In case any noobs are reading this thread....No shovels of any sort on an active sports field! Not even a trowel!
Thats why I carry a cheap folding lockback knife in my finds pouch, and wander around looking harmless with nothing but a 6" screwdriver...then, on the occasion I get a deep tasty signal I cant pass up, I stab that screwdriver down to its hilt right on top of the target, drop to one knee, whip out that knife, and cut a small deep plug around the screwdriver, no bigger than my fist,...pull up that plug like taking the top off a pumpkin, stab a bit deeper and ream around a little with the screwdriver, find the target, pop the plug back in and patch up the mess to an invisible form, stand back up and step on it, and move on, quicker to do it than type it!
....on the outside chance a guy is caught by an authority figure with a knife on school property, a fellow could always say he found it there, since its in the finds pouch and all....
Good holy Vishnu! Want to get in trouble? dink around with a big spade and a drop cloth, wearing a toolbelt and knee pads on an active sportsfield! Nope! Gotta look and behave like a shallow surface cladstabber for this kind of location...
Mud