In general, the only available options are either an evaporation pond or a recirculation pond. Landfill leachate ponds are a specialized use that may require a multi-phase approach, but the primary goal is to prevent any landfill leachate water from contaminating soil and groundwater. Water in recirculating ponds is pumped back into capped landfills for a period of months, but landfills constantly produce and absorb additional water, so a recirculating pump must eventually be drained and its contents hauled away. Evaporation ponds reduce water more efficiently so that only a small amount of waste material remains. The reduced disposal costs can be dramatic. Landfill leachate has little value and no alternative use available because it’s an undefined mix of organic matter, various heavy metals and inorganic macro components that are not worth the cost required to separate. The decomposing waste from open and operating landfills generates liquid that is added to by storm water to generate more runoff than that of a closed and capped landfill, and the runoff commonly includes bacteria in addition to chemical contaminants. Evaporation is most often the best and safest way to handle such material.
Evaporation ponds have additional advantages. They are relatively inexpensive to build and install, and they may be sized to handle the largest expected daily release from the landfill, or allowed to stand empty at times when that level isn’t reached. There is then no possibility of overflow or unexpected processing costs when daily release rates are on the high end of the scale. In addition, changing regulations may mandate future restrictions, and evaporation ponds can be relatively easily upgraded, expanded or supplemented with new ponds as necessary, even when they must conform to newer requirements. Only six percent of landfill facilities were using zero discharge evaporation methods in 2018. The overwhelming majority were still transporting leachates to distant treatment facilities or discharging directly into local sewers, both expensive and inefficient. Despite the required initial investment, evaporation ponds are quite possibly the most reliable and cost-effective solution for landfill management.
