[California Energy Commission Letterhead]

(Modify Ammonia Storage Area)

The Otay Mesa Generating Project is a nominal 510 megawatt natural gas-fired power plant currently under construction. The facility is located approximately 15 miles southeast of the City of San Diego in the Otay Mesa area of San Diego County.

On December 1, 2003, California Energy Commission (Energy Commission) staff received a petition from Otay Mesa Generating Company, to amend the Energy Commission Decision for their project.


Otay Mesa is seeking approval to modify the facility design of their aqueous ammonia storage area by replacing two double-walled 13,000 gallon aqueous ammonia storage tanks with one single-walled 16,000 gallon aqueous ammonia tank. The single-walled tank will be housed in a secondary containment basin capable of holding 150 percent of the tank volume plus 24 hours of rain. The storage area will be constructed in the same location requiring a smaller space.

The project was originally licensed to PG&E Generating, and subsequently sold to Calpine. Therefore, Calpine was unable to know of this design change at the time of licensing. The requested changes will reduce capital costs for the project and maintain the safety and reliability to the facility and public by reducing the amount of aqueous ammonia stored on site.


Pursuant to section 1769(a)(2), Title 20, California Code of Regulations, Energy Commission approval for the change is not required if Energy Commission staff determines: 1) that there is no possibility that the modification may have a significant effect on the environment, and 2) that the modification will not result in a change or deletion of a condition of certification, or make changes that would cause the project not to comply with applicable laws, ordinances, regulations, or standards. Energy Commission staff have determined that the proposed modifications to the aqueous ammonia storage area meets these criteria because:

  1. Existing conditions of certification are sufficient to cover the proposed change without changes to or deletion of a condition of certification;
  2. The modification will not have any significant effect on the environment; and
  3. The modification of the aqueous ammonia storage tank area will allow the project to remain in compliance with applicable laws, ordinances, regulations or standards.

Any person may file a written objection to staff's determination on the grounds that the project change does not meet the criteria set forth above. If you object to staff's determination, please submit the objection in writing to Ila Lewis, Compliance Project Manager, at the address above, or by fax at (916) 654-4678, or by e-mail at ilewis@energy.state.ca.us. If no substantive objection is received by December 30, 2003 at 5:00 P.M., the requested change will be approved.

Date On-line: December 18, 2003.

TERRENCE O'BRIEN, Deputy Director
Systems Assessment & Facilities Siting Division

Mail List # 708 and POS

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