By Clay Wallace

Beneath a grassy hill, just 10 miles northwest of Morehead, lies more than 4.5 million cubic feet of radioactive waste – enough to fill 64 Olympic swimming pools.

The original 280-acre site is nearly indistinguishable from any of the other fields atop the flat ridges of the Knobs physiographic region. The signs around its fenced perimeter, however, indicate its past as the nation’s first commercial disposal facility for low-level radioactive waste, which began operation in 1963.

Despite the original lucrative hopes for Maxey Flats as a catalyst for other types of industrial or nuclear industry, such as power plants or research facilities, the site is now a containment area, with its amassed radioactive waste buried safely under layers and layers of protective shielding, efforts that required decades and millions of dollars. It is tended by a small team of environmental scientists, who monitor it daily – and will far into its future.

“When I tell people that I work at the Maxey Flats Disposal Site, the first reaction is always a gasp and a strange look,” said Tom Stewart, an EEC environmental scientist advisor. 

Background

Looking past the green grassy mound – 60 acres fenced off with a vegetative cap – the site includes an additional 662 acres of buffer zone. Office buildings, a lab, garages, and equipment sheds dot the perimeter.

From 1963 to 1977, the state – under authorities granted by the federal government – licensed private operators to dispose of radioactive waste from the military, hospitals, universities, and corporations in 52 trenches spread across 30 acres.

“The Commonwealth of Kentucky thought that this could be a money-making venture,” Stewart said. “There was no nuclear repository for waste at the time, and there were stockpiles, so people needed somewhere to put all of this waste. And the Commonwealth says, ‘Well, hey, let’s do that and we can make money off of it.’”

“Before there was regulation from the EPA, before there were OSHA regulations, before we had current landfill standards, we didn’t do things the same way that we do them now,” said Scott Wilburn, EEC environmental control supervisor. 

“So, all of the disposal that was carried out in the beginning of the site’s history was shallow land burial. There was no bottom liner and there was no leachate collection system. There was no kind of barrier from those materials that were dumped to direct communication with the environment. So, it did. It did directly communicate with the environment, and it migrated outside of the waste cell.”

Challenges

During its operation, the site received approximately 533 pounds of material that contained uranium, thorium, and special nuclear waste containing plutonium and enriched uranium.

Solid radioactive waste handled in this way can be sequestered without significantly affecting the surrounding environment. However, the waste disposed of at Maxey Flats was not properly contained, and in 1972, monitoring conducted by the Kentucky Department of Health indicated migration of the radioactive material tritium.

“Prior to the cap, we had an issue with water getting into the trenches, raising the water level within those trenches, and of course that mixes with the waste and eventually the water flows out and spreads to groundwater,” Wilburn said.

As concerns mounted, a citizens’ watchdog group formed by local leaders and community members began in 1977 to call for its closure. The Commonwealth directed the Nuclear Engineering Company to discontinue the acceptance and burial of radioactive waste.

Two years later, the company’s license to receive low-level waste was revoked and the site’s care was handed over to the Commonwealth.

At the close of the 1970s, there was widespread national attention on the need to address contaminated sites. In response, Congress enacted the Comprehensive Environmental Response, Compensation, and Liability Act, which created the Superfund program.

Not only did the program seek to identify, investigate and clean up hazardous waste sites across the country, it sought to have the restoration funded directly by the responsible parties.

“So if you create a waste or you have a waste disposed of, you’re responsible for it after it’s disposed of,” Wilburn said.

Superfund Admission

In 1983, the Commonwealth initiated the process for the site to be included on the national priorities list, and three years later it was admitted into the Superfund program. In 1991, the EPA signed onto its cleanup plan.

The plan left all the waste in place, but contained it.

“That natural stabilization process just leaves everything where it’s at because it’s more dangerous to move it than it is to leave it where it’s at,” Stewart said. “And you cover it up as well as you can to keep the rain from getting to it and pushing it where it’s not supposed to be even more.”

The cleanup was to be done in three stages, an initial remedial phase (IRP), an interim maintenance period (IMP), and a final closure period. During the IRP, more than 80 sump pumps were sunk into the waste trenches to remove contaminated water.

One method to dispose of the leachate was to create concrete from a mixture of the contaminated water with cement, to be built into an underground bunker. Another method of disposal used an evaporator, which released clean water vapor into the air while the remaining contaminated solids were separated and stored in tanks at the site.

“During the IRP, we removed a million gallons of water from it, and prior to that, when the evaporator was running,” Wilburn said, “I think it was 13 million gallons of water that was removed from the trenches.”

At the end of the IRP, the site was covered with soil and capped with a 60-acre synthetic liner.

The interim maintenance period followed, and trained staff with the Energy and Environment Cabinet took frequent samples of water running off the site. The samples showed the levels of tritium decreased, indicating that the cap was successfully keeping rainwater from reaching the waste in the trenches.

However, this initial cap was brittle, requiring workers at the site to frequently weld new panels over breaks in the liner. When it got cold, Stewart said, it would almost shatter like glass. The original cap was then replaced with a new polypropylene liner.

“It was much, much, much more resilient to the changing climate,” Stewart said, “and the sorts of things that you see from ultraviolet exposure, from the sun beating down on it every day, all day long.”

Final Installations

In late 2012, the EPA determined the site was now ready for all remaining waste to be buried and the final earthen cap and permanent surface water control features to be installed.

“In its current state, the cap appears just to be a grass mound,” Wilburn said. “In reality, it’s much more than that.”

The cap is a composite structure made of layers of specially engineered materials. The existing polypropylene liner was used as the base layer. Above that, a geogrid, a structural material used to reinforce and stabilize soil, was laid over the trench areas.

Over the grid is a layer of fill dirt covering the whole 55 acres, all gathered from borrow areas within the buffer zone of Maxey Flats. The dirt forms a mound contoured to direct runoff to the appropriate water control features.

Covering that is another layer of the geogrid, this time spread over the entire cap to provide additional stability. Above that is a geosynthetic clay liner, which is a manmade composite designed to expand and seal when exposed to moisture.

It simulates a foot of clay and its protective properties, Stewart said, but it’s actually only a few millimeters thick.

Atop is another layer of plastic, a polyethylene geomembrane on which rests the geocomposite drain. It’s a tight weave knit that allows the rainfall that comes through and percolates through the soils to runoff and go where it’s intended.

At the very top is what’s visible at the site now: a layer of soil and grass. By keeping the burial trenches dry and contained, the waste can stabilize safely separated from contact with humans, animals and the surrounding watershed’s forests and farms.

“It’s actually like a sandwich,” Stewart said. “There are lots of layers and there are lots of different purposes for those different layers.”

Scientists with the Commonwealth’s Energy and Environment Cabinet, like Wilburn and Stewart, will continue their sampling and maintenance of the site for the next hundred years.

“The radioactive levels here are that of what natural background are,” Wilburn said. “And as long as we continue to maintain the site to the standards that we do and we continue to monitor it- because you never know when something new might develop – we have the public protected.”