That's pretty much the same reply that I usually get from Lands Dept when reporting dumping at Kam Tin - if it's private land they cannot take action.
One possibility to investigate is whether this dumping is being carried out on land zoned for agriculture (check the government's OZP for the area). If so, you could report it to Planning Dept to see if they can take action.
At Kam Tin, I have reported similar incidents several times but usually there seems to be little the government can do. The extensive filling on the Buffalo Fields last summer was on agricultural land, and this finally stopped after the Planning Dept got involved (although I don't know how long that will last). I'm still hoping the enforcement tema will force the land owner to remove the filling, but that may prove to be too much to hope!
