26    THE USE OF PETROLEUM CONTAMINATED
SOILS IN COLD MIX ASPHALT
James C. O'Shaughnessy, Professor
Department of Civil and Environmental Engineering
Worcester Polytechnic Institute
Worcester, Massachusetts 01609
Susan Daly, Engineer
Metcalf & Eddy
Wakefield, Massachusetts 01880
Deborah Duhamel. Engineer
Metcalf & Eddy
Wakefield, Massachusetts 01880
Karen Daly, Environmental Engineer
Exxon Oil Corporation
Everett, Massachusetts 02149
Christine Nardini, Technical Manager
ESMI
Loudon, New Hampshire 03585
INTRODUCTION
Past practices have allowed soils contaminated with various petroleum products to be disposed
of in solid waste facilities. However, due to the decreasing availability of space and landfill restrictions in such facilities, new methods which focus on reuse and recycle for these contaminated soils have been developed. One approach focuses on treatment of these soils and reuse of
the soils as either a construction fill, or general soil material. The other major approach is focused on stabilizing the contaminated soil (and the contaminant) in an engineered product. Pavements and subbase materials constitute the majority of these engineered products.
In the case of hot mix asphalt pavements, the petroleum contaminated soils are treated in a kiln
which heats fine, medium, and coarse aggregate materials prior to mixing with heated asphalt cement in a pug mill. The hot mix pavement is then placed in a truck and transported to an appropriate pavement construction site. Typical temperatures associated with hot mix pavements exceed 325°F and result in the volatilization of many of the petroleum contamination constituents
associated with these soils. As the hot mix pavement cools and solidifies, the remaining petroleum contaminants are incorporated with the asphalt cement and bound within the pavement matrix.
The use of petroleum contaminated soils in hot mix pavements requires the excavation and
transport of these soils to a batch plant prior to their incorporation into useful product. If the remediation site contains a large amount of contaminated soil and also has a sufficient hot mix
pavement need at the site, a batch plant could be located on the remediation site. A hot mix plant
is usually limited to less than 10 tons of sandy soil a day in new asphalt cement pavements, due
to acceptable pavement aggregate specifications.
Contaminated soils are added to the aggregate stream at the asphalt plant. In practice, the soil
feed aggregate should be limited to less than 5% of the total aggregate feed at any time. This restriction is required to maintain final product quality and to minimize air emissions caused by
volatilization of compounds. The lighter fraction which can soften the final product is burned off
5/51 Purdue Industrial Waste Conference Proceedings, 1996, Ann Arbor Press, Inc., Chelsea. Michigan 48118.
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