I am not sure how long ago you were there Ian, but I should think the area is much the same if you have been there in the five or six years, but some areas are being fenced off to some degree as they are in the process of creating a Mining Heritage Trail.
I remember the site being in a lot better condition in the 60's and early 70's - after this time quite a lot of work was done re-working the dumps, and quite large areas of the dumps were removed, and also some of the structures on the site were semi demolished. As you know DGC covers a large area and many interesting features are still to be seen, however the commercial woodland that covers most of the area obscures a great deal. The railway tunnel marked on Richrdsons Plan as "Arch Dump" has been demolished...not sure if that was the case when you were there last.
Steve