Think of how many people have passed by that throughout the years.
Thankfully it hadn't went off.
Had it unintentionally went off at anytime through those hidden years, not only could it have caused pedistrian injury, I seriously doubt the explostion would have been credited as a blast from the past and not atributed to current issues.
I feel sick thinking a child could have been the one to have found it
and hid it there.