Steve ,
We operate on a base that has had every type of munition expended over 60 years . I the old days nobody cared about a dud . Now every dud is logged and destroyed . 10% out of a lot , the whole lot is shut down .
When we prepped for a new MOUT town , it was 1 mile square . It starts with an aerial survey . Then foot surveys . The next step was metal detectors, and last but not least , magnetic blah blah detectors.
A year after completion , a motor grader was scraping the top 6" of the roads we had been driving on for 3 years . He uncovered a 175mm HE round . Now this thing had a born on date before I was even born , and had been driven over for 3 years . It was blown in place . Pretty damn impressive to say the least .
Sometimes we all get bit by the Dragon .
Hopefully the kids didn't feel a thing .
Greg