A disgraced ex-Stuyvesant High School assistant principal who pleaded guilty to sex abuse charges in 1999 is being sued by a former student who claims he sexually abused her beginning when she was 16.

Nicole Erlichman, 52, claims assistant principal and chairman of the Biology Department Richard Plass sexually abused her a few times a week for two years beginning when she was a junior at the prestigious school in Tribeca, according to her Manhattan Supreme Court lawsuit.

Starting when Erlichman was 15-years-old, Plass groomed her “using their shared interest in science as a way to secure time alone with her,” according to the court papers filed late Friday.

Plass allegedly told Erlichman “in graphic detail” about his other sexual relationships including with his wife and told Erlichman he wanted sexual contact with her but would wait until she turned 16, the court documents claim.

In 1985, Erlichman told then-principal Abraham Baumel about the abuse but Baumel “attempted to intimidate Erlichman and cause her to believe that Plass had done nothing wrong,” the lawsuit alleges.

Baumel — who died in 2015 — didn’t investigate, tell the police or her parents, the suit alleges. Rather, Baumel warned Plass of her complaint since the pair were “close personal friends,” the court papers charge.

And Plass “began a campaign of harassment,” to get Erlichman to stay quiet, the court filings claim.

The abuse “has haunted Erlichman for the rest of her life,” the court documents say.

Erlichman — who now lives in upstate Livingston county — is also suing the Department of Education and Stuyvesant for negligence under the Child Victims Act, which allows victims of child abuse to bring old claims that have passed outside of the statute of limitations during a one-year look-back period.

“Plass continued unabated in his role as Chair of the Biology Department and continued to sexually abuse young girls until he was finally caught,” the suit claims adding that Plass’ behavior was widely known about at the school.

In 1999, Plass was sentenced to three years probation for admitting to molesting a different 15-year-old girl. He gave up his teaching license but was eligible for a pension after an early retirement.

“Richard Plass abused his own power egregiously and pervasively,” Erlichman’s lawyer Renner Walker said. “But what is more concerning is that his abuse of power was ratified and certainly enabled by other supervisory actors in the DOE.”

Erlichman’s other lawyer, Anna Kull said, “We firmly believe that what happened to Plass is not justice. He got off with three years and a pension and his victims got nothing.”

An unidentified man, who answered Plass’ phone, hung up on The Post.

A rep with the city Law Department said they will review the case.

The DOE did not immediately return a request for comment.