Call it Westport’s “big dig.”

Construction crews have been excavating the downtown site needed for the underground garage that will be part of the Bedford Square multi-use project, flanked by Church Lane, Elm and Main streets and Post Road East.

The garage is expected to have space for about 100 cars when complete.

On Wednesday, Church Lane was closed to traffic while crews began pouring concrete for the garage, a process that could take some time, according to David Waldman, project developer.

Waldman noted that 1,000 truckloads of concrete will be needed to complete the job. He said workers actually began pouring the concrete Tuesday night. He said the street was closed off while workers pumped concrete into the site on Wednesday. He wasn’t sure if future street closures might take place.

Town officials had approved closing off Church Lane, from its intersection at Elm Street to Post Road East, to minimize neighborhood disruption.

“At the current time, we have no knowledge of any request to close Church Lane for construction tomorrow (Thursday) and they need to come through here for approvals,” Dewey Loselle, the town’s operations director, said Wednesday afternoon.

The Bedford Square project will completely renovate and re-purpose two historic structures — the 1924 Bedford Building, which was built for the YMCA 90 years ago and housed its operations up until last November, as well as the adjoining firehouse.

Bedford Square will encompass about 70,000 square feet of retail space, 24 residential apartments and office space, as well as the underground parking.

There was a groundbreaking in June for the anchor store, Anthropologie, the retailer of high-end clothing and home goods, which will occupy 40,000 square feet. The store plans to open at Bedford Square by Thanksgiving.

Waldman has called the project "a vision for Westport's future." He said it was made possible "through the collaboration and cooperation with our team, the town of Westport and our downtown neighbors."

At the groundbreaking for Anthropologie, Waldman said that "by preserving and re-purposing these historically significant structures into a thoughtful and architecturally beautiful, mixed-use addition," the developers are "not only opening the gateway and connecting it to the town's future, but anchoring it with a retailer who will draw shoppers downtown, which in the long run will benefit everyone."

Bedford Square is a collaboration between two local real estate development firms — Waldman's business and Charter Realty & Development Corp., led by partners Dan Zelson and Paul Brandes.