Concrete Water Tank Leak....Now What?
Concrete Water Tank Leak....Now What?
(OP)
Does anyone have some suggestions on cast in place concrete repair solutions in regards to water tightness?
I have a 22,000 cubic foot rectangular potable water tank that just went through the specified leak test, and...it leaks in about 5 spots. The owner has described them as "major" leaks. We went through a lot of effort to spec the right mix, Xypex waterproofing admixtures etc., but in the end, we have reason to believe the contractor didn't vibrate the walls like he should have.
So far the research I have come up with suggests:
1)Line exterior walls with bentonite filled boards. Patch interior with polymer concrete and then line with glass reinforced plastic.
2)HLM 5000 spray grade waterproofing
3) Various membranes (Atlas) and other spray on tank linings.
Does anyone have experience or success with a particular method or product? Again, the key words are POTABLE water, so whatever we put in there must be pretty inert.
I have a 22,000 cubic foot rectangular potable water tank that just went through the specified leak test, and...it leaks in about 5 spots. The owner has described them as "major" leaks. We went through a lot of effort to spec the right mix, Xypex waterproofing admixtures etc., but in the end, we have reason to believe the contractor didn't vibrate the walls like he should have.
So far the research I have come up with suggests:
1)Line exterior walls with bentonite filled boards. Patch interior with polymer concrete and then line with glass reinforced plastic.
2)HLM 5000 spray grade waterproofing
3) Various membranes (Atlas) and other spray on tank linings.
Does anyone have experience or success with a particular method or product? Again, the key words are POTABLE water, so whatever we put in there must be pretty inert.






RE: Concrete Water Tank Leak....Now What?
RE: Concrete Water Tank Leak....Now What?
Where is it leaking? Cracks/construccion joints/ through the concrete itself?
For leaks trough cracks/construction joints I have used Xypex, both as a slurry applied on the face of the concrete (kind of painted on) and as a paste forming a 2 inch triangle in a joint betwen wall and base slab. Both applications very sucessfuly and reasonably cheap (some of the options you talk about sound expensive). If I remember right once cured, Xypex is as good or as bad to water as normal concrete.
As with everything good surface prep/application/curing process are very important.
In my case the leaks were very minor, in the order of a couple of cups of liters a day maximum, sometimes just dampness in the concrete wall.
We considered sprayed on membrane (some were epoxy based, other were polymer or plastic) but discarted it. The problem was that they could not guarantee a design life of more than 15/20 years.
In your case, would it not be better to treat the problem areas instead of all the tank?
RE: Concrete Water Tank Leak....Now What?
RE: Concrete Water Tank Leak....Now What?
Contractor used Sika product to repair leaking concrete tank on a project. Need to establish limits of defects to for repair method.
RE: Concrete Water Tank Leak....Now What?
Dik
RE: Concrete Water Tank Leak....Now What?
The reason we are thinking the cause is improper vibration is because the contractor had a form blow out during the wall pour, and proceeded after the blow out with "extra caution" (i.e. limited to no vibration). But that is an assumption that we will need to verify.
RE: Concrete Water Tank Leak....Now What?
RE: Concrete Water Tank Leak....Now What?
I would recommend getting xypex involved as they are quite often willing to provided extra product for free if they think the leaks will give them a bad name.
Arguing with an engineer is like wrestling with a pig in mud. After a while you realize that they like it
RE: Concrete Water Tank Leak....Now What?
The contractor should pay for all this.
RE: Concrete Water Tank Leak....Now What?
Another problem I have come across is ground water ingress during consttruction causing washout of fines at the construction joints.
I agree with others that an injection system is the way to go. First you have to select the system either epoxy or foam and then start drilling and pressure grouting. The problem is that once you seal one leak the water can find another path and reappear. Also once the leaks have been repaired people may start focussing on damp spots.
RE: Concrete Water Tank Leak....Now What?
The real problem we are about to face is how we poured the new tank. Essentially an existing water tank (concrete, above grade, rectangular) was used as a form, after we removed the roof. We cast a new, independent structure inside the original tank, and extended the height (and volume) of the tank by about vertical feet.
ATTACHED IS A SKETCH of the tank configuration and leak location. There is a good chance the cold joint may be leaking (?) but we cannot see it. Unforunately, the leaky side is the side that is backfilled.
The tank is above grade, with one side backed into a hill.
At this point, due to the fact that the main leaks are hidden, we might have to drain the tank and do a roll-on liner. The other methods are too expensive for a hit and miss application.
I was always taught that concrete is very porous. I probably wouldn't have thought it could be used as a water storage device until I saw the existing tank perform. How much water does new concrete absorb? I'm sure it depends on density, add mixtures and a handful of other factors. Is it possible that a tank this size could soak up 500+ gallons of water in 72 hours?
RE: Concrete Water Tank Leak....Now What?
If you did the leak test right after the initial filling, see if you can do another one to find out what its leakage rate is now.
Concrete is quite water tight. A well built, well reinforced tank won't have any problems for many many years.
RE: Concrete Water Tank Leak....Now What?
If difficult to visually spot the defects, you might try to use "dye" to uncover them as Jed mentioned above, however, I would do differently - drain the tank, and fill the space in between new and old tanks with water and let it seep back in, now you should be able to spot the defective locations easily.
Well, to me, liner is cheaper and less messy. Good luck.
RE: Concrete Water Tank Leak....Now What?
RE: Concrete Water Tank Leak....Now What?
You could cover the whole inside face or just the areas and seams you think are causing problems but water might still migrate though the concrete from areas not covered.
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