AIR PERMITS OFFICE 

Shirley F. Rivera

INTERNAL DELIBERATIVE

DATE: March 31, 2008

TO: Sierra Research/ Eric Walther

Avenal Power Center, LLC/ Jim Rexroad

CC: U.S. EPA, Region 9/ Katherine Hoag

PSD File: #08-SJ-01

SUBJECT: Avenal Energy Project #08-SJ-01

Batch No. 1 – Request for Clarification

As a follow-up to the completeness determination letter dated March 19, 2008 and addressed to Mr. Stuart

Zisman of Avenal Power Center, LLC, the following presents a request for additional clarification of 

information presented for the Avenal Energy Project (AEP) PSD permit application.

SUMMARY: Below is a general checklist of the topics presented in this additional clarification request.

Details for each are presented in the “Discussion” section of this summary

√? Item Topic General Description

AEP-1 Project Description Equipment description

AEP-2 BACT for CO Emissions 4.0 ppmv vs. 2.0 ppmv @ 15% O2, dry

AEP-3 Soils and Vegetation Analysis Use of EPA December 1980 screening procedures

AEP-4 Visibility Impairment Analysis Use of EPA October 1992 guidance document

AEP-5 Endangered Species Act Awaiting information from Avenal

Batch 2 to be forwarded within approximately 2 weeks will include, at a minimum, clarification requests

regarding: the BACT evaluation, emission estimates, and worst-case emission assumptions and operating

scenarios used for modeling. Additionally, we will provide potential compliance requirements

information (e.g., emission limit averaging periods, performance test methods, etc.).

DISCUSSION

AEP-1. Project Description – On March 26, Avenal provided copies of application forms submitted

to the San Joaquin Valley APCD; we understand this information is intended to clarify the 

project description information in the application. As part of our PSD permit, we intend to

include descriptions (e.g., capacity, fuel fired) for PSD-affected equipment.

Heat rate values: Please confirm whether MMBtu/hr values, where otherwise not

specified, are based on HHV.

MW values: Please indicate MW values as gross, net, and/or nominal based on whatever

reference.

kW and hp ratings: We will indicate both ratings for the natural gas and diesel engines.

AEP-2. BACT for CO Emissions – We are aware that other comparably-sized combined-cycle 

projects have proposed a 2.0 ppmvd @ 15% O2 CO emission rate. Therefore, please provide 

justification for the proposed CO BACT level of 4.0 ppmvd @ 15% O2.

AEP-3. Soils and Vegetation Analysis – Avenal provided clarification, in its March 13 response to

EPA’s initial observations, that the additional impacts analysis for soils and vegetation are

presented in the following sections of the AFC:
Avenal Energy Project #08-SJ-01

Batch No. 1 – Request for Clarification

Page 2

AIR-3

0331EPA_AVENAL-BATCH 1 REQUEST.DOC

Section 6.4.2 – agriculture and soils

Section 6.6.2 – biological resources

Section 6.9.3 – land use

In addition to comparing to project impacts to the NAAQS, impacts should be compared

against those in “A Screening Procedure for the Impacts of Air Pollution Sources on Plants,

Soils, and Animals”, EPA 450/2-81-078, December 1980. While dated, this document is the

only guidance currently available for conducting additional impacts assessments. Below

presents Table 3.1 of this document.

Pollutant

Screening

Concentration

(μg/m3)

Modeled

maximum 

(μg/m3)

Model

averaging

time used

SO2 1-Hour 917 1 hour

SO2 3-Hour 786 3 hour

SO2 Annual 18 annual

NO2 4-Hours 3,760 1 hour

NO2 1-Month 564 1 hour

NO2 Annual 94 annual

CO Weekly 1,800,000 8 hour

We note that Section 6.4.2 of Avenal’s application does reference some of the above 

screening concentrations as benchmarks for discussing impacts.

For clarification purposes, please present a summary table of the project’s air quality impacts

within the context of this screening procedure, as well as any other relevant information from

this guidance document.

AEP-4. Visibility Impairment Analysis – Although it appears that a Class I analysis, which includes a

Class I AQRV analysis, is not required as a result of discussions between Avenal and the

respective Federal Land Managers, there is a visibility analysis required under Additional

Impacts Analysis that is separate from the Class I AQRV analysis.

Please conduct VISCREEN analysis, per EPA's “Workbook for Plume Visual Impact

Screening and Analysis (Revised)”, EPA-454/R-92-023, October 1992. This could be called

a “plume blight” analysis. The analysis would be carried out for any nearby “sensitive” Class

I locations, such as parks, or if there are not any of those, then simply locations within 10 km

or so. There are not regulatory criteria that the visibility impact has to meet, so this would be

for informational purposes as part of the additional impacts analysis.

AEP-5. Endangered Species Act – Avenal indicated in its response to initial EPA observations that

information is forthcoming for the purposes of our conduct of the ESA consultation process.

To date, we have not yet contacted the USFWS and therefore look forward to Avenal’s

information.

Thank you for your patience in receipt of this request for clarification. Please feel free to contact me at

(415) 972-3966 or rivera.shirley@epa.gov as needed.