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.� `r ..! R&B Trucking Preliminary Site Assessment Page: 3 3.0 INITIAL EVALUATION This section describes the hydrocarbon release from the tanks,as observed during the excavation, and analytical results of soil samples. The potential migratory pathways of contaminants and potential impact on humans and the environment are considered. 3.1 Type and Volume of Waste Present Laboratory analysis of 14 soil samples from the tank sites indicate a fairly high concentration of diesel fuel below tank#5: 3,417 mg/kg under the north end and 4,385 mg/kg under the south end. A moderate level of diesel,320 mg/kg,was present under the west end of tank#1;and a very low level,21 mg/kg,under the south end of tank#2. ._ All other soil samples were non-detected for diesel at 10 mg/kg detection level. The soil samples were also analyzed for the diesel components,benzene,toluene,xylenes, and ethyl benzene(BTX&E). At detection limits at 0.03 gg/kg,most samples were non- detected. Samples from below tanks#3&4 and under the north end of tank#5 had very low levels of BTX(as much as 0.15 gg/kg)but no ethylbenzene. Some additional samples had still lower levels, many of which are only slightly above the detection limits. These samples came from under tanks adjacent to tanks#3 and 5. Table 1 and Figure 3 give further details of the analytical results and the position of the tanks and samples. 3.2 Potential Migratory Pathways The bottom of the tank excavation, 11 to 14 feet below surface,was completed into the vadose zone. The ground water table is,however,quite shallow at the site and would be close to the level at which the samples were collected. Downward migration of hydrocarbons may therefore have reached the ground water. To assess if this has happened,and to what degree, the installation and testing of a monitoring well is proposed. The results of this testing will indicate if additional wells will be necessary. Lateral migration above the ground water table is judged to be limited but needs to be assessed. 3.3 Primary Public Health and Environmental Impacts Diesel fuel is only slightly toxic to humans in skin contact. Ingestion would pose a greater toxicity risk. Ingestion could be by drinking water containing the released product or eating soil. This is not regarded likely with typical adults,but unsupervised children could do this. However,the amounts would be small and of short duration, and health risks will be small.