The East Helena School District has temporarily halted work on a section of Dartman Field after a soil sample tested higher for lead than allowed by the Environmental Protection Agency.
A couple of weeks ago, construction crews were working on the west end of the field in an area where athletic fields will be built when the sample came in. The school district's Superintendent Ron Whitmoyer said soil used in the deep tilling process, which mixes contaminated soil with clean soil to reduce concentrations to acceptable levels, had produced several samples well below the EPA threshold of 500 parts per million for lead.
“Then we got a sample of over 1,100 (ppm for lead) and we were dumbfounded by that, we thought that we would be well within compliance,” he said. “When that sample came back that high out of the stockpile … we stopped everything to say, hold on a second what’s going on there.”
The district immediately halted construction and contacted the EPA, he said.
In recent years, the school district acquired two parcels of Dartman Field from the Montana Environmental Trust Group. The first parcel was donated for the new Prickly Pear Elementary School and the second parcel purchased for the future East Helena High School.
Dartman was formerly owned by Asarco, the company that operated the East Helena lead smelter, and conveyed to the trust through a settlement. Lead contamination on the property means that any future use requires environmental remediation. The school district agreed to clean up the area of the athletic fields to the stringent residential standard of 500 ppm under the terms of the donation and purchase.
Construction crews scraped the first layer of soil in the area and stockpiled it for mixing during deep tilling. But historic flood channels across the field have produced “hot spots” of contamination where lead-heavy sedimentation settled. Officials believe one of the hot spots likely triggered the high sample.
“Sometimes some surprises are out there, and the school district did the right thing when they identified some higher lead levels than anticipated,” said Betsy Burns, EPA’s project manager for East Helena.
To the north, construction of a 300-home subdivision also found some higher lead levels and crews had successfully “chased” the contaminated pockets and reduced lead to residential levels, she said. The area where the sample was discovered is also currently fenced off and inaccessible to the public, Burns added.
On the district’s property, additional testing is taking place with one option to do a deeper till to further dilute any potential contamination, Whitmoyer said.
Because of recommendations that the district wait until the fall to seed the athletic fields, Whitmoyer does not anticipate any major delays. The district received a state grant for remediation, and while the financial impact of the delay is not certain, the project is still within budget, he said.
In the meantime, barley was planted on the area to maintain the soil until the fall.