Drilling and Installation of Deep Groundwater Monitoring Wells: Los Alamos National Laboratory, New Mexico
Major challenges to the characterization approach at LANL are to obtain maximum information during drilling and to meet sample quality requirements while minimizing drilling costs. Current drilling practice makes limited use of fluid additives to supplement air circulation methods to advance through the vadose zone. Starting about 100 feet above the water table, drill casing is advanced to the regional aquifer using only air and municipal water for circulation. The ability to retract casing for video and geophysical logs allows for robust characterization of perched groundwater systems and accurate definition of the top of regional saturation.
Current well design emphasizes a minimal annulus, maximum screen slot size, and thorough well development to mitigate formation damage due to drilling. Careful subsurface characterization at depths ranging up to 1,400 feet bgs, while retaining the ability to collect representative groundwater samples, may have application at a number of sites throughout the environmental industry. Optimizing each well to meet program objectives while reducing total project costs benefits all environmental investigations. (LA-UR-17-23451)