COMPLETE DISSOLUTION OF TRICHLOROETHYLENE IN SATURATED POROUS-MEDIA

Porous media containing trichloroethylene (TCE) trapped at residual sa turation in otherwise water-saturated porous media were flushed with w ater to assess the dissolution rate of TCE as TCE volumetric fractions approached zero. Careful attention to column design and experimental methods limited the effect of column materials on effluent concentrati ons. Effluent concentration measurements during TCE dissolution are pr esented for a glass bead porous medium, a mixed sand, and a treated so il. Effluent concentrations were measured as they decreased below 5 mu g/L, the maxim um allowinant level, in the gla ss bead and mixed sand media. Efflable contamuent concentrations from columns packed with tr eated soil were measured down to 20 mu g/L. Solvent extraction of the treated soil after the dissolution experiments revealed that extremely small quantities of TCE were retained in this medium. Results from pa rallel experiments on columns exposed to only aqueous TCE suggest that TCE remaining in the treated soil columns was sorbed to the porous me dium. Existing power-law models were capable of describing TCE dissolu tion in these media, if the exponent an the TCE Volume fraction was mo dified appropriately.