A prototype and large-scale soil liner were constructed to test whether compacted soil barriers in cover and liner systems could be built to meet the standard set by the U.S. Environmental Protection Agency for saturated hydraulic conductivity. In situ ponded infiltration rates into the prototype liner were measured and water containing fluorescein and rhodamine WT dyers was allowed to infiltrate in the prototype liner. Although the liner met the USEPA conductivity requirement, the dye flow paths indicated a need for better bonding between lifts and a reduction in soil clod sizes. These observations suggested that if soil liners are to perform according to design specifications, soil processing prior to construction and rigid construction QA/QC are necessary. The large-scale liner (7.3 c 14.6 x 0.9 m) consisted of six 15-cm compacted lifts. Full-scale equipment was used for compaction, and construction practices were modified on the basis of experience gained from the prototype liner study. The work conducted so far indicates that compacted soil barriers can be constructed to meet the saturated hydraulic conductivity requirements established by the USEPA. Questions regarding methodologies to collect in situ infiltration data have arisen from the research. Differences have been noted in infiltration fluxes, as measured by different types of infiltrometers. Perturbations in measurements of infiltration rates and soil tensions have been correlated with barometric pressure fluctuations and/or temperature changes in the liner.