Percolation ponds were the means to dispose radio active wastes , effluents and waste water through injection wells from 1950s to 90s in the U.S. One of the worst examples was Idaho Nuclear Laboratory, Idaho. Initially the Nuclear power projects were to be started in isolated areas with ample water to be used in reactors and to push out/in the wastes.
The ponds or water masses were supposed to be safe as percolation into the subsoil 'aquifers' or water streams was assumed negligent with wastes 'lining' the cracks and rocks.
But it was observed that aquifers were turning 'plumes' or contaminated and ground water in surrounding areas dangerously radioactive and harmful. Thus these wells had either been redesigned like the Inter connected Pond Routing Storm (ICPRS) water models to name one or relocated and converted into 'capped' evaporation ponds.
The injection wells and in turn percolation ponds had wastes like di/tri/tetra/choro ethane etc., and same injection wells are now used to inject Sodium Lactate for decontamination.