Simultaneous counter-flow of chlorinated volatile organic compounds across the saturated-unsaturated interface region of an aquifer.

Concentrations of chlorinated volatile organic compounds (Cl-VOCs) at the saturated-unsaturated interface region (SUIR; depth of approximately 18m) of a sandy phreatic aquifer were measured in two monitoring wells located 25m apart. The concentrations of the Cl-VOCs obtained above and below the water table along a 413-day period are interpreted to depict variable, simultaneous and independent movement of trichlorothene, tetrachloroethene, 1,1-dichloroethene, cis-1,2-dichloroethene, 1,1,1-trichloroethane, chloroform and 1,1-dichloroethane vapors in opposite directions across the SUIR.