Model Clearinghouse Information Storage and Retrieval System
Record Details

Issue:  

Park City Wind LLC has proposed the construction of a 1232 MW offshore 
electric generation windfarm on the Outer Continental Shelf (OCS) off the 
coast of Massachusetts near Martha’s Vineyard. This project (New England 
Wind Phase 2 or Commonwealth Wind) is the second phase of a proposed 
windfarm project (Park City Wind Phase 1), which is located in the same 
geographic area of the OCS. For the Phase 1 project, Park City Wind LLC 
proposed, justified, and received U.S. Environmental Protection Agency 
(EPA) Region 1 approval for the use of an alternative AERCOARE-AERMOD 
modeling method over the preferred Offshore and Coastal Dispersion (OCD) 
model. For the Phase 2 project, the company is requesting a similar 
compliance demonstration approach using the AERCOARE-AERMOD alternative 
modeling method using the same justification and basis from the Phase 1 
project.

EPA Region 1 is seeking concurrence from the EPAs Model Clearinghouse on 
their proposal to approve the AERCOARE-AERMOD alternative model method for 
the New England Wind Phase 2 windfarm project. EPA Region 1 has conducted a 
thorough review of the Phase 2 modeling protocol and has confirmed that the 
model settings, methodology, and conditions-of-use are identical between 
Phase 1 and Phase 2. Given the similarities in project scope and proximity 
of the two project phases along with the sound technical justification 
already provided for the alternative model in the Phase 1 project, EPA 
Region 1 does not see the need for any additional model evaluation for the 
Phase 2 project.

C/H Response:  

The Model Clearinghouse would like to highlight a few aspects of the 
previous Phase 1 alternative model approval that we feel are germane to our 
concurrence with the Phase 2 project:
    1) Most importantly, the previous Phase 1, Park City Wind project 
       gained approval for the use of the AERCOARE-AERMOD alternative model 
       approach by fully satisfying the five elements of Condition 3 
       (Appendix W, Section 3.2.2(e)) required for alternative model 
       justification and approval (See reference below).
    2) There was additional information and analysis provided by Park City 
       Wind LLC and EPA Region 1 in the Phase 1 alternative model approach 
       that demonstrated the tracer studies used to develop the COARE 
       algorithm are sufficiently representative of the marine environment 
       off the coast of Massachusetts.
    3) Finally, EPA Region 1 provided additional justification in their 
       Phase 1 alternative model technical review and citation of a 
       relevant 2015 EPA peer-reviewed report demonstrating that using 
       meteorological inputs from WRF-MMIF performed similarly to AERCOARE-
       AERMOD modeling using measured data from buoys, in most scenarios. 
       This is particularly important because both the Phase 1 and Phase 2 
       projects are proposing to use WRF-MMIF prognostic data versus buoy 
       observational data as the meteorological input data to the AERCOARE 
       preprocessor. The COARE algorithm was originally developed using 
       offshore buoy data, the use of prognostic data could have introduced 
       unintended and inappropriate biases into its application in a 
       regulatory compliance demonstration. The Model Clearinghouse still 
       agrees with this assessment, notes that it is supported by Agency 
       peer-reviewed research, and finds that it is consistent with 
       Appendix W, Section 8.4.5 (Prognostic Meteorological Data, 
       Discussion and Recommendations).

With these aspects in mind, the Model Clearinghouse concurs with EPA Region 1 
proposed approval of a coupled AERCOARE-AERMOD approach for the compliance 
demonstration analysis required in the New England Wind Phase 2 project 
based on the current Phase 2 modeling protocol and the previous Phase 1 
alternative model justification package provided by Park City Wind LLC and 
the technical review documentation provided by EPA Region 1 for both 
phases.

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 New England Wind, Phase 2 offshore wind power project
        Dated: July 5, 2022
        From:  George Bridgers, Model Clearinghouse Director
                 Air Quality Modeling Group, Air Quality Assessment Division, 
                 Office of Air Quality Planning and Standards
        To:    Jay McAlpine, Regional Air Permit Modeler (on detail)
                 Air Permits, Toxics, and Indoor Programs Branch, Air and Radiation Division
                 EPA Region 1, Boston, Massachusetts
               Lynne Hamjian, Director
                 Air and Radiation Division
                 EPA Region 1, Boston, Massachusetts
                 
Memo:  Concurrence Request for Approval of Alternative Model AERCOARE in 
Conjunction with AERMOD, in Support of Outer Continental Shelf PSD air permitting 
of the New England Wind, Phase 2
        Dated: June 29, 2022
        From:    Jay McAlpine, Regional Air Permit Modeler (on detail)
                 Air Permits, Toxics, and Indoor Programs Branch, Air and Radiation Division
                 EPA Region 1, Boston, Massachusetts
        Thru:  Lynne Hamjian, Director
                 Air and Radiation Division
                 EPA Region 1, Boston, Massachusetts
        To:    George Bridgers, Model Clearinghouse Director
                 Air Quality Modeling Group, Office of Air Quality Planning and Standards

Reference:  AERCOARE-AERMOD Alternative Model Application in Support of Outer Continental 
Shelf PSD Air Permitting - Park City Wind
            MCHISRS Record: 22-I-01
            Dated: January 28, 2022