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A laboratory column technique was developed to measure retardation factors (Rf) of volatile organic compounds (VOC) using geological material obtained from an outwash aquifer. The site is a former solvent disposal pit near Ottawa, Canada. The experimental column was designed as a closed system from introduction of the sample to the collection and analysis of effluent samples to prevent loss through volatilization of the VOCs. The retardation of the volatile compounds 1,4‐dioxane, tetrahydrofuran, diethyl ether, 1,2‐dichloroethane, chloroform, 1,1‐dichloroethene, and benzene was measured. The centers of mass of both the contaminant and conservative tracer breakthrough curves were compared to determine Rf. The measured Rf values ranged from 1.1 (1,4‐dioxane) to 14.3 (benzene) compared with values of 1.6 and 8.8 derived from contaminant plume lengths. Considering the uncertainty of the disposal history at the site, the values are of reasonable agreement in comparison.

Organic chemicals disposed between 1969 and 1980 in a “Special Waste Compound” at the Gloucester Landfill near Ottawa, Canada, are migrating through a confined outwash aquifer. The subsurface distribution of the chemicals down gradient from the disposal site suggests that chromatographic dispersion (i.e. aqueous phase solute transport plus sorption) is the major process controlling migration. Retardation factors calculated on the basis of relative lengths of contaminant plumes agree closely with those determined independently during a purge-well test and indicate a linear relationship with the logarithm of the octanol/water partition coefficient (Kow): The slope, 0.50, of this relationship is at the low end of the range of values reported for other expressions of the same form determined principally on the basis of laboratory experiments. This lower slope may reflect the fact that in aquifers flow is predominantly through the coarser, less organic-rich units. The relatively low range of Kow values (log Kow from −0.27 to 2.83) represented by the contaminants may also be a factor contributing to a smaller slope value.

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