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1 11 February 2002 AGE-NC Project No 99-0559 ' Page 7 of 10 Hydrological Unit 2 (HU2) extends from 62 to 67 feet bsg, is predominantly fine grained, but is coarse locally, and is characterized by high pore pressure ' Hydrological Unit 3 (HU3)extends from 67 feet to 92 feet bsg,is predominantly coarse grained,but with significant interval of fine grained soil, the volume of fine grained soil increases toward the south The zone Is characterized by very moderate to low pore pressure tHydrological Unit 4 (HU4) extends from 92 feet to 105 feet bsg and consists primarily of coarse grained soil which is gravelly toward the north, toward the south the unit is thinner and contains ' more fine soil HU4 is characterized by very low to low pore pressure Hydrological Unit 5 (HU5) extends from 105 to and possibly beyond 155 feet bsg near the total ' depth penetrated by all three CPT bonngs Silt and clay are the dominant soil type in the interval, although sand occurs locally The various soil types do not appear to have great lateral continuity ' The interval is characterized by pore pressure variations from moderate to high pressures that do not appear to have great lateral continuity Locally, thin intervals of low to moderate pore pressure material occurs 10 Boring logs from the Western Farm Service (UNOCAL) site east of the subject site show the subsurface soil to increase in sand and gravel content and thickness This is probably due to the increasing volume of channel deposits of the nearby Calaveras River 3 3 LABORATORY RESULTS OF "GRAB" GROUND WATER SAMPLES A total of eleven"grab"ground water samples were collected from CPT-1, CPT-2 and CPT-3 and submitted for laboratory analysis for the above mentioned constituents Two grab water samples were collected from HU1 (CPT1-60 and CPT3-60), three grab water samples were collected from HU4(CPT1-100 CPT2-100 and CPT3-100),three grab water samples were collected from the upper ' portion of HU5 (CPT1-130,CPT2-130 and CPT3-130),and three grab water samples were collected from the lower portion of HU5 (CPT1-150, CPT2-150 and CPT3-150) Table 1 shows the sample identification, sampling depth and the associated informal hydrologic unit designation TPH- was not detected in HU1 samples collected from CPT and CPT3 HU1 was not sampled in g P ( p boring CPT2) TPH-g was detected in HU3 samples collected from CPT1 and CPT2 at concentrations of 6,700 µg/1 and 710 µg/l, respectively TPH-g was detected in the upper HU5 sample collected from CPT2 at a concentration of 4,700 pg/l and in the lower HU5 sample at a concentration of 10,000 µg/1 iBTEX compounds were detected in the HU4 sample collected from CPT1 at concentrations of I1,100 µg/1, 89 µg/1,41 Ogg/l and 900µg/1,respectively BTEX compounds were detected in the HU4 Advanced GeoEnvironmental,Inc I