5.1 This practice is a screening procedure for determining the presence of fuels containing aromatic compounds in soils. If a sample of the contaminant fuel is available for use in calibration, the approximate concentration of the fuel in the soil can be calculated. If the fuel type is known but a sample of the contaminant fuel is not available for calibration, an estimate of the contaminant fuel concentration can be calculated using average response factors based on composition of the fuel in the soil. If the composition of the contaminant fuel is unknown, a contaminant concentration cannot be calculated, and this practice can only be used only to indicate the presence or absence of fuel contamination.

5.2 Fuels containing aromatic compounds, such as diesel fuel and gasoline, as well as other aromatic-containing hydrocarbon materials, such as crude oil, coal oil, and motor oil, can be determined by this practice. The quantitation limit for diesel fuel is about 75 mg/kg. Approximate quantitation limits for other aromatic-containing hydrocarbon materials that can be determined by this screening practice are given in Table 1. Quantitation limits for highly aliphatic materials, such as aviation gasoline and synthetic motor oil, are much higher than those for more aromatic materials, such as coal oil and diesel fuel.

Note 1: The quantitation limits listed in Table 1 are estimated values because in this practice, the quantitation limit can be influenced by the particular fuel type and soil background. For information on how the values given in Table 1 were determined, see Appendix X1. Data generated during the development of this screening practice and other information pertaining to this practice can be found in the referenced research reports (1, 2).3

5.3 When applying this practice to sites contaminated by diesel fuel, care should be taken in selecting the appropriate response factor from the list given in Table 2, with consideration given to whether or not the fuel contamination is fresh or has undergone weathering or biodegradation processes. See Appendix X2.

5.4 A consideration in using this practice is whether the contamination is a mixture of one or more fuel types. If this is the case, and a site-specific response factor (see X2.3) cannot be determined, the response factors for the individual fuel types in the mixture should be used to estimate contaminant concentrations.

5.5 Certain materials, such as asphalts and asphalt residuals and oils and pitch from trees and other vegetation, which respond as fuel when tested by the practice, give high blank absorbance values which may interfere with use of this practice. See 8.1.2.1 and Note 3 for information on determining if this practice can be applied to a specific soil containing one or more of these types of materials.

5.6 Extractable material, which scatters or absorbs light at 254 nm, is a potential interference for this screening practice.