Apache Powder actually had 6 Porter 0-4-0 Fireless along with 10 4T - 5T Plymouths. All six Porters are still in existance scattered around the country and 1-2 Plymouths still exist at the plant - Now Apache Nitrogen (as in fertilizer).
Access was available as I and a friend did our last go thru in the late 80's right before the Porters were "officially" retired.
Have never seen a full Homestake compressed air roster, but there wer operations in Arizona - Ray Consolidated and Inspiration Consolidated Copper which both had large fleets of compressed air locos - 1 Ray (Kennecott) 0-4-0CA is on display and there are storage tanks from two others inside the Asarco mill at Hayden.