November 18, 1996

Pippin C. Brehler
Wayne County Department of Environment
Air Quality Management
640 Temple, Suite 700
Detroit, Michigan 48201

Dear Mr. Brehler:

This letter is in response to your October 21, 1996, request for a stationary source
determination for Marathon Oil Company. The information provided by the Wayne County
Department of Environment was sufficient for the United States Environmental Protection
Agency to conclude that Marathon's Michigan Refining Division and Marathon's Detroit Light
Products Terminal constitute a single stationary source.

A stationary source as defined in 40 CFR 52.21, and a source as defined in 40 CFR 70.2 is all
pollutant emitting activities from any building, structure, facility, or installations under common
control, belonging to the same industrial grouping, and located on one or more contiguous or
adjacent properties. However, the criteria for determining a major source of hazardous air
pollutants under 40 CFR 63.2 excludes industrial grouping as a source criteria.

According to the information provided by Wayne County, the refinery and the terminal are
adjacent to one another, and are both owned and controlled by the Marathon Oil Company.
The remaining issue is whether these facilities belong to the same industrial grouping.

One test for determining industrial grouping is whether the activities have the same two digit
SIC code. In this case, the refinery is classified under SIC code 29, and the terminal is
classified under SIC code 51. However, to complete the industrial grouping analysis, it must be
determined whether a support facility relationship exists irrespective of the different SIC codes.
According to the preamble to the August 7, 1980 final Prevention of Significant Deterioration
regulations, "...one source classification encompasses both primary and support facilities,
even when the latter includes units with a different two digit SIC code. Support facilities are
typically those which convey, store, or otherwise assist in the production of the principal
product." 45 FR 52695. Using this criteria, the refinery and the terminal are the same industrial
grouping, because the terminal is a support facility to the refinery. The terminal is a support
facility because it conveys the principal product of the refinery.

The proposed preamble to the part 70 regulations (56 FR 21724) and the initial proposed
revisions to part 70 (59 FR 44515) contemplate that a support facility is included with the
source it is supporting if 50 percent or greater of its output were dedicated to that principal
source. In this case, the terminal (the support facility) meets this criteria because most if not all
of the terminal's output is dedicated to the primary product of the refinery.

Marathon Oil Company has raised several concerns to Wayne County regarding the title V
operating permit program requirements that would apply if the refinery and the terminal were
considered one source. First, the company is concerned that the manager of one of the
facilities will be required to certify compliance for the other facility. However, part 70 provides
for such cases by allowing one source to have more than one responsible official, provided
that each person designated meets the responsible official criteria in 40 CFR 70.2. Second,
the company is concerned that modifications which may be necessary for the terminal's
operations would require the refinery's permit conditions to be reopened. As discussed in the
final part 70 preamble (57 FR 32289), any modifications to a source's operating permit would
only need to address the permit conditions that are being modified; portions of the permit that
are not being revised would not be subject to the permit revision process.

Thank you for the opportunity to comment on this issue. If you have any further questions with
regard to this letter, please contact Beth Valenziano at (312) 886-2703.

Sincerely yours,


Robert Miller, Chief
Permits and Grants Section

cc: Jerry Avery, MDEQ