DAQ-2024-004870

10/6/23, 1:23 PM State of Utah Mail - Re: Interpretation of Gadsby operating day
https://mail.google.com/mail/u/0/?ik=391b7b8965&view=pt&search=all&permthid=thread-f:1777506748721746188&simpl=msg-f:17775067487217461…1/2
Joe Rockwell <[e-mail]>
Re: Interpretation of Gadsby operating day
1 message
Harold Burge <[e-mail]>Tue, Sep 19, 2023 at 4:28 PM
To: David Beatty <[e-mail]>
Cc: Rob Leishman jr <[e-mail]>, Joe Rockwell <[e-mail]>
I think that's how we've traditionally looked at it. A day is a day, not a rolling 24-hour block average (unless specifically
defined as being a 24-hour rolling average). Joe or Rob let me know if I'm wrong on this. Wouldn't be the first time, won't
be the last.
On Tue, Sep 19, 2023 at 4:09 PM David Beatty <[e-mail]> wrote:
Pacificorp met with our staff to discuss a problem that Rob brought up during an inspection, John Jenks provided an
answer to them that we are all comfortable with but just wanted to make sure you guys are also good with this answer, I
would think that Gadsby would also follow up with you to make sure they don't have a problem going forward.
---------- Forwarded message ---------
From: John Jenks <[e-mail]>
Date: Tue, Sep 19, 2023 at 2:41 PM
Subject: Interpretation of Gadsby operating day
To: Jon Black <[e-mail]>, Beatty, David <[e-mail]>
Cc: Jennifer He <[e-mail]>, Ana Williams <[e-mail]>
Gentlemen,
After review, PacifiCorp will be interpreting the definition of operating day using the definition from 40 CFR 60 Subpart
GG (the applicable underlying subpart). This definition is:
Unit operating day means a 24-hour period between 12:00 midnight and the following midnight during which any fuel is
combusted at any time in the unit. It is not necessary for fuel to be combusted continuously for the entire 24-hour
period.
Under this approach, all of the hours of any day they operate is counted as a part of the daily emissions. If they
operate for 1 hour, they get to include 23 zeros in the total. They also only count operational days, not calendar days,
so if they don't operate for 2 weeks, those 14 days are not included in the total.
This is consistent across 40 CFR 60.
If you have any questions, please let me know.
--
John D. Jenks
Environmental Engineer IV | NSR Major Source
New Phone #: [phone]
airquality.utah.gov
10/6/23, 1:23 PM State of Utah Mail - Re: Interpretation of Gadsby operating day
https://mail.google.com/mail/u/0/?ik=391b7b8965&view=pt&search=all&permthid=thread-f:1777506748721746188&simpl=msg-f:17775067487217461…2/2
--
David P. Beatty, P.E.
Manager | Operating Permits Section
Phone: [phone]
Emails to and from this email address may be considered public records and thus subject to Utah GRAMA
requirements.