January 16, 1997

Donald Sutton, Manager
Permits Section
Division of Air Pollution Control
Illinois Environmental Protection Agency
P.O. Box 19506
2200 Churchill Road
Springfield, Illinois 62794-9506

Dear Mr. Sutton:

The purpose of this letter is to provide further guidance on the major modification provisions of
the federal rules for Prevention of Significant Deterioration (PSD), 40 CFR 52.21, as applied
to a proposed corn plant expansion (Application 89110058) at the Archer Daniels Midland
(ADM) plant in Decatur, Illinois. ADM proposes to offset the resulting 266.2 tons per year (tpy)
increase in particulate matter (PM) emissions with decreases in roadway fugitive dust
emissions in order to stay below the applicable 15 tpy PM major modification significance

According to the information provided by the Illinois Environmental Protection Agency (IEPA),
ADM believes that the proposed expansion does not result in a significant net change in
emissions pursuant to 40 CFR 52.21(b)(2). Per the January 13, 1997, conversation with
USEPA and IEPA staff, more information is needed for a proper PSD determination.

Based on the information given to USEPA at this time, it appears as though ADM has not
submitted a complete application for a comprehensive PSD netting exercise. The PSD
definition of a net emissions increase [40 CFR 52.21(b)(3)(I)] consists of two additive
components as follows:

(a) Any increases in actual emissions from a particular physical change or change in method
of operation at a stationary source; and

(b) Any other increases and decreases in actual emissions at the source that are
contemporaneous with the particular change and are otherwise creditable.

The proposed ADM permit accounts for 139.8 tpy of contemporaneous PM emissions from
previous minor NSR permit increases. But, the USEPA files for ADM show nineteen other
minor NSR permits for ADM at the "location" 115015AAE from 1994-1996 that have an
additional aggregate contemporaneous increase in PM emissions totaling 139.29 tpy, as
shown in the Attachment. Additionally, there are other minor NSR permits listed under a
separate "location number", yet at the same Decatur ADM "plant".

The PSD regulations in 40 CFR 52.21(b)(5) and (6) and the Title V operating permit
regulations in 40 CFR 70.2 define a stationary source as any building, structure, facility, or
installation that belong to the same industrial grouping, are located on contiguous or adjacent
properties, and are under the control of the same person (or persons under common control).
While the proposed expansion seems to belong to the Standard Industrial Classification (SIC)
Code 20, "Food and Kindred Products", there is question as to the classification of other
operations at the site. The August 7, 1980, Federal Register (45 FR 52695) states that "one
source classification encompasses both primary and support facilities, even when the latter
includes units with a different two-digit SIC code. While all of the operations are clearly
controlled by ADM, it is unclear what operations constitute a "stationary source" at ADM.

An additional USEPA concern with the netting exercise is the "creditable" contemporaneous
decrease (489.9 tpy of PM) achieved through road paving and sweeping. How were these
demonstrated to be the actual PM emissions and how will this reduction be achieved? To be
creditable, at what level will these fugitive road dust emission decreases be discounted
pursuant to 40 CFR Part 52.21(B)(3)(vi)(c) as follows:

A decrease in actual emissions is creditable only to the extent that: ... ... ( c ) It has
approximately the same qualitative significance for public health and welfare as that attributed
to the increase from the particular change.

Based on the information given to USEPA at this time, the proposed corn plant expansion
appears to be a major modification pursuant to PSD. More data is needed to make an
accurate PSD determination with regard to the stationary source categorization of the Decatur
ADM plant and the creditable contemporaneous PM emission increases and decreases
claimed for this project. Unless ADM can prove through the netting of emissions that the overall
increase in PM emissions from this project will not exceed major modification significance
level, 15 tpy, PSD requirements do apply.

I hope you will find this information useful. If we can answer any questions regarding these
comments, or if we can provide any further guidance, please contact Keary Cragan, of my
staff, at (312) 353-5669. Once again, thank you for your commitment to working with us to
improve the permitting process.

Sincerely yours,


Cheryl L. Newton, Chief
Permits and Grants Section