Nikki Varney, 44, allegedly admitted to police that she had sex with one of her 15-year-old students on a park bench in July

A Pennsylvania high school teacher is facing multiple charges after allegedly having sex with one of her 15-year-old male students — with one of the sexual encounters taking place on a park bench, PEOPLE confirms.

Nikki Varney, a 44-year-old mother and a science teacher at Williamsburg High School, allegedly admitted to police that she had sex with the teen twice in July, and the boy told investigators that they had coordinated at least one of the meetings on social media, according to a probable cause affidavit obtained by PEOPLE.

“The inappropriate contact began while he was swimming at her residence and they moved to the hot tub,” investigators alleged in the affidavit, citing a written statement from the boy. “He then wrote that he and the defendant went to Canoe Creek State Park to walk her dog. While at the park they walked along a path that ended at a couple of benches.”

The affidavit continued: “He [the teen] stated that they proceeded to engage in sex on one of the benches.”

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Credit: Williamsburg Community School District

Varney is charged with two counts each of statutory sexual assault, intercourse with a student, corruption of minors and unlawful contact with a minor.

She is being held at the Blair County Prison in Pennsylvania on $150,000 bail, a prison official tells PEOPLE.

She has not entered a plea and is expected to appear in court on Sept. 5, according to a spokesperson for the Pennsylvania District Attorney’s Office. It is unclear whether she has retained an attorney.

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Following the park incident, Varney and the boy allegedly had sex at her home in Hollidaysburg, Pennsylvania, after she picked the teen up from basketball practice.

Williamsburg Community School District Superintendent Lisa Murgas reported the alleged sexual relationship to police last Thursday after interviewing the teen, the affidavit states.

Varney allegedly confessed to the assault in an interview with investigators a day later and was arrested.

She has been placed on administrative leave, Murgas tells PEOPLE.