[7] In 1973, after having changed hands (and responsible oversight) several times, B&K Construction Co., a company contracted by Cotter Corporation, dumped a portion of the original stored radioactive material at a nearby storage facility.

[8][9][10] The leached barium sulfate was a byproduct of Mallinckrodt Chemical Works’ uranium enrichment program as a part of the Manhattan Project and later nuclear weapons production,[11] and dumping it there was illegal.

[16] The EPA has listed four potentially responsible parties: the US Department of Energy; the Cotter Corporation; and Republic Services subsidiaries Bridgeton Landfill and Rock Road Industries.

[5][20] After receiving additional comments from environmental groups and the general public, the EPA asked the potentially responsible parties to commission a study of alternative cleanup options.

Known as “Excavation Plus” or “Alternative 4,” the plan involved removing radioactively impacted material with a concentration greater than 52.9 picocuries per gram (pCi/g), to a maximum depth of 16 feet.

Potentially responsible parties, including Bridgeton Landfill LLC, Rock Road Industries Inc., Cotter Corporation, and the Department of Energy are liable for the costs of the clean-up.

[5][37] The EPA commissioned a supplemental feasibility study,[38][39] which followed internal agency deliberations and consideration of comments provided by interested community members.

[46][47] SSEs are a form of chemical combustion that occur deep within a landfill and produces no visible flame or quantity of smoke, unless they reach the surface, where oxygen is abundant.

[50] The EPA, working in conjunction with the Missouri Department of Natural Resources, the US Army Corps of Engineers and others, announced a decision in December, 2015, to install a physical isolation barrier for the West Lake Landfill Superfund Site.

[52] The amount of radon gas was well below the level that causes lung cancer, groundwater near the landfill moves away from the surrounding communities and is not used for drinking water, and soil samples showed no evidence of radioactive contamination.

[52][53] In mid-2016 there was a movement for control of the West Lake landfill to be shifted to the Formerly Utilized Sites Remedial Action Program (FUSRAP), administered by the United States Army Corps of Engineers.

[54] In addition, key US congressional energy committee members, along with the US Army Corps of Engineers oppose a proposal by Missouri's delegation to move the landfill's oversight from the EPA Superfund to FUSRAP.