The Fort Hall Mine Landfill: Groundwater Pollution, Part 2

Mar 31, 2021

This week on Sustainable Idaho, Rachel and Scott continue their investigation of the Fort Hall Mine Landfill. Speaking to Dr. Tamzen MacBeth, an expert in the development and implementation of innovative solutions for contaminated soil, sediment and groundwater, Sustainable Idaho explores attempts to mitigate and reduce the amount of pollution entering the Portneuf aquifer.


Credit Dr. Tamzen MacBeth, CDM Smith

Last week we spoke to David Goings, a senior hydrogeologist from the Idaho Department Environmental Quality. David explained that sometime during the 1940s, toxic chemicals were dumped into the landfill site, and that these pollutants have slowly leached into the Portneuf aquifer. We learned that this is potentially a very important issue because the Portneuf aquifer is the drinking water source for Pocatello and Chubbuck.

David also explained how previous attempts to characterize the hydrogeological conditions at the landfill site have not been successful, and as a result attempts to mitigate and reduce the amount of pollution entering the aquifer, have not been effective.

To find out how the Idaho Department of Environmental Quality is working with the County and other contracted organizations to solve this issue, we spoke to Dr. Tamzen MacBeth. Dr. MacBeth is an internationally recognized expert in the development and implementation of innovative solutions for contaminated soil, sediment and groundwater. Tamzen works for CDM Smith, a privately owned engineering and construction firm, which has been hired by Bannock County to help tackle this problem.

Tamzen started by explaining that since 1979, Bannock County has operated the landfill and that in 1991 contamination was found in the municipal water supply near Pocatello. The contamination was traced back to the landfill. The two identified toxic solvents are TCE and PCE, which are leaching into the ground, dissolving in the groundwater and then flowing towards Pocatello – ultimately impacting the drinking water supply.

Last week, we heard from David Goings that the first remediation strategy (attempting to reduce TCE and PCE contamination) centered on an air stripper device. Essentially, this device draws contaminated water out of the ground, before removing the contaminants, and replacing the water back into the ground.

However, Dr. MacBeth continued to explain that the past remediation technique was ineffective in preventing the toxins entering the Portneuf Aquifer. The device was likely ineffective because of an incomplete understanding of the hydrogeological conditions present at the site.

To find out more about the toxins and how they may harm human health, we spoke to Dr. Sarah Godsey, an expert in hydrogeology, who works at Idaho State University. Dr. Godsey explained that TCE and PCE stand for trichloroethylene and tetrachloroethylene, respectively. Both chemicals are carcinogenic are can be harmful to the liver and other vital organs.

Currently, Dr. MacBeth and her team are working to re-characterize the hydrogeological conditions present at the Fort Hall Mine Landfill site. We continued by asking Dr. Godsey what is involved in a new site characterization study, and how can this information be used to improve the effectiveness of a remediation technique.

Dr. Godsey explained that a site characterization study attempts to understand the sub surface material properties, including the material properties, the location of the contaminant, and how water moves through the ground and out of the site. This information can then be used to identify where future remediation devices should be located, in order to maximize their ability to remove contaminants and prevent leaching.

Whilst the site re-characterization study is ongoing, it’s important to understand whose water supply is affected, and what efforts are being made to keep these people safe. Dr. MacBeth explained that the Pocatello municipal water supply is regularly monitored and meets Environmental Protection Agency Standards for drinking water.  However, a small number of private potable wells, close to the landfill site, are affected. Dr. MacBeth suggested that nine private potable wells are impacted, but those households have been offered the opportunity to join the safe Pocatello water supply.

Thanks to Dr. Tamzen MacBeth and Dr. Sarah Godsey this week. Also, the ISU sustainability club invites you to its next zoom meeting, this Friday, April 2nd, from 4-5 P.M. The meeting will explore a host of exciting topics, including Earth Day, the forthcoming cooperative discussion panel with Political Science club, and the club’s next Community Restoration Day. Join us for Sustainable Idaho, every Tuesday morning at 7.35am.