Is this an old septic tank?
This concrete box is in the back yard. Its about 60" x 16" with two lift-off covers that are sealed with tar. Don't know how deep it is. The side close to the camera looks like some of it was cut or busted off. The house was built in 1974 and enlarged in '86 but this looks more old fashioned than '70s. I want to break it up and fill it in but don;t want any surprises.