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PART 71 FEDERAL OPERATING PERMIT

DRAFT STATEMENT OF BASIS

ASARCO 

Mission Mine Complex - San Xavier 

Permit No. TO-ROP 10-02

1. Facility Information 

a. Permittee

ASARCO 

P.O. Box 111 

Sahuarita, AZ 85629 

b. Facility location

4201 W. Pima Mine Road 

Sahuarita, AZ 85629 

c. Contact information

Facility Contact: Jamie Ekholm (520) 393-4671 

Responsible Official: Richard Rhoades (520) 648-2500 

d. Description of operations, products

The ASARCO Mission Complex mines and processes copper sulfide ore. Mining 

activities that generate emissions include metallic mineral processing activities 

such as crushers, screens, and belt transfer points, as well as drilling, hauling, and 

vehicle travel. 

e. Jurisdiction and permitting history

This facility was initially constructed in the 1961. Since the mine is located 

partially in Indian Country and partially on State land, permitting authority is 

shared by EPA and the Pima County Department of Environmental Quality 

(DEQ). DEQ issues construction and title V permits for the portion of this facility 

which is located on state land, where crushing, screening and transferring of ore 

takes place. EPA’s has jurisdiction over the equipment and activities located on 

the reservation of the Tohono O’odham Nation, which include drilling, hauling, 

and vehicle travel. These mining activities on the reservation have not previously 
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required a preconstruction permit from EPA. There are no Clean Air Act 

(“CAA”) applicable requirements that apply to these activities, and actual 

emissions are well below the title V major source threshold. However, because 

the portion of the mine on the reservation is part of a major source subject to title 

V permitting, it must obtain a separate title V permit from EPA in addition to the 

title V permit issued by DEQ. EPA issued the initial title V permit for the portion 

of the facility on the reservation on September 5, 2000, and the first renewal 

permit on December 16, 2005. 

f. Emission-generating units and activities

Table 1. Emission-generating units and activities 

Emission 

Unit I.D. 

No.

Unit Description Associated 

Control 

Equipment

SXFMA San Xavier Fugitive Emissions Mining Activities 

(hauling, dozing, grading, land clearing, vehicle 

travel, and unloading) 

n/a 

g. Potential to emit (in tons/year) 

 

Potential to emit (“PTE”) means the maximum capacity of a facility to emit any 

air pollutant regulated under the CAA under its physical and operational design. 

Any physical or operational limitation on the maximum capacity of SRMG to 

emit an air pollutant, including air pollution control equipment and restrictions on 

hours of operation or on the type or amount of material combusted or processed, 

shall be treated as part of its design if the limitation is enforceable by EPA. PTE 

is meant to be a worst case emissions calculation and is used in many, though not 

all, cases to determine the applicability of federal requirements. Actual emissions 

are typically lower than PTE. 

 

All emissions from the portion of the facility on the reservation are fugitive. 

Under the Part 71 regulations, fugitive emissions from a stationary source are not 

considered when determining whether the source is major unless the source 

belongs to one of the 27 source categories listed in the definition of “major 

source” (40 CFR Part 71.2). ASARCO’s Mission Mine Complex is not in one of 

the listed source categories. Table 2 shows the mines PTE of fugitive emissions; 

but these emissions do not count when determining whether the mine is a major 

source. 
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Table 2. Fugitive Emissions from Mining Activities on Tohono O’odham Nation 

Reservation (in tons/year) 

Unit NOx VOC SO2 PM10 CO Lead HAP

SXFMA 135.2 < 1 18.4 2823.3 490.4 < 1 < 1 

The point source (i.e., non-fugitive) emissions from the portion of the mine in 

Pima County, provided by PDEQ, are presented in Table 3. These emissions 

make the mine a major source for the purposes of the title V program. 

Table 3. Potential to Emit From Point Sources on Pima County Portion of the 

Mine (in tons/year) 

NOx VOC SO2 PM10 CO HAP 

246 < 100 < 100 300 314 < 10/25 

2. Tribe Information 

a. General

The reservation of the Tohono O’odham Nation is located in Pima County, 

Arizona and covers more than 2.8 million acres over four non-contiguous areas. 

The San Xavier District of the reservation, which covers approximately 71,000 

acres, currently is home to more than 2,000 people. 

b. Local air quality and attainment status

The San Xavier District of the Tohono O’odham Nation is currently designated as 

attainment or unclassifiable for all pollutants for which a National Ambient Air 

Quality Standard (“NAAQS”) has been established. 

3. Applicable Requirements 

The portion of the mine on the reservation is currently not subject to any existing applicable 

federal CAA programs, such as the Prevention of Significant Deterioration (“PSD”), New Source 

Performance Standards (“NSPS”), National Emission Standards for Hazardous Air Pollutants 

(“NESHAP”), or the acid rain program under Title IV of the CAA. Further, the portion of the 

mine covered by the Part 71 permit is not subject to the Pima County State Implementation Plan 

(“SIP”). Therefore, this portion of the mine is not subject to any substantive requirements that 

control emissions under the CAA. 
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EPA recognizes that, in some cases, sources of air pollution located in Indian country are subject 

to fewer requirements than similar sources located on land under the jurisdiction of a state or 

local air pollution control agency. To address this regulatory gap, EPA has promulgated a 

Federal Implementation Plan for preconstruction review of major sources in nonattainment areas 

and of minor sources in both attainment and nonattainment areas, which became effective on 

August 30, 2011. (76 FR 38748, July 1, 2011) These programs, codified in Parts 49 and 51 of 

the Code of Federal Regulations, establish pre-construction review requirements for sources that 

would be incorporated into Part 71 permits. The facility is not currently constructing new 

emission units or modifying existing emission units in the portion of the facility regulated by 

EPA. In the future, if the facility constructs new emission units or modifies existing emission 

units, it may be required to obtain a permit from EPA prior to construction, depending on the 

amount of the emission increase, if any, associated with the project. 

4. Inapplicable Requirements 

The facility occasionally operates three diesel-fired generators on the reservation. These engines 

are parts of motivators, which are mounted on flatbed trailers and used to move shovels from 

location to location at the Mission Complex facility, including the portion permitted by EPA. 

The primary purpose of a motivator is to provide power to propel a shovel. The motivator 

attaches to, powers, and propels the shovel as the shovel moves throughout the facility. 

EPA regulates diesel-fired engines in the Standards of Performance for New Stationary Sources 

(NSPS) for Stationary Compression Ignition Internal Combustion Engines (40 CFR Part 60, 

Subpart IIII), and the National Emissions Standards for Hazardous Air Pollutants (NESHAP) for 

Stationary Reciprocating Internal Combustion Engines (40 CFR Part 63, Subpart ZZZZ). 

Subpart IIII defines “stationary internal combustion engine” (§60.4219) as (emphasis added): 

...any internal combustion engine, except combustion turbines, that converts heat energy 

into mechanical work and is not mobile. Stationary ICE differ from mobile ICE in that a 

stationary internal combustion engine is not a nonroad engine as defined at 40 CFR 

1068.30 (excluding paragraph (2)(ii) of that definition), and is not used to propel a motor 

vehicle or a vehicle used solely for competition. Stationary ICE include reciprocating 

ICE, rotary ICE, and other ICE, except combustion turbines. 

The definition of “stationary reciprocating internal combustion engine (RICE)” in NESHAP 

Subpart ZZZZ contains language identical to the italicized language above. The definition of 

nonroad engine in §1068.30 is an internal combustion engine that meets any of three specified 

criteria. The engines used on the motivators meet two of the three criteria listed in §1068.30: 

• It is (or will be) used in or on a piece of equipment that is intended to be propelled while 

performing its function (such as lawnmowers and string trimmers). 

• By itself or in or on a piece of equipment, it is portable or transportable, meaning 

designed to be and capable of being carried or moved from one location to another. 
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Indicia of transportability include, but are not limited to, wheels, skids, carrying handles, 

dolly, trailer, or platform. 

However, the definition excludes any engine that “remains or will remain at a location for more 

than 12 consecutive months... A location is any single site at a building, structure, facility, or 

installation.” EPA has determined that engines, such as the engines on ASARCO’s motivators, 

that are located at a facility but moved around the facility, are not stationary engines unless they 

remain at the same location within the facility for more than 12 months.

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 Thus the three engines 

used in the motivators meet the definition of nonroad engines 40 CFR 1068.30 and are not 

subject to NSPS or NESHAP requirements, as long as they do not remain at one location within 

the facility for more than 12 months. 

We note that there is an exception to the nonroad definition for engines that replace stationary 

engines. Subsection (2)(iii) of the nonroad engine definition provides that, “[a]ny engine (or 

engines) that replaces an engine at a location and that is intended to perform the same or similar 

function as the engine replaced will be included in calculating the consecutive time period.” 

Therefore, “[p]ortable engines that replace existing stationary engines at the same location on a 

temporary basis and that are intended to perform the same or similar functions are considered 

stationary engines.” 2In this case, Asarco has indicated that its motivators are occasionally used 

for power generation purposes during power interruptions. If a motivator is used to temporarily 

replace an existing stationary engine at the facility, then it would be considered a stationary 

engine. However, it appears unlikely that the motivators are used for this purpose on the San 

Xavier portion of the facility, since there are no stationary engines in this part of the facility. 

ASARCO requested that EPA grant permit shields for NSPS Subparts IIII and JJJJ (which 

applies to spark ignition engines) and NESHAP Subpart ZZZZ. Sources may request, and 

permitting authorities may grant at their discretion, permit shields under two circumstances. A 

permitting authority may grant a shield from an applicable requirement if it has been 

incorporated into the permit, or if the permitting authority determines that a requirement is not 

applicable to the source. In light of our explanation that the engines are nonroad engines and 

thus not regulated by NSPS or NESHAP, and the fact that the engines are not part of the 

stationary source and will not be listed in the permit, EPA does not believe it is necessary to 

further clarify the inapplicability of NSPS and NESHAP requirements by granting the requested 

permit shields. 

5. EPA Authority

Title V of the CAA requires that EPA promulgate, administer, and enforce a Federal operating 

permits program when a State, local, or Tribal agency does not submit an approvable program 

within the time frame set by title V or does not adequately administer and enforce its EPA-

 

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See Response to Public Comments on Proposed National Emission Standards for Hazardous Air Pollutants for 

Existing Stationary Reciprocating Internal Combustion Engines Located at Area Sources of Hazardous Air Pollutant 

Emissions or Have a Site Rating Less Than or Equal to 500 Brake HP Located at Major Sources of Hazardous Air 

Pollutant Emissions (Aug. 10, 2010) , available at http://www.epa.gov/ttn/atw/rice/existing_si_rice_rtc.pdf

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Standards of Performance for Stationary Compression Ignition and Spark Ignition Internal Combustion Engines, 

76 Fed. Reg. 37954, 37958-37959 (June 28, 2011). 
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approved program. On July 1, 1996 (61 Fed. Reg. 34202), EPA adopted regulations codified at 

40 C.F.R. Part 71 setting forth the procedures and terms under which the Agency would 

administer a Federal operating permits program. These regulations were updated on February 

19, 1999 (64 Fed. Reg. 8247) to incorporate EPA's approach for issuing Federal operating 

permits to covered stationary sources in Indian country. 

As described in 40 C.F.R. 71.4(a), EPA will implement a part 71 program in areas where a State, 

local, or Tribal agency has not developed an approved part 70 program. Unlike States, Indian 

Tribes are not required to develop operating permits programs, though EPA encourages Tribes to 

do so. See, e.g., Indian Tribes: Air Quality Planning and Management (63 FR 7253, February 

12, 1998) (also known as the Tribal Authority Rule). Therefore, within Indian country, it is 

appropriate that EPA administer and enforce a part 71 Federal operating permits program for 

stationary sources until Tribes receive approval to administer their own operating permits 

programs. 

6. Endangered Species Act 

Pursuant to Section 7 of the Endangered Species Act (ESA), 16 U.S.C. § 1536, and its 

implementing regulations at 50 CFR Part 402, EPA is required to ensure that any action 

authorized, funded, or carried out by EPA is not likely to jeopardize the continued existence of 

any Federally-listed endangered species or threatened species or result in the destruction or 

adverse modification of such species’ designated critical habitat. The title V permit renewal that 

EPA is issuing to ASARCO Mission Complex does not authorize the construction of new 

emission units, or emission increases from existing units, nor does it otherwise authorize any 

other physical modifications to the facility or its operationsg. Therefore, EPA has concluded that 

the issuance of this permit will have no effect on listed species or their critical habitat.

7. Public Participation 

a Public Notice 

As described in 40 C.F.R. 71.11(a)(5), all Part 71 draft operating permits shall be 

publicly noticed and made available for public comment. The public notice of permit 

actions and public comment period is described in 40 C.F.R. 71(d). 

There is a 30 day public comment period for actions pertaining to a draft permit. Public 

notice will be given for this draft permit by mailing a copy of the notice to the permit 

applicant, the Tohono O’odham Nation, the affected state (Arizona), and local air 

pollution control agencies (DEQ). A copy of the notice will also be provided to all 

persons who have submitted a written request to be included on the mailing list. Public 

notice will also be published in the Arizona Daily Star, a daily newspaper of general 

circulation in the area affected by this source. 

b. Opportunity for Comment 
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Members of the public may review a copy of the draft permit prepared by EPA, this 

statement of basis for the draft permit, the application, and all supporting materials 

submitted by the source at the address listed in Section 8.e, below. Copies of the draft 

permit and statement of basis can also be obtained from EPA’s website 

(http://www.epa.gov/region9/air/permit/r9-permits-issued.html), or by contacting Roger 

Kohn at the EPA address, phone number, or email address listed in Section 8.e, below. 

All documents will be available for review at the EPA Region 9 office indicated in 

Section 8.e. below, during regular business hours. 

If you believe that any condition of the draft permit is inappropriate, you must raise all 

reasonably ascertainable issues and submit all arguments supporting your position during 

the 30-day public comment period. Any supporting documents must be included in full 

and may not be incorporated by reference, unless they are already part of the 

administrative record for this permit or consist of tribal, state or federal statutes or 

regulations, or other generally available referenced materials. 

All comments received during the public comment period and all comments made during 

any public hearing will be considered in arriving at a final decision on the permit. The 

final permit is a public record that can be obtained by request. A statement of reasons for 

changes made to the draft permits and responses to comments received will be sent to all 

persons who commented on the draft permit. 

c. Opportunity to Request a Hearing 

Any person may submit a written request for a public hearing to Roger Kohn, at the 

address listed in Section 8.e., below, by stating the nature of the issues to be raised at the 

public hearing. EPA shall hold a public hearing if EPA finds, on the basis of requests, a 

significant amount of public interest in the draft permit. If a public hearing is held, EPA 

will provide public notice of the hearing and any person may submit oral or written 

statements and data concerning the draft permit. 

d. Mailing List 

If you would like to be added to our mailing list to be informed of future actions on this 

or other CAA permits issued in Indian Country, please send your name and address to 

Roger Kohn at the address listed below. 

e. Contact Information

Roger Kohn (AIR-3) 

U.S. Environmental Protection Agency, Region IX 

75 Hawthorne St. 

San Francisco, CA 94105 

telephone: (415) 972-3973 

e-mail: kohn.roger@epa.gov