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A 4�( <br /> ;1 I <br /> ,I <br /> i� <br /> 4.0 DRILLING AND SOIL TESTING <br /> . F <br /> Drilling and sampling were performed to dete'r'mine the presence of any <br /> contamination to the surrounding soil should , the tank have leaked. Four <br /> borings were drilled at each corner around the tank periphery. The drilling <br /> was performed after visual inspection of thetank indicated no apparent } <br /> leakage from or damage to the tank., The age of the tank is estimated to be / <br /> about six' years old. Drilling permits were obtained from the San Joaquin <br /> County Health District. Copies are <br /> p provided in :Appendix V. As required by <br /> the permit., a copy of this report is provided to the client for forwarding to <br /> the local Health Authority. <br /> The borings were drilled on a 15° angle fromlvertical to intercept the <br /> backfill of the tank and obtain samples from the area directly beneath the <br /> tank. The sampling scheme is shown in Figure 4. fThe borings were backfilled <br /> with a concrete grout and finished to conform with the surface grade. Boring <br /> logs are presented in Appendix IV. <br /> �R <br /> The samples were sent to the IT Stoner Laboratory, 11Santa Clara, California for <br /> i <br /> analysis. The results indicated high levels of contamination which were <br /> inconsistent with visual observation. The client!, was informed of this fact <br /> and that a laboratory mix-up was suspected. A decision was therefore made to <br /> redrill four more borings in order to obtain new sa^mples. <br /> +i 1 <br /> 3 +i <br /> i� <br /> All samples were taken by using a 2" diameter standard penetrating sampler <br /> with brass liners, driven 18-inches. The sample's were taken at depths of <br /> l I <br /> approximately 10, 15 and 20 feet as shown on thellboring logs. The samples <br /> were packed in ice and shipped to the IT-Stone laboratory, Santa Clara, k <br /> California, under standard chain-of-custody procedures. The samples were <br /> analyzed for totalli <br /> petroleum hydrocarbons by solvent extraction and gas <br /> chromatography. The samples were analyzed for lead by McIntosh Laboratories <br /> and none was detected. The certified analytical results appear in Appendix VI <br /> ;i <br /> and Table I.. <br /> i� <br /> ii <br /> I <br /> 1 <br /> 1F ` <br /> IJ <br /> 4 <br /> ENG:0551/02246 <br />