- Remedial Design
- Remedial Action
- Construction Oversight
South Strafford, VT
Nobis is performing Phase II Non-Time-Critical Removal Actions (NTCRA) for the U.S. Environmental Protection Agency (USEPA) under contract to U.S. Army Corps of Engineers New England District (USACE). Preparation of final construction documents and plans began in December 2010. Preliminary on-site activities began in April 2011, with full scale construction beginning in May 2011. Total contract value is $20,000,000.
The Elizabeth Mine is an abandoned copper mine located on Mine Road in the Village of South Strafford, Vermont. The Site includes the Elizabeth Mine and the local areas impacted by the release of hazardous substances. The property consists of two mine tailings piles, one area of waste rock and heap leach piles, two open-cut mines, several adits (horizontal mine entrances), underground shafts and tunnels, ventilation shafts, and several former ore processing buildings.
Deposits at the Elizabeth Mine were discovered in 1793. The mine operated from the early 1800s until its closure in 1958. The ore was initially valued for its iron content, and then its pyrrhotite content from which copperas (iron sulfate) was produced. Circa 1830, the deposit was primarily exploited for its copper content based upon the recognition that a significant amount of chalcopyrite (copper iron sulfide) was disseminated in the pyrrhotite. For nearly a century, intermittent production came from the open-cut mine as underground work did not begin until 1886. During the early mining operations, several copper smelters were built on the property. Between 1830 and 1930 approximately 250,000 tons of ore were mined from which approximately 10,500,000 pounds of copper were produced. From 1943 to 1958, 2,967,000 tons of ore were mined producing more than 90,000,000 pounds of copper. All mining operations ceased in February 1958. At the close of the mining operation, the mine property encompassed approximately 1,400 acres.
The tailing and waste rock on the Site are rich in metals and sulfides. As water passes over and through the tailing and waste rock, sulfuric acid is produced and metals are dissolved and mobilized. This results in acid rock drainage, which contributes an elevated load of metals, decreases alkalinity, and increases conductivity within Copperas Brook, which ultimately discharges to the West Branch of the Ompompanoosuc River.