I'm with Bay on the substrate question. I like using a coco fiber/ultra fine sand mix but also adhere to the suggestion of coco/peat (it's not actually peat moss, it's just called peat moss. real peat moss is dead - sphagnum, which everyone calls peat, is very much alive).
your emp should be fine, I'm sure it'll dig itself out so long as you didn't dump too much over the burrow.