You do realize there are several toxic waste dumps, active, inactive, and abondoned in Utah right? There are even more "staging" area where things heading to a dump site are temporarly stored to pose a minimal risk until they can be introduced to the actual final resting place.
But whatever it is, it needs to be buried, and you probably shouldn't be "investigating" any tunnel sites without performing a bit of research like finding out who owns the land...Country Tax Assessors Office would be a good place to start, and if DuPont owns, or did own it, next stop should be a doctor.