In a June 14 unilateral administrative order, the U.S. Environmental Protection Agency (EPA) ordered the FMC Corporation to halt phosphine gas releases from additional waste ponds at the Eastern Michaud Flats Superfund site, where FMC operated an elemental phosphorus plant from 1947 to 2001. The Superfund site, designated in 1990, also includes the J.R. Simplot Co.’s Don phosphate fertilizer plant.
The FMC ponds, used to manage wastewater containing elemental phosphorus, were capped and closed under a 1999 Resource Conservation and Recovery Act (RCRA) consent decree. In 1998, FMC paid $11.9 million – the largest civil penalty settlement ever at that time – under a 1976 hazardous waste law. It also had to cap the ponds, which had caught fire periodically over the decades.
Construction of the pond caps was completed by 2005. In its latest Comprehensive Environmental Response, Compensation, and Liability Act (CERCLA) order, EPA said FMC must do a better job of protecting onsite personnel and the environment from potential exposure to the phosphine gas, which can be toxic and explosive. It can also damage respiratory, nervous, and gastrointestinal systems, as well as the heart, liver, and kidneys.
In December 2006, EPA issued a similar order requiring FMC to extract and treat gas from under the Pond 16S cap that had accumulated to high concentrations. Phosphine, hydrogen sulfide, and hydrogen cyanide gases were detected in and around a number of the ponds that year. The Pond 16S concentrations were successfully lowered with a gas extraction and treatment system.
The June 14 order requires FMC to design and operate gas extraction and treatment plants at three other ponds, plus extract and treat phosphine gas at other RCRA capped ponds where EPA determines it is needed to protect human health and the environment, conducting additional monitoring. A one-year period to demonstrate that Pond 16S gases can be maintained at safe levels began in November 2009.
In April 2010, FMC notified EPA that it was extracting gas at Pond 15S to address high phosphine concentrations under that cap, which were being released into ambient air. After EPA requested more information, FMC provided data showing concentrations there at or exceeding 20 parts per million. Phosphine gas concentrations have been measured at or exceeding 1 ppm in air outside of Ponds 8E and 17.
Idaho Department of Health and Welfare (IDHW) toxicologists, plus Centers for Disease Control and Prevention officials in Atlanta, analyzed data from the site after EPA requested help. The state concluded this month that phosphine gas from FMC’s Pond 15S between February and May posed a threat to the 12 workers cleaning up the site, as well as to anyone else who happened onto the property.
“The phosphine gas being released from Pond 15S is an urgent public health hazard to the health of people breathing the air in the proximity of Pond 15S, including workers, visitors to the pond area and any potential trespassers in the pond area,” a Health and Welfare public health toxicologist wrote in a June 1 letter to EPA.
The IDHW declared phosphine gas levels at Pond 15S an “urgent public health threat,” which FMC disputes, saying department officials lacked complete, up-to-date information and never visited the site. The company disagreed with some of EPA’s findings and conclusions in the order, but vowed to comply with it.
“FMC designed the ponds to allow for the capture and treatment of phosphine, which the ponds were known to generate as the phosphorus degrades and which was anticipated and addressed in the pond closure and post-closure plans,” Paul Yochum, former plant manager and now an FMC consultant, stated in a news release.
Yochum said the measures that FMC implemented and EPA approved for RCRA closure of the ponds continue to be the most protective, technically proven, and environmentally responsible means to manage phosphorus waste sediments.
Jim Werntz, EPA’s Idaho office director in Boise, said FMC needs to stop the gas emissions and ensure safety at the pond site. He called Monday’s EPA order an emergency response. “Work is already under way at FMC to capture and treat dangerous pond gases at two ponds,” Werntz said, adding the order requires FMC to design and deploy a more robust monitoring program.
EPA also will involve the Shoshone-Bannock Tribes and seek tribal input in reviewing and approving the projects and design documents required under the order. Much of the FMC site is on the Fort Hall Indian Reservation and not far from Interstate 86 and the Pocatello Regional Airport.