ESTIMATING HYDRAULIC CONDUCTIVITY OF COMPACTED CLAY LINERS

A database is described that contains laboratory measurements of hydraulic conductivity and associated soil properties that were extracted from construction reports for compacted soil liners. The database contains measurements conducted on a wide variety of soils from 67 landfills in North America. The database was used to evaluate relationships between hydraulic conductivity, compositional factors, and compaction variables and to identify minimum values for soil properties that are likely to yield a geometric mean hydraulic conductivity cl x 10(-7) cm/s. A graphical analysis suggests that a geometric mean hydraulic conductivity less than or equal to 1 x 10(-7) cm/s can be achieved if the liquid limit greater than or equal to 20, the plasticity index greater than or equal to 7, the percent fines (<No. 200 sieve) greater than or equal to 30%, and the percent clay (<2 mu m) greater than or equal to 15%. A multivariate regression equation was also developed that can be used to estimate the geometric mean hydraulic conductivity as a function of soil composition and compaction conditions.