AUGUSTA — Voters will determine in June whether to borrow millions without a tax hike to expand and renovate Lithgow Public Library, city councilors decided at a Thursday night meeting.

If voters approve Augusta’s borrowing plan, the city would issue bonds totaling $8 million to pay for its share of the library project while refinancing $7.6 million in existing employee pension debt.

City Manager William Bridgeo has said all that money could be paid back over 15 years without a property tax increase and with savings atop that, since bond payments and library operating costs would be less annually than what the city is spending to pay off pension debt.

“We’ll never, in the history of the city, have a deal like this again,” said Councilor-at-Large David Rollins.

Construction to overhaul the 118-year-old Winthrop Street building could start in spring 2015 if the issue passes at the June 10 election. The project is expected to cost $11.7 million, including private money, but organizers have said that could be reduced.

Ahead of Thursday night’s meeting, the main issue to be decided was when election would take place. A vote during the June 10 primary election would save the city money on debt service; a vote in the November general election would yield higher turnout.

Councilors voted 7-1 in favor of the plan on Thursday, with only Ward 4 Councilor Mark O’Brien dissenting. Though he said he supports renovation of the library, he had procedural issues with the plan.

O’Brien supported having the election in November, but his motion to move it there failed when no other councilor seconded it. Mayor William Stokes said the public should be well-informed of the vote.

There was also discussion about whether or not to require the Friends of Lithgow Library, the nonprofit group raising money to overhaul the library, to have $2 million or $3 million in hand before city borrowing is triggered.

O’Brien said requiring $3 million “may incentivize people to do more” to raise money for the project. But he withdrew that after the idea was rejected by other councilors, who said the group has been consistent in its projections and thought $2 million was appropriate.

The Friends of Lithgow Library has raised more than $2.3 million in cash and pledges, with about $1.4 million in hand, according to Wick Johnson, co-chairman of the Lithgow project’s fundraising campaign. The group has pledged to raise a total of $3 million for the project.

A similar plan has failed before: In 2007, voters narrowly rejected a proposal to borrow $6.9 million for essentially the same plan to renovate and expand the library. The project would be dramatic.

The Friends’ website says it would double the size of the library, which had 129,000 visitors in 2010, to 30,000 square feet. It would also add a cafe on the main floor and install an elevator, along with other upgrades.

Johnson said the campaign has momentum, saying the Stephen and Tabitha King Foundation recently upped its pledge to the project from $50,000 to $100,000.

He said fundraisers will soon kick off a campaign committee to reach out to Augusta voters about the necessity of the project, saying the June timing “will benefit everyone,” leaving plenty of time to plan ahead of construction.

“The campaign feels this is the right time and the right package,” Johnson said.

Michael Shepherd — 370-7652 mshepherd@centralmaine.com Twitter: @mikeshepherdme