Years-long cleanup of 9,000-acre Johnson County ammo plant site nears finish line

The U.S. Army and Army Corps of Engineers is just hundreds of acres away — out of nearly 9,000 acres total — from the long-awaited finish line for its clean up efforts at the Sunflower Army Ammunition Plant in western Johnson County.

The massive site near De Soto was once home to a factory that produced gunpowder for artillery shells in World War II and rocket propellants during the Vietnam War. The site also had storage facilities, powerhouses, landfills, burning grounds and waste treatment facilities. It shut down in the early 1990s but left behind a sludge of contaminants like lead, arsenic and nitroglycerin that called for major cleanup efforts.

While visions for parks and private development have come forward over the years — including when private developer Sunflower Redevelopment LLC purchased the site in 2005 — federal funding shortages and ongoing remediation efforts have pushed those dreams down the road.

But bit by bit, parts of the site have been deemed safe by the Kansas Department of Health and Environment. Almost 400 acres will be allocated to become part of what will be Johnson County’s biggest park.

Kansas Department of Health and Environment Deputy Communications Director Preston Webb said in an email that approximately 7,780 acres have been remediated, but some still need final approvals from KDHE before they’re considered complete.

Remediation work is underway on approximately 540 acres of soil and 750 acres still await remediation efforts.

In a board meeting on Thursday, the Army and U.S. Army Corps of Engineers shared that nine sites still need environmental remediation and a handful of sites — including two landfills — will need long-term monitoring.

Test, excavate, restore

The Army identified more than 80 sites that required environmental cleanup, said Scott Smith, the site manager with the U.S. Army.

“All these different areas, there was some reason that we examined and investigated them,” he said, to determine the extent of hazardous waste in each spot.

As part of their investigations, the Army Corps of Engineers gathers soil samples and checks for hazardous materials. If they find any, they will excavate the contaminated soil until tests come back clean.

“Now this takes years,” Smith said. “We dig that whole thing up a foot deep, generally, and then we retest the soil to see if you got it all. We do the same thing again until we get to clean. Once we get to clean, then we’re done.”

Once excavated, the army tests for “leachability,” or if the contaminants can spread into other parts of the ground. If the contaminants can spread, the soil goes to a site in Emelle, Alabama, as hazardous waste. If not, it goes into the Johnson County Landfill.

In this round of updates, Kathy Baker, the project manager from the U.S. Army Corps of Engineers, said about 80% of the excavated soil went to the Johnson County Landfill. The rest went to Alabama.

Once the soil samples come back clean, the Army Corps of Engineers can begin environmental restoration work and write to the Kansas Department of Health and Environment, saying that no further action is needed and they will close their permits.

Drinking water concerns

Alongside soil, the Army Corps of Engineers tests and monitors the groundwater below the former plant.

In past meetings, Baker said that several residents expressed concerns if people were using water that came off the Sunflower Plant. As an update, Baker said in April that the city gets most of its drinking water about 3 miles away from the Sunflower boundary near the flood plain.

“As I stated before, our investigations (of the wells) show that nothing is leaving the Sunflower boundary,” Baker said.

The Army Corps of Engineers did identify “a few domestic water wells” close to the boundaries, but “we do not know if they’re in use.”

“A lot of them are a lot deeper than the wells at Sunflower where we’re finding any contamination or any kind of contamination concern” she said, adding that the contaminated wells are about 25 feet deep. The domestic wells go further than 30 feet in the ground.

However, there are more protections in place, Baker said. As of Oct. 30, KDHE issued new regulations that will not allow a person to drill a well for potable water on the Sunflower site unless deemed OK by the state agency.

According to De Soto’s website, the agencies hope to finish the cleanup by 2028, but groundwater monitoring efforts may continue for the next 20 to 30 years.