All is right with the world. They sent out 3 trucks and 6 guys to retrieve and reseat the grate.
They used a winch to pick it up out of the hole but still tried setting it back into place by hand. I almost had a moment of redemption when I thought it was going to fall back in. They then used the winch to lower it into place.
Oh, and I did walk out just in time to see one of the guys ask the other, "How in the he-double-hockey-sticks did they do this?" I fessed up about the keys, dropping it, and imagining it was hinged. Friendly group agreed when I called myself a dumbass.