## 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

WEDNESDAY, AUGUST 12, 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 Presentations by EPA Conference Overview and George Bridgers, OAQPS 5 Logistics Welcome and Opening Remarks Chet Wayland, OAQPS 11 Current Status of Tyler Fox, OAQPS 17 Appendix W and Overview of Proposed Revisions to Appendix W AERMOD v15181 Regulatory Roger Brode, OAQPS 31 Update Proposed Updates to the Roger Brode, OAQPS 35 AERMOD Modeling System Proposed Updates to the James Thurman, OAQPS 47 AERMOD Modeling System - AERSCREEN Proposed Updates to the Chris Owen, OAQPS 50 AERMOD Modeling System - Proposed NO 2Tier 2 and Tier 3 Revisions Modeling of Mobile Sources Chris Owen, OAQPS 54 Meteorological Data for James Thurman, OAQPS 66 Dispersion Models Long Range Transport for Tyler Fox, OAQPS 73 NAAQS and Increment Assessments Treatment of PM2.5and Kirk Baker, OAQPS 87 Ozone in PSD Compliance Demonstrations Status and Role of the George Bridgers, OAQPS 103 Model Clearinghouse Single-Source and George Bridgers, OAQPS 111 Cumulative Impact Analyses

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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) Introduction to and George Bridgers, OAQPS 123 Opening of the Public Hearing (Day 1) Public Presentations and Comments Source Characterization Bob Paine, AECOM for AISI 124 Issues for Near-Field (AERMOD) Modeling AERMOD Low Wind Evaluation Bob Paine, AECOM for EPRI 134 Results for Tall Stack Databases AERMOD Treatment of Bob Paine, AECOM for 142 Buoyant Stack Releases in Lignite Energy Council Convective, Low Mixing Height Conditions Perspectives and Rich Hamel, ERM 148 Experience with ARM and ARM2 Evaluation of AERMOD Cathe Kalisz, API 158 with Alternate NO x Chemistry Scheme Optimized Use of MMIF Bart Brashers 164 for AERMOD in Complex Ramboll Environ, Inc. Terrain Recent Experiences with Tom Wickstrom, ERM 175 MMIF/WRF for Creating AERMOD Inputs Introduction to the AWMA David Long, AEP 185 APM Comments and General Items AWMA APM Comments on Mark Garrison, ERM 192 AERMOD Related Issues AWMA APM Comments on Gale Hoffnagle, TRC 201 Single Source Modeling and Long Range Transport 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) Exponent's Comments on Christopher DesAutels 209 CALPUFF and AERMOD Exponent Modeling Guidance Perspectives on CALPUFF, Mark Garrison, ERM 219 Roughness, and 30 Miles An Overview of the Biswanath Chowdhury 228 SCIPUFF Dispersion Model Sage Management SCICHEM for Regulatory Eladio Knipping, EPRI 235 Modeling Preliminary Comments on Rob Kaufmann 242 Proposed Changes to Koch Companies for Appendix W NAAQS Implementation Coalition

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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**  P R O C E E D I N G S 9:06 a.m. 1 Mr. Bridgers: Well, good morning, everybody, 2 and welcome to North Carolina. Thankfully the weat her 3 cleared through last night. I'm going to check rea l quick 4 with our court reporter and make sure that we are-- we're 5 clear? Okay. And we have a closed captioning serv ice 6 online, so I'm just making sure I have a mic check with Ms. 7 Tina. 8 I am George Bridgers. I'm with the Air Quality 9 Modeling Group here with the USEPA. Hopefully mostof you 10 will have seen my name along the way with the regis tration 11 and/or lining up the presentations. But I want to welcome 12 you here to the EPA facility and to the 11th Confer ence on 13 Air Quality Modeling. 14 I want to officially open the conference and that 15 of the public hearing that's related to the confere nce and 16 also with respect to the proposed rulemaking for th e 17 revisions to the Guideline on Air Quality Models

. 18 Before we have an opening remark and some other 19 remarks from Chet Wayland, I want to go through some 20 logistics real quickly about the conference and pub lic 21 hearing and also with respect to our facility here. 22 So it is clear, Congress in its infinite wisdom 23 back in--well, it started in '77, but then every th ree years 24 thereafter per Section 320 of Clean Air Act said th at 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**  to have a conference, a modeling conference, and th at is what 1 this is. They have to be transcribed and there has to be a 2 public record. 3 In addition, this conference, the 11th Conference, 4 is also serving as the public hearing, as I said ju st a 5 minute ago, with respect to the proposed revisions that we 6 are hoping to make with the Guidelines on Air Quality 7 Modeling . So every presentation today that's given will be 8 part of the record. Everything that's said will bepart of 9
the record. 10 Because this is a public hearing that's inter11 connected with public--or proposed rulemaking, we w ill not 12 have a question and answer session, so that's a lit tle 13 different than the 10th Conference on Air Quality Modeling. 14 And as I did when I started, I request that all spe akers when 15 they come to the microphone that they identify them selves and 16 if there's any affiliation that they're connected w ith. 17 I am the emcee and the public hearing officer, so 18 that means I drew the very short straw upstairs, bu t that 19 also means if you have any questions, if you have a ny 20 concerns, find me. Since Tyler Fox up here and Che t Wayland 21 are my supervisors, the chain above me, if you can' t find me, 22 find them. 23 But I will request, again, since we're in the 24 midst of a proposed rulemaking, that all of our oth er EPA 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**  brethren--that if there are specific questions abou t the 1 conference or anything with the proposed rulemaking , find me 2 or Tyler or Chet, and we'll delegate the questions as 3 appropriate. But we have to be sensitive to questi ons that 4 come in about our proposal. 5 We have a full schedule. We always do. Those of 6 you that have been to previous conferences and work shops know 7 that I try to run a tight ship, and I think that wehave 8 accommodated many of the speakers because we increa sed the 9 speaking time for the public presentations from 10 minutes to 10 15. And that also means that when we get to the op en forum 11 or the oral comments that we will also allow for 15minutes 12 or up to 15 minutes if there are people presenting oral 13
comments. 14 Most of you know that this is a pretty secure 15 facility. It's harder to get in here than it is toget in 16 most airports. Hopefully most of you through the 17 registration process didn't have any trouble gettin g in this 18 morning, but if you are leaving the foyer, the audi torium or 19 the cafeteria area here, you will need an escort he re on the 20 campus if you're in Building A, B, the upper floors of C, D, 21 E, or the High Bay. So if you leave, you know you have to go 22 back through security. 23 If you see a gentleman that's carrying a sidearm 24 and he tells you to do something, I would listen, a ssuming 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**  they have some sort of badge and they actually are security. 1 Actually, if someone is carrying a sidearm, I wouldjust 2 listen anyway. 3 For those of you that have not been to our campus, 4 I also wanted to pass along just some information about the 5 facilities. Bathrooms, most important: you don't have to 6 wait till breaks, although it's nice if we can. Ifyou go 7 back out the double doors here and go across the fo yer, 8 there's an alcove where the elevators are. Right b efore you 9 get to the elevators on the left are the bathrooms. 10 Snacks and lunch: a popular question, are we 11 offering refreshments? We are. They're for pay an d they're 12 across the hall at the Lakeside Café. And we're no t trying 13 to support the contractors; we just can't offer anything more 14 than water that's outside the bathroom. That's typ ically 15 mostly free. 16 But at any rate, across the way they have drinks, 17 coffee, some snacks during the morning and afternoo n, and 18 then they do have a full lunch selection. And I saw the 19 e-mail last week, Tyler. It was--they're having a cookout 20 day today or something, so I--just bear with them a cross the 21
hall. 22 But the point that I wanted to make here is that 23 we have a very full room. It looks like we're goin g to reach 24 standing room only shortly. So at 11:55, which is a little 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**  before the normal lunch hour, if all 200 of us get up and go 1 across the hall and stand in line, well, you'll be standing 2 in line with 200 people. 3 So we tried to make an hour, almost an hour and a 4 half--it's an hour and 20 minutes--lunch period so that some 5 of you may--if you're going to socialize during thelunch 6 hour or the lunch break, you may do it on the frontend 7 versus the back end so we can stagger people going through. 8 You're more than welcome to go ahead into the dinin g room and 9 sit down and chat while the line dies down or stay in here. 10 And there's--you know, you can come find me. We have some 11 WiFi if you need to check e-mail. 12 But at any rate, hopefully we can get everything 13 done in the hour and 20 minute time period, but theone thing 14 I will say, at least this afternoon at 1:20 we're g oing to 15 get the train back on the tracks so we can get thro ugh the 16
afternoon. 17 Also--and I will not put on my vest, my safety 18 vest and my hard hat, which I do have upstairs, whi ch is just 19 hilarious--if there is an emergency, if there's fir e alarms, 20 you'll hear somebody talking on the fire alarm syst em. I'm 21 your point of contact too. 22 The emergency egress for this building and for 23 this room is back up the stairs to which you came i n, and 24 then there's a small parking lot just past all 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**  construction right at the front on the left. That' s the 1 assembly area. It's technically Assembly Area 8. I think I 2 put that on the slide here. 3 But at whatever time the fire alarm--if it should 4 go off, I'll also make an announcement. Just follow me in an 5 orderly fashion. And if there's anybody that has-- that needs 6 assistance, there's an area of assistance I think r ight 7 outside the room, but we can figure that out. But hopefully 8 we won't have that. Hopefully there will be no fir e alarms 9 over the next couple of days. 10 And the other thing is that once the emergency is 11 over, myself, since I'm the point of contact for th e 12 conference, will be the one that gives the all clea r after I 13 get the all clear to come back in the building. 14 I would be--well, I should give lots of recogni15 tion. It takes a team; it takes a huge team here t o make 16 this happen. And so my brethren in the Air QualityModeling 17 Group from Tyler down through Kirk, Roger--I don't know if 18 Jim is in the room yet--both Chrises, Misenis and Owen, Brian 19 Timin, and James Thurman, all have provided invaluable 20 assistance, effort, energy to make this possible to day and 21 the proposed rulemaking come out the door. 22 And in addition we had a lot of help from the 23 front office, from our divisional front office. Wehad help 24 from OTAQ and also from all of our regional offices and our 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**  federal partners. So for all of that, we're very 1 appreciative. 2 And with that, I think, Chet, you are up, and 3 we're two minutes ahead of schedule. 4 Mr. Wayland: Very good. Well, thanks, 5 George. Before I make a few remarks, we've got a full house 6 here. How many people think it's kind of warm in h ere? Are 7 you guys okay there? All right. We will see if wecan get 8 the AC cranked down a little bit because this is go ing to be 9 a packed room and, you know, not that our speakers are full 10 of a lot of hot air, but it could get a little warmin here. 11 But I want to welcome you guys--Chet Wayland; I'm 12 the division director for the Air Quality Assessmen t Division 13 here in OAQPS, and the Modeling Group is under my p urview in 14 my division. And I'm really excited for you guys t o be here. 15 I was telling some folks this morning, you know, a lot of 16 times when EPA puts out a rule we kind of know whatthe 17 comments might be coming. 18 With this one I'm actually really excited because 19 I think we have tried to address a lot of things th at folks 20 have raised over the last many years. I know we pr obably 21 can't address everything that everybody wanted us t o address, 22 but I'm looking forward to the comments we're goingto get 23 because that's how we improve upon something, a pro duct that 24 we've already put out as a proposal. 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 in this case, you know, there's been a lot of 1 collaboration already from the beginning. I think it's--I 2 was talking to Jeff Masters just before I came up h ere, and 3 you know, we talked about in the old days how thereused to 4 be a lot of collaboration on the science, and I thi nk we're 5 trying to get back to that. And where we are with this 6 proposal, there has been a fair amount of collabora tion 7 leading up to this--this proposal between stakeholders and 8 the EPA here so that we can actually try to put thebest 9 science forward in our guideline models. 10 There's a lot of people that have been involved. 11 I know Pete Pagano at Iron and Steel, Cathe Kalisz at API-- 12 those folks have all worked with us on various, youknow, 13 field studies or data sets and things that we've be en able to 14 use as we've gone through and tried to upgrade the model and 15 improve the Guideline . And so I want to thank you guys for 16 that contribution. 17 I mean we're all at a place today, I think private 18 sector and public sector, where resources aren't wh at they 19 used to be, and so where we can work together and l everage, I 20 think we can develop a better product. 21 It is a guideline model, and as George said, this 22 is a public hearing, so we do want to get your feedback on 23 that, and we will be listening carefully obviously as we go 24 through this. But I thought it would be remiss notto thank 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**  all of you for not only being here but for what you 've 1 contributed up until this point. 2 It's been ten years since we last updated 3 Appendix W, and that's a long time. I wasn't even in this 4 job when that was--last occurred. In fact a lot ofthe folks 5 in the Modeling Group weren't even in the Modeling Group when 6 that last occurred. So I think it's--it has been along 7 time. It's been something that people have been wa iting for. 8 I'm fairly optimistic. I think we have tried to 9 address a lot of the issues that were raised, but I 'm also 10 very excited to see what kind of comments we're goi ng to get 11 and what we're going to hear today as well througho ut the 12 public comment period. 13 And I think we are going to try to address those 14 comments in a timely fashion and hopefully get a fi nal rule 15 out, you know, in the time frame that we're lookingfor, 16 which would be within the year, because we know howmuch 17 people are interested in having this final and bein g able to 18 use it. 19 So, you know, I just wanted to thank Tyler's staff 20 and his folks. I know how much time they've put in to this, 21 not only in the last, you know, two or three months getting 22 the proposal out the door, but in the last several years 23 working with many of you, the 10th Conference and o ther 24 meetings that we've had with state and local partne rs as well 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**  as with our federal partners and our stakeholders h ere today. 1 It has been a long process, but I think, you know, 2 if you're going to develop something worthwhile it takes 3 time. And I think, you know, what we have today is a much 4 better product that we had ten years ago. It's a b etter 5 product than we had a year ago. And a lot of that is because 6 of the work that people have done. 7 And Tyler, I just want to thank you and your 8 staff. I think they've done a tremendous job pulli ng the 9 proposal together, pulling these presentations toge ther 10 today, but also, you know, of reaching out and work ing 11 collaboratively, and I hope we can continue to go f orward and 12
do that. 13 Obviously there are rules as part of the comment 14 period. You know, during the comment period we'll take 15 information in. We'll evaluate it. But I don't wa nt people 16 to think that, you know, that's the end of the proc ess. I 17 would like to continue collaboration as we go forwa rd. 18 Even after this is final, let's continue the 19 scientific collaboration as we move forward in the years to 20 come because, you know, science never stops. It is always 21 evolving. We're always trying to get better. And even 22 though we do regulatory actions periodically, it do esn't mean 23 that it has to stop at that point. 24 So I've been really excited and impressed with 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**  collaboration we've had to date, and I hope we can continue 1 that even beyond this rulemaking as we continue to improve 2
the models and make them better and better. 3 So I hope this will be a great opportunity for you 4 guys to provide your input to us. We are going to be 5 listening carefully, and I'm looking forward to it. I know 6 it's a long process and public hearings can--you do n't have 7 as much time maybe as you'd like, but I appreciate- -you have 8 a full comment period after this, so obviously whatyou say 9 today will be put into the docket. But if you submit formal 10 comments, obviously they go into the docket as welland we 11 will be addressing those comments as we go forward. 12 So with that, I just wanted to thank you guys 13 again for being here. It obviously by the crowd he re shows 14 your interest in this particular proposal, and I th ink we 15 really understand how much this means to everybody and how 16 valuable this tool is because it's used in many, ma ny ways. 17 The one other thing I wanted to address that we 18 have tried to address is--probably if you've read t he 19 proposal you've seen it--was the petition from the Sierra 20 Club to deal with secondary formation of ozone and PM2.5from 21 a PSD standpoint. 22 You know, we had to deal with that kind of 23 independent of some of the collaborations we've hadwith you 24 guys because we were responding to a petition, but I think 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've put forward a good path there as well with a fair 1 amount of flexibility, so I'm really interested in seeing 2
comments on that. 3 This is something new. Some of the other things 4 are improvements, but this is something kind of gen erally new 5 that we haven't had to really address in the past a nd now 6 we're forced through the petition to make sure we a ddress it. 7 And so I'm really curious to see what kind of feedb ack we get 8 on that, and to you guys, what do you think about t he 9 flexibilities we've provided and so forth with that

. 10 So I'm not going to drone on because I want to get 11 to the heart of the discussion and have Tyler and h is folks 12 start walking through some things. And I'm real ex cited to 13 see your comments or hear your comments later on th is morning 14 and this afternoon. 15 Again, as George said, if you have any questions, 16 you know, logistically, track George down or Tyler or I. 17 We'll be happy to help you. Unfortunately, we can' t do a lot 18 of Q and A on the package itself because this is a public 19 hearing, but we'll look forward to continuing that dialogue 20 as we go forward, if not today. 21 So, well, thank you guys very much. I appreciate 22 your being here. And with that, I am going to turnit over-- 23 to you or to Tyler? Back to George. Thank you. 24 Mr. Bridgers: Perfect; thanks, Chet. Thank 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 so much, Chet. So Chet yields two minutes almo st to 1 Tyler Fox, so next up we have Tyler Fox, who is theAir 2 Quality Modeling Group's group leader. 3 Mr. Fox: I wanted to add my welcome to 4 everyone. I'm very excited for you all to be here. What I'm 5 going to attempt to do is provide a road map. You' ll hear 6 from each of the individual members who, as Chet an d George 7 indicated, have put in a lot of time and effort wit h you and 8 with their colleagues in getting us to this point. 9 And so I'm really here just to provide that 10 landscape, hopefully allow you to better connect th e pieces 11 and understand how they fit together and what our t hinking 12 was in putting these things together. 13 So obviously we all recognize that the rule was 14 published on July 29th. We are accepting public comment for 15 90 days. We knew that there would be quite a bit o f review 16 and time necessary to provide suitable review by yo u-all and 17 others. So that comment period goes through Octobe r 27th, so 18 even though we're hearing from you-all today, this is not the 19 end of hearing from you. This is just really the b eginning. 20 And so 70 some odd days from now, I'm sure you 21 will be busy testing code, evaluating our evaluatio ns, 22 providing more, you know, input and feedback of gre at value 23 to us, as Chet said, to then get to a final rule, which we 24 anticipate within the next year, the sooner the bet ter 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**  our standpoint. 1 We don't want it to go too far and get into the 2 presidential politic season and then have it get ki cked over 3 into the fall or beyond, if at all. So it is very important 4 that we get comments, that we then working with theregional 5 offices and the federal partners review those and g et to a 6 final rule in a very timely manner. 7 So let me start by going through the different 8 sections and giving you this overview. Sections 1 through 3 9 we really didn't do too much to, but they are criti cally 10 important in terms of setting the foundation for th e 11 Guidelineand what we do. The introduction clearly states 12 the purpose and the applicability of the Guideline . That was 13
not altered at all. 14 The overview of model use--we pulled in a number 15 of pieces from the old Section 9 on model accuracy and 16 uncertainty related to model performance and brough t that 17 forward into the discussion of suitability of model s, since 18 model performance evaluation is the ultimate way inwhich you 19 judge the suitability of models in terms of a fit f or purpose 20 type of paradigm. And so we brought those types of 21 discussions into Section 2 early on to set the stag e for 22 later portions of the Guideline . And we also tried to be 23 more clear in terms of the level of sophistication of air 24 quality models and providing definitions: screenin g/refined, 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**  demonstration tools, reduced form models. 1 In looking at this, we got confused ourselves with 2 screening/refined, screening techniques, screening models, 3 screening--you know, it was just very confusing as you read 4 through it. And so we really set upon a path to bevery 5 clear and very structured in how we refer to things because 6 the treatment of these models, given how we refer t o them and 7 the type or the distinction that we give them, is important. 8 And it's important because in Section 3 we provide 9 the rules of the game. And let me say that these rules of 10 the game have not changed, and I don't think they've changed 11 in two decades. They've been the same for a while. 12 Preferred models, we set out the specific 13 conditions that allows us to put a model in Appendi x A, which 14 means it's a preferred model. Those criteria are t he ones 15 that we adhere to in moving forward with models like AERMOD 16 and previously ISC--excuse me, and previously CALPU FF, so 17 those are clear so that the community at large know s what we 18 are holding ourselves to and what you hold us to interms of 19 preferred models, and as you want to put a model fo rward what 20 those criteria are. 21 Similarly for alternative models, those conditions 22 are still the same as they have been for decades, a nd it 23 makes clear to the community when a preferred modelis not 24 suitable, when it's not up to the task, an alternat ive model 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**  can be brought forward as long as it meets certain criteria 1 and conditions and goes through a process. That pr ocess has 2 served us well for many years and will continue to serve us 3 well, and we provide very--the clarity there in Sec tion 3. 4 And then we over the years have been using the 5 Model Clearinghouse and we've more formally codifie d that in 6
the Guideline , not that it's new; it's been existing as part 7 of the process for decades. We're just codifying t hat and 8 making it clear, and George will talk more about th at in his 9 presentation. 10 The next three sections really get into the meat 11 of things where we specifically identify--having identified 12 what the criteria are for preferred models and how we 13 evaluate the suitability of models and view models in 14 general, we identify those modeling approaches for inert 15 pollutants--we give the laundry list in the Guideline , so I'm 16 just putting inert pollutants here. 17 We then have Section 5, a new section for ozone 18 and secondary PM2.5 , and then a revised Section 6 that then 19 covers the outside of EPA models, guidance, approac hes, 20 procedures that other federal agencies are applyingin order 21 to meet Clean Air Act requirements. 22 So in Section 4 we are introducing AERSCREEN 23 formally as the screening model. We are establishi ng AERMOD 24 as the preferred model or reiterating it as the pre ferred 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. There are other preferred models in Appendi x A for 1 specific situations, OCD and CTDMPLUS for complex t errain, 2 and those still exist. They're there. 3 We are proposing to remove CALINE and replace it 4 with AERMOD for mobile sources, and we have integra ted BLP 5 into AERMOD, so that would mean that BLP would no l onger be a 6 preferred model in Appendix A. So we're trying to streamline 7 the process, bring better science and better tools, harmonize 8 those models so that we, you know, actually have a more 9 effective and efficient approach to addressing thes e 10 pollutants. 11 And then specifically we went in, as most of you 12 know, and modified the multitiered approach for NO 2as it 13 relates to the ambient ratio method, given work tha t API has 14 done, as well as the Tier 3 methods and updated tho se. And 15 Chris Owen will give you more details about that. 16 In Section 5, as Chet mentioned, we really broke 17 new ground here in response to the Sierra Club peti tion. 18 It's clear upon looking at the models and the techn iques that 19 are available that they are suitable to address sin gle source 20 impacts. 21 Kirk Baker and Jim Kelly have done a great job and 22 you-all have provided all the information to the li terature 23 and reports and the like that substantiate that cla im and 24 that assertion. And that's an important one for us to then 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**  move forward and say, okay, so now that the models are 1 capable, what is it that EPA would recommend and/orrequire 2 an applicant to do in the context of PSD. 3 So we cannot establish a preferred model or 4 technique at this point in time. Instead we're rec ommending 5 a two tiered approach with detailed guidance that a llows the 6 applicants to work with the state and local agencie s and the 7 regional offices to come up with the appropriate approach, as 8 Chet mentioned, the flexibility that we think is appropriate 9 and warranted here given the nature of the models a nd the 10 nature of the pollutants that we're dealing with. 11 In the preamble you'll notice that we also gave 12 some foreshadowing to EPA rules related to policy t ools that 13 are used in the PSD program. Particularly we refer enced 14 anticipated rulemakings and developing what we callmodel 15 emissions rates for precursors, or MERPs. MERPs ar e a good 16 thing, not a bad thing. You don't need any vaccina tion for 17
them. 18 And what you'll notice in the preamble is that we 19 try and provide information and in fact have put two memos 20 into the docket to try and, you know, flow chart sh ow you how 21 the system would work with that with this two tiere d 22 approach. In the PM2.5guidance we have a three tiered 23 approach, and the first is a qualitative type of as sessment. 24 What we anticipate is that the development 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**  these MERPs, which would establish an emissions level, that 1 if a source comes in below that level what EPA has done in 2 terms of demonstrating that level in being equivale nt to the 3 SIL value or significance threshold is sufficient t o meet 4 your requirements in demonstrating compliance for t he 5 precursor, so you are good to go and don't have to do any 6 additional analysis. 7 What now is a second tier and then a third tier 8 would then morph into what we're calling the first tier and 9 second tier of what's in Appendix W, the first tierbeing 10 using existing information, modeling, reduced form models, 11 other types of information short of full scale mode ling to 12 address that pollutant for that source, and then a second 13 tier, which would be full scale modeling that then Kirk's 14 guidance goes into a lot of detail in how to do tha t. 15 In Section 6 we clarified and worked very closely 16 with the Federal Land Management community. We have the role 17 of FLMs, the FLAG guidance, and AQRVs, specifically 18 visibility and deposition. We reference the FLAG guidance 19 and other guidance documents that the FLMs are resp onsible 20 for. And then we also acknowledge BOEM and the modeling of 21 OCS, the outer continental shelf modeling that goes on, as 22 well as FAA and their new tool, the AEDT tool, for air 23 quality assessments that has brought in AERMOD and also has 24 other capabilities. 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** 

One thing that I wanted to clarify because we've 1 gotten a lot of questions and it's clear that in th e preamble 2 we didn't provide as clear an explanation as perhap s we 3 should have, so we're likely going to put a memo tothe 4 docket along these lines, which is we're doing two things. 5 One is we're updating the regulatory version from 1 4134 to 6 15181 to address several bug fixes. And Roger is g oing to go 7 through that to be clear about what goes into now t he new 8 regulatory version. 9 At the same time, as part of this proposal, we are 10 recommending as part of the proposal use of specifi c data 11 options for public comment that then upon final rul emaking we 12 would codify and make as part of the regulatory def ault. 13 So I know a lot of people are saying, "Wait a 14 minute. Why aren't these things part of the regula tory 15 default now?" Well, we're in a proposed rulemaking . They 16 won't get codified until we go through the public c omment 17 process and then upon final rule, we'll bring in th ose 18 aspects, those elements that we're getting comment on, and 19 make those part of the regulatory default model. 20 That's why these options have remained in beta 21 form in the current version, 15181, to allow your t esting and 22 evaluation of those techniques. So I know there wa s some 23 almost disappointment in the proposal, but I just want to 24 make sure everybody is clear. We couldn't make them 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**  regulatory default. That would preempt the whole p rocess. 1 So we're going through the process, and at the end of the 2 process with your input we would expect to then cod ify those 3 in a final version of AERMOD. 4 We'll likely allow for some of these options to 5 remain as beta to facilitate continued testing and evolution 6 of things, but again, the whole process is one thatwould end 7 up with a regulatory default that would reflect tho se 8 changes, so hopefully that helps clear the air on t hat. 9 Also in terms of long range transport assessments, 10 I just wanted to reiterate that we're not--we no lo nger 11 contain language in Appendix W requiring the use ofCALPUFF 12 or any other Lagrangian model for long range transp ort 13
assessments. 14 Based on work that James Thurman and Chris Owen 15 have done, based on a variety of source and sector scenarios 16 from the AERMOD Implementation Workgroup, we did ve ry 17 detailed modeling that allowed us to come to the 18 determination and for your comment and input that we feel 19 that near-field modeling is sufficient in doing you r NAAQS 20 compliance demonstration. So we do not consider a long range 21 transport assessment necessary for inert pollutants beyond 50 22 kilometers or thereabout. So we're reducing the bu rden on 23 the community in terms of doing those assessments. 24 Now, we do recognize that long range transport 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**  assessments may be necessary for a limited number o f 1 situations for PSD increment, especially Class I in crement. 2 And so we've allowed for a screening approach. 3 Therefore, even though CALPUFF is not a preferred 4 model, it can be used as a screening technique alon g with any 5 other Lagrangian model, which are the typical model s used in 6 this context, to, again, sequence through a multist ep 7 screening with input from the regional office if yo u get to 8 that point. So it warrants the appropriate model when and 9 where necessary. And given our interactions with t he 10 regional offices, I think they can count collective ly on one 11 hand the number of instances in which a detailed PS D 12 increment analysis or cumulative analysis was done. 13 So we really felt that the need had been 14 diminished, especially when you start factoring in once you 15 comply with the NAAQS in the near field, the long-- the far 16 field impacts are far less. So we're reducing the onus and 17 the burden on the community of conducting those typ es of 18 analyses. 19 And then we ended with Sections 7 through 9 in 20 terms of how to inform and apply the models. So Se ction 7 21 had a lot of scrubbing. There still are specific 22 recommendations for dispersion models that you migh t not find 23 elsewhere and that are important to remind the community in 24 the context of Appendix W, but we removed a lot of details 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 were seemingly there because AERMOD in 2005 wa s new and 1 we wanted to err on the side of providing more info rmation. 2 I think after ten years a lot of that is not 3 necessary in Appendix W. It's more appropriate in other 4 documentation. And so we focused on certain critic al areas 5 of informing the model, and in particular dispersio n models, 6 for the community to understand and better apprecia te and 7 engage with us on. 8 And then in Section 8 we did do a lot of work in 9 terms of looking at the model input data. You'll h ear from 10 George later that the modeling domain we are limiti ng. We've 11 mentioned over and over again the overly conservati ve 12 aspects, particularly of the resource manual, and s o that 13 will end with this Appendix W. The modeling domainwill be 14 no more than 50 kilometers for NAAQS, and that's--I mean 15 that's in there. 16 We also talk about modeling domains for SIP 17 demonstrations for ozone and PM2.5 , and we have very much 18 tried to distinguish PSD and single source assessme nts versus 19 SIP demonstrations for control strategy purposes an d ozone 20 and secondary PM. So we're trying to be very clear

. 21 On source data we've clearly outlined that nearby 22 sources for the most part we would prefer that theybe 23 captured in terms of their impacts and contribution s through 24 ambient monitoring data, and if they need to be exp licitly 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**  modeled, they can be modeled with actual emissions. Tables 1 8-1 and 8-2 have been modified appropriately and ac cordingly. 2 And in terms of background concentrations, we try 3 and more clearly lay out the construct of single so urce-- 4 isolated single source situations and multisource s ituations 5 such that you're putting together more representati ve, more 6 appropriate characterizations of contribution from the 7 different sources and not overly conservative ones. And so 8 we've tried very much to remedy that situation. 9 And in terms of meteorological data, you'll hear 10 from James in terms of bringing in prognostic information. 11 You know, we've got difficulty and we know the mete orological 12 inputs are critically important, so we want to haveflexi13 bility in terms of bringing in more representative data, and 14 the prognostic data allow us that opportunity. 15 And so we've been talking about this since the 8th 16 Modeling Conference, I believe, and now finally it' s a 17 reality. And thanks to the hard work of James, Chr is, and a 18 number of other folks in the community, bringing th ose 19 prognostic data and sharing them for use in dispers ion models 20 as they are for photochemical and other models is agreat 21
advancement. 22 And then finally we end with the regulatory 23 application of models, very strong emphasis on mode ling 24 protocols, and then provide a very clear descriptio n, much 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**  clearer than I think we've had in the past, of the multistage 1 approach to demonstrating compliance, the single so urce 2 assessment of oneself vis-à-vis a significance thre shold and 3 then a cumulative impact assessment and evaluation of whether 4 or not you are contributing significantly to a pote ntial 5 violation or a model violation and how that process works. 6 So we go through the whole process and end with-- 7 you know, once you know the rules of the game, onceyou know 8 what models to apply and how to apply them, then th e context 9 in which you know you do that in your compliance demon10 stration. And we end with the use of measured datain lieu 11 of model estimates, not changed too much, but we'restill 12 struggling with examples and situations that eviden ce this 13 type of approach. 14 So this flexibility is still there. How it will 15 be put into practice is still an outstanding questi on, and we 16 would very much welcome input and thoughts from you -all if 17 you have situations that you think are evidence of that type 18 of approach. 19 So I don't know long I went, but thank you very 20 much. And now all the detailed presentations will allow you 21 to better understand each section and change. 22 Mr. Bridgers: Actually, Tyler, I've got a new 23 tool for our 101s in my yearly reviews right here. 24 Mr. Fox: It won't work. You always talk 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**  too long. 1 Mr. Bridgers: Oh, oh, right; that was last 2 night. I want to make two quick announcements, jus t kind of 3 roaming around the room. I realize that we are ful l on 4 seats. There's actually still some seats in this f ront row 5 up here, and there's a row right up here that durin g the 6 break I'll pull these seats forward so there's a li ttle more 7 flexibility, but there's probably, I don't know, ma ybe as 8 much as a dozen seats up here and we'll see during the break 9 if we can get a few more. But we had over 260 seat s in the 10 room, and so we'll accommodate that. 11 And the other thing is I do note that the screen 12 is sort of low and I know some in the back can't se e 13 everything. I was going to make this announcement later. 14 All the presentations that are given today and tomo rrow are 15 going to be posted on the web, but there's an Easte r egg, if 16 people know what Easter eggs are. It's actually al ready 17 posted on the web. 18 If you go to our 11th Modeling Conference page, 19 which most of you will know, and scroll down to theagenda 20 and click on it, I have embedded links for all the talks. 21 And so Roger's talk that he's getting ready to giveis there. 22 So if you have WiFi and you can't see from the backand you 23 can get to our 11th page and you can click through, you can 24 get to the presentations. All these presentations will also 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 loaded to the docket, as I said earlier. 1 So I will call Roger Brode to the podium. And 2 Roger is going to give two talks. The first talk i s 3 specifically aimed at the regulatory update that wejust made 4 with AERMOD version 15181, and then we'll switch an d have a 5 separate presentation that will talk about the prop osed 6 options. 7 So hopefully there's a good distinction here 8 between our regulatory release and what the propose d options 9 are in the revised version of AERMOD along the line s of what 10 Tyler gave a primer on just a minute ago. So Roger ? 11 Mr. Brode: Thank you, George. So again, 12 I'll talk about the update to the regulatory option s within 13 AERMOD that were just basically bug fixes. In the next talk 14 we'll talk about some of the proposed beta options and what 15 we've been doing there. 16 So the regulatory version of AERMOD and AERMET has 17 been updated to version 15181, which corresponds wi th June 18 30, 2015. And they include several bug fixes for AERMOD and 19 AERMET, which I'll kind of go over highlights of th at next. 20 We've also incorporated some proposed enhancements to the 21 non-default/beta options which are going to be disc ussed in 22 the next presentation. And these updates are documented in 23 Model Change Bulletin 11 for AERMOD and MCB6 for AE RMET. 24 So one of the key bug fixes that's been sort 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**  out there for a while but hardly ever reared its he ad, but 1 did not that long ago, something we've identified a nd 2 addressed in the AERMOD Implementation Guide, whichis that 3 if you have a relatively tall stack in a relativelysmall 4 urban area--relative is a relative term, but we've noticed 5 that some unrealistically high concentrations due t o the way 6 plume rise is calculated--there's sort of an unreal istic 7 limit on plume rise--may show up. 8 And this has been addressed in the AERMOD 9 Implementation Guide quite a few years ago, which s ort of 10 suggested those sources may be better treated as ru ral with 11 some adequate justification. And again, this is anissue 12 that didn't come up very often, but did not too lon g ago from 13 Region 5, the state of Michigan in fact. 14 So the new version has addressed that as a 15 formulation bug fix, and the approach that we used sort of 16 emulates the penetrated plume algorithm that's usedunder 17 convective conditions. And the next slide is goingto give 18 an example of a tall stack with--an urban area with55,000 19 population, and it will show the before and after. 20 So the before on the left, the red curve is the 21 urban curve and the blue curve is rural. Again, th at was 22 before. And the next slide, after, it shows a very , very 23 significant, about a factor of 10 higher with urbanoption 24 for that source over the rural. And then the rightslide 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**  shows, you know, that they're in much better agreement, so 1 much more reasonable from what you would expect. 2 We don't have a lot of data to evaluate this, but 3 this was the case, and the new concentrations with the urban 4 option show much better agreement with nearby monit ors in 5 that case, which is in the Detroit area. 6 So in terms of bug fixes again, there weren't that 7 many, but there was a issue that showed up with thePOINTCAP 8 beta option for capped stacks and determined that i f you use 9 POINTCAP with the no stack-tip downwash option, youcould get 10 some erroneous results because the POINTCAP option itself 11 takes care of how stack-tip downwash would be treat ed. 12 We also corrected an issue with the emission rate 13 being modified for area, line or open pit sources i n some 14 cases with the FASTAREA or FASTALL option. And the re are 15 some pretty anomalous results that had shown up in some cases 16 there. We believe those have been fixed now. 17 And another issue that had been brought up a while 18 back, and I don't have the details here, but there was an 19 issue if the wind is blowing nearly perpendicular t o an area 20 source or a line source, an elongated area source, some very 21 anomalous results showed up there. And it turned o ut that 22 one of the tolerance levels in the area source algo rithm was 23 a bit too splat, so we tightened that and that seemed to 24 clarify that--clean up that issue. 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 are a number of subroutines related to 1 the PVMRM option, one of the beta options for model ing NO 2 . 2 And basically a lot of it focused on the penetratedsource 3 contribution and did a more explicit treatment of t he 4 vertical and horizontal dimensions of the contribut ing 5 sources for that penetrated plume component. And t hat turned 6 out to show up with some importance in the New Mexi co Empire 7 Abo evaluation database. 8 We also modified the determination of NO x 9 concentrations to account separately for the horizo ntal plume 10 component and the terrain responding plume componen t. So 11 there are some aspects of the overall general formu lation of 12 AERMOD that have been incorporated more fully withi n the 13 PVMRM algorithm for NO 2 . 14 Continuing on bug fixes, there are some issues 15 that showed up with the use of the DAYRANGE keywordwhere you 16 could specify a range of days to process for indivi dual days, 17 and those could be specified either as a month/day or as a 18 Julian day. And it turned out there were some issu es if you 19 define those day range inputs for a leap year versu s a non20 leap year. That wasn't being handled properly, so that's 21 been taken care of and those issues, as far as we know, were 22 resolved with this update. 23 In terms of AERMET bug fixes, there weren't that 24 many, but we did make some changes to the ADJ_U* op tion 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**  AERMET that's used without the Bulk Richardson Numb er method. 1 And we made some modifications basically to be more 2 consistent with that original paper by Venkatram an d Qian, or 3 Qian and Venkatram. 4 And in the process we also noticed a bug with the 5 Bulk Richardson Number option in AERMET where the c alculation 6 of the CDN was incorrectly using Z0, or Z2 over Z0 instead of 7 ZREF over Z0. Those are the bug fixes, so I yield some of my 8 time to the next slide. 9 So this talk will be talking about the proposed 10 updates to the AERMOD Modeling System. So I begin with 11 version 12345, which is a version I wish we could h ave kept 12 forever because it's so easy to remember, but we in corporated 13 some non-default/beta options to address concerns r egarding 14 model overpredictions during stable/low wind condit ions. 15 And we have to acknowledge the contributions of 16 API, which funded a low wind study that AECOM condu cted back 17 in 2010, I guess, and that certainly helped move th e ball 18 along to address this issue. So there is non-defau lt options 19 that include the LOW_WIND option in AERMOD and the ADJ_U* 20 option in AERMET. And so the proposed updates to t hese 21 options are discussed here. 22 So there are going to be some additional updates 23 to the regulatory options that are being proposed, including 24 a buoyant line source option, which was mentioned e arlier, 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**  eliminate the need hopefully for the BLP model as aseparate 1 preferred model. And also we're going to address t he capped 2 and horizontal stack issue. And these updates are going to 3 be subject to public review and comment and then wo uld be 4 codified as part of the final rule action as approp riate, as 5 Tyler mentioned. 6 So again, beginning with 12345, AERMOD included 7 these low wind beta options. Prior to 15181 AERMODincluded 8 a LowWind1 option and a LowWind2 option. And basic ally this 9 just addresses the minimum value of sigma-v, the ho rizontal 10 dispersion coefficient. 11 So the LowWind1 option that we put in there 12 eliminates the horizontal meander component that's a part of 13 AERMOD and also increases the minimum sigma-v from the 14 default, currently at 0.2 meters per second, to 0.5meters 15 per second. 16 We also added a LowWind2 option that retains the 17 meander--horizontal meander component, but put an upper limit 18 of 0.95 on that, and then also increased the minimum value of 19 sigma-v from 0.2 to 0.3. And these two options aremutually 20 exclusive. You can't try to use both of them at th e same 21 time. So that was part of the initial foray into t hese beta 22 options for addressing low wind issues. 23 So with version 15181 we've added a new low wind 24 option, and for the lack of a better option we callit 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**  LowWind3. So this is sort of kind of a hybrid of t he two in 1 a way. It increased the minimum sigma-v from 0.2 t o 0.3, 2 which is consistent with the LowWind2 option, but e liminates 3 upwind dispersion, which is consistent sort of withthe 4 LowWind1 option, but it doesn't just ignore meander

. 5 So the LowWind3 option uses the effective sigma-y 6 value that would replicate the centerline concentra tion 7 accounting for meander, but then it puts a limit onthe 8 lateral spread at 5 sigma-y off the centerline, so it's 9 similar to the FASTALL option that's in AERMOD thatsort of 10 does that, so it replicates centerline concentratio n--or the 11 contribution of meander to the centerline concentra tion, but 12 just enhances the spread but doesn't include full upwind 13 dispersion. 14 So we proposed in the notice of proposed 15 rulemaking that the LowWind3 option be incorporatedinto the 16 regulatory version of AERMOD, while the LowWind1 an d LowWind2 17 options are still available for testing purposes. 18 So the other key beta option that we've been 19 dealing with especially focused on the low wind iss ues is the 20 beta ADJ_U* option in AERMET. And there's an ADJ_U * option 21 in AERMET that's associated with the Bulk Richardso n Number 22 option in AERMET to use Delta-T data, and that's be en 23 modified to include a more refined treatment of θ* and to 24 extend its suitability or applicability to very stable/low 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**  wind conditions based on a more recent paper by Luh ar and 1 Raynor, and that actually seems to have helped someof the 2 evaluations that we've seen. 3 So this updated ADJ_U* option in conjunction with 4 Bulk Richardson also includes some modifications inAERMET-- 5 in AERMOD, pardon me--to subroutine TGINIT to calcu late θ*. 6 And some of the issues that we've dealt with on the se new 7 options is, you know, the--is very low wind speed c onditions 8 and it can be surprisingly sensitive in terms of pr edicting 9 the profile of potential temperature gradients. 10 So we have proposed in the notice of proposed 11 rulemaking that the ADJ_U* option either with or wi thout the 12 Bulk Richardson option in AERMET be incorporated as part of 13 the regulatory version of the modeling system, so i t's part 14 of the proposal. 15 So capped and horizontal stacks, this is an issue 16 that's been around for some time. Back in 1993 theModel 17 Clearinghouse had issued a memorandum that provided 18 recommendations for modeling capped and horizontal stacks, 19 and that procedure involved setting the exit veloci ty to a 20 very low number, .001 meter per second, but adjusti ng the 21 stack diameter to maintain the actual flow rate andbuoyancy 22 of the plume. So that's something that would be do ne by the 23 user to modify the inputs to the model. 24 However, the PRIME numerical plume rise algorithm 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 building downwash that was incorporated in 2005 , I guess, 1 with AERMOD uses the input stack diameter to definethe 2 initial radius of the plume, and use of a very larg e 3 effective radius may alter the results in physicall y 4 unrealistic ways. In fact, we found cases where th e model 5 would crash because the--when that was being done. 6 So that prompted the need to do some different 7 approaches. The AERMOD Implementation Guide actual ly 8 suggests just setting the exit velocity to a very l ow number 9 and use the actual stack diameter as an interim sol ution. 10 However, that could produce--introduce some bias towards 11 overprediction there. 12 So we eventually had--since version 06341 we've 13 had some draft/beta options to model capped and hor izontal 14 stacks more explicitly, and but they're again not-- they're 15 non-default beta options. So POINTCAP and POINTHORsource 16 type is used to trigger these, and the user just inputs the 17 actual stack exit velocity and stack diameter. 18 So for non-downwash sources it basically 19 implements the Model Clearinghouse procedure from 1 993, 20 although there are some subtle differences in AERMO D as 21 opposed to ISC, so the POINTCAP/POINTHOR, that opti on 22 actually accounts for the vertical profiling of met eoro23 logical conditions in AERMOD that's more detailed t han within 24
ISC. 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 the POINTHOR--the horizontal stack option 1 actually uses the exit velocity assigned input to t he model 2 as the initial horizontal velocity of the plume, an d so the 3 issues that showed up--again, the prime downwash op tion uses 4 the numerical plume rise approach, and that actuall y can 5 account directly for the horizontal trajectory of t he plume 6 for horizontal stacks. 7 For the POINTCAP option with downwash, the initial 8 plume radius is assigned to be twice the input stac k 9 diameter--I guess that shouldn't be the plume radiu s, the 10 diameter--to account for initial plume spread from the cap 11 interacting--the plume interacting with the cap, an d the 12 initial horizontal velocity is assigned to be basedon the 13 exit velocity divided by 4. So it sort of has some 14 horizontal momentum to it but some vertical as well , rise. 15 So buoyant line sources--again, we've discussed 16 this briefly, but Appendix W currently recommends t he use of 17 the BLP model for modeling these sources, but the B LP model 18 is based on some outdated dispersion theory, P-G di spersion 19 coefficients, and the meteorological data processorfor BLP, 20 PCRAMMET, is not capable of processing the current meteoro21 logical data that we're using, including the 1-minu te ASOS 22 data. So there are some complications and limitati ons on 23 being able to apply BLP well. It also lacks the pr ocessing 24 options that would support the form of the new one hour 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**  and NO 2standards as well as the 24 hour PM2.5NAAQS. 1 So beginning with version 15181, AERMOD includes 2 an option to model buoyant line sources using the BUOYLINE 3 source type. And it allows for using the buoyant l ine-- 4 modeling of buoyant line sources using meteorologic al data 5 that are processed through the AERMET meteorologica l 6 processor. It also allows the use of the AERMOD pr ocessing 7 options to support the form of the new standards. So 8 basically it just takes--it actually takes the inpu ts and 9 calls the BLP model directly. 10 So now we'll talk about some of the evaluations of 11 the proposed updates. There's a lot that's gone onhere. 12 I'll try to cover some of the highlights. But we h ave again 13 the proposed beta ADJ_U* option in AERMET and the L ow_Wind 14 option in AERMOD. 15 And they've been evaluated based on several 16 relevant field studies, including--as I mentioned h ere, there 17 was a 1993 surface coal mine study, Cordero Rojo mi ne in 18 Wyoming, that was fugitive emissions of PM 10in 24 hour 19 concentrations, and this was done with version 1413 4. We've 20 also had two low wind studies that were part of theAPI-AECOM 21 low wind study, the '74 NOAA Oak Ridge, Tennessee s tudy and 22 the Idaho Falls study in the same year. 23 So just some general caveats on model evaluation: 24 it's a complex business, especially in these very e xtreme 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**  conditions, very low wind speeds. Slight errors or 1 uncertainties in the wind direction or wind speed c ould 2 significantly affect the concentrations, and it wou ld affect 3 the conclusions from the model performance evaluati on, so 4 keep that in mind. 5 So quickly, the surface coal mine study--we've 6 shown this before, and the results presented here a re 7 actually based on the previous version of AERMOD, b ut it was 8 a two month field study. Again, it was largely dri ven by 9 fugitive emissions from road dust from the trucks d riving 10 around the mine. And we were able to apply the Cox -Tikvart 11 protocol for determining the best performing model to this. 12 We presented these results based on version 14134, but the 13 results are likely to be similar for the current ve rsion. 14 That just shows a schematic of the mine, and this 15 is the composite performance measure that shows wit h 16 confidence intervals the different options. Starti ng from 17 the top, the top three are with ADJ_U*. The top on e is with 18 ADJ_U* and LowWind2, then LowWind1, and then no lowwind. 19 And there's very little differentiation between thelow wind 20 options there. 21 But the bottom three are without the ADJ_U* option 22 in AERMET, so the default, and there's a little bitmore 23 difference in the low wind options, but the key thi ng is that 24 the top three are closer to the left side, and thatmeans 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**  better performance, so a smaller value of CPM does imply 1 better model performance. 2 More importantly maybe, the model comparison 3 measure is the--compared the performance of one model against 4 another. So in the top three, again, that shows pe rformance 5 with and without the ADJ_U* option for the differen t low wind 6 options, and the key point there is that those conf idence 7 intervals, the horizontal bars, do not cross zero, and that 8 suggests that the difference in performance is stat istically 9 significant, and that's the key point here. The bo ttom three 10 just basically show the differences between the lowwind 11 options. Again, there's very little differentiatio n there. 12 So again, the low wind option--the LowWind1 13 options in AERMOD appeared to have limited effect o n model 14 performance in this case, but it does show signific ant 15 improvement with the ADJ_U* option. 16 So that brings us to the Oak Ridge and Idaho Falls 17 studies, which are really the more relevant and keydatabases 18 that we've been working with that API and AECOM int roduced a 19 few years back. It's sort of sad to see that the b est tracer 20 studies are from the mid '70s, but at least we stil l have 21 that data intact. 22 So there are just some caveats and I won't go over 23 the details, but it's--especially under these extreme 24 conditions some of these issues or decisions you mi ght make 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**  may have a little bit more relevance. So EPA assumed a 1 different surface roughness for Oak Ridge, .6, comp ared to 2 the original assumption in the AECOM/API study of . 2. 3 One of the complications with the Oak Ridge study 4 is the winds were so low that they couldn't measurethem, and 5 so the wind speeds reported were based on laser anemometry. 6 And so basically it's the Oak Ridge peninsula, so t here are 7 some hollers in there, in the Oak Ridge peninsula i tself, and 8 they had laser anemometry based on lasers that wereup on the 9 ridges, and where those lasers intersected was abou t 20 10 meters above the bottom, where the source was. 11 So we made a different assumption about the 12 measurement height, and it doesn't necessarily chan ge the 13 results that much, but we also made some adjustment s to the 14 surface roughness for these studies. 15 So that's the Oak Ridge area. You can see there's 16 some terrain there; you can see where the arcs are. So this 17 is some of the results with the version 15181. Thepaired 18 concentrations are on the left. The predicted to observed 19 ratios are on the right. This is done by arc. So you can 20 see with the default options there's pretty signifi cant 21 overprediction at this site. 22 When we bring in the ADJ_U* option and LowWind2-- 23 well, without the ADJ_U* and LowWind2 it does impro ve things 24 somewhat noticeably. On the right side it's the comparison 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 LowWind3 option in the newer version of AE RMOD 1 without the ADJ_U*, so the low wind option does make some 2 impact here. 3 This is with ADJ_U* and no low wind. On the left 4 it's the previous version; on the right it's the ne wer 5 version. And it eliminates much of that overpredic tion, but 6 there's still a pretty wide spread. 7 This is with ADJ_U* and LowWind2 versus LowWind3, 8 and it looks pretty good on the left. There's a li ttle bit 9 below the 1 to 1 line on the right with the LowWind 3 option, 10 but again, there are some additional caveats here, is that 11 there is terrain as part of the Oak Ridge site, andthat has 12 not been accounted for in the evaluation that API d id or that 13
we've done here. 14 This is the Idaho Falls study area. You can see 15 where the arcs were--the 100, 200, 400 meter arcs were 16 situated, but it's pretty flat, much different thanthe Oak 17 Ridge. So these results are paired by arc again, a nd with 18 the default options there is some overprediction, r oughly 19 about a factor of 2 overall, but it's pretty consis tent with 20 distance. 21 Without the ADJ_U* with LowWind1 (sic) on the left 22 for the previous version, LowWind3 on the right forthe new 23 version, eliminates most of that overprediction andactually 24 looks pretty good just with the low wind options. 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 ADJ_U* and no low wind, again, it eliminates 1 most of that overprediction, but there's a little b it of 2 tendency with distance for the ratios to go down, b ut maybe 3 that's okay. With the ADJ_U* and the low wind opti ons, the 4 predicted is really good at the closest arc, which would 5 probably be the most important for this, but still pretty 6 good performance overall. 7 And this is with the--that was--so these are all-- 8 the previous results were the degraded 1-layer data , but the 9 one thing that the Idaho Falls study provided is wegot the 10
raw data and we were able to calculate some Delta-Tmeasure11 ments so we would be able to use the Bulk Richardso n Number 12 option in here, and this is one of the more surpris ing 13 results, that without the ADJ_U*, the Bulk Richards on Number 14 option didn't work that well, especially at the clo sest arc. 15 You can see a pretty wide spread and quite a bit ofunder16 prediction at the 100 meter arc. It got a little b it better 17 downwind. With the ADJ_U* and Bulk Richardson, theresults 18 actually look much, much better, so that was an enc ouraging 19
result. 20 So that kind of wraps it up. I can't take any 21 questions, which is fine by me. Thank you. 22 Mr. Bridgers: Thank you, Roger. Actually, 23 that was saying 15 more minutes, so--- 24 Mr. Brode: (interposing) Okay. Do you 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**  want me to keep going? 1 Mr. Bridgers: No. James had already yielded 2 some time to you. I didn't want you to feel too ru shed 3 because that was an important presentation because that gets 4 at the heart, at least the front end, of what's in our 5 proposal. 6 So next up, James Thurman from our Modeling Group 7 is going to give us a quick presentation--I'm not g oing to 8 even run this, James; I know you'll be done ten min utes--on 9
AERSCREEN. 10 Dr. Thurman: Okay. This will be the best 11 presentation from EPA today because it's only four slides. 12 I'm James Thurman from the Modeling Group to give you a quick 13 update on AERSCREEN. 14 This slide shows the status of AERSCREEN through 15 the years, first mentioned in the 2000 (sic) Guidelinewhen 16 it said it would be released in the fall of 2005, b ut it made 17 it till 2011 where we released AERSCREEN and the ac companying 18 meteorological processor MAKEMET to generate the sc reening 19
met. 20 We also issued a memo in April of 2011 21 recommending AERSCREEN as the recommended screeningmodel for 22 EPA, because it's based on AERMOD, which represente d the 23 state of the science. And just to remind you, AERS CREEN is 24 only done for single sources only. It doesn't havethe 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**  multisource capability. 1 And then for the proposed Guidelinefor 2015 we're 2 incorporating AERSCREEN into the Guidelineas the screening 3 model for AERMOD, and it will be applicable in all types of 4 terrain and building downwash applications. And AE RSCREEN is 5 discussed in detail in Section 4.2.1.1 of the propo sed 6 Guideline

. 7 I'll just note the latest version of AERSCREEN, 8 15181. We incorporated the inversion break-up fumi gation and 9 coastal fumigation options from SCREEN3. That was probably 10 one of the last reasons people were running SCREEN3other 11 than AERSCREEN is too hard to run, which as Tyler a nd I say, 12
real men run AERSCREEN. 13 It uses the AERMOD equations for the sigma-y and 14 sigma-z estimates used in the fumigation calculatio ns. And I 15 won't go into detail here, but you can see the AERS CREEN 16 User's Guide for full details on how these fumigati on options 17 are incorporated. 18 We also tried to make the code more portable 19 across operating systems by eliminating system call s to copy 20 and delete files when possible, so we actually do F ortran 21 statements to the write and delete. There are stil l some 22 system calls like clearing the screen, but we've pu t in the 23 code and commented out for the Unix and Linux optio ns of 24 clearing the screen and also added a debug option t o output 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 intermediate output from the PROBE and FLOWSECT OR 1 subroutines and also output the intermediate fumiga tion 2 estimates if you want to see what was going on besi des the 3 final results, and we also did some bug fixes. 4 And one thing on the fumigation options, I did 5 change it where you don't have to run AERSCREEN anddo all 6 the AERMOD screening runs inside AERSCREEN. It wil l actually 7 just do the fumigation options, so you can usually get a 8 quick result there. 9 And then on MAKEMET we incorporated the ability to 10 adjust the surface friction velocity, U*, based on the AERMET 11 adjustment algorithms. That was done to help Chris Owen's 12 work on mobile source modeling. Right now this U* adjustment 13 is not done when you're calling MAKEMET from AERSCREEN. It 14 sets that option to no, but if you want to run the U* adjust15 ment with MAKEMET, you can do that outside of AERSC REEN by 16 running MAKEMET on your own. 17 We may incorporate the ability in future versions 18 of AERSCREEN to make it an option to do a U* adjustment, not 19 for like regulatory screening runs, but if you justwant to 20 get a quick result of how much change the U* adjustment will 21 make on your results. And then that's it, and I yi eld my 22 time to Chris. 23 Mr. Bridgers: In the interest of political 24 correctness, it would be real modelers run AERSCREEN. I want 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 make sure that we stay aboveboard. 1 While I'm changing presentations, I also wanted to 2 point out, since I'm the point of contact on the SC RAM web 3 site updates, AERMOD 15181, AERSCREEN 15181, and MAKEMET 4 15181, they were all posted when we posted the prop osal. 5 Just so that we're also crystal--as clear as we 6 can be, if you go to the 11th Conference Modeling p age, there 7 are some specifics for each of the postings of the model, but 8 if you're going for the regulatory release, I recommend going 9 to the other part of SCRAM where you normally woulddownload 10 AERMOD or AERSCREEN because all the model change bu lletins 11 and the other supporting information from its regul atory 12 application is there. So if you're using the link for the 13 11th Modeling page to download the model, I'd recommend going 14
over to the other. 15 All right. So we will transition from screening 16 and the demise of SCREEN3 in the regulatory applica tion to 17 changes with respect to NO 2with Chris Owen, and Chris, I'm 18 going to give you a little extra time. You lucked out. 19 Dr. Owen: Thanks, George. It looks like 20 James actually yielded his time to you, but that's okay. I 21 think we can get through this in time. And actuall y with the 22
NO 2modeling we're still referring to screening, just of a 23 slightly less conservative nature. 24 So I'm going to give an overview of the proposed 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**  changes to AERMOD and Appendix W with respect to NO 2 1 modeling. I'd like to thank my workgroup, which co nsisted o 2 of members from OAQPS, Regions 3, 4, 5, 6, and 10, and the 3 Office of Research and Development. 4 In short, EPA is proposing to modify both AERMOD 5 and Section 4.2.3.4 of Appendix W. These proposed changes 6 will incorporated ARM2 as the regulatory default op tion for 7 Tier 2 screening. It will adopt OLM and PVMRM as t he 8 regulatory default options for Tier 3 screening, an d we will 9 actually be updating PVMRM with additional dispersi on and 10 plume calculations, currently dubbed PVMRM2. 11 This slide gives some details on the ARM2 12 adoption. ARM2 or the ambient ratio 2 method was o riginally 13 developed by an API funded study. The study was eventually 14 published in a peer reviewed journal article in 201 4 by Marc 15 Podrez in Atmospheric Environment . The proposed version of 16 ARM2 in Appendix W and AERMOD has one modification to the 17 version that was provided in the final published paper, and 18 that is we propose to modify the minimum default ambient NO 2 19
to NO xratio to 0.5. 20 This proposal is to bring consistency between the 21 Tier 2 and Tier 3 methods. Specifically we have a 22 recommendation for the default NO 2to NO xin-stack ratio for 23 the Tier 3 methods to be equal to 0.5. The slide h ere shows 24 some model simulations comparing PVMRM with an in-s tack ratio 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 0.5 and an in-stack ratio of 0.2. 1 You can see that when you use PVMRM with this 2 recommended default, 0.5, your ambient NO 2to NO xratios are 3 also equal to 0.5, and thus we believe that the min imum 4 ambient NO 2to NO xratio for ARM2 is most appropriately set 5 to 0.5 to be consistent with the Tier 3 methods. 6 For the OLM and PVMRM adoption and implementation, 7 this will be very similar, what we currently have i n the 8 model and what we've recommended in past Guidance . That is 9 there will be no default background ozone value. We're 10 recommending a maximum ambient NO 2to NO xratio of 0.9 for 11 the Tier 3 options. 12 We're also recommending a default in-stack ratio 13 of 0.5 for the primary source and nearby sources. However, 14 for more distant sources we're recommending an in-s tack ratio 15 of 0.2. We do actually specify now in the reg textthat 16 PVMRM works better for relatively isolated and elevated point 17
sources and OLM tends to work better for other sour ce types. 18 With respect to the modifications to PVMRM that 19 we've dubbed PVMRM2, the PVMRM2 uses absolute rathe r than 20 relative dispersion coefficients under stable wind 21 conditions. There are several modifications in PVMRM2 to the 22 computation of the plume volume, and there are seve ral 23 additional miscellaneous bug fixes that are include d in 24 PVMRM2. Our proposal is to eventually replace PVMRM 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**  PVMRM2. However, in version 15181 we have both PVMRM and 1 PVMRM2 to facilitate evaluations of the two differe nt model 2 codings. 3 We provide in our technical support document 4 several evaluations of PVMRM and PVMRM2. The slidehere 5 provides an example from the Empire Abo gas plant i n New 6 Mexico which compares results from full conversion, PVMRM2--I 7 actually can't see it on the computer here--PVMRM, and I 8 think it's OLM Group all. And the slide here doesn 't give 9 very good detail. I again recommend that folks loo k at the 10 technical support document that's provided on this for easier 11 viewing. 12 The slides here do show if you can see that PVMRM2 13 is the best performing of the options that are eval uated for 14 this particular--these two particular monitors for this one 15 particular source. 16 Finally, I'd like to emphasize what Tyler said 17 earlier with respect to beta options in AERMOD, so the status 18 of the Tier 2 and Tier 3 screening methods. All ofthe NO 2 19 options are defined as screening techniques. If Appendix W 20 goes forward as proposed, then the NO 2options will no longer 21 be alternative models. They will not need approvalby the 22 regional office. 23 However, as screening methods, the reg text will 24 specify that their use will occur in agreement withthe 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**  appropriate reviewing authority, and this is specif ied in 1 Section 4.2.1(b) of the proposed version of Appendi x W. 2 Additionally, because of the complexities of the 3 Tier 3 options, applicants would need to consult wi th the EPA 4 regional office in addition to the reviewing author ity. This 5 is specified in Section 4.2.3.4(e). And again, thi s is occur 6 in agreement with the appropriate reviewing authori ty and 7 consult the EPA regional office, and you will no lo nger need 8 alternative model approval. 9 Again, though, this goes into effect with the 10 final version of AERMOD to be released next year. At present 11 ARM2, OLM, and PVMRM and PVMRM2 are still beta in version 12 15181 and they do require regional office approval at this 13 time. We released a Model Clearinghouse memo earli er in the 14 month on the use of ARM2 and refer readers to that memo to 15 get additional details on the use of ARM2 in regula tory 16 application. That should be July 8th, I believe. 17 The relevant docket items for this are specified 18 here. The docket items are both on regulations.govand they 19 can be obtained on the 11th Modeling Conference website as 20 well. And that concludes my slides for NO 2 , and it looks 21 like I've yielded myself 11 and a half minutes. 22 Okay. Now I'm going to give details on the 23 proposed replacement of CALINE3 with AERMOD in Appe ndix W. 24 I'd like to first thank my workgroup, which consist ed 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**  members of OAQPS, the Office of Transportation Air Quality, 1 Office of Research and Development, and Region 5. 2 As the title of this slide suggests, we are 3 proposing to replace CALINE3, CAL3QHC, and CAL3QHCRwith 4 AERMOD as the preferred Appendix A dispersion modelfor all 5 mobile source modeling for inert pollutants. 6 This proposal is based on three elements: first, 7 the AERMOD has updated dispersion model science rel ative to 8 CALINE3; second, the model intercomparisons of AERMOD show 9 that AERMOD outperforms CALINE3; and thirdly, that the 10 adoption of AERMOD would provide a simplified implementation 11 of mobile source modeling for Clean Air Act requirements. 12 These updates are reflected in Sections 4.2.3 and 7 .2.3 of 13 the proposed Appendix W text. 14 To support the elements of the changes in model 15 science I have some background on AERMOD and CALINE 3. 16 CALINE3 was developed in 1979. The dispersion mode l theory 17 is based on P-G stability classes, and the baselineCALINE3 18 model can actually only handle a single meteorologi cal 19 condition. 20 CAL3QHC was developed from CALINE3 for use in 21 screening for mobile sources. It adds a queuing al gorithm 22 for emissions from intersections. And finally, CAL 3QHCR was 23 developed from CAL3QHC for refined analyses. 24 CAL3QHCR adds the ability to use one year 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**  meteorological data. It adds an hourly emissions variation, 1 adds additional averaging periods for the additiona l met 2 that's processed in the model. The met preprocesso r that's 3 available for CAL3QHCR is only available for very o ld 4 meteorological data sets and has not been updated t o use any 5 of the newer one minute data. 6 The model developers replaced CALINE3 with CALINE4 7 in 1984, so according to the model developers CALINE3 was 8 outdated over 30 years ago. 9 Contrary to CALINE3, AERMOD was adopted in 2005 10 with the 2005 revisions to Appendix W. It reflects state of 11 the science dispersion model formulation, specifica lly the 12 boundary layer scaling parameter is used to charact erize 13 stability and determine dispersion rates. Monin-Ob ukhof 14 similarity profiling of winds are used near the sur face. 15 And the main point here is that in adopting AERMOD 16 in 2005 to replace ISC, one of the major technical advance17 ments was to replace the P-G stability class disper sion 18 that's used in both ISC and CALINE with these turbu lence 19 based dispersion rates consistent with PBL and M-O scaling 20 and similarity profiling. 21 EPA has conducted several model performance 22 evaluations and intercomparisons to determine the p erformance 23 of AERMOD versus CALINE3 as well as several other models. 24 These results were published in 2013 by Heist, et a l. 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**  Transportation Research D

. 1 These model findings were based on two field 2 studies that used SF 6tracers that were specifically designed 3 for evaluation of mobile source modeling. These two field 4 studies were the CALTRANS99 tracer experiment and t he Idaho 5 Falls barrier tracer experiment. 6 In the next couple of slides I give a very brief 7 summary of some of these results from these model i nter8 comparisons. The slide on your left shows model st atistics 9 for the highest 25 concentrations from the models t hat were 10 used in these model evaluations. These model runs consisted 11 of the RLINE model, which is currently being developed by the 12 Office of Research and Development; AERMOD using bo th area 13 and volume sources; CALINE3 and CALINE4; and the UK 's 14 regulatory default model, ADMS. 15 The statistics slide shows the robust highest 16 concentration versus the fractional bias. The best 17 performing or even a perfect performing model wouldbe at the 18 center of the axis that's highlighted in green. Th e model 19 statistics for CALTRANS show that AERMOD and RLINE have 20 almost identical performance, and you can see CALINE has a 21 tendency to overpredict by a factor of 2 and 3 depe nding on 22 whether you're looking at CALINE3 or CALINE4. 23 On the right-hand side I have a Q-Q plot, which 24 just makes it a little bit easier to see the model 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**  performance of these different concentration levels . You can 1 see the CALINE3 and the CALINE4 model results are e xtreme 2 outliers on this plot, the other models doing fairl y well, 3 relatively close to the 1 to 1 line. But the model 4 performance for CALINE3 and CALINE4 is not just limited to 5 the top three or four concentrations. Its overestimate 6 extends to about the top third of the distribution of data. 7 This slide shows the results from the Idaho Falls 8 tracer study. The same set of slides are presentedon this 9 as the previous slide. On the left-hand side I've got the 10 model statistics for the top 25 concentrations. Onthe 11 right-hand side I have the Q-Q plot. 12 For this particular field study all of the models 13 had a tendency to underpredict rather than to overp redict. 14 The model statistics indicate that AERMOD and this time ADMS 15 are almost identical and have the best model performance out 16 of the three models. And this time CALINE has a te ndency to 17 underpredict. 18 And you may notice on this slide that I have 19 CALINE4 and not CALINE3. For this particular fieldstudy we 20 were not able to get CALINE3 to provide reasonable results. 21 We had three or four different doctorates in engine ering look 22 at this model and try to get reasonable results andwe could 23 not get numbers that made sense to us. It may havebeen user 24 error or it may have been a limitation of the model . 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**  because of our inability to understand what was goi ng on with 1 CALINE3, we excluded those results from this partic ular field 2 study. However, we're using CALINE4 as a surrogatefor 3 CALINE3 under the assumption that CALINE4 would per form 4 better than CALINE3. 5 For this field study you can see CALINE4 is the 6 worst underpredictor. In the Q-Q plot you can see that 7 CALINE4 underpredicts across almost the entire conc entration 8 distribution range. 9 The third basis for our proposal is that the EPA 10 believes that the adoption of AERMOD will provide astream11 lined implementation for mobile sources. The Appen dix W 12 proposal will bring commonality and consistency in the model 13 analyses that are performed for EPA regulatory appl ications. 14 Specifically, AERMOD is already preferred for PM2.5 15
and PM 10conformity analyses. The adoption of AERMOD would 16 bring one model choice rather than four different model 17 choices for modeling mobile sources, so it would ma ke the 18 selection of model more simple. AERMOD has additio nal 19 options for source characterization, computation ofdesign 20 value, and is able to use more updated and refined 21 meteorological inputs. 22 Finally, I'd like to point out that FAA already 23 uses AERMOD in their EDMS and AEDT model. They moved away 24 from the CALINE3 model in 2005 when EPA promulgatedAERMOD as 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 preferred dispersion model. So the DOT has alr eady 1 adopted AERMOD over CALINE3 in the past. 2 Finally, I'd like to just point out that EPA fully 3 supports AERMOD with continued development and upda tes to 4 meet regulatory needs and issues, and that would in clude 5 updates that are needed to facilitate mobile sourcemodeling 6 in the future. 7 I'd finally like to highlight EPA's transition 8 plans under the proposed rulemaking. EPA is takingcomment 9 on the transition period from CALINE3 to AERMOD in the 10 proposed rulemaking. We are currently proposing a one year 11 transition period for the adoption of AERMOD over CALINE3. 12 That means it would be slightly less than two years from now 13 until applicants would be required to use AERMOD inplace of 14 CALINE3. Again, we're taking comment on this trans ition 15 period. 16 Additionally, I'd just like to provide a note that 17 EPA plans to provide training and already has a number of 18 training courses in place. We will provide a train ing 19 package with examples for using AERMOD over CAL3QHCfor CO 20 screening analyses. We'll provide webinars and tra inings for 21
stakeholders as needed. 22 And as I mentioned, EPA already has several 23 trainings that are available, specifically the Air Pollution 24 Training Institute course number 423, Air Pollution 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**  Dispersion Models, which outlines the use of AERMODfor 1 regulatory analyses. And the Office of Transportat ion Air 2 Quality already has training in place for project l evel hot 3 spot analyses. 4 Again, the technical details are provided in the 5 technical support document. These are available fr om 6 regulations.gov as well as the 11th Modeling Confer ence web 7 site. Thank you. 8 Mr. Bridgers: And just so I don't get one of 9 our transcriptionists in trouble, I was actually tr ying to 10 get Chris to slow down because I normally have the problem 11 with trying to get people to stop talking. I neede d to--I 12 should do my whole TV thing. It's like stretch it out 13 (indicating). 14 So we are running a bit ahead of schedule, and I 15 am going to afford a little bit longer break just b ecause of 16 that. But I wanted to make two notes. Chris in th at last 17 set of slides had said that there would be a one ye ar 18 transition period with respect to this replacement of CALINE. 19 That's broadly applicable with respect to the trans ition once 20 we get to 2016 and the promulgation of whatever form of 21 AERMOD we have after we go through the comment and 22 rulemaking. 23 I'm going to put some filler in here if the--oh, 24 it died. Well, I'm still going to put some filler in 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**  You guys can watch a real quick demonstration. In the 1 previous presentation Chris mentioned that we had j ust issued 2 a clearinghouse memorandum with respect to ARM2. And I'll 3 speak to this a little bit more in the clearinghous e 4 presentation, but in this particular case this is a n avenue 5 to which we can bring beta options to the forefrontand use 6 them currently, whether proposed or not. 7 Now, you can see how I get to SCRAM. I don't know 8 the EPA web address right off the top of my head. I should. 9 So I Google it. And it's going to get me to scram0 01, which 10 I know. But I did want to real quickly, because I won't have 11 this time after the break--so I'm on the guidance a nd 12 support. It's buried. 13 I will also mention that we are on the precipice 14 of revising the entire web structure of the EPA website, and 15 so here in probably a year's time there will not bea SCRAM 16 web site because we understand that that is not nec essarily 17 sensitive to the external community. 18 There seems to be some idea that we're telling 19 people to go away when we say SCRAM, so it--even th ough it's 20 a very technical web site, we are going to have to make it 21 such that the third grade audience can come in and feel good 22 about their experience. So there will probably be some 23 cutesy pictures and I'm sure we'll have to come up with an 24 icon for AERMOD or whatever Appendix A models 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** 

Male Voice: We can keep the name. We just 1 have to change the format. 2 Mr. Bridgers: We have to change the format; 3 right. So I'm going into MCHISRS, and I know some of you 4 loathe this, but I just wanted to point out--and I haven't 5 sent out the e-mail. It will come out in the next couple of 6 days. I just haven't had time. I'm just going in and 7 searching on Region 2 because Chris said it was a Region 2 8 memo, and I found 145 records. I'm going to go to the end 9 because it always sorts from the '80s. And see, he re it is. 10 Voices: No, we don't see it. We can't 11 see it. 12 Mr. Bridgers: You can't see it. Oh, no. 13 Okay. Well, let me start over again. See, this is a great 14 way for filling time. Now, let me see. I don't even know 15 how to get the screen back. Oh, okay. Well, we'llgo 16 through my whole process again. I get three more minutes. 17 So here's the web browser, yay. And it probably 18 has--yeah, here we go. It probably already has it in there. 19 Now I can't see it, so I'm going to have to look over here, 20 and now it doesn't work. So this also proves this is not 21 centric to Internet Explorer, but MCHISRS is under Model 22 Guidance and Support, the Clearinghouse and MCHISRS . One 23 part of the web redesign is things will probably bea lot 24 more logically laid out and easier to find. 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 I'm just going into MCHISRS, and there's a lot 1 of options here, but one of them is for EPA region or state. 2 And so I know that it's involving Region 2, so I'm going to 3 click Search. It happens to find 145 records, and as I said, 4 they start, you know, from a chronological order, a nd I'm 5 just going to go to the end. 6 And as we have indicated, it seems like there was 7 a lot of activity in the '80s and '90s and then thi ngs kind 8 of fell off, and so from the late '90s to 2015 ther e's a big 9 gap. Things were just perfect in the modeling worl d. 10 So anyway, here's the actual record in MCHISRS. 11 There's a brief summary. So that we have the date straight, 12 it's July 16th. And I will point out--I've got a l ot of ums 13 in my statements today, but I will point out the re quest came 14 in on the 18th, the reply went out on the 16th, andthis was 15 in the middle of a proposed rulemaking. 16 So I know there's a lot of built-up pent energy 17 that things take a very long time in the Clearingho use, but 18 here's one that we had a lot of other things going on and we 19 did drop some things, but we got this out in about a month's 20 time. We've got another couple that are in process and we're 21 going to be following up as soon as we get through with the 22 modeling conference here. 23 But anyway, here's the signed response back. And 24 so this can be the basis for future ARM2 usage, ass uming-- 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's that? 1 Mr. Fox: In the interim. 2 Mr. Bridgers: In the interim--assuming that 3 you meet the requirements in the memorandum that weput out 4 on ARM2 and are broadly applicable to the justifica tion that 5 was here. So there's a path forward. Now, we talked about 6 this in previous conferences that the bar is much l ower, 7 significantly lower now with ARM2 than it has been in the 8 past, because there's a road map people can follow. 9 And to Tyler's point here, it's also that we've 10 done a lot of work and there's a lot of things put forth in 11 the proposed rulemaking that can also be used as a part of 12 the justification for future ARM2 use. 13 So ADJ_U*, we've got something on the precipice. 14 We hope to be moving forward with the Clearinghouseaction. 15 We're hoping through that action lowering the bar. But 16 anybody that desires the use of the beta option in AERMET of 17 ADJ_U* right now, there's a lot of pieces of the pu zzle that 18 are on the 11th Conference or in the docket to this 19 rulemaking, and it's there. And so that's--I just want to 20 reinforce that. 21 So we have reached 10 o'clock. We're running ten 22 minutes ahead of schedule. Why don't we split the 23 difference? I know the schedule says that we go un til 10:30. 24 Why don't we split the difference and come back at 10:25? 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 gives us--or do you want to go 10:20? 1 Mr. Wayland: Go to 10:20 and give a longer 2 lunch in case--- 3 Mr. Bridgers: (interposing) Yeah, let's do-- 4 okay, yeah, let's do that. I like Chet's suggestio n. Let's 5 go to 10:20. That gives us 20 minutes for the brea k and what 6 we'll do is on the back end if we have extra time we'll just 7 take a longer lunch, and I think that's what peopleenjoy. 8 So I will suspend now for 20 minutes. Please be ba ck at 9 10:20. 10 (A recess was taken from 10:03 a.m. to 10:20 a.m.) 11 Mr. Bridgers: So we'll start the second 12 morning session now, and we'll start right off withanother 13 presentation by James Thurman with Chris Misenis somewhere in 14 the room, and this is focused on aspects of Section8 and 15 meteorological data. 16 Dr. Thurman: Okay. So I'm going to talk 17 about meteorological data for the dispersion models . These 18 are the members of the workgroup. Myself and Chris were 19 co-leads, or as I like to say, Chris is the assista nt to the 20 co-lead. He's Dwight Schrute to my Michael Scott. Members 21 from OAQPS and the regional offices, and just some 22 acknowledgements: Kali Frost of Indiana provided t he Gibson 23 AERMOD inputs and meteorological observed data for our 24 evaluations. Missouri DNR and Andy Hawkins of Regi on 7 ran 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**  Herculaneum AERMOD and MMIF, and then Andy and KirkBaker 1 from OAQPS and Roger for the Martins Creek WRF/MMIFoutput. 2 Then Rebecca Matichuk from Region 8 did the 3 meteorological analysis of the Region 8 sites. Tha t's 4 Appendix B in the TSD. And I also want to acknowle dge Bart 5 Brashers of Environ for all his work on the MMIF. He's done 6 a lot of work on MMIF and been a great help. 7 So Section 8.4 discusses the meteorological data 8 for dispersion models. There's two aspects: observed data 9 and the prognostic data. On the observed data side , the main 10 focus was on the introduction of AERMET into Append ix W. 11 As you know, we introduced AERMINUTE in 2011, and 12 it calculates hourly averages of the winds from the2 minute 13 winds for ASOS stations. And in 2013 we issued a memo 14 regarding the use of ASOS data and AERMINUTE in AERMOD, and 15 you can see the link under that sub-bullet. And ou r 16 recommendation is that it should be routinely used when 17 available. 18 There are some data gaps we found out in 2013 19 through Region 5 and AECOM, and it's a pretty subst antial 20 gap, so we're actually doing an update to AERMINUTEto bring 21 in the five minute wind data to substitute missing hours, and 22 we hope to have that out by October. 23 From the prognostic side, we're proposing that if 24 you don't have a representative NWS station, Nation al Weather 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**  Service station, and it's infeasible to collect sit e specific 1 data, you can use prognostic data. We're saying no

-- 2 recommending no--or proposing no fewer than three years of 3
data. 4 We developed the MMIF program to read the 5 prognostic data, such as WRF data, for input into AERMET and 6 AERMOD as well as other dispersion models, and MMIFis the 7 outcome of BARF, the Bret Anderson ReFormatter, so if you 8 BARF you get MMIF. 9 So we also issued guidance for the use of 10 prognostic met data. Here are some highlights of t hat 11 guidance. The number of years is a minimum of thre e years. 12 For developing the meteorological fields, i.e. run in WRF, 13 you would follow the Ozone, PM2.5 , and Regional Haze Modeling 14 Guidance that was updated in December 2014. I thin k that's 15 the Brian Timin guidance. 16 Our guidance also describes some evaluation 17 procedures, and you can see the link to that in thelast 18 bullet, and you can also see the link at the very b ottom for 19 the Ozone, PM2.5 , and Regional Haze Guidance. 20 More details on our guidance: we get guidance on 21 running MMIF for AERMOD. For regulatory applicatio ns you 22 should run MMIF to generate AERMET inputs. That's because 23 AERMET is the regulatory meteorological preprocesso r for 24 AERMOD and it also allows you to take advantage of options 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**  AERMET such as the u* adjustment and the upper air selection 1 time. If you're doing a nonregulatory application, you can 2 run MMIF to AERMET or go straight from MMIF to AERMOD to 3 generate the profile and surface file that go into AERMOD. 4 We also offer guidance on the grid resolution of 5 your WRF or prognostic run. That would depend on t he 6 location, you know, the complex terrain or complex meteoro7 logical situations. 8 Guidance on the representative grid cell, you 9 would run through MMIF for your application. For most cases, 10 this would be the grid cell that contains the facil ity of 11 interest, and if it's something like a SIP that cou ld cover 12 multiple grid cells, it would be a grid cell that's 13 representative of the whole domain. We also have o ther 14 recommendations in the guidance on postprocessing MMIF 15 outputs for AERMET and AERMOD. 16 We did some evaluations. Three case studies 17 represented here are the Gibson, Indiana SO 2study that 18 Indiana had done a paper on; also Martins Creek, 19 Pennsylvania, which is one of the AERMOD databases; and 20 Region 7 did Herculaneum, Missouri, which is a lead --the Doe 21 Run facility. 22 We did some evaluations of the met data and we 23 also did the AERMOD evaluations using the EPA proto col for 24 determining best performing model or the Cox-Tikvar t 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**  protocol, and you can see the link to our TSD at th e bottom. 1 Here's a map of the three areas. And just to note, all 2 these--none of these case studies used 15181. It wasn't 3 available at the time of the studies. 4 Here's the Gibson study area. It's southwest 5 Indiana. You see the two grid cells from WRF that contain 6 the facility, Gibson, and Evansville, the closest NWS station 7 used in the modeling. 8 This is a comparison of AERMOD output for the 9 different model runs. This is the model comparisonmeasure, 10 which compares the composite performance metric of each of 11 the model simulations. Basically here, like Roger said 12 earlier, if you overlap zero, you know, statistical ly not 13 different. 14 And as you can see highlighted in the red box, 15 Gib MMIF, which is the MMIF output for the Gibson f acility 16 versus the observed data for Gibson, we've got verygood 17 agreement, almost a zero model composite metric, sothat 18 statistically they're not different. And actually all 19 scenarios are not statistically different, so that was very 20 encouraging. I could just drop the mic and walk of fstage 21 now, but I won't. 22 The next one is Martins Creek. Here's a map of 23 the study area near the New Jersey-Pennsylvania bor der. You 24 can see ABE, the Allentown weather service station as well 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**  the west. 1 Martins Creek, not as good performance as Gibson-- 2 you know, complex terrain; we had 4 kilometer and 1 kilometer 3 grid cells to pick from as well as observe met datafrom the 4 site and the weather station that you can see. The4 5 kilometer grid cell almost was statistically not di fferent 6 from Martins Creek observed data at the 95th percen tile. If 7 we had gone to the 99th, it wouldn't have probably been 8 statistically different. 9 Also the 1 kilometers, you know, didn't perform as 10 well, but were not that bad compared to the weatherservice 11 station, which one of the goals of the evaluation was we 12 would hope MMIF was no worse than using National We ather 13 Service data. So I mean Martins Creek is not as go od as 14 Gibson but still, you know, not that bad. 15 Finally, the Herculaneum study area: we had 4 16 kilometer, 12 kilometer, and 36 kilometer MMIF outp ut as well 17 as on-site data at Herculaneum and the St. Louis ai rport off 18 to the northeast. And we couldn't do the detailed 19 statistical analysis for Herculaneum because these are lead 20 monitors, so they only had 24 hour data. 21 So we did a screening analysis in the Cox-Tikvart 22 protocol, where you take the top 25 concentrations and 23 calculate their mean bias and the standard deviatio n and plot 24 them against each other. And this small square yousee 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**  the plot is the factor of 2 box, and usually if you 're inside 1 that box you can continue with doing a detailed sta tistical 2 test on the one hour, 24 hour, and three hour avera ges, but 3 we didn't have one hour and three hour, so we stuckwith 24 4 hour. If you're outside of that box usually the pr otocol 5 recommends no more analysis because the data already has some 6 credibility issues. 7 So we're really not performing--we're outside the 8 factor of 2 box and we're underpredicting. If yourbias is 9 positive, that means that the model is underpredict ing 10 because the obs are higher. While it's outside thefactor of 11 2 box, if you notice the two--the MMIF runs, the gr een, blue 12 and purple, are fairly comparable to the Herculaneum on-site 13
data. 14 Actually the airport data is doing better, but 15 there could be some emission issues. You know, the y may not 16 be capturing all the emissions. This is, you know, a 17 smelter, so there may be some fugitives that may no t be 18 characterized well. 19 So in summary, the Gibson data was pretty good, 20 you know, statistically not different. Martins Cre ek did 21 show some difference, but not too bad. And Hercula neum 22 indicated prognostic data performance was comparabl e to site 23 specific, while not great, but still was comparable . So, you 24 know, more work needs to be done. We anticipate comments 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**  the use of prognostic data. 1 And then finally, here are the links to the draft 2 guidance on MMIF and our TSD. And that's it for th is 3 presentation. 4 Mr. Bridgers: Thank you, Dr. Thurman. I'm 5 going to give Tyler an extra few minutes because I know he'll 6 need it. While we're transitioning, I would also l ike to 7 remind everybody--I think I might need to do this a fter every 8 break; maybe I should do it before every break--is just to 9 remind everybody that EPA employees will not be abl e to 10 answer specific questions about the proposal, so ifyou ask 11 one of us other than Tyler, Chet, or myself and youget the 12 blank stare and then you can see the wheels spinnin g as to 13 what they can say, probably they shouldn't say anyt hing. 14 Mr. Fox: Or they run away. 15 Mr. Bridgers: Or they run away. So that's 16 just a friendly reminder. They're not trying to berude. 17 They're just trying to respect the rulemaking proce ss. 18 Mr. Fox: Thank you. All right. Well, 19 I'm going to address the issues related to long ran ge 20 transport assessments and what we're proposing in t he updates 21 to Appendix W. 22 Jumping right in with background, as you all are 23 aware in 2003 we revised the Guidelineto formally recommend 24 and bring in CALPUFF as the preferred model for lon g range 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**  transport, meaning source receptor distances of 50 kilometers 1 to several hundred kilometers for primary criteria 2 pollutants. 3 It was intended and in practice used to address 4 PSD increment and in particular Class I assessments , and 5 therefore quite a bit of interaction with the feder al land 6 managers, who under FLAG and in doing AQRV analysis would use 7 CALPUFF as well. So there were some joint efforts going on 8
there. 9 There's also some then issues that resulted in 10 that in terms of the FLMs having the ability under AQRV to be 11 more flexible in the specification of the CALPUFF model 12 vis-à-vis how EPA proposed it and promulgated it fo r a 13 particular use for PSD increment. 14 So right now under the current guideline, it's the 15 preferred model for long range transport. Also, as 16 referenced in Appendix A, CALPUFF can also be consi dered on a 17 case by case basis as an alternative model, again, subject to 18 approval under Section 3.2, that process that we me ntioned 19 earlier, for near-field applications where complex winds or 20 terrain warrant the use of a puff model. 21
So the Guidelineacknowledged that in Appendix A 22 that the model could be used, again, following the appro23 priate processes to get approval as an alternative model, and 24 that would have to be shown as of 2005 vis-à-vis th e 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**  preferred model in those instances, which would be AERMOD. 1 And we've got I think a number of examples. One 2 is the New Jersey 126 situation where there was a c omparison 3 made and I think is a very appropriate comparison t o look at 4 how we went about comparing those two models and th en 5 ultimately determining in that situation that therewas not a 6 sufficient difference and given the application tha t AERMOD 7 was appropriate in that use. And the agency went f orward in 8 that 126 action with AERMOD as the basis for the demon9 stration of a violation and for the consideration o f controls 10 in that case for the Portland generating station. 11 So what are we doing in the proposed revisions to 12
the Guideline ? Well, in Section 4 we are proposing to remove 13 CALPUFF as a preferred a model for long range trans port, and 14 rather we're recommending that it be used as a scre ening-- 15 excuse me, screening technique; it gets me choked up--a 16 screening technique along with other Lagrangian models for 17 addressing PSD increment in those situations beyond50 18 kilometers. 19 And so we're no longer providing it preferred 20 status. We're using it in a screening technique th at, as 21 I'll describe, we think is more appropriate given t he 22 situation for use in the context of PSD increment, and it 23 opens the field for other Lagrangian models to be u sed. 24 There are other models, SCIPUFF and other things. So again, 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 provides more flexibility for the community to u se those 1 models as appropriate. 2 As I mentioned earlier, we've also--given the work 3 that James and Chris Owen did, we conducted an anal ysis--I 4 don't have the TSD link, but there's a technical support 5 document that is referenced that demonstrates the a nalyses 6 done based on the AERMOD Implementation Workgroup s cenarios 7 that we feel and we've stated that near-field model ing is 8 sufficient to address whether a source will cause o r 9 contribute to a NAAQS violation, so EPA is not cons idering a 10 long range transport assessment beyond 50 kilometer s 11 necessary for inert pollutants. So for NAAQS you'r e dealing 12 with a near-field situation, you're applying AERMODor an 13 appropriately approved alternative model, and that' s 14 sufficient. 15 Again, under the current revisions CALPUFF or any 16 other Lagrangian model could still be available forus in the 17 near field as an alternative model subject to appro val, so 18 there's no change in the status of the model in tha t context 19 other than not specifically pointing it out. And I will 20 notice for folks, we don't point out any models in Section 5 21 or Section 6. I mean CMAQ, CAMx , other models--we're 22 purposely not trying to specify models unless they are a 23 preferred model so that there's no inference made about those 24
models. 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 recognize that there's going to be evolution. 1 There's going to be changes in those models. There 's going 2 to be changes in other models in terms of their ava ilability. 3 And so we've reserved that for guidance and the like, but 4 Appendix W itself does not infer any preference at all in 5 terms of acknowledging those types of models. 6 And so what do you mean, Tyler, by screening 7 approach for PSD increment? Well, Section 4 lays t hat out 8 explicitly. We, again, recognize that long range t ransport 9 assessments may be necessary in limited situations. We've 10 engaged with the regional offices--Region 4, Stan K rivo; 11 Region 6, Eric Snyder among others--to understand what their 12 experiences have been over the past ten plus years. 13 And again, as I said earlier, going down the road 14 to doing a Class I PSD increment analysis, my under standing 15 is that you can count them on one hand, so we're ta lking 16 about a very limited situation. And so having a sc reening 17 approach was deemed both appropriate and necessary in these 18 revisions. 19 So the first step would be for your near-field 20 application of the appropriate model--as I said, AE RMOD or an 21 alternative model, based on approval--you would det ermine the 22 level of significance of those ambient impacts fromyour new 23 or modifying source at or around 50 kilometers. Yo u'd have a 24 circle of receptors that would tell you that. Agai n, 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**  experience will tell you that the vast majority of situations 1 will screen out at that point in time. 2 If you don't screen out in that instance, then the 3 second step would be in consultation with the regio nal office 4 you determine the appropriate screening approach us ing 5 CALPUFF or any other Lagrangian puff model to determine the 6 significance at specific Class I areas of concern. 7 You're dealing with a specific new or modifying 8 source. You know those Class I areas that are with in a 9 reasonable transport distance, and you can look to those 10 specific receptors to determine what the significan ce levels 11 are in those cases. Again, the vast majority of si tuations 12 are expected to screen out--if they even get to tha t second 13 step, to screen out at that time. 14 If they don't screen out, then for those limited 15 situations you would have to conduct a cumulative impact 16 analysis, and I think memory didn't serve any of us well in 17 terms of being able to point to a situation where t hat 18 actually had occurred, so if there's public commentto 19 address and remind us of that, that would be apprec iated. 20 And then the selection and use of a model would be determined 21 through approval under Section 3.2.2(e), alternative model. 22 So that lays out the screening approach--again, 23 streamlining the approach in terms of what models you have to 24 use, having them, you know, and the approach be war ranted 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**  the nature of the problem. And so we feel as if itwas 1 appropriate to offer this flexibility and to reducethe 2 burden on the user community. 3 Then in Section 5 in terms of addressing secondary 4 pollutant impacts we feel that by not specifying a preferred 5 model we actually provide a lot of flexibility to t he user 6 community in estimating these single source seconda ry 7 pollutant impacts with more appropriate modeling te chniques. 8 We stress the full chemistry photochemical models i n the 9 preamble, and a number of those do address science issues of 10 Lagrangian models and in particular CALPUFF, and I' ll note 11 some of those in the next slide. 12 And based on the IWAQM, Interagency Workgroup of 13 Air Quality Modeling, the Phase 3 effort, there arereports 14 as well as published literature that support our de cisions. 15 And we've placed the emphasis on use of those chemi cal 16 transport models or techniques that reflect the sta te of the 17 science in atmospheric chemistry so that we're appl ying the 18 best science in those situations. 19 And again, we've got guidance. Kirk Baker and Jim 20 Kelly put together a detailed guidance to support S ection 5 21 for ozone and secondary PM2.5 , and we will reply upon the 22 regional offices and others and the community at la rge as 23 these models are there and developed and techniques within 24 those models are improved upon to allow them for us e 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**  tools like source apportionment, other instrumented 1 techniques, and Kirk will get into that in more det ail 2 shortly. 3 Then the preamble discusses in the section for 4 long range transport future considerations for visi bility 5 modeling with full chemistry photochemical models. We're 6 limited in our ability to do evaluations with respe ct to 7 visibility, and so we'll be working very closely, h ave been 8 working very closely through the three phases of IWAQM with 9 our federal partners. 10 And we feel as if--and as described in the 11 preamble that consistent with what we're doing for ozone and 12 secondary PM2.5under PSD that as these techniques are used 13 and improved that their application for AQRV analys is for 14 visibility and perhaps even in the regional haze co ntext 15 would not only provide improved science, but harmon y and 16 consistency with the models used in other aspects o f the 17 Clean Air Act programs. 18 And so it reduces the number of models you're 19 carrying around. It reduces decisions and flexibil ities of 20 determination of what knowledge to work with those models and 21 starts focusing us on best science and allows the c ommunity 22 to then focus on developments and research and the like 23
there. 24 And I think that's evidenced through work that 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**  EPRI has done with SCICHEM from SCIPUFF and the bayreleases 1 that they've done and we'll hear later in the publi c comment 2 about. And so I think there's the community there to develop 3 and improve these models, and we've provided the--I think the 4 impetus to continue that development and leverage t he 5 development that's gone on to establish what we've done in 6 Section 5. 7 So I mentioned the limitations, and so this was 8 documented in EPA's 2009 reassessment, and there wa s a 9 modification through a memo to the docket to add co nclusory 10 or summary statements, and this is part of that. 11 The chemical conversion algorithms in the 12 regulatory versions are quite old, and they're pret ty 13 inconsistent with our current knowledge and state o f the 14 science in terms of secondary PM2.5formation. 15 And even the more recent chemistry algorithms 16 still don't contain photochemical reactions that ar e 17 important to simulate secondary PM formation. They 're not 18 the type of full chemistry model that we feel is ne cessary 19 and appropriate. 20 And it does not estimate ozone formation from 21 single sources, which is something that now under S ection 5 22 and Appendix W and through guidance we are looking for and 23 expecting. 24 So--and then in a wide variety of situations where 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've tested and evaluated the model, there's just a lot of 1 variation in terms of an unexplained and very diffi cult to 2 comprehend and understand sensitivity of the disper sion model 3 with the CALMET meteorological input that necessita ted 4 putting a preset to CALMET by EPA in conjunction wi th the 5 FLMs to try and make it a more manageable process a nd 6 understand and provide more credibility in the mode ling 7
results. 8 And so it's just been a challenge for us dealing 9 with this model over the past ten years, and unfort unately 10 the community has not come together as was expectedto really 11 work on those types of developments, broadly speaki ng. 12 And to that point we also issued a memo related to 13 concerns about the management and maintenance of th e model. 14 The interactions between EPA and the model develope r have 15 been complicated by the changes in ownership and th e 16 uncertainty of the development process. That's jus t a fact. 17 We're not trying to say anything that is anything o ther than 18 just a fact of our experience and our observations. 19 And as EPA and as being responsible for a 20 preferred model in Appendix W, it becomes an obliga tion on 21 the federal government, and we have memos and otherthings 22 that are in the docket establishing that relationsh ip, and it 23 has just been difficult to adhere to those in a ver y 24 transparent and open manner. One example is the pr ocess that 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 went through in updating the VISTAS version of CALPUFF, 1 and that was discussed and summarized in detail at the 9th 2 Modeling Conference. 3 There have been a number of updates to the CALPUFF 4 modeling system just as there have been a number ofupdates 5 to AERMOD in terms of the regulatory version. It's just that 6 process has been a little hit or miss in terms of u nder7 standing and knowing what's coming and communicatio n to both 8 EPA and the broader community in terms of those thi ngs. 9 And there's been the parallel development process 10 with the series 6 versions, which has just caused alag in 11 our ability to adequately understand, to review, an d 12 ultimately approve changes in a timely fashion. An d it's 13 largely due to a lack of an open development proces s. 14 And then we recently in the latter part of June 15 were hit with from the current owner of CALPUFF a version 7 16 version of the model with no prior notice in the mi ddle of 17 this rulemaking, and again, it makes it very diffic ult, very 18 awkward for the agency to proceed with what it need s to with 19 that type of process. So we do believe that it's b een unduly 20 complicated by these changes, and it's already a complex 21 model, a complex world to apply it in. 22 And so it--when we're talking about a preferred 23 model that has status and that the EPA has ownershi p 24 obligations if deemed necessary, one option is to t ake 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**  model under our own roof. We've got difficulty eno ugh 1 maintaining AERMOD and other models and adequately staffing 2 and supporting the regions in the permit arena, so that would 3 be a totally unfeasible option for us to do. 4 And again, as I said, there are other models out 5 there. We've got a screening approach that adequat ely meets 6 the regulatory needs, and so from the standpoint ofmoving 7 forward we feel as if the changes that we're propos ing are 8 not just warranted but in everybody's best interest

. 9 And in terms of the Regional Haze Program, we did 10 issue a 2005 guideline separately for the BART requ irements 11 under Regional Haze Rule, and that did recommend atthe time 12 because there really was no other model capable--atthat 13 point in time photochemical models had not been rea lly--they 14 had been some--some had been instrumented with thes e types of 15 instrumented techniques, but they really hadn't bee n fully 16 evaluated and understood and put into practice. 17 So CALPUFF was available for single source assess18 ments. Again, in that process we acknowledge the l ack of 19 full evaluation, but it did provide information in a 20 multifactor decision making process under BART. Ag ain, it 21 wasn't the sole determination of things as it wouldbe under 22 a preferred model situation in terms of whether or not you 23 are complying. It was a factor in a multifactor de cision 24 framework, and so we felt comfortable in that conte xt. 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 in that we also did allow states the ability 1 to use alternative models, and some did use photoch emical 2 models and have used photochemical models. The EPAitself 3 has used photochemical models in this context in co nsultation 4 with the EPA regional offices. So I think as the s cience has 5 evolved the process is flexible and fluid enough tobring 6 those in so that the best science is used in this c ontext. 7 That said, the proposed changes do not affect the 8 recommendation from 2005 and past and current BART 9 applications of that model, and so adhering to Appe ndix W and 10 going through the appropriate process as folks haveis still 11 in place, and we do not--we want to make sure that everybody 12 knows that we do not feel that any of the changes t hat we're 13 proposing which need to move us forward should be r etro14 actively looked at in terms of these things. 15 We don't do that in any situation, you know. We 16 don't go back and reevaluate permits, you know, tha t were 17 done with older versions of the model. There's a r eason. 18 You have to respect that, but yet you have to also respect 19 the evolution of the science and the better sciencebecause 20 that will always change and evolve. 21 So in summary, just to close, so we're proposing 22 to remove CALPUFF as a preferred model in Appendix A 23 specifically for long range transport, and we're re commending 24 that it be used instead as a screening technique al ong 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**  other Lagrangian models for assessing PSD incrementbeyond 50 1 kilometers. 2 For NAAQS demonstrations based on the analyses 3 that we've done, and we welcome comment and new oth er source 4 sector scenarios that can be fully evaluated to support our 5 determination or question it, however the case may be, that 6 you would not conduct a NAAQS analysis outside of 5 0 7 kilometers for inert pollutants. 8 There's no change in the ability to use CALPUFF, 9 again, or any other Lagrangian model, or other Gaus sian model 10 for that case, in the near field as an alternative model for 11 low wind, low terrain, and other specific situation s in which 12 AERMOD, the preferred model, isn't working or beta options 13 available in AERMOD are not working. You have thatalterna14 tive model approach available, and that flexibilityhas 15 always been there and we continue that. 16 And along the line of flexibility, the user 17 community has that in estimating single source seco ndary 18 impacts, and we will continue to evolve. We've in Appendix W 19 provided a broad framework, an appropriate framewor k, that we 20 feel meets the requirements under the Sierra Club p etition in 21 terms of establishing models and/or techniques withreason22 able particularity. 23 We've done that in Appendix W with subsequent 24 guidance that supports that and that that allows fo r 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**  appropriate use of chemical transport models, and i n some 1 cases Lagrangian puff models may be appropriate to use in 2 that context, and we provide the appropriate contex t for 3
those used. 4 So again, we're opening the field up. We're 5 allowing flexibility in the user community to appropriately 6 address the problems that they have, and we, again, have a 7 framework and a process by which it can happen and it can be 8 effectively communicated in a transparent way. 9 And as we update the Guideline , you know, we 10 hopefully don't have another decade go by, and I do ubt we 11 will be able to let another decade go by, given theadvances 12 and the need to continue to refine the Guideline , to continue 13 to refine the models. We'll certainly be continuin g to 14 evolve what's in Appendix W, what's in the guidance , and our 15 preferred models to respect that. So I think that is it. 16 Thank you. 17 Mr. Bridgers: Thank you, Tyler. So we're 18 getting back on schedule, if there's a schedule we must keep. 19 We'll transition from the discussion that Tyler jus t gave on 20 long range transport and CALPUFF to a presentation from Kirk 21 Baker, et al. about the treatment of PM2.5and ozone in PSD 22 compliance demonstrations. 23 Dr. Baker: All right. Thanks, George. 24 The first thing I want to do is apologize to the re st of my 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**  group for not wearing a tie, so I guess we'll keep this a 1 little more informal in this talk. 2 So secondary pollutants for single source impacts, 3 I'm going to talk a little bit about that today. A s Tyler 4 mentioned, EPA granted a Sierra Club petition in Ja nuary 2012 5 with a commitment to update the Guideline on Air Quality 6
Modelsto address ozone and secondary PM2.5impacts. The 7 current version of the Guideline on Air Quality Modelshas 8 very little information about how one would go abou t 9 estimating the impacts from single sources for ozon e and 10 secondary PM2.5 . 11 So in response to that petition we now have an 12 entire new chapter in the Guideline , Chapter 5, that's 13 focused totally on secondarily formed pollutants sp eaking to 14
ozone and PM2.5 , and we have a Chapter 6 that's focused on 15 visibility, deposition, and air quality related val ues. 16 It's similar to the older Chapter 6. It retains 17 some of those elements, but if people remember the old 18 Chapter 6 it was kind of a hodgepodge of a lot of i ncongruous 19 information, so now it's just totally focused on ai r quality 20 related values and other governmental programs. 21 The intent that we had in going through and making 22 these updates to Appendix W is that the updates we would make 23 would be an appropriate level of detail that is goi ng to be 24 relevant over the long term and put the more dynami c 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**  information that would be reflecting the current pr actice of 1 model application into guidance documents, which ar e going to 2 be more dynamic and could be more fluid and updatedto 3 reflect the state of the practice going forward so we don't 4 always need to go back to rulemaking to update the Guideline 5 when new things come about. 6 So the process for updating Appendix W for the 7 secondary pollutants, the Interagency Workgroup on Air 8 Quality Modeling, IWAQM, has been a process that ha s 9 historically been used for collaboratively updatingregula10 tory air quality modeling approaches. 11 So we reinitiated the IWAQM process and called it 12 Phase 3 in July of 2013 so we had a mechanism for working 13 collaboratively with our EPA regional office partne rs and 14 partners at the other federal agencies to update th e Appendix 15 W, update or develop new guidance documents where n ecessary. 16 So the goal with this process was to just start to 17 understand and identify credible modeling technique s for 18 single source secondary impacts for ozone and PM2.5 . This 19 type of work had been done in the past but not an e normous 20 amount of work, so in a lot of ways we were startin g with 21 kind of a clean slate, especially on the ozone side , and just 22 trying to understand what types of tools are approp riate for 23 this, and if someone were going to use these types of tools, 24 how best should they be applying them for this typeof 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**  purpose. A lot of these tools have been used for o ther 1 purposes and we just wanted to make sure that when used for a 2 permit type application that they would be used in the most 3 appropriate way possible. 4 So in Phase 3 IWAQM consisted of two different 5 working groups. There was a near-field impacts wor king group 6 that was largely EPA regional office and OAQPS staf f, and 7 there was also a long range transport workgroup, wh ich is 8 more similar to the past IWAQM phases that people might be 9 more familiar with. So out of that we have technic al reports 10 and guidance documents to support the proposed revi sions to 11 the air quality modeling guideline. 12 So this looked pretty good on my computer. It 13 probably doesn't look too good here from where I'm standing, 14 but this is kind of a schematic of the different pi eces of 15 the puzzle that we were updating through that IWAQMprocess. 16 And up on the top we've got Appendix Q updated Chap ters 5 and 17 6 and the preamble language that was relevant to th ose two 18 chapters, so that was the main, overarching goal wa s to 19 update Appendix W for single source secondary impac ts. 20 And below that we've got kind of increasingly 21 dynamic documents. We've got the high level guidan ce 22 documents and moving down into technical reports th at kind of 23 provide a snapshot of what the world is right now i n terms of 24 the technical approaches that are available for us in 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**  single source impacts in the near field and long ra nge 1 transport. 2 So on the left side we've got the PM Modeling 3 Guidance that had already been put together. We di dn't work 4 on that, but we did develop a new guidance documentfor using 5 models for single source secondary impacts for ozon e and 6
PM2.5 . 7 And so the idea behind this is if people are 8 familiar with guidance that we have put out for thi ngs like 9 nonattainment demonstrations, the intent here was t o provide 10 something similar so that people would know if you' re going 11 to use a chemical transport model for the purposes of 12 estimating single source impacts, how would you setit up and 13 apply it for doing a PSD permit type of application . So we 14 wanted to have all that information in one place. That's the 15 intent of that. 16 And then below that we've got--the IWAQM Phase 3 17 near-field group had a technical report that just k ind of 18 details where we see the science and the feel of th at right 19 now with respect to doing these types of assessment s. 20 On the right-hand side the long range transport, 21 the main guidance document being the Federal Land Managers' 22 Air Quality Related Values Work Group Phase I repor t, the 23 FLAG guidance document. A lot of people are probab ly 24 familiar with that, and so that's going to be--thatwas not 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**  updated as part of this process. We expect the federal land 1 managers to take up a process moving forward to update that 2 if they feel it's appropriate. 3 And below that there is also a Phase 3 report from 4 the Long Range Transport Group that again kind of p rovides a 5 synopsis of the state of the practice and science r elated to 6 long range transport modeling for air quality relat ed values. 7 Then at the very bottom, which probably most 8 people in the room can't see, is just--there's a lo t of 9 technical reports from EPA, a lot of external repor ts that 10 some people in this room have put together and thin gs in the 11 literature that we used to inform these reports andthe 12 guidance. 13 So this is just an outline of what's actually in 14 Appendix W Chapter 5. This is the section on Model s for 15 Ozone and Secondarily Formed Particulate Matter. T here's a 16 discussion of what ground level ozone and secondaryPM2.5 17 generally is. There are also some broad recommenda tions 18 about what types of modeling systems would be appropriate for 19 either doing a single source permit type of assessment or for 20 doing a nonattainment demonstration, which would bea multi21 source projected type of modeling assessment for se condary 22 pollutants. 23 So what we've tried to do in Chapter 5 is really 24 clearly delineate using air quality models for nona ttainment 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**  demonstrations for NAAQS, which would be kind of mu ltisource 1 or all source projected future year assessment of acontrol 2 strategy and also have--clearly differentiate the approaches 3 necessary for doing a secondary impact assessment f or a 4 permit. So we've got both of those things in thereso it's 5 very clear for ozone and similar information for se condary 6
PM2.5 . 7 So the highlights for Chapter 5--this is a totally 8 new chapter in Appendix W. As I mentioned, we want ed to have 9 a very clear distinction between nonattainment plan ning for 10 NAAQS and permit assessments. We want to emphasizethe 11 importance of developing modeling protocols and con sultation 12 with the reviewing authority. 13 As Tyler mentioned, what we're doing is we're 14 putting forth a screening approach without a prefer red model. 15 We don't even really mention a lot of model names b ecause, 16 given the length of time it usually takes to updatethese, a 17 lot of times when you go back and read Appendix W i t's like 18 pulling out a time capsule and you see references t o models 19 that you forgot ever existed or, you know, you don' t even 20 know what the reference is supposed to be because n obody has 21 any idea what that model was back at that time. Sowhat 22 we're trying to is just kind of focus on high levelinforma23 tion and not get into a lot of specific details wit h model 24 names and things like that. 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 other thing that Chapter 5 puts forth is a 1 multitiered approach for single source permit asses sments. 2 We don't expect every single permit assessment to h ave to do 3 a rigorous, full scale photochemical transport mode l type of 4 assessment. There's going to be a multitiered appr oach, one 5 that's going to be using existing information whereit's 6 appropriate and available and seeing if that's goin g to 7 provide the information that will work for the asse ssment in 8 consultation with the reviewing authority. 9 And then beyond that if necessary we expect there 10 will be less situations where people would need to use a 11 photochemical or a Lagrangian chemical transport mo del. But 12 in situations where we do get into that, we do emph asize that 13 it's really important to use techniques that reflec t the 14 state of the science (coughing). Like Tyler, this is also 15 very emotional for me. It's been a long three year s since 16 the petition was agreed to. 17 Mr. Fox: We're almost there, Kirk. 18 Dr. Baker: I had no idea how this was 19 going to change my life. So some of the broader co nsidera20 tions for ozone and secondary PM2.5permit modeling, we put 21 forth this idea of MERP, the Model of Emission Ratefor 22 Precursors. And information about this has been in cluded in 23 the docket. So we're expecting to have this as par t of 24 future rulemaking and possibly guidance. 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 a MERP is not going to replace the significant 1 emission rate for permit assessments for determinin g the 2 applicability of the PSD requirements for sources w ith 3 emissions above the SER. However, a MERP would rep resent a 4 level of emissions of precursors that is not expect ed to 5 contribute significantly to concentrations of secon darily 6
formed PM2.5or ozone. 7 So if a source has emissions above the SER but 8 below the MERP, we may not expect that additional t echnical 9 demonstrations would be necessary at that point, bu t still 10 that would need to be totally determined on a case by case 11 basis with the reviewing authority. 12 So the idea for the MERP is just kind of an 13 initial screening to screen out people that we don' t--that we 14 think are small and the emissions are not going to result in 15 an impact that would be at the level of the SIL in any place, 16 so we want to--the idea is to have a conservative e stimate. 17 You know, we think no matter where the source is, t hose 18 emissions of NO xor SO 2would not result in secondary PM2.5 19 above the SIL anywhere, and similarly for MERPs forVOC and 20
NO xfor ozone. 21 So as I mentioned, I think there's a separate 22 document that's been submitted to the docket where it 23 outlines how MERPs fit into the permitting process, so in the 24 past in the PM2.5modeling guidance, people probably remember 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 flow charts where if your emissions are above t he SER and 1 depending on whether you're in an attainment area o r a non2 attainment area you kind of go through different pr ocesses to 3 determine what types of quantitative assessments ma y or may 4 not be necessary for you and what types of controls may or 5 may not be necessary. So there's a document that updates 6 that and includes how the MERPs fit into that proce ss. 7 So with the guidance on the use of models for 8 assessing the impacts of emissions from single sour ces on the 9 secondarily formed pollutants ozone and PM2.5 , we've provided 10 guidance so people know what to do for permit asses sments. 11 And I want, you know, to just reemphasize that we 12 expect that a lot of sources will be screened out t hrough the 13 MERPs once those are available. And if they are ab ove the 14 MERP, then a first and possibly second tier assessment may be 15 necessary. And those two tiers are broadly outline d in 16 Appendix W, and we have more information about thos e tiers in 17 this guidance document. 18 So for first tier assessments, it's generally 19 expected that applicants would use existing empiric al 20 relationships between precursors and secondary poll utants 21 based on credible and relevant modeling that already exists 22 and detailed in this guidance. 23 It's also possible that some screening approaches 24 could be developed based on full science photochemi cal 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**  transport modeling systems such as reduced form models, and 1 this could provide information that might satisfy t he first 2 tier requirement in some situations. 3 So the use of preexisting credible technical 4 information or a screening model for the purposes o f 5 estimating single source secondary impacts would be 6 considered on a case by case basis and done in cons ultation 7 with the appropriate review authority. So again, we're 8 trying to provide a lot of opportunity for people t o do a 9 credible assessment of their emissions against a SI L but not 10 necessarily have to go right into doing a full scal e, 11 rigorous chemical transport analysis. 12 So a second tier assessment could be necessary, 13 and when that would be necessary we have guidance o n how you 14 set up the air quality models, inputs, what kind ofrun time 15 options might be necessary, how you would set up th e 16 receptors, and how you would do the postprocessing in order 17 to appropriately assess the impacts of a project so urce on 18 ozone and secondary PM2.5 . 19 And even within the second tier in Appendix W when 20 you get into that situation, we kind of had a subti er set up 21 where there's different levels of rigor, so you cou ld do 22 something a little bit less rigorous and take a mor e 23 conservative impact being estimated for the projectsource or 24 you could do something more refined and complicated , 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**  there might be some leeway to move off of the most 1 conservative possible estimate. Those are the thin gs that 2 would be laid out in a modeling protocol and agreedupon with 3 the reviewing authority. But we just want to empha size that 4 we're trying to build a lot of flexibility into thi s for 5 people. 6 So for second tier assessments we do generally 7 recommend that chemical transport models be used fo r single 8 source ozone and secondary PM2.5impacts. Chemical transport 9 models broadly include Lagrangian puff models and E ulerian 10 grid models such as photochemical transport models. 11 One challenge with Lagrangian puff models is they 12 need a realistic chemical environment, so you need an input, 13 a three dimensionally varying set of oxidants and mutualizing 14 agents, so you need to get that information from somewhere 15 else, and it could be--you could get that from a ph oto16 chemical transport model because photochemical tran sport 17 models do estimate a generally realistic or usuallyrealistic 18 chemical environment, and that output could be usedas input 19 to a Lagrangian model if people are interested. 20 And there certainly could be some situations where 21 the three dimensional environment around a project source and 22 key receptors isn't that complicated. You might no t need to 23 go to that type of rigor, but that is something tha t would 24 be, again, decided on a case by case basis. 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** 

When using photochemical transport models, we've 1 got a lot of information in the guidance about how they would 2 be used for this purpose. Even though single sourc e 3 emissions are injected into a grid volume, we have done 4 comparisons with in-plume measurements, and this su ggests 5 that grid based models can provide appropriate downwind 6 secondary impacts when they're set up and applied appro7 priately for that particular purpose. So we do have 8 confidence that these models do work for single sou rce permit 9 types of assessments. 10 But having said that, clearly given that, you 11 know, there's not an enormous amount of informationavailable 12 up to this point, further testing is needed for dif ferent 13 types of modeling systems, both Lagrangian and Eule rian, to 14 better understand what configurations are going to be the 15 most appropriate for permit types of assessments an d build 16 upon a broader base of knowledge so that we can understand in 17 different parts of the country and even in differen t parts 18 maybe of particular urban areas how much secondary PM or how 19 much ozone would we expect to see from different le vels of 20 precursor emissions. 21 So I think that's going to be important going 22 forward is just building upon that body of knowledg e and 23 seeing how variable that's going to be from place t o place 24 and even within a particular place. 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 the IWAQM3 Near-field Impacts Group updated the 1 preamble and Chapter 5, which I mentioned this new guidance 2 document, which is available in the docket, which I just 3 talked about. And there's also a summary report th at talks 4 about what we know right now about the relationshipbetween 5 single source precursors and downwind secondary imp acts. 6 There's an overview of published emissions and 7 secondary impacts from single sources to provide some context 8 for what we expect in terms of impacts from these t ypes of 9 sources, and it also talks a little bit about recommended 10 models, approaches, and tools for these types of as sessments 11 that are available now. 12 So estimating source contributions with chemical 13 transport models, Lagrangian puff models are prettystraight14 forward. They usually just output the project sour ce 15 impacts. When you use something like a photochemic al grid 16 model that contains all the sources, it's really no t that 17 complicated, but you just want to keep in mind thatit could 18 involve two different simulations, that the simples t way to 19 get the single source impacts from photochemical gr id model 20 simulation would be to do a model simulation with a ll the 21 sources and the project source at preconstruction l evels and 22 do a second simulation with all the same sources no t changed 23 and the project source at postconstruction levels. 24 And what you would do is just difference those two 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**  things and find out what the impacts on ozone or se condary 1
PM2.5is from your project source. And that's what's 2 represented in the schematic that most people unfor tunately 3 from about the fourth or fifth row back probably ca n't see, 4 but we've got the baseline on the left with the sou rce 5 modification compared to the baseline in the middle

. 6 And on the right you can clearly see with the 7 spatial plot the warmer colors being the higher imp acts 8 nearest the source itself, and they kind of fall of f as you 9 get further away from the source. And it varies di rection10 ally based on the meteorology. So it's kind of a p hysically 11 realistic impact that we're seeing when we use thes e types of 12
models. 13 And alternatively, there's more complicated things 14 you can do with a photochemical transport model if you use 15 extensions like source apportionment or DDM. You c ould track 16 the model--you could track the contribution of a pa rticular 17 source through the model without a second model simulation, 18 although that does require some additional resource s. 19 Real briefly on Chapter 6, this is the section-- 20 now it's just focused on air quality related values and other 21 governmental programs, so Chapter 6 just kind of ta lks about 22 what are air quality related values, how do the FLM s fit into 23 this picture, and what is the appropriate guidance, and here 24 it would be the FLAG guidance. 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 in the past, as I mentioned before, Chapter 6 1 comprised a lot of really incongruous information. It had 2 GEP information in there along with long range tran sport 3 modeling, so it is really focused on visibility and 4 deposition and other programs. 5 I'll emphasize again as Tyler mentioned using 6 chemical transport models for these types of purpos es, and we 7 expect the specific guidance that people refer to would be 8 looking at the FLAG guidance document. Specific gu idance for 9 models and model applications are also available fr om the FAA 10 for airports and from BOEM for offshore sources tha t are 11 within their jurisdiction. 12 If it's an offshore source that's within EPA's 13 jurisdiction, then you would refer to other parts o f the 14 Guideline on Air Quality Models , Appendix W, for information 15 about doing those types of assessments. And Tyler also 16 mentioned that the screening approach for primary p ollu17 tants, that's in a different section of the Guideline on Air 18 Quality Models

. 19 So finally, the IWAQM3 and Long Range Transport 20 Group worked on updating the preamble and Chapter 6 , and 21 there's also in the docket a report from that groupthat 22 talks about recommended models, approaches for longrange 23 transport assessments of secondary pollutants inclu ding 24 visibility and deposition. 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. Bridgers: Thank you, Kirk. And it looks 1 like there's an assurance if I can keep my comments to time 2 that everyone will have a longer lunch break. I'm the emcee 3 and the conference host, so I have some prerogativethat I'm 4 going to take. I have two talks scheduled now on your 5 agenda. If you see them, I'm going to reverse them , and I'll 6 explain why. 7 I don't know if it was late one night, I don't 8 know if it was early one morning when I put this ag enda 9 together and I just randomly put my presentations o n there, 10 and then I realized last night about 9 o'clock--I'mlike, 11 "Er, I really should talk in the other order." 12 A subtle feature that we didn't announce: the 13 agenda today across the morning largely follows thepreamble 14 and the proposed actions that we have. And so to t alk about 15 the Clearinghouse needs to happen before we talk ab out the 16 final Chapter 8 and Chapter 9, so I'm going to takethe next 17 ten minutes--and good Lord, I need this--to talk ab out the 18 Clearinghouse and then we'll switch to a conversati on about 19 single source and cumulative analyses. 20 So again, just for the record, George Bridgers 21 with the Air Quality Modeling Group here. As I sta rted off 22 here and want to start off now, I want to kind of f rame 23 things with what is already in regulation and kind of frame 24 some history of the Clearinghouse and then talk abo ut what 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're trying or proposing to do in the revisions tothe 1 Guideline

. 2 So to start off with, in 40 CFR Part 51, 51.166--I 3 sound like I'm up in the policy group right now--(l )(2) 4 specifically, the authority for the specification o f a model 5 in Appendix W, which essentially happens in Appendi x A to 6 Appendix W, it's all granted through writing from t he 7 Administrator. 8 Now, I can assure you Lisa Jackson--oh, excuse me, 9 whoa. Our fair and very esteemed Administrator McC arthy--I'm 10 sorry to her--that will certainly come up in my per formance 11 review. See, you get in front of all these people and you 12 mind just goes blah. 13 So at any rate, yes, she was with the president 14 last week with a very big announcement, and I'm surprised the 15 president's not here with our announcement, but non etheless, 16 so yes; I do not think that Administrator McCarthy would be 17 personally writing the approvals for the various mo dels. 18 We do that through rulemaking for the Appendix A 19 models, the ones that are preferred status. And th en for the 20 alternative models it happens through a delegated a uthority 21 with the regions. And I wanted to point out first every22 thing--the buck stops with D.C. and the Administrat or. 23 The actual delegation of authority within the 24 hierarchy happens in Appendix W, and it has since t he '90s. 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 that happens actually in Section 3. I think it' s always 1 been in Section 3, and so what we're trying to do r ight now 2 is to bring further clarity to the delegation and r espect 3 what we have next and something that's been--and I have 4 slides in a minute--that's been throughout the proc ess, and 5 that's that the regional offices already have a res ponsi6 bility through regulation that they have to coordin ate with 7 headquarters on anything that could be inappropriat ely or 8 unfairly or, you know, capricious and arbitrarily applied 9 across the regions. 10 And so we're the headquarters, and so the buck 11 stops at least with the approval of alternative andpreferred 12 models with us in the Air Quality Modeling Group an d then 13 with the Clearinghouse the way it's been set up. 14 So just for the record, it's on the screen as Part 15 56 and 56.5 is where this responsibility of the reg ional 16 offices to seek concurrence of the headquarters. I f anybody 17 is red-green color blind, it's just blank, but I as sure you 18 it's on the screen. 19 So we have stressed the importance and the 20 consistency of--or trying to have or gain consisten cy for 21 years in multiple revisions of the Guidelinein the very 22 first sentence, and that's the "Industry and contro l 23 agencies"--and this has come through previous publi c comment, 24 and I think everybody in this room--well, I'm not g oing 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**  speak for everybody in this room, but I would hope everybody 1 in this room would want consistency in the applicat ion of air 2 quality models in the regulatory context. Otherwis e, we're 3 not doing our job right. 4 So just to point out a few things, this one is 5 actually in the docket. We included this on the 11 th 6 Modeling web site because we discovered it was not anywhere 7 to be found. And unfortunately, Annamaria could no t be with 8 us today, but Annamaria, our Region 2 modeling cont act, was 9 able to dig up in her treasure trove of archives th e old 1988 10 Model Clearinghouse Operational Plan. 11 And surprisingly, being the Model Clearinghouse 12 Director for going on five years now, I hadn't readthat. 13 Maybe I should have--another performance review thi ng, but 14 Tyler couldn't provide it to me anyway. Nonetheles s, it was 15 an interesting read because everything--and we got this prior 16 to the proposal--because everything that we're tryi ng to 17 codify in this proposed action was clearly stated a nd 18 provided to the regions in 1988. 19 1993 was the first time that the Clearinghouse 20 actually showed up that I could find in the Guideline . It 21 was in Section 3. And it was interesting that the first 22 thing that I found there was that the primary funct ion was to 23 review decisions proposed by the regional offices o n modeling 24 techniques and databases. 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 other two--one was performing audits and then 1 annual reports. We'll get back to the annual repor ts at some 2 point, but I'm not suggesting--we're not suggestingwe're 3 going back to the old days of auditing the regionaloffices, 4 but that used to happen. But nonetheless, historic ally the 5 Clearinghouse has been at the center of modeling demon6 stration approvals in the alternative context and t he 7 preferred context. 8 So subsequent revisions of the Guidelineseemed 9 to--and this just happens with time. Some of the c ontext was 10 lost through what we sometimes call streamlining, b ut what 11 we're trying to do today is to codify something tha t has been 12 in practice for like 25 years. 13 So that's what we have right now is that the 14 responsibilities and the preferred status approvals all 15 happen in Section 3.1, and in 3.2, this is where th e 16 Clearinghouse comes in with the approval or concurr ence with 17 the regional office on all of the approvals of alte rnative 18 modeling demonstrations. 19 So in the proposed revision, as I said, we have 20 references to the 1988 Clearinghouse Plan. We list ed in the 21 new proposal the 51.166(l)(2) regulatory text refer ence, and 22 that is to bring clarity on that delegation authori ty with an 23 understanding of what we talked about with the 56.5 (b). 24 We're trying to provide as much transparency-- 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**  again, this is a process that's been in place for 2 5 years. 1 There was a clearinghouse document, the operationalplan that 2 I couldn't even find. It was referenced in the 200 5 version 3 of Appendix W that's current, but it's one of those 4 unclickable links you can't find, so we're trying t o make 5 sure that the process is as clear as humanly possib le, not 6 only for our regional offices but for everybody in the 7 regulated community. 8 And it's also--for the stakeholder community it's 9 what's needed because every decision will be considered--at 10 least on alternative models will be considered in t he context 11 of its national importance and not just the regiona l 12 importance. 13 So I did want to take just a few minutes--this is 14 the formal process, and there are some roles and re sponsi15 bilities here that I'll also note. First and foremost, the 16 reviewing authority, whether it be a local program, a state 17 program, in some cases EPA or a tribal situation, t hey're the 18 first--they're the first rung in the ladder, so tha t's--when 19 an applicant is having issues, they're the people t hat need 20 to be addressed first. 21 When--in case it's not a regional office, if it's 22 a state, local, or tribal program, if they cannot r esolve the 23 issue or if it's going to fall in the territory of an 24 alternative model, then they can--they can engage t he 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**  regional office. And then from there the regional office 1 will engage us here in RTP. 2 We don't have situations--and I promise you some 3 of you will know. If you call me up and say, "Hey, George, 4 I've got this problem with this facility," I'm goin g to stop 5 right there and say, "Have you talked to the state, " "Have 6 you talked to the region," and "We need to have thi s 7 conversation in the context of all of them on the phone." 8 And that way the information process stays in its p roper 9
order. 10 At the point that it's determined that the 11 regional office is going--or needs to make a decisi on on an 12 alternative model through that delegated authority, they will 13 request from the Clearinghouse concurrence on theirdecision. 14 And so they'll actually write us a request, and it' s some15 thing that's done in coordination with us--it doesn 't happen 16 in a vacuum--and often in coordination with the sta te or a 17 local program. 18 A little earlier this morning I gave a demon19 stration of the Region 2 clearinghouse situation fr om July. 20 The state modeler, the regional modeler, and the 21 Clearinghouse closely coordinated as we pulled thatresponse 22 together, so it was not done in a vacuum. 23 The Clearinghouse would receive a statement of 24 issue, the desired approach with an appropriate jus tifica- 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**  tion--as the lawyers would like to say, a well reas oned 1 justification--and that would follow what's in Sect ion 3.2.2 2 of the current Appendix W. And fortunately for mapping from 3 the new to the proposed, it's also Section 3.2.2 inthe 4 proposed version. And then the Clearinghouse wouldengage 5 back with the solutions and write the formal concur rence-- 6 well, hopefully concurrence--memorandum. 7 Let's see. Moving along, so again, we summarize 8 those things in MCHISRS, which I demonstrated befor e the 9 break, and we also present things at the annual reg ional, 10 state, and local modelers workshop and at conferenc es like 11
these. 12 Fortunately in the last four to five years we also 13 have started having industry days where we will inv ite 14 outside stakeholders to the regional, state, and lo cal 15 modelers workshops, so again, that should be bringi ng 16 additional transparency. 17 And finally--and this I think is something that 18 people lose--generally in the community lose sight of. It's 19 the Clearinghouse memorandums that's another mechan ism for 20 bringing issues to us that identify things that we need to 21 change the course of the ship, so to speak, in whet her it's 22 the guidance documents we produce or ultimately rul emaking 23 that we need to go through. 24 So if we were not going through this process right 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**  now, this whole proposal process, and ARM2, just totake an 1 example, were presented to us, it would put first a nd 2 foremost that that's one of the things that needs t o be on 3 the docket for the next rulemaking. 4 And with that, I have a link here for the 5 Clearinghouse--again, that link will eventually cha nge--and 6 then my contact information, but this is for questi ons 7 specific to the Clearinghouse and not the proposal. So with 8 that I will end that presentation as close to on time. 9 And then I will move to the final presentation in 10 the morning session, and this is on single source a nd 11 cumulative impact analysis, which is maybe not the- -well, 12 it's a good title. But what I'm going to talk abou t is 13 really Section 8 and Section 9 of the proposed rulemaking. 14 So throughout the morning we have heard a lot of 15 discussion about AERMOD, AERSCREEN, met aspects of the 16 Guideline , other aspects of single source modeling in the PS D 17 context. We really have talked about all aspects o f Section 18 1 through 7 and portions of Section 8 that we're pr oposing to 19 update. 20 And all this culminates--it was previously 21 Sections 8 and 10, but all this sort of culminates at the 22 very end of Appendix W. And so what I'm planning t o do right 23 now is to talk about that culmination and what we p ropose to 24 do. And actually, I probably could take Tyler's ta lking 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**  points from his first opening session because he di d such a 1 great job. 2 But nonetheless, we simplified--I shouldn't say 3 simplified. It's probably a bad choice of words. We've 4 streamlined Appendix W, the Guideline , by reorganizing 5 information hopefully, and this is what we expect o r 6 appreciate your feedback on in a more logical manne r. 7 The previous Section 9 had a lot of information 8 about uncertainty, and it's one of those classic pi eces of 9 regulation. You get to the very end of the old Sec tion 9 and 10 it says basically disregard everything we just talked about 11 because we don't have enough information to bring i t to bear 12 in a regulatory context. There was a very awkward set of 13 text there. But nonetheless, we've reorganized inf ormation 14 from the previous Section 9, streamlined overall Appendix W, 15 so the previous Section 10 is now Section 9. 16 Despite us talking from the highest mountain or 17 valley or, you know, podium that we can find sayingthat 18 there's all sorts of reasons that you should not us e the 19 draft resource manual, the old puzzle book, at leas t in the 20 context of the permit modeling, is that, you know, if you can 21 use the old workshop manual and get the answer thatyou need 22 to get your permit, have at it, seriously. 23 But just because past practices have worked for 24 decades doesn't mean that they were necessarily thebest 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**  practices. Now, I'm a young whippersnapper, so to speak. 1 I'm not one of the old tried and true of the commun ity, but I 2 can tell you that things in that workshop manual we re overly 3 conservative. 4 Were they great thoughts? Yes. They were well 5 thought, well reasoned at the time, but the science , the 6 community has evolved, and we also have some very n ew, 7 different form standards, different time metrics th at we have 8 to take in consideration. And taking those into co nsidera9 tion in the mind's eye of the rest of the communityand the 10 rest of the tools that we have, we do need to move away from 11 some of the old unnecessarily conservative and comp licated 12 practices. So that's one of the things that we're attempting 13 to do in this rulemaking. 14 So throughout Section 8 we've intended to modify 15 the past practices and provide a more appropriate b asis for 16 the selection and the use of the various modeling i nputs. 17 I'll have some more slides on that in a minute. 18 And in Section 9, as Tyler said, what we've really 19 tried to do is get rid of a lot of old, bad or inco rrect 20 language that was in Section 9 and bring to bear th e policies 21 that the agency has been following with respect to single 22 source and cumulative impact analysis. And then inrare 23 circumstances, Tyler said, we've maintained and wil l remain 24 to keep the old Section 10.2.2 with respect to moni toring 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**  lieu of modeling. 1 So in Section 8, and this is new, there is a 2 section now talking specifically to the definition of a 3 modeling domain. That's information that previousl y was not 4 in Appendix W. We're proposing a new Section 8.1 w ith the 5 specific requirements that set up the definition ofmodeling 6 domain, and this is where you would have a radius e xtending 7 from your source that's either new or modifying outto the 8 point--the furthest point to which it can be demons trated to 9 have a significant ambient impact. So this is sortof 10 where--the old process of where you use a SIL analy sis to 11 figure out what your modeling domain is. 12 The other caveat is, is 50 kilometers, as Tyler 13 has said, at least for the inert pollutants and theNAAQS 14 compliance, is the limit. And so whichever one of these is 15 less is your modeling domain, and this is what woul d be used 16 in the cumulative analysis. 17 With respect to attainment demonstrations where 18 there was not information before, we're now providi ng some 19 more information that talks about setting and estab lishing 20 modeling domains in that context too. 21 Now, this is one that's a little bit different 22 because the nature of the problem is going to be di fferent. 23 You're normally talking about larger areas and mult isources, 24 and so that area needs to include all the major upw ind areas 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 could have impacts on the nonattainment area a nd also 1 all the monitors that are violating the nonattainme nt area. 2 And as a caveat and a previous modeler for a state, you 3 should really have--although we've seen it--all of the 4 nonattainment area in your modeling domain, but we classify 5 it as all the monitors being encapsulated. 6 I will say in both 8.1 and 8.2, and this happens 7 in the context of a well developed modeling protoco l, these 8 both should be vetted with the appropriate reviewin g 9 authority before significant modeling is underway. And 10 that's just an assurance on both sides that what's being done 11 is appropriate. 12 In Section 8.2 we have made some other changes, 13 and this flows along with the old source input datafrom the 14 previous Appendix W. Well, I say the previous; it' s the 15 current, the 2005 version. And I have listed out h ere some 16 specific section numbers with the various differentpieces. 17 But we have added new language with respect to, 18 again, SIP attainment demonstrations where AppendixW was 19 lacking previously--in this case for ozone, for fin e 20 particulates, and also for regional haze--new langu age on how 21 to characterize the direct and the precursor emissi ons, and 22 that's in 8.2.2(a). 23 We've revised the requirements on how to 24 characterize emissions from nearby sources that nee d to be 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**  explicitly modeled for the purposes of a cumulativeanalysis, 1 and that's covered in a handful of paragraphs in 8. 2.2(b), 2 (c), (d) of the new proposed Appendix W. And then finally in 3 8.2.2(e) we revised the language on how to characte rize 4 emissions from mobile sources, and that's been upda ted and is 5 more appropriate. And that happened with coordinat ion with 6 our transportation partners. 7 The most notable change--and this is the one that, 8 you know, flashing lights or whatever that we've ch anged--is 9 how to characterize the emissions from nearby sourc es. 10 Tables 8-1 and 8-2--they're still Tables 8-1 and 8- 2, and 11 that's for simplicity in all the world, so we didn' t change 12 the table numbers up--we have changed that nearby s ources 13 will now be characterized by--and I put it in quota tions 14 because there's 100 different ways you could classi fy this-- 15 what we traditionally have called actual emissions rather 16 than allowable emissions. 17 So my next caveat is the next bullet: emissions 18 are based on emission limit, operating level, opera ting 19 factor. Please look at Tables 8-1 and 8-2 to under stand the 20 full context of actual and allowable emissions beca use they 21 can take on some slightly different connotations. 22 With respect to the actual emissions, they need to 23 be based on the most recent two years of actual, an d I 24 probably should have put a comma there, nominal emi ssions. 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**  If the facility was shut down for two years for mai ntenance 1 or for a year for maintenance, you should not use o ne of 2 those in calculating what their actual emissions ar e. 3 I know many of you would like to, but you should 4 have two years of actual operation and they should be typical 5 operation. And so there's a bit of an art there increating 6 that emissions. Number one question: where's the inventory? 7 Just like with SIPs, there's some work that's goingto have 8
to be done there nonetheless. 9 I do also want to point out--and this is no change 10 in Tables 8-1 or 8-2 with respect to the new or mod ifying 11 source. They're still going to be characterized bytheir 12 proposed allowable or the permit limitation emissio ns, so the 13 only change is with nearby sources. 14 Then there's Section 8.3, and 8.3 kind of-- 15 everything here gets a little jumbled because this kind of 16 plays back on some of the things that we talked abo ut in 8.2 17 because this is where we're talking about how we co nstruct 18 the design concentration. And that has to be done in context 19 of whether you're an isolated single source or whet her you're 20 in a multisource area. 21 In an isolated single source area, typically 22 you're--and this is in the cumulative context--typi cally 23 you're going to have some background monitor that's going to 24 be representative of everything, and that's going t o be 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**  nearby sources and other sources and international emissions, 1 and then you're going to have your project source. 2 In the multisource area there's some updated 3 language in 8.3.3, and this is where you talk aboutthe 4 culmination of sources that could be nearby that ne ed to be 5 explicitly modeled, the other sources that are typi cally 6 characterized by background emissions, and the background 7 emissions. And then there's always the other emiss ions, like 8 I said, and that's typically taken care of by the monitored 9 background. 10 Before I get to that, I want to say a few more 11 things about 8.3. We also go into some detail here --and I 12 have it as the first bullet; I just missed it--is a 13 discussion of the importance of understanding of wh at the 14 monitoring data truly represent. 15 And this is--this is important because this goes 16 back to the bad past practices, because as often is the case, 17 we have seen time and time again that someone inclu des a 18 background monitor and they include--and I don't wa nt to give 19 a number because I'll miss--somebody will say, "Oh, I've seen 20 less" or "I've seen more," but numerous--underscore , 21 italicize, quotations, whatever, boldface--numerous nearby 22 sources. And there's a significant amount of overc ounting, 23 double counting, extra conservativeness that's put into the 24 demonstration. 25

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The community--what we're proposing is the 1 community as a whole, and that includes the states and 2 locals, they need to get out of the habit of just t aking 3 everything in the kitchen sink and throwing it at t he model 4 and then coming to us and saying, "We're getting th ese 5 outrageous concentrations," and you've got 1,000 ne arby 6 sources in there. 7 And so there is updating language--I'm jumping 8 around in the bullets, but there is updated languag e about 9 the concept of using significant concentration grad ients to 10 understand where you have situations where you havenearby 11 sources that are just not well classified or charac terized by 12 the monitor and need to be explicitly included. Bu t there 13 should be--and this statement is from the proposed guidance, 14 that there should be only a few nearby sources in most cases. 15 There's already been discussion this morning on 16 the met data side and the met data input, you know, the 17 introduction of the possibility of prognostic data where a 18 National Weather Service is not reasonably availabl e and it's 19 just not feasible to collect site specific data. And then 20 also we brought in AERMINUTE just so it was clearlyclassi21 fied in Appendix W. 22 Now, everything culminates in Section 9. We 23 stress--we updated the language with respect to 9.2 .1; it's a 24 recommendation, it's not a requirement--that the de velopment 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 a modeling protocol is extremely important. Thi s is the 1 living document that everybody can look to to under stand 2 what's going on, and a well developed modeling prot ocol on 3 the front end makes the whole back end with the pub lic 4 hearing and the public sharing of information much easier. 5 Information with respect to the design concen6 trations, previously we had information scattered b etween 7 Section 7 and Section 10. We had all very, very sp ecific 8 language for what individual standards were. As Ki rk got up 9 here and said with the models that were listed in S ection 6, 10 you look at it and you go what era, what decade is this from. 11 We removed that from the current proposed Appendix 12 W. We're not going through and listing out what every 13 current standard is and how to calculate it. That' s going to 14 be handled in guidance outside because the standard s change 15 and we can't update Appendix W every time we revisethe 16 NAAQS. We may need to at times, but we shouldn't do it every 17 time. So it's more dynamic. 18 We've also improved the discussion on receptor 19 sites in 9.2.2. Along with putting too many nearbysources 20 in, the other thing that we were seeing is people u sing tens 21 of thousands, if not hundreds of thousands, of receptors out 22 to 50 kilometers in every direction, and that is ex cessively 23 large and unnecessary. And this goes back to we'veupdated-- 24 are proposing to update language with respect to th e modeling 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**  domain, what's in that modeling domain, and then th e 1 receptors that you look in that modeling domain. 2 In 9.2.3 we overhauled the overall recommendations 3 of how to do the compliance demonstration. The lan guage 4 wasn't clear before and it wasn't concise, so now we have as 5 the first stage that you perform the single source impact 6 analysis. Some people refer to that as the SIL ana lysis. 7 And then only upon demonstrating that you are aboveor could 8 cause a significant impact, then you would move to the 9 cumulative analysis, which is much more comprehensi ve. 10 We also revised--and this was a major overhaul 11 because there were parts of the emissions limit dis cussion 12 that even our policy folks looked at and didn't understand or 13 realize--I mean most of the regional offices read i t and 14 said, "We didn't realize that was in Appendix W." And it was 15 outdated and it was largely incorrect given the form and the 16 time frame of the new standards. 17 And finally, as I just mentioned earlier, there is 18 some more information provided with respect to the monitoring 19 in lieu of modeling or the use of measured data in lieu of 20 model data, but as Tyler said, this is an area wher e we are 21 seeking input because this is an area where we don' t--we only 22 have a couple of very dated and very old examples. 23 And so we have provided more, hopefully more 24 clarity and some more structure on how one might st ep through 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 process to determine whether or not they can us e 1 monitored data, but there's a whole back end part t hat's not 2 in Appendix W and probably should never be in Appen dix W that 3 goes through the whole policy aspects of then how t he data is 4 used in actually writing the permit, potentially caveats that 5 need to be in that permit, conditions or postconstruction 6 monitoring or the like. And that's just something that's not 7 relevant or appropriate in Appendix W, but nonethel ess we end 8
that. 9 So Appendix W has this nice little, okay, we 10 defined the universe for models. If you have curre nt models, 11 you can use them, great, well and fine. If you have 12 situations that you need to use an alternative mode l or 13 there's not a preferred model, there are situations for that. 14 We define how you use your input data, how to put t hat in a 15 regulatory context. But if all else fails, there's this last 16 piece, and this last piece is the one that we want to get 17 additional comment from the external community. I think with 18
that I am done. 19 And so seeing that it is almost 11:45, I will take 20 this opportunity to break us for lunch. I'm going to keep us 21 on the 1:20 time schedule, so we get a few extra mi nutes for 22 lunch today. I'm trying to think of any other cave ats. Just 23 try to be back in the room by 1:20 because we'll st art then. 24 Have a great lunch, everybody. 25

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F U R T H E R P R O C E E D I N G S 1:24 p.m. 1 Mr. Bridgers: So I want to welcome everybody 2 back to the afternoon session of the first day hereof the 3 11th Conference on Air Quality Modeling. As if themodeling 4 conference wasn't already a public forum or public hearing 5 that's being transcribed, this is also a public hea ring for 6 the proposed rulemaking on the revisions to the Guideline on 7 Air Quality Modeling, as I mentioned that this morning. So 8 from this perspective, it's at this point that we a ctually 9 start the public hearing officially for the notice of 10 proposed rulemaking. So as the public hearing offi cer, I 11 call the public hearing to order. 12 Just as a reminder--I don't want to spend a lot of 13 time on this and we can go right into the presentat ions--all 14 the presentations today are part of the record. Th ey'll be 15 put in the docket at some point, in the week or so following 16 this conference. As I mentioned earlier, most of a ll the 17 presentations are already posted online that you ca n get 18 through the agenda that's posted online. And I'll make 19 that--I'll have more clear links over the next coup le of days 20 for others that weren't able to join us here. 21 I do ask that everybody identify themselves when 22 they come up to the microphone. And to that end, f or the 23 court reporter next to me, I am George Bridgers wit h the Air 24 Quality Modeling Group here at the USEPA. All the docket-- 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**  all the dialogue will be transcribed. We're not having any Q 1 and A. Let's see what else in my caveats. 2 Anyone that did not request a time to speak in 3 advance will have an opportunity tomorrow late morn ing and 4
then tomorrow afternoon to offer oral comments to t he docket. 5 Otherwise, comments then can be submitted to the do cket for 6 the next--it depends if you count from today or tomorrow, for 7 the next 74 or 75 days to October 27th of 2015. 8 We have a full afternoon. Although there are only 9 15 presentations, there's a lot of material to cove r. So I 10 ask that all speakers keep to their set times. Andto that 11 end since we're only offering 15 minutes, I will have to cut 12 people off. I will not try to be rude about it, bu t when we 13 get to 15 minutes, that's your allotted time. We w ill hold 14 that tomorrow as well with the public oral comments

. 15 So without wasting any time, I would like to 16 transition. And first up we have three presentatio ns, 17 although they're by different affiliations for Bob Paine, 18 they're from Bob Paine. This is not the Bob Paine 19 conference. And so Bob Paine. 20 Mr. Paine: Thank you. You've already 21 identified me. I'm from AECOM and I've given the c ourt 22 reporter a business card. This talk is going to beon behalf 23 of the American Iron and Steel Institute or AISI. And we're 24 going to talk about near-field modeling and source 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**  characterization issues for near-field modeling. I would 1 like to express appreciation to EPA for the dialogu e that 2 AISI has had with EPA on these issues and we're goi ng to 3 continue with that dialogue. 4 I'm going to talk about two issues that I have 5 time for and then there are supplemental issues tha t are 6 provided as attachments to the presentation, which I will 7 summarize very briefly at the end of my verbal comments. 8 Highly industrialized areas are mentioned briefly 9 in the proposed Appendix W changes and we would like to 10 expand on that discussion here. However, those wit h large 11 heat releases over a sizeable area can and should b e modeled 12 with urban dispersion option in AERMOD. 13 The other issue I'm going to dwell upon at some 14 length is stack plumes on or near buildings that have 15 experienced fugitive heat releases maybe not relate d to the 16 actual stack that can lift off the plumes being modeled. 17 That would--accounting for those effects would redu ce 18 inaccurate overpredictions due to the current downwash that 19
does not account for these heat releases. 20 The supplemental issues provided as attachments 21 deal with some evaluation results for these two items at the 22 top and also two other issues. And that is plumes from 23 adjacent stacks that would be partially merged and result in 24 a higher effective plume rise and also plume rise f rom moist 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**  plumes that isn't really addressed in AERMOD. 1 I have already mentioned the EPA and AISI have 2 been discussing these, and several technical docume nts have 3 been provided to EPA. But these documents will als o be 4 provided to the docket for this rulemaking by AISI. 5 Okay. Let's talk about urban dispersion for 6 highly industrialized areas. Right now--and this i s really a 7 source characterization effect. It's not really a change in 8 the model, but it's a change in how you characteriz e a 9 source's input to the model. 10 Normal assignments of urban versus rural 11 dispersion are important here. And industrial proc esses in 12 geographic areas of large heat releases but low pop ulation, 13 such as areas with a lot of industrial activity whe re not a 14 lot of people live and there might be water bodies nearby 15 that would make the 3 kilometer circle be character ized as 16 rural, but with all the heat release, it's probablybetter to 17 model it as an urban area with a large effective population. 18 And I'm going to talk about how to characterize 19 that effective population. Actually, Appendix W do es refer 20 to that, the need to do this characterization. Thi s 21 characterization would then provide the appropriateurbanized 22 treatment of mixing height and the temperature laps e rate for 23 the dispersion calculations. 24 Now, in the classic urban area, which is shown 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**  bottom right, there is a temperature excess at the core of 1 the urban area. And you can identify the depth of the urban 2 heat island, basically the boundary layer, by the t emperature 3 difference between the core of the urban area and t he 4 outskirts. 5 But as I said, these large industrialized areas do 6 not meet the classic definition for an urban area, but the 7 formulation of AERMOD does provide a way to paramet erize the 8 effective urban population if you can get an idea o f the 9
delta-T between the urban and rural. 10 The next slide shows how to get that. From the 11 AERMOD model formulation, the delta T u-ris related to the 12 population input to the model with this relationshi p. Where 13 there's a 12 degree Celsius delta-T, it is related to a 14 population--a reference population of 2,000,000. 15 You can get at the temperature difference now via 16 satellite data, which I'm going to show an example of. And 17 there's going to be more documents uploaded to the docket 18 that explain how to use satellite data to obtain th is very 19 important input to this process. 20 Alternatively, if you have engineering estimates 21 of the excess heat release, the bottom equation, ifyou can 22 see it, shows how you relate the watts per square meter 23 excess heat release to the temperature difference, and then 24 the temperature difference can be related to the ef fective 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**  population. 1 So let's talk about how we can get measurements of 2 this urban-rural temperature difference via satelli te data. 3 Available satellite platforms are ASTER and LandSat8. And 4 again, we're going to provide more technical discus sion of 5 how to access these databases. You actually don't get the 6 temperature difference map directly from the satell ite data. 7
You have to download the data and then create the map. In 8 the explanation we'll go into how that's done. 9 We provide an example on the next slide of such a 10 map and also in Supplement A to the presentation th at will be 11 online. And what you really get is a brightness temperature 12 that is related to the actual physical temperature 13 difference. Obviously these procedures are relatively new, 14 being refined. 15 The next slide shows an example of a highly 16 industrialized area with the white ellipse. And yo u can see 17 on the right side the variation of the temperature, the 18 brightness temperature. And the difference betweenthe core 19 of that highly industrialized area and the outskirt s is 20 roughly about 12 degrees Celsius. 21 And you can then accommodate that to the equation 22 on the previous slides. That would be an effective 23 population of about 1,000,000, which then could be used as 24 input to AERMOD with an urbanized--urban approach w ith 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**  effective population of 1,000,000. The next--and a gain, the 1 Supplement A gives more information about how this has been 2 evaluated already with a highly industrialized area

. 3 The next topic I want to talk about is building 4 downwash issues with this fugitive heat liftoff eff ect. In 5 fact we have a procedure called LIFTOFF. 6 There is an issue of--there is an issue with light 7 winds and downwash. Sometimes we get in AERMOD high 8 predictions in light winds, which is somewhat count er9 intuitive. I list a couple of papers down at the b ottom of 10 this slide that discuss this issue of downwash and light 11 winds. The bottom paper, which is a plume lift-off 12 consideration, is the core of this new technique, apaper by 13 Hanna, Briggs, and Chang. And I'm going to talk ab out a 14 formulation in that paper that we are using in this new 15 procedure. 16 When we see these predictions under light wind 17 stable conditions, we realize that they are probabl y not real 18 in some sense or they wouldn't be expected because first of 19 all you'd expect intermittent downwash with the win ds 20 fluctuating. AERMOD does not accommodate the fact that you 21 have unsteady downwash in conditions with a lot of wind 22 fluctuations in effect. To my knowledge the PRIME model does 23 not have a meander treatment in AERMOD, so that's a nother 24 reason why you might get an overprediction in lightwinds 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 downwash effects. 1 So how to adjust for this issue? Actually, 2 there's another model; the Danish OML model does ac count for 3 the intermittent nature of light winds on downwash, and the 4 publication is available here as a link. There's aweighting 5 factor in that model to accommodate the intermitten cy of this 6
effect. 7 Now, let's add the issue of heat releases onto low 8 winds, and we have a treatment in that referenced p aper with 9 a dimensionless buoyancy flux that's related to theheat--the 10 fugitive heat release, the wind speed, which is an hourly 11 effect, and a plume width that's probably tied to t he 12 building width. 13 So what we created is sort of a postprocesser to 14 AERMOD where we deal with the intermittency by usin g an 15 hourly weighting factor between two extremes, the n o downwash 16
case and the full downwash case. 17 As the buoyancy flux, dimensionless buoyancy flux, 18 goes toward zero, you would tend toward a full downwash 19 treatment. As the dimensionless buoyancy flux incr eases to a 20 large number, it would tend to a no downwash extreme. And in 21 the middle you would have a weighting of the two ef fects. 22 The evaluation testing has been--is done actually 23 not only by the studies cited in the Hanna, Briggs, Chang 24 paper, but also in a recently conducted field studythat'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**  going to be described more in documents submitted t o the 1 docket. Also in Supplement B we had four SO 2monitors around 2 the site with such heat releases. And the default modeling 3 approach with full downwash did overpredict substan tially. 4 This liftoff approach had much more accurate 5 predictions. We used satellite imagery to documentthe 6 buoyancy flux. For example, look at this. This wa s a plume 7 from this facility. 8 You're going to see in the next slide a thermal 9 infrared image with an intense heat from--they're n ot really 10 pollutants, but they're emitting heat. You also se e that the 11 building temperature is much higher than the ambien t. So you 12 have lots of heat being exuded. You can't see them . You 13 can't see this visually, but you can see it with th e right 14 kind of camera. So this effect is imparted into th e liftoff 15 postprocessor. 16 So to summarize issues with written comments 17 coming, I'd like to bring back the issue of when st acks are 18 touching or nearly so, I don't think we have a nati onwide 19 consistency of treating those as merged. But thereis a 20 Clearinghouse record--and I think that should be 91 -Roman 21 numeral II, rather than 11. The issue was addresse d in a 22 Clearinghouse record such that stacks that are with in 1 23 diameter should be modeled as fully merged, so I hope that 24 can be a national consistency issue that EPA addres ses. 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** 

Partial plume rise enhancement, this is going to 1 be--this is Supplement C in the presentation. Briggs had an 2 explanation in various classic textbooks, '75, '84, 3 Atmospheric Science and Power Productionor something like 4 that, where he has an algorithm for stacks in a rowwith 5 partial plume rise enhancement. That is--we've acc ommodated 6 that in a procedure we call AERLIFT. 7 And finally, we have the other procedure for plume 8 rise models for exhaust streams with substantial mo isture 9 that we call AERMOIST. And in that case the relati ve 10 humidity is a factor. What we do there is we prepr ocess the 11 hourly emission input so that the effective tempera ture input 12 to AERMOD is actually modified to accommodate the h eat of the 13 condensation due to moist plumes. That comes from basically 14 a model that's been validated in Germany, and the details are 15 going to be provided to the docket. And they are a lso in 16 Supplement D to this presentation. 17 So finally, the AISI recommendations for source 18 characterization effects to EPA would be that Appen dix W 19 should further clarify that the case by case source 20 characterization refinements should not be treated as 21 alternative model options, but should be allowed wi th 22 adequate documentation as normal, more accurate sou rce 23 characterization. 24 And besides the urban characterization for large 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**  industrialized areas that Appendix W does briefly mention, 1 we'd like it to be mentioned more clearly, maybe inthe model 2 implementation guide. 3 I mentioned the plume liftoff issue for fugitive 4 heat releases on buildings that affect downwash tre atment, 5 plume merging, not only due to stacks that are touc hing or 6 nearly so--that should be a no-brainer--but for sta cks that 7 are in a row that can have plume enhancement--that' s a 8 function of direction and other effects that AERLIF T accounts 9 for--adjustments to plume rise due to their moistur e content. 10 So each of these issues can be addressed by source 11 characterization approaches that improve the hourlyemissions 12 input. AISI requests these techniques be acknowledged as 13 viable source characterization options in Appendix W and 14 perhaps the AERMOD implementation guidance document . And my 15 15 minute buzzer has gone off. 16 Mr. Bridgers: You did have one more slide, 17 didn't you? 18 Mr. Paine: Oh, that's just the rest of 19
the--- 20 Mr. Bridgers: (interposing) The supplements. 21 Mr. Paine: It will be on the web site. 22 Mr. Bridgers: And I know some of you saw me 23 running about just a minute ago trying to do some s tuff over 24 there, and it's proof positive of government bureau cracy. 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**  had to get a contractor to come dial a telephone number. So 1 we once again acknowledge Bob Paine. 2 Mr. Paine: Thank you. Low wind speed 3 issues have been brought up this morning as importa nt 4 improvements in AERMOD. I've been talking about th at for 5 several years. But now we're going to augment the emphasis 6 on the evaluation databases of lower level sources to tall 7 stack databases. And in fact this study has been w ritten up 8 in a technical paper that has been accepted for pub lication 9 by the Journal of the Air & Waste Management Association , so 10 that should appear later this year in print. I wou ld also 11 like to acknowledge the sponsorship on this study t o EPRI and 12 the Lignite Energy Council. 13 I'm going to talk about the background for this 14 study, but I already sort of have. It's basically augmenting 15 the emphasis on lower level sources to tall stacks, a 16 description of the evaluation databases, the modeli ng options 17 evaluated, and the evaluation results and the overa ll results 18 and conclusions. 19 Now, before AERMOD, you know, model input wind 20 speeds were never allowed to go below 1 meter per s econd. 21 And as part of AERMET, our committee was--thought we could 22 conquer the world, and so we decided to go lower th an 1 meter 23 per second. But we are straining the steady state model 24 plume assumptions, which tend to break down as wind s go 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**  toward calm. 1 But AERMOD, in any case, does allow arbitrarily 2 low wind speed inputs down to the instrument thresh old, which 3 seem to be getting lower and lower these days with ice-free 4 instrumentation and sonic anemometry. So that's an other 5 thing that we didn't foresee in the '90s maybe. 6 So in an attempt to account for this effect with 7 plume meander, it's a random plume and a coherent p lume 8 weighting scheme that's shown in this slide, which is 9 borrowed from a Joe Scire presentation a few years ago 10 whereas we have a wind blowing from the south here in this 11 figure and the stack at 0.0 in the center. 12 And the coherent plume is predicted as the usual 13 Gaussian plume equation and its concentration is us ually much 14 higher than the so-called meander or pancake plume, which I 15 believe LowWind3 tends to chop off the bottom half of that 16 pancake such that we look at upwind concentrations. But 17 that's basically--the weighting between these two e xtremes is 18 what is done by the meander algorithm in AERMOD. 19 Okay. What did we bring up in our studies from 20 EPRI and UARG in 2010? We realized that friction velocity, 21 which is an important output of AERMET, was underes timated in 22 very low winds by up to a factor of 2. This result ed in 23 several compound issues in stable conditions--an un der24 prediction of the level of turbulence, the mechanic al mixing 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, and other related issues were underestimate d, which 1 led to too concentrated of a plume in stable condit ions. 2 Perhaps even the plume meander weight was possibly under3 estimated. 4 So we recommended changes in both the friction 5 velocity formulation and also recommended a change to the 6 minimum lateral plume spread in the AERMOD dispersi on model 7 to help account for the additional meander you woul d expect 8 in very light winds. 9 And I think this has already been explained. EPA 10 started to accommodate these changes in various ver sions 11 listed in the second bullet and finally in this ver sion have 12 come up with recommendations for a final ADJ_U* in AERMET and 13 a LowWind3 option in version 15181. There have bee n previous 14 webinars, and of course today's presentation has pr ovided 15 basic recommendations to adopt these changes. 16 I would concur that the proposed changes should be 17 made a permanent part of the model. I also want toadvise 18 EPA that due to hundreds of sources being modeled f or SO 2 19 these days, we may not be able to wait until next s pring. 20 And we hope that we can get an interim approval pro cess in 21 place for approval of these options now because modeling is 22 happening right now. And it's very critically impo rtant to 23 have these improvements accommodated in the model. 24 And I want to talk now about the findings 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**  tall stacks, which are a critical part of the SO 2modeling 1 that's being done nationwide. Two databases we loo ked at: 2 North Dakota Mercer County with rolling terrain, on e elevated 3 monitor and five monitors in all, four years of dat a; and we 4 talked about--I've seen Gibson before. We happenedto focus 5 on three specific years with four monitors. It's atall 6 stack, flat terrain database. Both of these databa ses use 7 the data from a 10 meter tower to evaluate standard 8 airport-type meteorological input. 9 We tested four options of AERMET and AERMOD in 10 default mode. This was model version 14134. Then we added 11 the beta U* option, but not any changes to AERMOD. And then 12 we added changes to the minimum sigma-v with the LowWind2 13 option in the last two options tested with a 0.3 an d a 0.5 14 meter per second minimum sigma-v. 15 We have produced various statistical tests which 16 are going to be discussed in that JAMA paper. And I'm going 17 to only have time really to present the 99th percen tile peak 18 daily 1 hour max statistics during the little bit o f time I 19 have here. We did Q-Q plots as well as review of meteoro20 logical conditions associated with peak predictions that I 21 will mention briefly today. 22 The key thing on the North Dakota database is the 23 fact that we have these five monitors that are sortof these 24 square pink or purple objects here. One of them is circled 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 high terrain, the DGC 17 monitor. Sources that were near 1 these monitors were the Antelope Valley station andthe Great 2 Plains Synfuels Plant, the red triangles. 3 The other four monitors were in relatively low 4 terrain, but this one monitor was in higher terrain . Notice 5 that the DGC 16 monitor was the closest to these so urces, and 6 it has a little bit of a different response to the models 7 than the other three in low terrain. Backing up, we also 8 modeled more distant sources, maybe more distant th an the new 9 guidance would say because these are approaching 50 10 kilometers away. 11 Okay. Now I'm going to dwell on this slide for a 12 little while because we take those four modeling op tions-- 13 from left to right, it's default AERMET, default AE RMOD. The 14 yellow is AERMET with beta U*, but no sigma-v LowWi nd2 15 options. Then we add the sigma-v minimum of 0.3 an d 0.5 as 16 the green and the purple bars. 17 We see that for--DGC 17 is the one that's next to 18 the--second from the right. That shows a large--wi th that 19 elevated terrain, that shows a large response to th e beta U* 20 option. In the other applications in terrain, I'venoticed 21 large responses. The other models show--the other monitors 22 show no real response to the beta U* option becausethe peak 23 predictions are in daytime conditions, but some res ponse to 24 the minimum sigma-v options. 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 DGC 16 had a little bit higher overprediction. 1 By the way, let's go back to that. Notice that on the 2 y-axis, all the models are predicting at or above a1.00 3 model to monitored ratio. So all overpredicting we re nearly 4 unbiased. But we see that adding these low wind op tions 5 improves the model performance, especially with thebeta U* 6 option for the monitor in high terrain. The low wi nd 7 options--the LowWind2 options result in somewhat in cremental 8 performance improvements. 9 Also, we noticed for that elevated monitor that 10 the meteorological conditions observed for the high est 11 concentrations were more aligned with the predicted 12 conditions when we added that ADJ_U* option becausewithout 13 it, all--almost every high hour was predicted to beat night. 14 But several high hours were predicted to be during the day-- 15 were monitored to be during the day. With the ADJ_U* option, 16 the predicted conditions were more in line with theobserved 17 conditions for the highest concentrations. 18 So the overall results from this database were 19 that the AERMOD default predicted the highest--overpredicted 20 substantially at the elevated monitor. The low win d options 21 did improve the performance at all monitors. It tu rns out 22 that even a minimum sigma-v of 0.5 was still relati vely 23 unbiased, did not underpredict. 24 The other database is Gibson and the monitors 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**  the four monitors with the yellow triangles. This is a very 1 flat terrain, tall stack database. Similar type of 2 appearance of the results here, but we see that wit h the flat 3 terrain, there is no real response to the ADJ_U*. In fact 4 with Mount Carmel, the beta U* option has a high wi nd side 5 effect. Sometimes high winds cause the predictions to go up 6 with the ADJ_U* option. 7 But by and large they were pretty much unaffected 8 by the ADJ_U* option--this is the yellow--and a lit tle bit of 9 an effect with the LowWind2 option. Certainly the low wind 10 options did not do too much to this database, impro ved it 11 slightly. 12 So the overall evaluation results again were 13 relative insensitivity to the model performance on the basis 14 of low wind options because the concentrations werepredicted 15 and observed during daytime conditions--there will be more 16 about that in the next presentation--relatively ins ensitive 17 to, you know, anything you do with stable condition s and a 18 little bit of sensitivity to the minimum sigma-v. But since 19 the winds causing the highest concentrations were alittle 20 bit too high, higher than those very low wind speed s, not 21 much of an effect. We still had, though, a general 22 overprediction from 10 to 50 percent. 23 Overall conclusions would be that the--and as I'm 24 going to say at the bottom, we haven't yet conducte d or had 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**  time to do any further testing on the new release, but as 1 Roger indicated, we would not expect much of a chan ge from 2 what we've seen so far with the LowWind3 option. 3 Tall stacks would have the lowest effect with 4 these low wind options with high terrain. There's a minor 5 effect only with flat terrain. But the effect in e levated 6 terrain is very profound, especially as you get ver y high 7 terrain. And so this ADJ_U* option will be extreme ly 8 important to put into the model and to have it as adefault 9 option. 10 We note that the LowWind3 option only has a 11 minimum sigma-v of 0.3, so the fact that we still d idn't get 12 underprediction at 0.5 would mean that the LowWind3option in 13 version 15181 is likely to be still slightly conservative. 14 The low wind options also improved the consistency of the 15 prediction of the meteorological conditions associa ted with 16 the highest observed and the highest predicted conc en17 trations. 18 So we do believe that the proposed options will 19 result in more accurate AERMOD predictions and we would like 20 to have the ability to use these options very soon in routine 21 modeling assessments. I think that is the last sli de. I 22 gave you 45 seconds. 23 Mr. Bridgers: Thanks, Bob. So once again I'd 24 like to introduce to the podium Bob Paine. 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. Paine: Thank you. These are issues 1 related to--maybe it's an issue that people have no t been 2 generally aware of, but you can also call this "Beware of the 3 Penetrated Plume." And this work followed from wor k we did 4 in the previous--the low wind study, but it's also related to 5 other interactions I've had with other investigator s, this 6 time Down Under, as you'll see. 7 I'm going to talk about the overview of the 8 issues: available diagnostic tools that most peopl e don't 9 have access to that have allowed us to find out wha t's really 10 happening with the predictions in tall stack releas es of 11 AERMOD, available model evaluations that have shed more light 12 on why this is an issue of concern, the evaluation results, 13 and conclusions. 14 Now, we've noted--we've done a lot of modeling 15 applications with tall stacks and we noticed that i n many 16 cases the highest one hour predictions--and this is obviously 17 applicable to SO 2 , because that's a one hour standard--we 18 keep seeing daytime conditions with low mixing heights and 19 low winds leading to the highest predictions, so th at's 20 interesting. 21 Observations tend to indicate that, well, the peak 22 predictions for tall stacks are expected to be duri ng the 23 daytime, but they're not always during low mixing h eights. 24 They're randomly scattered between low and high mix ing 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**  heights. So why is the model tending to favor justlow 1 mixing heights rather than a variety of mixing heights? 2 We have the ability, and I'm going to show an 3 example, of debugging output from AERMOD that indic ated that 4 the cause of these highest predictions is due to pl umes that 5 are actually emitted into the stable air aloft init ially, but 6 somehow reach the ground within a relatively short distance, 7 maybe 5 kilometers, maybe a little bit more than th at. 8 And that condition is associated with--and I'm 9 going to show an example of the three plume treatme nt in 10 AERMOD, but the penetrated plume is the plume that is 11 injected into the stable layer aloft. Previously t hat plume 12 was totally ignored. In the ISC model the predicti on of that 13 plume was assumed to be zero. 14 Now, believe it or not, it's actually controlling 15 the design concentration in AERMOD for tall stack r eleases in 16 flat terrain. Obviously in complex terrain it's st able 17 conditions, but this is for simple terrain, tall st acks in 18
AERMOD. 19 This picture I'm sure is from several training 20 figures that have been provided. Imagine here thatthe top 21 dashed line is the convective mixing height; the lower dashed 22 line is the mechanical mixing height. The direct material is 23 assumed to be material that does not really interac t or bump 24 up against the mixing height in convective conditio ns and it 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**  is mixed to the ground directly, no interaction wit h the 1 mixing lid. 2 The indirect material does not have enough 3 momentum or buoyancy to penetrate into the stable a ir aloft, 4 but it hangs up like a balloon on a ceiling againstthe 5 mixing lid and then eventually mixes down. But the 6 penetrated plume gets up into there and would not r eally be 7 expected to get down to the ground very rapidly. 8 Another depiction shows that the model treats 9 these plumes as separate--almost separate releases that has 10 different calculation do loops for--accounting for their 11 impacts but then adds them all together. So the pa rt of the 12 plume above the inversion layer or into the inversi on layer 13 is related to the part--you know, the mass that's a llocated 14 to the prediction is the total mass emitted times t he 15 penetration fraction. And when that penetration fr action 16 gets toward 1.0, that plume becomes very important in the 17 calculation. 18 Here's just a visualization of what you might 19 envision as a penetrated plume being. It's daytime . The 20 plume goes up and it hits the stable air and it jus t sort of 21 goes off to the left. It doesn't really mix down t o the 22 ground, visually at least in the realm of this pict ure. 23 Now, you probably can't see this, but I'm going to 24 point out we have this debugging output that actual ly comes 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**  from a--the bottom indicates we had actually downlo aded this 1 version of AERMOD, version 14134, available for download at 2 the EPRI web site where you can get other things li ke EMVAP. 3 It has a lot of useful debugging information. 4 The top part that's circled in red is the 5 mechanical and convective mixing height. In this c ase--I'll 6 just read off the number--the convective mixing hei ght, which 7 is a little higher than the mechanical mixing heigh t, is 256 8 meters. We have a final plume height--what happens for each 9 hour is that the controlling receptor is listed foreach 10 source model, and all sorts of information about wh at's 11 happening at that receptor is displayed. 12 We know what the final plume height is. The final 13 plume height is about 355 meters versus a convective mixing 14 height of 256 meters. So the plume gets up to be about 100 15 meters into the stable air aloft. But the dominantplume is 16 identified as the penetrated plume. We know that b ecause the 17 debugging information polls that it's--is it direct , is it 18 indirect, is it penetrated. The penetrated wins be cause it 19 has 90 percent of the mass. And that hour turned o ut to be 20 the highest predicted hour for that whole simulatio n. 21 So we can identify with this debugging output what 22 is causing the highest predicted concentrations. T hat's not 23 usually displayed in the version of AERMOD that comes out of, 24 you know, EPA. This is additional debugging information, 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**  we have lots of evidences of what is happening. 1 Now, I've been talking over the years with Dr. Ken 2 Rayner of Perth, Australia, who likes to dabble wit h code. 3 And if he doesn't understand anything about AERMOD, he would 4 dicker with the code and change it. And he was ver y 5 interested in using AERMOD and CALPUFF and trying t o get the 6 best model, and he had observed data from tall stac ks and 7 simple terrain. And he had a presentation with a l ink here 8 that you'll be able to download when you download t his whole 9 presentation. 10 The map here shows that in western Australia there 11 was a source, Muja power station, which is the lowe st red dot 12 there, and the Shotts monitor, which is about 8 kil ometers 13 from--circled in blue is a monitor where there was a model 14 evaluation conducted, relatively low terrain betwee n the 15 power plant and the monitor. 16 The Q-Q plot that Dr. Rayner provided shows both 17 the AERMOD with the penetrated plume and then with the 18 penetrated plume disabled because he went into the code and 19 disabled it. He shows about a 50 percent overpredi ction at 20 that monitor, and with--you know, with obviously th e 21 penetrated plume disabled he can show that the diff erence is 22 such that you need some of the penetrated plume the re, but it 23 makes a big difference and it's really the cause ofthe over24 prediction. 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 he had comments in his presentation that he 1 believed that AERMOD mixes the plume to the ground too fast 2 because it has to do everything in one hour, wherea s a 3 penetrated plume might be looked upon as a multiplehour 4 phenomenon. The plume is injected above the mixinglid, but 5 somehow it gets down to the ground as if it mixes down into 6 the convective mixing layer in the same hour, so is all that 7 just being squeezed by a steady-state model. 8 The other issue is the mixing height is assumed to 9 be constant, but it's obviously changing within thehour, so 10 that's another issue with a steady state model. Th ere's a 11 lot of constraints here. So he found an overpredic tion on 12 the order of 50 percent for his case. 13 Let's go back to Gibson. We did debugging on that 14 too. Isn't it interesting? We're also getting abo ut a 50 15 percent overprediction due to a penetrated plume fo r this 16 database--consistency. 17 So actually, I'm going to finish quickly here. 18 We're seeing at least for these two databases a con sistent 19 pattern for AERMOD peak predictions for tall stacks in simple 20 terrain. We can identify with our debugging output --or Ken 21 Rayner can identify with his debugging, his code ch anges, the 22 penetrated plume is causing it. It may be reachingthe 23 ground too fast, and maybe it's due to sigma-z. It 's 24 something that would warrant additional EPA review. 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** 

Now, Appendix W does indicate in various places 1 that the AERMOD model uncertainty is in the order o f 10 to 40 2 percent. Maybe we can extend that to 50 percent ba sed on 3 this issue. I would say that I would be happy whenthe model 4 is only 50 percent uncertain because that's well wi thin the 5 factor of 2. 6 But with these SO 2NAAQS demonstrations, if you 7 model--if the standard is 196.5 micrograms per cubi c meter. 8 If you model 200, is that enough to say that you kn ow there's 9 a violation of the NAAQS? Absolutely not. You cou ld be 50 10 percent over the NAAQS with your model and not be able to say 11 that you know there's a NAAQS violation, especiallyif the 12 controlling concentration is caused by this issue. 13 We hope to be able to review the new model to see 14 if this issue is still present, but I just wanted t o alert 15 the user community to this issue with AERMOD. And that's-- 16 okay, I'm done. 17 Mr. Bridgers: Well, Bob, you've got 3 more 18 minutes if you--- 19 Mr. Paine: (interposing) That's okay. 20 Mr. Bridgers: So at this point I'm going to 21 call to the podium Richard Hamel, not Bob Paine. And so, 22 Rich, if you'll identify yourself, you're good to g o here. 23 Mr. Hamel: I have to wait till I see the 24 first second tick off, okay. I'm not Bob Paine, bu t I am 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**  wearing the same shirt today. But I am Rich Hamel. I'm a 1 senior air dispersion modeler at Environmental Reso urces 2 Management or ERM in the Boston office. 3 And what I'd like to talk to today is the proposed 4 move to ARM2 as the Tier 2 method for refining the NO xto NO 2 5 conversion in AERMOD and take it with a bit of prac tical 6 approach to what does it really give us when we aretrying to 7 model compliance, not only with the NAAQS, but alsohoping to 8 get a model result that would have our impacts below the 9 significant impact level so we don't have to do cumulative 10 modeling. 11 Okay. So I'm going to talk about a quick overview 12 of the old--ARM and the old ARM2, which is really t he ARM2 13 with a minimum NO 2to NO xratio of 0.2, a little bit about 14 ARM2 in the proposed revision, a comparison of the Tier 2 and 15 Tier 3 options for NO 2conversion, what are some of the 16 benefits or changes in the proposed ARM2, what are some of 17 the issues, and then just a quick word about Tier 3

. 18 And you can see there the molecule for NO 2and the 19 chemical bar equation, ONO, or as we all said the f irst time 20 we tried to model an emergency generator against th e new NO 2 21 standard and saw the results, "Oh, no." 22 EPA allows us three different tiers. We know this 23
from our NO xmodeling experience. Tier 1 is just assuming 24 the full conversion of NO xto NO 2through modeling. Tier 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**  is the ambient ratio method based on analysis of ambient 1 monitoring data. That's the old ARM and ARM2, and then, of 2 course, Tier 3, which is refinement based on the ox idation of 3 nitrogen oxide by ozone to NO 2 , and that's the OLM and PVMRM 4 methods by the formula that you see there below. 5 Where did ARM originally come from? Originally it 6 was designed outside the realm of air dispersion mo deling and 7 there was a decent amount of study done. But when annual NO 2 8 modeling came around, the 90th percentile of the average 9
annual NO 2to NO xmonitoring data, as it was known at the 10 time, was used and that established a ratio of 0.75 . When 11 the 1 hour NO 2NAAQS came around, that wasn't considered a 12 conservative enough representation for short term modeling. 13 So the ARM ratio was set to 0.8. 14 So enter ARM2. Mark Podrez in 2013 working for 15 API did a study of all of the NO 2monitors in the United 16 States and some elsewhere, which amounted to 580 mo nitors, 17 looking at ten years' worth of data from 2000 to 20 10, which 18 gave a data set of over 5,000,000 hours to look at and the 19 ambient ratios of NO 2to NO x . Based on that data, he 20 developed a 6th order polynomial curve and found th at this 21 curve fairly consistently matched the ratio of NO 2to NO x , 22
based on the amount of NO xin the ambient air. 23 So it was really designed as a simpler alternative 24 to Tier 3 refinements, a way to get a Tier 3-like e ffect 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**  a little more conservatism than OLM or PVMRM withou t having 1 to deal with the whole issue of finding in-stack ra tio, 2 documentation for each of your sources, background ozone 3 data, and things like that, of course the advantagebeing 4 there are no additional inputs needed. You simply have a 5 look-up table against the curve at each of your rec eptors at 6 each of the hours. It would run faster than the Ti er 3 7 refinements and also wouldn't require case by case approval, 8 meaning not only less time to process, but less time to 9 review. 10 And this is the original ARM2 curve against all of 11 the hours that were posted. And you can see that t he curve 12 for the most part contains all of the hours that we re looked 13 at during the study with some outliers at the top a nd results 14 in ambient ratios anywhere from less than 0.1 at ve ry high 15
NO xconcentrations of 600 ppb and above, all the way up to a 16 1 to 1 ratio, and this is in very low cases, althou gh there 17 was also some documentation that some of those case s were 18 very specific situations that caused such a close c onversion. 19 So ARM for AERMOD was added as a beta option in 20 version 12345 with an upper limit of 0.9 and a lowe r limit of 21 0.2, although those could also be set manually--tho se are the 22 defaults--required a case by case approval for use in permit 23 modeling. 24 And the EPA webinar last year around the release 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 AERMOD version 14134 recommended that if your Ti er 1 1 modeling results were less than 150 to 200 ppb, the n the use 2 of ARM2 should be expedited in terms of the approva l process. 3 If you had initial results higher than that, then astudy of 4 the in-stack ratios of the sources being consideredwas 5 required. And also, special consideration was give n to 6 higher thresholds in situations where background NO 2was very 7 high or if background ozone layers were very high, although 8 what exactly constituted high was not really clearl y defined. 9 So old ARM2 versus Tier 3 OLM and PVMRM--and 10 remember, again, that Mark Podrez' research is real ly sort of 11 based around a comparison of those aspects. He use d 12 sensitivity modeling around the 2004 MACTEC report for single 13 and cumulative source scenarios and expanded upon t hose and 14 found that at low concentrations--and now we're tal king in 15 terms of micrograms per cubic meters--ARM2, OLM, an d PVMRM 16 all predicted NO 2to NO xratios around 0.9. 17 At the higher impact levels, greater than 300 18 micrograms per cubic meter, all of the different me thods had 19 ratios between 0.2 and 0.4, and ARM2 was consistent ly a 20 little more conservative than the other two. 21 At some very high impacts, it was found that PVMRM 22 occasionally had ratios higher than ARM2, and that may have 23 been because of a formulation error that would havebeen 24 identified and will be addressed with the updated PVMRM2. 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 updating the ARM2 development report. For a 1 project that we're doing and we're seeking approvalof the 2 ARM2 method for refinement, which just happens to b e the one 3 that George was talking about in terms of the Model 4 Clearinghouse, an additional analysis sort of exten ding what 5 Mark had done in the original ARM2 research was undertaken. 6 All monitors in the United States were looked at 7 between 2001 and 2012 with a focus on monitors thatwere 8 similar to the project site, which was a rural-ish project 9 site, so some of the urban monitors were removed. The 10 resulting data set still gad more than 4,000,000 da ta points 11 and the number of observations increased as the yea rs go on. 12 You can see that in 2001 there were less than half as many as 13 there were in 2009 (sic). 14 Ultimately, ARM2 was approved. It did get through 15 the Model Clearinghouse very quickly once it got th ere, but 16 it took nearly a year to get the data and a lot of back and 17 forth with the regulating agencies to get that all put 18 together, ultimately with a minimum NO 2to NO xratio of 0.54, 19 which as it turned out is higher than the recommended for the 20 proposed default now. So if we had waited a year, we could 21 have gotten it a little lower apparently. 22 Here are some of the observed data points from 23 that research. These are color coded by groups of hours. 24 Because the hours were densely packed, it wasn't po ssible 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**  put a single dash for every hour, so the colored ho urs are 1 groups of hours. 2 And you can see that if we look at the data in 3 three year blocks, from 2001 to 2004, the data most ly fit the 4 curve, the ARM curve being the red line that goes down across 5 to the right. And there were some outlying hours above the 6 curve all the way from 100 to 600 micrograms per cubic meter. 7 Moving to the next three years, we see roughly the 8 same pattern, although the outliers tend have falle n a bit 9 farther down towards the curve. And looking at themost 10 recent four years, you see that not only have most of the 11 outliers fallen out, but the general curve now appe ars to 12 even perhaps be a little conservative compared to t he 13 predominant amount of observed hours. 14 The proposed revisions would replace the old ARM, 15 which was, again, 0.8 in the modified version of ARM2. And 16 it's not really a modification of the curve. The 17 modification is that the new ARM2 would have a defa ult of 0.5 18 instead of 0.2, which is really tied into the Tier 3 refine19 ments that use 0.5 as your standard in-stack ratio. 20 And a review of the current EPA in-stack ratio 21 database, which has 2,323 entries, show that of tho se entries 22 about 4.5 percent have in-stack ratios greater than0.5, 23 about 23 percent have those greater than 0.2, and t hen the 24 other 77 percent are below 0.2. So the 0.5 is real ly 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**  protective of just about every--or a very high perc entage of 1 the in-stack ratios that are found in the database, 95 2 percent in fact. 3 So one of the things I want to do is look at, 4 well, if I'm modeling this, what does this really mean to me? 5 So I considered a concept of compliance ranges, mea ning if I 6 get a certain NO xconcentration--or what NO xconcentration do 7 I need that's greater than the standard of 188 micr ograms per 8 cubic meter that actually would fall into a range where the 9 conversion would put me below 188 and therefore in compliance 10 when I don't consider ambient background or other s ources and 11 stuff like that. 12 So the old ARM, using the 0.8 conversion, would 13 give you a result--if your model concentration landed from 14 189 to 235, you end up with a number below 188. Th e proposed 15 ARM2 improves on that, moving the compliance range up to 376, 16 which again is an improvement over the old ARM in t hat way 17 compared to the current ARM or the beta ARM2 of 0.2 . You can 18 see that the compliance range was actually much higher, all 19 the way up to 940, because up at that point you're getting an 20 in-stack ratio of 0.2, or a conversion ratio of 0.2 , so quite 21 a difference. 22 So what are some of the issues, however? Well, 23 ARM2 sometimes provides higher results than the oldARM did 24 simply because the curve exceeds 0.8 anytime your NO xconcen- 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**  tration is greater than--or sorry, less than 149 mi crograms 1 per cubic meter. Now, you're already below the sta ndard at 2 that point, but again, that's not considering ambie nt 3 background. And if you have an ambient background that's up 4 in the range of 50 micrograms per cubic meter, this can be 5 significant. You may find compliance using ARM, bu t not find 6 it using ARM2. 7 The same problem or issue--I won't call it problem 8 necessarily--when considering SIL modeling where anNO x 9 concentration, for example, of 9.4 if you're using ARM, gets 10 you to the 7.5 SIL, whereas a NO xconcentration of 8.4 would 11 be over the SIL using ARM2 because the conversion r atio would 12 be higher than 0.8. 13 Now, you are allowed in theory to ask for a lower 14 minimum ratio with your ARM2, but there are some pr oblems 15 there that actually might make it more difficult togain 16 approval than getting in-stack ratios approved for Tier 3. 17 And the issue there is with Tier 3, you deal on a s tack by 18 stack basis. So if you have ten sources of varyingkinds, 19 you can negotiate an in-stack ratio on each of thos e sources. 20 It's unclear based on ARM2 how you would negotiate 21 a lower minimum when you may have several differentsources-- 22 one has a 0.2, one has a 0.1, one has a 0.5--differ ent 23 operating characteristics, different percentages ofthe 24 overall emissions. So it's unclear exactly where t hat goes. 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** 

Because I'm running out of time, I'm going to just 1 skip the quick summary of the Tier 3 message and goto the 2 conclusions. So again, ARM2 was originally conceived as a 3 simpler alternative to a Tier 3, but that's no long er the 4 case. That was really a replacement for the ARM me thod. 5 You have a greater compliance range than ARM did, 6 but less than the beta version does. In some cases --with 30 7 seconds to go--ARM provides better refinement or mo re 8 refinement than ARM2 did when you're modeling again st the 9 SIL. And then there are questions as to how does o ne justify 10 a lower minimum in the case of a site with a variet y of 11

sources. 12 And we see that the ambient NO 2to NO xcurve seems 13 to be decreasing, either based on less ambient ozon e or other 14 factors or maybe because we removed the urban monit ors. So 15 the question is does that need to be updated at eve ry certain 16 amount of time or perhaps a study done between an u rban curve 17 and a rural curve. And that will be it. Thank youfor your 18 time. 19 Mr. Bridgers: Rich, I was actually going to 20 give you a couple of extra seconds because of the c omputer 21
snafu. 22 (Pause.) 23 Our apologies, a technical issue with Microsoft 24 Office. It decided to make my screen twice as larg e, 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**  it's not simple to make it the same. 1 (Pause.) 2 So with the technical snafu partially fixed, Cathe 3 is going to actually talk from her slides here up t here, so 4 Cathe, the podium is yours. 5 Ms. Kalisz: Good afternoon, everyone. I'm 6 Cathe Kalisz with the American Petroleum Institute or API. 7 And this presentation provides an overview of some ongoing 8 API work that's looking at AERMOD with an alternateNO x 9 chemistry scheme, an alternate to the Tier 3 NO 2options. 10 So the chemistry scheme that we're using comes 11 from the Atmospheric Dispersion Modeling System or ADMS. 12 Some of you may be familiar with it. I think Chris 13 referenced it in one of his presentations. And it' s commonly 14 used in Europe. 15 This work was prompted by a modeling study by one 16 of our API member companies who wanted to compare t he NO 2 17 performance of the ADMS model and AERMOD. And the results of 18 that study suggested that ADMS chemistry might havebetter 19 predictive skill than the NO 2options in AERMOD, and so that 20 prompted this project. 21 So what you'll see on the slides in this 22 presentation compare--when I say the current versio n of 23 AERMOD, I'm talking about 14134 that's been coded w ith an 24 ADMS chemistry option and then we're comparing thos e to 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**  Tier 3 option. And so we will be updating these evaluations 1 to look at new AERMOD 15181 and the new PVMRM2. 2 So this is some basic information about the ADMS 3 chemistry module that we're using. The work that we've done 4
uses what's referred to as the standard ADMS module , a little 5 bit more about that in a minute. So for inputs youhave your 6 basic source emission rates, but you're also inputt ing the 7 background values for NO 2and ozone. 8 And so the model works by calculating the NO xand 9
NO 2concentrations at the receptors, and then it also 10 calculates at each receptor the weighted, by the so urce 11 contribution, mean travel time of the pollutant. And it adds 12 the background concentrations and then applies the two 13 chemical reactions that you see over the mean trave l time. 14 So with respect to chemistry, the two key 15 differences between the ADMS chemistry module and t he Tier 3 16 options are that it includes reactions for both NO ozone 17 titration and NO 2photolysis. And it also accounts for 18 chemical reaction rates. 19 I was asked by someone, you know, do you see any 20 difference in model run times with this, and I gues s this is 21 qualified that for the work we've done thus far the re's been 22 no appreciable difference in the run time. However , we 23 haven't tested it with a data set that has hundreds of 24 sources, so that may change as we do more work. 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 is just a further comparison of the ADMS and 1 the AERMOD options. We've talked about the chemist ry. One 2 other thing I'll point out, that with respect to oz one 3 entrainment, ADMS has the standard version that we' re using 4 and then there's also a dilution and entrainment op tion. So 5 the standard ADMS works like OLM, and that's what we used for 6 the work you're going to see. 7 So in our evaluations we used five data sets. 8 Everyone is probably familiar with the first three: the 9 Palaau and the Empire Abo North and South data sets . We also 10 included Wainwright. That was a small power plant on the 11 Alaskan North Slope and then Prudhoe Bay, which was a 12 drilling operation in Prudhoe Bay. 13 One adjustment that our consultant did make for 14 Empire Abo and Palaau is after looking at the observations 15 for the data decided to adjust the in-stack ratios from 0.2 16 to 0.1 because it appeared to be more representative. 17 So these next series of slides--and I tried to 18 cram a lot of information on them, given the ten mi nutes. So 19 for each one you'll see in the lower right-hand cor ner 20 there's a summary of the model versus observed resu lts for 21
AERMOD NO xand for the three NO 2options. In the right-hand 22 corner you'll see a correlation coefficient betweenthe 23
observed and modeled NO 2to NO xambient ratios and then of 24 course the Q-Q plots for NO 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** 

So if you're looking at Palaau, ADMS, and PVMRM, 1 you know, pretty similar in results. OLM has got h igher 2 predicted concentrations. If you look at the corre lation for 3 the ambient ratios, very good for PVMRM and ADMS. 4 Unfortunately, they only go downhill from here, at least for 5 the ratios. 6 Here is Empire Abo North, again, you know, all 7 three options pretty much the same. PVMRM as you g et to 8 higher concentrations is overpredicting. If you lo ok at the 9 correlation, they're all positive. ADMS is the highest one 10
there. 11 Here is Empire Abo South. And again, ADMS and OLM 12 look about the same. PVMRM is a lot higher, althou gh if you 13 look in NO 2technical support document, PVMRM2 has definitely 14 made a difference in what you'll see here; also not ed that 15 for the ratio correlation PVMRM is negative. 16 This is Wainwright. With respect to the Q-Q 17 plots, the PVMRM looks to be the best performer, al though, 18 you know, again, a negative correlation on the ambi ent ratio 19
was calculated. 20 And lastly, Prudhoe Bay. One thing I'll mention 21 is because the model was significantly underpredict ing AERMOD 22
for NO x , we're not sure, you know, how much you can compar e 23 these various options. We're not sure if this larg e 24 difference for AERMOD was due to the fact that the monitor 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 very close to the source or the drilling struct ures 1 weren't characterized, but a definitive difference. 2 Here's just a summary of the comparisons for the 3 five data sets. So for OLM, generally overpredicts the NO 2 4 concentrations, had the lowest proportion of values within a 5 factor of 2. The ratio correlations were generallypoor. 6 For PVMRM, it had the best mean NO 2concentration, 7 had a reasonably high proportion of values within afactor of 8 2. However, the ambient ratio correlations were ge nerally 9 poor, and you had--I guess it was three out of the five data 10 sets you had a negative correlation. 11 For the ADMS module, again, it generally over12 predicts the NO 2concentration. It had a reasonably high 13 proportion of values within a factor of 2. Although they 14 weren't the best, they did show the most consistent 15 performance considering the correlation for the NO 2 /NO x 16 ratios. 17 As part of the effort thus far, we also did some 18 sensitivity modeling using a single source 121⁄2 mete r stack 19 and looked at various met conditions. I've just pr ovided one 20 example here. This is for near-field NO 2concentrations, 21 stable early morning, moderate wind speeds. And yo u can see 22 in the upper graph the NO 2concentration. The ADMS and OLM 23 are practically on top of each other and PVMRM is much higher 24 predicted NO 2 . And yes, I won't even talk about the ratio 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**  part, which looks even weirder. 1 What our consultant decided to do for fun was to 2 take the inputs for this sensitivity run and put th em in 3 AERMOD 15181, and the results for PVMRM2 were simil ar. So 4 this is definitely a scenario that we'll look at inour 5 continuing work. 6 So these are the planned next steps for this work. 7 We'll be adding the ADMS chemistry code into AERMOD15181 and 8 then we'll rerun the evaluations. We'll also do some 9 additional sensitivity testing using single and mul tisource 10 scenarios. 11 We're hopeful that we'll have--be able to do some 12 evaluations using NO 2data sets that come from a WRAP study. 13 These are for drilling sites in Colorado and Alaska . These 14 are probably the first data sets we have that have much more 15 accurate emissions because for both of these studie s, there 16 were CEMS on the engines and the boiler stacks. 17 And then, lastly, a new task that--or the 18 developer is going to consider making further modif ications 19 to their standard ADMS chemistry module to perhaps use a more 20 simplified version of the ADMS dilution and entrainment 21 module, maybe drawing on some of the parameters from PVMRM2. 22 And so in closing, I would just want to note that 23 for this model development work and for the other development 24
work that we've heard about and that we'll hear abo ut during 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 conference, I think it's very important that we have a 1 process or a structure that provides for timely tes ting and 2 implementation of model improvements. 3 Mr. Bridgers: Thank you, Cathe, and thank you 4 for dealing with the technical snafu here. I will let Bart 5 identify himself, and this one should look pretty n ormal so 6 you should be able to see it, I hope. It's all you rs. 7 Mr. Brashers: Hello, everyone. I'm Bart 8 Brashers from Ramboll Environ. It used to be Envir on before 9 the recent merger. I've been the developer and keeper of the 10 MMIF code for a couple of years now, since I think just after 11 version 1 came out. And I should acknowledge my co -authors 12 here, Ralph and Jason, who are both in the audiencehere, so 13 you can go ask them questions afterwards. Here's alittle 14 bit of a show of the complex terrain that we're goi ng to talk 15 about today. 16 So switching gears completely and probably one of 17 the--maybe one of the less controversial parts of t he changes 18 are this use of prognostic or numerical weather pre diction 19 code to drive AERMOD. So I thought I would give yo u the 20 quick 30 second introduction to MMIF. 21 The Mesoscale Model Interface Program takes 22 numerical weather prediction models like the weathe r research 23 and forecasting model and its predecessor, MM5, converts 24 their output to feed dispersion models, in historic al order 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**  CALPUFF, AERMOD, and SCICHEM. We're going to talk about 1 AERMOD today. 2 MMIF supports AERMOD in three ways. You can go in 3 the direct mode or AERMOD mode. I like to think ofit as 4 what's the model you're going to run next. AERMOD mode, you 5 run WRF, you run MMIF, and it outputs the profile a nd service 6 files, the PFL and SFC files, directly and you run AERMOD and 7 you're done. 8 In AERMET mode you run MMIF and it outputs an 9 on-site data file. You don't have to use a surfacepathway 10 at all. And then you run it through AERMET and the n you run 11 AERMOD. And it also supports up here--you can bare ly see it 12 with this screen--in AERCOARE mode. It's nicely gr ayed out 13 because that's for over water use and we're not goi ng to talk 14 about that today. 15 Here's the situation. It's the Monongahela River 16 Valley in Allegheny County, southeast of Pittsburgh , 17 Pennsylvania. There are several sources of SO 2in the area. 18 Mostly they put the industrial sources near the val ley floor. 19 At Liberty High School up on the ridge on the hill 20 there is an SO 2monitor and has measured a number of SO 2 21 exceedances and NAAQS violations. So there's been a 22 nonattainment area designated and where SIP revisio n is 23 required. And Allegheny County came to us and aske d us to 24 help them out back when we were Environ. 25

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So we had already done some initial work that 1 looked like traditional AERMET with the station at Liberty, 2 which has a met station as well with the closest ai rport as 3 backup. It was not producing very accurate results , so we 4 thought we would do a model shoot-out, throw all th e models 5 that we can at them and hope for a clear winner. S o we're 6 not going to talk today about SCICHEM or CALPUFF. And again, 7 there's CALWRF, CALMET, and CALPUFF in the availabl e there. 8 But we can run the observations through AERMET and 9 into AERMOD or you can run via the WRF pathway thro ugh MMIF 10 either directly to AERMOD or through AERMET. So th at's a lot 11 of potential options. 12 So we ran WRF for them. We ran five nested 13 domains, started out with the 36 kilometer domain, which 14 almost everybody who does CMAQ or CAMxwork uses that same 15 projection, and nested down 3 to 1 ratios all the way down to 16 1.33 kilometers and 444 meters, which is the red bo x you see 17 here. The usable domain, fortunately, is the blue box, which 18 fully spans the nonattainment area in bright green and their 19

sources. 20 There are a few sources that were outside of the 21 nonattainment area. This one up here in Pittsburgh , which is 22 actually outside of the usable part of the domain, screened 23 out, so we didn't have to worry about it. 24 We ran a little pilot project for about a month. 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 looked good, so we ran a production year of one year of 1 WRF data to do the model shoot-out. And while we were doing 2 that, we kept running WRF, so we have a three year period now 3 to play with. 4 Here is the WRF terrain for that innermost 444 5 meter domain. You can see WRF for numerical reason s has to 6 smooth the terrain. But even in WRF's terrain here , you can 7 see there's places, several places along in here, where the 8 contour lines here are very close together. It's p retty 9 steep. The difference between elevation between th e valley 10 floor and the tops of these crests here is around 1 30 meters. 11 So it's not quite the Rocky Mountains, but because of the 12 short distances, it's kind of getting close to comp lex 13 terrain. 14 We can zoom in a little bit here on the two 15 meteorological sites, observation sites. There's t he Liberty 16 monitor up there on the hill and the met station is very 17 close to it. And you can--here's the regional coun ty airport 18 up there on the plateau also. And you can kind of guess by 19 the direction of the landing strips that the predominant wind 20 direction is sort of perpendicular to this valley h ere. 21 You can also see two of the sites, two of the 22 sources. And each of these square black boxes is a444 meter 23 WRF grid cell. So it's about three or so cells tha t are 24 across the flat part of the bottom of the valley an d maybe 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**  five, if you think of it from crest to crest. So I had great 1 hopes that this would resolve the terrain reasonabl y well. 2 So the key features of our approach, we started 3 out with--we put a receptor at the SO 2site and then we put 4 rings of receptors at 100 meter increments up to 50 0 meters 5 radius around it. That was both so that we could s ee if 6 there was any gradient in the area of the receptor and 7 borrowing from the kind of CMAQ and CAMxstyle model 8 evaluations, we often allow for a slight miss. Youpick a 9 receptor nearby that has a higher value and pick th e max 10 within--near the site so that you're taking an obse rvation 11 and allowing for a slight miss in space. 12 Probably the most interesting feature of our 13 approach here was that we had this valley with morethan half 14 a dozen, around ten or so, sites up and down the va lley at 15 different orientations. And rather than using one meteoro16 logical data set for all of them, we pretended, by using 17 MMIF, that each site had its own met tower. So we did a MMIF 18 extraction at each site, every one of them, and the n you run 19 AERMOD for each site and output to POSTFILEs for th e same 20 receptor set, add them up, and do your statistics a fterwards. 21 We did both hourly statistics--and again, I was 22 thinking borrowing from the kind of CMAQ style eval uations 23 where you often allow for a slight miss in time, ki nd of 24 analogous to a slight miss in space, taking the nea rest 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**  highest receptor. But rather than just missing by an hour or 1 two, we decided to take the max daily statistic bec ause 2 that's what the max is actually based on anyway. 3 And then we did the whole lot of sensitivity runs. 4 The most interesting ones that we're going to talk about 5 today are these three questions, how tall of a met tower do 6 you need? Are we going to emulate a 10 meter towerlike you 7 would find at a National Weather Service site, an a irport, 8 where the profile file just contains one or two layers. 9 Are we going to emulate a tall, multilevel tower? 10 We started out with the ten levels that are the def ault for 11 the FLM CALPUFF levels that were the default in MMI F and they 12 still are. And we subtracted a few levels, we adde d a few 13 levels, saw if that made a difference. 14 We ended up with 17 levels, kind of going back to 15 the original philosophy of MMIF, which was don't me ss with 16 the met, just pass it straight through. So we tookthe 17 native WRF levels as close as we can, all of the le vels up to 18 250 meters, and just passed them straight through. 19 We have not yet run the MMIF guidance levels, 20 which is pretending that you have a multi-instrumen ted 5 21 kilometer tall tower. That's more information; right? The 22 more information you feed AERMOD, the better it get s. 23 The next question we answered is about domain 24 resolution--I only looked at the four smallest doma ins--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**  then some talk about mixing heights. 1 But you end up with a whole lot of data. And 2 rather than going all the way though the Cox-Tikvar t 3 methodology to the final protocol to the final hot spots, I 4 looked at the original numbers. I don't know if yo u guys can 5 all read this there in back. Yeah? Okay. I got athumbs up 6 in the back row. 7 So I color coded them all. Green is good. Red 8 and blue are underprediction and overprediction in a--sort of 9 bias-like statistics. And red is bad in a--like anerror 10 style statistic. So we were hoping that one of the se would 11 pop out to be all green and we'd be all good. 12 I think that you could conclude from this that 13 there are some clear losers, but there's not any cl ear 14 winners. There's no lines here that have all green . So we 15 can look a little bit more closely at just a few ofthem 16 here--moderately legible. I was worried about this slide. 17 So here at the top line we have the observations. 18 The 99th percentile--we added some other statistics that are 19 not part of the Cox-Tikvart set, but the 99th perce ntile for 20 the year was 257 micrograms per cubic meter. Therewere five 21 exceedances. And then the rest of Cox-Tikvart stat istics--I 22 could flip it down to 2 here. A lot of people likethe 23 robust highest concentration. It was 243 microgram s per 24 cubic meter. 25

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And then the top line is traditional AERMET with 1 AERMOD, so this is using the Liberty site through t he on-site 2 pathway and the regional airport for the surface pa thway. 3 And you can see the 99th percentile is grossly unde r4 predicted. It didn't predict any NAAQS exceedances . The 5 rest of the statistics are all not horrible, but th e robust 6 highest concentration really pops out there. So yo u can't 7 say that AERMOD--traditional AERMOD didn't do parti cularly 8
well. 9 The next two lines we have MMIF in AERMET mode 10 first and then two lines of MMIF in AERMOD mode, fi rst with 11 the 10 meter tower and then with the 250 meter towe r. So if 12 you really like the coefficient determination and maybe the 13 fractional gross error and the geometric correlatio n 14 coefficient down here, then I think you can conclude that the 15 tall towers did better than the short towers. 16 But if you look at the number of--the 99th 17 percentile, it's a little bit higher with the tower s, but 18 there are more exceedances with the short--I'm sorr y. 19 There's more exceedances with AERMET than there arewith 20 AERMOD. And the towers did slightly better, but ve ry slight, 21 I think, with the 99th percentile. And down here a t the 22 robust highest concentration, the shorter towers di d better, 23 so kind of a mixed take-away here. 24 I don't think that you can say that the tall tower 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**  or the short tower did particularly better or worse , and I 1 don't think you can say that the AERMET versus AERMOD mode 2 produced very much difference. Maybe there's a sli ght 3 preference towards AERMET mode and a slight prefere nce 4
towards taller towers. 5 We can look at the Q-Q plots and don't worry about 6 the numbers there. The only thing you should know is that 7 these are in log Q-Q plots, so the factor of 2 is astraight 8 line. And you can see that traditional AERMET gros sly 9 underpredicted the high end of the concentration an d most of 10 the low end of the concentration. It's in the mid range. 11 Here are the Q-Q plots for--on the left MMIF in 12 AERMOD mode, on the right MMIF in AERMET mode. On the top is 13 the 10 meter towers and on the bottom is the 250 me ter 14 towers. Looking on the left here, the AERMOD mode did pretty 15 good. It had a little bit of a dropoff near the top. And by 16 using the tall tower, it produced worse results thr oughout 17 the whole spectrum of concentrations and actually made 18 everything a little bit worse--not horrible, but a little bit 19 worse. For AERMET mode, going from the short towerto the 20 tall tower didn't really affect most of the concent rations. 21 But up here at the high end it produced lower value s. 22 Moving on to the WRF resolution, here we have the 23 obs again at the top, traditional AERMET, the line below 24 that, and then sets of three, 444 meters, 1.3 kilometers, 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**  4 kilometers, for MMIF in AERMET mode with the shor t towers, 1 MMIF in AERMET with the tall towers, MMIF in AERMODwith the 2 short towers and MMIF in AERMOD mode with the tall towers, 3 and immediately what drops out at you is that the 4 kilometer 4 did horrible. There's lots of red in all the 4 kil ometers. 5 Mr. Bridgers: If you want to summarize--- 6 Mr. Brashers: I'll hurry it up here. So 4 7 kilometers was too close. The number of exceedance s is 8 really awesome for the 1.3 kilometer. It did very much 9 better. And the robust highest concentrations did very well 10
as well. 11 Can I actually have the 4 minutes that we got from 12 the previous speaker? This is one of the more inte resting 13 parts, I think. There's three--- 14 Mr. Bridgers: (interposing) Take two and--- 15 Mr. Brashers: (interposing) Two, okay. 16 Mr. Bridgers: ---then post it on the web. 17 Mr. Brashers: So WRF produces PBL height. 18 It's quantized. Each PBL scheme decides its own de finition 19 of PBL height. There's no common method. So MMIF 20 rediagnoses it, and then of course there's AERMET's model for 21 the next height. 22 Here's WRF on the y-axis and AERMET on the x-axis 23 and you can see the quantization there. So on the Q-Q plots 24 it's still okay, kind of a tendency for underpredic tion low 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 overprediction high. And this is for the mecha nical 1 mixing heights, general overprediction by WRF. 2 This is MMIFs and they're doing--the general shape 3 is a lot better. There's a tendency toward underpr edicts, 4 mostly because there's a cluster of points here whe re MMIF-- 5 sorry, AERMET and WRF disagree about the science ofthe 6 stability. And here is the mechanical mixing heigh ts. The 7 Q-Q plot looks great, but that's just because it's equally 8 horribly distributed down here at the bottom. You can look 9 at this afterwards, but there's very little differe nce 10 between any of it. They're all the same color; right? 11 So for the annual distribution these mixing 12 heights just didn't make very much difference. I t hink for 13 individual hours it makes a lot of difference what the mixing 14 height is, but in this case, using the different so urces of 15 mixing height didn't make much difference. 16 So conclusions for the Liberty site, MMIF and 17 AERMOD give results on par, maybe a little bit bett er, than 18 traditional AERMOD. A tall tower is not necessaril y better 19 than a short tower. Finer WRF resolution didn't ac tually 20 give us better results. The 444 meter was not bett er than 21 the 1.3. 22 Using too coarse for this situation definitely 23 resulted in poorer concentrations, lower maximum 24 concentrations. So that was too low. Using WRF, MMIF, 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**  AERMET mixing heights gave a similar statistical pe rformance 1
over an annual SO 2distribution. MMIF and AERMET and AERMOD 2 modes, we get really similar results. So the parti ng shots 3 are maybe we should look at that. 4 The MMIF guidance says that this AERMET mode and 5 AERMOD mode are the same. There are some people inthis room 6 who would really like a little bit more help in theguidance 7 to say that we could use AERMOD mode in locations, like say 8 over the water, where AERMET is not applicable. An d then we 9 should probably talk about the PBL recalc settings and maybe 10 even look a little bit more at what it does. Thankyou. 11 Mr. Bridgers: I appreciate that, Bart. Just 12 to say in passing--I'm not trying to be rude and I understand 13 typically in our conferences we let presentations run over 14 and adjust things, but just the public hearing natu re of the 15 rulemaking, so I'm trying to respect that. 16 So the last presentation before the break, Tom 17 here is going to present on some more WRF/MMIF expe riences. 18 Mr. Wickstrom: Hi, all. I'm Tom Wickstrom 19 with ERM and I am from ERM's Philadelphia, PA offic e. I'm 20 going to talk a little bit about some recent experi ence we've 21 had using WRF, kind of off the beaten path applicat ion of 22 WRF. And I'm also going to talk about MMIF, specif ically the 23 recent proposal in Appendix W. 24 So our recent experience has shown that the WRF 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 can be useful as an illustrative aid for disc ussions on 1 meteorological data representativeness as it applie s to 2 permitting applications. I'm going to give you an example of 3 a recent AERMOD application where the met data repr esenta4 tiveness discussion was really enhanced by using WRF data as 5 an illustrative tool. 6 I'm also going to talk about EPA's proposed 7 changes to Appendix W that includes the use of WRF or MM5 8 meteorological models as the source of the input me teoro9 logical data into a regulatory application of AERMO D. And 10 I'm going to ask the question that I had when I rea d Appendix 11 W: could we have used WRF/MMIF for this previous application 12 that we had and get similar model design values compared to 13 use of an off-site MET tower. 14 I'll spend a few moments here looking at our 15 application site. We have here a very wide view. You can 16 tell by the scale; that's 25 kilometers there. Butthe 17 isopleths here are colored, so anything that is ora nge, red, 18 purple, black, or yellow, that's all intermediate a nd complex 19 terrain. 20 And we have the project site there. That's a 1 21 kilometer radius drawn around the project site. Yo u can see 22 in very close proximity there's some complex terrai n, 23 particularly a purple ridge running from the southwest to 24 northeast just a few kilometers to the northwest ofthe site. 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 we also note that we have a 60 meter meteoro1 logical tower in the nearby vicinity of this site. And that 2 was very fortunate because we can see here the near est 3 National Weather Service sites and airports were co nsiderably 4 far away. We're talking about 50, 60 kilometers fo r both of 5 them to the northeast and to the southwest. Considering the 6 complex terrain and the situation, we felt that tha t would be 7 a long row to hoe to justify the use of those dista nt met 8 data sites given the setting. 9 So yes, it's difficult to justify the use of those 10 distant airports for this particular site. And the re happens 11 to be a continuously operating and maintained tall meteoro12 logical tower located just 2.8 kilometers from the 13 application site. 14 We still had a need to justify the use of that 15 tall tower despite its close proximity due to the c lose 16 terrain influences, so we decided to look at WRF toget a 17 better understanding of the local wind patterns dueto 18 complex terrain. 19 We ran WRF at a 1.3 kilometer resolution for this 20 analysis. And at the time we used one year of met data 21 because it was convenient to us at that time. It h appened to 22 be the year 2005. There's no rhyme or reason why, but it's 23 just the year that we had readily available for thi s 24 application. 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 let's start looking at some WRF outputs here. 1 These are windroses derived from WRF at each node. So 2 they're at 1.3 kilometer resolution and 1.3 kilomet er spacing 3 from each other. And these isopleths--these are th e same 4 color scheme that was in that large figure, so oran ge and 5 red, purple up at the northwest there. That's all starting 6 to get into high terrain. 7 Now, this is at the 60 meter level. We can see in 8 the central part going to the north there's low lyi ng regions 9 where the tall tower is. We see slightly lower win d speed 10 when compared to the elevated terrain. That's, youknow, 11 pretty expected. But overall we're looking at a ve ry similar 12 directional distribution of winds. 13 So if we start going up in the atmosphere in WRF, 14 now what do we see? We see the directional comparability 15 between all these modes start to really come togeth er. We 16 still see, you know, slightly higher wind speeds inthe upper 17 terrain areas as opposed to the lower, but even tha t is 18 starting to converge. And then when we zoom out an d up in 19 the atmosphere up to nearly 500 meters, now we're e ssentially 20 looking at the same windrose at each WRF node for t hat year, 21 2005. 22 So we're trying to determine what level really is 23 important to us in this application site, so we use d the 24 AERMOD debug output. We wrote a little program to compile 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**  different plume rise statistics and we grouped themby hour 1 of day. And you can see here these little symbols are 2 frequency bins. The plus and the diamond, those ar e the most 3 frequent occurrences, so generally speaking, over t he course 4 of the day, plume rise in the main source at this p roject 5 site is between 200 and maybe 320 meters. So that' s really 6 our level in the atmosphere where we need to reallyfocus on. 7 Let's quickly look at a direct comparison of the 8 tower observations for 2005 versus WRF observations --the WRF 9 generated wind data in 2005. So on the left is thetower 10 windrose and on the right is the WRF windrose. Obv iously 11 they're not the same windrose. You can see there's some 12 artifacts in the tower, particularly that northeastartifact. 13 That's probably due to drainage flow of some kind. It's not 14 well realized at the 1.3 kilometer resolution of WRF. 15 Perhaps if we went down to 444 meters, the next nes ting 16 model, we could have started to draw that out, but we didn't 17 end up doing that. 18 Regardless, the average speeds here we felt were 19 pretty comparable. The tower has an average wind s peed of 20 3.4 meters per second at this level and the WRF model is 21 generating an average wind speed of 3.7. 22 So our conclusions on the met representativeness 23 discussion where we used this WRF run to really supplement, 24 at the 240 meter level, WRF shows a consistent wind rose 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**  pattern across the study area. And we identified t hat 240 1 meter level as an important one in the application due to the 2 expected modeled plume heights that it showed in th at 3 frequency by hour of day plot. 4 Also, we can comment that the wind pattern in the 5 immediate vicinity of the tower and the applicationsite is 6 similar at 60 meters. As we saw in that previous s lide, the 7 average wind speed is slightly less at the tower si te. And 8 the tower observed wind speeds themselves are gener ally 9 biased slightly lower than WRF. 10 So our overall conclusion here was that there was 11 acceptable directional representativeness, slightlylower 12 tower wind speeds, and those wind speeds will be co nservative 13 when they are extrapolated to plume height by AERMO D. So we 14 took five years, the five most recent years of towe r data, at 15 a 10 meter and 60 meter multilevel tower. And the end result 16 was we had a successful air quality modeling analys is using 17
those data. 18 So switching gears again, with the advent of the 19 new proposal for Appendix W from July 30th or whene ver it 20 was, we wanted to take a look at actually running MMIF as 21 proposed in Appendix W for this site. And I just want to 22 note some of the language included in the proposal, 23 specifically talking about cost prohibitiveness or 24 infeasibility being a trigger for when you can use 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**  prognostic data. Let's talk a little bit about tha t. 1 For the sake or argument, if we assume that that 2 nearby tower data wasn't available, could we have u sed MMIF 3 and WRF to generate the meteorological data for AERMOD? So 4 we know we had questionable representativeness of t he distant 5 airport met data sets. And this particular applica tion 6 likely could not have accepted a 16 month or so del ay for a 7 meteorological monitoring program. 8 Now, on-site met monitoring for this site would 9 likely have included a tall tower at 60 meters, likely 100 10 meters, a SODAR, and then the time to acquire all t hat 11 instrumentation, time to construct it, time to comp ile the 12 monitoring protocol, a minimum of 12 months of actu al met 13 data that needs to be collected, and of course thatmet data 14 has to meet all the completeness requirements. 15 And there's a lot of time that has to go into a 16 met monitoring program beyond just that 12 months. Things 17 can happen over the course of the monitoring that c an delay 18 things, and SODARs are particularly susceptible to vandalism. 19 Just things like that can really ruin your day whenyou're 20 trying to collect a year's worth of met data. 21 So what we did was we executed MMIF 3.2 following 22 the EPA July 2015 guidance. What we're doing here is to take 23 a quick look, an initial impression. We're not doi ng a full 24 model evaluation. You know, we did this, you know, in 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**  weeks leading up to this conference. 1 And I just want to point out that the tower data 2 isn't site specific, but it is a high quality, mult ilevel 3 data set. It's not a National Weather Service site . So I 4 just want to point out that the data that we're loo king to 5 compare to WRF is of higher resolution than we can find at a 6 National Weather Service site because there's more than one 7 level. And the instrumentation itself is, you know , of real 8 high quality. 9 So we used 2005 again because that's what we have 10
WRF data for. And we also have tower data all the way back 11 to 2005, so we have a nice year to year comparison here. The 12 model results that I'm about to show you are based on an 13 actual application that went through permitting, bu t these 14 results themselves are for a theoretical project atthe same 15 site. 16 So here's a plot of the model design value for 17
NO 2 , and this is using WRF/MMIF data. It's very hard to see, 18 but the project site is in the southeast corner the re. And 19 the high concentrations are occurring on a complex terrain 20 ridge just to the northwest. And that's really theextent of 21 most of our elevated concentrations. And this is, you know, 22 typical complex terrain, stable conditions causing the 23 elevated concentrations. 24 We're comparing this now to the tower data for 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**  same time period. And we can see that the maximum concen1 trations are occurring at that same piece of the ri dge on the 2 right-hand side of the slide there. We can see a l ittle bit 3 more than what's realized from the WRF data along t he grid as 4 it goes off to the southwest. And the design value s--I 5 forgot to note that the previous design value for MMIF was 6 89.5 and this design value is 91.75. So we're gett ing 7 extremely similar results. 8 Let's take a little bit closer look here. We have 9 source by source at the project site how do results compare 10 from the two data sets. And I have the high first high and 11 the high 8 high design values shown. 12 So you can see that between high first high and 13 high 8 high for source 1, that's the main source. It's a 14 tall stack, you know, very high flow. All of its impacts are 15 very episodic in complex terrain. Once you get to the more 16 stable design value, there's a big step off there f or the 17 design value in the high first high, not so for theancillary 18 equipment. Those are much more stable and much mor e-- 19 extremely comparable between the two data sets. 20 But even for the main source between the two data 21 sets, we have good comparability, at least from thi s initial 22 exercise here, you know, 32 versus 35.8 micrograms per meter 23 cubed. So our initial observations seem to suggestthat 24 there's reasonable comparability between the two da ta sets. 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 our initial conclusions and some comments here, 1 we feel that utilizing WRF and MMIF as a source of meteoro2 logical data for AERMOD for this application shows similar 3 model results compared to representative multilevel 4 observation of meteorological data. 5 If no observational meteorological data were 6 available, finding representative airport data woul d have 7 been challenging. And use of WRF/MMIF as suggestedby the 8 new Appendix W could possibly have saved this proje ct in that 9 case if that nearby tall tower wasn't available. 10 So we strongly support the proposal in Appendix W 11 to allow the option of using WRF or MM5 through MMI F to 12 generate meteorological data for regulatory applica tions. 13 Mr. Bridgers: Thanks so much, Tom. As we 14 prepare to go to break, I know I cautioned earlier about not 15 approaching EPA folks to ask them a bunch of questi ons. But 16 all the speakers from this afternoon, anything thatthey 17 presented, feel free to talk with them about all th at. Just 18 don't do it with EPA folks standing right there. We live 19 around y'all around here and we work around you. 20 But seriously, the presentations will be posted--I 21 know Bart was a little rushed just because of the t ime limit, 22 but his presentation will be posted online and feelfree to 23 follow up by contacting him directly and asking que stions if 24 you have them. 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 are just past--we'll stay on schedule with 1 respect to when we come back from break, so we'll b reak now 2 until 3:35. And then we'll round out the afternoonthrough 3 5:20, so about 20 minutes, guys. 4 (A recess was taken from 3:14 p.m. to 3:37 p.m.) 5 Mr. Bridgers: As we take our seats, we now 6 have three presentations that are going to be givenin 7 succession by the AWMA, a subcommittee of that, andDavid can 8 introduce that when he gets up here. So we've allo tted 15 9 minutes for three different topics. And I'm going to let the 10 three different topics kind of run semiautonomously , but like 11 I said, with these guys, I'm still going to try to keep them 12 to their 15 minute blocks. So over the next 45 min utes we'll 13 hear from AWMA. David? 14 Mr. Long: Good afternoon. My name is 15 David Long. I am an engineer with American Electri c Power 16 and today I'm speaking to you as my role as chairma n of the 17 Atmospheric Modeling and Meteorology Committee of AWMA. 18 The Atmospheric Modeling and Meteorology Committee 19 is the technical coordinating committee for air qua lity 20 modeling and meteorology issues within AWMA. We have roughly 21 100 active members on the committee and our objecti ves for 22 our committee are to provide technical support for the annual 23 meeting, support specialty conferences and workshop s, which 24 I'll mention a little bit about later in my part ofour 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, contribute to various technical progr ams 1 sponsored by AWMA, and provide comments and review on 2 regulatory and technical issues relating to modelin g in a 3 constructive manner. 4 For working on the Appendix W revisions, we put 5 together an ad hoc review committee chaired by Geor ge Schewe 6 of Trinity. And the committee consisted of myself, Justin 7 Walters of Southern Company, who's our vice chair; Michael 8 Hammer of Lakes Environmental, who's our secretary; Pete 9 Catizone from TRC; Bob Paine from AECOM; Gale Hoffn agle from 10 TRC; Ron Petersen from CPP Wind; Ralph Morris from Ramboll 11 Environmental; Mark Garrison from ERM; Tony Schroeder from 12 Trinity; and Abhishek Bhat from Trinity. And then as part of 13 our process, we solicited comments from all the var ious--all 14 the committee members and tried to work those into our 15
comments as best we could. 16 Our topic areas we're going to be discussing are 17 general comments, which will be the area I'll be sp eaking on, 18 AERMOD, the enhancements, new algorithms, and appli cations, 19 which will be spoken about by Mark Garrison, and fi nally, 20 single source modeling for ozone and PM2.5and long range 21 transport modeling, which Gale Hoffnagle will speakto. 22 Looking at general issues, EPA has produced a lot 23 of useful information to address many challenging t asks in 24 air quality modeling. However, looking at the curr ent record 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**  as it exists today, we see some of the guidance doc uments 1 that have been placed in the docket do not yet appe ar to be 2 complete or appear to still be works in progress, a nd we're 3 not sure they completely support the final rulemaki ng. 4 Now, where we see potential incomplete modeling 5 procedures are for ozone and PM2.5guidance, the Tier 1 6 emission rate guidance--and we view that as an esse ntial 7 piece of the Tier 1 process and it doesn't appear t o be 8 available based on what our members have been able to locate 9 to this point. Some of the long-range modeling pro cedures 10 don't appear to be well defined, and some of the pr omulgation 11 of these issues could occur with future rulemaking once the 12 more complete procedures are defined. We feel thatwould 13
make a better record. 14 We also--we do think that some of the incompletely 15 defined approaches can cause problems working on pe rmit 16 modeling. You know, one of the things that was men tioned 17 earlier today is, you know, protocols are going to be much 18 more important. And one of the problems that we'vehad that 19 our members have had over the last number of years is 20 protocols can take a very, very long time to be app roved. 21 And with some of what we see as potentially open is sues in 22
the Guidelineand more Model Clearinghouse review, the 23 timing--we don't feel the timing will get better. We're very 24 concerned the timing will be worse as time goes by. 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** 

Regulatory review for protocols we feel should be 1 able to be done in a fairly limited time, but you g et into a 2 number of agencies that sometimes don't see eye on how 3 something should be done and, you know, it causes s ome 4 problems. So we would encourage EPA to try and hel p move the 5 process along. 6 Obviously with these problems we see that that 7 increases the expense for entities that are trying to get 8 through permit modeling. It's going to take more e ffort to 9 prepare the protocol and then to work it through th e review 10 process with things not maybe as well defined as th ey could 11
be. 12 You know, this increases greater--increases costs 13 and uncertainty, especially in the areas of ozone a nd PM2.5 . 14 And it potentially leads to a greater effort to def end a 15 permit that would ultimately be issued because the procedures 16 may not have been as well defined in Appendix W. 17 You know, consistency, one of the things that, 18 again, we've heard mentioned earlier today. You kn ow, we see 19 some of the proposed changes as potentially causingless 20 consistency amongst modeling activities and--becaus e it seems 21 like things may be going more to a case by case sit uation 22 instead of a more uniform modeling approach through out the 23 country. Now, the consistency issue is something t hat we've 24 seen as an effort of past guidelines. And again, l ack 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**  consistency can lead to challenges to permit and mo re 1 litigation. 2 Potentially, it could drive companies to try and 3 avoid PSD type modeling, which increases the time a nd expense 4 for a permit. And it's also potentially going to t ake a long 5 process, getting a PSD or NSR permit, and make it a n even 6 longer process, which may not necessarily be the be st 7 utilization of agency or regulated community time. 8 You know, we would also recommend to EPA in their 9 changes to Appendix W that they not take positions that cause 10 special approvals to be restricted to single source s and then 11 not make them reachable for any other purpose. 12 And we also--as we've looked at the guideline 13 proposal to this point, it appears that special app rovals 14 will be much more extensively needed for everythingbut a 15 basic demonstration. And we would encourage EPA toretain 16 the current system where the permitting authority h as more 17 discretion to approve a modeling protocol in most c ases. 18 Obviously there are going to be cases where things are going 19 to be done that are not standard within the protoco l and 20 special handling is required for those, and that's been the 21 case all along. 22 We'd also suggest that EPA consider forming an 23 independent expert model science advisory panel to advise EPA 24 in planning and review of model component changes a nd 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**  guidance on how models are applied. The focus of t his group 1 would be on model evaluation changes that are scien tifically 2 justified rather than on just simple sensitivity st udies. 3 And EPA should demonstrate that model formulation a nd 4 guidance changes will indeed result in improved model 5 performance. 6 We also would suggest that EPA move to a tiered 7 approach for model changes and updates to allow newand 8 improved modeling formulations to move into use in a more 9 expeditious and better reviewed fashion. 10 Now, the first tier would be changes to models in 11 Appendix W, which would be major changes, and this would 12 require a formal public comment process with Federal Register 13 notice and a public hearing, would include a 90 daycomment 14 period, and we'd recommend allowing a one year peri od for 15 testing and debugging of new modeling procedures wi th 16 additional comments limited to just the testing anddebugging 17 and not the whole model formulation itself. 18 Final implementation would then occur after the 19 one year period is up, including a review of the 90 day 20 comment period information and the results of the t esting and 21 debugging activities. And potentially the new tech niques 22 could be allowed to be used immediately, but subjec t to 23 change due to the testing and debugging and public comment. 24 Tier 2 would be formulation updates to Appendix 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**  models. And this would be things such as the low w ind speed 1 options, changes to downwashes affecting stacks at or above 2 GEP height, and some of the options that have been set up for 3 CALPUFF but have not always been approved in a time ly 4 fashion. 5 Now, these are more substantial than simple bug 6 fixes and should be reviewed by the public. But a Tier 2 7 change would not require a Federal Register notice or a 8 public hearing. There would be a 90 day comment pe riod, but 9 it wouldn't require the reopening of Appendix W andallowing, 10 again, a one year period for testing and debugging with 11 additional comments outside of the 90 day period limited to 12 just testing and debugging information. 13 Then final implementation would be after that one 14 year period with review of all comments and the tes ting and 15 debugging activities. Again, we'd suggest some of these 16 techniques would be available for use immediately, but again, 17 subject to change based on the results of the testi ng and 18 debugging and public comment. 19 The final tier is simple bug fixes or procedural 20 clarifications. And again, we would suggest a comment period 21 on this of 90 days, but no testing being required a nd the new 22 techniques would be available for use immediately, but 23 subject to change. 24 Now, EPA, we also feel, should allow for review 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**  alternate modeling approaches through the Clearingh ouse 1 without tying such requests to permit applications. This 2 could be a case where an entity sees an issue with the model 3 and wants to bring it to EPA's attention, but it is n't going 4 to--it isn't happening in the context of a permitti ng 5 process. And we also would encourage collaborativefield 6 experiments with EPA input. 7 As I mentioned earlier, we do--our committee is 8 responsible for specialty conferences, and we are p lanning 9 one for 2016. It's going to be our sixth specialty 10 conference on air quality modeling. It's scheduledfor 11 April 12th through 14th at the Sheraton Chapel Hillin Chapel 12 Hill, North Carolina. The call for papers is open and more 13 information on this conference is available at aqmo dels.awma. 14 org. And now I would like to invite Mark Garrison up to 15
start our talk on AERMOD. 16 Mr. Garrison: I've got 15 minutes? Thank 17 you, David. Thank you, George. I appreciate the opportunity 18 to provide some comments at this conference. I'd a lso like 19 to thank Bob Paine, Ron Petersen and Pete Catizone for 20 providing a lot of the technical content of this 21 presentation. I think I was nominated to give this 22 presentation so that the impression wouldn't come a cross that 23 this is a Bob Paine conference, but nonetheless. 24 We do provide a number of feedback and questions 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**  regarding the new algorithms and enhancements. We did 1 provide some recommendations for possible future enhancements 2 to AERMOD for EPA's consideration. We also provideobserva3 tions, comments, recommendations on various aspects of the 4 application of the AERMOD system in Appendix W. 5 There are a lot of questions in our presentation. 6 I think I'm going to have to go through it fairly quickly to 7 get through the time allotted. Listening to the pr esenta8 tions this morning and this afternoon, however, I t hink a lot 9 of the questions and issues that we raise have beenaddressed 10 and in some cases answered by others. I'm going totry to 11 sort of point this out as I go through with--as I g o through 12 this. And the committee is planning on providing a dditional 13 comments in the comment period, either additional t hings that 14 we think of or amplifications to the comments that we're 15 making today. 16 Well, 15181 incorporates, as we have heard and as 17 we know, some new algorithms including PVMRM2, LowW ind3, 18 Teriminator4--sorry, Terminator4 is not in AERMOD-- and of 19 course, buoyant line source type that has been adde d to the 20 modeling. 15181 also contains some other options, beta 21 options that have been in the model since 12345. Our 22
comments are addressed to those too. 23 I think it's fair to say that for all the 24 committee members that these are very welcome and appropriate 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**  enhancements to AERMOD, and the committee does verymuch 1 appreciate EPA's hard work in their ongoing efforts to 2 consider and incorporate changes that improve the AERMOD 3 system. And I think that reminds me, did I introdu ce myself? 4 Mark Garrison, ERM. Thank you. 5 The first topic is NO 2modeling options, on which 6 we've heard a couple of presentations already. AndI think 7 obviously ARM2 is a more realistic approach to mode ling that 8 conversion than the existing Tier 1 and Tier 2 opti ons, 9 although there might be some issues with going to ARM2 10 directly from Tier--the existing ARM, especially si nce the 11 minimum ratio recommended is 0.5. 12 The committee feels that it's likely to be much 13 too conservative for many applications, and the lan guage on 14 alternatives--this is actually a misrepresentation. That is 15 actually at 4.2.3.4(d) in the proposed Appendix W. It is 16 very long. And improvements to PVMRM, as we've hea rd 17 previously PVMRM2 addresses some of those limitatio ns and 18 issues with the previous PVMRM. 19 ARM2 is now indicated as a beta option. We've 20 learned the process of, you know, removing it from the beta 21 option has to wait for close of the comment period and EPA's 22 response. So we simply want to encourage elevationto 23 default status as quickly as possible. 24 These two comments basically ask for a little bit 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**  more guidance in terms of how to model increment co nsumption, 1 net air quality benefit analyses involving NO 2 . The bottom 2 part of this graph simply--it's very hard to read, but the 3 horizontal axis is ozone concentration. The vertic al access 4 is time to complete conversion. And the point is, I think, 5 that for some situations with very near, very closeimpacts, 6 that can be an important consideration. And the su ggestion 7 is that some consideration of the time of conversio n be 8 incorporated into the AERMOD. 9 We heard about LowWind3, and I think this issue 10 hasn't been answered very much, what LowWind3 is compared to 11 the other low wind options. And again, we kind of encourage 12 the low wind options to become regulatory default options. 13 The buoyant line source algorithm is a welcome and 14 encouraging addition to AERMOD. It allows for mode ling of 15 buoyant line sources along with more traditional so urces. 16 And we think that the current version should be tre ated as a 17 beta version due to the limited user input and limi ted user 18 experience until such time as we kind of gain some experience 19 and can provide some feedback on that. 20 This suggestion is to include test runs in the 21 BUOYLINE source algorithm to be distributed with th e AERMOD 22 system. And I think this question, it kind of is a nswered by 23 the understanding that incorporation of BLP into AE RMOD is 24 intended not to create a new model, but to simply t ake what 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**  would be predicted by BLP and put it into AERMOD. 1 It produces some sort of strange, you know, a need 2 in other words, within AERMOD to determine a Pasqui ll-Gifford 3 stability category and some other issues like that where the 4 algorithms between the two models are different. B ut I think 5 that this is one area that need--certainly needs some more 6 review and study. 7 And this is really sort of the same issue. I mean 8 the intention as I understand it and as the committ ee 9 understands it is to include what would be predicte d by BLP 10 in AERMOD so that you don't have to run two models and kind 11 of mesh the two results in a close processing step. 12 In terms of mobile sources, I think we did hear 13 that the intention is to replace CAL3QHC in its ref ined 14 version with AERMOD. The issues listed here included, you 15 know, what to do about queuing algorithms and a couple of 16 other issues--a couple of other treatments within t he mobile 17 source models. It's not clear how AERMOD will hand le those, 18 but I think they will hopefully become clearer as we learn 19 more about 15181. 20 Just a quick note on secondary PM2.5application. 21 The committee feels that possibly a reduced form mo del for 22 secondary PM2.5could be adapted for AERMOD as opposed to 23 adding a constant value at all receptors. It can e ither be 24 done through a postprocessor using a look-up table or other 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**  means of calculating a transformation rate, or prob ably even 1 more straightforward, could or should be incorporat ed into 2 AERMOD directly. 3 Several slides on background concentrations--I 4 won't dwell on these too much. I think there have been some 5 helpful discussions already today. The first pointhere, 6 that focus should be on actual emissions, not allowable. And 7 the new Table 8.1 or 8.2--I don't remember which on e it 8 is--is certainly a welcome change to how nearby sou rces are 9
modeled. 10 And I think--again, I'm not going to go through 11 each of these in detail, but the overriding point i s that 12 background concentrations should be--should not have 13 influences from nearby industrial sources that are not going 14 to interact with the source in question. It's a ve ry 15 difficult thing to accomplish, but we think that it 's 16 important to achieve that goal. I'm sort of readin g through 17
here to see--- 18 (Pause.) 19 Again, I think--I won't go through these in 20 detail, but one thing to consider I think to the la st point 21 is that the use of lower percentiles, perhaps the 5 0th 22 percentile, should be used as a reasonable and viab le option 23 to account for a true background in refined modelin g. 24 In the area of building downwash, I think 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**  committee feels that there is still some sort of lo ng1 standing questions about performance for certain si tuations, 2 including long and narrow buildings, low wind speed s, which 3 we've heard a couple of presentations about already

. 4 The issue that's been on for a while, the downwash 5 for stacks at or above GEP, is an issue that probab ly needs 6 some further review and discussion, and I think thecommittee 7 would plan to amplify on that comment in its commen ts. And 8 of course the last bullet, we do encourage EPA to s eek 9
feedback from external stakeholders. 10 There were a number of theoretical issues that 11 were raised in the comments. And I won't go through these, 12 but I think these theoretical issues in part are addressed by 13 considerations about the heat island effect in cert ain 14 buildings and the issue with long narrow buildings that the 15 committee is going to provide additional comments during the 16 comment period. 17 Equivalent building dimension approach has been 18 around for a while as well, and I think the committ ee feels 19 that it is still a viable alternative for complex b uilding 20 cases, including porous structures, streamlined structures, 21 et cetera. And that should be considered--or guida nce for, 22 you know, preparing that kind of an analysis and EB D should 23
be addressed. 24 We have heard--these last two bullets, we're heard 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 about, you know, low wind speed downwash and 1 situations where excess heat in a building or an in dustrial 2 area can cause plume liftoff, so I won't go over th ose. 3 And finally, our last topic is in terms of using 4 prognostic meteorological data in AERMOD, which we' ve already 5 heard a couple of presentations about. And I think , you 6 know, all of us feel it's an encouraging and very welcome 7 option for cases where airport representativeness i s 8 uncertain. 9 And the point is that the use of MMIF should be 10 encouraged and should eventually become a default option. I 11 understand that some guidance is currently being de veloped, 12 but I think the committee feels that it's a great a lternative 13 and should be pursued. 14 Additional testing and comparison I think may 15 reveal some areas where, you know, the use should b e 16 cautioned, and I think that's one area that we feelneeds 17 some attention, not just sort of widely apply it, b ut 18 understand the limitations. 19 And I think the--just simply the option to work 20 with the appropriate reviewing authority or agency and 21 development of a protocol as to how to do this is absolutely 22 welcome for situations where measurements are not-- in situ 23 measurements, the on-site measurements, are impract ical or 24 cost prohibitive. 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 is a specific reference to MMIF and I think 1 kind of in keeping with not referring to specific models and 2 model versions and the references in the AERMOD use rs guide. 3 The issue of land use in WRF versus land use 4 eventually in AERMET is an issue that needs some at tention 5 and study as well. WRF cells, as we heard earlier, can go as 6 low as 400 meters or so, but that is still--there i s still 7 some question as to whether that 400 meter land useis 8 representative enough for a particular application. So I 9 think the idea is that, you know, maybe have WRF th rough MMIF 10 provide wind and temperature profiles, but then useAERMET to 11 specify land use in a more detailed, site specific area. 12 We do have I think a few more slides on prognostic 13 met data. I think the first question obviously has been 14 asked and answered, and another comment on a citati on in 15 8.4.2 that might need to be reviewed and possibly c hanged. 16 We did hear--I guess Bart was saying that his 17 AERCOARE option was grayed out and it was not addre ssed 18 currently, but I think that is something that needs to be 19 considered, that the AERCOARE algorithms and approa ch might 20 be appropriate for including in AERMOD for over wat er 21 applications. The AERCOARE has been approved for a nd 22 implementation of an AERCOARE type approach would b e similar 23 to a BLP inclusion. 24 Okay, summary. I think--again, I think 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**  proposals are encouraging and reflect considerable hard work 1 by EPA and are welcome changes, welcome updates to the 2 Guideline on Air Quality Models . We anxiously await the 3 elevation to default status of several important up dates. 4 BLP is a welcome addition, much work to be done. 5 Mobile sources, some clarification is needed on thestatus of 6 AERMOD with respect to CAL3QHC and particularly howcertain 7 algorithms within those models are handled in AERMO D. 8 Background, current procedures are still very conse rvative. 9 Downwash, work is needed on long buildings, low win d speeds. 10 MMIF, the use should be encouraged. Maybe there sh ould be a 11 clearinghouse for WRF data sets in the IM, and we'r e done. 12 The next speaker is Gale Hoffnagle. I'll let you 13 introduce yourself, Gale. 14 Mr. Hoffnagle: Gale Hoffnagle from TRC. I'm 15 going to talk about single source modeling for ozon e and PM 10 16 (sic) and long range transport modeling, and my ove rall theme 17 is case by case is not guidance. 18 This modeling issue is very challenging. The 19
ozone and PM2.5is very challenging. We recognize that has 20 EPA spent a good deal of hard work to date on the p roposal 21 package. The proposed approach, while having meritand being 22 a good start, is preliminary and needs more development 23 before becoming part of this rulemaking. It's not ready for 24 prime 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** 

Currently there are no clear modeling approaches, 1 which is a significant departure from the very spec ific 2 default options specified by EPA for AERMOD and CAL PUFF 3 modeling in prior guidance. Has EPA considered--th is as one 4 of the overview items. Has EPA considered the inte raction of 5 secondary formation and Class I increments? That's a big 6 question that's unaddressed. 7 So we have a three tiered approach, a qualitative 8 waiver of modeling requirement if new emissions areless than 9 model emission rates for precursors or MERP, which is not 10 available. I don't know how to evaluate the three tiered 11 process without MERPs being available. And I don'tknow 12 whether it's going to be a separate promulgation ornot. 13 The next tier is a screening approach based upon 14 relationships between emissions and impacts, which may have a 15 reduced form model or a screening model. This tieris to be 16 appropriate for most permit applicants. How does E PA know 17 that before it's done? I don't know that. 18 The final tier is use of more sophisticated case 19 by case sophisticated photochemical modeling analys is and 20 necessary only in special situations. I don't knowhow we 21 know that before the three tiered approach is finis hed. 22 MERPs need to be specified through a proposal and 23 public comment. I guess that's a future rulemaking . This 24 will help the user community to understand what thi s tier 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**  covers. 1 The IWAQM3 near-field document states, "At this 2 time, it is not clear that a robust reduced form mo del exists 3 for either ozone or secondary PM2.5for the purposes of 4 assessing single source downwind impacts of these 5 pollutants." Well, if there isn't such a model, how are we 6 going to get a workhorse model for the second tier? I don't 7 know. I don't know. We don't know how that is andwe don't 8 how to evaluate it. 9 More specifics are needed on the application of 10 Eulerian photochemical grid models or advanced Lagr angian 11 models in future rulemaking. We need a second--"Si ngle 12 source secondary impacts are...usually highest in p roximity 13
to the source." I don't know that. Is that true? That's an 14 issue. It's been an issue. Are they long range tr ansport? 15 Are we making more stuff long downwind or are we ma king more 16 stuff right there next to the source. I'm sure it changes 17 depending upon the situation. 18 But anyway, we don't have much data within 10 19 kilometers of a source, and we run into problems wi th the 20 grid size in photochemical grid models when we get down to 21 those kind of distances. We've seen the problems a t MMIF at 22 4 kilometers and 11⁄2--or 400 meters and 11⁄2 kilometer s. A 23 focus on near-field evaluations would be helpful. We need 24
more data. 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 if peak impacts occur near the source, careful 1 attention needs to be paid to modeling near the sou rce, and 2 plume-in-grid treatment would come up for debate ag ain. 3 Plume rise and source related effects are thereforevery 4 important. Where is the plume in elevation? Whereis the 5 chemistry in elevation? How does that chemistry inelevation 6 affect ground level concentrations? Those are all issues 7 that have to be discussed. Lagrangian models avoidthis 8 problem, so such models should be seriously conside red for 9
ozone and second PM2.5modeling, especially in the workhorse 10 category, if you will. 11 Relative versus absolute predictions: EPA 12 recommends that absolute photochemical grid modelin g 13 predictions should be compared to the SILs. We don 't have a 14 SIL, but when we have a SIL for ozone I guess we'lldo that, 15 which brings up the whole question of SILs. If thePM2.5SIL 16 is under remand, when and how are we going to have an ozone 17
SIL? 18 What is the ozone SIL? Is it 1 ppb? Does the 19 ozone SIL change as the ozone standard changes on t he 1st of 20 October because that's when we know it will change. So 21 there's a whole bunch of issues there that make it difficult 22 for us to evaluate where this is all going. 23 In many PGM applications, a relative reduction 24 factor is applied to minimize model uncertainty. T hat 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**  happens in the SIP program. But in the guideline p rogram, 1 we're not allowed to make calibrations, right, so t here's a 2 big difference in the way that these models have be en run for 3
SIPs and run for the Guidelinein using them for the 4 Guideline . I think there is a pretty good reason to suspect 5 that we ought to do some calibration of PGM models if we're 6 doing regulatory analysis under the Guideline . But this is 7 sort of a, you know, absolute issue. 8 Who will determine how to run the advanced models? 9 The widespread use of the top modeling tier may be because 10 the scope of the tiers is not yet clearly defined. We think 11 that's a problem. Model users need more specificat ion of 12 which top tier model and which technical options sh ould be 13 used. That is, where's the guidance? We don't have any 14 guidance. 15 What group of experts is available to determine 16 how to run the designated model, because we always get 17 involved in the question of which switches to use? Will 18 regional modeling platforms including existing sour ce 19 databases be set up and designated for use? If so, we will 20 need to plan that carefully. 21 I can't imagine that each model, each permit 22 applicant is free to go out and create a new smoke input for 23 their PGM model. That's ridiculous. That can't happen. It 24 will make modeling for a permit a $200,000, $300,00 0 job, not 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**  good. 1 Independent peer review program: the promulgation 2 of previous major Guidelinemodel changes were preceded by an 3 independent peer review. These important modeling develop4 ment changes warrant the same level of peer review, which 5 would be subject to public review and comment. Thi s process 6 can be conducted in association with future rulemak ing, but 7 we need--I believe that EPA needs some outside guidance on 8 how these models perform, et cetera. And AWMA is o ffering 9 that that's what should happen. 10 Additional evaluation databases should also be in 11 the review. Come on, guys, we need more data. Nowthe 12 models are being asked to do things that we've neve r asked 13 them to do before and we need more data. I applaudAPI for 14 bringing some new data, EPRI bringing new data, butwe need 15 more data. And I think EPA needs to sponsor data e valuations 16 again. So as I said, this three tiered approach is not 17 ready. 18 Long range transport models, CALPUFF and others--I 19 don't understand why EPA believes that there isn't the need 20 for long range transport modeling that there was be fore, but 21 I can tell you that we have had a recession, if youdon't 22 understand. And people are not building new plants . And if 23 there's less permits being put in over the last sixor seven 24 years, that's the reason. 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** 

When we get back to putting in permits for new 1 plants as the economy gets better, these are all wi thin 300 2 kilometers of Class I area and we're going to need to do a 3 lot more of those analyses, or at least we hope we' re going 4 to get to do a lot more of those analyses. 5 CALPUFF was recommended by IWAQM in 1998, used for 6 long range transport modeling, adopted in 2003. EPA proposes 7 not to have a long range transport guideline model. The 8 reasons for this appear to be more focused on CALPU FF manage9 ment than CALPUFF performance. However, we are hop eful that 10 the management of CALPUFF can be worked out with EPA. 11 CALPUFF is used widely throughout the world. We 12 have limited chemistry in the approved version beca use EPA 13 hasn't seen fit to evaluate any improvements in CAL PUFF. So 14 version 6.42 has improved aerosol thermodynamics an d aqueous 15 phase chemistry, which should be considered by EPA. It has 16 not been considered at all. 17 States and the user community have familiar with 18 CALPUFF, and its use could be retained at least as an 19 advanced screening model. Use of CALPUFF in this c apacity 20 will also formally support the recommendations of F LAG 2010 21 and use of BART, which I think we've covered before , that 22 those are going to happen. 23 Running CALPUFF is much easier than running PGM 24 for single sources, saving applicants and states time 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**  money. We need an advanced screening model for str ingent 1 Class I SILs and recommend that EPA retain the use of CALPUFF 2 for that purpose. Failing that, if the nearest Cla ss I area 3 is well beyond 50 kilometers, but less than 300, wehave a 4 question: have you considered whether AERMOD couldbe run 5 beyond 50 kilometers as a screening tool? 6 Next, could the FLAG 2010 Q/d less than 10 waiver 7 for modeling of AQRVs also be applied to PSD increment for 8 each pollutant? There's another screen that you co uld use 9 that would help us reduce the time and effort and e nergy. 10 And in conclusion, AWMA would welcome the oppor11 tunity to work with EPA on resolving any of the iss ues 12 addressed. Details and discussion of our comments will be 13 submitted to the docket to supplement our presentat ions here. 14 And AWMA appreciates the opportunity and EPA's effo rt to 15 accommodate our request to present these comments. Thank you 16 very much. 17 Mr. Bridgers: And our appreciation to both 18 David--well, all three, David, Mark, and Gale--for their 19 comments, and we're staying on schedule. 20 So we will switch from AWMA comments--I believe 21 I've got the right presentation. Is that it? And next up, 22 Chris, I'll let you identify yourself. 23 Mr. DesAutels: Thank you. Good afternoon. My 24 name is Chris DesAutels. I work with Exponent. I' m here 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**  offer comments on behalf of Exponent. We are the developers 1 and the maintainers of the CALPUFF model. Listed h ere are 2 some other members of the Exponent team who have be en 3 involved in developing and maintaining the CALPUFF model. 4 The primary purpose of this presentation is to 5 address some concerns that have been raised about CALPUFF as 6 part of the rulemaking process. Specifically up tothis 7 point, CALPUFF has been part of the guideline model s and it 8 has been an integral part of the modeling process. "CALPUFF 9 dispersion," as stated here, "had performed well an d in a 10 reasonable manner with no apparent bias towards under or 11 overprediction, so long as the transport distance was limited 12 to less than 300 kilometers." 13
There have been several documents that are 14 included as part of the proposed regulatory docket that have 15 raised concerns about the CALPUFF modeling system. And I 16 just want to address some of these and at least ope n the 17 conversation about possible resolution of these mat ters so 18 that CALPUFF can remain as part of the available mo dels that 19 can be used and be part of the suite of models thatwill 20 allow us to implement the best science because ther e are 21 going to be needs for non-steady state modeling. T here's 22 going to be needs for long range transport modeling , complex 23 terrain. And CALPUFF is well positioned to achievethese 24 goals so long as some of these issues can be resolved 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**  all the stakeholders involved and there can be the confidence 1 developed to move it forward. 2 So there are three specific documents that are 3 part of the docket that I want to address or at lea st discuss 4 today: the preamble to the proposed rulemaking hadsome 5 specific statements and concerns raised; the supplemental 6 information for the IWAQM Phase 2 recommendations; and then 7 there was a memo on CALPUFF's ownership since 2003 8 promulgation. 9 Initially with the preamble to the proposed 10 rulemaking notice there was expressed concerns abou t the 11 management and maintenance of the model code given the 12 frequent change of ownership of the model code, andit also 13 refers to uncertainties in the development process of the 14
model. 15 Initially here I'd like to address the issues of 16 the ownership. There is some uncertainty as to whythis is a 17 significant concern despite--there have been two ch anges of 18 ownership of the CALPUFF model, but the personnel maintaining 19 the model have continued. There's been a continuou s 20 representation of the same personnel maintaining th e model. 21 So there has been continuity. 22 The model has been freely available at the same 23 web site, so there's no mystery as to what the offi cial model 24 is or where you reach it. And the model developers 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**  provided EPA with a copy of the CALPUFF updates andmain1 tained both an EPA regulatory version which incorpo rates 2 primarily bug fixes, and a separate version which 3 incorporates model enhancements. CALPUFF does meetall the 4 requirements list in section 3.1.b of the Guidelinefor an 5 EPA approved model. 6 So the question is how do ownership changes fit 7 into the structure of a guideline model or any mode l for use 8 in regulatory purposes? This is not to say that an y change 9 of ownership is problematic. It's just to point ou t that it 10 is fairly common. It happens in the industry with modeling, 11 and there's a lot of update to all models. So how are we 12 going to proceed forward if change of ownership is a signifi13 cant concern for any of the models that are address ed here 14 and are part of the future modeling suites that aregoing to 15
be used? 16 The second section of the preamble that discussed 17 CALPUFF was the change in the language for complex winds. It 18 has been removed--it has removed the use of CALPUFF 19 specifically. There is no specific technical basis really 20 provided for this change. It refers to technical i ssues, but 21 there's no specific citation of what the technical issue 22 that's being referenced at this point is. 23 And the current guidelines state that "The purpose 24 of choosing a modeling system like CALPUFF is to fu lly treat 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 time and space variations of meteorology effect s on 1 transport and dispersion." This is a necessary pro cess 2 that's going to continue to occur and it's continua lly going 3
to need to be addressed. 4 There will be need to be a model to address this, 5 so we believe that CALPUFF is still well situated t o provide 6 this service, to do this type of modeling. And we don't see 7 the reason for there to be a change in the status f or that 8 specific purpose. 9 The second document that I referenced here is the 10 supplemental information for IWAQM's Phase 2 recommendations. 11 EPA observes that CALPUFF--it has a series of speci fic 12 concerns about the technical nature of CALPUFF, some of these 13 which were mentioned earlier today. 14 EPA observed that CALPUFF does not include photo15 chemistry for modeling of SO 2 , NO 2 , sulfates, or nitrates. 16 CALPUFF has however up to this point been extensive ly used in 17 regulatory applications for Class I AQRVs, for mode ling 18 deposition of sulfur and nitrogen and for visibilit y. 19 And we believe that it can be enhanced, that there 20 can be improvements to the science and the model ofCALPUFF 21 that will allow the Lagrangian type model to intera ct with 22 grid models to ingest ambient fields of oxidants an d ammonia 23 and achieve more accurate results and achieve some of the 24 goals in a reasonable fashion that could be product ive 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**  useful going forward. 1 And we have interest in seeing that happen and 2 working to achieve that goal with EPA and any other 3 stakeholders that are interested in that possibilit y. It 4 will offer another opportunity for how to accuratel y predict 5 secondary PM2.5and will advance the science of modeling. 6 EPA states also in that document that CALPUFF 7 cannot model single source impacts on ozone. And i n general, 8 we agree that probably a full chemical grid model i s more 9 appropriate for those purposes. That's a new area, and a 10 Lagrangian model is probably not the best served--b est suited 11 for that purpose. 12 The final observation, which is mentioned a few 13 other places also, is that CALPUFF predictions are very 14 sensitive to the CALMET meteorological processor. And 15 different switch settings, different CALMET fields will 16 produce different dispersion results. 17 There are alternatives available. We've heard 18 some presentations today about using weather foreca st models 19 and MMIF in order to drive CALMET--I mean in order to drive 20 CALPUFF or other dispersion models. That is a very 21 productive and possibly a development that its timehas come. 22 In the past when CALMET was originally developed, 23 those models were not ready for providing that reso lution of 24 data. MM5 runs at that time were typically 80 kilometer 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**  resolution. We needed a tool that would ingest obs ervations 1 and available prognostic data to achieve something that was 2 realistic and useful for dispersion modeling. Now we may be 3 ready to start looking at the use prognostic models more 4 directly and we support that possibility. 5
Concerns about CALMET should be addressed and 6 looked at, and we hope to examine those closely as they 7 arise, but it shouldn't affect the status of the CALPUFF 8 because there are other options. I'd also like to point out, 9 though, that all models, especially all three dimen sional, 10 non-steady state models will be sensitive to meteor ological 11 inputs. 12 And there is going to be a lot of skill in 13 developing those accurate meteorological fields, nomatter 14 what model is in the process flow stream, whether i t's 15 CALMET, whether it's MMIF, interpreting WRF. WRF h as a 16 variety of different schemes and settings that can produce 17 very different results. And they have to be evalua ted for 18 each application to ensure that they're producing a ccurate 19 flow fields because they will also produce sensitiv ities in 20 the meteorological dispersion models that come afte r them. 21 So this isn't a problem that is exclusive to 22 CALPUFF or CALMET. It's something we're going to h ave 23 develop skill and expert judgment on going forward and have 24 procedures for identifying when we have accurate me teoro- 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**  logical fields for any dispersion model. 1 The third--the other concern identified in that 2 document was generally about evaluation studies andCALPUFF's 3 performance in various evaluation studies. A speci fically 4 cited group of evaluation studies included a couplethat have 5 been reevaluated as time passed and they were looke d into in 6 more depth. 7 And some of the concerns or poor performance that 8 was shown by CALPUFF were identified to be other is sues, 9 sometimes related to meteorological issues, some sw itch 10 settings, and specifically you're speaking about th e ETEX 11 model. And also some of those evaluations extend f ar beyond 12 what would generally be considered to be long rangetransport 13 studies. They extend well beyond 300 kilometers upto 14 several thousand kilometers. 15 So a more general recommendation about the 16 evaluation studies is that they shouldn't necessari ly stop at 17 developing a scorecard. And that's not to say thatthe 18 evaluation study that does develop a scorecard is p roblematic 19 or improper or not helpful. It's just that can't b e the 20 final step of the process. 21 There needs to be an evaluation of why models 22 didn't meet the performance criteria that they wereexpected 23 to. What happened? What went wrong? Was it poorl y 24 performing model algorithms, things that should be updated, 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**  things that should be changed and proved based on b etter and 1 more current science? Were there problems with theinput 2 data, especially meteorology, which, as we said, is a very 3 sensitive input to the dispersion models? Do you n eed more 4 meteorology, better meteorology, more accurate? Is it 5 performing correctly? 6 Were there problems with model setups? There are 7 a lot of options and switch settings that have to b e set. 8 Are there things that are just not set correctly ina given 9 evaluation? That guidance should get out to the community so 10 people know which switch setting--they're very sens itive and 11 for which applications they should be applied, or i s a limit 12 on the model formulation? Is it something that a p lume or a 13 puff or a grid model just does not handle well? 14 Those are all possibilities about why a model does 15 not meet performance goals that it might have. And 16 determining which of those possibilities or what ca used the 17 poor model performance is critical to improving themodel and 18 getting the best science out of them. 19 Additionally, the statistics that are used to 20 evaluate this model should be consistent with the g oals we 21 have for dispersion modeling so that we're measurin g the 22 correct things. So that's something to just--I know there's 23 been a lot of work on developing the statistical me asures, 24 but that's something we should always keep our eye 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** 

The final document that I wanted to address was 1 the summary of CALPUFF ownership. In addition to s tatements 2 about the changes of ownership, there was also a ci tation 3 that described "a lag in the ability for EPA to ade quately 4 understand, review and approve changes largely due to the 5 lack of an open development process." 6 We'd like to develop that open development 7 process. We believe it's important that there's co nfidence 8 in the model and that all stakeholders feel that th ey 9 understand what's included in it. We're committed and 10 willing to work with EPA to do that and we're willi ng to 11 discuss a wide range of options of how to achieve t hat goal, 12 what it would take. I'm not going to try and formu late what 13 that will be here, but that's a conversation that I think is 14 probably--it's time and needs to be done. 15 I'm going to turn now to a few brief comments 16
about AERMOD. Some of these have been well address ed. Mark 17 covered many of these points and they've also been discussed 18 today. And I think a lot of these were questions t hat--very 19 helpfully a lot were addressed this morning. I'm s ure 20 they'll continually be addressed as the rulemaking process 21 proceeds and people have more time to look at the models and 22 the recommendations come forward. 23 There were some questions about how BLP performs. 24 There's going to need to be some testing by all theparties. 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**  Is BLP in AERMOD equivalent to BLP externally? Doe s AERMOD 1 treat calm and low wind speed hours in the same man ner? 2 We have some questions also about CAL3QHC similar 3 to the ones that Mark had listed and involving nega tive 4 emission rates. And the first two points up here h ave been 5 addressed earlier this morning and that's very help ful to 6 know the future status of the beta options within AERMOD and 7 the plans for them. And that appears to be a very good 8 advancement of the science. 9 There is still concern with the potential for 10 long--for building effect about GEP stack height, which are 11 now subject to downwash, how that was evaluated andfurther 12 evaluation of that decision within AERMOD. PRIME was 13 developed using data below GEP stack height--or sta cks below 14 GEP stack heights. These circumstances are outsideof the 15 general constructs of what was evaluated during the 16 development of PRIME, so there should be more evalu ation of 17 that modeling. That concludes my remarks. Thank you. 18 Mr. Bridgers: Thank you, Chris, for those 19 remarks. And as I said off the record during the b reak, I'll 20 say on the record we do wish that Joe could be withus to be 21 in the dialogue today. 22 So I just wanted to make sure I had everything 23 right. So Mark is up next. And Mark, you do need to 24 identify yourself. 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. Garrison: Thanks, George. Thanks for the 1 opportunity again to present some comments. The th ree topics 2 that I've listed here, CALPUFF, 30 miles, and rough ness 3 pretty much deal with some issues that are currentl y 4 considered settled policy or settled guidance. 5 Of course the Appendix W proposals that we have 6 paid so much attention to recently kind of put us i n a brave 7 new world in terms of--for the modeling community i n terms of 8 a couple of topics including the use of prognostic models for 9 developing representative met data for local scale models and 10 the development of guidance and policies related tothe use 11 of chemical transport models for ozone and PM2.5on the local 12
scale. 13 I think I and probably most modelers are pretty 14 excited about these developments and look forward t o 15 proceeding down that path. As a matter of fact, as some 16 earlier presenters attested, I get choked up when I think 17 about this. But anyway, EPA might not agree with t his, but I 18 would think there's no time like the present, giventhese--in 19 light of these developments to possibly reconsider or at 20 least think about some of the settled policy and gu idance 21 issues. 22 The things I'm going to talk about today are 23 CALPUFF. As an Appendix A long range transport model, I'm 24 not going to address that particular comment. Thatcomment 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**  has been made by others. My focus is on keeping CALPUFF as a 1 candidate at least for local scale analyses. This 2 presentation is focused on that. 3 30 miles, of course, if you haven't figured out by 4 now is equal to 50 kilometers. And the discussion is about 5 using straight line, steady state models out to 50 6 kilometers. In terms of the transition from real s ort of 7 steady state conditions to non-steady state should really not 8 be a bright line with discontinuities. 9 Lagrangian models in theory can simulate this 10 transition without discontinuities. And I guess inmy view 11 there ought to be something between the true steadystate 12 local scale analysis and analyses have to look out to 50 13 kilometers. 14 The last topic is in terms of roughness length, 15 how to specify roughness length for input to AERMET . And the 16 question is, you know, roughness at the measurementor the 17 application site. 18 Well, why do we need the Lagrangian model at all? 19 I think it largely has to do with wind speeds and p lume 20 transport distances. These two circles are both 50 21 kilometers. The first one represents transport of a plume 22 from the center of this circle outward to 50 kilome ters, and 23 each of the smaller circles represent 1 hour transp ort time. 24 And this kind of stuff I think is kind 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**  intuitive to modelers, but when you look at it this way, you 1 know, it takes 13 hours, nearly 14 hours for a plume to 2 travel from the center of the circle out to 50 kilometers. 3 And the plume can experience changes in land use, c hanges in 4 winds, changes in stability, night could turn into day, day 5 could turn into night during that transport time. 6 And especially, if you have sources in that area 7 that you're modeling in conjunction with the sourcein the 8 middle of the circle, it raises issues that make mo delers 9 cringe sometimes that the time sequence is not real ly 10 correct. The plot on the right of course looks a l ittle bit 11 better at higher wind speeds, but quite often the l ow wind 12 speed cases are the controlling cases. 13 And I think, you know, it's encouraging to hear in 14 the presentations and in the proposal that, you know, to do 15 multisource analyses we should really be focusing o n areas 16 from 10 to 20 kilometers and not beyond that. But there are 17 questions that frequently are raised about sources at 18 distances greater than 20 kilometers, and it would be nice to 19 have a tool to deal with those distance ranges. 20 Again, why do we need the Lagrangian model? Well, 21 the atmosphere is a complex place and complex winds exist 22
even on the local scale. And we do know that there 's an 23 option in the guidelines to justify a Lagrangian mo del on the 24 local scale due to complex winds. It's a very diff icult 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**  process that I've tried to go through a couple of t imes 1 without success. 2 But I have some illustrations here that take a 3 look at a 1 hour event with variable winds througho ut the 4 hour. I used CALPUFF in ten minute time steps base d on 5 meteorological data that was actually collected at five 6 minute intervals. So this was sort of an unusual s ituation, 7 but not too unusual if you consider that with AERME T we could 8 theoretically develop this kind time resolution eve n with 9 airport data. And then I look at AERMOD on an hour ly average 10 time frame. 11 This is basically a theoretical source located in 12 complex terrain. The plots illustrate each ten min ute time 13 step starting with the first ten minute time step. So in the 14 lower--the newer puffs that are released from the s ource by 15 CALPUFF in green--they kind of go down in age as th e colors 16 suggest. It's kind of hard to see the colors, but I think 17 you'll get kind of the gist as we go through these. 18 The contours are sort of relative concentration 19 contours. This is the first ten minute time step, second ten 20 minute time step, third ten minute time step, fourt h ten 21 minute time step, fifth ten minute time step, and f inal ten 22 minute time step. And if you look at the hourly average wind 23 speed and direction for this generic source, this i s what 24 AERMOD would predict. 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** 

Now, absolutely this is not intended to invalidate 1 AERMOD nor is it intended to validate CALPUFF. Butit is 2 intended to kind of get across the point that it wo uld be 3 helpful to have a Lagrangian model available and an 4 Lagrangian approach for all scales, ideally one tha t 5 simulates the steady state result for the appropria te 6 settings for steady state situations and also ideal ly 7 simulates the atmospheric chemical transformation a t all 8 scales that we are looking for in the Appendix W pr oposals. 9 And I know we're going to hear later this afternoonabout 10 SCICHEM and SCIPUFF. And I think, you know, certai nly that 11 direction provides a promising direction for this. And 12 pretty much only a steady--a non-steady state modelcan 13 handle the transition from steady state to temporal 14 variations without discontinuities. 15 So pretty much the recommendation is to keep 16 CALPUFF as a candidate for local scale analyses forthe time 17 being. And as policy guidance and models are devel oped for 18 chemical transport models on a local scale, conside r--this 19 will never happen--consider reevaluating the 50 kil ometer 20 applicability range for AERMOD, and also consider e valuating 21 CALPUFF with some of the suggestions that Chris hadpossibly, 22 along with the evaluations of other models. 23 The second part of my discussion is on roughness 24 with a focus on z 0 , which is roughness. Current policy 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**  course is to specify land use characteristics for t he 1 measurement site, using AERSURFACE to determine lan d use 2 characteristics based on the data set for which it' s 3 developed, 1992 NLCD data. 4 These characteristics then inform the AERMOD 5 interface in terms of its creation of a complete pr ofile of 6 winds, temperature, and turbulence. So this presen tation 7 will--this part of the presentation will look at th ree 8 things. 9 As we all have encountered from time to time, the 10 1992 data can be out of date and sometimes badly ou t of date. 11 I'll have a brief discussion about site characteris tics 12 versus measurement location characteristics, and th en another 13 quick look at what is upwind or how do you define upwind in 14 terms of determining the surface characteristics. 15 This is an example of NLCD 92 for a power plant 16 site where most of the area is classified as eitherwater or 17 quarry, strip mines, and gravel, obviously clearly out of 18 date and incorrect. I think many of us have encoun tered this 19 before and have developed methods to essentially re do the 20 land use classification here, which is, you know, more 21 reflective of what that site actually looks like interms of 22 development and areas that are not fully developed and 23
enforested areas. 24 One of--I thought it was kind of an interesting 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**  example that Rich Hamel found in Victoria, Texas. If you're 1 looking at the site characteristics for this airpor t 2 southwest of Victoria, it might look--well, it sortof looked 3 like an airport, but then with access to Google Ear th, we 4 realized that it is no longer an airport. It has aroad 5 running through it and the runways have all been de veloped. 6 So just a word of caution in terms of using 1992 la nd use. 7 As I mentioned, the surface characteristics, 8 especially Z 0 , inform the AERMOD interface in creating a full 9 profile of winds, temperature and turbulence. If t here are 10 differences in roughness length between the airportand the 11 site--and I have yet to encounter an airport that i s a 12 perfect match for an application site--what do you do? 13 I mean, you know, one conclusion, the airport is 14 not representative enough to collect on-site data, or the 15 other option is to run AERMOD both ways with both s ets of 16 land use, which is not a very satisfying way of ans wering 17 that question, or perhaps using the site roughness provides a 18 better profile representation. 19 And of course I'll have to mention that the 20 potential for using prognostic meteorological data, wind and 21 temperature profiles, also calls for some considera tion of 22 how to characterize land use at the application sit e. 23 This is one of those hard to read slides and I 24 apologize for that, but this is what the AERMOD int erface 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**  does. It takes the surface characteristics from AE RMET. In 1 this case--in this one hour case, the wind speed wa s 0.9 2 meters per second. The airport roughness length is 0.13. 3 The site roughness length is 1.12 meters, so clearl y very 4 different. 5 And if you look at the profiles, both in terms of 6 where the mechanical mixing height is, the wind spe ed 7 profile, the temperature reading profile, and the p rofiles of 8 turbulence, they are obviously very, very different . And 9 this would lead one to the conclusion that the airp ort was 10 not representative of the site. 11 But I think just taking a step back for a minute, 12 the important thing to remember is that the only pa rameter 13 you're getting from the airport, the only measureme nt, is 14 really the wind speed. So if you can make the casethat the 15 wind speed is representative of the site, however you would 16 do that, then I think that it is pretty clear that the site 17 roughness length actually creates a better profile for 18 modeling at that site than the--than using the airp ort 19 roughness length. 20 The last thing I want to look at is sort of a 21 quick, simple look at a different way of defining upwind for 22 AERSURFACE. And this is actually recognizing that AERSURFACE 23 is not part of the formal AERMOD system, just a too l to 24 develop the appropriate surface characteristics, th 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**  approach might be one to be considered. 1 AERSURFACE--if you're looking at particular sector 2 to develop Z 0 , the sector ends in a point at the application 3 site. If you have a site where stacks and sources are 4 separated by, in some cases, several hundred meters , it might 5 be more appropriate to use kind of wedge, as you se e here, to 6 characterize upwind characteristics for that partic ular site. 7 This is the kind of thing that can be done outside 8 of AERSURFACE. The geometric weighted average, Z 0 , can be 9 calculated fairly easily outside of AERSURFACE, so just a 10 suggestion as to something to consider if a site ha s sources 11 that are not at the same point. 12 So in the brave new world, I guess the summary-- 13 the suggestions are keeping CALPUFF as an alternati ve for 14 local complex winds. And I think Tyler's presentat ion 15 indicated of course that's still an option, so it's not--the 16 mention of it doesn't mean that it's not an option. But I 17 think the suggestion is made to keep it in there as a 18 example. 19 Consider revisiting the 50 kilometer application 20 distance for AERMOD and ideally eventually substitu ting with 21 an appropriate Lagrangian model; consider allowing the use of 22 application site roughness in some situations. Usi ng WRF and 23 MMIF should be encouraged. And then, finally, you know, 24 consider and evaluate different options for determi ning land 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**  use specifications with MMIF generated wind and temperature 1 profiles. 26 seconds left. 2 Mr. Bridgers: Thank you again, Mark. We're 3 getting in the home stretch now, a couple more pres entations. 4 We're going to switch focus from CALPUFF to SCICHEM

. 5 Mr. Chowdhury: Good afternoon. My name is 6 Biswanath Chowdhury, and I'm a senior engineer at S age 7 Management, and I'm part of the team--development t eam for 8 SCIPUFF and also SCICHEM. I would like to thank yo u for the 9 opportunity to present the work on SCIPUFF. 10 So first, a lot of you know about AERMOD and 11 CALPUFF, but very few modelers here know about SCIPUFF or 12 SCICHEM, so I'll just go through the base developme nt history 13 of SCIPUFF and a description of the use of SCIPUFF. 14 So SCIPUFF is acronym for second order closure 15 integrated puff model, so as the name implies, it u ses second 16 order closure for modeling of the turbulence parame ters. And 17 it's a puff model. More specifically, it's a Gauss ian puff 18 model. To represent a concentration field we use t he sum of 19 overlapping three dimensional Gaussian puffs and westep the 20 model by solving ordinary differential equations fo r puff 21 moments. The puff moments are the mass, the centro id, and 22 the sigma. 23 This is just a brief development history of 24 SCIPUFF, and I'll just give the highlights, and it' s not 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**  comprehensive list. The development of SCIPUFF sta rted in 1 1984, and it was funded by EPRI. And in 1991 DOD u sed 2 SCIPUFF for nuclear cloud rise model, and one of th e 3 important highlights is that DOD decided to use SCI PUFF as 4 the core transport and dispersion model for HPAC, which is 5 Hazard Prediction and Assessment Capability model, so SCIPUFF 6 is the core transport model, and it has been so for --since 7 today. So a lot of our work is funded by DOD. 8 In 1998 SCIPUFF was approved by EPA as an 9 alternative model, and in 2000 EPRI funded development of 10 SCICHEM 1.0 where we put in gas phase chemistry andaqueous 11 phase chemistry in SCIPUFF so that it was named SCI CHEM. 12 Other modifications for the SCIPUFF model 13 development is that we added urban wind field modelin 2001, 14 then again in 2001 SCICHEM was included as a plume in grid 15 model for the CMAQ advanced plume treatment. I won 't go 16 through the whole list, but the PRIME was added in 2004 to 17 take into account building effects. We have WRF an d RAMS 18 support, which was added in 2011. 19 In 2012 a lot of the updates to the SCIPUFF model 20 which were not there in the SCICHEM 1.0, so EPRI de cided to 21 update the SCICHEM model, and that's when we included all the 22 updates which are made to SCIPUFF into SCICHEM 3.0. And 23 Eladio, who is the program manager for SCICHEM, he will be 24 making a presentation right after me. 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 the development team is led by Dr. Ian Sykes. 1 He is the Environmental Sciences Group manager. An d he is in 2 charge of overall model development, turbulence clo sure 3 monitoring of dispersion and concentration fluctuat ion 4 intensity. He has been the leader of the group formore than 5 30 years. 6 Similarly, Dr. Stephen Parker, he's also with the 7 group for more than 30 years. Doug Henn, he's an e xpert in 8 the meteorology section, and he has been with us mo re than 25 9 years. And I am responsible for the SCICHEM development. 10 I'm one of the lead developers, and also I do the s ource 11 estimation part of SCIPUFF, and I have also been wi th the 12 development team for more than 15 years. 13 So what are the model capabilities of SCIPUFF? 14 SCIPUFF can transport gases, liquids, or particles. It can-- 15 it includes the primary and secondary operation forliquids, 16 and it can do dynamics. For example, it can do den se gas 17 effects, and also if you have a jet or if you have a burn 18 plume, it can handle that. 19 And there are a variety of release types that it 20 can handle. The generic types are the instantaneou s and 21 continuous releases. It can have a moving release or a 22 pooled release. It can also model jet releases, wh ich can be 23 horizontal or vertical jets. It can do burn source s or stack 24
sources and also area and volume sources. 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 some of the unique characteristics of SCIPUFF 1 is that in addition to the mean concentration, eachpuff 2 carries the variance also, so this allows SCIPUFF t o take 3 into account the rambling nature of the turbulence dispersion 4 and also uncertainty in the source or in the regula rity. 5 Each puff takes its own time step based on its 6 evolution grid, so a puff which has been released f or example 7 at high momentum or buoyancy will take a smaller st ep. 8 Similarly, it has an adaptive grid for the output, so the 9 smaller puffs will have a smaller grid and the bigg er puffs 10 will have a bigger grid. 11 To properly represent the wind field, we split the 12 puffs so that we can take into account wind shear a nd other 13 effects, but when we split we get more number of pu ffs. So 14 we have a merging algorithm also so that when the p uffs grow 15 they can merge together to reduce the number of puf fs. And 16 SCIPUFF can be used for multiple scales. It has be en used 17 from laboratory scale to global scale. 18 We do the model validation using various typical 19 and experimental studies. Some of these are listedhere. We 20 have the PGT curves for short range and surface rel eases, the 21 instantaneous dispersion data from Weil, Mikkelsen, and 22 Hogstrom. We have used SCIPUFF compared with the l aboratory 23 dispersion data from Willis and Deardorff and also fluctua24 tion data from Fackrell and Robins. 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 have used SCIPUFF for continental scale field 1 experiment ANATEX, which is across North America experiment. 2 Also we have done validation with EPRI tall stack emissions 3 experiment such as the Bull Run and Kincaid experiments. 4 Some of the other tests are listed here. One of 5 them is ETEX. Eladio I think will be presenting a slide on 6 ETEX. And we have found that it performs favorablycompared 7 to other long range transport models. 8 So what are the current research and development 9 work that we're doing, and we are collaborating wit h a lot of 10 other groups. One of them is the Los Alamos Nation al Lab, 11 where SCIPUFF is being integrated with the QUIC-Urb an model 12 so that it takes into account the building effects. 13 We are working with ENSCO for chemical deposition. 14 SCIPUFF has been used as a plume in grid model for the 15 CHIMERE model, which is a European model. We are working 16 with ENVIRON to put in the gas, aerosol and aqueous phase 17 chemistry for SCICHEM. We have worked with Penn St ate 18 University group for ensemble modeling. And for so urce 19 estimation we have worked for Aerodyne, worked withAerodyne 20
and NCAR. 21 So the systems which use SCIPUFF are--SCIPUFF is 22 the core transport and dispersion model here for SC ICHEM, and 23 then the other one is the Hazard Prediction and Ass essment 24 Capability, HPAC, and the Joint Effects Model, whic h is also 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**  part of the DOD models. And then we have the MSRAM , which is 1 the Maritime Security Risk Analysis Model, and ther e are 2 slightly different flavors for different department s. 3 We have been trying to parallelize the SCIPUFF 4 code, and we have tried to use OpenMP, and as we we re saying, 5 we are working with LANL to get the QUIC-URB model integrated 6 in SCIPUFF. And other work we're trying to do is w ith 7 SCIPUFF as an inline component of WRF-ARW simulatio ns, and 8 also source attribution. 9 So we have had success with parallelizing SCIPUFF 10 in that initially the challenge is that when you ru n a 11 parallel--the code in parallel and in serial, you t end to get 12 slight differences in results. And we have set up the code 13 now so that there's hardly any difference in the co ncentra14 tion and there's very insignificant difference in t he 15 deposition and the dosage. 16 And in the QUIC-URB integration, we--the QUIC-URB 17 represents building flow and dispersion in near fie ld using 18 Lagrangian particles, and the model runs concurrent ly with a 19 continuous transfer, so once the puff grows bigger, it hands 20 over--the QUIC-URB model hands over the puffs to SC IPUFF for 21 longer range dispersion. 22 And for the WRF integration we are investigating 23 embedding SCIPUFF inside WRF-ARW so that we can runthe 24 dispersion in sync with the meteorology. And usingthis we 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**  will have direct access to the full meteorological field from 1
WRF. 2 Another area that we are working on is trying to 3 get source attribution. In this we want to tag eac h source 4 so that when we merge a puff we know that how much mass comes 5 from that source, and using that we should be able to query 6 the sampler and find out what is the contribution f rom an 7 individual source. 8 So I would like to summarize that SCIPUFF R & D is 9 ongoing in a managed environment, and the science i n SCIPUFF 10 is continuously being updated. The source of the c ore 11 transport model is public domain, and we have worke d with 12 multiple contributors to advance the capabilities. 13 There is extensive model verification and 14 validation. DOD has their own validation process. For 15 example, for defense analysis we have found that SC IPUFF was 16 underpredicting for convective cases, so we improve d the 17 SCIPUFF model to include skew turbulence and the re sults are 18 much better than what it was before. So we are als o 19 committed to the regulatory air quality community. 20 Some of the applications that SCIPUFF is currently 21 being used is for air quality permitting. It's par t of the 22 Appendix W alternative model. And also it's used f or 23 emergency response for DHS, Department of Homeland Security, 24 and DOD and Coast Guard. If there are any question s, I can 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**  send by e-mail. 1 Mr. Bridgers: Thank you, Biswanath. As I'm 2 transitioning slides and we hit the 5 o'clock hour, I know 3 that some people may be leaving today for flights t hat are 4 not going to be with us tomorrow. So if you are le aving 5 today, I do wish you safe travels and appreciate yo ur 6 participation today. 7 And also, after we end the session, because I know 8 there's going to be a mad dash for the door, I do a sk if the 9 regional modelers from the EPA would all congregatesomewhere 10 up here close to the front. I'd just like for all of us to 11 get together for a minute or two. So now we will c hange 12 presenters on SCICHEM to Eladio. 13 Mr. Knipping: Thank you, everyone, and thank 14 you, EPA, for this opportunity to speak on SCICHEM. I'm 15 Eladio Knipping and I'm with the Electric Power Res earch 16 Institute. I'd like to recognize my colleague, Nar esh Kumar, 17 who's in the room, and also the SCICHEM developmentteam, 18 particularly Biswanath, who just finished speaking, and 19 Prakash Karamchandani from Ramboll Environ. They h ave been 20 instrumental in developing the SCICHEM model. 21 As Biswanath mentioned, SCICHEM and SCIPUFF both 22 simulate the evolution of puffs in the atmosphere. These are 23 three dimensional Gaussian puffs, but the models th emselves 24 are Lagrangian models. In fact SCICHEM is a Lagran gian 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**  photochemical puff model with different options forgas and 1 aerosol chemistry, the most detailed of which are c onsistent 2 with the mechanisms found in photochemical grid models. In 3 summary, SCICHEM is also a photochemical model. 4 It is able to model the dispersion of primary 5 pollutants and the formation of secondary pollutant s. It can 6 explicitly model the conversion of NO to NO 2 . It can be used 7 to model ozone and secondary PM2.5 . It can be used for near8 source applications as well as long range transport 9 applications. There is an option to simplify the c hemistry 10 for near-source applications. This refers to the NO to NO 2 11 conversion. 12 The features of SCICHEM 3.0. Its chemistry--the 13 gas phase chemistry is based on the carbon bond 5 mechanism. 14 And the aerosol and aqueous chemistry modules are b ased on 15 CMAQ 4.7.1. So these are consistent, again, with photo16 chemical grid models. 17 The dispersion, as Biswanath had mentioned 18 earlier, incorporates the last ten years of improvements in 19 the SCIPUFF model. It can treat point, area, and v olume 20 sources and it has the PRIME building downwash algo rithm. It 21 is able to be run in a manner which should be famil iar to 22 AERMOD users. And we have also the ability to spec ify 23 background concentration fields based on photochemi cal grid 24 modeling simulations. 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 little bit of SCICHEM history. SCIPUFF, the 1 dispersion component, was evaluated with tracer exp eriments 2 and AERMOD databases, and then we developed SCICHEMin order 3 to add chemistry into SCIPUFF. And it in turn was evaluated 4 with power plant plume measurements. There were on ly 5 sporadic incremental upgrades up to 2010, at which time a 6 major upgrade effort was initiated around 2011. 7 SCICHEM was released as a public domain open 8 source beta, the first beta of which was focused onmodeling 9
one hour NO 2and SO 2 . It was released in the middle of 2013. 10 The second beta for modeling both primary and secon dary 11 impacts was released in the middle of 2014. And wh at we were 12 able to do during these beta periods was obtain ext ensive 13 user feedback from a variety of federal, local, and 14 consulting groups. 15 And the final version, SCICHEM 3.0, was released 16 on Monday, August 10th, 2015. Several of you probably got 17 spammed by me announcing the e-mail. It is locatedon the 18 Source Forge web site, sourceforge.net/projects/epr i19 dispersion. Again, it is available as a public domain, open 20
source model. 21 SCICHEM evaluations have included theoretical 22 studies and also evaluation with tracer experiments such as 23 the European Tracer Experiment--I'll show a result of that-- 24 and also the AERMOD evaluation databases. Most imp ortantly, 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 photochemical grid modeling component has been evaluated 1 with aircraft measurements, for example the TVA Cumberland 2 plume during the Southern Oxidants Studies, the Dol et Hills 3 power plant plume, which I'll show some results. 4 And ongoing, we have an evaluation with the 2013 5 SENEX measurements from the Southeast Nexus Experiments. 6 These were flights conducted by NOAA in 2013 as par t of the 7 Southeast Atmosphere Studies. And those include me asurements 8
of ozone and PM2.5 , so these will be rather exciting 9 evaluations to perform. We also have an explorator y research 10 study using measurements located at the Southeaster n Aerosol 11 Research and Characterization Study network sites. 12 On this slide I show the results of SCICHEM on the 13 left and observations on the right for long range t ransport 14 evaluation using tracer studies from the European T racer 15 Experiment in 1994. What we see is that there are consistent 16 transport of the tracers, both when comparing the p redicted 17 concentration fields with the observations. 18 Now, this result is from the Dolet Hills power 19 plant plume transects from the Northeast Texas Air Care 20 (NETAC) 2005 Air Quality Study. And what we see fo r this 21 simulation from left to right, NO x , NO y , ozone, and SO 2 . What 22 we see is that, you know, the peaks for NO y , SO 2 , and ozone 23 are all within 20 percent of observed values. We a re doing 24 rather well with simulating this plume. This is anadvanced 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**  Lagrangian photochemical model accurately simulatin g ozone. 1 For the 54 kilometer downwind transect, the plumes 2 tend to diverge a little bit from their center line s. And as 3 many other presenters have said, it's really diffic ult to get 4 the transport, you know, completely aligned. But t he plume 5 results are very consistent with the observations. And 6 again, for ozone we are simulating the production o f a 20 ppb 7 ozone peak in the observations with an advanced Lag rangian 8 photochemical model. 9 Now, one of the comments that we received during 10 the SCICHEM beta periods was that the model needed to be 11 stress tested, that we needed to be able to assure the 12 community that the model could be run for annual simulations 13 for different types of sources and in different chemical and 14 meteorological environments. 15 So the objective of our stress testing is to test 16 the robustness of the model for long term, annual applica17 tions for these range of conditions and to demonstr ate the 18 calculation of secondary impacts in Class I areas b y doing 19 so. Our hypothetical sources are a power plant, a flare with 20 highly reactive VOC emissions, and a petrochemical complex 21 plume. In the interest of time, I won't be showingresults 22 for the domains that we have modeled. I will focus on the 23 Southwest--what we're calling the Southwest Four Co rners 24 domain located in the Four Corners 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** 

For the power plant simulation--again, these are 1 hypothetical sources--we are able to simulate PM2.5values in 2 the range of .5 to 4.3 micrograms per cubic meter. Most of 3 that is due to nitrate formation in the range of 0. 4 to 4 4 micrograms and maximum PM sulfate ranges from 0.1 t o 0.4 5 micrograms per cubic meter. Our ozone, fourth high est 8 hour 6 average ozone impacts ranges, depending on location , from 3.3 7 to 8 ppb. 8 For the highly reactive VOC flares, we have PM2.5 9 impacts ranging from 0.3 to 0.6 micrograms per cubi c meter, 10 with the details following. The fourth highest 8 h our 11 average ozone impact ranges from 0.6 to 3.9 ppb, co nsistent 12 with the emissions that were used in this hypotheti cal 13 scenario. 14 And for the petrochemical complex PM impact, we 15 have also now some small amounts of secondary organ ic aerosol 16 precursor emissions, toluene and xylene. So not on ly do we 17 simulate the formation of nitrate and sulfate, but we 18 simulate a very small amount of secondary organic a erosol. 19 But we are able to simulate secondary organic aeros ol. In 20 fact we are able to simulate secondary PM formation 21 consistent with the emissions in all scenarios, andas well 22 as we can model formation of ozone consistent with the 23 emissions that were generated from these sources. 24 So in summary of the stress--let me summarize 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**  stress testing. We were able to conduct stress tes ting for 1 selected domains and source scenarios. And the ave rage--the 2 run times for these annual simulations range from 2 0 to 80 3 hours depending on the domain and source scenario. And what 4 we're finding is that the model is robust. 5 So in conclusion, SCICHEM has been thoroughly 6 evaluated throughout its history of development andshown to 7 be a robust model that can handle different sources under 8 different chemical and meteorological regimes. 9 SCICHEM has been demonstrated that it can be used 10 to simulate pollutant concentrations accurately fordifferent 11 applications such as short range SO 2simulations, short range 12
NO 2simulations, and long range ozone and primary and 13 secondary PM2.5simulations. 14 Representative run times is around 15 to 30 15 minutes for annual SO 2simulations, 20 to 40 minutes for NO 2 16 simulations, and 20 to 80 hours for annual simulati ons with 17 secondary pollutants. Let me just reiterate one mo re time: 18 an advanced Lagrangian photochemical model that cansimulate 19 ozone and secondary PM2.5 . 20 Additional details on SCICHEM can be found in the 21 following peer reviewed journal publication in addi tion to 22 the documentation included with the model. The cit ation is 23 shown on the slide. It is an open access article, so it is 24 free to download, and I will not say the actual URLbecause 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 wouldn't be nice. Thank you. 1 Mr. Bridgers: Thank you, Eladio. Eladio is 2 helping you get out the door just a little bit soon er. So we 3 have one more talk. In this one Rob Kaufmann is go ing to 4 give some comments on behalf of the NAAQS Implement ation 5 Coalition. And Rob, just to be nice, I have a background 6 slide for you. 7 Mr. Kaufmann: Oh, boy. I'm honored. 8 Mr. Bridgers: So Rob Kaufmann. 9 Mr. Kaufmann: Well, you can all read the 10 slide. I'm Rob Kaufmann and I work for Koch Indust ries, and 11 I'm here on behalf of the NAAQS Implementation Coal ition. 12 And Chet at the beginning of the day told me that s ince I go 13 last, I have as long as I want. Fortunately for yo u, I do 14 not have a 30 slide deck with embedded videos. I'mnot 15 planning to do any song and dance. 16
For the record I want to note that I am not 17 related to Andy Kaufman, so I'm not planning to sin g or lip18 synch the words to the Mighty Mouse theme. However , I think 19 it might be appropriate, if you are familiar with t he Mighty 20 Mouse them, with a couple of subtle changes, it cou ld have 21 been the theme song for this conference, "Here we c ome to 22 save the day. EPA's Appendix W fixes are on the wa y." 23 Audience member: Sing it. 24
Mr. Kaufmann: What I do have--and I'm not 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 for any comment from EPA on that, but it wo uld have 1 been good to start the day with that theme song. 2 I do have a very brief statement, and fortunately 3 or unfortunately for you, it was drafted by lawyers . I'm not 4 a modeler. I'm not an engineer. I'm not a lawyer, so bear 5 with me. For those of you who aren't familiar withthe NAAQS 6 Implementation Coalition, it's comprised of trade a ssocia7 tions, companies, and what the drafter of this call ed other 8 entities who confront challenges in the permitting and 9 operation of their facilities under increasingly st ringent 10 NAAQS. 11 And our coalition has been in regular contact with 12 EPA starting at the very highest levels, Gina McCar thy, Janet 13 McCabe, and down to the level of Chet and his team here at 14 the Office of Air Quality Planning and Standards. And we 15 have been working with them and discussing the deve lopment of 16 tools and policies and guidance to address the issu es that 17 arise as the NAAQS have been pushed beyond their limits by 18 new and more stringent air quality standards. And we hope to 19 keep that dialogue open and in fact plan to keep th at 20 dialogue open. 21 A lot of coalition members--and there are a lot of 22 coalition members in the audience, API, AISI, AFPA, NCASI-- 23 they've been investing resources and testing and mo deling 24 tools that have been provided to EPA. And in fact some 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**  those results were the basis for some of the fixes to 1 Appendix W. 2 And we really appreciate all the work that EPA has 3 done over the last couple of years. They've identi fied some 4 serious problems with the models. They've attempte d to 5 address them. However, as a coalition, we think th at some of 6 those problems still exist and have not been resolved. 7 And it's probably no surprise to you that since we 8 represent industry that it's our view that current 9 implementation policies and modeling tools continueto over10 predict and in some cases significantly overpredictemission 11 impacts, resulting in model results that do not ref lect local 12 air quality or public exposure. 13 Now, in our far distant past when NAAQS were far 14 less stringent, there was what I might call headroom that 15 would allow the overly conservative assumption of t he models, 16 especially as applied to PSD permitting, to not rea lly 17 present any significant modeling problems. 18 But as the standards have gotten tighter, the 19 conservative nature of some of these modeling tools leads to 20 the overprediction which I just referenced and coul d cause 21 states to have to incorporate overly burdensome emi ssion 22 limits in both their attainment and nonattainment S IPs. 23 The proposed changes to Appendix W and many of the 24 justifications for those changes were just released , as we 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**  all know. And coalition members are still evaluati ng them, 1 reviewing them, and testing them. Some of that tes ting has 2 been discussed at length today. 3 We are pleased to see that some of the--that based 4 on our preliminary reviews some of those changes have 5 resulted in significant improvements, but we believe that 6 there is a continued need for collaboration betweenindustry 7 and EPA as we go forward with some of those model f ixes, and 8 AWMA presentations noted that as well. So we concu r with 9 that finding. And we will be providing some more i n depth 10 comments for the record once we've had time to full y dive 11 into the Appendix W Federal Register notice. 12 In closing, in closing, we would note that 13 although EPA acknowledges that there are some insta nces 14 where, quote, the preferred air quality model may b e shown to 15 be less than reasonably acceptable, unquote, the ne w document 16 shows a preference for modeling analyses over monit oring. 17 And it is our ongoing belief that a modeling based 18 approach will increase the challenges to businesses and 19 detract from the Clear Air Act's goal of ensuring t hat 20 economic growth will occur consistent with the pres ervation 21 of existing clean air resources. And that's it. I 'm done. 22 And I guess we can adjourn with George's permission . Thank 23
you. 24 Mr. Bridgers: Thank you, Rob. Yes, actually 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 one of the next official duties that I can do. But as 1 I go through the official process of suspending forthe night 2 the conference and public hearing, a quick reminderthat we 3 do start at 8:30 in the morning. We do have ten mo re public 4 presentations before we get to any additional oral comments. 5 The only other thing I would have to say is I 6 think they're a little grouchy if you're hanging ar ound here 7 after 6 o'clock. So if you are a visitor and not a n EPA 8 employee, probably aim to be off campus in the next , you 9 know, 30 minutes or so. But again, I hope you havea 10 wonderful evening. For those that are traveling, I hope you 11 have safe travels back. I suspend the conference a nd public 12 hearing until 8:30 tomorrow morning. 13

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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 5 through 246 represent a true and accurate transcript of the proceedings held at the United St ates Environmental Protection Agency in Research Triangl e Park, North Carolina, on Wednesday, August 12, 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