Abstract
Of the various subsurface intake systems available for use, gallery intake systems have the greatest potential to provide the feed water requirements of very large-capacity seawater reverse osmosis (SWRO) systems because of their scalability and flexibility as far as hydrogeological constraints. A beach gallery system is constructed beneath the intertidal zone of the beach where the wave action continuously cleans the face of the filter media. While it is designed similar to a slow sand filter, a clogging layer tends not to form at the sediment/water interface which allows it to be operated at a higher infiltration rate compared to a seabed gallery system. Design of a beach gallery system active layer (uppermost layer) must be compatible with the grain size characteristics of the beach into which it is constructed. It also must be constructed with sufficient thickness to avoid damage during storm events that produce large waves, which that can temporarily change the beach profile. The beach must be sufficiently stable so as not to have a prograding shoreline that could increase the distance from the gallery face to the sea which would decrease the rate of recharge and cause the intake to fail. This intake type is most suited for use on sandy beaches with moderate wave energy.