We have a couple holes in our basement floor that I assume drain to the sewer, but they're not covered. A guy installing our water heater recommended covering them so we don't get sewer gas or something. We stuffed plastic bags partially down them for now, but wondering what a more long term solution would be. Is it acceptable to fill them with concrete? Are they there from a heater or something from a long time ago or do they stool serve a purpose? (The house was constructed in 1920.)
We want to at least level the floor, but do we need to leave this open?
We're in northern Minnesota if that matters.