Suffolk residents Tuesday night grilled the U.S. Army Corps of Engineers over its $1.2 billion flood plan for the South Shore at a public hearing while dividing bitterly over whether buyouts should go from a very minor to a major role.

Anthony Graves, chief environmental analyst for the Town of Brookhaven, expressed Supervisor Edward P. Romaine’s concerns that the plan is based on old climate-change data and should place more emphasis on acquiring flood-prone homes rather than raising or floodproofing 4,400 homes.

“We feel that a buyout program is a better way for our communities to be stronger and resilient,” he said at the Patchogue meeting.

Catherine Kobasiuk, president of the Mastic Beach Property Owners Association, agreed.

“There are a lot of homes that need to go,” she said, adding the proposal would maintain property values and support environment.

However, buyout opponents said it was unfair to single out Mastic Beach, especially when other low-lying coastal areas, including Westhampton Beach, are not being pressured to retreat.

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“We in Mastic Beach are offended by the town’s position of strategic retreat” Frank Fugarino said.

Alan Chasinov, 61, of Mastic Beach, said: “I don’t want to see our community torn apart or dismantled,” also citing the economic benefits the coast provides.

The federally funded plan calls for spending more than half of the construction budget retrofitting homes to withstand floods. Another $237 million would fund planning, design and other costs. The plan also has a large contingency budget.

The Army Corps proposed elevating 2,424 houses in flood-prone areas. Another 1,450 homes would receive flood-proofing assistance, such as relocating basement furnaces and utilities. About 200 houses would be rebuilt or gain flood barriers.

Lindenhurst, West Babylon, Babylon, Bay Shore, Islip, East Islip, Sayville, Brookhaven and Mastic Beach all are covered by the plan. Construction would not begin until 2018, provided the plan secures all required approvals.

Though no dunes can be built in the Fire Island National Seashore, the barrier island’s restored sand barricades will stand about 15 feet high and stretch along one-third of its length.

Under the plan, 5.9 miles of roads in Amityville, Lindenhurst and Mastic Beach would be turned into dikes, shielding more than 1,000 homes from floodwaters.

Brookhaven also warned the Army Corps that the town — one of five municipalities that would be asked to serve as local sponsors — would have to pay about 30 percent of the state’s share of replenishing Fire Island dunes over the next 30 years. The Army Corps estimates that price tag at hundreds of millions of dollars. It would pay 65 percent of that bill; the state would pay 35 percent, but ask the locality to contribute its 30 percent.

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Graves, the Brookhaven official, noted that the 2 percent property tax cap, once mandates are subtracted, only lets Brookhaven raise other spending by a much smaller amount: 0.67 percent.

Two other flash points were whether the Army Corps should scrap plans to raise the 5.9 miles of roads and turn them into dikes, as this could trap water north of the Great South Bay, and whether the plan should raise septic systems or build sewers when it raises homes.

Stephen Couch, chief of the Hurricane Sandy Planning Division for the Army Corps’ New York district, said he knew of no federal requirement to improve septic systems, but stressed that the agency wants to heed local concerns, which could include scrapping the road-raising proposal.

Several speakers urged the Army Corps to leave the breach Sandy cut through Fire Island open, because it has cleansed some of the waters in the Great South Bay.

As part of the plan, the Army Corps modified the breach-closing plan in the Fire Island National Seashore by giving decision-makers 60 days to choose whether to fill in gaps or let them close naturally.

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The so-called FIMP project — for Fire Island to Montauk Point Reformulation Study — also includes dredging the Fire Island, Moriches and Shinnecock inlets. Tiana, downtown Montauk, Smith Point and Westhampton all would gain beach fill. Groins that worsen erosion would be shortened in Ocean Beach and Westhampton.

To absorb storm surges, salt marshes would be restored in areas including Tiana, Great Gunn and Corneille Estates on Fire Island, and west of Shinnecock Inlet.

As an interim project, the Army Corps finished repairing Montauk’s beaches and dunes this year. Though work also has begun on Fire Island’s $207 million dune restoration, the work will probably not be finished until 2018, according to the revised plan.