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EPA finalizes cleanup plan for Ballard Mine

10/01/2019
Contact Information: 
Bill Dunbar (dunbar.bill@epa.gov)
206-553-1019

The Environmental Protection Agency has issued its final cleanup plan for the 534-acre Ballard Mine Site, a former open-pit phosphate mine located 13 miles north of Soda Springs, Idaho.

Monsanto operated the Ballard Mine from 1951 to 1969, when workers mined phosphate-rich rock and hauled it to Monsanto’s processing plant near Soda Springs. The approximately 19 million cubic yards of waste rock Monsanto left at the site contain elements that may be harmful to people and animals. In particular, the shale waste rock contains elevated levels of contaminants such as selenium, arsenic, naturally occurring uranium, and uranium-daughter products such as radium-226 and radon-222.

“The cleanup of the old Ballard Mine has been a long time in coming,” said EPA Regional Administrator Chris Hladick. “This Administration has placed a high priority on expediting Superfund cleanups to more quickly return contaminated sites to productive use. We’re pleased to say the pending cleanup of the Ballard Mine will do just that.”

In its cleanup plan, called a Record of Decision, the EPA divided the site into two “Operable Units”: Operable Unit 1 consists of six external waste rock dumps, six open pits, and an abandoned haul road, while the approximately 10-acre Operable Unit 2 consists of the Ballard Shop Area - the location for maintaining/garaging heavy trucks and mining equipment.

Cleanup methods and technologies were evaluated for their effectiveness in keeping contaminants from soil, sediment, surface water, and groundwater. Alternatives were evaluated against a list of nine criteria, including state, tribal, and community acceptance.

The selected remedy in the ROD is a combination of engineered source controls, treatment technologies, and other approaches and components. The ROD for “Operable Unit 1” includes the following key components:

Engineered Cover System. Mine pits will be filled to cover exposed ore beds and shale. A cover system five to six feet thick will be constructed over the 500+ acres where wastes remain.

Permeable Reactive Barriers (PRBs). A series of PRBs will be constructed downgradient of the source areas to intercept and treat contaminated groundwater.

Wetland Treatment Cells. Semi-passive bioreactors will be constructed on the margins of the site to remove selenium and other contaminants from seeps and springs.

Monitored Natural Attenuation (MNA) of contaminants in Groundwater. The remedy also recognizes that dilution and dispersion of groundwater contaminants will occur over time. EPA will monitor to determine if it’s occurring at the expected rate.

Stormwater and Sediment Control BMPs. During construction, sediment ponds and other control BMPs will be constructed to control release of sediment to downstream waterbodies.

Monitored Natural Recovery of Sediment (MNR). As with MNA for the groundwater, natural processes of dilution and dispersion are expected to result in natural recovery of these impacted areas and attainment of cleanup goals.

Institutional Controls and Access Restrictions. Institutional Controls will protect the remedy and prevent human exposure by limiting land and resource use. Fences, gates and, physical barriers will be built to prevent damage to engineered and vegetated remedy components.

About four million tons of phosphate ore remain at the site, both exposed at the surface and in the bottoms and sidewalls of existing mine pits. Although potential ore recovery is not part of the remedy, EPA’s ROD recognizes that P4 Production LLC, a Monsanto (now Bayer) subsidiary, intends to recover phosphate ore concurrent with implementation of the remedy. Ore recovery may help lower the costs of constructing the remedy.

The remedy is expected to cost approximately $41 million and take six to eight years for construction. Following construction, operations and maintenance will protect the cleanup work. Remedy effectiveness will be evaluated every five years after implementation.

For the 10-acre Ballard Shop Area/OU2, EPA will conduct a separate process for the development of a Feasibility Study, Proposed Plan, and eventually a ROD. P4 intends to continue the use of this area to support remedy implementation and nearby mining operations. The ROD for OU1, however, selects “Institutional Controls” (use restrictions on the area and its groundwater) and fencing as interim actions at the Ballard Shop Area to limit potential exposure to construction and mine workers until a final remedy is selected and implemented.

For more information on the Ballard Mine cleanup go to https://cumulis.epa.gov/supercpad/cursites/csitinfo.cfm?id=1002859

For more information on the Superfund program and processes go to https://www.epa.gov/superfund

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