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♦ (41m) inconsistent with the standard." According to BSK, the peaks on the chromatogram associated with the "lighter end" gasoline constituents (BTEX and other volatile constituents) were higher than usual as compared with the "heavier end" constituents, relative to BSK's gas chromatogram standard. BSK's organic lab supervisor stated that this indicated a more "volatile mix" than usually seen in Method 8015/8020 chromatograms. Table 2 indicates that total lead was detected at concentrations ranging from 5.8 to 12 mg/kg in soil samples from each of the five borings drilled at the site. No lead was detected in the groundwater samples. Lead was used as a gasoline additive for many years in the form of tetraethyl lead. According to the American Society for Testing and Materials (ASTM) Guidance Document for Risk-Based Corrective Action.Applied at Petroleum Release Sites (ASTM E1739-95), tetraethyl lead'decomposes to inorganic lead in dilute aqueous solutions and in contact with other environmental media. It remains as organic lead in free gasoline product, however, no free product was observed at the site. Since lead was detected in numerous soil samples which contained no organic compounds (petroleum hydrocarbons), it is reasoned that the lead is in an inorganic state. US EPA Region IX Preliminary Remediation Goals (May 1998) for inorganic lead in soil are 130 mg/kg for residential soils and 1,000 mg/kg for industrial soils. The lead concentrations found at the site are much lower than these remediation goals. A' Published background data for lead in the western United States has an arithmetic mean of 20 mg/kg with a concentration range from less than 10 to 700 mg/kg (based on "Element Concentrations in Soils and Other SurficW Materials of the Conterminous United States", U.S. Geological Survey Professional Paper 1270, 1984). Since the soil samples were collected in areas peripheral to the former excavation or dispenser area, and since no PHCs were detected in most of these soils, it is reasoned that the lead concentrations detected are background levels for the area. In addition, lead-concentrations in all samples are far below the total threshold limit concentration (TTLC) value of 1,000 mg/kg. . The TTLC value, per Title 22 of the California Code of Regulations (CCR), is the concentration of a solubilized, extractable and nonextractable bioaccumulative or persistent toxic substance which, if equaled or exceeded in a waste, renders the waste hazardous. 5.0 CONCLUSIONS AND RECONEMNDATIONS ON No PHCs were detected in soils near the former tank area, and total lead concentrations found in soils are within the range of background levels for the area and well below.the TTLC values L set by the State and the preliminary remediation goals set by the US EPA. Based on these results, soils in the vicinity of the former tanks do not appear to constitute a threat to human health and safety. However, groundwater is impacted with PHCs along the eastern end of the 7 98117MWRPT WUSTINV.RPr 13kBOYAIIAN & ROSS, INC. Environmental Scientists & Engineers