re: Need culvert/catch basin help. 24" culvert into 28" hole (see picture)

Temporarily seal off the outside of the basin at the pipe with gorilla tape and back that with plywood and dirt for reinforcement.

From the inside of the basin fill the gap with closed cell spray foam. wear gloves


Once dry remove the tape and plywood and use fiberglass mortar tape and quick patch to create a durable outer seal around the pipe and then back fill the hole with dirt once dry.

You could also put same tape and mortar on inside if you wish.








As the culvert and basin settle though it is very like that the mortar will crack.