Summary

Past studies have demonstrated that the average movement and spread of subsurface contamination depends on heterogeneity in the hydraulic conductivity field. However, variability in hydraulic conductivity and its relationship to geologic formation processes and geologic observations is poorly understood.

The hydraulic conductivity of glacial outwash sediments on Cape Cod Massachusetts was studied to address this need. Exposed sediments were classified into lithofacies and hydraulic conductivity was measured for sediment samples using permeameter tests or particle size analysis. The geometric mean hydraulic conductivity was calculated as a function of facies and maximum clast size (used as a quantitative measure of proximity to the sediment source).

The results show that the geometric mean hydraulic conductivity for the cross bedded sand facies varied little with maximum clast size. The mean hydraulic conductivity for gravel samples reached a peak value around a maximum clast size of about 32 cm. The horizontally bedded sand increased in permeability as maximum clast size decreased.

AAPG Search and Discovery Article #90937©1998 AAPG Annual Convention and Exhibition, Salt Lake City, Utah