Reminiscent of the storm that devastated New Orleans, Louisiana, several years ago, Hurricane Sandy ravaged both Con Edison's underground and overhead electrical delivery systems in late fall 2012. Winds gusted up to 90 mph (145 kmph), sending thousands of trees crashing onto overhead lines, while unprecedented floodwaters rushed into substations and other critical facilities, ultimately crippling many sections of the city.
Con Edison, which serves 3.3 million customers in the five boroughs of New York City and Westchester County, has long realized its susceptibility to storm tides, and weather forecasts made it clear Sandy posed a serious flooding threat. In fact, the utility monitored weather reports that predicted the storm tide at the Battery — the southern tip of Manhattan Island — could reach 12 ft (4.7 m). The previous high reached approximately 11 ft (3.4 m) in 1821, and Hurricane Irene, which struck the region in August 2011, brought a storm tide of 9.5 ft (2.9 m).
When the storm tide from Sandy exceeded forecasters' expectations, reaching 14 ft (4.3 m) on the evening of Oct. 29, the result was a massive deluge of saltwater into substations and other parts of the area's underground electrical system. As New York Harbor roiled violently and floodwaters rose rapidly, Con Edison made a critical call early that evening: The utility shut down two electrical networks on the southeastern tip of Manhattan and one network in Brooklyn, leaving 6,500 customers in Manhattan and 28,200 in Brooklyn without electrical service. However, these shutdowns likely prevented extensive long-term damage to customer and utility equipment.
Another 11 electrical networks in Lower and Midtown Manhattan were shut down between 8 p.m. and 9 p.m. because of water flooding substation equipment. Shortly after 9 p.m., an additional network, which serves the World Trade Center construction, was removed from service at the customer's request. Power was out as far north as 39th Street to 40th Street on the East Side of Manhattan and as far north as 30th Street to 31st Street on the West Side.
Con Edison includes both submersible and nonsubmersible network protectors on its system. After the worst of the storm passed, and the manholes and vaults were pumped out, Con Edison removed about 200 nonsubmersible network protectors from flooded areas and had them refurbished by its own personnel and by Richards, a New Jersey contractor. The repairs were quick and aligned with customer restoration plans. Since Con Edison also maintains spare breakers and transformers, the utility was able to replace failed devices within a few days. For example, when much of Manhattan went dark due to flooding, Con Edison possessed all the materials and equipment it needed to execute a relatively quick turnaround.
Because Con Edison's equipment is exposed to road salt during winter storms, the utility boasts a storehouse of knowledge about the impact of salt on equipment. Its engineers and operators know distribution bushings and elbows can withstand flooding conditions. But, the utility is investigating the impact of saltwater on other devices. According to Robert Schimmenti, the utility's vice president of engineering and planning, Con Edison intends to investigate design enhancements on transformer bushings to make them more resistant to salt contamination and develop submersible designs for other critical equipment.
Paper-insulated lead-covered (PILC) cables did not pose a significant problem during this event. The Con Edison system operates with limited amounts of PILC cable, relying instead on more dependable, extruded dielectric cables and splices. For the past 11 years, Con Edison has been installing cold-shrink splices, which have performed well, particularly in water-prone conditions. This splice design also is less susceptible to workmanship failures because of its ease of installation, its use of shear-bolt connectors and the pretensioned shrink that seals the joint from environmental elements.
Con Edison brought in thousands of mutual-aid and contractor workers to help restore service to customers following Sandy. Stated Schimmenti, “We brought in underground mutual aid to assist in the pumping out of the manholes and vaults, as well as changing out of network protectors. Crews from as far west as California, as north as Canada, as far south as Florida and Texas came in to give a hand.”
While the damage and outages in Manhattan were flood related, most of the damage in Westchester County was caused by wind. Falling trees caused damage on some Westchester circuits that was so devastating entire lines had to be rebuilt from scratch. Circuits that would have taken two to three months to build on a planned basis were replaced in three to four days.
Looking at the overhead portions of the Con Edison service territory, more than 1,000 poles and 900 overhead transformers had to be replaced, more than five times as many as had been replaced in any previous storm.
Early on in the restoration, a major issue for Con Edison was road closures and toppled trees, which affected 75% of the utility's overhead service territory.
The extensive damage on Staten Island proved to be both wind and flood related. A number of houses in the coastal communities were knocked off their foundations. “Our Con Edison energy service representatives worked side by side with city inspectors and contractors. NYC launched a very successful initiative called ‘NYC Rapid Repairs,’” said Schimmenti.
NYC Rapid Repairs was a huge fast-track effort to bring in rebuild services providers to make homes livable. Services provided included the removal of sheet rock, as well as electrical and plumbing work. Con Edison also worked with the city to expedite the delivery of electricity to hotels under construction so the city could provide temporary housing for displaced residents.
Con Edison restored service to more than 230,000 Manhattan customers. Systemwide, Con Edison restored service to more than 1.1 million customers affected by Hurricane Sandy and the snowy nor'easter that followed the next week. It brought about the largest storm-related-restoration campaign in Con Edison's long history, and there is no close second. Hurricane Irene, the second most devastating storm, knocked just under 204,000 electric customers out of service.