That investigation spanned several years and concluded with a $US27.5 million ($AU30.4 million) fine issued to ANR for over 1600 offenses that had gone unnoticed by the DEP.

DEP deputy secretary for mining John Stefanko told the Westport News that Alpha's discharge-monitoring report was reviewed by staff, but not always right away. He conceded “maybe there were some gaps, maybe data wasn't reviewed in three months but in six months.”

"Data probably wasn't being monitored in a timely manner," he continued.

Stefanko insisted that the DEP worked with Alpha to resolve its compliance issues once it became aware of them. The company had not reached the point of enforcement when the EPA moved forward with its settlement. To avoid duplicated efforts, the DEP joined the EPA’s consent decree.

Alpha’s violations are reported to be one of many currently under investigation. Consol Energy is reported to have committed violations to the same degree as Alpha since 2006.

Stefanko confirmed that Consol had submitted information to the DEP, but failed to comment on whether they were looking into the company’s compliance history.