It seems like there must be a known short cut along the quarry the the kids take. There does not seem to be an easy way to get into the quarry just looking on google maps. It appears that a combination of darkness, some alcohol (said he was at J's corner) and maybe not having your phone working is a real problem. Certainly it was a terrible accident the first time. But it seems to be a real safety issue now with 2 deaths. I can't imagine a phone taking you through the quarry. I can't imagine living in Granby Mills and not knowing that there is a giant hole in the ground, especially after losing someone so recently. So there must be something similar to a swiss cheese model of accidents.
Best I can tell is that they take Whitney St., to Georgia St to Delaware St and jump a fence to come in the back of the apartments. Or, you take Whitney to the end and jump the fence to the right of the building and walk along the right edge...maybe saves a minute or 2. I suspect that there is a well known route through the quarry. Can't be the 1st time he has walked home from there. But maybe chose the wrong fence to jump.
Or, some dude(s) robbed him and threw him into the quarry.
Terribly sad no matter what happened.