Another 20 operations with similar track records have been identified with a second round of warnings.
Those showing an improvement were Blue Diamond Coal's No. 77 mine (71% reduction); the Elk Run Coal operated Black King mine (32%); Chess Processing, also operated by Elk Run Coal (47%); the Riverside Cement Co's Oro Grande Quarry (54%); Left Fork Mining's Straight Creek No. 1 (60%); and Tilden Mining's Tilden mine (45%).
A violation is S&S, or significant and substantial, if it "significantly and substantially contributes to the cause and effect of a coal or other mine safety or health hazard," according to MSHA.
In order to be removed from consideration for a second round of notices reflecting a pattern of violations, the S&S violation frequency rate must have been reduced by 30% over the agency's 90-day review period or to levels above average for the US.
"[The mines] were encouraged to develop a written corrective action plan to reduce S&S violations and to avoid violations caused by imminent dangers, failure to abate previously cited violations, and unwarrantable failures to comply with safety and health standards," the agency said.
Two of the operations, Peachtree Ridge Mining's Eagle No. 1 and Oak Grove Resources' Oak Grove, were not included because the former was temporarily idled in July and the latter underwent an ownership transfer. Oak Grove will have a new review period due to the change.
"The operators that received the first letter in June knew they needed to make serious changes to improve their safety records, and change they did," said MSHA assistant secretary Richard Stickler.
"They have successfully and dramatically reduced their S&S violation rates - on average, by 50 percent."
However, the operations' work is not yet done.
"We strongly encourage these mine operators to continue to improve their compliance records until their mines are violation free, and we will continue to conduct our inspections in a rigorous fashion," Stickler said.
"Hopefully, they will serve as an example to the other 20 operators to improve their compliance rates."
The agency did not identify the new group of offending mines.
Federal regulations currently outline annual reviews for compliance, but MSHA officials said the process will increase to at least two screenings each year to identify operations that exhibit a potential pattern of violations under its criteria.
