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NEPA Document Collection for: DOI-BLM-CA-017-P006-60
EIS at Long Valley Caldera Geothermal Area for Geothermal/Well Field, Geothermal/Power Plant,

Final EIS and Supplemental Environmental Impact Report for the Proposed PLES I Geothermal Development Project at Long Valley Caldera Geothermal Area for Geothermal/Well Field, Geothermal/Power Plant

General NEPA Document Info
Energy Sector Geothermal energy

Analysis Type



Pacific Energy
Consultant Environmental Science Associates, Inc.

Geothermal Area

Long Valley Caldera Geothermal Area

Project Location


Project Phase

Geothermal/Well Field, Geothermal/Power Plant


Development Drilling
Time Frame (days)
Participating Agencies

Lead Agency


Funding Agency

none provided

Managing District Office

BLM Central California District Office

Managing Field Office

BLM Bishop Field Office,

Funding Agencies

none provided

Surface Manager

Mineral Manager

none provided
Selected Dates
Final EA-EIS Date
/Public Comment Period
June 1989
Decision Document Date 06/09/1989
Relevant Numbers
Lead Agency
Doc Number
Lease Numbers

Proposed Action

Pacific Energy proposes to construct and operate a 10 MWe (net) binary power plant and geothermal wellfield development project (PLES I Project) on federal geothermal lease CA-11667. The project area is located approximately three miles east of the Town of Mammoth Lakes, Mono County, California and is within the Long Valley East Geothermal Unit on land administered by the Inyo National Forest. The project area is within the Long Valley KGRA, immediately adjacent to the existing seven MWe (net) Mammoth-Pacific I geothermal resource electric generating facility (MP I).

The proposed project would include: the drilling, construction, and operation of geothermal production and injection wellfields; the construction and operation of the related production pipeline gathering and injection pipeline distribution system; the construction and operation of a 10 MWe (net) binary power plant facility; and construction of control facilities. As part of the proposed project, all of the mitigating stipulations previously applied by the BLM have been adopted.

Geothermal fluid, produced from up to four geothermal production wells located in the vicinity of Casa Diablo Hot Springs, would be directed by surface pipelines to the proposed binary power plant facility. Approximately 5,000 gpm of geothermal fluid would be produced. After heat extraction, the cooled geothermal fluid would be directed from the power plant by surface pipeline up to four geothermal injection wells and injected into the subsurface injection reservoir. Approximately 13 acres would be disturbed in the development and operation of the proposed project.



EA/EIS Report: