Currently, efforts are being made nationally to reclaim abandoned mine lands and to mitigate their associated affects. Not only are millions of acres of land useless moonscapes, but their associated hazards, notably acid mine drainage, affect thousands of miles of waterways. Acid mine drainage is the single largest source of water contamination in every Appalachian coal mining state. In many instances only the symptoms can be treated, for instance, by channeling acid-impacted streams through limestone drains while the long-term causes go unabated. Such acid-generating mining waste is expected to continue unabated for 800–3000 years. This is why the method examined—sealing the mining waste of geological materials causing acid mine drainage with an impermeable fill material, while restoring megavoids—holds great potential. The main high wall has been restored to its original contours, covered with a manufactured soil, and planted. Monitoring of groundwater and monitoring wells indicate that the area water supply is improving since the initiation of this project (PADEP 2002).

The Bark Camp Mine Reclamation Laboratory was opened in 1980 to test various methods of reclamation, including the treatment of acid impacted streams with artificial wetlands, and the use of fly ash grouts to backfill stripped high-walls. Coal fly-ash is the mineral remnant of coal combustion, often containing large amounts of lime added to reduce sulfuric acid emissions, and usually having pozzolonic or cementitious properties. Since coal combustion is responsible for 50% of US electricity generation, over 130,000,000 tons of fly ash is produced annually, posing a major disposal problem.

The Bark Camp project sought to combine the massive fill requirements of mine reclamation with another volume related issue; the removal of 500,000,000 tons of dredged materials from US navigation channels annually. The size of todays shipping fleets requires the creation of channels in excess of natural depths. Erosion, sedimentation, and tidal processes make maintenance dredging unavoidable. Much of this vast amount of material had previously been disposed of in the near-shore and marine environment, but increasing sentiment against such disposal methods due to traces of agricultural and industrial contaminants has instigated a drive for beneficial upland uses. Upland placement of dredged mud consolidated with pozzolonic materials does not pose the problem of direct ingestion by mud-dwelling organisms, and this was the hypothesis tested at Bark Camp.

The Bark Camp Mine Reclamation project has been deemed extremely successful. The final report detailing this project is scheduled to be released in 2003.

There are two main technical issues associated with data preparation for further analysis: (1) vector-to-raster conversion, and (2) choice of spatial units and projection for selection of the pixel neighborhood for the focalvariety function.

Vector-to-raster conversion is a procedure that is accomplished by converting the spatial extent of the data into the gridded surface with a given pixel size. Pixel size selection depends on the computer power and available memory. Smaller pixel size creates large sizes for the grids and requires a considerable amount of processing time. Large pixel size makes files smaller, but resolution of the data becomes lower at the expense of the quicker data processing. After experimenting with grid pixel sizes, the size of 1 × 1 km was selected as most adequate for the speed and memory of the available computer (Pentium IV, 2 MHz processor, 1 Gb RAM). This pixel size places spatial resolution and accuracy of analytical results within 1 km. Results of analysis identify abandoned coal mines that satisfy conditions of the analysis. The geographical location and address for each mine is available from the associated attribute table. Therefore, this seemingly coarse resolution is not critical. If needed, mines can be located precisely according to its address information.

The focalvariety function requires setting of the search window or neighborhood for the analysis with an integer value greater than 1 (i.e., number of pixels). Original units for GIS data in this analysis are decimal degrees. In geographic conversion one degree is equal to 78.85 km (east–west arcs to distance at 45°N latitude); therefore, a 20-km search radius will be equal to 0.25 decimal degrees, and 100 km will be equal to 1.3. These numbers are less than 1 or not integers. To make the search radius in appropriate units, the original GIS data were reprojected into a geographic projection with units defined as meters. After data were reprojected, they were converted into grids with pixel size of 1 km, covering the total area of the contiguous United States.

Focalvariety analysis is one of the techniques available in a raster GRID module of ArcInfo GIS software (ESRI, 1992a,b). As was mentioned before, this function exists also in other GIS software packages. Focal analysis is a technique used with raster data that defines a neighborhood or search window and then executes a standard statistical or other technique within the window. Figure 1 shows an example of the focalvariety function.

Analysis with the focalvariety method produces grids with values corresponding to the number of various unique values found within the defined neighborhood. For the analysis we selected five different neighborhoods—20, 40, 60, 80, and 100 km. Upon completion of analysis, each neighborhood within which all four codes (corresponding to dredging sites, abandoned coal mines, fly ash and railroads) existed was mapped.

Figures 2, 3, 4, 5, 6 show maps of the contiguous United States with locations of abandoned coal mines suitable for reclamation projects similar to one in Bark Camp.

Maps (Figures 2, 3, 4, 5, 6) and associated GIS databases display information about location of potential mines for reclamation. These locations have dredging sites, fly ash sources, and railroads within radii of 20–100 km. More comprehensive data on these mines and resources is available in GIS database and corresponding metadata (documentation) files.

Additional analysis should be done to narrow down the list of potential mines for reclamation to mines with geotechnical problems similar to that at Bark Camp. These problems are categorized in the National Association of Abandoned Mine Lands Programs (NAAMLP) database. The Bark Camp project was aimed toward reclamation of the dangerous embankment and highwall created by strip mining.

Upon analysis of the 30 problem codes stored in the NAAMLP database, we found four codes that closely match the problem at the Bark Camp site. These are: dangerous highwall, dangerous impoundment, dangerous slide, and dangerous pile or embankment. These categories address problems of stability. Engineering remedies include major earth works in addition to installation of fencing and vegetative barriers (Natural Resources Conservation Service 1981). At Bark Camp the earthwork was done with dredged material amended with fly ash.

Additional selection of records from the database reduced the number of selected mines and generated a list of potential mine reclamation projects for mines similar to the Bark Camp geotechnical problem, displayed in Table 1.