Edgartown selectmen agreed on Monday to the terms of a deal hammered out with The Nature Conservancy (TNC) that would allow the town to replace one of two hangars at Katama airfield with a much larger hangar and bring an end to a tussle with the national conservation organization that’s lasted more than eight years.

The town could not alter the size of the hangar without first coming to an agreement with TNC, which holds the conservation restrictions on the historic grass airfield. The agreement, which has changed little over the past year, would amend a conservation restriction on airfield property granted by Edgartown to The Nature Conservancy in 1988. That amendment would, in effect, remove the land where the airfield’s buildings are massed from some conservation restrictions.

“In terms of the conservation restriction, we resolved everything with The Nature Conservancy,” town counsel Ronald Rappaport told selectmen Monday. “We’re ready to go.”

Under the terms of the current deal, the town would be required to put 21 acres of town-owned land off Pennywise Path under new permanent conservation restrictions. The existing uses of the land include five acres reserved for solar energy, two acres for wastewater, seven and a quarter acres for recreation, and five for conservation, Mr. Rappaport said.

The land surrounds a town well, and town officials have previously said it is not likely to be developed, but the new conservation restrictions would prevent any use, in perpetuity.

The proposal would also convert about 6,700square feet of land, currently mowed and used for airfield operations, to wild, protected land; add a 62-acre parcel that was left out of the 1988 agreement by mistake; and designate a zone for specifically defined airfield operations.

“There’s nothing new that’s being added that wasn’t in the deal before,” Mr. Rappaport said. “What I said when I was last in front of you was that the town is giving up a lot to effectively double the size of this small hangar.” Mr. Rappaport continued, “People ought to take a deep breath and see if what we’re giving up is worth it.”

Mr. Rappaport reminded selectmen that voters have already approved the expansion at a special town meeting in 2010.

Also present Monday were airfield commission members Mike Creato, Jim Harrison, former chairman Bob Stone, and current chairman Jamie Craig. The airfield officials have pressed Edgartown selectmen for support of their hangar project. Planning began in 1996 and the airfield trust began raising funds in 1998. They have raised $330,000 to date.

In the past, selectmen balked at signing a conservation restriction agreement with TNC, after being advised that it placed too many restrictions on the town’s control over the hangar project, and they blamed TNC for long delays and unreasonable demands that have delayed the project.

Selectman Arthur Smadbeck asked airfield commissioners why the airfield officials seemed to be on board with this new agreement when they had expressed “vocal opposition” before.

“Our major opposition was that we didn’t have assurance that we would get what we want,” Mr. Stone said. “I wouldn’t sign anything unless we knew we’d get what we’d want, which is a larger hangar. I haven’t seen assurance of that yet.”

Airport manager Mike Creato said the agreement now provides clarity that was lacking before.

Mr. Creato also said the hangar project will be a benefit to the town. “I think there’s a benefit to having a building that sort of cleans things up out there,” he said. “It’s a pretty nice little oasis. It’s a little messy and overridden, but I think it’s a worthwhile effort to make it a viable facility. It’s not without a pretty good return.”

Since TNC has signed off on the deal, the decision now rests with the selectmen, Mr. Rappaport said.

“I think we’re on our way, hopefully,” selectman Margaret Serpa said.

Selectman Michael Donaroma was not present Monday. Selectmen are expected to sign the new conservation restriction at their meeting next Monday.

In other business, selectmen approved a request from John Roberts, owner of the former 11 North restaurant building, to block part of a loading zone on Mayhew Lane. Mr. Roberts told selectmen he plans to install a dumpster, effective immediately through May 15, in order to make repairs following a flood on December 13, that caused significant interior damage to the building. Selectman Serpa approved the request on the condition that nothing is poured or spilled into the storm drain.

Finally, selectmen gave town administrator Pam Dolby the go-ahead to sign off on a grant application to pay the salary of an energy manager who will oversee energy projects in Oak Bluffs, Vineyard Haven, and Edgartown.