Model Clearinghouse Information Storage and Retrieval System
Record Details

Issue:

US Wind, Inc. (US Wind) is developing the Maryland Offshore Wind Project, 
an offshore wind energy project in a federal lease area on the Outer 
Continental Shelf (OCS) approximately 18.5 km (10 nautical miles) off the 
coast of Maryland and will include up to 121 wind turbine generators and 4 
offshore substations. The project is projected to have an approximate 
production capacity of 2 gigawatts (GW). US Wind expects that emissions of 
one or more criteria air pollutants would exceed the pollutant specific PSD 
significant emission rates (SER) and, consequently, an air quality 
assessment, including air quality modeling, to determine the potential 
impact of the project emissions on the NAAQS and all applicable PSD 
increment levels will be required.

US Wind has requested to use an alternative model, as provided in Section 
3.2 of the Guideline on Air Quality Models (40 CFR Part 51, Appendix W), to 
conduct its PSD air quality modeling analysis of the Maryland Offshore Wind 
Project’s construction and operation and maintenance (O&M) activities. This 
alternative model request has been routed through the Maryland Department 
of the Environment (MDE), which, as a permit reviewing authority, 
subsequently submitted the request to the U.S. Environmental Protection 
Agency (EPA) Region 3. Specifically, US Wind has requested to use the 
Coupled Ocean-Atmosphere Response Experiment (COARE) bulk flux algorithm, 
as implemented in the AERCOARE meteorological data preprocessor program, to 
prepare meteorological data for use in the American Meteorological 
Society/Environmental Protection Agency Regulatory Model (AERMOD) 
dispersion program in lieu of the preferred Offshore and Coastal Dispersion 
(OCD) model to assess ambient impacts in a marine environment.

EPA Region 3 has conducted a thorough review of US Wind’s request and has 
found the proposed application of the alternative model to be satisfactory 
and addresses the requirements of the Guideline, Section 3.2.2(b), 
Condition (3), including the subsequent five elements contained in 
Section 3.2.2(e). As such, pursuant to the Guideline, Sections 3.0(b) and 
3.2.2(a), Region 3 currently intends to approve the use of proposed coupled 
AERCOARE-AERMOD alternative model approach for the Maryland Offshore Wind 
Project air permit application.

C/H Response:

The Model Clearinghouse concurs with EPA Region 3’s proposed approval of a 
coupled AERCOARE-AERMOD alternative modeling approach for the air quality 
modeling analysis required in the Maryland Offshore Wind Project based on 
the alternative model request package provided by US Wind and MDE and the 
review documentation in the alternative model concurrence request 
memorandum provided by EPA Region 3. The Model Clearinghouse encourages EPA 
Region 3 to respond to US Wind, MDE, and to the docket for federal 
permitting actions related to the Maryland Offshore Wind Project with a 
letter of alternative model approval, as appropriate. The information 
associated with the EPA Region 3 alternative model approval and the Model 
Clearinghouse concurrence should be available for comment during the 
appropriate public comment period(s).

Given the possible importance of platform downwash and shoreline 
fumigation, the Model Clearinghouse continues to recommend caution and 
careful review before additional alternative model considerations of the 
coupled AERCOARE-AERMOD model methodology in other projects. This case-
specific Model Clearinghouse concurrence does not constitute a generic 
approval of a coupled AERCOARE-AERMOD approach for other applications 
elsewhere. However, the scope of the technical assessment submitted here 
and with similar AERCOARE-AERMOD alternative model requests continue to 
provide a good basis for such considerations.

Memo:  Model Clearinghouse review of an alternative model application of AERCOARE 
in conjunction with AERMOD in Support of Outer Continental Shelf PSD air 
permitting of the US Wind Maryland Offshore Project
        Dated: September 11, 2023
        From:  George Bridgers, Model Clearinghouse Director
                 Air Quality Modeling Group, Air Quality Assessment Division, 
                 Office of Air Quality Planning and Standards
        To:    Timothy A. Leon Guerrero, Meteorologist
                 Air Quality Analysis Branch, Air & Radiation Division
                 EPA Region 3, Philadelphia, PA
        Thru:  Alice Chow, Branch Chief
                 Air Quality Analysis Branch, Air & Radiation Division
                 EPA Region 3, Philadelphia, PA
                 
Memo:  Model Clearinghouse review of an alternative model application of AERCOARE 
in conjunction with AERMOD in Support of Outer Continental Shelf PSD air 
permitting of the US Wind Maryland Offshore Wind Project
        Dated: August 17, 2023
        From:  Timothy A. Leon Guerrero, Meteorologist
                 Air Quality Analysis Branch, Air & Radiation Division
                 EPA Region 3, Philadelphia, PA
        Thru:  Alice Chow, Branch Chief
                 Air Quality Analysis Branch, Air & Radiation Division
                 EPA Region 3, Philadelphia, PA
        To:    George Bridgers, Director of Model Clearinghouse
                 Air Quality Modeling Group, Air Quality Assessment 
                 Division,
                 Office of Air Quality Planning and Standards

Memo:  Justification for the use of an alternative model to evaluate how air 
emissions associated with US Wind’s planned Maryland offshore wind project 
are dispersed over water
        Dated: July 19, 2023