For those unfamiliar with the heap leach pad/pond

For those unfamiliar with the heap leach pad/pond here is some good info.

Heap leaching is the process to extract precious metals like gold, silver, copper and uranium from their ore by placing them on a pad (a base) in a heap and sprinkling a leaching solvent, such as cyanide or acids, over the heap. This process dissolves the metals and they collect at the bottom of the pad. The metal is then further processed. This methodology is mostly used for low-grade ores, and the basic processing steps involve crushing and sometime grinding.
The stages for heap leaching can be described as:

Ground Preparation and pad construction: Here the soil on a slightly sloping ground is compacted and covered by an impermeable pad (can be made of plastic).
Ore stacking: Then the crushed ore is stacked in the form of big heaps. Amount of fines is decreases as low as possible to improve permeability.
Then the leaching agent such as cyanide or acid is sprayed over the heap.
As, the reagent passes through the heap; the valuable metals get dissolved in it.
The solution containing metal is drained from the heap and collected in a pond and the solution is sent for subsequent process for metal recovery .
Here is an illustration of the process:





The two large tanks visible above store the acid used in the leaching process.