1

Chang, Andy

From: Mathias, Scott

Sent: Wednesday, January 20, 2016 9:27 AM

To: Chang, Andy

Subject: FW: SO2 air dispersion modeling: H.A. Wagner (Maryland)

Attachments: Sierra Club comments and Sears Analysis, EPA-HQ-OAR-2015-0310.pdf; 2014 01 16 

Draft COMAR 26.11.39 - SO2.pdf

Scott Mathias | Associate Director, Air Quality Policy Division | U.S. EPA, RTP, NC 27711 | 919.541.5310 

From: Joshua Berman [mailto:josh.berman@sierraclub.org] 

Sent: Wednesday, January 20, 2016 8:42 AM 

To: Mathias, Scott <Mathias.Scott@epa.gov> 

Cc: Jones, Rhea <Jones.Rhea@epa.gov>; Zachary Fabish <zachary.fabish@sierraclub.org> 

Subject: Re: SO2 air dispersion modeling: H.A. Wagner (Maryland) 

Thanks for your note, Scott. It appears that the AECOM SO2 Characterization Modeling Analysis for the H.A. Wagner and 

Brandon Shores Power Plants in Baltimore, Maryland was posted yesterday afternoon on your website (and, as you noted, lacks any 

explanatory documentation). I presume that this report was submitted by the State of Maryland in furtherance of its requested attainment 

designation. However, for at least two major reasons and a number of subsidiary reasons, this report does not support an attainment 

designation for the area surrounding the H.A. Wagner and Brandon Shores facilities.

 

First, contrary to EPA’s modeling protocols, the AECOM modeling utilizes neither actual historical emission data nor enforceable maximum 

SO2 emissions. Rather, AECOM’s modeling is based on adjustments to historical emission data that lack any identified legal or regulatory 

basis. Specifically, for Wagner Unit 2 AECOM adjusts downward historical SO2 emissions greater than 1,500 lb/hr because, AECOM states, 

Wagner Unit 2 is currently burning lower sulfur Colorado coal and actual emissions using this coal based on the five months of data AECOM 

provided are at or below 1,500 lb/hr. AECOM assumes, without any identified support, that the plant will “continue burning this or similar 

coal in Wagner Unit 2 in order to meet MATS” and that, as a result, Wagner Unit 2’s emissions will remain below 1,500 lb/hr indefinitely 

(AECOM Rpt. at 3-2). This approach is deeply flawed. AECOM cites no permit or SIP condition that enforceably limits Wagner Unit 2’s 

emissions to 1,500 lb/hr. Moreover, MATS cannot supply this missing limit because it does not impose 1-hour emission limits on facilities 

that elect to rely on SO2 emissions as a proxy for acid gas emissions. Absent an enforceable 1-hour limit on Wagner Unit 2’s SO2 emissions, 

there is no basis for adjusting the unit’s historical operations. This adjustment is especially concerning because AECOM's modeling projects 

near-violations of the NAAQS at the controlling receptor (186.0 vs. 196.2 ug/m3), driven overwhelmingly by emissions from the Wagner 

facility. Even if Wagner 2 burned "similar coal" to the current Colorado coal in the future, even a slight increase in the sulfur content of the 

coal (which will dictate the SO2 emissions from Wagner 2 given the lack of installed emission controls for SO2 on that unit) would push 

AECOM's modeled results above the NAAQS. Moreover, as previously provided by the Sierra Club, time series modeling using actual 

historical emission data identifies significant violations of the 2010 1-hour SO2 NAAQS. Absent enforceable 1-hour SO2 emission limits 

that eliminate those violations, AECOM's modeling simply provides no basis to avoid a nonattainment designation. 

 

Second, AECOM conducted its modeling exclusively using the ADJ_U* and LOWWIND3 options in AERMET and AERMOD even though 

EPA has not formally approved the use of these options as the regulatory default under Appendix W and no demonstration has been provided 

regarding their appropriateness in this instance. Although AECOM devotes three appendices to an attempt to establish the validity of 

ADJ_U* and LOWWIND3 (Appendices B-D), these appendices fail to support the preferability of the ADJ_U* and LOWWIND3 nondefault options for modeling the Baltimore-area coal plants, especially for determining whether the area is attaining the 1-hour SO2 

NAAQS. AECOM’s own paper (Appendix C) indicates that “[t]he AERMOD low wind speed options have a minor effect for flat terrain 

locations,” such as those present around the coastal Wagner and Brandon Shores facilities. (AECOM Appendix C, Paine et al., J. Air & 

Waste Mgmt. Ass’n 65 (2015) 1341-53, 1352). Consequently, it is unclear why AECOM even thinks it would be necessary to use these 

modules here. Moreover, AECOM’s Appendix C paper and accompanying reanalysis in Appendix D rely on data from only 4 or 5 SO2 

monitors. But as set forth in the attached comments of Camille Sears, AERMOD’s demonstrated predictive accuracy is in determining the 
2

robust highest concentration (RHC) associated with an emission source or set of sources, not in identifying the exact location of these 

impacts. With the extremely limited monitor dataset available to AECOM in North Dakota and Indiana, it is simply not possible to evaluate 

whether the ADJ_U* and LOWWIND3 options more accurately predict RHC than the current AERMET and AERMOD defaults. As the 

attached comments from Camille Sears demonstrate, “[i]n many modeling applications, version 15181 AERMET ADJ_U* and AERMOD 

LOWWIND3 non-default options will likely degrade performance compared to current regulatory default versions.” (Sears Comments at 

10.) Given that it is the RHC, not the model’s predictive ability at a specific monitor location, that is critical to evaluating attainment with the 

NAAQS, AECOM has not provided a sufficient justification for deviating from the Appendix W defaults. As Appendix W, Section 3.2.2 

requires, in order to use a non-default, AECOM must show that the alternate model “can be demonstrate to be applicable to the problem on a 

theoretical basis.” However, AECOM has not identified a problem specific to the Maryland plants that use of ADJ_U* and LOWWIND3 

would purportedly solve. And, as noted above, given that the value of interest is the RHC, not AERMOD’s predictive capability at a specific 

monitor location, AECOM has failed to establish even a theoretical basis for use of ADJ_U* and LOWWIND3 in this instance. As Ms. 

Sears’ analysis of these non-default options shows, they tend to underpredict RHC. Given that AECOM’s modeled impacts closely approach 

the 1-hour SO2 NAAQS, failure to use the default modules in AERMET and AERMOD alone could readily account for the modeled 

attainment rather than nonattainment (even setting aside the deeply flawed modeled emission rates discussed above). AECOM’s exclusive 

reliance on ADJ_U* and LOWWIND3 fails to support an attainment or unclassifiable designation. 

Ultimately, AECOM appears to have elected inputs and modeling options in order to decrease modeled impacts--replacing actual historical 

emissions data with synthesized, hypothetical low-sulfur coal emissions, removing entirely startup and shutdown emissions, adopting a low 

background emissions concentration, using non-regulatory default modeling options without any clear justification, using a small, sparse 

receptor grid, among others--yet nonetheless AECOM's modeling yields peak concentrations just a few percentage points below the 

NAAQS. Far from disputing the modeling submitted by Sierra Club and the state of Maryland indicating that NAAQS exceedences can only 

be avoided through adoption of enforceable 1-hour emission limits identified in the attached draft regulation, AECOM's modeling goes a long 

ways towards confirming the presence of those problems and the need for additional 1-hour enforceable limitations on SO2 emissions from 

the Wagner facility. 

Sincerely, 

Josh 

On Wed, Jan 20, 2016 at 8:14 AM, Mathias, Scott <Mathias.Scott@epa.gov> wrote: 

Josh,

I received your inquiry regarding posting material to EPA’s SO2 designations website. Our convention has 

been to post to the website the official state correspondence of modified recommendations, but not 

necessarily all correspondence related to a designation action. When we receive new material our Regional 

office will take the time necessary to review any correspondence to determine its relevance, and if it

conforms to our convention we will post it to the website. Otherwise, all relevant documentation supporting 

EPA’s actions will be deposited in the official public docket at the time we notify states of our intended 

designations (i.e., the 120-day letters). We are scheduled to complete that milestone very soon, so any 

relevant material not posted to the website will be available in the public docket shortly.

Scott Mathias | Associate Director, Air Quality Policy Division | U.S. EPA, RTP, NC 27711 | 919.541.5310
3

From: Joshua Berman [mailto:josh.berman@sierraclub.org] 

Sent: Friday, January 15, 2016 4:26 PM 

To: Mathias, Scott <Mathias.Scott@epa.gov> 

Cc: Jones, Rhea <Jones.Rhea@epa.gov>; Zachary Fabish <zachary.fabish@sierraclub.org> 

Subject: Re: SO2 air dispersion modeling: H.A. Wagner (Maryland)

 

Ms. Jones and Mr. Mathias: 

 

It appears that the State Designations website, as of now, has not been updated with any additional submissions 

from Maryland. If Maryland did provide EPA with an identification of federally enforceable emissions limits 

or permit conditions that it believes may be needed to support its requested attainment demonstration (which it 

indicated it would provide by today), I would appreciate if you could post these on the website and/or send me 

a copy. 

 

Thank you, and I hope you have a good weekend, 

Josh 

 

On Tue, Jan 12, 2016 at 8:36 PM, Joshua Berman <josh.berman@sierraclub.org> wrote: 

Dear Ms. Jones and Mr. Mathias:

As a follow-up to the time series modeling that I provided last week, I wanted to briefly address a couple of points in Maryland’s 

November 20, 2015 SO2 designation submission. 

First, contrary to the State’s suggestion, the ambient monitor data collected during a two-month period in 2013 if anything supports a 

nonattainment designation—not an attainment designation—for the area around the Wagner and Brandon Shores facilities. Notably, this is 

the only reported ambient monitor data that was collected in any proximity to the Wagner and Brandon Shores facilities. Given its limited 

two-month duration, the occurrence of a maximum 1-hour SO2 concentration of 101.7 ppb at the monitor closest to those plants during 

that time, and the fact that the monitoring was conducted during the summer months even though Wagner Unit 2 has been operating at far 

higher capacity factors in winter than summer months in recent years (and Unit 3’s operations show no seasonal bias), even a basic 

extrapolation the monitored results produces a 99th percentile 1-hour maximum far in excess of the 75 ppb standard.

Second, in Attachment 6, the State indicates that on January 15, 2016 it will “identif[y] federally enforceable emissions limits or permit 

conditions that may be needed to support the attainment designation.” Unless those limitations have been fully reviewed and vetted by 

EPA to ensure they adequately maintain the SO2 NAAQS and are already embodied in federally enforceable permits or regulations, EPA 

cannot rely on the State’s unenforceable promise of potential future action as a basis for declining to propose a nonattainment designation 

at this time. I also wanted to draw your attention to SO2 modeling that MDE previously completed for these plants and modelinginformed SO2 emission limits that MDE previously shared with stakeholders in early 2014. I have attached MDE's presentation to 
4

stakeholders from February 2014 in which MDE summarizes the results of its modeling (as well as Sierra Club's prior modeling) and 

explains the unit-specific emission rates necessary to ensure compliance with the 1-hour SO2 NAAQS. Shortly before that stakeholder 

meeting, MDE released to stakeholders a draft SO2 regulation (attached) that includes modeling-informed unit- or plant-specific emission 

rates. EPA should review with special care any newly proposed emission limitations that differ meaningfully from those identified by 

Maryland as requisite to maintain the NAAQS in 2014. 

Finally, the State indicates that it will be submitting “further emissions and modeling analyses and information” in “early 2016.” To date, 

EPA has not posted any additional submissions on its State Designations webpage. If EPA has or receives any additional submissions 

from Maryland, I would appreciate if you could post those on the website and/or provide a copy to me. 

Thank you,

Josh

 

On Tue, Jan 5, 2016 at 10:47 AM, Mathias, Scott <Mathias.Scott@epa.gov> wrote: 

Mr. Berman,

On behalf of Ms. Jones, I’m acknowledging that we have received your email and its attachments pertaining 

to the power plants located in the Baltimore area.

Scott Mathias | Associate Director, Air Quality Policy Division | U.S. EPA, RTP, NC 27711 | 919.541.5310

From: Joshua Berman [mailto:josh.berman@sierraclub.org] 

Sent: Monday, January 04, 2016 4:19 PM 

To: Mathias, Scott <Mathias.Scott@epa.gov>; Jones, Rhea <Jones.Rhea@epa.gov> 

Cc: Fernandez, Cristina <Fernandez.Cristina@epa.gov>; Esher, Diana <Esher.Diana@epa.gov>; George Aburn -MDE- 

<george.aburn@maryland.gov>; Zachary Fabish <zachary.fabish@sierraclub.org> 

Subject: SO2 air dispersion modeling: H.A. Wagner (Maryland)

 

Ms. Jones and Mr. Mathias: 

 

Per the attached cover letter, please find enclosed time series and steady-state sulfur dioxide air dispersion 

modeling for the H.A. Wagner, C.P. Crane, and Brandon Shores power plants located in the Baltimore area 

in Maryland. This modeling was previously provided as an attachment to a June 18, 2015 letter to the 

Maryland Department of the Environment, and is provided here again as an attachment along with the 
5

original June 18th letter. CDs with the input and output files are being sent via FedEx and copied to the 

other recipients on this email. 

 

If you have any questions, please let me know. 

 

Thank you, 

Josh 

 

-- 

Joshua Berman 

Staff Attorney 

Sierra Club Environmental Law Program 

50 F St. NW, 8th Floor 

Washington, DC 20001 

Tel: (202) 650-6062

Fax: (202) 547-6009

 

-- 

Joshua Berman 

Staff Attorney 

Sierra Club Environmental Law Program 

50 F St. NW, 8th Floor 

Washington, DC 20001 

Tel: (202) 650-6062

Fax: (202) 547-6009
6

 

-- 

Joshua Berman 

Staff Attorney 

Sierra Club Environmental Law Program 

50 F St. NW, 8th Floor 

Washington, DC 20001 

Tel: (202) 650-6062

Fax: (202) 547-6009

-- 

Joshua Berman 

Staff Attorney 

Sierra Club Environmental Law Program 

50 F St. NW, 8th Floor 

Washington, DC 20001 

Tel: (202) 650-6062 

Fax: (202) 547-6009