Federal regulators have expanded their study into the permitting of huge mountaintop removal strip mines in West Virginia, officials said last week.

The U.S. Office of Surface Mining broadened the investigation so that it focuses more on questions about whether state officials have abused a key mine reclamation rule.

OSM officials said they hope additional work by their inspectors will provide a clearer understanding of the federal "approximate original contour" or AOC reclamation standard.

"My goal is to make it clear whether AOC is being applied correctly," said Roger Calhoun, director of the Charleston OSM field office.

OSM launched the special study in February after citizen complaints about mountaintop removal mines.

Old-time strip mines chipped coal away from hillsides. Mountaintop removal mines shave off entire hilltops to reach valuable low-sulfur coal underneath. In mountaintop removal, rock and earth removed to reach coal are often dumped in streams in waste piles called valley fills.

Normally, all strip mines must be returned to their approximate original contour. They must be reclaimed so that post-mining land closely resembles the general surface configuration of pre-mining land.

Mountaintop removal can be permitted only under a variance that allows mine operators to leave land flat, or with gently rolling hills, instead of steep Appalachian slopes. Under federal law, this variance can only be granted if mine operators have specific plans to develop flat land for schools, businesses, public parks or other improvements.

Originally, OSM planned only to examine whether mines that were granted the mountaintop removal variance to AOC reclaimed their land for the promised developments.

Now, the agency will also look at whether dozens of mountaintop removal mines were improperly permitted without the AOC variance.

As part of the study, OSM investigators will examine some of those mines and try to determine if they are really being reclaimed to meet the AOC standard or whether they should have been required to obtain a variance.

Federal regulators have expanded their study into the permitting of huge mountaintop removal strip mines in West Virginia, officials said last week.

The U.S. Office of Surface Mining broadened the investigation so that it focuses more on questions about whether state officials have abused a key mine reclamation rule.

OSM officials said they hope additional work by their inspectors will provide a clearer understanding of the federal "approximate original contour" or AOC reclamation standard.

"My goal is to make it clear whether AOC is being applied correctly," said Roger Calhoun, director of the Charleston OSM field office.

OSM launched the special study in February after citizen complaints about mountaintop removal mines.

Old-time strip mines chipped coal away from hillsides. Mountaintop removal mines shave off entire hilltops to reach valuable low-sulfur coal underneath. In mountaintop removal, rock and earth removed to reach coal are often dumped in streams in waste piles called valley fills.

Normally, all strip mines must be returned to their approximate original contour. They must be reclaimed so that post-mining land closely resembles the general surface configuration of pre-mining land.

Mountaintop removal can be permitted only under a variance that allows mine operators to leave land flat, or with gently rolling hills, instead of steep Appalachian slopes. Under federal law, this variance can only be granted if mine operators have specific plans to develop flat land for schools, businesses, public parks or other improvements.

Originally, OSM planned only to examine whether mines that were granted the mountaintop removal variance to AOC reclaimed their land for the promised developments.

Now, the agency will also look at whether dozens of mountaintop removal mines were improperly permitted without the AOC variance.

As part of the study, OSM investigators will examine some of those mines and try to determine if they are really being reclaimed to meet the AOC standard or whether they should have been required to obtain a variance.

Calhoun said Thursday that his agency had added nine more permits to the original list of 10 that OSM was going to study. He said the study is still on schedule for completion in mid-August.

Originally, OSM officials also said they would not - regardless of the study outcomes - try to come up with a more concrete definition of approximate original contour.

Calhoun said that OSM may decide to look at that issue after all.

"When we're done, this may be something so specific to West Virginia that DEP the state Division of Environmental Protection might want to take the lead on developing some specific guidance," Calhoun said.

Meanwhile, coal industry lobbyists have blasted OSM for its involvement in a related controversy over a post-mining land use popular with many of the state's larger coal operators.

OSM has been investigating the state's permitting of mountaintop removal AOC variances for mines that propose to reclaim the land for "fish and wildlife habitat and recreation lands."

Under current federal rules, that post-mining land use is not allowed for mountaintop removal mines.

In a June 8 letter to OSM Director Kathy Karpan, West Virginia Coal Association President Bill Raney said that, in not approving the land use, OSM is "relying on the longstanding sympathies and biases of several of its employees, rather than on a sound reading of the law.

"Although personnel within OSM's Charleston field office have, from time to time, informally expressed their displeasure with the use of this post-mining land use as the basis for an AOC variance, to our knowledge, OSM has never taken any oversight action with respect to such operations notwithstanding its long knowledge of their existence," Raney wrote.

Raney attached a legal paper and court decision that he says backs up the coal industry argument that fish and wildlife habitat can be used for mountaintop removal AOC variances.

In his letter, Raney also asked that OSM reopen a public comment period on a state Division of Environmental Protection proposal to add fish and wildlife habitat as an approved AOC variance post-mining land use. Calhoun declined comment on Raney's letter.