Permit Air Quality Modeling Guidelines

An air quality modeling demonstration is a key step in the licensing process. As with any licensing effort, great care must be taken to insure that the results are not only as accurate as possible, but also conform to all applicable state and federal modeling requirements.

The information presented here is intended to clearly inform you of what the Maine Department of Environmental Protection - Bureau of Air Quality (MEDEP-BAQ) expects and requires for modeling submittals. It has been our experience that following these recommendations greatly reduces the time, effort and expense of air quality modeling within the State of Maine.

The following pages are provided as guidance to help you through the air quality modeling process:

Modeling Protocol Development
Screening Modeling
Refined Modeling
Increment Modeling
Meteorological Data
Class I AQRV Analyses
Background Data
Presentation of Results
Guidance Documents and Links

Some currently approved models are identified and discussed in this document. Although the intent is for the information to be as complete as possible, this guidance is also meant to be somewhat broad, as modeling methodologies and analyses can greatly vary from one project to the next. It is very important that you work in close consultation with MEDEP-BAQ as you prepare to submit a valid modeling protocol and demonstration.

This guidance does not preclude the use of other USEPA approved models, provided the applicant has all the required data and expertise to execute the models. Furthermore, an applicant may use a non-guideline or site-specific model, provided that the applicant has written approval (on a case-by-case basis) from USEPA Region I and/or MEDEP-BAQ, as appropriate, and meets all specifically defined requirements of that model.

MEDEP-BAQ strongly encourages consultants receive professional training in the use of air quality models prior to performing an air quality demonstration. Although MEDEP-BAQ is available as a resource for project-specific questions, MEDEP-BAQ will not provide training in the use of air quality models.

To better orient yourself with the modeling requirements and methodologies, MEDEP-BAQ urges that you review all modeling requirements set forth by:

USEPA, 40 CFR, Part 51, Appendix W;

Chapters 100, 114, 115, 116 and 140 of the Maine Air Regulations

and guidance/recommendations located on the SCRAM (Support Center for Regulatory Air-quality Modeling) website, as well as the topics discussed in the following pages.

Applicants are strongly encouraged to set up a pre-application meeting with MEDEP-BAQ. During this meeting, the scope of the analysis and site-specific parameters will be established which will improve understanding for all parties involved. Pre-application meetings allow applicants to gain valuable knowledge of the air quality modeling/licensing process. It is important to note that additional meetings can be scheduled with MEDEP-BAQ project engineers and meteorologists at any time during the licensing process.

Experience has demonstrated that when a clear, complete, written modeling protocol is submitted for approval prior to performing the air quality modeling analysis, potential problems are resolved at the beginning of the process, resulting in a cost effective modeling analysis for the applicant. Furthermore, approved modeling protocols become the blueprint of the process for both the applicant and MEDEP-BAQ.

Compliance with the ambient impact requirements is generally shown by using approved air quality models. The modeling process involves a sequence of steps explained in subsequent sections of this guideline. Basically, the steps are as follows:

  1. Schedule a pre-protocol meeting to discuss the scope and details of the project with the MEDEP-BAQ project engineer and meteorologist
  2. Submit the screening and/or refined modeling protocol for MEDEP-BAQ approval. Protocol(s) should include highly detailed descriptions of the source, operating scenario(s), meteorological data, receptor data, screening model results, etc. More detailed requirements are set forth in Chapters 115/140 as well as other sections of this guidance document. Upon submission, MEDEP-BAQ will review the modeling protocol(s). If the protocol(s) sufficiently meets all requirements, it will be approved and the modeling may begin. Otherwise, corrections are to be made until MEDEP-BAQ finds the protocol(s) to be acceptable.
  3. Perform modeling analysis as proposed in the MEDEP-BAQ approved modeling protocol(s).
  4. Present the modeling approach, results and all supporting documentation in a report for MEDEP-BAQ review. MEDEP-BAQ will review the report for accuracy and completeness and make a determination as to the acceptability of the modeling demonstration.

    For additional modeling information and/or questions, please contact:

Kevin J. Ostrowski, Senior Meteorologist
(207) 287-2437
kevin.ostrowski@maine.gov