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MOHR-FRY Ranches 950 Industrial Drive, Stockton, California June 2, 1993 Phase II Remedial Report Page. 7 1 sampling. These procedures were followed between each well, sampling point, ' and at the end of the sampling day. De-ionized or organic-free water (also provided by the laboratory) was introduced into the bailer as a final stage of cleaning. This water was then gently poured into sample vials to be used as bailer blanks. These blanks were not tested because their corresponding samples did not contain contaminants. ' Immediately prior to sampling, water levels and well depth measurements were taken in all wells at the site Each was evacuated using a stainless steel bladder ' pump, which does not introduce air into the water column. The pH, temperature, and electrical conductivity of the water were monitored as the well was evacuated. These parameters are noted on a field log (Appendix D). ' Instruments calibrated to known standards were used to monitor these parameters. At least 5 well volumes were evacuated from each well, and more, if necessary, until the above parameters were stabilized. The samples were ' carefully poured from a Teflon bailer into clean glass vials with Teflon-lined screw caps and half gallon plastic containers provided by the laboratory Care was taken to ensure that no air space existed in the vials by inverting to check for bubbles and re-sampling if necessary. The samples were analyzed or extracted within 14 days according to their EPA methods. Water samples ' collected for analysis were analyzed by EPA method 602 for BTX&B compounds, and method 3510 for diesel range hydrocarbons. All analyses were conducted by Geo-Monitor, Inc , a state certified laboratory. 4.0 Soil Conditions The sub-surface geology of the Mohr-Fry Ranches site is characterized by inorganic silty clays of low to medium plasticity, and three interbedded silty, clayey, fine-grained micaceous quartz sands with than occasional pea-gravel layers as determined from boring logs (Appendix Q. The two upper clays average 15 feet thick; the lower clay between 4.5 - 7.5 feet thick. The three sands are between 4.0 - 8.0 feet thick and were penetrated by all three monitoring wells as well as borings B3 and B5. Previous borings B1 and B2 were found to have depth and hthologic errors and were revised (Appendix Q. Cross sections constructed from the Boring Log data (Figures 3, 4 and 5) show a relative consistency of lithology and bed thickness within the study area. 5.0 Ground Water Conditions The ground water gradient (determined by monitoring wells MW-1, MW-2 and MW-3) on 3130193 was to the east-southeast at 0.003 feet/foot. Figure 2 shows the locations of I