Once I got it based, I was glad that I did not make it bigger like I wanted too. The base ended up being roughly 17 x 14 inches as it is. It big enough to fit my Mig Mek Stompa inside of it.
Anyway, I made the rubble using a mixture of basing ballast, sand, and plastic sprues that I ground up using a hand meat grinder that I keep just for making rubble. It works great.
I still want to add some more detail to it before I declare it ready for painting, especially to the interior. It needs something more, I am just not sure what to add at this time. Maybe some fallen floor panels or rubble piles. I am planning to make this my Painting Challenge Project for the month of May, so I still have some time to work on it.