We have to add on to an existing concrete manure pit. The local code allows some leakage, but personally and professionally I'd like to avoid any significant leakage at all.
Common practice seems to be to cut a notch into the existing wall and create a construction joint. I would think doweling would be required as well. There is a bentonite based sealant, RX, that is sometimes used. It's not recommended where the bentonite can, and apparently has, actually swelled with enough force to crack the concrete.
Any ideas about other directions would be appreciated.
Ed Fasula, EIT