Plumber Gives Away Plum Treasure

In this dreary season of severe shortage of all manner of cash, how could a cash-forsaken plumber mistake a bounty of a treasure for a bomb?
A clueless plumber digging a drainage system for the purpose of installing water pipes in the East Rand of Johannesburg comes across a sopping cooler box buried about two metres below the surface.
Convinced that he had chanced upon a deadly cocktail of super bombs similar to Saddam Hussein's yet unearthed weapons of mass destruction, he dialed the police hot-line to report that the clicking devices are about to flatten the motherland.
The bomb disposal unit arrives in a flash.
Box is meticulously opened and... instead of a dreadful beast of super bombs, they unwrap 1.5 million rands in hard cool cash.
Cops dutifully load bounty into their car for 'further investigations', leaving behind bewildered plumber to his fate of digging up dirt.

What would you have done?