Straight From the Source
David Cameron, City Administrator
October 26, 2010
The Near Miss
The Siloam Springs Electric Department has plenty of reasons to be nervous when a vehicle hits a power pole. Recently, an 18-wheel tractor trailer struck an electric transmission pole while trying to avoid an accident at the corner of Quarter Road and Lincoln Street.
The truck damaged the pole, but luckily it remained intact. While this incident was a “near miss”, Siloam Springs could have faced significant problems had the truck damaged the pole any further. Currently, there is only one power connection point with our power supplier, the Grand River Dam Authority (GRDA) of Oklahoma. And the pole that was damaged a few weeks ago was on this crucial transmission line.
Had the power pole received more damage and broken the situation could have been grim. When a pole like this falls, it generally causes a domino effect, taking down several more poles. The Electric Department estimates that this pole had the capability to cause four more poles to break, bringing the total to five downed poles. Just to give everyone an idea of the magnitude of this scenario, let’s consider the consequences of just one broken pole.
If one pole had broken, the Electric Department would have total power loss at three of our four electric substations, leaving 3,000 to 3,500 customers without power. Each of Siloam Springs industrial customers would also lose power, as would all businesses east of Kenwood Street on Highway 412. Eight traffic signals would be without power as well.
Electric Department crews would then jump into action to begin the long process of restoring power to as many customers as possible. Within a few hours, power might be restored to an estimated 1000 customers. This would leave 2,000 to 2,500 customers, and all local industries, still without electricity. It would likely take another 17 to 24 hours to complete the repairs to bring everyone back online. In this time, you can imagine the impact to the community and local business and industry.
While we all hope that a situation like this never happens, it is possible. Over the past five years, an average of 7.6 power poles have been damaged or broken each year after being struck by vehicles. Siloam Springs has been in dire need of a contingency plan to avoid a large power outage.
Our contingency plan is nearing completion. A new electric transmission line loop and substation is under construction north of Siloam Springs. The Siloam Springs City #3 North 69kV Transmission Line will provide a second point connection, and is an important step in supporting ever-increasing system loads and will also drastically improve system reliability.
The City of Siloam Springs and GRDA partnered on this project beginning in 2008 to establish a second power connection point in Siloam Springs. A part of our long-term purchase power agreement, GRDA’s transmission upgrade expenses were estimated to be $11.4 million. The city is constructing its portion of the line on the Arkansas side of the state line at a cost of $2.9 million. Funded by a 3/8 cent sales tax approved by voters in July 2006, the project will be completed in late 2010 or early 2011. The line will be approximately 4.2 miles in length. Steel poles will support the line at an average of 70 feet high, with the bases of the poles 18”-24” in diameter.
This project is necessary for several reasons. First, it will allow for future growth and expand our access to power. It will also improve reliability. The expansion will also create redundancy in our electrical system by creating two power connection points that supply Siloam Springs with power. This will reduce the chance of a power outage. Lastly, it will help us plan system maintenance more effectively. The Electric Department will be able to isolate certain sections of the system without affecting other sections of the line.
The recent “near miss” reminded us of how important the insurance policy of the new transmission line will be. Soon we won’t have to rely on luck or be quite as nervous about falling power poles.
The City of Siloam Springs is quite fortunate to own its own electric utility. The forward thinking, professional and dedicated local staff of the Electric Department works hard to ensure that Siloam Springs has reliable, competitively priced energy.
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