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Weldon Spring Site
Interpretive Center Online Tour

Weldon Spring Site through the 20th Century


1900: In the southeastern part of St. Charles County along the banks of the Missouri River, the villages of Hamburg and Mechanicsville were thriving. Mechanicsville was renamed Howell in 1901. The town of Toonerville was established in this area in the 1920s.

1940: As the United States prepared to enter World War II, the U.S. Department of the Army, under a state of emergency, acquired 17,232 acres of land for the production of explosives. The people in the three small towns of Howell, Hamburg, and Toonerville were permanently displaced.

1941–1946: Atlas Powder Company, under contract with the U.S. Department of the Army, operated a
trinitrotoluene (TNT) and dinitrotoluene (DNT) production plant known as the Weldon Spring Ordnance Works (WSOW). In August 1945, as Americans celebrated the official end of World War II, termination of production at the WSOW was ordered. In 1946, the U.S. Army Corps of Engineers began to decontaminate the site. As a part of this effort, several production buildings were burned in place. At the time, burning was thought to be the safest way to dispose of structures that were contaminated with explosive dust and residue. The remaining explosives-contaminated buildings were burned in 1956 and 1957.

1942–1969: Limestone from the Weldon Spring Quarry, located 4 miles south of the Weldon Spring Site, was used to construct the roads and building foundations for the WSOW. Afterward, the quarry was used to dump debris generated from the cleanup efforts of the WSOW. Additional contaminated debris from various U.S. Department of the Army and U.S. Atomic Energy Commission operations was dumped into the Weldon Spring Quarry. During this time period, experts and officials believed that this was an acceptable and supported practice.

1942–1957: Under contracts with the Manhattan Engineer District and the U.S. Atomic Energy Commission (AEC), Destrehan Street Refinery and Metal Plant (later Mallinckrodt Chemical Works) processed various forms of uranium compounds at a facility in St. Louis. All operations ended at the St. Louis plant in 1957 after the AEC contracted with Mallinckrodt Chemical Works to build the Uranium Feed Materials Plant at Weldon Spring.

1947–1949: Much of the ordnance works land was transferred to public entities. The University of Missouri received 7,920 acres for agricultural research. The Missouri Department of Conservation (MDC) later purchased 7,200 acres from the University of Missouri and created the Weldon Spring Wildlife Area. The MDC received an additional 6,944 acres of the original ordnance works property and created the August A. Busch Memorial Wildlife Area. St. Charles County Public Schools received 37.9 acres, including the area where Francis Howell High School stands.

1950: Thirty homes were built a safe distance from the Ordnance Works in 1941 to house U.S. Department of the Army personnel operating the plant. In 1950, the homes were sold and the village of Weldon Spring Heights was incorporated.

1955: As the U.S. involvement in the Cold War with the former Soviet Union intensified, the U.S. Atomic Energy Commission (AEC), a predecessor to the U.S. Department of Energy, constructed the Uranium Feed Materials Plant on 205 acres acquired from the U.S. Department of the Army.

1957–1966: Mallinckrodt Chemical Works, contractor to AEC, operated the Uranium Feed Materials Plant. The plant was a uranium processing facility, which assayed "yellow cake" (uranium ore concentrate), converted it into uranium metal, and/or shipped it off for further processing at other sites. The uranium processed at the Weldon Spring plant was ultimately used in both the nuclear weapons and nuclear fuels cycle processes. In December 1966, AEC ceased operations at the plant.

1959: 1,858 acres of the original Ordnance Works property was designated as the Weldon Spring U.S. Department of the Army Reserve Training Area.

1967: AEC transferred about 169 acres of the Uranium Feed Materials Plant back to the Army. AEC retained ownership of the raffinate pit area and the quarry. The U.S. Department of the Army renamed it the Chemical Plant, and planned to use parts of the plant for production of a herbicide known as "Agent Orange" for use in the Vietnam War.

1969: After attempting to decontaminate and renovate several buildings at the Chemical Plant, the Agent Orange Project was cancelled. Reduced requirements for the herbicide and escalating cleanup costs resulted in the cancellation of the project. This cancellation took place prior to the receipt of any equipment or chemicals for production. No herbicides were ever produced.

1970–1980: Environmental concerns became a national issue. Congress passed the National Environmental Policy Act (NEPA) and the U.S. Environmental Protection Agency (EPA) was created. NEPA established a national policy to protect the environment. Several other environmental laws were also passed that affected water quality, air quality, and waste management. 

1980: Congress passes the Comprehensive Environmental Response, Compensation, and Liability Act (CERCLA), commonly known as Superfund. Superfund established a program to identify and clean up abandoned hazardous waste sites.

1985–1986: At the direction of the U.S. Office of Management and Budget, the U.S. Department of the Army transferred custody of the Chemical Plant to DOE. Under this direction, DOE was responsible for the cleanup, and the U.S. Department of the Army was required to pay part of this cost. DOE designated the site a Major Project called the Weldon Spring Site Remedial Action Project (WSSRAP), and funds for cleanup were requested from Congress. A project office was established at the site in 1986, and cleanup activities were initiated.

1987: The Weldon Spring Quarry was placed on the National Priorities List as a Superfund site because of the perceived threat to drinking water wells that were located less than a mile away. The wells provided drinking water to some users in St. Charles County.

1988: Additional cleanup investigations were initiated. Investigations included chemical and radiological soil sampling, off-site lake and stream sediment sampling, studies of fish and wildlife, groundwater monitoring, and numerous geological studies. The first work activities at the site included removing all exterior power and telephone lines and consolidating several hundred varieties of common industrial chemicals that were located throughout the site.

1989: EPA expanded the National Priorities List designation to include the Chemical Plant area. This combined listing of the quarry and Chemical Plant area was designated as the Weldon Spring Site.

1990: EPA placed the former Weldon Spring Ordnance Works on its National Priorities List but as a separate entity managed by the U.S. Army Corps of Engineers. This cleanup project adjacent to the DOE property was known as the Weldon Spring Ordnance Works Site.

1991: The Record of Decision (ROD) for the management of bulk wastes in the Weldon Spring Quarry was approved. A ROD is a written record that explains the selected plan for cleanup at a National Priorities List site. The ROD was one of the first in the nation signed by EPA for a DOE facility under CERCLA.

1991–1994: The 43 buildings and structures that made up the former Weldon Spring Uranium Feed Materials Plant were safely decontaminated and dismantled. Structural materials, machinery, and debris were placed on an engineered lay-down pad within the Chemical Plant boundary and were subsequently placed in the cell.

1992: Dewatering the Weldon Spring Quarry was the first step in the cleanup of the quarry. The Quarry Water Treatment Plant went into operation. Water pumped from the quarry was treated to remove its chemical and radiological contaminants, tested to confirm compliance with permits, and released through a pipeline to the Missouri River.

1993: A ROD for remedial action at the Chemical Plant was approved. The Site Water Treatment plant went into operation. Like the quarry water treatment, site water was treated, tested, and released through a pipeline to the Missouri River.

Removal of bulk waste from the quarry began in May. Haul trucks transported the waste to the site over the dedicated haul road, which paralleled Highway 94. The waste was then placed on an engineered lay-down pad within the Chemical Plant boundary.

1995: Bulk waste removal was completed after more than 120,000 cubic yards of contaminated waste was removed from the quarry.

The Missouri Department of Conservation (MDC) entered into a compensated agreement to permit DOE to remove clay soil material from land in the Weldon Spring Wildlife Area. Clay soil from what was termed the "Borrow Area" was used for construction of the disposal cell. A dedicated haul road was constructed leading from the Borrow Area, under a relocated section of Highway 94, to the Chemical Plant. DOE also agreed to restore the site to MDC requirements when borrow operations were complete. 

1995–1997: Removal of 33 major structure foundations and contaminated soil from 54 acres was completed. During this project, approximately 500,000 cubic yards of contaminated soil and concrete were excavated and stockpiled in the Ash Pond area of the site.

1996: The last shipment of the more than 20,000 gallons total of organic and aqueous liquids stored at the Chemical Plant site left for the K-25 incinerator facility in Oak Ridge, Tennessee.

1997: Groundbreaking ceremonies were held to commemorate the beginning of construction of the disposal cell. The ceremonies marked "the beginning of the end" of remediation activities required for environmental restoration of the Uranium Feed Materials Plant site, nearby vicinity properties, and the abandoned quarry previously used as a dump site for chemical and radiological wastes.

1998: The first load of contaminated waste was placed in the disposal cell on March 5. In November, the Chemical Stabilization and Solidification Plant completed processing sludge.

1998: The Ordnance Works Site cleanup included removal of TNT- and DNT-contaminated soils and underground wooden pipelines that were used to carry TNT wastewater from the production lines to the wastewater treatment plants. Incineration was selected as the treatment remedy because it was the only method of treatment that has been proven to permanently destroy TNT. After incineration, the ash was tested to confirm that cleanup standards had been met. The ash and other materials were placed in the disposal cell. The excavation areas were then backfilled. This cleanup was completed in 1999.

1999: The Weldon Spring Site Remedial Action Project received the DOE Voluntary Protection Program "Star" status for safety. This was the first DOE environmental remediation site to achieve the department’s highest award for excellence in safety.

2000: An interim Record of Decision was signed by DOE and EPA approving a plan to treat trichloroethylene (TCE) in the groundwater.

2001: The final load of waste was placed in the disposal cell on June 3, bringing the total amount of waste placed in the disposal cell to 1.48 million cubic yards. The "last rock" was placed on the cap of the 45-acre disposal cell on October 23. The disposal cell was complete.

2002: Final restoration of the Chemical Plant site and the quarry was completed. The areas were graded then seeded to minimize erosion and to return the areas to their natural contours. The official opening of the Weldon Spring Interpretive Center was celebrated in the summer. Haul roads were converted to a hike and bike trail, the Hamburg Trail, linking the historic Katy Trail from the quarry to the Chemical Plant site and to the wildlife center at the August A. Busch Memorial Wildlife Area. This trail gives visitors the opportunity to experience an important part of this of the county’s history while enjoying family-oriented recreation.

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Last Updated: 6/15/2015