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.
2

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 NO2 Tier 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 PM2.5 and 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
3

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 NOx

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
4

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
5

KAY McGOVERN & ASSOCIATES (919) 870-1600

Suite 117, 314 West Millbrook Road FAX 870-1603

Raleigh, North Carolina 27609-4306 (800) 255-7886

1 P R O C E E D I N G S 9:06 a.m.

2 Mr. Bridgers: Well, good morning, everybody,

3 and welcome to North Carolina. Thankfully the weather

4 cleared through last night. I'm going to check real quick

5 with our court reporter and make sure that we are--we're

6 clear? Okay. And we have a closed captioning service

7 online, so I'm just making sure I have a mic check with Ms.

8 Tina.

9 I am George Bridgers. I'm with the Air Quality

10 Modeling Group here with the USEPA. Hopefully most of you

11 will have seen my name along the way with the registration

12 and/or lining up the presentations. But I want to welcome

13 you here to the EPA facility and to the 11th Conference on

14 Air Quality Modeling.

15 I want to officially open the conference and that

16 of the public hearing that's related to the conference and

17 also with respect to the proposed rulemaking for the

18 revisions to the Guideline on Air Quality Models.

19 Before we have an opening remark and some other

20 remarks from Chet Wayland, I want to go through some

21 logistics real quickly about the conference and public

22 hearing and also with respect to our facility here. 

23 So it is clear, Congress in its infinite wisdom

24 back in--well, it started in '77, but then every three years

25 thereafter per Section 320 of Clean Air Act said that we have
6

KAY McGOVERN & ASSOCIATES (919) 870-1600

Suite 117, 314 West Millbrook Road FAX 870-1603

Raleigh, North Carolina 27609-4306 (800) 255-7886

1 to have a conference, a modeling conference, and that is what

2 this is. They have to be transcribed and there has to be a

3 public record.

4 In addition, this conference, the 11th Conference,

5 is also serving as the public hearing, as I said just a

6 minute ago, with respect to the proposed revisions that we

7 are hoping to make with the Guidelines on Air Quality

8 Modeling. So every presentation today that's given will be

9 part of the record. Everything that's said will be part of

10 the record.

11 Because this is a public hearing that's inter12 connected with public--or proposed rulemaking, we will not

13 have a question and answer session, so that's a little

14 different than the 10th Conference on Air Quality Modeling. 

15 And as I did when I started, I request that all speakers when

16 they come to the microphone that they identify themselves and

17 if there's any affiliation that they're connected with.

18 I am the emcee and the public hearing officer, so

19 that means I drew the very short straw upstairs, but that

20 also means if you have any questions, if you have any

21 concerns, find me. Since Tyler Fox up here and Chet Wayland

22 are my supervisors, the chain above me, if you can't find me,

23 find them.

24 But I will request, again, since we're in the

25 midst of a proposed rulemaking, that all of our other EPA
7

KAY McGOVERN & ASSOCIATES (919) 870-1600

Suite 117, 314 West Millbrook Road FAX 870-1603

Raleigh, North Carolina 27609-4306 (800) 255-7886

1 brethren--that if there are specific questions about the

2 conference or anything with the proposed rulemaking, find me

3 or Tyler or Chet, and we'll delegate the questions as

4 appropriate. But we have to be sensitive to questions that

5 come in about our proposal.

6 We have a full schedule. We always do. Those of

7 you that have been to previous conferences and workshops know

8 that I try to run a tight ship, and I think that we have

9 accommodated many of the speakers because we increased the

10 speaking time for the public presentations from 10 minutes to

11 15. And that also means that when we get to the open forum

12 or the oral comments that we will also allow for 15 minutes

13 or up to 15 minutes if there are people presenting oral

14 comments.

15 Most of you know that this is a pretty secure

16 facility. It's harder to get in here than it is to get in

17 most airports. Hopefully most of you through the

18 registration process didn't have any trouble getting in this

19 morning, but if you are leaving the foyer, the auditorium or

20 the cafeteria area here, you will need an escort here on the

21 campus if you're in Building A, B, the upper floors of C, D,

22 E, or the High Bay. So if you leave, you know you have to go

23 back through security. 

24 If you see a gentleman that's carrying a sidearm

25 and he tells you to do something, I would listen, assuming
8

KAY McGOVERN & ASSOCIATES (919) 870-1600

Suite 117, 314 West Millbrook Road FAX 870-1603

Raleigh, North Carolina 27609-4306 (800) 255-7886

1 they have some sort of badge and they actually are security. 

2 Actually, if someone is carrying a sidearm, I would just

3 listen anyway.

4 For those of you that have not been to our campus,

5 I also wanted to pass along just some information about the

6 facilities. Bathrooms, most important: you don't have to

7 wait till breaks, although it's nice if we can. If you go

8 back out the double doors here and go across the foyer,

9 there's an alcove where the elevators are. Right before you

10 get to the elevators on the left are the bathrooms.

11 Snacks and lunch: a popular question, are we

12 offering refreshments? We are. They're for pay and they're

13 across the hall at the Lakeside Café. And we're not trying

14 to support the contractors; we just can't offer anything more

15 than water that's outside the bathroom. That's typically

16 mostly free. 

17 But at any rate, across the way they have drinks,

18 coffee, some snacks during the morning and afternoon, and

19 then they do have a full lunch selection. And I saw the 

20 e-mail last week, Tyler. It was--they're having a cookout

21 day today or something, so I--just bear with them across the

22 hall.

23 But the point that I wanted to make here is that

24 we have a very full room. It looks like we're going to reach

25 standing room only shortly. So at 11:55, which is a little
9

KAY McGOVERN & ASSOCIATES (919) 870-1600

Suite 117, 314 West Millbrook Road FAX 870-1603

Raleigh, North Carolina 27609-4306 (800) 255-7886

1 before the normal lunch hour, if all 200 of us get up and go

2 across the hall and stand in line, well, you'll be standing

3 in line with 200 people. 

4 So we tried to make an hour, almost an hour and a

5 half--it's an hour and 20 minutes--lunch period so that some

6 of you may--if you're going to socialize during the lunch

7 hour or the lunch break, you may do it on the front end

8 versus the back end so we can stagger people going through. 

9 You're more than welcome to go ahead into the dining room and

10 sit down and chat while the line dies down or stay in here. 

11 And there's--you know, you can come find me. We have some

12 WiFi if you need to check e-mail.

13 But at any rate, hopefully we can get everything

14 done in the hour and 20 minute time period, but the one thing

15 I will say, at least this afternoon at 1:20 we're going to

16 get the train back on the tracks so we can get through the

17 afternoon.

18 Also--and I will not put on my vest, my safety

19 vest and my hard hat, which I do have upstairs, which is just

20 hilarious--if there is an emergency, if there's fire alarms,

21 you'll hear somebody talking on the fire alarm system. I'm

22 your point of contact too. 

23 The emergency egress for this building and for

24 this room is back up the stairs to which you came in, and

25 then there's a small parking lot just past all the
10

KAY McGOVERN & ASSOCIATES (919) 870-1600

Suite 117, 314 West Millbrook Road FAX 870-1603

Raleigh, North Carolina 27609-4306 (800) 255-7886

1 construction right at the front on the left. That's the

2 assembly area. It's technically Assembly Area 8. I think I

3 put that on the slide here.

4 But at whatever time the fire alarm--if it should

5 go off, I'll also make an announcement. Just follow me in an

6 orderly fashion. And if there's anybody that has--that needs

7 assistance, there's an area of assistance I think right

8 outside the room, but we can figure that out. But hopefully

9 we won't have that. Hopefully there will be no fire alarms

10 over the next couple of days. 

11 And the other thing is that once the emergency is

12 over, myself, since I'm the point of contact for the

13 conference, will be the one that gives the all clear after I

14 get the all clear to come back in the building.

15 I would be--well, I should give lots of recogni16 tion. It takes a team; it takes a huge team here to make

17 this happen. And so my brethren in the Air Quality Modeling

18 Group from Tyler down through Kirk, Roger--I don't know if

19 Jim is in the room yet--both Chrises, Misenis and Owen, Brian

20 Timin, and James Thurman, all have provided invaluable

21 assistance, effort, energy to make this possible today and

22 the proposed rulemaking come out the door.

23 And in addition we had a lot of help from the

24 front office, from our divisional front office. We had help

25 from OTAQ and also from all of our regional offices and our
11

KAY McGOVERN & ASSOCIATES (919) 870-1600

Suite 117, 314 West Millbrook Road FAX 870-1603

Raleigh, North Carolina 27609-4306 (800) 255-7886

1 federal partners. So for all of that, we're very

2 appreciative.

3 And with that, I think, Chet, you are up, and

4 we're two minutes ahead of schedule.

5 Mr. Wayland: Very good. Well, thanks,

6 George. Before I make a few remarks, we've got a full house

7 here. How many people think it's kind of warm in here? Are

8 you guys okay there? All right. We will see if we can get

9 the AC cranked down a little bit because this is going to be

10 a packed room and, you know, not that our speakers are full

11 of a lot of hot air, but it could get a little warm in here.

12 But I want to welcome you guys--Chet Wayland; I'm

13 the division director for the Air Quality Assessment Division

14 here in OAQPS, and the Modeling Group is under my purview in

15 my division. And I'm really excited for you guys to be here. 

16 I was telling some folks this morning, you know, a lot of

17 times when EPA puts out a rule we kind of know what the

18 comments might be coming. 

19 With this one I'm actually really excited because

20 I think we have tried to address a lot of things that folks

21 have raised over the last many years. I know we probably

22 can't address everything that everybody wanted us to address,

23 but I'm looking forward to the comments we're going to get

24 because that's how we improve upon something, a product that

25 we've already put out as a proposal.
12

KAY McGOVERN & ASSOCIATES (919) 870-1600

Suite 117, 314 West Millbrook Road FAX 870-1603

Raleigh, North Carolina 27609-4306 (800) 255-7886

1 And in this case, you know, there's been a lot of

2 collaboration already from the beginning. I think it's--I

3 was talking to Jeff Masters just before I came up here, and

4 you know, we talked about in the old days how there used to

5 be a lot of collaboration on the science, and I think we're

6 trying to get back to that. And where we are with this

7 proposal, there has been a fair amount of collaboration

8 leading up to this--this proposal between stakeholders and

9 the EPA here so that we can actually try to put the best

10 science forward in our guideline models.

11 There's a lot of people that have been involved. 

12 I know Pete Pagano at Iron and Steel, Cathe Kalisz at API--

13 those folks have all worked with us on various, you know,

14 field studies or data sets and things that we've been able to

15 use as we've gone through and tried to upgrade the model and

16 improve the Guideline. And so I want to thank you guys for

17 that contribution. 

18 I mean we're all at a place today, I think private

19 sector and public sector, where resources aren't what they

20 used to be, and so where we can work together and leverage, I

21 think we can develop a better product.

22 It is a guideline model, and as George said, this

23 is a public hearing, so we do want to get your feedback on

24 that, and we will be listening carefully obviously as we go

25 through this. But I thought it would be remiss not to thank
13

KAY McGOVERN & ASSOCIATES (919) 870-1600

Suite 117, 314 West Millbrook Road FAX 870-1603

Raleigh, North Carolina 27609-4306 (800) 255-7886

1 all of you for not only being here but for what you've

2 contributed up until this point.

3 It's been ten years since we last updated 

4 Appendix W, and that's a long time. I wasn't even in this

5 job when that was--last occurred. In fact a lot of the folks

6 in the Modeling Group weren't even in the Modeling Group when

7 that last occurred. So I think it's--it has been a long

8 time. It's been something that people have been waiting for.

9 I'm fairly optimistic. I think we have tried to

10 address a lot of the issues that were raised, but I'm also

11 very excited to see what kind of comments we're going to get

12 and what we're going to hear today as well throughout the

13 public comment period.

14 And I think we are going to try to address those

15 comments in a timely fashion and hopefully get a final rule

16 out, you know, in the time frame that we're looking for,

17 which would be within the year, because we know how much

18 people are interested in having this final and being able to

19 use it.

20 So, you know, I just wanted to thank Tyler's staff

21 and his folks. I know how much time they've put into this,

22 not only in the last, you know, two or three months getting

23 the proposal out the door, but in the last several years

24 working with many of you, the 10th Conference and other

25 meetings that we've had with state and local partners as well
14

KAY McGOVERN & ASSOCIATES (919) 870-1600

Suite 117, 314 West Millbrook Road FAX 870-1603

Raleigh, North Carolina 27609-4306 (800) 255-7886

1 as with our federal partners and our stakeholders here today.

2 It has been a long process, but I think, you know,

3 if you're going to develop something worthwhile it takes

4 time. And I think, you know, what we have today is a much

5 better product that we had ten years ago. It's a better

6 product than we had a year ago. And a lot of that is because

7 of the work that people have done. 

8 And Tyler, I just want to thank you and your

9 staff. I think they've done a tremendous job pulling the

10 proposal together, pulling these presentations together

11 today, but also, you know, of reaching out and working

12 collaboratively, and I hope we can continue to go forward and

13 do that. 

14 Obviously there are rules as part of the comment

15 period. You know, during the comment period we'll take

16 information in. We'll evaluate it. But I don't want people

17 to think that, you know, that's the end of the process. I

18 would like to continue collaboration as we go forward. 

19 Even after this is final, let's continue the

20 scientific collaboration as we move forward in the years to

21 come because, you know, science never stops. It is always

22 evolving. We're always trying to get better. And even

23 though we do regulatory actions periodically, it doesn't mean

24 that it has to stop at that point.

25 So I've been really excited and impressed with the
15

KAY McGOVERN & ASSOCIATES (919) 870-1600

Suite 117, 314 West Millbrook Road FAX 870-1603

Raleigh, North Carolina 27609-4306 (800) 255-7886

1 collaboration we've had to date, and I hope we can continue

2 that even beyond this rulemaking as we continue to improve

3 the models and make them better and better.

4 So I hope this will be a great opportunity for you

5 guys to provide your input to us. We are going to be

6 listening carefully, and I'm looking forward to it. I know

7 it's a long process and public hearings can--you don't have

8 as much time maybe as you'd like, but I appreciate--you have

9 a full comment period after this, so obviously what you say

10 today will be put into the docket. But if you submit formal

11 comments, obviously they go into the docket as well and we

12 will be addressing those comments as we go forward.

13 So with that, I just wanted to thank you guys

14 again for being here. It obviously by the crowd here shows

15 your interest in this particular proposal, and I think we

16 really understand how much this means to everybody and how

17 valuable this tool is because it's used in many, many ways.

18 The one other thing I wanted to address that we

19 have tried to address is--probably if you've read the

20 proposal you've seen it--was the petition from the Sierra

21 Club to deal with secondary formation of ozone and PM2.5 from

22 a PSD standpoint. 

23 You know, we had to deal with that kind of

24 independent of some of the collaborations we've had with you

25 guys because we were responding to a petition, but I think
16

KAY McGOVERN & ASSOCIATES (919) 870-1600

Suite 117, 314 West Millbrook Road FAX 870-1603

Raleigh, North Carolina 27609-4306 (800) 255-7886

1 we've put forward a good path there as well with a fair

2 amount of flexibility, so I'm really interested in seeing

3 comments on that. 

4 This is something new. Some of the other things

5 are improvements, but this is something kind of generally new

6 that we haven't had to really address in the past and now

7 we're forced through the petition to make sure we address it. 

8 And so I'm really curious to see what kind of feedback we get

9 on that, and to you guys, what do you think about the

10 flexibilities we've provided and so forth with that.

11 So I'm not going to drone on because I want to get

12 to the heart of the discussion and have Tyler and his folks

13 start walking through some things. And I'm real excited to

14 see your comments or hear your comments later on this morning

15 and this afternoon.

16 Again, as George said, if you have any questions,

17 you know, logistically, track George down or Tyler or I. 

18 We'll be happy to help you. Unfortunately, we can't do a lot

19 of Q and A on the package itself because this is a public

20 hearing, but we'll look forward to continuing that dialogue

21 as we go forward, if not today.

22 So, well, thank you guys very much. I appreciate

23 your being here. And with that, I am going to turn it over--

24 to you or to Tyler? Back to George. Thank you.

25 Mr. Bridgers: Perfect; thanks, Chet. Thank
17

KAY McGOVERN & ASSOCIATES (919) 870-1600

Suite 117, 314 West Millbrook Road FAX 870-1603

Raleigh, North Carolina 27609-4306 (800) 255-7886

1 you so much, Chet. So Chet yields two minutes almost to

2 Tyler Fox, so next up we have Tyler Fox, who is the Air

3 Quality Modeling Group's group leader.

4 Mr. Fox: I wanted to add my welcome to

5 everyone. I'm very excited for you all to be here. What I'm

6 going to attempt to do is provide a road map. You'll hear

7 from each of the individual members who, as Chet and George

8 indicated, have put in a lot of time and effort with you and

9 with their colleagues in getting us to this point. 

10 And so I'm really here just to provide that

11 landscape, hopefully allow you to better connect the pieces

12 and understand how they fit together and what our thinking

13 was in putting these things together.

14 So obviously we all recognize that the rule was

15 published on July 29th. We are accepting public comment for

16 90 days. We knew that there would be quite a bit of review

17 and time necessary to provide suitable review by you-all and

18 others. So that comment period goes through October 27th, so

19 even though we're hearing from you-all today, this is not the

20 end of hearing from you. This is just really the beginning. 

21 And so 70 some odd days from now, I'm sure you

22 will be busy testing code, evaluating our evaluations,

23 providing more, you know, input and feedback of great value

24 to us, as Chet said, to then get to a final rule, which we

25 anticipate within the next year, the sooner the better from
18

KAY McGOVERN & ASSOCIATES (919) 870-1600

Suite 117, 314 West Millbrook Road FAX 870-1603

Raleigh, North Carolina 27609-4306 (800) 255-7886

1 our standpoint. 

2 We don't want it to go too far and get into the

3 presidential politic season and then have it get kicked over

4 into the fall or beyond, if at all. So it is very important

5 that we get comments, that we then working with the regional

6 offices and the federal partners review those and get to a

7 final rule in a very timely manner.

8 So let me start by going through the different

9 sections and giving you this overview. Sections 1 through 3

10 we really didn't do too much to, but they are critically

11 important in terms of setting the foundation for the

12 Guideline and what we do. The introduction clearly states

13 the purpose and the applicability of the Guideline. That was

14 not altered at all.

15 The overview of model use--we pulled in a number

16 of pieces from the old Section 9 on model accuracy and

17 uncertainty related to model performance and brought that

18 forward into the discussion of suitability of models, since

19 model performance evaluation is the ultimate way in which you

20 judge the suitability of models in terms of a fit for purpose

21 type of paradigm. And so we brought those types of

22 discussions into Section 2 early on to set the stage for

23 later portions of the Guideline. And we also tried to be

24 more clear in terms of the level of sophistication of air

25 quality models and providing definitions: screening/refined,
19

KAY McGOVERN & ASSOCIATES (919) 870-1600

Suite 117, 314 West Millbrook Road FAX 870-1603

Raleigh, North Carolina 27609-4306 (800) 255-7886

1 demonstration tools, reduced form models.

2 In looking at this, we got confused ourselves with 

3 screening/refined, screening techniques, screening models,

4 screening--you know, it was just very confusing as you read

5 through it. And so we really set upon a path to be very

6 clear and very structured in how we refer to things because

7 the treatment of these models, given how we refer to them and

8 the type or the distinction that we give them, is important.

9 And it's important because in Section 3 we provide

10 the rules of the game. And let me say that these rules of

11 the game have not changed, and I don't think they've changed

12 in two decades. They've been the same for a while. 

13 Preferred models, we set out the specific

14 conditions that allows us to put a model in Appendix A, which

15 means it's a preferred model. Those criteria are the ones

16 that we adhere to in moving forward with models like AERMOD

17 and previously ISC--excuse me, and previously CALPUFF, so

18 those are clear so that the community at large knows what we

19 are holding ourselves to and what you hold us to in terms of

20 preferred models, and as you want to put a model forward what

21 those criteria are.

22 Similarly for alternative models, those conditions

23 are still the same as they have been for decades, and it

24 makes clear to the community when a preferred model is not

25 suitable, when it's not up to the task, an alternative model
20

KAY McGOVERN & ASSOCIATES (919) 870-1600

Suite 117, 314 West Millbrook Road FAX 870-1603

Raleigh, North Carolina 27609-4306 (800) 255-7886

1 can be brought forward as long as it meets certain criteria

2 and conditions and goes through a process. That process has

3 served us well for many years and will continue to serve us

4 well, and we provide very--the clarity there in Section 3.

5 And then we over the years have been using the

6 Model Clearinghouse and we've more formally codified that in

7 the Guideline, not that it's new; it's been existing as part

8 of the process for decades. We're just codifying that and

9 making it clear, and George will talk more about that in his

10 presentation.

11 The next three sections really get into the meat

12 of things where we specifically identify--having identified

13 what the criteria are for preferred models and how we

14 evaluate the suitability of models and view models in

15 general, we identify those modeling approaches for inert

16 pollutants--we give the laundry list in the Guideline, so I'm

17 just putting inert pollutants here.

18 We then have Section 5, a new section for ozone

19 and secondary PM2.5, and then a revised Section 6 that then

20 covers the outside of EPA models, guidance, approaches,

21 procedures that other federal agencies are applying in order

22 to meet Clean Air Act requirements.

23 So in Section 4 we are introducing AERSCREEN

24 formally as the screening model. We are establishing AERMOD

25 as the preferred model or reiterating it as the preferred
21

KAY McGOVERN & ASSOCIATES (919) 870-1600

Suite 117, 314 West Millbrook Road FAX 870-1603

Raleigh, North Carolina 27609-4306 (800) 255-7886

1 model. There are other preferred models in Appendix A for

2 specific situations, OCD and CTDMPLUS for complex terrain,

3 and those still exist. They're there.

4 We are proposing to remove CALINE and replace it

5 with AERMOD for mobile sources, and we have integrated BLP

6 into AERMOD, so that would mean that BLP would no longer be a

7 preferred model in Appendix A. So we're trying to streamline

8 the process, bring better science and better tools, harmonize

9 those models so that we, you know, actually have a more

10 effective and efficient approach to addressing these

11 pollutants.

12 And then specifically we went in, as most of you

13 know, and modified the multitiered approach for NO2 as it

14 relates to the ambient ratio method, given work that API has

15 done, as well as the Tier 3 methods and updated those. And

16 Chris Owen will give you more details about that.

17 In Section 5, as Chet mentioned, we really broke

18 new ground here in response to the Sierra Club petition. 

19 It's clear upon looking at the models and the techniques that

20 are available that they are suitable to address single source

21 impacts. 

22 Kirk Baker and Jim Kelly have done a great job and

23 you-all have provided all the information to the literature

24 and reports and the like that substantiate that claim and

25 that assertion. And that's an important one for us to then
22

KAY McGOVERN & ASSOCIATES (919) 870-1600

Suite 117, 314 West Millbrook Road FAX 870-1603

Raleigh, North Carolina 27609-4306 (800) 255-7886

1 move forward and say, okay, so now that the models are

2 capable, what is it that EPA would recommend and/or require

3 an applicant to do in the context of PSD.

4 So we cannot establish a preferred model or

5 technique at this point in time. Instead we're recommending

6 a two tiered approach with detailed guidance that allows the

7 applicants to work with the state and local agencies and the

8 regional offices to come up with the appropriate approach, as

9 Chet mentioned, the flexibility that we think is appropriate

10 and warranted here given the nature of the models and the

11 nature of the pollutants that we're dealing with.

12 In the preamble you'll notice that we also gave

13 some foreshadowing to EPA rules related to policy tools that

14 are used in the PSD program. Particularly we referenced

15 anticipated rulemakings and developing what we call model

16 emissions rates for precursors, or MERPs. MERPs are a good

17 thing, not a bad thing. You don't need any vaccination for

18 them.

19 And what you'll notice in the preamble is that we

20 try and provide information and in fact have put two memos

21 into the docket to try and, you know, flow chart show you how

22 the system would work with that with this two tiered

23 approach. In the PM2.5 guidance we have a three tiered

24 approach, and the first is a qualitative type of assessment.

25 What we anticipate is that the development of
23

KAY McGOVERN & ASSOCIATES (919) 870-1600

Suite 117, 314 West Millbrook Road FAX 870-1603

Raleigh, North Carolina 27609-4306 (800) 255-7886

1 these MERPs, which would establish an emissions level, that

2 if a source comes in below that level what EPA has done in

3 terms of demonstrating that level in being equivalent to the

4 SIL value or significance threshold is sufficient to meet

5 your requirements in demonstrating compliance for the

6 precursor, so you are good to go and don't have to do any

7 additional analysis.

8 What now is a second tier and then a third tier

9 would then morph into what we're calling the first tier and

10 second tier of what's in Appendix W, the first tier being

11 using existing information, modeling, reduced form models,

12 other types of information short of full scale modeling to

13 address that pollutant for that source, and then a second

14 tier, which would be full scale modeling that then Kirk's

15 guidance goes into a lot of detail in how to do that.

16 In Section 6 we clarified and worked very closely

17 with the Federal Land Management community. We have the role

18 of FLMs, the FLAG guidance, and AQRVs, specifically

19 visibility and deposition. We reference the FLAG guidance

20 and other guidance documents that the FLMs are responsible

21 for. And then we also acknowledge BOEM and the modeling of

22 OCS, the outer continental shelf modeling that goes on, as

23 well as FAA and their new tool, the AEDT tool, for air

24 quality assessments that has brought in AERMOD and also has

25 other capabilities.
24

KAY McGOVERN & ASSOCIATES (919) 870-1600

Suite 117, 314 West Millbrook Road FAX 870-1603

Raleigh, North Carolina 27609-4306 (800) 255-7886

1 One thing that I wanted to clarify because we've

2 gotten a lot of questions and it's clear that in the preamble

3 we didn't provide as clear an explanation as perhaps we

4 should have, so we're likely going to put a memo to the

5 docket along these lines, which is we're doing two things. 

6 One is we're updating the regulatory version from 14134 to

7 15181 to address several bug fixes. And Roger is going to go

8 through that to be clear about what goes into now the new

9 regulatory version.

10 At the same time, as part of this proposal, we are

11 recommending as part of the proposal use of specific data

12 options for public comment that then upon final rulemaking we

13 would codify and make as part of the regulatory default. 

14 So I know a lot of people are saying, "Wait a

15 minute. Why aren't these things part of the regulatory

16 default now?" Well, we're in a proposed rulemaking. They

17 won't get codified until we go through the public comment

18 process and then upon final rule, we'll bring in those

19 aspects, those elements that we're getting comment on, and

20 make those part of the regulatory default model.

21 That's why these options have remained in beta

22 form in the current version, 15181, to allow your testing and

23 evaluation of those techniques. So I know there was some

24 almost disappointment in the proposal, but I just want to

25 make sure everybody is clear. We couldn't make them
25

KAY McGOVERN & ASSOCIATES (919) 870-1600

Suite 117, 314 West Millbrook Road FAX 870-1603

Raleigh, North Carolina 27609-4306 (800) 255-7886

1 regulatory default. That would preempt the whole process. 

2 So we're going through the process, and at the end of the

3 process with your input we would expect to then codify those

4 in a final version of AERMOD.

5 We'll likely allow for some of these options to

6 remain as beta to facilitate continued testing and evolution

7 of things, but again, the whole process is one that would end

8 up with a regulatory default that would reflect those

9 changes, so hopefully that helps clear the air on that.

10 Also in terms of long range transport assessments,

11 I just wanted to reiterate that we're not--we no longer

12 contain language in Appendix W requiring the use of CALPUFF

13 or any other Lagrangian model for long range transport

14 assessments. 

15 Based on work that James Thurman and Chris Owen

16 have done, based on a variety of source and sector scenarios

17 from the AERMOD Implementation Workgroup, we did very

18 detailed modeling that allowed us to come to the

19 determination and for your comment and input that we feel

20 that near-field modeling is sufficient in doing your NAAQS

21 compliance demonstration. So we do not consider a long range

22 transport assessment necessary for inert pollutants beyond 50

23 kilometers or thereabout. So we're reducing the burden on

24 the community in terms of doing those assessments.

25 Now, we do recognize that long range transport
26

KAY McGOVERN & ASSOCIATES (919) 870-1600

Suite 117, 314 West Millbrook Road FAX 870-1603

Raleigh, North Carolina 27609-4306 (800) 255-7886

1 assessments may be necessary for a limited number of

2 situations for PSD increment, especially Class I increment. 

3 And so we've allowed for a screening approach. 

4 Therefore, even though CALPUFF is not a preferred

5 model, it can be used as a screening technique along with any

6 other Lagrangian model, which are the typical models used in

7 this context, to, again, sequence through a multistep

8 screening with input from the regional office if you get to

9 that point. So it warrants the appropriate model when and

10 where necessary. And given our interactions with the

11 regional offices, I think they can count collectively on one

12 hand the number of instances in which a detailed PSD

13 increment analysis or cumulative analysis was done. 

14 So we really felt that the need had been

15 diminished, especially when you start factoring in once you

16 comply with the NAAQS in the near field, the long--the far

17 field impacts are far less. So we're reducing the onus and

18 the burden on the community of conducting those types of

19 analyses.

20 And then we ended with Sections 7 through 9 in

21 terms of how to inform and apply the models. So Section 7

22 had a lot of scrubbing. There still are specific

23 recommendations for dispersion models that you might not find

24 elsewhere and that are important to remind the community in

25 the context of Appendix W, but we removed a lot of details
27

KAY McGOVERN & ASSOCIATES (919) 870-1600

Suite 117, 314 West Millbrook Road FAX 870-1603

Raleigh, North Carolina 27609-4306 (800) 255-7886

1 that were seemingly there because AERMOD in 2005 was new and

2 we wanted to err on the side of providing more information.

3 I think after ten years a lot of that is not

4 necessary in Appendix W. It's more appropriate in other

5 documentation. And so we focused on certain critical areas

6 of informing the model, and in particular dispersion models,

7 for the community to understand and better appreciate and

8 engage with us on.

9 And then in Section 8 we did do a lot of work in

10 terms of looking at the model input data. You'll hear from

11 George later that the modeling domain we are limiting. We've

12 mentioned over and over again the overly conservative

13 aspects, particularly of the resource manual, and so that

14 will end with this Appendix W. The modeling domain will be

15 no more than 50 kilometers for NAAQS, and that's--I mean

16 that's in there.

17 We also talk about modeling domains for SIP

18 demonstrations for ozone and PM2.5, and we have very much

19 tried to distinguish PSD and single source assessments versus

20 SIP demonstrations for control strategy purposes and ozone

21 and secondary PM. So we're trying to be very clear.

22 On source data we've clearly outlined that nearby

23 sources for the most part we would prefer that they be

24 captured in terms of their impacts and contributions through

25 ambient monitoring data, and if they need to be explicitly
28

KAY McGOVERN & ASSOCIATES (919) 870-1600

Suite 117, 314 West Millbrook Road FAX 870-1603

Raleigh, North Carolina 27609-4306 (800) 255-7886

1 modeled, they can be modeled with actual emissions. Tables

2 8-1 and 8-2 have been modified appropriately and accordingly.

3 And in terms of background concentrations, we try

4 and more clearly lay out the construct of single source--

5 isolated single source situations and multisource situations

6 such that you're putting together more representative, more

7 appropriate characterizations of contribution from the

8 different sources and not overly conservative ones. And so

9 we've tried very much to remedy that situation.

10 And in terms of meteorological data, you'll hear

11 from James in terms of bringing in prognostic information. 

12 You know, we've got difficulty and we know the meteorological

13 inputs are critically important, so we want to have flexi14 bility in terms of bringing in more representative data, and

15 the prognostic data allow us that opportunity.

16 And so we've been talking about this since the 8th

17 Modeling Conference, I believe, and now finally it's a

18 reality. And thanks to the hard work of James, Chris, and a

19 number of other folks in the community, bringing those

20 prognostic data and sharing them for use in dispersion models

21 as they are for photochemical and other models is a great

22 advancement.

23 And then finally we end with the regulatory

24 application of models, very strong emphasis on modeling

25 protocols, and then provide a very clear description, much
29

KAY McGOVERN & ASSOCIATES (919) 870-1600

Suite 117, 314 West Millbrook Road FAX 870-1603

Raleigh, North Carolina 27609-4306 (800) 255-7886

1 clearer than I think we've had in the past, of the multistage

2 approach to demonstrating compliance, the single source

3 assessment of oneself vis-à-vis a significance threshold and

4 then a cumulative impact assessment and evaluation of whether

5 or not you are contributing significantly to a potential

6 violation or a model violation and how that process works.

7 So we go through the whole process and end with--

8 you know, once you know the rules of the game, once you know

9 what models to apply and how to apply them, then the context

10 in which you know you do that in your compliance demon11 stration. And we end with the use of measured data in lieu

12 of model estimates, not changed too much, but we're still

13 struggling with examples and situations that evidence this

14 type of approach.

15 So this flexibility is still there. How it will

16 be put into practice is still an outstanding question, and we

17 would very much welcome input and thoughts from you-all if

18 you have situations that you think are evidence of that type

19 of approach.

20 So I don't know long I went, but thank you very

21 much. And now all the detailed presentations will allow you

22 to better understand each section and change.

23 Mr. Bridgers: Actually, Tyler, I've got a new

24 tool for our 101s in my yearly reviews right here.

25 Mr. Fox: It won't work. You always talk
30

KAY McGOVERN & ASSOCIATES (919) 870-1600

Suite 117, 314 West Millbrook Road FAX 870-1603

Raleigh, North Carolina 27609-4306 (800) 255-7886

1 too long.

2 Mr. Bridgers: Oh, oh, right; that was last

3 night. I want to make two quick announcements, just kind of

4 roaming around the room. I realize that we are full on

5 seats. There's actually still some seats in this front row

6 up here, and there's a row right up here that during the

7 break I'll pull these seats forward so there's a little more

8 flexibility, but there's probably, I don't know, maybe as

9 much as a dozen seats up here and we'll see during the break

10 if we can get a few more. But we had over 260 seats in the

11 room, and so we'll accommodate that.

12 And the other thing is I do note that the screen

13 is sort of low and I know some in the back can't see

14 everything. I was going to make this announcement later. 

15 All the presentations that are given today and tomorrow are

16 going to be posted on the web, but there's an Easter egg, if

17 people know what Easter eggs are. It's actually already

18 posted on the web. 

19 If you go to our 11th Modeling Conference page,

20 which most of you will know, and scroll down to the agenda

21 and click on it, I have embedded links for all the talks. 

22 And so Roger's talk that he's getting ready to give is there. 

23 So if you have WiFi and you can't see from the back and you

24 can get to our 11th page and you can click through, you can

25 get to the presentations. All these presentations will also
31

KAY McGOVERN & ASSOCIATES (919) 870-1600

Suite 117, 314 West Millbrook Road FAX 870-1603

Raleigh, North Carolina 27609-4306 (800) 255-7886

1 get loaded to the docket, as I said earlier.

2 So I will call Roger Brode to the podium. And

3 Roger is going to give two talks. The first talk is

4 specifically aimed at the regulatory update that we just made

5 with AERMOD version 15181, and then we'll switch and have a

6 separate presentation that will talk about the proposed

7 options. 

8 So hopefully there's a good distinction here

9 between our regulatory release and what the proposed options

10 are in the revised version of AERMOD along the lines of what

11 Tyler gave a primer on just a minute ago. So Roger?

12 Mr. Brode: Thank you, George. So again, 

13 I'll talk about the update to the regulatory options within

14 AERMOD that were just basically bug fixes. In the next talk

15 we'll talk about some of the proposed beta options and what

16 we've been doing there.

17 So the regulatory version of AERMOD and AERMET has

18 been updated to version 15181, which corresponds with June

19 30, 2015. And they include several bug fixes for AERMOD and

20 AERMET, which I'll kind of go over highlights of that next. 

21 We've also incorporated some proposed enhancements to the

22 non-default/beta options which are going to be discussed in

23 the next presentation. And these updates are documented in

24 Model Change Bulletin 11 for AERMOD and MCB6 for AERMET.

25 So one of the key bug fixes that's been sort of
32

KAY McGOVERN & ASSOCIATES (919) 870-1600

Suite 117, 314 West Millbrook Road FAX 870-1603

Raleigh, North Carolina 27609-4306 (800) 255-7886

1 out there for a while but hardly ever reared its head, but

2 did not that long ago, something we've identified and

3 addressed in the AERMOD Implementation Guide, which is that

4 if you have a relatively tall stack in a relatively small

5 urban area--relative is a relative term, but we've noticed

6 that some unrealistically high concentrations due to the way

7 plume rise is calculated--there's sort of an unrealistic

8 limit on plume rise--may show up.

9 And this has been addressed in the AERMOD

10 Implementation Guide quite a few years ago, which sort of

11 suggested those sources may be better treated as rural with

12 some adequate justification. And again, this is an issue

13 that didn't come up very often, but did not too long ago from

14 Region 5, the state of Michigan in fact.

15 So the new version has addressed that as a

16 formulation bug fix, and the approach that we used sort of

17 emulates the penetrated plume algorithm that's used under

18 convective conditions. And the next slide is going to give

19 an example of a tall stack with--an urban area with 55,000

20 population, and it will show the before and after.

21 So the before on the left, the red curve is the

22 urban curve and the blue curve is rural. Again, that was

23 before. And the next slide, after, it shows a very, very

24 significant, about a factor of 10 higher with urban option

25 for that source over the rural. And then the right slide
33

KAY McGOVERN & ASSOCIATES (919) 870-1600

Suite 117, 314 West Millbrook Road FAX 870-1603

Raleigh, North Carolina 27609-4306 (800) 255-7886

1 shows, you know, that they're in much better agreement, so

2 much more reasonable from what you would expect.

3 We don't have a lot of data to evaluate this, but

4 this was the case, and the new concentrations with the urban

5 option show much better agreement with nearby monitors in

6 that case, which is in the Detroit area.

7 So in terms of bug fixes again, there weren't that

8 many, but there was a issue that showed up with the POINTCAP

9 beta option for capped stacks and determined that if you use

10 POINTCAP with the no stack-tip downwash option, you could get

11 some erroneous results because the POINTCAP option itself

12 takes care of how stack-tip downwash would be treated.

13 We also corrected an issue with the emission rate

14 being modified for area, line or open pit sources in some

15 cases with the FASTAREA or FASTALL option. And there are

16 some pretty anomalous results that had shown up in some cases

17 there. We believe those have been fixed now.

18 And another issue that had been brought up a while

19 back, and I don't have the details here, but there was an

20 issue if the wind is blowing nearly perpendicular to an area

21 source or a line source, an elongated area source, some very

22 anomalous results showed up there. And it turned out that

23 one of the tolerance levels in the area source algorithm was

24 a bit too splat, so we tightened that and that seemed to

25 clarify that--clean up that issue.
34

KAY McGOVERN & ASSOCIATES (919) 870-1600

Suite 117, 314 West Millbrook Road FAX 870-1603

Raleigh, North Carolina 27609-4306 (800) 255-7886

1 So there are a number of subroutines related to

2 the PVMRM option, one of the beta options for modeling NO2. 

3 And basically a lot of it focused on the penetrated source

4 contribution and did a more explicit treatment of the

5 vertical and horizontal dimensions of the contributing

6 sources for that penetrated plume component. And that turned

7 out to show up with some importance in the New Mexico Empire

8 Abo evaluation database.

9 We also modified the determination of NOx

10 concentrations to account separately for the horizontal plume

11 component and the terrain responding plume component. So

12 there are some aspects of the overall general formulation of

13 AERMOD that have been incorporated more fully within the

14 PVMRM algorithm for NO2.

15 Continuing on bug fixes, there are some issues

16 that showed up with the use of the DAYRANGE keyword where you

17 could specify a range of days to process for individual days,

18 and those could be specified either as a month/day or as a

19 Julian day. And it turned out there were some issues if you

20 define those day range inputs for a leap year versus a non21 leap year. That wasn't being handled properly, so that's

22 been taken care of and those issues, as far as we know, were

23 resolved with this update.

24 In terms of AERMET bug fixes, there weren't that

25 many, but we did make some changes to the ADJ_U* option in
35

KAY McGOVERN & ASSOCIATES (919) 870-1600

Suite 117, 314 West Millbrook Road FAX 870-1603

Raleigh, North Carolina 27609-4306 (800) 255-7886

1 AERMET that's used without the Bulk Richardson Number method. 

2 And we made some modifications basically to be more

3 consistent with that original paper by Venkatram and Qian, or

4 Qian and Venkatram. 

5 And in the process we also noticed a bug with the

6 Bulk Richardson Number option in AERMET where the calculation

7 of the CDN was incorrectly using Z0, or Z2 over Z0 instead of

8 ZREF over Z0. Those are the bug fixes, so I yield some of my

9 time to the next slide.

10 So this talk will be talking about the proposed

11 updates to the AERMOD Modeling System. So I begin with

12 version 12345, which is a version I wish we could have kept

13 forever because it's so easy to remember, but we incorporated

14 some non-default/beta options to address concerns regarding

15 model overpredictions during stable/low wind conditions.

16 And we have to acknowledge the contributions of

17 API, which funded a low wind study that AECOM conducted back

18 in 2010, I guess, and that certainly helped move the ball

19 along to address this issue. So there is non-default options

20 that include the LOW_WIND option in AERMOD and the ADJ_U*

21 option in AERMET. And so the proposed updates to these

22 options are discussed here. 

23 So there are going to be some additional updates

24 to the regulatory options that are being proposed, including

25 a buoyant line source option, which was mentioned earlier, to
36

KAY McGOVERN & ASSOCIATES (919) 870-1600

Suite 117, 314 West Millbrook Road FAX 870-1603

Raleigh, North Carolina 27609-4306 (800) 255-7886

1 eliminate the need hopefully for the BLP model as a separate

2 preferred model. And also we're going to address the capped

3 and horizontal stack issue. And these updates are going to

4 be subject to public review and comment and then would be

5 codified as part of the final rule action as appropriate, as

6 Tyler mentioned.

7 So again, beginning with 12345, AERMOD included

8 these low wind beta options. Prior to 15181 AERMOD included

9 a LowWind1 option and a LowWind2 option. And basically this

10 just addresses the minimum value of sigma-v, the horizontal

11 dispersion coefficient.

12 So the LowWind1 option that we put in there

13 eliminates the horizontal meander component that's a part of

14 AERMOD and also increases the minimum sigma-v from the

15 default, currently at 0.2 meters per second, to 0.5 meters

16 per second.

17 We also added a LowWind2 option that retains the

18 meander--horizontal meander component, but put an upper limit

19 of 0.95 on that, and then also increased the minimum value of

20 sigma-v from 0.2 to 0.3. And these two options are mutually

21 exclusive. You can't try to use both of them at the same

22 time. So that was part of the initial foray into these beta

23 options for addressing low wind issues.

24 So with version 15181 we've added a new low wind

25 option, and for the lack of a better option we call it
37

KAY McGOVERN & ASSOCIATES (919) 870-1600

Suite 117, 314 West Millbrook Road FAX 870-1603

Raleigh, North Carolina 27609-4306 (800) 255-7886

1 LowWind3. So this is sort of kind of a hybrid of the two in

2 a way. It increased the minimum sigma-v from 0.2 to 0.3,

3 which is consistent with the LowWind2 option, but eliminates

4 upwind dispersion, which is consistent sort of with the

5 LowWind1 option, but it doesn't just ignore meander.

6 So the LowWind3 option uses the effective sigma-y

7 value that would replicate the centerline concentration

8 accounting for meander, but then it puts a limit on the

9 lateral spread at 5 sigma-y off the centerline, so it's

10 similar to the FASTALL option that's in AERMOD that sort of

11 does that, so it replicates centerline concentration--or the

12 contribution of meander to the centerline concentration, but

13 just enhances the spread but doesn't include full upwind

14 dispersion.

15 So we proposed in the notice of proposed

16 rulemaking that the LowWind3 option be incorporated into the

17 regulatory version of AERMOD, while the LowWind1 and LowWind2

18 options are still available for testing purposes.

19 So the other key beta option that we've been

20 dealing with especially focused on the low wind issues is the

21 beta ADJ_U* option in AERMET. And there's an ADJ_U* option

22 in AERMET that's associated with the Bulk Richardson Number

23 option in AERMET to use Delta-T data, and that's been

24 modified to include a more refined treatment of θ* and to

25 extend its suitability or applicability to very stable/low
38

KAY McGOVERN & ASSOCIATES (919) 870-1600

Suite 117, 314 West Millbrook Road FAX 870-1603

Raleigh, North Carolina 27609-4306 (800) 255-7886

1 wind conditions based on a more recent paper by Luhar and

2 Raynor, and that actually seems to have helped some of the

3 evaluations that we've seen.

4 So this updated ADJ_U* option in conjunction with

5 Bulk Richardson also includes some modifications in AERMET--

6 in AERMOD, pardon me--to subroutine TGINIT to calculate θ*. 

7 And some of the issues that we've dealt with on these new

8 options is, you know, the--is very low wind speed conditions

9 and it can be surprisingly sensitive in terms of predicting

10 the profile of potential temperature gradients.

11 So we have proposed in the notice of proposed

12 rulemaking that the ADJ_U* option either with or without the

13 Bulk Richardson option in AERMET be incorporated as part of

14 the regulatory version of the modeling system, so it's part

15 of the proposal.

16 So capped and horizontal stacks, this is an issue

17 that's been around for some time. Back in 1993 the Model

18 Clearinghouse had issued a memorandum that provided

19 recommendations for modeling capped and horizontal stacks,

20 and that procedure involved setting the exit velocity to a

21 very low number, .001 meter per second, but adjusting the

22 stack diameter to maintain the actual flow rate and buoyancy

23 of the plume. So that's something that would be done by the

24 user to modify the inputs to the model.

25 However, the PRIME numerical plume rise algorithm
39

KAY McGOVERN & ASSOCIATES (919) 870-1600

Suite 117, 314 West Millbrook Road FAX 870-1603

Raleigh, North Carolina 27609-4306 (800) 255-7886

1 for building downwash that was incorporated in 2005, I guess,

2 with AERMOD uses the input stack diameter to define the

3 initial radius of the plume, and use of a very large

4 effective radius may alter the results in physically

5 unrealistic ways. In fact, we found cases where the model

6 would crash because the--when that was being done.

7 So that prompted the need to do some different

8 approaches. The AERMOD Implementation Guide actually

9 suggests just setting the exit velocity to a very low number

10 and use the actual stack diameter as an interim solution. 

11 However, that could produce--introduce some bias towards

12 overprediction there.

13 So we eventually had--since version 06341 we've

14 had some draft/beta options to model capped and horizontal

15 stacks more explicitly, and but they're again not--they're

16 non-default beta options. So POINTCAP and POINTHOR source

17 type is used to trigger these, and the user just inputs the

18 actual stack exit velocity and stack diameter.

19 So for non-downwash sources it basically

20 implements the Model Clearinghouse procedure from 1993,

21 although there are some subtle differences in AERMOD as

22 opposed to ISC, so the POINTCAP/POINTHOR, that option

23 actually accounts for the vertical profiling of meteoro24 logical conditions in AERMOD that's more detailed than within

25 ISC.
40

KAY McGOVERN & ASSOCIATES (919) 870-1600

Suite 117, 314 West Millbrook Road FAX 870-1603

Raleigh, North Carolina 27609-4306 (800) 255-7886

1 For the POINTHOR--the horizontal stack option

2 actually uses the exit velocity assigned input to the model

3 as the initial horizontal velocity of the plume, and so the

4 issues that showed up--again, the prime downwash option uses

5 the numerical plume rise approach, and that actually can

6 account directly for the horizontal trajectory of the plume

7 for horizontal stacks.

8 For the POINTCAP option with downwash, the initial

9 plume radius is assigned to be twice the input stack

10 diameter--I guess that shouldn't be the plume radius, the

11 diameter--to account for initial plume spread from the cap

12 interacting--the plume interacting with the cap, and the

13 initial horizontal velocity is assigned to be based on the

14 exit velocity divided by 4. So it sort of has some

15 horizontal momentum to it but some vertical as well, rise.

16 So buoyant line sources--again, we've discussed

17 this briefly, but Appendix W currently recommends the use of

18 the BLP model for modeling these sources, but the BLP model

19 is based on some outdated dispersion theory, P-G dispersion

20 coefficients, and the meteorological data processor for BLP,

21 PCRAMMET, is not capable of processing the current meteoro22 logical data that we're using, including the 1-minute ASOS

23 data. So there are some complications and limitations on

24 being able to apply BLP well. It also lacks the processing

25 options that would support the form of the new one hour SO2
41

KAY McGOVERN & ASSOCIATES (919) 870-1600

Suite 117, 314 West Millbrook Road FAX 870-1603

Raleigh, North Carolina 27609-4306 (800) 255-7886

1 and NO2 standards as well as the 24 hour PM2.5 NAAQS.

2 So beginning with version 15181, AERMOD includes

3 an option to model buoyant line sources using the BUOYLINE

4 source type. And it allows for using the buoyant line--

5 modeling of buoyant line sources using meteorological data

6 that are processed through the AERMET meteorological

7 processor. It also allows the use of the AERMOD processing

8 options to support the form of the new standards. So

9 basically it just takes--it actually takes the inputs and

10 calls the BLP model directly.

11 So now we'll talk about some of the evaluations of

12 the proposed updates. There's a lot that's gone on here. 

13 I'll try to cover some of the highlights. But we have again

14 the proposed beta ADJ_U* option in AERMET and the Low_Wind

15 option in AERMOD.

16 And they've been evaluated based on several

17 relevant field studies, including--as I mentioned here, there

18 was a 1993 surface coal mine study, Cordero Rojo mine in

19 Wyoming, that was fugitive emissions of PM10 in 24 hour

20 concentrations, and this was done with version 14134. We've

21 also had two low wind studies that were part of the API-AECOM

22 low wind study, the '74 NOAA Oak Ridge, Tennessee study and

23 the Idaho Falls study in the same year.

24 So just some general caveats on model evaluation: 

25 it's a complex business, especially in these very extreme
42

KAY McGOVERN & ASSOCIATES (919) 870-1600

Suite 117, 314 West Millbrook Road FAX 870-1603

Raleigh, North Carolina 27609-4306 (800) 255-7886

1 conditions, very low wind speeds. Slight errors or

2 uncertainties in the wind direction or wind speed could

3 significantly affect the concentrations, and it would affect

4 the conclusions from the model performance evaluation, so

5 keep that in mind.

6 So quickly, the surface coal mine study--we've

7 shown this before, and the results presented here are

8 actually based on the previous version of AERMOD, but it was

9 a two month field study. Again, it was largely driven by

10 fugitive emissions from road dust from the trucks driving

11 around the mine. And we were able to apply the Cox-Tikvart

12 protocol for determining the best performing model to this. 

13 We presented these results based on version 14134, but the

14 results are likely to be similar for the current version.

15 That just shows a schematic of the mine, and this

16 is the composite performance measure that shows with

17 confidence intervals the different options. Starting from

18 the top, the top three are with ADJ_U*. The top one is with

19 ADJ_U* and LowWind2, then LowWind1, and then no low wind. 

20 And there's very little differentiation between the low wind

21 options there.

22 But the bottom three are without the ADJ_U* option

23 in AERMET, so the default, and there's a little bit more

24 difference in the low wind options, but the key thing is that

25 the top three are closer to the left side, and that means
43

KAY McGOVERN & ASSOCIATES (919) 870-1600

Suite 117, 314 West Millbrook Road FAX 870-1603

Raleigh, North Carolina 27609-4306 (800) 255-7886

1 better performance, so a smaller value of CPM does imply

2 better model performance.

3 More importantly maybe, the model comparison

4 measure is the--compared the performance of one model against

5 another. So in the top three, again, that shows performance

6 with and without the ADJ_U* option for the different low wind

7 options, and the key point there is that those confidence

8 intervals, the horizontal bars, do not cross zero, and that

9 suggests that the difference in performance is statistically

10 significant, and that's the key point here. The bottom three

11 just basically show the differences between the low wind

12 options. Again, there's very little differentiation there.

13 So again, the low wind option--the LowWind1

14 options in AERMOD appeared to have limited effect on model

15 performance in this case, but it does show significant

16 improvement with the ADJ_U* option.

17 So that brings us to the Oak Ridge and Idaho Falls

18 studies, which are really the more relevant and key databases

19 that we've been working with that API and AECOM introduced a

20 few years back. It's sort of sad to see that the best tracer

21 studies are from the mid '70s, but at least we still have

22 that data intact.

23 So there are just some caveats and I won't go over

24 the details, but it's--especially under these extreme

25 conditions some of these issues or decisions you might make
44

KAY McGOVERN & ASSOCIATES (919) 870-1600

Suite 117, 314 West Millbrook Road FAX 870-1603

Raleigh, North Carolina 27609-4306 (800) 255-7886

1 may have a little bit more relevance. So EPA assumed a

2 different surface roughness for Oak Ridge, .6, compared to

3 the original assumption in the AECOM/API study of .2.

4 One of the complications with the Oak Ridge study

5 is the winds were so low that they couldn't measure them, and

6 so the wind speeds reported were based on laser anemometry. 

7 And so basically it's the Oak Ridge peninsula, so there are

8 some hollers in there, in the Oak Ridge peninsula itself, and

9 they had laser anemometry based on lasers that were up on the

10 ridges, and where those lasers intersected was about 20

11 meters above the bottom, where the source was.

12 So we made a different assumption about the

13 measurement height, and it doesn't necessarily change the

14 results that much, but we also made some adjustments to the

15 surface roughness for these studies.

16 So that's the Oak Ridge area. You can see there's

17 some terrain there; you can see where the arcs are. So this

18 is some of the results with the version 15181. The paired

19 concentrations are on the left. The predicted to observed

20 ratios are on the right. This is done by arc. So you can

21 see with the default options there's pretty significant

22 overprediction at this site.

23 When we bring in the ADJ_U* option and LowWind2--

24 well, without the ADJ_U* and LowWind2 it does improve things

25 somewhat noticeably. On the right side it's the comparison
45

KAY McGOVERN & ASSOCIATES (919) 870-1600

Suite 117, 314 West Millbrook Road FAX 870-1603

Raleigh, North Carolina 27609-4306 (800) 255-7886

1 with the LowWind3 option in the newer version of AERMOD

2 without the ADJ_U*, so the low wind option does make some

3 impact here.

4 This is with ADJ_U* and no low wind. On the left

5 it's the previous version; on the right it's the newer

6 version. And it eliminates much of that overprediction, but

7 there's still a pretty wide spread.

8 This is with ADJ_U* and LowWind2 versus LowWind3,

9 and it looks pretty good on the left. There's a little bit

10 below the 1 to 1 line on the right with the LowWind3 option,

11 but again, there are some additional caveats here, is that

12 there is terrain as part of the Oak Ridge site, and that has

13 not been accounted for in the evaluation that API did or that

14 we've done here.

15 This is the Idaho Falls study area. You can see

16 where the arcs were--the 100, 200, 400 meter arcs were

17 situated, but it's pretty flat, much different than the Oak

18 Ridge. So these results are paired by arc again, and with

19 the default options there is some overprediction, roughly

20 about a factor of 2 overall, but it's pretty consistent with

21 distance.

22 Without the ADJ_U* with LowWind1 (sic) on the left

23 for the previous version, LowWind3 on the right for the new

24 version, eliminates most of that overprediction and actually

25 looks pretty good just with the low wind options.
46

KAY McGOVERN & ASSOCIATES (919) 870-1600

Suite 117, 314 West Millbrook Road FAX 870-1603

Raleigh, North Carolina 27609-4306 (800) 255-7886

1 With ADJ_U* and no low wind, again, it eliminates

2 most of that overprediction, but there's a little bit of

3 tendency with distance for the ratios to go down, but maybe

4 that's okay. With the ADJ_U* and the low wind options, the

5 predicted is really good at the closest arc, which would

6 probably be the most important for this, but still pretty

7 good performance overall.

8 And this is with the--that was--so these are all--

9 the previous results were the degraded 1-layer data, but the

10 one thing that the Idaho Falls study provided is we got the

11 raw data and we were able to calculate some Delta-T measure12 ments so we would be able to use the Bulk Richardson Number

13 option in here, and this is one of the more surprising

14 results, that without the ADJ_U*, the Bulk Richardson Number

15 option didn't work that well, especially at the closest arc. 

16 You can see a pretty wide spread and quite a bit of under17 prediction at the 100 meter arc. It got a little bit better

18 downwind. With the ADJ_U* and Bulk Richardson, the results

19 actually look much, much better, so that was an encouraging

20 result.

21 So that kind of wraps it up. I can't take any

22 questions, which is fine by me. Thank you.

23 Mr. Bridgers: Thank you, Roger. Actually,

24 that was saying 15 more minutes, so---

25 Mr. Brode: (interposing) Okay. Do you
47

KAY McGOVERN & ASSOCIATES (919) 870-1600

Suite 117, 314 West Millbrook Road FAX 870-1603

Raleigh, North Carolina 27609-4306 (800) 255-7886

1 want me to keep going?

2 Mr. Bridgers: No. James had already yielded

3 some time to you. I didn't want you to feel too rushed

4 because that was an important presentation because that gets

5 at the heart, at least the front end, of what's in our

6 proposal.

7 So next up, James Thurman from our Modeling Group

8 is going to give us a quick presentation--I'm not going to

9 even run this, James; I know you'll be done ten minutes--on

10 AERSCREEN.

11 Dr. Thurman: Okay. This will be the best

12 presentation from EPA today because it's only four slides. 

13 I'm James Thurman from the Modeling Group to give you a quick

14 update on AERSCREEN.

15 This slide shows the status of AERSCREEN through

16 the years, first mentioned in the 2000 (sic) Guideline when

17 it said it would be released in the fall of 2005, but it made

18 it till 2011 where we released AERSCREEN and the accompanying

19 meteorological processor MAKEMET to generate the screening

20 met. 

21 We also issued a memo in April of 2011

22 recommending AERSCREEN as the recommended screening model for

23 EPA, because it's based on AERMOD, which represented the

24 state of the science. And just to remind you, AERSCREEN is

25 only done for single sources only. It doesn't have the
48

KAY McGOVERN & ASSOCIATES (919) 870-1600

Suite 117, 314 West Millbrook Road FAX 870-1603

Raleigh, North Carolina 27609-4306 (800) 255-7886

1 multisource capability.

2 And then for the proposed Guideline for 2015 we're

3 incorporating AERSCREEN into the Guideline as the screening

4 model for AERMOD, and it will be applicable in all types of

5 terrain and building downwash applications. And AERSCREEN is

6 discussed in detail in Section 4.2.1.1 of the proposed

7 Guideline.

8 I'll just note the latest version of AERSCREEN,

9 15181. We incorporated the inversion break-up fumigation and

10 coastal fumigation options from SCREEN3. That was probably

11 one of the last reasons people were running SCREEN3 other

12 than AERSCREEN is too hard to run, which as Tyler and I say,

13 real men run AERSCREEN.

14 It uses the AERMOD equations for the sigma-y and

15 sigma-z estimates used in the fumigation calculations. And I

16 won't go into detail here, but you can see the AERSCREEN

17 User's Guide for full details on how these fumigation options

18 are incorporated.

19 We also tried to make the code more portable

20 across operating systems by eliminating system calls to copy

21 and delete files when possible, so we actually do Fortran

22 statements to the write and delete. There are still some

23 system calls like clearing the screen, but we've put in the

24 code and commented out for the Unix and Linux options of

25 clearing the screen and also added a debug option to output
49

KAY McGOVERN & ASSOCIATES (919) 870-1600

Suite 117, 314 West Millbrook Road FAX 870-1603

Raleigh, North Carolina 27609-4306 (800) 255-7886

1 the intermediate output from the PROBE and FLOWSECTOR

2 subroutines and also output the intermediate fumigation

3 estimates if you want to see what was going on besides the

4 final results, and we also did some bug fixes.

5 And one thing on the fumigation options, I did

6 change it where you don't have to run AERSCREEN and do all

7 the AERMOD screening runs inside AERSCREEN. It will actually

8 just do the fumigation options, so you can usually get a

9 quick result there.

10 And then on MAKEMET we incorporated the ability to

11 adjust the surface friction velocity, U*, based on the AERMET

12 adjustment algorithms. That was done to help Chris Owen's

13 work on mobile source modeling. Right now this U* adjustment

14 is not done when you're calling MAKEMET from AERSCREEN. It

15 sets that option to no, but if you want to run the U* adjust16 ment with MAKEMET, you can do that outside of AERSCREEN by

17 running MAKEMET on your own.

18 We may incorporate the ability in future versions

19 of AERSCREEN to make it an option to do a U* adjustment, not

20 for like regulatory screening runs, but if you just want to

21 get a quick result of how much change the U* adjustment will

22 make on your results. And then that's it, and I yield my

23 time to Chris.

24 Mr. Bridgers: In the interest of political

25 correctness, it would be real modelers run AERSCREEN. I want
50

KAY McGOVERN & ASSOCIATES (919) 870-1600

Suite 117, 314 West Millbrook Road FAX 870-1603

Raleigh, North Carolina 27609-4306 (800) 255-7886

1 to make sure that we stay aboveboard.

2 While I'm changing presentations, I also wanted to

3 point out, since I'm the point of contact on the SCRAM web

4 site updates, AERMOD 15181, AERSCREEN 15181, and MAKEMET

5 15181, they were all posted when we posted the proposal. 

6 Just so that we're also crystal--as clear as we

7 can be, if you go to the 11th Conference Modeling page, there

8 are some specifics for each of the postings of the model, but

9 if you're going for the regulatory release, I recommend going

10 to the other part of SCRAM where you normally would download

11 AERMOD or AERSCREEN because all the model change bulletins

12 and the other supporting information from its regulatory

13 application is there. So if you're using the link for the

14 11th Modeling page to download the model, I'd recommend going

15 over to the other.

16 All right. So we will transition from screening

17 and the demise of SCREEN3 in the regulatory application to

18 changes with respect to NO2 with Chris Owen, and Chris, I'm

19 going to give you a little extra time. You lucked out.

20 Dr. Owen: Thanks, George. It looks like

21 James actually yielded his time to you, but that's okay. I

22 think we can get through this in time. And actually with the

23 NO2 modeling we're still referring to screening, just of a

24 slightly less conservative nature.

25 So I'm going to give an overview of the proposed
51

KAY McGOVERN & ASSOCIATES (919) 870-1600

Suite 117, 314 West Millbrook Road FAX 870-1603

Raleigh, North Carolina 27609-4306 (800) 255-7886

1 changes to AERMOD and Appendix W with respect to NO2

2 modeling. I'd like to thank my workgroup, which consisted o

3 of members from OAQPS, Regions 3, 4, 5, 6, and 10, and the

4 Office of Research and Development.

5 In short, EPA is proposing to modify both AERMOD

6 and Section 4.2.3.4 of Appendix W. These proposed changes

7 will incorporated ARM2 as the regulatory default option for

8 Tier 2 screening. It will adopt OLM and PVMRM as the

9 regulatory default options for Tier 3 screening, and we will

10 actually be updating PVMRM with additional dispersion and

11 plume calculations, currently dubbed PVMRM2.

12 This slide gives some details on the ARM2

13 adoption. ARM2 or the ambient ratio 2 method was originally

14 developed by an API funded study. The study was eventually

15 published in a peer reviewed journal article in 2014 by Marc

16 Podrez in Atmospheric Environment. The proposed version of

17 ARM2 in Appendix W and AERMOD has one modification to the

18 version that was provided in the final published paper, and

19 that is we propose to modify the minimum default ambient NO2

20 to NOx ratio to 0.5.

21 This proposal is to bring consistency between the

22 Tier 2 and Tier 3 methods. Specifically we have a

23 recommendation for the default NO2 to NOx in-stack ratio for

24 the Tier 3 methods to be equal to 0.5. The slide here shows

25 some model simulations comparing PVMRM with an in-stack ratio
52

KAY McGOVERN & ASSOCIATES (919) 870-1600

Suite 117, 314 West Millbrook Road FAX 870-1603

Raleigh, North Carolina 27609-4306 (800) 255-7886

1 of 0.5 and an in-stack ratio of 0.2. 

2 You can see that when you use PVMRM with this

3 recommended default, 0.5, your ambient NO2 to NOx ratios are

4 also equal to 0.5, and thus we believe that the minimum

5 ambient NO2 to NOx ratio for ARM2 is most appropriately set

6 to 0.5 to be consistent with the Tier 3 methods.

7 For the OLM and PVMRM adoption and implementation,

8 this will be very similar, what we currently have in the

9 model and what we've recommended in past Guidance. That is

10 there will be no default background ozone value. We're

11 recommending a maximum ambient NO2 to NOx ratio of 0.9 for

12 the Tier 3 options. 

13 We're also recommending a default in-stack ratio

14 of 0.5 for the primary source and nearby sources. However,

15 for more distant sources we're recommending an in-stack ratio

16 of 0.2. We do actually specify now in the reg text that

17 PVMRM works better for relatively isolated and elevated point

18 sources and OLM tends to work better for other source types.

19 With respect to the modifications to PVMRM that

20 we've dubbed PVMRM2, the PVMRM2 uses absolute rather than

21 relative dispersion coefficients under stable wind

22 conditions. There are several modifications in PVMRM2 to the

23 computation of the plume volume, and there are several

24 additional miscellaneous bug fixes that are included in

25 PVMRM2. Our proposal is to eventually replace PVMRM with
53

KAY McGOVERN & ASSOCIATES (919) 870-1600

Suite 117, 314 West Millbrook Road FAX 870-1603

Raleigh, North Carolina 27609-4306 (800) 255-7886

1 PVMRM2. However, in version 15181 we have both PVMRM and

2 PVMRM2 to facilitate evaluations of the two different model

3 codings.

4 We provide in our technical support document

5 several evaluations of PVMRM and PVMRM2. The slide here

6 provides an example from the Empire Abo gas plant in New

7 Mexico which compares results from full conversion, PVMRM2--I

8 actually can't see it on the computer here--PVMRM, and I

9 think it's OLM Group all. And the slide here doesn't give

10 very good detail. I again recommend that folks look at the

11 technical support document that's provided on this for easier

12 viewing.

13 The slides here do show if you can see that PVMRM2

14 is the best performing of the options that are evaluated for

15 this particular--these two particular monitors for this one

16 particular source.

17 Finally, I'd like to emphasize what Tyler said

18 earlier with respect to beta options in AERMOD, so the status

19 of the Tier 2 and Tier 3 screening methods. All of the NO2

20 options are defined as screening techniques. If Appendix W

21 goes forward as proposed, then the NO2 options will no longer

22 be alternative models. They will not need approval by the

23 regional office.

24 However, as screening methods, the reg text will

25 specify that their use will occur in agreement with the
54

KAY McGOVERN & ASSOCIATES (919) 870-1600

Suite 117, 314 West Millbrook Road FAX 870-1603

Raleigh, North Carolina 27609-4306 (800) 255-7886

1 appropriate reviewing authority, and this is specified in

2 Section 4.2.1(b) of the proposed version of Appendix W.

3 Additionally, because of the complexities of the

4 Tier 3 options, applicants would need to consult with the EPA

5 regional office in addition to the reviewing authority. This

6 is specified in Section 4.2.3.4(e). And again, this is occur

7 in agreement with the appropriate reviewing authority and

8 consult the EPA regional office, and you will no longer need

9 alternative model approval.

10 Again, though, this goes into effect with the

11 final version of AERMOD to be released next year. At present

12 ARM2, OLM, and PVMRM and PVMRM2 are still beta in version

13 15181 and they do require regional office approval at this

14 time. We released a Model Clearinghouse memo earlier in the

15 month on the use of ARM2 and refer readers to that memo to

16 get additional details on the use of ARM2 in regulatory

17 application. That should be July 8th, I believe.

18 The relevant docket items for this are specified

19 here. The docket items are both on regulations.gov and they

20 can be obtained on the 11th Modeling Conference web site as

21 well. And that concludes my slides for NO2, and it looks

22 like I've yielded myself 11 and a half minutes.

23 Okay. Now I'm going to give details on the

24 proposed replacement of CALINE3 with AERMOD in Appendix W. 

25 I'd like to first thank my workgroup, which consisted of
55

KAY McGOVERN & ASSOCIATES (919) 870-1600

Suite 117, 314 West Millbrook Road FAX 870-1603

Raleigh, North Carolina 27609-4306 (800) 255-7886

1 members of OAQPS, the Office of Transportation Air Quality,

2 Office of Research and Development, and Region 5.

3 As the title of this slide suggests, we are

4 proposing to replace CALINE3, CAL3QHC, and CAL3QHCR with

5 AERMOD as the preferred Appendix A dispersion model for all

6 mobile source modeling for inert pollutants. 

7 This proposal is based on three elements: first,

8 the AERMOD has updated dispersion model science relative to

9 CALINE3; second, the model intercomparisons of AERMOD show

10 that AERMOD outperforms CALINE3; and thirdly, that the

11 adoption of AERMOD would provide a simplified implementation

12 of mobile source modeling for Clean Air Act requirements. 

13 These updates are reflected in Sections 4.2.3 and 7.2.3 of

14 the proposed Appendix W text.

15 To support the elements of the changes in model

16 science I have some background on AERMOD and CALINE3. 

17 CALINE3 was developed in 1979. The dispersion model theory

18 is based on P-G stability classes, and the baseline CALINE3

19 model can actually only handle a single meteorological

20 condition.

21 CAL3QHC was developed from CALINE3 for use in

22 screening for mobile sources. It adds a queuing algorithm

23 for emissions from intersections. And finally, CAL3QHCR was

24 developed from CAL3QHC for refined analyses. 

25 CAL3QHCR adds the ability to use one year of
56

KAY McGOVERN & ASSOCIATES (919) 870-1600

Suite 117, 314 West Millbrook Road FAX 870-1603

Raleigh, North Carolina 27609-4306 (800) 255-7886

1 meteorological data. It adds an hourly emissions variation,

2 adds additional averaging periods for the additional met

3 that's processed in the model. The met preprocessor that's

4 available for CAL3QHCR is only available for very old

5 meteorological data sets and has not been updated to use any

6 of the newer one minute data.

7 The model developers replaced CALINE3 with CALINE4

8 in 1984, so according to the model developers CALINE3 was

9 outdated over 30 years ago.

10 Contrary to CALINE3, AERMOD was adopted in 2005

11 with the 2005 revisions to Appendix W. It reflects state of

12 the science dispersion model formulation, specifically the

13 boundary layer scaling parameter is used to characterize

14 stability and determine dispersion rates. Monin-Obukhof

15 similarity profiling of winds are used near the surface. 

16 And the main point here is that in adopting AERMOD

17 in 2005 to replace ISC, one of the major technical advance18 ments was to replace the P-G stability class dispersion

19 that's used in both ISC and CALINE with these turbulence

20 based dispersion rates consistent with PBL and M-O scaling

21 and similarity profiling.

22 EPA has conducted several model performance

23 evaluations and intercomparisons to determine the performance

24 of AERMOD versus CALINE3 as well as several other models. 

25 These results were published in 2013 by Heist, et al. in
57

KAY McGOVERN & ASSOCIATES (919) 870-1600

Suite 117, 314 West Millbrook Road FAX 870-1603

Raleigh, North Carolina 27609-4306 (800) 255-7886

1 Transportation Research D. 

2 These model findings were based on two field

3 studies that used SF6 tracers that were specifically designed

4 for evaluation of mobile source modeling. These two field

5 studies were the CALTRANS99 tracer experiment and the Idaho

6 Falls barrier tracer experiment.

7 In the next couple of slides I give a very brief

8 summary of some of these results from these model inter9 comparisons. The slide on your left shows model statistics

10 for the highest 25 concentrations from the models that were

11 used in these model evaluations. These model runs consisted

12 of the RLINE model, which is currently being developed by the

13 Office of Research and Development; AERMOD using both area

14 and volume sources; CALINE3 and CALINE4; and the UK's

15 regulatory default model, ADMS.

16 The statistics slide shows the robust highest

17 concentration versus the fractional bias. The best

18 performing or even a perfect performing model would be at the

19 center of the axis that's highlighted in green. The model

20 statistics for CALTRANS show that AERMOD and RLINE have

21 almost identical performance, and you can see CALINE has a

22 tendency to overpredict by a factor of 2 and 3 depending on

23 whether you're looking at CALINE3 or CALINE4.

24 On the right-hand side I have a Q-Q plot, which

25 just makes it a little bit easier to see the model
58

KAY McGOVERN & ASSOCIATES (919) 870-1600

Suite 117, 314 West Millbrook Road FAX 870-1603

Raleigh, North Carolina 27609-4306 (800) 255-7886

1 performance of these different concentration levels. You can

2 see the CALINE3 and the CALINE4 model results are extreme

3 outliers on this plot, the other models doing fairly well,

4 relatively close to the 1 to 1 line. But the model

5 performance for CALINE3 and CALINE4 is not just limited to

6 the top three or four concentrations. Its overestimate

7 extends to about the top third of the distribution of data.

8 This slide shows the results from the Idaho Falls

9 tracer study. The same set of slides are presented on this

10 as the previous slide. On the left-hand side I've got the

11 model statistics for the top 25 concentrations. On the

12 right-hand side I have the Q-Q plot.

13 For this particular field study all of the models

14 had a tendency to underpredict rather than to overpredict. 

15 The model statistics indicate that AERMOD and this time ADMS

16 are almost identical and have the best model performance out

17 of the three models. And this time CALINE has a tendency to

18 underpredict.

19 And you may notice on this slide that I have

20 CALINE4 and not CALINE3. For this particular field study we

21 were not able to get CALINE3 to provide reasonable results. 

22 We had three or four different doctorates in engineering look

23 at this model and try to get reasonable results and we could

24 not get numbers that made sense to us. It may have been user

25 error or it may have been a limitation of the model. But
59

KAY McGOVERN & ASSOCIATES (919) 870-1600

Suite 117, 314 West Millbrook Road FAX 870-1603

Raleigh, North Carolina 27609-4306 (800) 255-7886

1 because of our inability to understand what was going on with

2 CALINE3, we excluded those results from this particular field

3 study. However, we're using CALINE4 as a surrogate for

4 CALINE3 under the assumption that CALINE4 would perform

5 better than CALINE3.

6 For this field study you can see CALINE4 is the

7 worst underpredictor. In the Q-Q plot you can see that

8 CALINE4 underpredicts across almost the entire concentration

9 distribution range.

10 The third basis for our proposal is that the EPA

11 believes that the adoption of AERMOD will provide a stream12 lined implementation for mobile sources. The Appendix W

13 proposal will bring commonality and consistency in the model

14 analyses that are performed for EPA regulatory applications.

15 Specifically, AERMOD is already preferred for PM2.5

16 and PM10 conformity analyses. The adoption of AERMOD would

17 bring one model choice rather than four different model

18 choices for modeling mobile sources, so it would make the

19 selection of model more simple. AERMOD has additional

20 options for source characterization, computation of design

21 value, and is able to use more updated and refined

22 meteorological inputs.

23 Finally, I'd like to point out that FAA already

24 uses AERMOD in their EDMS and AEDT model. They moved away

25 from the CALINE3 model in 2005 when EPA promulgated AERMOD as
60

KAY McGOVERN & ASSOCIATES (919) 870-1600

Suite 117, 314 West Millbrook Road FAX 870-1603

Raleigh, North Carolina 27609-4306 (800) 255-7886

1 the preferred dispersion model. So the DOT has already

2 adopted AERMOD over CALINE3 in the past.

3 Finally, I'd like to just point out that EPA fully

4 supports AERMOD with continued development and updates to

5 meet regulatory needs and issues, and that would include

6 updates that are needed to facilitate mobile source modeling

7 in the future.

8 I'd finally like to highlight EPA's transition

9 plans under the proposed rulemaking. EPA is taking comment

10 on the transition period from CALINE3 to AERMOD in the

11 proposed rulemaking. We are currently proposing a one year

12 transition period for the adoption of AERMOD over CALINE3. 

13 That means it would be slightly less than two years from now

14 until applicants would be required to use AERMOD in place of

15 CALINE3. Again, we're taking comment on this transition

16 period.

17 Additionally, I'd just like to provide a note that

18 EPA plans to provide training and already has a number of

19 training courses in place. We will provide a training

20 package with examples for using AERMOD over CAL3QHC for CO

21 screening analyses. We'll provide webinars and trainings for

22 stakeholders as needed. 

23 And as I mentioned, EPA already has several

24 trainings that are available, specifically the Air Pollution

25 Training Institute course number 423, Air Pollution
61

KAY McGOVERN & ASSOCIATES (919) 870-1600

Suite 117, 314 West Millbrook Road FAX 870-1603

Raleigh, North Carolina 27609-4306 (800) 255-7886

1 Dispersion Models, which outlines the use of AERMOD for

2 regulatory analyses. And the Office of Transportation Air

3 Quality already has training in place for project level hot

4 spot analyses.

5 Again, the technical details are provided in the

6 technical support document. These are available from

7 regulations.gov as well as the 11th Modeling Conference web

8 site. Thank you.

9 Mr. Bridgers: And just so I don't get one of

10 our transcriptionists in trouble, I was actually trying to

11 get Chris to slow down because I normally have the problem

12 with trying to get people to stop talking. I needed to--I

13 should do my whole TV thing. It's like stretch it out

14 (indicating).

15 So we are running a bit ahead of schedule, and I

16 am going to afford a little bit longer break just because of

17 that. But I wanted to make two notes. Chris in that last

18 set of slides had said that there would be a one year

19 transition period with respect to this replacement of CALINE. 

20 That's broadly applicable with respect to the transition once

21 we get to 2016 and the promulgation of whatever form of

22 AERMOD we have after we go through the comment and

23 rulemaking.

24 I'm going to put some filler in here if the--oh,

25 it died. Well, I'm still going to put some filler in here. 
62

KAY McGOVERN & ASSOCIATES (919) 870-1600

Suite 117, 314 West Millbrook Road FAX 870-1603

Raleigh, North Carolina 27609-4306 (800) 255-7886

1 You guys can watch a real quick demonstration. In the

2 previous presentation Chris mentioned that we had just issued

3 a clearinghouse memorandum with respect to ARM2. And I'll

4 speak to this a little bit more in the clearinghouse

5 presentation, but in this particular case this is an avenue

6 to which we can bring beta options to the forefront and use

7 them currently, whether proposed or not.

8 Now, you can see how I get to SCRAM. I don't know

9 the EPA web address right off the top of my head. I should. 

10 So I Google it. And it's going to get me to scram001, which

11 I know. But I did want to real quickly, because I won't have

12 this time after the break--so I'm on the guidance and

13 support. It's buried.

14 I will also mention that we are on the precipice

15 of revising the entire web structure of the EPA web site, and

16 so here in probably a year's time there will not be a SCRAM

17 web site because we understand that that is not necessarily

18 sensitive to the external community. 

19 There seems to be some idea that we're telling

20 people to go away when we say SCRAM, so it--even though it's

21 a very technical web site, we are going to have to make it

22 such that the third grade audience can come in and feel good

23 about their experience. So there will probably be some

24 cutesy pictures and I'm sure we'll have to come up with an

25 icon for AERMOD or whatever Appendix A models we have.
63

KAY McGOVERN & ASSOCIATES (919) 870-1600

Suite 117, 314 West Millbrook Road FAX 870-1603

Raleigh, North Carolina 27609-4306 (800) 255-7886

1 Male Voice: We can keep the name. We just

2 have to change the format.

3 Mr. Bridgers: We have to change the format;

4 right. So I'm going into MCHISRS, and I know some of you

5 loathe this, but I just wanted to point out--and I haven't

6 sent out the e-mail. It will come out in the next couple of

7 days. I just haven't had time. I'm just going in and

8 searching on Region 2 because Chris said it was a Region 2

9 memo, and I found 145 records. I'm going to go to the end

10 because it always sorts from the '80s. And see, here it is.

11 Voices: No, we don't see it. We can't

12 see it.

13 Mr. Bridgers: You can't see it. Oh, no. 

14 Okay. Well, let me start over again. See, this is a great

15 way for filling time. Now, let me see. I don't even know

16 how to get the screen back. Oh, okay. Well, we'll go

17 through my whole process again. I get three more minutes. 

18 So here's the web browser, yay. And it probably

19 has--yeah, here we go. It probably already has it in there. 

20 Now I can't see it, so I'm going to have to look over here,

21 and now it doesn't work. So this also proves this is not

22 centric to Internet Explorer, but MCHISRS is under Model

23 Guidance and Support, the Clearinghouse and MCHISRS. One

24 part of the web redesign is things will probably be a lot

25 more logically laid out and easier to find.
64

KAY McGOVERN & ASSOCIATES (919) 870-1600

Suite 117, 314 West Millbrook Road FAX 870-1603

Raleigh, North Carolina 27609-4306 (800) 255-7886

1 So I'm just going into MCHISRS, and there's a lot

2 of options here, but one of them is for EPA region or state. 

3 And so I know that it's involving Region 2, so I'm going to

4 click Search. It happens to find 145 records, and as I said,

5 they start, you know, from a chronological order, and I'm

6 just going to go to the end.

7 And as we have indicated, it seems like there was

8 a lot of activity in the '80s and '90s and then things kind

9 of fell off, and so from the late '90s to 2015 there's a big

10 gap. Things were just perfect in the modeling world.

11 So anyway, here's the actual record in MCHISRS.

12 There's a brief summary. So that we have the date straight,

13 it's July 16th. And I will point out--I've got a lot of ums

14 in my statements today, but I will point out the request came

15 in on the 18th, the reply went out on the 16th, and this was

16 in the middle of a proposed rulemaking.

17 So I know there's a lot of built-up pent energy

18 that things take a very long time in the Clearinghouse, but

19 here's one that we had a lot of other things going on and we

20 did drop some things, but we got this out in about a month's

21 time. We've got another couple that are in process and we're

22 going to be following up as soon as we get through with the

23 modeling conference here.

24 But anyway, here's the signed response back. And

25 so this can be the basis for future ARM2 usage, assuming--
65

KAY McGOVERN & ASSOCIATES (919) 870-1600

Suite 117, 314 West Millbrook Road FAX 870-1603

Raleigh, North Carolina 27609-4306 (800) 255-7886

1 what's that?

2 Mr. Fox: In the interim.

3 Mr. Bridgers: In the interim--assuming that

4 you meet the requirements in the memorandum that we put out

5 on ARM2 and are broadly applicable to the justification that

6 was here. So there's a path forward. Now, we talked about

7 this in previous conferences that the bar is much lower,

8 significantly lower now with ARM2 than it has been in the

9 past, because there's a road map people can follow.

10 And to Tyler's point here, it's also that we've

11 done a lot of work and there's a lot of things put forth in

12 the proposed rulemaking that can also be used as a part of

13 the justification for future ARM2 use.

14 So ADJ_U*, we've got something on the precipice. 

15 We hope to be moving forward with the Clearinghouse action. 

16 We're hoping through that action lowering the bar. But

17 anybody that desires the use of the beta option in AERMET of

18 ADJ_U* right now, there's a lot of pieces of the puzzle that

19 are on the 11th Conference or in the docket to this

20 rulemaking, and it's there. And so that's--I just want to

21 reinforce that.

22 So we have reached 10 o'clock. We're running ten

23 minutes ahead of schedule. Why don't we split the

24 difference? I know the schedule says that we go until 10:30. 

25 Why don't we split the difference and come back at 10:25? 
66

KAY McGOVERN & ASSOCIATES (919) 870-1600

Suite 117, 314 West Millbrook Road FAX 870-1603

Raleigh, North Carolina 27609-4306 (800) 255-7886

1 That gives us--or do you want to go 10:20?

2 Mr. Wayland: Go to 10:20 and give a longer

3 lunch in case---

4 Mr. Bridgers: (interposing) Yeah, let's do--

5 okay, yeah, let's do that. I like Chet's suggestion. Let's

6 go to 10:20. That gives us 20 minutes for the break and what

7 we'll do is on the back end if we have extra time we'll just

8 take a longer lunch, and I think that's what people enjoy. 

9 So I will suspend now for 20 minutes. Please be back at

10 10:20.

11 (A recess was taken from 10:03 a.m. to 10:20 a.m.)

12 Mr. Bridgers: So we'll start the second

13 morning session now, and we'll start right off with another

14 presentation by James Thurman with Chris Misenis somewhere in

15 the room, and this is focused on aspects of Section 8 and

16 meteorological data.

17 Dr. Thurman: Okay. So I'm going to talk

18 about meteorological data for the dispersion models. These

19 are the members of the workgroup. Myself and Chris were 

20 co-leads, or as I like to say, Chris is the assistant to the

21 co-lead. He's Dwight Schrute to my Michael Scott. Members

22 from OAQPS and the regional offices, and just some

23 acknowledgements: Kali Frost of Indiana provided the Gibson

24 AERMOD inputs and meteorological observed data for our

25 evaluations. Missouri DNR and Andy Hawkins of Region 7 ran
67

KAY McGOVERN & ASSOCIATES (919) 870-1600

Suite 117, 314 West Millbrook Road FAX 870-1603

Raleigh, North Carolina 27609-4306 (800) 255-7886

1 Herculaneum AERMOD and MMIF, and then Andy and Kirk Baker

2 from OAQPS and Roger for the Martins Creek WRF/MMIF output. 

3 Then Rebecca Matichuk from Region 8 did the

4 meteorological analysis of the Region 8 sites. That's

5 Appendix B in the TSD. And I also want to acknowledge Bart

6 Brashers of Environ for all his work on the MMIF. He's done

7 a lot of work on MMIF and been a great help.

8 So Section 8.4 discusses the meteorological data

9 for dispersion models. There's two aspects: observed data

10 and the prognostic data. On the observed data side, the main

11 focus was on the introduction of AERMET into Appendix W. 

12 As you know, we introduced AERMINUTE in 2011, and

13 it calculates hourly averages of the winds from the 2 minute

14 winds for ASOS stations. And in 2013 we issued a memo

15 regarding the use of ASOS data and AERMINUTE in AERMOD, and

16 you can see the link under that sub-bullet. And our

17 recommendation is that it should be routinely used when

18 available.

19 There are some data gaps we found out in 2013

20 through Region 5 and AECOM, and it's a pretty substantial

21 gap, so we're actually doing an update to AERMINUTE to bring

22 in the five minute wind data to substitute missing hours, and

23 we hope to have that out by October.

24 From the prognostic side, we're proposing that if

25 you don't have a representative NWS station, National Weather
68

KAY McGOVERN & ASSOCIATES (919) 870-1600

Suite 117, 314 West Millbrook Road FAX 870-1603

Raleigh, North Carolina 27609-4306 (800) 255-7886

1 Service station, and it's infeasible to collect site specific

2 data, you can use prognostic data. We're saying no--

3 recommending no--or proposing no fewer than three years of

4 data.

5 We developed the MMIF program to read the

6 prognostic data, such as WRF data, for input into AERMET and

7 AERMOD as well as other dispersion models, and MMIF is the

8 outcome of BARF, the Bret Anderson ReFormatter, so if you

9 BARF you get MMIF.

10 So we also issued guidance for the use of

11 prognostic met data. Here are some highlights of that

12 guidance. The number of years is a minimum of three years. 

13 For developing the meteorological fields, i.e. run in WRF,

14 you would follow the Ozone, PM2.5, and Regional Haze Modeling

15 Guidance that was updated in December 2014. I think that's

16 the Brian Timin guidance.

17 Our guidance also describes some evaluation

18 procedures, and you can see the link to that in the last

19 bullet, and you can also see the link at the very bottom for

20 the Ozone, PM2.5, and Regional Haze Guidance.

21 More details on our guidance: we get guidance on

22 running MMIF for AERMOD. For regulatory applications you

23 should run MMIF to generate AERMET inputs. That's because

24 AERMET is the regulatory meteorological preprocessor for

25 AERMOD and it also allows you to take advantage of options in
69

KAY McGOVERN & ASSOCIATES (919) 870-1600

Suite 117, 314 West Millbrook Road FAX 870-1603

Raleigh, North Carolina 27609-4306 (800) 255-7886

1 AERMET such as the u* adjustment and the upper air selection

2 time. If you're doing a nonregulatory application, you can

3 run MMIF to AERMET or go straight from MMIF to AERMOD to

4 generate the profile and surface file that go into AERMOD.

5 We also offer guidance on the grid resolution of

6 your WRF or prognostic run. That would depend on the

7 location, you know, the complex terrain or complex meteoro8 logical situations.

9 Guidance on the representative grid cell, you

10 would run through MMIF for your application. For most cases,

11 this would be the grid cell that contains the facility of

12 interest, and if it's something like a SIP that could cover 

13 multiple grid cells, it would be a grid cell that's

14 representative of the whole domain. We also have other

15 recommendations in the guidance on postprocessing MMIF

16 outputs for AERMET and AERMOD.

17 We did some evaluations. Three case studies

18 represented here are the Gibson, Indiana SO2 study that

19 Indiana had done a paper on; also Martins Creek,

20 Pennsylvania, which is one of the AERMOD databases; and

21 Region 7 did Herculaneum, Missouri, which is a lead--the Doe

22 Run facility.

23 We did some evaluations of the met data and we

24 also did the AERMOD evaluations using the EPA protocol for

25 determining best performing model or the Cox-Tikvart
70

KAY McGOVERN & ASSOCIATES (919) 870-1600

Suite 117, 314 West Millbrook Road FAX 870-1603

Raleigh, North Carolina 27609-4306 (800) 255-7886

1 protocol, and you can see the link to our TSD at the bottom. 

2 Here's a map of the three areas. And just to note, all

3 these--none of these case studies used 15181. It wasn't

4 available at the time of the studies.

5 Here's the Gibson study area. It's southwest

6 Indiana. You see the two grid cells from WRF that contain

7 the facility, Gibson, and Evansville, the closest NWS station

8 used in the modeling.

9 This is a comparison of AERMOD output for the

10 different model runs. This is the model comparison measure,

11 which compares the composite performance metric of each of

12 the model simulations. Basically here, like Roger said

13 earlier, if you overlap zero, you know, statistically not

14 different. 

15 And as you can see highlighted in the red box, 

16 Gib MMIF, which is the MMIF output for the Gibson facility

17 versus the observed data for Gibson, we've got very good

18 agreement, almost a zero model composite metric, so that

19 statistically they're not different. And actually all

20 scenarios are not statistically different, so that was very

21 encouraging. I could just drop the mic and walk offstage

22 now, but I won't.

23 The next one is Martins Creek. Here's a map of

24 the study area near the New Jersey-Pennsylvania border. You

25 can see ABE, the Allentown weather service station as well to
71

KAY McGOVERN & ASSOCIATES (919) 870-1600

Suite 117, 314 West Millbrook Road FAX 870-1603

Raleigh, North Carolina 27609-4306 (800) 255-7886

1 the west.

2 Martins Creek, not as good performance as Gibson--

3 you know, complex terrain; we had 4 kilometer and 1 kilometer

4 grid cells to pick from as well as observe met data from the

5 site and the weather station that you can see. The 4

6 kilometer grid cell almost was statistically not different

7 from Martins Creek observed data at the 95th percentile. If

8 we had gone to the 99th, it wouldn't have probably been

9 statistically different. 

10 Also the 1 kilometers, you know, didn't perform as

11 well, but were not that bad compared to the weather service

12 station, which one of the goals of the evaluation was we

13 would hope MMIF was no worse than using National Weather

14 Service data. So I mean Martins Creek is not as good as

15 Gibson but still, you know, not that bad.

16 Finally, the Herculaneum study area: we had 4

17 kilometer, 12 kilometer, and 36 kilometer MMIF output as well

18 as on-site data at Herculaneum and the St. Louis airport off

19 to the northeast. And we couldn't do the detailed

20 statistical analysis for Herculaneum because these are lead

21 monitors, so they only had 24 hour data.

22 So we did a screening analysis in the Cox-Tikvart

23 protocol, where you take the top 25 concentrations and

24 calculate their mean bias and the standard deviation and plot

25 them against each other. And this small square you see in
72

KAY McGOVERN & ASSOCIATES (919) 870-1600

Suite 117, 314 West Millbrook Road FAX 870-1603

Raleigh, North Carolina 27609-4306 (800) 255-7886

1 the plot is the factor of 2 box, and usually if you're inside

2 that box you can continue with doing a detailed statistical

3 test on the one hour, 24 hour, and three hour averages, but

4 we didn't have one hour and three hour, so we stuck with 24

5 hour. If you're outside of that box usually the protocol

6 recommends no more analysis because the data already has some

7 credibility issues.

8 So we're really not performing--we're outside the

9 factor of 2 box and we're underpredicting. If your bias is

10 positive, that means that the model is underpredicting

11 because the obs are higher. While it's outside the factor of

12 2 box, if you notice the two--the MMIF runs, the green, blue

13 and purple, are fairly comparable to the Herculaneum on-site

14 data. 

15 Actually the airport data is doing better, but

16 there could be some emission issues. You know, they may not

17 be capturing all the emissions. This is, you know, a

18 smelter, so there may be some fugitives that may not be

19 characterized well.

20 So in summary, the Gibson data was pretty good,

21 you know, statistically not different. Martins Creek did

22 show some difference, but not too bad. And Herculaneum

23 indicated prognostic data performance was comparable to site

24 specific, while not great, but still was comparable. So, you

25 know, more work needs to be done. We anticipate comments on
73

KAY McGOVERN & ASSOCIATES (919) 870-1600

Suite 117, 314 West Millbrook Road FAX 870-1603

Raleigh, North Carolina 27609-4306 (800) 255-7886

1 the use of prognostic data.

2 And then finally, here are the links to the draft

3 guidance on MMIF and our TSD. And that's it for this

4 presentation.

5 Mr. Bridgers: Thank you, Dr. Thurman. I'm

6 going to give Tyler an extra few minutes because I know he'll

7 need it. While we're transitioning, I would also like to

8 remind everybody--I think I might need to do this after every

9 break; maybe I should do it before every break--is just to

10 remind everybody that EPA employees will not be able to

11 answer specific questions about the proposal, so if you ask

12 one of us other than Tyler, Chet, or myself and you get the

13 blank stare and then you can see the wheels spinning as to

14 what they can say, probably they shouldn't say anything.

15 Mr. Fox: Or they run away.

16 Mr. Bridgers: Or they run away. So that's

17 just a friendly reminder. They're not trying to be rude. 

18 They're just trying to respect the rulemaking process.

19 Mr. Fox: Thank you. All right. Well,

20 I'm going to address the issues related to long range

21 transport assessments and what we're proposing in the updates

22 to Appendix W.

23 Jumping right in with background, as you all are

24 aware in 2003 we revised the Guideline to formally recommend

25 and bring in CALPUFF as the preferred model for long range
74

KAY McGOVERN & ASSOCIATES (919) 870-1600

Suite 117, 314 West Millbrook Road FAX 870-1603

Raleigh, North Carolina 27609-4306 (800) 255-7886

1 transport, meaning source receptor distances of 50 kilometers

2 to several hundred kilometers for primary criteria

3 pollutants. 

4 It was intended and in practice used to address

5 PSD increment and in particular Class I assessments, and

6 therefore quite a bit of interaction with the federal land

7 managers, who under FLAG and in doing AQRV analysis would use

8 CALPUFF as well. So there were some joint efforts going on

9 there.

10 There's also some then issues that resulted in

11 that in terms of the FLMs having the ability under AQRV to be

12 more flexible in the specification of the CALPUFF model 

13 vis-à-vis how EPA proposed it and promulgated it for a

14 particular use for PSD increment.

15 So right now under the current guideline, it's the

16 preferred model for long range transport. Also, as

17 referenced in Appendix A, CALPUFF can also be considered on a

18 case by case basis as an alternative model, again, subject to

19 approval under Section 3.2, that process that we mentioned

20 earlier, for near-field applications where complex winds or

21 terrain warrant the use of a puff model.

22 So the Guideline acknowledged that in Appendix A

23 that the model could be used, again, following the appro24 priate processes to get approval as an alternative model, and

25 that would have to be shown as of 2005 vis-à-vis the
75

KAY McGOVERN & ASSOCIATES (919) 870-1600

Suite 117, 314 West Millbrook Road FAX 870-1603

Raleigh, North Carolina 27609-4306 (800) 255-7886

1 preferred model in those instances, which would be AERMOD. 

2 And we've got I think a number of examples. One

3 is the New Jersey 126 situation where there was a comparison

4 made and I think is a very appropriate comparison to look at

5 how we went about comparing those two models and then

6 ultimately determining in that situation that there was not a

7 sufficient difference and given the application that AERMOD

8 was appropriate in that use. And the agency went forward in

9 that 126 action with AERMOD as the basis for the demon10 stration of a violation and for the consideration of controls

11 in that case for the Portland generating station.

12 So what are we doing in the proposed revisions to

13 the Guideline? Well, in Section 4 we are proposing to remove

14 CALPUFF as a preferred a model for long range transport, and

15 rather we're recommending that it be used as a screening--

16 excuse me, screening technique; it gets me choked up--a

17 screening technique along with other Lagrangian models for

18 addressing PSD increment in those situations beyond 50

19 kilometers.

20 And so we're no longer providing it preferred

21 status. We're using it in a screening technique that, as

22 I'll describe, we think is more appropriate given the

23 situation for use in the context of PSD increment, and it

24 opens the field for other Lagrangian models to be used. 

25 There are other models, SCIPUFF and other things. So again,
76

KAY McGOVERN & ASSOCIATES (919) 870-1600

Suite 117, 314 West Millbrook Road FAX 870-1603

Raleigh, North Carolina 27609-4306 (800) 255-7886

1 it provides more flexibility for the community to use those

2 models as appropriate.

3 As I mentioned earlier, we've also--given the work

4 that James and Chris Owen did, we conducted an analysis--I

5 don't have the TSD link, but there's a technical support

6 document that is referenced that demonstrates the analyses

7 done based on the AERMOD Implementation Workgroup scenarios

8 that we feel and we've stated that near-field modeling is

9 sufficient to address whether a source will cause or

10 contribute to a NAAQS violation, so EPA is not considering a

11 long range transport assessment beyond 50 kilometers

12 necessary for inert pollutants. So for NAAQS you're dealing

13 with a near-field situation, you're applying AERMOD or an

14 appropriately approved alternative model, and that's

15 sufficient.

16 Again, under the current revisions CALPUFF or any

17 other Lagrangian model could still be available for us in the

18 near field as an alternative model subject to approval, so

19 there's no change in the status of the model in that context

20 other than not specifically pointing it out. And I will

21 notice for folks, we don't point out any models in Section 5

22 or Section 6. I mean CMAQ, CAMx, other models--we're

23 purposely not trying to specify models unless they are a

24 preferred model so that there's no inference made about those

25 models. 
77

KAY McGOVERN & ASSOCIATES (919) 870-1600

Suite 117, 314 West Millbrook Road FAX 870-1603

Raleigh, North Carolina 27609-4306 (800) 255-7886

1 We recognize that there's going to be evolution. 

2 There's going to be changes in those models. There's going

3 to be changes in other models in terms of their availability. 

4 And so we've reserved that for guidance and the like, but

5 Appendix W itself does not infer any preference at all in

6 terms of acknowledging those types of models.

7 And so what do you mean, Tyler, by screening

8 approach for PSD increment? Well, Section 4 lays that out

9 explicitly. We, again, recognize that long range transport

10 assessments may be necessary in limited situations. We've

11 engaged with the regional offices--Region 4, Stan Krivo;

12 Region 6, Eric Snyder among others--to understand what their

13 experiences have been over the past ten plus years. 

14 And again, as I said earlier, going down the road

15 to doing a Class I PSD increment analysis, my understanding

16 is that you can count them on one hand, so we're talking

17 about a very limited situation. And so having a screening

18 approach was deemed both appropriate and necessary in these

19 revisions.

20 So the first step would be for your near-field

21 application of the appropriate model--as I said, AERMOD or an

22 alternative model, based on approval--you would determine the

23 level of significance of those ambient impacts from your new

24 or modifying source at or around 50 kilometers. You'd have a

25 circle of receptors that would tell you that. Again, the
78

KAY McGOVERN & ASSOCIATES (919) 870-1600

Suite 117, 314 West Millbrook Road FAX 870-1603

Raleigh, North Carolina 27609-4306 (800) 255-7886

1 experience will tell you that the vast majority of situations

2 will screen out at that point in time.

3 If you don't screen out in that instance, then the

4 second step would be in consultation with the regional office

5 you determine the appropriate screening approach using

6 CALPUFF or any other Lagrangian puff model to determine the

7 significance at specific Class I areas of concern. 

8 You're dealing with a specific new or modifying

9 source. You know those Class I areas that are within a

10 reasonable transport distance, and you can look to those

11 specific receptors to determine what the significance levels

12 are in those cases. Again, the vast majority of situations

13 are expected to screen out--if they even get to that second

14 step, to screen out at that time.

15 If they don't screen out, then for those limited

16 situations you would have to conduct a cumulative impact

17 analysis, and I think memory didn't serve any of us well in

18 terms of being able to point to a situation where that

19 actually had occurred, so if there's public comment to

20 address and remind us of that, that would be appreciated. 

21 And then the selection and use of a model would be determined

22 through approval under Section 3.2.2(e), alternative model.

23 So that lays out the screening approach--again,

24 streamlining the approach in terms of what models you have to

25 use, having them, you know, and the approach be warranted to
79

KAY McGOVERN & ASSOCIATES (919) 870-1600

Suite 117, 314 West Millbrook Road FAX 870-1603

Raleigh, North Carolina 27609-4306 (800) 255-7886

1 the nature of the problem. And so we feel as if it was

2 appropriate to offer this flexibility and to reduce the

3 burden on the user community.

4 Then in Section 5 in terms of addressing secondary

5 pollutant impacts we feel that by not specifying a preferred

6 model we actually provide a lot of flexibility to the user

7 community in estimating these single source secondary

8 pollutant impacts with more appropriate modeling techniques. 

9 We stress the full chemistry photochemical models in the

10 preamble, and a number of those do address science issues of

11 Lagrangian models and in particular CALPUFF, and I'll note

12 some of those in the next slide.

13 And based on the IWAQM, Interagency Workgroup of

14 Air Quality Modeling, the Phase 3 effort, there are reports

15 as well as published literature that support our decisions. 

16 And we've placed the emphasis on use of those chemical

17 transport models or techniques that reflect the state of the

18 science in atmospheric chemistry so that we're applying the

19 best science in those situations.

20 And again, we've got guidance. Kirk Baker and Jim

21 Kelly put together a detailed guidance to support Section 5

22 for ozone and secondary PM2.5, and we will reply upon the

23 regional offices and others and the community at large as

24 these models are there and developed and techniques within

25 those models are improved upon to allow them for use here,
80

KAY McGOVERN & ASSOCIATES (919) 870-1600

Suite 117, 314 West Millbrook Road FAX 870-1603

Raleigh, North Carolina 27609-4306 (800) 255-7886

1 tools like source apportionment, other instrumented

2 techniques, and Kirk will get into that in more detail

3 shortly.

4 Then the preamble discusses in the section for

5 long range transport future considerations for visibility

6 modeling with full chemistry photochemical models. We're

7 limited in our ability to do evaluations with respect to

8 visibility, and so we'll be working very closely, have been

9 working very closely through the three phases of IWAQM with

10 our federal partners. 

11 And we feel as if--and as described in the

12 preamble that consistent with what we're doing for ozone and

13 secondary PM2.5 under PSD that as these techniques are used

14 and improved that their application for AQRV analysis for

15 visibility and perhaps even in the regional haze context

16 would not only provide improved science, but harmony and

17 consistency with the models used in other aspects of the

18 Clean Air Act programs.

19 And so it reduces the number of models you're

20 carrying around. It reduces decisions and flexibilities of

21 determination of what knowledge to work with those models and

22 starts focusing us on best science and allows the community

23 to then focus on developments and research and the like

24 there. 

25 And I think that's evidenced through work that
81

KAY McGOVERN & ASSOCIATES (919) 870-1600

Suite 117, 314 West Millbrook Road FAX 870-1603

Raleigh, North Carolina 27609-4306 (800) 255-7886

1 EPRI has done with SCICHEM from SCIPUFF and the bay releases

2 that they've done and we'll hear later in the public comment

3 about. And so I think there's the community there to develop

4 and improve these models, and we've provided the--I think the

5 impetus to continue that development and leverage the

6 development that's gone on to establish what we've done in

7 Section 5.

8 So I mentioned the limitations, and so this was

9 documented in EPA's 2009 reassessment, and there was a

10 modification through a memo to the docket to add conclusory

11 or summary statements, and this is part of that.

12 The chemical conversion algorithms in the

13 regulatory versions are quite old, and they're pretty

14 inconsistent with our current knowledge and state of the

15 science in terms of secondary PM2.5 formation. 

16 And even the more recent chemistry algorithms

17 still don't contain photochemical reactions that are

18 important to simulate secondary PM formation. They're not

19 the type of full chemistry model that we feel is necessary

20 and appropriate. 

21 And it does not estimate ozone formation from

22 single sources, which is something that now under Section 5

23 and Appendix W and through guidance we are looking for and

24 expecting.

25 So--and then in a wide variety of situations where
82

KAY McGOVERN & ASSOCIATES (919) 870-1600

Suite 117, 314 West Millbrook Road FAX 870-1603

Raleigh, North Carolina 27609-4306 (800) 255-7886

1 we've tested and evaluated the model, there's just a lot of

2 variation in terms of an unexplained and very difficult to

3 comprehend and understand sensitivity of the dispersion model

4 with the CALMET meteorological input that necessitated

5 putting a preset to CALMET by EPA in conjunction with the

6 FLMs to try and make it a more manageable process and

7 understand and provide more credibility in the modeling

8 results. 

9 And so it's just been a challenge for us dealing

10 with this model over the past ten years, and unfortunately

11 the community has not come together as was expected to really

12 work on those types of developments, broadly speaking.

13 And to that point we also issued a memo related to

14 concerns about the management and maintenance of the model. 

15 The interactions between EPA and the model developer have

16 been complicated by the changes in ownership and the

17 uncertainty of the development process. That's just a fact. 

18 We're not trying to say anything that is anything other than

19 just a fact of our experience and our observations. 

20 And as EPA and as being responsible for a

21 preferred model in Appendix W, it becomes an obligation on

22 the federal government, and we have memos and other things

23 that are in the docket establishing that relationship, and it

24 has just been difficult to adhere to those in a very

25 transparent and open manner. One example is the process that
83

KAY McGOVERN & ASSOCIATES (919) 870-1600

Suite 117, 314 West Millbrook Road FAX 870-1603

Raleigh, North Carolina 27609-4306 (800) 255-7886

1 we went through in updating the VISTAS version of CALPUFF,

2 and that was discussed and summarized in detail at the 9th

3 Modeling Conference.

4 There have been a number of updates to the CALPUFF

5 modeling system just as there have been a number of updates

6 to AERMOD in terms of the regulatory version. It's just that

7 process has been a little hit or miss in terms of under8 standing and knowing what's coming and communication to both

9 EPA and the broader community in terms of those things. 

10 And there's been the parallel development process

11 with the series 6 versions, which has just caused a lag in

12 our ability to adequately understand, to review, and

13 ultimately approve changes in a timely fashion. And it's

14 largely due to a lack of an open development process.

15 And then we recently in the latter part of June

16 were hit with from the current owner of CALPUFF a version 7

17 version of the model with no prior notice in the middle of

18 this rulemaking, and again, it makes it very difficult, very

19 awkward for the agency to proceed with what it needs to with

20 that type of process. So we do believe that it's been unduly

21 complicated by these changes, and it's already a complex

22 model, a complex world to apply it in. 

23 And so it--when we're talking about a preferred

24 model that has status and that the EPA has ownership

25 obligations if deemed necessary, one option is to take the
84

KAY McGOVERN & ASSOCIATES (919) 870-1600

Suite 117, 314 West Millbrook Road FAX 870-1603

Raleigh, North Carolina 27609-4306 (800) 255-7886

1 model under our own roof. We've got difficulty enough

2 maintaining AERMOD and other models and adequately staffing

3 and supporting the regions in the permit arena, so that would

4 be a totally unfeasible option for us to do. 

5 And again, as I said, there are other models out

6 there. We've got a screening approach that adequately meets

7 the regulatory needs, and so from the standpoint of moving

8 forward we feel as if the changes that we're proposing are

9 not just warranted but in everybody's best interest.

10 And in terms of the Regional Haze Program, we did

11 issue a 2005 guideline separately for the BART requirements

12 under Regional Haze Rule, and that did recommend at the time

13 because there really was no other model capable--at that

14 point in time photochemical models had not been really--they

15 had been some--some had been instrumented with these types of

16 instrumented techniques, but they really hadn't been fully

17 evaluated and understood and put into practice.

18 So CALPUFF was available for single source assess19 ments. Again, in that process we acknowledge the lack of

20 full evaluation, but it did provide information in a

21 multifactor decision making process under BART. Again, it

22 wasn't the sole determination of things as it would be under

23 a preferred model situation in terms of whether or not you

24 are complying. It was a factor in a multifactor decision

25 framework, and so we felt comfortable in that context.
85

KAY McGOVERN & ASSOCIATES (919) 870-1600

Suite 117, 314 West Millbrook Road FAX 870-1603

Raleigh, North Carolina 27609-4306 (800) 255-7886

1 And in that we also did allow states the ability

2 to use alternative models, and some did use photochemical

3 models and have used photochemical models. The EPA itself

4 has used photochemical models in this context in consultation

5 with the EPA regional offices. So I think as the science has

6 evolved the process is flexible and fluid enough to bring

7 those in so that the best science is used in this context.

8 That said, the proposed changes do not affect the

9 recommendation from 2005 and past and current BART

10 applications of that model, and so adhering to Appendix W and

11 going through the appropriate process as folks have is still

12 in place, and we do not--we want to make sure that everybody

13 knows that we do not feel that any of the changes that we're

14 proposing which need to move us forward should be retro15 actively looked at in terms of these things.

16 We don't do that in any situation, you know. We

17 don't go back and reevaluate permits, you know, that were

18 done with older versions of the model. There's a reason. 

19 You have to respect that, but yet you have to also respect

20 the evolution of the science and the better science because

21 that will always change and evolve.

22 So in summary, just to close, so we're proposing

23 to remove CALPUFF as a preferred model in Appendix A

24 specifically for long range transport, and we're recommending

25 that it be used instead as a screening technique along with
86

KAY McGOVERN & ASSOCIATES (919) 870-1600

Suite 117, 314 West Millbrook Road FAX 870-1603

Raleigh, North Carolina 27609-4306 (800) 255-7886

1 other Lagrangian models for assessing PSD increment beyond 50

2 kilometers.

3 For NAAQS demonstrations based on the analyses

4 that we've done, and we welcome comment and new other source

5 sector scenarios that can be fully evaluated to support our

6 determination or question it, however the case may be, that

7 you would not conduct a NAAQS analysis outside of 50

8 kilometers for inert pollutants.

9 There's no change in the ability to use CALPUFF,

10 again, or any other Lagrangian model, or other Gaussian model

11 for that case, in the near field as an alternative model for

12 low wind, low terrain, and other specific situations in which

13 AERMOD, the preferred model, isn't working or beta options

14 available in AERMOD are not working. You have that alterna15 tive model approach available, and that flexibility has

16 always been there and we continue that.

17 And along the line of flexibility, the user

18 community has that in estimating single source secondary

19 impacts, and we will continue to evolve. We've in Appendix W

20 provided a broad framework, an appropriate framework, that we

21 feel meets the requirements under the Sierra Club petition in

22 terms of establishing models and/or techniques with reason23 able particularity. 

24 We've done that in Appendix W with subsequent

25 guidance that supports that and that that allows for the
87

KAY McGOVERN & ASSOCIATES (919) 870-1600

Suite 117, 314 West Millbrook Road FAX 870-1603

Raleigh, North Carolina 27609-4306 (800) 255-7886

1 appropriate use of chemical transport models, and in some

2 cases Lagrangian puff models may be appropriate to use in

3 that context, and we provide the appropriate context for

4 those used.

5 So again, we're opening the field up. We're

6 allowing flexibility in the user community to appropriately

7 address the problems that they have, and we, again, have a

8 framework and a process by which it can happen and it can be

9 effectively communicated in a transparent way. 

10 And as we update the Guideline, you know, we

11 hopefully don't have another decade go by, and I doubt we

12 will be able to let another decade go by, given the advances

13 and the need to continue to refine the Guideline, to continue

14 to refine the models. We'll certainly be continuing to

15 evolve what's in Appendix W, what's in the guidance, and our

16 preferred models to respect that. So I think that is it. 

17 Thank you.

18 Mr. Bridgers: Thank you, Tyler. So we're

19 getting back on schedule, if there's a schedule we must keep. 

20 We'll transition from the discussion that Tyler just gave on

21 long range transport and CALPUFF to a presentation from Kirk

22 Baker, et al. about the treatment of PM2.5 and ozone in PSD

23 compliance demonstrations.

24 Dr. Baker: All right. Thanks, George. 

25 The first thing I want to do is apologize to the rest of my
88

KAY McGOVERN & ASSOCIATES (919) 870-1600

Suite 117, 314 West Millbrook Road FAX 870-1603

Raleigh, North Carolina 27609-4306 (800) 255-7886

1 group for not wearing a tie, so I guess we'll keep this a

2 little more informal in this talk.

3 So secondary pollutants for single source impacts,

4 I'm going to talk a little bit about that today. As Tyler

5 mentioned, EPA granted a Sierra Club petition in January 2012

6 with a commitment to update the Guideline on Air Quality

7 Models to address ozone and secondary PM2.5 impacts. The

8 current version of the Guideline on Air Quality Models has

9 very little information about how one would go about

10 estimating the impacts from single sources for ozone and

11 secondary PM2.5.

12 So in response to that petition we now have an

13 entire new chapter in the Guideline, Chapter 5, that's

14 focused totally on secondarily formed pollutants speaking to

15 ozone and PM2.5, and we have a Chapter 6 that's focused on

16 visibility, deposition, and air quality related values. 

17 It's similar to the older Chapter 6. It retains

18 some of those elements, but if people remember the old

19 Chapter 6 it was kind of a hodgepodge of a lot of incongruous

20 information, so now it's just totally focused on air quality

21 related values and other governmental programs.

22 The intent that we had in going through and making

23 these updates to Appendix W is that the updates we would make

24 would be an appropriate level of detail that is going to be

25 relevant over the long term and put the more dynamic
89

KAY McGOVERN & ASSOCIATES (919) 870-1600

Suite 117, 314 West Millbrook Road FAX 870-1603

Raleigh, North Carolina 27609-4306 (800) 255-7886

1 information that would be reflecting the current practice of

2 model application into guidance documents, which are going to

3 be more dynamic and could be more fluid and updated to

4 reflect the state of the practice going forward so we don't

5 always need to go back to rulemaking to update the Guideline

6 when new things come about.

7 So the process for updating Appendix W for the

8 secondary pollutants, the Interagency Workgroup on Air

9 Quality Modeling, IWAQM, has been a process that has

10 historically been used for collaboratively updating regula11 tory air quality modeling approaches.

12 So we reinitiated the IWAQM process and called it

13 Phase 3 in July of 2013 so we had a mechanism for working

14 collaboratively with our EPA regional office partners and

15 partners at the other federal agencies to update the Appendix

16 W, update or develop new guidance documents where necessary.

17 So the goal with this process was to just start to

18 understand and identify credible modeling techniques for

19 single source secondary impacts for ozone and PM2.5. This

20 type of work had been done in the past but not an enormous

21 amount of work, so in a lot of ways we were starting with

22 kind of a clean slate, especially on the ozone side, and just

23 trying to understand what types of tools are appropriate for

24 this, and if someone were going to use these types of tools,

25 how best should they be applying them for this type of
90

KAY McGOVERN & ASSOCIATES (919) 870-1600

Suite 117, 314 West Millbrook Road FAX 870-1603

Raleigh, North Carolina 27609-4306 (800) 255-7886

1 purpose. A lot of these tools have been used for other

2 purposes and we just wanted to make sure that when used for a

3 permit type application that they would be used in the most

4 appropriate way possible.

5 So in Phase 3 IWAQM consisted of two different

6 working groups. There was a near-field impacts working group

7 that was largely EPA regional office and OAQPS staff, and

8 there was also a long range transport workgroup, which is

9 more similar to the past IWAQM phases that people might be

10 more familiar with. So out of that we have technical reports

11 and guidance documents to support the proposed revisions to

12 the air quality modeling guideline.

13 So this looked pretty good on my computer. It

14 probably doesn't look too good here from where I'm standing,

15 but this is kind of a schematic of the different pieces of

16 the puzzle that we were updating through that IWAQM process. 

17 And up on the top we've got Appendix Q updated Chapters 5 and

18 6 and the preamble language that was relevant to those two

19 chapters, so that was the main, overarching goal was to

20 update Appendix W for single source secondary impacts.

21 And below that we've got kind of increasingly

22 dynamic documents. We've got the high level guidance

23 documents and moving down into technical reports that kind of

24 provide a snapshot of what the world is right now in terms of

25 the technical approaches that are available for us in these
91

KAY McGOVERN & ASSOCIATES (919) 870-1600

Suite 117, 314 West Millbrook Road FAX 870-1603

Raleigh, North Carolina 27609-4306 (800) 255-7886

1 single source impacts in the near field and long range

2 transport.

3 So on the left side we've got the PM Modeling

4 Guidance that had already been put together. We didn't work

5 on that, but we did develop a new guidance document for using

6 models for single source secondary impacts for ozone and

7 PM2.5. 

8 And so the idea behind this is if people are

9 familiar with guidance that we have put out for things like

10 nonattainment demonstrations, the intent here was to provide

11 something similar so that people would know if you're going

12 to use a chemical transport model for the purposes of

13 estimating single source impacts, how would you set it up and

14 apply it for doing a PSD permit type of application. So we

15 wanted to have all that information in one place. That's the

16 intent of that.

17 And then below that we've got--the IWAQM Phase 3

18 near-field group had a technical report that just kind of

19 details where we see the science and the feel of that right

20 now with respect to doing these types of assessments.

21 On the right-hand side the long range transport,

22 the main guidance document being the Federal Land Managers'

23 Air Quality Related Values Work Group Phase I report, the

24 FLAG guidance document. A lot of people are probably

25 familiar with that, and so that's going to be--that was not
92

KAY McGOVERN & ASSOCIATES (919) 870-1600

Suite 117, 314 West Millbrook Road FAX 870-1603

Raleigh, North Carolina 27609-4306 (800) 255-7886

1 updated as part of this process. We expect the federal land

2 managers to take up a process moving forward to update that

3 if they feel it's appropriate.

4 And below that there is also a Phase 3 report from

5 the Long Range Transport Group that again kind of provides a

6 synopsis of the state of the practice and science related to

7 long range transport modeling for air quality related values.

8 Then at the very bottom, which probably most

9 people in the room can't see, is just--there's a lot of

10 technical reports from EPA, a lot of external reports that

11 some people in this room have put together and things in the

12 literature that we used to inform these reports and the

13 guidance.

14 So this is just an outline of what's actually in

15 Appendix W Chapter 5. This is the section on Models for

16 Ozone and Secondarily Formed Particulate Matter. There's a

17 discussion of what ground level ozone and secondary PM2.5

18 generally is. There are also some broad recommendations

19 about what types of modeling systems would be appropriate for

20 either doing a single source permit type of assessment or for

21 doing a nonattainment demonstration, which would be a multi22 source projected type of modeling assessment for secondary

23 pollutants.

24 So what we've tried to do in Chapter 5 is really

25 clearly delineate using air quality models for nonattainment
93

KAY McGOVERN & ASSOCIATES (919) 870-1600

Suite 117, 314 West Millbrook Road FAX 870-1603

Raleigh, North Carolina 27609-4306 (800) 255-7886

1 demonstrations for NAAQS, which would be kind of multisource

2 or all source projected future year assessment of a control

3 strategy and also have--clearly differentiate the approaches

4 necessary for doing a secondary impact assessment for a

5 permit. So we've got both of those things in there so it's

6 very clear for ozone and similar information for secondary

7 PM2.5.

8 So the highlights for Chapter 5--this is a totally

9 new chapter in Appendix W. As I mentioned, we wanted to have

10 a very clear distinction between nonattainment planning for

11 NAAQS and permit assessments. We want to emphasize the

12 importance of developing modeling protocols and consultation

13 with the reviewing authority.

14 As Tyler mentioned, what we're doing is we're

15 putting forth a screening approach without a preferred model. 

16 We don't even really mention a lot of model names because,

17 given the length of time it usually takes to update these, a

18 lot of times when you go back and read Appendix W it's like

19 pulling out a time capsule and you see references to models

20 that you forgot ever existed or, you know, you don't even

21 know what the reference is supposed to be because nobody has

22 any idea what that model was back at that time. So what

23 we're trying to is just kind of focus on high level informa24 tion and not get into a lot of specific details with model

25 names and things like that.
94

KAY McGOVERN & ASSOCIATES (919) 870-1600

Suite 117, 314 West Millbrook Road FAX 870-1603

Raleigh, North Carolina 27609-4306 (800) 255-7886

1 The other thing that Chapter 5 puts forth is a

2 multitiered approach for single source permit assessments. 

3 We don't expect every single permit assessment to have to do

4 a rigorous, full scale photochemical transport model type of

5 assessment. There's going to be a multitiered approach, one

6 that's going to be using existing information where it's

7 appropriate and available and seeing if that's going to

8 provide the information that will work for the assessment in

9 consultation with the reviewing authority. 

10 And then beyond that if necessary we expect there

11 will be less situations where people would need to use a

12 photochemical or a Lagrangian chemical transport model. But

13 in situations where we do get into that, we do emphasize that

14 it's really important to use techniques that reflect the

15 state of the science (coughing). Like Tyler, this is also

16 very emotional for me. It's been a long three years since

17 the petition was agreed to.

18 Mr. Fox: We're almost there, Kirk.

19 Dr. Baker: I had no idea how this was

20 going to change my life. So some of the broader considera21 tions for ozone and secondary PM2.5 permit modeling, we put

22 forth this idea of MERP, the Model of Emission Rate for

23 Precursors. And information about this has been included in

24 the docket. So we're expecting to have this as part of

25 future rulemaking and possibly guidance.
95

KAY McGOVERN & ASSOCIATES (919) 870-1600

Suite 117, 314 West Millbrook Road FAX 870-1603

Raleigh, North Carolina 27609-4306 (800) 255-7886

1 So a MERP is not going to replace the significant

2 emission rate for permit assessments for determining the

3 applicability of the PSD requirements for sources with

4 emissions above the SER. However, a MERP would represent a

5 level of emissions of precursors that is not expected to

6 contribute significantly to concentrations of secondarily

7 formed PM2.5 or ozone.

8 So if a source has emissions above the SER but

9 below the MERP, we may not expect that additional technical

10 demonstrations would be necessary at that point, but still

11 that would need to be totally determined on a case by case

12 basis with the reviewing authority.

13 So the idea for the MERP is just kind of an

14 initial screening to screen out people that we don't--that we

15 think are small and the emissions are not going to result in

16 an impact that would be at the level of the SIL in any place,

17 so we want to--the idea is to have a conservative estimate.

18 You know, we think no matter where the source is, those

19 emissions of NOx or SO2 would not result in secondary PM2.5

20 above the SIL anywhere, and similarly for MERPs for VOC and

21 NOx for ozone.

22 So as I mentioned, I think there's a separate

23 document that's been submitted to the docket where it

24 outlines how MERPs fit into the permitting process, so in the

25 past in the PM2.5 modeling guidance, people probably remember
96

KAY McGOVERN & ASSOCIATES (919) 870-1600

Suite 117, 314 West Millbrook Road FAX 870-1603

Raleigh, North Carolina 27609-4306 (800) 255-7886

1 the flow charts where if your emissions are above the SER and

2 depending on whether you're in an attainment area or a non3 attainment area you kind of go through different processes to

4 determine what types of quantitative assessments may or may

5 not be necessary for you and what types of controls may or

6 may not be necessary. So there's a document that updates

7 that and includes how the MERPs fit into that process.

8 So with the guidance on the use of models for

9 assessing the impacts of emissions from single sources on the

10 secondarily formed pollutants ozone and PM2.5, we've provided

11 guidance so people know what to do for permit assessments. 

12 And I want, you know, to just reemphasize that we

13 expect that a lot of sources will be screened out through the

14 MERPs once those are available. And if they are above the

15 MERP, then a first and possibly second tier assessment may be

16 necessary. And those two tiers are broadly outlined in

17 Appendix W, and we have more information about those tiers in

18 this guidance document.

19 So for first tier assessments, it's generally

20 expected that applicants would use existing empirical

21 relationships between precursors and secondary pollutants

22 based on credible and relevant modeling that already exists

23 and detailed in this guidance.

24 It's also possible that some screening approaches

25 could be developed based on full science photochemical
97

KAY McGOVERN & ASSOCIATES (919) 870-1600

Suite 117, 314 West Millbrook Road FAX 870-1603

Raleigh, North Carolina 27609-4306 (800) 255-7886

1 transport modeling systems such as reduced form models, and

2 this could provide information that might satisfy the first

3 tier requirement in some situations.

4 So the use of preexisting credible technical

5 information or a screening model for the purposes of

6 estimating single source secondary impacts would be

7 considered on a case by case basis and done in consultation

8 with the appropriate review authority. So again, we're

9 trying to provide a lot of opportunity for people to do a

10 credible assessment of their emissions against a SIL but not

11 necessarily have to go right into doing a full scale,

12 rigorous chemical transport analysis.

13 So a second tier assessment could be necessary,

14 and when that would be necessary we have guidance on how you

15 set up the air quality models, inputs, what kind of run time

16 options might be necessary, how you would set up the

17 receptors, and how you would do the postprocessing in order

18 to appropriately assess the impacts of a project source on

19 ozone and secondary PM2.5. 

20 And even within the second tier in Appendix W when

21 you get into that situation, we kind of had a subtier set up

22 where there's different levels of rigor, so you could do

23 something a little bit less rigorous and take a more

24 conservative impact being estimated for the project source or

25 you could do something more refined and complicated, and
98

KAY McGOVERN & ASSOCIATES (919) 870-1600

Suite 117, 314 West Millbrook Road FAX 870-1603

Raleigh, North Carolina 27609-4306 (800) 255-7886

1 there might be some leeway to move off of the most

2 conservative possible estimate. Those are the things that

3 would be laid out in a modeling protocol and agreed upon with

4 the reviewing authority. But we just want to emphasize that

5 we're trying to build a lot of flexibility into this for

6 people.

7 So for second tier assessments we do generally

8 recommend that chemical transport models be used for single

9 source ozone and secondary PM2.5 impacts. Chemical transport

10 models broadly include Lagrangian puff models and Eulerian

11 grid models such as photochemical transport models.

12 One challenge with Lagrangian puff models is they

13 need a realistic chemical environment, so you need an input,

14 a three dimensionally varying set of oxidants and mutualizing

15 agents, so you need to get that information from somewhere

16 else, and it could be--you could get that from a photo17 chemical transport model because photochemical transport

18 models do estimate a generally realistic or usually realistic

19 chemical environment, and that output could be used as input

20 to a Lagrangian model if people are interested.

21 And there certainly could be some situations where

22 the three dimensional environment around a project source and

23 key receptors isn't that complicated. You might not need to

24 go to that type of rigor, but that is something that would

25 be, again, decided on a case by case basis.
99

KAY McGOVERN & ASSOCIATES (919) 870-1600

Suite 117, 314 West Millbrook Road FAX 870-1603

Raleigh, North Carolina 27609-4306 (800) 255-7886

1 When using photochemical transport models, we've

2 got a lot of information in the guidance about how they would

3 be used for this purpose. Even though single source

4 emissions are injected into a grid volume, we have done

5 comparisons with in-plume measurements, and this suggests

6 that grid based models can provide appropriate downwind

7 secondary impacts when they're set up and applied appro8 priately for that particular purpose. So we do have

9 confidence that these models do work for single source permit

10 types of assessments.

11 But having said that, clearly given that, you

12 know, there's not an enormous amount of information available

13 up to this point, further testing is needed for different

14 types of modeling systems, both Lagrangian and Eulerian, to

15 better understand what configurations are going to be the

16 most appropriate for permit types of assessments and build

17 upon a broader base of knowledge so that we can understand in

18 different parts of the country and even in different parts

19 maybe of particular urban areas how much secondary PM or how

20 much ozone would we expect to see from different levels of

21 precursor emissions.

22 So I think that's going to be important going

23 forward is just building upon that body of knowledge and

24 seeing how variable that's going to be from place to place

25 and even within a particular place.
100

KAY McGOVERN & ASSOCIATES (919) 870-1600

Suite 117, 314 West Millbrook Road FAX 870-1603

Raleigh, North Carolina 27609-4306 (800) 255-7886

1 So the IWAQM3 Near-field Impacts Group updated the

2 preamble and Chapter 5, which I mentioned this new guidance

3 document, which is available in the docket, which I just

4 talked about. And there's also a summary report that talks

5 about what we know right now about the relationship between

6 single source precursors and downwind secondary impacts. 

7 There's an overview of published emissions and

8 secondary impacts from single sources to provide some context

9 for what we expect in terms of impacts from these types of

10 sources, and it also talks a little bit about recommended

11 models, approaches, and tools for these types of assessments

12 that are available now.

13 So estimating source contributions with chemical

14 transport models, Lagrangian puff models are pretty straight15 forward. They usually just output the project source

16 impacts. When you use something like a photochemical grid

17 model that contains all the sources, it's really not that

18 complicated, but you just want to keep in mind that it could

19 involve two different simulations, that the simplest way to

20 get the single source impacts from photochemical grid model

21 simulation would be to do a model simulation with all the

22 sources and the project source at preconstruction levels and

23 do a second simulation with all the same sources not changed

24 and the project source at postconstruction levels.

25 And what you would do is just difference those two
101

KAY McGOVERN & ASSOCIATES (919) 870-1600

Suite 117, 314 West Millbrook Road FAX 870-1603

Raleigh, North Carolina 27609-4306 (800) 255-7886

1 things and find out what the impacts on ozone or secondary

2 PM2.5 is from your project source. And that's what's

3 represented in the schematic that most people unfortunately

4 from about the fourth or fifth row back probably can't see,

5 but we've got the baseline on the left with the source

6 modification compared to the baseline in the middle. 

7 And on the right you can clearly see with the

8 spatial plot the warmer colors being the higher impacts

9 nearest the source itself, and they kind of fall off as you

10 get further away from the source. And it varies direction11 ally based on the meteorology. So it's kind of a physically

12 realistic impact that we're seeing when we use these types of

13 models. 

14 And alternatively, there's more complicated things

15 you can do with a photochemical transport model if you use

16 extensions like source apportionment or DDM. You could track

17 the model--you could track the contribution of a particular

18 source through the model without a second model simulation,

19 although that does require some additional resources.

20 Real briefly on Chapter 6, this is the section--

21 now it's just focused on air quality related values and other

22 governmental programs, so Chapter 6 just kind of talks about

23 what are air quality related values, how do the FLMs fit into

24 this picture, and what is the appropriate guidance, and here

25 it would be the FLAG guidance.
102

KAY McGOVERN & ASSOCIATES (919) 870-1600

Suite 117, 314 West Millbrook Road FAX 870-1603

Raleigh, North Carolina 27609-4306 (800) 255-7886

1 So in the past, as I mentioned before, Chapter 6

2 comprised a lot of really incongruous information. It had

3 GEP information in there along with long range transport

4 modeling, so it is really focused on visibility and

5 deposition and other programs.

6 I'll emphasize again as Tyler mentioned using

7 chemical transport models for these types of purposes, and we

8 expect the specific guidance that people refer to would be

9 looking at the FLAG guidance document. Specific guidance for

10 models and model applications are also available from the FAA

11 for airports and from BOEM for offshore sources that are

12 within their jurisdiction. 

13 If it's an offshore source that's within EPA's

14 jurisdiction, then you would refer to other parts of the

15 Guideline on Air Quality Models, Appendix W, for information

16 about doing those types of assessments. And Tyler also

17 mentioned that the screening approach for primary pollu18 tants, that's in a different section of the Guideline on Air

19 Quality Models.

20 So finally, the IWAQM3 and Long Range Transport

21 Group worked on updating the preamble and Chapter 6, and

22 there's also in the docket a report from that group that

23 talks about recommended models, approaches for long range

24 transport assessments of secondary pollutants including

25 visibility and deposition.
103

KAY McGOVERN & ASSOCIATES (919) 870-1600

Suite 117, 314 West Millbrook Road FAX 870-1603

Raleigh, North Carolina 27609-4306 (800) 255-7886

1 Mr. Bridgers: Thank you, Kirk. And it looks

2 like there's an assurance if I can keep my comments to time

3 that everyone will have a longer lunch break. I'm the emcee

4 and the conference host, so I have some prerogative that I'm

5 going to take. I have two talks scheduled now on your

6 agenda. If you see them, I'm going to reverse them, and I'll

7 explain why.

8 I don't know if it was late one night, I don't

9 know if it was early one morning when I put this agenda

10 together and I just randomly put my presentations on there,

11 and then I realized last night about 9 o'clock--I'm like,

12 "Er, I really should talk in the other order."

13 A subtle feature that we didn't announce: the

14 agenda today across the morning largely follows the preamble

15 and the proposed actions that we have. And so to talk about

16 the Clearinghouse needs to happen before we talk about the

17 final Chapter 8 and Chapter 9, so I'm going to take the next

18 ten minutes--and good Lord, I need this--to talk about the

19 Clearinghouse and then we'll switch to a conversation about

20 single source and cumulative analyses.

21 So again, just for the record, George Bridgers

22 with the Air Quality Modeling Group here. As I started off

23 here and want to start off now, I want to kind of frame

24 things with what is already in regulation and kind of frame

25 some history of the Clearinghouse and then talk about what
104

KAY McGOVERN & ASSOCIATES (919) 870-1600

Suite 117, 314 West Millbrook Road FAX 870-1603

Raleigh, North Carolina 27609-4306 (800) 255-7886

1 we're trying or proposing to do in the revisions to the

2 Guideline. 

3 So to start off with, in 40 CFR Part 51, 51.166--I

4 sound like I'm up in the policy group right now--(l)(2)

5 specifically, the authority for the specification of a model

6 in Appendix W, which essentially happens in Appendix A to

7 Appendix W, it's all granted through writing from the

8 Administrator. 

9 Now, I can assure you Lisa Jackson--oh, excuse me,

10 whoa. Our fair and very esteemed Administrator McCarthy--I'm

11 sorry to her--that will certainly come up in my performance

12 review. See, you get in front of all these people and you

13 mind just goes blah.

14 So at any rate, yes, she was with the president

15 last week with a very big announcement, and I'm surprised the

16 president's not here with our announcement, but nonetheless,

17 so yes; I do not think that Administrator McCarthy would be

18 personally writing the approvals for the various models. 

19 We do that through rulemaking for the Appendix A

20 models, the ones that are preferred status. And then for the

21 alternative models it happens through a delegated authority

22 with the regions. And I wanted to point out first every23 thing--the buck stops with D.C. and the Administrator.

24 The actual delegation of authority within the

25 hierarchy happens in Appendix W, and it has since the '90s. 
105

KAY McGOVERN & ASSOCIATES (919) 870-1600

Suite 117, 314 West Millbrook Road FAX 870-1603

Raleigh, North Carolina 27609-4306 (800) 255-7886

1 So that happens actually in Section 3. I think it's always

2 been in Section 3, and so what we're trying to do right now

3 is to bring further clarity to the delegation and respect

4 what we have next and something that's been--and I have

5 slides in a minute--that's been throughout the process, and

6 that's that the regional offices already have a responsi7 bility through regulation that they have to coordinate with

8 headquarters on anything that could be inappropriately or

9 unfairly or, you know, capricious and arbitrarily applied

10 across the regions.

11 And so we're the headquarters, and so the buck

12 stops at least with the approval of alternative and preferred

13 models with us in the Air Quality Modeling Group and then

14 with the Clearinghouse the way it's been set up. 

15 So just for the record, it's on the screen as Part

16 56 and 56.5 is where this responsibility of the regional

17 offices to seek concurrence of the headquarters. If anybody

18 is red-green color blind, it's just blank, but I assure you

19 it's on the screen.

20 So we have stressed the importance and the

21 consistency of--or trying to have or gain consistency for

22 years in multiple revisions of the Guideline in the very

23 first sentence, and that's the "Industry and control

24 agencies"--and this has come through previous public comment,

25 and I think everybody in this room--well, I'm not going to
106

KAY McGOVERN & ASSOCIATES (919) 870-1600

Suite 117, 314 West Millbrook Road FAX 870-1603

Raleigh, North Carolina 27609-4306 (800) 255-7886

1 speak for everybody in this room, but I would hope everybody

2 in this room would want consistency in the application of air

3 quality models in the regulatory context. Otherwise, we're

4 not doing our job right.

5 So just to point out a few things, this one is

6 actually in the docket. We included this on the 11th

7 Modeling web site because we discovered it was not anywhere

8 to be found. And unfortunately, Annamaria could not be with

9 us today, but Annamaria, our Region 2 modeling contact, was

10 able to dig up in her treasure trove of archives the old 1988

11 Model Clearinghouse Operational Plan. 

12 And surprisingly, being the Model Clearinghouse

13 Director for going on five years now, I hadn't read that. 

14 Maybe I should have--another performance review thing, but

15 Tyler couldn't provide it to me anyway. Nonetheless, it was

16 an interesting read because everything--and we got this prior

17 to the proposal--because everything that we're trying to

18 codify in this proposed action was clearly stated and

19 provided to the regions in 1988.

20 1993 was the first time that the Clearinghouse

21 actually showed up that I could find in the Guideline. It

22 was in Section 3. And it was interesting that the first

23 thing that I found there was that the primary function was to

24 review decisions proposed by the regional offices on modeling

25 techniques and databases. 
107

KAY McGOVERN & ASSOCIATES (919) 870-1600

Suite 117, 314 West Millbrook Road FAX 870-1603

Raleigh, North Carolina 27609-4306 (800) 255-7886

1 The other two--one was performing audits and then

2 annual reports. We'll get back to the annual reports at some

3 point, but I'm not suggesting--we're not suggesting we're

4 going back to the old days of auditing the regional offices,

5 but that used to happen. But nonetheless, historically the

6 Clearinghouse has been at the center of modeling demon7 stration approvals in the alternative context and the

8 preferred context.

9 So subsequent revisions of the Guideline seemed

10 to--and this just happens with time. Some of the context was

11 lost through what we sometimes call streamlining, but what

12 we're trying to do today is to codify something that has been

13 in practice for like 25 years. 

14 So that's what we have right now is that the

15 responsibilities and the preferred status approvals all

16 happen in Section 3.1, and in 3.2, this is where the

17 Clearinghouse comes in with the approval or concurrence with

18 the regional office on all of the approvals of alternative

19 modeling demonstrations.

20 So in the proposed revision, as I said, we have

21 references to the 1988 Clearinghouse Plan. We listed in the

22 new proposal the 51.166(l)(2) regulatory text reference, and

23 that is to bring clarity on that delegation authority with an

24 understanding of what we talked about with the 56.5(b).

25 We're trying to provide as much transparency--
108

KAY McGOVERN & ASSOCIATES (919) 870-1600

Suite 117, 314 West Millbrook Road FAX 870-1603

Raleigh, North Carolina 27609-4306 (800) 255-7886

1 again, this is a process that's been in place for 25 years. 

2 There was a clearinghouse document, the operational plan that

3 I couldn't even find. It was referenced in the 2005 version

4 of Appendix W that's current, but it's one of those

5 unclickable links you can't find, so we're trying to make

6 sure that the process is as clear as humanly possible, not

7 only for our regional offices but for everybody in the

8 regulated community.

9 And it's also--for the stakeholder community it's

10 what's needed because every decision will be considered--at

11 least on alternative models will be considered in the context

12 of its national importance and not just the regional

13 importance.

14 So I did want to take just a few minutes--this is

15 the formal process, and there are some roles and responsi16 bilities here that I'll also note. First and foremost, the

17 reviewing authority, whether it be a local program, a state

18 program, in some cases EPA or a tribal situation, they're the

19 first--they're the first rung in the ladder, so that's--when

20 an applicant is having issues, they're the people that need

21 to be addressed first.

22 When--in case it's not a regional office, if it's

23 a state, local, or tribal program, if they cannot resolve the

24 issue or if it's going to fall in the territory of an

25 alternative model, then they can--they can engage the
109

KAY McGOVERN & ASSOCIATES (919) 870-1600

Suite 117, 314 West Millbrook Road FAX 870-1603

Raleigh, North Carolina 27609-4306 (800) 255-7886

1 regional office. And then from there the regional office

2 will engage us here in RTP.

3 We don't have situations--and I promise you some

4 of you will know. If you call me up and say, "Hey, George,

5 I've got this problem with this facility," I'm going to stop

6 right there and say, "Have you talked to the state," "Have

7 you talked to the region," and "We need to have this

8 conversation in the context of all of them on the phone." 

9 And that way the information process stays in its proper

10 order.

11 At the point that it's determined that the

12 regional office is going--or needs to make a decision on an

13 alternative model through that delegated authority, they will

14 request from the Clearinghouse concurrence on their decision. 

15 And so they'll actually write us a request, and it's some16 thing that's done in coordination with us--it doesn't happen

17 in a vacuum--and often in coordination with the state or a

18 local program.

19 A little earlier this morning I gave a demon20 stration of the Region 2 clearinghouse situation from July. 

21 The state modeler, the regional modeler, and the

22 Clearinghouse closely coordinated as we pulled that response

23 together, so it was not done in a vacuum.

24 The Clearinghouse would receive a statement of

25 issue, the desired approach with an appropriate justifica-
110

KAY McGOVERN & ASSOCIATES (919) 870-1600

Suite 117, 314 West Millbrook Road FAX 870-1603

Raleigh, North Carolina 27609-4306 (800) 255-7886

1 tion--as the lawyers would like to say, a well reasoned

2 justification--and that would follow what's in Section 3.2.2

3 of the current Appendix W. And fortunately for mapping from

4 the new to the proposed, it's also Section 3.2.2 in the

5 proposed version. And then the Clearinghouse would engage

6 back with the solutions and write the formal concurrence--

7 well, hopefully concurrence--memorandum.

8 Let's see. Moving along, so again, we summarize

9 those things in MCHISRS, which I demonstrated before the

10 break, and we also present things at the annual regional,

11 state, and local modelers workshop and at conferences like

12 these. 

13 Fortunately in the last four to five years we also

14 have started having industry days where we will invite

15 outside stakeholders to the regional, state, and local

16 modelers workshops, so again, that should be bringing

17 additional transparency.

18 And finally--and this I think is something that

19 people lose--generally in the community lose sight of. It's

20 the Clearinghouse memorandums that's another mechanism for

21 bringing issues to us that identify things that we need to

22 change the course of the ship, so to speak, in whether it's

23 the guidance documents we produce or ultimately rulemaking

24 that we need to go through.

25 So if we were not going through this process right
111

KAY McGOVERN & ASSOCIATES (919) 870-1600

Suite 117, 314 West Millbrook Road FAX 870-1603

Raleigh, North Carolina 27609-4306 (800) 255-7886

1 now, this whole proposal process, and ARM2, just to take an

2 example, were presented to us, it would put first and

3 foremost that that's one of the things that needs to be on

4 the docket for the next rulemaking.

5 And with that, I have a link here for the

6 Clearinghouse--again, that link will eventually change--and

7 then my contact information, but this is for questions

8 specific to the Clearinghouse and not the proposal. So with

9 that I will end that presentation as close to on time.

10 And then I will move to the final presentation in

11 the morning session, and this is on single source and

12 cumulative impact analysis, which is maybe not the--well,

13 it's a good title. But what I'm going to talk about is

14 really Section 8 and Section 9 of the proposed rulemaking.

15 So throughout the morning we have heard a lot of

16 discussion about AERMOD, AERSCREEN, met aspects of the

17 Guideline, other aspects of single source modeling in the PSD

18 context. We really have talked about all aspects of Section

19 1 through 7 and portions of Section 8 that we're proposing to

20 update. 

21 And all this culminates--it was previously

22 Sections 8 and 10, but all this sort of culminates at the

23 very end of Appendix W. And so what I'm planning to do right

24 now is to talk about that culmination and what we propose to

25 do. And actually, I probably could take Tyler's talking
112

KAY McGOVERN & ASSOCIATES (919) 870-1600

Suite 117, 314 West Millbrook Road FAX 870-1603

Raleigh, North Carolina 27609-4306 (800) 255-7886

1 points from his first opening session because he did such a

2 great job.

3 But nonetheless, we simplified--I shouldn't say

4 simplified. It's probably a bad choice of words. We've

5 streamlined Appendix W, the Guideline, by reorganizing

6 information hopefully, and this is what we expect or

7 appreciate your feedback on in a more logical manner.

8 The previous Section 9 had a lot of information

9 about uncertainty, and it's one of those classic pieces of

10 regulation. You get to the very end of the old Section 9 and

11 it says basically disregard everything we just talked about

12 because we don't have enough information to bring it to bear

13 in a regulatory context. There was a very awkward set of

14 text there. But nonetheless, we've reorganized information

15 from the previous Section 9, streamlined overall Appendix W,

16 so the previous Section 10 is now Section 9.

17 Despite us talking from the highest mountain or

18 valley or, you know, podium that we can find saying that

19 there's all sorts of reasons that you should not use the

20 draft resource manual, the old puzzle book, at least in the

21 context of the permit modeling, is that, you know, if you can

22 use the old workshop manual and get the answer that you need

23 to get your permit, have at it, seriously.

24 But just because past practices have worked for

25 decades doesn't mean that they were necessarily the best
113

KAY McGOVERN & ASSOCIATES (919) 870-1600

Suite 117, 314 West Millbrook Road FAX 870-1603

Raleigh, North Carolina 27609-4306 (800) 255-7886

1 practices. Now, I'm a young whippersnapper, so to speak. 

2 I'm not one of the old tried and true of the community, but I

3 can tell you that things in that workshop manual were overly

4 conservative. 

5 Were they great thoughts? Yes. They were well

6 thought, well reasoned at the time, but the science, the

7 community has evolved, and we also have some very new,

8 different form standards, different time metrics that we have

9 to take in consideration. And taking those into considera10 tion in the mind's eye of the rest of the community and the

11 rest of the tools that we have, we do need to move away from

12 some of the old unnecessarily conservative and complicated

13 practices. So that's one of the things that we're attempting

14 to do in this rulemaking.

15 So throughout Section 8 we've intended to modify

16 the past practices and provide a more appropriate basis for

17 the selection and the use of the various modeling inputs. 

18 I'll have some more slides on that in a minute. 

19 And in Section 9, as Tyler said, what we've really

20 tried to do is get rid of a lot of old, bad or incorrect

21 language that was in Section 9 and bring to bear the policies

22 that the agency has been following with respect to single

23 source and cumulative impact analysis. And then in rare

24 circumstances, Tyler said, we've maintained and will remain

25 to keep the old Section 10.2.2 with respect to monitoring in
114

KAY McGOVERN & ASSOCIATES (919) 870-1600

Suite 117, 314 West Millbrook Road FAX 870-1603

Raleigh, North Carolina 27609-4306 (800) 255-7886

1 lieu of modeling.

2 So in Section 8, and this is new, there is a

3 section now talking specifically to the definition of a

4 modeling domain. That's information that previously was not

5 in Appendix W. We're proposing a new Section 8.1 with the

6 specific requirements that set up the definition of modeling

7 domain, and this is where you would have a radius extending

8 from your source that's either new or modifying out to the

9 point--the furthest point to which it can be demonstrated to

10 have a significant ambient impact. So this is sort of 

11 where--the old process of where you use a SIL analysis to

12 figure out what your modeling domain is.

13 The other caveat is, is 50 kilometers, as Tyler

14 has said, at least for the inert pollutants and the NAAQS

15 compliance, is the limit. And so whichever one of these is

16 less is your modeling domain, and this is what would be used

17 in the cumulative analysis.

18 With respect to attainment demonstrations where

19 there was not information before, we're now providing some

20 more information that talks about setting and establishing

21 modeling domains in that context too.

22 Now, this is one that's a little bit different

23 because the nature of the problem is going to be different. 

24 You're normally talking about larger areas and multisources,

25 and so that area needs to include all the major upwind areas
115

KAY McGOVERN & ASSOCIATES (919) 870-1600

Suite 117, 314 West Millbrook Road FAX 870-1603

Raleigh, North Carolina 27609-4306 (800) 255-7886

1 that could have impacts on the nonattainment area and also

2 all the monitors that are violating the nonattainment area. 

3 And as a caveat and a previous modeler for a state, you

4 should really have--although we've seen it--all of the

5 nonattainment area in your modeling domain, but we classify

6 it as all the monitors being encapsulated.

7 I will say in both 8.1 and 8.2, and this happens

8 in the context of a well developed modeling protocol, these

9 both should be vetted with the appropriate reviewing

10 authority before significant modeling is underway. And

11 that's just an assurance on both sides that what's being done

12 is appropriate.

13 In Section 8.2 we have made some other changes,

14 and this flows along with the old source input data from the

15 previous Appendix W. Well, I say the previous; it's the

16 current, the 2005 version. And I have listed out here some

17 specific section numbers with the various different pieces.

18 But we have added new language with respect to,

19 again, SIP attainment demonstrations where Appendix W was

20 lacking previously--in this case for ozone, for fine

21 particulates, and also for regional haze--new language on how

22 to characterize the direct and the precursor emissions, and

23 that's in 8.2.2(a).

24 We've revised the requirements on how to

25 characterize emissions from nearby sources that need to be
116

KAY McGOVERN & ASSOCIATES (919) 870-1600

Suite 117, 314 West Millbrook Road FAX 870-1603

Raleigh, North Carolina 27609-4306 (800) 255-7886

1 explicitly modeled for the purposes of a cumulative analysis,

2 and that's covered in a handful of paragraphs in 8.2.2(b),

3 (c), (d) of the new proposed Appendix W. And then finally in

4 8.2.2(e) we revised the language on how to characterize

5 emissions from mobile sources, and that's been updated and is

6 more appropriate. And that happened with coordination with

7 our transportation partners.

8 The most notable change--and this is the one that,

9 you know, flashing lights or whatever that we've changed--is

10 how to characterize the emissions from nearby sources. 

11 Tables 8-1 and 8-2--they're still Tables 8-1 and 8-2, and

12 that's for simplicity in all the world, so we didn't change

13 the table numbers up--we have changed that nearby sources

14 will now be characterized by--and I put it in quotations

15 because there's 100 different ways you could classify this--

16 what we traditionally have called actual emissions rather

17 than allowable emissions.

18 So my next caveat is the next bullet: emissions

19 are based on emission limit, operating level, operating

20 factor. Please look at Tables 8-1 and 8-2 to understand the

21 full context of actual and allowable emissions because they

22 can take on some slightly different connotations.

23 With respect to the actual emissions, they need to

24 be based on the most recent two years of actual, and I

25 probably should have put a comma there, nominal emissions. 
117

KAY McGOVERN & ASSOCIATES (919) 870-1600

Suite 117, 314 West Millbrook Road FAX 870-1603

Raleigh, North Carolina 27609-4306 (800) 255-7886

1 If the facility was shut down for two years for maintenance

2 or for a year for maintenance, you should not use one of

3 those in calculating what their actual emissions are. 

4 I know many of you would like to, but you should

5 have two years of actual operation and they should be typical

6 operation. And so there's a bit of an art there in creating

7 that emissions. Number one question: where's the inventory? 

8 Just like with SIPs, there's some work that's going to have

9 to be done there nonetheless.

10 I do also want to point out--and this is no change

11 in Tables 8-1 or 8-2 with respect to the new or modifying

12 source. They're still going to be characterized by their

13 proposed allowable or the permit limitation emissions, so the

14 only change is with nearby sources.

15 Then there's Section 8.3, and 8.3 kind of--

16 everything here gets a little jumbled because this kind of

17 plays back on some of the things that we talked about in 8.2

18 because this is where we're talking about how we construct

19 the design concentration. And that has to be done in context

20 of whether you're an isolated single source or whether you're

21 in a multisource area.

22 In an isolated single source area, typically

23 you're--and this is in the cumulative context--typically

24 you're going to have some background monitor that's going to

25 be representative of everything, and that's going to be
118

KAY McGOVERN & ASSOCIATES (919) 870-1600

Suite 117, 314 West Millbrook Road FAX 870-1603

Raleigh, North Carolina 27609-4306 (800) 255-7886

1 nearby sources and other sources and international emissions,

2 and then you're going to have your project source.

3 In the multisource area there's some updated

4 language in 8.3.3, and this is where you talk about the

5 culmination of sources that could be nearby that need to be

6 explicitly modeled, the other sources that are typically

7 characterized by background emissions, and the background

8 emissions. And then there's always the other emissions, like

9 I said, and that's typically taken care of by the monitored

10 background.

11 Before I get to that, I want to say a few more

12 things about 8.3. We also go into some detail here--and I

13 have it as the first bullet; I just missed it--is a

14 discussion of the importance of understanding of what the

15 monitoring data truly represent. 

16 And this is--this is important because this goes

17 back to the bad past practices, because as often is the case,

18 we have seen time and time again that someone includes a

19 background monitor and they include--and I don't want to give

20 a number because I'll miss--somebody will say, "Oh, I've seen

21 less" or "I've seen more," but numerous--underscore,

22 italicize, quotations, whatever, boldface--numerous nearby

23 sources. And there's a significant amount of overcounting,

24 double counting, extra conservativeness that's put into the

25 demonstration.
119

KAY McGOVERN & ASSOCIATES (919) 870-1600

Suite 117, 314 West Millbrook Road FAX 870-1603

Raleigh, North Carolina 27609-4306 (800) 255-7886

1 The community--what we're proposing is the

2 community as a whole, and that includes the states and

3 locals, they need to get out of the habit of just taking

4 everything in the kitchen sink and throwing it at the model

5 and then coming to us and saying, "We're getting these

6 outrageous concentrations," and you've got 1,000 nearby

7 sources in there.

8 And so there is updating language--I'm jumping

9 around in the bullets, but there is updated language about

10 the concept of using significant concentration gradients to

11 understand where you have situations where you have nearby

12 sources that are just not well classified or characterized by

13 the monitor and need to be explicitly included. But there

14 should be--and this statement is from the proposed guidance,

15 that there should be only a few nearby sources in most cases.

16 There's already been discussion this morning on

17 the met data side and the met data input, you know, the

18 introduction of the possibility of prognostic data where a

19 National Weather Service is not reasonably available and it's

20 just not feasible to collect site specific data. And then

21 also we brought in AERMINUTE just so it was clearly classi22 fied in Appendix W.

23 Now, everything culminates in Section 9. We

24 stress--we updated the language with respect to 9.2.1; it's a

25 recommendation, it's not a requirement--that the development
120

KAY McGOVERN & ASSOCIATES (919) 870-1600

Suite 117, 314 West Millbrook Road FAX 870-1603

Raleigh, North Carolina 27609-4306 (800) 255-7886

1 of a modeling protocol is extremely important. This is the

2 living document that everybody can look to to understand

3 what's going on, and a well developed modeling protocol on

4 the front end makes the whole back end with the public

5 hearing and the public sharing of information much easier.

6 Information with respect to the design concen7 trations, previously we had information scattered between

8 Section 7 and Section 10. We had all very, very specific

9 language for what individual standards were. As Kirk got up

10 here and said with the models that were listed in Section 6,

11 you look at it and you go what era, what decade is this from. 

12 We removed that from the current proposed Appendix

13 W. We're not going through and listing out what every

14 current standard is and how to calculate it. That's going to

15 be handled in guidance outside because the standards change

16 and we can't update Appendix W every time we revise the

17 NAAQS. We may need to at times, but we shouldn't do it every

18 time. So it's more dynamic.

19 We've also improved the discussion on receptor

20 sites in 9.2.2. Along with putting too many nearby sources

21 in, the other thing that we were seeing is people using tens

22 of thousands, if not hundreds of thousands, of receptors out

23 to 50 kilometers in every direction, and that is excessively

24 large and unnecessary. And this goes back to we've updated--

25 are proposing to update language with respect to the modeling
121

KAY McGOVERN & ASSOCIATES (919) 870-1600

Suite 117, 314 West Millbrook Road FAX 870-1603

Raleigh, North Carolina 27609-4306 (800) 255-7886

1 domain, what's in that modeling domain, and then the

2 receptors that you look in that modeling domain.

3 In 9.2.3 we overhauled the overall recommendations

4 of how to do the compliance demonstration. The language

5 wasn't clear before and it wasn't concise, so now we have as

6 the first stage that you perform the single source impact

7 analysis. Some people refer to that as the SIL analysis. 

8 And then only upon demonstrating that you are above or could

9 cause a significant impact, then you would move to the

10 cumulative analysis, which is much more comprehensive.

11 We also revised--and this was a major overhaul

12 because there were parts of the emissions limit discussion

13 that even our policy folks looked at and didn't understand or

14 realize--I mean most of the regional offices read it and

15 said, "We didn't realize that was in Appendix W." And it was

16 outdated and it was largely incorrect given the form and the

17 time frame of the new standards.

18 And finally, as I just mentioned earlier, there is

19 some more information provided with respect to the monitoring

20 in lieu of modeling or the use of measured data in lieu of

21 model data, but as Tyler said, this is an area where we are

22 seeking input because this is an area where we don't--we only

23 have a couple of very dated and very old examples.

24 And so we have provided more, hopefully more

25 clarity and some more structure on how one might step through
122

KAY McGOVERN & ASSOCIATES (919) 870-1600

Suite 117, 314 West Millbrook Road FAX 870-1603

Raleigh, North Carolina 27609-4306 (800) 255-7886

1 the process to determine whether or not they can use

2 monitored data, but there's a whole back end part that's not

3 in Appendix W and probably should never be in Appendix W that

4 goes through the whole policy aspects of then how the data is

5 used in actually writing the permit, potentially caveats that

6 need to be in that permit, conditions or postconstruction

7 monitoring or the like. And that's just something that's not

8 relevant or appropriate in Appendix W, but nonetheless we end

9 that.

10 So Appendix W has this nice little, okay, we

11 defined the universe for models. If you have current models,

12 you can use them, great, well and fine. If you have

13 situations that you need to use an alternative model or

14 there's not a preferred model, there are situations for that. 

15 We define how you use your input data, how to put that in a

16 regulatory context. But if all else fails, there's this last

17 piece, and this last piece is the one that we want to get

18 additional comment from the external community. I think with

19 that I am done.

20 And so seeing that it is almost 11:45, I will take

21 this opportunity to break us for lunch. I'm going to keep us

22 on the 1:20 time schedule, so we get a few extra minutes for

23 lunch today. I'm trying to think of any other caveats. Just

24 try to be back in the room by 1:20 because we'll start then. 

25 Have a great lunch, everybody.
123

KAY McGOVERN & ASSOCIATES (919) 870-1600

Suite 117, 314 West Millbrook Road FAX 870-1603

Raleigh, North Carolina 27609-4306 (800) 255-7886

1 F U R T H E R P R O C E E D I N G S 1:24 p.m.

2 Mr. Bridgers: So I want to welcome everybody

3 back to the afternoon session of the first day here of the

4 11th Conference on Air Quality Modeling. As if the modeling

5 conference wasn't already a public forum or public hearing

6 that's being transcribed, this is also a public hearing for

7 the proposed rulemaking on the revisions to the Guideline on

8 Air Quality Modeling, as I mentioned that this morning. So

9 from this perspective, it's at this point that we actually

10 start the public hearing officially for the notice of

11 proposed rulemaking. So as the public hearing officer, I

12 call the public hearing to order.

13 Just as a reminder--I don't want to spend a lot of

14 time on this and we can go right into the presentations--all

15 the presentations today are part of the record. They'll be

16 put in the docket at some point, in the week or so following

17 this conference. As I mentioned earlier, most of all the

18 presentations are already posted online that you can get

19 through the agenda that's posted online. And I'll make

20 that--I'll have more clear links over the next couple of days

21 for others that weren't able to join us here.

22 I do ask that everybody identify themselves when

23 they come up to the microphone. And to that end, for the

24 court reporter next to me, I am George Bridgers with the Air

25 Quality Modeling Group here at the USEPA. All the docket--
124

KAY McGOVERN & ASSOCIATES (919) 870-1600

Suite 117, 314 West Millbrook Road FAX 870-1603

Raleigh, North Carolina 27609-4306 (800) 255-7886

1 all the dialogue will be transcribed. We're not having any Q

2 and A. Let's see what else in my caveats.

3 Anyone that did not request a time to speak in

4 advance will have an opportunity tomorrow late morning and

5 then tomorrow afternoon to offer oral comments to the docket. 

6 Otherwise, comments then can be submitted to the docket for

7 the next--it depends if you count from today or tomorrow, for

8 the next 74 or 75 days to October 27th of 2015.

9 We have a full afternoon. Although there are only

10 15 presentations, there's a lot of material to cover. So I

11 ask that all speakers keep to their set times. And to that

12 end since we're only offering 15 minutes, I will have to cut

13 people off. I will not try to be rude about it, but when we

14 get to 15 minutes, that's your allotted time. We will hold

15 that tomorrow as well with the public oral comments. 

16 So without wasting any time, I would like to

17 transition. And first up we have three presentations,

18 although they're by different affiliations for Bob Paine,

19 they're from Bob Paine. This is not the Bob Paine

20 conference. And so Bob Paine.

21 Mr. Paine: Thank you. You've already

22 identified me. I'm from AECOM and I've given the court

23 reporter a business card. This talk is going to be on behalf

24 of the American Iron and Steel Institute or AISI. And we're

25 going to talk about near-field modeling and source
125

KAY McGOVERN & ASSOCIATES (919) 870-1600

Suite 117, 314 West Millbrook Road FAX 870-1603

Raleigh, North Carolina 27609-4306 (800) 255-7886

1 characterization issues for near-field modeling. I would

2 like to express appreciation to EPA for the dialogue that

3 AISI has had with EPA on these issues and we're going to

4 continue with that dialogue.

5 I'm going to talk about two issues that I have

6 time for and then there are supplemental issues that are

7 provided as attachments to the presentation, which I will

8 summarize very briefly at the end of my verbal comments. 

9 Highly industrialized areas are mentioned briefly

10 in the proposed Appendix W changes and we would like to

11 expand on that discussion here. However, those with large

12 heat releases over a sizeable area can and should be modeled

13 with urban dispersion option in AERMOD.

14 The other issue I'm going to dwell upon at some

15 length is stack plumes on or near buildings that have

16 experienced fugitive heat releases maybe not related to the

17 actual stack that can lift off the plumes being modeled. 

18 That would--accounting for those effects would reduce

19 inaccurate overpredictions due to the current downwash that

20 does not account for these heat releases.

21 The supplemental issues provided as attachments

22 deal with some evaluation results for these two items at the

23 top and also two other issues. And that is plumes from

24 adjacent stacks that would be partially merged and result in

25 a higher effective plume rise and also plume rise from moist
126

KAY McGOVERN & ASSOCIATES (919) 870-1600

Suite 117, 314 West Millbrook Road FAX 870-1603

Raleigh, North Carolina 27609-4306 (800) 255-7886

1 plumes that isn't really addressed in AERMOD.

2 I have already mentioned the EPA and AISI have

3 been discussing these, and several technical documents have

4 been provided to EPA. But these documents will also be

5 provided to the docket for this rulemaking by AISI.

6 Okay. Let's talk about urban dispersion for

7 highly industrialized areas. Right now--and this is really a

8 source characterization effect. It's not really a change in

9 the model, but it's a change in how you characterize a

10 source's input to the model. 

11 Normal assignments of urban versus rural

12 dispersion are important here. And industrial processes in

13 geographic areas of large heat releases but low population,

14 such as areas with a lot of industrial activity where not a

15 lot of people live and there might be water bodies nearby

16 that would make the 3 kilometer circle be characterized as

17 rural, but with all the heat release, it's probably better to

18 model it as an urban area with a large effective population.

19 And I'm going to talk about how to characterize

20 that effective population. Actually, Appendix W does refer

21 to that, the need to do this characterization. This

22 characterization would then provide the appropriate urbanized

23 treatment of mixing height and the temperature lapse rate for

24 the dispersion calculations.

25 Now, in the classic urban area, which is shown at
127

KAY McGOVERN & ASSOCIATES (919) 870-1600

Suite 117, 314 West Millbrook Road FAX 870-1603

Raleigh, North Carolina 27609-4306 (800) 255-7886

1 bottom right, there is a temperature excess at the core of

2 the urban area. And you can identify the depth of the urban

3 heat island, basically the boundary layer, by the temperature

4 difference between the core of the urban area and the

5 outskirts. 

6 But as I said, these large industrialized areas do

7 not meet the classic definition for an urban area, but the

8 formulation of AERMOD does provide a way to parameterize the

9 effective urban population if you can get an idea of the

10 delta-T between the urban and rural.

11 The next slide shows how to get that. From the

12 AERMOD model formulation, the delta Tu-r is related to the

13 population input to the model with this relationship. Where

14 there's a 12 degree Celsius delta-T, it is related to a

15 population--a reference population of 2,000,000. 

16 You can get at the temperature difference now via

17 satellite data, which I'm going to show an example of. And

18 there's going to be more documents uploaded to the docket

19 that explain how to use satellite data to obtain this very

20 important input to this process.

21 Alternatively, if you have engineering estimates

22 of the excess heat release, the bottom equation, if you can

23 see it, shows how you relate the watts per square meter

24 excess heat release to the temperature difference, and then

25 the temperature difference can be related to the effective
128

KAY McGOVERN & ASSOCIATES (919) 870-1600

Suite 117, 314 West Millbrook Road FAX 870-1603

Raleigh, North Carolina 27609-4306 (800) 255-7886

1 population.

2 So let's talk about how we can get measurements of

3 this urban-rural temperature difference via satellite data. 

4 Available satellite platforms are ASTER and LandSat 8. And

5 again, we're going to provide more technical discussion of

6 how to access these databases. You actually don't get the

7 temperature difference map directly from the satellite data. 

8 You have to download the data and then create the map. In

9 the explanation we'll go into how that's done.

10 We provide an example on the next slide of such a

11 map and also in Supplement A to the presentation that will be

12 online. And what you really get is a brightness temperature

13 that is related to the actual physical temperature

14 difference. Obviously these procedures are relatively new,

15 being refined. 

16 The next slide shows an example of a highly

17 industrialized area with the white ellipse. And you can see

18 on the right side the variation of the temperature, the

19 brightness temperature. And the difference between the core

20 of that highly industrialized area and the outskirts is

21 roughly about 12 degrees Celsius. 

22 And you can then accommodate that to the equation

23 on the previous slides. That would be an effective

24 population of about 1,000,000, which then could be used as

25 input to AERMOD with an urbanized--urban approach with an
129

KAY McGOVERN & ASSOCIATES (919) 870-1600

Suite 117, 314 West Millbrook Road FAX 870-1603

Raleigh, North Carolina 27609-4306 (800) 255-7886

1 effective population of 1,000,000. The next--and again, the

2 Supplement A gives more information about how this has been

3 evaluated already with a highly industrialized area.

4 The next topic I want to talk about is building

5 downwash issues with this fugitive heat liftoff effect. In

6 fact we have a procedure called LIFTOFF.

7 There is an issue of--there is an issue with light

8 winds and downwash. Sometimes we get in AERMOD high

9 predictions in light winds, which is somewhat counter10 intuitive. I list a couple of papers down at the bottom of

11 this slide that discuss this issue of downwash and light

12 winds. The bottom paper, which is a plume lift-off

13 consideration, is the core of this new technique, a paper by

14 Hanna, Briggs, and Chang. And I'm going to talk about a

15 formulation in that paper that we are using in this new

16 procedure.

17 When we see these predictions under light wind

18 stable conditions, we realize that they are probably not real

19 in some sense or they wouldn't be expected because first of

20 all you'd expect intermittent downwash with the winds

21 fluctuating. AERMOD does not accommodate the fact that you

22 have unsteady downwash in conditions with a lot of wind

23 fluctuations in effect. To my knowledge the PRIME model does

24 not have a meander treatment in AERMOD, so that's another

25 reason why you might get an overprediction in light winds
130

KAY McGOVERN & ASSOCIATES (919) 870-1600

Suite 117, 314 West Millbrook Road FAX 870-1603

Raleigh, North Carolina 27609-4306 (800) 255-7886

1 with downwash effects.

2 So how to adjust for this issue? Actually,

3 there's another model; the Danish OML model does account for

4 the intermittent nature of light winds on downwash, and the

5 publication is available here as a link. There's a weighting

6 factor in that model to accommodate the intermittency of this

7 effect.

8 Now, let's add the issue of heat releases onto low

9 winds, and we have a treatment in that referenced paper with

10 a dimensionless buoyancy flux that's related to the heat--the

11 fugitive heat release, the wind speed, which is an hourly

12 effect, and a plume width that's probably tied to the

13 building width. 

14 So what we created is sort of a postprocesser to

15 AERMOD where we deal with the intermittency by using an

16 hourly weighting factor between two extremes, the no downwash

17 case and the full downwash case.

18 As the buoyancy flux, dimensionless buoyancy flux,

19 goes toward zero, you would tend toward a full downwash

20 treatment. As the dimensionless buoyancy flux increases to a

21 large number, it would tend to a no downwash extreme. And in

22 the middle you would have a weighting of the two effects.

23 The evaluation testing has been--is done actually

24 not only by the studies cited in the Hanna, Briggs, Chang

25 paper, but also in a recently conducted field study that's
131

KAY McGOVERN & ASSOCIATES (919) 870-1600

Suite 117, 314 West Millbrook Road FAX 870-1603

Raleigh, North Carolina 27609-4306 (800) 255-7886

1 going to be described more in documents submitted to the

2 docket. Also in Supplement B we had four SO2 monitors around

3 the site with such heat releases. And the default modeling

4 approach with full downwash did overpredict substantially.

5 This liftoff approach had much more accurate

6 predictions. We used satellite imagery to document the

7 buoyancy flux. For example, look at this. This was a plume

8 from this facility. 

9 You're going to see in the next slide a thermal

10 infrared image with an intense heat from--they're not really

11 pollutants, but they're emitting heat. You also see that the

12 building temperature is much higher than the ambient. So you

13 have lots of heat being exuded. You can't see them. You

14 can't see this visually, but you can see it with the right

15 kind of camera. So this effect is imparted into the liftoff

16 postprocessor.

17 So to summarize issues with written comments

18 coming, I'd like to bring back the issue of when stacks are

19 touching or nearly so, I don't think we have a nationwide

20 consistency of treating those as merged. But there is a

21 Clearinghouse record--and I think that should be 91-Roman

22 numeral II, rather than 11. The issue was addressed in a

23 Clearinghouse record such that stacks that are within 1

24 diameter should be modeled as fully merged, so I hope that

25 can be a national consistency issue that EPA addresses.
132

KAY McGOVERN & ASSOCIATES (919) 870-1600

Suite 117, 314 West Millbrook Road FAX 870-1603

Raleigh, North Carolina 27609-4306 (800) 255-7886

1 Partial plume rise enhancement, this is going to

2 be--this is Supplement C in the presentation. Briggs had an

3 explanation in various classic textbooks, '75, '84,

4 Atmospheric Science and Power Production or something like

5 that, where he has an algorithm for stacks in a row with

6 partial plume rise enhancement. That is--we've accommodated

7 that in a procedure we call AERLIFT.

8 And finally, we have the other procedure for plume

9 rise models for exhaust streams with substantial moisture

10 that we call AERMOIST. And in that case the relative

11 humidity is a factor. What we do there is we preprocess the

12 hourly emission input so that the effective temperature input

13 to AERMOD is actually modified to accommodate the heat of the

14 condensation due to moist plumes. That comes from basically

15 a model that's been validated in Germany, and the details are

16 going to be provided to the docket. And they are also in

17 Supplement D to this presentation.

18 So finally, the AISI recommendations for source

19 characterization effects to EPA would be that Appendix W

20 should further clarify that the case by case source

21 characterization refinements should not be treated as

22 alternative model options, but should be allowed with

23 adequate documentation as normal, more accurate source

24 characterization. 

25 And besides the urban characterization for large
133

KAY McGOVERN & ASSOCIATES (919) 870-1600

Suite 117, 314 West Millbrook Road FAX 870-1603

Raleigh, North Carolina 27609-4306 (800) 255-7886

1 industrialized areas that Appendix W does briefly mention,

2 we'd like it to be mentioned more clearly, maybe in the model

3 implementation guide.

4 I mentioned the plume liftoff issue for fugitive

5 heat releases on buildings that affect downwash treatment,

6 plume merging, not only due to stacks that are touching or

7 nearly so--that should be a no-brainer--but for stacks that

8 are in a row that can have plume enhancement--that's a

9 function of direction and other effects that AERLIFT accounts

10 for--adjustments to plume rise due to their moisture content.

11 So each of these issues can be addressed by source

12 characterization approaches that improve the hourly emissions

13 input. AISI requests these techniques be acknowledged as

14 viable source characterization options in Appendix W and

15 perhaps the AERMOD implementation guidance document. And my

16 15 minute buzzer has gone off.

17 Mr. Bridgers: You did have one more slide,

18 didn't you?

19 Mr. Paine: Oh, that's just the rest of

20 the---

21 Mr. Bridgers: (interposing) The supplements.

22 Mr. Paine: It will be on the web site.

23 Mr. Bridgers: And I know some of you saw me

24 running about just a minute ago trying to do some stuff over

25 there, and it's proof positive of government bureaucracy. I
134

KAY McGOVERN & ASSOCIATES (919) 870-1600

Suite 117, 314 West Millbrook Road FAX 870-1603

Raleigh, North Carolina 27609-4306 (800) 255-7886

1 had to get a contractor to come dial a telephone number. So

2 we once again acknowledge Bob Paine.

3 Mr. Paine: Thank you. Low wind speed

4 issues have been brought up this morning as important

5 improvements in AERMOD. I've been talking about that for

6 several years. But now we're going to augment the emphasis

7 on the evaluation databases of lower level sources to tall

8 stack databases. And in fact this study has been written up

9 in a technical paper that has been accepted for publication

10 by the Journal of the Air & Waste Management Association, so

11 that should appear later this year in print. I would also

12 like to acknowledge the sponsorship on this study to EPRI and

13 the Lignite Energy Council.

14 I'm going to talk about the background for this

15 study, but I already sort of have. It's basically augmenting

16 the emphasis on lower level sources to tall stacks, a 

17 description of the evaluation databases, the modeling options

18 evaluated, and the evaluation results and the overall results

19 and conclusions.

20 Now, before AERMOD, you know, model input wind

21 speeds were never allowed to go below 1 meter per second. 

22 And as part of AERMET, our committee was--thought we could

23 conquer the world, and so we decided to go lower than 1 meter

24 per second. But we are straining the steady state model

25 plume assumptions, which tend to break down as winds go
135

KAY McGOVERN & ASSOCIATES (919) 870-1600

Suite 117, 314 West Millbrook Road FAX 870-1603

Raleigh, North Carolina 27609-4306 (800) 255-7886

1 toward calm.

2 But AERMOD, in any case, does allow arbitrarily

3 low wind speed inputs down to the instrument threshold, which

4 seem to be getting lower and lower these days with ice-free

5 instrumentation and sonic anemometry. So that's another

6 thing that we didn't foresee in the '90s maybe.

7 So in an attempt to account for this effect with

8 plume meander, it's a random plume and a coherent plume

9 weighting scheme that's shown in this slide, which is

10 borrowed from a Joe Scire presentation a few years ago

11 whereas we have a wind blowing from the south here in this

12 figure and the stack at 0.0 in the center.

13 And the coherent plume is predicted as the usual

14 Gaussian plume equation and its concentration is usually much

15 higher than the so-called meander or pancake plume, which I

16 believe LowWind3 tends to chop off the bottom half of that

17 pancake such that we look at upwind concentrations. But

18 that's basically--the weighting between these two extremes is

19 what is done by the meander algorithm in AERMOD.

20 Okay. What did we bring up in our studies from

21 EPRI and UARG in 2010? We realized that friction velocity,

22 which is an important output of AERMET, was underestimated in

23 very low winds by up to a factor of 2. This resulted in

24 several compound issues in stable conditions--an under25 prediction of the level of turbulence, the mechanical mixing
136

KAY McGOVERN & ASSOCIATES (919) 870-1600

Suite 117, 314 West Millbrook Road FAX 870-1603

Raleigh, North Carolina 27609-4306 (800) 255-7886

1 height, and other related issues were underestimated, which

2 led to too concentrated of a plume in stable conditions. 

3 Perhaps even the plume meander weight was possibly under4 estimated.

5 So we recommended changes in both the friction

6 velocity formulation and also recommended a change to the

7 minimum lateral plume spread in the AERMOD dispersion model

8 to help account for the additional meander you would expect

9 in very light winds.

10 And I think this has already been explained. EPA

11 started to accommodate these changes in various versions

12 listed in the second bullet and finally in this version have

13 come up with recommendations for a final ADJ_U* in AERMET and

14 a LowWind3 option in version 15181. There have been previous

15 webinars, and of course today's presentation has provided

16 basic recommendations to adopt these changes.

17 I would concur that the proposed changes should be

18 made a permanent part of the model. I also want to advise

19 EPA that due to hundreds of sources being modeled for SO2

20 these days, we may not be able to wait until next spring. 

21 And we hope that we can get an interim approval process in

22 place for approval of these options now because modeling is

23 happening right now. And it's very critically important to

24 have these improvements accommodated in the model.

25 And I want to talk now about the findings from
137

KAY McGOVERN & ASSOCIATES (919) 870-1600

Suite 117, 314 West Millbrook Road FAX 870-1603

Raleigh, North Carolina 27609-4306 (800) 255-7886

1 tall stacks, which are a critical part of the SO2 modeling

2 that's being done nationwide. Two databases we looked at:

3 North Dakota Mercer County with rolling terrain, one elevated

4 monitor and five monitors in all, four years of data; and we

5 talked about--I've seen Gibson before. We happened to focus

6 on three specific years with four monitors. It's a tall

7 stack, flat terrain database. Both of these databases use

8 the data from a 10 meter tower to evaluate standard

9 airport-type meteorological input.

10 We tested four options of AERMET and AERMOD in

11 default mode. This was model version 14134. Then we added

12 the beta U* option, but not any changes to AERMOD. And then

13 we added changes to the minimum sigma-v with the LowWind2

14 option in the last two options tested with a 0.3 and a 0.5

15 meter per second minimum sigma-v.

16 We have produced various statistical tests which 

17 are going to be discussed in that JAMA paper. And I'm going

18 to only have time really to present the 99th percentile peak

19 daily 1 hour max statistics during the little bit of time I

20 have here. We did Q-Q plots as well as review of meteoro21 logical conditions associated with peak predictions that I

22 will mention briefly today.

23 The key thing on the North Dakota database is the

24 fact that we have these five monitors that are sort of these

25 square pink or purple objects here. One of them is circled
138

KAY McGOVERN & ASSOCIATES (919) 870-1600

Suite 117, 314 West Millbrook Road FAX 870-1603

Raleigh, North Carolina 27609-4306 (800) 255-7886

1 in high terrain, the DGC 17 monitor. Sources that were near

2 these monitors were the Antelope Valley station and the Great

3 Plains Synfuels Plant, the red triangles.

4 The other four monitors were in relatively low

5 terrain, but this one monitor was in higher terrain. Notice

6 that the DGC 16 monitor was the closest to these sources, and

7 it has a little bit of a different response to the models

8 than the other three in low terrain. Backing up, we also

9 modeled more distant sources, maybe more distant than the new

10 guidance would say because these are approaching 50

11 kilometers away.

12 Okay. Now I'm going to dwell on this slide for a

13 little while because we take those four modeling options--

14 from left to right, it's default AERMET, default AERMOD. The

15 yellow is AERMET with beta U*, but no sigma-v LowWind2

16 options. Then we add the sigma-v minimum of 0.3 and 0.5 as

17 the green and the purple bars.

18 We see that for--DGC 17 is the one that's next to

19 the--second from the right. That shows a large--with that

20 elevated terrain, that shows a large response to the beta U*

21 option. In the other applications in terrain, I've noticed

22 large responses. The other models show--the other monitors

23 show no real response to the beta U* option because the peak

24 predictions are in daytime conditions, but some response to

25 the minimum sigma-v options. 
139

KAY McGOVERN & ASSOCIATES (919) 870-1600

Suite 117, 314 West Millbrook Road FAX 870-1603

Raleigh, North Carolina 27609-4306 (800) 255-7886

1 The DGC 16 had a little bit higher overprediction.

2 By the way, let's go back to that. Notice that on the 

3 y-axis, all the models are predicting at or above a 1.00

4 model to monitored ratio. So all overpredicting were nearly

5 unbiased. But we see that adding these low wind options

6 improves the model performance, especially with the beta U*

7 option for the monitor in high terrain. The low wind

8 options--the LowWind2 options result in somewhat incremental

9 performance improvements.

10 Also, we noticed for that elevated monitor that

11 the meteorological conditions observed for the highest

12 concentrations were more aligned with the predicted

13 conditions when we added that ADJ_U* option because without

14 it, all--almost every high hour was predicted to be at night. 

15 But several high hours were predicted to be during the day--

16 were monitored to be during the day. With the ADJ_U* option,

17 the predicted conditions were more in line with the observed

18 conditions for the highest concentrations.

19 So the overall results from this database were

20 that the AERMOD default predicted the highest--overpredicted

21 substantially at the elevated monitor. The low wind options

22 did improve the performance at all monitors. It turns out

23 that even a minimum sigma-v of 0.5 was still relatively

24 unbiased, did not underpredict.

25 The other database is Gibson and the monitors are
140

KAY McGOVERN & ASSOCIATES (919) 870-1600

Suite 117, 314 West Millbrook Road FAX 870-1603

Raleigh, North Carolina 27609-4306 (800) 255-7886

1 the four monitors with the yellow triangles. This is a very

2 flat terrain, tall stack database. Similar type of

3 appearance of the results here, but we see that with the flat

4 terrain, there is no real response to the ADJ_U*. In fact

5 with Mount Carmel, the beta U* option has a high wind side

6 effect. Sometimes high winds cause the predictions to go up

7 with the ADJ_U* option. 

8 But by and large they were pretty much unaffected

9 by the ADJ_U* option--this is the yellow--and a little bit of

10 an effect with the LowWind2 option. Certainly the low wind

11 options did not do too much to this database, improved it

12 slightly.

13 So the overall evaluation results again were

14 relative insensitivity to the model performance on the basis

15 of low wind options because the concentrations were predicted

16 and observed during daytime conditions--there will be more

17 about that in the next presentation--relatively insensitive

18 to, you know, anything you do with stable conditions and a

19 little bit of sensitivity to the minimum sigma-v. But since

20 the winds causing the highest concentrations were a little

21 bit too high, higher than those very low wind speeds, not

22 much of an effect. We still had, though, a general

23 overprediction from 10 to 50 percent.

24 Overall conclusions would be that the--and as I'm

25 going to say at the bottom, we haven't yet conducted or had
141

KAY McGOVERN & ASSOCIATES (919) 870-1600

Suite 117, 314 West Millbrook Road FAX 870-1603

Raleigh, North Carolina 27609-4306 (800) 255-7886

1 time to do any further testing on the new release, but as

2 Roger indicated, we would not expect much of a change from

3 what we've seen so far with the LowWind3 option.

4 Tall stacks would have the lowest effect with

5 these low wind options with high terrain. There's a minor

6 effect only with flat terrain. But the effect in elevated

7 terrain is very profound, especially as you get very high

8 terrain. And so this ADJ_U* option will be extremely

9 important to put into the model and to have it as a default

10 option.

11 We note that the LowWind3 option only has a

12 minimum sigma-v of 0.3, so the fact that we still didn't get

13 underprediction at 0.5 would mean that the LowWind3 option in

14 version 15181 is likely to be still slightly conservative. 

15 The low wind options also improved the consistency of the

16 prediction of the meteorological conditions associated with

17 the highest observed and the highest predicted concen18 trations.

19 So we do believe that the proposed options will

20 result in more accurate AERMOD predictions and we would like

21 to have the ability to use these options very soon in routine

22 modeling assessments. I think that is the last slide. I

23 gave you 45 seconds.

24 Mr. Bridgers: Thanks, Bob. So once again I'd

25 like to introduce to the podium Bob Paine.
142

KAY McGOVERN & ASSOCIATES (919) 870-1600

Suite 117, 314 West Millbrook Road FAX 870-1603

Raleigh, North Carolina 27609-4306 (800) 255-7886

1 Mr. Paine: Thank you. These are issues

2 related to--maybe it's an issue that people have not been

3 generally aware of, but you can also call this "Beware of the

4 Penetrated Plume." And this work followed from work we did

5 in the previous--the low wind study, but it's also related to

6 other interactions I've had with other investigators, this

7 time Down Under, as you'll see.

8 I'm going to talk about the overview of the

9 issues: available diagnostic tools that most people don't

10 have access to that have allowed us to find out what's really

11 happening with the predictions in tall stack releases of

12 AERMOD, available model evaluations that have shed more light

13 on why this is an issue of concern, the evaluation results,

14 and conclusions.

15 Now, we've noted--we've done a lot of modeling

16 applications with tall stacks and we noticed that in many

17 cases the highest one hour predictions--and this is obviously

18 applicable to SO2, because that's a one hour standard--we

19 keep seeing daytime conditions with low mixing heights and

20 low winds leading to the highest predictions, so that's

21 interesting. 

22 Observations tend to indicate that, well, the peak

23 predictions for tall stacks are expected to be during the

24 daytime, but they're not always during low mixing heights. 

25 They're randomly scattered between low and high mixing
143

KAY McGOVERN & ASSOCIATES (919) 870-1600

Suite 117, 314 West Millbrook Road FAX 870-1603

Raleigh, North Carolina 27609-4306 (800) 255-7886

1 heights. So why is the model tending to favor just low

2 mixing heights rather than a variety of mixing heights? 

3 We have the ability, and I'm going to show an

4 example, of debugging output from AERMOD that indicated that

5 the cause of these highest predictions is due to plumes that

6 are actually emitted into the stable air aloft initially, but

7 somehow reach the ground within a relatively short distance,

8 maybe 5 kilometers, maybe a little bit more than that. 

9 And that condition is associated with--and I'm

10 going to show an example of the three plume treatment in

11 AERMOD, but the penetrated plume is the plume that is

12 injected into the stable layer aloft. Previously that plume

13 was totally ignored. In the ISC model the prediction of that

14 plume was assumed to be zero. 

15 Now, believe it or not, it's actually controlling

16 the design concentration in AERMOD for tall stack releases in

17 flat terrain. Obviously in complex terrain it's stable

18 conditions, but this is for simple terrain, tall stacks in

19 AERMOD.

20 This picture I'm sure is from several training

21 figures that have been provided. Imagine here that the top

22 dashed line is the convective mixing height; the lower dashed

23 line is the mechanical mixing height. The direct material is

24 assumed to be material that does not really interact or bump

25 up against the mixing height in convective conditions and it
144

KAY McGOVERN & ASSOCIATES (919) 870-1600

Suite 117, 314 West Millbrook Road FAX 870-1603

Raleigh, North Carolina 27609-4306 (800) 255-7886

1 is mixed to the ground directly, no interaction with the

2 mixing lid.

3 The indirect material does not have enough

4 momentum or buoyancy to penetrate into the stable air aloft,

5 but it hangs up like a balloon on a ceiling against the

6 mixing lid and then eventually mixes down. But the

7 penetrated plume gets up into there and would not really be

8 expected to get down to the ground very rapidly.

9 Another depiction shows that the model treats

10 these plumes as separate--almost separate releases that has

11 different calculation do loops for--accounting for their

12 impacts but then adds them all together. So the part of the

13 plume above the inversion layer or into the inversion layer

14 is related to the part--you know, the mass that's allocated

15 to the prediction is the total mass emitted times the

16 penetration fraction. And when that penetration fraction

17 gets toward 1.0, that plume becomes very important in the

18 calculation.

19 Here's just a visualization of what you might

20 envision as a penetrated plume being. It's daytime. The

21 plume goes up and it hits the stable air and it just sort of

22 goes off to the left. It doesn't really mix down to the

23 ground, visually at least in the realm of this picture.

24 Now, you probably can't see this, but I'm going to

25 point out we have this debugging output that actually comes
145

KAY McGOVERN & ASSOCIATES (919) 870-1600

Suite 117, 314 West Millbrook Road FAX 870-1603

Raleigh, North Carolina 27609-4306 (800) 255-7886

1 from a--the bottom indicates we had actually downloaded this

2 version of AERMOD, version 14134, available for download at

3 the EPRI web site where you can get other things like EMVAP. 

4 It has a lot of useful debugging information.

5 The top part that's circled in red is the

6 mechanical and convective mixing height. In this case--I'll

7 just read off the number--the convective mixing height, which

8 is a little higher than the mechanical mixing height, is 256

9 meters. We have a final plume height--what happens for each

10 hour is that the controlling receptor is listed for each

11 source model, and all sorts of information about what's

12 happening at that receptor is displayed.

13 We know what the final plume height is. The final

14 plume height is about 355 meters versus a convective mixing

15 height of 256 meters. So the plume gets up to be about 100

16 meters into the stable air aloft. But the dominant plume is

17 identified as the penetrated plume. We know that because the

18 debugging information polls that it's--is it direct, is it

19 indirect, is it penetrated. The penetrated wins because it

20 has 90 percent of the mass. And that hour turned out to be

21 the highest predicted hour for that whole simulation.

22 So we can identify with this debugging output what

23 is causing the highest predicted concentrations. That's not

24 usually displayed in the version of AERMOD that comes out of,

25 you know, EPA. This is additional debugging information, but
146

KAY McGOVERN & ASSOCIATES (919) 870-1600

Suite 117, 314 West Millbrook Road FAX 870-1603

Raleigh, North Carolina 27609-4306 (800) 255-7886

1 we have lots of evidences of what is happening.

2 Now, I've been talking over the years with Dr. Ken

3 Rayner of Perth, Australia, who likes to dabble with code. 

4 And if he doesn't understand anything about AERMOD, he would

5 dicker with the code and change it. And he was very

6 interested in using AERMOD and CALPUFF and trying to get the

7 best model, and he had observed data from tall stacks and

8 simple terrain. And he had a presentation with a link here

9 that you'll be able to download when you download this whole

10 presentation.

11 The map here shows that in western Australia there

12 was a source, Muja power station, which is the lowest red dot

13 there, and the Shotts monitor, which is about 8 kilometers

14 from--circled in blue is a monitor where there was a model

15 evaluation conducted, relatively low terrain between the

16 power plant and the monitor.

17 The Q-Q plot that Dr. Rayner provided shows both

18 the AERMOD with the penetrated plume and then with the

19 penetrated plume disabled because he went into the code and

20 disabled it. He shows about a 50 percent overprediction at

21 that monitor, and with--you know, with obviously the

22 penetrated plume disabled he can show that the difference is

23 such that you need some of the penetrated plume there, but it

24 makes a big difference and it's really the cause of the over25 prediction.
147

KAY McGOVERN & ASSOCIATES (919) 870-1600

Suite 117, 314 West Millbrook Road FAX 870-1603

Raleigh, North Carolina 27609-4306 (800) 255-7886

1 So he had comments in his presentation that he

2 believed that AERMOD mixes the plume to the ground too fast

3 because it has to do everything in one hour, whereas a

4 penetrated plume might be looked upon as a multiple hour

5 phenomenon. The plume is injected above the mixing lid, but

6 somehow it gets down to the ground as if it mixes down into

7 the convective mixing layer in the same hour, so is all that

8 just being squeezed by a steady-state model.

9 The other issue is the mixing height is assumed to

10 be constant, but it's obviously changing within the hour, so

11 that's another issue with a steady state model. There's a

12 lot of constraints here. So he found an overprediction on

13 the order of 50 percent for his case.

14 Let's go back to Gibson. We did debugging on that

15 too. Isn't it interesting? We're also getting about a 50

16 percent overprediction due to a penetrated plume for this

17 database--consistency. 

18 So actually, I'm going to finish quickly here. 

19 We're seeing at least for these two databases a consistent

20 pattern for AERMOD peak predictions for tall stacks in simple

21 terrain. We can identify with our debugging output--or Ken

22 Rayner can identify with his debugging, his code changes, the

23 penetrated plume is causing it. It may be reaching the

24 ground too fast, and maybe it's due to sigma-z. It's

25 something that would warrant additional EPA review.
148

KAY McGOVERN & ASSOCIATES (919) 870-1600

Suite 117, 314 West Millbrook Road FAX 870-1603

Raleigh, North Carolina 27609-4306 (800) 255-7886

1 Now, Appendix W does indicate in various places

2 that the AERMOD model uncertainty is in the order of 10 to 40

3 percent. Maybe we can extend that to 50 percent based on

4 this issue. I would say that I would be happy when the model

5 is only 50 percent uncertain because that's well within the

6 factor of 2. 

7 But with these SO2 NAAQS demonstrations, if you

8 model--if the standard is 196.5 micrograms per cubic meter.

9 If you model 200, is that enough to say that you know there's

10 a violation of the NAAQS? Absolutely not. You could be 50

11 percent over the NAAQS with your model and not be able to say

12 that you know there's a NAAQS violation, especially if the

13 controlling concentration is caused by this issue.

14 We hope to be able to review the new model to see

15 if this issue is still present, but I just wanted to alert

16 the user community to this issue with AERMOD. And that's--

17 okay, I'm done.

18 Mr. Bridgers: Well, Bob, you've got 3 more

19 minutes if you---

20 Mr. Paine: (interposing) That's okay.

21 Mr. Bridgers: So at this point I'm going to

22 call to the podium Richard Hamel, not Bob Paine. And so,

23 Rich, if you'll identify yourself, you're good to go here.

24 Mr. Hamel: I have to wait till I see the

25 first second tick off, okay. I'm not Bob Paine, but I am
149

KAY McGOVERN & ASSOCIATES (919) 870-1600

Suite 117, 314 West Millbrook Road FAX 870-1603

Raleigh, North Carolina 27609-4306 (800) 255-7886

1 wearing the same shirt today. But I am Rich Hamel. I'm a

2 senior air dispersion modeler at Environmental Resources

3 Management or ERM in the Boston office. 

4 And what I'd like to talk to today is the proposed

5 move to ARM2 as the Tier 2 method for refining the NOx to NO2

6 conversion in AERMOD and take it with a bit of practical

7 approach to what does it really give us when we are trying to

8 model compliance, not only with the NAAQS, but also hoping to

9 get a model result that would have our impacts below the

10 significant impact level so we don't have to do cumulative

11 modeling.

12 Okay. So I'm going to talk about a quick overview

13 of the old--ARM and the old ARM2, which is really the ARM2

14 with a minimum NO2 to NOx ratio of 0.2, a little bit about

15 ARM2 in the proposed revision, a comparison of the Tier 2 and

16 Tier 3 options for NO2 conversion, what are some of the

17 benefits or changes in the proposed ARM2, what are some of

18 the issues, and then just a quick word about Tier 3. 

19 And you can see there the molecule for NO2 and the

20 chemical bar equation, ONO, or as we all said the first time

21 we tried to model an emergency generator against the new NO2

22 standard and saw the results, "Oh, no."

23 EPA allows us three different tiers. We know this

24 from our NOx modeling experience. Tier 1 is just assuming

25 the full conversion of NOx to NO2 through modeling. Tier 2
150

KAY McGOVERN & ASSOCIATES (919) 870-1600

Suite 117, 314 West Millbrook Road FAX 870-1603

Raleigh, North Carolina 27609-4306 (800) 255-7886

1 is the ambient ratio method based on analysis of ambient

2 monitoring data. That's the old ARM and ARM2, and then, of

3 course, Tier 3, which is refinement based on the oxidation of

4 nitrogen oxide by ozone to NO2, and that's the OLM and PVMRM

5 methods by the formula that you see there below.

6 Where did ARM originally come from? Originally it

7 was designed outside the realm of air dispersion modeling and

8 there was a decent amount of study done. But when annual NO2

9 modeling came around, the 90th percentile of the average

10 annual NO2 to NOx monitoring data, as it was known at the

11 time, was used and that established a ratio of 0.75. When

12 the 1 hour NO2 NAAQS came around, that wasn't considered a

13 conservative enough representation for short term modeling. 

14 So the ARM ratio was set to 0.8.

15 So enter ARM2. Mark Podrez in 2013 working for

16 API did a study of all of the NO2 monitors in the United

17 States and some elsewhere, which amounted to 580 monitors,

18 looking at ten years' worth of data from 2000 to 2010, which

19 gave a data set of over 5,000,000 hours to look at and the

20 ambient ratios of NO2 to NOx. Based on that data, he

21 developed a 6th order polynomial curve and found that this

22 curve fairly consistently matched the ratio of NO2 to NOx,

23 based on the amount of NOx in the ambient air.

24 So it was really designed as a simpler alternative

25 to Tier 3 refinements, a way to get a Tier 3-like effect with
151

KAY McGOVERN & ASSOCIATES (919) 870-1600

Suite 117, 314 West Millbrook Road FAX 870-1603

Raleigh, North Carolina 27609-4306 (800) 255-7886

1 a little more conservatism than OLM or PVMRM without having

2 to deal with the whole issue of finding in-stack ratio,

3 documentation for each of your sources, background ozone

4 data, and things like that, of course the advantage being

5 there are no additional inputs needed. You simply have a

6 look-up table against the curve at each of your receptors at

7 each of the hours. It would run faster than the Tier 3

8 refinements and also wouldn't require case by case approval,

9 meaning not only less time to process, but less time to

10 review.

11 And this is the original ARM2 curve against all of

12 the hours that were posted. And you can see that the curve

13 for the most part contains all of the hours that were looked

14 at during the study with some outliers at the top and results

15 in ambient ratios anywhere from less than 0.1 at very high

16 NOx concentrations of 600 ppb and above, all the way up to a

17 1 to 1 ratio, and this is in very low cases, although there

18 was also some documentation that some of those cases were

19 very specific situations that caused such a close conversion.

20 So ARM for AERMOD was added as a beta option in

21 version 12345 with an upper limit of 0.9 and a lower limit of

22 0.2, although those could also be set manually--those are the

23 defaults--required a case by case approval for use in permit

24 modeling. 

25 And the EPA webinar last year around the release
152

KAY McGOVERN & ASSOCIATES (919) 870-1600

Suite 117, 314 West Millbrook Road FAX 870-1603

Raleigh, North Carolina 27609-4306 (800) 255-7886

1 of AERMOD version 14134 recommended that if your Tier 1

2 modeling results were less than 150 to 200 ppb, then the use

3 of ARM2 should be expedited in terms of the approval process. 

4 If you had initial results higher than that, then a study of

5 the in-stack ratios of the sources being considered was

6 required. And also, special consideration was given to

7 higher thresholds in situations where background NO2 was very

8 high or if background ozone layers were very high, although

9 what exactly constituted high was not really clearly defined.

10 So old ARM2 versus Tier 3 OLM and PVMRM--and

11 remember, again, that Mark Podrez' research is really sort of

12 based around a comparison of those aspects. He used

13 sensitivity modeling around the 2004 MACTEC report for single

14 and cumulative source scenarios and expanded upon those and

15 found that at low concentrations--and now we're talking in

16 terms of micrograms per cubic meters--ARM2, OLM, and PVMRM

17 all predicted NO2 to NOx ratios around 0.9.

18 At the higher impact levels, greater than 300

19 micrograms per cubic meter, all of the different methods had

20 ratios between 0.2 and 0.4, and ARM2 was consistently a

21 little more conservative than the other two.

22 At some very high impacts, it was found that PVMRM

23 occasionally had ratios higher than ARM2, and that may have

24 been because of a formulation error that would have been

25 identified and will be addressed with the updated PVMRM2.
153

KAY McGOVERN & ASSOCIATES (919) 870-1600

Suite 117, 314 West Millbrook Road FAX 870-1603

Raleigh, North Carolina 27609-4306 (800) 255-7886

1 So updating the ARM2 development report. For a

2 project that we're doing and we're seeking approval of the

3 ARM2 method for refinement, which just happens to be the one

4 that George was talking about in terms of the Model

5 Clearinghouse, an additional analysis sort of extending what

6 Mark had done in the original ARM2 research was undertaken. 

7 All monitors in the United States were looked at

8 between 2001 and 2012 with a focus on monitors that were

9 similar to the project site, which was a rural-ish project

10 site, so some of the urban monitors were removed. The

11 resulting data set still gad more than 4,000,000 data points

12 and the number of observations increased as the years go on. 

13 You can see that in 2001 there were less than half as many as

14 there were in 2009 (sic).

15 Ultimately, ARM2 was approved. It did get through

16 the Model Clearinghouse very quickly once it got there, but

17 it took nearly a year to get the data and a lot of back and

18 forth with the regulating agencies to get that all put

19 together, ultimately with a minimum NO2 to NOx ratio of 0.54,

20 which as it turned out is higher than the recommended for the

21 proposed default now. So if we had waited a year, we could

22 have gotten it a little lower apparently.

23 Here are some of the observed data points from

24 that research. These are color coded by groups of hours.

25 Because the hours were densely packed, it wasn't possible to
154

KAY McGOVERN & ASSOCIATES (919) 870-1600

Suite 117, 314 West Millbrook Road FAX 870-1603

Raleigh, North Carolina 27609-4306 (800) 255-7886

1 put a single dash for every hour, so the colored hours are

2 groups of hours. 

3 And you can see that if we look at the data in

4 three year blocks, from 2001 to 2004, the data mostly fit the

5 curve, the ARM curve being the red line that goes down across

6 to the right. And there were some outlying hours above the

7 curve all the way from 100 to 600 micrograms per cubic meter.

8 Moving to the next three years, we see roughly the

9 same pattern, although the outliers tend have fallen a bit

10 farther down towards the curve. And looking at the most

11 recent four years, you see that not only have most of the

12 outliers fallen out, but the general curve now appears to

13 even perhaps be a little conservative compared to the

14 predominant amount of observed hours.

15 The proposed revisions would replace the old ARM,

16 which was, again, 0.8 in the modified version of ARM2. And

17 it's not really a modification of the curve. The

18 modification is that the new ARM2 would have a default of 0.5

19 instead of 0.2, which is really tied into the Tier 3 refine20 ments that use 0.5 as your standard in-stack ratio.

21 And a review of the current EPA in-stack ratio

22 database, which has 2,323 entries, show that of those entries

23 about 4.5 percent have in-stack ratios greater than 0.5,

24 about 23 percent have those greater than 0.2, and then the

25 other 77 percent are below 0.2. So the 0.5 is really
155

KAY McGOVERN & ASSOCIATES (919) 870-1600

Suite 117, 314 West Millbrook Road FAX 870-1603

Raleigh, North Carolina 27609-4306 (800) 255-7886

1 protective of just about every--or a very high percentage of

2 the in-stack ratios that are found in the database, 95

3 percent in fact.

4 So one of the things I want to do is look at,

5 well, if I'm modeling this, what does this really mean to me? 

6 So I considered a concept of compliance ranges, meaning if I

7 get a certain NOx concentration--or what NOx concentration do

8 I need that's greater than the standard of 188 micrograms per

9 cubic meter that actually would fall into a range where the

10 conversion would put me below 188 and therefore in compliance

11 when I don't consider ambient background or other sources and 

12 stuff like that.

13 So the old ARM, using the 0.8 conversion, would

14 give you a result--if your model concentration landed from

15 189 to 235, you end up with a number below 188. The proposed

16 ARM2 improves on that, moving the compliance range up to 376,

17 which again is an improvement over the old ARM in that way

18 compared to the current ARM or the beta ARM2 of 0.2. You can

19 see that the compliance range was actually much higher, all

20 the way up to 940, because up at that point you're getting an

21 in-stack ratio of 0.2, or a conversion ratio of 0.2, so quite

22 a difference.

23 So what are some of the issues, however? Well,

24 ARM2 sometimes provides higher results than the old ARM did

25 simply because the curve exceeds 0.8 anytime your NOx concen-
156

KAY McGOVERN & ASSOCIATES (919) 870-1600

Suite 117, 314 West Millbrook Road FAX 870-1603

Raleigh, North Carolina 27609-4306 (800) 255-7886

1 tration is greater than--or sorry, less than 149 micrograms

2 per cubic meter. Now, you're already below the standard at

3 that point, but again, that's not considering ambient

4 background. And if you have an ambient background that's up

5 in the range of 50 micrograms per cubic meter, this can be

6 significant. You may find compliance using ARM, but not find

7 it using ARM2.

8 The same problem or issue--I won't call it problem

9 necessarily--when considering SIL modeling where an NOx

10 concentration, for example, of 9.4 if you're using ARM, gets

11 you to the 7.5 SIL, whereas a NOx concentration of 8.4 would

12 be over the SIL using ARM2 because the conversion ratio would

13 be higher than 0.8.

14 Now, you are allowed in theory to ask for a lower

15 minimum ratio with your ARM2, but there are some problems

16 there that actually might make it more difficult to gain

17 approval than getting in-stack ratios approved for Tier 3. 

18 And the issue there is with Tier 3, you deal on a stack by

19 stack basis. So if you have ten sources of varying kinds,

20 you can negotiate an in-stack ratio on each of those sources.

21 It's unclear based on ARM2 how you would negotiate

22 a lower minimum when you may have several different sources--

23 one has a 0.2, one has a 0.1, one has a 0.5--different

24 operating characteristics, different percentages of the

25 overall emissions. So it's unclear exactly where that goes.
157

KAY McGOVERN & ASSOCIATES (919) 870-1600

Suite 117, 314 West Millbrook Road FAX 870-1603

Raleigh, North Carolina 27609-4306 (800) 255-7886

1 Because I'm running out of time, I'm going to just

2 skip the quick summary of the Tier 3 message and go to the

3 conclusions. So again, ARM2 was originally conceived as a

4 simpler alternative to a Tier 3, but that's no longer the

5 case. That was really a replacement for the ARM method.

6 You have a greater compliance range than ARM did,

7 but less than the beta version does. In some cases--with 30

8 seconds to go--ARM provides better refinement or more

9 refinement than ARM2 did when you're modeling against the

10 SIL. And then there are questions as to how does one justify

11 a lower minimum in the case of a site with a variety of

12 sources.

13 And we see that the ambient NO2 to NOx curve seems

14 to be decreasing, either based on less ambient ozone or other

15 factors or maybe because we removed the urban monitors. So

16 the question is does that need to be updated at every certain

17 amount of time or perhaps a study done between an urban curve

18 and a rural curve. And that will be it. Thank you for your

19 time.

20 Mr. Bridgers: Rich, I was actually going to

21 give you a couple of extra seconds because of the computer

22 snafu. 

23 (Pause.)

24 Our apologies, a technical issue with Microsoft

25 Office. It decided to make my screen twice as large, and
158

KAY McGOVERN & ASSOCIATES (919) 870-1600

Suite 117, 314 West Millbrook Road FAX 870-1603

Raleigh, North Carolina 27609-4306 (800) 255-7886

1 it's not simple to make it the same.

2 (Pause.)

3 So with the technical snafu partially fixed, Cathe

4 is going to actually talk from her slides here up there, so

5 Cathe, the podium is yours.

6 Ms. Kalisz: Good afternoon, everyone. I'm

7 Cathe Kalisz with the American Petroleum Institute or API. 

8 And this presentation provides an overview of some ongoing

9 API work that's looking at AERMOD with an alternate NOx

10 chemistry scheme, an alternate to the Tier 3 NO2 options.

11 So the chemistry scheme that we're using comes

12 from the Atmospheric Dispersion Modeling System or ADMS. 

13 Some of you may be familiar with it. I think Chris

14 referenced it in one of his presentations. And it's commonly

15 used in Europe.

16 This work was prompted by a modeling study by one

17 of our API member companies who wanted to compare the NO2

18 performance of the ADMS model and AERMOD. And the results of

19 that study suggested that ADMS chemistry might have better

20 predictive skill than the NO2 options in AERMOD, and so that

21 prompted this project.

22 So what you'll see on the slides in this

23 presentation compare--when I say the current version of

24 AERMOD, I'm talking about 14134 that's been coded with an

25 ADMS chemistry option and then we're comparing those to the
159

KAY McGOVERN & ASSOCIATES (919) 870-1600

Suite 117, 314 West Millbrook Road FAX 870-1603

Raleigh, North Carolina 27609-4306 (800) 255-7886

1 Tier 3 option. And so we will be updating these evaluations

2 to look at new AERMOD 15181 and the new PVMRM2.

3 So this is some basic information about the ADMS

4 chemistry module that we're using. The work that we've done

5 uses what's referred to as the standard ADMS module, a little

6 bit more about that in a minute. So for inputs you have your

7 basic source emission rates, but you're also inputting the

8 background values for NO2 and ozone. 

9 And so the model works by calculating the NOx and

10 NO2 concentrations at the receptors, and then it also

11 calculates at each receptor the weighted, by the source

12 contribution, mean travel time of the pollutant. And it adds

13 the background concentrations and then applies the two

14 chemical reactions that you see over the mean travel time.

15 So with respect to chemistry, the two key

16 differences between the ADMS chemistry module and the Tier 3

17 options are that it includes reactions for both NO ozone

18 titration and NO2 photolysis. And it also accounts for

19 chemical reaction rates.

20 I was asked by someone, you know, do you see any

21 difference in model run times with this, and I guess this is

22 qualified that for the work we've done thus far there's been

23 no appreciable difference in the run time. However, we

24 haven't tested it with a data set that has hundreds of

25 sources, so that may change as we do more work.
160

KAY McGOVERN & ASSOCIATES (919) 870-1600

Suite 117, 314 West Millbrook Road FAX 870-1603

Raleigh, North Carolina 27609-4306 (800) 255-7886

1 This is just a further comparison of the ADMS and

2 the AERMOD options. We've talked about the chemistry. One

3 other thing I'll point out, that with respect to ozone

4 entrainment, ADMS has the standard version that we're using

5 and then there's also a dilution and entrainment option. So

6 the standard ADMS works like OLM, and that's what we used for

7 the work you're going to see.

8 So in our evaluations we used five data sets. 

9 Everyone is probably familiar with the first three: the

10 Palaau and the Empire Abo North and South data sets. We also

11 included Wainwright. That was a small power plant on the

12 Alaskan North Slope and then Prudhoe Bay, which was a

13 drilling operation in Prudhoe Bay. 

14 One adjustment that our consultant did make for

15 Empire Abo and Palaau is after looking at the observations

16 for the data decided to adjust the in-stack ratios from 0.2

17 to 0.1 because it appeared to be more representative.

18 So these next series of slides--and I tried to

19 cram a lot of information on them, given the ten minutes. So

20 for each one you'll see in the lower right-hand corner

21 there's a summary of the model versus observed results for

22 AERMOD NOx and for the three NO2 options. In the right-hand

23 corner you'll see a correlation coefficient between the

24 observed and modeled NO2 to NOx ambient ratios and then of

25 course the Q-Q plots for NO2.
161

KAY McGOVERN & ASSOCIATES (919) 870-1600

Suite 117, 314 West Millbrook Road FAX 870-1603

Raleigh, North Carolina 27609-4306 (800) 255-7886

1 So if you're looking at Palaau, ADMS, and PVMRM,

2 you know, pretty similar in results. OLM has got higher

3 predicted concentrations. If you look at the correlation for

4 the ambient ratios, very good for PVMRM and ADMS. 

5 Unfortunately, they only go downhill from here, at least for

6 the ratios.

7 Here is Empire Abo North, again, you know, all

8 three options pretty much the same. PVMRM as you get to

9 higher concentrations is overpredicting. If you look at the

10 correlation, they're all positive. ADMS is the highest one

11 there.

12 Here is Empire Abo South. And again, ADMS and OLM

13 look about the same. PVMRM is a lot higher, although if you

14 look in NO2 technical support document, PVMRM2 has definitely

15 made a difference in what you'll see here; also noted that

16 for the ratio correlation PVMRM is negative.

17 This is Wainwright. With respect to the Q-Q

18 plots, the PVMRM looks to be the best performer, although,

19 you know, again, a negative correlation on the ambient ratio

20 was calculated. 

21 And lastly, Prudhoe Bay. One thing I'll mention

22 is because the model was significantly underpredicting AERMOD

23 for NOx, we're not sure, you know, how much you can compare

24 these various options. We're not sure if this large

25 difference for AERMOD was due to the fact that the monitor
162

KAY McGOVERN & ASSOCIATES (919) 870-1600

Suite 117, 314 West Millbrook Road FAX 870-1603

Raleigh, North Carolina 27609-4306 (800) 255-7886

1 was very close to the source or the drilling structures

2 weren't characterized, but a definitive difference.

3 Here's just a summary of the comparisons for the

4 five data sets. So for OLM, generally overpredicts the NO2

5 concentrations, had the lowest proportion of values within a

6 factor of 2. The ratio correlations were generally poor.

7 For PVMRM, it had the best mean NO2 concentration,

8 had a reasonably high proportion of values within a factor of

9 2. However, the ambient ratio correlations were generally

10 poor, and you had--I guess it was three out of the five data

11 sets you had a negative correlation.

12 For the ADMS module, again, it generally over13 predicts the NO2 concentration. It had a reasonably high

14 proportion of values within a factor of 2. Although they

15 weren't the best, they did show the most consistent

16 performance considering the correlation for the NO2/NOx

17 ratios.

18 As part of the effort thus far, we also did some

19 sensitivity modeling using a single source 121⁄2 meter stack

20 and looked at various met conditions. I've just provided one

21 example here. This is for near-field NO2 concentrations,

22 stable early morning, moderate wind speeds. And you can see

23 in the upper graph the NO2 concentration. The ADMS and OLM

24 are practically on top of each other and PVMRM is much higher

25 predicted NO2. And yes, I won't even talk about the ratio
163

KAY McGOVERN & ASSOCIATES (919) 870-1600

Suite 117, 314 West Millbrook Road FAX 870-1603

Raleigh, North Carolina 27609-4306 (800) 255-7886

1 part, which looks even weirder.

2 What our consultant decided to do for fun was to

3 take the inputs for this sensitivity run and put them in

4 AERMOD 15181, and the results for PVMRM2 were similar. So

5 this is definitely a scenario that we'll look at in our

6 continuing work.

7 So these are the planned next steps for this work. 

8 We'll be adding the ADMS chemistry code into AERMOD 15181 and

9 then we'll rerun the evaluations. We'll also do some

10 additional sensitivity testing using single and multisource

11 scenarios. 

12 We're hopeful that we'll have--be able to do some

13 evaluations using NO2 data sets that come from a WRAP study. 

14 These are for drilling sites in Colorado and Alaska. These

15 are probably the first data sets we have that have much more

16 accurate emissions because for both of these studies, there

17 were CEMS on the engines and the boiler stacks.

18 And then, lastly, a new task that--or the

19 developer is going to consider making further modifications

20 to their standard ADMS chemistry module to perhaps use a more

21 simplified version of the ADMS dilution and entrainment

22 module, maybe drawing on some of the parameters from PVMRM2.

23 And so in closing, I would just want to note that

24 for this model development work and for the other development

25 work that we've heard about and that we'll hear about during
164

KAY McGOVERN & ASSOCIATES (919) 870-1600

Suite 117, 314 West Millbrook Road FAX 870-1603

Raleigh, North Carolina 27609-4306 (800) 255-7886

1 this conference, I think it's very important that we have a

2 process or a structure that provides for timely testing and

3 implementation of model improvements.

4 Mr. Bridgers: Thank you, Cathe, and thank you

5 for dealing with the technical snafu here. I will let Bart

6 identify himself, and this one should look pretty normal so

7 you should be able to see it, I hope. It's all yours.

8 Mr. Brashers: Hello, everyone. I'm Bart

9 Brashers from Ramboll Environ. It used to be Environ before

10 the recent merger. I've been the developer and keeper of the

11 MMIF code for a couple of years now, since I think just after

12 version 1 came out. And I should acknowledge my co-authors

13 here, Ralph and Jason, who are both in the audience here, so

14 you can go ask them questions afterwards. Here's a little

15 bit of a show of the complex terrain that we're going to talk

16 about today.

17 So switching gears completely and probably one of

18 the--maybe one of the less controversial parts of the changes

19 are this use of prognostic or numerical weather prediction

20 code to drive AERMOD. So I thought I would give you the

21 quick 30 second introduction to MMIF.

22 The Mesoscale Model Interface Program takes

23 numerical weather prediction models like the weather research

24 and forecasting model and its predecessor, MM5, converts

25 their output to feed dispersion models, in historical order
165

KAY McGOVERN & ASSOCIATES (919) 870-1600

Suite 117, 314 West Millbrook Road FAX 870-1603

Raleigh, North Carolina 27609-4306 (800) 255-7886

1 CALPUFF, AERMOD, and SCICHEM. We're going to talk about

2 AERMOD today.

3 MMIF supports AERMOD in three ways. You can go in

4 the direct mode or AERMOD mode. I like to think of it as

5 what's the model you're going to run next. AERMOD mode, you

6 run WRF, you run MMIF, and it outputs the profile and service

7 files, the PFL and SFC files, directly and you run AERMOD and

8 you're done.

9 In AERMET mode you run MMIF and it outputs an 

10 on-site data file. You don't have to use a surface pathway

11 at all. And then you run it through AERMET and then you run

12 AERMOD. And it also supports up here--you can barely see it

13 with this screen--in AERCOARE mode. It's nicely grayed out

14 because that's for over water use and we're not going to talk

15 about that today.

16 Here's the situation. It's the Monongahela River

17 Valley in Allegheny County, southeast of Pittsburgh,

18 Pennsylvania. There are several sources of SO2 in the area. 

19 Mostly they put the industrial sources near the valley floor.

20 At Liberty High School up on the ridge on the hill

21 there is an SO2 monitor and has measured a number of SO2

22 exceedances and NAAQS violations. So there's been a

23 nonattainment area designated and where SIP revision is

24 required. And Allegheny County came to us and asked us to

25 help them out back when we were Environ.
166

KAY McGOVERN & ASSOCIATES (919) 870-1600

Suite 117, 314 West Millbrook Road FAX 870-1603

Raleigh, North Carolina 27609-4306 (800) 255-7886

1 So we had already done some initial work that

2 looked like traditional AERMET with the station at Liberty,

3 which has a met station as well with the closest airport as

4 backup. It was not producing very accurate results, so we

5 thought we would do a model shoot-out, throw all the models

6 that we can at them and hope for a clear winner. So we're

7 not going to talk today about SCICHEM or CALPUFF. And again,

8 there's CALWRF, CALMET, and CALPUFF in the available there.

9 But we can run the observations through AERMET and

10 into AERMOD or you can run via the WRF pathway through MMIF

11 either directly to AERMOD or through AERMET. So that's a lot

12 of potential options.

13 So we ran WRF for them. We ran five nested

14 domains, started out with the 36 kilometer domain, which

15 almost everybody who does CMAQ or CAMx work uses that same

16 projection, and nested down 3 to 1 ratios all the way down to

17 1.33 kilometers and 444 meters, which is the red box you see

18 here. The usable domain, fortunately, is the blue box, which

19 fully spans the nonattainment area in bright green and their

20 sources.

21 There are a few sources that were outside of the

22 nonattainment area. This one up here in Pittsburgh, which is

23 actually outside of the usable part of the domain, screened

24 out, so we didn't have to worry about it.

25 We ran a little pilot project for about a month. 
167

KAY McGOVERN & ASSOCIATES (919) 870-1600

Suite 117, 314 West Millbrook Road FAX 870-1603

Raleigh, North Carolina 27609-4306 (800) 255-7886

1 It looked good, so we ran a production year of one year of

2 WRF data to do the model shoot-out. And while we were doing

3 that, we kept running WRF, so we have a three year period now

4 to play with.

5 Here is the WRF terrain for that innermost 444

6 meter domain. You can see WRF for numerical reasons has to

7 smooth the terrain. But even in WRF's terrain here, you can

8 see there's places, several places along in here, where the

9 contour lines here are very close together. It's pretty

10 steep. The difference between elevation between the valley

11 floor and the tops of these crests here is around 130 meters. 

12 So it's not quite the Rocky Mountains, but because of the

13 short distances, it's kind of getting close to complex

14 terrain.

15 We can zoom in a little bit here on the two

16 meteorological sites, observation sites. There's the Liberty

17 monitor up there on the hill and the met station is very

18 close to it. And you can--here's the regional county airport

19 up there on the plateau also. And you can kind of guess by

20 the direction of the landing strips that the predominant wind

21 direction is sort of perpendicular to this valley here.

22 You can also see two of the sites, two of the

23 sources. And each of these square black boxes is a 444 meter

24 WRF grid cell. So it's about three or so cells that are

25 across the flat part of the bottom of the valley and maybe
168

KAY McGOVERN & ASSOCIATES (919) 870-1600

Suite 117, 314 West Millbrook Road FAX 870-1603

Raleigh, North Carolina 27609-4306 (800) 255-7886

1 five, if you think of it from crest to crest. So I had great

2 hopes that this would resolve the terrain reasonably well.

3 So the key features of our approach, we started

4 out with--we put a receptor at the SO2 site and then we put

5 rings of receptors at 100 meter increments up to 500 meters

6 radius around it. That was both so that we could see if

7 there was any gradient in the area of the receptor and

8 borrowing from the kind of CMAQ and CAMx style model

9 evaluations, we often allow for a slight miss. You pick a

10 receptor nearby that has a higher value and pick the max

11 within--near the site so that you're taking an observation

12 and allowing for a slight miss in space.

13 Probably the most interesting feature of our

14 approach here was that we had this valley with more than half

15 a dozen, around ten or so, sites up and down the valley at

16 different orientations. And rather than using one meteoro17 logical data set for all of them, we pretended, by using

18 MMIF, that each site had its own met tower. So we did a MMIF

19 extraction at each site, every one of them, and then you run

20 AERMOD for each site and output to POSTFILEs for the same

21 receptor set, add them up, and do your statistics afterwards.

22 We did both hourly statistics--and again, I was

23 thinking borrowing from the kind of CMAQ style evaluations

24 where you often allow for a slight miss in time, kind of

25 analogous to a slight miss in space, taking the nearest
169

KAY McGOVERN & ASSOCIATES (919) 870-1600

Suite 117, 314 West Millbrook Road FAX 870-1603

Raleigh, North Carolina 27609-4306 (800) 255-7886

1 highest receptor. But rather than just missing by an hour or

2 two, we decided to take the max daily statistic because

3 that's what the max is actually based on anyway.

4 And then we did the whole lot of sensitivity runs. 

5 The most interesting ones that we're going to talk about

6 today are these three questions, how tall of a met tower do

7 you need? Are we going to emulate a 10 meter tower like you

8 would find at a National Weather Service site, an airport,

9 where the profile file just contains one or two layers. 

10 Are we going to emulate a tall, multilevel tower? 

11 We started out with the ten levels that are the default for

12 the FLM CALPUFF levels that were the default in MMIF and they

13 still are. And we subtracted a few levels, we added a few

14 levels, saw if that made a difference.

15 We ended up with 17 levels, kind of going back to

16 the original philosophy of MMIF, which was don't mess with

17 the met, just pass it straight through. So we took the

18 native WRF levels as close as we can, all of the levels up to

19 250 meters, and just passed them straight through.

20 We have not yet run the MMIF guidance levels,

21 which is pretending that you have a multi-instrumented 5

22 kilometer tall tower. That's more information; right? The

23 more information you feed AERMOD, the better it gets.

24 The next question we answered is about domain

25 resolution--I only looked at the four smallest domains--and
170

KAY McGOVERN & ASSOCIATES (919) 870-1600

Suite 117, 314 West Millbrook Road FAX 870-1603

Raleigh, North Carolina 27609-4306 (800) 255-7886

1 then some talk about mixing heights.

2 But you end up with a whole lot of data. And

3 rather than going all the way though the Cox-Tikvart

4 methodology to the final protocol to the final hot spots, I

5 looked at the original numbers. I don't know if you guys can

6 all read this there in back. Yeah? Okay. I got a thumbs up

7 in the back row.

8 So I color coded them all. Green is good. Red

9 and blue are underprediction and overprediction in a--sort of

10 bias-like statistics. And red is bad in a--like an error

11 style statistic. So we were hoping that one of these would

12 pop out to be all green and we'd be all good. 

13 I think that you could conclude from this that

14 there are some clear losers, but there's not any clear

15 winners. There's no lines here that have all green. So we

16 can look a little bit more closely at just a few of them

17 here--moderately legible. I was worried about this slide.

18 So here at the top line we have the observations.

19 The 99th percentile--we added some other statistics that are

20 not part of the Cox-Tikvart set, but the 99th percentile for

21 the year was 257 micrograms per cubic meter. There were five

22 exceedances. And then the rest of Cox-Tikvart statistics--I

23 could flip it down to 2 here. A lot of people like the

24 robust highest concentration. It was 243 micrograms per

25 cubic meter.
171

KAY McGOVERN & ASSOCIATES (919) 870-1600

Suite 117, 314 West Millbrook Road FAX 870-1603

Raleigh, North Carolina 27609-4306 (800) 255-7886

1 And then the top line is traditional AERMET with

2 AERMOD, so this is using the Liberty site through the on-site

3 pathway and the regional airport for the surface pathway. 

4 And you can see the 99th percentile is grossly under5 predicted. It didn't predict any NAAQS exceedances. The

6 rest of the statistics are all not horrible, but the robust

7 highest concentration really pops out there. So you can't

8 say that AERMOD--traditional AERMOD didn't do particularly

9 well.

10 The next two lines we have MMIF in AERMET mode

11 first and then two lines of MMIF in AERMOD mode, first with

12 the 10 meter tower and then with the 250 meter tower. So if

13 you really like the coefficient determination and maybe the

14 fractional gross error and the geometric correlation

15 coefficient down here, then I think you can conclude that the

16 tall towers did better than the short towers.

17 But if you look at the number of--the 99th

18 percentile, it's a little bit higher with the towers, but

19 there are more exceedances with the short--I'm sorry. 

20 There's more exceedances with AERMET than there are with

21 AERMOD. And the towers did slightly better, but very slight,

22 I think, with the 99th percentile. And down here at the

23 robust highest concentration, the shorter towers did better,

24 so kind of a mixed take-away here. 

25 I don't think that you can say that the tall tower
172

KAY McGOVERN & ASSOCIATES (919) 870-1600

Suite 117, 314 West Millbrook Road FAX 870-1603

Raleigh, North Carolina 27609-4306 (800) 255-7886

1 or the short tower did particularly better or worse, and I

2 don't think you can say that the AERMET versus AERMOD mode

3 produced very much difference. Maybe there's a slight

4 preference towards AERMET mode and a slight preference

5 towards taller towers.

6 We can look at the Q-Q plots and don't worry about

7 the numbers there. The only thing you should know is that

8 these are in log Q-Q plots, so the factor of 2 is a straight

9 line. And you can see that traditional AERMET grossly

10 underpredicted the high end of the concentration and most of

11 the low end of the concentration. It's in the mid range.

12 Here are the Q-Q plots for--on the left MMIF in

13 AERMOD mode, on the right MMIF in AERMET mode. On the top is

14 the 10 meter towers and on the bottom is the 250 meter

15 towers. Looking on the left here, the AERMOD mode did pretty

16 good. It had a little bit of a dropoff near the top. And by

17 using the tall tower, it produced worse results throughout

18 the whole spectrum of concentrations and actually made

19 everything a little bit worse--not horrible, but a little bit

20 worse. For AERMET mode, going from the short tower to the

21 tall tower didn't really affect most of the concentrations. 

22 But up here at the high end it produced lower values.

23 Moving on to the WRF resolution, here we have the

24 obs again at the top, traditional AERMET, the line below

25 that, and then sets of three, 444 meters, 1.3 kilometers, and
173

KAY McGOVERN & ASSOCIATES (919) 870-1600

Suite 117, 314 West Millbrook Road FAX 870-1603

Raleigh, North Carolina 27609-4306 (800) 255-7886

1 4 kilometers, for MMIF in AERMET mode with the short towers,

2 MMIF in AERMET with the tall towers, MMIF in AERMOD with the

3 short towers and MMIF in AERMOD mode with the tall towers,

4 and immediately what drops out at you is that the 4 kilometer

5 did horrible. There's lots of red in all the 4 kilometers.

6 Mr. Bridgers: If you want to summarize---

7 Mr. Brashers: I'll hurry it up here. So 4

8 kilometers was too close. The number of exceedances is

9 really awesome for the 1.3 kilometer. It did very much

10 better. And the robust highest concentrations did very well

11 as well. 

12 Can I actually have the 4 minutes that we got from

13 the previous speaker? This is one of the more interesting

14 parts, I think. There's three---

15 Mr. Bridgers: (interposing) Take two and---

16 Mr. Brashers: (interposing) Two, okay.

17 Mr. Bridgers: ---then post it on the web.

18 Mr. Brashers: So WRF produces PBL height. 

19 It's quantized. Each PBL scheme decides its own definition

20 of PBL height. There's no common method. So MMIF

21 rediagnoses it, and then of course there's AERMET's model for

22 the next height.

23 Here's WRF on the y-axis and AERMET on the x-axis

24 and you can see the quantization there. So on the Q-Q plots

25 it's still okay, kind of a tendency for underprediction low
174

KAY McGOVERN & ASSOCIATES (919) 870-1600

Suite 117, 314 West Millbrook Road FAX 870-1603

Raleigh, North Carolina 27609-4306 (800) 255-7886

1 and overprediction high. And this is for the mechanical

2 mixing heights, general overprediction by WRF. 

3 This is MMIFs and they're doing--the general shape

4 is a lot better. There's a tendency toward underpredicts,

5 mostly because there's a cluster of points here where MMIF--

6 sorry, AERMET and WRF disagree about the science of the

7 stability. And here is the mechanical mixing heights. The

8 Q-Q plot looks great, but that's just because it's equally

9 horribly distributed down here at the bottom. You can look

10 at this afterwards, but there's very little difference

11 between any of it. They're all the same color; right? 

12 So for the annual distribution these mixing

13 heights just didn't make very much difference. I think for

14 individual hours it makes a lot of difference what the mixing

15 height is, but in this case, using the different sources of

16 mixing height didn't make much difference.

17 So conclusions for the Liberty site, MMIF and

18 AERMOD give results on par, maybe a little bit better, than

19 traditional AERMOD. A tall tower is not necessarily better

20 than a short tower. Finer WRF resolution didn't actually

21 give us better results. The 444 meter was not better than

22 the 1.3.

23 Using too coarse for this situation definitely

24 resulted in poorer concentrations, lower maximum

25 concentrations. So that was too low. Using WRF, MMIF, and
175

KAY McGOVERN & ASSOCIATES (919) 870-1600

Suite 117, 314 West Millbrook Road FAX 870-1603

Raleigh, North Carolina 27609-4306 (800) 255-7886

1 AERMET mixing heights gave a similar statistical performance

2 over an annual SO2 distribution. MMIF and AERMET and AERMOD

3 modes, we get really similar results. So the parting shots

4 are maybe we should look at that.

5 The MMIF guidance says that this AERMET mode and

6 AERMOD mode are the same. There are some people in this room

7 who would really like a little bit more help in the guidance

8 to say that we could use AERMOD mode in locations, like say

9 over the water, where AERMET is not applicable. And then we

10 should probably talk about the PBL recalc settings and maybe

11 even look a little bit more at what it does. Thank you.

12 Mr. Bridgers: I appreciate that, Bart. Just

13 to say in passing--I'm not trying to be rude and I understand

14 typically in our conferences we let presentations run over

15 and adjust things, but just the public hearing nature of the

16 rulemaking, so I'm trying to respect that.

17 So the last presentation before the break, Tom

18 here is going to present on some more WRF/MMIF experiences.

19 Mr. Wickstrom: Hi, all. I'm Tom Wickstrom

20 with ERM and I am from ERM's Philadelphia, PA office. I'm

21 going to talk a little bit about some recent experience we've

22 had using WRF, kind of off the beaten path application of

23 WRF. And I'm also going to talk about MMIF, specifically the

24 recent proposal in Appendix W.

25 So our recent experience has shown that the WRF
176

KAY McGOVERN & ASSOCIATES (919) 870-1600

Suite 117, 314 West Millbrook Road FAX 870-1603

Raleigh, North Carolina 27609-4306 (800) 255-7886

1 model can be useful as an illustrative aid for discussions on

2 meteorological data representativeness as it applies to

3 permitting applications. I'm going to give you an example of

4 a recent AERMOD application where the met data representa5 tiveness discussion was really enhanced by using WRF data as

6 an illustrative tool.

7 I'm also going to talk about EPA's proposed

8 changes to Appendix W that includes the use of WRF or MM5

9 meteorological models as the source of the input meteoro10 logical data into a regulatory application of AERMOD. And

11 I'm going to ask the question that I had when I read Appendix

12 W: could we have used WRF/MMIF for this previous application

13 that we had and get similar model design values compared to

14 use of an off-site MET tower.

15 I'll spend a few moments here looking at our

16 application site. We have here a very wide view. You can

17 tell by the scale; that's 25 kilometers there. But the

18 isopleths here are colored, so anything that is orange, red,

19 purple, black, or yellow, that's all intermediate and complex

20 terrain. 

21 And we have the project site there. That's a 1

22 kilometer radius drawn around the project site. You can see

23 in very close proximity there's some complex terrain,

24 particularly a purple ridge running from the southwest to

25 northeast just a few kilometers to the northwest of the site. 
177

KAY McGOVERN & ASSOCIATES (919) 870-1600

Suite 117, 314 West Millbrook Road FAX 870-1603

Raleigh, North Carolina 27609-4306 (800) 255-7886

1 And we also note that we have a 60 meter meteoro2 logical tower in the nearby vicinity of this site. And that

3 was very fortunate because we can see here the nearest

4 National Weather Service sites and airports were considerably

5 far away. We're talking about 50, 60 kilometers for both of

6 them to the northeast and to the southwest. Considering the

7 complex terrain and the situation, we felt that that would be

8 a long row to hoe to justify the use of those distant met

9 data sites given the setting.

10 So yes, it's difficult to justify the use of those

11 distant airports for this particular site. And there happens

12 to be a continuously operating and maintained tall meteoro13 logical tower located just 2.8 kilometers from the

14 application site.

15 We still had a need to justify the use of that

16 tall tower despite its close proximity due to the close

17 terrain influences, so we decided to look at WRF to get a

18 better understanding of the local wind patterns due to

19 complex terrain. 

20 We ran WRF at a 1.3 kilometer resolution for this

21 analysis. And at the time we used one year of met data

22 because it was convenient to us at that time. It happened to

23 be the year 2005. There's no rhyme or reason why, but it's

24 just the year that we had readily available for this

25 application.
178

KAY McGOVERN & ASSOCIATES (919) 870-1600

Suite 117, 314 West Millbrook Road FAX 870-1603

Raleigh, North Carolina 27609-4306 (800) 255-7886

1 So let's start looking at some WRF outputs here. 

2 These are windroses derived from WRF at each node. So

3 they're at 1.3 kilometer resolution and 1.3 kilometer spacing

4 from each other. And these isopleths--these are the same

5 color scheme that was in that large figure, so orange and

6 red, purple up at the northwest there. That's all starting

7 to get into high terrain.

8 Now, this is at the 60 meter level. We can see in

9 the central part going to the north there's low lying regions

10 where the tall tower is. We see slightly lower wind speed

11 when compared to the elevated terrain. That's, you know,

12 pretty expected. But overall we're looking at a very similar

13 directional distribution of winds.

14 So if we start going up in the atmosphere in WRF,

15 now what do we see? We see the directional comparability

16 between all these modes start to really come together. We

17 still see, you know, slightly higher wind speeds in the upper

18 terrain areas as opposed to the lower, but even that is

19 starting to converge. And then when we zoom out and up in

20 the atmosphere up to nearly 500 meters, now we're essentially

21 looking at the same windrose at each WRF node for that year,

22 2005.

23 So we're trying to determine what level really is

24 important to us in this application site, so we used the

25 AERMOD debug output. We wrote a little program to compile
179

KAY McGOVERN & ASSOCIATES (919) 870-1600

Suite 117, 314 West Millbrook Road FAX 870-1603

Raleigh, North Carolina 27609-4306 (800) 255-7886

1 different plume rise statistics and we grouped them by hour

2 of day. And you can see here these little symbols are

3 frequency bins. The plus and the diamond, those are the most

4 frequent occurrences, so generally speaking, over the course

5 of the day, plume rise in the main source at this project

6 site is between 200 and maybe 320 meters. So that's really

7 our level in the atmosphere where we need to really focus on.

8 Let's quickly look at a direct comparison of the

9 tower observations for 2005 versus WRF observations--the WRF

10 generated wind data in 2005. So on the left is the tower

11 windrose and on the right is the WRF windrose. Obviously

12 they're not the same windrose. You can see there's some

13 artifacts in the tower, particularly that northeast artifact. 

14 That's probably due to drainage flow of some kind. It's not

15 well realized at the 1.3 kilometer resolution of WRF. 

16 Perhaps if we went down to 444 meters, the next nesting

17 model, we could have started to draw that out, but we didn't

18 end up doing that.

19 Regardless, the average speeds here we felt were

20 pretty comparable. The tower has an average wind speed of

21 3.4 meters per second at this level and the WRF model is

22 generating an average wind speed of 3.7.

23 So our conclusions on the met representativeness

24 discussion where we used this WRF run to really supplement,

25 at the 240 meter level, WRF shows a consistent windrose
180

KAY McGOVERN & ASSOCIATES (919) 870-1600

Suite 117, 314 West Millbrook Road FAX 870-1603

Raleigh, North Carolina 27609-4306 (800) 255-7886

1 pattern across the study area. And we identified that 240

2 meter level as an important one in the application due to the

3 expected modeled plume heights that it showed in that

4 frequency by hour of day plot.

5 Also, we can comment that the wind pattern in the

6 immediate vicinity of the tower and the application site is

7 similar at 60 meters. As we saw in that previous slide, the

8 average wind speed is slightly less at the tower site. And

9 the tower observed wind speeds themselves are generally

10 biased slightly lower than WRF.

11 So our overall conclusion here was that there was

12 acceptable directional representativeness, slightly lower

13 tower wind speeds, and those wind speeds will be conservative

14 when they are extrapolated to plume height by AERMOD. So we

15 took five years, the five most recent years of tower data, at

16 a 10 meter and 60 meter multilevel tower. And the end result

17 was we had a successful air quality modeling analysis using

18 those data.

19 So switching gears again, with the advent of the

20 new proposal for Appendix W from July 30th or whenever it

21 was, we wanted to take a look at actually running MMIF as

22 proposed in Appendix W for this site. And I just want to

23 note some of the language included in the proposal,

24 specifically talking about cost prohibitiveness or

25 infeasibility being a trigger for when you can use the
181

KAY McGOVERN & ASSOCIATES (919) 870-1600

Suite 117, 314 West Millbrook Road FAX 870-1603

Raleigh, North Carolina 27609-4306 (800) 255-7886

1 prognostic data. Let's talk a little bit about that.

2 For the sake or argument, if we assume that that

3 nearby tower data wasn't available, could we have used MMIF

4 and WRF to generate the meteorological data for AERMOD? So

5 we know we had questionable representativeness of the distant

6 airport met data sets. And this particular application

7 likely could not have accepted a 16 month or so delay for a

8 meteorological monitoring program.

9 Now, on-site met monitoring for this site would

10 likely have included a tall tower at 60 meters, likely 100

11 meters, a SODAR, and then the time to acquire all that

12 instrumentation, time to construct it, time to compile the

13 monitoring protocol, a minimum of 12 months of actual met

14 data that needs to be collected, and of course that met data

15 has to meet all the completeness requirements. 

16 And there's a lot of time that has to go into a

17 met monitoring program beyond just that 12 months. Things

18 can happen over the course of the monitoring that can delay

19 things, and SODARs are particularly susceptible to vandalism. 

20 Just things like that can really ruin your day when you're

21 trying to collect a year's worth of met data.

22 So what we did was we executed MMIF 3.2 following

23 the EPA July 2015 guidance. What we're doing here is to take

24 a quick look, an initial impression. We're not doing a full

25 model evaluation. You know, we did this, you know, in the
182

KAY McGOVERN & ASSOCIATES (919) 870-1600

Suite 117, 314 West Millbrook Road FAX 870-1603

Raleigh, North Carolina 27609-4306 (800) 255-7886

1 weeks leading up to this conference.

2 And I just want to point out that the tower data

3 isn't site specific, but it is a high quality, multilevel

4 data set. It's not a National Weather Service site. So I

5 just want to point out that the data that we're looking to

6 compare to WRF is of higher resolution than we can find at a

7 National Weather Service site because there's more than one

8 level. And the instrumentation itself is, you know, of real

9 high quality.

10 So we used 2005 again because that's what we have

11 WRF data for. And we also have tower data all the way back

12 to 2005, so we have a nice year to year comparison here. The

13 model results that I'm about to show you are based on an

14 actual application that went through permitting, but these

15 results themselves are for a theoretical project at the same

16 site.

17 So here's a plot of the model design value for

18 NO2, and this is using WRF/MMIF data. It's very hard to see,

19 but the project site is in the southeast corner there. And

20 the high concentrations are occurring on a complex terrain

21 ridge just to the northwest. And that's really the extent of

22 most of our elevated concentrations. And this is, you know,

23 typical complex terrain, stable conditions causing the

24 elevated concentrations.

25 We're comparing this now to the tower data for the
183

KAY McGOVERN & ASSOCIATES (919) 870-1600

Suite 117, 314 West Millbrook Road FAX 870-1603

Raleigh, North Carolina 27609-4306 (800) 255-7886

1 same time period. And we can see that the maximum concen2 trations are occurring at that same piece of the ridge on the

3 right-hand side of the slide there. We can see a little bit

4 more than what's realized from the WRF data along the grid as

5 it goes off to the southwest. And the design values--I

6 forgot to note that the previous design value for MMIF was

7 89.5 and this design value is 91.75. So we're getting

8 extremely similar results.

9 Let's take a little bit closer look here. We have

10 source by source at the project site how do results compare

11 from the two data sets. And I have the high first high and

12 the high 8 high design values shown. 

13 So you can see that between high first high and

14 high 8 high for source 1, that's the main source. It's a

15 tall stack, you know, very high flow. All of its impacts are

16 very episodic in complex terrain. Once you get to the more

17 stable design value, there's a big step off there for the

18 design value in the high first high, not so for the ancillary

19 equipment. Those are much more stable and much more--

20 extremely comparable between the two data sets. 

21 But even for the main source between the two data

22 sets, we have good comparability, at least from this initial

23 exercise here, you know, 32 versus 35.8 micrograms per meter

24 cubed. So our initial observations seem to suggest that

25 there's reasonable comparability between the two data sets.
184

KAY McGOVERN & ASSOCIATES (919) 870-1600

Suite 117, 314 West Millbrook Road FAX 870-1603

Raleigh, North Carolina 27609-4306 (800) 255-7886

1 So our initial conclusions and some comments here,

2 we feel that utilizing WRF and MMIF as a source of meteoro3 logical data for AERMOD for this application shows similar

4 model results compared to representative multilevel

5 observation of meteorological data. 

6 If no observational meteorological data were

7 available, finding representative airport data would have

8 been challenging. And use of WRF/MMIF as suggested by the

9 new Appendix W could possibly have saved this project in that

10 case if that nearby tall tower wasn't available.

11 So we strongly support the proposal in Appendix W

12 to allow the option of using WRF or MM5 through MMIF to

13 generate meteorological data for regulatory applications. 

14 Mr. Bridgers: Thanks so much, Tom. As we

15 prepare to go to break, I know I cautioned earlier about not

16 approaching EPA folks to ask them a bunch of questions. But

17 all the speakers from this afternoon, anything that they

18 presented, feel free to talk with them about all that. Just

19 don't do it with EPA folks standing right there. We live

20 around y'all around here and we work around you. 

21 But seriously, the presentations will be posted--I

22 know Bart was a little rushed just because of the time limit,

23 but his presentation will be posted online and feel free to

24 follow up by contacting him directly and asking questions if

25 you have them.
185

KAY McGOVERN & ASSOCIATES (919) 870-1600

Suite 117, 314 West Millbrook Road FAX 870-1603

Raleigh, North Carolina 27609-4306 (800) 255-7886

1 We are just past--we'll stay on schedule with

2 respect to when we come back from break, so we'll break now

3 until 3:35. And then we'll round out the afternoon through

4 5:20, so about 20 minutes, guys.

5 (A recess was taken from 3:14 p.m. to 3:37 p.m.)

6 Mr. Bridgers: As we take our seats, we now

7 have three presentations that are going to be given in

8 succession by the AWMA, a subcommittee of that, and David can

9 introduce that when he gets up here. So we've allotted 15

10 minutes for three different topics. And I'm going to let the

11 three different topics kind of run semiautonomously, but like

12 I said, with these guys, I'm still going to try to keep them

13 to their 15 minute blocks. So over the next 45 minutes we'll

14 hear from AWMA. David?

15 Mr. Long: Good afternoon. My name is

16 David Long. I am an engineer with American Electric Power

17 and today I'm speaking to you as my role as chairman of the

18 Atmospheric Modeling and Meteorology Committee of AWMA.

19 The Atmospheric Modeling and Meteorology Committee

20 is the technical coordinating committee for air quality

21 modeling and meteorology issues within AWMA. We have roughly

22 100 active members on the committee and our objectives for

23 our committee are to provide technical support for the annual

24 meeting, support specialty conferences and workshops, which

25 I'll mention a little bit about later in my part of our
186

KAY McGOVERN & ASSOCIATES (919) 870-1600

Suite 117, 314 West Millbrook Road FAX 870-1603

Raleigh, North Carolina 27609-4306 (800) 255-7886

1 presentation, contribute to various technical programs

2 sponsored by AWMA, and provide comments and review on

3 regulatory and technical issues relating to modeling in a

4 constructive manner.

5 For working on the Appendix W revisions, we put

6 together an ad hoc review committee chaired by George Schewe

7 of Trinity. And the committee consisted of myself, Justin

8 Walters of Southern Company, who's our vice chair; Michael

9 Hammer of Lakes Environmental, who's our secretary; Pete

10 Catizone from TRC; Bob Paine from AECOM; Gale Hoffnagle from

11 TRC; Ron Petersen from CPP Wind; Ralph Morris from Ramboll

12 Environmental; Mark Garrison from ERM; Tony Schroeder from

13 Trinity; and Abhishek Bhat from Trinity. And then as part of

14 our process, we solicited comments from all the various--all

15 the committee members and tried to work those into our

16 comments as best we could. 

17 Our topic areas we're going to be discussing are

18 general comments, which will be the area I'll be speaking on,

19 AERMOD, the enhancements, new algorithms, and applications,

20 which will be spoken about by Mark Garrison, and finally,

21 single source modeling for ozone and PM2.5 and long range

22 transport modeling, which Gale Hoffnagle will speak to.

23 Looking at general issues, EPA has produced a lot

24 of useful information to address many challenging tasks in

25 air quality modeling. However, looking at the current record
187

KAY McGOVERN & ASSOCIATES (919) 870-1600

Suite 117, 314 West Millbrook Road FAX 870-1603

Raleigh, North Carolina 27609-4306 (800) 255-7886

1 as it exists today, we see some of the guidance documents

2 that have been placed in the docket do not yet appear to be

3 complete or appear to still be works in progress, and we're

4 not sure they completely support the final rulemaking.

5 Now, where we see potential incomplete modeling

6 procedures are for ozone and PM2.5 guidance, the Tier 1

7 emission rate guidance--and we view that as an essential

8 piece of the Tier 1 process and it doesn't appear to be

9 available based on what our members have been able to locate

10 to this point. Some of the long-range modeling procedures

11 don't appear to be well defined, and some of the promulgation

12 of these issues could occur with future rulemaking once the

13 more complete procedures are defined. We feel that would

14 make a better record.

15 We also--we do think that some of the incompletely

16 defined approaches can cause problems working on permit

17 modeling. You know, one of the things that was mentioned

18 earlier today is, you know, protocols are going to be much

19 more important. And one of the problems that we've had that

20 our members have had over the last number of years is

21 protocols can take a very, very long time to be approved. 

22 And with some of what we see as potentially open issues in

23 the Guideline and more Model Clearinghouse review, the

24 timing--we don't feel the timing will get better. We're very

25 concerned the timing will be worse as time goes by.
188

KAY McGOVERN & ASSOCIATES (919) 870-1600

Suite 117, 314 West Millbrook Road FAX 870-1603

Raleigh, North Carolina 27609-4306 (800) 255-7886

1 Regulatory review for protocols we feel should be

2 able to be done in a fairly limited time, but you get into a

3 number of agencies that sometimes don't see eye on how

4 something should be done and, you know, it causes some

5 problems. So we would encourage EPA to try and help move the

6 process along.

7 Obviously with these problems we see that that

8 increases the expense for entities that are trying to get

9 through permit modeling. It's going to take more effort to

10 prepare the protocol and then to work it through the review

11 process with things not maybe as well defined as they could

12 be. 

13 You know, this increases greater--increases costs

14 and uncertainty, especially in the areas of ozone and PM2.5. 

15 And it potentially leads to a greater effort to defend a

16 permit that would ultimately be issued because the procedures

17 may not have been as well defined in Appendix W.

18 You know, consistency, one of the things that,

19 again, we've heard mentioned earlier today. You know, we see

20 some of the proposed changes as potentially causing less

21 consistency amongst modeling activities and--because it seems

22 like things may be going more to a case by case situation

23 instead of a more uniform modeling approach throughout the

24 country. Now, the consistency issue is something that we've

25 seen as an effort of past guidelines. And again, lack of
189

KAY McGOVERN & ASSOCIATES (919) 870-1600

Suite 117, 314 West Millbrook Road FAX 870-1603

Raleigh, North Carolina 27609-4306 (800) 255-7886

1 consistency can lead to challenges to permit and more

2 litigation. 

3 Potentially, it could drive companies to try and

4 avoid PSD type modeling, which increases the time and expense

5 for a permit. And it's also potentially going to take a long

6 process, getting a PSD or NSR permit, and make it an even

7 longer process, which may not necessarily be the best

8 utilization of agency or regulated community time.

9 You know, we would also recommend to EPA in their

10 changes to Appendix W that they not take positions that cause

11 special approvals to be restricted to single sources and then

12 not make them reachable for any other purpose. 

13 And we also--as we've looked at the guideline

14 proposal to this point, it appears that special approvals

15 will be much more extensively needed for everything but a

16 basic demonstration. And we would encourage EPA to retain

17 the current system where the permitting authority has more

18 discretion to approve a modeling protocol in most cases.

19 Obviously there are going to be cases where things are going

20 to be done that are not standard within the protocol and

21 special handling is required for those, and that's been the

22 case all along.

23 We'd also suggest that EPA consider forming an

24 independent expert model science advisory panel to advise EPA

25 in planning and review of model component changes and
190

KAY McGOVERN & ASSOCIATES (919) 870-1600

Suite 117, 314 West Millbrook Road FAX 870-1603

Raleigh, North Carolina 27609-4306 (800) 255-7886

1 guidance on how models are applied. The focus of this group

2 would be on model evaluation changes that are scientifically

3 justified rather than on just simple sensitivity studies. 

4 And EPA should demonstrate that model formulation and

5 guidance changes will indeed result in improved model

6 performance.

7 We also would suggest that EPA move to a tiered

8 approach for model changes and updates to allow new and

9 improved modeling formulations to move into use in a more

10 expeditious and better reviewed fashion. 

11 Now, the first tier would be changes to models in

12 Appendix W, which would be major changes, and this would

13 require a formal public comment process with Federal Register

14 notice and a public hearing, would include a 90 day comment

15 period, and we'd recommend allowing a one year period for

16 testing and debugging of new modeling procedures with

17 additional comments limited to just the testing and debugging

18 and not the whole model formulation itself.

19 Final implementation would then occur after the

20 one year period is up, including a review of the 90 day

21 comment period information and the results of the testing and

22 debugging activities. And potentially the new techniques

23 could be allowed to be used immediately, but subject to

24 change due to the testing and debugging and public comment.

25 Tier 2 would be formulation updates to Appendix W
191

KAY McGOVERN & ASSOCIATES (919) 870-1600

Suite 117, 314 West Millbrook Road FAX 870-1603

Raleigh, North Carolina 27609-4306 (800) 255-7886

1 models. And this would be things such as the low wind speed

2 options, changes to downwashes affecting stacks at or above

3 GEP height, and some of the options that have been set up for

4 CALPUFF but have not always been approved in a timely

5 fashion.

6 Now, these are more substantial than simple bug

7 fixes and should be reviewed by the public. But a Tier 2

8 change would not require a Federal Register notice or a

9 public hearing. There would be a 90 day comment period, but

10 it wouldn't require the reopening of Appendix W and allowing,

11 again, a one year period for testing and debugging with

12 additional comments outside of the 90 day period limited to

13 just testing and debugging information.

14 Then final implementation would be after that one

15 year period with review of all comments and the testing and

16 debugging activities. Again, we'd suggest some of these

17 techniques would be available for use immediately, but again,

18 subject to change based on the results of the testing and

19 debugging and public comment.

20 The final tier is simple bug fixes or procedural

21 clarifications. And again, we would suggest a comment period

22 on this of 90 days, but no testing being required and the new

23 techniques would be available for use immediately, but

24 subject to change.

25 Now, EPA, we also feel, should allow for review of
192

KAY McGOVERN & ASSOCIATES (919) 870-1600

Suite 117, 314 West Millbrook Road FAX 870-1603

Raleigh, North Carolina 27609-4306 (800) 255-7886

1 alternate modeling approaches through the Clearinghouse

2 without tying such requests to permit applications. This

3 could be a case where an entity sees an issue with the model

4 and wants to bring it to EPA's attention, but it isn't going

5 to--it isn't happening in the context of a permitting

6 process. And we also would encourage collaborative field

7 experiments with EPA input.

8 As I mentioned earlier, we do--our committee is

9 responsible for specialty conferences, and we are planning

10 one for 2016. It's going to be our sixth specialty

11 conference on air quality modeling. It's scheduled for

12 April 12th through 14th at the Sheraton Chapel Hill in Chapel

13 Hill, North Carolina. The call for papers is open and more

14 information on this conference is available at aqmodels.awma.

15 org. And now I would like to invite Mark Garrison up to

16 start our talk on AERMOD.

17 Mr. Garrison: I've got 15 minutes? Thank

18 you, David. Thank you, George. I appreciate the opportunity

19 to provide some comments at this conference. I'd also like

20 to thank Bob Paine, Ron Petersen and Pete Catizone for

21 providing a lot of the technical content of this

22 presentation. I think I was nominated to give this

23 presentation so that the impression wouldn't come across that

24 this is a Bob Paine conference, but nonetheless.

25 We do provide a number of feedback and questions
193

KAY McGOVERN & ASSOCIATES (919) 870-1600

Suite 117, 314 West Millbrook Road FAX 870-1603

Raleigh, North Carolina 27609-4306 (800) 255-7886

1 regarding the new algorithms and enhancements. We did

2 provide some recommendations for possible future enhancements

3 to AERMOD for EPA's consideration. We also provide observa4 tions, comments, recommendations on various aspects of the

5 application of the AERMOD system in Appendix W.

6 There are a lot of questions in our presentation. 

7 I think I'm going to have to go through it fairly quickly to

8 get through the time allotted. Listening to the presenta9 tions this morning and this afternoon, however, I think a lot

10 of the questions and issues that we raise have been addressed

11 and in some cases answered by others. I'm going to try to

12 sort of point this out as I go through with--as I go through

13 this. And the committee is planning on providing additional

14 comments in the comment period, either additional things that

15 we think of or amplifications to the comments that we're

16 making today.

17 Well, 15181 incorporates, as we have heard and as

18 we know, some new algorithms including PVMRM2, LowWind3,

19 Teriminator4--sorry, Terminator4 is not in AERMOD--and of

20 course, buoyant line source type that has been added to the

21 modeling. 15181 also contains some other options, beta

22 options that have been in the model since 12345. Our

23 comments are addressed to those too.

24 I think it's fair to say that for all the

25 committee members that these are very welcome and appropriate
194

KAY McGOVERN & ASSOCIATES (919) 870-1600

Suite 117, 314 West Millbrook Road FAX 870-1603

Raleigh, North Carolina 27609-4306 (800) 255-7886

1 enhancements to AERMOD, and the committee does very much

2 appreciate EPA's hard work in their ongoing efforts to

3 consider and incorporate changes that improve the AERMOD

4 system. And I think that reminds me, did I introduce myself? 

5 Mark Garrison, ERM. Thank you. 

6 The first topic is NO2 modeling options, on which

7 we've heard a couple of presentations already. And I think

8 obviously ARM2 is a more realistic approach to modeling that

9 conversion than the existing Tier 1 and Tier 2 options,

10 although there might be some issues with going to ARM2

11 directly from Tier--the existing ARM, especially since the

12 minimum ratio recommended is 0.5. 

13 The committee feels that it's likely to be much

14 too conservative for many applications, and the language on

15 alternatives--this is actually a misrepresentation. That is

16 actually at 4.2.3.4(d) in the proposed Appendix W. It is

17 very long. And improvements to PVMRM, as we've heard

18 previously PVMRM2 addresses some of those limitations and

19 issues with the previous PVMRM.

20 ARM2 is now indicated as a beta option. We've

21 learned the process of, you know, removing it from the beta

22 option has to wait for close of the comment period and EPA's

23 response. So we simply want to encourage elevation to

24 default status as quickly as possible.

25 These two comments basically ask for a little bit
195

KAY McGOVERN & ASSOCIATES (919) 870-1600

Suite 117, 314 West Millbrook Road FAX 870-1603

Raleigh, North Carolina 27609-4306 (800) 255-7886

1 more guidance in terms of how to model increment consumption,

2 net air quality benefit analyses involving NO2. The bottom

3 part of this graph simply--it's very hard to read, but the

4 horizontal axis is ozone concentration. The vertical access

5 is time to complete conversion. And the point is, I think,

6 that for some situations with very near, very close impacts,

7 that can be an important consideration. And the suggestion

8 is that some consideration of the time of conversion be

9 incorporated into the AERMOD.

10 We heard about LowWind3, and I think this issue

11 hasn't been answered very much, what LowWind3 is compared to

12 the other low wind options. And again, we kind of encourage

13 the low wind options to become regulatory default options.

14 The buoyant line source algorithm is a welcome and

15 encouraging addition to AERMOD. It allows for modeling of

16 buoyant line sources along with more traditional sources. 

17 And we think that the current version should be treated as a

18 beta version due to the limited user input and limited user

19 experience until such time as we kind of gain some experience

20 and can provide some feedback on that.

21 This suggestion is to include test runs in the

22 BUOYLINE source algorithm to be distributed with the AERMOD

23 system. And I think this question, it kind of is answered by

24 the understanding that incorporation of BLP into AERMOD is

25 intended not to create a new model, but to simply take what
196

KAY McGOVERN & ASSOCIATES (919) 870-1600

Suite 117, 314 West Millbrook Road FAX 870-1603

Raleigh, North Carolina 27609-4306 (800) 255-7886

1 would be predicted by BLP and put it into AERMOD. 

2 It produces some sort of strange, you know, a need

3 in other words, within AERMOD to determine a Pasquill-Gifford

4 stability category and some other issues like that where the

5 algorithms between the two models are different. But I think

6 that this is one area that need--certainly needs some more

7 review and study.

8 And this is really sort of the same issue. I mean

9 the intention as I understand it and as the committee

10 understands it is to include what would be predicted by BLP

11 in AERMOD so that you don't have to run two models and kind

12 of mesh the two results in a close processing step.

13 In terms of mobile sources, I think we did hear

14 that the intention is to replace CAL3QHC in its refined

15 version with AERMOD. The issues listed here included, you

16 know, what to do about queuing algorithms and a couple of

17 other issues--a couple of other treatments within the mobile

18 source models. It's not clear how AERMOD will handle those,

19 but I think they will hopefully become clearer as we learn

20 more about 15181.

21 Just a quick note on secondary PM2.5 application. 

22 The committee feels that possibly a reduced form model for

23 secondary PM2.5 could be adapted for AERMOD as opposed to

24 adding a constant value at all receptors. It can either be

25 done through a postprocessor using a look-up table or other
197

KAY McGOVERN & ASSOCIATES (919) 870-1600

Suite 117, 314 West Millbrook Road FAX 870-1603

Raleigh, North Carolina 27609-4306 (800) 255-7886

1 means of calculating a transformation rate, or probably even

2 more straightforward, could or should be incorporated into

3 AERMOD directly.

4 Several slides on background concentrations--I

5 won't dwell on these too much. I think there have been some

6 helpful discussions already today. The first point here,

7 that focus should be on actual emissions, not allowable. And

8 the new Table 8.1 or 8.2--I don't remember which one it

9 is--is certainly a welcome change to how nearby sources are

10 modeled.

11 And I think--again, I'm not going to go through

12 each of these in detail, but the overriding point is that

13 background concentrations should be--should not have

14 influences from nearby industrial sources that are not going

15 to interact with the source in question. It's a very

16 difficult thing to accomplish, but we think that it's

17 important to achieve that goal. I'm sort of reading through

18 here to see---

19 (Pause.)

20 Again, I think--I won't go through these in

21 detail, but one thing to consider I think to the last point

22 is that the use of lower percentiles, perhaps the 50th

23 percentile, should be used as a reasonable and viable option

24 to account for a true background in refined modeling.

25 In the area of building downwash, I think the
198

KAY McGOVERN & ASSOCIATES (919) 870-1600

Suite 117, 314 West Millbrook Road FAX 870-1603

Raleigh, North Carolina 27609-4306 (800) 255-7886

1 committee feels that there is still some sort of long2 standing questions about performance for certain situations,

3 including long and narrow buildings, low wind speeds, which

4 we've heard a couple of presentations about already. 

5 The issue that's been on for a while, the downwash

6 for stacks at or above GEP, is an issue that probably needs

7 some further review and discussion, and I think the committee

8 would plan to amplify on that comment in its comments. And

9 of course the last bullet, we do encourage EPA to seek

10 feedback from external stakeholders.

11 There were a number of theoretical issues that

12 were raised in the comments. And I won't go through these,

13 but I think these theoretical issues in part are addressed by

14 considerations about the heat island effect in certain

15 buildings and the issue with long narrow buildings that the

16 committee is going to provide additional comments during the

17 comment period.

18 Equivalent building dimension approach has been

19 around for a while as well, and I think the committee feels

20 that it is still a viable alternative for complex building

21 cases, including porous structures, streamlined structures,

22 et cetera. And that should be considered--or guidance for,

23 you know, preparing that kind of an analysis and EBD should

24 be addressed.

25 We have heard--these last two bullets, we're heard
199

KAY McGOVERN & ASSOCIATES (919) 870-1600

Suite 117, 314 West Millbrook Road FAX 870-1603

Raleigh, North Carolina 27609-4306 (800) 255-7886

1 presentations about, you know, low wind speed downwash and

2 situations where excess heat in a building or an industrial

3 area can cause plume liftoff, so I won't go over those.

4 And finally, our last topic is in terms of using

5 prognostic meteorological data in AERMOD, which we've already

6 heard a couple of presentations about. And I think, you

7 know, all of us feel it's an encouraging and very welcome

8 option for cases where airport representativeness is

9 uncertain. 

10 And the point is that the use of MMIF should be

11 encouraged and should eventually become a default option. I

12 understand that some guidance is currently being developed,

13 but I think the committee feels that it's a great alternative

14 and should be pursued.

15 Additional testing and comparison I think may

16 reveal some areas where, you know, the use should be

17 cautioned, and I think that's one area that we feel needs

18 some attention, not just sort of widely apply it, but

19 understand the limitations.

20 And I think the--just simply the option to work

21 with the appropriate reviewing authority or agency and

22 development of a protocol as to how to do this is absolutely

23 welcome for situations where measurements are not--in situ

24 measurements, the on-site measurements, are impractical or

25 cost prohibitive.
200

KAY McGOVERN & ASSOCIATES (919) 870-1600

Suite 117, 314 West Millbrook Road FAX 870-1603

Raleigh, North Carolina 27609-4306 (800) 255-7886

1 This is a specific reference to MMIF and I think

2 kind of in keeping with not referring to specific models and

3 model versions and the references in the AERMOD users guide.

4 The issue of land use in WRF versus land use

5 eventually in AERMET is an issue that needs some attention

6 and study as well. WRF cells, as we heard earlier, can go as

7 low as 400 meters or so, but that is still--there is still

8 some question as to whether that 400 meter land use is

9 representative enough for a particular application. So I

10 think the idea is that, you know, maybe have WRF through MMIF

11 provide wind and temperature profiles, but then use AERMET to

12 specify land use in a more detailed, site specific area.

13 We do have I think a few more slides on prognostic

14 met data. I think the first question obviously has been

15 asked and answered, and another comment on a citation in

16 8.4.2 that might need to be reviewed and possibly changed.

17 We did hear--I guess Bart was saying that his

18 AERCOARE option was grayed out and it was not addressed

19 currently, but I think that is something that needs to be

20 considered, that the AERCOARE algorithms and approach might

21 be appropriate for including in AERMOD for over water

22 applications. The AERCOARE has been approved for and

23 implementation of an AERCOARE type approach would be similar

24 to a BLP inclusion.

25 Okay, summary. I think--again, I think the
201

KAY McGOVERN & ASSOCIATES (919) 870-1600

Suite 117, 314 West Millbrook Road FAX 870-1603

Raleigh, North Carolina 27609-4306 (800) 255-7886

1 proposals are encouraging and reflect considerable hard work

2 by EPA and are welcome changes, welcome updates to the

3 Guideline on Air Quality Models. We anxiously await the

4 elevation to default status of several important updates.

5 BLP is a welcome addition, much work to be done. 

6 Mobile sources, some clarification is needed on the status of

7 AERMOD with respect to CAL3QHC and particularly how certain

8 algorithms within those models are handled in AERMOD. 

9 Background, current procedures are still very conservative.

10 Downwash, work is needed on long buildings, low wind speeds. 

11 MMIF, the use should be encouraged. Maybe there should be a

12 clearinghouse for WRF data sets in the IM, and we're done.

13 The next speaker is Gale Hoffnagle. I'll let you

14 introduce yourself, Gale.

15 Mr. Hoffnagle: Gale Hoffnagle from TRC. I'm

16 going to talk about single source modeling for ozone and PM10

17 (sic) and long range transport modeling, and my overall theme

18 is case by case is not guidance.

19 This modeling issue is very challenging. The

20 ozone and PM2.5 is very challenging. We recognize that has

21 EPA spent a good deal of hard work to date on the proposal

22 package. The proposed approach, while having merit and being

23 a good start, is preliminary and needs more development

24 before becoming part of this rulemaking. It's not ready for

25 prime time.
202

KAY McGOVERN & ASSOCIATES (919) 870-1600

Suite 117, 314 West Millbrook Road FAX 870-1603

Raleigh, North Carolina 27609-4306 (800) 255-7886

1 Currently there are no clear modeling approaches,

2 which is a significant departure from the very specific

3 default options specified by EPA for AERMOD and CALPUFF

4 modeling in prior guidance. Has EPA considered--this as one

5 of the overview items. Has EPA considered the interaction of

6 secondary formation and Class I increments? That's a big

7 question that's unaddressed.

8 So we have a three tiered approach, a qualitative

9 waiver of modeling requirement if new emissions are less than

10 model emission rates for precursors or MERP, which is not

11 available. I don't know how to evaluate the three tiered

12 process without MERPs being available. And I don't know

13 whether it's going to be a separate promulgation or not.

14 The next tier is a screening approach based upon

15 relationships between emissions and impacts, which may have a

16 reduced form model or a screening model. This tier is to be

17 appropriate for most permit applicants. How does EPA know

18 that before it's done? I don't know that.

19 The final tier is use of more sophisticated case

20 by case sophisticated photochemical modeling analysis and 

21 necessary only in special situations. I don't know how we

22 know that before the three tiered approach is finished.

23 MERPs need to be specified through a proposal and

24 public comment. I guess that's a future rulemaking. This

25 will help the user community to understand what this tier
203

KAY McGOVERN & ASSOCIATES (919) 870-1600

Suite 117, 314 West Millbrook Road FAX 870-1603

Raleigh, North Carolina 27609-4306 (800) 255-7886

1 covers.

2 The IWAQM3 near-field document states, "At this

3 time, it is not clear that a robust reduced form model exists

4 for either ozone or secondary PM2.5 for the purposes of

5 assessing single source downwind impacts of these

6 pollutants." Well, if there isn't such a model, how are we

7 going to get a workhorse model for the second tier? I don't

8 know. I don't know. We don't know how that is and we don't

9 how to evaluate it.

10 More specifics are needed on the application of

11 Eulerian photochemical grid models or advanced Lagrangian

12 models in future rulemaking. We need a second--"Single

13 source secondary impacts are...usually highest in proximity

14 to the source." I don't know that. Is that true? That's an

15 issue. It's been an issue. Are they long range transport? 

16 Are we making more stuff long downwind or are we making more

17 stuff right there next to the source. I'm sure it changes

18 depending upon the situation.

19 But anyway, we don't have much data within 10

20 kilometers of a source, and we run into problems with the

21 grid size in photochemical grid models when we get down to

22 those kind of distances. We've seen the problems at MMIF at

23 4 kilometers and 11⁄2--or 400 meters and 11⁄2 kilometers. A

24 focus on near-field evaluations would be helpful. We need

25 more data.
204

KAY McGOVERN & ASSOCIATES (919) 870-1600

Suite 117, 314 West Millbrook Road FAX 870-1603

Raleigh, North Carolina 27609-4306 (800) 255-7886

1 So if peak impacts occur near the source, careful

2 attention needs to be paid to modeling near the source, and

3 plume-in-grid treatment would come up for debate again. 

4 Plume rise and source related effects are therefore very

5 important. Where is the plume in elevation? Where is the

6 chemistry in elevation? How does that chemistry in elevation

7 affect ground level concentrations? Those are all issues

8 that have to be discussed. Lagrangian models avoid this

9 problem, so such models should be seriously considered for

10 ozone and second PM2.5 modeling, especially in the workhorse

11 category, if you will.

12 Relative versus absolute predictions: EPA

13 recommends that absolute photochemical grid modeling

14 predictions should be compared to the SILs. We don't have a

15 SIL, but when we have a SIL for ozone I guess we'll do that,

16 which brings up the whole question of SILs. If the PM2.5 SIL

17 is under remand, when and how are we going to have an ozone

18 SIL? 

19 What is the ozone SIL? Is it 1 ppb? Does the

20 ozone SIL change as the ozone standard changes on the 1st of

21 October because that's when we know it will change. So

22 there's a whole bunch of issues there that make it difficult

23 for us to evaluate where this is all going.

24 In many PGM applications, a relative reduction

25 factor is applied to minimize model uncertainty. That
205

KAY McGOVERN & ASSOCIATES (919) 870-1600

Suite 117, 314 West Millbrook Road FAX 870-1603

Raleigh, North Carolina 27609-4306 (800) 255-7886

1 happens in the SIP program. But in the guideline program,

2 we're not allowed to make calibrations, right, so there's a

3 big difference in the way that these models have been run for

4 SIPs and run for the Guideline in using them for the

5 Guideline. I think there is a pretty good reason to suspect

6 that we ought to do some calibration of PGM models if we're

7 doing regulatory analysis under the Guideline. But this is

8 sort of a, you know, absolute issue.

9 Who will determine how to run the advanced models? 

10 The widespread use of the top modeling tier may be because

11 the scope of the tiers is not yet clearly defined. We think

12 that's a problem. Model users need more specification of

13 which top tier model and which technical options should be

14 used. That is, where's the guidance? We don't have any

15 guidance.

16 What group of experts is available to determine

17 how to run the designated model, because we always get

18 involved in the question of which switches to use? Will

19 regional modeling platforms including existing source

20 databases be set up and designated for use? If so, we will

21 need to plan that carefully. 

22 I can't imagine that each model, each permit

23 applicant is free to go out and create a new smoke input for

24 their PGM model. That's ridiculous. That can't happen. It

25 will make modeling for a permit a $200,000, $300,000 job, not
206

KAY McGOVERN & ASSOCIATES (919) 870-1600

Suite 117, 314 West Millbrook Road FAX 870-1603

Raleigh, North Carolina 27609-4306 (800) 255-7886

1 good.

2 Independent peer review program: the promulgation

3 of previous major Guideline model changes were preceded by an

4 independent peer review. These important modeling develop5 ment changes warrant the same level of peer review, which

6 would be subject to public review and comment. This process

7 can be conducted in association with future rulemaking, but

8 we need--I believe that EPA needs some outside guidance on

9 how these models perform, et cetera. And AWMA is offering

10 that that's what should happen.

11 Additional evaluation databases should also be in

12 the review. Come on, guys, we need more data. Now the

13 models are being asked to do things that we've never asked

14 them to do before and we need more data. I applaud API for

15 bringing some new data, EPRI bringing new data, but we need

16 more data. And I think EPA needs to sponsor data evaluations

17 again. So as I said, this three tiered approach is not

18 ready.

19 Long range transport models, CALPUFF and others--I

20 don't understand why EPA believes that there isn't the need

21 for long range transport modeling that there was before, but

22 I can tell you that we have had a recession, if you don't

23 understand. And people are not building new plants. And if

24 there's less permits being put in over the last six or seven

25 years, that's the reason.
207

KAY McGOVERN & ASSOCIATES (919) 870-1600

Suite 117, 314 West Millbrook Road FAX 870-1603

Raleigh, North Carolina 27609-4306 (800) 255-7886

1 When we get back to putting in permits for new

2 plants as the economy gets better, these are all within 300

3 kilometers of Class I area and we're going to need to do a

4 lot more of those analyses, or at least we hope we're going

5 to get to do a lot more of those analyses.

6 CALPUFF was recommended by IWAQM in 1998, used for

7 long range transport modeling, adopted in 2003. EPA proposes

8 not to have a long range transport guideline model. The

9 reasons for this appear to be more focused on CALPUFF manage10 ment than CALPUFF performance. However, we are hopeful that

11 the management of CALPUFF can be worked out with EPA.

12 CALPUFF is used widely throughout the world. We

13 have limited chemistry in the approved version because EPA

14 hasn't seen fit to evaluate any improvements in CALPUFF. So

15 version 6.42 has improved aerosol thermodynamics and aqueous

16 phase chemistry, which should be considered by EPA. It has

17 not been considered at all.

18 States and the user community have familiar with

19 CALPUFF, and its use could be retained at least as an

20 advanced screening model. Use of CALPUFF in this capacity

21 will also formally support the recommendations of FLAG 2010

22 and use of BART, which I think we've covered before, that

23 those are going to happen.

24 Running CALPUFF is much easier than running PGM

25 for single sources, saving applicants and states time and
208

KAY McGOVERN & ASSOCIATES (919) 870-1600

Suite 117, 314 West Millbrook Road FAX 870-1603

Raleigh, North Carolina 27609-4306 (800) 255-7886

1 money. We need an advanced screening model for stringent

2 Class I SILs and recommend that EPA retain the use of CALPUFF

3 for that purpose. Failing that, if the nearest Class I area

4 is well beyond 50 kilometers, but less than 300, we have a

5 question: have you considered whether AERMOD could be run

6 beyond 50 kilometers as a screening tool?

7 Next, could the FLAG 2010 Q/d less than 10 waiver

8 for modeling of AQRVs also be applied to PSD increment for

9 each pollutant? There's another screen that you could use

10 that would help us reduce the time and effort and energy.

11 And in conclusion, AWMA would welcome the oppor12 tunity to work with EPA on resolving any of the issues

13 addressed. Details and discussion of our comments will be

14 submitted to the docket to supplement our presentations here. 

15 And AWMA appreciates the opportunity and EPA's effort to

16 accommodate our request to present these comments. Thank you

17 very much.

18 Mr. Bridgers: And our appreciation to both

19 David--well, all three, David, Mark, and Gale--for their

20 comments, and we're staying on schedule.

21 So we will switch from AWMA comments--I believe

22 I've got the right presentation. Is that it? And next up,

23 Chris, I'll let you identify yourself.

24 Mr. DesAutels: Thank you. Good afternoon. My

25 name is Chris DesAutels. I work with Exponent. I'm here to
209

KAY McGOVERN & ASSOCIATES (919) 870-1600

Suite 117, 314 West Millbrook Road FAX 870-1603

Raleigh, North Carolina 27609-4306 (800) 255-7886

1 offer comments on behalf of Exponent. We are the developers

2 and the maintainers of the CALPUFF model. Listed here are

3 some other members of the Exponent team who have been

4 involved in developing and maintaining the CALPUFF model.

5 The primary purpose of this presentation is to

6 address some concerns that have been raised about CALPUFF as

7 part of the rulemaking process. Specifically up to this

8 point, CALPUFF has been part of the guideline models and it

9 has been an integral part of the modeling process. "CALPUFF

10 dispersion," as stated here, "had performed well and in a

11 reasonable manner with no apparent bias towards under or

12 overprediction, so long as the transport distance was limited

13 to less than 300 kilometers."

14 There have been several documents that are

15 included as part of the proposed regulatory docket that have

16 raised concerns about the CALPUFF modeling system. And I

17 just want to address some of these and at least open the

18 conversation about possible resolution of these matters so

19 that CALPUFF can remain as part of the available models that

20 can be used and be part of the suite of models that will

21 allow us to implement the best science because there are

22 going to be needs for non-steady state modeling. There's

23 going to be needs for long range transport modeling, complex

24 terrain. And CALPUFF is well positioned to achieve these

25 goals so long as some of these issues can be resolved with
210

KAY McGOVERN & ASSOCIATES (919) 870-1600

Suite 117, 314 West Millbrook Road FAX 870-1603

Raleigh, North Carolina 27609-4306 (800) 255-7886

1 all the stakeholders involved and there can be the confidence

2 developed to move it forward.

3 So there are three specific documents that are

4 part of the docket that I want to address or at least discuss

5 today: the preamble to the proposed rulemaking had some

6 specific statements and concerns raised; the supplemental

7 information for the IWAQM Phase 2 recommendations; and then

8 there was a memo on CALPUFF's ownership since 2003

9 promulgation.

10 Initially with the preamble to the proposed

11 rulemaking notice there was expressed concerns about the

12 management and maintenance of the model code given the

13 frequent change of ownership of the model code, and it also

14 refers to uncertainties in the development process of the

15 model. 

16 Initially here I'd like to address the issues of

17 the ownership. There is some uncertainty as to why this is a

18 significant concern despite--there have been two changes of

19 ownership of the CALPUFF model, but the personnel maintaining

20 the model have continued. There's been a continuous

21 representation of the same personnel maintaining the model. 

22 So there has been continuity.

23 The model has been freely available at the same

24 web site, so there's no mystery as to what the official model

25 is or where you reach it. And the model developers have
211

KAY McGOVERN & ASSOCIATES (919) 870-1600

Suite 117, 314 West Millbrook Road FAX 870-1603

Raleigh, North Carolina 27609-4306 (800) 255-7886

1 provided EPA with a copy of the CALPUFF updates and main2 tained both an EPA regulatory version which incorporates

3 primarily bug fixes, and a separate version which

4 incorporates model enhancements. CALPUFF does meet all the

5 requirements list in section 3.1.b of the Guideline for an

6 EPA approved model.

7 So the question is how do ownership changes fit

8 into the structure of a guideline model or any model for use

9 in regulatory purposes? This is not to say that any change

10 of ownership is problematic. It's just to point out that it

11 is fairly common. It happens in the industry with modeling,

12 and there's a lot of update to all models. So how are we

13 going to proceed forward if change of ownership is a signifi14 cant concern for any of the models that are addressed here

15 and are part of the future modeling suites that are going to

16 be used?

17 The second section of the preamble that discussed

18 CALPUFF was the change in the language for complex winds. It

19 has been removed--it has removed the use of CALPUFF

20 specifically. There is no specific technical basis really

21 provided for this change. It refers to technical issues, but

22 there's no specific citation of what the technical issue

23 that's being referenced at this point is.

24 And the current guidelines state that "The purpose

25 of choosing a modeling system like CALPUFF is to fully treat
212

KAY McGOVERN & ASSOCIATES (919) 870-1600

Suite 117, 314 West Millbrook Road FAX 870-1603

Raleigh, North Carolina 27609-4306 (800) 255-7886

1 the time and space variations of meteorology effects on

2 transport and dispersion." This is a necessary process

3 that's going to continue to occur and it's continually going

4 to need to be addressed. 

5 There will be need to be a model to address this,

6 so we believe that CALPUFF is still well situated to provide

7 this service, to do this type of modeling. And we don't see

8 the reason for there to be a change in the status for that

9 specific purpose.

10 The second document that I referenced here is the

11 supplemental information for IWAQM's Phase 2 recommendations. 

12 EPA observes that CALPUFF--it has a series of specific

13 concerns about the technical nature of CALPUFF, some of these

14 which were mentioned earlier today.

15 EPA observed that CALPUFF does not include photo16 chemistry for modeling of SO2, NO2, sulfates, or nitrates. 

17 CALPUFF has however up to this point been extensively used in

18 regulatory applications for Class I AQRVs, for modeling

19 deposition of sulfur and nitrogen and for visibility. 

20 And we believe that it can be enhanced, that there

21 can be improvements to the science and the model of CALPUFF

22 that will allow the Lagrangian type model to interact with

23 grid models to ingest ambient fields of oxidants and ammonia

24 and achieve more accurate results and achieve some of the

25 goals in a reasonable fashion that could be productive and
213

KAY McGOVERN & ASSOCIATES (919) 870-1600

Suite 117, 314 West Millbrook Road FAX 870-1603

Raleigh, North Carolina 27609-4306 (800) 255-7886

1 useful going forward. 

2 And we have interest in seeing that happen and

3 working to achieve that goal with EPA and any other

4 stakeholders that are interested in that possibility. It

5 will offer another opportunity for how to accurately predict

6 secondary PM2.5 and will advance the science of modeling.

7 EPA states also in that document that CALPUFF

8 cannot model single source impacts on ozone. And in general,

9 we agree that probably a full chemical grid model is more

10 appropriate for those purposes. That's a new area, and a

11 Lagrangian model is probably not the best served--best suited

12 for that purpose.

13 The final observation, which is mentioned a few

14 other places also, is that CALPUFF predictions are very

15 sensitive to the CALMET meteorological processor. And

16 different switch settings, different CALMET fields will

17 produce different dispersion results.

18 There are alternatives available. We've heard

19 some presentations today about using weather forecast models

20 and MMIF in order to drive CALMET--I mean in order to drive

21 CALPUFF or other dispersion models. That is a very

22 productive and possibly a development that its time has come. 

23 In the past when CALMET was originally developed,

24 those models were not ready for providing that resolution of

25 data. MM5 runs at that time were typically 80 kilometer
214

KAY McGOVERN & ASSOCIATES (919) 870-1600

Suite 117, 314 West Millbrook Road FAX 870-1603

Raleigh, North Carolina 27609-4306 (800) 255-7886

1 resolution. We needed a tool that would ingest observations

2 and available prognostic data to achieve something that was

3 realistic and useful for dispersion modeling. Now we may be

4 ready to start looking at the use prognostic models more

5 directly and we support that possibility.

6 Concerns about CALMET should be addressed and

7 looked at, and we hope to examine those closely as they

8 arise, but it shouldn't affect the status of the CALPUFF

9 because there are other options. I'd also like to point out,

10 though, that all models, especially all three dimensional,

11 non-steady state models will be sensitive to meteorological

12 inputs. 

13 And there is going to be a lot of skill in

14 developing those accurate meteorological fields, no matter

15 what model is in the process flow stream, whether it's

16 CALMET, whether it's MMIF, interpreting WRF. WRF has a

17 variety of different schemes and settings that can produce

18 very different results. And they have to be evaluated for

19 each application to ensure that they're producing accurate

20 flow fields because they will also produce sensitivities in

21 the meteorological dispersion models that come after them.

22 So this isn't a problem that is exclusive to

23 CALPUFF or CALMET. It's something we're going to have

24 develop skill and expert judgment on going forward and have

25 procedures for identifying when we have accurate meteoro-
215

KAY McGOVERN & ASSOCIATES (919) 870-1600

Suite 117, 314 West Millbrook Road FAX 870-1603

Raleigh, North Carolina 27609-4306 (800) 255-7886

1 logical fields for any dispersion model.

2 The third--the other concern identified in that

3 document was generally about evaluation studies and CALPUFF's

4 performance in various evaluation studies. A specifically

5 cited group of evaluation studies included a couple that have

6 been reevaluated as time passed and they were looked into in

7 more depth. 

8 And some of the concerns or poor performance that

9 was shown by CALPUFF were identified to be other issues,

10 sometimes related to meteorological issues, some switch

11 settings, and specifically you're speaking about the ETEX

12 model. And also some of those evaluations extend far beyond

13 what would generally be considered to be long range transport

14 studies. They extend well beyond 300 kilometers up to

15 several thousand kilometers.

16 So a more general recommendation about the

17 evaluation studies is that they shouldn't necessarily stop at

18 developing a scorecard. And that's not to say that the

19 evaluation study that does develop a scorecard is problematic

20 or improper or not helpful. It's just that can't be the

21 final step of the process.

22 There needs to be an evaluation of why models

23 didn't meet the performance criteria that they were expected

24 to. What happened? What went wrong? Was it poorly

25 performing model algorithms, things that should be updated,
216

KAY McGOVERN & ASSOCIATES (919) 870-1600

Suite 117, 314 West Millbrook Road FAX 870-1603

Raleigh, North Carolina 27609-4306 (800) 255-7886

1 things that should be changed and proved based on better and

2 more current science? Were there problems with the input

3 data, especially meteorology, which, as we said, is a very

4 sensitive input to the dispersion models? Do you need more

5 meteorology, better meteorology, more accurate? Is it

6 performing correctly?

7 Were there problems with model setups? There are

8 a lot of options and switch settings that have to be set. 

9 Are there things that are just not set correctly in a given

10 evaluation? That guidance should get out to the community so

11 people know which switch setting--they're very sensitive and

12 for which applications they should be applied, or is a limit

13 on the model formulation? Is it something that a plume or a

14 puff or a grid model just does not handle well? 

15 Those are all possibilities about why a model does

16 not meet performance goals that it might have. And

17 determining which of those possibilities or what caused the

18 poor model performance is critical to improving the model and

19 getting the best science out of them.

20 Additionally, the statistics that are used to

21 evaluate this model should be consistent with the goals we

22 have for dispersion modeling so that we're measuring the

23 correct things. So that's something to just--I know there's

24 been a lot of work on developing the statistical measures,

25 but that's something we should always keep our eye on.
217

KAY McGOVERN & ASSOCIATES (919) 870-1600

Suite 117, 314 West Millbrook Road FAX 870-1603

Raleigh, North Carolina 27609-4306 (800) 255-7886

1 The final document that I wanted to address was

2 the summary of CALPUFF ownership. In addition to statements

3 about the changes of ownership, there was also a citation

4 that described "a lag in the ability for EPA to adequately

5 understand, review and approve changes largely due to the

6 lack of an open development process." 

7 We'd like to develop that open development

8 process. We believe it's important that there's confidence

9 in the model and that all stakeholders feel that they

10 understand what's included in it. We're committed and

11 willing to work with EPA to do that and we're willing to

12 discuss a wide range of options of how to achieve that goal,

13 what it would take. I'm not going to try and formulate what

14 that will be here, but that's a conversation that I think is

15 probably--it's time and needs to be done.

16 I'm going to turn now to a few brief comments

17 about AERMOD. Some of these have been well addressed. Mark

18 covered many of these points and they've also been discussed

19 today. And I think a lot of these were questions that--very

20 helpfully a lot were addressed this morning. I'm sure

21 they'll continually be addressed as the rulemaking process

22 proceeds and people have more time to look at the models and

23 the recommendations come forward.

24 There were some questions about how BLP performs. 

25 There's going to need to be some testing by all the parties. 
218

KAY McGOVERN & ASSOCIATES (919) 870-1600

Suite 117, 314 West Millbrook Road FAX 870-1603

Raleigh, North Carolina 27609-4306 (800) 255-7886

1 Is BLP in AERMOD equivalent to BLP externally? Does AERMOD

2 treat calm and low wind speed hours in the same manner? 

3 We have some questions also about CAL3QHC similar

4 to the ones that Mark had listed and involving negative

5 emission rates. And the first two points up here have been

6 addressed earlier this morning and that's very helpful to

7 know the future status of the beta options within AERMOD and

8 the plans for them. And that appears to be a very good

9 advancement of the science.

10 There is still concern with the potential for

11 long--for building effect about GEP stack height, which are

12 now subject to downwash, how that was evaluated and further

13 evaluation of that decision within AERMOD. PRIME was

14 developed using data below GEP stack height--or stacks below

15 GEP stack heights. These circumstances are outside of the

16 general constructs of what was evaluated during the

17 development of PRIME, so there should be more evaluation of

18 that modeling. That concludes my remarks. Thank you.

19 Mr. Bridgers: Thank you, Chris, for those

20 remarks. And as I said off the record during the break, I'll

21 say on the record we do wish that Joe could be with us to be

22 in the dialogue today.

23 So I just wanted to make sure I had everything

24 right. So Mark is up next. And Mark, you do need to

25 identify yourself.
219

KAY McGOVERN & ASSOCIATES (919) 870-1600

Suite 117, 314 West Millbrook Road FAX 870-1603

Raleigh, North Carolina 27609-4306 (800) 255-7886

1 Mr. Garrison: Thanks, George. Thanks for the

2 opportunity again to present some comments. The three topics

3 that I've listed here, CALPUFF, 30 miles, and roughness

4 pretty much deal with some issues that are currently

5 considered settled policy or settled guidance.

6 Of course the Appendix W proposals that we have

7 paid so much attention to recently kind of put us in a brave

8 new world in terms of--for the modeling community in terms of

9 a couple of topics including the use of prognostic models for

10 developing representative met data for local scale models and

11 the development of guidance and policies related to the use

12 of chemical transport models for ozone and PM2.5 on the local

13 scale.

14 I think I and probably most modelers are pretty

15 excited about these developments and look forward to

16 proceeding down that path. As a matter of fact, as some

17 earlier presenters attested, I get choked up when I think

18 about this. But anyway, EPA might not agree with this, but I

19 would think there's no time like the present, given these--in

20 light of these developments to possibly reconsider or at

21 least think about some of the settled policy and guidance

22 issues.

23 The things I'm going to talk about today are

24 CALPUFF. As an Appendix A long range transport model, I'm

25 not going to address that particular comment. That comment
220

KAY McGOVERN & ASSOCIATES (919) 870-1600

Suite 117, 314 West Millbrook Road FAX 870-1603

Raleigh, North Carolina 27609-4306 (800) 255-7886

1 has been made by others. My focus is on keeping CALPUFF as a

2 candidate at least for local scale analyses. This

3 presentation is focused on that.

4 30 miles, of course, if you haven't figured out by

5 now is equal to 50 kilometers. And the discussion is about

6 using straight line, steady state models out to 50

7 kilometers. In terms of the transition from real sort of

8 steady state conditions to non-steady state should really not

9 be a bright line with discontinuities. 

10 Lagrangian models in theory can simulate this

11 transition without discontinuities. And I guess in my view

12 there ought to be something between the true steady state

13 local scale analysis and analyses have to look out to 50

14 kilometers.

15 The last topic is in terms of roughness length,

16 how to specify roughness length for input to AERMET. And the

17 question is, you know, roughness at the measurement or the

18 application site.

19 Well, why do we need the Lagrangian model at all? 

20 I think it largely has to do with wind speeds and plume

21 transport distances. These two circles are both 50

22 kilometers. The first one represents transport of a plume

23 from the center of this circle outward to 50 kilometers, and

24 each of the smaller circles represent 1 hour transport time.

25 And this kind of stuff I think is kind of
221

KAY McGOVERN & ASSOCIATES (919) 870-1600

Suite 117, 314 West Millbrook Road FAX 870-1603

Raleigh, North Carolina 27609-4306 (800) 255-7886

1 intuitive to modelers, but when you look at it this way, you

2 know, it takes 13 hours, nearly 14 hours for a plume to

3 travel from the center of the circle out to 50 kilometers. 

4 And the plume can experience changes in land use, changes in

5 winds, changes in stability, night could turn into day, day

6 could turn into night during that transport time. 

7 And especially, if you have sources in that area

8 that you're modeling in conjunction with the source in the

9 middle of the circle, it raises issues that make modelers

10 cringe sometimes that the time sequence is not really

11 correct. The plot on the right of course looks a little bit

12 better at higher wind speeds, but quite often the low wind

13 speed cases are the controlling cases.

14 And I think, you know, it's encouraging to hear in

15 the presentations and in the proposal that, you know, to do

16 multisource analyses we should really be focusing on areas

17 from 10 to 20 kilometers and not beyond that. But there are

18 questions that frequently are raised about sources at

19 distances greater than 20 kilometers, and it would be nice to

20 have a tool to deal with those distance ranges.

21 Again, why do we need the Lagrangian model? Well,

22 the atmosphere is a complex place and complex winds exist

23 even on the local scale. And we do know that there's an

24 option in the guidelines to justify a Lagrangian model on the

25 local scale due to complex winds. It's a very difficult
222

KAY McGOVERN & ASSOCIATES (919) 870-1600

Suite 117, 314 West Millbrook Road FAX 870-1603

Raleigh, North Carolina 27609-4306 (800) 255-7886

1 process that I've tried to go through a couple of times

2 without success.

3 But I have some illustrations here that take a

4 look at a 1 hour event with variable winds throughout the

5 hour. I used CALPUFF in ten minute time steps based on

6 meteorological data that was actually collected at five

7 minute intervals. So this was sort of an unusual situation,

8 but not too unusual if you consider that with AERMET we could

9 theoretically develop this kind time resolution even with

10 airport data. And then I look at AERMOD on an hourly average

11 time frame.

12 This is basically a theoretical source located in

13 complex terrain. The plots illustrate each ten minute time

14 step starting with the first ten minute time step. So in the

15 lower--the newer puffs that are released from the source by

16 CALPUFF in green--they kind of go down in age as the colors

17 suggest. It's kind of hard to see the colors, but I think

18 you'll get kind of the gist as we go through these. 

19 The contours are sort of relative concentration

20 contours. This is the first ten minute time step, second ten

21 minute time step, third ten minute time step, fourth ten

22 minute time step, fifth ten minute time step, and final ten

23 minute time step. And if you look at the hourly average wind

24 speed and direction for this generic source, this is what

25 AERMOD would predict.
223

KAY McGOVERN & ASSOCIATES (919) 870-1600

Suite 117, 314 West Millbrook Road FAX 870-1603

Raleigh, North Carolina 27609-4306 (800) 255-7886

1 Now, absolutely this is not intended to invalidate

2 AERMOD nor is it intended to validate CALPUFF. But it is

3 intended to kind of get across the point that it would be

4 helpful to have a Lagrangian model available and an

5 Lagrangian approach for all scales, ideally one that

6 simulates the steady state result for the appropriate

7 settings for steady state situations and also ideally

8 simulates the atmospheric chemical transformation at all

9 scales that we are looking for in the Appendix W proposals. 

10 And I know we're going to hear later this afternoon about

11 SCICHEM and SCIPUFF. And I think, you know, certainly that

12 direction provides a promising direction for this. And

13 pretty much only a steady--a non-steady state model can

14 handle the transition from steady state to temporal

15 variations without discontinuities.

16 So pretty much the recommendation is to keep

17 CALPUFF as a candidate for local scale analyses for the time

18 being. And as policy guidance and models are developed for

19 chemical transport models on a local scale, consider--this

20 will never happen--consider reevaluating the 50 kilometer

21 applicability range for AERMOD, and also consider evaluating

22 CALPUFF with some of the suggestions that Chris had possibly,

23 along with the evaluations of other models.

24 The second part of my discussion is on roughness

25 with a focus on z0, which is roughness. Current policy of
224

KAY McGOVERN & ASSOCIATES (919) 870-1600

Suite 117, 314 West Millbrook Road FAX 870-1603

Raleigh, North Carolina 27609-4306 (800) 255-7886

1 course is to specify land use characteristics for the

2 measurement site, using AERSURFACE to determine land use

3 characteristics based on the data set for which it's

4 developed, 1992 NLCD data.

5 These characteristics then inform the AERMOD

6 interface in terms of its creation of a complete profile of

7 winds, temperature, and turbulence. So this presentation

8 will--this part of the presentation will look at three

9 things. 

10 As we all have encountered from time to time, the

11 1992 data can be out of date and sometimes badly out of date. 

12 I'll have a brief discussion about site characteristics

13 versus measurement location characteristics, and then another

14 quick look at what is upwind or how do you define upwind in

15 terms of determining the surface characteristics.

16 This is an example of NLCD 92 for a power plant

17 site where most of the area is classified as either water or

18 quarry, strip mines, and gravel, obviously clearly out of

19 date and incorrect. I think many of us have encountered this

20 before and have developed methods to essentially redo the

21 land use classification here, which is, you know, more

22 reflective of what that site actually looks like in terms of

23 development and areas that are not fully developed and

24 enforested areas.

25 One of--I thought it was kind of an interesting
225

KAY McGOVERN & ASSOCIATES (919) 870-1600

Suite 117, 314 West Millbrook Road FAX 870-1603

Raleigh, North Carolina 27609-4306 (800) 255-7886

1 example that Rich Hamel found in Victoria, Texas. If you're

2 looking at the site characteristics for this airport

3 southwest of Victoria, it might look--well, it sort of looked

4 like an airport, but then with access to Google Earth, we

5 realized that it is no longer an airport. It has a road

6 running through it and the runways have all been developed. 

7 So just a word of caution in terms of using 1992 land use.

8 As I mentioned, the surface characteristics,

9 especially Z0, inform the AERMOD interface in creating a full

10 profile of winds, temperature and turbulence. If there are

11 differences in roughness length between the airport and the

12 site--and I have yet to encounter an airport that is a

13 perfect match for an application site--what do you do? 

14 I mean, you know, one conclusion, the airport is

15 not representative enough to collect on-site data, or the

16 other option is to run AERMOD both ways with both sets of

17 land use, which is not a very satisfying way of answering

18 that question, or perhaps using the site roughness provides a

19 better profile representation.

20 And of course I'll have to mention that the

21 potential for using prognostic meteorological data, wind and

22 temperature profiles, also calls for some consideration of

23 how to characterize land use at the application site.

24 This is one of those hard to read slides and I

25 apologize for that, but this is what the AERMOD interface
226

KAY McGOVERN & ASSOCIATES (919) 870-1600

Suite 117, 314 West Millbrook Road FAX 870-1603

Raleigh, North Carolina 27609-4306 (800) 255-7886

1 does. It takes the surface characteristics from AERMET. In

2 this case--in this one hour case, the wind speed was 0.9

3 meters per second. The airport roughness length is 0.13. 

4 The site roughness length is 1.12 meters, so clearly very

5 different.

6 And if you look at the profiles, both in terms of

7 where the mechanical mixing height is, the wind speed

8 profile, the temperature reading profile, and the profiles of

9 turbulence, they are obviously very, very different. And

10 this would lead one to the conclusion that the airport was

11 not representative of the site.

12 But I think just taking a step back for a minute,

13 the important thing to remember is that the only parameter

14 you're getting from the airport, the only measurement, is

15 really the wind speed. So if you can make the case that the

16 wind speed is representative of the site, however you would

17 do that, then I think that it is pretty clear that the site

18 roughness length actually creates a better profile for

19 modeling at that site than the--than using the airport

20 roughness length.

21 The last thing I want to look at is sort of a

22 quick, simple look at a different way of defining upwind for

23 AERSURFACE. And this is actually recognizing that AERSURFACE

24 is not part of the formal AERMOD system, just a tool to

25 develop the appropriate surface characteristics, this
227

KAY McGOVERN & ASSOCIATES (919) 870-1600

Suite 117, 314 West Millbrook Road FAX 870-1603

Raleigh, North Carolina 27609-4306 (800) 255-7886

1 approach might be one to be considered. 

2 AERSURFACE--if you're looking at particular sector

3 to develop Z0, the sector ends in a point at the application

4 site. If you have a site where stacks and sources are

5 separated by, in some cases, several hundred meters, it might

6 be more appropriate to use kind of wedge, as you see here, to

7 characterize upwind characteristics for that particular site. 

8 This is the kind of thing that can be done outside

9 of AERSURFACE. The geometric weighted average, Z0, can be

10 calculated fairly easily outside of AERSURFACE, so just a

11 suggestion as to something to consider if a site has sources

12 that are not at the same point.

13 So in the brave new world, I guess the summary--

14 the suggestions are keeping CALPUFF as an alternative for

15 local complex winds. And I think Tyler's presentation

16 indicated of course that's still an option, so it's not--the

17 mention of it doesn't mean that it's not an option. But I

18 think the suggestion is made to keep it in there as a

19 example.

20 Consider revisiting the 50 kilometer application

21 distance for AERMOD and ideally eventually substituting with

22 an appropriate Lagrangian model; consider allowing the use of

23 application site roughness in some situations. Using WRF and

24 MMIF should be encouraged. And then, finally, you know,

25 consider and evaluate different options for determining land
228

KAY McGOVERN & ASSOCIATES (919) 870-1600

Suite 117, 314 West Millbrook Road FAX 870-1603

Raleigh, North Carolina 27609-4306 (800) 255-7886

1 use specifications with MMIF generated wind and temperature

2 profiles. 26 seconds left.

3 Mr. Bridgers: Thank you again, Mark. We're

4 getting in the home stretch now, a couple more presentations. 

5 We're going to switch focus from CALPUFF to SCICHEM.

6 Mr. Chowdhury: Good afternoon. My name is

7 Biswanath Chowdhury, and I'm a senior engineer at Sage

8 Management, and I'm part of the team--development team for

9 SCIPUFF and also SCICHEM. I would like to thank you for the

10 opportunity to present the work on SCIPUFF.

11 So first, a lot of you know about AERMOD and

12 CALPUFF, but very few modelers here know about SCIPUFF or

13 SCICHEM, so I'll just go through the base development history

14 of SCIPUFF and a description of the use of SCIPUFF.

15 So SCIPUFF is acronym for second order closure

16 integrated puff model, so as the name implies, it uses second

17 order closure for modeling of the turbulence parameters. And

18 it's a puff model. More specifically, it's a Gaussian puff

19 model. To represent a concentration field we use the sum of

20 overlapping three dimensional Gaussian puffs and we step the

21 model by solving ordinary differential equations for puff

22 moments. The puff moments are the mass, the centroid, and

23 the sigma.

24 This is just a brief development history of

25 SCIPUFF, and I'll just give the highlights, and it's not a
229

KAY McGOVERN & ASSOCIATES (919) 870-1600

Suite 117, 314 West Millbrook Road FAX 870-1603

Raleigh, North Carolina 27609-4306 (800) 255-7886

1 comprehensive list. The development of SCIPUFF started in

2 1984, and it was funded by EPRI. And in 1991 DOD used

3 SCIPUFF for nuclear cloud rise model, and one of the

4 important highlights is that DOD decided to use SCIPUFF as

5 the core transport and dispersion model for HPAC, which is

6 Hazard Prediction and Assessment Capability model, so SCIPUFF

7 is the core transport model, and it has been so for--since

8 today. So a lot of our work is funded by DOD.

9 In 1998 SCIPUFF was approved by EPA as an

10 alternative model, and in 2000 EPRI funded development of

11 SCICHEM 1.0 where we put in gas phase chemistry and aqueous

12 phase chemistry in SCIPUFF so that it was named SCICHEM.

13 Other modifications for the SCIPUFF model

14 development is that we added urban wind field model in 2001,

15 then again in 2001 SCICHEM was included as a plume in grid

16 model for the CMAQ advanced plume treatment. I won't go

17 through the whole list, but the PRIME was added in 2004 to

18 take into account building effects. We have WRF and RAMS

19 support, which was added in 2011.

20 In 2012 a lot of the updates to the SCIPUFF model

21 which were not there in the SCICHEM 1.0, so EPRI decided to

22 update the SCICHEM model, and that's when we included all the

23 updates which are made to SCIPUFF into SCICHEM 3.0. And

24 Eladio, who is the program manager for SCICHEM, he will be

25 making a presentation right after me.
230

KAY McGOVERN & ASSOCIATES (919) 870-1600

Suite 117, 314 West Millbrook Road FAX 870-1603

Raleigh, North Carolina 27609-4306 (800) 255-7886

1 So the development team is led by Dr. Ian Sykes. 

2 He is the Environmental Sciences Group manager. And he is in

3 charge of overall model development, turbulence closure

4 monitoring of dispersion and concentration fluctuation

5 intensity. He has been the leader of the group for more than

6 30 years.

7 Similarly, Dr. Stephen Parker, he's also with the

8 group for more than 30 years. Doug Henn, he's an expert in

9 the meteorology section, and he has been with us more than 25

10 years. And I am responsible for the SCICHEM development. 

11 I'm one of the lead developers, and also I do the source

12 estimation part of SCIPUFF, and I have also been with the

13 development team for more than 15 years.

14 So what are the model capabilities of SCIPUFF? 

15 SCIPUFF can transport gases, liquids, or particles. It can--

16 it includes the primary and secondary operation for liquids,

17 and it can do dynamics. For example, it can do dense gas

18 effects, and also if you have a jet or if you have a burn

19 plume, it can handle that. 

20 And there are a variety of release types that it

21 can handle. The generic types are the instantaneous and

22 continuous releases. It can have a moving release or a

23 pooled release. It can also model jet releases, which can be

24 horizontal or vertical jets. It can do burn sources or stack

25 sources and also area and volume sources.
231

KAY McGOVERN & ASSOCIATES (919) 870-1600

Suite 117, 314 West Millbrook Road FAX 870-1603

Raleigh, North Carolina 27609-4306 (800) 255-7886

1 So some of the unique characteristics of SCIPUFF

2 is that in addition to the mean concentration, each puff

3 carries the variance also, so this allows SCIPUFF to take

4 into account the rambling nature of the turbulence dispersion

5 and also uncertainty in the source or in the regularity.

6 Each puff takes its own time step based on its

7 evolution grid, so a puff which has been released for example

8 at high momentum or buoyancy will take a smaller step. 

9 Similarly, it has an adaptive grid for the output, so the

10 smaller puffs will have a smaller grid and the bigger puffs

11 will have a bigger grid.

12 To properly represent the wind field, we split the

13 puffs so that we can take into account wind shear and other

14 effects, but when we split we get more number of puffs. So

15 we have a merging algorithm also so that when the puffs grow

16 they can merge together to reduce the number of puffs. And

17 SCIPUFF can be used for multiple scales. It has been used

18 from laboratory scale to global scale.

19 We do the model validation using various typical

20 and experimental studies. Some of these are listed here. We

21 have the PGT curves for short range and surface releases, the

22 instantaneous dispersion data from Weil, Mikkelsen, and

23 Hogstrom. We have used SCIPUFF compared with the laboratory

24 dispersion data from Willis and Deardorff and also fluctua25 tion data from Fackrell and Robins.
232

KAY McGOVERN & ASSOCIATES (919) 870-1600

Suite 117, 314 West Millbrook Road FAX 870-1603

Raleigh, North Carolina 27609-4306 (800) 255-7886

1 We have used SCIPUFF for continental scale field

2 experiment ANATEX, which is across North America experiment. 

3 Also we have done validation with EPRI tall stack emissions

4 experiment such as the Bull Run and Kincaid experiments.

5 Some of the other tests are listed here. One of

6 them is ETEX. Eladio I think will be presenting a slide on

7 ETEX. And we have found that it performs favorably compared

8 to other long range transport models.

9 So what are the current research and development

10 work that we're doing, and we are collaborating with a lot of

11 other groups. One of them is the Los Alamos National Lab,

12 where SCIPUFF is being integrated with the QUIC-Urban model

13 so that it takes into account the building effects.

14 We are working with ENSCO for chemical deposition. 

15 SCIPUFF has been used as a plume in grid model for the

16 CHIMERE model, which is a European model. We are working

17 with ENVIRON to put in the gas, aerosol and aqueous phase

18 chemistry for SCICHEM. We have worked with Penn State

19 University group for ensemble modeling. And for source

20 estimation we have worked for Aerodyne, worked with Aerodyne

21 and NCAR.

22 So the systems which use SCIPUFF are--SCIPUFF is

23 the core transport and dispersion model here for SCICHEM, and

24 then the other one is the Hazard Prediction and Assessment

25 Capability, HPAC, and the Joint Effects Model, which is also
233

KAY McGOVERN & ASSOCIATES (919) 870-1600

Suite 117, 314 West Millbrook Road FAX 870-1603

Raleigh, North Carolina 27609-4306 (800) 255-7886

1 part of the DOD models. And then we have the MSRAM, which is

2 the Maritime Security Risk Analysis Model, and there are

3 slightly different flavors for different departments.

4 We have been trying to parallelize the SCIPUFF

5 code, and we have tried to use OpenMP, and as we were saying,

6 we are working with LANL to get the QUIC-URB model integrated

7 in SCIPUFF. And other work we're trying to do is with

8 SCIPUFF as an inline component of WRF-ARW simulations, and

9 also source attribution.

10 So we have had success with parallelizing SCIPUFF

11 in that initially the challenge is that when you run a

12 parallel--the code in parallel and in serial, you tend to get

13 slight differences in results. And we have set up the code

14 now so that there's hardly any difference in the concentra15 tion and there's very insignificant difference in the

16 deposition and the dosage.

17 And in the QUIC-URB integration, we--the QUIC-URB

18 represents building flow and dispersion in near field using

19 Lagrangian particles, and the model runs concurrently with a

20 continuous transfer, so once the puff grows bigger, it hands

21 over--the QUIC-URB model hands over the puffs to SCIPUFF for

22 longer range dispersion.

23 And for the WRF integration we are investigating

24 embedding SCIPUFF inside WRF-ARW so that we can run the

25 dispersion in sync with the meteorology. And using this we
234

KAY McGOVERN & ASSOCIATES (919) 870-1600

Suite 117, 314 West Millbrook Road FAX 870-1603

Raleigh, North Carolina 27609-4306 (800) 255-7886

1 will have direct access to the full meteorological field from

2 WRF.

3 Another area that we are working on is trying to

4 get source attribution. In this we want to tag each source

5 so that when we merge a puff we know that how much mass comes

6 from that source, and using that we should be able to query

7 the sampler and find out what is the contribution from an

8 individual source.

9 So I would like to summarize that SCIPUFF R & D is

10 ongoing in a managed environment, and the science in SCIPUFF

11 is continuously being updated. The source of the core

12 transport model is public domain, and we have worked with

13 multiple contributors to advance the capabilities.

14 There is extensive model verification and

15 validation. DOD has their own validation process. For

16 example, for defense analysis we have found that SCIPUFF was

17 underpredicting for convective cases, so we improved the

18 SCIPUFF model to include skew turbulence and the results are

19 much better than what it was before. So we are also

20 committed to the regulatory air quality community.

21 Some of the applications that SCIPUFF is currently

22 being used is for air quality permitting. It's part of the

23 Appendix W alternative model. And also it's used for

24 emergency response for DHS, Department of Homeland Security,

25 and DOD and Coast Guard. If there are any questions, I can
235

KAY McGOVERN & ASSOCIATES (919) 870-1600

Suite 117, 314 West Millbrook Road FAX 870-1603

Raleigh, North Carolina 27609-4306 (800) 255-7886

1 send by e-mail.

2 Mr. Bridgers: Thank you, Biswanath. As I'm

3 transitioning slides and we hit the 5 o'clock hour, I know

4 that some people may be leaving today for flights that are

5 not going to be with us tomorrow. So if you are leaving

6 today, I do wish you safe travels and appreciate your

7 participation today. 

8 And also, after we end the session, because I know

9 there's going to be a mad dash for the door, I do ask if the

10 regional modelers from the EPA would all congregate somewhere

11 up here close to the front. I'd just like for all of us to

12 get together for a minute or two. So now we will change

13 presenters on SCICHEM to Eladio.

14 Mr. Knipping: Thank you, everyone, and thank

15 you, EPA, for this opportunity to speak on SCICHEM. I'm

16 Eladio Knipping and I'm with the Electric Power Research

17 Institute. I'd like to recognize my colleague, Naresh Kumar,

18 who's in the room, and also the SCICHEM development team,

19 particularly Biswanath, who just finished speaking, and

20 Prakash Karamchandani from Ramboll Environ. They have been

21 instrumental in developing the SCICHEM model.

22 As Biswanath mentioned, SCICHEM and SCIPUFF both

23 simulate the evolution of puffs in the atmosphere. These are

24 three dimensional Gaussian puffs, but the models themselves

25 are Lagrangian models. In fact SCICHEM is a Lagrangian
236

KAY McGOVERN & ASSOCIATES (919) 870-1600

Suite 117, 314 West Millbrook Road FAX 870-1603

Raleigh, North Carolina 27609-4306 (800) 255-7886

1 photochemical puff model with different options for gas and

2 aerosol chemistry, the most detailed of which are consistent

3 with the mechanisms found in photochemical grid models. In

4 summary, SCICHEM is also a photochemical model.

5 It is able to model the dispersion of primary

6 pollutants and the formation of secondary pollutants. It can

7 explicitly model the conversion of NO to NO2. It can be used

8 to model ozone and secondary PM2.5. It can be used for near9 source applications as well as long range transport

10 applications. There is an option to simplify the chemistry

11 for near-source applications. This refers to the NO to NO2

12 conversion.

13 The features of SCICHEM 3.0. Its chemistry--the

14 gas phase chemistry is based on the carbon bond 5 mechanism. 

15 And the aerosol and aqueous chemistry modules are based on

16 CMAQ 4.7.1. So these are consistent, again, with photo17 chemical grid models.

18 The dispersion, as Biswanath had mentioned

19 earlier, incorporates the last ten years of improvements in

20 the SCIPUFF model. It can treat point, area, and volume

21 sources and it has the PRIME building downwash algorithm. It

22 is able to be run in a manner which should be familiar to

23 AERMOD users. And we have also the ability to specify

24 background concentration fields based on photochemical grid

25 modeling simulations.
237

KAY McGOVERN & ASSOCIATES (919) 870-1600

Suite 117, 314 West Millbrook Road FAX 870-1603

Raleigh, North Carolina 27609-4306 (800) 255-7886

1 A little bit of SCICHEM history. SCIPUFF, the

2 dispersion component, was evaluated with tracer experiments

3 and AERMOD databases, and then we developed SCICHEM in order

4 to add chemistry into SCIPUFF. And it in turn was evaluated

5 with power plant plume measurements. There were only

6 sporadic incremental upgrades up to 2010, at which time a

7 major upgrade effort was initiated around 2011.

8 SCICHEM was released as a public domain open

9 source beta, the first beta of which was focused on modeling

10 one hour NO2 and SO2. It was released in the middle of 2013. 

11 The second beta for modeling both primary and secondary

12 impacts was released in the middle of 2014. And what we were

13 able to do during these beta periods was obtain extensive

14 user feedback from a variety of federal, local, and

15 consulting groups.

16 And the final version, SCICHEM 3.0, was released

17 on Monday, August 10th, 2015. Several of you probably got

18 spammed by me announcing the e-mail. It is located on the

19 Source Forge web site, sourceforge.net/projects/epri20 dispersion. Again, it is available as a public domain, open

21 source model.

22 SCICHEM evaluations have included theoretical

23 studies and also evaluation with tracer experiments such as

24 the European Tracer Experiment--I'll show a result of that--

25 and also the AERMOD evaluation databases. Most importantly,
238

KAY McGOVERN & ASSOCIATES (919) 870-1600

Suite 117, 314 West Millbrook Road FAX 870-1603

Raleigh, North Carolina 27609-4306 (800) 255-7886

1 the photochemical grid modeling component has been evaluated

2 with aircraft measurements, for example the TVA Cumberland

3 plume during the Southern Oxidants Studies, the Dolet Hills

4 power plant plume, which I'll show some results. 

5 And ongoing, we have an evaluation with the 2013

6 SENEX measurements from the Southeast Nexus Experiments. 

7 These were flights conducted by NOAA in 2013 as part of the

8 Southeast Atmosphere Studies. And those include measurements

9 of ozone and PM2.5, so these will be rather exciting

10 evaluations to perform. We also have an exploratory research

11 study using measurements located at the Southeastern Aerosol

12 Research and Characterization Study network sites.

13 On this slide I show the results of SCICHEM on the

14 left and observations on the right for long range transport

15 evaluation using tracer studies from the European Tracer

16 Experiment in 1994. What we see is that there are consistent

17 transport of the tracers, both when comparing the predicted

18 concentration fields with the observations.

19 Now, this result is from the Dolet Hills power

20 plant plume transects from the Northeast Texas Air Care

21 (NETAC) 2005 Air Quality Study. And what we see for this

22 simulation from left to right, NOx, NOy, ozone, and SO2. What

23 we see is that, you know, the peaks for NOy, SO2, and ozone

24 are all within 20 percent of observed values. We are doing

25 rather well with simulating this plume. This is an advanced
239

KAY McGOVERN & ASSOCIATES (919) 870-1600

Suite 117, 314 West Millbrook Road FAX 870-1603

Raleigh, North Carolina 27609-4306 (800) 255-7886

1 Lagrangian photochemical model accurately simulating ozone.

2 For the 54 kilometer downwind transect, the plumes

3 tend to diverge a little bit from their center lines. And as

4 many other presenters have said, it's really difficult to get

5 the transport, you know, completely aligned. But the plume

6 results are very consistent with the observations. And

7 again, for ozone we are simulating the production of a 20 ppb

8 ozone peak in the observations with an advanced Lagrangian

9 photochemical model.

10 Now, one of the comments that we received during

11 the SCICHEM beta periods was that the model needed to be

12 stress tested, that we needed to be able to assure the

13 community that the model could be run for annual simulations

14 for different types of sources and in different chemical and

15 meteorological environments. 

16 So the objective of our stress testing is to test

17 the robustness of the model for long term, annual applica18 tions for these range of conditions and to demonstrate the

19 calculation of secondary impacts in Class I areas by doing

20 so. Our hypothetical sources are a power plant, a flare with

21 highly reactive VOC emissions, and a petrochemical complex

22 plume. In the interest of time, I won't be showing results

23 for the domains that we have modeled. I will focus on the

24 Southwest--what we're calling the Southwest Four Corners

25 domain located in the Four Corners area.
240

KAY McGOVERN & ASSOCIATES (919) 870-1600

Suite 117, 314 West Millbrook Road FAX 870-1603

Raleigh, North Carolina 27609-4306 (800) 255-7886

1 For the power plant simulation--again, these are

2 hypothetical sources--we are able to simulate PM2.5 values in

3 the range of .5 to 4.3 micrograms per cubic meter. Most of

4 that is due to nitrate formation in the range of 0.4 to 4

5 micrograms and maximum PM sulfate ranges from 0.1 to 0.4

6 micrograms per cubic meter. Our ozone, fourth highest 8 hour

7 average ozone impacts ranges, depending on location, from 3.3

8 to 8 ppb.

9 For the highly reactive VOC flares, we have PM2.5

10 impacts ranging from 0.3 to 0.6 micrograms per cubic meter,

11 with the details following. The fourth highest 8 hour

12 average ozone impact ranges from 0.6 to 3.9 ppb, consistent

13 with the emissions that were used in this hypothetical

14 scenario.

15 And for the petrochemical complex PM impact, we

16 have also now some small amounts of secondary organic aerosol

17 precursor emissions, toluene and xylene. So not only do we

18 simulate the formation of nitrate and sulfate, but we

19 simulate a very small amount of secondary organic aerosol. 

20 But we are able to simulate secondary organic aerosol. In

21 fact we are able to simulate secondary PM formation

22 consistent with the emissions in all scenarios, and as well

23 as we can model formation of ozone consistent with the

24 emissions that were generated from these sources.

25 So in summary of the stress--let me summarize the
241

KAY McGOVERN & ASSOCIATES (919) 870-1600

Suite 117, 314 West Millbrook Road FAX 870-1603

Raleigh, North Carolina 27609-4306 (800) 255-7886

1 stress testing. We were able to conduct stress testing for

2 selected domains and source scenarios. And the average--the

3 run times for these annual simulations range from 20 to 80

4 hours depending on the domain and source scenario. And what

5 we're finding is that the model is robust.

6 So in conclusion, SCICHEM has been thoroughly

7 evaluated throughout its history of development and shown to

8 be a robust model that can handle different sources under

9 different chemical and meteorological regimes. 

10 SCICHEM has been demonstrated that it can be used

11 to simulate pollutant concentrations accurately for different

12 applications such as short range SO2 simulations, short range

13 NO2 simulations, and long range ozone and primary and

14 secondary PM2.5 simulations.

15 Representative run times is around 15 to 30

16 minutes for annual SO2 simulations, 20 to 40 minutes for NO2

17 simulations, and 20 to 80 hours for annual simulations with

18 secondary pollutants. Let me just reiterate one more time:

19 an advanced Lagrangian photochemical model that can simulate

20 ozone and secondary PM2.5.

21 Additional details on SCICHEM can be found in the

22 following peer reviewed journal publication in addition to

23 the documentation included with the model. The citation is

24 shown on the slide. It is an open access article, so it is

25 free to download, and I will not say the actual URL because
242

KAY McGOVERN & ASSOCIATES (919) 870-1600

Suite 117, 314 West Millbrook Road FAX 870-1603

Raleigh, North Carolina 27609-4306 (800) 255-7886

1 that wouldn't be nice. Thank you.

2 Mr. Bridgers: Thank you, Eladio. Eladio is

3 helping you get out the door just a little bit sooner. So we

4 have one more talk. In this one Rob Kaufmann is going to

5 give some comments on behalf of the NAAQS Implementation

6 Coalition. And Rob, just to be nice, I have a background

7 slide for you.

8 Mr. Kaufmann: Oh, boy. I'm honored.

9 Mr. Bridgers: So Rob Kaufmann.

10 Mr. Kaufmann: Well, you can all read the

11 slide. I'm Rob Kaufmann and I work for Koch Industries, and

12 I'm here on behalf of the NAAQS Implementation Coalition. 

13 And Chet at the beginning of the day told me that since I go

14 last, I have as long as I want. Fortunately for you, I do

15 not have a 30 slide deck with embedded videos. I'm not

16 planning to do any song and dance.

17 For the record I want to note that I am not

18 related to Andy Kaufman, so I'm not planning to sing or lip19 synch the words to the Mighty Mouse theme. However, I think

20 it might be appropriate, if you are familiar with the Mighty

21 Mouse them, with a couple of subtle changes, it could have

22 been the theme song for this conference, "Here we come to

23 save the day. EPA's Appendix W fixes are on the way."

24 Audience member: Sing it.

25 Mr. Kaufmann: What I do have--and I'm not
243

KAY McGOVERN & ASSOCIATES (919) 870-1600

Suite 117, 314 West Millbrook Road FAX 870-1603

Raleigh, North Carolina 27609-4306 (800) 255-7886

1 looking for any comment from EPA on that, but it would have

2 been good to start the day with that theme song.

3 I do have a very brief statement, and fortunately

4 or unfortunately for you, it was drafted by lawyers. I'm not

5 a modeler. I'm not an engineer. I'm not a lawyer, so bear

6 with me. For those of you who aren't familiar with the NAAQS

7 Implementation Coalition, it's comprised of trade associa8 tions, companies, and what the drafter of this called other

9 entities who confront challenges in the permitting and

10 operation of their facilities under increasingly stringent

11 NAAQS. 

12 And our coalition has been in regular contact with

13 EPA starting at the very highest levels, Gina McCarthy, Janet

14 McCabe, and down to the level of Chet and his team here at

15 the Office of Air Quality Planning and Standards. And we

16 have been working with them and discussing the development of

17 tools and policies and guidance to address the issues that

18 arise as the NAAQS have been pushed beyond their limits by

19 new and more stringent air quality standards. And we hope to

20 keep that dialogue open and in fact plan to keep that

21 dialogue open.

22 A lot of coalition members--and there are a lot of

23 coalition members in the audience, API, AISI, AFPA, NCASI--

24 they've been investing resources and testing and modeling

25 tools that have been provided to EPA. And in fact some of
244

KAY McGOVERN & ASSOCIATES (919) 870-1600

Suite 117, 314 West Millbrook Road FAX 870-1603

Raleigh, North Carolina 27609-4306 (800) 255-7886

1 those results were the basis for some of the fixes to

2 Appendix W. 

3 And we really appreciate all the work that EPA has

4 done over the last couple of years. They've identified some

5 serious problems with the models. They've attempted to

6 address them. However, as a coalition, we think that some of

7 those problems still exist and have not been resolved.

8 And it's probably no surprise to you that since we

9 represent industry that it's our view that current

10 implementation policies and modeling tools continue to over11 predict and in some cases significantly overpredict emission

12 impacts, resulting in model results that do not reflect local

13 air quality or public exposure.

14 Now, in our far distant past when NAAQS were far

15 less stringent, there was what I might call headroom that

16 would allow the overly conservative assumption of the models,

17 especially as applied to PSD permitting, to not really

18 present any significant modeling problems. 

19 But as the standards have gotten tighter, the

20 conservative nature of some of these modeling tools leads to

21 the overprediction which I just referenced and could cause

22 states to have to incorporate overly burdensome emission

23 limits in both their attainment and nonattainment SIPs.

24 The proposed changes to Appendix W and many of the

25 justifications for those changes were just released, as we
245

KAY McGOVERN & ASSOCIATES (919) 870-1600

Suite 117, 314 West Millbrook Road FAX 870-1603

Raleigh, North Carolina 27609-4306 (800) 255-7886

1 all know. And coalition members are still evaluating them,

2 reviewing them, and testing them. Some of that testing has

3 been discussed at length today.

4 We are pleased to see that some of the--that based

5 on our preliminary reviews some of those changes have

6 resulted in significant improvements, but we believe that

7 there is a continued need for collaboration between industry

8 and EPA as we go forward with some of those model fixes, and

9 AWMA presentations noted that as well. So we concur with

10 that finding. And we will be providing some more in depth

11 comments for the record once we've had time to fully dive

12 into the Appendix W Federal Register notice.

13 In closing, in closing, we would note that

14 although EPA acknowledges that there are some instances

15 where, quote, the preferred air quality model may be shown to

16 be less than reasonably acceptable, unquote, the new document

17 shows a preference for modeling analyses over monitoring. 

18 And it is our ongoing belief that a modeling based

19 approach will increase the challenges to businesses and

20 detract from the Clear Air Act's goal of ensuring that

21 economic growth will occur consistent with the preservation

22 of existing clean air resources. And that's it. I'm done. 

23 And I guess we can adjourn with George's permission. Thank

24 you.

25 Mr. Bridgers: Thank you, Rob. Yes, actually
246

KAY McGOVERN & ASSOCIATES (919) 870-1600

Suite 117, 314 West Millbrook Road FAX 870-1603

Raleigh, North Carolina 27609-4306 (800) 255-7886

1 that's one of the next official duties that I can do. But as

2 I go through the official process of suspending for the night

3 the conference and public hearing, a quick reminder that we

4 do start at 8:30 in the morning. We do have ten more public

5 presentations before we get to any additional oral comments.

6 The only other thing I would have to say is I

7 think they're a little grouchy if you're hanging around here

8 after 6 o'clock. So if you are a visitor and not an EPA

9 employee, probably aim to be off campus in the next, you

10 know, 30 minutes or so. But again, I hope you have a

11 wonderful evening. For those that are traveling, I hope you

12 have safe travels back. I suspend the conference and public

13 hearing until 8:30 tomorrow morning.
247

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 States

Environmental Protection Agency in Research Triangle 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 interested 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

 /s/ Kay K. McGovern