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L <br /> to 3 feet"of which appear to be attributable to the heavy and prolonged El Nino rainfall events <br /> sof last winter. The static water level at the sitCas measured in the three borings ranged from <br /> ,17 to 7.5 feet bgs on August 6, 1998. 'Based on nearby studies,(SPGC, 1998;and EMCON, <br /> J998) groundwater flow directions in the vicinity appear to be variable, ranging from west <br /> hnorthwest to east southeast. .Flow direction changes may be due to tidal influences produced <br /> Jby the deep water channel to the north and the San Joaquin Riverto the west and southwest <br /> !;of the Port area. <br /> 4.2 SOIL AND GROUNDWATER VANALYTICAL RESULTS . k: <br /> E iI <br /> IiAnalyticai results for soil and groundwater samples collected during this investigation are <br /> 4 �presented on Table 2.' The laboratory data sheets and chain-of-custody records are included <br /> Ejin Appendix B. No PHCs were detected in soil samples collected in the three borings, or <br /> �igroundwater samples collected from borings B1-1 and 131-3. ' Groundwater sample W-012, <br /> (`collected at 12 feet bgs in boring B1-2, contained MTBE at a concentration of 95:µg/? using <br /> !;Method 801518020. This result was confirmed by Method 8260,-where MTBE was detected <br /> t iat a concentration of 120 µg/f. No other oxygenates were detected in this sample (Table 2). <br /> �jTable 2 indicates that total lead was•detected at concentrations ranging from 6.6 to 141 mg/kg <br /> !in soil samples from each of the three borings. No lead was detected in the groundwater <br /> 'samples. Lead was used as a gasoline additive for many years in'the form of,tetraethyl lead. <br /> According to the American Society for Testing and Materials (ASTM) Guidance Document for <br /> Risk-Based Corrective Action Applied at Petroleum Release Sites (ASTM E1739-95), tetraethyl <br /> 4ead decomposes to inorganic lead in dilute aqueous solutions :land in contact,'with ,other <br /> `!environmental media. :It remains as organic lead,in free gasoline,product, however, no 'free <br /> ;product was observed at the site.:!:.Since no organic compounds (petroleum hydrocarbons) were <br /> `detected in soils at the location&:where lead concentrations were detected, it is""reasoned that <br /> !the lead is in an inorganic state., US EPA Region IX Preliminary.Remediation Goals (May <br /> i14998) for inorganic lead in soil are' 130 mg/kg °for residential soils and 1,000 mg/kg for: <br /> `industrial soils. The lead concentrations found at-the site are much lower. than these <br /> ',',remediation goals. ,. <br /> ,In addition, published background data for lead`in the western United States has an arithmetic <br /> Ellmean of 20 mg/kg with a concentration range from less than 10 to 700 mg/kg (based on <br /> '!;"Element Concentrations in Soils and Other Surficial Materials of the Conterminous-United <br /> States", U.S. Geological Survey Professional Paper 1270, 1984). Since the soil samples were <br /> icollected'in an area peripheral to the former excavation and no PHCs.were detected in these <br /> 'soils, it is reasoned that the lead' concentrations detected are background levels for the area. <br /> �Further, lead concentration in all samples are far below total threshold limit concentration <br /> 981171INVRPMs1USTINVAPT <br /> 11 <br /> BOYARAN & ROSS; INC. <br /> Li Environmental Scientists &.Engineers <br /> ki <br />