The Sun Valley City Council, Idaho Power Co. and members of the community on Wednesday discussed the feasibility of placing one of two main overhead power lines in the city underground.
The project would bury about two and a half miles of overhead power line, along Juniper Road to the southeast of the Elkhorn substation up to the top of the divide between the East Fork of the Wood River and Elkhorn. The 138,000-volt line runs over 38 properties.
Preliminary cost estimates are $2.3 million per mile. However, a feasibility study conducted by Idaho Power states that the cost could vary 20 percent or more from the estimate. The largest single expenditure is for cable and installation, which comes in at $3.8 million. The study states that large fluctuations in cost could come from escalating metal prices, a volatile market over the past year.
Preliminary discussion on a funding method has focused on the creation of a local improvement district, most likely composed of the 38 affected properties. The LID would involve a bond issue repaid through increased property taxes.
City Councilman Nils Ribi, whose home is one of the 38 affected properties, said initial analysis by real estate experts indicates the removal of the overhead line could increase property values anywhere from $200,000 to $250,000.
The biggest concern among the council, residents and Sun Valley Co. is the reliability of the new, underground cable. The current cable has been very reliable, said David Angell, Idaho Power manager of delivery planning. Angell said that over the past 10 years, there have been only four "sustained" outages¾those lasting five minutes or more. He said three were due to weather and one was a maintenance problem.
In the first two years of operation, new cables are prone to what power industry insiders refer to as "infant mortality," Angell said. These failures occur at the splices¾weak points where two cables are joined. He said that during the first two years, inspections are required every six months, during which time the power would be off for a full eight-hour working day. In addition to outages for maintenance, residents would have to incur two eight-hour outages during the initial construction phase as well.
"It seems unreasonable to sign up for such an inconvenience," said Councilwoman Ann Agnew, who was assured the outages could be coordinated with the affected communities.
Of even greater concern are the unscheduled outages.
Sun Valley Co. General Manager Wally Huffman sat in on the "exact-same conversation in 1991," he said, and brought up at Wednesday's meeting the same concern he had then: the danger of losing power in the winter months.
"If we lose power for 24 hours in the winter the amount of damage to this community would be great," Huffman said. "Pipes would burst, things would freeze up, it would be a disaster."
He pointed out that winter is a very difficult time to fix a circuit, contending that a 24-hour outage is a best-case scenario.
Several options were discussed to potentially mitigate the impact of an unforeseen outage, including leaving the existing overhead power lines up during the crucial first two years or instilling an 80- or 100-megawatt generator. Angell said such generators are costly and highly inefficient.
"The next step is to work with the affected parties—the focus being the cost of undergrounding versus property values," Ribi said. "Most importantly, we want to make sure we do this right and don't rush it."