Surface Water Impacts from Active Underground Mining

High extraction mining techniques have produced the need to mitigate and understand ground movements associated with this technology.  Tools such as the Surface Deformation Prediction System (SDPS) facilitate sound scientific decision making in the industry and has continually improved since its inception in 1987.  The capabilities of SDPS have expanded on an as-needed basis.  Currently, the regulatory climate has emphasized the need to understand the impact of underground mining on surface waters, physically and chemically.

The SDPS program is used to conduct an analysis of ground movements to assess optimal barrier pillar size for stream protection.  Typical analytical and empirical methods used in mine planning were compared against SDPS methods to ensure the validity and advantage to the use of SDPS for this purpose.

Finally, underground mining effects on stream chemistry and health were explored by studying the heavily mined and industrialized watershed of Dumps Creek located in Russell County, Virginia.  This watershed has been identified as being impaired since the Virginia 303(d) List of Impaired Waters was created in 1994.  Currently, there are two pumps staged in the headwaters region of Dumps Creek that help to maintain water levels in an inactive underground mine.  The pumping is necessary to control methane levels that rising water could force into an active underground mine that lies stratigraphically above the inactive mine.  Water is pumped on an as-needed basis and discharges directly into Dumps Creek.  Historic measurements of stream conductivity and benthic health scores were compared to assess whether a correlation exists between the two measurements.  These measurements were compared based on regulatory decisions that emphasized that conductivity is a direct indicator of stream health in all watersheds.

Scientific contributions associated with this research include: Further developments in the use of SDPS programming in order to account for stream protection on a case by case basis for both mine panel and surface water protection by optimizing barrier pillar size in relation to a nearby stream; the analysis of available and currently obtained water chemistry data in a mining impacted watershed in attempt to further research to appropriately characterize and mitigate specific problems in order to improve stream health; and, assessment of the complexity of water chemistry impacts from underground mining as related to stream health indicators in different chemically dominated watersheds.