A team from the U.S. EPA Region 7 is in Bridgeton, Missouri, to update congressional staff, local officials, and local community representatives on the latest results from the investigation at the West Lake Landfill. EPA is overseeing the Remedial Design Investigation of the site by the Potentially Responsible Parties (PRPs). Following EPA’s requirements and under its oversight, the PRPs have been working to identify the boundaries of the radiologically impacted material to design the remedy. The West Lake Landfill is a Superfund site on the National Priorities List. Beginning in 1973, an estimated 8,700 tons of radiologically impacted material, or RIM, was mixed with 39,000 tons of soil and transported to the landfill. This mixture was then used as cover material in landfill operations.
Summary of Recent Remedial Design Investigation Results
So far during the investigation, the PRPs have identified RIM in areas that were scheduled for sampling, as well as in some “step-out” sample locations on the site. The PRPs collect these step-out samples when RIM is located beyond the original planned sampling areas. RIM has been located above and below a depth of 20 feet.
The West Lake Landfill Site Operable Unit 1 also includes part of the Lot2A2 property. EPA required the PRPs to sample part of the Lot2A2 property, to the north and immediately adjacent to the landfill facility. Within the OU-1 site boundary at the property, recent samples found RIM below the surface, which is consistent with past findings in this area, and one surface sample to the west of the gravel parking lot. EPA and the PRPs worked with the property owners to cover that sample location with gravel. It will be cleaned up as part of further operations. The location is on private property not readily accessible to the public and is partially fenced and posted with no trespassing signs.
The included map below shows the West Lake Landfill Superfund Site boundary and locations where drilled boring samples have been taken during the investigation by the PRPs with EPA oversight through March 18, 2022. The map will be updated once a review of the findings so far is complete and will identify which locations sampled contain radiologically impacted material.
Operable Unit 1 is currently in the Design Investigation phase of the Remedial Design. At the time of signing the Record of Decision Amendment (RODA) in 2018, EPA had enough information on location and volume of RIM to evaluate cleanup alternatives that ultimately led to a change from the 2008 remedy, and the Agency went on to spell out numerous specific actions needed to design the new partial excavation remedy. EPA documented that additional samples were to be collected during the Remedial Design phase to confirm the extent of RIM near the boundaries of Areas 1 and 2 to ensure that the engineered cover is properly placed over all areas where RIM will remain on-site and to support the basis and locations for targeted excavation specified in the optimization plan.
All the originally planned sampling for the Design Investigation was completed in January 2021. After that point, a series of additional step-out borings were collected to identify the outer boundary of RIM. Because additional areas of RIM have been identified, the PRPs have continued the search by stepping out to sample. Once those samples are evaluated, it is possible that additional step-out borings will be needed. The PRPs will conduct any additional samples that are required.