DEPARTMENT OF ENVIRONMENTAL QUALITY 

DIVISION OF AIR QUALITY 

Michael O. Leavitt 150 Nonh [950 West .1/ Governor P.O. Box 144820 

Dianne R. Nielson, Ph.D. Salt Lake City, Utah 84114-4820 

Executive Director (801) 536-4000 Voice ( "" 

Richard W. --- '~. Sprott (80 I) 536-4099 Fax
 

Director
 (801) 536-4414 TD.D. 

January 17,2001 

Richard R. Long, Director
 

Air and Radiation Program
 

EPA Region VIII 8P-AR
 

999 18th Street, Suite 300
 

Denver, Colorado 80202-2466
 

Dear Mr. Long: 

Re: Issues surrounding Utah's forthcoming PMIO SIP revision 

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DAQP-007-0 I 

This letter is written in response to your letter, dated October 6, 2000, in which you had outlined Region 

VIII's list of concerns surrounding Utah's present efforts to produce "interim" maintenance plans for two 

of its PM I0 nonattainment areas. As noted in the October 6, 2000 letter, these interim plans are founded 

on receptor modeling and are intended to mitigate the duration of conformity lapses in each of the two 

nonattaining counties. Implicit in that notion is that Utah will continue to develop a more comprehensive 

maintenance plan using, to the extent possible, dispersion modeling as its basis, and it remains our 

intention to do so. 

It is also possible that an interim maintenance plan would become useful should Region vm's efforts to 

extend the attainment date!:' for Salt Lake and Utah Counties prove unsuccessful. Given the circumstances 

surrounding this action, we continue to encourage your every effort to resolve this matter. 

We intend the following to address the list of concerns identified in the October 6,2000 letter. Some of 

these concerns had been identified in previous discussions with your staff, while others are new to us. 

Thus, this letter may not represent our final position on each of these matters; rather, it is intended to 

reflect our current standings about each one. 

* Commitment to produce a ''final'' maintenance plan. As stated above. it remains the intention of 

Utah Division of Air Quality (UDAQ) to produce a comprehensive maintenance plan for the entire 

Wasatch Front, using the UAM-AERO model as its basis. To the extent this is possible, we will not only 

continue our efforts to that end, but also agree to include a commitment to do so in any plan submitted in 

the interim period. The only circumstance that would persuade us to do otherwise would be the event in 

which the model simply does not work. In such case, we would be forced to re-evaluate the usefulness of 

dispersion modehng, and base the plan on some other fonn of analysis. 

* Tier II interim (MobileS) credits· UDAQ is aware of EPA's policy conceming the use of 

Tier II interim credits in conjunction with the MOBILES model. If the "interim" SIP makes use of these 

credits and does not use MOBILE6, Utah will include a commitment to revise the SIP within the 

appropriate time frame. 
DAQP-007-01 

Page 2 

* Director's discretion· UDAQ offers no opinion as to the validity of the current EPA-approved SIP 

provisions that EPA refers to as "director's discretion" issues. In your October 6, 2000 letter you suggested 

that the following language be included in the maintenance plan to resolve that issue: 

"Notwithstanding any other provision in the Utah SIP, no change to emission 

limits or other requirements contained in or relied on by this maintenance 

plan shall be effective to change such federally enforceable emission limits 

Or requirements without a SIP revision approved by EPA." 

This language raised a number of concerns by UDAQ about what extent emission levels or other factors 

that are not directly limited in the maintenance plan, but are used in the maintenance demonstration, would 

be frozen. 

On November 2,2000 we received an E-mail authored by Jonah Staller clarifying the 

October 6, 2000 letter's language. In it, he stated that where minor emission points at a large emitting 

source did not have limits in the maintenance plan, the letter's language "would not apply to minor 

emission points that have no specific limit in the maintenance plan or other portions of the SIP relied on by 

the maintenance plan." The letter also states that the term "requirements" would not encompass something 

that the SIP projects will occur, but does not require." However, because maintenance plans must idemify 

measures that the State will implement in order to demonstrate maintenance, these measures would be a 

requirement "relied on" by the maintenance plan. Finally, UDAQ agrees with EPA that in order to work, 

the maintenance plan must clearly identify all regulations, pennits or other documents outside the 

maintenance plan that it relies on. Therefore, we agree that the language as stated in the November 2, 

2000 E-mail is workable, and therefore we will include it in the draft proposed maintenance plan when it is 

submitted to the Air Quality Board for proposal for public comment. 

* "Major" source threshold· As envisioned, this threshold would detennine which sources would be
 

projected, in the UAM-AERO SIP, using actual emissions and which would be projected using allowable
 

.emissions.	 Subsequent evaluation of the source list has suggested the following cutoffs: for PMlO - 100 

tons/yr, for S02 - 250 tons/yr, and for NOx - 200 tons/yr. It is our intention to do the preliminary runs of 

the model using these thresholds, but we recognize that the sensitivity of the model may suggest using 

different cut points. We intend to re-evaluate the situation as more information becomes available. For the 

"interim" maintenance plan however, we intend to look first at projecting all sources based on allowable 

emissions. 

* 24·hour emission rates· As mentioned in the October 6, 2000 letter, this issue has been discussed 

before, and it remains our intention to structure the maintenance demonstration so as to evaluate emission 

rates on a 24-hour basis. 

* Additional sources· As discussed on prior occasions, it is our intention to include in the projections any 

significant source, even if it was not included in the base-year inventory. 

* Breakdown rule· With respect to EPA's concern with the breakdown rule currently approved into 

Utah's SIP, UDAQ agrees that the rule would benefit from clarification. However, because any 
DAQP-007-01 

Page 3 

rulemaking on this subject will take considerable time, UDAQ proposes to submit a revision of the rule in 

time for the final maintenance plan, instead of the interim plan. 

* Refineries - Your letter has raised several issues that we had not anticipated: namely the Flares and the 

Sulfur Recovery Unit (SRU) turnaround period. Concerning the flares; there are no emission limits 

associated with these emission points because, to our knowledge, there is no practical way to measure the 

emissions rate at a flare. Nevertheless, estimates were provided for the SIP in order to insure that the 

ambient impacts associated with these emissions were factored into the attainment demonstration. This is 

really no different than factoring in an estimate for the impacts associated with mobile sources. Mobile 

source emission rates are no more verifiable or enforceable than the emission rates from flares. In the case 

of emissions associated with the turnaround of the sulfur recovery units; these estimates were used, in the 

attainment demonstration, to evaluate the county-wide rollback for an annual averaging time, or in other 

words, to ensure that the annual NAAQS for PM 10 would be protected. The estimates for each refinery 

appear as part of the source-wide annual emissions estimate referenced at the end of each source-specific 

entry in Part H of the SIP. None of these source-wide annual estimates is considered to be enforceable, in 

and of itself, unless otherwise specified in the source-specific section of Part H (see IX.H.2.aJ). As 

exceptions to this general rule, each of the refineries was given an enforceable annual emissions cap for 

S02, which does not include the estimate for SRU turnaround. Thus, the references to these estimates are 

for informational purposes. Additionally, in order to safeguard against an exceedance of the 24-hour 

PMlO standard, section IX.H.2.a.M.B requires that such SRU turnaround not be scheduled during that 

portion of the year when the meteorology could provide the conditions necessary for an episode. Perhaps 

EPA could elaborate as to why either of these issues undermines the intent of the SIP, but it is our 

intention to leave these issues alone, at least in the interim plan. This would mean not changing what has, 

so far, proved to be a successful plan. 

* Contingency measures· We appreciate your research into the relevant policy documents, and as per 

that guidance, will not be submitting a contingency measure package to supplement the existing SIP. We 

recognize that, should there be a violation of the standards, the State would need to address this issue on 

the federal level. As it stands, our original contingency measures remain in effect at the state level, 

providing some immediate mitigation should there be a violation of the NAAQS. We also recognize that 

any maintenance plan, submitted under section 175 of the Act, must contain contingency measures, 

although they are somewhat different than those incorporated in an attainment plan. 

If you have any questions, please contact Bill Reiss at 801-536-4077. 

Sin~y,

'(iI/ 

>,.."'Richard W. 

Director 

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