I have a concrete septic tank on some land I have purchased and the effluent pipe entering the septic tank is broken so I need to replace it. The pipe entering the tank does not seem to be attached to the tank -- it just runs into the hole. Is this how its typically done? Should the pipe be coupled to the tank in some way or does it just need to run through the hole, and how far should it run through the hole? Thanks!

First I'd suggest you replace with PVC. The pipe enters the hole in the side of the tank near the top. It is frequently sealed with tar or grouted but that can fall apart over the years. The wall of the tank is less than 4" so put about 6" of pipe into the hole and grout it. I assume the old pipe was cast or clay, in any case if it broke replace the entire run to the house. This can be a back breaker since most lines run below 42" so maybe a few bids from excavators won't hurt. They may give you a fairly good deal and just doing the whole project. I know how to do it, I would choose to subcontract it out and sit in the shade.