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BECKHAM, LISA

From: Richard.Grimes@aps.com

Sent: Monday, June 09, 2014 1:31 PM

To: Lee, Anita

Subject: RE: Request for concurrence on EPA determination that installation of new air pollution 

controls at Four Corners Power Plant is not likely to adversely affect listed species

Please see one response imbedded below. 

From: Lee, Anita [mailto:Lee.Anita@epa.gov] 

Sent: Tuesday, June 03, 2014 9:07 AM 

To: Grimes, Richard L 

Cc: McKaughan, Colleen; Lyons, Ann 

Subject: FW: Request for concurrence on EPA determination that installation of new air pollution controls at Four 

Corners Power Plant is not likely to adversely affect listed species 

Hi Richard, 

As you probably heard from Mike Kafka, we sent an email to FWS back in May to request concurrence on our 

determination that the PSD project is not likely to adversely affect listed species. The FWS asked a couple of follow up 

questions. I will take care of questions 1-3 below, but would like confirmation on something related to question 3, and 

am asking that APS/AECOM work on question 4. 

Regarding question 3, I would like to confirm that the level of sulfuric acid emission used in the deposition analysis in the

BA is based on the sulfuric acid limit APS recommended in the PSD application. 

Your understanding is correct. The maximum deposition rate of H2SO4 shown in Table 2-2 of the BA is 0.071 g/m2/yr and 

the H2SO4 emission rate used in the PSD permit application, Table A-2 (111.26 lb/hr uncontrolled x (1-0.42 control 

efficiency) = 64.53 lb/hr), correspond to the same emission rate of 8.13 g/s.

Regarding question 4, FWS has found an old study suggesting that a pH of 3 causes damage to plants. They are hoping to 

understand the deposition estimates (provided in the BA of proton equivalents per square meter per year) in terms of 

an estimated pH of rain. I am thinking this is something that you or AECOM can work through, possibly as a supplement 

to the BA. Logistically, we could also add it to the current version of the BA and call the next draft the “final” one 

(related to FWS’ question 2). 

I understand you are on vacation this week, so feel free to give me a call next week to discuss. Thanks very much! 

Anita 

Anita Lee, PhD 

Environmental Scientist 

US EPA, Air Division, Planning Office (Air-2) 

75 Hawthorne Street 

San Francisco, CA 94105 

(415) 972-3958 
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From: Lusk, Joel [mailto:joel_lusk@fws.gov] 

Sent: Thursday, May 29, 2014 3:30 PM 

To: Lee, Anita 

Cc: David Campbell 

Subject: Fwd: Request for concurrence on EPA determination that installation of new air pollution controls at Four 

Corners Power Plant is not likely to adversely affect listed species 

Hi Anita, 

I am currently reviewing your BA, and I have the following questions I am hopeful you can answer. I will refer 

to the email from Mr Gerardo C. Rios, sent on May 19, 2014, as the "cover email." With verification of the 

following, we expect to be able to concur with your findings, and have provided additional scientific rationale 

(Neufeld et al. 1985) than was provided in the BA. 

1. Should the letter should be addressed to Mr Gerardo C. Rios and is "Chief, Permits Office" his official and 

only title? Could you please provide a mailing address, as if we were to mail our concurrence (it will also most 

likely be emailed, but the letter could also be mailed). 

2. Mr Rios cover email (below) refers to the Biological Assessment from AECOM (2014) as a draft, suggesting 

there may be another Biological Assessment available that is final. Was the Biological Assessment from 

AECOM (2014) attached to Mr. Rios' email (i.e., TAKE 2 with attachments) the final version of the Biological 

Assessment that is being provided by USEPA to USFWS for this informal consultation? 

3. The cover email states that USEPA has not yet made a Best Available Control Technology (BACT) 

determination that will set a limit for sulfuric acid mist (SAM), and will likely do so in the proposed PSD 

permit and, of course, in the final PSD permit. Do you have a anticipated or expect range of emission limits for 

SAM yet that you could state? Or should we consult on the proposed action before us now, and assume a worst 

case scenario with no emission limits for SAM? The challenge with a "floating" proposed action is that we 

either consult on the worst case effects analysis now, and if that changes, consult on the new proposed 

action. Or we prefer to consult on any expected range of emission limits, and when the final PSD is issued, then 

the concurrence remains valid if the final emission limits were within the range of expected. Could you please 

estimate, to the best of your knowledge, the range of anticipated SAM emission limits that might be expected a 

final PSD permit for a facility of this type, accepting that USEPA has authority to change it subject to their final 

determination? With an expected range as part of your proposed action (provided to us by email), would would 

know that we are consulting whatever the particular SAM emission limit turns out to be in the final PSD. 

4. We appreciate your (direction of APS and AECOM) and exploration of the issue of direct foliar injury to 

plants by SAM and other acids. From the BA provided, I was able to determine that the USDA had conducted 

range health surveys and did not report acid injuries (It is possible that those observations were made of grasses, 

which have high surface angles). I understand that while acid was indicated as a threat to Mancos milkvetch, the 

USFWS (1989) did not have any data to substantiate any injury to the milkvetch from acid rain. I also learned 

that the deposition of SAM into the milkvetch's environment is about 30 sulfur equivalents per hectare per year 

or about 0.0047 total proton equivalents per meter squared per year, from your BA. Would you please verify 

those deposition values and perhaps convert it into something more easy to understand - such as pH? From the 

BA it looks like the maximum would be about 0.0047 total proton equivalents per meter squared per year, and 

using the ranges reported by Neufeld et al. (1985), it appears that would be about pH 5 ish? But I could use your 

help to identify the most likely pH of rains that will occur on milkvetch from the proposed action. It appears 

that foliar damage occurs at or below about pH 3.0 for other plants (Neufeld et al. 1985), and that the degree of 

injury might be related to the leaf angle, shape, structure, and waxiness of leaf (Haines et al. 1985) and while it 
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appears from your BA that those pHs are not likely to occur, I need you to help me verify that fact (perhaps 

through a simple conversion). 

Thank you 

 ̧ ̧.· ́ ̄`·. ̧ ̧.><((((o>. ̧ ̧.· ́ ̄`·. ̧ ̧.>+++('>. ̧ ̧.· ́ ̄`·. ̧ ̧.><((((o>. ̧ ̧.· ́ ̄`·. ̧ ̧.>+++('>. ̧ ̧ 

Joel D. Lusk, Senior Fish and Wildlife Biologist 

US Fish and Wildlife Service, New Mexico Ecological Services 

2105 Osuna Road NE, Albuquerque, NM 87113-1001 

T: 505-761-4709 F: 505-346-2542 Email: joel_lusk@fws.gov

 ̧ ̧.· ́ ̄`·. ̧ ̧.><((((o>. ̧ ̧.· ́ ̄`·. ̧ ̧.>+++('>. ̧ ̧.· ́ ̄`·. ̧ ̧.><((((o>. ̧ ̧.· ́ ̄`·. ̧ ̧.>+++('>. ̧ ̧ 

The Rio Grande begins on our streets and includes our yards and homes. We can all help protect it by 

conserving water and reducing our wastes. 

---------- Forwarded message ---------- 

From: Rios, Gerardo <Rios.Gerardo@epa.gov> 

Date: Mon, May 19, 2014 at 12:55 PM 

Subject: Request for concurrence on EPA determination that installation of new air pollution controls at Four 

Corners Power Plant is not likely to adversely affect listed species 

To: "david_campbell@fws.gov" <david_campbell@fws.gov>, "joel_lusk@fws.gov" <joel_lusk@fws.gov> 

Cc: "wally_murphy@fws.gov" <wally_murphy@fws.gov>, "mckauaghan.colleen@epa.gov" 

<mckauaghan.colleen@epa.gov>, "Lee, Anita" <Lee.Anita@epa.gov>, "BECKHAM, LISA" 

<BECKHAM.LISA@epa.gov>, "Lyons, Ann" <Lyons.Ann@epa.gov> 

 

Dear Mr. Campbell and Mr. Lusk: 

 

EPA is requesting concurrence under Section 7 of the Endangered Species Act (ESA) with our finding that an 

increase in emissions of sulfuric acid mist (SAM) from the Four Corners Power Plant (FCPP), located on the 

Navajo Nation, near Farmington, New Mexico, is not likely to adversely affect listed species. 

 

Arizona Public Service Company (APS), the operator and co-owner of FCPP, has submitted an application to 

EPA for a federal permit allowing it to increase emissions of sulfuric acid mist (SAM) as a result of their plan to 

install selective catalytic reduction (SCR) on Units 4 and 5 at FCPP (Project). The installation of SCR will 

significantly reduce emissions of oxides of nitrogen (NOx) from FCPP. NOx is a criteria air pollutant that 

affects human health and visibility, and contributes to ozone formation and acid deposition. The Federal Action 

under consideration for this consultation is a Federal Prevention of Significant Deterioration (PSD) permit for 

SAM under the Clean Air Act. 

 

EPA is responsible for complying with ESA Section 7 requirements with respect to Federal PSD permitting and is 

the lead Federal Agency for Section 7(a)(2) compliance for this Project. Because the Project has the potential to 

affect listed species and/or critical habitat, final action on this PSD permit must not occur until EPA has determined 

that permit issuance will be consistent with the substantive and procedural requirements of the ESA.
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On August 24, 2012, EPA promulgated a Federal Implementation Plan (FIP) that requires FCPP to reduce 

emissions of NOx by 80 to 87 percent under the Best Available Retrofit Technology (BART) requirement of the 

Clean Air Act and the Regional Haze Rule. The FIP requires APS to implement one of two options to reduce 

emissions of NOx: (1) install SCR on Units 1-5 by October 2017 (BART), or (2) close Units 1-3 by January 1, 

2014 and install SCR on Units 4 and 5 by July 31, 2018 (BART Alternative). To comply with the FIP, APS has 

elected to implement the BART Alternative, and accordingly, APS permanently retired Units 1-3 at FCPP by 

January 1, 2014, resulting in substantial emission reductions of numerous air pollutants from FCPP, including 

NOx, mercury, selenium, and sulfur dioxide (SO2). The operation of SCR on Units 4 and 5 will result in an 

increase in emissions of SAM; therefore, APS must apply for a permit under the PSD program and install Best 

Available Control Technology (BACT) to control emissions of SAM. Because Units 4 and 5 are already 

equipped with wet scrubbers and baghouses, when EPA proposes a PSD permit for public review, EPA’s 

BACT determination will set an emission limit for SAM that will likely require sorbent injection to increase the 

capture and control of SAM in the baghouses. 

 

At our request, APS submitted a draft Biological Assessment (BA), developed by AECOM, to examine 

potential impacts from our issuance of the PSD permit to listed species and critical habitat (attached).The BA 

identified seven species and their critical habitat that are listed or proposed to be listed as federally endangered 

or threatened that have the potential to occur within the Action Area of the facility. The Action Area includes 

areas where potential direct and indirect impacts on listed species and critical habitat may occur. The BA refers 

to the Action Area as the Deposition Area, and is the area where the predicted increase in soil concentration of 

metals (as a proxy for deposition of acids and other particulate matter) after 25 years of future full load 

operation of Units 4 and 5 with SCR, was modeled to be more than one percent of the current concentrations. 

The species that may occur within this area are the Mexican spotted owl (threatened), the Southwestern willow 

flycatcher (endangered), the yellow-billed cuckoo (proposed for listing as threatened), the Colorado 

pikeminnow (endangered), the razorback sucker (endangered), the Mancos milk-vetch (endangered), and the 

Mesa Verde cactus (threatened). 

 

Installation and operation of the SCR, including associated buildings, such as storage silos, will occur within the 

existing fenceline of FCPP, in the middle of disturbed areas or within existing buildings. Although delivery of 

the reagents necessary for the operation of SCR (and any additional controls that EPA requires as BACT for 

SAM) will increase truck traffic to FCPP, the deliveries will occur on existing roads and paved areas within the 

existing fenceline of the facility. Analysis in the BA indicates that listed species and critical habitat do not occur 

within the fenceline of FCPP. 

 

The BA evaluates the effect of acid deposition to soils and surface water to determine whether the installation 

and operation of SCR would decrease the pH of soils and surface water to make existing metals more 

biologically available. Based on the analysis, the BA concludes that deposition of acid gases from FCPP would 

not significantly alter the pH of soil or surface water in the Deposition Area. The BA also considered direct 

deposition of acid mist, and pollutants that contribute to acid deposition (SO2 and NOx), on vegetation in 

general. The BA cites to a study by the World Health Organization (WHO) that concludes deposition of SAM 

tends to be greater on forested areas and vegetation at higher altitudes, and estimates critical load guidelines for 

SO2 and NOx to be 250 sulfur equivalents per hectare per year, and 5 kilograms of nitrogen per hectare per 
5

year. The modeling analysis in the BA predicts a maximum annual average of 29.9 sulfur equivalents per 

hectare per year and 0.037 kilograms of nitrogen per hectare per year in the Deposition Area. 

 

Based on documents from the US FWS, including recovery plans, goals, and listing documents, the primary 

threats to all of the eight species that may occur within the Deposition Area relate to extensive habitat loss or 

modification resulting from anthropogenic activities. Establishment of non-native invasive species and 

competition and predation were also identified as threats to the Southwestern willow flycatcher, the yellowbilled cuckoo, the Colorado pikeminnow, the razorback sucker, and the roundtail chub. Although pollutants 

associated with coal combustion, e.g., mercury and selenium, are listed as potential threats to the fish species, 

the closure of Units 1-3 at FCPP have reduced overall emissions of all pollutants, including mercury and 

selenium, and acid deposition (associated with the increase in SAM from the installation of SCR on Units 4 and 

5) has not been identified as a potential threat to fish species. However, in the 1989 Final Recovery Plan for the 

Mancos milk-vetch (1989 Recovery Plan), acid deposition from power plants was identified as a potential 

threat. The 1989 Recovery Plan stated “Presently, there are no data to suggest that acidic wet or dry deposition 

pose any threat to the Mancos milkvetch, though no data have been collected. However, northwestern New 

Mexico is a center for power production in the region. Two power plants are already on line, and another is 

scheduled for construction. Particulate and chemical fallout from power plants is often acidic, and thus acidic 

deposition is a potential threat to the species.” More recent information from the US FWS, i.e., the 2011 fiveyear review of the Mancos milk-vetch (2011 five-year review), does not provide further discussion of, or any 

data related to, the potential threat of acid deposition to the species. On May 9, 2014, EPA conducted a 

literature search on the effects of acid deposition on milk-vetch (i.e., search terms Mancos milk vetch, Mancos 

milk-vetch, Astragalus humullimus, or milk vetch; and acid deposition, acid uptake, or acid rain, or sulfuric 

acid) on the Science Direct “Web of Science” database and Google Scholar. The only relevant documents from 

the search were the 1989 Recovery Plan, the 2011 five-year review, and the April 2007 Biological Assessment 

for the Desert Rock Energy Project (DREP), prepared by Ecosphere Environmental Services for the Bureau of 

Indian Affairs and the US FWS, with general references to the potential for acid rain to affect vegetation. We 

note that the draft Biological Opinion for DREP, prepared by the US FWS, did not focus on or address potential 

impacts of acid gases on the Mancos milk-vetch. 

 

The installation of SCR on Units 4 and 5 at FCPP to reduce emissions of NOx by 18,600 tons per year will 

result in a projected increase in emissions of SAM of 230 tons per year. The primary threats to the listed or 

proposed species relate to habitat destruction or modification, and the installation and operation of SCR will 

occur within the existing fenceline and disturbed areas of FCPP. The increase in SAM emissions is not expected 

to alter the pH of soils or surface water in the Deposition Area, and acid deposition rates of sulfur and nitrogen 

are expected to be well below critical load guidelines put forth by the WHO. Although acid deposition was 

previously identified as a potential threat to the Mancos milk-vetch, there is no data to suggest that acid 

deposition poses an actual threat to the species. Therefore, we find that if EPA issues a PSD permit to FCPP to 

install and operate SCR on Units 4 and 5, the increase in emissions of SAM is not likely to adversely affect 

federally-listed species or their critical habitats, in accordance with 50 CFR 402.13 and 402.14(b). EPA requests 

concurrence from the Service with this finding. 

 

Thank you in advance for your attention to this request. If you have any questions, please contact Anita Lee at 

(415) 972-3958 or lee.anita@epa.gov. 

 
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Gerardo C. Rios 

Chief, Permits Office 

(415) 972-3974 

 

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