If there is a better catagory to ask this question, someone please let me know.
We have our old kitchen torn out and under the floor, in the dirt, (no basement) is a dome about 20" across that is made of something cast, we think, it might be crock/pottery. It looks like a cylinder that is in the ground on end. My contractor has only exposed about 15-18" of it, and doesn't intend to dig around it anymore. He's not willing to crack it open either....I think he should be more brave. Does anyone have any idea what we've come across? There do not seem to be lines to it, although they may be further underground. The existing plumbing and septic do not go to it, as far as we can tell. Thanks for any help. oldfarmhousekeeper