Wow, I clicked on that expecting something entirely different.
Burying them in the ground for ambush sites/pillboxes or supply points would present a safety hazard I would think if they were fully recessed. However, if they were partially raised, perhaps 3.4 buried most people with any amount of brainpower should be able to see it and not fall into it.
TM SR-16 *Stock*, And A Shitload Of Mags
Apparently, a hand grenade does not belong in my toolbox. Nor does a hand grenade with the pin pulled belong in someone else's toolbox.
When In Doubt, Empty A Magazine.