Specifications include, but are not limited to: The scope of work is to remove waste rock from the ephemeral channel to reduce mobilization of metals and provide a stable conduit for natural runoff that does not contact waste rock. Waste rock will be relocated to an area west (on-site) of the current waste rock pile and ephemeral drainage path. Waste rock will be excavated to a clean-up goal to be set by the USFS and DRMS, considering the high copper, arsenic, lead, mercury and zinc as clean-up targets. Currently, the only clean-up target is for lead, set at 2,000 ppm, which is in keeping with clean-up levels in the Animas River basin set by the Environmental Protection Agency for recreational areas on the superfund site. Additional metals clean-up levels may be set in the field during project execution, depending on metals levels encountered below the waste rock pile in the native soils. Sampling during excavation will be done with an x-ray fluorescence meter to determine the levels in the soils for clean-up. The relocated and consolidated mine waste will be covered with clean cover talus as well as talus and scree harvested from on-site to reduce erosion. A drainage channel to convey acid mine drainage from the collapsed Thunder portal will be constructed within the existing portal access road prism. This drainage channel is estimated at 1,000 feet in length. The drainage channel will be constructed such that heavy equipment will be able to access the site in the future, but will block ATV and vehicle access to the Thunder portal. The drainage channel will empty onto the main road into Rush Basin and immediately drain off the road into the red Dolores formation that has higher buffering capacity for the acid mine water...
