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This Environmental Assessment (EA) analyzes the potential impacts associated with the proposed construction and testing of geothermal exploration wells, access roads, and ancillary facilities in Dixie Valley, Churchill County, Nevada (see links in column to the right). TGP Dixie Development Company (TGP) proposes to explore the geothermal resource potential of the Coyote Canyon (CC) and Dixie Meadows (DM) lease areas in Dixie Valley, which are located primarily on federal lands managed by the U.S. Bureau of Land Management (BLM). The BLM is the lead agency for this EA in accordance with the National Environmental Policy Act (NEPA) (40 Code of Federal Regulations [CFR] Parts 1500-1508). The purpose of the geothermal exploration is to confirm that sufficient reservoir capacity is available to allow long-term production. This EA analyzes potential impacts from the proposed exploration and testing activities at the CC and DM sites. Because both geothermal drilling projects have similar timing, geography, and types of actions, BLM has determined that the two proposals would be analyzed in one EA. The exploration activities are referred to as the Proposed Actions. The geothermal leases held by TGP for the CC exploration project contain 7,681 acres (CC lease area). The geothermal leases held by TGP for the DM exploration project contain 3,960 acres. The Proposed Action for DM also includes an area known as the Lamb Mineral Interests (760 acres). TGP owns the mineral rights for this land, along with the right to surface use in exercise of mineral rights. The U.S. Navy owns the land surface. Although the BLM does not have any jurisdiction to permit any surface activities, and no BLM action is required for exercise of these mineral rights, information on project activities there is included in this EA because they are part of the overall project described for Dixie Meadows. TGP proposes to conduct geothermal exploration in a portion of each lease area called the project area. Figures 2 and 3 show the lease areas and project areas for each site. An Operations Plan to drill and test up to 15 explorations wells at the CC project area and to drill and test up to 15 exploration wells at the DM project area was submitted to the Bureau of Land Management (BLM), Stillwater Field Office (SFO) in September 2009. A revised Operations Plan was submitted in October 2009. In addition to the exploration drilling program, mineral material sales contracts would be required for aggregate material obtained from BLM-managed gravel pits. These contracts (one for CC and one for DM) would be for less than 50,000 cubic yards of aggregate and less than 5 acres of subsurface disturbance each. Individual Geothermal Drilling Permits (GDPs) would be issued separately from this document.

• Clean construction equipment prior to project work (may be washed in Fallon prior to deployment) • Avoid or treat existing weed infestations prior to disturbance. • Any areas that become infested with weeds during construction would be mapped and treated.

Management practices, described in Section 2 and including development of a spill plan, use of secondary containment structures, and worker training, would be used to prevent the release of hazardous wastes to the environment. Solid wastes would be transported offsite to a landfill. Implementation of these procedures would prevent or minimize potential impacts on the environment due to generation of hazardous or solid wastes.

To minimize air pollution emissions from construction activities and construction and drill rig diesel engines, the following BMPs for fugitive dust and diesel exhaust would be implemented during operational activities: • Surfacing access roads with aggregate materials, wherever appropriate • Using dust abatement techniques, such as watering on unpaved, unvegetated surfaces to minimize airborne dust, as needed (The source of water to be used for dust abatement is described in Section 2.1.8.) • Posting and enforcing speed limits to reduce fugitive dust (speed limit of 15 miles per hour, as necessary) • Applying dust abatement techniques (such as watering, requiring loader buckets to be emptied slowly, minimizing drop heights, etc.) to earth-moving, excavating, trenching, and grading activities • Minimizing equipment and vehicle idling times during construction activities

If active nests are present within these areas to be disturbed, TGP would coordinate with BLM to develop appropriate protection measures for these sites, which may include avoidance, construction constraints, and/or the establishment of buffers. Habitat for migratory birds would be eliminated within areas of proposed disturbance prior to the nesting season. In the event this elimination measure is not implemented, if ground disturbing activities do take place during the migratory bird nesting season, migratory bird nest surveys would be conducted early in the nesting season by a qualified biologist acceptable to BLM. This survey would be conducted to identify either breeding adult birds or nest sites within the specific areas to be disturbed. If active nests are present within these areas to be disturbed, TGP would coordinate with BLM to develop appropriate protection measures for these sites, which may include avoidance, construction constraints, and/or the establishment of buffers. To minimize impacts to migratory birds and other wildlife, in addition to the management practices described above, well pads and roads would be recontoured and reseeded following completion of the Proposed Actions as described in Section 2.1.10. Erosion-control measures would be implemented as described in Section

Coyote Canyon <p> Construction activities that include surface disturbance of the immediate subsurface at one well pad (Well 61-15) would have the potential to impact paleontological resources because subfossil wood occurs in the immediate vicinity (PFYC = 4). Prior to construction at this site, this impact would be mitigated by moving the location of Well 61- 15 to the west away from this resource, staking for avoidance that area within Sections 14 and 15 where subfossil wood exists, subsequent avoidance of the area during construction, and by worker education that would include the importance of paleontological resources avoidance. <p> Of the 25 well sites in the CC area, only one possesses high (PFYC Class 4) paleontological sensitivity (Well 61-15), because of the presence of subfossil wood on the surface in the immediate vicinity. The subsurface potential of all well pads in the CC area is considered to be low (PFYC Class 2) because they are located at sites underlain by alluvium or oxidized playa sediments. Impacts to paleontological resources from project development in the CC area would therefore not occur because the one area designated PFYC Class 4 (high sensitivity) will be avoided by relocation of the well pad, and by educating workers on paleontological resources avoidance. <p> Dixie Meadows <p> The area possessing unknown potential with the possibility of fossils occurring at depth (PFYC Class 3b) lies to the east of the well sites and their associated access roads. In this area deep, relatively unweathered lacustrine sediment and spring discharge deposits occur, and theses sediments have yielded scientifically important paleontological resources in other portions of the Great Basin. A north-south segment of access road is the only portion of the Dixie Valley project area to cross sediments that have unknown potential (PFYC Class 3b). This would be mitigated by assuring that the roadway in that area is not bladed, but instead would consist of material imported to create a roadbed elevated above potentially sensitive sediments.

• Excavation into native soil during construction of well pad reserve pits would be minimized to the maximum extent possible. • Wells and roads not required for development purposes would be re-contoured to blend with the surrounding topography, in accordance with lease stipulations. • Topsoil would be salvaged and reused whenever possible and in a timely manner. • Temporarily disturbed areas would be reseeded where previously vegetated using a BLM-approved seed mixture. • Erosion control measures, including but not limited to silt fencing, diversion ditches, water bars, temporary mulching and seeding, and application of gravel or rip rap, would be installed where necessary immediately after completion of construction activities to avoid erosion and runoff. • Access roads would follow existing contours to the maximum extent possible. In areas where new access roads must be constructed across slopes, erosion control measures would be installed as necessary, in accordance with Gold Book standards (BLM, 2007a). • An average of 6 inches of gravel would be used as road surface because roads would be used during all seasons. Up to 3 feet of gravel may be used on some sections of road, and no gravel would be used on road sections where the natural surface is adequate. • Additional gravel would be laid down when ground conditions are wet enough to cause rutting or other noticeable surface deformation and severe compaction. As a general rule, if vehicles or other project equipment create ruts in excess of 4 inches deep, a gravel surface would be installed prior to additional use. • When construction occurs in areas of very soft soils, up to 3 feet of aggregate would be used. • An NDEP BAPC Surface Area Disturbance documenting the BMPs to be used would be required for the project because the surface disturbed would be greater than 5 acres. • Overland route corridors may be used for infrequently accessed locations.

Impacts to vegetation would be minimized by reseeding all areas of access roads and well pads not required for subsequent energy production using a BLM-approved native seed mixture. Topsoil would be salvaged whenever possible and reused in a timely manner.

• When permanent new access roads must cross ephemeral washes, rolling dips would be installed. The rolling dips would be designed to accommodate flows from at least a 25-year storm event. Culverts may be used wherever rolling dips are not feasible. • Drill pad reserve pits would be compacted during construction and settled bentonite clay from drilling mud would accumulate on the bottom of the drill pad reserve pit to act as an unconsolidated clay liner, reducing the potential for drilling fluid to percolate to groundwater. • TGP would obtain necessary working in waters and/or groundwater discharge permits and provide a Notice of Intent to NDEP prior to well pad construction. • Wetland boundaries would be avoided to the extent possible. • A BLM-approved grouting and casing program for construction of slim well and/or exploration wells would be implemented to prevent water quality effects on groundwater during or after well installation. • Borehole geophysics analyses (cement bond logs) would be conducted to document that well-casing grouting activities provide an effective seal, isolating the geothermal aquifer from shallow alluvial aquifers and therefore minimizing potential impacts on surface washes, springs, seeps, or floodplains. • BMPs would be implemented to ensure that any geothermal fluid encountered during the drilling does not flow uncontrolled to the surface. These include the use of “blowout” prevention equipment during drilling and the installation of well casing cemented into the ground. • A hydrologic evaluation plan will be submitted to the BLM for approval prior to drilling.

This Environmental Assessment (EA) analyzes the potential impacts associated with the proposed construction and testing of geothermal exploration wells, access roads, and ancillary facilities in Dixie Valley, Churchill County, Nevada (see links in column to the right). TGP Dixie Development Company (TGP) proposes to explore the geothermal resource potential of the Coyote Canyon (CC) and Dixie Meadows (DM) lease areas in Dixie Valley, which are located primarily on federal lands managed by the U.S. Bureau of Land Management (BLM). The BLM is the lead agency for this EA in accordance with the National Environmental Policy Act (NEPA) (40 Code of Federal Regulations [CFR] Parts 1500-1508). The purpose of the geothermal exploration is to confirm that sufficient reservoir capacity is available to allow long-term production. This EA analyzes potential impacts from the proposed exploration and testing activities at the CC and DM sites. Because both geothermal drilling projects have similar timing, geography, and types of actions, BLM has determined that the two proposals would be analyzed in one EA. The exploration activities are referred to as the Proposed Actions. The geothermal leases held by TGP for the CC exploration project contain 7,681 acres (CC lease area). The geothermal leases held by TGP for the DM exploration project contain 3,960 acres. The Proposed Action for DM also includes an area known as the Lamb Mineral Interests (760 acres). TGP owns the mineral rights for this land, along with the right to surface use in exercise of mineral rights. The U.S. Navy owns the land surface. Although the BLM does not have any jurisdiction to permit any surface activities, and no BLM action is required for exercise of these mineral rights, information on project activities there is included in this EA because they are part of the overall project described for Dixie Meadows. TGP proposes to conduct geothermal exploration in a portion of each lease area called the project area. Figures 2 and 3 show the lease areas and project areas for each site. An Operations Plan to drill and test up to 15 explorations wells at the CC project area and to drill and test up to 15 exploration wells at the DM project area was submitted to the Bureau of Land Management (BLM), Stillwater Field Office (SFO) in September 2009. A revised Operations Plan was submitted in October 2009. In addition to the exploration drilling program, mineral material sales contracts would be required for aggregate material obtained from BLM-managed gravel pits. These contracts (one for CC and one for DM) would be for less than 50,000 cubic yards of aggregate and less than 5 acres of subsurface disturbance each. Individual Geothermal Drilling Permits (GDPs) would be issued separately from this document.