What you need is Hawk-Seal made by Blackhawk company.

It comes in a butyl rope coil and is used in all underground sewer and water pre-castings, and wherever two pieces are connected.

It is used on all sanitary or storm sewer manholes and in multi piece concrete septic tank connections.

Any precast place should have it, and also available on the mighty internet.

All the really good ideas I've ever had came to me while I was milking a cow.