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Derecho Demonstrates Importance of Resilient Electric Transmission Grid

ITC Midwest Transmission Grid

November 30, 2020

As Iowans know, a powerful derecho rolled across a wide swath of the state on August 10, 2020. The storm had the effect of a 40-mile wide tornado that caused severe damage along a 200-mile stretch of the Highway 30 corridor from Boone eastward to the Mississippi River, leaving one-third of all Iowa homes and businesses without power. Suddenly, we were reminded once again how essential electricity is in our daily lives.

As the electric transmission service provider for about two-thirds of the state, the damage to the ITC Midwest high-voltage transmission grid was unparalleled, with 145 lines initially out of service across 26 counties.New LIne in Belle Plaine

The magnitude of the property damage cannot be overstated. ITC Midwest’s largest load center — the Cedar Rapids metropolitan area — took a direct hit with extensive damage to homes, businesses and trees across the area. In addition, all ITC Midwest Cedar Rapids employees suffered residential electric and internet connectivity outages, and employees across the state experienced limited or no cell phone service as cell towers were impacted. This occurred at a time when the COVID-19 pandemic caused its own obstacles. Yet, employees rose to the challenge of helping with ITC Midwest’s swift efforts to restore the transmission system.

Mobilizing Workers Across the State

Utility Workers at Damaged Pole in Belle Plaine

ITC Midwest responded quickly to mobilize 783 utility workers to safely repair the lines and help restore power to Iowans. More than 1,200 wooden and steel poles were used in the rebuild. ITC Midwest personnel maintained close communication with the Governor’s Office, Iowa Utilities Board, Alliant Energy, MidAmerican Energy, CIPCO, rural electric cooperatives and municipal utilities we serve to safely coordinate the storm response.

Despite the immense damage, our crews worked safely and quickly to put poles in the ground and power lines in the air. Just after Noon on Tuesday, August 18 — just eight days after the massive storm hit — ITC Midwest fully restored service to the distribution utilities it serves.

Upgraded Transmission Lines

Our experience from the derecho is that the recently upgraded lines fared much better than older lines, although extremely high wind speeds coupled with storm debris blowing into the lines still caused damage. ITC Midwest transmission poles are designed to withstand winds up to 90 miles per hour, providing resilience and improved system reliability.

Of note is that ITC Midwest’s new line designs incorporate storm structures, which act to stop cascading pole losses. Storm structures are reinforced — typically with guy wires — to limit additional damage caused by increased line tension when a pole goes down. These structures served to help prevent catastrophic damage in our new transmission line segments. Conversely, we observed significant additional damage to our older line segments where we do not have storm structures.

Over the past 12 years, ITC Midwest has invested more than $3.9 billion to improve the reliability of its system. The upgraded lines are improving efficiency, reducing transmission outages, increasing the system’s capacity and providing additional back-up capability during planned and unplanned outages. In fact, we’ve decreased electric transmission outages by 63% on our system since 2008.

The derecho has reinforced our commitment to building resilience into our transmission lines to provide the reliable electric service the distribution utilities we serve and their customers expect. We’re also keenly aware of our costs being passed along to our customers, while recognizing the pitfall of being penny wise and pound foolish. At ITC Midwest, we don’t design our transmission lines just to be reliable on sunny days, but also when severe thunderstorms and ice storms hit. As we’ve witnessed, those storms seem to be happening more and more, which reinforces the need for and value of our investments.

On behalf of the entire ITC Midwest team, I would like to extend our thanks for the outpouring of support we received throughout our restoration of the electric transmission system following the derecho. The patience shown during the outage, the support of our day-and-night operations and the kindness shown our utility crews are much appreciated.

Although our work to restore the transmission grid following the derecho is complete, the work to restore our communities is ongoing. Working together, we will come back even stronger.

Greater Des Moines (DSM) has one of the best business climates in the country. The region is nationally recognized for having a talented and educated workforce, a cost of doing business 17 percent below the national average, a low cost of living and an exceptional quality of life.

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