Here's where it's being placed.
View attachment 168733
Here's the plan that we saw earlier this year on it
From this thread:
http://forums.wdwmagic.com/threads/osceola-interchange-road-permits.913026/page-3
Now what is this for? Well good question. Basically what disney is doing is they are building an enormous retention pond on the west side of World Drive and they are using the material they are digging up from that hole as fill on the East side of the road. The fill will be going in quite a few areas but quite a bit of it will be used for the interchange projects as well as the regrading of the expanded and reconfigured DHS parking area. Currently on the west side of the road there is a 3 story high pile of dirt several football fields in size (hidden behind the trees) and they have barely started digging the retention pond. All of this dirt that's piled up so far is from several other projects from what I can tell.