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OAR Box 1778 

Prepped by Ollie Stewart 

Document Number: 

56) ll-B-31 

Docket Number: 

A-90-06 

Printed 10/28/2008 9:50:54 AM Sheet 56 of 276 
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UNITED STATES ENVIRONMENTAL PROTECTION AGENCY 

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V(f $ U - V. -.-

II-B-31 

MEMORANDUM 

SUBJECT: PSD Applicabilit y Determination-Southwester n Publi c 

Servic e Company 

FROM: 

TO; 

Director , Stationar y Source Compliance Divisio n 

Offic e of Air Qualit y Plannin g and Standard s \ 

Actin g Associat e Genera l Counse l 

Air, Noise and Radiatio n Divisio n 

Ally n M. Davis, Directo r 

Air and Waste Management Division , Region VI 

Pau l Seals 

Regional Counsel, Region VI 

This is in response to your memorandum dated February 18, 

1983 concerning the applicability of PSD to the Southwestern 

Public Service Company's (SPS) steam electric generating station 

in Amarillo, Texas. SPS operates a coal-fired steam generating 

unit subject to the NSPS requirements of 40 CFP 60 Subpart D. 

SPS is proposing to modify.its existing air pollution control 

system which consists of two electrostatic precipitators (ESP) 

with 95 percent control efficiency of particulate matter followed 

by six wet scrubbers which remove enough of the remaining particulate matter to comply with the particulate matter emission 

standard of the NSPS. The scrubbers also provide a significant 

effect on the SO2 emissions by reducing their amounts by approximately 40 percent. These scrubbers, however, are not necessary 

in order for SPS to comply with the S02 requirements of the 

NSPS. The control alternative SPS has selected for this purpose 

is low sulfur coal. / 

The modification that SPS is proposing is the removal of 

the scrubbers and an upgrading of their ESP which will maintain 

their present level of compliance with the particulate matter 

NSPS. However, removal of these scrubbers will result in an 

approximate increase of 4400 tons per year of SO2. The question 

you raise then is, does this modification of the control sytem 

co •institut e a major noo n lcatafgQRB^CEsthe purposes ot PSD? 

rMBOL

 \eN.:}li.. 

OATE H^7-*3 

EPA Form 132W (12.7&) 

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KM-K* 

OFFICIAL FILE COPY 
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previously it has been determined that this change would ( 

not constitute a rodificstion under the NSPS program. The NSPS 

regulations at 40 CFR 60.14(e) contain a list which exempts 

certain changes from consideration as modifications. Included in 

this list is the provision at 40 CFR 60.14te') (5) which states: 

"The addition or use of any system or 

device whose primary function is the 

reduction of air pollutants except 

when an emission control system is 

removed or is replaced by a system 

which the Administrator determines to 

be less environmentally beneficial." 

Under this provision it was determined that SPS* proposed 

modification would not be less environmentally beneficial for 

NSPS purposes since the change contejnplated by SPS would still 

result in compliance with the NSPS for both particulate matter 

and SO2. 

The separate question of PSD applicability arises because 

the PSD modification provisions do not specifically contain an 

exemption such as that et §60.14(e)(5). After consultation with 

the Office of General Counsel, we both agree with the rationale 

presented by the Texas Air Control Board (TACB) in their January 

21, 1983 letter to Dick Whittington. TACE believes that since 

the NSPS regulations provide an exemption from the modification ( 

provisions for replacement of control equipment, the PSD regulations must provide this exemption as well. This is because the 

Clean Air Act provides in Section 169 (1) (c) that for PSD 

purposes the term modification shall be defined as that term is 

defined in Section 111 (a) of the Act relating to KSPS. EPA has 

interpreted this to mean that for PSD purposes Congress intended 

the term modification to include all exemptions included in the 

NSPS regulations promulgated under Section 111 of the Act prior 

to the date of enactment of Section f69. See 4 3 FR 26396. The 

control equipment exemption was promulgated prior to Section 

169. Therefore, the term modification in the PSD regulations 

inherently encompasses the control equipment exemption. 

I wish to add, however, that just because it was determined 

that the change was not less environmentally beneficial under the 

NSPS program does not mean the same conclusion must be drawn 

with regard to PSD. Under the PSD program the concern is not 

solely the application of best technology, bi/t also impacts on 

air quality from industrial growth. The Region and State must 

evaluate this situation to ensure there will be no adverse air 

quality impact before concluding that the control equipment 

replacement will not "be less environmentally beneficial. If this 

determination can be made, the SPS generating station in Amarillo 

may be exempted from PSD as a major modification. 
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If you have any additiona l question s o r conirients concernin g 

thi s response , pleas e contac t Rich Biondi of SSCD a t 382-2831 or 

Sar a Schheeber a of OGC a t 382-7730. 

Edward E. Reich 

c c : Pete r Wyckoff 

hike Trutna 

Tom Diggs 

William F. Pederson 

EN-341: R.Biondi:kw:Draft 4-2-83 : Final 4-7-8 3 

Disk RAS *3 Rich 

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