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Frederick D Day-Lewis

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Tracking changes in bulk electrical conductivity (EC) during tracer tests in saturated sediments allows for direct observation of both mobile and less-mobile pore space exchange dynamics. Electrode arrays made up of four stainless steel rods (insulated with the exception of exposed 0.5 cm tips) were installed vertically at depths of interest and apparent electrical resistivity data (the inverse of bulk EC) were collected using a Wenner configuration with an AGI SuperSting R8 meter. The Bulk EC data are described and listed within the files below. Controlled, downward flow experiments were conducted in Dual-domain porosity apparatus (DDPA). Downward flow rates ranged from 1.2 to 1.4 m/d in DDPA1 and at 1 m/d, 3 m/d,...
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This dataset includes example data used for demonstration of the moisturEC program. This includes inverted electrical resistivity data, model resolution from the inversion, point moisture information, and conductivity-saturation calibration information. The data are from a field site in Coventry, CT outfitted with five, Decagon 5TE moisture probes, arranged along a 28 m transect at different depths. The data represent a slice in time after irrigating the soil for 12 hours.
Borehole geophysical logs were collected to characterize bedrock aquifers at three contamination sites located in California, Wisconsin, and New Jersey. The data were collected by the U.S. Geological Survey (USGS) and the University of Guelph from 2014 to 2015 as part of the U.S. Department of Defense Strategic Environmental Research and Development Program (SERDP) and Environmental Security Technology Certification Program (ESTCP) initiatives to apply geophysical methods at fractured-rock sites contaminated with chlorinated solvents. Logs were collected in open boreholes completed in fractured rock. Each borehole was logged with natural gamma, electromagnetic induction, normal resistivity, single-point resistance,...
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Electrical geophysical data collected in the shallow sediments of Snake Pond, Cape Cod, USA
Quantification of mobile/less-mobile porosity dynamics at the sediment/water interface is critical to predicting contaminant storage, release, and transformation processes. Zones in groundwater flow-through lakes where lake water recharges the aquifer can strongly control aquifer water quality. Less-mobile porosity has previously been characterized in aquifers using flow path scale (10's of m+) tracer injections which are analyzed using numerical models. Methodology was recently developed to couple geoelectric measurements (bulk electrical conductivity, EC), which are directly sensitive to less-mobile ionic tracer exchange processes, with pumped fluid EC tracer data over time. If the fluid EC concentration history...
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When water is pumped slowly from saturated sediment-water inteface sediments, the more highly connected, mobile porosity domain is prefferentially sampled, compared to less-mobile pore spaces. Changes in fluid electrical conductivity (EC) during controlled downward ionic tracer injections into interface sediments can be assumed to represent mobile porosity dynamics, which are therefore distinguished from less-mobile porosity dynamics that is measured using bulk EC geoelectrical methods. Fluid EC samples were drawn at flow rates similar to tracer injection rates to prevent inducing preferential flow. The data were collected using a stainless steel tube with slits cut into the bottom (USGS MINIPOINT style) connected...
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