I have a “sunken” utility room whose floor is 8 3/4 inches lower than the rest of the house, and want to raise it to the same level as the other floor. The utility room floor is a concrete slab that has a toilet (the drain pipe is embedded in concrete). How do I do this correctly? I may be able to cut the top of the drain pipe / flange out with a Dremel, but that probaly creates other problems. Any advise is appreciated.