The NSW Department of Education and Communities says it is unclear how many people came in contact with "potentially hazardous material" after it was donated to Bulli Public School to be used as fill for a vegetable garden bed.
A department spokesman said a member of the school community had donated the excavated fill, obtained from a builder.
He said this was believed to have contained small fragments of fibro, and the department had engaged a licensed asbestos removalist, who "fully encapsulated and fenced the area, and covered the fill to contain it".
The fill is believed to have remained on school grounds from the week of August 11 until the department removed it on Sunday.
"The material is currently being tested," the spokesman said.
"As a precaution, the Department of Education and Communities treated the material as potentially being hazardous and managed it as such, according to the department's procedures."
However, the fill was not believed to have posed a major risk to anyone at the school, the spokesman said.
"There was very low risk to anyone on site because the fill material only contained a small amount of non-friable, bonded fibro pieces.
"It is unclear who or how many people came into contact with the fill during this time."
Bulli Public School parent Kim Adams said the pile of debris had sat on the grounds covered for some time, and other parents had feared the pile contained asbestos.