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CAP Addendum:Former Fuehg Station, 7500 West Eleventh Street, Tracy, dv� Page 12 solubility of its components. For diesel fuel, this is often given as 1.0 to 3.0 mg/L or 1000 to 3000 µg/L. For gasoline containing no additives, a solubility of 10,000 to 20,000 is usually quoted. However, for gasoline containing fuel oxygenates, those estimates of solubility jump to 100,000 to 200,000 µg/L(Lyman, Reidy and Levy 1992). When a groundwater sample was recovered from Monitoring Well MW-7 after the well had been purged on September 11, 2001, it contained 1,400,000 4g/L of diesel and 86,000 µg/L of gasoline. It is evident that the concentration of diesel greatly exceeds the solubility of that fuel in groundwater. Such conditions may occur because, when abundant LNAPL is present in the formation adjacent to the wall of the well boring, small emulsified droplets of diesel can become entrained in the extracted water. This may occur regardless of the thoroughness of the well purging. In the case of gasoline in the sample recovered from Monitoring Well MW-7 on that date, its concentration - 86,000 µg/L - is extremely high, but it is less than the possible saturation concentration for gasoline that contains oxygenates. Because of the likelihood that emulsified components of fuels may be entrained in the groundwater, sampling is not usually performed when LNAPL is present in a well. However, to obtain a general indication of the concentrations of components of fuels present in the groundwater, SJC, on a number of occasions, had analyses performed on water extracted from Monitoring Well MW-7 after it was purged. At the time of the July 2007 groundwater sampling round, there was 0.04 ft of LNAPL floating on the groundwater in Monitoring Well MW-7. After purging, a sample of water recovered from that well contained 49,000 µg/L of diesel and 40,000 gg/L of gasoline. Based on the saturation concentrations cited above, those figures indicate that the sample was oversaturated for diesel but may not have been oversaturated for gasoline. 2.3.3 Relationship_between Redox and Concentration of Fuel Hydrocarbons in Groundwater The relationship between the concentration of components of fuel hydrocarbons and the Redox Potential of the groundwater will next be considered. Figure 7 is plot of total fuel hydrocarbons in groundwater (i.e., the sum of the concentrations of TPHd and TPHd) against the Redox Potential of the groundwater. The data were taken from the results of the natural attenuation study and the associated groundwater-quality monitoring round that were conducted in March 2005 that are presented in Tables 2 and 4. As would be expected given the very large number of geochemical and contaminant chemistry parameters the affect Redox Potential and the nitrates and other dissolved materials loading the groundwater at the Navarra Site that vary greatly from location to location in the subsurface, there is a large degree of scatter in the data. However it is possible to statistically generate a trend line though the data that, as expected, indicated a reduction in Redox Potential with increasing concentration of components of fuel hydrocarbons in the groundwater. The equation of the trend line is: