It depends who you are – the installer or the owner!
The installer of a decorative pond liner asked when the survey should best be performed – before or after placing the cover soil? The project specifications required a survey to be done by the installer but did not state when. The installer was not responsible for placing cover soil, but knew that the earth mover had never worked on top of a geomembrane, so elected to do it before the cover soil was placed. Clearly, it is more in the interest of the owner to perform the survey after the soil has been placed, to catch all leaks in the liner. Statistics show that 74% of the leaks in a liner are made during placement of the cover soil. But arguments can arise as to whether the earth mover or the installer is responsible for the cost of repairing which holes.
Four small leaks were found when the liner was surveyed and all were satisfactorily repaired. We were passing the site about a week later so dropped in to see how it looked. Cover soil had been placed and the upper slopes sodded. It looked neat and tidy. However, when we walked on the soil we noticed many large (3 in.) pieces of broken glass in it! How many holes now in the liner? Who knows!? But the installer did the required survey and covered his own work. The owner probably did not get what he wanted because he or his engineer did not specify the survey to be done after cover soil had been placed.
In critical situations there is much to be said for performing surveys both before and after cover soil placement – delineate responsibility for damage, make some repairs without excavating that might cause additional damage.
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| Ian Peggs leading a T-CLIC Liner Integrity Survey course test cell training session. |
If you have questions or comments, or would like to participate in the next LIS training session, please contact Ian Peggs.
