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EPA Proposes to Modify Simplot Superfund Site Cleanup Plan

Release Date: 03/17/2009
Contact Information: Kira Lynch/EPA – Seattle, 206-553-2144 Susan Skinner/EPA – Pocatello, 208-262-4326 Mark MacIntyre/EPA – Seattle, 206-553-7302(desk) 206-369-7999(cell)

EPA officials: “This proposal seeks to add phosphorous as factor, requires additional pollution control measures, at Simplot’s ‘Don Plant’.”
(Seattle, Washington – March 17, 2009) The U.S. Environmental Protection Agency is proposing changes to the Record of Decision (ROD) for the Simplot Plant Operable Unit (Simplot OU) of the Eastern Michaud Flats Superfund site. The ROD is the legal document that guides the cleanup of property or facilities that have been added to the National Priorities List or federal “Superfund” site list.

To help keep the river healthy, Simplot needs to make some serious changes at their plant.

Some major components of EPA’s preferred alternative for the Simplot Plant OU proposed plan are:

  • Identifying phosphorus in groundwater as a “contaminant of concern”;
  • Characterizing all contamination sources at or near the phosphoric acid plant;
  • Control of all phosphorus contamination sources to the extent practicable;
  • Installation of a high-density polyethylene (HDPE) liner on top of the phosgypsum pile, which is known as the “gypstack,” to minimize process water infiltration through the gypstack and into groundwater;
  • Continued development, operation, and maintenance of the groundwater extraction system to address those areas where arsenic and phosphorus concentrations remain above cleanup standards or levels of concern.

Public Meetings Are scheduled for: Tuesday, March 17 6:00- 9:00 PM in the Pocatello City Hall Chambers, Pocatello; and Wednesday, March 18, 6:00 – 9:00 PM in Fort Hall Business Council Chambers, Fort Hall. Written and oral comments will be accepted at the meetings.

Beginning March 16th, you may send comments regarding the proposed
ROD Amendment to:
Ms. Kira Lynch
US EPA Region 10, ECL-113
1200 Sixth Ave, Suite 900
Seattle, WA 98101
or email comments* to :

*Please put “Simplot ROD Amendment” in subject line

For more about the site, visit EPA’s Eastern Michaud Flats Superfund Site website:

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