4.4.5.6   Implementability -- Alternative 5

Implementation considerations for plasma torch systems include
technical feasibility, administrative feasibility, and
availability of services and materials.  Additional information
is also needed to implement plasma torch technology.  These
considerations are discussed below.

Technical Feasibility

With proper design, the implementability of excavation, removal,
transport, of waste, and treatment of waste in a plasma torch
system is moderate to difficult because of the complexity of the
plasma torch technology.  Mobile units have been constructed and
used and are considered effective for small-scale cleanups of
soils contaminated with metal and organic compounds; however, the
locations and large quantity of contaminated soil requiring
treatment make a full-scale unit at a central location more
practical.

Construction of the plasma torch unit should be routine; however,
ease of construction depends on initial planning, project
management, and detailed design activities.  Although most
testing of the plasma torch unit was conducted on a system with a
6-foot diameter primary chamber a full-scale, 10-foot diameter
primary chamber is proposed to treat the contaminated materials
at the six CD sites.  Treatability testing of a controlled pilot-
scale study must be conducted before detailed design and
construction.  In addition to the destruction of PCBs, the
complete design must address treatment rates, feed preparation,
interim feed storage, gas treatment, and utilities.  Feed
treatment rates depend on waste type and moisture content. 
Utility requirements are also a major consideration.  High-
powered electrical equipment is necessary, as are cooling water,
monitoring equipment, and associated utilities.  High electrical
requirements are associated with this thermal destruction method. 
Also, a climate controlled enclosure structure can be used to
house all equipment.  

During the demonstration tests, operations were interrupted by
unexpected problems with the furnace and the plasma torch (EPA
1992d).  The plasma centrifugal furnace uses heat generated from
a plasma torch to melt and vitrify solid feed material.  Problems
were associated with the plugging of the furnace piping leading
to the solids collection chamber.  The plasma torch relies on the
interaction of a high-frequency magnetic field and ionized argon
gas.  As a result, the high temperature and high voltage may
cause unanticipated power outages or problems.  During testing, a
high degree of maintenance was required because of equipment
failure.  The sump pump overheated, particulates clogged the
exhaust blower, and the torch developed a cooling water leak.  It
was concluded that torch cooling water leaks are the most common
form of equipment breakdown and are caused by "secondary arcing
within the primary chamber" and that welding the torch ram would
plug these pinholes leaks (EPA 1992d).  Torch electrode
replacement every 100 to 200 hours is the most regular
preventative maintenance procedure required to ensure
uninterrupted operation.  If these problems are not addressed, it
is possible that problems may occur during full-scale treatment.

The generation of vapors from incomplete combustion, solids from
the vitrification process, and scrubber liquid from the gas
treatment system require monitoring systems.  The demonstration
tests conclude that particulate emissions exceeded RCRA
regulations.  Constant monitoring of carbon monoxide, carbon
dioxide, oxygen, and nitrogen oxides should be conducted despite
the reliability of the afterburner. In addition, volatile metals
not captured in the molten soil at treatment completion should be
captured by the gas treatment system.  Solids would need to be
disposed of in an approved RCRA landfill or incinerator.

Plasma torch system success depends on the engineering and design
of the system based on the analysis of the media to be treated
and its characteristics.  The equipment and procedures must be
properly designed and performed for successful implementation of
the plasma torch system:  

          The furnace must be sized appropriately to handle the
          capacity of feed in 11 years and to prevent secondary
          arcing.  Proper preventative maintenance should also be
          performed.

          The proper number and size of plasma torches must be
          used to ensure complete heating and PCB destruction.

          A vapor treatment system should be designed to
          efficiently collect all hazardous vapors, particulates,
          and metals.  If necessary, nitrogen oxides reduction
          equipment should be used.

          Blower and associated piping must be sized properly,
          and particulate buildup and premature fouling should be
          monitored and prevented.

Administrative Feasibility

The plasma torch technology must be approved by local, state, and
federal agencies, including the EPA, as an acceptable alternative
treatment method.  All applicable local, state, and federal laws,
regulations, and permits must be obtained for excavation,
transport, and treatment of materials.  An Indiana Solid Waste
Facility Site Approval must be obtained.  In comparison with
incineration or other treatment technologies, no additional
permits are required. 

Availability of Services and Materials

Although thermal destruction is a sufficiently demonstrated and
implemented technology for the destruction of PCBs in soil,
plasma torch is an emerging process option.  Vendors are not
readily available, and demonstration testing has not been
documented for PCB-contaminated soil.  As a result, many of the
vendors rely on scientific theory that PCBs will be thermally
destroyed by plasma torch.  Bench-, pilot-, and full-scale
development has been completed by Retech, Inc., for VOC
treatment.  No testing has been conducted on a soil mass as large
as  627,000 yd3.  A competitive bidding process may also be
difficult to implement because vendors are not common.

A newly constructed system must be designed to adequately store
and treat contaminated soil.  Sufficient capacity for liquid and
solids disposal is expected.  The furnace is the critical item
related to capacity.  Two identical units have therefore been
proposed to treat the soil in the mandated remediation time. 
Provisions can be made during design to leave space for an
additional furnace, if necessary.  It is expected that APC
equipment will be readily available.  Plasma torch technology is
considered an emerging technology; therefore, operators with
plasma torch experience may not be readily available.

Additional Information Needed To Evaluate the Technical
Feasibility

Extensive treatability testing and results are needed to
characterize the waste and products of the plasma torch system
and to evaluate the technical feasibility of plasma torch for the
wastes from the CD sites.  This testing should assess the effect
of the feed materials at each site on the technology and
determine chemicals that may be formed during treatment. 
Specific information on the emissions and residues from PCB
destruction is also required.  This testing could provide
estimates on the cost of waste treatment.  In addition, vendors
must be evaluated for their ability to provide technical
assistance and support.