Stonington — Hartford HealthCare, the parent company of the William W. Backus Hospital, slowly has been expanding its medical offerings over several years in the shoreline area traditionally covered by Lawrence + Memorial Hospital, which is affiliated with the Yale New Haven Health System.

Construction is expected to start in September on a new development in Pawcatuck that will house yet another shoreline Hartford HealthCare facility, a medical office building that a company spokesman said will include primary care offices, specialty care and physical rehabilitation.

The company will close its primary care offices in North Stonington and relocate and expand them two miles south at the Pawcatuck location, said Shawn Mawhiney, a spokesman for Hartford HealthCare.

"We are trying to grow our presence along the shoreline, and this is part of that," Mawhiney said.

Stonington's Planning and Zoning Commission approved a plan by Old Lyme developer READCO last week to construct the two-story medical office building on the Liberty Street site of a former amusement park that once featured a water slide, miniature golf course, bumper boats, a children's go-cart track and an ice cream stand.

The commission also approved a special use permit, subdivision approval and a groundwater protection permit RAEDCO asked for to build the 25,206-square-foot building.

In addition to the North Stonington primary care office, Hartford HealthCare operates family and internal medicine practices in East Lyme, Mystic, Old Lyme and Uncasville, and a Backus-affiliated surgery center in Waterford.

Mawhiney said the company is seeking to expand its primary care offerings and grow its customer base in an area with a growing population of senior citizens.

"There's certainly a lack of primary care," he said. "It's also kind of an aging demographic."

Mawhiney added that a gap between supply and demand for primary care doctors leads people to overwhelm emergency rooms and clinics.

"Unfortunately, because of the lack of primary care, a lot of people will use the emergency department or, more commonly now, walk into urgent care facilities," he said. "That becomes their primary care."

Mawhiney said it's too early to announce what specialties doctors at the office will serve or how many medical staff it will employ.

"We're working with area doctors who might have an interest in joining us," Mawhiney said.

Construction is expected to begin in September and Mawhiney said he expects the office to open in July 2019.

m.shanahan@theday.com