SOUTH PORTLAND — A Colorado company is expected to begin construction this summer on a 120-unit assisted-living and memory-care facility on property that was part of the former Sable Oaks Golf Club.

The $40 million project at Running Hill and Country Club roads – at the entrance to the golf club property and across from the Target shopping center – is the first of several residential proposals that are anticipated on the 179-acre parcel near the Maine Turnpike and the Maine Mall.

Confluent Development LLC of Denver is expected to submit final subdivision and site plans for the senior living community this month, with a goal to start work on the 6-acre site by summer, according to Planning Director Tex Haeuser and the company’s project application to the city.

The Planning Board voted 7-1 last month to grant preliminary subdivision approval to HarborChase of South Portland. The 115,000-square-foot building will include 80 assisted-living apartments and 40 secure memory-care apartments for people who have Alzheimer’s disease and other forms of dementia.

In 2017, the City Council rezoned the golf club property from Professional Office District to Suburban Commercial District to allow for mixed-use redevelopment. Ocean Properties, the New Hampshire company that owns Sable Oaks, told city officials it needed the zoning change to make way for more than 300 housing units.

Still, the company disappointed the club’s 200-plus members when it announced in January that it would close Sable Oaks after three decades, a casualty of a decadelong decline in the number of golf courses nationwide.

HarborChase of South Portland, meanwhile, is responding to the soaring senior demographic. Maine’s population is now solidly the oldest in the nation, with the highest median age of 44.7 years – meaning the younger population is dwindling – and tied, with Florida and Montana, for the largest proportion of residents age 65 and older – 19 percent of the state’s 1.3 million people, according to the U.S. Census.

Looking ahead, Maine’s senior population is projected to grow 41 percent over the next decade, from 270,229 in 2017 to 381,870 in 2027, according to a 2018 report from the Muskie School of Public Service.

The proposed building will be a one- to three-story, shingle-style mansion with architectural features common on the coast of Maine, including a sloped roof, a covered porch and large overhangs and balconies, according to EGA Architects of Newburyport, Massachusetts.

The assisted-living apartments will be in the two- and three-story sections of the building, with common areas such as a lobby, bistro, community room, resident lounge, activity rooms, dining rooms, a salon and a wellness suite.

The memory-care apartments will be in one-story wings arranged around a central courtyard that will be used by all residents. That section of the building will include a country kitchen, living rooms, dining rooms, an activity room and a personal care room.

The facility will have surface parking with 93 spaces and will require a variety of permits to address drainage, wetlands and other concerns. Approvals from the Maine Department of Environmental Protection are expected in the fall, according to the developers. Construction would be completed by summer 2020.

This story was changed at 7:30 p.m. on March 14, 2019, to correct the square footage and parking plans for the facility.