Thursday, February 20, 2020

History of the West Lake Landfill Operating Unit 1 Superfund Site

  1. General Site Background and Disposal of Radiological Waste
  2. How Radiological Materials Reached the Landfill
  3. Investigating the Contamination at the Site
  4. Historical Timeline of Events
See Glossary of terms

1. General Site Background and Disposal of Radiological Waste

  • The West Lake Landfill Site is approximately 200 acres of property within the city limits of the City of Bridgeton in northwestern St. Louis County, approximately one mile north of the intersection of Interstate highways I-70 and I-270. The Missouri River lies about one and one-half miles to the north and west of the Site. The Site is generally surrounded by commercial/industrial properties.
  • The Site consists of a former permitted solid waste (trash) landfill – the Bridgeton Landfill – and several inactive solid waste and construction/demolition waste fill areas, including the old West Lake Landfill. The permitted Bridgeton Landfill closed in 2005; the property continues to operate as a trash transfer station where household trash from neighborhood trash trucks is consolidated into bigger loads and transported to landfills in the St. Louis metropolitan area.
  • The Site was a farm until 1939 when a limestone quarrying and crushing operation began. Starting in the early 1950s, portions of the quarry and adjacent areas were used to landfill municipal trash and refuse, industrial solid waste and construction/demolition debris. The quarry pits were permitted by the State of Missouri for solid waste landfill operations beginning in 1979; prior to that time, the State of Missouri did not set standards for landfills or issue permits.
  • In 1973, part of the Site became radiologically contaminated when soil mixed with leached barium sulfate residues were used as daily and intermediate cover in the West Lake Landfill solid waste disposal operations.
  • The U.S. Environmental Protection Agency (EPA) placed the Site on the Superfund National Priorities List (NPL) in 1990.
  • Radiological materials are found at two parts of the West Lake Landfill – OU-1 Rad Areas 1 and 2, and a narrow strip of adjacent property called the “Ford Property” or the “Buffer Zone/Crossroads Property.” The radiological materials are mixed with landfilled refuse, debris, soil and fill, and appear in both surface (the upper six inches of ground) and subsurface (7 to 12 feet or deeper) areas of the Site.
  • The radiologically-contaminated materials consist of approximately 146,000 cubic yards of commingled refuse, debris, fill materials and soil, distributed in various quantities and concentrations across, under, and in approximately 28 acres of landfill.

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2. How Radiological Materials Reached the Landfill

  • The material at the West Lake Landfill originated as part of the Manhattan Project at the Mallinckrodt Chemical Works plant in downtown St. Louis. From 1947 to the mid-1960s, the Atomic Energy Commission (AEC) stored Manhattan project waste, including leached barium sulfate cake residue, at properties in North St. Louis County now known as the St. Louis Airport Sites (SLAPS). In the 1960’s, the AEC moved these materials a half mile northeast, from the airport to AEC's Hazelwood Interim Storage Site (HISS).
  • In April 1962, a private company bought the ore residues and uranium and radium process wastes being stored at SLAPS from the AEC. In 1966, the company transported approximately 117,000 tons of these materials from SLAPS to 9200 Latty Avenue in north St. Louis County. These radioactive materials consisted of 74,000 tons of Belgium Congo pitchblende raffinate, 32,500 tons of Colorado raffinate, 8,700 tons of leached barium sulfate cake residue, 1,500 tons of unleached barium sulfate cake, and 350 tons of miscellaneous residues.
  • In 1967, a distressed assets recovery company seized the assets of the company which owned the radiological wastes stored at Latty Avenue and sold and shipped 70,000 tons of these radioactive materials to Canon City, Colorado. By December of 1970, the only materials still stored at Latty Avenue were an estimated 10,000 tons of Colorado raffinate and 8,700 tons of leached barium sulfate.
  • In 1973, the 10,000 tons of Colorado raffinate were shipped to Colorado. The remaining 8,700 tons of leached barium sulfate cake residue, the lowest activity-level material stored at the Latty Avenue location, was mixed with 39,000 tons of soil and the resulting 47,700 tons of material was taken to the West Lake Landfill in St. Louis County.
  • At West Lake, the 47,700 tons of soil mixed with leached barium sulfate cake residue was used to cover incoming refuse and solid waste.
  • The only radiological waste disposed at the West Lake Landfill was leached barium sulfate cake residue.

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3. Investigating the Contamination at the Site

  • The U.S. Department of Energy (DOE) and three private companies began investigating the contamination at the West Lake Landfill Site in 1993 under the supervision EPA and the Missouri Department of Natural Resources (MDNR).
  • The investigation including extensive sampling to determine the extent of the radiological contamination (as well as any other contamination caused by hazardous substances), including:
    • Airborne transport of radon gas and fugitive dust;
    • Rainwater runoff and transport of dissolved or suspended contaminants;
    • Erosion and transport of contaminated soils; and
    • Leaching of contaminants to the underlying groundwater.
  • Based on this investigation work (including installation and repeated sampling of numerous groundwater monitoring wells), EPA and MDNR determined that the West Lake Landfill contents show the same types of metallic and chemical contaminants as are present in any old municipal landfill, and that there is no underground plume of groundwater contamination hiding under or flowing from the Site.
  • A limited number of radiological contaminants have been detected in monitoring wells inside the Site. These include wells with total radium levels slightly greater than the maximum contaminant level (MCL) for drinking water systems, which is 5 picocuries per liter (pCi/l).
  • Updated groundwater monitoring performed in 2012 confirmed the findings of the earlier groundwater investigations and further demonstrated the likelihood of a natural source of radium at low levels in groundwater, based upon higher levels of radium observed upgradient of (and therefore not coming from) the OU-1 waste materials.
  • The results of decades of investigation conclusively show that the West Lake Landfill is not a source of a plume of radiological or chemical groundwater contamination which has or could migrate off the Site and impact water supply wells, water quality in the Missouri River, or the quality of water withdrawn from the Missouri River by any of the metropolitan St. Louis water suppliers. 

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1942: The Manhattan Engineering District (MED) achieves the first self-sustained nuclear chain reaction at Stagg Field at the University of Chicago using uranium oxide produced by the Destrehan Street Refinery and Metal Plant (later Mallinckrodt Chemical Works). Following the success of the Stagg Field experiment, the MED contracts with Mallinckrodt to process uranium. Under this contract, uranium and radium are extracted from ore and used to make the first atomic bombs. Years later, this facility will become known as the St. Louis Downtown Site (SLDS).

1945: The first atomic bomb is tested at White Sands Test Range in Alamogordo, New Mexico. On August 6 & 9, atomic bombs are detonated at Hiroshima and Nagasaki, leading to Japanese surrender in September. World War II officially ends.

1946: MED acquires land from the City of St. Louis and obtains consent to store process byproducts containing radioactive residuals from the Mallinckrodt plant. Most of the wastes and residues are stored on open ground. Some contaminated materials and scrap are buried at the western end and other parts of the site. Later, this land becomes known as the St. Louis Airport Site (SLAPS). Congress passes the Atomic Energy Act in September, which creates the five-member Atomic Energy Commission (AEC) to manage the atomic energy program. On December 31, the Manhattan Engineering District is deactivated. The newly created AEC assumes the Manhattan Engineering District's responsibilities.

1948: With AEC financing, Mallinckrodt begins to decontaminate Plants 1 and 2.


1951: The AEC releases the Mallinckrodt Plants 1 and 2 for use without radiological restrictions.

1957: AEC operations downtown close. From 1942 to 1957, the plant had processed more than 50,000 tons of uranium product. Contaminated scrap metal and miscellaneous radioactive wastes are transported to SLAPS and buried on the western edge of the property.


1960: AEC offers uranium processing residues and wastes at SLAPS for sale.

1965: In a waste inventory and radiological survey conducted at SLAPS, the AEC finds approximately 121,000 tons of uranium refinery residues and contaminated material.

1966: In February, Continental Mining and Milling Co. purchases wastes stored at SLAPS and begins moving them to 9200 Latty Avenue in Berkeley, Missouri. Improper storage, handling, and transportation of materials causes the spread of these materials along haul routes to Vicinity Properties (SLAPS VPs). The Latty Avenue property, where the wastes from SLAPS were stored, will later became known as the Hazelwood Interim Storage Site (HISS). After removal of most residuals to HISS, structures on SLAPS are demolished and buried on the property. Sixty truck loads of scrap metal and a contaminated vehicle are buried on the property. One to three feet of clean fill material are spread over SLAPS to achieve acceptable levels of surface radioactivity.

1967: Commercial Discount Corporation purchases the residues stored on HISS and after drying, ships much of the material to Canon City, Colorado.

1969: Cotter Corporation purchases the remaining residues at HISS, dries it and ships additional material to Canon City during 1970.


1970: The Environmental Protection Agency is formed.

1973: The AEC conveys the SLAPS property by quitclaim deed to the St. Louis Airport Authority. Cotter concludes its shipping operation at HISS. The remaining contaminated material (leached barium sulfate residue) is mixed with approximately 5 times as much topsoil "to disperse and dilute the uranium bearing residues" and disposed of in the West Lake Landfill in St. Louis County, MO.

1974: AEC established the Formerly Utilized Sites Remedial Action Program (FUSRAP) for the cleanup of sites not owned by the DOE but contaminated from past activities involving radioactive materials. The SLDS, SLAPS, SLAPS VPs, and HISS sites are eventually placed in FUSRAP. West Lake Landfill is eventually proposed for, and listed as, a Superfund site and is not a part of FUSRAP. In a reorganization of the state government, the Missouri Department of Natural Resources (MDNR) is formed.

1975: The Atomic Energy Commission is replaced by two new federal agencies. One is the Nuclear Regulatory Commission (NRC), which is charged with regulating the civilian uses of atomic energy (mainly nuclear power plants). The other is the Energy Research and Development Administration (ERDA), whose duties include the control of the nuclear weapons complex.

1977: ERDA is transferred to the newly created Department of Energy (DOE).

1978: An aerial survey sponsored by the Nuclear Regulatory Commission (NRC) detected two areas within the West Lake Landfill Site (Radiological Areas 1 and 2) with gamma radiation levels indicating the presence of radioactive materials. NRC concludes that the materials originated from Latty Avenue.


1981: SLAPS is designated for remedial action under FUSRAP.

1984: The Energy and Water Development Appropriations Act directs DOE to conduct a decontamination research and development project at four sites throughout the nation, one of which is HISS. Results of the survey demonstrate that the property exceeds guidelines for residual radioactive material given in DOE Order 5400.5. Subsequently, Congress adds HISS to FUSRAP in order to expedite decontamination. DOE is directed by Congress to reacquire SLAPS (Public Law 98-360) and use it as a permanent disposal site for waste already on the property, contaminated soil in the surrounding ditches, and the waste from HISS. The City of St. Louis refuses to transfer the property to the DOE.

1985: DOE performs a radiological survey of the roads thought to have been used to transport contaminated materials to and from SLAPS and HISS. Parts of Hazelwood Avenue, Pershall Road, and McDonnell Boulevard are designated by the DOE for remedial action.

1989: SLAPS and HISS are added to the Environmental Protection Agency's National Priorities List (NPL). This list requires the cleanup to proceed under the guidelines of the Comprehensive Environmental Response, Compensation, and Liability Act (CERCLA) as amended by the Superfund Amendments and Reauthorization Act (SARA).


1990: The Environmental Protection Agency (EPA) and DOE sign a Federal Facilities Agreement, which establishes an environmental review process and establishes a schedule for the remediation of SLAPS, SLDS, and HISS. The process requires DOE to evaluate alternatives for waste management, one of which is storage at SLAPS. The City of St. Louis offers to transfer the SLAPS property back to DOE under the condition that a permanent disposal cell for radioactive wastes will not be constructed on the site. The DOE declines acceptance of the SLAPS property from the city until the environmental review process is conducted. Due to the presence of radioactive waste at West Lake Landfill Radiological Areas 1 and 2, EPA lists the entirety of the 200 acre West Lake Landfill Site on the NPL, designating Radiological Areas 1 and 2 as Operable Unit 1 (OU-1), and the remainder of the site as Operable Unit 2 (OU-2).

1993: Three private Potentially Responsible Parties (PRPs) and the DOE sign an Administrative Order on Consent (AOC) and agree to perform a Remedial Investigation and Feasibility Study (RI/FS) for West Lake Landfill OU-1.

1994: The owner and operator of West Lake Landfill OU-2 signs an AOC with EPA to perform an RI/FS for OU-2, the non-radiologically impacted portions of the Site.

1994: Beginning of excavation and shipments of radiologically-contaminated materials to a licensed, out-of-state disposal facility for the SLAPS, HISS and SLDS FUSRAP sites.

1994 to 2000: Three private party PRPs and DOE undertake a Remedial Investigation at OU-1 in cooperation with EPA and MDNR. The Remedial Investigation Report, summarizing the extensive data collected through the evaluation, is finalized with EPA’s approval in April 2000.


2000 to 2006: Using the data gathered through the Remedial Investigation, the three private party PRPs and DOE undertake a Feasibility Study for OU-1 in cooperation with EPA and MDNR. The Feasibility Study, evaluating the remedial options for OU-1, is finalized with EPA’s approve in May 2006.

2006: EPA issues a Proposed Plan selecting an enhanced capping remedy for West Lake Landfill OU-1, and a solid waste cap for the inactive and demolition debris landfills at OU-2.

2006 to 2008: EPA takes extensive public comments and holds three public meetings prior to making a remedy decision regarding West Lake Landfill OU-1. The public comments focus primarily on the fact that Latty Avenue and other FUSRAP locations contaminated by the Manhattan Project wastes are being excavated and disposed of in out-of-state nuclear waste disposal sites by the Army Corps of Engineers.

May 29, 2008: EPA signs the Record of Decision (ROD) for West Lake Landfill OU-1. The selected remedy calls for the installation of an engineered landfill cover and implementation of a long-term monitoring program.

July 25, 2008: EPA signs the ROD for West Lake Landfill OU-2. Under this decision, the other landfill units will be closed and monitored in accordance with Missouri solid waste regulations.

October, 2008: EPA, DOE and the private PRPs amend the 1993 AOC for RI/FS work to allow performance of remedial design for the OU-1 ROD remedy.


January, 2010: EPA asks the PRPs to perform a Supplemental Feasibility Study (SFS) to evaluate the cost or practicality of two varieties of a full excavation remedy: one of which would excavate and remove all radiologically-contaminated materials from the Site and transport them to a licensed low-level radiological waste disposal facility in Utah, Idaho or Texas (off-site disposal); and the other which would do the same full excavation and removal of the radiological wastes, then re-dispose them on-site in a new landfill to be built within the 200 acre boundary of the overall property (on-site disposal).

May, 2010: EPA approves the PRPs’ work plan for performing the SFS analysis for the off-site and on-site excavation and disposal options.

2010-2011: The PRPs work in cooperation with EPA, with input of MDNR, to complete the SFS in accordance with the approved SFS Work Plan and EPA guidance.

December 30, 2011: EPA approves the final Supplemental Feasibility Study and releases the document for public review.

February 2012: EPA participates in early consultation with the National Remedy Review Board (“NRRB”) regarding EPA’s selection of the remedy and the Supplemental Feasibility Study.

May 2012: EPA directs the PRPs to perform an additional round of groundwater sampling to verify that current groundwater quality is consistent with conditions characterized during earlier sampling events in 1995, 1996, 1997 and 2004.

June 2012: Based upon NRRB recommendations EPA directs the PRPs to undertake more detailed evaluations of (i) the partial excavation alternative; (ii) alternative landfill cap designs; and (iii) treatment technologies. EPA memorialized these requests in an October, 2012 letter to the PRPs.

July-August 2012: The PRPs conduct the requested groundwater sampling event, sampling 75 wells in and outside of West Lake OU-1 for uranium, thorium and radium isotopes (both total and dissolved); total and dissolved trace metals; volatile organic compounds; and semivolatile organic compounds.

September 2012 - present: The PRPs prepare and submit for EPA review work plans detailing the scope and timing for the additional evaluations requested by EPA.

September-December 2012: The PRPs work to complete the Groundwater Monitoring Report detailing the results of the 2012 additional groundwater sampling event.

December 30, 2012: EPA accepts the 2012 sampling event Groundwater Monitoring Report.

January 31, 2013: EPA directs that the PRPs perform additional rounds of groundwater sampling to evaluate a full year’s worth of periodic testing for the Site, as set out in a January 31, 2013 letter.

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