Riverbank Filtration Provides Natural Filtration of Surface Water

Riverbank filtration is a natural process that permits surface water to be infiltrated into alluvial aquifers to replenish groundwater pumped from a well, gallery, or other water-producing structure. As water is pumped from the well, the water table is lowered resulting in a reversal of the hydraulic gradient that would normally discharge groundwater to the surface water source. Once groundwater has been pumped sufficiently, the surface water that is replacing groundwater from within the aquifer receives very slow filtration by riverbank and riverbed sediments as it migrates toward the well screens and pumps. During this slow infiltration, suspended particulates, such as turbidity and organic matter, are naturally filtered by the soils typically providing a consistent water quality, often characterized as of groundwater quality (or not under the direct influence of surface water) and thus not requiring full surface water treatment. Hydrogeological testing can illustrate the recharging of the pumped water by surface water to meet surface water rights, where applicable. Case examples of operating systems, the system characteristics and water quality issues for several utilities will be presented.