The October snowstorm alone resulted in 700,000 public utility customers statewide without power.
SPRINGFIELD – The thought, “Why don’t they just bury the power lines,” crossed the minds of everyone left cold, wet, hungry and miserable by October’s freak snowstorm, as well as those whose lives were disrupted by Hurricane – turned tropical storm – Irene in August and by the tornadoes in June.
But, burying those power lines would probably result in trading one set of maintenance headaches for another, all at considerable expense, according to utilities and engineers.
“It’s not only expensive, but underground lines can be difficult to get to in case something goes wrong,” says Peter A. Wozniak, senior engineer at Tighe & Bond in Westfield who has spent 43 years in the profession.
Where underground lines are most often used – urban areas, shopping malls, new and densely-built housing developments – it’s aesthetics, not reliability, which justifies the added expense.
The October snowstorm alone resulted in 700,000 public utility customers statewide without power. In Western Massachusetts, that number included more than 200,000 National Grid and Western Massachusetts Electric Co. customers. Some had to wait more than a week for power to be restored.
Northeast Utilities, WMECO’s parent company, said its recovery costs from the October storm will be about $202.5 million. Most of that – $162.8 million – is for restoration efforts at Connecticut Light & Power. About 830,000 Connecticut customers were without power.
Northeast Utilities said $23.5 million will pay for restoration costs at Western Massachusetts Electric and $16.2 million for a third subsidiary, Public Service Co. of New Hampshire.
Underground lines like the ones the company maintains in downtown Springfield and downtown Pittsfield cost 10 times what a comparable above-ground system would cost to install, according to Sandra Ahearn, spokeswoman for Western Massachusetts Electric Co. here in Springfield. She estimated the cost at $630,000 a mile for overhead lines and $6.3 million a mile for buried lines.
The Edison Electric Institute, an organization funded by investor-owned power utilities, estimated costs at $150,000 to $5 million per mile for overhead wire systems. Likewise, underground conduit costs from $5 million to $23 million per mile, according to a 2009 report.
In addition, underground lines have a life expectancy of only about 30 years versus 50 years for overhead wires, according to the Edison Institute.
Wozniak said much of that added expense comes in the high cost of buying rights of way for underground lines. The work is also more difficult and time consuming, Wozniak said. Materials costs can also be higher.
But, it’s better to have buried wires in a natural disaster, correct?
Not so fast, says the Edison Institute. Hurricanes lead to floods which can damage underground systems.
Customers depending on a damaged underground line might have to wait longer for a repair than their neighbors with overhead wires, noted Wozniak. Buried cables take longer to access.
Ongoing maintenance problems for underground power systems are largely the result of heat, he said. Electricity passing through wires generates heat. In an overhead system it dissipates, while underground cables are sheathed and run through a conduit to keep them dry. That also allows heat to build up and, over time, cause damage.
Heat build-up also keeps underground cables from carrying as much power as overhead lines, he said.
Frost heaves in the spring also damage underground cables, according to Wozniak. Power lines can’t be buried deep enough to avoid frost, he said.
The Edison Electrical Institute also points out that electricity gets to underground systems via overhead lines.
One solution can actually be much simpler, notes Wozniak. Utilities need to trim trees so limbs are further away from power lines, he said.
“I think the utility companies need more resources to do that kind of maintenance work,” Wozniak said.
