Image courtesy of Nelson Worldwide

The 1.8 million-square-foot redevelopment plan for the former Domino Sugar refinery property includes a new flood barrier protecting not only the 25-acre site but over 200 acres in the surrounding Charlestown, Somerville and Cambridge neighborhoods, developers say.

The Flatley Co. proposes eight buildings ranging from 2 to 22 stories including 1 million square feet of housing, 575,000 square feet of office-lab space and a 115,000-square-foot hotel to replace the former factory and parking lot at 425 Medford St. in Charlestown.

The site is the most vulnerable breach point for flood waters along the entire Mystic River, according to coastal resiliency studies of projected sea level rise through 2070.

“A finger in the dyke approach is not an option; this project must provide a real solution,” the Braintree development company stated in a submission to the Boston Planning & Development Agency.

The strategy: a flood barrier 22 feet high along the property’s entire waterfront. Between the barrier and existing riverfront, developers plan to build a series of public spaces including floodable steps, living shorelines, cantilevered boardwalks and observatory platforms.

A three-quarter-mile public walking and bicycle path would be built along the property extending north to the Schrafft Center, also owned by Flatley Co., and the existing Boston Harborwalk bordering Ryan’s Playground.

Construction of the development would take place in three phases, but the entire resiliency component would be included in the first phase, according to the PDA application.

The strategies incorporate elements of the city’s Climate Ready Charlestown resiliency plan, which seeks to protect the Sullivan Square area from flooding. In 2020, Boston adopted a wetlands ordinance giving city regulators additional authority over development in flood resilience zones.

Image courtesy of Nelson Worldwide