4.4.5.4   Reduction of Mobility, Toxicity, or Volume through
Treatment -- Alternative 5

This evaluation criterion addresses the statutory preference for
selecting remedial actions that employ treatment technologies
that permanently and significantly reduce the toxicity, mobility,
or volume of hazardous substances.  This preference is satisfied
when treatment reduces the principal threats at a site through
destruction of toxic contaminants, reduction of the total mass of
toxic contaminants, irreversible reduction in contaminant
mobility, or reduction of the total volume of contaminated media. 
The plasma torch process as applied to the PCB-contaminated
materials at the six CD sites is expected to decrease mobility,
toxicity, or volume of contaminants.  

The ability of the plasma torch technology to reduce the toxicity
or volume of contamination at a site is assessed based on the
following considerations:

          Reduction in mobility of contaminants
          Reduction in toxicity of contaminants
          Irreversibility of treatment
          Reduction in volume of contaminated materials

Each of these considerations is discussed below.

Reduction in Mobility of Contaminants

The mobility of contaminants in the contaminated materials would
be reduced by the plasma torch technology through the production
of a nonleachable vitrified solid to which inorganics are bound.

Reduction in Toxicity of Contaminants

The toxicity of organic contaminants in the contaminated
materials would be reduced by plasma torch because the
contaminants would be destroyed.  The toxicity of inorganic
contaminants typically is not altered unless metals are oxidized
to a less toxic state.

Irreversibility of Treatment

The plasma torch technology permanently destroys organic
contaminants.  Leachate tests indicate that in the short-term
inorganic compounds are bound in the vitrified slag.  Long-term
testing of vitrified slag has not been conducted to determine
whether inorganic contaminants are permanently bound in the slag
matrix.  

Reduction in Volume of Contaminated Material

The reduction of volume resulting from plasma torch results from
the vaporization of gases and water in the feed and the
combustion of organic materials in the feed.  The volume
reduction values vary depending on the waste feed.  Feed with a
high organic or high moisture content would undergo a greater
reduction in volume.  Although the volume would be decreased, the
production of vitrified solids increase the density of the
treated materials.