Comparison of Stainless Steel vs. PTFE Miniwells for Monitoring Halogenated Organic Solute Transport |
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| Authors: | Gino C Bianchi-Mosquera Douglas M Mackay |
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| Institution: | Gino Bianchi-Mosquera (51 Claremont Ave., Long Beach, CA 90803) is a project geochemist with Watkins-Johnson Environmental Inc. He received a B.A. degree in geochemistry from Occidental College, Los Angeles, California, an M.S. degree in geochemistry from The Pennsylvania State University, and a D.Env. degree from the University of California, Los Angeles, in 1982, 1986, and 1992, respectively. His research interests include the transport and fate of organic compounds in the subsurface, and in the evaluation of new aquifer cleanup techniques.;Douglas Mackay is adjunct professor in the Centre for Groundwater Research at the University of Waterloo (Waterloo, Ontario N2L3G1), Canada, and a visiting scientist at the UCLA Department of Civil Engineering. From 1986 to mid-1990, he was a faculty member in the Environmental Science and Engineering Program of the UCLA School of Public Health. His research focuses on field studies of transport and fate of organic chemicals in ground water and ground water decontamination technologies. Dr. Mackay received a B.S. in engineering and M.S. and Ph.D. degrees in civil engineering from Stanford University in 1970, 1973, and 1981, respectively. |
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| Abstract: | Field tests of organic solute transport behavior have often been monitored using small-diameter wells (miniwells). To determine if experimental results could be significantly biased by sorption to, desorption from, or diffusion through sampling lines, dissolved concentrations of tetrachloroethene and carbon tetrachloride were measured in ground water samples collected simultaneously from the same spatial location during a forced-gradient test in the Borden aquifer using polytetrafluoroethene (PTFE) and stainless steel miniwells (1/8-inch O.D.).
A semiautomated organic analytical system was used on-site to obtain real-time results, which avoided sample holding problems and permitted optimizing sampling times. The breakthrough curves (plots of concentration vs. time) for both organic compounds indicate that under the conditions of this experiment (low organic solute concentrations, short exposure time of sampling lines to the plume, adequate flushing of sampling lines) there is no significant difference between concentration histories (breakthrough curves) collected using a polytetrafluoroethene sampling line and those collected using a stainless steel sampling line. This suggests that organic solute tailing seen in this and also in a similar transport experiment previously conducted at the site is the result of transport processes in the aquifer rather than an artifact introduced by the PTFE miniwells. |
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