SCANLON, BRIDGET R., ROBERT REEDY, and JINHUO LIANG
Bureau of Economic Geology, The University of Texas at Austin, Austin, TX

Abstract: Monitoring Unsaturated Flow Processes Related to the Texas Low-Level Radioactive Waste-Disposal Site

An understanding of unsaturated flow processes is critical to evaluating the performance of a waste-disposal cover system. The purpose of this study was to monitor unsaturated flow in engineered barriers, including a capillary barrier at 2-m depth and an asphalt barrier at 1.3-m depth. The engineered barriers were installed during the summer of 1997 in two plots (15 x 34 m) near Sierra Blanca for the Texas low-level radioactive waste-disposal site. These barriers are being evaluated as covers for waste-disposal cells to minimize downward water movement into the waste. The various components of the water balance are being monitored, including precipitation, surface runoff, water-storage changes, lateral flow on the asphalt layer, and deep drainage. We are monitoring water content by using a neutron probe in vertical and horizontal neutron-probe access tubes and by using time domain reflectometry. We are monitoring water potential by using thermocouple psychrometers in the dry range and heat dissipation sensors in the wet range. Pan lysimeters were installed to monitor drainage at depth. Electromagnetic induction is being evaluated as a noninvasive tool for monitoring water content changes and is calibrated with data from time domain reflectometry and neutron-probe monitoring. Monitoring results from the engineered barriers will be compared with those from the surrounding natural system to evaluate the performance of the cover designs.

AAPG Search and Discovery Article #90928©1999 AAPG Annual Convention, San Antonio, Texas