The City of Lincoln Council said it will begin court proceedings to evict the dozens of caravans camped without authorisation behind the Birchwood Leisure Centre off Fulmar Road.
As previously reported, the group parked on the field on Saturday, June 21, and initially comprised of just nine caravans and a work vehicle.
On June 23, another group also moved onto the field, leading the City Council to get involved.
The City Council works with unauthorised encampments alongside Lincolnshire County Council in a joint protocol.
Following a visit on the site on Monday, the City Council said it will begin court proceedings to clear the camp.
Karen Bevan, Leisure Services Team Leader at the City Council, said: “Following a needs assessment and community impact assessment we will be issuing court proceedings tomorrow (June 25).
“The law requires there to be a notice period of two full days before any further action can be taken.”