I have a precast catch basin as a pond overflow, and I later added a 12in precast shim on top of it to raise the level. I used sort of self leveling poly product for concrete joints, and it held for a few years be has failed and is leaking. I am in the cold northeast and the pond freezes hard so I assume that broke a seal. The product may not have been intended for continuous submersion. I am draining the pond for other work and can try to fix this, but don't want to do it again. I assume i should lift it off and redo. Any recommendations? I did find a specialty gasket make be a company for this, but it was like $900 for a roll- out of my budget.
