PITTSFIELD — The last time Sebasticook Valley Health underwent a major renovation was 1993, the hospital’s 30th anniversary.

Plans are now on track for a $9.5 million upgrade to the hospital’s medical-surgical inpatient unit and $2.5 million worth of improvements to the infrastructure and utilities.

Work is scheduled to start in June, and construction completed by the fall of 2013, the hospital’s 50th anniversary.

Sebasticook Valley Health President and CEO Victoria Alexander-Lane emphasized that that the hospital was not expanding, but making necessary renovations.

“This is actually a two-part renovation: the medical-surgical unit and physical plant,” Alexander-Lane said. “The boilers are 40 years old, and the rooms are in need of a major upgrade.”

The hospital will still have 25 beds, but five will be converted into two-person “super suites” with two separate bathrooms and a partition that can be used for privacy.

After a brief public hearing on April 9, the Planning Board approved the hospital’s site plan application on the condition that a full set of blueprints will be available before the actual building permit is granted.

The revamped inpatient medical-surgical unit will be between 12,000 and 13,000 square feet larger than the present space, according to Michael Peterson, hospital vice president of ancillary and support services.

“The rooms will start in the same location in the hospital, but expand westward,” Peterson said. “The total project will add approximately 33,000 square feet to the hospital.”

Chris Osterrieder of DeLuca-Hoffman Associates, the project engineer, said that all permits have been approved from the Department of Environmental Protection and the process “was very thorough with very stringent controls.”

Michael A. Gallagher, vice-chairman of the hospital board, said that the renovation project “was scaled back somewhat from its original plan due to costs and other factors. But it will meet our current needs as well as our future ones.”

Sue diRosario, the hospital’s director of marketing and development, said the capital campaign for the renovation will get under way soon.

Sebasticook Valley Health has approximately 355 employees. Its services include a women’s health center, special care unit, rehabilitation centers, a sleep study center, diabetes and nutrition clinics and walk-in-care medical offices in Clinton, Newport and Pittsfield.