Eastern Michaud Flats Contamination
EPA ID# IDD984666610
EPA Region 10
Power and Bannock Counties

2nd Congressional District

Other Names: FMC Corporation
J. R. Simplot, Simplot Don Plant
Last Update: October, 2011

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The Eastern Michaud Flats (EMF) Superfund Site is located in Southeast Idaho, approximately 3 miles northwest of Pocatello, Idaho. Within the site boundaries are two adjacent phosphate ore processing facilities, the FMC Corporation and the J.R. Simplot Company, began operation since the 1940s. The J.R. Simplot Don Plant (Simplot) is still an active facility; the FMC Corporation Elemental Phosphorus Plant (FMC) ceased operations in December 2001 and was subsequently demolished. The main portion of the site is roughly 2,475 acres in size, which is 1,450 acres for the FMC Operable Unit and 1,025 for the Simplot Operable Unit). The EMF Superfund Site also includes the Off-Plant Operable Unit, which encompasses the areal extent of contamination at or from both plants outside of the previously defined operable units.

The J.R. Simplot facility produces 12 principle products, including five grades of solid fertilizer and four grades of liquid fertilizers. The raw materials for their processes are phosphate ore (transported to the plant via a slurry pipeline from the Smoky Canyon Mine), sulfur, air and natural gas. The primary waste by-product from the Simplot plant is phosphogypsum, which is pumped as a thick slurry to large unlined stacks south of the processing plant.

The FMC plant produced approximately 250 million pounds of elemental phosphorus per year from two million tons of shale, silica, and coke; the elemental phosphorus was sold and used in a variety of products from cleaning compounds to foods. Ore was shipped to the plant in railcars and stockpiled at the plant. The primary by-products from the production process were slag (stored on-site), ferrous-phosphate residuals, carbon monoxide and several aqueous streams (such as phossy water/solids, precipitator slurry, calciner water/solids, and industrial wastewater). Most of the aqueous streams were managed in lined surface impoundments some of which were subject to regulation under the federal Resource Conservation and Recovery Act. FMC shut down operations in December 2001.

In 1976, the Idaho Department of Health and Welfare conducted a groundwater monitoring study down gradient from the plants. The investigation showed elevated levels of arsenic, lead and cadmium above Federal Drinking Water Standards. Further sampling during the 1980s confirmed these results, and the site was listed on the National Priorities List on August 30, 1990.

The Michaud Flats are on the Snake River Plain and are bordered by the American Falls Reservoir, the Portneuf River, Rock Creek, and on the south by the foothills of the Deep Creek Mountains and Bannock Range. The Portneuf River, which is located 1/4 mile from the site, is used for fishing, recreation, and irrigation downstream from the site. The Portneuf River flows back onto the Fort Hall Reservation 1 mile downstream of Batiste Spring, an area where contaminated groundwater flows into the surface waters of the river. The river flows through the "Bottoms" area of Fort Hall, a wetland that is sacred to the Shoshone-Bannock Tribes, then into the American Falls Reservoir.

Site Responsibility: This site is being addressed through federal and potentially responsible parties' actions.

NPL Listing HistoryDates
Proposed Date:05/05/1989
Removed Date:
Withdrawal Date:
Final Date:08/30/1990
Deleted Date:

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Media Affected: Groundwater, Soil
On-site groundwater has been affected by releases from unlined waste management facilities at both FMC and Simplot. The primary contaminants of concern for groundwater and surface water are arsenic and phosphorus. Groundwater moves generally north-northeast underneath the facilities and discharges to springs and to the Portneuf River. The largest single known source of phosphorus, relative to regionally observed phosphorus concentrations, discharges from EMF site groundwater into the Portneuf River. Phosphorus in groundwater currently discharges to surface water at over10 times the TMDL of 70 ppb. Off-site soils contain elevated levels of fluoride, radium-226, and cadmium to the north/northwest of the facility as a result of airborne releases from plant processes. Some of the on-site soils contain elevated levels of cadmium, chromium, copper, lead, nickel, silver, vanadium, zinc, radium-226, and fluoride.

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SITE MANAGER(S):Chris Bellovary (Simplot OU), Kevin Rochlin (FMC OU)
E-MAIL ADDRESS:bellovary.chris@epa.gov, rochlin.kevin@epa.gov
PHONE NUMBER:206-553-2723
E-MAIL ADDRESSphalen.dan@epa.gov
PHONE NUMBER:206-553-8578
Information pertaining to this site is housed at the following location(s):
Idaho State University Library
Reference Section
850 South 9th Avenue
Pocatello, Idaho 83209
(208) 282-3152

Shoshone-Bannock Library
Tribal Business Center
Pima Drive and Bannock Avenue
Fort Hall, Idaho 83203
(208) 478-3882

EPA Region 10 Superfund Records Center
1200 Sixth Avenue, ECL-076 (7th Floor)
Seattle, WA 98101
(206) 553-4494