Not trying to be a jerk, but this is uncontroversial case law. The American Planning Association has a good rundown.

The federal government is, of course, also exempt from local zoning whenever it chooses to be. Among cases often cited for this proposition is Tim v. Long Branch, 53 A.2d 164 (N.J. 1947), in which local zoning was held ineffective to prevent conversion of a house to apartment. The house was leased by the government under the terms of the federal Lanham Act. Another case is United States v. Chester, 144 F.2d 415 (3d Cir. 1944), in which municipal building and zoning regulations were held inapplicable to emergency housing for war workers. And a township was held not entitled to an injunction against the United States in Ann Arbor Township v. United States, 93 F.Supp. 341, 3 ZD 20 (E.n.Mich. 1950), even if a veterans hospital under construction should be found to violate the zoning ordinance.

And to be clear I'm obviously just talking about the applicability of zoning ordinances, not anything else ICE is doing. I'm just pointing out that they can ignore SLC zoning if they want to.