A "pop-up" primary school for 300 children at Wentworth Park in Ultimo will escape environmental scrutiny, despite the discovery of lead contamination at the site and the takeover of public recreation space.

The Department of Education is seeking to fast-track the proposal to build the primary school on a site which straddles the Wentworth Park greyhound racing complex and the public park.

Students from Ultimo Public School play at Wentworth Park, Ultimo.

The department argues it takes up 5 per cent of the overall space, and organised sport won't be impacted.

The temporary school will be in the park until December 2019, as Ultimo Public School is demolished and rebuilt as a high-rise for 800 students to cater to booming inner city enrolments.