A Westwood developer seeks approval for a 72-unit multifamily project in a pair of 4-story buildings off a private way in West Roxbury.

Onsite Builders & Development LLC said it will completely rebuild Heron Street to modern standards and add sidewalks and street trees as it constructs the 78,704-square-foot project at 11-26 Heron St. Designs by Nunes Trabucco Architects of Needham call for two 4-story wood-frame buildings with clapboard siding and synthetic stone panels.

In a filing with the Boston Planning and Development Agency, the development team said it will address existing flooding in the neighborhood by adding an on-site infiltration system and treating stormwater with deep sump catch basins and water quality treatment equipment.

Located on a 1.2-acre site, the project would include nine affordable units to comply with the city’s inclusionary development policy, and have 85 parking spaces located next to each building along with partial below-grade parking. Plans call for 24 one-bedroom and 48 two-bedroom units.

The project will require a use variance from the zoning board of appeals.