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4.0 Conclusions and Recommendations <br /> No detectable concentrations of TPH asasoline were <br /> g identified in any of the groundwater <br /> samples collected during this quarterly sampling event TPH as gasoline has never been <br /> detected during previous sampling events In concordance with the San Joaquin County <br /> Registered Environmental Health Specialist, Ms Mary Meays (County REHS), it is <br /> recommended that the testing of the groundwater for TPH as gasoline be suspended <br /> Sporadic, trace detections of benzene, toluene and xylenes have historically been detected <br /> during previous groundwater monitoring events (Table 2) None of these detections have <br /> been confirmed during subsequent sampling events No detectable concentrations of BTEX <br /> were identified in any of the groundwater samples collected during this quarterly sampling <br /> event In addition, there is no evidence of a relationship between the groundwater elevation, <br /> BTEX detections and time Since detected concentrations are sporadic and well below state <br /> maximum contaminant levels (MCL's), BTEX is not considered to be of concern at the site <br /> In concordance with the County REHS, it is recommended that testing of the groundwater for <br /> BTEX be suspended indefinitely <br /> The <br /> groundwater analytical data during this sampling event indicates that TPH as diesel is <br /> present at very low concentrations in the groundwater at the site The highest detectable <br /> concentration of TPH as diesel (190 gg/L) was measured in MW-3 This is lower than the <br /> highest concentration (210 pg/L) detected during the August 1995 sampling event However, <br /> since groundwater at the site has yielded TPH as diesel in successive quarters in MW-5, it is <br /> recommended that the groundwater sampling and testing continue for TPH as diesel only <br /> The groundwater at the site was determined to flow in a northwesterly direction, with a <br /> gradient between 0 001 ft/ft and 0 025 ft/ft The water level at the site rose by as much as <br /> 2 48 feet since August 1995 The cause of this unseasonal change is uncertain It is <br /> recommended that water level monitoring continue in order to evaluate these variations <br /> r <br /> MZ/0430-96/VDBF/95-0045 If 4-1 <br />