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1 <br /> February 2002 Quarterly Ground Water Monitoring <br /> 1645 Cherokee Lane,Stockton,CA <br />' Hydro-Environmental Technologies,Inc <br />' 30 CONCLUSIONS AND RECOMMENDATIONS <br /> 3.1 Conclusions <br />' For the last three sampling events, MW-2 through MW-4 were dry During this sampling event, there <br /> was insufficient water in MW-1 for samples to be collected for analysis However, although there was <br />' insufficient ground water in MW-1, the detection of ground water indicates that recharge of the shallow <br /> confined ground water system is now occurring In June 2000, HETI had installed six DP bonngs <br /> throughout the subject property The DP boring investigation determined that ground water occurred <br />' from approximately 40 feet to 50 feet bsg and that a clay aquitard occurred at approximately 50 feet bsg <br /> During that investigation grab ground water samples were obtained from each boring No detectable <br /> concentrations of TPH as gasoline, TPH as diesel, BTEX, or the five fuel oxygenates were found in the <br />' 46 soil samples and six grab ground water samples submitted for analysis <br /> In August 2000, HETI installed three shallow ground water monitoring wells in the same vicinity as the <br />' DP borings Monitoring wells were installed to approximately 50 feet bsg, they were grounded in a clay <br /> aquitard in accordance with CCR Title 23 procedures, and guidelines from the PHDIEHD Variable <br /> ground water flow directions and the published County ground water map indicated that the subject <br /> property was on the crest of a local ground water divide Unlike chlorinated volatile organic compounds, <br /> dissolved light hydrocarbon fuels do not penetrate clay layers Therefore, this aquitard is currently <br /> effectively retarding the downward movement of TPH as diesel with infiltrating ground water Only <br />' small quantities of dissolved TPH as diesel (ranging to 100 ppb) have been detected Penetration of the <br /> clay aquitard would certainly result in the downward movement of diesel into lower, possible confined <br /> aquifers <br /> 1 <br /> 3.2 Recommendations <br /> ' Because of the slow infiltration of recent precipitation, HETI recommends one additional quarterly <br /> sampling round in May 2002 <br /> Limitations to this report are in Appendix B <br /> 6 <br /> 1 <br />