AUGUSTA -- Two top utility officials today will unveil details of a planned $1.9 billion overhaul of Maine's bulk power transmission system.

The initiative, which Maine Public Service President and CEO Brent Boyles and Central Maine Power Co. President Sara Burns will discuss in a Statehouse press conference this morning, is an effort to address a growing population's increasing dependence on an electrical grid largely unchanged since 1971.

The state's electrical-transmission infrastructure relies on a 345,000-volt line that stretches from New Hampshire to New Brunswick. Near Bangor, it splits into two separate transmission lines.

The 345,000-volt lines supply power to a network of 115,000-volt lines that deliver power locally.

The overhaul would add nearly 500 miles of both types of electrical lines. It would also provide the infrastructure for connecting a series of wind-energy projects in Aroostook County to the state's grid.

"What they're trying to do is create some redundancy," said Sue Bell, a senior project manager for the firm Bernstein Shur.

Since 1971, the state's electricity use has doubled while the population has grown 32 percent and migrated south and toward the coast, according to the Maine Power Reliability Program, a 10-year forecast assessing power availability and need in the state.

The assessment found the state's transmission system could easily find itself unable to handle interruptions due to a reliance on one line, Bell said. It also identified the areas of the state with the highest electricity demand -- mostly areas with higher populations or more industrial activity.

The existing system has "served reliably and well, but there's some concern that if any equipment failed or something happened to that line, we'd experience a blackout for a number of days or longer until that problem could be addressed," she said.

Analysts conducting the assessment found the utilities need to make major investments by 2012 to handle rising demand in the targeted areas.

"There's some urgency in addressing the needs analysis," Bell said.

The proposed project would install a new 345,000-volt line from Bangor through Kennebunkport to the New Hampshire border. The line would pass through 80 municipalities in the Detroit-Pittsfield, Waterville, Augusta, Lewiston-Auburn and Portland areas.

Bell said CMP planned to file an application with the state's Public Utilities Commission this month and another application with the state Department of Environmental Protection in the fall. The company would also need local clearances to construct the line in the 80 municipalities targeted.

"It's a significant project in terms of keeping the lights on, looking at the affordability, the electrical performance; looking at the environmental impact and the local impact," Bell said.

If project planners can demonstrate other states in New England will benefit from the overhaul, ISO New England, a private body that oversees the region's electrical grid, could provide 92 percent of the project funding.

"That's a significant part of the feasibility of this project," Bell said of securing that funding.

Matthew Stone -- 623-3811, Ext. 435

mstone@centralmaine.com