EM Organizations Successfully Manage Stormwater Flow at Idaho Facility

An interim cap over the tank farm at the Idaho Nuclear Technology and Engineering Center serves to channel water away from the site to protect the underlying Snake River Plain Aquifer.

IDAHO FALLS, Idaho -Two EMorganizations in Idaho are effectively working together to manage water at a Cold War-era facility at the Idaho National Laboratory (INL) Siteto protect the underlying aquifer used by 300,000 Idaho residents for agriculture, drinking water and municipal usage.

EM contractor Idaho Environmental Coalition's (IEC's) Environmental Restoration (ER) and Infrastructure organizations teamed up to investigate water leaks and manage rain and snowmelt at the Idaho Nuclear Technology and Engineering Center (INTEC), which reprocessed spent nuclear fuel from the early 1950s until 1992. Because the facility stores radioactive and hazardous waste and some of that waste has contaminated underlying soil through historic releases, the effort is imperative to prevent water from moving through the contaminated soil toward the underlying Snake River Plain Aquifer.

At INTEC, water diversion is focused in and around the Tank Farm. The Tank Farm is a collection of underground storage tanks that accepted and transferred high-level liquid radioactive waste generated from reprocessing activities. Historic leaks in piping and valve boxes contaminated the soil beneath the Tank Farm. Since then, all but four tanks have been emptied, cleaned and grouted. A 10-acre asphalt pad and water diversion system were later installed.

ER and Infrastructure maintain the asphalt pad and the stormwater drainage system that diverts all runoff to the INTEC Evaporation Pond, a lined pond east of the facility. Workers conduct quarterly inspections, drainage cleanouts and preventative maintenance on the lift station pump and the pond's leak detection system. In 2021, ER purchased asphalt maintenance equipment to conduct periodic repairs on the pad.

Water diversion below the surface pertains to the contaminated water body - a saturated zone of soil and rock between the ground surface and the top of the aquifer. ER and INTEC workers monitor the facility's water utility systems to identify when a pipeline leak occurs, isolate the leak and repair the system as soon as possible. A network of situated water monitoring wells also are used to identify the location of pipeline leaks and to monitor the contaminants of concern on an annual basis. Most recently, flow-metering upgrades have been completed on the firewater, raw water and the potable water systems to improve monitoring.

"In the last dozen years, crews have identified more than 80 water discharges from the facility and made repairs to stop those discharges," said IEC environmental scientist Sarah Thompson.

The INL receives an average of about nine inches of rain and snow annually, and where that water flows at INTEC is crucially important.

"We're having very good success and are constantly making improvements," said Thompson. "The aquifer directly benefits from our work."