of contaminated soil at an off-site landfill. Currently, EPA and MDEQ are completing what’s called a “Remedial Investigation” in the Pine River downstream of the former chemical plant property.

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What Has Been Done to Clean Up the Site?

Drinking Water Supply

In May 2014, construction began for the replacement of the city of St. Louis drinking water supply. St. Louis and Alma formed a joint water authority called the Gratiot Area Water Authority (GAWA). In October 2015, St. Louis switched to the new GAWA drinking water. A summary of completed construction activities is included below.

  • Expansion of Alma’s water treatment plant.
  • Construction of water mains from Alma water treatment plant to St. Louis.
  • Construction of two booster pump stations for new water mains.
  • Construction of an elevated water tank in St. Louis.
  • Installation of new water wells.

Main Plant Site

The two largest contaminated areas on the site are referred to as Areas 1 and 2. The following is a list of completed cleanup activities.

  • Design and cleanup of residential area.
  • In situ (in-place) thermal treatment for Area 1.
  • Excavation design for potential source areas.
  • Predesign investigation for additional potential source areas.

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What Is the Current Site Status?

Velsicol Plant Site - In-place Thermal Treatment
The heating for the first phase of Area 2 has begun and will be gradually ramped up over the next several months to attain target underground treatment temperature of 100 degrees Celsius (212 degrees Fahrenheit). A total of 323 holes were drilled for the heaters, extraction wells, temperature probes, and pressure probes.

Drilling continues for phase 2 of Area 2 and 448 holes will need to be drilled for the equipment and wells.  Drilling for phase 2 is planned for completion late this fall. The expected completion of in-place thermal treatment for Area 2 is fall 2021.

 Velsicol Plant Site - Design Investigations
EPA has developed a plan to investigate portions of the slurry wall to determine its effectiveness. Drilling to support the investigation was completed over the past month. This work will also provide additional information on the design of the water treatment plant and provide additional groundwater sampling and elevation data. 

Pine River Downstream Study
EPA and its contractor, Jacobs, are finishing the ecological study for the downstream area.  Upon completion of the study, Jacobs will complete a report on cleanup options for the upstream section of the Pine River below the St. Louis dam, known as "Operable Unit 3" or OU3. The cleanup options will focus on removal of contamination from the most heavily impacted floodplains.

In addition, EPA and Jacobs continue monitoring the field pilot study using an activated carbon technology for potential application in the section of the Pine River that is farther downstream and appears less affected by contamination (OU4).  The results of the field pilot study will be incorporated into a second feasibility study for OU4. There is compelling evidence that carbon is effective at binding to contaminants like DDT reducing its ability to harm the environment.  Alma College will perform supporting work using Solid Phase Micro-Extraction (SPME), which is a specialized test to assess how animals in the ecosystem absorb chemicals like DDT. That absorption process is known as "bioavailability."

This testing will help scientists understand how much the carbon reduces bioavailability of contaminants to animals. In August, the activated carbon was placed in the pilot areas and testing is anticipated to go through spring 2020.

Velsicol Burn Pit
EPA completed the final design for the hook-up of nine homes to St. Louis municipal drinking water and the site preparation for in-place thermal treatment. This will include removal of the remnant burn debris material.

It is currently unknown if funding will be provided in 2020 for the site preparation or residential drinking connection. The in-place thermal treatment cannot begin until fall of 2021 at the earliest since only one thermal treatment project can operate at a time.

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Activity and Use Limitations

At this site, activity and use limitations that EPA calls institutional controls are in place. Institutional controls play an important role in site remedies because they reduce exposure to contamination by limiting land or resource use. They also guide human behavior. For instance, zoning restrictions prevent land uses – such as residential uses – that are not consistent with the level of cleanup.

For more background, see Institutional Controls.

On-site groundwater is contaminated with DDT, chlorobenzene, carbon tetrachloride, trichloroethylene (TCE), and other chlorinated compounds. Onsite soil samples revealed contamination with PBBs, copper, chromium, zinc, and magnesium. The sediments of the Pine River were also contaminated with similar contaminants through direct discharges from the site; however, surface waters do not show any significant impacts. Potential risks exist for people who eat contaminated fish and wildlife in the vicinity of the site.

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Sampling and Monitoring

Data is available on the in-place thermal treatment system. This system is installed at the site to capture underground contamination by heating the soil and capturing contaminated vapors. An interactive map shows system location and sampling data, including air monitoring data, collected during the operation of the thermal treatment system.

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