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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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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Early Response Actions:
In 1991, EPA issued an Administrative Order on Consent (AOC) to FMC and Simplot to jointly perform a remedial investigation/feasibility study to determine the nature and extent of site contamination (completed in April, 1997). In 1993 EPA issued a second AOC to FMC to close Pond 8S. A Record of Decision for the site was issued on June 8, 1998, requiring capping of contaminated soils at the FMC plant, containment of contaminated groundwater from the EMF site, and further monitoring and institutional controls at both plants as well as areas beyond the boundaries of both plants. The site has been divided into three separate cleanup areas called operable units (OUs): the former FMC Plant OU, the Simplot Don Plant OU and the Off Plant OU.

Remedial Actions - Simplot OU
Simplot entered into a Consent Decree in 2002 to conduct remedial actions within the Simplot Don Plant Facility operable unit. Groundwater extraction wells have been installed in two phases to intercept the groundwater contamination from the facility. A final groundwater extraction and monitoring design is currently under review by EPA. Simplot is conducting additional characterization in the phosphoric acid plant area. A Proposed Plan to Amend the ROD for the Simplot OU went out for public comment in March 2009, an Interim ROD Amendment was signed in January 2010.

The extraction system at the Simplot OU intercepted over 2.4 million pounds of phosphorus between 2007-2010, which otherwise would have been discharged into the Portneuf River. Prior to remedial work, groundwater associated with the EMF site contributed an average daily load of 2,920 pounds of phosphorus to the Portneuf River. This loading rate was reduced to 1,070 pounds of phosphorus per day in 2010, and is expected to decrease further in 2011 due to the rest of the extraction system coming on line and other source control measures. The end effect has been to decrease phosphate concentrations in the Portneuf River from a baseline concentration of 1.56 ppm to 0.56 ppm with a target of reducing phosphorus concentrations to no more than 0.075 ppm by 2022.

Remedial Actions - FMC OU
After closing in December 2001, EPA issued an Administrative Order on Consent (AOC) in 2003 to FMC for a Supplemental Remedial Investigation/Feasibility Study to investigate former operating portions of the FMC facility not covered under the 1998 ROD. FMC conducted the Supplemental Remedial Investigation field activities and data collection in 2007 and 2008, and EPA approved that work in 2009. FMC conducted the Supplemental Feasibility Study for the FMC OU in 2009 and 2010, which EPA approved in 2011. On September 26, 2011, EPA released a proposed plan for an interim amendment to the Record of Decision for public comment, involving proposed enhancements for groundwater, surface water, and soil at the FMC OU. The public comment period was originally scheduled to end on October 26, 2011, and was extended to December 2, 2011.

Remedial Actions - RCRA regulated units of the FMC facility
Also within the site boundaries are RCRA regulated units of the FMC facility. These actions are not part of the FMC OU since they are under RCRA subtitle C authority. The regulated unit of greatest interest to EPA and the community has been Pond 16S. Pond 16S is a closed and capped hazardous waste pond, which covers approximately 10.2 acres of phosphorus-containing waste from the elemental phosphorus manufacturing process. The Pond 16S cap consists of several engineered layers to prevent water from leaching to the waste. In June 2006, visible air emissions were observed coming from the temperature monitoring ports (TMPs) at Pond 16S. EPA conducted a site investigation in November and December 2006 to evaluate the source of these emissions, which determined that there was a high concentration of toxic phosphine gas that had built up under the Pond 16S cap. If not addressed, that phosphine gas presented a threat of release and exposure to site workers or others who might be in the vicinity of Pond 16S.

EPA proceeded to issue a Unilateral Administrative Order (UAO) under CERCLA in December 2006, requiring FMC to characterize gas generation under the cap, conduct ambient air monitoring, and design, construct and operate a gas extraction and treatment system capable of drawing down gas concentrations under the cap to safe levels. The scope of work was subsequently modified to also require FMC to implement an interim gas extraction and treatment system until a larger system can be designed and built. FMC performed gas characterization and ambient air sampling in May and June 2007, in accordance with the EPA-approved gas characterization and ambient air monitoring work plans.

Analytical and monitoring results confirmed that high concentrations of phosphine gas existed under the cap at Pond 16S. Hydrogen cyanide and hydrogen sulfide gasses were also detected. In February 2008, EPA approved FMC's Final Design Analysis Report for a gas extraction and treatment system capable of reducing gas concentrations under Pond 16S to safe levels, and construction of the Gas Extraction Treatment System was completed in April 2008. The Gas Extraction Treatment System worked as anticipated. Monitoring results show that gas concentrations under Pond 16S have remained at safe levels since November 2009.

Remedial Actions - Off-Plant OU
FMC and Simplot have conducted investigative work in the Off-Plant OU, and are working with EPA to determine what additional investigative and remedial work is necessary.

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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