2012 Abandoned Mine Land Reclamation Award Winners
Western Region Award Winner Spring Meadow Lake Abandoned Mine Reclamation Project Helena, Lewis and Clark County, MT
The Western Region AML Reclamation Award was presented to the Spring Meadow Lake Abandoned Mine Reclamation Project in Helena, Lewis and Clark County, MT.
In 2003 an undergraduate college student working on his senior thesis at Carroll College in Helena discovered that a well-known and heavily utilized state park in Helena, Montana was contaminated with extremely high lead and arsenic levels.
Spring Meadow Lake State Park hosts about 85,000 people each year to swim, fish, canoe, picnic and play.
The project removed waste from gold, silver, zinc and manganese processing dating from 1910 to 1920. The contaminated soil contained high levels of lead and arsenic which leached into the nearby lake.
Historic records indicated the man-made lake was a hardrock milling site prior to World War I. Between 1912 and 1920, it processed gold, silver, zinc and manganese ore from all over the state - ore from mines that are now listed on the EPA's Superfund list. State AML officials confirmed the student's findings that pollutants from those milled ores contaminated the park area.
Testing indicated arsenic levels in the lake exceeded drinking water standards by 20 times the limit, and high levels of heavy metals. Fortunately, the recreational beach areas were not contaminated, and fish and aquatic insects were not bio-accumulating heavy metals. The state reassessed its mine site reclamation priority list; Spring Meadow rose to the top by a large margin due to the volume and toxicity of the wastes at the site.
Cleaning up the park required a two-pronged approach. Some of the soil was contaminated so lightly that it could be transported to a lower-level disposal site in Montana. Other soil and sediment, however, was so badly contaminated it would require heavier treatment or transport out of state. The team excavated about nine acres of lightly contaminated soil at a depth of 3 feet. They removed 65,000 tons, which was treated and hauled away to an approved disposal site.
The state converted the old ore milling site, including some of the old structures, into the new Montana Outdoor Discovery Center, which provides visitors with opportunities to learn about wildlife and nature.
To address the heavier contaminated soil, workers mixed it into Portland cement, which trapped the heavy metals and prevented leaching. This allowed the final product to be sent to the lower-level disposal site. Workers then backfilled the area with replacement soil and rock, then graded, seeded, and planted about 13 acres. Finally, the state redeveloped the old milling structures and named it the Montana Outdoor Discovery Center.
Visit the Montana Department of Environmental Quality Abandoned Mine Lands Website at http://deq.mt.gov/AbandonedMines/default.mcpx