Developer discusses impact of underground brook with P&Z

A developer is trying to figure out how to best handle a brook going through a downtown property where a major mixed-use project is being proposed.

The Burying Ground Brook flows underground through the site at Center Street and Coram Avenue, surrounded by walls. It flows through a seven-feet-high support archway built of stone and brick, and then flows under a concrete slab. The underground system dates back more than 100 years.

The situation represents one of the challenges that face redevelopment activities in old industrial areas. In the old days, waterways were just altered or diverted to make way for a project. Many minor waterways in downtown areas were essentially forgotten when they were piped underground or covered over.

An entity known as 62 Center Street LLC wants to build 42 apartments, a large restaurant and bar, and a parking garage on a half-acre lot at 62-66 Center St. and 325 Coram Ave. The site now includes Jeff's Appliance and other commercial tenants, as well as a stand-alone house.

Existing structures would be knocked down and replaced with a modern building and garage.

The Burying Ground Brook was partially covered on the property in the 1890s. The developer wants to put new slabs over the waterway so it can build on top of it, but there's concern about the long-term stability of old brick retaining walls that contain the brook on the property as well as the archway.

It's uncertain whether it's best to knock down the old retaining walls and archway to replace them, or try to salvage the existing set-up by reinforcing the old infrastructure. The walls could potentially fail in the future anyway, which would impact the slabs being held up above the brook. Or the process of demolishing the retaining walls could create unforeseen problems.

"Wouldn't it make sense to build something new?" Inland Wetlands Commission (IWC) Chairman Gary Zahornasky asked during the commission's June meeting.

"That's an awful lot of effort to preserve something that may not hold up," Zahornasky said.

The developer's engineer, James Swift, said the current system "has been here 100-plus years" and held up fine, and altering the channel might put "pressure" on locations downstream. He said many large pieces of stone provide support in the archway.

City Engineer Robert Kulacz wants the developer to replace the old underground archway with "a new precast concrete box culvert" because this would have the capacity to handle greater water flow. Kulacz said while photographs appear to show "stable conditions" with the current system, there would be limited access to repair and maintain the archway if needed once the new project is built above it.

"It is imperative that a modern, low-maintenance scour-free conduit with upgraded hydraulic capacity be provided, before the developer permanently constructs a major structure above it," Kulacz wrote.

Swift indicated the developer is open to considering making such improvements. "It should be looked at," he said.

He said access to the underground infrastructure would continue if new slabs are placed above the brook. "It's not like we're sealing it like a mummy forever," Swift said.

City Inland Wetlands Coordinator John Cook said water quality must be maintained during demolition and construction, presenting challenges.

Zahornasky questioned how debris could be kept out of the brook during demolition. "There's going to be a lot of stuff falling -- it's an old building," he said.

"I agree -- it's probably the most critical thing about the project is that nothing falls in," Swift responded.

The IWC voted to table the application so staff could continue working with the applicant, and more input can be provided by Kulacz.

Swift promised to keep the IWC informed by providing "detailed structural engineering, and the process to be followed."