Went there yesterday. It's every bit as bad as your notes say.

I naively took a black plastic bag with me, thinking I could at least get rid of some of the stuff. When I looked into the pit, there are hypodermic needles and all sorts of unpleasantness, so I decided not to risk touching anything. This looks like a hang-out, rather than anything left over from forest operations. On the way down into Caerphilly I was passed on the narrow road by several cars of teenagers - the road only leads up here.

The saddest thing is that on the walk here from Pontypridd I visited at least half a dozen other barrows, and this one is undoubtedly the finest one on the whole of the Sengenydd ridge. What a shame.

Let me know if you got a response, I'll probably send a follow-up but I'm not expecting any action to be taken. It really needs a proper clean-up by, in all likelihood, volunteers. But I have this horrible feeling that any clean-up might be a temporary respite.