Thanks for the response. Yes, this property has been on the city system since the 60s, so I'm assuming this setup (whatever it is) has probably been unused since that time
My wife and I recently purchased a home built around 1900. Digging in the side yard, we ran into a pipe coming out from under or house we didn't know about. We followed it and found it went into what looks like a metal barrel buried in the ground.
There are two pipes running into the barrel...