The J.R. Simplot Co. and the U.S. Environmental Protection Agency (EPA) on Wednesday, Sept. 1, filed a consent decree amendment in U.S. District Court for the District of Idaho, in Boise, legally committing Simplot to a multimillion dollar investment in reducing phosphorus releases into the Portneuf River from its gypsum stack and phosphoric acid production plant near Pocatello, Idaho.
Simplot’s Don phosphate fertilizer complex is the river’s largest source of phosphorus, a nutrient that can cause rampant weed and algae growth during warmer months, robbing the water of life-supporting oxygen needed by fish, insects, and other aquatic life. EPA researchers said 80 percent – or about 1,200 pounds – of the phosphorus entering the river daily downstream of Batiste Road originates near Simplot’s Don Plant.
While the Simplot plant is not located on the Fort Hall Reservation, the Portneuf River flows through the property’s northeast section and north into “The Bottoms,” where most Shoshone-Bannock traditional and ceremonial activities occur, including fishing and the gathering of native plants.
The latest amendment expands a 2002 agreement between Simplot and EPA regarding cleanup actions at the complex, and provides the legal framework for Simplot to implement EPA’s 1998 Record of Decision (ROD) and 2010 Interim ROD Amendment (IRODA) for Simplot’s operable unit of the Eastern Michaud Flats Superfund Site.
The 1998 ROD added phosphoric acid as a contaminant of concern. Metals, arsenic, radionuclides, and other contaminants were previously listed.
The Simplot plant is on the Superfund site encompassing 2,475 acres. The adjacent FMC elemental phosphorus plant that closed in December 2001 and was later demolished was also located there. Both plants were constructed in the 1940s. The FMC property was 1,450 acres, while Simplot’s acreage totals 1,025.
Lori Cohen, deputy director of EPA’s Superfund cleanup office in Seattle, said the work Simplot has agreed to perform under the amendment will significantly reduce phosphorus discharges into the Portneuf River and better protect groundwater.
Many of the actions agreed to in the consent agreement are already being done by Simplot. Details of the consent decree were ironed out earlier this year when Simplot agreed to take additional measures to clean up the site and slow the flow of phosphorus into the river, which has struggled with pollution for decades.
EPA officials said Simplot’s efforts to reduce phosphorus discharges into the Portneuf River are getting results. Researchers said their latest data shows phosphorus concentrations in the river have declined by 50 percent, compared to peak levels recorded in 2006.
While the decline is encouraging, EPA officials caution the new data is an initial glimpse, and far from the long-term data needed to accurately assess efforts to clean up the river. “The reductions are much faster than what we expected to see,” said Kira Lynch, EPA remedial project manager for the site. “We’re hopeful that we’re going to keep seeing dramatic reductions.”
Last summer, Simplot constructed a large decant pond to capture and store process water to block it from penetrating the gypsum stack. Simplot officials estimate the company has spent more than $6 million in the past four years on the project.
Under the amendment, Simplot must:
- Identify phosphorus in groundwater as a “contaminant of concern”;
- Characterize all contamination sources at or near the phosphoric acid plant;
- Control all phosphorus contamination sources to the extent practical;
- Install a high-density polyethylene (HDPE) liner atop the gypsum stack to minimize process water infiltration through the gyp stack and into ground water; and
- Continue to develop, operate, and maintain a ground water extraction system to address those areas where arsenic and phosphorus concentrations remain above cleanup standards or levels of concern.
Earlier this year, Simplot began installing the synthetic liner over the top of the massive pile of gypsum blamed as the main source for phosphorus leaking into the groundwater and then the river. The liner will be fitted over the top of the 200-acre waste pile the next four years.
The company’s amended clean-up plan also includes drilling monitoring and extraction wells to reduce the flow of contaminated groundwater, and replacing equipment identified as a risk.