During a 12-year period beginning in 1964, soldiers at Fort Jackson fired rockets and tossed hand grenades on the base's southern boundary, just across Leesburg Road from a community that today is living with a chemical threat the explosives left behind.
Those explosives, used to train soldiers, contained a poisonous compound that has polluted 31 wells and remains a potential threat to the drinking water of more than 100 others, officials at Fort Jackson say.
The fort released information Tuesday night that traces the source of groundwater contamination to an explosives range known as Kasserine Pass, just east of the fort's landmark Weston Lake and north of homes across Leesburg Road.
Soldiers learning the basics of warfare at Kasserine Pass shot hundreds of 3.5-inch rockets, each containing about a pound each of RDX, a toxic chemical linked to cancer and seizures in people exposed to high amounts, according to information Fort Jackson released during a meeting Tuesday night.
Thousands more 40 millimeter hand grenades, each containing 1 to 2 grams of RDX, also were exploded in this area, officials said during an open house for neighbors of Fort Jackson. Explosives with RDX were used at Kasserine Pass from 1964-76, according to charts the fort displayed at Tuesday's meeting with neighbors.
Fort officials said that while as many as seven other parts of the base have been tainted by RDX from explosives, groundwater from the Kasserine Pass area is flowing directly toward homes across Leesburg Road. RDX is believed to have seeped into the soil and soaked into groundwater over time.
Explosives containing RDX are no longer used at Kasserine, and areas where the material is used today are farther away from Leesburg Road, they said.
"We collected a lot of samples; we did a lot of investigation work," said Barbara Williams, who heads environmental management at Fort Jackson. "It also depends on groundwater flow. So working our way backwards to where it was discovered led us to Kasserine Pass range."
The fort also has ruled out historic training missions in the 1950s that occurred across Leesburg Road in areas where homes have since been built, officials said. No RDX was used in the smoke grenades and signal flares that were used on about 17,000 across from the base's current boundary, charts posted at the meeting show.
RDX, short for Royal Demolition Explosive, has been used for decades in military explosives and is still used today. It is a key ingredient in the estimated 100,000 hand grenades thrown each year by soldiers at Fort Jackson.
Officials said, however, that current training is not hurting groundwater offsite.
"Where (RDX) is currently being used does not flow south, so that's how we know it is not affecting the residents who live south of Fort Jackson," Williams said.
Still, the question is what the Fort should do to protect people whose homes have polluted wells or lie in the path of the contaminated groundwater that did flow off the base.
Options include connecting the area with tainted wells to the city of Columbia's water system, cleaning up the groundwater or continuing to provide home filters for people with RDX-tinged water. Hooking up to Columbia's water system is a potentially expensive project, city officials have said. Cleaning up the groundwater could take a decade or more, Williams said.
"All we can do is manage it from here on in," Williams, noting that the fort is willing to test more wells for people who are concerned..
Tuesday's meeting, held on a soggy cold night at a base clubhouse off Leesburg Road, drew no more than a few dozen residents to learn about the contamination.
The fort did not advertise the meeting to the general public because officials said they wanted to speak with people in the immediate area who are most directly affected. The fort sent about 245 invitations to neighbors, including all with polluted wells.
The effort to update neighbors was the latest development since RDX polluted groundwater was discovered at Fort Jackson more than five years ago. The fort confirmed in 2014 that five private wells off the base were contaminated with the toxin. Since that time, the fort says it has been routinely testing wells.
Since the fort began looking at the issue, about 16 percent of the drinking water wells tested near the fort have shown contamination from RDX, according to federal data obtained last summer by The State newspaper.
Results the fort released last summer showed that 31 of 186 wells tested had some level of RDX in the water. That's more than 16 percent. Of those wells with RDX, 16 of those showed levels above the safe drinking water standard or exceeded a federal risk limit, the fort reported in July.
The fort said last summer it intended to sample a minimum of 75 wells annually off the base. While the fort gets much of its own drinking water from the city of Columbia, some on-base drinking water comes from about 10 wells. Williams said tests have not found RDX pollution in Fort Jackson drinking water wells.
The contamination from Fort Jackson isn't unique to the Columbia base. Military bases across the country have tainted groundwater with an array of toxins from historic use of the property.
Fort Jackson is one of the nation's top Army training bases. More than 45,000 soldiers go through basic training and advanced training at the fort every year.
This article is written by Sammy Fretwell from The State and was legally licensed via the Tribune Content Agency through the NewsCred publisher network. Please direct all licensing questions to firstname.lastname@example.org.