sealing old septic tanks

[operatorjoe]

I live in a small town in middle Tennessee. The town has a problem with I&I. The system only treats effluent from septic tanks. When system was built existing old concrete septic tanks were used. The tanks were not sealed against ground water intrusion. The ground water causes huge swings in flow and other problems. Is there any way to seal these old tanks without replacement?
Thanks

 

[swazimatt]

there may be some sort of chrystaline sealant that could be injected into the concrete, or if it is drained and cleaned it could be sealed on the inside. both options i believe will be more expensive than putting in a new tank.
are the tanks connected to the municipal WW network or pumped out and trucked to the treatment works? are you sure it is the tanks where you are getting the I&I and not old piping or low gulley traps that go to the tanks?