CHICAGO (AP) — High levels of mercury and other contaminants are being removed from a vacant Chicago lot where a tent camp housing 2,000 migrants is planned, a report from a consultant hired by the city said.

The Chicago Tribune reported that the nearly 800-page assessment by Terracon Consultants released Friday night said high levels of mercury and other chemicals were being removed from the Brighton Park lot where workers had already begun building the giant tents for incoming migrants this week.

City officials did not respond to requests by The Associated Press for comment, or access to the report, on Saturday. The document was only released to those who filing an open records request, despite being at the heart of roiling controversy over the site and in spite of a repeated vow from Johnson to keep the public informed, The Tribune reported.

Local residents have been protesting the project, saying it doesn’t meet zoning requirements and that the soil at the site, which has a long history of industrial use, is toxic.

But Mayor Brandon Johnson’s office told the Tribune that it was confident in moving ahead with the camp, citing the soil’s removal as well as the use of an “engineered barrier” along the site.

“With the limited soil removal and placement and maintenance of the barrier, the site is safe for temporary residential use,” Johnson’s office told the newspaper.

More than 23,000 asylum-seekers have been bused to Chicago from Texas since August of last year, according to the city. Other Democratic-led cities are grappling with similar influxes, including Denver, Houston, Los Angeles and New York, which has received more than 120,000 asylum-seekers.

The state said it wouldn’t move people into the shelter until it is deemed safe. Gov. J.B. Pritzker’s office said Friday night it would not have a comment until the Illinois Environmental Protection Agency reviewed the report.

Alderwoman Julia Ramirez, who represents the ward on the City Council and has opposed the project, did not immediately respond to a message Saturday from The Associated Press.

The report came out as Chicago is scrambling to house hundreds of asylum-seekers still sheltering on sidewalks, at police stations and at O’Hare International Airport as cold weather sets in. The city announced a partnership with religious leaders this week to house 400 of the migrants in churches.

The mayors of Chicago, Denver, Houston, Los Angeles and New York have been pressing for more federal aid to deal with the surge in migrants who have been arriving in the Democrat-led cities on buses funded by the Republican governors of Texas and Florida.