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29 April 2002 <br /> AGE-NC Project No. 99-0628 <br /> Page 4 of 4 <br /> casings. Ground water elevations at the site ranged between 27.85 feet and 27.87 feet below <br /> MSL. Ground water was inferred to have been flowing toward the southwest under an <br /> average gradient of 0.0003 foot/foot. <br /> • Cadmium, copper, mercury, chromium, zinc, silver and lead were not detected at or above <br /> laboratory reporting limits in any of the ground water samples collected and analyzed. <br /> • TPH-mo,TPH-d, and BTEX compounds were not detected at or above laboratory reporting <br /> -- limits in any of the ground water samples collected and analyzed. <br /> • Semi-volatile organic compounds were not detected at or above Iaboratory reporting limits <br /> in any of the ground water samples collected and analyzed. <br /> • Ground water samples collected from the site contained 0.094 to 0.15 m1g/1 MBAS. <br /> • All three ground water samples collected from the site contained detectable concentrations <br /> of nickel and arsenic. The detected concentration of nickel in sample MW-1 (0.14 mg/l) <br /> exceeded the California State Maximum Contaminant Level (MCL) of 0.1 mg/l. The <br /> detected concentrations of arsenic,at a maximum concentration of 0.0036 mg/l(MW-1)were <br /> below the MCL (0.05 mg/1), but exceeded the Primary Remediation Goal (PRG) of <br /> 0.000045 mg/l. <br /> • The pH of the water samples collected ranged from 6.90 to 7.30;the pH values were always <br /> highest in MW-1, lowest in MW-3. <br /> 5.0. RECOMMENDATIONS <br /> Due to the return of lower concentrations of MBAS in ground water samples this quarter, AGE <br /> recommends that the site should be closed as per the recommendation of the EHD. <br /> 6.0. LIMITATIONS <br /> Our professional services were performed using that degree of care and skill ordinarily exercised by <br /> environmental consultants practicing in this or similar localities. The findings were based mainly <br /> upon analytical results provided by an independent laboratory. Evaluations of the hydrogeologic <br /> conditions at the site for the purpose of this investigation are made from a limited number of <br /> available data points (i.e. monitoring well ground water samples), and subsurface conditions may <br /> vary away from these data points. No other warranty, expressed or implied, is made as to the <br /> professional interpretations, opinions and recommendations contained in this report. <br /> Advanced GcuFnvironmcntal,Inc <br />