BANGOR, Maine — Ron Gastia won’t be retiring as Bangor’s police chief until the end of September, but the city already has someone lined up to serve as his interim replacement until a permanent chief is named.

Deputy Chief Peter Arno, a 25-year veteran member of the Bangor Police Department, was unanimously approved by the Bangor City Council as the department’s interim chief Monday night.

“Peter’s the deputy chief, so he was the logical person to step in,” said Cathy Conlow, Bangor’s city manager. “He’s agreed to serve as interim chief through March, which buys me a little bit of time to get through the fall and holiday season to get the ad done and conduct a thorough search.

“Hopefully, we will have a permanent replacement named by the first of the year,” she said.

Gastia is retiring at the end of September after a 30-year career with the Bangor Police Department.

Arno, who was promoted to lieutenant to replace Bob Welch back in the fall of 1998, took over the deputy chief’s position in 2002. He applied for the position of Bangor police chief in 2007, but elected to withdraw his name as a candidate shortly afterward.

“My experience with Peter is he’s very thoughtful and does a good job of balancing the needs of the community with his managerial duties and serving as a liaison with city officials,” Conlow said.

Arno, who has served as a field office supervisor in the Bangor office of the Maine Drug Enforcement Agency, has extensive investigative experience. He also worked under the federal drug task force with Gastia in the early 1990s.

“He’s seen it all and done it all,” said Conlow. “With that job, you have to be hands-on, delegate, be mindful of politics and be managerial as well. Being the police chief is a hard job.”

Conlow said she and city staff members are closing in on naming a new fire chief within the next month or so.

“I’d like to get the fire chief done soon. We have candidates and just finished up the second part of the process,” Conlow explained. “We have seven remaining candidates and would like to thin that to four or five semifinalists.”

Semifinalists will be scheduled for interviews over the next few weeks.

“We’d like to have someone named as the new chief by late September,” Conlow said.

The fire chief’s position has been vacant since Jeff Cammack retired in late February after 32 years as a firefighter, the last 15 as chief.