On this page:
- What Is Being Done to Clean Up the Site?
- What Is the Current Site Status?
- EPA’s Involvement at the Site
- Operable Units (opens new page)
- Cleanup Progress (opens new page)
The 200-acre West Lake Landfill Site is located at 13570 St. Charles Rock Road in the Earth City Industrial Park in Bridgeton, Missouri. It is surrounded by commercial/industrial and agricultural land on the eastern edge of the Missouri River flood plain. From 1939 to 1985, limestone was quarried on site. Beginning in 1962, parts of the site property were used for landfilling of municipal solid waste and construction debris. Two areas became radiologically contaminated in 1973 when soils mixed with uranium ore processing residues were used as daily cover in the landfilling operation. An adjacent property has also been impacted by erosional migration of radiologically contaminated material from the landfill. This property, known as the Buffer Zone or the Crossroad Property, was subsequently purchased by the landfill operator. It is considered part of the site and is enclosed within the site's perimeter security fence. Also located on the site is the Bridgeton Sanitary Landfill, which ceased operations in 2005. This sanitary landfill did not receive any radiologically contaminated soil.
What Is Being Done to Clean Up the Site?
The PRPs are performing additional studies to support EPA’s reevaluation of the 2008 remedy for OU-1. Access is currently restricted to the contaminated areas.
Off-site air monitoring was performed by EPA between May 2014 and February 2015 at five locations to determine preconstruction baseline concentrations for OU-1 contaminants of concern (COCs - radionuclides, particulates, and volatile organic compounds or VOCs). Monitoring for radionuclides at one station within Spanish Village continued through July 30, 2015. EPA is confident that the results of the data collected to date provide a sufficient baseline from which to compare any future off-site air monitoring for those compounds.
In early 2015, the PRPs installed 13 air monitoring stations around Areas 1 and 2 of OU-1. These stations became fully operational in May 2015 and will establish baseline air concentrations onsite for OU-1 COCs over the next year. These monitoring systems will subsequently be used by the PRPs to monitor site conditions, with EPA oversight, for any future on-site construction activities.
What Is the Current Site Status?
The PRPs are collecting additional data from OU-1. Once complete, the data will be used to further reevaluate the remedial alternatives presented in the 2011 SFS. EPA will then determine whether any changes to the 2008 remedy decision are warranted. The major components of the Selected Remedy for the OU-2 Inactive Sanitary Landfill includes: install landfill cover meeting the Missouri closure and post-closure care requirements for sanitary landfills, apply groundwater monitoring and protection standards consistent with requirements for sanitary landfills, surface water runoff control, gas monitoring and control consistent with sanitary landfill requirements as necessary, institutional controls to prevent land uses that are inconsistent with a closed sanitary landfill site, and long-term surveillance and maintenance of the remedy.
EPA’s Involvement at the Site
After listing the site on the National Priorities List (NPL) in 1990, EPA completed a preliminary study and determined that no immediate actions were necessary at the West Lake Landfill Site while site studies were underway. EPA divided the site into two areas, or operable units (OUs), for cleanup. OU-1 addresses radiologically contaminated landfill areas. OU-2 addresses three sanitary landfill cells containing municipal refuse and construction/demolition debris. Subsequently, EPA entered into a consent agreement with the responsible parties in which the parties agreed to perform field studies and engineering evaluations designed to identify the best strategies for cleanup. The Remedial Investigation and Feasibility Study (RI/FS) work was completed in 2006 and a proposed plan for both operable units (OUs) was published in June 2006. The Record of Decision (ROD) for OU-1 was signed in May 2008. The selected remedy calls for the installation of an engineered landfill cover system over radiologically contaminated areas, implementation of a long-term groundwater monitoring and cover maintenance program, and institutional controls to restrict access. The ROD for OU-2 was also signed in July 2008. Under this decision, the OU-2 non-radiological landfill units will be closed and monitored in accordance with Missouri solid waste regulations.
After the OU-1 ROD was signed, EPA continued to receive public comments about the selected remedy. In response to those comments, EPA tasked the potentially responsible parties (PRPs) to conduct a Supplemental Feasibility Study (SFS) for OU-1 that further evaluated the ROD-selected remedy, as well as full-scale excavation of the radiologically contaminated landfill material (also called radiologically impacted materials or RIM) and disposal either at a permitted off-site facility or in a new, on-site engineered disposal cell.
The estimated costs defined for each alternative in the December 2011 SFS Report triggered an early consultation with EPA’s National Remedy Review Board (NRRB). Since February 2012, the NRRB has provided suggestions relating to the SFS Report for consideration. These include: evaluating additional groundwater sampling to refresh the body of existing site data; conducting a more detailed study of the partial excavation alternative; and conducting a more detailed analysis of potential treatment technologies for radiologically contaminated landfill material. In June 2012, EPA Region 7 tasked the PRPs to perform this work under the existing Consent Order.
EPA Region 7 also performed additional radiation screening of the OU-1 surface and perform vertical gamma radiation screening in site monitoring wells.
In July and August 2012, the PRPs performed the first round of additional groundwater sampling. In November 2012, EPA staff performed the vertical gamma radiation screening in site monitoring wells to further refine distribution of radiologically impacted wastes. Three additional quarterly rounds were collected through early 2014. Data from these sampling events were independently evaluated for EPA by the US Geological Survey (USGS).
As previously stated, OU-2 addresses the other landfill areas that are not impacted by radionuclide contaminants. Missouri is a federally approved regulator for solid waste landfills. For areas operated under state permit (the Former Active Sanitary Landfill and the Closed Demolition Landfill), the terms of their respective permits dictate the appropriate closure and post-closure care requirements. Successful completion of these requirements would eliminate the need for further CERCLA action at these units. Consistent with EPA's policy on coordination between the Resource Conservation and Recovery Act and CERCLA actions, these regulated units are deferred to the state regulatory program. For the Inactive Sanitary Landfill, which was closed prior to state regulation, the Selected Remedy is containment with relevant and appropriate closure and post-closure care requirements identified through the CERCLA remedy selection process.
During cleanup, a site can be divided into a number of distinct areas depending on its complexity. These areas, called operable units (OUs), may address geographic areas, specific problems, or areas where a specific action is required. Examples of typical operable units include construction of a groundwater pump and treatment system or construction of a cap over a landfill.