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Mn M Earthgrains Bakery February 3, 1992 02320 0106 Page 3 Field Area Investigation of the adjacent field area indicates the presence of hydrocarbon concentrations greater than 100 ppm in one sampling location at a depth between 1.5 and 2 feet. TPH concentration in sample 3D was measured at 1,300 ppm. Field observations made at the time of sampling indicate that asphaltic material was present in the samples collected in this location. The asphaltic material may be the source of TPH in the sample, and the hydrocarbons found in this area may be due to the presence of heavier, non-regulated asphaltic material. Three soil samples were collected from the field for analyses of background metals concentrations. No cadmium or lead was detected in any of the samples analyzed for metals. Chromium, nickel, and zinc were detected. A summary of these analytical results is presented on Table 2 (Appendix B). 3.0 DISCUSSION Based on the results of soil sampling conducted during the preliminary assessment, it appears that two types of hydrocarbons are present in the study area. The hydrocarbons associated with the ditch appear to stain the surface and exhibit an oily appearance. Besides the sample collected at the IF location only two other samples (5F and 9F) collected from this ditch at 1.5 to 2.0 feet below grade, contained detectable TPH concentrations of 36 to 12 ppm. These data indicate that the hydrocarbons are relatively immobile. Furthermore, sample 5F was analyzed for TPH and TOG (Table 1, Appendix B), and was found to contain 36 ppm TPH and 20 ppm TOG. The values of each result are not additive because TPH and TOG constituents overlap. These two analytical methods are commonly used to determine the amount of petroleum hydrocarbons (TPH) relative to the total hydrocarbon concentration (TOG). TOG includes vegetable, animal, and petroleum hydrocarbons. Although the values of TPH and TOG are similar, the TPH value exceeds the TOG value and therefore this data is inconclusive. In the field area, personnel noted the presence of asphalt remnants which contribute asphaltene hydrocarbons to the TPH value during analysis. Asphaltene hydrocarbons are generally immobile and have a high boiling point. No remarkable metals concentrations were found. The results of metals analyses have been compared to soluble and total threshold limit concentrations (STLC and TTLC) listed in State of California code of Regulations Title 22. The STLC and TTLC are guidelines used in determining the persistent and bioaccumulative toxic affects of substances. None of the metals analyzed for were present in significant quantities at or near the TTLC. Additionally, no metals species were found at or above 10 times the STLC listed in Title 22 (Table 2, Appendix B). 0106H35.RPT J GROUNDWATER TECHNOLOGY, INC.