Phase one construction of the mixed-use project on Decatur’s East College Avenue should begin in May according to Dillon Baynes, managing partner for developer Columbia Ventures.

When finished, the project — a joint effort between Columbia, MARTA and Decatur — will cover 7.7 acres, most of which is currently a parking lot for the Avondale Estates MARTA station.

The initial phase will include 288 market-rate apartments, 22,000 square feet of commercial space (office and/or restaurant), a parking deck with 728 spaces and 92 units of senior affordable housing. The first units should be habitable, Baynes said, 18 months after construction, or roughly late fall 2017.

There will be three more mini phases or “out parcels,” which could be built simultaneously or staggered.

The southwest quadrant is tentatively slated as site for a new Early Childhood Learning Center, although Baynes said that could become additional mixed use if City Schools Decatur backs out of those plans.

Initially estimated that the project, which will take about five years to build out, would include a total 500 apartments, Baynes said Wednesday it was too early to give a precise final figure.