Brine ponds and, indeed, evaporation ponds in general, work on the premise that a volume of liquid exposed to sunlight and relatively dry air can be reduced by allowing water to evaporate into the atmosphere, leaving behind non-volatile dissolved contaminants such as salt and other minerals. Sometimes the remaining substances can be harvested and processed for profit.
Evaporation ponds are most efficient when a large area is exposed to sunlight and air, so ponds should have a shallow profile with maximized surface area. Ideally, evaporative ponds are sited where exposure to sunlight is maximized, the air is naturally dry, and steady mild winds are present. In some cases, the evaporative advantage of wind is enhanced by providing artificial air movement or in the case of brine mining, by adding evaporative membranes. These are textile sheets that are sprayed with brine and exposed to wind, which significantly increases the rate of evaporation. Valuable mineral crystals can be harvested by scraping them directly off the membrane.
While some evaporative ponds may include some sort of ballast material (gravel, blocks, sand) spread over the liner in order to keep it from shifting, that won’t work for brine ponds where valuable mineral deposits are to be collected. Instead, these ponds should have smooth sides and bottoms where crystals can be efficiently scraped and gathered for harvest. If shifting is a concern, brine ponds may be constructed instead with a smooth concrete layer on top of the impermeable liner. In any case, floating ballast balls that are commonly used to discourage wildlife access on storage ponds are not employed in evaporation ponds since anything floating on the surface will directly reduce evaporative efficiency.
