Mineralogy of the playa clays at the Pantex plant, Amarillo, Texas

The Southem High Plains of Texas contains approximately 20,000 small ephemeral lake basins called playas. Recentiy, these playas have received considerable attention due to the realization that focused recharge to the Ogallala Aquifer can occur through these basins (Wood and Osterkamp, 1984, 1987; Scanlon et al., 1994; Wood et al., 1996).

The Pantex Plant, located 16 miles northeast of Amarillo, Texas, in Carson County, has five playa lakes on property owned or leased by the Department of Energy. Potential contamination of the Ogallala Aquifer from Pantex has created much concern. Measurable contamination has been detected in the soils underlying the Plant (Laun, 1995).

A sufficient knowledge of soil properties in playa basins is necessary to properly characterize the potential of contamination. Playa basins are a major focus of surface mnoff on the Southem High Plains. Playa basins have a distinctive surface soil, termed the Randall soil series (USDA-SCS unpublished material, 1978). Randall soils are defined as fine, montmorillonitic, thermic typic Halplustert. Playa basins collect mn-off from agricultural fields, roads, pavement and other man-made stmctures that can be sources of contamination. Mineralogy influences factors such as recharge and contaminant attenuation through these basins.