The city’s plan to “lift” East River Park by 8 to 10 feet will mean bulldozing millions of dollars in new park amenities unveiled just last month, burying them under tons of dirt, and closing the entire oasis for 3 ½ years.

Some residents are scratching their heads that so soon after the city spent $2.8 million to deliver a new soccer field and resurfaced running track, it will now flush those features and close the park again.

The work, to begin in 2020, is part of a massive, $1.45 billion flood-prevention plan to protect the area from storm surges.

The newly revised design will elevate the surface of the 40-acre park between the East River and FDR Drive by dumping tons of soil and fill between 13th and Cherry streets, raise and rebuild the esplanade along the river by boosting the height of the pilings underneath, and erect a flood wall at the river’s edge.

At the height of superstorm Sandy, Lower Manhattan was plunged into darkness and the Con Edison substation on East 13th Street was flooded, sparking a transformer explosion that knocked out part of the island’s grid.

The new plan would protect against such catastrophic flooding.

But the collateral damage is the park and its baseball, football, soccer, basketball, tennis and track facilities, which will be bulldozed and covered, with fill, said a Department of Design and Construction official.

It’s not known what will happen to the historic 1941 amphitheater, situated between Jackson and Grand Streets, which has hosted the likes of salsa legend Willie Colon and rapper KRS-One. The legendary Joseph Papp, founder of Shakespeare in the Park and the Public Theater, staged “Julius Caesar” there in 1956.

City officials have assured there would be “an amphitheater space” in the final product.

“On a project of this magnitude and importance, which will change the face of the east side of Manhattan and provide flood protections for 110,000 New Yorkers, it’s essential we get this right,” said Seth Stein, a spokesman for Mayor de Blasio.

He said the redesign “will protect the community a full year sooner [than the earlier plan] and provide them with a world-class park at the completion of this process.”

He added, “Rest assured, the existing structures and park features will be replaced and improved.”

But many residents are miffed at the apparent waste of money, and their recreational routines being disrupted again.

“It’s incredibly stupid to close it down after finally fixing it up,” runner Lyn Seltzer, 70, told The Post as he prepared to use “the best 400 meter track south of Randalls Island.

“I’m shocked and disappointed. They spent [millions] on it for two years of use!”

Awad Foster, 46, who was training 50 middle- and high-school track and field athletes on the refurbished field, fumed, “It’s crazy! If they are going to do it, they should do it section by section. They shouldn’t close the park down.”

Gilberto Aponte, 45, who plays soccer and jogs at the park four times a week, was crestfallen when informed of the impending closure. “I’m really going to miss this. I love everything. The breeze, the view.”

Parks Commissioner Mitchell Silver said the agency is already thinking about how to bring recreational alternatives to park users.

“We are going to start those conversations with a public meeting and how to address the other public spaces surrounding the park,” he said. “We are doing research internally.”

“We have from now until March 2020,” he continued. “We are looking at city-owned spaces, parks as options for recreation during construction.”

Some residents are not ready to take a leap of faith.

“We know so little. How can they justify spending $1.4 billion? Is it worth touching the park?” said Billie Cohen, a 40-year Lower East Side resident who attended an Oct. 11 community board meeting where the city unveiled the revised flood plan.

“They are going to cover the park, cut all the trees down … They didn’t answer any questions,” she said.

Stein said City Hall “will be able to answer the communities’ design questions in the coming weeks.”