Hard as it is to believe, it appears that the insanitary and possibly toxic area used to hold demonstrators during the Republican convention was not a city facility, but a property provided by the RNC.
Although there are potentially some complex legal questions lurking around the terms by which RNC might have made the space available to the cops, in several imaginable scenarios — but not all! — the RNC might be liable for any damages caused by toxic exposure. Alternately, or even jointly and severally, the city might be extra liable if it used a facility that it knew or should have known was unsuitable.
I suspect that some plaintiffs' lawyers are going to have a (justified) field day with all this.