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A comparison between field and laboratory measurements of hydraulic conductivity in a varved clay

TitleA comparison between field and laboratory measurements of hydraulic conductivity in a varved clay
Publication TypeJournal Article
Year of Publication1994
AuthorsDegroot DJ, Lutenegger AJ
JournalHydraulic Conductivity and Waste Contaminant Transport in Soil
Start Page300
Pagination300-317
Date Published01/1994
Keywordsdilatometer, hydraulic conductivity, Piezocone, piezometers, varved clay
Abstract

The measurement of hydraulic conductivity using a variety of field and laboratory techniques was evaluated at a site consisting of medium stiff and soft lacustrine varved clay in western Massachusetts. Field measurements were obtained by conducting “slug” tests in both predrilled and push-in piezometers and also from pore pressure dissipation tests using the piezocone and flat dilatometer. Laboratory hydraulic conductivity values were obtained for both vertical and horizontal flow conditions using a flexible wall permeameter and by indirect estimation from 1-dimensional consolidation tests. Based on a comparison of tests conducted throughout the profile, laboratory flexible wall tests with vertical flow gave the lowest values of hydraulic conductivity whereas the predrilled piezometers yielded the highest values. Of all the field techniques, the push-in piezometers gave the lowest values. Hydraulic conductivity values interpreted from piezocone and flat dilatometer dissipation tests tended to be between those obtained from the predrilled and push-in piezometers. Results from tests in predrilled piezometers show that the hydraulic conductivity increases with increasing screen length, showing the influence of scale effects. The results of this study clearly show that estimation of hydraulic conductivity for this soil is highly dependent on scale effects, the test technique used and on the direction of flow (i.e., parallel versus perpendicular to the orientation of the varves).

DOI10.1520/STP23894S