DARIEN — A plan to add 255,000 square feet of commercial and residential space, including 122 residential units in two of the three proposed buildings to Norton was the focus of a hearing Tuesday.

The Planning and Zoning Commission opened on Tuesday the first of four public hearings on Federal Realty’s site plan application to redevelop the eastern side of the Noroton Heights Shopping Center.

The hearing focused on two of the three proposed buildings and an emphasis on pedestrian accessibility, a strong retail base, and protecting for residential neighbors to the north on West Road.

According to the architect Bruce Beinfield, the development has been designed as “an assemblage of one, two and three-story buildings that were constructed incrementally over time. The architectural vocabulary is derived from simple forms and character of traditional buildings in coastal New England towns. The design offers both architectural diversity and continuity.”

A pedestrian “promenade” would run north-to-south through the development, and a vibrant streetscape with sidewalk dining would hopefully attract foot traffic to the area, according to the developers.

As was the case in the recently approved site plan application for the Palmers side of the project, that will bring an additional 59 units to the area, drainage is a primary concern in the area, which has seen flooding on storefronts along Heights Road.

The 9-acre shopping center sits at the bottom of a 125-acre watershed, according to Craig Flaherty, principal and senior engineer at Redniss and Mead and a consultant to Federal Realty. In large storms, there is more water than in the area that the culvert can funnel through a small culvert that runs beneath Stop and Shop and its parking lot, across Heights Road and under the railroad tracks.

“If we can add more storage at a lower elevation, we can lower the water surface elevation on Heights Road,” Flaherty said.

The answer, Flaherty said, is a large, underground concrete structure, or a “void,” that would add four water acres — the amount of water needed to fill an acre at one foot depth — of water storage to the area, which could reduce the incidence of flooding in the area by between 44 and 46 percent.

The public hearing will continue on Tuesday, June 13.

justin.papp@scni.com; @justinjpapp1