Council documents show that building on the 1360-square-metre site doesn't require a permit. However, the cost of cleaning up the contaminated soil and building a circus home is estimated at $2.5-5.3 million.

Mayor Michael Clarke said keeping the Women's Circus was fundamental to Footscray's becoming "an artistic city".

Over the past 17 years, the circus has passed on skills to prisoners, prostitutes, refugees and people with disabilities.

Outreach worker Annemarie Ferguson said she was proud to help marginalised people.

"As human beings, we feel better about ourselves when we achieve something.

"That could be conquering a fear of heights or the fact someone leaves their house and turns up to a class.

"Watching people's perception of themselves change is the thing that thrills me with what I do."