Environmental Effects of Mining in the Anthracite Region: Problems and Possible Solutions
Kenneth M. Klemow, Ph.D.
Acid Mine Drainage
Perhaps the best known effect of mining on aquatic ecosystems comes in the form of acid mine drainage (AMD). AMD is characterized by the presence of inorganic elements like iron, manganese, aluminum, and sulfates that are carried by water discharging from culm banks or mine voids. The chemistry of AMD has been well studied, especially in the bituminous coal fields of western Pennsylvania and southern Appalachia. The AMD problem in the anthracite fields has received some attention between 1940 and 1985, but work done in the 1990s has both increased our understanding of the pattern of AMD effects and trends in water quality over the last 40 years.
AMD forms when water intercepts underground pyrite or aluminum-bearing deposits, and leaches harmful substances from those deposits. In some cases, AMD is generated when rainwater or snowmelt enters into culm banks, and dissolves the iron-rich coal waste material. In other cases, AMD forms when the water table contacts residual pyrite in underground mine workings, and then flows to the surface. AMD normally enters creeks in two ways. The first is in the form of seeps that often discharge from the bases of culm banks. Such seeps are rarely exceed 50 gallons per minute, but often contain high concentrations of dissolved metals and sulfates. The second is in the form of deep mine outfalls that often spew thousands of gallons of mine water per minute into receiving waterbodies. Such outfalls exist at the points of old mine shafts or ventilation holes, but some are actually boreholes that were intentionally excavated to relieve underground flooding. Some of the worst mine outfalls in the anthracite region include the Jeddo mine tunnel northwest of Hazleton, the old Newport Dump west of Nanticoke, the Solomon’s Creek boreholes south of Wilkes-Barre, the Butler mine tunnel in Pittston, and the Old Forge discharge south of Scranton.
AMD impairs the ecological productivity in receiving waterbodies in several ways. First, the dissolved iron undergoes a series of chemical reactions that lead to the formation of insoluble iron hydroxide, which is really liquid rust. Iron hydroxide particles coagulate in the water, staining the water bright orange. Over time, those particles settle onto the creekbed forming deposits known as “yellow boy.” The cloudy water and accumulated deposits create conditions harmful to all forms of aquatic life. Indeed, studies recently done in the southern Wyoming Valley indicate that AMD-impacted streams are completely devoid of invertebrates and fish life. In the middle and southern anthracite fields, dissolved aluminum and low pH conditions typify the AMD problems. Dissolved aluminum presents a problem to aquatic animals because it collects on gills, thus rendering them incapable of gas exchange. Low pH levels, indicative of high acidity loads, also impair the functioning of all forms of life because they disrupt normal cellular metabolism.
Because it enters into creeks and streams, AMD is normally carried downstream to receiving rivers, thus impairing their function. In the northern anthracite field of the Wyoming and Lackawanna Valleys, AMD is ultimately received by the Susquehanna and Lackawanna Rivers. The effect of AMD on the Susquehanna-Lackawanna complex is really unknown and deserves intensive study. Spot analyses indicate that water quality in those rivers is at least impaired at points of entry and for some distance downstream. Indications of that impairment are obvious at the discharge of the Old Forge borehole into the Lackawanna River, the confluence of the Lackawanna and Susquehanna Rivers, and where Solomon’s Creek, Nanticoke Creek, and Newport Creek all enter the Susquehanna. At those places, the riverbed is heavily stained by deposits of iron hydroxide. The nature of accumulation of those iron deposits, and their transport downriver are unknown and need further investigation. Moreover, the effects of mine drainage on invertebrates and fish in the river are also unknown. While numerous species of both types of aquatic life are found, biodiversity and productivity are probably both impaired to some degree by discharges of contaminated mine water from outfalls and creeks that receive AMD.