Abandoned Mine Drainage Basics
Contaminated water seeping from abandoned coal mine areas (commonly known as abandoned mine drainage, AMD) is the most severe water pollution problem in the coal fields of the Appalachian mountains of the eastern United States and certainly in the bituminous and anthracite coal fields of Pennsylvania. There are many possible contaminants in and around abandoned mines. The most common and severe problem is a certain type of AMD which is highly acidic. Acid mine drainage, as it is often called, can kill fish and aquatic insects, stunt plant growth, eat away concrete and metal structures, raise water treatment costs, and color stream banks and beds a bright, rusty, garish orange. In addition, it can leach toxic concentrations of metals like iron, and aluminum from mine rocks, causing further contamination of creeks, rivers, and ground water.
The problems of AMD are not always from acidity; toxicities of certain metals and even alkaline mine drainage can cause water quality problems in the eastern United States. Whatever the type of AMD, it is this pollution that degrades habitats, causes safety problems, ruins the natural aesthetics, and has a negative economic impact in general.
The majority of AMD problems stem from the reactions of the mineral pyrite with water and oxygen. Not one, but a series of chemical reactions occur creating the pollutants that appear in our waterways. The specifics of where and how these reactions occur is dependent on the specifics of the geology and hydrology of the particular site. No two AMD discharges are exactly alike chemically, (In fact, we prefer the term Abandoned Mine Drainage over Acid Mine Drainage, because some discharges are actually alkaline.) The individual impacts and the options for treating discharges have much variability.
This, the AMD Basics section, will provide you with an appreciation for
For those wanting to dig deeper a section on the chemistry of AMD and its treatment provides the following topics: