MILLINOCKET – A Central Street building will undergo extensive renovation as part of a $500,000 plan to expand and relocate occupational and physical therapy services offered by Millinocket Regional Hospital, officials said Monday.

Under the plan, the White Birch Medical Center at 899 Central St. will be the new site of most of MRH’s occupational and physical therapy work. The hospital’s existing PT space at 200 Somerset St. will be converted into office space for internal medicine specialists, Marie Vienneau, the hospital’s chief executive officer, said.

“Our current physical therapy space is the oldest department in the hospital. It’s the only one not renovated since 1978 or so,” Vienneau said Monday. “It’s very cramped. There’s not a lot of privacy for patients and it doesn’t have a great work flow.”

Combining the new White Birch with patients and services offered at the Facility of Occupational and Rehabilitative Medicine, or FORM, on Connecticut Avenue, another part of the plan, in a space designed for all those services would further improve efficiency while solving the lack of privacy and good work flow, Vienneau said.

Hospital officials also hope to add another service, for speech therapy, when they hire a therapist, she said.

An indoor pool would be added to White Birch as part of the plan. The hospital’s inpatient PT services will stay at the hospital, Vienneau said.

Hospital officials hope to go out to bid on final construction designs in January. The work will begin by early spring and finish by fall if all goes well, Vienneau said.

The hospital has undergone periodic but extensive renovations for several years, the most recent being a lobby redesign finished in September, Vienneau said.

Hospital officials also hope to add a helipad to the hospital grounds for patient transportation service, said David Nelson, the hospital’s director of public relations and Millinocket’s Town Council chairman.

How all the work will be paid for is still an open question, Vienneau said. The hospital could mortgage some of its property or apply for loans.

Jeannette Ruhl, the hospital’s director of rehabilitative services, could not be reached for comment Monday.