Interstate Power and Light Co. (IPL), Cedar rapids, Iowa, an Alliant Energy company, concluded rebuild work and re-energized a 20 mile stretch of 345 kV transmission line in Poweshiek County. The transmission line, which serves IPL customers throughout the company's service area, was severely damaged at 10:30 am on February 24, 2007 during a major Midwest winter storm.
As part of the rebuild project, IPL rebuilt 82 steel H-Frame transmission structures weighing a total of approximately 3.2 million pounds. With the assistance of helicopters, IPL strung nearly 160 miles of conductor and static wire, equivalent to the distance from Des Moines to the Quad Cities. IPL also installed approximately 300 insulators, which are used to attach the conductor to each of the transmission structures.
IPL completed the redesign and rebuild of the transmission line in less than five months. Rebuild projects of this magnitude typically require 18-30 months to design and construct. Up to 50 workers were on site, working seven days a week. The workers accumulated a total of over 45,000 worker-hours to complete the project as safely and quickly as possible. IPL's share of the cost of the rebuild project is approximately $10 million.
"The completion of the 345 kV transmission line in southeast Iowa was an awesome display of teamwork by our employees," says Vern Gebhart, vice president of IPL customer operations. "The February storms wreaked havoc on our electric system and the rebuild efforts were daunting. With the completion of the rebuild of this part of our transmission system, our ability to provide safe and reliable electric service to our customers throughout our service area has been greatly enhanced."
IPL completed its initial restoration efforts on March 7, 2007. Permanent repairs to the system will continue throughout 2007. More than 269,000 IPL customers lost electric service as a mix of freezing rain, high winds, sleet and snow caused extensive damage to IPL's electric distribution and transmission infrastructure in late February and early March 2007. More than 100 communities served by IPL in Iowa and Minnesota were without electric service for more than 24 hours at some point during the two Midwest winter storms.
More than 2,200 IPL employees, mutual assistance and contract employees from utility companies across the country were deployed to assist in the restoration of IPL's electric transmission and distribution infrastructure.