Plans to restore Squibnocket Beach, now under review by the Chilmark conservation commission, are the subject of fresh scrutiny and debate.

Two separately-funded projects won approval from the town selectmen in December. But at public hearings before the conservation commission last week, town residents who are critics renewed concerns about the plans and how they will accommodate an eroding shoreline.

Vineyard Land Surveying, working for the town, has designed a new parking lot farther inland from the beach and a new boat launch at Squibnocket Pond to the west.

Meanwhile, the engineering firm Haley and Aldrich, working for the Squibnocket Farm Homeowners Association, has designed a new road and raised causeway that would run to the homes at Squibnocket Farm.

Both projects will involve the displacement of wetlands, a main concern for the commission.

The planned new parking lot includes a paved turnaround that would extend into wetlands bordering the pond. A new boat launch would also encroach on the wetlands. Reid Silva of Vineyard Land Surveying said new wetlands would be created to mitigate the loss.

The current parking lot will be replaced by a large dune to protect the area from storms, and a stone revetment where the parking lot meets the beach will be removed and used for a new retaining wall at the turnaround.

“A big part of the project is restoring what has been occupied,” Mr. Silva said, noting the town’s intention to allow for a managed shoreline retreat.

The new dune will be tall enough to become established, Mr. Silva said, but will also migrate inland as the shoreline recedes. “We did not design a dune here to last for years and years,” he said.

Some aspects of the project are designed to be more permanent. Both the turnaround and a portion of the new road will be paved in order to accommodate regular traffic, and a raised causeway running through wetlands will be mostly concrete and steel. The new lot will be mostly gravel to improve drainage and preserve the natural character of the area, but will incorporate part of Squibnocket Road, which is paved.

Critics have argued that the solid structures are contradictory to the restoration efforts and will be a problem later on as the shoreline retreats. Only about 60 feet now lie between the ocean and the coastal bank. Mr. Silva agreed that heavy storms in the near future could push waves as far inland as the new turnaround.

Conservation commission member Pam Goff suggested a time frame where the turnaround is moved farther inland once the shoreline is 10 feet away. “That’s the most vulnerable and unattractive part of the project,” she said.

Town resident Thomas Bena questioned whether it would be easier to relocate the turnaround if it was made of gravel.

In response, Mr. Silva pointed to the limitations of the area, which by nature is always changing. “It’s the end of the road, and it always will be,” he said. “Is this is the best we can do for now and for a reasonable period of time? I’d say yes.”

Funding from the state Office of Coastal Zone Management will pay for the town portion of the project, but the town has already missed one deadline for using a major grant. The grant was awarded again last year, but the town will likely miss another deadline in June. Chilmark conservation agent Chuck Hodgkinson plans to reapply for the grant again, and he said the state was still onboard with the project.

“It’s the first time they have seen a town actually have a managed retreat plan,” Mr. Hodgkinson said. “It’s not perfect, but it’s what town approved,” he added.

There were also questions about the homeowner project, which extends even closer to the shore and may need to be altered to accommodate erosion in the future. Mark Haley of Haley and Aldrich said the raised causeway would have minimal affects on the wetland, but concerns focused mostly on its appearance and practicality.

At 13 feet above sea level, the causeway would stand above a 100-year flood. A study by VHB Inc., which is also working on the project, shows that the dimensions of the causeway would allow most of the natural sunlight to reach the ground below, so plants would have no measurable decrease in growth.

The causeway would rest on 45 steel piles (not all in the wetlands) and have a concrete deck and timber rails. The road leading to the causeway from the north would be a mix of pavement and gravel. Steel slabs at each end of the causeway could be moved farther landward in the event of erosion.

Commissioner Chris Murphy suggested that without the proposed fill at the west end, the causeway could be five feet lower, but Mr. Haley argued that it would then be impassable for much of the time. A special town committee that evaluated the project and its alternatives last year had recommended that the bridge be designed to handle overwash several times a year. Former chairman James Malkin said the committee decided in the end to leave it to the engineers to determine the necessary height.

Mrs. Goff argued that a lower bridge would deteriorate faster, and that the rushing water would also damage the wetlands. “This is going to allow the natural process,” she said of the current plan. She also doubted the causeway would last very long. “I think the natural process will be pretty fast,” she said.

Haley and Aldrich based the height on the elevation of a 100-year flood, as projected by the Federal Emergency Management Agency. But some questioned the criteria. Charles Parker, who worked on an alternative plan for the area in 2014, noted the low frequency of 100-year storms. “We haven’t had that much water, I don’t think, ever in the pond,” he said.

Town resident Doug Liman said neither project fully embraces the idea of a managed shoreline retreat.

“You are constantly trying to put in physical structures that can’t move,” he said. "You’ve designed a bridge that can just extend and extend and extend.” He favored a more temporary design and suggested a condition that would require the eventual removal of the causeway.

Meg Rehrauer of Ropes and Gray in Boston, representing the homeowners association, said engineers had taken the committee recommendation “extremely seriously.” But she added that the matter at hand was the protection of wetlands, not whether the plan complies with the recommendation.

Other concerns center on the location of the boat launch, which some had hoped would be closer to the parking lot, and the removal of boulders farther west, where old revetments have tumbled into the sea. Some see the boulders as a safety hazard for swimmers and surfers. Mr. Murphy pressed for the removal of all manmade materials at the site, although Mr. Hodgkinson pointed out that the loose boulders might be useful in absorbing the energy from waves.

Staging for the town project could start as soon as the beach closes for the season next September, Mr. Hodgkinson said, with work lasting about three months. The homeowner plan is expected to take up to five months to complete.

But approvals are not in hand yet.

The conservation commission continued both public hearings to Jan. 21. The commission has not yet decided whether to refer the projects to the Martha’s Vineyard Commission as developments of regional impact. The town selectmen signed off on both plans in December.