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• i <br /> Jim Pinasco <br /> January 4, 1995 <br /> Page 5 <br /> 5. Revisions to Ground Water Sampling Log <br /> The ground water sampling log does not include spaces for <br /> recording dissolved oxygen (DO) or Eh readings during purging. <br /> In addition, the log does not include calculation or recording of <br /> ground water volumes to be purged from tubing and pump for <br /> low-volume purge method. <br /> Recommendations <br /> The ground water sampling log should be revised to include <br /> DO and Eh readings as well as volumes to be purged for low-volume <br /> purging (tubing volume and pump volume) . <br /> 6. Limited Number of Wells in Study with High Contaminant <br /> Concentrations (Greater than 100 microgram/liter [µg/1] ) <br /> Table 3-3 indicates of the 30 wells in the study there are <br /> only two wells with contaminant concentrations exceeding <br /> 100 µg/1. Comparison data of low volume purging versus standard <br /> purging for high contaminant concentrations is very limited. <br /> Results from a Castle Air Force Base study conducted in 1994 <br /> indicated the greatest disparities between the two methods <br /> occurred in samples collected from wells with high contaminant <br /> concentrations; however, the number of data points in the Castle <br /> Air Force Base study with high contaminant concentrations were <br /> very limited. <br /> Recommendations <br /> It is recommended that more than two wells with contaminant <br /> concentrations exceeding 100 µg/1 be included in the low-flow <br /> rate sampling study. Two sampling points is too limited to <br /> compare results from the two different purging methods. This <br /> comparison may be critical information for evaluating if <br /> low-volume purging is appropriate for monitoring in areas with <br /> high contaminant concentrations. <br /> MS.mk <br /> MS4.015/5 <br />