Salt Caverns are developed by washing out rock salt formations with pure river water.
A wellhead is installed at a proposed site and a hole is drilled suitable for production requirements. String arrangements and configurations of new caverns are based on flow rate injection requirements.
During Cavern Wash (Leaching Phase) fresh water enters the cavern through the wash string and due to its less specific gravity the fresh water goes up in the cavern and mixes
with the surrounding brine. Finally, the diluted brine reaches the cavern wall and dissolves the salt. The re-concentrated brine drops down along the wall driven by it high specific gravity and is then sent out of the cavern through the annulus.
For this whole process to work there must be enough pressure to push water into the cavern and a brine disposal system to send the displaced unsaturated brine.