The US Mine Safety and Health Administration said the four operations were issued letters of warning.

They were Ten-Mile Coal’s No. 4 mine in Harrison County, West Virginia; Pike Floyd Mining’s No. 3 mine in Pike County, Kentucky; Argus Energy WV’s Deep Mine No. 8 in Wayne County, West Virginia; and the non-coal Noranda Alumina Gramercy Facility in St James County, Louisiana.

MSHA also confirmed two operations in a non-producing status would be subject to PPOV action once they come back online. One of those is a coal mine, D&C Mining in Harlan County, Kentucky, and the other is Hecla Mining’s Lucky Friday mine in Shoshone County, Idaho.

Another 14 mines are under PPOV consideration. The agency is reviewing and verifying operators’ self-reported injury information for those complexes for accuracy.

This is just the third time MSHA has issued PPOV letters to operations since establishing its process to target mines with chronic violation problems in September 2010.

The outlines were originally designed to better identify mines subject to closure orders, including for serious issues such as failing to correct violations cited by MSHA, unwarrantable failures to comply with health or safety standards, failure to provide miners with required training and imminent dangers in the mine.

By using the process, the agency said it could better identify those operations that had not sufficiently improved compliance. This includes the issuance of a high number of significant and substantial, or S&S, violations, and targets those with an above-average injury severity measure.

A first screening in October 2010 resulted in 17 PPOV notices and one postponement letter to Massey Energy’s Upper Big Branch mine. Following a second screening review in October 2011, MSHA issued eight PPOV notices and three postponement letters at mines that were in non-producing status, inactive or abandoned.

"The revised potential pattern of violations program, along with other enforcement actions such as impact inspections, is making mines safer," assistant secretary of labor for mine safety and health Joseph Main said.

"The number of chronic violators meeting improved screening criteria has substantially dropped since we began implementing these criteria in 2010.”

Under the Mine Act, MSHA must screen for PPOV mines at least once a year, and those receiving warning notices are given the opportunity to implement corrective action programs.

The targeted mines must reduce their S&S rates to targets set by the agency. Operators that do not are subject to a pattern of violations filing and closure orders for all S&S violations under Section 104(e).

According to statistics from the agency’s PPOV actions in October 2010, four additional mines were put on notice after audits of 39 operations revealed inaccurately reported injury data.

The following year, federal officials found 28 additional mines that were subject to agency injury audits, though none received PPOV notices.

In April 2011, Bledsoe Coal’s Abner Branch Rider mine in Kentucky and New West Virginia Mining’s Apache mine in McDowell County were the first two mines ever to be subject to the full effect of PPOV enforcement action and 104(e) closure orders.

Main noted the number of mines meeting the audit trigger criteria had fallen significantly.

US operations that wish to monitor performance and compliance can use the agency’s online PPOV monitoring tool, available on its web site.

This tool uses the most recent compliance data available how a mine matches up with the initial screening criteria for a potential pattern of violations.

Data is refreshed to the system monthly.