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David Jenkins <br /> 4/12/95 <br /> Page 3 <br /> 2 . Chemical Analysis <br /> Section 5 .2 proposes that soil samples will be analyzed <br /> using EPA Methods 8310 and 8020 . Given reasonable limits of <br /> detection, these methods should provide quantitative estimates <br /> of the concentrations of chemicals in petroleum of toxicologi- <br /> cal significance. Risk from petroleum fuels is generally <br /> proportional to the concentrations of benzene, carcinogenic <br /> polynuclear aromatic hydrocarbons (PAHs) , non-carcinogenic <br /> PAHs, toluene, xylene, and ethylbenzene. The concentrations of <br /> these chemicals are quantified by EPA Methods 8310 and 8020 . <br /> Based on the reported site history, these chemical analyses <br /> would seem to be adequate. However, if the site were used Tor <br /> purposes other than storage of locomotive fuel, it is theoreti- <br /> cally possible that other chemicals may be present . <br /> 3 . Location of Soil Samples <br /> Sixty-four soil borings are shown on figures 7a and 7b. <br /> Samples are to be taken from depths of 2 to 2 . 5, 5 . to 5 . 5 and <br /> 8 to 8 . 5 feet. The sample locations appear to cover the areas <br /> shown to have high total petroleum hydrocarbons (TPH) in <br /> sampling of previous years. The sampling grid should provide <br /> an unbiased estimate of the average soil concentration. <br /> Uptake of PAHs by home grown produce must be evaluated. <br /> Typically, the relevant root zone for vegetables in the top <br /> twelve inches of soil . Therefore, samples should be taken in <br /> the top twelve inches of the soil borings which would be <br /> relevant to the location of potential gardens. The results of <br /> these analyses would be used for estimating the concentration <br /> of chemicals located in vegetables grown in those gardens. <br /> If the risk assessment indicates that there could be a <br /> significant risk from home-grown produce, a variety of risk <br /> management options are possible. The risk management objective <br /> will be to mitigate exposure. Contaminated soil could be <br /> removed immediately which would likely cause disruption to the <br /> community and result in significant costs to CPL. <br /> Alternatively, contaminated soil could be removed as it is <br /> identified in the future. Gardening requires that the soil be <br />