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Remedying the Ecological Effects of Mining

Environmental Effects of Mining in the Anthracite Region: Problems and Possible Solutions

 

Kenneth M. Klemow, Ph.D.

Remedying the Ecological Effects of Mining

As with most problems, the environmental degradation caused by mining can be rectified. One can classify such remedies by whether they fix terrestrial vs aquatic ecosystems. Many approaches to fixing mining-related problems are based on straightforward methods that are decades old. However, novel approaches have been developed within the past twenty years, largely drawing from the new discipline of Restoration Ecology. Those new approaches have been used to a limited degree in remedying environmental problems within the anthracite region. Much more can be done to implement that new knowledge and to discover even better approaches in the future.

In terms of terrestrial ecosystems, successful restoration depends upon improving the physical environment and introducing plant stock to enhance the rate at which vegetation can develop. Improving the physical environment for plant growth typically involves regrading the disturbed landscape to eliminate highly erodable steep slopes, and improving the soil by the adding fertilizers and organic mulch. Plant stock is usually added by seeding the area with species tolerant of reclaimed mine sites, and able to form a dense vegetative cover quickly.

When they are implemented, mine reclamation practices generally follow the guidelines given in the 1977 Surface Mining Control and Reclamation Act (SMCRA). In essence, that legislation mandates that mine reclamation is accomplished when the mined site is regraded to a topographic contour that approximates the original conditions, and a dense cover of vegetation is established. Reclamation specialists satisfy the requirements of SMCRA by first bulldozing the disturbed area to a smooth contour having uniform grades. A fertilizer containing nitrogen, phosphorous, potassium and lime is then added. Finally, the area is seeded, typically by a grass-legume mix. Those practices usually create a meadow-like stand of vegetation that protects against erosion and can even by used as pastureland.

Because the environmental damage caused by mining in the anthracite region occurred long before the implementation of SMCRA, reclamation is mostly conducted by governmental agencies. The most active agency involved in mine reclamation is the Bureau of Abandoned Mine Reclamation (BAMR), of the Pennsylvania Department of Environmental Protection (PADEP). In the northern anthracite field, the Earth Conservancy (EC) is also engaged in reclamation efforts on its land holdings.

While the efforts to reclaim mine lands according the SMCRA guidelines do improve their ecological productivity, some concern has been expressed over the long-term effects of current reclamation practices. Specifically, the grass-legume mixture introduced as a vegetative cover is viewed as being artificial because it uses alien species not really belonging to the native flora of Pennsylvania. Also, the meadow-like vegetation may actually hamper the development of a forest community that is normal for eastern Pennsylvania. In short, reclaimed sites may remain in an arrested state of ecological development, and might not be sustainable over the course of decades. As an alternative, some restoration ecologists are calling for an alternate “smart” reclamation strategy that involves rough-grading the site, and introducing native species that will ultimately be consistent with the development of forest conditions. The feasibility of using that “smart” approach to reclaim abandoned mined sites in the anthracite region deserves to be explored.

Efforts to reclaim impaired aquatic habitats have also been conducted in the anthracite area, but the practices employed are evolving as new knowledge becomes available. Restoration of aquatic habitats is aimed at promoting healthy streams, lakes, and wetlands with high ecological productivity and biological diversity. To accomplish that goal, attention must be devoted to restoring the both the physical conditions and chemical makeup of local waterways.

Historically, addressing chemical contamination in the form of acid mine drainage often meant adding additional chemicals, such as lime or caustic soda. The aim was to neutralize the acidity and quickly precipitate the heavy metals. While generally effective, adding neutralizing chemicals to AMD can be costly and dangerous.

During the past fifteen years, passive approaches to addressing AMD have been developed. Such approaches involve technologies such as the use of constructed wetlands, anoxic limestone drains, and sequential alkalinity producing systems (SAPS). Often, those technologies are combined in a given project. The goal is to raise the level of alkalinity of the water and promote the oxidation and removal of heavy metals, particularly iron, manganese, and aluminum, in a controlled location.

One of the first AMD-treatment wetlands in the anthracite region was constructed by the Earth Conservancy in Hanover Township, Luzerne County. Completed in 1996, it treats a large seep that enters into Espy Run, a tributary of Nanticoke Creek. Based upon the success of that wetland, the EC constructed a 2.2 acre wetland to treat mine water discharging from the Dundee Outfall, 0.7 miles from the original wetland. That second wetland utilizes a novel water aeration system to promote iron oxidation, and began working in May 1999. Analyses of that system’s performance indicate that it removes over 95% of the iron in the water, exceeding 300 lbs per day.

Further implementation of constructed wetland technology is possible. However, it should not be viewed as the total solution to the AMD problem, largely because not enough land is available for wetland construction. Instead, fixing the AMD problem will probably require the elimination of root causes of mine drainage. In one sense, the removal of culm banks and the implementation of sound reclamation techniques in terrestrial mine-impacted sites should reduce the infiltration of rainwater and snowmelt into pyrite-bearing rock strata. Second, mine voids can be filled with various materials like fly ash, as done in West Virginia. Filling mine voids reduces the flow of mine water from normal discharge points, but should be used with care, especially if done in populated or industrial areas.

A third, highly promising approach to eliminating the formation of AMD is to restore normal creekbed conditions in abandoned minelands. Because many creeks in minelands often lose water to underground mine pools making them impermeable to water loss is an attractive option. The idea of lining creekbeds with impermeable material is not entirely new. Indeed, coal companies often enclosed watercourses in flumes to prevent seepage into inactive mines. However, such structures often deteriorated and failed over time. The confinement of watercourses in smooth-walled flumes also prevents a productive aquatic community from forming.

Within the past ten years, new techniques have been developed to restore stream channels following ecologically sound principles. First, channels are constructed to mimic the horizontal morphology of natural watercourses, specifically by using a “channel within a channel” design. That morphology allows the channel to accommodate wide ranges of flow conditions from low volume baseflows to periodic floods. Second, the new designs provide for the development of pools and riffles that create the diversity of habitats needed by the array of invertebrates and vertebrates found in healthy aquatic ecosystems. Third, the materials used to form the bed and banks of newly restored stream channels are selected to mimic natural conditions and promote high levels of biological diversity. For example, new approaches abandon the use of conventional rip-rap and concrete in favor of “bioengineering” materials like layered shrubs and carefully oriented tree trunks. Finally, wooded buffer zones are placed along the sides of creeks because they provide both organic matter to feed aquatic invertebrates, as well as shade in reducing extreme summertime temperatures.

The result of a successful stream restoration effort has the dual benefit of keeping otherwise clean water on the surface, thus preventing the formation of AMD, and providing a biologically rich corridor that effectively links headwaters to lower reaches of the watershed. A well designed stream corridor also has recreational benefits for hiking, mountain biking, and horseback riding.

To date, a ecological stream restoration effort has been conducted near Hazleton by BAMR. A proposal to develop an even more comprehensive restoration effort along the Nanticoke Creek headwaters in central Luzerne County has been submitted by the US Army Corps of Engineers. Clearly, however, many miles of degraded streams and other aquatic habitats exist in the anthracite region, and deserve to be restored.

 

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