House Natural Resources Committee Chairman Doc Hastings (R-Wash.) subpoenaed the Interior Department for a second time Friday over planned regulations aimed at curbing environmental damage from Appalachian coal mining.

The subpoena calls on the Interior Department to provide documents related to the planned rules by May 24 — it’s the second subpoena issued by the committee over the regulations in the last month.

House Republicans have taken aim at Interior’s plans to rework rules issued at the end of the George W. Bush administration that regulate the dumping of debris from mountaintop-removal coal mining into nearby waterways.

Committee Republicans, who authorized Hastings to issue the subpoena in a March party-line vote, have been investigating the planned regulations for more than a year.

Hastings said Friday that the Interior Department didn’t adequately comply with the first subpoena, issued on April 5.