A Vancouver, Washington, company wants to build a 150-unit independent senior housing complex off outer Ocean Avenue in Portland, on a site where the City Council last year rejected a proposal for a 96-unit condominium development.

Hawthorn Retirement Group already operates two assisted-living communities in Maine – Birchwoods at Canco in Portland and Winterberry Heights in Bangor – and it built and previously owned the Woods at Canco independent living community in Portland.

Hawthorn’s proposal for 802-828 Ocean Ave. is one of several senior housing projects proposed or under construction in Greater Portland, each of them answering a growing demand fueled by Maine’s rapidly aging population.

“There’s a great need for senior housing and we’ve enjoyed operating in Maine,” said Larry Wright, Hawthorn’s spokesman.

Hawthorn submitted the proposal to Portland’s planning office last week and is seeking a zoning text amendment to allow congregate housing on the 18-acre property. City planners have started reviewing the proposal, but a hearing date before the Planning Board has yet to be scheduled.

Maine’s aging demographics are driving demand for senior housing. Maine has the highest median age in the nation – 43.9 years – and the second-highest proportion of people age 65 and older – 17.7 percent. Only Florida’s is higher at 18.6 percent, according to the U.S. Census.

Maine also has the nation’s highest proportion of baby boomers – 29 percent of its 1.3 million residents were born between 1946 and 1964 – and they’re turning 65 at a rate of 18,250 a year, according to AARP Maine. By 2030, more than 25 percent of Mainers will be 65 or older, magnifying the already serious challenges facing seniors and their communities.

The wooded site off Ocean Avenue has been targeted for development for more than a decade. In 2004, the council approved a conditional rezoning that would have allowed Saco developer Diane Doyle to build two nine-story residential towers, each containing 49 condos. Last year, the Planning Board and the council rejected a rezoning amendment that would have reduced the number of condos to 96 but would have expanded the project’s footprint.

Hawthorn has negotiated a purchase-and-sale agreement to buy the property from Doyle for an undisclosed price.

Hawthorn is a family-owned business that has built about 400 retirement residences across the United States, Canada and England and currently operates 48 of them, Wright said.

Hawthorn’s proposal in Portland calls for building an access road next to Ridge Road, according to the company’s application for a zoning change. The four-story building would be built on 10 acres and eight acres would be maintained as open space. The footprint of the building would be 40,000 square feet.

The building would include studio, one-bedroom and two-bedroom apartments that would rent for $1,995 to $4,100 per month, Wright said. That’s an all-inclusive rate that would cover three daily meals served in a restaurant-style dining room, a live-in management team, weekly housekeeping service and regular maintenance service for everything from fixing a toilet to moving a sofa.

Personal and home health care services could be contracted through an on-site provider or an independent provider, Wright said. The property also would offer laundry service, social programming, a movie theater, gym and shuttle service to errands and appointments.

About 20 percent of residents at Hawthorn’s other properties keep their cars after moving in.

This story was updated at 8:40 a.m., March 17, to correct the number of condos approved for Saco developer Diane Doyle.