No guarantee: Underground utilities are not a perfect science

Lisa Parsons was startled to see her power fade to black before Hurricane Milton swept across the state directly through Brevard County.

"I thought it wasn't supposed to go out if the electric lines are underground," she said.

She wasn't the only one, no doubt.

"The hurricane wasn't even here yet, and the power went off. Weird," said her husband, Mike, who suspects Florida Power & Light Co. shut it down to avoid excessive damage before Milton's 60 mph gusts and about 7 inches of rain barreled through their Palm Bay neighborhood.

The undergrounding of utilities, such as electric cables, is not a perfect science, according to several experts and some past examples. It's something to keep in mind as Key Biscayne focuses its effort on underground utilities (at least in Zone 1 around the K-8 Center for $75 million) as part of the Village's Resilient Infrastructure & Adaptation Program (RIAP) , which also includes telecommunications and cable lines, and potential improved stormwater drainage.

Just last year, when Hurricane Idalia's storm surge flooded Longboat Key, south of Anna Maria Island, 20 underground transformers failed, according to a report in the Longboat Observer . It left some 400 FPL customers without power for about 15 hours.

"This system is the best we can put in, but it's not perfect, and there's going to be failures," Robert Gaddis, director of FPL's Storm Secure Underground Program, said in that report.

He said the transformers were never meant to be fully submerged, and probably no system could guarantee against some kind of outage in that scenario.

Gaddis could only guess that saltwater interacted with certain metals, but a full forensic investigation months later revealed "accelerated corrosion within the transformers" caused outages during Idalia's storm surge. The report noted that new transformers had been in place only six months.

In response to several Islander News questions, FPL spokesperson Conlan Kennedy said, "Underground power lines perform significantly better than overhead lines during hurricanes and on a day-to-day basis. FPL (the nation's largest utility company) has been installing underground service for decades. Approximately 50% of our distribution system is underground."

Kennedy, however, did not answer whether FPL could pull the plug before threatening storms or if telecommunications lines could be affected the same way.

To solve Longboat Key's issue, Gaddis said FPL would have backup and replacement transformers ready. He also said FPL aims to harden the entire state's utility infrastructure with underground lines.

"How is it possible that we're going to harden the whole state when we can't get a 10-mile island done?" Mayor Ken Schneier told The Observer last year.

According to the Village of Key Biscayne's website on why utility undergrounding is the choice, "burying them underground means a safer, more reliable, more resilient and more beautiful Village for residents and visitors."

All of those assumptions cannot be argued.

Kennedy said FPL has two programs: one is called the Storm Secure Underground Program to harden areas with a history of outages, and the other for municipality-community requested changeovers, such as Key Biscayne.

Typically, the transformation includes main or "feeder" lines as well as neighborhood power lines or "laterals" (usually done simultaneously with telephone and cable lines). Costs are paid by the municipality that wants to convert to underground (as opposed to an added surcharge for each household). Discounts are available per the FPL tariff, and most costs are recovered through a special assessment on their taxpayers/community members.

According to a web story by the WGI Engineering firm in West Palm Beach from a few years ago, underground power lines cost five to 10 times more than overhead wires, but they don't last as long — "a fact that would surprise most consumers."

The report noted that it typically costs approximately $750,000 per mile to bury above-ground power lines in rural areas and $1.4 million per mile to bury them in urban areas.

In addition to the upfront costs, "other disadvantages include a shorter lifespan for cables (20 to 30 years noted in several other analyses); the danger of accidental damage to cables by road construction or other digging; vulnerability to floods; and the fact that if damage does occur, repairs can be costly and take considerably longer (60%) than overhead cable repair."

Those disadvantages echo a similar refrain with buried telecommunications and cable lines, including the potential degradation of the sheathing material around the cables due to excessive heat or cold, weather conditions, and even rodents building nests in equipment or cabinets, causing faults.

Because other electrical system components have to remain above ground, there can be possible damage to high-voltage transmission lines, substations, switching cabinets, and transformers, which almost always require an easement.

Should replacement or repairs be necessary, the maintenance cost (queried by a few Village Council members) should be explained before the burying of lines.

According to FPL's website, approximately 67,000 miles of distribution lines serve its 4.7 million customers in all or parts of 35 counties in Florida. Included is the installation of more than 66,000 intelligent devices that help reduce and prevent power outages, as well as the strengthening of more than 700 main power lines and poles.

And it's not just in Florida where underground systems are being installed.

A study by Northern Lights Inc. , in Sagle, Idaho, called underground lines "a trade-off between fewer outages and time-consuming repairs."

Similarly, the Utilities in Lake Tahoe, CA, report noted that "While undergrounding may seem like a logical solution, there is more to consider."

In geographical areas with a high water table or rocky subsoil, undergrounding is not a viable option, its report read. "Although under-grounding may eliminate the causes of some outages, underground cable and equipment can still fail, and other issues can lead to power outages. Underground outage repair time is often three to four times longer than overhead outage repair time."

That report listed several things to consider before transitioning to underground utilities:

Cost: Underground utilities are expensive to install and maintain, costing up to 10 times more than overhead utilities.

Lifespan: Underground utilities don't last as long as overhead utilities. After 20 to 30 years, underground cables can develop cracks in the insulation, which can lead to faults.

Damage: Underground utilities can be damaged by road construction, digging, flooding and other natural disasters.

Repairs: Repairs to underground utilities can be costly and time-consuming. It can be difficult to locate the exact spot of a malfunction.

Geological conditions: Underground utilities can be impractical in areas with flooding, rocky subsoil, boulders, or bedrock.

Moisture ingress: Moisture can cause short circuits and corrosion of copper conductors.

Excessive heating: Excessive heating can degrade the insulation and sheathing material.

At least during Hurricane Milton, where the Parsons family lives in Palm Bay, they didn't take long for them to see the light.

"We're grateful that they had the power restored by the next day (after the storm passed)," Lisa said.