- Remedial Design
- Remedial Action
- Construction Oversight
South Strafford, VT
The Elizabeth Mine Site, one of the largest intact historic mining sites in New England, operated for 100+ years producing over 50,000 tons of copper. After the mine closed in 1957, associated mine waste remained whose acidity and metals posed harmful to the area’s water and eco systems. The U.S. Environmental Protection Agency (EPA) designated the area as a “Superfund” site and developed a remedy to contain the waste and reduce pollutants.
In 2010, Nobis was selected to close tailing piles - Phase II Non-Time-Critical Removal Actions (NTCRA) - for the EPA under contract to U.S. Army Corps of Engineers New England District (USACE). The team’s efforts were focused on constructing surface and groundwater diversion structures, stabilizing tailing piles, and capturing and treating contaminated discharge. Nobis' services on the $20 Million project included: project management, construction oversight, building demolition/abatement, waste excavation/consolidation, construction of a 43 acre tailing and waste rock landfill and geosynthetic cap, wetlands mitigation and construction.
In addition, Nobis treated over 10 million gallons of acid rock drainage (ARD) and mine influenced water (MIW) - roughly 20 Olympic Swimming Pools of water - using an innovative lime amendment Rotating Cylinder Treatment System (RCTS) to oxidize and precipitate metals. The RCTS consolidates several systems into one and improves efficiency, thereby lowering treatment costs.
The team implemented a “Green Remediation Strategy” at the outset of the cleanup to identify measures to reduce impacts to the area’s natural and cultural assets. Strategies included:
- reducing air emissions by using fuel-efficient equipment and having a no-idling policy;
- purchasing and hiring locally to stimulate economic growth to the tune of 97,000 labor hours of local contracting;
- reusing existing construction materials or using commercially-available environmentally-friendly products. For example, more than 90,000 cubic yards of earthen fill was obtained onsite. This eliminated more than 6,000 trucks trips and saved nearly a million pounds of air emissions.
Sustainable lessons from this pilot project will be applied to future remediation projects, saving energy, reducing costs to the government, and providing positive economic and environmental boosts to impacted communities.
The cap’s construction has resulted in significant and ongoing reductions in both acidity and heavy metals in the water, demonstrating the ultimate effectiveness of the remedy.