An advisory group postponed its vote on a 105,000-square-foot fitness center and field house proposed for Atlantic Yards/Pacific Park so it can first examine Empire State Development’s rationale for forgoing an environmental review of the facility.

ESD oversees the 22-acre Atlantic Yards/Pacific Park project, where planned and completed construction includes Barclays Center Arena, 16 buildings with residential and commercial space, a public school, eight acres of publicly accessible open space and improvements to the Long Island Rail Road train yard on the site. The project’s boundaries are Atlantic, Flatbush and Vanderbilt avenues and Dean Street.

The board of directors at Atlantic Yards Community Development Corp. (which is a subsidiary of ESD) on Monday tabled the measure that would enable ESD to include the athletic facility in the mega-development’s Modified General Project Plan, the legal document that determines what the developers will be able to build.

The facility’s intended location is in the basements of two sites (B12 and B13), where developer TF Cornerstone plans to construct apartment buildings.

As of now, the Modified General Project Plan only explicitly permits retail space to be built on the buildings’ ground floors. The plan neither allows nor forbids retail space to be constructed at basement-level.

The board of directors wanted to review a technical memorandum prepared by ESD staffers about the gym and field house’s potential adverse environmental impacts before Monday’s vote — but they were not allowed to do so.

The directors were told the tech memo concluded that the sports facilities wouldn’t cause any significant impacts that hadn’t already been identified in Atlantic Yards/Pacific Park’s previous environmental reviews.

The tech memo is in draft form, and according to ESD regulations, draft memos can’t be released publicly — not even to the advisory group’s directors.

Atlantic Yards Community Development Corp. President Marion Phillips III said at the meeting that as a remedy, the directors will be allowed to make appointments to read the tech memo in person, at the organization’s Midtown Manhattan office. Staff members and consultants will be made available to go over its more technical aspects.

Soccer, gymnastics and swimming at the field house

Before this suggestion was made, State Assemblymember Jo Anne Simon, who attended the meeting, spoke out during a public-comment period against ESD’s withholding of the tech memo from the advisory group’s directors.

“If they don’t have the information they need to make an informed decision, then that decision is not going to be a good advisory decision,” said Simon, who represents the district in which the project site is located.

“It would seem to me that it’s in the interest of the public for this body to have as much information as possible before it’s called upon to make a decision to vote,” Simon added.

Last week, she told the Brooklyn Eagle that ESD should be more forthcoming about its reasons for wanting to build the field house and fitness center.

Some details about the field house and fitness center were revealed at Monday’s meeting.

The 60,000-square-foot field house will have an indoor soccer field, a gymnastics facility and a “learn-to-swim pool.” The fitness center will be 45,000 square feet in size.

A total of 96,000 square feet of the combined facilities will occupy part of the basements of the sites on Dean Street. There will be a 9,000-square-foot lobby at ground level.

The tech memo also contains information about a second issue the board of directors tabled on Monday: the construction of ventilation structures for Atlantic Yards/Pacific Park garages, the gym and field house. A vote on the gym and the ventilation structures is now scheduled for Aug. 12.

‘We will be lucky to break even’

During the hearing, Atlantic Yards Community Development Corp. Director Gib Veconi said he asked an expert what the fitness center and field house might be worth to the developer and was told they could generate revenues of $10 million to $15 million per year.

After the hearing, TF Cornerstone Senior Vice President Jon McMillan told the Eagle, “The numbers quoted today are nowhere near the rents we expect to collect from the [athletic-facility] operator. Our sense at this point is that we will be lucky to break even.”

McMillan also told the Eagle that TF Cornerstone doesn’t yet know what company will operate the members-only fitness center. There’s a Chelsea Piers gym at 33 Bond St., a Downtown Brooklyn apartment building the developer constructed a couple years ago.

TF Cornerstone decided to include a field house for the general public’s use at Atlantic Yards/Pacific Park sites B12 and B13 because “we found communities are critical of developers when they ‘internalize’ these residential amenities,” McMillan told the Eagle. “And so we tried to find a way to break down the barriers between the residents of these big, new projects and the surrounding communities.”

Valet parking for bikes? Nope, not happening

At Monday’s meeting, the board did vote in favor of recommending the adoption of several other modifications to Atlantic Yards/Pacific Park’s Modified General Project Plan. They were lumped together into a single resolution.

Here are some of the measures included in the vote:

* The reduction of Atlantic Yards/Pacific Park’s parking requirements to 1,000 parking spaces from 1,200 parking spaces.

* Abandoning a plan to provide free indoor valet parking for 400 bicycles for arena-event ticket holders and instead making available to arena-event attendees outdoor bike racks for 100 bicycles with no valet service.

* Narrowing the width of north-and-south-running walkways at the complex to 12 feet from 16 feet to allow for more lawn space and planting beds.

Follow reporter Lore Croghan on Twitter.