Tetra Tech EC, Inc. (Tetra Tech) was contracted by Idaho Power and Rocky Mountain Power to support their plans to construct a series of 11 transmission line segments of 230 kilovolts (kV) and 500 kV. The total length of all proposed segments is approximately 1,100 miles. In addition, the proposed project will include construction of three new substations and the expansion of six others. Tetra Tech used a route selection methodology based on constraints and opportunities, GIS databases, and use of a linear routing tool, engaging the public, agencies and the feedback of all stakeholders in the route selection itself.

The project will improve the reliability and efficiency of both utility systems and address congestion problems with the western electrical grid. The project will also tap the developing renewable energy market, especially wind energy, in Idaho and Wyoming and will aid in delivering that energy throughout the northwest region.

Tetra Tech is managing or conducting corridor and routing studies, detailed environmental studies, third-party Environmental Impact Statement (EIS) preparation, and permitting for the proposed construction. Routing considerations include national historic trails, wildlife management areas, national forests, national monuments, agriculture lands, oil and gas well fields, and many other resources found between eastern Wyoming and western Idaho.

Tetra Tech is conducting and managing the biological resources surveys for the entire project. Due to time constraints and in light of conducting detailed field surveys over the entire length of the project, a detailed habitat mapping approach was proposed and accepted by all involved agencies. This methodology will be detailed enough to make impact assessments for special status species based on the amount of disturbance to their specific vegetation habitat requirements.

Tetra Tech is conducting resource studies to identify the required project-specific field data that could be completed with existing data sets available from BLM, United States Forestry Service, and other sources.We are also preparing two Storm Water Pollution Prevention Plans to support an application for the project to be covered under the General Storm Water In coordination with the client, Tetra Tech developed an extensive public involvement/participation program that was implemented throughout the two-state study area.

Tetra Tech managed the preparation of the Draft Environmental Impact Statement (DEIS), which included coordination with multiple local, state, and federal agencies, as well as other stakeholders. In addition, Tetra Tech will assist our client in obtaining all other local, state, and federal permits required for this project.

PERFORMANCE HIGHLIGHTS

• Detailed corridor/routing studies using GIS-based Linear Routing Tool
• Cultural and biological field studies have been initiated for proposed and alternate corridors
• EIS involves 12 Bureau of Land Management (BLM) field offices, 2 national forests, USFWS and many other federal and state agencies
• Public involvement includes 20 counties in Idaho and Wyoming