This article showcases the challenges faced in the Cayman Islands for the design and installation of a well-field in an aquifer, while preventing the degradation a freshwater lens. In the Cayman Islands, it is typical to abstract the saline water needed for reverse osmosis plants from deep wells and dispose brines into zones that are deeper than the location zones.

In this particular case, the low porosity cap rock of the Cayman Formation isolated effectively the freshwater lens from water circulation in the deeper part of the succession. The well-field abstracted saline water from an open zone below the cap rock of the Cayman Formation at a depth of 45–65 m, and disposed brine at a depth of 62–86 m, where the bottom of the brine disposal zone is highly cavernous.    

The plant became operational in 1998, and production capacity was doubled in 1999. The Lower Valley reverse osmosis plant has been operating successfully without adverse effects on the Lower Valley freshwater lens. This is evident by water quality data obtained from a network of monitoring wells designed to monitor the effects of the plant on the freshwater lens.