Travellers have descended on a site in Worksop near a school.
Around 17 caravans arrived on land on Valley Road, Worksop.
If Gypsies or Travellers are camped on council-owned land, the council can evict them.
However, if the encampment is on private land, it is usually the landowner's responsibility.
A statement from Worksop Leisure Centre said: "Those responsible for the land have issued the Travellers a 24hr notice.
"We’ve been informed that bailiffs shall be on site tomorrow morning.
"Thank you for your patience in this matter."
Spokesman for Outwood Valley said: “We are working with the relevant bodies to resolve the situation, and an eviction notice has been served by The Sheriffs Office ahead of the car park being cleared tomorrow.
“With exams now underway, we are keen to keep the Academy operating as normal and we do not believe that there is any need to close.
“The safety of our students and staff is of paramount importance and we have ensured all the appropriate steps have been taken to manage this situation.”