Leaking Concrete Tank
Leaking Concrete Tank
(OP)
We have a 20 year old, 145m3 tank which we recently lined with spray-on liquid rubber due to excessive water that was being lost. But, since lining, when tested for leakage, we have continued to lose about 40m3 in 3 days at around a constant rate. Does anyone know of a method to detect the leak. One meter of this tank is below ground. Certain parts of the wall is weeping. There are three manholes and three outlet nozzles, one drain and one inlet from the top of the tank. Any help will be much appreciated. Thanks






RE: Leaking Concrete Tank
Too bad you didn't ask before you sprayed that gunk on. I bet they promised that it would stop your leaks easy. Where are they now? The problem is that if there's a crack, the spray on either transmits the crack or fails at it.
For individual wall cracks, you should epoxy inject. If the whole tank is bad, sheet liners are much better. You batten them to the boundaries above the water line.
RE: Leaking Concrete Tank
we've used bentonite clay liners for pond lining on fire-water-supply ponds. when those leak, the manufacturer recommends pouring sacks of powdered bentonite (from the well driller supply store) into the pond. the bentonite seeks the leak and plugs it up. i'm not saying that would be a permanent fix for your situation, but i could imagine that it would seek the leak as well, accumulate, and even may plug... then you drain the tank slowly out the outlet and seek out the places that look like the clay accumulated. there would probably be a sweet spot where dumping more sacks would just coat the floor and obscure indications. you should check, but i would bet the gray bentonite would be compatible with your membrane and different enough in color to indicate. also, it would seem like the clay could be removed by pressure washing afterwards and not be much of a concern for the tank use.....
again, never tried it. interested in what the forum throws out there.
RE: Leaking Concrete Tank
Liquid Rubber sounds like snake oil. A spray on polyurea liner would have been much more applicable.
RE: Leaking Concrete Tank
Hopefully you get to the point where the level doesn't fall anymore, but if not then you know it's in the floor!
what is the physical size of this thing?
with that many nozzles and outlets it's likely that the seal between the rubber liner and the nozzle face is part of the problem. Once it gets behind the there then the water will appear some distance from the problem. First make sure the nozzle fixing is good before you start anything else.
I did a fire water tank with a rubber liner and that still leaked, but at least we could concentrate on the joins and the seals with the nozzles. Once we fixed that the tank was tight.
A 20 yr old concrete tank that has been leaking that much might have a load of other issues and replacement could easily be the next best solution rather than a quick non fix like a spray on solution.
My motto: Learn something new every day
Also: There's usually a good reason why everyone does it that way
RE: Leaking Concrete Tank
RE: Leaking Concrete Tank
Littleinch, I have enclosed the drawings of this tank--it comprises of three cells all joined together by small opening at the bottom.
JedClampett, I may have to reline the whole tank with sheets. Do you have any product recommendation?
Darthsoilguy, that is a very interesting method--may probe a little more into it.
Gumpmaster, the liquid rubber we used is: http://www.liquidrubber.net.au/High-Build-PRODUCT-...
The top view is 7'10" x 19' - 3 off
RE: Leaking Concrete Tank
Sealing around the openings is a nuisance. But the good news is lining is probably cheaper or about the same as you spent already.
RE: Leaking Concrete Tank
RE: Leaking Concrete Tank
I'd recommend looking at a coated polyester such as Seaman's XR-3 or XR-5. It's much easier to install and repair than CSPE. The installation is more important than the product and most installers have a selection of products that they can offer. Focus on finding a quality installer first and then see what they recomend for products.
Are there any pipe penetrations below the water line? It wasn't clear from your drawing. If so, as others have said, that may be an important place to look at. If the leak is suspected there you may try epoxy injection at the wall pipe in addition to lining the tank.
RE: Leaking Concrete Tank
Therefore the leak is probably in the bottom 1m.
I can't work out what that weird sump thing is in the middle of the bottom chamber, but that's a good place to start.
Are there any pipes embedded in concrete? Can you get access to send a camera up them to see if these pipes are still there and not just corroded away?
Make sure it is the tank that is leaking and not the pipes or the seals around any pipe exits thought the concrete. The main concrete should be Ok unless you've had an earthquake recently, but any seals between sections might have started to perish.
you might need to excavate those particular spots to find out, but it's best to do this now than spend more money on a liner and find it still doesn't stop leaking....
My motto: Learn something new every day
Also: There's usually a good reason why everyone does it that way
RE: Leaking Concrete Tank
Gumpmaster, thanks for the info on liner.
Cheers
RE: Leaking Concrete Tank
Please let us know how it works out and pictures are always nice.
Have in the back pocket a cost for a brand new tank in concrete or GRP though to benchmark the costs of fixing something that is probably getting a little close to its effective life.
Good luck - fixing leaking tanks can be a never ending problem when it is not clear where it's all leaking out from....
My motto: Learn something new every day
Also: There's usually a good reason why everyone does it that way