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MEASUREMENTS OF CAPILLARY PRESSURE-SATURATION RELATIONSHIPS AND DNAPL DISTRIBUTION IN SILICA SANDS USING LIGHT TRANSMISSION VISUALIZATION
Citation:
BOB, M., M. BROOKS, T. R. LEE, C. G. ENFIELD, AND A. L. WOOD. MEASUREMENTS OF CAPILLARY PRESSURE-SATURATION RELATIONSHIPS AND DNAPL DISTRIBUTION IN SILICA SANDS USING LIGHT TRANSMISSION VISUALIZATION. Presented at 13th Annual David S. Snipes Clemson Hydrogeology Symposium, Clemson, SC, April 13 - 15, 2005.
Impact/Purpose:
To inform the public.
Description:
This study is a part of an ongoing research project that aims at assessing the environmental benefits of partial DNAPL removal. The laboratory part of the research project is to examine the functional relationship between DNAPL (modeled by PCE) architecture, mass removal and contaminant mass flux in 2-D models under well-defined conditions. For this, the characterization of the DNAPL in the model system is carried out using light transmission visualization (LTV). In this technique, images of the entire 2-D chamber are captured using a charge-couple device (CCD) and analyzed pixel by pixel using image analyses software. Water, air and DNAPL saturation across the 2-D model are measured as variations in the transmitted light intensity of these pixels. In this part of the study, air entry pressure in silica sands is measured as an experimental validation of LTV using 2-D flow chamber constructed of two glass plates separated by 1.4 cm. Naturally translucent silica sand is used as packing media. Variable saturation of water and air across the height of the model in a water-air system is dictated by controlling the capillary pressure of the fluids. Saturation-Capillary Pressure relationships measured using the LTV technique are compared with experimental results obtained by Tempe cell and frozen column measurements. Also, the LTV technique is used to measure air saturation distributions during air sparging experiments. In addition, the distribution of PCE saturation in the 2-D static system is measured by the LTV technique and PCE mass calculated by image analyses is compared to actual PCE added.