I saw one other person posted on here with this issue, so I'll share what I've learned:
Full Forge Log (pastebin doesn't like 18MB files apparently):
Biomes 0' Plenty 22.214.171.1244
Forge 10.13.2.1224, 1230
I know that there's some kind of conflict between the Gregtech world generation and the Biomes O' Plenty world generation. If you remove either, the issue goes away entirely. I'm planning on posting the same information on their github, but I wanted to make sure the people here were aware, and to see if Greg could take a look and rule out an issue on his side.