Docket Number
250 MW
Stanislaus County
Combined Cycle
Project Status
Operational (Natural Gas-Fired)
Project Type
Application for Certification
Project Description

The Walnut Energy Center (WEC) located on 18 acres within a 69-acre parcel in an industrially zoned area, about 4 miles west of the downtown portion of the City of Turlock, Stanislaus County. The site is located southeast of the intersection of West Main Street and South Washington Road.

WEC is a nominal 250-megawatt gas-fired, combined-cycle power plant consisting of two General Electric Frame 7EA combustion turbine generators equipped with dry, low oxides of nitrogen combustors; two heat recovery steam generators; one condensing steam turbine generator; a de-aerating surface condenser; a five-cell mechanical-draft cooling tower; and associated support equipment. Additional components include an advanced water treatment facility, administration and control building, emission control equipment, storage tanks, parking area, and one or more stormwater detention ponds.

WEC’s 2004 CEC Decision approved the use of potable water from the City as an interim supply, or “bridge supply,” for cooling, steam cycle make up and also as a back-up supply until the wastewater treatment plant was able to produce recycled water. Once recycled water was made available, potable water was permitted for use as a back-up source of water in the event of a short-term interruption in recycled water delivery. The use of potable water as a back-up supply after the bridge supply period was limited to 51 acre-feet per year (afy), calculated using a 5-year rolling average. Operation of WEC requires up to 1,800 afy of water, approximately 98 percent of which is used for cooling purposes.

On January 19, 2005, the California Energy Commission (CEC) approved a Post-Certification Amendment (PCA) to replace potable water as its bridge water supply with lower quality ground water from two wells drilled into the upper aquifer; to allow use of potable water for construction instead of upper aquifer well water from TID’s WPP and substation.

On July 27, 2005, the CEC approved a PCA (TN 36090) to modify the number and locations of the bridge and backup plant water supply wells and changes the definition of the “bridge period".

In August 27, 2013, the Energy Commission approved a PCA (TN 200536) to amend soils and water condition of certification to allow for additional back-up water supply.

  • Order Approving Transfer of Ownership to Walnut Energy Center Authority, TN 32329, 09/13/2004, Order No. 04-0908-01c, Commission approval of the transfer of ownership from Turlock Irrigation District to Walnut Energy Center Authority.
  • Order Approving A Petition to Modify Bridge and Construction Water Supply, TN 33181, 01/21/2005, Order No. 05-0119-02, Commission approval to replace potable water as a bridge water supply with lower quality ground water from two wells drilled into the upper aquifer, and to use potable water for construction purposes instead of upper aquifer well water from Turlock Irrigation District’s Walnut Peaker Plant and substation.
  • Order Approving a Petition to Modify Storage of Hazardous Substances, TN 34776, 06/27/2005, Order No. 05-0622-02, Commission approval to modify the minimum distances between sulfuric acid tanks and stored flammable materials from 100 feet to 50 feet.
  • Order Approving an Amendment Petition to Modify Bridge and Backup Water Supply, TN 36090, 12/14/2005, Order No. 05-0727-02, Commission approval to modify the number and locations of the bridge and backup plant water supply wells and changes the definition of the “bridge period”.
  • Order Approving a Petition to Modify Air Quality Transcription Errors, TN 36494, 03/08/2006, Order No. 06-0301-03, Commission approval to correct a transcription error in Condition of Certification AQ-71 which provides emission limits during project commissioning.
  • Notice of Insignificant Project Change to Modify the Back Wash Holding Tank, TN 45681, 03/19/2008, Staff approval  to replace its 18,000 gallon, 12-foot diameter by 20-foot high backwash holding tank with a 24,000 gallon, 12-foot diameter by 30-foot high tank.
  • Staff Approval to Add New Micro Filter Feed Tank and Shade Structure, TN 57281, 06/07/2010, Staff approval to add a new Micro Filter Feed Tank and shade structure to continue to effectively operate its Zero Liquid Discharge water treatment process.
  • Order Approving a Petition to Amend Soils and Water Condition Of Certification to Allow for Additional Back-Up Water Supply, TN 200536, 09/20/2013, Order No. 13-0827-04, Commission approval to modify the wording of the existing condition of certification SOILS&WATER-5, allowing the project to increase the back-up water supply when recycled water is not available.

Attention: Non-hypertext items above will need to be requested from the Compliance Project Manager, along with the document TN number, if provided above.

Power Plant Certification and Exemption Processes

As required by the Warren-Alquist Act, the Energy Commission monitors projects under its jurisdiction throughout construction, operation, and closure to ensure compliance with the conditions of certification imposed for approving the projects.

Original Proceeding

e-Commenting has been closed. Please submit your comments in compliance proceeding above.

Docket Log (02-AFC-04)

Exhibit List

Proof of Service List

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Keith Winstead

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