The Fort Hall Mine Landfill: Groundwater Pollution

Mar 24, 2021

This week on Sustainable Idaho, Scott and Rachel investigate a new topic, the Fort Hall Mine Landfill. Hazardous chemicals were dumped into the landfill sometime during the 1940s. These chemical pollutants have slowly leached into the Portneuf aquifer and have degraded drinking water quality. Speaking to David Goings, a senior hydrogeologist for the Department Environmental Quality, Sustainable Idaho investigates.


Credit Bannock County, the Landfill Site

This week on Sustainable Idaho, we are investigating a new topic, the Fort Hall Mine Landfill.  The Fort Hall Mine Landfill is located south of Pocatello, near the Gap, and has operated since 1943.  Despite its name, the landfill is actually not on the Fort Hall reservation. So, you might be wondering why we’re interested in the Fort Hall Mine Landfill, it might sound like a bit of trashy topic, if you pardon the awful pun. But, the Landfill is an extremely important topic. Hazardous chemicals were dumped in landfill sometime in the 1940s and the chemical pollutants have slowly seeped into the ground and into the groundwater storage in the Portneuf aquifer.

So this week on Sustainable Idaho, we speak to David Goings, a senior hydrogeologist for the Department of Environmental Quality, who has been tackling the issue of groundwater contamination from the Fort Hall Mine Landfill.

David started by explaining that the issue of groundwater contamination from the landfill site has been known for decades. Historically, the site was used to dump large quantities of toxic solvents, specifically trichloroethylene (TCE), tetrachloroethylene (PCE), and vinyl chloride. All the toxic solvents are emanating from the same zone of the landfill, which is called Cell 1.  

David continued to explain that this issue is concerning because the toxic pollutants are entering the Portneuf aquifer, which is used by Pocatello and Chubbuck as a drinking water source.

Scott: Right, and an aquifer is a body of underground permeable rock, which can transmit groundwater.  In this situation, it’s possible to think of the Portneuf aquifer as an underground river, where Pocatello and Chubbuck are downstream of the point source pollution.

It’s important to note here, that when these chemical pollutants were dumped sometime in the 1940s, there were very few environmental regulations. Since then, ownership of the landfill site has changed hands a couple times, with Bannock County operating the site since 1979.

We continued by asking David to provide a brief history how the landfill containments have been managed. David explained that the groundwater contamination was found in 1991. Subsequently, Bannock County, working in conjunction with the Department of Environmental Quality, implemented a remediation strategy to try to stop the contamination. The remediation strategy was developed after a hydrogeological investigation of the landfill site, which attempted to understand, contextualize, and model how the toxic contaminants were moving out of the site. Specifically, the remediation strategy relied on an air stripper, which sucked water out of the ground and removed the contaminants, before replacing it into the ground.

However, David explained that in 2004, the DEQ determined that the air stripper remediation strategy was ineffective and additional actions were required to prevent the leaching of the pollutants. This raised a number of key questions, why was the air stripper not working, and how could the County and the Department of Environmental Quality work to find an effective alternative solution?

David described how the initial attempts to characterize, contextualize, and model how the toxic contaminants were moving out of the site, were incorrect. As a result, the remediation strategy was never likely to have been effective. David continued to explain that the County and the DEQ are now working to re-study the landfill site and develop revised groundwater remedy.

Thank you to David Goings for joining us this week. Join us for Sustainable Idaho next week were delve deeper into the issue of groundwater contamination.  Also, the sustainability club is hosting an explorative Education Day, this Friday, March 26th, from 3-5 P.M. Meet at the sportsman access point off of E. Old Oregon Trail Road, 6 miles east of McCammon. For more details, visit the ISU sustainability club website. Join us for Sustainable Idaho every Tuesday morning at 7:35