So I'll try to keep this short. I have three pits in my crawl space. Ejector pump pit, sump pump pit, and this one. I had plumbers replace our existing sump pump and while they were there I asked them about this pit. Guy in charge seemed to think it was a pit separate made for grease build up. Said back in the day some homes had those installed. He recommended I get a wet vac and suck up the gunk inside, fill it with gravel and throw a lid on it. So taking his advice, I grabbed the vac got in and started sucking it up. My Lord. The stench it released was the worst smelling thing I've experienced. Is it possible it's sewage? And that he's wrong? Should I seek another opinion? I sucked up most of the liquid, now all that's remaining is bigger clumps and solidified stuff. Pardon my ignorance also, I'm just beginning to learn about all of this. Thank you