EPA Ambient Air Monitor Values Reports

Find summary reports for ambient air monitoring stations here:

Monitor Values Report AirData US EPA

VOC/NOx Screening for Ozone Standards

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The Scheffe memo has been used as a screening method to demonstrate compliance with ozone standards based on a facility's VOC and NOx PTEs. The first link below is a poor-quality scanned version of the memo with "draft" stamped on several pages. The second link is from a Nevada web site; it's cleaner and doesn't have the draft markings, but it cautions that it's a recreation of the original and they don't guarantee its accuracy.

Scanned original (marked "draft")

Cleaned version on Nevada web site

Here's a table and chart based on the Scheffe method that was used for permitting a previous incarnation of the Montana Advanced Biofuels project (stored in project folder ACT203382).
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State & Local Modeling Guidelines

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Minnesota PCA. 10/2004.
MPCA modeling page. See especially modeling protocol forms and spreadsheet. (Page contains link to above guidance, but link didn't work when access attempted 8/11.)

San Joaquin Valley. Lots of useful guidance and data, especially regarding NOx modeling.

Iowa DNR. Lots of good stuff including:

• 20D "Screening Threshold Method for PSD Modeling; North Carolina Air Quality Section." Screening method for selecting nearby sources to include in a cumulative impacts analysis.
• Source Characterization Guidance and Tools. These include spreadsheets for calculating flare parameters and building volume source parameters. Documents provide guidelines on modeling haul roads, storage piles, storage tanks, truck and rail loadouts, and other specific types of sources.
• They also include guidance on the ambient ratio method for modeling annual average NO2 NAAQS compliance. But it hasn't been updated with any new information for modling 1-hour average compliance.
• They have a PSD modeling protocol template, but it's only a couple of pages and isn't nearly as extensive as we would need.
• VISCREEN tool.
• A spreadsheet that calculates shortest distance from a Class I area.

North Carolina DENR, Division of Air Quality. Includes quarry modeling and air toxics modeling guidance. PSD modeling guidance provides the 20D rule for selecting nearby sources outside of the SIA.

Texas Commission on Enironmental Quality (TCEQ). As of today (8/19/11), modeling guidelines not posted but in work. Includes draft checklist and e-mail discussion group.

Arizona DEQ modeling guidance. This page links to a 2004 guidance document and includes a March 2011 update memo. The memo mostly adds AERMOD as the prefered short-range model and clarifies air toxics modeling requirements. The page also includes links to some EPA resources such as the RBLC, the applicability determination index, and two policy databases.

Bay Area Air Quality Management District (BAAQMD). June 2007. Mostly outlines requirements; not much by way of practical guidance.

New Mexico Environment Department Dispersion Modeling and Emissions Inventory Section. Extensive guidance, updated April 2010. Noticed it says the following about modeling wind erosion from piles: "Wind erosion of storage piles should not be modeled, as it says in AP42 not to use the equations for wind erosion in a steady state model." Site includes links to other resources.

South Carolina Dept. of Health and Environmental Control. 2001

Michigan DEQ. Last revised September 2009.

Ohio EPA. 2003. Q&A format. Not a lot here.

Haul Road Emissions Modeling. Last updated June 2004. According to this presentation at the May 2010 Modeler's Workshop in Portland, OR, the Haul Road Work Group is working to update its recommendations with a report due out early 2011. (This EPA R5 presentation says a report should be issued by fall 2011. I found nothing on the internet as of 11/7/11.)

Albuquerque Modeling Guidance. Includes road dust emissions guidelines, including this introductory discussion:

"Careful examination of AP-42 for both Paved and Unpaved Roads shows the science of haul road modeling is dubious in nature. Furthermore, the WRAP Fugitive Dust handbook published  November  2004  shows  paving  of  haul  roads  and  keeping  those  roads  clean results in nearly 100  percent control of PM10 emissions. Modeling of paved haul roads will not be required if the applicant is willing to implement reasonably available control measures as specified below or if the applicant implements a department approved best management practices plan."

Modeling Presentations from 2011 R/S/L Modelers Workshop

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Here's a link to the main page that contains links to the individual presentations.

One thing I found interesting, and potentially useful, was a San Joaquin Valley APCD web page with expanded NO2 modeling guidance and data. For example, they've collected and reported NO2/NOx ratios from a variety of source types. The range of values is surprisingly large.

(Note: Joe attended the single day of this conference that was opened to the public.)
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Modeling Fugitive Particulate from Surface Coal Mines

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The 1990 Clean Air Act Amendments included Section 234, inserted by then-Wyoming Senator Alan Simpson, requiring EPA to "analyze the accuracy" of modeling analyses designed to predict impacts to short-term particulate NAAQS from surface coal mine fugitive emissions. The section also requires EPA to "make revisions as may be necessary to eliminate any significant over-prediction of air quality effect of fugitive particulate emissions from such sources." It provides that, until EPA complies, "the State may use alternative empirical based modeling approaches pursuant to guidelines issued by the Administrator." In May 2011, McVehil-Monnett Associates released this draft white paper assessing EPA's compliance with the requirement (which included a 3-year deadline) and the current state of fugitive particulate modeling.

This statement in a 1996 memo from EPA to Senator Simpson appears to be the final word on the matter:

"Since the model still appears to overpredict the impacts of surface coal mines, the Agency does not plan to use it for regulatory applications involving these sources. As a consequence, the regulatory procedures currently in place will remain in effect. These procedures are contained in the January 24, 1994 Memorandum of Agreement (MOA) between EPA Region VIII and the State (copy enclosed) and were summarized in the Federal Register on September 12, 1995 (60 FR 47290). The MOA allows the State to conduct monitoring in lieu of short term modeling for assessing coal mining-related impacts in the Powder River Basin. We believe that these procedures provide adequate protection for the environment and are also acceptable to the stakeholders. At this time, we and the various stakeholders believe that the interim procedures work well, and therefore we do not currently plan any further analyses. If in the future EPA is able to correct the model’s tendency to overpredict as described above, it may, of course, review these regulatory procedures."

The author also points out that the Wyoming Supreme Court issued a ruling in March of this year stating, in part, that EPA still has not remedied the situation addressed by the Simpson amendment.

Wyoming has a specific Memorandum of Agreement with EPA regarding modeling (or not) of surface coal mine fugitive PM. Their agreement relies heavily on an approved monitoring network and valid data and on requiring Best Available Work Practices (BAWPs). They also had to work through PSD increment issues, although it appears that the rather creative fixes no longer apply and any further work to address the issue is at a standstill.
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Annotated Appendix W Modeling Guideline

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I've started annotating, bookmarking, and linking this copy of the current Guideline on Air Quality Models (Appendix W, 2005). I used Foxit, which has some very nice annotation features. I think you can view the mark-ups and notes and use the bookmarks and links when reading with Adobe, but you may want to download Foxit (the basic version is free) if you're going to be adding to the annotations--which I would highly encourage if you're studying the document for something in particular.

(Unfortunately, clicking the link here or where the document is stored in the Bison SharePoint site only opens the document within the browser. This seems to provide limited Foxit annotation functionality. You may have to download a copy of the document, save the revised version to your computer with the same name, and re-upload to SharePoint--overwriting the existing version.)
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North Dakota Modeling Policy for Compressor Engines & Glycol Dehy Units

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Clarifies "when dispersion modeling is required for be submitted for facilities which include compressor engine(s) and/or glycol dehydration unit(s) as the primary source(s) of emissions." Applies to criteria and air toxics emissions. Also provides "procedure to follow when "further review" of emissions is required..."

May 16, 2011 NDDH Memo
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Anemometer Height Data

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WebMet has anemometer hight information, but it's not always current.

This NRCS site includes a spreadsheet with anemometer height for weather stations throughout the country. I don't know how frequently it's updated, however. The author of the NRCS wind rose site pointed me here for weather station data collections. The NWS station history files (zipped and unzipped) seem to be the appropriate sources for anemometer height histories, but the links don't work. This is the ftp site where the files are supposed to reside, but they don't. Some of the other posted files may have relevent information, but I've not found the right one or ones yet.

I was looking specifically for the current anemometer height at the Great Falls Airport. I ended up calling the NWS office in Great Falls. They said it's an ASOS station and all of them (or most all?) use 10 m towers. The person I talked to was unaware of any published information with current NWS station anemometer heights.
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Modeling Inputs & Procedures Spreadsheet

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Please use this spreadsheet to capture all pertinent information regarding a model's inputs, file names, data sources, assumptions, etc. The spreadsheet is intended to act as a checklist of items to consider while conducting the analysis and a record to facilitate second-party review and report preparation. It also includes some template tables for reporting results in a format that can be pasted into a report. As you're using the spreadsheet, and as we receive responses to submitted models from regulatory agencies, please consider how we might improve on it or develp a more effective and/or efficient tool to accomplish the same objectives.
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EPA Officially Announces AerScreen Preferred Screening Model

AerScreen EPA Memo

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October 2010 Biomass Modeling Report from RTP

This is a useful report that, among other things, provides data for in-stack ratios of NO/NO2 from wood combustion. Diane Lorenzen provided it to MDEQ to support assumptions she made in the UM boiler modeling.

Biomass Modeling Report
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Updated NO2/SO2 1-hr modeling guidance

EPA released additional guidance for modeling 1-hour NO2 NAAQS compliance 3/1/2011. It updates OLM and PVMRM policy, addresses significant contribution analyses using the SILs, and discusses how to perform cumulative analyses including the option of incorporating temporally-varying background concentrations.

It also "[r]ecommends that compliance demonstrations for the 1-hour NO2 NAAQS address emission scenarios that can logically be assumed to be relatively continuous or which occur frequently enough to contribute significantly to the annual distribution of daily maximum 1-hour concentrations based on existing modeling guidelines, which provide sufficient discretion for reviewing authorities to not include intermittent emissions from emergency generators or startup/shutdown operations from compliance demonstrations for the 1-hour NO2 standard under appropriate circumstances."

3/1/2011 Policy Memo

See this blog post for access to previous memos.

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See this article for a helpful discussion of the state of SO2 and NO2 1-hr NAAQS modeling guidance, including April updates to AERMOD and AERMET. It also talks about recent EPA guidance to states for 1-hr SO2 NAAQS attainment designation.
(added 5/20/2011, KMM)
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Revised FLAG Document

Document, published October 2010:
Federal Land Managers’ Air Quality Related Values Work Group (FLAG)Phase I Report—Revised (2010)

Trinity summary article:
Trinity Consultants - New FLAG Guidance for Class I Area Modeling

Recommendations for Modeling PM2.5

NACAA PM2.5 Modeling Methodology Recommendations

Updated FLAG Document

Click on title to go to a National Park Service page with a link to the October 2010 updated FLAG document.

MDEQ Modeling Guidance

1998 Policy Memo -- When Modeling is Required

Draft 2007 Modeling Guideline Document
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SO2 Modeling Guidance

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Although this guidance offers a "first tier" approach of using the "overall highest hourly background SO2 concentration from a representative monitor" (emphasis added), it goes on to seemingly stress the appropriateness of applying professional judgment when characterizing background by modeling nearby sources and by using monitoring data. It even goes so far as to suggest that you don't necessarily have to follow the modeling guidance in the 1980 Draft NSR Workshop Manual.

EPA SO2 Modeling Policy Memo, August 2010

I noticed, too, that Appendix W seems to encourage efforts to avoid double counting through use of modeling and monitored data. This link accesses a copy of the current version of Appendix W:

EPA SCRAM site with link to Appendix W

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Flare Guidance (Modeling, Emissions, etc)

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Flare Modeling Guidance from NDDH

Iowa DNR guidance and spreadsheet tool -- links on this page

Texas Natural Resources Conservation Commission


(updated post 8/19/2011, KMM)
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New NO2 Air Standards Prove Technically Challenging

This article from Trinity Consultants refers to June 28, 2010 modeling guidance from EPA (link below) that doesn't actually provide much guidance, but it does suggest an interim SIL. It also reports a SIL that NESCAUM states are using. The article discusses methods for estimating NO/NO2 ratios.

Trinity Consultants - New NO2 Air Standards Prove Technically Challenging

EPA NO2 Modeling Guidance 6/2010

2010 State/Local Modelers Workshop

Presentations from the:

EPA Regional State/Local Modelers Workshop