DOE Injecting Molasses Into Ground Sites to Encourage Bacteria to Break Down Contaminants

Employees adjust a bioremediation systems injection well at the Pantex Plant. Credit: NNSA

The Pantex Plant near Amarillo has been working diligently to clean up its part of the High Plains region and has identified a surprising ingredient to help with the task—molasses.

For decades, the Department of Energy/National Nuclear Security Administration (DOE/NNSA) site has worked to remediate historic pollution. Since the plant’s operation as a munitions facility during World War II, when noxious solvents were part of the manufacturing process, the site released toxic materials into the soil, including at the Burning Ground, an area at Pantex previously used for the disposal of high explosive waste and hazardous materials.

State-of-the-art Cleanup Method Meets Basic Bacteriology

To ensure legacy pollutants do not reach the Ogallala Aquifer, the main water source for the Panhandle, Pantex recently installed 25 in situ bioremediation (ISB) injection wells along the southeast boundary of the plant property. The wells are designed to prevent movement of contaminates by establishing treatment zones capable of reducing contaminants to safe drinking water levels. Injecting molasses into these zones can stimulate bacterial growth. As the bacteria feed and multiply, they naturally slurp up oxygen and break down contaminants.

The Pantex Plant has installed 25 new bioremediation systems injection wells along the southeast boundary of the site to prevent further movement of contaminants. Credit: DOE/NNSA

The ISB systems are complemented by pump-and-treat systems that also help clear pollution by extracting water and treating the contamination above ground. Other cleanup actions include drilling wells for the perched groundwater—water below the surface but still hundreds of feet above the aquifer. At the Burning Ground, a vapor extraction system operates to remove remaining solvents in the soil.

After commissioning a study with industry experts in 2019 and installing monitoring wells to track contaminant movement, Pantex determined that roughly 90 wells, using both methods of bioremediation, would be needed to restore perched groundwater to drinking water standards.

The study, however, indicated that some contamination has reached beyond the plant site. To address the clean-up, Pantex is installing wells on the neighbor’s property. In March 2020, Pantex began the initial phase of this infrastructure project on neighboring property by installing 16 wells at its leading edge to stop any potential spread of pollutants. Four of these wells will be used for extraction to obtain water to mix with molasses for injection into the other 12 wells.

Molasses Injection

This fall, molasses will be injected to establish a bio-reactive zone in the perched groundwater that will begin the remediation process. To combat challenging groundwater zones, Pantex engineers will drill pump and treat extraction wells to the east of the plant. These wells are expected to be operational by the end of year and will help capture the water and contaminates that continue to move to the south and east.

Pantex is committed to finding the extent of contamination, protecting neighboring wells, preventing further offsite movement of the contaminated groundwater, and mitigating the offsite contamination. As part of its commitment, Pantex monitors more than 100 perched groundwater wells to evaluate the effectiveness of the clean-up efforts and 28 Ogallala Aquifer wells to evaluate the continued protection of the drinking water aquifer.

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