Reply #304: The septic tanks I've seen come with a square concrete entrance "plug" with a

[AikidoSoul]

metal ring to pull the cover off. If a tornado comes you don't want to be struggling with a heavy concrete lid so we'd replace it with a wood trap-door. Then we would cut out a larger entrance on the other end for another entrance so we don't feel trapped. For insurance we would also have a hydraulic jack in case heavy stuff gets blown around that settles on both entrances so we'd have a way to push the lid up to to get out.