Tests revealed the remains of historic ore from an abandoned copper mine at the Elizabeth Mine Superfund Site in Strafford, Vermont proved dangerous to human health. Remediation of the site would prevent impending catastrophic failure of the tailings dam, as well as protect human health and environmental systems in the area.

Conti Federal stabilized the 30-acre, 80-foot high, 1,600-foot long TP-1 copper tailings dam in two distinct phases of work. The first phase entailed replacement of a failed decant piping system, which included installation of a 36-inch diameter decant system extending from a pond inlet structure 840 feet with an emergency spillway leading to a constructed outfall. The first phase also included natural stream stabilization.

During the second phase, Conti Federal stabilized the tailing dam, which included site infrastructure development, removal of transported tailing sediments, regrading/ stabilizing the steep tailing dam, toe drain system construction, earthen buttress construction and site restoration.

Conti Federal successfully completed both phases under an aggressive schedule by mobilizing quickly, managing unanticipated and difficult site and soil conditions and coordinating closely with the client.

Communication and alignment between Conti Federal and the USACE team produced a final product that garnered Conti Federal a General’s Coin and a District Coin of Excellence.

Key features of the project included:

  • Installed piping and inlet structure, emergency spillway and outlet structure
  • Excavated wetlands
  • Developed and managed 12-acre onsite borrow area
  • Constructed 75,000 cubic yard earthen buttress
  • Constructed subsurface drain system
  • Restored and stabilized 40 acres of distributed areas

“Conti’s efforts to make this as seamless as possible led to a more mutual trust and product for our customer, the EPA.”

-James A. Morocco, Resident Engineer/ACO, USACE New England