AECOM Environment (805)388-3775 tel 1220 Avenida Acaso (805)388-3577 fax Camarillo, CA 93012

July 21, 2010

Mr. Gerardo Rios Chief, Permits Office (AIR 3) U.S. Environmental Protection Agency 75 Hawthorne Street San Francisco, CA 94105

RE: Palmdale Hybrid Power Project (PHPP) – Supplemental Information for the Application for PSD Permit

Dear Mr. Rios:

AECOM Environment, on behalf of the City of Pa lmdale and Inland Energy, Inc., is submitting the enclosed Supplemental Info rmation on the application for a Prevention of Significant Deterioration (PSD) permit for the Palmdale Hy brid Power Project (PHPP). The PHPP is a hybrid power plant consisting of combined-cycle power plant integrated with 50 megawatts (MW) of solar arrays for a combined nominal output of 570 MW. The PSD application for PHPP was submitted to EPA on April 1, 2009. This supplemental information is being provided in response to a conference call held between EPA Region 9 staff, Inland Energy, Latham & Watkins, and AECOM on March 14, 2010. EPA indicated that the PHPP PSD Application would be complete if the following items were addressed:

1. An expanded cumulative fine particulate matter (PM2.5) impact analysis to demonstrate compliance with the National Ambient Air Quality Standard (NAAQS). The EPA also requested additional analysis regarding the potential applicability of PM2.5 increment thresholds proposed in the Federal Register on September 21, 2007;

2. A 1-hour Nitrogen Dioxide (NO 2 ) NAAQS modeling analysis;

3. An expanded Soils and Vegetation analysis based on the Environmental Appeals Board

case In re: Indeck-Elwood, LLC ; PSD Appeal No. 03-04; PSD Permit No. 197035AAJ (decided September 27, 2006) ;

4. A Visibility analysis at local sensitive state or federal Class II areas;

5. Additional justification/documentation that the receptor grids used in the PSD modeling analysis out to 20 kilometers (km) are su fficient to identify the maximum impacts; and

6. A more detailed growth analysis than was submitted with the PSD application.AECOM

OC\1073055.1 2

In addition to the above items, the EPA r equested the following it em, that was not a “completeness” item, but wh ich would expedite the issuance of the permit:

7. Additional detail regarding the Best Available Control Technology (BACT) analysis

Enclosed please find three copi es of the PSD Applicati on Supplement. Since these supplemental materials do not change our Class I area analyses, we have not provided a copy to the National Park Service or the U.S. Forest Service.

We request that EPA review the supplemental information in a timely manner and move forward with processing the PSD permit application. Please let me know (by phone 805-388-3775 or email sara.head@aecom.com) if you or your sta ff have questions or need further supplemental information.

Sincerely

Sara J. Head, QEP Vice President, AECOM Environment Sara.head@aecom.com

Attachments: PSD Application Supplemental Inform ation (3 copies) DVD with modeling files (3 copies)

cc: Ms. Shirley Rivera, EPA Ms. Felicia Miller, California Energy Commi ssion (with 1 copy of the attachments) Mr. Alan De Salvio, Antelope Valley Air Quality Management District Ms. Laurie Lile, Assistant City Manager, Palmdale Mr. Tom Barnett, Inland Energy, Inc. Mr. Tony Penna, Inland Energy, Inc. Mr. Mike Carroll, Latham & Watkins