Questions on FCPP modeling files for APS proposal

Scott Bohning Scott Bohning to: Kostrova, Olga 12/17/2010 10:36 AM

Cc: "Paine, Bob", Anita Lee

Olga -

Hello! This week I have finally been able to examine the modeling files from the disk you sent the other 

week, and I have a few questions for you... sorry to drop this on you so near the holidays. (Please forward 

if you are not the right person to ask about this.)

1.Particular modeling output files relied on Particular modeling output files relied on

I wanted to confirm exactly which outputs were used as the basis for conclusions and the graphic 

(attached) in the APS proposal, since there are various modeling files on the disk and not all of them were 

used (e.g. c2 files for LNB not used). I would appreciate if you could check that I have this right.

The following lists what I found, in this format:

My conclusion for the scenario in the bar chart graphic 

CALPOST input file name for arches for 2001

POSTUTIL concentration output file used as CALPOST input

POSTUTIL input file name: CALPUFF.DAT a.k.a.. MODDAT file(s) used as POSTUTIL 

input

All the units in base case were used in "Baseline" in APS Proposal graphic

calpost\am1_c0\ct_fcpp_c0_am1_arch_01.inp

postutil\am1\pu_fcpp_c0_am1_01.con

am1\pu_fcpp_c0_am1_01.inp: 1 calpuff\cf_fcpp_c0_u123_01.con

am1\pu_fcpp_c0_am1_01.inp: 2 calpuff\cf_fcpp_c0_u45_01.con

Just units 4&5 in base case were used in "Units 4 & 5 Baseline" in APS Proposal graphic

calpost\am1_c0_u45\ct_fcpp_c0_am1_arch_01.inp

postutil\am1\pu_fcpp_c0_am1_u45_01.con

am1\pu_fcpp_c0_am1_u45_01.inp: 1 calpuff\cf_fcpp_c0_u45_01.con

All the units in SCR & PM control case were used in "EPA BART Case: SCR/PM Controls (Units 1-5 ON)" 

in APS Proposal graphic

calpost\am1_c5\ct_fcpp_c5_am1_arch_01.inp

postutil\am1\pu_fcpp_c5_am1_01.con

am1\pu_fcpp_c5_am1_01.inp: 1 calpuff\cf_fcpp_c5_u123_01.con

am1\pu_fcpp_c5_am1_01.inp: 2 calpuff\cf_fcpp_c5_u45_01.con

Just units 4&5 in SCR & PM control case were used in "Units 4 & 5 SCR/PM Controls" in APS Proposal 

graphic

calpost\am1_c5_u45\ct_fcpp_c5_am1_arch_01.inp

postutil\am1\pu_fcpp_c5_am1_u45_01.con

am1\pu_fcpp_c5_am1_u45_01.inp: 1 calpuff\cf_fcpp_c5_u45_01.con

2.Basis for emissions Basis for emissions

The emissions used by AECOM for "EPA BART" (c5) do not appear to match the emissions that EPA used 

to model the effect of SCR (c3) and of PM controls (c1); see comparison in attached spreadsheet (see 
notes at its top and yellow highlighting in its ratio table ). (The emissions used for scenarios c0 base

case, and c2 LNB do match EPA's, though.) Am I looking in the wrong place, or can you explain why the 

numbers differ? Can you provide details on where those emission numbers came from, such as the nice 

spreadsheets ENSR/AECOM originally provided way back when?

3.CMAQ ammonia scenario CMAQ ammonia scenario

This one we don't need an answer on, but I thought you would like to know. It appears to me that the 

POSTUTIL files under Monthly_Ave_CMAQ all use both the u123 and the u45 CALPUFF results, whereas 

I would have expected them to have just u45 (units 4 & 5) to show results of APS proposal. The do not 

have "u45" in their names, so I see that this actually is consistent with how file names were used for the 

other scenarios (i.e. no "u" means all the units)... maybe this is a non-problem, since use of these outputs 

would be for effect "EPA BART", not for the APS proposal.

Thanks for any help you can provide.

- Scott B.

-- 

=+=+=+=+=+=+=+=+=+=+=+=+=+=+=

"Scott Bohning" <bohning.scott@epa.gov>

U.S. EPA Region 9, AIR-7

415/947-4127 fax-3579

P.S. I hope you will have some good time off!

Attachment: "APS Proposal graphic", the bar chart on p.5 of file "FINAL EPA-BART LETTER ED FOX.pdf", 

Nov. 24, 2010

Attachment: spreadsheet comparison of AECOM emissions for APS proposal and "EPA BART" to 

emissions used by EPA

 aps_rh_impacts_barchart.png aps_rh_impacts_barchart.png emissions_APS_alt.xlsx emissions_APS_alt.xlsx 
RE: Questions on FCPP modeling files for APS proposal

Kostrova, Olga 

to: 

Scott Bohning 

12/17/2010 12:42 PM 

Cc: 

"Paine, Bob", Anita Lee 

Show Details 

Scott, 

Thanks for reviewing the files I sent to you. I will respond to all of your questions on Monday. Regarding the 

emissions: we used the lb/MMBtu directly from the TSD’s Table ES-1 and multiplied them by the heat input rates 

you used in the ANPR modeling, instead of applying a percent reduction to the baseline emissions.

Regards,

Olga

From: Bohning.Scott@epamail.epa.gov [mailto:Bohning.Scott@epamail.epa.gov] 

Sent: Friday, December 17, 2010 1:36 PM 

To: Kostrova, Olga 

Cc: Paine, Bob; Lee.Anita@epamail.epa.gov 

Subject: Questions on FCPP modeling files for APS proposal

 

Olga - 

Hello! This week I have finally been able to examine the modeling files from the disk you sent the other week, 

and I have a few questions for you... sorry to drop this on you so near the holidays. (Please forward if you are not 

the right person to ask about this.) 

1. Particular modeling output files relied on 

I wanted to confirm exactly which outputs were used as the basis for conclusions and the graphic (attached) in the 

APS proposal, since there are various modeling files on the disk and not all of them were used (e.g. c2 files for 

LNB not used). I would appreciate if you could check that I have this right. 

The following lists what I found, in this format: 

My conclusion for the scenario in the bar chart graphic 

CALPOST input file name for arches for 2001 

 POSTUTIL concentration output file used as CALPOST input 

 POSTUTIL input file name: CALPUFF.DAT a.k.a.. MODDAT file(s) used as POSTUTIL input 

All the units in base case were used in "Baseline" in APS Proposal graphic 

calpost\am1_c0\ct_fcpp_c0_am1_arch_01.inp 

 postutil\am1\pu_fcpp_c0_am1_01.con 

 am1\pu_fcpp_c0_am1_01.inp: 1 calpuff\cf_fcpp_c0_u123_01.con 

 am1\pu_fcpp_c0_am1_01.inp: 2 calpuff\cf_fcpp_c0_u45_01.con 

Just units 4&5 in base case were used in "Units 4 & 5 Baseline" in APS Proposal graphic 

calpost\am1_c0_u45\ct_fcpp_c0_am1_arch_01.inp 

 postutil\am1\pu_fcpp_c0_am1_u45_01.con

Page 1 of 2

file://C:\Documents and Settings\ALEE07\Local Settings\Temp\notesBAAA25\~web6520.h... 1/6/2011
 am1\pu_fcpp_c0_am1_u45_01.inp: 1 calpuff\cf_fcpp_c0_u45_01.con

 

All the units in SCR & PM control case were used in "EPA BART Case: SCR/PM Controls (Units 1-5 ON)" in APS 

Proposal graphic 

calpost\am1_c5\ct_fcpp_c5_am1_arch_01.inp 

 postutil\am1\pu_fcpp_c5_am1_01.con 

 am1\pu_fcpp_c5_am1_01.inp: 1 calpuff\cf_fcpp_c5_u123_01.con 

 am1\pu_fcpp_c5_am1_01.inp: 2 calpuff\cf_fcpp_c5_u45_01.con 

 

Just units 4&5 in SCR & PM control case were used in "Units 4 & 5 SCR/PM Controls" in APS Proposal graphic 

 

calpost\am1_c5_u45\ct_fcpp_c5_am1_arch_01.inp 

 postutil\am1\pu_fcpp_c5_am1_u45_01.con 

 am1\pu_fcpp_c5_am1_u45_01.inp: 1 calpuff\cf_fcpp_c5_u45_01.con 

2. Basis for emissions 

The emissions used by AECOM for "EPA BART" (c5) do not appear to match the emissions that EPA used to 

model the effect of SCR (c3) and of PM controls (c1); see comparison in attached spreadsheet (see notes at its 

top and yellow highlighting in its ratio table). (The emissions used for scenarios c0 base case, and c2 LNB do 

match EPA's, though.) Am I looking in the wrong place, or can you explain why the numbers differ? Can you 

provide details on where those emission numbers came from, such as the nice spreadsheets ENSR/AECOM 

originally provided way back when? 

3. CMAQ ammonia scenario 

This one we don't need an answer on, but I thought you would like to know. It appears to me that the POSTUTIL 

files under Monthly_Ave_CMAQ all use both the u123 and the u45 CALPUFF results, whereas I would have 

expected them to have just u45 (units 4 & 5) to show results of APS proposal. The do not have "u45" in their 

names, so I see that this actually is consistent with how file names were used for the other scenarios (i.e. no "u" 

means all the units)... maybe this is a non-problem, since use of these outputs would be for effect "EPA BART", 

not for the APS proposal. 

Thanks for any help you can provide. 

- Scott B. 

-- 

=+=+=+=+=+=+=+=+=+=+=+=+=+=+= 

"Scott Bohning" <bohning.scott@epa.gov> 

U.S. EPA Region 9, AIR-7 

415/947-4127 fax-3579 

P.S. I hope you will have some good time off! 

Attachment: "APS Proposal graphic", the bar chart on p.5 of file "FINAL EPA-BART LETTER ED FOX.pdf", Nov. 

24, 2010 

Attachment: spreadsheet comparison of AECOM emissions for APS proposal and "EPA BART" to emissions used 

by EPA

Page 2 of 2

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RE: Questions on FCPP modeling files for APS proposal

Kostrova, Olga 

to: 

Scott Bohning 

12/21/2010 08:24 AM 

Cc: 

"Paine, Bob", Anita Lee, C.Mathai, "Kostrova, Olga"

Show Details 

Scott,

Please find below our responses to your questions. In the future, it would be good for you to copy APS 

on questions so that they are aware of your review 

progress. 

1. Particular modeling output files relied on

Your understanding of the modeling files in relation to the results graphic is correct. We also modeled 

a fifth case (not depicted on your graphic) with LNB/OFA on Units 4&5 and Units 1-3 shut down (c2). 

 The graphs with that case included are attached (“modeling results – 5 cases.bmp”)

2. Basis for emissions

There are actually two versions of the EPA Region 9 proposed BART emissions, associated with 

different averaging times. We selected for modeling the version in the Technical Support Document 

Table 40, which are based on 30-day rolling averages for NOx and a 6-hour average for PM. However,

in emission tables that you included on the hard drive containing the EPA Region 9 modeling files, 

there was a computation of NOx emissions associated with the SCR controls on Units 1-5 by applying 

an 80% reduction to the worst-case daily baseline NOx emissions. PM emissions associated with the 

ESP controls on Units 1-3 were computed by applying a 52% (on Unit 1) and 59% (on Units 2-3) 

reduction to the worst-case daily baseline PM emissions. These represent peak 24-hour average 

emissions, while the TSD Table 40 generally appears to represent lower emission rates associated with

a longer (30-day) averaging time. We modeled the peak 24-hour emissions for the baseline case and 

the 30-day rolling average emissions for the control cases. Therefore, our modeling results will likely 

overstate the benefits of SCR and PM controls.

3. CMAQ ammonia scenario

We used the CMAQ-derived ammonia values only for a sensitivity study to compare the results from 

Peak 24-hour emissions 30-day average emissions

NOx worstcase daily 

average

PM worst-case

daily average

NOx 30-day

average

PM 6-hour

average

lb/MMBtu lb/MMBtu lb/MMBtu lb/MMBtu

0.17 0.014 0.16 0.012

0.14 0.017 0.13 0.012

0.13 0.015 0.12 0.012

0.13 0.025 0.10 0.015

0.11 0.012 0.10 0.015

Page 1 of 4

file://C:\Documents and Settings\ALEE07\Local Settings\Temp\notesBAAA25\~web9794.h... 1/6/2011
the baseline case and the EPA BART case. The EPA BART case includes modeling of all five units, not

just Units 4 and 5. Therefore, in POSTUTIL, we combined the impacts from Units 1-3 and units 4-5. 

 However, if EPA is interested in the results of APS emissions proposals using the CMAQ ammonia 

concentrations, these could be modeled.

Please let me know if you have any questions.

Regards,

Olga

Olga Kostrova

Air Quality Specialist

Environment

D 978.589.3174

olga.kostrova@aecom.com

AECOM 

2 Technology Park Drive, Westford, MA 01886-3140

T 978.589.3174 F 978.589.3312

http://www.aecom.com/" title="blocked::http://www.aecom.com/">www.aecom.com

 Please consider the environment before printing this e-mail 

From: Bohning.Scott@epamail.epa.gov [mailto:Bohning.Scott@epamail.epa.gov] 

Sent: Friday, December 17, 2010 1:36 PM 

To: Kostrova, Olga 

Cc: Paine, Bob; Lee.Anita@epamail.epa.gov 

Subject: Questions on FCPP modeling files for APS proposal

 

Olga - 

Hello! This week I have finally been able to examine the modeling files from the disk you sent the other week, 

and I have a few questions for you... sorry to drop this on you so near the holidays. (Please forward if you are not

the right person to ask about this.) 

1. Particular modeling output files relied on 

I wanted to confirm exactly which outputs were used as the basis for conclusions and the graphic (attached) in the

APS proposal, since there are various modeling files on the disk and not all of them were used (e.g. c2 files for 

LNB not used). I would appreciate if you could check that I have this right. 

The following lists what I found, in this format: 

My conclusion for the scenario in the bar chart graphic 

CALPOST input file name for arches for 2001 

 POSTUTIL concentration output file used as CALPOST input 

 POSTUTIL input file name: CALPUFF.DAT a.k.a.. MODDAT file(s) used as POSTUTIL input 

All the units in base case were used in "Baseline" in APS Proposal graphic 

calpost\am1_c0\ct_fcpp_c0_am1_arch_01.inp 

 postutil\am1\pu_fcpp_c0_am1_01.con 

 am1\pu_fcpp_c0_am1_01.inp: 1 calpuff\cf_fcpp_c0_u123_01.con 

 am1\pu_fcpp_c0_am1_01.inp: 2 calpuff\cf_fcpp_c0_u45_01.con

Page 2 of 4

file://C:\Documents and Settings\ALEE07\Local Settings\Temp\notesBAAA25\~web9794.h... 1/6/2011
Just units 4&5 in base case were used in "Units 4 & 5 Baseline" in APS Proposal graphic 

calpost\am1_c0_u45\ct_fcpp_c0_am1_arch_01.inp 

 postutil\am1\pu_fcpp_c0_am1_u45_01.con 

 am1\pu_fcpp_c0_am1_u45_01.inp: 1 calpuff\cf_fcpp_c0_u45_01.con 

 

All the units in SCR & PM control case were used in "EPA BART Case: SCR/PM Controls (Units 1-5 ON)" in APS 

Proposal graphic 

calpost\am1_c5\ct_fcpp_c5_am1_arch_01.inp 

 postutil\am1\pu_fcpp_c5_am1_01.con 

 am1\pu_fcpp_c5_am1_01.inp: 1 calpuff\cf_fcpp_c5_u123_01.con 

 am1\pu_fcpp_c5_am1_01.inp: 2 calpuff\cf_fcpp_c5_u45_01.con 

 

Just units 4&5 in SCR & PM control case were used in "Units 4 & 5 SCR/PM Controls" in APS Proposal graphic 

 

calpost\am1_c5_u45\ct_fcpp_c5_am1_arch_01.inp 

 postutil\am1\pu_fcpp_c5_am1_u45_01.con 

 am1\pu_fcpp_c5_am1_u45_01.inp: 1 calpuff\cf_fcpp_c5_u45_01.con 

2. Basis for emissions 

The emissions used by AECOM for "EPA BART" (c5) do not appear to match the emissions that EPA used to 

model the effect of SCR (c3) and of PM controls (c1); see comparison in attached spreadsheet (see notes at its 

top and yellow highlighting in its ratio table). (The emissions used for scenarios c0 base case, and c2 LNB do 

match EPA's, though.) Am I looking in the wrong place, or can you explain why the numbers differ? Can you 

provide details on where those emission numbers came from, such as the nice spreadsheets ENSR/AECOM 

originally provided way back when? 

3. CMAQ ammonia scenario 

This one we don't need an answer on, but I thought you would like to know. It appears to me that the POSTUTIL 

files under Monthly_Ave_CMAQ all use both the u123 and the u45 CALPUFF results, whereas I would have 

expected them to have just u45 (units 4 & 5) to show results of APS proposal. The do not have "u45" in their 

names, so I see that this actually is consistent with how file names were used for the other scenarios (i.e. no "u" 

means all the units)... maybe this is a non-problem, since use of these outputs would be for effect "EPA BART", 

not for the APS proposal. 

Thanks for any help you can provide. 

- Scott B. 

-- 

=+=+=+=+=+=+=+=+=+=+=+=+=+=+= 

"Scott Bohning" <bohning.scott@epa.gov> 

U.S. EPA Region 9, AIR-7 

415/947-4127 fax-3579 

P.S. I hope you will have some good time off! 

Page 3 of 4

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Attachment: "APS Proposal graphic", the bar chart on p.5 of file "FINAL EPA-BART LETTER ED FOX.pdf", Nov. 

24, 2010 

Attachment: spreadsheet comparison of AECOM emissions for APS proposal and "EPA BART" to emissions used

by EPA

Page 4 of 4

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presentation of CALPUFF v. 6.4 to FLMs

Paine, Bob 

to: 

Scott Bohning 

12/22/2010 10:30 AM 

Cc: 

Anita Lee, "Kostrova, Olga", C.Mathai, Ann.Becker 

Show Details 

Scott, attached is a copy of the presentation that Joe Scire made on December 10 to the FLMs in 

Lakewood, CO on CALPUFF v. 6.4. The FLMs were pleased to receive this presentation and will be 

working with EPA to “expedite” the review and implementation for this improved version of CALPUFF.

Olga reminded me that we have included some CALPUFF 6.4 modeling runs in addition to the 

CALPUFF version 5.8 modeling runs on the DVD that you received. 

Please let us know if you have any additional questions on the modeling files. Hope you have a 

peaceful and joyous holiday!

Bob

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RE: Questions on FCPP modeling files for APS proposal

Paine, Bob 

to: 

Scott Bohning 

12/23/2010 06:50 AM 

Cc: 

Anita Lee, "Kostrova, Olga", C.Mathai, Ann.Becker 

Show Details 

Scott, to help you interpret the results of our CALPUFF modeling, I am attaching a document that has bar graph 

results and tables of emissions used. The model combinations are CALPUFF v. 5.8 and also v. 6.4 with two sets 

of ammonia background: the IWAQM default 1.0 ppb and also the AECOM values that were used in the 2008

BART analyses.

The five emission cases that we modeled are tabulated, and they include:

Case 1) The baseline emissions that you used in your modeling

Case 2) The proposed EPA BART emissions as published in the Federal Register

Case 3) An alternative baseline case that has no emissions from Units 1-3

Case 4) Case 3 with LNB/OFA installed on Units 4-5

Case 5)Case 2 with Units 1-3 shut down.

You will notice that the relative visibility impact and the effectiveness of the emission cases to improve visibility 

vary considerably depending the choice of the CALPUFF version and the ammonia background assumed.

Bob

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RE:Questions on FCPP modeling files for APS proposal Questions on FCPP modeling files for APS proposal 

Scott Bohning Scott Bohning to: Paine, Bob 12/27/2010 11:05 AM

Cc: Anita Lee, Ann.Becker, C.Mathai, "Kostrova, Olga"

Bob & Olga -

Thank you for those bar charts, and for the previous spreadsheets and explanations. The main point I 

was concerned about, difference between "worst case" and proposed FIP 30-day average limit for NOx, I 

understand now and should have been able to get from what you had already sent.

Sorry if I am being dense , but I still do not see how the EPA proposed PM limits were used in the 

modeling. We may not need to resolve this, since EPA will likely have our own version of the effect of the 

new APS proposal, but if you have other details you might send them.

In summary, the tables in the Word document you just sent are consistent with the emission rates used in 

the AECOM modeling for the EPA proposed BART case, except that there is no PMC emission rate, and it 

is not clear how the FIP PM emission limits (e.g. 0.012 lb/MMBTU for units 1-3) were used to get the 

emission rates used in that table or the modeling. 

FYI, here are some things that I checked.

The heat inputs (MMBTU/hr) and emission rates (lb/hr) in "Shut Down 123 in 2012 (11-29-10).xls" for the 

case "EPA Proposed BART" do not correspond to those used by EPA, nor to those in "FCPP charts and 

emissions_23dec10.doc" or in the actual CALPUFF files, so I don't know what to make of them... I won't 

worry about these in light of later tables supplied in the Word document "FCPP charts and 

emissions_23dec10.doc".

For "FCPP charts and emissions_23dec10.doc" there is a match between the emissions in Table 2 

"Proposed FIP Emissions (from published proposal)" and those used by AECOM in the latest CALPUFF 

modeling for SO2, NOx, PMF, EC, SO4*98/96, and SOA. 

The SO2, NOx, and PM lb/hr and lb/MMBTU are consistent with the proposed FIP limits, and give heat 

inputs consistent with what EPA assumed (units 1-5 in MMBTU/hr: 2349; 2352; 3032; 8000; 8051).

But it is not clear to me how the PM limit or emission rate lb /hr was used to derive the various PM 

components (PMC, PMF etc.) used for the AECOM modeling; I guess that is someplace else.

The table does not include a PMC/PM coarse emission rate, and the PMC rate used in CALPUFF does 

not correspond to (PM minus PM fine), or (PM minus PM fine and EC), or (PM minus everything else).

- Scott B.

-- 

=+=+=+=+=+=+=+=+=+=+=+=+=+=+=

"Scott Bohning" <bohning.scott@epa.gov>

U.S. EPA Region 9, AIR-7

415/947-4127 fax-3579

"Paine, Bob" Scott, to help you interpret the results of our CAL... 12/23/2010 06:50:45 AM

From: "Paine, Bob" <bob.paine@aecom.com>

To: Scott Bohning/R9/USEPA/US@EPA

Cc: Anita Lee/R9/USEPA/US@EPA, "Kostrova, Olga" <olga.kostrova@aecom.com>, 

<C.Mathai@aps.com>, <Ann.Becker@pinnaclewest.com>
Date: 12/23/2010 06:50 AM

Subject: RE: Questions on FCPP modeling files for APS proposal

Scott, to help you interpret the results of our CALPUFF modeling, I am attaching a document that has 

bar graph results and tables of emissions used. The model combinations are CALPUFF v. 5.8 and also v. 

6.4 with two sets of ammonia background: the IWAQM default 1.0 ppb and also the AECOM values that 

were used in the 2008 BART analyses.

The five emission cases that we modeled are tabulated, and they include:

Case 1) The baseline emissions that you used in your modeling

Case 2) The proposed EPA BART emissions as published in the Federal Register

Case 3) An alternative baseline case that has no emissions from Units 1-3

Case 4) Case 3 with LNB/OFA installed on Units 4-5

Case 5)Case 2 with Units 1-3 shut down.

You will notice that the relative visibility impact and the effectiveness of the emission cases to improve 

visibility vary considerably depending the choice of the CALPUFF version and the ammonia background 

assumed.

Bob[attachment "FCPP charts and emissions_23dec10.doc" deleted by Scott Bohning/R9/USEPA/US] 
Questions on FCPP modeling files for APS proposal - updated response

Paine, Bob 

to: 

Scott Bohning 

01/03/2011 07:53 PM 

Cc: 

"Kostrova, Olga", C.Mathai, Ann.Becker, Anita Lee 

Show Details 

Scott, in response to your questions posed on December 27 about the PM emissions that we modeled 

for the Four Corners Power Plant, I have checked with Olga Kostrova, and we have the following 

responses to your questions as well as attached files (Excel and Word) that will help to clarify what we 

modeled. 

Bob

Comments and responses are provided here.

1) Scott Bohning:

In summary, the tables in the Word document you just sent are consistent with the emission rates used 

in the AECOM modeling for the EPA proposed BART case, except that there is no PMC emission rate, 

and it is not clear how the FIP PM emission limits (e.g. 0.012 lb/MMBTU for units 1-3) were used to get 

the emission rates used in that table or the modeling. 

AECOM Response:

We are attaching a clarifying Excel and a Word version of the emissions with PMC emissions included 

as well as details regarding the computation of the emission rates. The Excel file is based upon the file 

you sent us, with the red edits created by EPA’s review and changes to the original BART Excel 

spreadsheet submitted by AECOM with the 2008 BART analysis.

2) Scott Bohning:

FYI, here are some things that I checked. 

The heat inputs (MMBTU/hr) and emission rates (lb/hr) in "Shut Down 123 in 2012 (11-29-10).xls" for 

the case "EPA Proposed BART" do not correspond to those used by EPA, nor to those in "FCPP charts 

and emissions_23dec10.doc" or in the actual CALPUFF files, so I don't know what to make of them... I 

won't worry about these in light of later tables supplied in the Word document "FCPP charts and 

emissions_23dec10.doc". 

AECOM Response:

Please use the updates to the December 23 documents that are attached for comparison to the 

modeling files. The only changes in the attached files from those sent on December 23 are 

clarifications to the PM emissions rates. Note that the emissions used in the modeling correspond to 

those in the Excel spreadsheets that you provided to us, as well as EPA’s BART proposal as found in 

Page 1 of 4

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Table 40 of the Technical Support Document. Also note that the baseline emissions represent peak 

24-hour NOx emissions, while the BART options correspond to 30-day rolling average emission rates. 

Due to the inherently higher emission rate for the peak 24-hour average vs. the 30-day rolling average, 

the modeled visibility improvement will be an overestimate of the actual visibility improvement that 

would be realized if consistent emission averaging times were considered.

3) Scott Bohning:

For "FCPP charts and emissions_23dec10.doc" there is a match between the emissions in Table 2 

"Proposed FIP Emissions (from published proposal)" and those used by AECOM in the latest 

CALPUFF modeling for SO2, NOx, PMF, EC, SO4*98/96, and SOA. 

AECOM Response:

Those values are not changed in the attached information provided, so they will continue to match.

 4) Scott Bohning:

The SO2, NOx, and PM lb/hr and lb/MMBTU are consistent with the proposed FIP limits, and give heat 

inputs consistent with what EPA assumed (units 1-5 in MMBTU/hr: 2349; 2352; 3032; 8000; 8051). 

But it is not clear to me how the PM limit or emission rate lb/hr was used to derive the various PM 

components (PMC, PMF etc.) used for the AECOM modeling; I guess that is someplace else. 

AECOM Response:

The table does not include a PMC/PM coarse emission rate, and the PMC rate used in CALPUFF does 

not correspond to (PM minus PM fine), or (PM minus PM fine and EC), or (PM minus everything else). 

AECOM Response:

The attached documents will address these questions.

Regards,

Bob Paine, CCM, QEP

Technical Director

AECOM Environment

The attached documents will clarify what we used for the PM modeling. Note that:

• For a dry bottom boiler fired with bituminous coal and equipped with a scrubber (Units 

1-3), total filterable PM10 is 71% of filterable PM and fine filterable PM10 is 51% of 

filterable PM based on AP-42, Table 1.1-6.

• For a dry bottom boiler fired with bituminous coal and equipped with a baghouse 

(Units 4-5), total filterable PM10 is 92% of filterable PM and fine filterable PM10 is 53% 

of filterable PM based on AP-42, Table 1.1-6.

5) Scott Bohning:

Page 2 of 4

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D 978.589.3164

mailto:bob.paine@aecom.com">bob.paine@aecom.com

AECOM

2 Technology Park Drive

Westford, MA 01886

T 978.589.3000 F 978.589.3100 

http://www.aecom.com/" title="blocked::http://www.aecom.com/">www.aecom.com

From: Bohning.Scott@epamail.epa.gov [mailto:Bohning.Scott@epamail.epa.gov] 

Sent: Monday, December 27, 2010 2:05 PM 

To: Paine, Bob 

Cc: Lee.Anita@epamail.epa.gov; Ann.Becker@pinnaclewest.com; C.Mathai@aps.com; Kostrova, Olga

Subject: RE: Questions on FCPP modeling files for APS proposal

Bob & Olga - 

Thank you for those bar charts, and for the previous spreadsheets and explanations. The main point I 

was concerned about, difference between "worst case" and proposed FIP 30-day average limit for NOx, 

I understand now and should have been able to get from what you had already sent. 

Sorry if I am being dense , but I still do not see how the EPA proposed PM limits were used in the 

modeling. We may not need to resolve this, since EPA will likely have our own version of the effect of 

the new APS proposal, but if you have other details you might send them. 

In summary, the tables in the Word document you just sent are consistent with the emission rates used 

in the AECOM modeling for the EPA proposed BART case, except that there is no PMC emission rate, 

and it is not clear how the FIP PM emission limits (e.g. 0.012 lb/MMBTU for units 1-3) were used to get 

the emission rates used in that table or the modeling. 

FYI, here are some things that I checked. 

The heat inputs (MMBTU/hr) and emission rates (lb/hr) in "Shut Down 123 in 2012 (11-29-10).xls" for 

the case "EPA Proposed BART" do not correspond to those used by EPA, nor to those in "FCPP charts 

and emissions_23dec10.doc" or in the actual CALPUFF files, so I don't know what to make of them... I 

won't worry about these in light of later tables supplied in the Word document "FCPP charts and 

emissions_23dec10.doc". 

For "FCPP charts and emissions_23dec10.doc" there is a match between the emissions in Table 2 

"Proposed FIP Emissions (from published proposal)" and those used by AECOM in the latest 

CALPUFF modeling for SO2, NOx, PMF, EC, SO4*98/96, and SOA. 

The SO2, NOx, and PM lb/hr and lb/MMBTU are consistent with the proposed FIP limits, and give heat 

inputs consistent with what EPA assumed (units 1-5 in MMBTU/hr: 2349; 2352; 3032; 8000; 8051). 

But it is not clear to me how the PM limit or emission rate lb/hr was used to derive the various PM 

components (PMC, PMF etc.) used for the AECOM modeling; I guess that is someplace else. 

The table does not include a PMC/PM coarse emission rate, and the PMC rate used in CALPUFF does 

not correspond to (PM minus PM fine), or (PM minus PM fine and EC), or (PM minus everything else). 

- Scott B. 

-- 

=+=+=+=+=+=+=+=+=+=+=+=+=+=+= 

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"Scott Bohning" <bohning.scott@epa.gov> 

U.S. EPA Region 9, AIR-7 

415/947-4127 fax-3579

Scott, to help you interpret the results of our CALPUFF modeling, I am attaching a document that has 

bar graph results and tables of emissions used. The model combinations are CALPUFF v. 5.8 and also 

v. 6.4 with two sets of ammonia background: the IWAQM default 1.0 ppb and also the AECOM values 

that were used in the 2008 BART analyses. 

 

The five emission cases that we modeled are tabulated, and they include: 

 

Case 1) The baseline emissions that you used in your modeling 

Case 2) The proposed EPA BART emissions as published in the Federal Register 

Case 3) An alternative baseline case that has no emissions from Units 1-3 

Case 4) Case 3 with LNB/OFA installed on Units 4-5 

Case 5)Case 2 with Units 1-3 shut down. 

 

You will notice that the relative visibility impact and the effectiveness of the emission cases to improve 

visibility vary considerably depending the choice of the CALPUFF version and the ammonia 

background assumed. 

 

Bob[attachment "FCPP charts and emissions_23dec10.doc" deleted by Scott Bohning/R9/USEPA/US] 

From: "Paine, Bob" <bob.paine@aecom.com> 

To: Scott Bohning/R9/USEPA/US@EPA 

Cc: Anita Lee/R9/USEPA/US@EPA, "Kostrova, Olga" <olga.kostrova@aecom.com>, 

<C.Mathai@aps.com>, <Ann.Becker@pinnaclewest.com> 

Date: 12/23/2010 06:50 AM 

Subject: RE: Questions on FCPP modeling files for APS proposal

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