Plans to expand Catholic Medical Center include demolishing a strip mall housing Rite Aid and building a new store on the site on Manchester’s West Side.

MANCHESTER — Catholic Medical Center is moving forward with plans for building up to a six-story addition and demolishing a nearby strip mall in a project estimated to cost $125 million to $175 million.

Plans include expanding the emergency room and the New England Heart & Vascular Institute as well as adding up to 90 private rooms and six new operating suites.

“I think it’s going to be a significant project for the West Side,” Alex Walker Jr., CMC’s executive vice president and chief operating officer, said in an interview Monday.

“That corner, Amory and McGregor, in a lot of ways is the gateway to the West Side,” Walker said.

Hospital representatives have filed paperwork with the city requesting variances to regulations that include building heights, landscaping and off-site loading requirements. The Zoning Board of Adjustment is expected to consider the request in May.

Walker said he hopes the project could be completed in mid-2022. A possible parking garage, which the hospital is seeking permission to build, isn’t part of the cost estimate or within the 2022 timetable, he said.

Ron Covey, president and CEO of St. Mary’s Bank, said the project will allow more access from Amory and McGregor streets and include a dedicated drive-thru lane for St. Mary’s.

The change would “make it a lot more convenient,” Covey said. “Security will be better” since the partially vacant strip mall attracts people loitering.

Construction could start this summer on demolishing the vacant portion of the strip mall. A new Rite Aid, to be built in the existing parking lot, could open in 2020, followed by demolition of the existing Rite Aid store.

CMC would build its addition — 220,000 square feet of new space — on the western side of the property north of the hospital.

CMC officials have had “our sights on this particular parcel to redevelop for the past five years,” Walker said.

In January, CMC officials told the New Hampshire Union Leader it wanted to expand and make other renovations with a possible $175 million price tag.

CMC has 330 licensed beds and staffs about 260 of them. Plans call to add up to 90 rooms on three patient floors.

“The patients we see are among the sickest patients from around the state,” Walker said. “We are at capacity just about every night of the week.”

Demographic changes show the state’s population is aging, and “as we get older, we get sicker,” Walker said.

The hospital also would like to start converting existing semi-private rooms to private rooms. Plans call for building private rooms as part of the addition, he said.

CMC would own the land under the new addition. The $125 million to $175 million cost includes the site’s infrastructure work, building the new Rite Aid and the hospital addition, Walker said.

CMC had considered plans to locate certain outpatient services in a proposed medical building at the Tuscan Village multi-use development in Salem in a possible partnership with Massachusetts General Hospital.

But CMC officials decided to concentrate on its Manchester campus instead, according to Walker.

Michael Morrison, director of media relations at Massachusetts General Hospital, said “the hospital is currently considering the possibility of occupying a medical building at the Salem, N.H., location but no final decision has been made at this time.”

Last week, Tuscan Village developer Joe Faro told Salem officials that two medical buildings were planned.

Union Leader Reporter Mark Hayward contributed to this story.