GROTON — The Sewer Commission voted to set betterment rates for scores of property owners along Boston and Old Ayer Roads, where construction of new extensions to the town’s sewer system has recently been completed.

Although rates for Boston Road had not been contested by residents, those proposed for Old Ayer Road were opposed by resident Gerard Gingras.

Gingras appeared at an earlier meeting of the commission to register his complaint that $20,000 being charged to property owners, for repaving the road following installation of the new sewer system, was unfair.

In particular, Gingras complained that the extra charge for repaving, which would come to about $2,200 for each of nine property owners along Old Ayer Road, was without precedent and was not approved by residents at town meeting when they voted to accept the extension plans and set the cost for the sewer construction.

Highway Surveyor Thomas Delaney had asked the Sewer Commission to add the extra charge to the betterment fee to be paid by residents of Old Ayer Road to cover the cost of repaving the street after construction was concluded.

Although sympathetic to Gingras’ complaint, commissioners told him that there was little they could do about the charge but that perhaps Delaney could be persuaded to change his mind if enough property owners voiced their concerns to him.

But as of the commission’s meeting of July 24, Delaney had not changed his position on the issue. When the commissioners voted to set the betterment rate for Old Ayer Road at $308,063, the $20,000 charge for repaving was still included.

Delaney said he had spoken to Gingras about the issue, but he had not received any calls from other residents of Old Ayer Road.

The Highway Surveyor confirmed that he had not changed his mind on the issue, insisting that there is a precedent for charging ratepayers directly for road improvements following the installation of utilities. He cited past extensions of the town’s water distribution system as an example.

Delaney insisted that the $20,000 charge represented a good price for property owners, who saved up to 20 percent on the cost by having the town do the repaving and using its own contractors to do the work.

“I’m inclined to keep the old numbers,” said Commissioner James Gmeiner of the betterment rate that included the cost of repaving. “I think we’re getting a good deal at $20,000.”

With their vote last week, commissioners set the betterment fee for residents of Old Ayer Road at $34,229 per household. That amount will pay for the repaving as well as construction costs and the cost to the Sewer Department to purchase added capacity at the Pepperell treatment facility where Groton sends its wastewater.

At the same meeting, the commission also voted to set a betterment rate for the 28 property owners along Boston Road, for whom repaving would not be an issue. The state, which has jurisdiction over Route 119, has informed the commission that there will be no need for the town to repave the road after work is completed.

For property owners on Boston Road, which include Sacred Heart School, CVS, the Emerson Building, Groton Community School and various residences, the total estimated betterment will come to $844,707.

Individual rates will range from an average $21,481 for residential homes to $45,451 for the Emerson Building to $75,413 for the Sacred Heart School. The Post Office building will be charged only $3,024 to cover the cost of capacity at the Pepperell plant.

With last week’s voting, the board of assessors will be notified of the new rates by Aug. 15, followed by the town treasurer, who will notify ratepayers of the decision and provide information on how property owners may choose to pay for the betterments. The first installment paid by property owners, covering the first half of the year, will appear on the February 2008 tax bill.