Effect of Sediment Concentration on Well Recharge in a Fine Sand Aquifer

Abstract

A model recharge well was constructed to simulate recharge into wells in a fine sand aquifer. The sand in the model aquifer was uniform fine sand and had a uniformity coefficient of 1.25 and an effective diameter of 144 microns. Both clear tap water and sediment laden water were used for recharge. Sediment laden water was obtained by mixing 50% bentonite and 50% kaolinite with tap water. Sediment concentrations were 100, 200, and 500 ppm. The piezometric surfaces near the recharge well were measured during the tests. Migration of sediment into the aquifer was determined by sampling the aquifer sand after the tests at predetermined distances from the well. The sediment in the recharge water highly affected the rate of recharge. During the period of the tests a reduction in hydraulic conductivity of the model aquifer of 15–46% occurred as a result of recharge with sediment laden water. Most of the sediment deposited in the aquifer was retained near the well screen.