California Energy Commission Letterhead

Notice of Staff Workshop on
Clarification of Data Responses, Issue
Resolution and Project Schedule for the
Mariposa Energy Project

The California Energy Commission staff will conduct a workshop for the proposed Mariposa Energy Project (MEP) to discuss the clarification of the applicant's data responses, work towards resolving outstanding issues and discuss project scheduling. All interested agencies and members of the public are invited to participate.

The workshop will be held:

WEDNESDAY, June 30, 2010
Beginning at 1:15 PM

California Energy Commission
First Floor - Hearing Room B
1516 9th Street
Sacramento, CA 95814-5512
(Wheelchair Accessible)

Call-in Number (toll free): 1-888-469-1348 (pass code: 31996)


The purpose of the workshop is to allow staff, the applicant, other parties, interested agencies, and the public to clarify any of the applicant's data responses. The workshop will also focus on resolving project issues and the project schedule. Subjects to be discussed include: Air Quality, Thermal Plume Analysis and Traffic and Transportation. Other technical areas addressed in the data requests may be discussed as necessary. The status of the proposed project, copies of notices, an electronic version of the Application for Certification, data responses, and other relevant documents are also available on the Energy Commission's Internet web site at:

Project Location

The proposed project site is in northeastern Alameda County, in an unincorporated area designated for Large Parcel Agriculture by the East County Area Plan. The site is located approximately 7 miles northwest of Tracy, 7 miles east of Livermore, 6 miles south of Byron, and approximately 2.5 miles west of the community of Mountain House in San Joaquin County.

The facility would be located southeast of the intersection of Bruns Road and Kelso Road on a 10-acre portion of a 158-acre parcel (known as the Lee Property) immediately south of the Pacific Gas and Electric Company (PG&E) Bethany Compressor Station and 230-kilovolt (kV) Kelso Substation. The proposed power plant site is located in the southern portion of the Lee Property. The existing, unrelated 6.5 MW Byron Power Cogeneration Plant occupies 2 acres of the 158-acre parcel northeast of the MEP site. The remainder of the parcel is non-irrigated grazing land.

Project Description

The MEP would be a natural-gas fired, simple cycle peaking facility with a generating capacity of 200 megawatts (MW). The project proposes to operate on average, 600 hours per year, but if licensed can run up to 4,000 hours. Primary equipment for the generating facility would include four General Electric (GE) LM6000 PC-Sprint natural-gas fired combustion turbine generators (CTG) and associated equipment. Power would be transmitted to the grid at 230-kV through a new 0.7-mile transmission line that would connect to the existing Kelso Substation. A new 580-foot natural gas pipeline would connect the project site to PG&E's Line 2, which is an existing high-pressure natural gas pipeline located northeast of the project site. Service and process water would be fresh irrigation water provided from a new connection to the Byron Bethany Irrigation District (BBID) via a new pump station and 1.8-mile pipeline. The MEP is proposing to utilize on average 35 acre feet of water per year. In the event of continuous and maximum permitted operation, the MEP would utilize 187 acre feet of water for 4,000 hours of operation. All domestic wastewater would be routed to an onsite septic system and either discharged to an onsite leach field or removed via truck for offsite disposal. Stormwater runoff would be detained onsite in an extended detention basin and released according to regulatory standards for stormwater quality control. Air emissions control systems would include a selective catalytic reduction (SCR) system for nitrogen oxides (NOx) control and an oxidation catalyst for carbon monoxide (CO) control.

Temporary construction facilities would include a 5-acre worker parking and laydown area immediately east of the project site, a 1-acre water supply pipeline parking and laydown area located at the BBID headquarters facility, to serve water pipeline construction needs, and a 0.6 acre laydown area along the transmission line route.

Construction of the generating facility, from site preparation and grading to commercial operation, is expected to take place from April 2011 to July 2012 (14 months total).


Please direct your technical or project schedule questions to Craig Hoffman, Energy Commission Project Manager, at (916) 654-4781, or by e-mail at If you desire information on participating in the Energy Commission's review of the project, please contact the Energy Commission's Public Adviser's Office, at (916) 654-4489 or toll free in California, at (800) 822-6228. The Public Adviser's Office can also be contacted via email at News media inquiries should be directed to the media office at (916) 654-4989 or via email at You can also subscribe to receive e-mail notification of all notices at By being on the mailing list, you will receive notices of all project-related activities and notices when documents related to the proposed project's evaluation are available for review. If you want your name removed from the mailing list, please contact Hilarie Anderson, Project Assistant, at (916) 651-0479 or by email at

Date: June 6, 2010

________________/ SIGNED /______________
TERRENCE O'BRIEN, Deputy Director
Siting, Transmission & Environmental Protection Division