West Lake Landfill - Going Forward
EPA is working to complete the evaluation of the 2008 ROD. The results of additional site characterization and assessments will be used in a revised evaluation of various remedial options, including the 2008 selected remedy, partial excavation, and full excavation. By the end of 2016, EPA will present its proposed decision on whether or not to make changes to the 2008 ROD to the community with an opportunity to comment. After the public comment period closes, EPA will release its final remedy decision.
Isolation Barrier System
In December 2010, Bridgeton Landfill LLC notified Missouri Department of Natural Resources (MDNR) that it found elevated temperatures in its south quarry. The company and MDNR eventually determined this to be an underground smoldering event. A subsurface smoldering event (SSE) is a high-temperature, self-sustaining (without the need for oxygen), chemical reaction that is consuming the buried waste (accelerating decomposition).
The most recent testing data indicate the SSE has not migrated past the area referred to as the “neck” which lies between the Bridgeton Landfill North and South Quarries. A series of temperature monitoring probes and gas extraction wells, in addition to visual observation and other methods, provide data to monitor the SSE.
On Dec. 31, 2015, EPA announced its decision to proceed with the installation of an isolation barrier. The decision calls for the installation of additional engineering controls, such as cooling loops, to prevent potential impacts that could result if a SSE were to come into contact with radioactive materials contained in the West Lake Landfill.
EPA will continue to work closely with MDNR with expert support from the Army Corps of Engineers. EPA will release additional information, such as location of the barrier, once plans are finalized.
It is important to fully characterize the extent of any groundwater contamination in order to determine whether remedial actions are warranted. EPA intends to investigate and address groundwater as Operable Unit (OU-3). (WILL NEED MAP)
EPA, with technical support from the U.S. Geological Survey, is developing the scope of additional groundwater investigations to fully characterize the nature and extent of contamination, if there is any related to the site.
Surface Fire Prevention
EPA issued a Unilateral Administrative Order (UAO) on December 9, 2015, for a time-critical removal action to reduce or prevent the risk of surface fires in areas where RIM is located at or near the surface. A UAO is an enforceable order requiring the completion of specified actions.
A surface fire could potentially lead to a release of radionuclides near areas where radiologically impacted materials are located at or near the surface, creating an on-site hazard for workers at the site. To mitigate this risk, the UAO requires the Potentially Responsible Parties (PRPs) to:
- Implement engineering measures to mitigate the risk of a surface fire within the boundary of the West Lake Landfill site coming in contact with radiologically impacted material at or near the surface, and
- Develop an incident management plan that will be used to coordinate with local emergency responders.
This work is expected to be completed in late spring of 2016. The PRPs provided EPA with a draft work plan and supporting documents for construction of a non-combustible cover and an incident management plan. EPA is currently reviewing these documents, which will be made available to the public upon approval. Following completion of this work, a final report documenting the activities will be made available to the public once finalized.
Air Monitoring, and Soil Testing
EPA continues to oversee work at the site, which includes air monitoring and soil sampling. As the lead regulatory agency at the West Lake Superfund Site, EPA will continue to direct and oversee actions taken to investigate site conditions, evaluate response action alternatives, and implement protective actions.