1/ ■ i / 



\ 



i 



1 



1 

 v ! 



i 



! . ' 



1 i 





Figure 35 — Abandoned mines can adversely affect the environment through acid 

 drainage. 



of noncoal past producers. Most of these mines were underground operations 

 (69 percent, 61 percent, 76 percent, 68 percent, and 83 percent, respectively). 



— Both surface and underground mines can be affected by acid mine drainage, 

 although this problem is more commonly associated with underground mines. 

 When sulfide-rich strata are exposed to air, acid forming reactions are triggered 

 and oxidized sulfides are created. During and after mining, water comes into 

 contact with the oxidized sulfides. Acid mine drainage problems are 

 exacerbated when the low-pH water comes in contact with mineralized zones 

 and dissolves heavy metals, many of which are toxic to aquatic life. 



— In the Eastern United States, most acid mine drainage is the result of past coal 

 mining operations. In the western parts of the country, most acid mine drainage 

 flows from abandoned underground metal mines. Estimates of the number of 

 western mines affected by acid drainage range from 20,000 to 50,000. 



— Over 13,000 past producers are located within the administrative boundaries of 

 the National Forest System. Many of these are patented and unpatented mining 

 claims dating from the turn of the century. In the Western United States, 1 ,500 

 of these sites have been identified as having significant acid mine drainage 

 problems. 



Responsibility for abandoned mines is shared among Federal and State governments 

 and private land owners. The Surface Mining Control and Reclamation Act of 1977 

 (SMCRA), due to expire in 1995, requires surface-mined coal operators to pay a 

 quarterly fee to the Abandoned Mine Reclamation Fund. The Energy Policy Act of 



66 



