NEW CORING AND MULTILEVEL SAMPLING TECHNOLOGY FOR BEDROCK STREAM AND PHREATIC CAVE RESEARCH

The number of studies focused on hyporheic exchange and related groundwater-surface water interactions has grown exponentially in the last 20 years (Wondzell, 2015). Though numerous studies have been published on hyporheic exchange in the sediments of rivers and streams, bedrock streams and phreatic caves have received little attention (Wilson and Henry, 2014). Key aspects of field efforts aimed at identifying hyporheic exchange in these environments include core recovery and analysis, and tracer experiments. We present new coring technology using a submersible (to 50m) electric drill and a mechanical drill guide that greatly enhances core recovery, allowing intact cores to be collected through either vertical or horizontal drilling while wading at the surface or by submerged divers. The drill guide maximizes a plum hole and ensures that a steady pushing force is provided to the drill. Second we present an improved mechanical packer design for multilevel sampling of rock that allows passive or active sampling (or tracer injection) of discrete intervals within the rock matrix. When installed properly the packers create effective seals with core-hole walls, isolating multiple sampling/injection intervals from one another. This helps to better constrain specific hyporheic exchange pathways within the rock matrix. Multilevel samplers can be scaled to different size drill or core holes, from less than 1 inch to more than 3 inches in diameter, making them a versatile tool that can be used for many different applications.