Bob
I was out there last year. I think you can see it in Guy's photo, isn't there a mailbox on one of the sand road intersections?
I think this is part of Brick Wall corp. Even back in the '70's I don't think a sand co. would venture on public or private land it didn't own. I think there's more to it than your assessment of "get the hell out of here" from the State. Maybe your right and Pinelands put a stop to it as they did that big proposed development in Manchester just West of the Lacey Line? You know where I'm talking about, Wynnwood I think, next to Roosevelt City?
I would think that hill comprised of the "right" sand and when the sand ran out so did the hill. That entire area just up from Bryant rd has been mined heavy and now left to reclaim itself. I haven't seen any Conservancy signs in this particular area, are you sure it's now their land? If Brick Wall can no longer mine there they may have sold or donated for a tax purpose since it would be worthless to them. It could have been a "peace" offering, here, you can have this, now leave us be.
JD, I don't recall the mailbox, but it would not surprise me. What you say could all be true or partially true, but I'm almost positive that the remediation method was blasted by everyone. I wish I really knew the full story, it would make for interesting reading. It's in some archives somewhere I'm sure. It is Nature Conservancy land now, but that switched hands only 7-10(?) years ago.