The federal government has filed an objection to Alpha Natural Resources’ plan for emerging from Chapter 11 bankruptcy.

The federal government says the bankrupt coal miner’s plan doesn’t provide enough detail about how it will meet its environmental obligations. Alpha’s plan involves selling off the company’s core assets, including its mines in Wyoming, while holding onto less profitable mines that need to be reclaimed. The government says without any details about how Alpha plans to pay for that reclamation, it would be inappropriate for the bankruptcy court to approve the plan.

The government also notes in its objection that many of the mines Alpha plans to sell are on federal land, and argues that as a result, their sale requires federal approval. If the bankruptcy judge agrees with the government, that could throw a major wrinkle into Alpha’s restructuring.