Abstract: Because of severe seepage and calcium-bleeding in Luowan Dam,decision has been made in2001to carry out anti-seepage treatment at upstream facing.A10-cm-thick anti-seepage bituminous concrete is cast to cover the face slab,using plastic sealing material at expansion crack,lying3～5-m-thick clay blanket along dam datum line upstream.A cofferdam was built in front of the dam for anti-seepage treatment under EL338m to make construction in the dry.?