An army of 50,000 restoration workers from across the U.S. and Canada were working on Florida’s power grid at ENR press time on Sept. 12, according to an Edison Electric Institute estimate. Nearly 65% of the state’s electric customers had lost power at the peak of Hurricane Irma’s slam into the southeastern U.S., including 72% of Florida Power & Light customers and 73% of Duke Energy’s.

FPL said it had little damage to generation plants, but it is assessing damage after reports of multiple tornados, said Eric Silagy, FPL’s CEO. The 1,250-MW Riviera Beach gas-fired plant, near Palm Beach, had to be shut due to a huge influx of debris being removed from intakes.

FPL says it expects far less structural damage to the system after spending $3 billion, since 2006, to harden the grid against storms. Upgrades included putting 450 transmission lines underground, replacing poles—many made of concrete—to meet strength requirements and shortening conductor spans. “We would be replacing tens of thousands of poles without the upgrades,” Silagy says. Helicopters and drones inspecting power lines found no structural damage.

Still, the power grid in the southwestern portion of Florida will require a “complete rebuild,” and it likely will be Sept. 22 before all its customers have electricity in the severely damaged area, FPL officials said on Sept. 12. The company, Florida’s largest electric utility, had more than 5 million total outages.

Hurricane Irma had a broad impact zone throughout the Southeast and the Caribbean, with coastal flooding from the Florida Keys to Jacksonville, where flooding along the St. Johns River shattered 150-year-old records, all the way to Charleston, S.C.

Island Devastation

Before hitting the continental U.S., Irma devastated the U.S. Virgin Islands and Cuba. Some areas, especially St. Thomas and St. John, were so severely impacted that FEMA could not give a clear picture of the full extent of damages, said Don Caetano, external affairs director, FEMA, Region II. Irma next struck the Florida Keys, where initial damage estimates show 25% of houses were destroyed and 65% have major damage, reported the agency.

While not the direct hit that Miami officials dreaded, Irma lashed the city with rains and high winds. Two cranes in the Miami area and a third in Fort Lauderdale suffered partial collapses. No injuries were reported, and damage to other structures was minimal, according to local officials.

The two Miami cranes came down at a time when there are about 24 tower cranes working in the city. City officials contacted the general contractors, seeking “the best way to secure the tower-crane arms from collapsing further and get structural engineering reports on the affected buildings,” said Maurice Pons, deputy director of the city’s buildings department. “It’s way too early to determine exactly what happened.”

The three partial crane collapses raised issues related to a long-simmering dispute over crane standards in Miami-Dade County, an area which has one of the country’s densest concentrations of high-rise buildings on coastal properties exposed to hurricane-force winds.

“This has been a big source of anxiety for people downtown,” said Ken Russell, Miami city commissioner for District 2, which includes the sites of the crane collapses. “We were fortunate [the cranes] came down on the buildings that were being constructed and did not strike any of the surrounding buildings, and no one was hurt. But for sure, we as a city are going to look into legislation, regulations and practices in the future about how these cranes are handled during a storm.”

One of the fallen cranes was at the GranParaiso high-rise condominium development. In a statement, lead contractor Plaza Construction said the engineers and supplier took measures to secure the crane. Nevertheless, the boom was damaged due to high winds. In Miami, the other damaged crane was located at a residential tower site, and the Fort Lauderdale crane was working on a beach spa and residence.

Irma’s storm surge also impacted downtown Miami. Russell reported at a press conference that “all along the water­front was completely submerged” after Irma’s arrival, as was the Brickell financial district and parts of downtown.

“Fortunately, we don’t have a Houston situation here because we have a porous oolite limestone, and we have very good drainage systems,” Russell added. “Storm drains were all prepped before the storm so that things could flow as soon as the first low tide came about.” As a result, flooding had fully receded by Sept. 11.

Duke Energy on Sept. 7 suspended work at the $1.5-billion, 1,640-MW Citrus County, Fla., gas-fired plant in preparation for Hurricane Irma but on Sept. 12 returned the site to Fluor, the EPC contractor. Fluor will decide when construction will start again, says Heather Danenhower, a Duke spokeswoman. The project has water on site but did not sustain significant damage.

Meanwhile, Miami Beach—notorious for its flooding problems—escaped much of the storm surge. Where new permanent pump stations had been installed, “they worked well,” says Bruce Mowry, city engineer. For example, the recently raised and largely rebuilt area of Sunset Harbour did not experience significant flooding, he adds. But parts of Miami Beach did have flooding of about 6 in. higher than the city’s king tides last year, he notes.

Still, he says, “We had more impacts than expected, even with Irma moving west,” with downed trees and power lines and knocked-out traffic-signal lights  making up much of the primary longer-term impacts. Most city construction sites, including the city’s $400-million convention-center project, avoided significant damage due to storm preparation made possible by Irma’s relatively slow forward movement. But the $25-million Indian Creek Drive/SR A1A Storm Mitigation project became “fully flooded” because perimeter walls and pump stations were not completely installed along the river, says Mowry.

Marlins’ Membrane

Miami Marlins President David Samson in a statement acknowledged that the  Marlins Park’s 17-acre retractable roof, engineered to resist 146-mph winds, did sustain damage to a membrane that serves to weatherproof the roof structure. “A section of the rubber-and-plastic membrane on the west vertical face of the center panel of the roof will need to be replaced immediately following the conclusion of the 2017 season. This represents approximately 6% of the entire roof membrane,” Samson stated. “Based on our initial assessment today, the building performed extremely well, considering the intensity of the hurricane.”

Matthew Alvarez—a project director for CH2M, which is contracted to operate the North Miami Beach water-treatment plant and other plants—said all are reported operational, including those in heavily damaged Key West. “Our team had a focus on backup power generation, knowing the facilities would likely lose power during the hurricane,” Alvarez says. “We started generators ahead of the storm to ensure that critical pumping systems remained in service continuously so there was no loss of pressure due to unexpected power surges.”

Irma’s shift to the west didn’t spare coastal areas of Georgia and South Carolina, where high winds and surf eroded beaches and flooded roads on several barrier islands. Preliminary reports indicate that the coastal damage, though widespread, was less severe than that inflicted by Hurricane Matthew in 2016.

In Charleston, Irma’s rains and storm surge coincided with an above-normal high tide on Sept. 11, creating a 9.9-ft flood tide, the third highest in the low-lying city’s history. The Concord Street pump station, one of the first components of an ongoing, citywide drainage improvement program begun in 1999, remained in operation through the event.

The city of Jacksonville was dealing with what local officials dubbed “epic river flooding” along the St. Johns River and tributaries, caused by storm surge and flooding from the hurricane.

U.S. Army Corps of Engineers, port survey personnel, and power, debris-removal and roofing teams are in Florida and Georgia, the Dept. of Defense reports. Work includes efforts to reopen ports in Port Everglades and Tampa.

By Scott Blair, with Scott Judy in Ormond Beach, Jeff Rubenstone, Mary Powers, Debra Rubin, and Jim Parsons