Abstract: This article provides examples of reclamation and remediation in Colorado watersheds. The projects were undertaken by the US Environmental Protection Agency (EPA) Region 8, in cooperation with the Colorado Division of Minerals and Geology (CDMG), Colorado Department of Public Health and Environment (CDPHE), US Forest Service (USFS), the Bureau of Land Management (BLM), Bureau of Reclamation (BOR) and the US Geological Survey (USGS). These agencies collaborated on the environmental problems at abandoned mines. These samples involved the interaction of surface and ground waters with sulfide-bearing rocks, mine workings and surface mine spoils that produce acid solutions charged with heavy metals that are toxic to organisms. In these examples, acid mine drainage from historic mines in Colorado has been approached cooperatively with stakeholders. Each example emphasizes one aspect of the three-stage process. These stages include characterization and prioritization, hydrologic controls and the evaluation of long-term remediation activities.

Abstract: In the 1994 paper by Brown, Skousen & Renton it was argued that settleability and wet-packing density were the most important physical characteristics of sludge from treatment of mine drainage. These characteristics plus zeta-potential, intrinsic viscosity, specific resistance to filtration, and coefficient of compressibility were determined for several sludge samples from passive treatment sites and for several sludge samples that were prepared in the laboratory. Sludge from passive systems had high packing density, low intrinsic viscosity, low specific resistance to filtration and low coefficient of compressibility compared to sludge that was produced after addition of NaOH.