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Underground Injection Control (UIC)

Public Notice: Public Hearing and Extended Public Comment Period; Excelsior Mining Arizona Inc's Gunnison Copper Project

Publish Date: 01/22/2018


Public Hearing Scheduled and Comment Period Extended Through February 27, 2018

The United States Environmental Protection Agency, Region 9 (EPA) is soliciting public comments on its proposal to issue a Class III Underground Injection Control (UIC) Area Permit for Excelsior Mining Arizona, Inc. (Excelsior) to construct and operate an in-situ copper recovery (ISCR) facility known as the Gunnison Copper Project (Project) near the Town of Willcox, Arizona. The wellfield is proposed to be constructed within Township 15 South, Range 22 East, Section 36 and Township 15 South, Range 23 East, Section 31, in Cochise County, Arizona.

The Class III UIC Area Permit, if issued, would authorize Excelsior to inject a dilute sulfuric acid solution into the copper orebody and recover copper-laden solution for the purpose of producing copper. EPA proposes to issue the permit and the authorization to construct, test, and inject at the proposed Project site for twenty (20) years, followed by aquifer restoration and closure operations for three (3) years and a post-rinsing monitoring period of five (5) years.

The injection interval would be the copper oxide orebody present within the Oxide Bedrock Zone at the Project site. It is a bedrock formation that was formed as coatings on rock fractures and as vein fill that is approximately 400 to 1,400 feet below ground surface. The wellfield area is approximately 192 acres in areal extent. After completing a thorough technical review of all submitted information, as well as the operational standards, monitoring requirements, and the geologic setting, EPA has made a preliminary determination that the activities under the draft Class III UIC Area Permit (draft Permit) are protective of underground sources of drinking water (USDWs) as required by the Safe Drinking Water Act (SDWA).

EPA has made a preliminary determination to issue a Class III UIC Area Permit to Excelsior pending this public notice and comment period. This action is being taken as provided by Part C of the SDWA and pursuant to Title 40 of the Code of Federal Regulations (CFR) Parts 124, 144, 146, and 147.

Final Permit Decision and Permit Appeal Process

After the close of the extended public comment period, EPA will issue a response to comments and a final permit decision pursuant to 40 CFR §124.15(a) and will notify all commenters regarding this decision. A written transcript of the public hearing will also be made available to the public. If comments are filed which request a change in the draft Permit, the final decision shall become effective no sooner than thirty (30) days after the service of the notice of decision. Within thirty (30) days after the final permit decision has been issued, any person who filed comments on the draft Permit, participated in any public hearing on this matter, or takes issue with any changes in the draft Permit, may petition the Environmental Appeals Board to review any condition of the permit decision. Commenters are referred to 40 CFR §124.19 for procedural requirements of the permit appeal process.

Applicant or Respondent

Excelsior Mining Arizona, Inc.
Concord Place, Suite 300
2999 North 44th Street
Phoenix, AZ 85018

Permit #: R9UIC-AZ3-FY16-1

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