The Conservation Commission, after more than four hours of testimony Wednesday night, decided to continue a public hearing on plans by Bridgewater Associates for upgrades at its 15.84-acre Glendinning campus.

An application for the proposal, filed earlier this year by the giant hedge fund with the Planning and Zoning Commission, calls for a two-story underground parking garage that would eliminate the approximately 160 above-ground parking spaces that lie in a flood plain adjacent to the main headquarters on Glendinning Place.

It also involves the renovation of two of the five buildings on the Bridgewater property, which is a designated Design Development District.

Tom Galleta, a site designer with Fuss and O’Neill, at Wednesday’s meeting discussed storm water reduction and how the “big green roof” — that will cover the underground garage — would act as a filter.

He said there will be three underground storm water infiltration systems, a new septic system and a stone trench drain along Glendinning Place.

There will also be some remediation on the site, including removal of some contaminated soil. The property, the commission was told, encompasses six ecological communities including the Saugatuck and Aspetuck rivers and a coniferous forest. There are about 200 special species plants as well as a number of birds and amphibians.

Commission members also heard about a construction management plan.

In all, about 7,000 square feet of wetlands — a small portion of the 958,000-square-foot site — would be affected by the plan, they were told.

“This is complex, like a Swiss watch with interconnected pieces,” said Wesley Stout of Wesley Stout Associates, a landscape architecture planning firm. He said Bridgewater “places tremendous value on this unique setting.”

“It’s an aging facility,” he said of the headquarters property, adding this is “not an enormous expansion, but a renovation-based project.”

Alicia Mozian, the town’s Conservation Department director, read letters of support for the project that, she said, came from neighbors and the Aspetuck Land Trust, which owns abutting property. The town’s Architectural Review Board approved the plan Tuesday night, commission members were told.

But after hearing hours of testimony, the commission decided there still are many unanswered questions about the plans, including some concerning the underground parking and the impact on wetlands.

Town Attorney Ira Bloom offered some advice and Commission Chairwoman Patricia Shea, who said the presentation was informative, polled commission members on their feelings about continuing the hearing. Many felt it was a good plan, but agreed more time is needed to digest the material. Around 11:30 p.m., the commission voted unanimously to continue the hearing to 7 p.m. Aug. 19.

Prior to the vote, Eric Bernheim of Halloran and Sage, Bridgewater’s lawyer, said: “We believe we gave you everything you need.” He asked for feedback from the commission before the next hearing.

Commission tours campus

Last Friday, commission members took a site tour of the Glendinning property, led by Stout, who pointed out some of the proposed changes on the property that also includes 5.89 acres off Ford Road.

The tour, during which members were told how the developer plans to work within the town’s wetland and other conservation guidelines, was in preparation for Wednesday’s hearing.

Stout, at that time, explained where the septic area would be located and where soil would be stored while excavation of the underground garage is taking place. “We will work from east to west on the garage” he said, noting they will be dealing with sand and gravel, not rock which is “one of the blessings” of the soil type at the property.

He also said the front entry to the campus at 1 Glendinning Place will also be widened from 20 feet to 24 feet to allow for buses and emergency vehicles to enter.

A smaller building used as a central reception area would also be completely rebuilt, under the proposal. There will also be plantings and buffering as well as a new fish ladder installed on site.

Stout said from start to finish, the entire project should take 24 months to complete. During that time, the business will relocate some workers, about 300, to other locations. That’s one reason they would like to move as quickly as possible on the project, he told commission members.

At the request of a lawyer representing Bridgewater, the P&Z in March 2014 approved a proposal loosening the development restrictions that applied to the DDD districts since the regulation was adopted in 1980.

The P&Z, in unanimously approving revisions to the DDD regulations, struck a compromise on the allowance for expanded coverage on the affected properties, cutting back the proposal to no more than a 10 percent increase in building or site coverage from the 20 percent that Bridgewater sought.

Commission members were told at the April meeting that this proposal would expand Bridgewater's coverage close to the 10 percent threshold on the building side and maybe a little more on the site proposal.

The plan needs a review by other town boards and commissions, like the Conservation Commission, before a formal proposal goes back to P&Z.

Bridgewater, the world's largest hedge fund, has been located in town for the past 17 years. It had announced plans last year to move its corporate offices to Stamford. Despite $115 million in state incentives for the firm to move to a new waterfront headquarters in that city, the project became mired in local zoning disputes and Bridgewater ultimately pulled out.

Bridgewater Associates was the town's fourth largest taxpayer on the 2014 grand list with holdings assessed at $22,053,470.