The building of pads for copper heap leach is well known technology. The goal is essentially zero seepage fo plastic liners ocvered with a protective layer are often use. is it becoming more common to have a dual barrier separated by a layer where leakage can be intercepted and...
If you have designed this dam without understanding the hydrological regime in the area, the characteristics and chemistry of the tailings, and engineered the dam to allow you to intercept and collect the seepage you have been pretty negligent unless the seepage is benign which sounds unlikely...
