Surface Impoundment Leak Detection

Q: We have a double composite surface impoundment with a leak detection between the liner system containing frackwater (brine with high chlorides content) and are seeing evidence of a leak in the primary liner after five years of excellent operations. The pond and leak detection zone (LDZ) levels have been stable for years, but after unusually heavy rain, the head in the surface impoundment and the flows in the LDZ have increased significantly. In addition, we confirmed that we have a “true leak” and not groundwater infiltration by measuring the conductivity of the water in the LDZ, which is high. Can you offer any suggestions?

A: Something seems strange. I don’t think this is a durability or aging issue. I think you have a leak in the upper slope of the surface impoundment, which usually acts as the freeboard. I would lower the head in the impoundment, then send a human down (rappel) each fusion seam and check for a breach or tear in the seams. I would also look for punctures in the freeboard. Such damage could be caused by animals or vandalism. I would be very curious what you find.