The Elizabeth Mine in South Strafford, Vermont has transformed from a detriment to aquatic life to an award winning environmental project. The New England District and its contractors continue to improve the site.
The District awarded a $25 million Indefinite Delivery Indefinite Quantity (IDIQ) contract to Nobis Engineering on Dec. 19, 2017 for that purpose. Efforts under the new IDIQ will include cleanup in the Lord Brook Source Area, including closure of an open pit lake, closure of mine adits/entrances, and long term passive treatment of any remaining contaminated discharge. Nobis Engineering, Inc., a small business firm from Concord, New Hampshire, had previously installed the tailing pile cap in 2011 and 2012 and performed wetland mitigation in 2013. The U.S. Environmental Protection Agency is funding the work.
Elizabeth Mine is one of the largest and most intact historic mining sites in New England. “The Elizabeth Mine Superfund Site is located in Strafford, Vermont," said project manager Stephen Dunbar. "It is an abandoned copper and iron-sulfate mine that operated from 1806 until 1958. The operations started as open-cut type mining with underground mining starting in 1886. Between 1830 and 1930, about 250,000 tons of ore were mined, from which about 10.5 million pounds of copper were produced. From 1943 to 1958, three million tons of ore were mined, producing more than 90 million pounds of copper. All mining operations ceased in February 1958. At the end of its operation, the mine was abandoned without any closure measures to restrict access or to prevent run-off from entering the mine. In addition, there were 40 acres of exposed tailing piles (TP) which were still producing acid mine drainage. The acid run-off was causing water quality problems in receiving waters of the drainage, Copperas Brook, and downstream in the west branch of the Ompompanoosuc River.”
The U.S. Environmental Protection Agency (EPA) approached the New England District for assistance in 1999, beginning a long and massive cleanup effort. “Starting in 2005, EPA Region 1 retained the New England District to design and cleanup the Superfund site,” said Dunbar. “The New England District project delivery team (PDT) initially focused their efforts on constructing surface water and groundwater diversion structures, stabilizing the steep slopes of the tailing piles, and capturing and treating the contaminated discharge.”
Nobis has previously completed building demolition/abatement compliant with historic preservation requirements, re-graded the 43 acre site, constructed an engineered cap over 3 million cubic yards of waste, and treated millions of gallons of acid rock drainage and iron-impacted water.
Green Remediation Strategies implemented during construction received the Chief of Engineer’s Green Dream Team Award in 2014.
The 43-acre cap has been re-utilized by a private firm for a solar array providing enough electricity for about 1,200 homes annually.
Work on the Lord Brook Source Area is set to begin in March 2018 and will continue through the CY 2019 construction season.