Effects of Access Tube Material and Grout on Neutron Probe Measurements in the Vadose Zone |
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| Authors: | B R Keller L G Everett R J Marks |
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| Institution: | Dr. Barry Keller is a hydrogeophysicist wtih Metcalf &Eddy in Santa Barbara, California. He received his B.S from Caltech, M S. from the University of Washington,and Ph.D. from the University of California, Santa Barbara. Dr. Keller is interested in issues of toxic substances and water resource planning, particularly the hydrogeology of aquifers affected by active faulting.;Dr. Lorne G. Everett is a vice president with Metcalf &Eddy in Santa Barbara, California. He is a Registered Professional Hydrologist and Hydrogeologist. Dr. Everett received his Ph.D. from the University of Arizona in Tucson. He is the author of several books including Groundwater Monitoring and Vadose Zone Monitoring for Hazardous Waste Sites. As chairman of ASTM's Section on Vadose Zone Monitoring, he is responsible for developing national vadose zone monitoring standards, He has authored more than 100 professional papers on ground water monitoring and has received the LU Distinguished Alumnus A ward for Excellence in Hydrogeology.;Robert J. Marks is manager of the Santa Barbara office of Metcay &Eddy. He received a B.S. in geology from the State University of New York at Cortland and is a Certified Geologist through the AIPG. |
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| Abstract: | A test-stand experiment was conducted on neutron probe measurements using steel and Schedule 40 PVC access tubes to determine the effect of backfill grout in boreholes. The experiment used a moveable simulated vadose zone. Access tubes and grout do have masking effects on vadose zone measurements, but vadose zone moisture was detected through all configurations tested. Steel tubing has a smaller masking effect than PVC tubing. The masking effect of grout increased with borehole diameter. Although this experiment produced numerical results, conclusions drawn are qualitative in nature, rather than a quantitative calibration of the technique. |
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