PRAIRIEVILLE — Activity is stirring anew at an old hazardous waste dump in Ascension Parish. Federal regulators believed 35 years ago that the site had been cleaned, but state officials are concerned it might not have been fully remediated.

In recent days, contractors working with the state Department of Environmental Quality have been drilling three new monitoring wells on a wooded patch of land at the end of Tiger Heights Drive in Prairieville, agency officials said.

In the mid-1980s, barrels of hazardous chemicals with suspected or possible cancer-causing agents like vinyl chloride; 1,1,2-trichloroethane; and other chlorinated solvents and volatile organic compounds were discovered dumped and buried at the end of the street in what was a mostly wooded area at the time, residents said. 

051619 Tiger Heights drum site

The U. S. Environmental Protection Agency removed barrels that been buried more than 60 years ago by unknown parties, and the surface soil around them. Contaminated groundwater from a shallow monitoring well drilled at the site was disposed of as hazardous waste, according to DEQ summaries of the old cleanup.

Though DEQ officials say past tests of drinking water wells near the site showed chemicals from the barrels haven't escaped into the wells' water source, the chemicals have persisted in a shallow layer of groundwater and remain above state standards for environmental cleanup. Agency officials say they have recently come into the funding to investigate why that might be the case.

A December electromagnetic survey that can see up to 10 feet underground found five metallic "anomalies" suspected of being buried iron, according to a February report to DEQ.

Tommy Doran, a DEQ environmental scientist, said the agency can't definitively say whether that anomaly at the back of the property represents more barrels that weren't discovered in the past — parts of the front of the property near the road remain an illegal household waste dump — but the discovery and other recent findings have agency officials concerned.

With only one monitoring well on the property, DEQ and EPA have never been able to define fully the extent of any underground contamination, which is often known as a plume, and whether it has ever reached a nearby tributary of Muddy Creek or area water wells, so the agency is drilling the new wells to try to figure out what's happening.

"That's the purpose of these wells. We've got three wells we're putting out here and we're kind of getting a better handle on whether we've got a plume (underground)," Doran said at the site Tuesday.

The new drilling activity, off La. 929 southeast of Prairieville Middle School, has raised concerns in the historically black portion of Prairieville that predated the region's transformation into a Baton Rouge bedroom community. Longtime residents said they were frustrated that they haven't been told more about what DEQ is doing, that the problem wasn't dealt with completely the first time and that the situation indicates a general lack of care for residents in their area.

Margie Noble, 61, who lives at the end of Tiger Heights Drive and saw the old cleanup happen, said she asked people working on the site at the time if they shouldn't go farther into the back of the property, past an old fence line, to check for more barrels. 

"But I asked them and I asked the parish, 'This is as far as you all going? You all think there's nothing else back here?' 'On, no, we got it all,'" Noble said she was told. 

Doran said recent testing showed contaminants are along that fence line, and a February report to DEQ says three past environmental investigations dating to 1987 didn't look at the area now being reviewed.

News accounts from the time suggested the barrels were found when a school bus tire hit a buried barrel under the side of the road and got stuck, a version of events that Noble disputed.

Noble, a parish school bus driver, stood in the middle of the Tiger Heights turnaround at the end of the street and showed where a bulldozer operator hit the barrels and then almost dumped the contaminants on himself. At the time, in the mid-1980s, the turnaround for school buses was being constructed in front of her home.

"And when he flipped the bulldozer (bucket) to take it (the barrel) up and put on the back of the truck, the barrel, all the waste came out and he just took off running," Noble said. 

Many of the residents on Tiger Heights, including Noble and her family members, use well water and worry the lingering contamination could have been seeping into their water source all these years. Noble said the digging and the soil and barrel removal extended to her front porch across the street from the dump site. 

George Foreman, 42, and Cedrick Johnson, 30, Noble's son, expressed concern that polluted water may have caused health problems in the area, including some cancers that they don't believe are part of a coincidence. Everyone in the neighborhood took water from wells to "cook with it, take a bath with it and everything," Foreman said.

According to reports through the years of the site's monitoring, the contamination was found in a layer of shallow groundwater about 20 to 27 feet deep.

DEQ spokesman Greg Langley said that shallow aquifer is sealed off from lower layers by a thick layer of clay, with Langley adding that many wells in the area are tapping groundwater at a few hundred feet deep. Noble said her well is no more than 80 feet deep.

Doran said past testing of residential wells in the area have shown that their water is clear of contaminants from the old barrels.

Research into cancer clusters have often shown that relatively small but concentrated collections of cancer incidences, such as in a neighborhood, often are alarming but are statistically random. A 2012 academic review of 576 cancer cluster investigations over 20 years found that in only 72 cases could an increase in the normal cancer rate be confirmed. Of that 72, only three cases could be linked to possible exposure to a cancer-causing agent.

Doran said preliminary results from testing of the monitoring wells are expected in a few weeks.

Follow David J. Mitchell on Twitter, @NewsieDave.