The Environmental Protection Agency will begin removing lead-contaminated soil from East Helena residential properties this June, with work expected to run through October. The effort expands cleanup tied to the former ASARCO lead smelter, which has left contamination across the area for more than a century.

The expansion is driven by a recently lowered acceptable residential soil lead standard. The EPA and the Montana Department of Environmental Quality dropped the threshold from 500 parts per million to 400 parts per million, meaning properties previously considered remediated may now require additional work. There will be no cost to affected property owners. EPA remedial project manager Bridget Williams said the agency still has $10 million remaining from the ASARCO bankruptcy settlement, plus an additional $40 million in federal funding to cover the work.

Under a new agreement, the U.S. Army Corps of Engineers and the EPA will oversee contractors handling the removals. Williams said crews will dig down 18 inches, remove contaminated soil, and bring in clean fill. Cleanup efforts under the federal Superfund program have been underway at the East Helena site since the 1980s.