Geosynthetics Closure System for Abandoned Elizabeth Mine
Weston & Sampson was retained as the geosynthetics quality control supervisor for the installation of a geosynthetics closure system that covers 45 acres of mine tailings. The Elizabeth Mine is an abandoned copper mine located in South Strafford, Vermont.
The Environmental Protection Agency (EPA) non-time-critical removal action addresses mitigation measures to control acid mine drainage from two large tailing piles and waste rock/heap leach piles. The tailings are rich in metals and sulfides and as water passes over and through the tailings, sulfuric acid is produced and the metals within the tailings are dissolved and mobilized. This results in acid mine leachate of metals that impacts local groundwater, the Copperas Brook and the West Branch Ompompanoosuc River.
The 45-acre geosynthetic cap was constructed over a two-year period. The cap consisted of a textured 60-mil linear low density geomembrane liner overlain by a geosynthetic triplaner drainage geocomposite. The geosynthetics were covered with 24 inches of a vegetative support layer and six inches of topsoil, which was then hydro-seeded.
As follow up work for the Vermont Department of Environmental Conservation (VTDEC) Dam Safety Section, an Emergecy Action Plan was prepared to address provisions in case the impoundment were to fail and cause a flood wave to travel down stream to residents and roads.