A Preliminary Evaluation of the Effects of Agricultural Lime Addition to Organochlorine Pesticides in Soil

P. James Linton, Blasland, Bouck and Lee, Inc., 3350 Buschwood Park Drive, Suite 100, Tampa, FL 33618, Tel: 813-933-0697, Fax: 813-932-9514, Email: pjl@bbl-inc.com

Agricultural lime (quick lime – calcium oxide) is one of many additives used to stabilize soil and sediments for transport and disposal, and the slaking process is commonly used to treat sewage sludge.  The slaking process results in an exothermic reaction that releases considerable energy and creates, at least temporarily, hydroxyl radicals.  During the early 1990’s, some research was conducted into the possibility of using this reaction to treat polychlorinated biphenyls in soil and sediment.

Soil from a former agricultural chemical blending facility located in central Florida was being evaluated for stabilization options prior to initiation of an emergency removal action.  Soil contamination was primarily from chlordane, DDT and daughter products, and BHC isomers.  One of the potential stabilization options was addition of agricultural quick lime. 

Various ratios of lime to soil and moisture content were evaluated to determine the optimum mixture.  During this process, it was noted that those mixtures where the reaction temperature had exceeded 100^o Celsius showed two or more orders of magnitude reduction in concentrations of the organochlorines below those that would be expected due to dilution from the mixing ratio, and in many cases were below detectable levels.

Additional laboratory bench-scale testing was conducted, including the use of closed reaction vessels and off-gas trapping to determine if the organochlorines were degraded, or simply volatilized by the heat of the hydration reaction.  This poster presents the strategy for, and results of, the tests conducted.

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