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-, 10, CJeafngicaf?echnics Inc. Page 5 Soil Groundwater Investigation Report Moresco Project No.251.3 i„ .Tune 7, 1999 3.1 Analytical Results 3.1.1 Soil Sample Analysis The following is a summary of the soil analytical results. The data is included in Table 1 of Appendix A and the laboratory data sheets are included in Appendix C. 1. MW-1 • The 15.5 foot sample showed the presence of very low levels of MTBE (11 ug/Kg). • The 60.5 foot sample showed the presence of low levels of MTBE and TBA (110 ug/Kg and 15 ug/Kg, respectively). • The 25.5, 45.5, 75.5, 90.5 and 110.5 foot samples were non-detect for all analytes. �• 3.1.2 Groundwater Sample Analysis After development of the monitoring well on April 5, 1999, a groundwater monitoring was conducted on April 8, 1999 and May 19, 1999. The water samples were submitted to Kiff Analytical LLC for analysis for BTEX, the gasoline fuel oxygenate compounds (MTBE, DIPE, ETRE, TAME, and TBA) and TPH-G. The results of the groundwater analysis are included in as Table 2 in Appendix A. The analytical data reports are included in Appendix C. The groundwater sample from MW-1 did not show the presence of any of the compounds tested for. LW 3.2 Site Hydrology On April 8, 1999, the depth to water was 89.70 feet bgs. On May 19, 1999, the depth to `r water was 93.72 feet bgs. The groundwater appears to show a rapid decrease in elevation at the site. This is possibly due to groundwater pumping for irrigation purposes of the surrounding farms. It is not possible to calculate a site specific groundwater gradient as there is only one monitoring well at the site. 3.3 Geology and Field Observations The following section discusses the subjective field observations and geology documented during this investigation based on the interpretations of the field geologist. The site's geology is typical for shallow valley sediments consisting of sand with varying .� amounts of silt and clay. The following specific observation were made: • At least four distinct sediment types have identified between the surface and 100 ft: - clean sand - sand with fines clayey silt/silty clay - sandy gravel • A thin gravel layer was encountered between 60 and 65 feet bgs. • From 90 feet to 110 feet in MW-1 the soil was very fine-grained materials, silts, clays and silty sands. i.• Field observations indicate that the soils below the tank pit have been effectively remediated by the vapor extraction system. Only the 10 and 15 foot samples showed field evidence (i.e., L