The Mine Environment Neutral Drainage program recently completed a review of soil covers on mine wastes in cold regions (MEND 1.61.5a 2009). Several dozen cold regions processes were identified as potentially important for soil covers. These effects can develop slowly enough that they may not be obvious in current observations of soil covers,, but quickly enough that they could have significant negative effects over a cover’s design life.
The current report presents the results of a series of tasks that each represent a small advance in the state of cold regions cover research:
• Cold regions phenomena identified in MEND 1.61.5a are characterized as “observed”, “suspected”, “expected” or “not expected” to affect the performance of various types of soil covers.
• The role of vegetation on cold regions covers is reviewed and available literature on cold regions evapotranspiration and rooting depth are surveyed.
• The state of the art of computer modeling of cold regions soil covers and related hydrologic processes is reviewed.
• Possible applications of convective cooling in both flat and sloping soil cover designs are examined using a series of bounding calculations.
• The potential for insulating layers to limit freeze-thaw effects on low-permeability barrier layers is examined.
• Ongoing soil cover trials or research programs in locations that might experience cold regions effects are identified and tabulated.
A series of additional studies are recommended for consideration. High priorities for immediate action are:
• Inspections of existing cold regions covers to identify and characterize cold regions effects;
• Continued information exchange to increase the likelihood that cold regions phenomena in existing covers will be properly identified, and to ensure that potentially negative effects are taken into account in the design of new covers; and
• Addition of evapotranspiration, root depth and related vegetation studies to ongoing cold regions cover trials.