LONG TERM STABILITY OF TIME DOMAIN REFLECTOMETRY MEASUREMENTS IN A MULTI-YEAR FIELD EXPERIMENT

Time Domain Reflectometry measurements in a field demonstration of landfill covers at Los Alamos, New Mexico, USA were analyzed in an attempt to determine the long-term stability of the TDR system. The demonstration was comprised of four landfill cover designs: Conventional, EPA, Loam Capillary Barrier and Clay Loam Capillary Barrier with each design replicated at slopes of 5%, 10%, 15%, and 25% for a total of 16 plots. A total of 212 locations in the plots were instrumented with 2 rod TDR pairs and each location was interrogated at 7 hour intervals for seven years using an automated and multiplexed measurement system. The TDRs were located in a variety of soil types and at differing depths from the soil surface. Measurements from differing soil types were considered separately and seasonal changes in soil water content due to precipitation were minimized by annual averaging. Statistical and graphical analyses were performed to assess the stability of the measurements over the life of the demonstration.

 

Tracy G. Schofield  
Environmental Science Group  
Los Alamos National Laboratory  
Los Alamos, New Mexico