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OAR Box 1778 

Prepped by Ollie Stewart 

Document Number: 

80) ll-C-22 

Docket Number: 

A-90-06 

Printed 10/28/2008 9:50:55 AM Sheet 80 of 276 
II-C-22 

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 ri UNITED STATES ENVIRONMENTAL PROTECTION AGENCY 

- • J TM ^ - •" WASHINGTON, D.C. 20460 

MAR 2 6 1991 

OFFICE OF 

AIR ANO RADIATION 

Mr. Andrew Aitken 

Vice P res ident r^ - zfff ' \/AA '••:: \ 

Director of Environmental Affairs 

New England Power Service Company i\-<r. ••* 

25 Research Drive \\\Ul B\N \ •; \99\ \» «J\ 

Westborough, Massachusetts 01582-0099 

Dear Mr. Aitken: 

This letter is in response to your request for a 

determination on the applicability of New Source Review (NSR) 

regulations and New Source Performance Standards (NSPS) to the 

addition of natural gas-burning capability at New England Power 

Service Company's Brayton Point Station, Unit No. 4. 

As you described in your January 25, 1991 presentation, your 

letters of February 1 and February 19, 1991, and in subsequent 

telephone conversations with Scott Throwe of my staff, the project 

at Unit Ho. 4 is a pollution control project that is being 

conducted as part of a program to comply with state and federal 

acid rain laws and will not expand the unit's capacity, involve 

extensive renovations to the unit or extend its useful life. You 

state that this project involves the installation of new gas/oil 

low-NOx burners in Unit No. 4, replacing the existing oil-only 

burners. You have provided EPA information stating that this 

project will not result in an increase in maximum hourly emissions 

of any of the pollutants emitted (S02, NOx, PM, CO, VOC) when 

firing oil. Furthermore, you state that this project will result 

in a significant decrease in the maximum hourly emissions of all 

pollutants emitted when firing gas. 

The NSR and NSPS provisions of the Clean Air Act apply to 

both new sources and to modifications of existing sources. 

In general under EPA regulations, a physical or operational change 

which increases emissions over baseline levels is a modification 

that triggers these new source requirements. Under NSPS, an 

emissions increase is defined as an increase in maximum hourly 

emissions [see 40 CFR 60.14]. Under NSR, an emissions increase is 

defined as an increase in annual actual emissions to the 

atmosphere [see e.g., 40 CFR 51.165(a) (1) (v) (A) and (vi)(A), and 

40 CFR 52.21(b) (2) (i) and (3) (i)]. EPA has observed that these 

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definitions can be interpreted in such a manner as to subject to 

NSR, NSPS, or both, certain environmentally beneficial 

activities which neither Congress nor EPA intended to be covered 

by new source requirements. 

EPA's current interpretation of its NSR and NSPS regulations 

is that environmentally beneficial activities such as pollution 

control projects involving the addition of pollution control 

equipment or, as in the case of Brayton Point the use of a less 

polluting fuel, are not the type of physical or operational 

changes intended to be covered by the-EPA's regulations. 

Therefore, pollution control projects are not modifications for 

the purposes of NSPS or major modifications for the purposes of 

NSR. EPA has determined that the installation of new gas/oil lowNOx burners in unit No. 4 at Brayton Point is an environmentally 

beneficial pollution control project that should not be considered 

a physical or operational change within the meaning of the NSR or 

NSPS regulations, and is not subject to the requirements of NSR or 

NSPS. 

EPA is in the process of drafting an interpretative ruling to 

provide further guidance on defining what activities do not 

constitute a modification that may trigger application of new 

source requirements. In particular, if a source only adds or 

enhances systems or devices whose primary function is the 

reduction of air pollution and are determined to be 

environmentally beneficial, then those activities will not 

constitute a physical or operational change triggering new source 

requirements. Please be aware that this- letter does not exempt 

New England Power Service Company from any applicable state 

regulations. 

If you have any questions, please contact John Rasnic of my 

staff at (703) 308-8672 or EPA's Regional office in Boston. Your 

contact there will be Mr. Louis F. Gitto who can be reached at 

(617) 835-3800. 

T' 

William G. Rosenberg 

Assistant Administrator 

Office of Air and Radiation 

cc: R. Brenner, OPAR (ANR-443) 

L. Gitto, Region 1 

B. Tyndall, OGC (LE-132A) 

D. Solomon, AQMD (MD-15) 

S. Throwe, SSCD (EN-341W)