Of those, 40 were Alpha Natural Resources operations formerly owned by Massey Energy.

Federal officials issued 158 total citations, 26 orders and three safeguards to nine US mines last month.

In a separate two-day blitz it handed down 225 violations to the former Massey mines in Appalachia.

The latter resulted from an earlier conveyor belt fire at Alpha’s Road Fork No. 51 mine in Wyoming County, West Virginia, another operation the producer acquired in its June 2010 takeover of Massey.

MSHA said no other similar violations were found during the subsequent 40 inspections.

Another inspection receiving significant attention was a May 16 visit federal officials made to K and D Mining’s No. 17 complex in Harland County, Kentucky, during crews’ second shift.

Among the 43 violations were 16 unwarrantable failure withdrawal orders.

Among other things, inspectors found a continuous mining machine in operation with the ventilation curtain rolled up and a 60ft-deep visible cloud of dust, inadequate water pressure and several inoperative sprays.

Withdrawal orders issued to K and D included combustible material accumulations on conveyor belts, defective and stuck belt rollers, a non-permissible pump starter in the return air shaft and inadequate electrical and on-shift examinations.

Unfortunately, the Kentucky operator was not the only operation found to have serious violations of safety and health standards.

MSHA visited Pay Car Mining’s No. 58 operation in McDowell County, West Virginia, on May 2 and issued nine citations, one unwarrantable failure citation and six unwarrantable failure orders during an evening shift impact inspection.

The review was the mine’s second after previously receiving a notice for a potential pattern of violations in November 2011.

While officials said the mine subsequently implemented a corrective action program and met the target criteria, it was still being monitored for a PPOV.

The most recent inspection revealed a failure to follow the mine’s approved mine ventilation plan on two working sections.

“Although the mine has a history of methane liberation, MSHA’s inspection team found insufficient ventilation in two mine entries, the last open crosscut of one mining mechanized unit section and the working faces and last open crosscut of another such section,” inspectors noted.

“The operator was issued five unwarrantable failure orders when no air movement could be measured using calibrated anemometers and, in one instance, the blades of the anemometer reversed, indicating that the ventilation was flowing in the wrong direction.”

Additionally, the ventilation line curtain was rolled up in the area of the continuous miner and 18ft of curtain across the break were missing.

Another working face’s ventilation also was not being provided because 27ft of curtain was missing.

MSHA issued citations to Pay Car for inadequate roof control, faulty electrical equipment and a conveyor belt and combustible materials accumulations.

“Mine operators know full well the consequences that occur when these kinds of conditions exist and we cannot and will not tolerate this type of noncompliance that endangers miners' lives and leads to potentially disastrous results,” MSHA assistant secretary of labor Joseph Main said.

“What goes on at some of these mines when MSHA is not there is of great concern and likely would not be detected if it were not for the special tactics MSHA employs.”

The agency’s special impact inspections began in force in April 2010, following the explosion at the Upper Big Branch mine where 29 workers were killed.

The push involved mines that warranted increased attention and enforcement by the agency due to a poor compliance history or particular compliance concerns.

These included high numbers of violations or closure orders; indications of operator tactics, such as advance notification of inspections that prevented inspectors from observing violations; frequent hazard complaints or hotline calls; plan compliance issues; inadequate workplace examinations; a high number of accidents, injuries or illnesses; fatalities; and adverse conditions such as increased methane liberation, faulty roof conditions and inadequate ventilation.

Since April 2010, MSHA has conducted 452 impact inspections which have resulted in a total of 8106 citations, 811 orders and 32 safeguards.