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Public Notice: Cyprus Tohono Corporation; Public Comment, Informational Session and Public Hearing on Proposed Clean Air Act Tribal Minor New Source Review (NSR) Permit

Publish Date: 02/28/2019


On February 28, 2019, the United States Environmental Protection Agency, Region 9 (EPA) announced a proposed action with a comment period that was scheduled to close on April 3, 2019. We are extending the comment period until May 3, 2019. EPA is proposing to issue a synthetic minor permit for use in Indian Country pursuant to the Clean Air Act (CAA) Federal Indian Country Minor New Source Review (NSR) program for new and modified minor sources, codified at 40 C.F.R. 49.151 through 49.165 to the Cyprus Tohono Corporation (CTC), for a mining operation (CTC Mine or Facility) located on tribal land of the Tohono O’odham Nation (Nation). The proposed permit would authorize construction of new equipment and operation of new and existing equipment (Project), subject to enforceable emissions limitations to restrict the Source’s potential to emit to levels below major source thresholds. The Facility is located 31 miles southwest of Casa Grande, Arizona, at the cross of Highway 15 and the Pima and Pinal County boundary. The address for CTC is P.O. Box 15009, Casa Grande, AZ 85130-5009. CTC’s Operations Manager is Raymond Romero, (520) 361-3111.

Proposed activities include: 1) open pit mining (including drilling, blasting, loading, hauling, and unloading of ore and non-ore); 2) ore crushing & conveying; 3) heap leaching; 4) solvent extraction/electrowinning; 5) fuel burning equipment; 6) storage tanks; 7) stockpiles subject to wind erosion; and 8) support traffic. The proposed permit limits emissions from these activities and accompanying equipment through control technology requirements that include fabric filters, suppression techniques, shrouds and enclosures, work practice standards, and fugitive dust control planning. The proposed permit also includes conditions for existing emergency generators at the Facility. Under the proposed controls and associated emissions limitations, the Facility will be a synthetic minor source of particulate matter (PM), PM less than or equal to 10 μm in diameter (PM10), and PM less than or equal to 2.5 μm in diameter (PM2.5). EPA’s proposed permit also includes applicable requirements of the New Source Performance Standards and National Emission Standards for Hazardous Air Pollutants. This action will result in non-fugitive emissions increases of the following pollutants: 11.23 tons per year (tpy) of PM, 11.12 tpy of PM10, 11.09 tpy of PM2.5, 7.39 tpy of carbon monoxide (CO), 7.97 tpy of nitrogen oxides (NOx), 0.62 tpy of sulfur dioxide, and 3.78 tpy of volatile organic compounds (VOC). More information on the emission changes and limitations associated with this draft permit can be found in Sections 5 and 6 of the technical support document for this action.

The draft permit action also includes our proposed decision under section 106 of the National Historic Preservation Act that the issuance of this minor NSR permit will have no effect on historic properties.

Draft Permit Review

A copy of the draft permit prepared by EPA, the technical support document for the draft permit, and all supporting materials are available for review by the public through the online docket listed above. If you have trouble accessing materials, please contact LaWeeda Ward at

Additionally, key documents (such as the draft permit and our technical support document) may also be viewed in person at the following locations:

Sif Oidak District Office
Address: Indian Route 15 Milepost 27, North Komelik Community
Phone: (520) 361-2360 2.

U.S. EPA Region 9 Office (address at right)
Monday through Friday, from 9:00 a.m. until 4:00 p.m., excluding federal holidays. Due to building security procedures, please call La Weeda Ward at (213) 244- 1812 at least 48 hours in advance to arrange a visit.

National Historic Preservation Act

Section 106 of the National Historic Preservation Act requires EPA to consider the effects of its permit actions on properties listed in or eligible for inclusion in the National Register of Historic Places (NRHP). In accordance with Section 106 and the implementing regulations at 36 CFR 800, EPA is also seeking public comment on the proposed permit action’s potential to directly (e.g., physically) and indirectly (e.g., visually) affect historic properties, and information on potential adverse effects to historic properties and/or traditional cultural properties (e.g., archeological sites).

With regard to the proposed Project, the Nation’s Tribal Historic Preservation Officer (THPO) requested that CTC hire a consultant (WestLand Resources) to revisit the sites recorded during previous surveys, and if still in existence, assess their present condition and ensure that they were accurately plotted with modern GPS equipment. Additionally, at the THPO’s request, CTC also hired WestLand Resources to complete a cultural landscape study to be utilized with the resurvey to evaluate impacts to the cultural landscape. WestLand was able to locate 71 of the 73 previously known sites and located one previously unrecorded site. The remaining two sites could not be relocated at their originally plotted locations. Based on site conditions, WestLand recommends eight sites eligible for inclusion in the NRHP and 66 sites ineligible. In a June 4, 2016 letter to CTC, the Nation THPO stated that it concurs with recommendations made in these two reports and accepts these reports as completing the Section 106 consultation with the following provisions:

  1. The Ramada Site, AZ AA:5:151 (ASM), represents a multicomponent cultural resource site that includes a prehistoric flaked stone scatter and a historical Tohono O'odham saguaro fruit-harvesting camp with a ramada and associated historical period artefacts. This site will be preserved in place with a fenced 100 ft. buffer around the historic ramada portion of the site.
  2. Site AZ AA:5:182 (ASM), represents a lithic scatter-procurement site that contains over 2,000 flaked stone artefacts, numerous chipping stations and a concentration of ceramic sherds. This site was recommended as eligible for the National Register of Historic Places. This site was never tested, and no data recovery was ever completed. A portion of this site is located in the mine expansion area and a portion outside the mine expansion area. This site area will be fenced with a 100 ft. buffer and the boundary of the mine expansion area will be altered to place this site outside the mine expansion area.
  3. The boundary of the waste development dump will be fenced so any sites located along the boundary will be protected and outside the fence. EPA’s summary of the Section 106 compliance efforts is detailed in the report “Cultural Resources Summary Report under the National Historic Preservation Act – Cyprus Tohono Mine Project,” available in the docket for this proposed action.

Public Informational Meetings

To facilitate opportunities for interested persons to provide informed oral presentations at the public hearing describe below, EPA will hold two public informational meetings for the purpose of providing interested parties with additional information and an opportunity to obtain answers to questions about the proposed Project. The dates, times and locations of the public information meetings are as follows:

Date: April 2, 2019
Time: 5:00 PM – 6:00 PM
Location: Sif Oidak District Council Office Conference Room #2 Indian Route 15 Mile Post 27 Casa Grande, Arizona 85230

Date: April 3, 2019
Time: 5:00 PM – 6:00 PM
Location: Sells Recreation Center Multipurpose Room Main Street Sells, Arizona 85634

Public Hearing

Pursuant to 40 CFR 49.157(c), EPA also intends to hold two public hearings to provide the public with further opportunity to comment on today’s proposed Tribal Minor New Source Review permit. At these public hearings, any interested person may provide written or oral comments and data pertaining to today’s proposed permit. The dates, times and locations of the public hearings are as follows:

Date: April 2, 2019

Time: 6:30 PM – 8:00 PM
Location: Sif Oidak District Council Office Conference Room #2 Indian Route 15 Mile Post 27 Casa Grande, Arizona 85230

Date: April 3, 2019
Time: 6:30 PM – 8:00 PM
Location: Sells Recreation Center Multipurpose Room Main Street Sells, Arizona 85634

If you are a person with a disability and require a reasonable accommodation for the above events, please contact Philip Kum ( or at (415) 947-3566. If possible, requests should be made at least five business days in advance of the event to ensure proper arrangements can be made.

Final Action

Before taking final action on the draft permit, EPA will consider all written comments submitted during the public comment period as well as comments presented orally or in writing at the public hearings. EPA will send notice of our final permit decision to each person who submitted comments and contact information during the public comment period or requested notice of the final permit decision. EPA will summarize the contents of all substantive comments and provide written responses in a document accompanying EPA’s final permit decision. EPA’s final permit decision will become effective 30 days after the service of notice of the final permit decision, unless:

  1. A later date is specified in the permit; or
  2. Review of the final permit decision by EPA’s Environmental Appeals Board (EAB) is requested under 40 CFR 49.159(d); or
  3. EPA elects to make the permit effective immediately upon issuance if no comments request a change in the draft permit or a denial of the permit.

Appeals to the Environmental Appeals Board (EAB)

In accordance with 40 CFR 49.159, within 30 days after EPA’s final permit decision has been issued, any person who filed comments on the proposed permit or participated in the public hearing may petition the EAB to review any condition of the permit decision. Any person who failed to file comments or to participate in the public hearing may petition for administrative review only to the extent that the changes from the draft to the final permit or other new grounds were not reasonably ascertainable during the public comment period. The 30-day period within which a person may request review under this section begins with service of notice of the final permit decision, unless a later date is specified in that notice. A petition to the EAB is, under Section 307(b) of the Act, a prerequisite to seeking judicial review of the final agency action. For purposes of judicial review, final agency action occurs when we deny or issue a final permit and agency review procedures are exhausted. A final permit decision will be issued by the EPA following an appeal to the EAB as specified in 40 CFR 49.159(d)(8).

Additional Information

If you have questions, or if you wish to obtain further information, please contact Laweeda Ward at (213) 244-1812, via email at, or at the mailing address above. If you would like to be added to our mailing list to receive future information about this draft permit decision or other permit decisions issued by EPA Region 9, please contact the EPA at the address listed above or send an email to

*Please bring the foregoing notice to the attention of all persons who would be interested in this matter.*

Applicant or Respondent

Cyprus Tohono Corporation (CTC)
P.O. Box 15009
Casa Grande, AZ 85130-5009

Docket Number: