Re: PPEC PSD Permit Application: PM BACT for the Cooling System 

Roger Kohn to: Steve Hill 05/23/2012 10:13 AM

Cc: Gerardo Rios

Steve,

Thank you for the additional information you provided on PM BACT for the PPEC cooling system in your 

5/16/12 letter. Your letter provides some, but not all, of the additional information that we need to 

complete our BACT analysis and send our draft permit and fact sheet to OAQPS for review. To help us 

propose the permit sooner, we need additional clarification on two issues.

In your letter, you state that you have eliminated dry cooling in the BACT analysis because “there are 

times when the ambient temperature in San Diego is too high for a 100% air-cooled system to provide 

sufficient cooling for the intercooler system to sustain turbine performance.” Similarly, in the PSD 

application (p. PSD-App-1.92), you state that “The main technical issue associated with dry cooling 

towers for this application is the limited availability to provide adequate cooling under high-temperature 

conditions. The plant will use a PDCS in a closed-loop configuration that utilizes dry cooling but also

requires additional cooling capacity. For the purposes of this analysis, dry cooling was eliminated as a 

potential BACT option for the second stage of the cooling system because enhanced cooling is required 

for the plant beyond what is already being provided by the dry cooling system.”

We believe we might understand your point, however, the information you have provided is not specific 

enough to justify eliminating dry cooling in Step 2 of the analysis on the basis of technical infeasibility. 

Based on your submittal, it appears that you are actually trying to explain that dry cooling alone is not 

technically feasible all the time and may need to be supplemented by a type of wet cooling when the 

ambient temperature exceeds a level that is not stated in the documentation you submitted. Please 

clarify if this is the case, the temperature at which the dry cooling system would not function, how often 

that is expected to occur, and how the supplemental cooling system could be used for those short periods 

of time when the dry cooling system alone would not work. Thus, you would provide the necessary 

information to eliminate dry cooling alone, but would show how dry cooling with intermittent use another 

cooling system would be technically feasible. As you outline your decision-making for the selected (and 

non-selected) control option, please discuss any associated trade-offs considered, such as environmental 

and economic trade-offs, as part of your design and operating criteria. 

Also, in your 5/16/12 letter, you present a bullet list of control technologies for the BACT analysis, in 

descending order of control effectiveness. However, you did not include the Partial Dry Cooling System 

(PDCS) that PPEC proposes to use in the initial ranked list. This means that if once-through cooling and 

dry cooling are eliminated from the analysis, we do not know if the PDCS is the highest ranked remaining 

option. If it is, we do not need to eliminate the other remaining control options from the analysis. If it is 

not, we may require additional information to justify eliminating any other options that are more effective, 

or as effective, as PDCS. Please provide a complete list of all control options you considered in the 

analysis, ranked by control efficiency.

Thank you.

Roger Kohn

USEPA Region 9 - Air Division (AIR-3)

75 Hawthorne Street

San Francisco, CA 94105-3901

415-972-3973 

kohn.roger@epa
Steve Hill Attached is a response to a request from EPA... 05/16/2012 08:39:17 AM

From: Steve Hill <SHill@sierraresearch.com>

To: Gerardo Rios/R9/USEPA/US@EPA, "David Jenkins (djenkins@apexpowergroup.com)" 

<djenkins@apexpowergroup.com>, "McKinsey, John A." <JAMCKINSEY@stoel.com>, "Moore, 

Steve" <Steve.Moore@sdcounty.ca.gov>, 

Cc: Roger Kohn/R9/USEPA/US@EPA, Gary Rubenstein <GRubenstein@sierraresearch.com>, 

Maggie Fitzgerald <MFitzgerald@sierraresearch.com>, "<Craig.Kebodeaux@kiewit.com>"

<Craig.Kebodeaux@kiewit.com>, Michael King <mpking@apexpowergroup.com>, "Foster, 

Melissa A." <mafoster@stoel.com>, "Hellwig, Kimberly J." <kjhellwig@stoel.com>

Date: 05/16/2012 08:39 AM

Subject: PPEC PSD Permit Application: PM BACT for the Cooling System

Attached is a response to a request from EPA about PM BACT for the Cooling System for the PPEC PSD 

Permit application.

Thanks to Roger for articulating EPA’s need for additional information about this issue.

Do not hesitate to contact me if you have any questions.

[attachment "Cooling System BACT letter 05-16-12.pdf" deleted by Roger Kohn/R9/USEPA/US]