This is actually an old Titan 1 site that was turned into a toxic waste disposal site. There are 2 others in the vicinity, one just E of Boise, and one S of Bruneau. The one E of Boise is now privately owned, they live on top of it. The one S of Bruneau I'm not sure of, but I believe it too was filled with hazardous waste, and then covered over.
On a side note, my father was stationed at Mountain Home AFB, and was a Missileman with the squadron there. He worked at the Boise site.
4240'13.75"N 11552'3.54"W
4320'43.53"N 11559'34.13"W