ROCKLAND, Maine — The former limestone quarry that has been used for generations to dispose of a wide range of waste is expected to be filled in fewer than six years.

The quarry is used only for demolition debris. A policy debate over the past decade has focused on whether the city should reserve what space is left for Rockland residents only or allow outside contractors to dump wastes as a way to make revenue for the city.

The city received a memo in April from the engineering firm of Woodard and Curran concerning the firm’s latest estimate on the lifespan of the quarry landfill.

The study found that 147,300 cubic yards of space are left. Based on a projection of 25,000 cubic yards of wastes to be disposed of annually, the landfill likely would be filled in five to six years, the memo concluded. The estimate presented to city officials in April was based on residential use and a projected amount of outside contractors.

The issue of the city’s management of the landfill arose at the city council’s Wednesday night meeting, when councilors authorized the city manager to sign contracts with two outside contractors for demolition debris disposal in the quarry.

That move was sharply criticized by former Councilor Adele Grossman Faber.

“Since 2004, I — as a councilor and then as a citizen — have spoken out against the sweetheart deals at the landfill. These contracts defy reason,” Faber said.

Faber said the city is selling the space at far too low an amount and that the city should not try to compete with waste company Casella Waste Systems by offering such a low price.

The former councilor said it was irresponsible to sell the space when the city would have to pay considerably more money for disposal and transportation of demolition debris when the quarry is filled.

The contracts with Troiano Waste Services Inc. of South Portland and Jeffrey A. Simpson Inc. of Sanford call for the companies to pay $31 per ton for the first year, $32 for the second year and $33 for the third and final year of the contracts. Troiano is expected to dispose of 10,000 tons annually and Simpson 2,000 tons per year.

Councilor Larry Pritchett said there have been huge environmental and air quality benefits to filling the quarry to the point at which it is now. He also pointed out the economic benefit.

From 2008 through 2015, the city has received $7.3 million from disposal contracts. That money largely has been used to pay for operations at the landfill and remove that expense from property taxpayers.

The city has set aside $336,000 since 2008 for the eventual closure of the landfill. The cost of closing the dump is estimated to be up to $1.8 million. A legislative measure expected to be signed into law would reimburse communities 75 percent of their dump closing costs.