1. I-5 Corridor Reinforcement Project
ColumbiaGrid Regional Review
September 5, 2007

2. Project Purpose
The purpose of the project is to address the following:
Transmission service requests (Long-term)
Generation interconnection requests
Path Congestion
Increasing summer peak loads and existing contractual obligations to serve them
Reduce dependence on existing RAS while maintaining transmission system reliability

3. New Substation -Troutdale 500kV Line and Routing Options

4. Recommended Plan of Service
BPA’s recommended plan of service is to construct a 500 kV line from a New substation north of Allston, to Troutdale substation
The major elements of this plan are:
Construct a new 500kV three breaker ring bus approximately 12 miles north of Allston substation (near Castle Rock, WA) tied into the Napavine-Allston 500kV line.
Construct a 500kV three breaker ring bus at the Troutdale 500kV yard
Construct approximately 70 miles of new 500kV line from the new substation (north of Allston) to Troutdale.

5. Path Capacity
Preliminary study results indicate the following increases in path capacity with the I-5 Corridor Reinforcement project.
NOTES:
These values were based on a comparison assuming the same generation pattern presently used to establish Operating limits on the paths.
These values will vary based on season, generation pattern, etc.

6. What Has Been Done Identify the Problems
Identify the Limiting Conditions (Study Assumptions)
Thermal Analysis
Some Voltage Stability Analysis
Evaluate Alternative Solutions
Develop a Recommended Plan of Service

7. What Remains to be Done Post Draft Report and Base cases
Complete Voltage Stability Analysis
Transient Stability Analysis
Sensitivity Studies
Alternate Plans of Service or Other Projects
Finalize Report