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the ASB mixture. This test involves examination of any leachate from sample ASB mixtures with
and without contaminated materials generally through use of a gas chromatograph.
5. Contamination Types and Levels.
a. The types of petroleum hydrocarbon materials that can appear in contaminated soils can
vary considerably. The following is a list of possible materials (after Ellison 1991):
Light Fuel Oils No. 1 and No. 2
Heavy Fuel Oils Nos. 4, 5, and 6
From this list the types normally associated with ASB material would include: diesel, light and
heavy oils, crude oil, and asphalt. Gasoline contaminated soils can be dangerous, especially at
high levels of concentration, due to their volatility which can constitute a fire or explosive hazard
(Cole 1994). Diesel can incorporate a broad range of petroleum products which vary significantly
in composition. Research has shown that all distillate fuels, such as diesel, contain polycyclic
aromatic hydrocarbons (PAHs) (Stone 1991). The toxicity of diesel can be primarily related to
these levels of PAH and these levels will vary widely between different diesel materials (Block et
b. One difficult issue of interest is the need to develop appropriate levels of contamination.
There is a need to quantify low and high levels of contamination. Appropriate detection limits are
needed. Some states and other agencies have allowable limits at or below detection limits for
standard tests (Bauman 1991). Some materials are more difficult to detect than others and even
the type of soil that was contaminated can have an effect on the results.
c. Soils lightly-contaminated with gasoline when used in small amounts can be used to
produce ASB, but the final product tends to be of low quality (EPA 1992 and Friend 1996). This
is because the light fraction hydrocarbons soften the asphalt cement binder, making the binder act
like a cutback material which would require complete curing or evaporation of the gasoline to
allow the asphalt cement to bind properly. Light and heavy fuel oils have been most commonly
used to produce ASB; however, they also normally do not meet most state department of