Navajo Generating Station NSR Permit 

August 2015 

2

Navajo Generating Station 

PSD Permit No. AZ 08-01A: Low NOX Burner Project 

Project Description 

The Navajo Generating Station (NGS) has a combined power generating capacity of 2,250 net 

megawatts and consists of three existing coal-fired steam generating units (Boiler Units 1, 2, and 

3), associated air pollution control devices, and auxiliary equipment. The facility was constructed 

in 1970 and is located on the Navajo Nation Indian Reservation approximately five miles east of 

Page, Arizona. Units 1, 2, and 3 are operated by the Salt River Project Agricultural and Power 

District (SRP) and co-owned by the following six entities: U.S. Bureau of Reclamation, SRP, 

Los Angeles Department of Water and Power, Arizona Public Service Company, Nevada Power, 

and Tucson Electric Power Company. The Permittee receives coal with a maximum sulfur 

content of 1.5% by weight from the Peabody Western Coal Company’s Kayenta Mine. 

SRP decided to implement voluntary emission reduction projects at the NGS by retrofitting all 

three boilers with Low-NOx Burners (LNBs) and separated over-fire air (SOFA) systems. All 

three boilers have been retrofitted since PSD Permit AZ 08-01 was issued on November 20, 

2008. 

Although the LNB/SOFA Project significantly reduces emissions of NOx at NGS, it also results 

in a significant increase in CO emissions. This significant increase in CO emission triggered a 

Best Available Control Technology (BACT) review for emissions of CO as part of the issuance 

for PSD Permit AZ 08-01. The boilers were retrofitted and not originally designed for optimum 

combustion as with new units. Thus, it was difficult to appropriately asses the required CO 

emissions limitation. 

Rather than setting the CO emission rates equal to the lowest proposed BACT limitation for new 

units, EPA incorporated a proposed emission rate of 0.42 lb/MMBtu, based on a rolling 30-day 

average into the previous permit along with language that would allow the limit to be ratcheted 

down following the first 18 months of operation of the LNB/SOFA systems. In accordance with 

this permit requirement, SRP submitted CO and NOx emissions data from Unit 3, the first boiler 

unit outfitted with the LNB/SOFA system. This data was used to determine the appropriate CO 

emissions limit for all three boilers. Although this permit revision establishes the final CO 

emissions limitation for Units 1, 2 and 3 at NGS, Demonstration Period reporting requirements 

are still required for Units 1 and 2. 

Minor NSR Permit T-0004-NN – Administrative Amendment 

NGS is adding a new calcium bromide application system and a new powdered activated carbon 

(PAC) injection system for Boilers 1, 2, and 3. The addition of this equipment also increases 

truck traffic at NGS for the routine delivery of calcium bromide and PAC. This project results in 

emissions increase of particulate matter (PM, PM10, and PM2.5) from the PAC system’s storage 

silos and fugitive truck traffic emissions for deliveries of calcium bromide and PAC. 
Navajo Generating Station NSR Permit 

August 2015 

3

EQUIPMENT DESCRIPTION 

Unit ID /

Stack ID Unit Description 

Maximum 

Capacity 

Controls 

Existing Equipment

Boiler 1- 

U1/ 

Stack- S1

One (1) pulverized coal-fired boiler, 

using No. 2 fuel oil for ignition fuel. 

Stack S1 equipped with SO2, CO, 

and NOx CEMS, and a COMS. 

7,725 MMBtu/hr; 

750 Net MW 

FGD system, SCBR1 (1999);

ESP1, LNB/SOFA system 

(2011) 

Boiler 2- 

U2/ 

Stack- S2

One (1) pulverized coal-fired boiler, 

using No. 2 fuel oil for ignition fuel. 

Stack S1 equipped with SO2, CO, 

and NOx CEMS, and a COMS. 

7,725 MMBtu/hr; 

750 Net MW 

FGD system, SCBR2 (1998);

ESP2, LNB/SOFA system 

(2010) 

Boiler 3- 

U3/ 

Stack- S3

One (1) pulverized coal-fired boiler, 

using No. 2 fuel oil for ignition fuel. 

Stack S1 equipped with SO2, CO, 

and NOx CEMS, and a COMS. 

7,725 MMBtu/hr; 

750 Net MW 

FGD system, SCBR3 (1997);

ESP3, LNB/SOFA system 

(2009) 

New Equipment 

PAC Silo 

A 

Storage silo for powder activated 

carbon (PAC) 

1200 acfm Baghouse (integral to 

system) 

PAC Silo 

B 

Storage silo for PAC 1200 acfm Baghouse (integral to 

system) 

FugitivePAC Truck Traffic on Unpaved Roads for 

PAC Delivery 

30 VMT/yr Water spray 

FugitiveCaBr2 Truck Traffic on Unpaved Roads for 

Calcium Bromide Delivery 

365 VMT/yr Water spray 

PERMIT CONDITIONS 

I. PERMIT EXPIRATION

As provided in 40 CFR 52.21(r), this PSD Permit shall become invalid if construction: 

A. is not commenced (as defined in 40 CFR 52.21(b)(9)) within 18 months after the 

approval takes effect; or 

B. is discontinued for a period of 18 months or more; or 

C. is not completed within a reasonable time. 

II. PERMIT NOTIFICATION REQUIREMENTS
Navajo Generating Station NSR Permit 

August 2015 

4

Permittee shall notify EPA Region 9 in writing or by electronic mail of the: 

A. date construction is commenced, postmarked within 30 days of such date. 

B. actual date of initial startup, as defined in 40 CFR 60.2, postmarked within 15 

days of such date. 

C. date upon which initial performance tests will commence, in accordance with the 

provision of Section IX.F, postmarked not less than 30 days prior to such date. 

Notification may be provided with the submittal of the performance test protocol 

required pursuant to Section IX.F. 

D. date upon which initial performance evaluation of the CEMS will commence in 

accordance with 40 CFR 60.13(c), postmarked not less than 30 days prior to such 

date. Notification may be provided with the submittal of the CEMS performance 

test protocol required pursuant to Condition IX.E.5. 

III. FACILITY OPERATION 

At all times, including periods of startup, shutdown and malfunction, Permittee shall, to 

the extent practicable, maintain and operate the facility including associated air pollution 

control equipment in a manner consistent with good air pollution control practices for 

minimizing emissions. Determination of whether acceptable operating and maintenance 

procedures are being used will be based on information available to the EPA which may 

include, but is not limited to, monitoring results, opacity observations, review of 

operating maintenance procedures and inspection of the source. 

IV. MALFUNCTION REPORTING

A. Permittee shall notify EPA by facsimile or electronic mail at R9.AEO@epa.gov

within two (2) working days following the discovery of any failure of air 

pollution control equipment, process equipment, or of a process to operate in a 

normal manner, which results in an increase in emissions above the allowable 

emission limit stated in Condition IX.B of this permit. 

B. In addition, Permittee shall notify EPA in writing or electronic mail within fifteen 

(15) days of any such failure described under Condition IV.A. This notification 

shall include a description of the malfunctioning equipment or abnormal 

operation, the date of the initial malfunction, the period of time over which 

emissions were increased due to the failure, the cause of the failure, the estimated 

resultant emissions in excess of those allowed in Condition IX.B, and the methods 

utilized to mitigate emissions and restore normal operations. 
Navajo Generating Station NSR Permit 

August 2015 

5

C. Compliance with this malfunction notification provision shall not excuse or 

otherwise constitute a defense to any violation of this permit or any law or 

regulation such malfunction may cause. 

V. RIGHT OF ENTRY

The EPA Regional Administrator, and/or an authorized representative, upon the 

presentation of credentials, shall be permitted: 

A. to enter the premises where the source is located or where any records are 

required to be kept under the terms and conditions of this PSD Permit; and 

B. during normal business hours, to have access to and to copy any records required 

to be kept under the terms and conditions of this PSD Permit; and 

C. to inspect any equipment, operation, or method subject to requirements in this 

PSD Permit; and 

D. to sample materials and emissions from the source(s). 

VI. TRANSFER OF OWNERSHIP

In the event of any changes in control or ownership of the facilities to be constructed, this 

PSD Permit shall be binding on all subsequent owners and operators. Permittee shall 

notify the succeeding owner and operator of the existence of this PSD Permit and its 

conditions by letter, a copy of which shall be forwarded to EPA Region 9 at the address 

shown in Section X. 

VII. SEVERABILITY

The provisions of this PSD Permit are severable, and, if any provision of the PSD Permit 

is held invalid, the remainder of this PSD Permit shall not be affected. 

VIII. OTHER APPLICABLE REGULATIONS

Permittee shall construct and operate this project in compliance with this PSD Permit, the 

application on which this Permit is based, and all other applicable federal, state, and local 

air quality regulations. This PSD Permit does not release the Permittee from any liability 

for compliance with other applicable federal, state and local environmental laws and 

regulations, including the Clean Air Act. 

IX. SPECIAL CONDITIONS PURSUANT TO 40 CFR 52.21 - PSD 
Navajo Generating Station NSR Permit 

August 2015 

6

Low-NOx Burner (LNB) & Separated Over-fire Air (SOFA) Requirements 

A. Prior to commencement of installation, the Permittee shall submit the following 

information to EPA: 

1. Design specifications of the LNB/SOFA system to be installed. 

2. At least one month prior to the date of initial start-up, an LNB/SOFA system 

operating plan which sets forth measures that will be taken to maintain and 

operate the system in a manner to ensure compliance with the emission 

limits specified in Condition IX.B. 

B. Emission Limits 

1. Carbon monoxide (CO) emissions from each unit shall not exceed the 

following: 

a. 0.23 lb/MMBtu based on a 30-day rolling average, and 

b. 0.15 lb/MMBtu based on a 12-month rolling average 

2. Nitrogen oxide emissions (NOx) from each unit shall not exceed 0.24 

lb/MMBtu based on a 30-day rolling average. 

C. Demonstration Period Requirements 

1. Demonstration Period is defined as the first 18 months of operation after 

installation of the LNB/SOFA system. 

2. After the Demonstration Period for each of the U1 and U2 LNB/SOFA 

systems, the Permittee shall submit to EPA a written report together with 

CO CEMS data showing actual CO emissions while maintaining NOx

emission levels at or below 0.24 lb/MMbtu on a 30-day rolling average. The 

report shall provide all supporting documentation identifying the 

combustion characteristics that impact CO emissions. This report shall also 

evaluate the ten highest occurrences for a one-hour average and an 8-hour 

average for pounds per hour CO. If these averages are inconsistent (higher) 

with the modeling submittal, either a new modeling analysis will be required 

to assure maintenance of the CO NAAQS or a short term limit will be 

established for the permit. 

D. At all times, including periods of startup and shutdown, the Permittee shall, to the 

extent practicable, maintain and operate the LNB/SOFA system in a manner 

consistent with good combustion practices to minimize emissions. 

E. Continuous Emission Monitoring Systems 
Navajo Generating Station NSR Permit 

August 2015 

7

1. Within 60 days of completion of installation of each LNB/SOFA system, the 

Permittee shall install, and thereafter operate, maintain, certify, and qualityassure a continuous emission monitoring system (CEMS) for each boiler 

which measures stack gas CO concentrations in lb/MMbtu. 

2. The CO CEMS shall meet the applicable requirements of 40 CFR Part 60 

Appendix B, Performance Specifications 3 and 4A, and 40 CFR Part 60 

Appendix F, Procedure 1. The diluent monitor (O2 or CO2) must meet the 

requirements of 40 CFR Part 75. 

3. Permittee shall operate, maintain, and quality-assure according to the 

requirements of 40 CFR Part 75, a CEMS for each boiler which measures 

stack gas NOx concentrations in lb/MMbtu. The NOx CEMs must meet the 

requirements of 40 CFR Part 75. 

4. The CO CEMS shall complete a minimum of one cycle of operations 

(sampling, analyzing and data recording) for each successive 15-minute 

period. 

5. Permittee shall submit a CO CEMS performance test protocol to the EPA no 

later than 30 days prior to the test date to allow review of the test plan and to 

arrange for an observer to be present at the test. The performance test shall 

be conducted in accordance with the submitted protocol, and any changes 

required by EPA. 

6. Permittee shall furnish the EPA a written report of the results of 

performance tests within 60 days of completion. 

7. The CO CEMS shall be tested annually and quarterly in accordance with the 

requirements of 40 CFR 60 Appendix F, Procedure 1. The NOx CEMS shall 

meet the quality assurance requirement found in 40 CFR Part 75. 

F. Performance Test 

A thirty day initial performance test for CO and NOx shall be conducted with the 

CEMS starting the day after successful completion of the performance testing for 

the CO CEMS. A report of the NOx and CO hourly emissions during this initial 

test shall be submitted to EPA within 30 days of completion of the test. 

G. Recordkeeping and Reporting Requirements 

1. Permittee shall maintain records of the hours of operation for U1, U2 and 

U3 on a monthly basis. 

2. Permittee shall maintain records of the amount of fuel used in U1, U2 and 

U3 on a monthly basis. 

3. Permittee shall maintain all records on site of actual operating data and 

emissions calculations for emissions limits required in Condition IX.B. 
Navajo Generating Station NSR Permit 

August 2015 

8

4. Permittee shall maintain CEMS records that contain the following: the 

occurrence and duration of any startup, shutdown or malfunction, 

performance testing, evaluations, calibrations, checks, adjustments, 

maintenance, duration of any periods during which a continuous monitoring 

system or monitoring device is inoperative, and emission measurements. 

 

5. Permittee shall maintain records and submit a written report of all excess 

emissions to EPA semi-annually. The report is due on the 30th day 

following the end of the calendar quarter and shall include the following: 

a. Time intervals, data and magnitude of the excess emissions, the 

nature and cause (if known), corrective actions taken and preventive 

measures adopted; 

b. Applicable time and date of each period during which the CEMS 

was inoperative (monitor down time), except for zero and span 

checks, and the nature of system repairs or adjustments; and 

c. A negative declaration when no excess emissions occurred or when 

the CEMS has not been inoperative, repaired, or adjusted. 

6. Excess emissions shall be defined as any operating day in which the 30-day 

rolling average CO and NOx concentration, as measured by the CEMS, 

exceeds the maximum emission limits set forth in Condition IX.B. 

7. A period of monitor down time shall be any unit operating hour in which 

sufficient data are not obtained to validate the hour for CO, NOx, or O2. 

8. Excess emissions indicated by the CEMS shall be considered violations of 

the applicable emission limit for the purpose of this permit. 

9. All records required by this PSD Permit shall be retained for five years 

following the date of such measurements, maintenance, and reports. 

X. SPECIAL CONDITIONS PURSUANT TO 40 CFR 49.151-161 – MINOR NSR IN 

INDIAN COUNTRY – Units IDs: PAC Silo A, PAC Silo B, Fugitive-PAC, FugitiveCaBr2 

A. Operating Requirements 

1. Vehicle miles traveled (VMT) for truck traffic associated with the delivery 

of powder activated carbon shall not exceed 30 VMT per 12-month period. 

2. VMT for truck traffic associated with the delivery of calcium bromide 

(Fugtive-CaBr2) shall not exceed 365 VMT per 12-month period. 
Navajo Generating Station NSR Permit 

August 2015 

9

B. Monitoring and Recordkeeping Requirements 

1. The Permittee shall monitor and maintain records on a calendar month basis 

of each PAC delivery, the VMT of each delivery, and determine the 12-

month rolling total. 

2. The Permittee shall monitor and maintain records on a calendar month basis 

of each calcium bromide delivery, the VMT of each delivery, and determine 

the 12-month rolling total. 

3. At least once during each calendar week the permittee shall perform a 

visible emissions survey for each PAC Silo (Silos A and B). The survey 

shall be performed during daylight hours by an individual trained in EPA 

Method 22 while the equipment is in operation. If visible emissions are 

detected during the survey, the permittee shall take corrective action so that 

within 24 hours no visible emissions are detected. 

XI. AGENCY NOTIFICATIONS 

All correspondence as required by this permit must be forwarded to: 

Director, Air Division (Attn: AIR-3) 

EPA Region 9 

75 Hawthorne Street 

San Francisco, CA 94105-3901 

e-mail: R9AirPermits@epa.gov and AEO_R9@epa.gov

Environmental Department Director 

Navajo Nation EPA 

P.O. Box 9000 

Window Rock, AZ 86515