The "delta" fire channel was originally a conventional channel using the frequency 154.280 MHz. (PL tone 103.5 hz). In N.C. and many other states, 154.280 is licensed for use on a statewide basis ... hence the name "state fire."
Union County now airs the "delta" channel over both 154.280, and over talkgroup 45587 on the Union County P-25 digital sites that are part of the Charlotte regional system.
As to "what channel," I've never seen the templates for the VHF or 800 radios used by the fire agencies in Union County.