After months of testimony, the Martha’s Vineyard Commission closed its marathon public hearing Thursday on the regional high school’s proposed athletic field renovation.

Held before an audience of 84 viewers over Zoom, the meeting marked the sixth and final hearing on the $7 million first phase of an $11 million project to renovate the high school’s aging athletic complex. The project includes five new or remodeled grass fields and one new synthetic turf track and field — which has been the center of much controversy. The commission is reviewing the project as a development of regional impact (DRI).

The 15-month exhaustive review has included impassioned testimony from scientists, toxicologists, environmentalists, coaches, school administrators and Islanders on all sides of the issue.

On Thursday Ben Polimer, field grounds coordinator for the town of Weston, answered questions from commissioners and staff about the maintenance and merits of grass fields.

“I can tell you that the Vineyard certainly has a unique climate and that climate, I believe, could handle natural grass athletic fields very well,” said Mr. Polimer, who detailed rigorous maintenance practices, like field rotations and resting schedules, and the full-time custodial staff need to maintain excellent grass fields.

“If fields are built correctly, if fields are maintained correctly, they can last indefinitely, but [they must be] started from the ground up, drainage, proper soil selection, proper growing medium,” he said.

At one point he was asked whether there were benefits to using both grass and synthetic fields.

“Absolutely, 100 per cent,” Mr. Polimer said. “The [synthetic surface] takes pressure off our natural grass facilities.”

Commissioners also had questions for the high school and the project architects.

Commissioner Ben Robinson asked how the school planned to improve its existing grass fields under the plan, while others wondered about funding. School superintendent Matthew D’Andrea has said previously that the cost of the project will covered by private fundraising, although he has provided no details.

“Phase two would be something that the school would have to get behind and be able to fund,” said Chris Huntress of Huntress Associates, the lead architect on the project. “That would be down the road when that would occur . . . but step one has to come first.”

In final public testimony, a small group of Islanders spoke passionately about the pros and cons of the project, capping months of public debate and echoing previous testimony.

The evening concluded with a joint presentation from school committee members, Mr. Huntress, and administrators, including superintendent Matthew D’Andrea, assistant superintendent Richie Smith and high school principal Sara Dingledy.

“While I believe that my core work is curriculum and direct student support, I also know that the condition of the building and the grounds where students learn and play are important. I believe that teachers and students are inspired and shaped by this space that they inhabit,” said Ms. Dingledy. “One of the biggest values of this project is it can get done . . . we can do it, we can finish it. Let’s get it done and let’s take an important first step in upgrading the facilities of high school.”

Commission chairman Joan Malkin gave a final summation.

“We’ve held six public hearings and three LUPC hearings, we’ve had testimony from 15 experts . . . 28 organizations have provided written and or oral testimony, 65 members of the public have testified and . . . the documentary record consists of somewhere 1,214 pages of data and information, including 345 letters from a public,” she said. “And now 16 commissioners are going to try and decipher what it all means.”

With that, the hearing was closed. The written record will stay open until May 3 at 5 p.m. A post-public hearing review and deliberations will follow, with a vote expected sometime next month.