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w� <br /> 1 <br /> 4 <br /> Quik Stop Market No. 132 September 19, 1990 <br /> Project No. 349132-31 Page 4 <br /> f� <br /> t <br /> SUBSURFACE CONDITIONS <br /> - Soils <br /> r" Exceltech explored the subsurface ranging from 16 foot to 31.5 foot depth at the borimy <br /> ' locations. The upper six to ten feet consisted of dense to medium dense clayey sand. <br /> Underlying this was a sandy to silty clay of medium plasticity. A well graded sand without <br /> " t Y binder was also found at this depth in borings B-3,B-4,B-5,MW-1,and MW-3. <br /> Hydrogeolosy <br /> Groundwater was first encountered during drilling at depths ranging from 16.5 feet to 19 . <br /> feet. Static water levels later stabilized at approximately 15 feet as measured in th <br /> monitoring wells on September 14, 1990. Exceltech was not able to prepare a groundwatEr <br /> S surface contour map as a survey has not been completed. <br /> LAW)RATORY ANALYSES <br /> - Anametrix,Inc.of San Jose, California,a state-ceritified laboratory,analyzed the sd <br /> groundwater samples.for.the presence of total petroleum hydrocarbons asgas e <br /> (TPHG),.benzene, toluene, ethyl'benzene, and total xylenes (BTEX). Soil was also <br /> analyzed for total lead. <br /> SUMMARY OF LABORATORY RESULTS <br /> r <br /> The results of soil and groundwater analyses are summarized in Tables 1 and 2, <br /> respectively. The analytical reports from the state-certified laboratory are attached in <br /> Appendix D. <br /> Laboratory analysis of soil samples revealed hydrocarbon concentrations in borings B-1, <br /> B-2, B-3, B-5, MW-1, and MW-2. TPHG was found in B-5 at I I feet at 1.3 parts per <br /> million(ppm), it was also present yn B-3 in concentrations of 0.81 ppm and 460 ppm at 11 <br /> and 15 foot depth,respectively. BTEX was found in soil between 0.005 ppm and 28 ppm j <br /> z; concentrations(see Table 1). Total lead was found in boring B-2 at 3.7 ppm and boring <br /> a MW-1 at 4.4 ppm,both at 16 foot depth. <br /> Groundwater analyses revealed hydrocarbon concentration in monitoring wells MW-1 and <br /> L MW-2. Monitoring well MW-1 was sampled twice, once when it was first installed, <br /> August 24, 1990, and -gain with the later wells on September 14, 1990 (see Table 2). <br /> Both sampling events for MW-1 revealed elevated concentrations of TPHG/BTEX in the <br /> a groundwater. The highest concentrations were 470 ppb(parts per billion)TPHG, 34 ppb <br /> benzene,.37 ppb toluene, 6.2 ppb ethyl benzene, and 55 ppb total xylenes. Monitoring <br /> a <br /> < r, <br />