Concrete Tank Leak Test 2

[jqeng]

I have a concrete tank that needs a leak test done. The leak test will be done after its already been backfilled and the tank is 21m by 21m and holds about 3000m3 of water. Wall thickness ranges from 600mm at the bottom to 450mm at the top (7.1m tall).

My question is once the tank is filled up, the concrete will absorb some of the water. How long should I wait before I start my actual measurement of change in water height. How long should I give the concrete to absorb the bulk of what it will absorb?

 

[JedClampett]

We say 24 hours.
If you have time, you might want to wait a week as sometimes some small leaks seal themselves as the concrete re-hydrates from the liquid in the tank.

 

[steelbeam]

I do tank designs and water tight testing for our structures on all of our water and waste water projects. I highly suggest using as a guide,"Tightness Testing of Environmental Engineering Concrete Structures" ACI 350.1-01. By the way, this guide suggests that the unlined tank be filled for 3 days for stabilization prior to starting the test. Also the tank should not be backfilled durng the test, otherwise how are you and the contractor going to know where it may be leaking and need repairs?
I hope this helps.

 

[ATSE]

Agree with steelbeam re: ACI 350.1, even if you're not in the US.
Soil backfill prior to leak testing was a mistake.

 

[waterpipe]

jqeng,

cross posting is against the forum's rules.
I've left you a respond in connection to your question, in the same post that you have put at:
Civil/Environmental engineering other topics Forum.

 

[waterpipe]

Here's the link to that post for the people who follow this post:
thread194-295929