The dimensions of the right side where the does and buck are is 8'x14'. There is no bottom, but it is retained by a 2' front and right side wall. The interior hight is 6' so you can comfortably stand up. We took a chance that the redwood roots would retain them in the back, and so far that has worked. They did dig under the front wall last year, but I installed a 2' wide armored path and they haven't dug out since.
I have 3 does and one buck in the breeding side of the colony, and 11 juniors on the other side. There are 17 babies (under 5 weeks) in with the does and buck, with 2 of the does pregnant again... Yikes!
The left side of the colony where the juniors are has 2"x4" wire on the bottom covered with soil, so there is no digging allowed on that side. Instead, I built wooden hiding holes for them which they really like.
I plan on putting the buck in the junior side for a while to give the does a break after this next round of kits.
If you're interested in seeing more specific details, I'll be glad to send you more pictures.