Seepage Control by Particle Size Selection

EARTH linings are frequently used in reservoirs, canals, and other earth structures to control liquid movement for the purposes of pollution control, water conservation, and structural stability. Clays or chemicals are often added to linings to reduce the hydraulic con-ductivity of the native soil, however, both additives sometimes decrease in effectiveness with time. Under ordinary conditions, gravel is nearly inert and does not change properties with time. The hydraulic con-ductivity of permeable soil was substantially reduced by adding gravel that was at least 15 times larger than the particle size of the soil. The amount of clay required to control seepage was reduced by half by the addi-tion of graved.