Whenever I reopen a world with an active builder I get a CtD. Even when I'm in the same dimension. I have a ChickenChunks chunkloader keeping it's area loaded.

Crashlog: http://pastebin.com/ejAHZDkc

Ok, there seems to be a chunkloading conflict. To get your world to load you can probably disable the chunkloading ability of the builder in the config:

B:quarryChunkloads=false

Yup, that fixed it. For future reference does a builder only load the chunk it's currently placed and working in?

Only the chunk it is working in. It doesn't attemp to chunkload its own chunk

This was fixed in 4.21