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1/10/22, 10:32 AM State.co.us Executive Branch Mail-Re: HC#67752 Colowyo Mine Permit Technical Revision 152 <br /> We appreciate the additional information provided for our review. We, however, have additional questions and <br /> comments regarding the proposed undertaking. <br /> You noted that the technical revision consists of highwall mining to the northeast and southeast of the South Taylor Pit. <br /> While areas to the northeast of the mine appear to be previously disturbed, it remains unclear where the mine proposes <br /> to expand mining operations to the northeast of the Pit. Could you please clarify the extent of activities that will occur <br /> as a result of the undertaking including in this area to the northeast of the Pit? <br /> We understand that the proposed undertaking will involve subsurface mining activities and that the proposed <br /> undertaking will not result in surface mining. The proposed expansion of subsurface mining operations has the <br /> potential to affect cultural resources through the development of infrastructure (i.e. ventilation, access roads, and <br /> surface borings), temporary use areas, and reclamation activities as well as through reasonably foreseeable effects <br /> such as subsidence and ground vibrations. Similar types of underground operations in similar geological locations <br /> have resulted in subsidence that posed impacts to cultural resources including archaeological sites, rock art sites, and <br /> historic structures. <br /> The Advisory Council on Historic Preservation has previously commented on effects posed by subsidence in Colorado <br /> and noted that"subsidence, in general, with or without subsidence cracks, should be considered an effect on historic <br /> properties as it may include changes in the relationship of a property to its surroundings, including changes in its <br /> surface contours, topography, and erosional patterns. Following the same reasoning it appears that the opening and <br /> subsequent refilling of subsidence fractures, if they were to occur, should be considered at least an effect on <br /> archaeological sites." <br /> According to our records, portions of the mine expansion area have not been previously inventoried by cultural <br /> resource specialists and inventories that were completed were completed between 33 and 44 years ago. These <br /> inventories do not meet current standards and resources considered modern at the time would be considered historic <br /> by current standards. Aerial images show that a high frequency of the proposed expansion areas remain relatively <br /> undisturbed. In particular, the area to the west and south of the Pit remains relatively undisturbed. These areas show <br /> the potential for containing previously unidentified cultural remains. As a result, we recommended a cultural resource <br /> inventory. <br /> The provided map suggests that inventory was completed in a higher frequency of the area than we have in our files. <br /> Has the area recently been inventoried by a cultural resource specialist(s)? If so, could you please send us a copy of <br /> the results of the inventory(ies). If not, we continue to request the completion of a class III cultural resource inventory <br /> considering the reasons discussed above. <br /> Please let me know if you would like to discuss this over the phone or if you have any additional questions. <br /> Thank you, <br /> Matthew Marques <br /> Section 106 Compliance Manager <br /> History Colorado I State Historic Preservation Office <br /> 303.866.4678 1 matthew.marques@state.co.us <br /> 1200 Broadway I Denver, Colorado 80203 1 HistoryColorado.org <br /> Note: On Tuesday, October 19, 2021, Governor Jared Polis appointed Dawn DiPrince as the new Colorado State <br /> Historic Preservation Officer. The State Historic Preservation Officer has the delegated authority to represent the State <br /> of Colorado in carrying out the responsibilities specified in the National Historic Preservation Act, and in the regulations <br /> and administrative requirements established for implementation of the NHPA. Please join us in welcoming Ms. DiPrince <br /> to this new capacity. <br /> Under the Colorado Open Records Act(CORA),all messages sent by or to me on this state-owned email account may be subject to public disclosure <br /> https://mail.google.com/mail/b/ALGkd0y8elLUpphO-cw_b4dRu9Vtn4AuagQgJnHQChhDjud92irb/u/O/?ik=deb7fOcd20&view=pt&search=all&permthid=t... 2/3 <br />