More testing needed at West Lake Landfill

The Environmental Protection Agency (EPA) has been assisting in the investigation of radiologically impacted material (RIM) at the West Lake Landfill, Bridgeton, Missouri, with plans to develop a plan to clean up potential soil contamination at the site.

A team from the EPA’s Region 7 office on March 23 updated congressional staff, local officials and community representatives on the latest results from the investigation.

The West Lake Landfill is a Superfund site on the EPA’s National Priorities List. Beginning in 1973, an estimated 8,700 tons of 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, the EPA says.

The EPA is overseeing the Remedial Design Investigation of the site by the potentially responsible parties (PRPs). Investigators have been working to identify the boundaries of the RIMs to design the remedy.

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.

All the originally planned sampling for the design investigation was completed in January 2021. After that, 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, taking more soil samples. Once those are evaluated, it is possible that additional step-out borings will be needed. The PRPs will conduct any additional samples that are required.

Within the Operable Unit 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 a gravel parking lot. Investigators 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 off with no trespassing signs.

Operable Unit 1 is still being investigated. At the time of signing the Record of Decision Amendment in 2018, the EPA had enough information on the location and volume of RIM to evaluate cleanup alternatives that ultimately led to a change from a 2008 remedy, and the agency went on to spell out 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.

Work has also progressed on other critical design elements, including design of the cover system, excavation and loading procedures, disposal facility evaluations and plans for monitoring to be conducted during the cleanup.