ARCHIVED REPORTS_ROY'S AUTO - HISTORICAL (2)

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the total lead concentrations exceeds the US EPA Preliminary Remedial Goal (PRG) concentration of 400 ppm. Total lead in two samples only exceeds the Cal EPA Modified PRG of 130 ppm. The sample with the highest petroleum hydrocarbon concentration did not fail the bioassay toxicity test, and consequently, is not characteristic of a hazardous waste. By Knowledge of Characteristics, none of the- other samples with detectable concentrations of petroleum hydrocarbons exceed the toxicity criterion characteristic of hazardous waste. Results of the initial sampling by Ground Zero indicated concentrations of soluble lead in the northeastern portion of the property at a depth of 1 foot (A, AA, B, BB and C) that exceeded the 5 ppm Title 22 STLC lead concentration characteristic of hazardous waste. However, the low total lead levels present at depths of 5 feet at these locations indicates that the lead is immobile and relatively insoluble under site conditions. The supplemental sampling results indicate that soil containing soluble lead in excess of the STLC limit of 5 ppm is not laterally extensive and is confined to the far northeastern boundary of the property and a small area just off the southeast corner of the shop building. Samples collected in the driveway east of the building and north of the building did not contain lead in excess of the STLC limit. The samples collected from depth of 3 feet at locations BSS and BSB did not contain detectable soluble lead, however soluble lead was minimal at a depth of 1 foot at these locations. This result suggests that shallow soil contamination within the areas of impact is erratically distributed and laterally discontinuous. TCLP and deionized water STLC analysis of the sample collected at 1 foot from location BSS indicates that the lead in that soil sample would not be expected to be significantly soluble or leachable under environmental conditions. The highest contamination concentrations are present in samples collected at a depth of 1 foot from locations A, AA, B, BB, C, and, CC. Soil samples collected adjacent to those soil samples (BSS, BSB, and SS-6) at depths of approximately 1 foot did not contain similar levels of contamination. The apparent lead contamination at the site is limited in areal and vertical extent in the northeastern portion of the property. As depicted on Figure 2, it is estimated that approximately 1,250 square feet are affected to a depth probably not more than 1.5 feet. Cal EPA uses the statistical method described in US EPA document SW-846 to determine the average concentration (u) of contaminants in a waste for classification purposes. The statistic consists of the 80% confidence interval calculated by the two-tailed Student's T distribution at n-1 degrees of freedom. rays\r%X"U\w -Y 7