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Eckert Cold Storage Company ' 757 Moffat Blvd, Manteca, California November 26, 1997 Underground Tank Investigation, Continued Phase I Report of Findings Page: 6 the fans occasionally prograded over the axial area of the trough in response to major ' climatic changes in the Sierras. This has resulted in a predominance of fine grained silts and clays in the subsurface of the area. 5.0 Soil Conditions ' The lithology at this site is characterized as thinly bedded silty sands, well-graded sands, silts and clays(Figures 4 & 5). Saturated sands below the water table became very fluid ("heaved", ' "flowed", "caved") and made well installation very difficult. Laboratory analysis of soil samples detected BTEX and Gasoline contamination in the soils ' above the water table in borings MW-1, 2 and 3. All soil samples for MW-4 tested "ND" (Table 1 & Appendix A). TEPH (for Kerosene, Diesel and Motor Oil) tested "ND" (None Detected) in all soil samples. 60 Hydrology ' California and the Federal Government have mandated that virtually all groundwater is ' beneficial for current or future use unless it can be demonstrated that no beneficial use is known. ' This aquifer is considered to be of beneficial use and as a result, must be protected from contamination. Those identified uses include agriculture and industrial, as well as potential use for animal or human consumption. 7.0 Groundwater Conditions ' Analyses of the six monitoring wells MW-1, 3, 4, 5, 6 & 7 (MW-2 was damaged and is used for water levels, only) show that contaminants are present in MW-1, 3, 6&7. tAll the wells were resurveyed after the addition of MW-5, 6 & 7. (Appendix F). Gradient was calculated from the wells and is also shown as Figure 11. The predominant direction is N490W ' at 0.00233 fl/ft (Figure 11). The surface of the site is paved, but the area to the east is open residential property. Recharge from surface precipitation is the probable cause of the steep gradient to the west. All groundwater samples collected during this event were non-detectable for the oxygenated ' compounds by EPA Method 8260.