PORTSMOUTH — The long-running public debate over installing sewers in the north and west sides of town, interrupted last fall, won’t resume anytime soon, at least not in time to put a referendum on the November ballot, says Town Administrator Robert G. Driscoll.

A preliminary version of a wastewater facilities plan — the document necessary for estimating construction costs — was prepared for the town last fall but did not include the Common Fence Point neighborhood at the north end of town, to the consternation of the director of the state environmental agency.

The Town Council agreed to add Common Fence Point to the study, a step that requires additional work by the town’s consulting engineers, Woodard & Curran.

Driscoll, the town administrator, said the scope of that additional engineering work has not yet been decided.

“There’s a fair amount of contention as to how much planning work is necessary,” he said.

The back-and-forth involves the state Department of Environmental Management, which would pay for part of the added work, and the consulting engineers, Driscoll said.

In addition to Common Fence Point, Driscoll said, there is discussion about any additional engineering work necessary regarding 10 other small neighborhoods or “cluster areas” in town previously identified as “needing some sewer solution beyond individual septic systems,” Driscoll said.

“The more tortured parts of the work involve those potential cluster areas,” Driscoll said.

Because these areas may not need attention for another 10 years, one opinion holds that they do not need to be studied now, he said. But there is not unanimity on this point, he said.

“We need to see the amended scope of the work before we can determine a price tag” for wastewater facilities plan, Driscoll said. He estimated the amendment would cost between $60,000 and $90,000.

A DEM spokeswoman said yesterday that the agency can’t say how much of the additional engineering work it will cover until the cost of the amended facilities plan is determined.

But DEM is “committed to helping the town,” said DEM spokeswoman Gail Mastrati.

DEM remains very concerned about the significant erosion of water quality in Mount Hope Bay and the surrounding areas, and will work to invest with the town and the local citizenry to help stop or reduce adverse impacts to water quality,” she said in a statement.

Driscoll, meanwhile, said the wastewater facilities plan will serve as a basis for determining the cost of sewer construction.

Without having fixed cost estimates, the town had scheduled a sewer referendum last November, an approach criticized by DEM director W. Michael Sullivan.

Sullivan said at the time that voters needed more complete information to make a decision, and the Town Council called off the referendum.

Driscoll said he expects the facilities plan to be completed by the end of the year and a referendum to be rescheduled for 2009.

“When you give people time to thoroughly discuss something, they take the time allotted,” he said.

“And on a big topic like this, why not?” he said. “This is even more complicated than we thought,” Driscoll said.

gmacris@projo.com