The toxic contamination underlying many Superfund sites today is often decades old.
In Orange, the U.S. Radium Corporation processed a half ton (450 kilograms) of ore each day on its two-acre (0.8-hectare) facility between 1915 and 1926.
"Every ton of ore was mixed with 60 tons [54 metric tons] of water and 6 tons [5.4 metric tons] of hydrochloric acid, then left to stand for a month," said Gene Urbanik, an engineer with U.S. Army Corps of Engineers based in East Brunswick, New Jersey.
The corps was contracted by the EPA to clean up the site.
"In the end, only a few precious crystals of radium were produced," Urbanik said. "The yield was one gram [three-hundredths of an ounce] of radium for every 250 tons [227 metric tons] of ore."
That left mountains of by-product, which were dumped in municipal garbage pits throughout Orange and the nearby cities of Mont Clair and West Orange.
After a higher-yield ore was discovered in the Congo, U.S. Radium closed its New Jersey plant in 1926, leaving it abandoned.
"As the years went by, houses were eventually built on top of the open fields where the tailings were dumped, and the contaminated soil was used to fill in low-lying areas around the properties," Urbanik said.
Cleanup of the community's radioactive soil began in January 1997 and is expected to conclude later this year. Treatments varied according to levels of soil contamination.
In some cases the EPA installed radon mitigation systems in houses. "It's a pipe that goes through the basement foundation, collecting gas from below ground before it can enter the home," McKnight explained. "The gas is channeled through PVC pipes to a fan, usually in the attic. The gas is then discharged into the atmosphere, where it dissipates."
Cleanup officials say the level of radiation found in many homes affected by contamination fell into a category known as naturally occurring radioactive material, or NORM.
"That's about as low level as you can get with radioactive soil. [It] is similar to the level of radiation that you will find in nature," Urbanik said. "Nevertheless, this is a residential area, so it needed to be dealt with."
In other areas, contaminated soil was more radioactive and therefore more dangerous. The U.S. Army Corps of Engineers was charged with removing it.
Laborers wore protective clothing and respirators and worked in tightly controlled staging areas. They placed contaminated soil in specialized containers, which were shipped by truck then rail to a permanent waste-storage facility in the Utah desert, 80 miles (130 kilometers) west of Salt Lake City.
The site is operated by Envirocare. The private corporation is charged with safely storing the material, which will remain radioactive for approximately 14,000 years.
"We seal it up in highly regulated disposal cells," said Tim Barney, the company's senior vice president. "We have a lot of water-monitoring and air-monitoring stations around the site to make absolutely sure that no radiation escapes."
Two feet (0.6 meter) of natural, impermeable clay forms the bottom of the cell. The contaminated soil is then added in multiple one-foot (0.3-meter) layers. The top of the pile is covered with another seven feet (two meters) of clay, with thick layers of gravel covering that. The gravel protects the clay from erosion. The impermeable clay prevents radiation from leaking into the atmosphere.
"We believe this is the perfect place for this type of material," Barney said. "The clay is naturally available here. The local groundwater does not drain into any other water system; and we monitor it constantly to make sure it's pristine. Best of all, we are over 40 miles [64 kilometers] from the nearest community. There's nobody living out here."
For related coverage, watch Minutes to Meltdown Sunday, July 11, at 10 p.m. ET/PT on the National Geographic Channel (U.S. only).
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