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Q: We recently relined an aeration pond at a POTW with a 45 mil GRI GM-30 barrier. It was successfully lined for 30 years with a 45 mil CSPE (Hypalon®) liner that was, unfortunately, punctured and torn beyond repair by a fallen tree from outside the fence line. The relined surface impoundment currently is leaking greater than 10,000 gpad, even after leak integrity surveys and three attempts to repair it. Can you offer advice on how we can get this facility back online?
A: You are using the wrong barrier for your critical application. A GRI GM-30 barrier is fine for a temporary drop in aquaculture, oil and gas, or animal feed lot pond. However, you are dealing with a critical structure that needs to last for many years. Your application is challenging and unfortunately, you chose a barrier that is not good under tension. The seams (extrusion and fusion) and connections at your installation are going through repeated thermal cycling. As such, they are rupturing the relatively thin surface ply from the slit film woven polyethylene scrim at the center of the barrier and creating a multitude of leaks within and through your liner system. I am sorry for the bad news, but your repairs are merely temporary bandages. You will most likely need to tear out the new GRI GM-30 liner and replace it with one of the following:
GRI GM-34: EIA
GRI GM-28: CSPE
GRI GM-25: LLDPE-R
GRI GM-18: fPP-R
GRI GM-21: EPDM-R
There are hundreds of barriers and geomembranes to choose from in our industry for containment applications such as yours. Unfortunately, they are not all appropriate for critical surface impoundment applications, particularly when the liner is acting in isolation (i.e., performance of your liner system will be greatly enhanced by a GCL or CCL under the geomembrane).