The Colorado Division of Reclamation, Mining and Safety has regulated operations at the limestone quarry since it was first opened by Mid-Continent Resources in 1982. The quarry continues to be recognized by the state agency as the Mid-Continent Quarry.

Prior to the 2023 rockslide, permit enforcement by the Colorado Division of Reclamation, Mining and Safety (DRMS) has been limited to quarterly and annual reporting.

After the rockslide incident, which occurred on Jan. 18, 2023, DRMS stepped up its enforcement authority. Agency staffers have provided helpful information about state enforcement actions and insights into  U.S. Mine Safety and Health Administration enforcement actions.

DRMS rockslide inspections

DRMS mine inspectors Amy Yeldell and Dustin Czapla visited the quarry on Jan. 23, 2023, and produced a detailed report describing the slide.

Yeldell and Czapla noted the differences in the highwall angles and observed water seeping out between the two upper layers of limestone. They also saw workers loading previously processed rock onto trucks, but noted that no work was taking place on the production bench or in the crushing mill.

Yeldell and colleagues prepared an extensive report on their observations. See RESOURCES at right to read their report and cover letters.

Notice of Possible Violation

DRMS issued a notice of “Possible Violation” on Jan. 25, 2023, alleging that RMI’s mining methods “resulted in destabilized highwalls and failed to control erosion and sedimentation on the affected lands.”

The inspection report also noted, “Mitigation of the rockslide to stabilize the highwall and reclaim the surrounding area will require an impact to areas outside of the affected lands.”

The notice required RMI to appear before the Colorado Mined Land Reclamation Board for a formal hearing, set for April 19. (The board is an appointed panel that considers permit violations and imposes penalties and remedies.)

Stipulated Agreement

Prior to the hearing, DRMS staff negotiated a Stipulated Agreement with RMI in lieu of holding the formal public hearing. Conditions are:

  • RMI acknowledges “awareness” of its failure to protect areas outside its permit boundary from slides or damage.
  • RMI must seek a technical revision to its permit to establish a long-term geologic monitoring and stability plan. The application must include a geotechnical stability plan prepared by an accredited engineering firm.
  • A cease-and-desist order is imposed on the production bench until a technical revision to RMI’s mining permit is approved by DRMS.
  • RMI must coordinate its efforts with MSHA and BLM to ensure that monitoring and stability analysis and plans meet their requirements.
  • Any disturbance proposed for lands outside RMI’s state mining permit boundary will require a permit amendment.
  • Failure to comply may lead to an enforcement hearing before the MLRB.

Technical Revision process

The Technical Revision process began in October 2023, after RMI submitted its Rock Failure Analysis and Stability Report. (Learn about the report here.)

A Technical Revision (TR) is handled directly between DRMS staff and the mine operator. Public comment is not a part of this process, and Colorado Mined Land Reclamation Board (MLRB) action is not needed to finalize the TR.

RMI submitted its Technical Revision proposal in November 2023, which led DRMS to ask further questions. (See links at right for these interim documents.)

RMI submitted its last updates on March 5, 2024. The Colorado DRMS staff approved RMI’s Technical Revision on April 1, 2024.

Permit Amendment

RMI will face a higher-level Permit Amendment if it seeks an expansion of acreage beyond current permit boundaries. The permit amendment process includes public comment and requires MLRB action to finalize.

Reclamation bond

DRMS holds a reclamation bond for the RMI quarry of $336,000. The agency expects to increase the bond to account for inflation in the coming months. Additional bond money could be required if the agency conducts an amendment process.

Post-rockslide Exclusion Zone map prepared by Colorado Division of Reclamation, Mining & Safety, May 2023
Note: Map is based on a pre-rockslide aerial image from Google Earth.
  • Purple line: Colorado DRMS mining permit boundary (does not align with BLM or Garfield County permit boundaries)
  • Red area: Slide exclusion area
  • Light blue line: Production benches / highwalls
  • Dark blue line: Processing bench
  • Green area: Mill bench