Hailey-Ketchum Transmission Line Frequently Asked Questions

1. Why is this power line needed?
2. Is growth an issue in the Wood River Valley?
3. How was the need for the line determined?
4. What is the project cost?
5. Can the power line be put underground?
6. Who pays that cost?
7. How will the residents be involved in the project process?
8. Has the route been identified?
9. How are route options identified?
10. When will construction begin?
11. Will the power line project conflict with the Idaho Highway 75 project?
12. Can you add local generation, like a wind farm, to replace the need for a new line?
13. What will the transmission line and poles look like?

1. Why is this power line needed?

The north valley is currently served by a single 138,000 volt transmission line. An outage on this line results in power loss to the entire Ketchum and Sun Valley area. A second transmission line to the north is critical for reliable electric service, and a plan now exists to provide for that needed reliability. A second redundant line provides back-up for the other line. An outage on the existing line during peak winter cold temperatures could be catastrophic without it.

2. Is growth an issue in the Wood River Valley?

Over time, the Wood River Valley grows by about 1-2 percent each year and that growth, along with increases in electricity use, continue to drive the demand for reliable electric service. Homes and businesses have multiple PCs, TVs, lighting, furnaces or other electronics they rely on, particularly in the winter with the ski industry and year-round tourism.

The Hailey Planning and Zoning Department recently received a report projecting the city’s population will double by 2025. While all this presents many growth-related challenges for infrastructure planning, Idaho Power is focused on serving the electric needs of Wood River Valley residents today and in the future.

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3. How was the need for the line determined?

The need for a second transmission line was identified in 1995 by a community advisory committee (CAC) that worked with Idaho Power to consider electric demand and infrastructure; however residents and leaders declined the line and decided the risk at the time was acceptable.

A CAC was convened in 2007 and through another collaborative process with Idaho Power, developed the Wood River Electrical Plan (WREP), which had multiple electric infrastructure recommendations. It describes the transmission facilities needed to reliably serve the valley into the future.

Following that planning effort, Idaho Power initiated the first project recommended by the CAC – the 138 kV transmission line between Hailey and Ketchum.

4. What is the project cost?

The cost of the project depends on the final route and design. A 138 kV overhead transmission line costs approximately $350,000 to $400,000 per mile to construct. The line will be approximately 12 miles, depending on the final route.

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5. Can the power line be put underground?

Underground construction is an option, but there are some factors to consider. As regulated by the Idaho Public Utilities Commission (IPUC), Idaho Power is obligated to build its infrastructure in the most cost effective manner possible. Idaho Power develops transmission project designs that provide for least cost while adhering to consistent standards for service throughout its service area. The IPUC allows recovery of those reasonable costs. To the extent that customers desire the company to pursue alternate designs, such as underground transmission, at a higher cost, it is the company’s position, supported by the IPUC, that the customer requesting the alternate design is responsible for the additional costs.

As described above, a 138 kV overhead transmission line costs approximately $350,000 to $400,000 per mile to construct. A similar transmission line placed underground costs about 10 times that amount. Learn more about overhead/underground power lines.

6. Who pays that cost?

As outlined above, customer(s) requesting underground service are required to cover costs exceeding the least-cost design, as regulated by the IPUC. Customers, such as a city or county, can pursue options such as creating a Local Improvement District to raise funds for such a project.

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7. How will the residents be involved in the project process?

Idaho Power values the input and ideas of local community members for project location and design. Many community work sessions will be held with residential and business groups throughout the project area to exchange information and ideas for this transmission line. Project open houses also will be held and information will be shared through other avenues such as the news media, website, posters, mailings, etc.

8. Has the route been identified?

No. The WREP CAC recommended, to the extent possible, that the line follow Idaho Highway 75. Beyond that, no specifics have been identified. Community meetings, feedback and public input/work sessions will help identify constraints for the line, opportunities for potential routes, issues and ideas.

Currently a lower-voltage distribution line follows the highway. Options and ideas from the CAC include:

• Putting the existing line on the same poles as the new transmission line
• Burying the distribution (at a significant cost increase) and putting only the transmission line overhead
• Burying the transmission line (an even greater cost increase)
• Or a combination of overhead and underground design for the transmission line.

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9. How are route options identified?

Using the recommendations from the WREP CAC, Idaho Power uses an internal route development process to consider all route options initially. This process includes:

• Collecting data on existing conditions of the area
• Reviewing studies and documentation
• Conducting field visits to understand terrain, constraints, existing corridors or other opportune areas
• Coordinating with the public, permitting agencies, municipalities and other stakeholders to discuss the project.

10. When will construction begin?

Construction is anticipated to begin in 2012, with an in-service date of 2013.

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11. Will the power line project conflict with the Idaho Highway 75 project?

Construction of the transmission line is tentatively planned to coincide with the widening of Idaho Highway 75, if the route ends up following the highway. Poles could be placed in the road right-of-way.

12. Can you add local generation, like a wind farm, to replace the need for a new line?

Part of the Idaho Power concession as a regulated utility is an obligation to reliably serve its customers. In fulfilling this obligation, Idaho Power forecasts energy usage by its customers and is required to have adequate resources (or access to energy markets) to reliably satisfy that demand.

Electricity is not easily stored and for all practical purposes the instantaneous customer demand is generated at the moment of usage. The requirement to serve all instances of demand is the reason intermittent resources such as wind and solar are backed up by dispatchable generation. Wind and solar are not an instantaneous, dependable resource, and it is access to a dispatchable resource via a transmission line that satisfies Idaho Power’s obligation to serve customers. A transmission line is the current proposal to reliably satisfy the Wood River Valley’s instantaneous demand.

The mandate to reliably serve means that even if significant small wind and solar units are deployed in the Wood River Valley, these resources will not satisfy Idaho Power’s obligation to its customers. The inability to serve electricity needs is due to the risk of the wind and solar resources not generating at the instant the energy is required by the customer and adversely impacting the system.

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13. What will the transmission line and poles look like?

Typical 138 kV designs include a wood or steel pole, approximately 85 feet tall to allow for distribution underbuild and a shield wire on top.

Early design options preferred by the WREP CAC include low-profile poles approximately 45 feet tall that run next to the distribution line; another option uses similar poles about 70 feet tall and include the distribution line on the same poles.

Poles can be made of gray steel, a weathering/rust-colored steel, or wood.