The US Department of Environmental Protection (DEP) said that longwall mining at Consol Pennsylvania Coal Company's Appalachian Bailey Mine in Greene County resulted in ground movements that damaged the Ryerson Station Dam.
DEP Mining Operations director Michael Terretti said the findings were based on concrete information from the department of conservation and natural resources, DEP files and months of site observations.
"The department stands behind its findings and will now move into the second phase of its investigation, which is to address the appropriate remedy," Terretti said.
According to DEP findings, underground coal mining at Bailey Mine caused pipeline buckling and road and stream heaving.
The findings also identified several instances of ground movements throughout Appalachian coal fields, including three near to Bailey Mine and two in West Virginia.
The investigation determined that, other than longwall mining activity, no other activity took place in spring and summer 2005 in that area which could cause ground movement and damage to the dam.
The interim report, however, overlooked that dam instability and hillside instability could also be causes for ground movements.
The investigation was initiated following an Allegheny County Court of Common Pleas' decision that directed DCNR to file a claim with DEP under the state's Bituminous Mine Subsidence and Land Conservation Act for damage sustained by the dam.