I think we've mentioned this before, but this year's update of the google maps imagery really shows the progress on the infill project behind the maintenance area. It's been a slow project that they seemingly add to as they have additional fill. It's been an obvious dump site since 2009, but since 2013 they've really amped up, even after Outlaw Run construction was complete.
Seems a little strange to me, since they have room to expand the maintenance area in other places, and it would take an enormous amount of fill to level that valley enough to be useful at that elevation, but of course they have filled in valleys before...