Pima County on Thursday joined Democratic U.S. Representatives Ron Barber and Raul Grijalva in formally requesting the U.S. Forest Service to require substantial revisions to the Draft Environmental Impact Statement for the proposed Rosemont copper mine.
“A new draft DEIS and public comment period are warranted for this project,” Pima County Administrator Chuck Huckleberry said in an Oct. 25 letter to Coronado National Forest Supervisor Jim Upchurch.
Last July, Rosemont Copper Company submitted revised plans to the Forest Service for the mile-wide, half-mile deep open pit copper mine it wants to build in the Santa Rita Mountains on the Coronado National Forest south of Tucson. Rosemont Copper is owned by Vancouver, B.C.-based Augusta Resource Corporation.
Rosemont, in July and September letters to the Forest Service, stated the revisions to its mining plan included in the DEIS it submitted last year and for which the public comment period is now closed, are minor and do not require extensive analysis such as a supplemental or new DEIS.
Huckleberry, however, said Rosemont’s revisions are “substantial changes” to the proposed mine, which under federal law must be reviewed either through a supplemental or new DEIS.
The substantial changes cited by Huckleberry include:
* An additional 80 million tons more of ore will be removed from the mining pit.
* The pit is “much larger” than what was proposed in the DEIS and will intersect the crest of the Santa Rita Mountains.
* The removal of nine miles of under-drains from beneath the waste rock and tailings piles.
* The addition of a proposed compliance dam.
* The deletion of the heap leach pad for processing approximately 70 million tons of oxide ore that would be treated as waste rock, raising the potential of acid drainage.
Huckleberry also states the Forest Service has the responsibility to “rigorously explore” Rosemont’s proposal to have a much higher than needed high voltage power line extended to the mine site.
“The ability to draw more water and power needed to process additional ore with the larger line needs to be evaluated under cumulative impacts,” Huckleberry stated.
Rosemont wants to construct a 138 kV transmission line that, according to Huckleberry, has excess capacity of “several hundred megawatts” of power, “adequate to support all four mines in the affected environment.”
In addition to the Rosemont claim, Augusta owns three other mining claims in close proximity: Broadtop Butte, Copper World and Peach-Elgin.
The extra power, and Rosemont’s ability to pump unlimited amount of groundwater, raises concerns that the company is installing the infrastructure necessary to expand mining to the three other claims.
Augusta has already stated in regulatory filings that Broadtop Butte could “potentially be added as a satellite development” to the Rosemont mine.
Huckleberry also noted that Rosemont’s plans to abandon underdrains and the addition of a new compliance dam “will trigger a significant amendment of Rosemont’s Aquifer Protection Permit (APP).”
The state Department of Environmental Quality issued Rosemont an APP last spring. The permit, however, has been appealed by mine opponents.
Huckleberry said the APP as issued falls short in protecting the environment because it does not regulate the pit lake that will be created after the pit intersects the groundwater table.