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' Report-Soil and Groundwater Investigation Herman&Helen's Marina September 30, 1996 ' Page-S- TABLE 3 Geotechnical Testing (Soil - August 1996) ' Specific Organic Permeability Moisture% Porosity % Dry Density pcf Gravity Carbon cm/sec (initial) (initial) (initial) ' Content % ASTM Method D-854 D-2974 D-5084 D-5084 D-5084 D-5084 Sample I.D. ' 1432-GPI-8 2.59 2.5 4x10" 44.3 59.32 65.7 1432-GP3-10 2.64 12.4 2x10 53.6 60.72 64.7 ' 4.0 CONCLUSIONS Based on the data presented above, the limits of gasoline and diesel contamination in the soil ' and groundwater appear to be sufficiently established to the north and south of the former location of the USTs. TPH-G, BTEX, and MTBE were detected at elevated concentrations at GP-4, indicating ' that the northeastern and eastern limit of the plume have not been established. The eastern edge of the property is bordered by an irrigation ditch and agricultural crop land. The previous investigation t conducted in August, 1995, indicates that the western edge of the plume is at or near the shoreline of the adjacent river. The TEPH (motor oil range) concentrations detected in the soil at GP-2, GP-3, ' and GP-4 are likely to be associated with the natural organic content of the soil (i.e., peat). This interpretation is made due to the lack of a motor oil pattern on the TEPH chromatogram and the negative TEPH results for the groundwater analyses. According to Gregory Merciadis of ' GeoAnalytical Laboratories, false positives are considered to be common regarding the TEPH analysis of organic rich soils due to interference from plant or animal fats. An estimate of the extent ' of soil and groundwater contamination is shown in Figure 3, Appendix A. ' The geotechnical testing indicated that the soils have a relatively low average permeability (3x10) which is characteristic of silty clay. For comparison, class II landfill liners are required by ' State law to have a permeability not more than 1x1 O-6 cm/sec, which is of the same order of magnitude. The organic carbon content ranged from 2.5% to 12.4%. The average dry density ' (65.2 pcf) is appropriately low considering the high peat content of the soil. The average porosity (60.02%) is indicative of organic rich, silty clays. 1 n ' L• CONDOR