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7 <br /> n t L L rf1+0' .�a.� -aar iK r cc <br /> W'315 �;� r'.✓"`' a n+ e.,a „°` r w,r ,.,.yy;. ..t....0 Y.. L4' e <br /> ��.:Gr <br /> i .,,,,;,,S..e �ryT��b`®.,�_.. `.�' ,zL' T y{•'�ri t'r""'i' r,s'Y2 < . _. <br /> wx,4y�:s <br /> n <br /> fr �, <br /> o- <br /> GASCO Gasoline Station February 8, 1991 <br /> Project No. 3-30054-31 Page 2 <br /> SCOPE OF WORK <br /> Exceltech proposes to drill four exploratory borings at the site and convert them to <br /> groundwater monitoring wells. The locations of proposed wells are inthe approximate <br /> corners of the site as shown in Figure 2. <br /> Prior to any drilling, Exceltech will contact Underground :service Alert (USA) so that <br /> the underground utilities on adjacent public right-of-ways can be marked by their <br /> respective companies. A site safety plan relating to the investigation is attached in <br /> Appendix A. <br /> Exploratory Drilling <br /> Exceltech will drill the borings using a truck-mounted drill rig and hollow-stern auger. <br /> The auger and other tools used in the hole will be. steam cleaned before use. Relatively <br /> undistcrbe sail samples will be cellected following Exceltech`s soil sampling protocol <br /> (Appendix H) at 5-feat depth intervals or at any significant change in lithology. A <br /> modified California split-spoon sarapler with internal brass liners will be used to colied <br /> the samples. The boring will be advanced to the deslicd sampling depth and the <br /> sampler will be lowered to the bottom of the hole. It will be driven ahead of the auger <br /> wi'h a 140-pound, rig-operated hammer. The sampler will bremoved from the role <br /> and disassembled into its component parts. The Ioweimost brass liner with sample will <br /> be capped, labeled, logged on a chain-of-custody form, and placed in a chilled ice chest <br /> for transport to a state-certified labor,atoty for analysis. <br /> An Exceltech geologist will prepare a description of the subsurface conditions <br /> encountered during drilling. The ercountered soils will be classified using the Unified <br /> Soil Classification System. The geologist will alio condu.t a field test for hydrocarbon <br /> contaminant vapors from selected soil satrapies using a portable photoionixation <br /> detector. <br /> i , <br /> Drilling cuttings will be placed in Department of Transportation (DOT)-approved 17I4 <br /> ' drums. The drums will be left at the site until laboratory analytical results are known. <br /> At that time, the drums will be properly disposed of by Uarpetrol. <br /> Groundwater (Monitoring Well Construction <br /> Groundwater monitoring wells will be constructed in each of the exploration borings. <br /> All monitoring wells will be built in accordance with permit requirements of San <br /> Joaquin County. The wcl!s will be construetvd of 4-inch-inside-diameter flush-threaded <br /> : polyvinyl chloride (PVC) casing: no glues or solvents will be used. After drilling the <br /> boring to the desired depth, the PVC casing will be installed in the borehole and a filter <br /> pack of clean sand will be placed in the annular space to aVproximateiv 1 to 2 feet above <br />