BANGOR, Maine — Residents opposed to the plan to double the capacity of Juniper Ridge Landfill in Old Town expressed concerns this week at a two-day public hearing at the Cross Insurance Center hosted by the Maine Board of Environmental Protection, which is tasked with deciding whether the expansion is good for Maine.

Casella Waste Systems, the company hired to operate the state-owned landfill, and the state Bureau of General Services filed an expansion application with the Maine Department of Environmental Protection in 2015 to add 9.35 million cubic yards to the landfill’s existing permitted 10 million cubic yards.

About 35 people spoke at the citizen-led environmental board’s hearing.

The “proponents said the expansion is needed because if it isn’t approved, those using it will have to find another landfill, which is now expensive,” Don Meagher, manager of planning and development for Casella Waste Systems, said Wednesday after the two-day hearing ended.

“The opposition was all about water quality — protecting the river, the Penobscot River, and other natural resources,” Old Town resident Cheryl Spencer said after the hearing.

The state acquired the former Georgia-Pacific Corp. landfill in May 2003 to help keep the Old Town mill operating and selected Casella to operate the facility. It was renamed Juniper Ridge Landfill in 2005, after the state and Casella acquired a permit to increase its capacity from a 3 million cubic yard landfill to one that could handle 10 million cubic yards of trash.

In January 2012, Casella and the state received partial approval from the state Department of Environmental Protection for the expansion at the 64-acre property located near exit 199 on Interstate 95, but that application was later removed by Casella and resubmitted last year.

The Maine Department of Environmental Protection estimates Juniper Ridge will reach existing landfill capacity in 2019, at current fill rates of 675,000 tons annually. Based on this usage, the department projects that the 9.35 million cubic yard expansion would extend the landfill’s life by eight to 10 years.

Charles Leithiser, an Old Town resident who sits on the Juniper Ridge Landfill Advisory Committee, said that citizens have been told the site is “hydrogeologically speaking, ‘perfect,’” but he worries about what happens when “millions of tons of waste are piled on top of it.”

“It makes no sense to try to improve the water quality of the river on one hand while simultaneously allowing contaminated water from the landfill into the river with the other hand,” Leithiser said of the possibility leaks at the landfill.

Orono resident Paul Schroeder spoke at the public hearing and also submitted a thick packet of information to the board, which he called a one-year timeline of activities at Juniper Ridge.

“Before they expand [the landfill], they should have a good idea of how it came about,” Schroeder said of the rationality for submitting his timeline.

Climate change and eliminating controversial out-of-state waste were two other things residents expressed concerns about, Spencer said.

Juniper Ridge now accepts out-of-state waste after it has been “processed” in Maine.

“If something comes from out of state and touches Maine ground, it become Maine waste,” Old Town City Manager Bill Mayo said.

That stipulation has upset residents for years, Spencer said.

“Does that make sense to anybody?” she asked. “Casella is very creative in their labeling.”

Leithiser said Juniper Ridge operators have been accepting out of state waste for years, and he estimates that “between one-third and one-half of the waste disposed of at Juniper Ridge did not become waste within Maine’s borders.”

“Tightening the regulations around what is supposed to be ‘in-state waste’ only would greatly reduce that amount of landfill space needed in the future,” said Leithiser.

Before the board ended the public hearing on Wednesday, it discussed in-state and out-of-state waste, and board Chairman James Parker asked that the definition of municipal waste be better defined.

The expansion application will be considered by the Board of Environmental Protection, which may have a draft decision by the end of the year, said Cindy Bertocci, analyst for the board.

“By the end of the year, we’ll certainly have a decision,” she said.

Bertocci said the state accepts public comments on draft decisions, which means a final decision will not take place until 2017.

“People don’t realize how complicated trash is,” Mayo said. “If you follow your Dorito bag from your trash can to the landfill, it’s a very complicated issue.”