4.4.4.4   Reduction of Mobility, Toxicity, or Volume through
Treatment -- Alternative 4

The quicklime treatment is an irreversible process that can
increase the mobility and volume and potentially increase the
toxicity of the PCB-contaminated waste.

The quicklime process provides an increase in mobility by the
dispersion of a majority of the PCBs.  This dispersal occurs when
water is added and PCBs are stripped from the contaminated
materials by steam.  The water added slakes the lime and a
reaction temperature of 180o F is reached.  At this point, the
PCBs with a smaller number of chlorine atoms tend to be
volatilized, thus entering the atmosphere.  PCBs containing a
greater number of chlorine atoms are also susceptible to
volatilization.

The quicklime treatment process has an unpredictable effect on
the toxicity of PCB-contaminated waste.  It does destroy up to
5 percent of the PCB components, decreasing toxicity to some
degree.  However, some of that degradation consists of
condensation to PCDF.  For instance, researchers have reported up
to 1 percent conversion of hexachlorobiphenyl to
tetrachlorodibenzodioxin isomers (Einhaus and others 1991). 
Determination of the overall effect of quicklime on waste
toxicity would require individual pilot-scale studies and careful
analysis.

The final volume of the treated soil/lime slurry is several times
the original volume of the contaminated waste.  This increase in
volume occurs through the required addition of such a large
amount of the quicklime reactant.  The ratio of quicklime to
contaminated waste is approximately two to one (Einhaus and
others 1991).