### DEPARTMENT OFENVIRONMENTAL QUALITY DIVISION OFAIR QUALITY
150 Nonh [950 West Michael O. Leavitt 

### .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 (80I) 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 PM IO SIP revision 

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This letter is written in response to your letter, dated October6, 2000, in which you had outlined Region VIII's list ofconcerns surrounding Utah's present efforts to produce "interim" maintenance plans for two ofits PMI0 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 ofconformity lapses in each ofthe 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 becomeuseful should Region vm'sefforts 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 ofconcerns 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 ourfinal position on each ofthese matters; rather, it is intended to reflect ourcurrent standings about each one. 

## * Commitmentto produce a ''final'' maintenance plan.As stated above. itremains the intention of Utah Division ofAir Quality (UDAQ) to produce a comprehensive maintenance plan for the entire Wasatch Front, using the UAM-AERO model as its basis. To the extentthis is possible, we will not only continue ourefforts to that end, butalso agree to include a commitment to do so in any plan submitted in the interim period. The onlycircumstance that would persuade us to do otherwise would bethe 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 ofanalysis. 

## *Tier II interim (MobileS) credits· UDAQ is aware ofEPA's policy conceming the use of Tier IIinterim credits in conjunction with the MOBILES model. Ifthe "interim" SIP makes use ofthese credits and does not use MOBILE6, Utah will include a commitmentto revise the SIP within the appropriate time frame.DAQP-007-01 Page 2


## * Director's discretion· UDAQ offers no opinion as to the validity ofthe current EPA-approved SIP provisions that EPA refers to as "director's discretion" issues. In your October6, 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 otherrequirements contained in orrelied on by this maintenance plan shall beeffective tochange such federally enforceable emission limits Orrequirements without a SIP revision approved by EPA." This language raised a number ofconcerns by UDAQ about whatextentemission 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 Stallerclarifying the October6, 2000 letter's language. In it, he stated that where minoremission 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 orotherportions ofthe SIP relied on by the maintenance plan." The letteralso states that the term "requirements" would not encompass something that the SIP projects will occur, butdoes not require." However, because maintenance plans must idemify measures that the State will implementin orderto demonstrate maintenance, these measures would be a requirement "relied on" by the maintenanceplan. Finally, UDAQ agrees with EPA that in order to work, the maintenance plan must clearly identifyall regulations, pennits or otherdocuments outside the maintenance plan that itrelies 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" sourcethreshold· 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 ofthe source list has suggested the following cutoffs: for PMlO

- 100 tons/yr, for S02

- 250 tons/yr, andfor NOx

- 200 tons/yr. It is ourintention to do the preliminary runs of the model using these thresholds, but we recognize thatthe sensitivity ofthe model may suggestusing different cutpoints. We intend to re-evaluate the situation as more information becomes available. Forthe "interim" maintenanceplan however, we intend to look first at projecting all sources based on allowable emissions.


## *24·houremission rates· As mentioned in the October6, 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-hourbasis. 

## *Additional sources· As discussed on prior occasions, it is ourintention to include in the projections any significant source, even ifit 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 benefitfrom clarification. However, because anyDAQP-007-01 Page 3

rulemaking on this subject will take considerable time, UDAQ proposes to submit a revision ofthe rulein time for the final maintenance plan, instead ofthe interim plan.



## * Refineries

- Your letter has raised several issues that we had not anticipated: namely the Flares and the SulfurRecovery 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 orderto 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 orenforceable than the emission rates from flares. Inthe case ofemissions associated with the turnaround ofthe sulfurrecovery units; these estimates were used, in the attainment demonstration, to evaluate the county-wide rollback for an annual averaging time, orin other words, to ensure that the annual NAAQS for PM10 would be protected. Theestimates for each refinery appear as partofthe source-wide annual emissions estimate referenced at the end ofeach source-specific entry in Part H ofthe SIP. None ofthese source-wide annual estimates is considered to be enforceable, in and ofitself, unless otherwise specified in the source-specific section ofPart H (see IX.H.2.aJ). As exceptions to this general rule, each ofthe refineries was given an enforceable annual emissions cap for S02, which does not includethe estimate for SRU turnaround. Thus, the references to these estimates are for informational purposes. Additionally, in orderto safeguard against an exceedance ofthe 24-hour PMlO standard, section IX.H.2.a.M.B requires that such SRU turnaround notbe scheduled during that portion ofthe yearwhen the meteorologycould provide the conditions necessary for an episode. Perhaps EPA could elaborate as to why either ofthese issues undermines the intent ofthe SIP, but it is our intention to leave these issues alone, atleast in the interim plan. This would mean notchanging what has, so far, proved to be a successful plan. 

## * Contingencymeasures· We appreciate your research into the relevant policy documents, and as per that guidance, will not be submitting a contingency measure package to supplementthe existing SIP. We recognize that, should there bea violation ofthe 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 ofthe NAAQS. We also recognizethat any maintenance plan, submitted under section 175 ofthe Act, mustcontain contingency measures, although they are somewhat different than those incorporated in an attainmentplan. Ifyou have any questions, please contact Bill Reiss at 801-536-4077.**Sin~y,**



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