UNITED STATES ENVIRONMENTAL PROTECTION AGENCY 

WASHINGTON, D.C. 20460 

FEB 222012 


OFFICE OF 

AlA AND RADIATION 

Ms. Aletta Belin 

Counselor to the Deputy Secretary 

U. S. Department of Interior 

1849 C Street, NW 

Room 6116 

MS 7229-MIB 

Washington, D.C. 20240 

Dear Ms. Belin: 

Thank you for completing Phase I of your study on Navajo Generating Station. We expect that this 

report by the U.S. Department of Energy's National Renewable Energy Lab (NREL) titled ''Navajo 

Generating Station and Air Visibility Regulations: Alternatives and Impacts," will provide useful 

information to consider in the U.S. Environmental Protection Agency's BART analysis for this facility. 

During our initial review of the report after it was released, we discovered that some corrections and 

clarifications are needed, especially as they relate to the EPA actions. We have spoken to the NREL 

staff about these issues and they indicated that they would make the necessary corrections in an errata 

sheet. However, to further the understanding of these complex issues, I am providing the attached list of 

factual corrections and clarifications to the report. 

We look forward to seeing the comments your office receives on this report, and to continuing to work 

together on this complex issue. 

If you have any questions or concerns, please do not hesitate to contact me at (202) 564-3206, or Ms. 

Deborah Jordan, Director of the Region IX Air Division, at (415) 972-3133 . 

Sincerely, 

Janet McCabe 

Principal Deputy Assistant Administrator 

Enclosure 

cc: Deborah Jordan, Air Division Director, EPA Region IX 

Internet Address (URL) _ http/ lwww.epa.gov 

ReeycledJRecyclabla _ Printed with Vegetable on Based Inks on 100"10 Postconsumer, Process Chlorine Free Recycled Paper 
Enclosure 

EPA Corrections to NREL Phase I Study on Navajo Generating Station 

1. 	 EPA regulatory actions on pages 12 and 14 are not accurately described. The Report states 

that the plant will be subject to a number of regulations and implies that they will require 

additional investments. In many cases, we do not know whether NGS would be affected 

(e.g., in cases where standards have not been set, rules have not been finalized, or 

designations have not been completed). IfNGS were affected by many of these actions, it is 

likely that actions NGS has already taken or will take for MATS or BART would cover some 

of their obligations. Therefore., except in the case of finalized rules, EPA actions should be 

presented as "potentially affecting NGS," including in the title of the table on page 12. 

a. Utility Mercury and Air Toxics Standard. The report incorrectly states that MATS 

sets emission limits for organic compounds. The final rule sets work practice 

standards for organic compounds. 

b. Cooling water intake. The rule will "minimize" not "prevent" 

impingement/entrainment of aquatic life. 

c. Coal Combustion Residues. EPA has no public date for finalizing this rule. The status 

should read "pending". The summary should read "EPA has proposed to regulate coal 

ash to address the risks from the disposal of the wastes, such as residues from the 

combustion of coal in power plants, generated by electric utilities and independent 

power producers. The target date for release of a final rule will be detennined 

pending a full evaluation of all the infonnation and comments EPA received on the 

proposal. " 

d. Ozone and PM NAAQS. The report states that EPA has proposed a revised ozone 

standard. In September 2011, EPA chose not to finalize that revised standard and 

instead has begun implementing the ozone NAAQS promulgated in 2008. EPA is also 

conducting the 5 year review of the ozone NAAQS required by statute and expects a 

proposal in 2013. As a result, the schedule box for this action should read "pending". 

The text under "summary of action" for the PM NAAQS should also be used for the 

summary of action for the ozone NAAQS. Finally, since the ozone and PM NAAQS 

are the same type of process now, both should be characterized as "reviews" or 

neither should be characterized as a "review." 

e. Transport Rule. Also on the table on pg. 12, the Transport Rule II is no longer on 

EPA's Regulatory Agenda. As a result, this rule should be removed from the table. 

f. Utility Boiler GHG NSPS. The Summary should read "EPA is under a court 

settlement to set NSPS standards for this source category for GHG emissions. Under 

the NSPS provisions, the agency will also establish guidelines for states to use in 

regulating existing sources such as Navajo GS. This process could lead to GHG 

requirements for Navajo OS. 

,g. California Senate Bill 1368. The California OHO emission perfonnance standards 

does not impose any requirements on NOS, rather it affects one of the co-owners of 

NOS (Los Angeles Department of Water and Power). We suggest the text be adjusted 

to reflect this. 

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2 . . The discussion on MATS on page 51 is not current - it describes the potential need for 

baghouses and sorbent injection to control SO) and sulfuric acid mist (both contribute to the 

condensable fractions of particulate matter). The final MATS rule set a filterable only PM 

limit of 0.03 IbIMMBtu, therefore, discussion of SO) and sulfuric acid controls is not 

relevant for MATS implementation and should not be characterized as such. EPA notes that 

source tests show that NGS generally already achieves 0.03 Ib/MMBtu (filterable PM). 

Additionally, references to proposal and final rule dates associated with MATS are 

inconsistent in the report and do not correctly distinguish between signature dates and 

publication dates. The publication date of the final MATS rule in the Federal Register is 

February 16, 2012. 

3. 	 In Table 3-11 on page 51, the costs labeled "SCR with sorbent injection and polishing 

baghouse" appear to be consistent with Sargent and Lundy cost estimates for SCR and DSI 

only (i.e., polishing baghouse not included). As noted above, theses costs are unlikely to be 

applicable to MATS implementation based on the final MATS rule. 

4. 	 Page 88. Most sources will have 4 years to comply with MATS, until early 2016 (3 years 

available to all sources + 4th year that EPA expects to be widely available from permitting 

authorities to enable sources to complete compliance activities). 

5. 	 Table 5-1 on page 75 reports emissions ofNOx and S02 emissions that are identical. This 

appears to be a typographical error. 

6. 	 The narrative describing Table 5-6 on page 84 and the numerical values in the table are 

inconsistent. The narrative describes a reduction in nitrate concentrations over time, but the 

values in the table shows a dramatic increase. Additionally, the percent reduction numbers do 

not seem to reflect the actual values in the table. 

7. 	 On page 93, the statement that Mohave Generating Station in southeastern Nevada closed at 

the end of 2005, due largely to the cost of retrofitting the power plant with S02 scrubbers is 

misleading. EPA understands that the spray dryers with high velocity baghouses were 

expected to cost $250 million, and that additional expenses at the time that were unrelated to 

the new scrubbers included a new slurry pipeline ( $250 million) and upgrades/life extension 

of the plant ($500 million) were three times higher than the cost of new controls. Therefore, 

Mohave closed in part, due to the cost of new air pollution controls, but many other factors 

existed that affected decisions related to closure. 

8. 	 On page 101, the report is misleading in its description of the permitting of Desert Rock. 

Although EPA requested a voluntary remand of the final permit to incorporate new 

applicable requirements, the project applicant has not responded to our multiple requests for 

an amended permit application; we most recently sent a letter in December 2011 and will 

follow up with another letter providing a deadline after which we will consider the 

application withdrawn. 

9. 	 Table 3-4 on page 45, should also list Springerville Units 3 and 4 as plants with installed 

SCR technology. Although Springerville is operated by Tucson Electric Power, Unit 4 is 

owned by SRP. These units came on line in 2007 and 2009. 

10. The information on pages 45-47 should include any available cost information for the 

planned retrofit of Unit 2 at Coronado Generating Station - another SRP facility. The 

Consent Decree for Coronado requires the SCR be installed and operational by June 1, 2014. 

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11. On pg. IV of the Executive Summary, the report states that LNB with SOFA have reduced 

NOx emissions at the plant by 40% relative to the plant's air pennit before controls were 

added. The percent control would be lower (-30% reduction from LNB/SOFA) if the 

calculation was done comparing pre-project actual emission rates to limits after installation 

of LNB/SOFA. 

12. On pg IV of the Executive Summary, the report then cites a 78% reduction if SCR were 

installed and 50-60% reduction if SNCR were installed. A control efficiency of 50-60% from 

SNCR is higher than typically cited for SNCR alone. SRP recently estimated SNCR could 

achieve 0.15 - 0.18 IblMMBtu at NOS (a 25 - 38% reduction on top ofpennitted levels of 

0.24 IblMMBtu with LNB/SOF A). Because LNB/SOF A is already installed and operational 

at NOS, control efficiencies from SNCR and SCR alone should either be calculated using a 

baseline of 0.24 IbIMMBtu, or if 0.35 IblMMBtu is used as the baseline, should be reported 

as a control efficiency based on SNCR + LNB/SOFA or SCR+LNB/SOFA (i.e., to be more 

consistent with values reported in Table 3-2 ofNREL report). 

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