Abstract
Some irrigated lands along the Clark Fork River, near Deer Lodge, Montana contain elevated levels of arsenic, cadmium, copper, lead and zinc, and low soil pH. This contamination originated from river-transported mine wastes associated with metal mining, milling and smelting operations in the Butte and Anaconda, Montana areas. In May 1999, the U.S. Environmental Protection Agency ordered the responsible party (ARCO) to reduce contamination on historically irrigated lands along the Eastside Ditch near Deer Lodge, Montana. These lands consist of residential properties and adjacent pastures. The preferred action for the residential yards is excavation and replacement of soils (up to 18 inch depth) whose average arsenic values exceed the trigger value of 120 mg/kg which is the 95% lower confidence interval value of the human health risk-based residential concentration of 150 mg/kg. The preferred remedial action for adjacent pastures is tilling and liming to varying depths (up to 24 inches) to evenly distribute arsenic and metals into the soil profile, and neutralize potential and active acidity.
The Reclamation Research Unit, in conjunction with W.B.E, Inc. and CH2MHill performed oversight for sampling and remedial actions along the Eastside Ditch for the U.S. EPA. Soil samples were collected from 17 residences and adjacent pastures, and 2 pastures in 1998 and 1999. The soil samples were analyzed for arsenic, copper, lead, zinc and pH. Soils were excavated and replaced in 8 residential yards as of November 1999 (remaining soil arsenic levels are typically below 70 mg/kg). In addition, 10 adjacent pastures were tilled and limed as of November 1999. Further sampling and remedial activities are expected to continue in Spring 2000.
Start Date
14-4-2000 12:00 AM
End Date
14-4-2000 12:00 AM
Document Type
Poster
Time Critical Removal Action in Response to Contaminated Soils Along the Eastside Ditch near Deer Lodge, Montana
Some irrigated lands along the Clark Fork River, near Deer Lodge, Montana contain elevated levels of arsenic, cadmium, copper, lead and zinc, and low soil pH. This contamination originated from river-transported mine wastes associated with metal mining, milling and smelting operations in the Butte and Anaconda, Montana areas. In May 1999, the U.S. Environmental Protection Agency ordered the responsible party (ARCO) to reduce contamination on historically irrigated lands along the Eastside Ditch near Deer Lodge, Montana. These lands consist of residential properties and adjacent pastures. The preferred action for the residential yards is excavation and replacement of soils (up to 18 inch depth) whose average arsenic values exceed the trigger value of 120 mg/kg which is the 95% lower confidence interval value of the human health risk-based residential concentration of 150 mg/kg. The preferred remedial action for adjacent pastures is tilling and liming to varying depths (up to 24 inches) to evenly distribute arsenic and metals into the soil profile, and neutralize potential and active acidity.
The Reclamation Research Unit, in conjunction with W.B.E, Inc. and CH2MHill performed oversight for sampling and remedial actions along the Eastside Ditch for the U.S. EPA. Soil samples were collected from 17 residences and adjacent pastures, and 2 pastures in 1998 and 1999. The soil samples were analyzed for arsenic, copper, lead, zinc and pH. Soils were excavated and replaced in 8 residential yards as of November 1999 (remaining soil arsenic levels are typically below 70 mg/kg). In addition, 10 adjacent pastures were tilled and limed as of November 1999. Further sampling and remedial activities are expected to continue in Spring 2000.