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sealing old septic tanks

operatorjoe

Civil/Environmental
Sep 5, 2013
14
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
 
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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?
 
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?
Thank you for your reply. I was fairly certain that replacement was cheaper than any alternative. I don't believe that all the original customers have intrusion. There are about 45 houses that are in a swampy area. Water table in that area is very close to surface. Water meter boxes will stand with water within 4-6 inches from top. The local nickname for the sub-division is crawdad estates.
 
There was a product called Vandex that was a crystalline sealant...
 
You will probably find that the piping systems have more I/I than the septic tanks.

Recommend the entire system be replaced starting from the residential drain pipe.
 
as BMIR says, more likely to have I&I in the pipework.
Recently went to a conference where a paper was submitted on very high I&I in a low pressure sewer network. For those of you who do not know this is a pumped network with every household having a small grinder pump and common rising main, the system is designed without I&I as it is under pressure and if anything the system will leak into the soil. What the presenter found was that during large storm events the flat gardens were flooding and flowing into the gulley traps (which had not been installed to code because of the flat properties). Point is you need to locate the source of the infiltration

(FYI the LP sewer system managed to cope with the spikes even though it was significantly higher than the design peak)
 

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