We are installing a backflow check valve (BAD sewer back up with this summer's storms). During the process we dug this up. Does anyone know what it is? We're assuming it's an old form of flood control? Does anyone know how old? It was filled with concrete when we found it, presumably from the rehabber that did our house previous to us buying it. The cement looked new. Secondly, here is a picture of the unfinished basement before it was finished by the rehabber. I got it off a real estate site. Does anyone have any idea what that black pipe looking thing in the far left corner is? It is right where we dug up that old flood control and right where the main sewer comes into the house. He removed it and paved over it with cement and ceramic tile. Please solve this mystery! Thanks!









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The top photo looks like the "shell" for a combination backflow/gate valve but it is too far away to know for sure. I have no idea what the other photos are showing, much less what they are.

It doesn't look like a grease trap that I have ever seen, but I worked with a plumber from Chicago and he said that residential homes used to have grease interceptors installed. It is possible that this was an abandoned one that was filled in instead of being removed.