Aug 15 1983


Mr. Harold E. Hodges, P.E., Director


Division of Air Pollution Control


Tennessee Department of Public Health


150 Nineth Avenue North


Nashville, Tennessee 37203


Dear Mr. Hodges:


This is in answer to a request made by Angie Pitcock to Rodger Pfaff by


telephone on July 21, regarding EPA’s policy on accumulation of de minimis


increases in emissions at major stationary sources.


As you know, EPA interprets the PSD and nonattainment new source review 


rules (40CFR 51.24, 40CFR 52.21, 40CFR 51 Appendix S, 40 CFR 51.18 (j),


40CFR 52.24) as allowing an unlimited number of de minimis increases at


major stationary sources without subjecting the source to review. This


policy is stated in a memorandum from Edward E. Reich to Charles Whitmore,


January 22, 1981, and is further confirmed in EPA’s June 2, 1983 summary


of applicability determination (PSD-138).


Although the policy outlined in these documents allows a series of de minimis


modifications to escape review, it is important that the reviewing agency


not allow a source owner to circumvent the regulations by splitting up what


would normally be considered a single major modification into two or more


de minimis increases. Two or more increases should be considered by the


reviewing authority to be part of the same project if they are considered part


of the same project in the corporate planning of the source owner or if the


emissions units being constructed or modified are interdependent. For


example, if the company institutes a “debottlenecking” project or a plant-


wide energy conservation project involving several independent facilities, 


the project should be considered to be a single modification. If a company


constructs a new boiler to generate steam and also adds new steam-using


equipment, such as an evaporator, these units should also be considered part


of the same project.


In order to facilitate agency decisions regarding whether two or more


increases constitute a single project, EPA Region IV is adopting a policy


which allows an initial presumption based upon easily distinguishable


criteria, with allowance for rebuttal of the presumption by the applicant. 


Region IV policy is to consider two or more increases as a single project


if the permit application for the last increase is submitted before the 


first increase is operational. This is a reasonable dividing line because 


it is easily discernible and because it would prohibit two facilities from


being considered separate projects if one could not operate without the 


other.

For example, suppose a company obtains a permit for a new boiler at a


major source in an attainment area on June 1, 1983. The new boiler emits


30 tons per year of SO2 and escapes PSD review as a de minimis increase.


On October 1, 1983, while the first boiler is under construction, the


company submits an application for a second, identical, boiler. The 


agency would initially presume that these two boilers were part of a single


project causing a significant increase in SO2. Both boilers would be


subject to PSD, including retroactive BACT for the first boiler. However,


if the company could show, through engineering analysis and internal


documents, that the two boilers were planned during separate time frames 


and involve separate, independent facilities (such as separate product


lines at a large chemical plant), the agency could allow the boilers to


be treated as separate projects. Conversely, if you know that two actions


are actually one project, but the source owner is able to build and 


operate the first one before applying for the second, solely to avoid 


review, you should use that knowledge to subject the project to review.


The initial presumption criteria are used for the purpose of simplifying


your decision process for the more obvious cases. The final criteria 


should always be whether or not the source owner is circumventing the new


source review rules by separating what would normally be considered one


project into two or more projects.


Sincerely yours,


James T. Wilburn, Chief


Air Management Branch


Air and Waste Management Division


cc:	 Ed Reich


Mike Trutna