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## Kay McGovern & Associates **Suite 117, 314 West Millbrook Road** C**Raleigh, NC 27609-4380 (919) 870-1600**  C**FAX 870-1603** C**(800) 255-7886** UNITED STATES ENVIRONMENTAL PROTECTION AGENCY

11th CONFERENCE ON AIR QUALITY MODELING

THURSDAY, AUGUST 13, 2015

ENVIRONMENTAL PROTECTION AGENCY RESEARCH TRIANGLE PARK, NORTH CAROLINA

8:30 a.m.

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KAY McGOVERN & ASSOCIATES (919) 870-1600 **Suite 117, 314 West Millbrook Road FAX 870-1603 Raleigh, North Carolina 27609-4306 (800) 255-7886**  A G E N D A
Opening of the Public George Bridgers, OAQPS 251 Hearing (Day 2) Public Presentations and Comments Virtual Facilities Beth Barfield, ERM for 253 NAAQS Study NAAQS Implementation Coalition Outstanding Issues for David Heinold, AECOM for 259 Modeling Low-Level AF&PA and American Wood Emission Sources Council Impacts of Measurement Zachery Emerson, NCASI 267 Uncertainty and Emissions for AF&PA Variability on Modeled Impacts Use of EMVAP for Bob Paine, AECOM 277 Determining Permitted Carlos Szembek, ERM 281 Emission Rates for Highly Variable Sources Related to Appendix W 8.2 Building Downwash: Ron Petersen, CPP, Inc. 287 Problems, Solutions, and Next Generation Background Concentrations Sergio Guerra, CPP, Inc. 29 6 and the Need for a New System to Update AERMOD The Use of CAMD Data in David Long, AEP 309 Air Quality Modeling Initial Feedback on Chris Rabideau, Chevron 317 Proposed Revisions to for API Appendix W Procedural Concerns Cindy Langworthy 326 Related to EPA's Hunton & Williams for Regulations and Guidance UARG on Air Quality Modeling

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KAY McGOVERN & ASSOCIATES (919) 870-1600 **Suite 117, 314 West Millbrook Road FAX 870-1603 Raleigh, North Carolina 27609-4306 (800) 255-7886**  A G E N D A (continued) Is AERSCREEN Always George Schewe 335 Greater than AERMOD Trinity Consultants Preliminary Appendix W Jeff Bennett 343 Comments - Ozone Barr Engineering Oral Comments Bridget Lee, Sierra Club 352 Peter Guo, Apex TITAN 356 George Schewe, Trinity Consultants 358

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KAY McGOVERN & ASSOCIATES (919) 870-1600 **Suite 117, 314 West Millbrook Road FAX 870-1603 Raleigh, North Carolina 27609-4306 (800) 255-7886** 

F U R T H E R P R O C E E D I N G S 8:33 a.m. 1 Mr. Bridgers: So while everybody is taking 2 their seats, I'll go ahead and call the public hear ing and 3 the conference back to order. I hope that everybody had a 4 pleasant evening. The weather last night was phenomenal. I 5 forget to mention before everybody broke for evenin g that 6 there was a meteor shower last night. I guess it i s August. 7 I did get home late, but I didn't look up. 8 Nonetheless, thank you for coming back this 9 morning. I know we lost a few people but we have t en more 10 public presentations this morning, and I already kn ow that we 11 have at least a couple of slide decks that have bee n 12 requested during the open forum session that will f ollow 13 right before lunch and then right after lunch. 14 So I did want to go through--this is just some 15 real quick logistics. Most of you that were here yesterday, 16 this is old hat, but I just wanted to reiterate tha t this 17 conference is a public hearing. It's a public hear ing both 18 in the context of Section 320 of the Clean Air Act, which 19 requires us to have triennial modeling conferences but it's 20 also a public hearing with respect to the proposed rulemaking 21 for the guideline--for the revisions to the Guideline on Air 22 Quality Model

. 23 So again, everyone that speaks today needs to 24 identify themselves and their affiliation. As such , I'm 25

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KAY McGOVERN & ASSOCIATES (919) 870-1600 **Suite 117, 314 West Millbrook Road FAX 870-1603 Raleigh, North Carolina 27609-4306 (800) 255-7886**  George Bridgers with the Air Quality Modeling Grouphere at 1 the USEPA. Everything that is said is going to be 2 transcribed, and that will become part of the recor d and 3 submitted to the docket. 4 We will not allow any question and answering. And 5 anyone that has not requested a spot to speak, whic h will be 6 the first ten presentations, out the front door her e Nan has 7 a sign-up sheet that you can put your name on, but I'll go 8 ahead and say that later in the after lunch period we'll have 9 a session that--not assigning myself to any religio us 10 affiliation, but the Quakers, where if the spirit moves you, 11 you can come up and speak at the mic. All of our 12 presentations during the open forum, we will respec t them the 13 same as we have our other speakers, and they will h ave up to 14 15 minutes, if they would like, to use that time. 15 After the conference, if you would like to 16 submit--I'm sure everybody that probably spoke willbe 17 submitting final comments in writing to the docket. You 18 have--I think it's 74 days before we get to October27. 19 We have a brisk schedule. It's not ridiculous, 20 but we're going to do like we did yesterday. Each speaker 21 again has 15 minutes and maybe a few seconds here o r there, 22 but we need to keep people on track, and so I just ask for 23 everybody to be respectful. 24 And so we that, we'll actually be ahead of 25

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KAY McGOVERN & ASSOCIATES (919) 870-1600 **Suite 117, 314 West Millbrook Road FAX 870-1603 Raleigh, North Carolina 27609-4306 (800) 255-7886**  schedule, and we'll go ahead and call Beth--is Bethhere, she 1 is--to the podium. And while Beth is coming up, ag ain, if 2 there are any questions or issues, find me and I wi ll try to 3 resolve them. So without further ado, Beth, the fo rum is 4 yours. The podium is yours. 5 Ms. Barfield: My name is Beth Barfield. I'm 6 with Environmental Resources Management. We call i t ERM. 7 Today I am speaking on behalf of the National Ambie nt Air 8 Quality Standards Implementation Coalition. Last a fternoon 9 the last speaker was Rob Kaufmann, and he gave you the 10 comments that were more policy oriented than the on es that 11 I'll be presenting today are the more technical ori ented, the 12 ones that we're talking about, the specific comment s to the 13 proposed revisions. 14 Yesterday also Rob mentioned a song of Mighty 15 Mouse. And I was kind of surprised because we havefurther 16 at ERM shortened that acronym from NAAQS Implementa tion 17 Coalition to NIC. So I thought he was going to do Mickey 18 Mouse, you know, because we're N-I-C, and we're say ing why. 19 We like to see the revisions, and that is really th e theme of 20 my presentation. Before I went into my singing, I should 21 have asked how to do this. Do you do this? Okay. There we 22
go. 23 Okay. The study objectives that we had when we 24 were preparing even--not even comments, but recomme ndations 25

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KAY McGOVERN & ASSOCIATES (919) 870-1600 **Suite 117, 314 West Millbrook Road FAX 870-1603 Raleigh, North Carolina 27609-4306 (800) 255-7886**  for what we would like to see for revisions for theAppendix 1 W, we looked at the challenges that the members of the NIC 2 were having when they were doing their air permitti ng and 3 their compliance demonstrations that were dependenton 4 dispersion modeling, and we wanted to identify the key 5 technical changes that we would like to see in the Appendix W 6 revisions. 7 The--NIC, see there, that's what we're calling 8 it--is comprised of various trade organizations and 9 individual member companies who were having these c hallenges 10 in demonstrating their compliance when they were do ing their 11 permitting and even just regular ambient compliancemodeling 12 that would be required by the states. 13 What we came up with, the three that I'm going to 14 focus on today, are the recommendations on how the background 15 concentration should be handled, also the suggestio n that the 16 low wind beta options be changed to default insteadof non17 default beta, and similarly, that the two refinemen ts should 18 become default as opposed to non-default beta optio ns. 19 What I'll do today is just present to you the 20 general approach that we took in preparing our study and then 21 how we develop the virtual sources and then the res ults that 22 we have that support the recommendations that we ma de. 23 This is really again not so much a list of things 24 that I would hope that you could read during this 25

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KAY McGOVERN & ASSOCIATES (919) 870-1600 **Suite 117, 314 West Millbrook Road FAX 870-1603 Raleigh, North Carolina 27609-4306 (800) 255-7886**  presentation, but just to show you that there is a lot of 1 different guidance that has to be followed, and we would like 2 to see these things compiled in one Appendix W. Itlooks 3 like it's going to be. 4 We began with three hypothetical types of 5 facilities. One was a gas fired electrical generat ing unit-- 6 these are combined cycle and simple cycle units--al so then a 7 gas refinery and some industrial manufacturing, jus t to look 8 at three different types of facilities. 9 These were again virtual facilities. Nobody is 10 planning to build any of these. They were a compil ation of 11 different units that are in different facilities th roughout 12 the U.S. by the member companies. There was quite of a 13 negotiation process about what our facilities shoul d look 14 like. 15 So here with the electric generating unit, as I 16 mentioned, we have both combined and simple cycle. And then 17 the refinery we have all the process heaters and fl ares. We 18 tried to make all of the facilities look like they were 19 very--generally well controlled, not brand new but existing 20 units; and then a manufacturing facility. 21 Similarly, we picked three different types of 22 location, ones with flat terrain, ones with complexterrain, 23 and one with rolling terrain. The reason that we t ook 24 specific locations is because we wanted to have act ual 25

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KAY McGOVERN & ASSOCIATES (919) 870-1600 **Suite 117, 314 West Millbrook Road FAX 870-1603 Raleigh, North Carolina 27609-4306 (800) 255-7886**  meteorology and ambient monitoring data that we cou ld use in 1 our analysis. 2 And again, none of those sites are really being 3 considered. They were empty sites. We chose them as empty 4 because we didn't want the background concentration s to 5 include something that was already there that we we re going 6 to be modeling on top of. 7 So there's our site in Louisiana. And you can see 8 the relative location of the site with the refinery , the 9 power plant, and the manufacturing location. And t hen here 10 is--the Montana site was our complex one. And in N orth 11 Carolina King's Mountain is out there. 12 The first comment that we wanted to make on the 13 changes that the EPA is proposing is from the 8.3.2 c.iii 14 that "For short-term standards, the diurnal or seas onal 15 patterns of the air quality monitoring data may dif fer 16 significantly from the patterns associated with themodeled 17 concentrations." 18 And we found out that this does occur frequently. 19 If you look at the table here, we have the averagin g period 20
for PM2.5and O 2and SO 2 . We presented the design value--and 21 this is for the North Carolina site--the design val ue if we 22 take just the annual numbers, and then also how whe n we 23 paired it with the modeling results, you can see th at PM2.5 24 didn't go down much, but NO 2and SO 2really made a 25

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KAY McGOVERN & ASSOCIATES (919) 870-1600 **Suite 117, 314 West Millbrook Road FAX 870-1603 Raleigh, North Carolina 27609-4306 (800) 255-7886**  significant difference. And in our cases, it was t he 1 difference between demonstrating attainment and not

. 2 The next one is the modification to the AERMOD 3 system. This has been discussed earlier, yesterday , and that 4 was on changing the low wind from a default--to a default 5 from the non-default beta options. And in our case s, we 6 found that the North Carolina--or all the results c hanged 7 more significantly in the fugitive emissions than i n the 8 cumulative impact, so I've put both of those here. You can 9 see the difference. And with the annual average, s imilarly 10 we see more of the results are significantly impact ed with 11 the fugitive emissions, not so much with the whole 12 cumulative. 13 And I think, now, Bob talked too about the stacks 14 yesterday. And we found a similar difference betwe en those. 15 And this is again using the low wind option 2. We haven't 16 done this with 3. 17 The third is how the treatment of nitrogen dioxide 18 would be in. In the preamble it was mentioned thatthe ARM2 19 would be replaced. And we had discussions yesterda y about 20 this in more detail. Rich Hamel went through that. The 21 difference--now, what we had used was the .3 instea d of the 22 .5. We haven't redone it for those numbers. And what we 23 would like to see is this to be changed also to def ault so 24 that we don't need to spend the time and the money coming up 25

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KAY McGOVERN & ASSOCIATES (919) 870-1600 **Suite 117, 314 West Millbrook Road FAX 870-1603 Raleigh, North Carolina 27609-4306 (800) 255-7886**  with a site specific demonstration. 1 This is the differences that we found. You can 2 see I listed them all for North Carolina, Montana, and 3 Louisiana with the Tier 1, 2, and 3. You can see w ith the-- 4 even with the Tier 2 ARM2 that there was a signific ant 5 reduction in the proposed--in, sorry, the calculate d 6 concentrations. 7 So in summary, we would like to support the EPA's 8 revised changes on how background concentrations sh ould be 9 determined. And by that we mean using the diurnal- -seasonal 10 diurnal type of background calculations instead of a one 11 number design value. 12 And that's because, as we showed, that there is a 13 low likelihood between the time and the place that the--or 14 the time, I should say, that the monitored value wo uld be 15 peaking and the model value would also be peaking. 16 We also support the designation of the low wind 17 speed options to default in both AERMET and in AERMOD. And 18 finally, we support also the change of the non-defa ult beta 19 options for the NO xrefinements to default options. And I 20 will take questions offline at another time. Thankyou for 21 your attention. 22 Mr. Bridgers: Thank you, Beth. We're zooming 23 right along. If David--is David--oh, David is here , yes. 24 All right, David. 25

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KAY McGOVERN & ASSOCIATES (919) 870-1600 **Suite 117, 314 West Millbrook Road FAX 870-1603 Raleigh, North Carolina 27609-4306 (800) 255-7886** 

Mr. Heinold: Good morning, everyone. My 1 name is David Heinold. I'm an air quality meteorol ogist with 2 AECOM. And I'm speaking on the behalf of the Ameri can Forest 3 & Paper Association and the American Wood Council. 4 This morning what I'd like to talk about are some 5 issues that are out there that have been out there kind of 6 forever for low level emission sources. When we me an low 7 level emission sources we mean things like fugitivedust, 8 emissions that are essentially non-buoyant from lowrise 9 buildings that are very common to industry througho ut the 10
U.S. 11 So one of the characteristics of these types of 12 sources that make them particularly problematical i n terms of 13 modeling, well, location of these sources relative to what 14 are--have been considered historically off-site rec eptors is 15 often very close. 16 In other words, some of these are smaller 17 facilities that are--that are nearby fence lines sothat if 18 you have emissions close to the ground, you could e asily have 19 model concentrations that are disproportionately hi gh in 20 reference to the annualized emissions from those so urces. So 21 because of that modeling those sources and characte rizing 22 them are extremely important. They are also many t imes 23 emitted in--among the flow obstacles like buildings and tanks 24 and piles and whatnot. Again it makes them charact erizing 25

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KAY McGOVERN & ASSOCIATES (919) 870-1600 **Suite 117, 314 West Millbrook Road FAX 870-1603 Raleigh, North Carolina 27609-4306 (800) 255-7886**  very important. 1 And more recently, because we now have tighter 2 NAAQS--that is the background concentrations are ge tting 3 perilously close to the ambient air quality standar ds, 4 especially for example for annual PM2.5 --if we model them with 5 excessive conservatism, they're often likely to demonstrate a 6 model that's not in compliance when there really is n't an 7 issue, especially if there isn't an issue really wh ere 8 legitimate off-site receptors should be located. 9 So based on that, there are essentially two issues 10 that I'm going to talk about today among all of the se. The 11 first is the identification of what has been charac teristi12 cally identified as fence line receptors as a standard way of 13 establishing what receptors should need to be model ed. 14 And the second is taking a look at issues that 15 have been brought up at previous modeling conferenc es 16 regarding PM 10and PM2.5 , and the rate that they are 17 transported off site and the physical dynamics thataffect 18 those concentrations as they go off site. 19 So placement of near-field receptors; so the idea 20 that we're discussing here is in 2014 EPA came up w ith risk 21 assessment guidance that has been essentially long- standing 22 but clarified, and it talked about how to character ize 23 off-site risk, and in that they stated that one sho uld be 24 evaluating exposure where exposure can actually occ ur, 25

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KAY McGOVERN & ASSOCIATES (919) 870-1600 **Suite 117, 314 West Millbrook Road FAX 870-1603 Raleigh, North Carolina 27609-4306 (800) 255-7886**  essentially put in a nutshell. 1 And so if we take that concept and address it in 2 terms of the NAAQS, we should consider for the part icular 3 NAAQS, say it's an annual average, can exposure occ ur for an 4 appreciable portion of that. Is it possible? And if it's 5 not, is that a legitimate receptor? 6 And for the short-term NAAQS, say the 24 hour PM2.5 7
or the NO 2or the SO 2 , one hour, could a person be at that 8 location 98 percent or more than 2 percent of the days for 9
PM2.5 ? Could they be in that location more than 1 perce nt of 10 the days in terms of SO 2 ? If it's impossible for someone to 11 be in those locations, those should not be legitima te 12 receptors. 13 So the examples that we'll be talking about will 14 be things like railroad right-of-ways, controlled a ccess 15 highways, public roadways, inaccessible terrain, pe rhaps 16 rivers with rapids where it would be difficult for someone to 17 be there located. And we're suggesting that this b e 18 evaluated on a case by case basis. 19 So what we're now seeing is a hypothetical example 20 of a facility along a river that is--also has a res tricted 21 access highway, say an interstate, to its north andto its 22 east it has a railroad property, a railroad right-o f-way. 23 And what we display here with the yellow stars is what would 24 typically be the set of receptors that would be use d for 25

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KAY McGOVERN & ASSOCIATES (919) 870-1600 **Suite 117, 314 West Millbrook Road FAX 870-1603 Raleigh, North Carolina 27609-4306 (800) 255-7886**  modeling. And each of those red dots essentially i ndicate a 1 low level source of emissions so that one would exp ect 2 concentrations to decrease rapidly with distance. 3 So what we're showing here is a different way of 4 looking at the receptors depending on the particula r NAAQS. 5 If we look on the river side, we have an annual PM2.5NAAQS of 6 12 micrograms per cubic meter. And at the fencelin e for this 7 hypothetical example, we had a concentration of 14 micrograms 8 per cubic meter, which is above the NAAQS and acros s the 9 river it's low, similar relief on the northbound si de. 10 And the legitimacy of putting that on the other 11 side of the river is that is someone--could someonepossibly 12 be on that river for an annual period. Now, if the re was 13 a--if there--if boats were docked there along that river, 14 then clearly that would be a possible receptor, butfor 15 instances where it's not a river that's really acce ssible or 16 used for that purpose, then it's not legitimate rea lly to put 17 receptors along the river. 18 The limited access highway, we know there's laws 19 in place that don't allow people to loiter on the h ighway for 20 nearly a large part of 24 hours, so those receptors perhaps 21 should be on the north side of that. And even for the 22 railroad property, we know we're not supposed to bethere at 23 all because you're going to be hit by trains and fo r walking 24 the tracks, there are other laws regarding--you know, 25

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KAY McGOVERN & ASSOCIATES (919) 870-1600 **Suite 117, 314 West Millbrook Road FAX 870-1603 Raleigh, North Carolina 27609-4306 (800) 255-7886**  independent of the Clean Air Act or any other kind of 1 environmental act that prevents people from being t here. 2 And we're not necessarily talking about relative 3 risk but just the fact that they're breaking the law being 4 there. And should that--is there any legitimacy toputting 5 receptors on the tracks, and we maintain that thereis not 6 legitimacy. 7 So now I'd like to go to a different subject 8 matter, the second topic that we want to discuss, i s that 9 fugitive dust studies have shown over the years the re are 10 mechanisms when you have high concentrations of emi ssions 11 from a fugitive dust source, say like from a haul r oad, that 12 would affect the transport off site. 13 And what we're discussing here, not to go into 14 details, but this was previously discussed by Dr. C hatten 15 Cowherd at the EPA's 10th Modeling Conference, and 16 essentially there are three aspects of this that wewant to 17 reiterate. 18 Number one, roadway dust from industrial sources 19 is different than standard highways in that you wou ld have 20 individual sources that are moving along a line rat her than a 21 whole string of vehicles that would actually repres ent a line 22 source, which is the way we model it in AERMOD. 23 And so there are refinements that could be applied 24 that account for that transient nature. And the in dications 25

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KAY McGOVERN & ASSOCIATES (919) 870-1600 **Suite 117, 314 West Millbrook Road FAX 870-1603 Raleigh, North Carolina 27609-4306 (800) 255-7886**  of previous studies have indicated that within the 100 meters 1 you could have a sizeable decrease in the modeled c oncen2 tration due to the lateral dispersion and the long wind 3 dispersion of a moving source. 4 And the two effects that affect off site transport 5 are the agglomeration of the particles when they'rein very 6 high concentration so that the PM2.5will essentially stick 7 together and become PM 10and some of the PM 10size or the 8 coarse particles would agglomerate to some extent a nd get out 9
of the PM 10range. And that's been shown to have an effect 10 for very high concentration sources which are assoc iated with 11 fugitive dust. 12 And if the sources--if there's buildings and 13 vegetation near the sources, it's also been shown t hat the 14 vegetation especially has a large effect on scaveng ing the 15 dust as it begins to move off site, and that can bea very 16 large effect. And the rate of scavenging is much g reater 17 than it would be say estimated by just using the st andard 18 deposition algorithms in ISC, which dates me--in AE RMOD, 19 which uses the same methodology as ISC used, by theway. 20 Okay, so just some pictures of what we're looking 21 at in terms of intermittency. So on the left we se e a 22 representation of a roadway segment and how it woul d be 23 modeled in AERMOD as a series of line sources. Andhere we 24 see that would represent something like the roadwaywe see 25

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KAY McGOVERN & ASSOCIATES (919) 870-1600 **Suite 117, 314 West Millbrook Road FAX 870-1603 Raleigh, North Carolina 27609-4306 (800) 255-7886**  that's below it where you have, you know, a string of cars or 1 vehicles in a row so that a line source fairly repr esents it. 2 And on the right side we see something more like a 3 haul road in this case. It looks like some kind ofa dirt 4 road in a rural area where you have very intermitte nt 5 traffic, and so it's really a traveling point sourc e, so more 6 of the representations say that FAA uses in modelin g aircraft 7 where it looks at individual moving sources might b e more 8 appropriate than using a line source in AERMOD. 9 For the second effect, this is an illustration 10 of--we can see vehicles had traveled along these ro adways and 11 we can see the residual dust and we can see the tra nsport as 12 it approaches the vegetation. But we also can notethat the 13 vegetation--there's the ability to scavenge out muc h of those 14 emissions. And if one has a roadway that is--wherethere's 15 quite a bit of vegetation surrounding it on one side or the 16 other, we should be able to account for that in themodel so 17 we're not indicating off-site transport of the PM2.5and the 18
PM 10and account for that degradation. 19 So where are we now? Well, since the 10th 20 Modeling Conference, AISI and Dr. Cowherd have pres ented the 21 concepts to OAQPS and there have been further discu ssions at 22 annual workshops. And EPA has indicated at that time they 23 aren't really interested or think it's appropriate to 24 actually change the AERMOD because that's--in otherwords, if 25

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KAY McGOVERN & ASSOCIATES (919) 870-1600 **Suite 117, 314 West Millbrook Road FAX 870-1603 Raleigh, North Carolina 27609-4306 (800) 255-7886**  we want to evaluate these effects we should look ex ternally 1 to AERMOD to figure out how to perhaps characterizethe 2 emissions in a more exact way that would account fo r these 3 types of effects. So an industry group is currentl y-- 4 presently investigating the feasibility of incorpor ating 5 these concepts into refined modeling procedures forfugitive 6
dust sources. 7 So what's going on right now is we have current 8 activities to review the literature and the basis f or these 9 theoretical studies and see what types of degradati on factors 10 are appropriate. We're looking at the characteriza tion of 11 the fugitive dust emission reduction factors, that is what 12 parameters are important to take into account in ca lculating 13 those factors, and then also developing a conceptua l design 14 of how they could be implemented in AERMOD into eit her pre or 15 postprocesses that wouldn't affect the dispersion c alculated 16 in AERMOD, but it would essentially accomplish a co rrection 17 to the emission rates that are being simulated. 18 So possible future activities, then, would be to 19 design and implement the algorithms, identify exist ing field 20 studies that might further support the use of the a lgorithms, 21 and if deemed necessary perhaps develop more field data. 22 So what are we talking about in terms of the 23 requests based on these types of effects? Well, es sentially 24 we suggest that the Appendix W discussion regardingreceptors 25

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KAY McGOVERN & ASSOCIATES (919) 870-1600 **Suite 117, 314 West Millbrook Road FAX 870-1603 Raleigh, North Carolina 27609-4306 (800) 255-7886**  gives some--a lot of the users and regulatory autho rities to 1 consider the potential for public presence either b y physical 2 barriers or by other regulatory or laws that preven t exposure 3 in critical cases where the receptors should not le gitimately 4 be placed, and perhaps at a minimum at least Append ix W 5 should provide some indication that local regulator s in 6 regions should have the ability to kind of be free thinkers, 7 not be lockstepped. 8 As was noticed previously in the placement of 9 receptors by EPA when they said we don't want to us e the 10 puzzle book anymore as the way to do things necessa rily, we 11 would suggest the same thought process should go onin the 12 placement of near-field receptors. 13 We'd also suggest in the discussion in Appendix W 14 regarding fugitive dust emissions that, again, flex ibility be 15 given to the characterization of the sources to acc ount for 16 factors that are not addressed directly in the mode l such as 17 discussed here. And that is the end of my remarks. Thank 18
you. 19 Mr. Bridgers: Thank you, David. So next up 20 we have Zach from NCASI, and I'll let you announce all your 21
coauthors. 22 Mr. Emerson: Hi. I am Zach Emerson from the 23 National Council for Air and Stream Improvement forthe pulp 24 and paper industry. We call ourselves NCASI. Coau thors on 25

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KAY McGOVERN & ASSOCIATES (919) 870-1600 **Suite 117, 314 West Millbrook Road FAX 870-1603 Raleigh, North Carolina 27609-4306 (800) 255-7886**  this talk are Tim Hunt with AF&PA and Dave Heinold, who just 1 spoke. 2 I'm going to talk a bit today about what are some 3 of the impacts of data handling on modeled impacts. I'm not 4 a modeler. I work in emissions data and emissions measure5 ments. But what we see is that a lot of times as modelers 6 pick up an inventory or pick up emissions data, the y don't 7 consider some of the underlying uncertainty that we nt into 8 that data when evaluating what the impacts are. Sohopefully 9 what I'll talk about today can be useful going forward. 10 I'll talk about some measurement uncertainty and 11 what it is and what it means, and then a specific e xample of 12 measurement uncertainty due to measurements that ar e really 13 close to zero, really close to the detection limit. The 14 example I'll use will be PM2.5emissions from paper machines, 15 and then we'll look at some of the modeled impacts of 16 different decisions on how that data is handled. I 'll talk 17 for a second about emission variability at the end, but I 18 think the next speaker will hit that more. 19 So with measurement uncertainty, measurement-- 20 obviously when you take a measurement, you've got s ome 21 uncertainty in what the actual number is. So if yo u look at 22 measurement at some arbitrary level here--we'll saythat's at 23 the practical quantitation limit, PQL--it will havean 24 uncertainty that's that dotted line. 25

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KAY McGOVERN & ASSOCIATES (919) 870-1600 **Suite 117, 314 West Millbrook Road FAX 870-1603 Raleigh, North Carolina 27609-4306 (800) 255-7886** 

It's a Gaussian line really, and really the error 1 in that measurement is such that you've got 99 perc ent 2 certainty. If you've got a number at the PQL or a number--a 3 result at that number, you've got a 99 percent conf idence 4 that it's under that curve. Each method will have its own 5 curve really, and really every test event will haveits own 6 curve based on how confident you are in the result. 7 You can see as you move this curve closer and 8 closer to the blank level--in this case, we'll callthe blank 9 level zero--then you'll reach a point where this cu rve will 10 overlap with the zero result. The point at which t hat curve 11 exactly hits zero, that's actually what the method detection 12 limit is. That's the point at which you have a 99 percent 13 confidence that your number is statistically differ ent from 14

zero. 15 And this is really the minimum number at which you 16 even know that a pollutant is there. If you're doi ng a 17 measurement for PM and you're below the method dete ction 18 limit, then you have no confidence that PM is actua lly even 19
there. 20 The PQL is another statistically defined term. 21 That's the limit below which you have any confidenc e in that 22
value as a number. Values between the MDL and the PQL, you 23 know it's there or you have 99 percent confidence t hat the 24 material is there, but you don't have 99 percent co nfidence 25

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KAY McGOVERN & ASSOCIATES (919) 870-1600 **Suite 117, 314 West Millbrook Road FAX 870-1603 Raleigh, North Carolina 27609-4306 (800) 255-7886**  in the actual number itself. You just know it's th ere. And 1 these are all kind of classically statistically def ined. 2 So this matters when you've got low pollutant 3 level concentrations. You could see going back tha t there's 4 a spread in that curve, and if you're closer to thelower 5 level, then that spread--the spread is usually a co nstant 6 number, then it's a high percentage of your actual response. 7 So if the level is close to the detection limit, yo ur 8 uncertainty may be 50 percent or higher of your act ual 9
measurement. 10 So as I said, data below the MDL, you can't even 11 say that the pollutant is there. Now, when you're dealing 12 with PM, if you measure long enough, you'll probabl y measure 13 something. You can always get a number if you're measuring a 14 filter or measuring the goo at the bottom of the be aker. 15 So the example that we'll talk about are paper 16 machines. And these are processes that are usuallylocated 17 inside of a building with a lot of different vents. The 18 vents have high flow rates with very, very low conc en19 trations. They're also usually relatively low-- th ey're low 20 relative to boiler stacks, obviously. And they have a high 21 flow rate, low concentration. They're usually rela tively 22 cold. So they can have a pretty high impact on themodel 23
results. 24 Although this kind of analysis really has 25

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KAY McGOVERN & ASSOCIATES (919) 870-1600 **Suite 117, 314 West Millbrook Road FAX 870-1603 Raleigh, North Carolina 27609-4306 (800) 255-7886**  applications for a lot of different kind of sources , a tank 1 farm or some other stuff, anything where the emissi ons levels 2 are thought to be low, and the actual emission sour ce is low 3 or close to the fence line, then it'll--this will matter. 4 Here's some example test data. I hope that you 5 can tell from the colors. So the orange test data, these are 6 all measurements on different vents on a paper mach ine. In 7 this case, there's eight vents although the machineitself 8 probably had more, and they ran for a number of hou rs, and 9 this is the collected mass at the end of that run. 10 So the orange results are all cases where the 11 analyzed mass at the end of the run--this is PM2.5 . I didn't 12 say that. All the measured mass at the end of the run was 13 less than the method detection limit as defined by EPA. And 14
the other results are all cases where the mass was greater 15 than the detection limit, but still less than the P QL. 16 So you can see that for these examples there's one 17
that there's not a lot of mass collected at all andmost of 18 it is less than the detection limit. This is also our--kind 19 of our response because a lot of times when we brin g these 20 issues to a modeler, they say, well, get better dat a. Well, 21 these are cases where we went 8 hours, 4 hours, 16 hours on a 22 paper machine. And this is--it's pretty good data. We 23 just--there's nothing there. 24 So then when you roll all these results up--these 25

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KAY McGOVERN & ASSOCIATES (919) 870-1600 **Suite 117, 314 West Millbrook Road FAX 870-1603 Raleigh, North Carolina 27609-4306 (800) 255-7886**  are all vents on a--say on a single paper machine. When you 1 roll all these results up, you'll get an emission f actor for 2 the machine, which then you figure up what the emis sion rate 3 is. In this case, we'll look at tons per year. Le t's see if 4 I can move that. Okay. 5 So in this case, we took the results from--this 6 says a small paper machine and a large paper machin e. Really 7 that's a small--that's a machine at a small facilit y and 8 machines at a large facility. The large facility-- this is 9 probably four machines here with an annual producti on or a 10 daily production rate of about 1800 tons per day ofeither 11 tissue or linerboard. The small facility would be about 400, 12 I think is the number. 13 So look at, in this case, this tissue and 14 linerboard. So I'll go ahead and direct you for th e tissue 15 machine. If you--this is the impact of different data 16 handling procedures. If you look at the previous data on the 17 previous slide and everywhere that those result les s than the 18 MDL and use the zero, the annual production rate--o r annual 19 emission rate is PM2.5or 1.4 tons per year. 20 For--if you use at the measurement detection 21 level, which a lot of regulators will tell you woul d be what 22 you should do, you would get about 30 tons per year . If you 23 use the detected mass--that is, you use the actual number 24 that's here and that's probably your tester, that's probably 25

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KAY McGOVERN & ASSOCIATES (919) 870-1600 **Suite 117, 314 West Millbrook Road FAX 870-1603 Raleigh, North Carolina 27609-4306 (800) 255-7886**  what they'll do if they give you the result--you'llget about 1 18 tons per year. 2 You can see there's a big spread in the difference 3 here for tissue. It's a lot more dramatic for tiss ue than 4 for linerboard, although it's still--this is a pret ty big 5 difference. If you look between 2.4 and 3.6, that' s still a 6 50 percent difference relative to the data handled with MDL 7 equal to zero. 8 Now, for the large machine, because really all 9 we've done is scaled up the emission--or scaled up the 10 emission rate based on the production, the impact i s about 11 the same. You go from about 6 tons per year to 140 tons per 12 year for the machines at a large facility for a tis sue mill. 13 So why does this matter? Okay. So for--a 14 facility, a paper mill, has a lot of different proc esses. 15 It's got the power to run the unit. It's got the p rocesses 16 to make pulp, to reclaim the chemicals in the proce ss, and 17 then to actually make the paper. 18 The actual emissions associated with--this is a-- 19 these are for the tissue mill. To actually make th e fiber or 20 to--I mean, excuse me, to make the tissue, it's abo ut 8 21 percent of the total emissions for the facility wit h the 22 balance being 92. That comes from power, recovery, and other 23
processes. 24 When you put these into a model facility, and this 25

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KAY McGOVERN & ASSOCIATES (919) 870-1600 **Suite 117, 314 West Millbrook Road FAX 870-1603 Raleigh, North Carolina 27609-4306 (800) 255-7886**  was done by Dave Heinold, because of the--one, beca use of 1 where the machines are and because they're low, the n they can 2 have a pretty big impact on what the actual model r esults 3

are. 4 So the design value concentration--this is the 5 annual 2.5 impact--I've lost my cursor--due to the machines 6 is about 60 percent. So it's a big difference between 8 and 7 60. And one, this is due to the fact that these ar e usually 8 close to the fence line and they're pretty low. 9 So why does this matter? So we've got--these are 10 our model design concentrations for a variety of fa cilities, 11 large and small tissue and linerboard. The purple bars in 12 this graph are the rest of the facility. This is t he fence 13 line impact for annual 2.5 due to the rest of the f acility, 14 and then the bars--the blue, red, and green bars ar e the--due 15 to the paper machine--or due to tissue or paper mac hines 16 under different handling procedures. 17 So the blue bars, if you just took the MDL, used 18 it as zero, or took all the data that's less than t he MDL and 19 used it as zero, you can see that there's a big dif ference 20 between the blue and the green bar. I'll point outthat this 21 is--you go from about 1 to 20. That's bigger than the actual 22 standard. So your uncertainty in the impact is bigger than 23
the standard. 24 So even for a small tissue mill, the impact is 25

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KAY McGOVERN & ASSOCIATES (919) 870-1600 **Suite 117, 314 West Millbrook Road FAX 870-1603 Raleigh, North Carolina 27609-4306 (800) 255-7886**  between less than 1 to about 21⁄2. If you've only go t 2 to 1 begin with between the background and the modeled impact, 2 then that will be important. And the linerboard, a s I said, 3 is--the impact is smaller, although still significa nt. 4 Now, EPA released guidance in 2011--this was a 5 memo written by Westlin and Merrill--taking data fr om the 6 Boiler MACT exercise to figure out what the detecti on limits 7 are, and in that process outlined that you shouldn' t use data 8 that's less than the MDL for anything, really for a ny 9 regulatory action, so we think it's appropriate to kind of 10 exclude it on this basis. 11 I'll talk just a second about emissions 12 variability. I think the next speaker will hit it more. I 13 just want to point out what emissions variability a ctually is 14 when you look at it. When you model at maximum con cen15 tration--this is CEMS data. This is hourly SO 2CEMS data for 16 recovery boilers. It's actually two recovery boile rs ducted 17 to the same stack, so really the variability shouldsmooth 18 out a little bit. 19 The permitted value for this stack is 800 pounds 20 per hour. So the max here that they ever saw was about 800 21 pounds per hour, but the mean was 80. The median was 7. So 22 you can see it's a big impact if you take that permitted 23 value. Even if you take the 99th percentile value, that's 24 still one and a half times--or the max is still oneand a 25

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KAY McGOVERN & ASSOCIATES (919) 870-1600 **Suite 117, 314 West Millbrook Road FAX 870-1603 Raleigh, North Carolina 27609-4306 (800) 255-7886**  half times the 99th percentile value. The 99th per centile 1 value is one and a half times the 95th percentile value. 2 So we think it's still very conservative and very 3 protective to use the 99th percentile or 95th perce ntile 4 emission rate instead of modeling permitted values. And 5 that's not modeling actual. That's still modeling a very 6 high rate relative to where they actually run, but it's just 7 a little more reasonable when you put that into themodel. 8 So some of our conclusions, you can't ignore the 9 uncertainty and measurements. You can't take that number as 10 gospel and pass it forward when you're doing these modeling 11 exercises. As Bob said, the models themselves havean 12 uncertainty or assumed uncertainty of 10 to 40 perc ent, and 13 the measurements probably have at least that. And if you're 14 up against the standard, if you're one over the sta ndard, you 15 really have no confidence that you're actually overor under 16
the standard. 17 So our recommendations are that the update to 18 Appendix W should include some guidance on how to h andle data 19 or the AERMOD implementation guidance should include that, 20 and the guidance should provide some flexibility to 21 regulators and the modelers in how they handle thes e data, 22 especially for measurements that are really low. We think 23 that those measurements should be excluded under pr evious EPA 24 guidance; and also some guidance on how to handle s ources 25

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KAY McGOVERN & ASSOCIATES (919) 870-1600 **Suite 117, 314 West Millbrook Road FAX 870-1603 Raleigh, North Carolina 27609-4306 (800) 255-7886**  that are either intermittent or highly variable. And that's 1 all I've got. 2 Mr. Bridgers: Thanks, Zach. To that end, 3 yesterday, I was always wondering why we were runni ng ahead 4 of schedule. A few of you heard me make the joke t hat it was 5 because we weren't having Q and A. That was the odd thing. 6 We always have that. 7 But the other thing that was oddly different 8 yesterday is there was no clapping. So that was al so just 9 unusual; I guess formal public hearing, or at leastall the 10 public hearings I go to are pretty drab. No offens e to any 11 of the speakers, especially the EPA speakers from yesterday 12 morning. 13 Okay. Bob, are you really on the schedule again? 14 Is Carlos--are you presenting or is Carlos presenti ng? 15 Mr. Paine: We're both presenting. 16 Mr. Bridgers: A tag team; okay, awesome. 17 Mr. Paine: Tag team. 18 Mr. Bridgers: So AECOM is going to offer some 19
comments. 20 Mr. Paine: And ERM. 21 Mr. Bridgers: And ERM, excuse me. 22 Mr. Paine: Okay. I'm back, Robert Paine 23 from AECOM, but I'm going to have Carlos do most ofthe talk. 24 I'm going to--we're going to talk about EMVAP, the Emissions 25

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KAY McGOVERN & ASSOCIATES (919) 870-1600 **Suite 117, 314 West Millbrook Road FAX 870-1603 Raleigh, North Carolina 27609-4306 (800) 255-7886**  Variability Processor, and an application, sort of a hypo1 thetical application of that tool, basically what t his slide 2
says. 3 Especially with very short term ambient standards, 4 the issue of very short term emission rates comes i nto play, 5 and that's what sort of made us design this tool be cause we 6 foresaw this issue back even before the 2010 ambien t 7 standards were promulgated. 8 So intermittent sources do present modeling 9 challenges, and obviously if you assume a peak emis sion rate 10 all the time, we know that you will overpredict theconcen11 trations of a model. Now, the Technical AssistanceDocument 12 for modeling does provide that for existing sources actual 13 emission rates should be modeled. 14 And that reminds me that in the proposal for 15 modeling off-site sources, there are three factors in the 16 proposal, and only one of them has been changed from 17 allowable to actual. They all should be made actua l. There 18 should not be the word "allowable" in that table fo r 19 background sources. So that should be fixed in thefinal 20 proposal, or in the final rulemaking. 21 But now let's go back to EMVAP. We're going to 22 show how an actual distribution of emission rates c an be 23 turned into a way to model the variability of emiss ions in a 24 model. Here's an example of a time series or 8760 hours of 25

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KAY McGOVERN & ASSOCIATES (919) 870-1600 **Suite 117, 314 West Millbrook Road FAX 870-1603 Raleigh, North Carolina 27609-4306 (800) 255-7886**  an emission source. And you can see that the emiss ions can 1 go up to over 130 grams per second on this graph. 2 We turn that into a cumulative frequency 3 distribution in the next graph, and this is what weuse as a 4 tool to provide input to our model because we basic ally put 5 on several boxes, each with a discrete amount of fr equency. 6 What you can do then is you can model each of thoseboxes 7 separately in a model and put them on a shelf, put them on-- 8 and then access those concentrations in a random number 9 generator processor called EMVAP. 10 So the basic--the basic approach is to 11 characterize this emission variability based on act ual data 12 or data from a similar facility and then use that a s a tool 13 to select the concentration in your processor. Andnotice 14 these boxes are such that there's room on top of th ese 15 individual bars so there's some conservatism in theEMVAP 16 processor, also the fact that we--if we randomly se lect the 17 high emissions. 18 Usually high emissions are clustered, and with the 19 form of the standard being, you know, the highest h our of a 20 day, we tend to spread out those high days--those h igh hours 21 over several days in the EMVAP processor. So the 22 conservatism was both in the characterization of th e empty 23 space above those emissions in each box and also th e 24 clustering. 25

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KAY McGOVERN & ASSOCIATES (919) 870-1600 **Suite 117, 314 West Millbrook Road FAX 870-1603 Raleigh, North Carolina 27609-4306 (800) 255-7886** 

So EMVAP is--you may have heard from other 1 presentations is a Monte Carlo model that randomly takes 2 those boxes after you run the model for each of tho se 3 categories and puts the other simulated annualizati ons of the 4 emission--of the concentrations at all the receptor s you'd 5 want to model and then applies the appropriate summary 6 statistics for the one hour SO 2or NO 2standards. You can 7 also take sources that do not vary as separate runs of AERMOD 8 and add those together in EMVAP. 9 You can also--let's go back to this slide on 10 the--if you model the actual emissions and then youcompare 11 the results to modeling EMVAP, you can determine wh at is the 12 percentile of all of your results that would be con servative. 13 And it turns out that the 50th percentile is often satisfying 14 that requirement. 15 So for example if you ran 1,000 simulations, 16 annual simulations, you might get a maximum daily o ne hour 17 result that varies according to this simulation up to 1,000. 18 If you then do a cumulative distribution, we often find that 19 the 50th percentile is conservative relative to modeling 20 actual hourly emissions, and that would be the resu lt you 21 would pick from the EMVAP simulation to determine t he design 22 concentration. 23 The available information on EMVAP is freely 24 available from the EPRI web site. We've seen this link in 25

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KAY McGOVERN & ASSOCIATES (919) 870-1600 **Suite 117, 314 West Millbrook Road FAX 870-1603 Raleigh, North Carolina 27609-4306 (800) 255-7886**  several applications. You can also get SCICHEM forexample 1 from this or the distance debug AERMOD model. We p resented 2 this last year in much more detail at the modeling workshop, 3 and there are peer reviewed journal articles available in the 4 December 2014 issues of both the Environmental Manager and 5
the Journal . I'm going to then provide Carlos for the rest 6 of this presentation. 7
Mr. Szembek: Hello. I am Carlos Szembek. 8 I'm with ERM in the Boston office. And so I'm goin g to sort 9 of talk about a different, an alternative, way of u sing EMVAP 10 from this article that was discussed in the Journalfor using 11 the--for using permitted emission rates to achieve a permit. 12 So just a little history. In the past, EPA 13 guidance has been to have--if you have an averagingtime for 14 an emission rate, it should be the same as the aver aging time 15 of the applicable NAAQS that you're applying it to. Hence 16 the initial approach with the one hour standard was to--for 17 an emission rate that would be also one hour. 18 It was put forward by EPA to have this idea of a 19 critical value, and this critical value would be anhourly 20 emission rate that would be--that would show attainment with 21 the NAAQS. But there is a complication in all of t his. We 22 have--how do you actually use a one hour emission r ate that 23 would actually handle emission--highly variable emi ssion 24
rates? 25

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KAY McGOVERN & ASSOCIATES (919) 870-1600 **Suite 117, 314 West Millbrook Road FAX 870-1603 Raleigh, North Carolina 27609-4306 (800) 255-7886** 

So there were some caveats placed. And EPA 1 expected it's possible for the states to develop co ntrol 2 strategies that would account for the variability i n one hour 3 emission rates. And what was put forth was that th is could 4 be accomplished by actually having averaging times that are 5 longer than one hour but still demonstrate the atta inment of 6 the one hour NAAQS. 7 Okay. So I'll read some of these. EPA expects 8 that any emission limits with an averaging time lon ger than 9 one hour might need to be less than the critical va lue to 10 compensate for the loss of stringency inherent in applying 11 the longer term averaging limit. 12 In terms of variability becoming zero, so constant 13 emissions, the long term average would exceed--woul d equal 14 the critical value. 15 If the frequent emissions above the critical value 16 are sufficiently sporadic, they will have little ef fect on 17 the longer term compliant emission rate. 18 But there's still a challenge, so how to demon19 strate that with an hourly emission variability thelonger 20 term emission rate is still protective of the NAAQS

. 21 EPA has this example for dealing with that. So it 22 seems the variable patterns after the control measu res would 23 still be the same. You would first actually calcul ate what 24 that critical value was, so in this example, 600 po unds per 25

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KAY McGOVERN & ASSOCIATES (919) 870-1600 **Suite 117, 314 West Millbrook Road FAX 870-1603 Raleigh, North Carolina 27609-4306 (800) 255-7886**  hour. 1 You would then analyze your emission distribution 2 and find the 99th percentile of your one hour emiss ions, in 3 this case 800 pounds per hour. You would then obta in the 4 percentage of the--it should be 30 day rolling aver age 5 emission rates, and it would be 720 pounds per hour

. 6 You would then find the ratio of those two 7 numbers, in this case .9, and multiply--use that toscale the 8 critical value to 540 pounds per hour, and that wou ld be a 30 9 day rolling average limit. 10 So EMVAP--the EMVAP approach is an alternative to 11 this EPA approach that actually provides additional 12 confidence in protecting the NAAQS because it actua lly is a 13 modeling demonstration and it encompasses by designthe 14 emission variability. 15 So here I'm going to discuss quickly the stepped 16 process of how to apply EMVAP. Some of these I'll actually 17 go through rather quickly and you can kind of revie w the 18 nuances in the slides later. So--but it's a four s tep 19
process. 20 So first you would actually find the critical 21 value. Then you would--you would analyze your faci lity's 22 emission distribution that will be used in EMVAP an d then run 23 AERMOD to generate inputs into EMVAP, and then fina lly you're 24 ready to run EMVAP to find out what your compliant emission 25

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KAY McGOVERN & ASSOCIATES (919) 870-1600 **Suite 117, 314 West Millbrook Road FAX 870-1603 Raleigh, North Carolina 27609-4306 (800) 255-7886**  rate would be. 1 Okay. So I'm not going to run through all the 2 details here, but this is one way of obtaining the critical 3 value, so this would be a straightforward AERMOD ru n with a 4 constant emission rate that would show compliance w ith the 5 NAAQS. 6 Then you would look at your emission variability. 7 So in this case, you know, you can see it's a highl y variable 8 emission rate. And, you know, here we've marked th e long 9 term average of 97.7 grams per second. And it's wo rth noting 10 that here actually the peak emission rate is more t han twice 11 the long term average. 12 You would then--as Bob showed, you would organize 13 those in a cumulative distribution. And here we ac tually did 14 more gate points to establish the bins that would b e run on 15 these boxed emissions. We've also marked where thecritical 16 value is in relation to these emission rates. 17 Then step 3, and you would actually now take each 18 of those bins that were generated here and have a s eparate 19 AERMOD run that you would then run at just 1 gram p er second 20 and would later be scaled up in EMVAP. 21 And then run--here you would be running EMVAP in a 22 default mode--there was a critical value mode, but in this 23 case you'd be running it in default mode, and usingthat 24 distribution of the boxed bins. And as long as youcan--the 25

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KAY McGOVERN & ASSOCIATES (919) 870-1600 **Suite 117, 314 West Millbrook Road FAX 870-1603 Raleigh, North Carolina 27609-4306 (800) 255-7886**  main issue here is you're confirming that the resul ts at the 1 50th percentile are in compliance with the NAAQS. You can 2 then proceed. 3 And you'll note here that EMVAP adjusts the 4 emissions, that if it didn't work, you would actual ly have to 5 adjust your emissions downward until you showed compliance, 6 so it sometimes can be an iterative process. For t his 7 example, we're assuming that the run actually did s how 8 compliance at the 50th percentile. 9 So what we're showing here is that the long term 10 average is just sort of noted here to show that it' s actually 11 below the critical value that was found. And one t hing to 12 note is that what we're--what we're, you know, high lighting 13 here that there are only three bins that are at or above the 14 critical value. These will actually be--you'll go forward 15 and using those for the permit language. 16 So to kind of generate this coupled short term 17 limit for a hypothetical source, and I'll kind of j ust read 18 through this, with a critical value emission rate o f 120 19 grams per second, suppose the bins at or above 120 grams per 20 second as shown were 200 grams per second with a 5 percent 21 bin width--and so you can see that. That's the tal l, slender 22 one. Then we have--the next bin is 150 grams per s econd at 23 10 percent bin width. And then the third is at 120 grams per 24 second, which is our critical value, and that's als o at 10 25

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KAY McGOVERN & ASSOCIATES (919) 870-1600 **Suite 117, 314 West Millbrook Road FAX 870-1603 Raleigh, North Carolina 27609-4306 (800) 255-7886**  percent bin width. 1 So the remaining lower emission bins have emission 2 rates below the critical values. These actually te nd not to 3 drive the main exceedances of the NAAQS. And as yo u see, as 4 Bob had noted also, you know, again there's conservatism, so 5 there's a lot of area above the curve captured by t hese bins. 6 So for this case the permit language would be as 7 follows. The hourly emission rate will never excee d 200 8 grams per second. The hourly emission rate will beat or 9 above--or at or below 150 grams per second for at l east 95 10 percent of the hours in the long term period. The hourly 11 emission rate will be at or below 120 grams per sec ond for at 12 least 85 percent of the hours in the long term peri od. 13 All right. So the overall conclusions, the two-- 14 the second and third are main take-aways--SO 2and NO 2one 15 hour NAAQS are probabilistic, so EMVAP is consisten t with 16 that approach. It's a probabilistic model. EMVAP can be 17 used with an emission distribution with a rigorous modeling 18 approach to demonstrate that a coupled short term l imit would 19 be protective of a one hour NAAQS standard. And ag ain, 20 here's the source for EMVAP, and our contact information-- 21 four, three, two, one. Okay. 22 Mr. Bridgers: Well played. So we have two 23 more presentations before our first break in the mo rning. 24 Both of these are by CPP, and first up is Ron Peter sen here. 25

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KAY McGOVERN & ASSOCIATES (919) 870-1600 **Suite 117, 314 West Millbrook Road FAX 870-1603 Raleigh, North Carolina 27609-4306 (800) 255-7886**  And I hope this works, Ron. 1 Dr. Petersen: Good morning; Ron Petersen, 2 CPP. I'm going to talk about building downwash, some 3 problems, solutions, and what I perceive as maybe t he next 4 generation downwash model. 5 Basically, why is this important? Well, let's 6 look at--we've got, you know, the needs of society, the 7 environment, industry, and really to have all theseneeds, 8 stakeholders, reach the best decisions, you need anaccurate 9 model. It's someplace in the middle. You want it to be the 10 most accurate so you can make the best decisions. 11 And kind of an overview of some of the problems 12 with building downwash right now, the theory is bas ed on 13 research done before 2000, basically. The originalresearch 14 used a limited number of solid building shapes. 15 Schulman and Petersen at the 10th Modeling 16 Conference presented some information illustrating some of 17 the problems with certain types of buildings, long and wide 18 buildings. The theory is not suitable for porous, 19 streamlined, wide or elongated structures. 20 CPP's evaluation recently has identified some 21 problems in the theory. And there's also some rece nt and 22 past model comparisons with observations that show problems 23 in the downwash arena. 24 So some examples here of these problems from the 25

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KAY McGOVERN & ASSOCIATES (919) 870-1600 **Suite 117, 314 West Millbrook Road FAX 870-1603 Raleigh, North Carolina 27609-4306 (800) 255-7886**  10th Modeling Conference, and Lloyd Schulman presen ted a very 1 interesting talk at that conference, and you can't really see 2 the charts from that, but in summary what he found that for 3 wide buildings he got factors of 3 to 14 increases due to 4 building downwash when the width of the building wa s four 5 times the height. For long buildings, he had conce ntration 6 increases of 4 to 10 when the length was four times the 7 height, and that was at GEP stack. So you were get ting 8 significant concentration increases. He also menti oned an 9 ALCOA field study where the model was overpredictin g by about 10 a factor of 10 for a very long, big building. 11 More recently Keith Baugues at IDEM showed some 12 results where AERMOD was overpredicting by a factorof 2, and 13 also when paired in space and time very poor correl ation with 14 field observations. And again, these were relative ly tall 15 stacks compared to the building, so could we have abuilding 16 downwash problem going on here? 17 A while back AECOM had a field study where they 18 measured concentrations on a nearby high-rise, and the model 19 was overpredicting by about a factor of 10. And wh en 20 equivalent building dimensions were used in place o f BPIP 21 inputs, the concentrations still were higher by a f actor of 22 4. When you actually ran with no building inputs, the model 23 still overpredicted by a factor of 2, which suggest s really 24 in this case the plume was probably escaping the bu ilding 25

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KAY McGOVERN & ASSOCIATES (919) 870-1600 **Suite 117, 314 West Millbrook Road FAX 870-1603 Raleigh, North Carolina 27609-4306 (800) 255-7886**  downwash zone entirely, so due to the plume rise. 1 So, you know, I kind of was thinking what's 2 causing some of these problems. So I got to diggin g into the 3 theory that's in the model formulation document wri tten by 4 Schulman and Scire, and it's based on a technical p aper, so 5 there really is no formulation document. It's a te chnical 6
paper. 7 So why is the model overpredicting? We've 8 got--one of the problems, we create these artificia l 9 buildings. You can see the blue shape there. That 's the 10 building in plan view. BPIP creates that gray buil ding 11 that's much longer than the real building. 12 And so what happens, the wake starts growing much 13 further upwind. And the point that we're going to have the 14 maximum turbulence occurs much further downwind tha n the real 15 situation. So you're really having the wake being 16 characterized incorrectly in the model. 17 Some of the turbulence calculations in the wake 18 are flawed. And I'm not going to--I just have the equations 19 there for reference and documentation, but they're in the 20 paper. Basically what the model is assuming is tha t the 21 turbulence enhancement, or the building downwash in crease, is 22 constant all the way up to the top of the wake. An d that's 23 really an unrealistic assumption. And it's making an 24 assumption of uniform approach flow, constant wind field with 25

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KAY McGOVERN & ASSOCIATES (919) 870-1600 **Suite 117, 314 West Millbrook Road FAX 870-1603 Raleigh, North Carolina 27609-4306 (800) 255-7886**  height. 1 This is kind of what we found here. The top slide 2 shows what's going on in PRIME. And you've got thewake 3 growing. You can see that white line. That's the calculated 4 wake height. And the enhanced turbulence doesn't s tart until 5 the lee end of the building where the red zone is. So the 6 maximum turbulence starts occurring right at the downwind 7 edge of the building, and it goes all the way up tothe top 8 of the wake, which is the white line. 9 What we found in reality is that the enhanced 10 turbulence zone really doesn't go much above the top of the 11 building, and it decreases quickly back to ambient levels. 12 So this can explain why some of these taller stacks are 13 getting higher numbers. They shouldn't be really impacted 14 much by the high turbulence in the wake zone. 15 Another problem that we found in this area is that 16 under stable stratification the turbulence in the wake is 17 enhanced by a factor of 10, while under neutral con ditions, 18 it's only enhanced by a factor of about 5.7, unstab le by 19 about a factor of 3. And so that really is not--th ere's no 20 evidence supporting this relationship is a functionof 21 stability. Everything that was done was done underneutral 22 conditions to develop the theory. 23 We did a little limited research on our own at 24 CPP, put in a building, a 1:1:2 building, which mea ns it's 25

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KAY McGOVERN & ASSOCIATES (919) 870-1600 **Suite 117, 314 West Millbrook Road FAX 870-1603 Raleigh, North Carolina 27609-4306 (800) 255-7886**  two times as long as its height and its width is th e same as 1 its height. We measured the turbulence enhancementin this 2 plot. What you see here on the horizontal axis is the 3 turbulence increase is a function of distance downw ind of the 4 building. You can see that black object there. 5 And the maximum turbulence enhancement you can see 6 is below the top of the building where that value o f 1 is. 7 Above the top of the building you have very little turbulence 8 enhancement. It goes back to ambient very quickly, so kind 9 of supporting that little chart I showed you based on wind 10 tunnel measurements. And the decay of turbulence e nhancement 11 is much quicker for this particular building than t he theory. 12 We also did some large eddy simulation runs using 13 CFD. And--well, that should have been running, but --let's go 14 back to that. Yeah, you can see the blue there is the 15 velocity deficit zone in the wake of that building, and you 16 can see it kind of confirms the wind tunnel measurements. 17 It's the same building basically that we simulated in the 18 wind tunnel. And it shows most of the turbulence e nhancement 19 or velocity deficit is occurring below the top of t he 20 building. 21 So what are the problems we found in the downwash 22 model? The streamline calculation comparison that' s in the 23 model formulation document--when we went through th e 24 calculations the example showed the streamlines goi ng 25

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KAY McGOVERN & ASSOCIATES (919) 870-1600 **Suite 117, 314 West Millbrook Road FAX 870-1603 Raleigh, North Carolina 27609-4306 (800) 255-7886**  downward. When we actually followed the procedure in the 1 manual, we calculated they should all be going hori zontal, so 2 there seems to be some problem in what's written inthe 3 document, so I'm not really sure what the model is actually 4 doing for that case, but the example doesn't match what's in 5 the paper. 6 The second one is there's a discontinuity in the 7 streamlines right at the leading edge of the buildi ng. Right 8 there in that figure where you see the zero on the building 9 there's a discontinuity. Right at zero the slope i s a factor 10 of 4, and immediately upwind of that is a factor of2. So 11 there's a factor of 2 change in the trajectory of t he plume 12 right at that point. 13 Another weakness is the streamlines for all 14 structures are calculated assuming the buildings ar e solid. 15 So like a lattice type structure where the flow goe s through 16 it--you know, oil platforms, things like that--the flow will 17 more likely be horizontal. A real quick fix to tha t would be 18 to change the streamline calculation in the model t o be 19 horizontal, and that would improve model performanc e 20 dramatically for that situation. 21 The top picture is a lattice structure. The 22 middle one, no structure, and you can see is very s imilar to 23 the lattice structure. And the bottom one is what it looks 24 like in AERMOD. It assumes a solid building. 25

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So the solutions really to these problems--the 1 short term fix really is--one that's being used cur rently is 2 equivalent building dimensions where you do a wind tunnel 3 study to find the building dimension to input to ge t the 4 correct dispersion. 5 I should mention that even that is not fixing the 6 problem completely because, as you notice, there ar e some 7 theoretical problems, so even with the equivalent b uilding 8 dimension you're going to tend to overestimate the 9 concentrations for the reasons I just went through. 10 So really the next generation is to develop an 11 improved AERMOD model, which actually--or which act ually this 12 would be the PRIME algorithm, which also is in SCIC HEM, and 13 you would have to do some modifications to BPIP tooto make 14 everything work correctly. 15 To do this, you'd really need a collaboration 16 between EPA and industry to get this done in a quic k manner, 17 and it's something that I really think should be do ne outside 18 of the current regulatory framework. It's just something 19 that should be done to improve the model. Current science-- 20 as was mentioned earlier, we need to advance the st ate of the 21 science. That should be the goal of all us here. 22 The short term fix, as I mentioned, is equivalent 23 building dimensions. Those are fairly expensive, t ime 24 consuming, but that is a tool that can be used in t he interim 25

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KAY McGOVERN & ASSOCIATES (919) 870-1600 **Suite 117, 314 West Millbrook Road FAX 870-1603 Raleigh, North Carolina 27609-4306 (800) 255-7886**  to give better predictions. 1 If you find you have a problem--lattice 2 structures, long buildings--really the only fix right now is 3 equivalent building dimensions, because right now f or these 4 types of structures--hyperbolic cooling towers let' s say--the 5 model is overpredicting by a factor of 2 to 4, 4 to8 for 6 short buildings with a large footprint, 2 to 3.5 fo r lattice 7 structures, and 2 to 5 for very long, narrow struct ures. So 8 currently the model has some significant overestima tes going 9 that the only way to correct is through a wind tunn el 10 modeling study at the current time. 11 So of course why does--equivalent buildings don't 12 solve the problem, they do help a little bit, but why do they 13 help? You can see this picture here on the bottom is a very 14 long structure. You can see the high turbulence zo ne right 15 at the lee edge of the building, so a plume could h it and go 16 off that building, immediately hit that zone, be mi xed with 17 the ground. That's kind of that yellow color in th e picture. 18 The equivalent buildings we usually find are much 19 shorter, and so the wake height is much shorter, wh ich means 20 when you put that into the model, even though you'r e still 21 intersecting the wake zone incorrectly, the concent rations 22 hit further downwind or lower. So it is an improvement, but 23 even if the model were fixed, you'd even get lower concen24 trations than using EBD. 25

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Kind of just another picture, this is the BREEZE 1 downwash analyzer that we can kind of visualize wha t's going 2 on with the building. It kind of shows the buildin g and then 3 the BPIP input, which is in blue, and you can see h ow much 4 bigger the building is. 5 Well, we ran that case in AERMOD just to see what 6 it looked like with this building and then with an equivalent 7 building, and here's kind of what the plumes look l ike close 8 in. You can see the real building, that blue line there is 9 the wake, top of the wake, and you can see the plume, 1 10 sigma-z, how much wider it is than with the equival ent 11 building, the top picture, because on the top pictu re the 12 plume is just slightly above the top of the wake, s o you're 13 getting very little enhancement in the plume, furth er 14 illustrating what I was saying here how the model i s 15 overestimating the enhanced dispersion downwind of the 16 building. 17 Of course, there are cases where the model is 18 underpredicting, so you really need to--you know, f or a 19 sustainable type of situation, you want to cover everything. 20 You've got to make good decisions, bad, or--you know, 21 overpredictions, underpredictions, whatever. You've got to 22 go both ways. 23 The corner vortex is an issue where the model is 24 probably underestimating by a factor of 2. Upwind terrain 25

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KAY McGOVERN & ASSOCIATES (919) 870-1600 **Suite 117, 314 West Millbrook Road FAX 870-1603 Raleigh, North Carolina 27609-4306 (800) 255-7886**  effects are not in the model either. And the modelis 1 probably underestimating by a factor of 2 to 6 for that 2 situation. So these are all things that could be developed. 3 These latter two are probably more complex or are g oing to 4 take a little more research, but the ones that we t alked 5 about first are pretty easy fixes. 6 So what do we do? Correct the bugs, fix the known 7 problems, incorporate the current state of the scie nce. We 8 need to advance the state of the science, expand th e types of 9 structures that can be accurately handled. 10 We really need a well documented and verified 11 model formulation document and code for PRIME, and a section 12 needs to go into Appendix W that we can update thin gs quickly 13 and create collaboration with industry and EPA to k ind of 14 move on this path forward to develop a more accurat e building 15 downwash model. Thank you. 16 Mr. Bridgers: Thank you, Ron. And for our 17 last presentation before the break, we have Sergio. 18 Dr. Guerra: Thank you very much; Sergio 19 Guerra with CPP. In the last two presentations, we 've seen 20 new understanding of the science, and it's very imp ortant for 21 us to figure out how we can incorporate that into t he model 22 as soon as possible so that we can continue advanci ng the 23 science. 24 I'm going to be covering background concentrations 25

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KAY McGOVERN & ASSOCIATES (919) 870-1600 **Suite 117, 314 West Millbrook Road FAX 870-1603 Raleigh, North Carolina 27609-4306 (800) 255-7886**  and the need for a new system to update AERMOD, so we're 1 going to go through what is in the guidance right n ow related 2 to background concentrations, an alternative approa ch, and 3 then going to Appendix W, what have we learned and what would 4 be a new method to go forward. 5 So going to the draft guidance, Section 8.3, there 6 are a few options that you can use to get your background 7 concentrations. You can--if you have a source thatis 8 impacting the monitor, you can exclude the 90 degre e downwind 9 sector from the source in question, and that was--t hat's in 10 the current guidance and it's also in the proposed. 11 The second one is a new one. You can modify the 12 ambient data record with monitor--when the monitor is 13 impacted by unusual events. I call them exceptiona l events, 14 but these are things like the Canadian forest fires , like 15 construction, things that are not reasonably contro lled that 16 can be excluded for other purposes in designing con centration 17 calculations. You can do that by removing hourly o r daily 18 data or you can do it by scaling or adjusting, basi cally 19 multiplying by a factor or adding or subtracting. 20 The guidance also talks about pairing monitoring 21 and modeled data on a temporal basis. You can do i t by 22 season, by hour of day, and on rare occasions on li ke the 23 paired sums approach, on an hour by hour basis. An d then the 24 fourth way is you can use a regional scale photochemical grid 25

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KAY McGOVERN & ASSOCIATES (919) 870-1600 **Suite 117, 314 West Millbrook Road FAX 870-1603 Raleigh, North Carolina 27609-4306 (800) 255-7886**  model to give you the background that you can use. 1 The first one, the 90 degree downwind sector, this 2 is some peer reviewed research done by Doug Murray and 3 Michael Newman, and they did exactly that for the K incaid 4
database for SO 2and SF 6 . And what you would expect is that 5 when your downwind--your receptors are downwind from the 6 source, you would exclude all those receptors and j ust take 7 the receptors around it. 8
In the case of SF 6there is nothing else that 9 would contaminate those samples. However, we found --or what 10 was found in this research is that the 99th percent ile for 11 example for SF 6is 247, and then outside of the sector you 12 still have 188. So it's a good idea, but unfortuna tely it 13 does not work. Winds are not stable enough, and yo u do have 14 some impacts outside of that 90 degree sector downw ind of 15
your source. 16 Excluding unusual events--I have to commend EPA. 17 I've been talking about this for a while, you know, that we 18 shouldn't be including exceptional events on the da ta set 19 that is used to calculate the background. And EPA kind of 20 responded to that by the draft guidance. 21 This is a satellite image from I think June 29 of 22 this year when all these forest fires were basicall y coming 23 down into the U.S. through Minnesota. In fact Minn esota had 24 a lot of--along with other states had a lot of heal th type of 25

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KAY McGOVERN & ASSOCIATES (919) 870-1600 **Suite 117, 314 West Millbrook Road FAX 870-1603 Raleigh, North Carolina 27609-4306 (800) 255-7886**  events due to these forest fires. I was not in Min nesota at 1 the time, but even in Fort Collins we got the effec ts from 2 this plume. They say that you can run but you can' t hide, so 3 that's what happens in some of these exceptional events. 4 But why do we care about these exceptional events? 5 We care about these exceptional events because theybasically 6 make a normal distribution be skewed, be stretched to the 7 right like you can see here. And when you stretch that 8 distribution you basically pull with it all your pe rcentiles. 9 So whereas your 98th percentile in normal 10 distribution might be 5 micrograms, when you have a n excep11 tional event, that pulls the whole distribution to the right 12 and it may be 10 micrograms, 50 micrograms. 13 This is from a peer reviewed journal article that 14
I wrote for PM2.5showing that same trend. And as you can see 15 here, anything above maybe 20 is statistically an o utlier. 16
For NO 2I did the same thing and we see the same pattern. 17
And for SO 2I guess that's the most dramatic where you have 18 very few observations that are really, really high, that are 19 really pulling that distribution to the right and making the 20 98th percentile, or the 99th in the case of SO 2 , be much 21 more--much higher than what it would be normally. 22 Another thing that you have to consider here is 23 that you need met data in order to address some of the--in 24 order to subtract those days that are impacted by e xceptional 25

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KAY McGOVERN & ASSOCIATES (919) 870-1600 **Suite 117, 314 West Millbrook Road FAX 870-1603 Raleigh, North Carolina 27609-4306 (800) 255-7886**  events or unusual events. But in many cases we do not have 1 that. We have a monitor, but we do not have met da ta or a 2 met station that is close by or representative. Soan 3 alternative method is necessary when there's no metdata 4 available. 5 Now, let's talk about temporal pairing. This is 6 the current Section 9.1, Model Accuracy, and it bas ically 7 says that models are more accurate for the annual s tandard 8
than for the one hour standard and that we are reas onable in 9 knowing the magnitude of the highest concentration, but we do 10 not know the exact time or the exact location of it

. 11 This is absent from the guidance as far as I could 12 tell, and I think that if there's evidence to the c ontrary 13 that this is not true anymore, that evidence shouldbe 14 released to the public. Otherwise, it should be in cluded so 15 that we know basically what are the limitations of the model 16 and we can use the model correctly. 17 This is what a perfect model would do on an hour 18 by hour basis. You have one monitoring observationthe first 19 hour, and if you have a receptor at that hour you c ompare the 20 two and if they give you the same number, it would create 21 this 45 degree angle, this 1 to 1. However, this i s what we 22 find in real life. This is again the Gibson genera ting 23 station, a peer reviewed journal, Kali Frost. 24 And it's showing two things: first, that that is 25

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KAY McGOVERN & ASSOCIATES (919) 870-1600 **Suite 117, 314 West Millbrook Road FAX 870-1603 Raleigh, North Carolina 27609-4306 (800) 255-7886**  not following that pattern, so basically there is n o 1 relationship between the monitored concentrations a nd the 2 predicted concentrations. And the second thing is that--a 3 little bit more troublesome--is that when the monit or is 4 showing really high concentrations, the model is sh owing very 5 low and vice versa. So when we do pairings in timeand 6 space, you have to keep this in mind, are you compa ring the 7 right values or not, and according to this it's notthe case. 8 This is the same article that I showed by Doug 9 Murray and Mike Newman, and it shows the same patte rn for a 10 different station for the Kincaid database. And th en they 11 took it a step further and said, well, let's just p air them 12 in time, basically any receptor. Let's try to see if any of 13 the receptors match with the monitors, and it just had like a 14 slight improvement, but obviously that pattern is n ot correct 15 like it should be. 16
So how do we evaluate AERMOD? Most of us are used 17 to seeing something like this. These are Q-Q plots . You 18 rank them from highest to lowest and you compare th e highest 19 on the monitor with the highest with the model and then the 20 second highest with the second highest and somethin g like 21
that. 22 So basically you compare them. You uncouple them 23 from time and space. And that's how we evaluate th e model 24 because it's probabilistic also in that sense. We are 25

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KAY McGOVERN & ASSOCIATES (919) 870-1600 **Suite 117, 314 West Millbrook Road FAX 870-1603 Raleigh, North Carolina 27609-4306 (800) 255-7886**  looking at the probability of having an exceedance somewhere 1 at some hour throughout your evaluation study and e valuation 2 time. So basically temporal matching is not justif iable 3 based on the information that I've seen, so it shou ld be 4 avoided. 5 And just a word about the photochemical grid 6 model, it's something that--it's a complete differe nt 7 scaling, complete different parameterization, diffe rent 8 assumptions, chemistry. 9 So we're not comparing apples to apples; it's like 10 apples to oranges, watermelons. They are very diff erent, so 11 I think we should reconsider that, and even some ofEPA 12 guidance says that we should take photochemical gri d models 13 in a relative fashion, and you know, sort of rememb er we 14 looked at this at some point--well, let's use thesedata for 15 background. And we couldn't use it because it was way, way 16 higher than the standard itself. So I think this might not 17 be ready for prime time yet. 18 An alternative to pairing background and predicted 19 concentrations--if we look at the probability of th ese two 20 events happening, the 98th worst concentration fromthe model 21 happening at the same time as the 98th worst concen tration 22 from your monitor, the probability is equal to the product of 23 both probabilities, in this case .02 times .02, as long as 24 both distributions are independent from each other. 25

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And as I showed earlier, if we had something like 1 a 45 degree angle pattern to the data, we could saythat 2 there is, but there really isn't. So in this case we had 3 .0004 probability or a 99.96 percentile combined pr obability 4 of those two events happening at the same time. Th is is 5 obviously more conservative than the model if you do it for 6 the 99th percentile, and it's also one exceedance e very 27 7
years. 8 So I've been advocating for the 50th percentile. 9 I'm glad to hear that for EMVAP it's working as wel l. But 10 the 50th percentile is a good measure because it's not 11 heavily influenced by these exceptional events. It 's more 12 toward the middle of the concentration and it's sti ll 13 conservative because it's being pulled just like th e other 14 percentiles. So when you look at that, the combine d 15 distribution and the combined probability is even more 16 conservative than the form of the standard. 17
But now let's talk about the Guideline on Air 18 Quality Models . It was published in 1978 and its purpose was 19 to streamline and to create consistency across the country 20 and across industry, basically one model for everyo ne to use. 21 The critics back then said that the rigidity of therules 22 would inhibit innovation and would render the Guidance 23 obsolete as technology and science advanced. 24 It was a very heated argument, from what I 25

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KAY McGOVERN & ASSOCIATES (919) 870-1600 **Suite 117, 314 West Millbrook Road FAX 870-1603 Raleigh, North Carolina 27609-4306 (800) 255-7886**  understand. It was very controversial at the time. I was 1 not there. I was only 2, so I did not know enough about 2 dispersion modeling, but nonetheless there is a rec ord of it. 3 So what I'm proposing is in line with what the APM 4 Committee has proposed, the establishment of a Tech nical 5 Review Advisory Committee, TRAC, with the ability t o 6 evaluate, approve, and incorporate new methods with out the 7 need to undergo a long and infrequent rulemaking pr ocess. 8 TRAC would be composed of the leading experts from 9 EPA, industry, and academia with one purpose, to evaluate new 10 dispersion modeling techniques and incorporate scie ntifically 11 valid methods to the regulatory model in an expedie nt manner. 12 The APM Committee from the Air and Waste Management 13 Association can provide a good framework for TRAC. 14 And why do we need to do this? Well, first of all 15 because of timing. Updates to the guidance requirea long 16 and complicated rulemaking process. I mean it's ta ken us ten 17 years to come here again. Current system results i n a 18 lengthy time gap between the proposal of new and advanced 19 techniques and their implementation for widespread use. And 20 again, the current mechanism does not allow for an expedient 21 update of the model to incorporate fixes that we ar e finding 22 like Dr. Petersen mentioned about downwash or new t echniques. 23 Now, let's talk about the rulemaking process. To 24 keep up with the new methods and science, EPA was s upposed to 25

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KAY McGOVERN & ASSOCIATES (919) 870-1600 **Suite 117, 314 West Millbrook Road FAX 870-1603 Raleigh, North Carolina 27609-4306 (800) 255-7886**  update the guidance through the rulemaking process, basically 1 through the formal public comment. Instead it gaveus--and 2 again, it's really hard because EPA has their platefull and 3 they have a lot of responsibilities on top of that, so this 4 is really stretching them to the limit. 5 So instead what EPA has done is issued nonbinding 6 guidance or technical assistance--technical assista nce 7 documents without formal evaluation or public invol vement. 8 However, as the courts have said, if you have a nonbinding 9 document that dictates what you have to do in orderto get a 10 permit, for all practical purposes that document is binding. 11
So that's from the Appalachian Power v. EPA , D.C. Circuit, 12 2000. 13 But in reality--the court is another thing, you 14 know, but what we have really done is we have circumvented 15 the evaluation process that is supposed to go into the model, 16 and many times we make changes to the model with go od 17 intentions that end up having very unfortunate typeof 18 situations or results. 19 The other thing is we need to take action because 20 it might take ten years to update the guidance agai n, so we 21 need to do this right now. The science is constant ly 22 evolving and we need to make sure that we promote t he science 23 so that we can incorporate it and we can improve itevery 24 time more and more. 25

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And we need to recognize also that the current 1 system is not working. It's not working for EPA. It's not 2 working for industry. It's not working to protect the 3 environment. And all the stakeholders need to takecharge of 4 this and be involved and collaborate because only b y 5 collaboration can we do something. We cannot wait another 6 ten years to see what happens. 7 And then one of the main things is create 8 consistency. For example there are some beta optio ns in 9 AERMOD, but at the same time there are many updates that have 10 been made to the model. AERMOD was updated 11 time s, 11 AERSCREEN five times, AERMET six times, AERMAP thre e times, 12 AERMINUTE three times. AERSURFACE even got its update. 13 BPIP, like Dr. Petersen mentioned, hasn't been upda ted, but 14 we're working on that. 15 And then another thing is there have been updates 16 that have been enhancements like when we did not have a form 17 of the standard that the model could give you, thatwas a 18 very welcome enhancement. But there have been alsobug fixes 19 that are necessary, but there have been miscellaneo us changes 20 such as the change on calculating downwash above GE P stack 21 height, that whereas it is true that there is downwash at 40 22 percent, what Dr. Petersen showed is that the downwash is 23 being overstated, so there was not a proper evaluat ion to 24 identify this problem and now we've created anotherproblem 25

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KAY McGOVERN & ASSOCIATES (919) 870-1600 **Suite 117, 314 West Millbrook Road FAX 870-1603 Raleigh, North Carolina 27609-4306 (800) 255-7886**  by trying to fix a problem. 1 So basically it's not clear what changes can be 2 made by EPA and what changes need to wait until therule3 making process. That's why we need something like the TRAC 4 that I'm promoting. 5 And basically the Technical Review Advisory 6 Committee would promote collaboration, share respon sibility 7 among all the stakeholders, result in a more effici ent 8 process and improve the timing of implementation ofthe 9 science into the model. And this will create consi stency, 10 which is the goal of the model--of the Appendix W, excuse me. 11 So again, the APM Committee from the Air & Waste 12 would be the ideal framework because the major players are 13 part of it already, and as technology and science a dvance we 14 need to evolve with it and we need to make sure tha t we can 15 lead again, you know, because in this case we've se en models 16 like ADM like used in Europe that are basically hav ing better 17 science than the one that we have here. So let's p rove the 18 critics of 1978 wrong and let's update Appendix W s o it can 19 work efficiently, as it was intended. 20 And in 30 seconds I have a summary of my comments. 21 I'll just say about the 90 degree downwind sector, that's not 22 solving the problem, unfortunately. Unusual events need to 23 be excluded from the monitoring data and we need tomake sure 24 that we provide enough tools so that we can do thatin an 25

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KAY McGOVERN & ASSOCIATES (919) 870-1600 **Suite 117, 314 West Millbrook Road FAX 870-1603 Raleigh, North Carolina 27609-4306 (800) 255-7886**  efficient way. 1 The use of the 50th percentile that I've been 2 advocating for is one of those options that should be 3 considered. And then the statement about model acc uracy for 4 long and short term averages should remain in the updated 5 guidance, and otherwise evidence should be providedthat it's 6 no longer valid. 7 And the temporal matching is not justifiable 8 because AERMOD's accuracy is suspect on a temporal basis. 9 And background values from photochemical grid model ing should 10 be reconsidered until we know for sure that it's something 11 that is technically feasible. 12 And again, the main thing right now is we need to 13 form a Technical Review Advisory Committee with theability 14 to evaluate and approve any changes to the model be cause 15 that's an urgent need at the time. Thank you very much. 16 Mr. Bridgers: Thank you, Sergio. So we have 17 reached the point of our first break. What I do wa nt to 18 say--I'm not going to talk for five minutes to fillthe time, 19 but what I am going to say, there's going to be some 20 changes--slight changes to the agenda right before lunch. 21 We have received two requests for additional 22 presentations that would be given, quote, during th e oral 23 comments. And so I'm going to have those two prese ntations 24 right before lunch, and then we'll have the open fo rum 25

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KAY McGOVERN & ASSOCIATES (919) 870-1600 **Suite 117, 314 West Millbrook Road FAX 870-1603 Raleigh, North Carolina 27609-4306 (800) 255-7886**  immediately following lunch, and so that's just shi fting that 1 just a little bit. And that way for folks that happen to 2 need to leave at lunch for an airplane flight or wh atnot, 3 they'll see all of the PowerPoint presentations tha t are 4 going to be given. 5 And so with that, it is 10:00. I'm going to 6 adjust the time, so we need to be back at 10:20. T hank you. 7 (A recess was taken from 10:02 a.m. to 10:20 a.m.) 8 Mr. Bridgers: So thank you for everybody 9 coming back after the break. We're going to jump r ight into 10 the presentations. Oh, just a real quick note. I know that 11 there are some in this room that are looking for ri des to the 12 airport. And so there's a white drawing board overhere that 13 the ride list is starting to form, so if there are extra 14 spots in cars that are going over to the airport, you know, 15 see if you might help some of your colleagues. 16 Next up we have David Long. And David, I'll let 17 you present your topic. 18 Mr. Long: Good morning. My name is David 19 Long. I am an engineer with the American Electric Power 20 Service Corporation, which is the technical service s 21 organization for American Electric Power. And this morning 22 I'm going to talk about the use of data collected b y the 23 Clean Air Markets Division, or CAMD for short, in i ts 24 application to air quality modeling. Under the onehour SO 2 25

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KAY McGOVERN & ASSOCIATES (919) 870-1600 **Suite 117, 314 West Millbrook Road FAX 870-1603 Raleigh, North Carolina 27609-4306 (800) 255-7886**  standard, we're seeing a lot of this data source tr ying to be 1 used, and there are issues with this data simply be cause of 2 its design. 3 When the 1990 Clean Air Act amendments were 4 passed, EPA was told to develop a program for monit oring S0 2 5
and NO xfrom the utility industry as part of what was known 6 as the--what's known as the Acid Rain Program. Thi s data was 7 intended when it was put together as an accounting program 8 for the use and consumption of allowances that wereassigned 9 to the various electric generating units. The data 10 management system is therefore set up to overstate emissions 11 if there's any errors in measurements. 12 And the regulations implementing this monitoring 13 program are found in 40 CFR Part 75. And they do g o into a 14 great deal of detail on how the monitoring systems are to be 15 operated and what data is to be collected and repor ted. 16 Most of the data in CAMD is an hourly database, 17 which for an hourly program people look at it and s ay, 18 "Wonderful, we have hourly data." And the typical data 19 that's reported includes gross load on the generati ng unit, 20 typically in megawatts, but not all sources reporte d 21 megawatts; SO 2emitted in both pounds per hour and ppm; NO x 22 emitted in pounds per hour, pounds per million Btu and ppm; 23 stack flow rate in standard cubic feet per hour, an d that's a 24 critical issue that it's standard cubic feet; a dil uent gas, 25

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KAY McGOVERN & ASSOCIATES (919) 870-1600 **Suite 117, 314 West Millbrook Road FAX 870-1603 Raleigh, North Carolina 27609-4306 (800) 255-7886**  CO 2or O 2 , so you're not always going to have CO 2data, but 1 with some of the changes coming based on the Clean Power 2 Program, CO 2probably will be added to the mandatory list; 3 and then a calculation of heat input in million Btuper hour. 4 Obviously with all the data that's been collected 5 over the past 20 plus years and reported, there's amassive 6 database out there, and it isn't overall terrible data. For 7 Part 75 purposes in fact it's very good data. 8 However, when we've tried to apply this to one 9
hour SO 2where trying to get an accurate picture of the 10 emissions impacts on an hourly basis, the data have --we start 11 to find the shortcomings in the accounting program reporting. 12 One of the other problems we have is for modeling 13 to get the plume height correct, we need hourly temperatures 14 to temporally match up with the flow rates and to b ack those 15 standard cubic feet per hour values into actual cub ic feet so 16 the velocities are correct. 17 Guess what we don't have to report? Temperature. 18 Even though the data is captured because we have touse it to 19 take the actual cubic feet that is typically measur ed by the 20 CEMS systems and converted into standard cubic feet , CAMD 21 doesn't require us to report temperatures at this t ime. In 22 order to get the modeling accurate, you need accura te 23 temperature data, so that's another shortcoming. 24 Another shortcoming, as I mentioned earlier, this 25

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KAY McGOVERN & ASSOCIATES (919) 870-1600 **Suite 117, 314 West Millbrook Road FAX 870-1603 Raleigh, North Carolina 27609-4306 (800) 255-7886**  was set up as an accounting program. There are ext ensive 1 missing data substitution--invalid data substitutio n 2 protocols in Part 75. Basically you get a value every hour 3 regardless of whether the CEMS are working correctl y or not, 4 and it may be substituted. 5 There are flags when data is substituted or even 6 when it isn't to tell you that this is actually wha t the CEMS 7 system read. When you go to CAMD and request an ho urly data 8 set from them, you don't get the flags typically un less you 9 specifically ask for them. 10 So you're looking at this massive list of hourly 11 flows and hourly emissions, and how much of it's ac tually 12 what was measured and how much of it was actually s ubstituted 13 and may be substituted using any number of differen t 14 protocols you can't tell just looking at the basic data set 15 CAMD issues. And to find some of that, you either have to 16 get into the flags themselves or go down to the sen sor level 17 data that is actually reported. 18 Now, one of the things that also is included in 19 the CAMD data--and again, for accounting purposes, it's 20 what's called a bias adjustment factor. Bias adjus tment 21 factors by their definition in Part 75 cannot go be low 1.0. 22 And these are based on RATA tests on the CEMS systems that 23 are done annually or semiannually depending on the accuracy 24 determined during the most recent RATA. 25

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If the monitor is reading below the actual value 1 and you flunk the calculation for bias, you then pu t in a 2 bias adjustment factor on the monitor data greater than 1. 3 If it goes the other way where the monitor is readi ng higher 4 than the test method, you don't go below 1. It sta ys at 1 so 5 you're again overstating emissions and consuming a few extra 6 allowances under the accounting rules that were setup. It 7 doesn't help us, though, a lot if we're trying to g et 8 accurate representation of emissions from the unit. 9 Another issue that I've hit on several times 10 already, temperature data. We don't have that in t he CAMD 11 data. One of the interesting parts is for units th at use dry 12 control technologies, the temperatures vary much mo re wildly 13 than you set on wet scrubbed units, although you dosee 14 temperature variations there too, and those can--an d that can 15 affect the plume performance in the model. 16 Temperature for the modeling studies, you can 17 obtain it from several sources. One would be a sta te 18 permitting or an inventory database. However, the 19 temperature you get there is typically a single val ue and 20 it's based on full load operating conditions that don't 21 necessarily represent the hourly variation and unit 22 operation. So you have no guidance on how to adjus t the flow 23 rates back from standard conditions to actual condi tions 24
based on that data source. 25

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You can also go back--and one of the things that 1 we've been doing with the data we've been putting t ogether 2 for the various state agencies we've been working w ith is we 3 pull the sensor level data, where we do get the hou rly values 4 that were used to adjust the actual measured flows back to 5 standard, and then we can bring them back up to theactual 6 flow rates and get a more accurate representation o f the exit 7 velocities for the model. You know, obviously how you 8 recognize the temperature data can impact the exit velocity 9 and lead to improper dispersion if you don't get itright. 10 Flow calculations: now, here we see how the bias 11 adjustment factor comes into play. You know, the b ias 12 adjustment factor is applied to the flow sensor dat a, not to 13 the temperature data, the flow sensor. So if the f low sensor 14 was determined to be reading low, it gets raised, a nd in this 15 case it's probably an appropriate increase. But ifthe 16 sensor is reading slightly high, it doesn't go downand that 17 can introduce some error into the calculations. 18 Emissions, and I do have a slight error in this 19 equation. I'm just showing a single application ofthe bias 20 adjustment factor, and it's actually applied to bot h the 21
value of the SO 2concentration and to the flow individually, 22 not as a single factor on the emission. 23 So you can get into a situation where if you have 24 an error with--or I shouldn't say an error, but a b ias 25

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KAY McGOVERN & ASSOCIATES (919) 870-1600 **Suite 117, 314 West Millbrook Road FAX 870-1603 Raleigh, North Carolina 27609-4306 (800) 255-7886**  adjustment on both the flow and the SO 2 , you can 1 significantly increase the emissions possibly in wa ys that 2 aren't completely realistic. And again, if there's 3 substituted data, it occurs at the sensor level, no t at the 4 emissions level. And substitutions can be very int eresting. 5 If you have just a limited amount of missing data, 6 typically the technique that is used is called hour 7 before/hour after, which if the unit is sitting the re 8 operating in a stable mode, it's probably going to be a 9 pretty accurate estimator of what happened during t he hour or 10 two of missing data. If the unit isn't stable beca use the 11 load is being shifted, it's hard to say how that wo uld impact 12 you. But the impacts of an hour before/hour after are still 13 probably going to be relatively minor. 14 The other extreme of data substitution is what's 15 called the maximum potential concentration. And ifyou get 16 that value thrown in, it can send you all over the place. 17 And typically if you're just doing a real basic QA of the 18 data, and just looking at it, you can see these bec ause 19 you'll get a--you'll be going along and all of a su dden you 20 get a very crazy number showing up in the data set. 21 Some of the good examples I've seen of this are 22 where you're going along with a unit sitting at a s table 23 condition with an FGD system running, no evidence o f any 24 equipment problems, and the emission rate suddenly jumps from 25

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KAY McGOVERN & ASSOCIATES (919) 870-1600 **Suite 117, 314 West Millbrook Road FAX 870-1603 Raleigh, North Carolina 27609-4306 (800) 255-7886**  .2 or .3 of a pound per million to 2 or 3 pounds pe r million 1 or higher. So, you know, that can just totally dri ve an air 2 quality model nuts when you throw that kind of a ch ange into 3 it. And exit velocities can jump to two or three t imes the 4 design value of the stack and potentially go well i nto the 5 very high velocities that you just don't design a s mokestack 6 for in most cases. 7 Hourly temperature data, you get into needing to 8 select the proper sensors to obtain reasonable temp eratures. 9 If there's a problem with it, if you have too low o f a 10 temperature, it will again affect the dispersion ofthe plume 11 and give unreasonable and incorrect results. 12 One other special case of data substitution, and 13 this is where you see--where we've seen a lot of th e MPC data 14 show up, is in a start-up of a new stack when a wetscrubber 15 is started up on an existing facility. Yes, some o f the data 16 is substituted using stack testing, which is a verygood 17 source of data when you have it. 18 But you don't have that from the minute the units 19 are fired up in this case. It's some hours later, and you 20 may not see it continuously for the several weeks i t takes to 21 get the CEMS systems up and running. So you end upwith 22 substitution based on the old stacks, which are uns crubbed, 23 and it just is very crazy and you have to manually correct 24
all of that data. 25

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You know, the recommendations we would offer at 1 this point is that the modeling group here at OAQPSshould be 2 involved with CAMD as we move into the fall as they 're 3 planning on revising the emissions data reporting p rogram 4 that's used for the utilities to report data and towork with 5 them to try to include parameters that are needed t o help 6 improve our ability to model using their data set, because 7 again, it's an hourly data set, and there are a lotof good 8 possibilities of what you can do with that data. S ometimes 9 it just takes a lot of work and quality assurance t o make 10 sure that the data is something suitable for use inair 11 quality modeling. 12 And, you know, again, remember, this was set up as 13 an accounting program, not as a program to collect data for 14 air quality modeling. We're just using it for that . And we 15 have to keep that in mind as we work with the data and QA it 16 prior to it being included in an air quality model. Thank 17
you. 18 Mr. Bridgers: Thank you, David. Up next we 19 have Chris presenting for API. Chris? 20 Mr. Rabideau: Thanks, George. My name is 21 Chris Rabideau. I am with Chevron, but today I am speaking 22 as the chair of the American Petroleum Institute's Air 23 Modeling Group. 24 First of all, I just want to--we appreciate the 25

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KAY McGOVERN & ASSOCIATES (919) 870-1600 **Suite 117, 314 West Millbrook Road FAX 870-1603 Raleigh, North Carolina 27609-4306 (800) 255-7886**  efforts done by EPA and the IWAQM3 group in develop ing the 1 proposal package. We know there's been a lot of wo rk going 2 into that package. We also appreciate EPA's reviewand the 3 consideration of all the API sponsored research tha t have 4 gone into some of the improvements that are in the proposal 5 package as well. 6 I also want to acknowledge EPA for opening up the 7 annual modelers meetings to the stakeholders for atleast, 8 you know, one day for the last couple of years. Th at's also, 9 I think, been very beneficial to some of the progre ss of the 10 projects that we've been working on. 11 Also, since we had to do these presentations a 12 couple of days ago to get them into George, obvious ly this is 13 based on our initial review and understanding, whic h, you 14 know, some has changed based on the presentations yesterday 15 and interpretations of what we were seeing. So obv iously you 16 know we'll be following up with written comments. They'll be 17 a lot more detailed. 18 So today's comments are basically what we had-- 19 what we saw at the beginning and at least what our 20 recommendations are. Obviously based on yesterday some of 21 these things are in there. We just want to make su re that--I 22 just want to clarify that at the beginning. 23 As we undertake the process to revise Appendix W-- 24 and again, as many have said before, you know, this is ten 25

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KAY McGOVERN & ASSOCIATES (919) 870-1600 **Suite 117, 314 West Millbrook Road FAX 870-1603 Raleigh, North Carolina 27609-4306 (800) 255-7886**  years in the making--you know, we need to consider a 1 structure that's more timely for the incorporation of the 2 model updates. We should not be delayed for severa l years on 3 model updates. 4 We know in the next year there's going to be some 5 new, more robust NO 2evaluation databases. You know, 6
there's--two NO 2studies being done right now that API has 7 been supporting will be WRAP NO 2drill rigging and the PRCI 8 project that's going to be starting here very soon. 9 You know, these data sets are going to allow more 10 rigorous evaluation of these models. And, you know , these 11 data sets could also suggest that model refinements need to 12 be done. And we need to have the ability to timely 13 incorporate those technical advances. 14 And it has been suggested--you know, there's a 15 tier structure which I'll get into, and also a subj ect that 16 we had brought up at our last--API's comments at th e last 17 modeling conference of a technical advisory panel. 18 Again, some of the lack of clarity has been 19 addressed with some of the presentations yesterday, but 20 basically--first of all, I also want to make sure we 21 understand that the low wind project that Bob Painehad 22 mentioned and that was mentioned in some of the EPAcomments 23 was not just an API project. It was also supportedby UARG, 24 so it was a joint low wind project as well. 25

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But we support the adoption of the U* option. 1 Again, we understand the beta option,but the plan i s to go to 2 a default option with the promulgation of Appendix W. We 3 still haven't evaluated LowWind3,but we plan to do so for our 4 written comments. 5 With respect to the NO 2improvements, again, we 6 support the adoption of ARM2. Again, we appreciateAPI--or 7 EPA working with API in getting that--getting that into the 8 system. However, it's unclear as to what steps wou ld be 9 required to allow the use of a lower in-stack ratio

. 10 As we saw yesterday by Rich Hamel of ERM, you 11 know, only 4.5 percent of the in-stack ratios in th e database 12 are greater than .5. So if an applicant has site s pecific 13 in-stack ratio that is less than .5, we're going tosuggest 14 that adjustments should be allowed, you know, witho ut the 15 need for additional approval or going through the modeling 16 clearinghouse. There should be--there should be a way to set 17 that up since, you know, 95 percent of what we thin k is going 18 to happen is going to be less than .5. 19 We support the classification of ARM2, OLM, and 20 PVMRM2. Again, I think the understanding there has been 21 clarified, but we haven't had time to evaluate PVMRM2 so we 22 plan to do so for our written comments. 23 Again, and I think these issues have been 24 addressed in a number of the presentations before mine, but, 25

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KAY McGOVERN & ASSOCIATES (919) 870-1600 **Suite 117, 314 West Millbrook Road FAX 870-1603 Raleigh, North Carolina 27609-4306 (800) 255-7886**  you know, there are still some outstanding needs wi th AERMOD. 1 There's obviously the building downwash issue that' s been 2 touched both on the long and narrow as well as the GEP height 3 issue, also on the background. And again I think s ome of 4 these things have been addressed and some of them h ave not 5
been. 6 Again, with modeling nearby we want to make sure 7 that the actuals are being used, not allowable. Al so, we 8 think there should be some more flexibility in the use of 9 monitoring data to not just characterize the contri bution 10 from nearby sources but also potentially in the pla ce of 11 modeling. And then also we want to make sure the b ackground 12 excludes anything that's impacted by exceptional events. 13 With respect to CALPUFF and long range transport, 14 again, I think we agree with some of the statements made that 15 I think EPA is underestimating the times when a lon g range 16 transport is going to be required. I think there s till 17 is--there's still a need for a long range transportmodel. 18 We have a concern that there is no consensus on acc eptable-- 19 on an acceptable model, which we feel there probabl y will be 20 significant delays in permitting. 21 I think we've got a typo here. In the absence of 22 a preferred long--we're suggesting CALPUFF version 6.42 that 23 has the advanced chemistry, you know, should be all owed as a 24 refined screen model, again in some of the work tha t we have 25

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KAY McGOVERN & ASSOCIATES (919) 870-1600 **Suite 117, 314 West Millbrook Road FAX 870-1603 Raleigh, North Carolina 27609-4306 (800) 255-7886**  done in the past on it, putting--improving the chemistry in 1 CALPUFF. So we'd like to see that potentially be u sed. 2 Again, also, if there is--I know there's been some 3 prior concerns with CALMET, so obviously WRF/MMIF c an also be 4 used to be--to input into CALPUFF. So hopefully th e use of 5 CALPUFF should not be an issue there. 6 With respect to the ozone and secondary PM2.5 , a 7 lot of unknowns. We know that there's going to be, you know, 8 further rulemaking on this. So with MERPs, you know, in 9 principle we think that's a reasonable approach. H owever, we 10 really can't comment on how it's--what the numbers are 11 because we haven't seen anything yet, so obviously there's a 12 lot more to come on that, so it's hard for us to ac cess the 13 appropriateness of whatever, you know, this approac h is going 14 to be, but in principle the idea of a MERP does sou nd like a 15 good idea. 16 With respect to the first tier, again, there's 17 questions about where is this--where does the data exist, 18 because obviously there's still some more guidance that needs 19 to come out with the proposal. There's still not a --I think 20 as somebody said yesterday, it's still--the story i s still n 21 not complete yet. It's still out. So we still have a lot 22 more details that need to be--need to be addressed on this. 23 With respect to the second tier, again, what's 24 classified as only, you know, saying--being used inspecial 25

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KAY McGOVERN & ASSOCIATES (919) 870-1600 **Suite 117, 314 West Millbrook Road FAX 870-1603 Raleigh, North Carolina 27609-4306 (800) 255-7886**  situations, which is an application of more sophist icated 1 chemical transport model, I think--again, I think t his is 2 going to be used more frequently than EPA is presuming in the 3 proposal. 4 And I think obviously developing photochemical 5 grid model databases from scratch is costly and time 6 consuming. And again, that's--for the ones that ar e going to 7 need to do the permitting that's obviously an issuefor us. 8 I think this was also mentioned yesterday. We 9 need consistencies in the regulatory modeling. Forfar-field 10 modeling, development of the common databases that have been 11 preevaluated and tested and could alleviate some ofthose 12 issues. 13 And I know that with this last bullet there's some 14 concern there that we're saying there may be--now, there's a 15 role for Lagrangian photochemical models using a ra nge of 16 realistic background concentrations to identify pot ential 17 worst case ozone and secondary PM2.5impacts. You know, some 18 could say to get a realistic background you need torun the 19 photochemical grid model, so why don't you just do the 20 photochemical grid model. 21 So maybe--what we're proposing is maybe like a 22 tier 1.5, somewhere in the middle, where you could use 23 Lagrangian and, you know, put in some worst case ba ckground 24 so that you don't have to do the full-blown photoch emical 25

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KAY McGOVERN & ASSOCIATES (919) 870-1600 **Suite 117, 314 West Millbrook Road FAX 870-1603 Raleigh, North Carolina 27609-4306 (800) 255-7886**  grid model. So maybe there's some flexibility ther e. 1 Obviously we'll follow that up some more in our wri tten 2 comments, but that's just a suggestion. 3 Obviously this--George presented this yesterday on 4 Model Clearinghouse. It seemed like reading through the 5 proposal that there's a lot of places in there for going 6 through the Model Clearinghouse for approval. And, you know, 7 George showed the letter yesterday of a month. 8 Our concern is all the stuff that goes up before 9 that. There's all the work with the state and withthe 10 regions and trying to get them to get to the Cleari nghouse. 11 So again, if everything has got to go through the 12 Clearinghouse, obviously there's concern with the p rocess, 13 also just with the issues of being responsive becau se of the 14 staffing resources that EPA has to deal with. So we just 15 feel that there's potentially a lot of things that could go 16 to the Clearinghouse. I'm not sure if that's the-- you know, 17 the right answer for everything. 18 You know, this is--I think Sergio talked about 19 this, and I think Air & Waste also brought this up yesterday, 20 and I just want to recognize Steve Hanna, who--basi cally this 21 was his brainstorm when we presented our comments a t the 10th 22 Modeling Conference of the need for a scientific advisory 23 panel. 24 I think an external panel could strengthen and 25

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KAY McGOVERN & ASSOCIATES (919) 870-1600 **Suite 117, 314 West Millbrook Road FAX 870-1603 Raleigh, North Carolina 27609-4306 (800) 255-7886**  expedite some of these model improvements and couldbe used 1 as part of this tiered structure that was suggestedyesterday 2 by Air & Waste. Again, the panel can review the pr oposed 3 methodologies, can review any specific model revisi ons, you 4 know, model--the panel can review the beta options before the 5 release to help, you know, with the bug fixes so th at there's 6 not numbers of bug fixes after each other. Again, it's just 7 a--and also the panel could provide input on any gu idance 8 that's issued prior, you know, to that. 9 So again, I think, you know, we suggested this, or 10 Steve suggested this, at the 10th Modeling Conferen ce and I 11 think it's still a premonition. I think it sounds like 12 there's other people that are also behind this issu e, so I 13 think, you know, this is one of our suggestions. 14 And just to kind of also wrap up here with the 15 tiered approach that Air & Waste brought up yesterday, I 16 think it's a good idea. We also support that. I t hink with 17 the one--one added suggestion is that I think for t he one 18 year testing and debugging period, knowing how longit took 19 to get ARM2 and some of the low wind projects throu gh the 20 system, I think our suggestion would be that the te sting and 21 debugging be concurrent with the EPA assessment. 22 So when a project comes to EPA and it's ready to 23 go, instead of--while they're also reviewing it, pu t it out 24 there for testing and debugging so that the modelin g 25

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KAY McGOVERN & ASSOCIATES (919) 870-1600 **Suite 117, 314 West Millbrook Road FAX 870-1603 Raleigh, North Carolina 27609-4306 (800) 255-7886**  community can also look at it at the same time and try to 1 shorten up their review process, because you're sti ll going 2 to have--as I suggested, you're still going to havea 90 day 3 comment period to take in any comments on any of th e--any 4 improvements. But at least maybe some of that test ing and 5 debugging could be done concurrently so that we cankind of 6 shorten up the time period on that. And that wraps it up. 7 Mr. Bridgers: Thank you, Chris. So we'll 8 transition from Chris to Cindy Langworthy. And Cin dy is 9 going to offer some comments from UARG. 10 Ms. Langworthy: Thank you, George. I'm Cindy 11 Langworthy of Hunton & Williams, and I am pleased t o have the 12 opportunity to speak with you on behalf of the Util ity Air 13 Regulatory Group, UARG. UARG is a voluntary group of 14 electric generating companies and national trade 15 associations. The vast majority of electric energyin the 16 United States is generated by individual members ofUARG or 17 other members of UARG's trade association members. UARG 18 participates on behalf of its members in proceeding s under 19 the federal Clean Air Act that affect the interests of 20 electric generators. 21 Air quality modeling has an impact on many of the 22 activities of UARG's members. For example, such mo deling 23 influences the siting and design of new power plant s, and it 24 affects the operation of existing power plants. Toensure 25

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KAY McGOVERN & ASSOCIATES (919) 870-1600 **Suite 117, 314 West Millbrook Road FAX 870-1603 Raleigh, North Carolina 27609-4306 (800) 255-7886**  that business decisions concerning these facilities are based 1 on accurate information, it is vital that EPA's rec ommended 2 models and modeling tools realistically estimate, n ot greatly 3 overestimate, the impact of power plant emissions o n air 4 quality. EPA's proposed rule on revision of the mo deling 5 guideline explicitly recognizes this. It says thatthe use 6 of modeling practices that are overly conservative may 7 unnecessarily complicate permitting. 8 But overly conservative modeling practices do more 9 than just complicate permitting. Overly conservati ve 10 practices can lead to predictions that air quality problems 11 exist when in fact they do not. And that in turn c an force 12 expensive and unnecessary facility redesign or emis sion 13 reduction measures. It can even lead to cancellati on of 14 planned facilities or shutdown of existing ones in order to 15 address problems that do not exist in the real worl d. And 16 the more stringent EPA makes its air quality standa rds, the 17 greater the problems caused by overly conservative models. 18 There is simply less room for error. 19 UARG plans to submit detailed written comments on 20 a broad range of issues raised by the proposed chan ges to the 21 modeling guideline. My comments today, though, aregoing to 22 focus on one overarching concern: EPA's continued reserva23 tions about accepting model improvements developed with 24 support from industry groups in order to make timel y improve- 25

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KAY McGOVERN & ASSOCIATES (919) 870-1600 **Suite 117, 314 West Millbrook Road FAX 870-1603 Raleigh, North Carolina 27609-4306 (800) 255-7886**  ments to EPA's preferred models. 1 And I will say that I've heard some stuff here. 2 I'll try and take it into account as I'm talking. I'm sort 3 of in the same position as Chris--that is, this was written 4 and approved, you know, before we heard the discuss ions here. 5 Industry groups have repeatedly shown that they 6 are willing at their own expense, and sometimes con siderable 7 expense, to retain recognized air quality modeling experts to 8 undertake rigorous, well-vetted projects to developtools 9 that address identified inadequacies in current models and 10 modeling techniques. They coordinate with EPA on s uch 11 projects, seeking and responding to feedback received from 12 the agency. 13 But when industries then provide EPA with improved 14 modeling tools, EPA does not necessarily, and I wou ld say as 15 a matter of course, act promptly to incorporate theimproved 16 tools in the modeling guideline or in guidance. In stead it 17 has been our experience that approval of new techni ques 18 developed by anyone outside of the federal governme nt are 19 delayed. 20 Often the best that happens is that after months 21 or years EPA will label those techniques as non-def ault beta 22 options, which means they cannot be employed unless the user 23 is willing to undertake burdensome, time-consuming, case 24 specific demonstrations of the worthiness of the ne w 25

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KAY McGOVERN & ASSOCIATES (919) 870-1600 **Suite 117, 314 West Millbrook Road FAX 870-1603 Raleigh, North Carolina 27609-4306 (800) 255-7886**  techniques. 1 Thus, in addition to the cost of retaining 2 recognized modeling experts to carefully develop an d test 3 model improvements, the regulated community faces t he cost of 4 regulatory delay and uncertainty when seeking a permit to 5 build or to modify a source. And a climate of dela y and 6 uncertainty discourages businesses from building ne w sources 7 or upgrading existing sources. Not only does this hurt the 8 economy, but it can also mean that existing sources with 9 higher emissions are not replaced or updated. 10 This is what has happened with industry developed 11 techniques to improve the prediction of short-term pollutant 12 concentrations during low wind speed conditions. E PA took a 13 step in the right direction in 2012 when it incorpo rated 14 three improved techniques, LowWind1, LowWind2, and U*, into 15 AERMOD and AERMET. Since then, however, these opti ons have 16 been treated as non-default beta options, and runni ng AERMOD 17 and AERMET with non-default beta options turns thos e 18 preferred models into nonpreferred or alternative models. 19 In other words, in order to use an improved 20 technique to model short term concentrations duringlow wind 21 speed conditions, users find themselves turning thepreferred 22 AERMOD and AERMET into nonpreferred versions of themodel. 23 And that burden--they then have the additional burden of 24 having to demonstrate to permitting authorities the 25

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KAY McGOVERN & ASSOCIATES (919) 870-1600 **Suite 117, 314 West Millbrook Road FAX 870-1603 Raleigh, North Carolina 27609-4306 (800) 255-7886**  appropriateness of such nonpreferred alternative mo dels from 1 both a theoretical and a performance perspective. And I'm 2 concerned that this already cumbersome process is about to 3 get worse because EPA has proposed that written app roval will 4 be required from the Model Clearinghouse each time an 5 alternative model is going to be used. 6 UARG members had hoped that the proposed revision 7 of the modeling guideline would signal a major chan ge in 8 EPA's attitude towards model improvements developedby those 9 outside of EPA. In particular, we hoped, indeed weexpected, 10 that EPA would announce that it would no longer tre at the 11 techniques for addressing AERMOD model overpredicti on under 12 stable, low wind speed conditions as non-default be ta 13 approaches but would instead consider them acceptab le by 14 default. As you have heard repeatedly at this conf erence, 15 these techniques have been shown to improve AERMOD' s 16 performance significantly. 17 Language from the preamble to the proposed rule 18 encouraged us to think that EPA was in fact proposi ng such 19 action. The preamble states that EPA is proposing to-- 20 proposing updates to the AERMOD modeling system to address a 21 number of technical concerns expressed by stakeholders and 22 goes on to explain that among the updates are propo sed 23 options to address AERMOD model overprediction unde r stable, 24 low wind speed conditions. Great. 25

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But the user's guides for AERMET and AERMOD still 1 refer to them as non-default and/or beta options, which means 2 their use would still require approval of an altern ative 3 model. And we were encouraged yesterday by comment s from EPA 4 that this may not be the case when the current rulemaking is 5 complete, and we certainly hope that's true. 6 And it appears that other industry-sponsored model 7 development work has not been incorporated into thedefault 8 models, although it may be. Although a modified ve rsion of 9 the ARM2 screening technique developed with industr y support 10 has been incorporated into AERMOD, again, the AERMO D's user 11 guide indicates that this technique is a non-defaul t data 12 option. 13 And an industry developed improved chemistry 14 algorithm for CALPUFF has not even been considered, as EPA 15 proposes to downgrade CALPUFF to the status of a sc reening 16 model. We were told that that would happen, that 17 consideration would take place, during this modelin g 18
conference. 19 Furthermore, EPA does not seem--seems to have 20 determined some limitations on how Lagrangian model s can be 21 used, which means that the SCICHEM model, a sophist icated 22 Lagrangian model with photochemistry that we heard about 23 yesterday, that industry developed at considerable expense 24 with significant feedback from EPA will not necessa rily have 25

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KAY McGOVERN & ASSOCIATES (919) 870-1600 **Suite 117, 314 West Millbrook Road FAX 870-1603 Raleigh, North Carolina 27609-4306 (800) 255-7886**  a role in the modeling guideline. We certainly hop e it does. 1 But the preamble to the proposed rule indicates 2 that a Lagrangian model may be the type of model tobe used 3 on a case by case basis for second level screening assess4 ments for Class I significance and cumulative increment 5 analyses. And again, on a case by case basis means it's an 6 alternative model. 7 In these times of limited budgets, EPA should take 8 advantage of the fact that industries are willing t o 9 undertake at their own expense model improvement pr ojects to 10 address identified inadequacies in the current suit e of 11 tools. EPA should be able to review and approve th e use of 12 such techniques promptly and should not let the imp rovements 13 linger as beta options for years. 14 The above described options to address AERMOD 15 model overprediction under stable, low wind speed c onditions 16 have been beta options for three years. Three year s as a 17 beta option is more than long enough. The modelingguideline 18 should be revised now to give appropriate stature t o reviewed 19 and validated tools that recognized modeling expert s have 20 developed with financial support from industry. Su ch 21 improvements should no longer be relegated to alter native 22
model status. 23 Moreover, it should not be necessary for the 24 regulated community to have to wait more than ten years in 25

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KAY McGOVERN & ASSOCIATES (919) 870-1600 **Suite 117, 314 West Millbrook Road FAX 870-1603 Raleigh, North Carolina 27609-4306 (800) 255-7886**  order to see improvements in the modeling tools inc orporated 1 in the modeling guideline. Nothing in the Clean Ai r Act 2 requires that a proposal to revise the modeling gui deline be 3 tied to one of the triennial conferences, which, bythe way, 4 are triennial, not every ten years. Nothing says t hat 5 changes to the guideline must be made all at one time instead 6 of as each new tool or option becomes available. 7 In summary, UARG continues to urge EPA to adopt a 8 more agile approach to updating the modeling guidel ine to 9 ensure that it keeps pace with the needs of all sta keholders 10 and with the efforts of stakeholders to provide theagency 11 with well-conceived, well-vetted improvements to ex isting 12 modeling techniques. UARG encourages EPA take fulladvantage 13 of model development work being performed by recogn ized 14 experts and funded by the regulatory community--theregulated 15 community. 16 And if I could just add a little aside here, I 17 understand that the modeling guideline is a rule an d that 18 revising it requires notice and comment, rulemaking . I'm a 19 lawyer. I believe in this. What is not clear to me, 20 however, is what constitutes a bug fix that does no t require 21 rulemaking, and what is a change that does, and I s uggest 22 that EPA clarify the distinction. 23 In any event, the agency should now revise it's 24 proposed--the modeling guideline by classifying thehelpful 25

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KAY McGOVERN & ASSOCIATES (919) 870-1600 **Suite 117, 314 West Millbrook Road FAX 870-1603 Raleigh, North Carolina 27609-4306 (800) 255-7886**  new techniques, including those for low wind speed 1 conditions, as acceptable by default, not as non-de fault or 2 beta options. And Model Clearinghouse approval forthe use 3 of such new techniques should not be required. It may well 4 be that EPA can take this action at the end of the current 5 rulemaking, and we would welcome that. 6 Even if taking such action would require the 7 current proposed Modeling Guideline revision to be re8 proposed, however, that should not stop the agency from 9 taking that correct step. UARG believes that any delay 10 caused by a re-proposal to include the fact that th ese will 11 become default options would be offset by the time that would 12 be saved by the ability to conduct modeling analyse s without 13 the need to go through approval for an alternative model. 14 Furthermore, UARG recommends that EPA revise its 15 modeling guideline much more often than once every ten years. 16 EPA should put in place a mechanism that ensures th e agency 17 will revise its modeling guideline whenever new modeling 18 techniques have been shown to improve model performance. And 19 the agency should consider whether revisions to the Guideline 20 are needed each time it revises a NAAQS, and if the y are, it 21 should proceed to make those revisions promptly. T hank you. 22 Mr. Bridgers: Thank you, Cindy, and UARG. So 23 now we're going to go off of the agenda that you have in 24 front of you and we're going to go with two more 25

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KAY McGOVERN & ASSOCIATES (919) 870-1600 **Suite 117, 314 West Millbrook Road FAX 870-1603 Raleigh, North Carolina 27609-4306 (800) 255-7886**  presentations, and if there's time we also have alr eady 1 requested one oral comment that we'll squeeze in be fore 2 lunch. So pardon me just a minute to pull this ove r. 3 (Pause.) 4 There we go. So now I'll yield 15 minutes to 5 George Schewe--where's George--oh, there's George, with 6 Trinity Consultants. 7 Mr. Schewe: Good morning. My name is 8 George Schewe. I'm a meteorologist with Trinity Co nsultants 9 in Covington, Kentucky. And I'm going to keep this very 10 simple. A lot of you know I teach some classes forTrinity 11 and a few other places and I can speak for about anhour from 12 one slide, so I've got 18 slides, so we're going tocut it a 13 little shorter today. 14 One way to keep it simple is I'm kind of speaking 15 here on behalf of all the little guys that aren't h ere, the 16 local agencies, some of the state agencies, Chris B eekman 17 from--he's a meteorologist up in Ohio EPA. He call ed and 18 said, "Can you kind of be paying attention to what' s going on 19 for me? We can't afford to get down here." 20 The city of Cincinnati has air toxics problems, 21 and one of the things that they still do--they don' t have all 22 the CAMx capabilities--are some of them still run AERSCREEN. 23 Some of them are still running SCREEN3. And so we' ve been 24 trying to wean them away from running SCREEN3 and j ust 25

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KAY McGOVERN & ASSOCIATES (919) 870-1600 **Suite 117, 314 West Millbrook Road FAX 870-1603 Raleigh, North Carolina 27609-4306 (800) 255-7886**  running AERSCREEN. 1 So what I did was I just looked at AERSCREEN and I 2 said is it really conservative, okay? So that is t he whole 3 thing I'm going to talk about today. Here's the qu ote from 4 the existing Appendix W. I won't read to you all o f it, but 5 the purpose of screening is to eliminate the need o f more 6 detailed modeling so it will not cause--so it's supposed to 7 give you a conservative answer. 8 I couldn't find that in the new one, but what I 9 found that was close was in Section 4.2.1(b), and i t says, 10 "As discussed in paragraph 2.2(a), screening models or 11 techniques are designed to provide a conservative e stimate of 12 concentrations." 13 So if I've got AERSCREEN, and I've got an air 14 toxics program in my state and I'm not going to runCAMx for 15 an air toxics of 1 ton of formaldehyde from somebody in town, 16 I want to know if it's going to be conservative eno ugh to 17 protect the standard so that I don't have to tell t hat little 18 mom and pop operation that they've got to run AERMO D and it's 19 going to cost them more to run AERMOD than it is toproduce 20 whatever they're producing and put down a little bi t of 21 formaldehyde. So that's what I tried to do. 22 So what I did was, unfortunately--I did this 23 couple or three months ago--I used some older versi ons of the 24 model. So one of the things that I need to do is r erun this 25

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KAY McGOVERN & ASSOCIATES (919) 870-1600 **Suite 117, 314 West Millbrook Road FAX 870-1603 Raleigh, North Carolina 27609-4306 (800) 255-7886**  with the newer versions of the models to see if it makes any 1 difference, so AERSCREEN 14147, the current versionof AERMOD 2 which is not current anymore, 14134. I used the cu rrent 3 versions of BPIP and AERSURFACE and AERMAP and basi cally set 4 it up using some of the default and suggested sourc es that 5 have been in some of the examples for AERMOD, ISC, and all of 6 the other models over the years, okay? 7 That one little bullet there at the end, which you 8 in the back can't see because it's way down on the bottom, is 9 that I've actually compared SCREEN3 to AERSCREEN, a nd if you 10 use all the defaults and do the best job you can doon 11 defining the Bowen ratio and the surface roughness and the 12 albedo that you get fairly similar results between SCREEN3 13 and AERSCREEN, at least for the current--the previo us 14 version. 15 So what was my methodology, seven different source 16 types, and basically four different locations: Orl ando, 17 Florida surface data, LaGuardia, Bowling Green, andDalhart, 18 Texas. Those are really different types of meteoro logical 19 stations. These are little windroses for each of t hose 20 stations on an eastern U.S. map just to kind of show the 21 general patterns of wind that are going on there. And you 22 can see LaGuardia, New York has a very diverse patt ern, a big 23 component from the northeast and from the northwest , which is 24
not unusual. 25

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KAY McGOVERN & ASSOCIATES (919) 870-1600 **Suite 117, 314 West Millbrook Road FAX 870-1603 Raleigh, North Carolina 27609-4306 (800) 255-7886** 

So what are the differences between some of these 1 stations? I took the two that were the most divers e from 2 each other and just put their little graphical Goog le Earth 3 image on here. LaGuardia in the top is situated ne ar water, 4 but it's also situated in a very highly urbanized, 5 industrialized and commercialized area, as comparedto 6 Dalhart, Texas, which is in the middle of a lot of circular 7 watering systems, watering plants for agricultural, so very 8 different in terms of that. 9 So what did that mean in terms of assigning 10 albedo? So I downloaded the AERSURFACE, the 1992, which is 11 now 23 years old, data and ran the AERSURFACE modelon that 12 to get the albedo, the Bowen ratio, and surface rou ghness, 13 which I then put into AERMET to run the AERMET mete orology 14 data for using in the AERMOD part of the analysis b ut then 15 also used these inputs for the AERSCREEN part of th e analysis 16 because you have to put those in. 17 The biggest difference there is, well, first, 18 Bowen ratio and the surface roughness. Those are quite 19 different from LaGuardia. So I just want to point that out 20 because when I show you some results in a few minut es, you'll 21 see how that affected the results possibly. 22 These are the sources I selected. Again, these 23 are derived from some example problems that are ava ilable for 24 AERMOD and have been kind of historically used overthe 25

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KAY McGOVERN & ASSOCIATES (919) 870-1600 **Suite 117, 314 West Millbrook Road FAX 870-1603 Raleigh, North Carolina 27609-4306 (800) 255-7886**  years, so four different stacks, from a little shor t stack up 1 to a GEP stack, and then an area source that was square, an 2 area source that was circular, and then a volume so urce that 3 was kind of a nominal dimensions, about the same si ze as the 4
area source because a lot of us use those for roadways and 5 things like that, so just put each of those into th e models. 6 For receptors, the last bullet, no terrain; I 7 didn't want to have terrain affecting the analysis here, so 8 everything is flat. We're in eastern or western Il linois. 9 But then I've got two different receptor grids. Fo r the 10 AERMOD analysis I just had a circular grid, which we don't 11 use much anymore, but I used a circular grid to kin d of 12 simulate all the different 10 degree sectors of win d for 13 AERMOD. And then for AERSCREEN I just kind of tookevery14 thing to the east of each of these facilities becau se that's 15 the way the wind blows most of the time in AERSCREEN, from 16
the west. 17 Okay. The rest of the methodology, no downwash, 18 so no buildings or anything that's going to affect any of our 19 analysis. I ran AERMOD with each source for each r eceptor 20 for each meteorological location. And then I did o ne hour, 21 24 hour, and annual block averages--24 hour and ann ual block 22 averages, or I guess 24 hour is block average annua ls, 23 though--everything and then all the one hour values . And 24 then I ran AERSCREEN/MAKEMET with each source for e ach 25

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KAY McGOVERN & ASSOCIATES (919) 870-1600 **Suite 117, 314 West Millbrook Road FAX 870-1603 Raleigh, North Carolina 27609-4306 (800) 255-7886**  receptor for each of those and then used all the same inputs 1 for the AERSURFACE data that you need to run MAKEME T. 2 So what was my expectation? My expectation, based 3 on reading the two Appendix W, were that I would al ways get 4 higher concentrations with AERSCREEN for each situa tion. And 5 that would be something that I could use as a scree ning tool. 6 I had a second expectation on this slide and I 7 took it off because I still use AERSCREEN occasiona lly just 8 to model some sources to find out where's the hot s pots. And 9 as my friend Ryan Gesser--Ryan, are you still here- -said to 10 me years ago, "Why should I run AERSCREEN? Why don 't I just 11 throw everything in AERMOD and run AERMOD because t hen we can 12 put in multiple sources." Oh, yeah, you can only do one 13 source at a time. I didn't run all seven of these at once, 14 okay? So, but I took that expectation out because I was 15 limited to 15 minutes. 16
So here are the answers. These are for one hour. 17 I know you guys in the back can't see these. But AERSCREEN 18 is in the third column, the concentration you got f or one 19 hour from each airport. And then AERMOD is in the fourth 20 column. And then I just hit a simple yes or no, wa s it 21 conservative or not, okay? I'll highlight a few ofthese for 22
you. 23 So if we look at Dalhart, it looks pretty good 24 except for the square area source. If you look down here at 25

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KAY McGOVERN & ASSOCIATES (919) 870-1600 **Suite 117, 314 West Millbrook Road FAX 870-1603 Raleigh, North Carolina 27609-4306 (800) 255-7886**  Orlando, it looks pretty good for all the sources. It was 1 pretty conservative for all the sources, and it was generally 2 above AERMOD. Then you look at Bowling Green, and for 3 Bowling Green neither one of the area sources passe d. All 4 the point sources still passed, so that was good. AERSCREEN 5 was still conservative for the point sources. But then you 6 look finally at LaGuardia, and it's all nos except for the 35 7 meter stack. So for LaGuardia we did not get AERSC REEN to be 8 conservative, so I was a little concerned about tha t. 9 The last three columns over there were my little 10 hot spot analysis. I was trying to again figure ou t if it 11 really picked where the hot spots were, and again t he same 12 kind of mixed results, did a pretty good job, but-- so I 13 decided, okay, I'll plot these and just kind of seewhat they 14 look like. 15 So the northwest corner for all the meteorologists 16 there, that graphic for Orlando, AERSCREEN was alwa ys above 17 the AERMOD models, so it was conservative. But the n if you 18 start looking at some of the other sources or locat ions, 19 Bowling Green, Kentucky, there's our area source th ere. It 20 was underestimated. And if you look again at Dalha rt, it was 21 underestimated. If you look at LaGuardia, just abo ut 22 everything again was underestimated. So it really wasn't 23 screening--a good screening tool for doing sources in the 24 LaGuardia type area. 25

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KAY McGOVERN & ASSOCIATES (919) 870-1600 **Suite 117, 314 West Millbrook Road FAX 870-1603 Raleigh, North Carolina 27609-4306 (800) 255-7886** 

The same kind of deal in the 24 hour concen1 trations, and if you look at all the locations ther e, all of 2 them on a 24 hour basis--and I didn't give you a tabular view 3 of the 24 hour. All of them you did get higher numbers. 4 Even at LaGuardia it did pretty good. You can see down at 5
the bottom corner here there are a few that were st ill below 6 at some of the source types, and I didn't pick out which 7 kinds those were. 8 On an annual basis, I think in this case all of 9 the answers were above the screening level--or the screening 10 level was above what you would get in AERMOD. So i t did good 11 job on the longer term averages. As somebody earli er this 12 morning pointed out in one of their slides, the model does 13 pretty good for longer averages somewhere in space and time, 14 but when you get down to the shorter, one hour peri ods, maybe 15 it doesn't do as well. 16 Okay, so what are our observations? AERSCREEN is 17 not always higher than AERMOD for one hour concentr ations, 18 especially--they're always higher for stacks in rur al 19 situations, though. That was pretty good, I guess. But 20 they're not always lower for--and they're lower formost 21 source types in an urban situation. And again, I o nly based 22 that on one urban situation, that being LaGuardia, so--and 23 AERSCREEN is generally higher on a 24 hour and annu al basis. 24 So my conclusions were AERSCREEN provides a good, 25

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KAY McGOVERN & ASSOCIATES (919) 870-1600 **Suite 117, 314 West Millbrook Road FAX 870-1603 Raleigh, North Carolina 27609-4306 (800) 255-7886**  basic tool for consideration of sources very quickl y. It's 1 not always conservative. It does better in rural s ituations, 2 meaning it's conservative. It does well for rural and area 3 sources. And it doesn't do as well--it underpredic ts for 4 area sources--I'm sorry, in most locations. And itdoes 5 pretty well for longer averaging periods. 6 So as--Bob and I talked about this just a few 7 minutes before--or this morning, and, you know, one 8 consideration is rerun it with 15181. Another ques tion, 9 though, I perhaps have for our panel of modelers he re for 10 OAQPS is can you in MAKEMET, and maybe James--I thi nk you 11 were the AERSCREEN guy yesterday--I can ask questio ns from 12 the podium, right? 13 Does MAKEMET have an option to include U* or the 14 low end options? And if we make it default in AERMOD, will 15 it also become default in AERSCREEN? So that was k ind of one 16 last question. So I thank you very much. Have a g ood day. 17 Mr. Bridgers: Thank you, George. It's nice 18 to have another George up on the podium. So we have one last 19 presentation that has prepared slides, Mr. Jeff Ben nett. And 20 Jeff, I am going to turn the podium to you. 21 Mr. Bennett: Good morning. As George told 22 you, my name is Jeff Bennett. I'm an air quality e ngineer 23 for Barr Engineering out of our Jefferson City, Mis souri 24 office. I'm going to be giving a few comments toda y on the 25

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KAY McGOVERN & ASSOCIATES (919) 870-1600 **Suite 117, 314 West Millbrook Road FAX 870-1603 Raleigh, North Carolina 27609-4306 (800) 255-7886**  ozone--single source ozone modeling component to th e 1 Appendix W proposed rulemaking. 2 And what I--I mean George asked for people to say 3 who they're representing, and I would tell--I've be en a 4 regulator for a long time. I was a regulator at th e state of 5 Missouri for about 18 years, and so I've never real ly been 6 able to say--I'm representing myself today as a con cerned 7 citizen, so there you go. That's who I'm represent ing--a 8 concerned air quality modeler may be better. 9 So just a quick, very quick, summary of what EPA 10 is--what appears, what my read of the initial--my i nitial 11 review of the Appendix W rulemaking and what they'r e trying 12 to do, they want to develop some MERPs. They're ab ove what 13 the existing SERs are on a national basis, which, you know, I 14 think Chris from API said people would generally support. I 15 think that's true. 16 They want to utilize photochemical modeling of 17 areas around the project as a means to arrive at a calculated 18 ratio of precursors to downwind ozone impact, so ba sically 19 existing air quality data, photochemical modeling data to use 20 to develop these calculated ratios of ozone to prec ursors. 21 The third and the fourth ones are sort of combined 22 I think a little bit in the rulemaking, but a new p hoto23 chemical modeling analysis, and a lot of yesterday was 24 talking about the Lagrangian piece, to determine sp ecific 25

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KAY McGOVERN & ASSOCIATES (919) 870-1600 **Suite 117, 314 West Millbrook Road FAX 870-1603 Raleigh, North Carolina 27609-4306 (800) 255-7886**  projects will either have impacts above or below th e SIL to 1 avoid a NAAQS modeling analysis, a cumulative NAAQSmodeling 2 analysis. 3 And the last one of course is the one that's sort 4 of exactly the opposite of what George was just tal king 5 about. It's not air screening. It's the most comp licated 6 thing you can probably do in terms of modeling anal ysis, 7 which is full photochemical modeling. 8 All right, so regulatory context. As I said, I'm 9 an old regulator from the state of Missouri. I was working 10 there for about 18 years. And we went through a ru lemaking 11 in about 2004, 2005, and it was called Missouri 10 CSR 12 10-6.345, and it was affectionately called the Upwi nd NO x 13 rule. So we've already gone through--"we," this is the old 14
"we." 15 When I was working for the state of Missouri, we 16 went through a--went through a process as part of o ur NO xSIP 17 component of our ozone--our ozone SIP, I'm sorry. As part of 18 our ozone SIP we went through a process and develop ed an 19 upwind NO xrule for five counties upwind of the St. Louis 20 area. It was difficult. I don't begrudge EPA tryi ng to go 21 down this road. I think it's going to be a long an d winding 22 pathway. 23 But the idea was we wanted to--we wanted to sort 24 of alleviate some of the control requirements on ex isting 25

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KAY McGOVERN & ASSOCIATES (919) 870-1600 **Suite 117, 314 West Millbrook Road FAX 870-1603 Raleigh, North Carolina 27609-4306 (800) 255-7886**  sources within an nonattainment area by trying to l imit the 1 amount of impact that was coming in from upwind are as. So it 2 was a tradeoff situation. And so the concept was we were 3 going to develop this de minimis threshold, right? 4 And so there's a lengthy rule. It's been-- 5 subsequently the rule has been revoked because it was never 6 used, quote-unquote, used, and the St. Louis area g ot 7 redesignated so there was--there was not a need forit at the 8 time. They've been redesignated back into nonattai nment now, 9 but I guess the air standards are getting more stri ngent. 10 You can move back and forth; right? 11 So the idea is that you can go check out the rule 12 and see what it says, but the question you always-- that comes 13 immediately to everybody's mind is what was the number, what 14 did you come up with, what's this upwind NO xrule, what's the 15
MERP or the--what I call the local MERP. 16 It was 900 tons of NO xper ozone season. May 17 through September was the ozone season. It still i s. And 18 that is equivalent to about 2100 tons a day, a lot better 19 than the 40 tons a day for the SER, and so we had-- we had 20 developed that process. We went through the evalua tion to 21 generate that number. 22 What I'm not doing today is suggesting that that's 23 the right number. That's not what we're talking ab out. It's 24 not necessarily 2150 tons. It's not necessarily 90 0 tons for 25

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KAY McGOVERN & ASSOCIATES (919) 870-1600 **Suite 117, 314 West Millbrook Road FAX 870-1603 Raleigh, North Carolina 27609-4306 (800) 255-7886**  ozone season, but it does--the process we went thro ugh raises 1 a lot of sort of more detailed technical issues tha t the 2 rulemaking and the subsequent guidance don't reallyget into, 3 and so that's what I'm going to focus on a little b it today. 4 So area specific considerations, and you can read 5 that stuff. I mean the photochemical models are gr eat 6 because you include all the sources in there. It h as back7 ground in it. You don't have to worry about addingin other 8 stuff or combining models. It's a single model to predict 9 concentrations to the extent it has the capability of doing 10 that, which you have to go through an evaluation ex ercise to 11 get a SIP approved, and so there was that benefit. 12 But in St. Louis we had gone through that exercise 13 and so we had the capability of going down the pathway of 14 using this existing data set to go through the anal ysis that 15 EPA's talking--that EPA is considering doing as par t of the 16 Appendix W proposed rulemaking. 17 The fact is that that's a difficulty, though. 18 When you attempt to use a photochemical grid model, which 19 takes a long time to run--everybody gets that--for single 20 source analysis, it's impacted by all the sources t hat are 21 around it, the background, the ratio of VOC to NO x . 22 I mean there's a whole pile of existing informa23 tion that has to be accounted for every time you ru n the 24 model and every modeling step. And so it changes e very time 25

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KAY McGOVERN & ASSOCIATES (919) 870-1600 **Suite 117, 314 West Millbrook Road FAX 870-1603 Raleigh, North Carolina 27609-4306 (800) 255-7886**  that the model kicks over to the next meteorologica l period. 1 And so the idea is that it causes--and not only is it a 2 benefit, it also causes some potential problems. 3 And so what did we find out? From a VOC/NO xratio 4 perspective in St. Louis, the reason why it's not c alled the 5 upwind VOC rule was because the St. Louis area is e xtra6 ordinarily NO xlimited. It's got a whole--Chet probably 7 remembers this from back in the day, but it's the b iogenic 8 volcano in the Ozarks, which is south of St. Louis. And so 9 there's a whole pile of additional biogenic VOC tha t's 10 hanging around, and so the VOC controls doesn't make any 11 difference. 12 And so there wasn't an upwind VOC rule because you 13 could have changed a 10,000 ton a year VOC source o r 100,000 14 ton a year VOC source and it wouldn't have made any 15 difference. And so that's why it's not called the upwind VOC 16 rule. It's called the upwind NO xrule. 17 And so the idea is that that's going to be the 18 case in a lot of areas. You're going to have this same 19 problem in every--in every--in every county, every state, 20 every area, every rural or urban area, and you're g oing to 21 have these discussions. And so this is a specific issue that 22 EPA is going to have to address and deal with, I th ink. 23 So the next issue--so it's the next level. So 24 you've got levels of this stuff. So the first leve l on the 25

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KAY McGOVERN & ASSOCIATES (919) 870-1600 **Suite 117, 314 West Millbrook Road FAX 870-1603 Raleigh, North Carolina 27609-4306 (800) 255-7886**  decision making process is which model am I going t o use? 1 What episodes am I going to evaluate. Am I going t o use 2 source apportionment or am I just going to use a br ute force 3
method? 4 I mean those are all sort of first level 5 questions. What's the form of the model concentrat ion that 6 we're going to compare to the SIL? There's all the se sort of 7 specific things that are sort of rudimentary in terms of 8 moving past the initial hurdles that EPA is talkingabout 9
here. 10
And so the next levels--there's several levels of 11 conversation. It's about stack heights and VOC to NO xratio 12 and specific ozone speciation, and that's what this slide 13 talks about. So the reaction chemistry for all ozo ne models, 14 all photochemical models, is set up on profiles. 15 And so there's a grouping there. You don't model 16 every VOC species. There are groupings of species, right? 17 And so each one of those have got a different react ivity. If 18 it didn't have a different reactivity, why would yo u have a 19 speciation profile? You're going to have to--you h ave to 20 have it--you have to have it show up as different s pecies in 21 order for the model to predict appropriately. And so that's 22 the idea. You need to speciate stuff. 23 And so what does that mean for downwind ozone 24 impacts? Eladio yesterday in his presentation wentthrough 25

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KAY McGOVERN & ASSOCIATES (919) 870-1600 **Suite 117, 314 West Millbrook Road FAX 870-1603 Raleigh, North Carolina 27609-4306 (800) 255-7886**  and was looking at highly reactive species versus s omewhat 1 unreactive species, I think. And so his results wo uld be 2 consistent with what I would have expected, which i s you're 3 going to have higher--more reactive VOC species show up with 4 additional impacts and less reactive species, and s o VOC 5 tonnages, one ton to the next, are not the same, an d so 6 you're going to have to address that issue as well. 7 But generally, my overall comment--and we're 8 trying to get out of here on time for lunch, George , so there 9 you go. I'm doing what I can for you and everybodyelse. 10 The idea is that you guys have done a bunch of goodwork. I 11 think that you've evaluated this process and went t hrough a 12 constructive and difficult arena to get down to thepath of 13 trying to propose a MERP. Ultimately that's reallywhat 14 we're talking about, I think, for a lot of sources that are 15 going to be out there. 16 The problem is that the level of detail that's in 17 the rule right now and the guidance isn't sufficien t to talk 18 about a lot of these issues that are--that I didn'teven 19 bring up today. There's dozens of issues like this you're 20 going to have to get through. 21 And so to provide substantive comments, and I 22 think a lot of folks have said this already, you'regoing to 23 have to come up with additional detail. The concep t is 24 solid, we believe, or I believe in general, but you 're going 25

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KAY McGOVERN & ASSOCIATES (919) 870-1600 **Suite 117, 314 West Millbrook Road FAX 870-1603 Raleigh, North Carolina 27609-4306 (800) 255-7886**  to have to--you're going to have to come up with additional 1 things to provide the ability to provide comments f rom a 2 more--on a more detailed basis. That's what it amo unts to. 3 And that's all I've got, with five minutes to go. I think I 4
set the record. 5 Mr. Bridgers: So since we have got into the 6 slight bit of clapping, I think now that we have fi nished all 7 of the presentations, at least with prepared slides , I think 8 that--for the EPA presenters yesterday and then allthe 9 public presenters from the stakeholder community, I think we 10 should all give a round of applause. 11 (Applause.) 12 Mr. Bridgers: And EPA graciously appreciates 13 the effort from all the stakeholder community to pr ovide 14 those comments to us in slide form, and we look forward to 15 your written comments by the 27th. 16 Considering it's 11:30, and we still have a little 17 bit of time before we break for lunch, we have had one 18 request for oral comments. I think it would be app ropriate 19 to put that in before the lunch break, and dependin g on how 20 time goes, if there are some others that feel that they want 21 to say something, I think we can run up to say 11:4 5 or 22 11:50. We'll just see how it goes, and then we'll break for 23
lunch. 24 And immediately following lunch, I will open the 25

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KAY McGOVERN & ASSOCIATES (919) 870-1600 **Suite 117, 314 West Millbrook Road FAX 870-1603 Raleigh, North Carolina 27609-4306 (800) 255-7886**  forum back up for anyone else that may have a desir e to 1 speak. I'm not going to put forth any expectations . My 2 anticipation is it's probably going to be smaller, but all 3 the comments will be transcribed, so any that have to leave 4 for the airport at lunch, you can catch that as soo n as we 5 post it to the web site in about a month. 6 So Bridget, are you--so next we have Bridget Lee. 7 Let me find a good slide to put up, Bridget, maybe this one. 8 Yeah, forget the times but the slide looks pretty g ood. So 9 Bridget Lee is with the Sierra Club, and 15 minutes

. 10 Ms. Lee: I wish I had had this slide on 11 Wednesday morning when I was trying to find my park ing spot. 12 Good morning, everyone. I'm Bridget Lee. I'm an a ttorney 13 with the Sierra Club. And I expect that we will be 14 submitting detailed written comments in October, bu t since 15 I'm here, I'll just share a few very brief thoughts

. 16 First, the Sierra Club is very concerned with the 17 proposal to incorporate the LowWind3 and U* beta op tions as 18 regulatory defaults. In 2013 we submitted to EPA a n 19 evaluation of the performance of the beta options, which 20 demonstrated that they decreased model performance and 21 increased the variability of impacts from tall stac k sources 22 as compared to the accepted regulatory defaults. 23 The possibility that the adoption of these options 24 as defaults could lead to underprediction of air qu ality 25

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KAY McGOVERN & ASSOCIATES (919) 870-1600 **Suite 117, 314 West Millbrook Road FAX 870-1603 Raleigh, North Carolina 27609-4306 (800) 255-7886**  impacts causes great concern within the environment al and 1 public health community. We question the reliance on the 2 Idaho Falls and Oak Ridge studies, which were exclu ded by EPA 3 during the initial evaluation of the model. Moreover, these 4 four year old studies are not likely to be represen tative of 5 air quality impacts from tall stack sources, and wedon't see 6 any compelling reason that the agency should rely o n the 7 studies now. 8 Second, with respect to the tier demonstration 9 approach for addressing single source ozone and PM2.5impacts, 10 we're still in the process of assessing this approa ch but 11 again have concerns about whether it would fulfill EPA's 12 obligations under Section 165. Thank you for your time and 13 attention. 14 Mr. Bridgers: Well, thank you, Bridget. So 15 we now have a few more minutes before we break for lunch. 16 And we--typically we have a podium microphone set up in the 17 foyer, or excuse me, the aisleway there, but it's g oing to be 18 easier for transcription if you come to the podium. So if 19 there are any people in the audience that would like to offer 20 any oral comments at this time, you have 15 minutes of time 21 if you want it. 22 (Pause.) 23 Mr. Bridgers: We needed to pay for some 24 Jeopardy

music or something. We'd have to pay copyright, 25

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KAY McGOVERN & ASSOCIATES (919) 870-1600 **Suite 117, 314 West Millbrook Road FAX 870-1603 Raleigh, North Carolina 27609-4306 (800) 255-7886**  though. Merv Griffin gets his. Well, seeing no immediate 1 interest in providing additional oral comments to t he record, 2 I will reiterate for those that will be leaving forthe 3 airport over the lunch break that the comment perio d now 4 extends for--I think it's 74 days to October 27th. 5 I will during the lunch break update our web site. 6 I wanted to take the registration link off because that 7 becomes sort of invalid, but also to make sure all the 8 presentations are clearly posted. I know that ther e is one 9 or two that we had little slight corrections that a re not 10 changing the record, but there's just some plots th at need to 11 move around. But they'll be available. 12 And as said, it will be three or four weeks at the 13 minimum before the transcripts are ready, but as so on as the 14 transcripts are provided to us and we review them, we will 15 put those on the web site and put those in the docket, so 16 there should be at least--I'm figuring at least 45 days left 17 in the comment period for those that need to reviewthe 18 transcripts and prepare their final comments. 19 And so with that, I will suspend the conference 20 and public hearing until 1 o'clock, and we will rec onvene 21 exactly at 1 o'clock for those that come back, if you would 22 like to provide oral comments. Otherwise I wish th ose that 23 are traveling safe travels, and see you later. 24

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KAY McGOVERN & ASSOCIATES (919) 870-1600 **Suite 117, 314 West Millbrook Road FAX 870-1603 Raleigh, North Carolina 27609-4306 (800) 255-7886** 

F U R T H E R P R O C E E D I N G S 1:00 p.m. 1 Mr. Bridgers: Okay. I am going to in just a 2 moment call the public hearing and conference--oh, everybody 3 got quiet, so I'm going to go ahead and do it. I'mgoing to 4 call the conference and public hearing back to orde r. I hope 5 everybody enjoyed a pleasant lunch. 6 So really quickly, just because it's a formality, 7 I just want to reiterate things that everybody in t his room 8 probably already knows, but since this is the oral session, I 9 just want to make sure that everybody knows that th is is a 10 public hearing. 11 Everything that was said is going to be tran12 scribed and put in the docket. We're going to requ ire that 13 everybody identify themselves and their affiliation --George 14 Bridgers, USEPA, here, Air Quality Modeling Group i n RTP. 15 We're going to have a session for oral comments. 16 At such time that we do not have anybody else reque sting a 17 speaking spot, then I will go ahead and close the p ublic 18 hearing and conference. But that being said, writt en 19 comments for the next 74-ish days can be submitted to the 20 docket by October 27th. And on the information website for 21 the conference and public hearing, there's a docketlink. If 22 not, you can search for it--or it's even in this pr esentation 23
here. 24 The other thing--this is just a side note. Over 25

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KAY McGOVERN & ASSOCIATES (919) 870-1600 **Suite 117, 314 West Millbrook Road FAX 870-1603 Raleigh, North Carolina 27609-4306 (800) 255-7886**  the lunch period I updated the 11th Modeling page, the web 1 site, so all the presentations are now more clearlyposted. 2 They're not embedded in links--I mean they're stillembedded 3 in links in the agenda, but there's a page now thathas all 4 of them listed, and so you can just go to the 11th Modeling 5 Conference page and see that. 6 If there are any nonsignificant--let me make sure 7 I say this right--changes that need to be made by a ny of the 8 speakers--I know there was a couple of plots that d idn't 9 print right with the .pdf--we can accommodate those , but if 10 there's any other substantive changes in the presen tations, 11 they were given in a public record and I can't chan ge them 12 now, including ours. 13 Let's see; what else? Other than that, I think 14 that we'll start--we do have one requested oral comments 15 here. And I will go back to the presentation I clo sed just 16 to have a nice pretty background on the screen. SoPeter, 17 I'll give the floor to you. And just like everybody else, 18 you have up to 15 minutes if you need it. 19 Mr. Guo: Hello, everyone. My name is 20 Peter Guo. I work with Apex TITAN. We are a consu lting firm 21 in Texas. I'll just take a few minutes, you know. We are 22 still working on the detailed comments about the pr oposed 23 regulation, so right now I'll just make quick briefcomments. 24 We do have some concern for the additional 25

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KAY McGOVERN & ASSOCIATES (919) 870-1600 **Suite 117, 314 West Millbrook Road FAX 870-1603 Raleigh, North Carolina 27609-4306 (800) 255-7886**  requirement of the PM2.5secondary modeling requirement and 1 replacement of SCREEN3 with AERSCREEN. I think tha t 2 everyone--I think many people already talked about the 3 secondary--PM2.5secondary formation modeling, so I won't 4 repeat our comments. I will just discuss the use o f SCREEN3 5 here real quick. 6 As I mentioned, we do the permit modeling for the 7 oil and gas industry in Texas, and we have been usi ng SCREEN3 8 for more than a decade, so SCREEN3 have demonstrate d a very 9 useful tool for--you know, for the permit modeling in Texas. 10 So as proposed, SCREEN3 will be replaced with AERSC REEN at 11 this time, so we just suggest that SCREEN3 should b e still 12 kept on the list of the preferred models, you know, give the 13 industry the option to use simple and, you know, qu ick tools 14 to do the permit modeling, you know. 15 We know, you know, AERSCREEN will give us a more 16 accurate result, but actually, you know, AERSCREEN will 17 require additional, you know, information such as, you know, 18 detailed meteorological data. You know, you have t o collect, 19 Bowen ratio, you know, rough surface, or other, youknow, 20 terrain, even the terrain information or building downwash 21 information, so--and in the meantime AERSCREEN willjust give 22 a similar, you know, result compared with the SCREEN3 result, 23 you know, for the oil and gas, you know, permittingproject. 24 And so overall, so I would suggest, you know, 25

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KAY McGOVERN & ASSOCIATES (919) 870-1600 **Suite 117, 314 West Millbrook Road FAX 870-1603 Raleigh, North Carolina 27609-4306 (800) 255-7886**  still, you know, the SCREEN3 should be kept on the list of 1 preferred models, and I think that's all I have today. Thank 2 you very much. 3 Mr. Bridgers: Thank you, Peter. And so at 4 this point having no one that has requested time th rough Nan 5 up front, I will, like I did before lunch, open thefloor up. 6 And probably what I'll do is leave the floor open f or two or 7 three minutes. I might not stand up here in front of you 8 because we don't have the Merv Griffin music. But the 9 microphone is open, and if anybody feels that they would like 10 to offer some oral comments to the record, the floo r would be 11
yours. 12 (Pause.) 13 Mr. Schewe: Good afternoon. My name is 14 George Schewe. I'm not going to speak for 15 minut es. I 15 just have a few things to say. I'm with Trinity Co nsultants. 16 That's our advertisement part. 17 The data requirements rule, the SO 2consent 18 decree--we're in the middle of doing a lot of stufffor a lot 19 of clients, and the Appendix W changes coming rightin the 20 middle of this is not helping us, as of course no t ime would 21 Appendix W changing help any of the analyses we have to do 22 for permitting or for air toxics or anything else. 23 So just having said that, I thought I'd leave you 24 with that thought as you're going down the road of trying to 25

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KAY McGOVERN & ASSOCIATES (919) 870-1600 **Suite 117, 314 West Millbrook Road FAX 870-1603 Raleigh, North Carolina 27609-4306 (800) 255-7886**  get some of these studies completed. Thank you. 1 Mr. Bridgers: Thank you, George. We still 2 have plenty of time till 5 o'clock today. I think George 3 just wanted to get the last word in. 4 (Pause.) 5 Mr. Bridgers: It's as awkward for me as it is 6 for you guys. At least in the other meetings I man age, I 7 just wait for someone to make a motion that we clos e the 8 meeting, all in favor. 9 As the hearing officer, at least I'm not seeing 10 any motion toward the microphone, so I will make on e last 11 call. Raise your hand if you're thinking; if not-- going 12 once, going twice. Okay. 13 With that case, I will call a close to the 11th 14 Conference on Air Quality Modeling and for the publ ic hearing 15 related to the proposed rulemaking for the Guideline on Air 16 Quality Models . We appreciate all of your participation, and 17 as I've said many times, safe travels and all that. 18 But I will also say that feedback, good, bad and 19 otherwise--I've said that to a few people--we welcome through 20 the comments formally on the proposed rulemaking, b ut also 21 with respect to the conference. We're not going todo a 22 formal suggestion box or a survey, but if there arethings 23 that for future modeling conferences that you wouldthink 24 that we should improve upon or change--coffee; yeah , can't do 25

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KAY McGOVERN & ASSOCIATES (919) 870-1600 **Suite 117, 314 West Millbrook Road FAX 870-1603 Raleigh, North Carolina 27609-4306 (800) 255-7886**  it, unless we do it somewhere where you offer free coffee. 1 But nonetheless, I appreciate feedback, good, bad 2 and otherwise. So if there are things that you wou ld like to 3 see changed in future modeling conferences other th an 4 question and answer sessions--can't do it unless we 're not 5 doing a rulemaking--but please send them along. Yo u should 6 be able to find my e-mail address without any probl em. 7 The other thing, and Tyler was good to remind me, 8 I know we've said offline to a bunch of people we a re 9 planning or are in the preliminary planning stages for next 10 year's Regional, State, and Local Modelers Workshop

. 11 I will not say that we are completely set upon a 12 destination because we have to get a bunch of thing s 13 approved, but it would be a city that in 2005 did h ave an 14 encounter with Katrina, if all goes to plan. And we also did 15 have a Regional, State, and Local Modelers Workshopthere 16 that same year prior to Katrina. 17 But nonetheless, we're looking right now at 18 planning a weeklong meeting, so the first half woul d be 19 dispersion and the second half would be photochemic al 20 modeling with an overlap day. And not that we've c ompletely 21 set on it, but the thoughts would be as possibly th e middle 22 day where we have an overlap between both curriculaor both 23 disciplines is that we would also have invited stakeholders 24 come in. But it will happen in September. It willhappen 25

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KAY McGOVERN & ASSOCIATES (919) 870-1600 **Suite 117, 314 West Millbrook Road FAX 870-1603 Raleigh, North Carolina 27609-4306 (800) 255-7886**  after that we finalize the rule package, and so I t hink that 1 would be a forum that we could have a lot more inte raction 2 than over the last couple of days. 3 So again, we appreciate everybody's participation 4 and just have a great rest of your day if you're st aying here 5 enjoying the weather, or if you're traveling, I hop e your 6
travels are safe. 7

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KAY McGOVERN & ASSOCIATES (919) 870-1600 **Suite 117, 314 West Millbrook Road FAX 870-1603 Raleigh, North Carolina 27609-4306 (800) 255-7886**  STATE OF NORTH CAROLINA
COUNTY OF WAKE

C E R T I F I C A T E

I, Kay K. McGovern, do hereby certify that the foregoing pages 251 through 361 represent a true an d accurate transcript of the proceedings held at the United St ates Environmental Protection Agency in Research Triangl e Park, North Carolina, on Thursday, August 13, 2015.

I do further certify that I am not counsel for or employed by any party to this action, nor am I inte rested in the results of this action.

In witness whereof, I have hereunto set my hand this 10th day of September, 2015.

_______________________________ Kay K. McGovern, CVR-CM Court Reporter