West Lake Landfill

The Problem

In 1973, soils mixed with uranium ore processing residues and other materials were used during landfill operations, which radiologically contaminated former disposal areas of the site.

Contaminants of Concern

Contamination at the site includes radioactive waste and contamination typically encountered in solid waste landfills.

What’s Been Done  

Site investigation and cleanup is being conducted under CERCLA, and activities are ongoing. As a result of historical assessments, EPA ultimately placed West Lake Landfill on the National Priorities List in 1990, making it a Superfund Site. Each of the former waste disposal areas have contamination characteristics unique to that area. In order to address contamination more effectively, EPA divided the site into three distinct operable units (OUs).

• OU-1: Along with contamination typically encountered in solid waste landfills, OU-1 is also contaminated with radiological material and remediation soil transported from the Hazelwood Interim Storage Site. As a result of migrating radiologically impacted material (RIM), OU-1 also includes two neighboring properties, identified as Buffer Zone and Crossroads Lot 2A2. A final remedial action has been selected and its design is underway.
• OU-2: This unit consists of former waste disposal areas that are not known to be impacted by radiological materials. These disposal areas and expected contaminants were considered typical for solid waste landfills. A final remedial action has been selected, but design has been put on hold due to potential changes in OU boundaries.  
• OU-3: OU-3 addresses sitewide groundwater contamination. 

What’s Left

• OU-1: Remedial design is underway
• OU-2: Remedial design is underway
• OU-3: Investigation is ongoing

The remedial action phases will begin after the remedial design phases are complete and will involve the actual construction or implementation phase of site cleanup. Once the remedial action is implemented, the OU will move into the operation and maintenance phase. Long-term stewardship will continue for institutional controls put in place to protect human health and the environment from contamination that remains after cleanup. 

Looking to the Future

The parties involved are working towards closing out and deleting (removing) the site from the National Priorities List. The remedial actions are selected to protect humans or other organisms from coming into contact with, or being harmed by contamination that remains after cleanup. Activity and use restrictions will be put in place, and are determined based on the contamination that remains in that area of the site. As studied in the baseline risk assessment, the risk of harm assumes the property will only be used for restricted industrial or commercial purposes, depending on the contamination in that area. 

Site Description

The West Lake Landfill site is located on over 200 acres at 13570 St. Charles Rock Road, in Bridgeton. The site sits within the Earth City Industrial Park and is surrounded by commercial, industrial, residential and agricultural land on the eastern edge of the Missouri River floodplain. In 1939, the land became a limestone quarrying and crushing operation. Beginning in the early 1950s, portions of the quarried areas and surrounding areas were used to dispose municipal solid waste, industrial wastes and construction and demolition debris. In 1973, around 8,700 tons of leached barium sulfate from the Manhattan Project, a World War II nuclear bomb development program, and other material from the Hazelwood Interim Storage Site was mixed with approximately 38,000 tons of soil and used during landfill operations. 

The site contains several former waste disposal areas, including the Bridgeton Sanitary Landfill, the Inactive Sanitary Landfill and the Closed Demolition Landfill. The Bridgeton Landfill stopped accepting wastes Dec. 31, 2004. 

The Problem

In the mid-1970s, the department and Nuclear Regulatory Commission investigated reports of radioactive material transported to a local landfill. Initial site assessment and investigation results showed the uranium ore processing residues and other material radiologically contaminated two of the former disposal areas of the site (Area 1 and Area 2). Property next to Area 2 (Buffer Zone and Crossroads Lot 2A2) were also impacted by radiologically impacted material (RIM) migrating from Area 2, presumably through historic erosion. The Bridgeton Landfill is not known to be impacted by RIM.

MoDNR conducted follow up investigations, not part of EPA's formal site investigation. On Feb. 2, 2013, MoDNR and Missouri Department of Health and Senior Services staff conducted radiological surveys and collected deposition dust samples near the site, using odor as a wind direction indicator. The upwind and downwind readings were compared for differences in radiological readings. 

• West Lake Landfill Radiological Survey Report, May 2013 
• Department of Health and Senior Services, Bridgeton/ West Sanitary Landfill Radiological Air Sampling, June 2013

On Nov. 4-6, 2015, MoDNR and Missouri Department of Health and Senior Services staff conducted radiological surveying and sampling near West Lake Landfill. The investigation report was released in two phases, interim reports and final reports. The interim reports described the investigation and presented immediately available data. The final reports supplemented the interim report with laboratory sample results and investigation conclusions. 

• West Lake Landfill Vicinity Radiological Survey and Sampling Nov. 4-6, 2015 Interim Report, January 2016 - MoDNR
• West Lake Landfill Vicinity Radiological Survey and Sampling Final Report, March 2016 - MoDNR
• Bridgeton/ West Lake Landfill Radiological Sampling Interim Report, January 2016 - DHSS
• Bridgeton/ West Lake Landfill Radiological Sampling Final Report, May 2016 - DHSS

Environmental Restoration

Site investigation and cleanup is being conducted under CERCLA, which allows federal and state governments to clean up hazardous waste sites and to force responsible parties to perform cleanups or reimburse the government for cleaning up hazardous waste sites. CERCLA cleanups follow a multi-phase process. After a site has gone through initial assessment and investigation, that information is used to evaluate the potential risks posed by the site. The Hazard Ranking System is used to numerically “score” the site. Sites that score at or above an established number of points qualify for cleanup under Superfund and are proposed for listing on EPA’s National Priorities List. As a result of historical assessments, EPA ultimately placed West Lake Landfill on the National Priorities List in 1990, making it a Superfund Site.

During the cleanup process, 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. Each of the former waste disposal areas at the West Lake Landfill site have contamination characteristics unique to that area. In order to address contamination more effectively, EPA divided the site into three OUs. Each of the OUs is proceeding through the cleanup process separately:

• OU-1: Along with contamination typically encountered in solid waste landfills, OU-1 is also contaminated with radiological material.
• OU-2: OU-2 consists of former waste disposal areas that are not known to be impacted by radiological materials. These disposal areas and expected contaminants are typical for solid waste landfills.
• OU-3: OU-3 addresses sitewide groundwater contamination.

Details about the investigation and cleanup activities for each OU is discussed on the corresponding tabs above. For more information about the cleanup process, visit the department's Superfund Cleanups webpage.

Contamination Description

Operable unit (OU)-1 contains radioactive contamination identified as radiologically impacted material (RIM). EPA’s 2018 amended record of decision identified contaminants that risk human health and the environment through the quantitative (detailed numerical) risk assessment and evaluation of potential exposure pathways found in the remedial investigation addendum. The contaminants include:

• Radiological contaminants of concern: radionuclides within the natural decay series of uranium 238, uranium 235 and thorium 232
• Inorganic chemicals of concern: antimony, arsenic, barium, beryllium, chromium (+6), cobalt, lead, mercury, nickel, thallium, uranium metal, vanadium and zirconium
• Pesticides and polychlorinated biphenyls (PCBs): aldrin/ dieldrin and aroclor 1242, 1248 and 1254
• Semi-volatile and volatile organic compounds: benzene, chlorobenzene, 1,1-dichloroethane, 1,4-dichlorobenzene, ethylbenzene, naphthalene and pentachlorophenol

What’s Been Done

The remedial investigation and feasibility study phase for OU-1 began March 3, 1993, when EPA signed an Administrative Order on Consent for Remedial Investigation/ Feasibility Study, Docket No. VII-93-F-0005. Following the required public notice and opportunity for comment on the West Lake Landfill OU-1 and OU-2 Proposed Plan, EPA decided on a remedial action in May 2008. EPA issued a Record of Decision - Operable Unit 1 that describes the final remedial actions selected, taking into account studies, public comments and community concerns.

In response to a brush fire that occurred at the property entrance on Oct. 24, 2015, EPA ordered the responsible parties to perform a time-critical removal action in a Unilateral Administrative Order for Removal Action, Docket No. CERCLA-07-2016-0002, dated Dec. 9, 2015. The order included the following components:

• Placing non-combustible cover over portions of OU-1 where RIM is located at or near the surface
• Performing tests and surface surveys to confirm surficial RIM was covered
• Determine the potential radiological risk from combustion of the remaining vegetation in OU-1
• Maintain the non-combustible cover
• Develop a sitewide incident management plan for responding to incidents affecting OU-1
• Action documents and reporting requirements, such as submitting monthly activity reports that include repair and maintenance of the cover and submitting a final action report when all action is completed

While placing non-combustible cover over surface RIM on steep slopes in Area 2, 167 tires were found lining one of the slopes. The responsible parties developed a cleaning, screening and disposal plan that EPA approved before the tires were removed from the site.

EPA re-entered the remedial investigation and feasibility study phase to bring in new data and review a broader range of potential remedies. Based on the new information, EPA determined an amendment to the original remedial action was needed in order to be protective of health and the environment. Following the required public notice and opportunity for comment on the Proposed Record of Decision Amendment, EPA decided on a final remedial action on Sept. 27, 2018. EPA issued a Record of Decision Amendment - Operable Unit 1 explaining the amended remedy.

EPA West Lake Landfill Remedial Design Investigation Interactive Map

What’s Left

OU-1 is currently in the remedial design phase of the Superfund cleanup process. EPA and the responsible parties agreed to add remedial design work to the existing settlement agreement, which was added through a Third Amendment to Administrative Settlement Agreement and Order on Consent, Docket No. VII-93-F-0005, dated May 6, 2019. The remedial design phase covers pre-construction investigation and planning activities in preparation for remedial action at the site. Monitoring and safety planning are essential components of remedial design that evolve as the project moves into remedial action. For OU-1, the safety-planning document is referred to as the emergency response plan. The phases for design of the OU-1 remedy are outlined in Section 6 of EPA’s statement of work, which is included in the above amendment to the settlement agreement and order. OU-1 also has a preliminary excavation plan document, which describes how total activity will be calculated to show conformity with requirements of the record of decision. When final, the excavation plan should describe the boundaries of the planned excavation.

The department and EPA continue to review additional documents submitted by the responsible parties. The agency review and approval process can take a substantial amount of time due to the size and scope of these documents. Site documents and data are available on EPA's Westlake Landfill webpage.

After the remedial design phase is complete, the following activities will occur:

• The parties will continue to negotiate a consent decree and settlement agreement for implementing and constructing the remedial action
• The remedial action phase will begin, which involves the actual construction or implementation phase of site cleanup
• Operation and maintenance of the remedial action
• Long-term stewardship will continue for institutional controls put in place to protect human health and the environment from radiological contamination that remains in OU-1 after cleanup

Looking to the Future

The remedy was selected to protect humans or other organisms from coming into contact with, or being harmed by radiological contamination. Since some radcontamination will be left behind after the partial excavation, the site will need activity and use restrictions to ensure that unacceptable exposure to residual contamination does not occur in the future. As studied in the baseline risk assessment, the risk of harm assumed that the property will only be used for restricted industrial purposes. Based on this assumption, site redevelopment may be severely restricted for thousands of years.

Contamination Description

Operable unit (OU)-2 contains contamination that is assumed to be typical of solid waste landfills. The former waste disposal areas are not known to be impacted by radiological materials.

• Carcinogenic (cancer causing): arsenic, benzene, vinyl chloride
• Non-Carcinogenic (non-cancer health impacts): chloride, fluoride, iron, manganese, total dissolved solids and total petroleum hydrocarbons

What’s Been Done

OU-2 currently is made up of three former waste disposal areas: the former Active (Bridgeton) Sanitary Landfill, the Inactive Sanitary Landfill and the Closed Demolition Landfill. The remedial investigation and feasibility study phase for OU-2 began Dec. 14, 1994, when EPA signed an Administrative Order on Consent for Remedial Investigation/ Feasibility Study, Docket No. VII-94-F-0025. The West Lake Landfill OU-2 Remedial Investigation Report was revised in September 2005 and West Lake Landfill OU-2 Feasibility Study Report was revised in June 2006. Following the required public notice and opportunity for public review and comment on the West Lake Landfill OU-1 and OU-2 Proposed Plan, EPA decided on a remedial action in July 2008. EPA issued a Record of Decision - Operable Unit 2 that describes the final remedial actions selected, taking into account studies, public comments and community concerns. EPA selected separate remedies for each disposal area and retained regulatory authority for the Inactive Sanitary Landfill. EPA deferred the Bridgeton Sanitary Landfill and Closed Demolition Landfill to the department for oversight under state regulatory authority. The department’s Waste Management Program oversees closure and post-closure of these former waste disposal areas.

On Dec. 23, 2010, the responsible party reported to the department that the Bridgeton Sanitary Landfill was experiencing elevated temperatures on some gas extraction wells. The facility began testing landfill gas from the gas extraction system and found elevated hydrogen, carbon monoxide and reduced methane concentrations, which indicated a subsurface smoldering event. The subsurface smoldering event was the result of subsurface exothermic events (chemical reactions that release heat). On May 13, 2013, the state of Missouri and Bridgeton Landfill entered into a First Agreed Order of Preliminary Injunction, Case No. 13SL-CC01088, to address the subsurface smoldering event. The agreed order included a phased sampling program in Bridgeton Landfill near OU-1, Area 1, to identify potential locations for installing a barrier between radiologically impacted material and the existing smoldering event. EPA later took the lead regulatory role in the investigation and approved the investigation results in April 2017, which expanded the previously defined boundaries of OU-1, Area 1. 

The responsible party also developed and continue to implement a baseline air-monitoring program as part of EPA’s Administrative Settlement Agreement and Order on Consent for Removal Action - Preconstruction Work, Docket No. CERCLA-07-2014-0002, dated April 16, 2014. In EPA’s follow-up Administrative Settlement Agreement and Order on Consent for Removal Actions, Docket No. 07-2016-0005, dated April 28, 2016, the responsible party implemented engineering controls within portions of the Bridgeton Landfill to mitigate potential impacts to OU-1, Area 1. These controls include:

• Inert gas injection plan
• Installing ethylene vinyl alcohol cover over the north quarry area of Bridgeton Landfill
• Installing a system of temperature monitoring probes in the north quarry area of Bridgeton Landfill
• Installing a heat extraction system in the neck area of Bridgeton Landfill, based on the work plan document the department conditionally approved Dec. 4, 2015
• Two sulfur dioxide ambient air monitors and monitoring for one year
• Action documents and reporting requirements, such as submitting monthly activity reports, monitoring results and a final action report when the action is complete

The responsible party continues to operate and monitor the systems. For more information, visit the department's Bridgeton Sanitary Landfill webpage. 

EPA West Lake Landfill Remedial Design Investigation Interactive Map

What’s Left

OU-2 is currently in the remedial design phase of the Superfund cleanup process. EPA and the responsible party agreed to add remedial design work to the existing settlement agreement. The phases for design of the OU-2 remedy are outlined in EPA’s West Lake Landfill OU-2 Statement of Work Remedial Design, dated Oct. 7, 2008. The remedial design phase covers pre-construction investigation and planning activities in preparation for remedial action at the site.  

EPA retained regulatory oversight for the Inactive Sanitary Landfill and the department’s Waste Management Program has regulatory oversight of the former Active (Bridgeton) Sanitary Landfill and Closed Demolition Landfill. The department and EPA continue to review additional documents submitted by the responsible party. The agency review and approval process can take a substantial amount of time due to the size and scope of these documents. Site documents and data are available on EPA's West Lake Landfill webpage. 

EPA reports that the remedial design for the Inactive Sanitary Landfill is expected to be completed at the same time as the design of the remedy for OU-1, Area 2. After the remedial design phase is complete, the following activities will occur:

• The parties will continue to negotiate a consent decree and settlement agreement for implementing and constructing the remedial action
• The remedial action phase will begin, which involves the actual construction or implementation phase of site cleanup
• Operation and maintenance of the remedial action
• Long-term stewardship will continue for institutional controls put in place to protect human health and the environment from contamination that remains after cleanup

EPA deferred the Bridgeton Sanitary Landfill and Closed Demolition Landfill to the department for oversight under state regulatory authority. The department’s Waste Management Program is overseeing closure and post-closure of the Bridgeton Sanitary Landfill and Closed Demolition Landfill.

Looking to the Future

The remedy was selected with the intent to protect humans or other organisms from coming into contact with, or being harmed by contamination typically found in municipal landfills. Since contamination will be left in place when the cap is installed, the site will need activity and use restrictions to ensure the cap is protected and unacceptable exposure to contamination does not occur in the future. As studied in the baseline risk assessment, the risk of harm assumed that the property will only be used for commercial and industrial purposes. Based on this assumption, future use in OU-2 will likely be restricted based on regulatory restrictions. 

Contamination Description

Operable unit (OU)-3 contaminants of concern will be identified through the remedial investigation and associated risk assessment.

What’s Been Done

OU-3 was discovered through information compiled from OU-1 and OU-2. 

EPA West Lake Landfill Remedial Design Investigation Interactive Map

What’s Left

OU-3 is currently in the remedial investigation and feasibility study phase. This phase began Feb. 6, 2019, when EPA signed an Administrative Settlement Agreement and Order on Consent for Remedial Investigation/ Feasibility Study, Docket No. CERCLA-07-2018-0259. The respondents are performing groundwater investigations based on the EPA approved work plan. If a remedial action is determined to be necessary after the remedial investigation and feasibility study phase is complete, the following activities will occur:

• Proposed plan, public comment and record of decision
• The parties will negotiate a consent decree and settlement agreement for implementing and constructing the remedial action.
• Design, construct and implement the remedial action.
• Operation and maintenance of the remedial action.
• Closeout and deletion (removing) the site from the National Priorities List.
• Long-term stewardship of institutional controls put in place to protect human health and the environment from contamination that remains after cleanup.

Looking to the Future

The outcome of additional groundwater investigation will determine what action will be required in the future.