What was once a tree-covered private estate at 135 Great Plain Ave. is on its way to becoming a 44-unit Chapter 40B development.

Construction, including site clearance for the controversial project, started a little over a week ago.

Massachusetts law mandates that every town have at least 10 percent affordable housing units. At the time the application was filed, only 6.3 percent of Wellesley's year-round units were for low- or moderate-income. As a result, under Chapter 40B of the state law, the town had little control over the approval process, and certain town bylaws, rules and regulations were waived, including those dealing with tree protection.

The project was approved in 2018.