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a _ _ <br /> r � - <br /> November 1990 <br /> M88168D <br /> Appendix C. The locations of the drill holes/monitoring well are illustrated on <br /> Plate 1 - Site Plan. <br /> The site specific technical work plan, which was approved by SJLHD, <br /> ` planned for the advancement of three drill holes to depths ranging between 60 to <br /> s <br /> 80 feet bgs (dependent on water table elevation), which were to be completed as <br /> 4-inch PVC ground water monitoring wells. Drill hole MW-1 was the first drill <br /> hole advanced and was completed as a ground water monitoring well with a total <br /> depth of 80 feet bgs. Upon discovering that MW-I had been set as a dry well, SGD <br /> decided to advance drill hole DH-2 to the maximum depth allowed by the mechanical <br /> capabilities of the drill rig. DH-2 was advanced to a depth of 90 feet bgs <br /> (maximum drilling depth th abilit <br /> F capability),y), however ground water was not encountered. <br /> Upon driving the split-spoon sampler beyond the tip of the hollow stem auger M1 <br /> subsurface water was encountered, however it is not known if this exists within <br /> the water table. <br /> Because continuous field screening of soil cuttings with a PID from / w <br /> grade to total depth did not indicate the presence of trace concentrations of <br /> hydrocarbon contamination, and because ground water was not encountered within <br /> the drilling depth capabilities of the drill rig employed (Mobil Drill Rig Model ' <br /> B-61), SGD.concluded that adequate ground water monitoring wells could not be b <br /> constructed nor are they necessary according to the LUFT Field Manual. Because <br /> of these circumstances, SGD decided to deviate from the approved technical work <br /> plan and advance two additional drill holes <br /> west and east of the former UST <br /> excavation <br /> . (DH-3 and DH-4, respectively). <br /> Soil Sampling, During the advancement of the soil borings described j <br /> �i <br /> above, undisturbed and disturbed soil.samples were collectedat 5-foot intervals, ' <br /> as per CCR, Title 23, Section 2654, Subsection C. The sample collection protocol ' <br /> is described i7 Appendix C. Soil samples were selected for laboratory analysis ' <br /> 1 t based on PID monitoring of soils duri.n drillin and proximity to f:. <br /> g g, p y ground water. yr <br /> f Soil samples collected at 63 and 80 feet bgs from drill hole NW-1, 15 and 90 feet <br /> j <br /> zz ' bgs from DH-2, and 15 and 90 feet bgs from both DH-3 and DH-4 were analyzed for � I <br /> i TPH and BTEX_by_a_-State of--California—Department-of Health -Services <br /> ,T <br /> fk certified laboratory. is. <br /> 1 <br /> qy s <br /> 7 <br /> 3 <br />