Groundwater

A DeWind construction worker uses the trencher Nov. 21 to dig a 30-foot-deep trench at Wright-Patterson Air Force Base, Ohio. The trencher digs, lays the pipe and fills the trench in one efficient and environmentally friendly pass. (U.S. Air Force photo by Hannah Carranza)

WRIGHT-PATTERSON AIR FORCE BASE, Ohio—One line of effort is being set in stone, clay and gravel at Wright-Patterson Air Force Base (WPAFB), where an army of construction workers and machines are digging a 420-foot-long trench toward a way to environmental progress.

The project targets the hazardous materials storage facility on Area B, which accidently released a firefighting agent called aqueous film-forming foam (AFFF) containing per- and polyfluoroalkyl substances (PFAS) on two occasions in 2008 and 2011. Officials said the fire-suppression system at this facility used an earlier version of AFFF before EPA identified PFAS for possible health risks. The released AFFF soaked into the soil and entered the ground and surface water near the site.

The constructed trench will intercept impacted groundwater, and a downgradient-collection basin will catch affected surface water so it can be treated before it's discharged near the Dayton drinking water wellfield.

The 2-foot-wide trench extends about 30 feet below ground surface, reaching all the way down to bedrock, according to Ed Coggin, technical director of the water engineering group at Weston Solutions LLC, the contractor awarded the project in 2021 as part of the U.S. Army Corps of Engineers’ Rapid Response Program.

Environmental Protection Agency officials survey the work site Nov. 22 at Wright-Patterson Air Force Base, Ohio. A 450-foot trench construction project in Area B is underway to help remove substances previously used in firefighting from groundwater. (U.S. Air Force photo by Hannah Carranza)

As groundwater seeps out the trench's sides, gravity will pull it down through the gravel fill material and into a slotted pipe, preventing groundwater from migrating further from the site. Next, the collection pipe will convey the water to a sump at the trench's low point. Finally, a pump installed in the sump will send 15-25 gallons of water per minute to the downgradient-treatment system, which will use a special type of organically-engineered clay to filter out PFAS.

"The intercepted groundwater will be combined with captured surface water from the drainages south and west of the storage facility," said Greg Plamondon, the WPAFB Remedial Project Manager for the site. "All accumulated water will then be treated by a series of passive pretreatment and primary treatment beds before being discharged to the base stormwater network. This system will effectively reduce the concentrations of PFAS leaving the base."

A worker uses an excavator Nov. 21 to prep a gravel pile at Wright-Patterson Air Force Base, Ohio. The 450-foot trench being dug is part of an Area B construction project designed to help remove substances previously used in firefighting from groundwater. (U.S. Air Force photo by Hannah Carranza)

The Ohio EPA holds a direct stake and role in WPAFB's water remediation, overseeing the project to ensure it meets state and federal regulations.

"We are very supportive of taking early actions like this that Wright-Patterson Air Force Base is doing," said Bonnie Buthker, chief of the Ohio EPA's Southwest District office."By installing this trench and collecting the contaminated groundwater and the rainwater from this particular site, they’re preventing that contamination from impacting Dayton's production wells and also base production wells."

Slated to finish the site-remediation treatment system by the end of next summer, the project team is employing a host of equipment to do the heavy lifting, starring the large DeWind "one-pass" trencher.

A worker drives an excavator Nov. 21 toward a pile of gravel at Wright-Patterson Air Force Base, Ohio. The 450-foot trench being dug is part of an Area B construction project designed to help remove substances previously used in firefighting from groundwater. (U.S. Air Force photo by Hannah Carranza)

"We like yellow iron," Coggin said. "The main piece of equipment is the trencher itself; it really drives the whole thing."

The Area B project is the first of two to use the USACE Rapid Response Program for PFAS remediation, which features fast preparation, initiation and funding for time-sensitive environmental needs. Solutions at the current and former fire-training locations on Area A are in the works as well.

"I’m just really excited that we’re getting to do something," Crocker said. "It's nice to be breaking ground."