Field Deployment of Novel Approach in Acquiring Deep Groundwater Samples at Sandia National Laboratories; Nevada Test Site; and Nye County, Nevada

Groundwater sampling is routinely conducted at hundreds of wells at numerous U.S. Department of Energy facilities to monitor changes in the groundwater that occur over time. Some of these wells are very deep (greater than 600 meters), consequently presenting unique problems that must be overcome in order to obtain representative, undisturbed samples. Samples are being collected at these facilities using current technology, including submersible pumps, discrete bailers, and various manufactured systems. Each system or method has particular advantages and special uses. One of the greatest limitations to routine groundwater sampling is the cost associated with acquiring samples. Thus, innovations that allow purging and collection of groundwater at minimal expense are highly desirable. A novel solution for economically collecting groundwater samples is presented. In this approach, a pneumatic sampler employs compressed air to force a polyurethane pig up and down a borehole. This sampler employs two moving parts and is completely automated. Purge rates between 3-4 liters per minute have been demonstrated thus far, and greater purge rates are possible. Successive prototypes of the sampler have been deployed in wells at Sandia National Laboratories; Nevada Test Site; and Nye County, Nevada, adjacent to Yucca Mountain. A functionality test was conducted during the Sandia deployment. The initial prototype of the sampler was improved during deployment to the Nevada Test Site where rudimentary comparisons were made between tritium samples collected by the pneumatic sampler and samples collected through pumping and bailing operations. In the Nye County deployment, various types of groundwater samples were collected and compared to those collected using established groundwater sampling techniques. In addition, durability of the sampler will be assessed over long periods during the Nye County deployment.