• Concerning regular quarterly inspections, MSHA inspectors "did not document the work they performed or the basis for their conclusions in addressing these responsibilities."

• MSHA "lacked guidance on appropriate non-rescue activities" when it allowed media representatives into the mine during the rescue effort.

The mine is owned by Murray Energy, with headquarters in Cleveland, and Intermountain Power Agency, a Utah cooperative that generates electricity for communities in Utah and California. Crandall Canyon was operated by Genwal Resources Inc., a partially owned subsidiary of UtahAmerica Energy, which is owned by Murray Energy, says the report.

Crandall Canyon miners were using a technique called pillar extraction, which the report says is a high-risk underground mining technique to increase coal recovery. In the process, also called retreat mining, miners remove support pillars of coal as they retreat toward the entrance, allowing the roof to collapse behind them. The deeper the mine, the more pressure from the overburden and the more likely for coal bounces or bumps.

Despite the risks, MSHA "could not show that it did everything appropriate to ensure the Crandall Canyon plan was sufficient ... did not assure that its districts had an adequate process for reviewing and approving the plan."

MSHA is supposed to require that each of its district's Standard Operating Procedures address 20 minimum controls.

"District 9 did not address 12 of these 20 controls," the Office of the Inspector General adds.

At one point, a first-year roof control engineer ran a computer model that identified inconsistencies in a proposed plan. Later, an MSHA official met with the operator and, according to an MSHA letter, resolved the differences in favor of the mine operator's engineering result.

MSHA did not consider findings of inspections by another federal agency, the Bureau of Land Management. BLM land was leased for the mine, and BLM inspects mines on its property at least four times a year.

"I have been concerned about pulling pillars in this environment with mining a narrow block with little coal barriers to mined-out blocks on both sides," a BLM inspector wrote on July 12, based on his inspection of the North Barrier on Feb. 27, 2007.

"So far no inordinate pillar stresses have been noted, though thing(s) should get interesting soon."