4.4.5.5   Short-Term Effectiveness -- Alternative 5

The potential short-term effectiveness of the plasma torch
technology application involves worker safety considerations and
potential community exposures.  The technology's impact in each
area is discussed below.

Worker Safety

If a well designed plasma torch system is properly operated,
gases would be treated for hazardous vapors, particulates, and
metals prior to discharge and should not present any significant
risk to workers or the surrounding population.  Because of the
high temperatures and voltages involved in each stage of the
plasma torch process, suitable protection would be required for
the workers to avoid burn injuries.  Other potential risks during
the plasma torch process involve potential leakage of hot gases
from the furnace seals and fire hazards from the high
temperatures generated during the process.  Workers would have to
be provided with adequate personal protection to handle the
scrubber equipment and water, and only properly trained personnel
should be involved in the operation.  The scrubber water would be
stored in suitable containers for subsequent disposal as
hazardous waste.  The containers should be stored in a secondary
containment area and labeled appropriately, and proper hazard
signs should be posted.  The workers should also wear noise
pollution protection from plasma torch operation.  Workers should
also be monitored for heat and cold stress.

Potential Community Exposure

Potential community exposures to health hazards from application
of a plasma torch system could include exposure to stack gas and
fugitive dust emissions.  These potential exposures can be
addressed by developing standards for stack gas and dust
emissions at each site.  These standards must be approved by EPA,
IDEM, and local authorities before remediation begins. 
Compliance with the standards would be demonstrated during POP
testing and by testing during remediation.  Potential community
exposure issues are discussed below.

During processing, PCBs in the soil have the potential to
transform the feed into hazardous vapors and unstable solids
prior to stabilization.  Short-term effectiveness of the plasma
torch technology should be evaluated by examining analytical data
obtained from the vitrified solid, stack gas, and scrubber
liquor.  Emissions depend on the chemical characteristics of the
feed soil and the scrubbing system.  The scrubbing system
operated during the demonstration test was ineffective.  As a
result, without proper design and testing, adverse short-term
effects could occur.     

Scrubber design is critical for efficiently controlling and
capturing potentially hazardous vapors and emissions.  Primary
inorganic oxides of concern include nitrogen oxides.  Results
from demonstration testing conclude that nitrogen oxides are
formed in the plasma furnace.  Pure oxygen is fed to the primary
chamber while waste is being fed to the furnace, resulting in
high nitrogen oxides levels because air is used as the torch gas,
forming oxides of nitrogen when the torch gas passes through the
hot arc of the plasma.  Demonstration testing shows that the
average concentration of nitrogen oxides in the stack gas was
approximately 5,000 ppm, which corresponds to an emission rate of
2.6 pounds of nitrogen oxides per hour.  The emission rate
depends on the size of the torch used.  The feed rate of the soil
does not influence the level of nitrogen oxides in the exhaust
assuming that the same torch is used during the different feed
rates because the torch uses the same amount of torch gas
regardless of the feed rate of soil.   Appropriate APC equipment
should be implemented to minimize release of nitrogen oxides into
the atmosphere.

An indication of the ability of the plasma torch process to treat
organic media is the low levels of carbon monoxide in the
exhaust.  VOCs and SVOCs were not detected in the prescrubber
liquid or exhaust gas during demonstration testing, which also
indicates that organic compounds were combusted completely.

The amount of particulates captured by the demonstration test APC
system was small.  The low level of scrubber solids in the
scrubber sump indicates that APC equipment was inefficient.  Dust
from the feed may not have been retained in the melted soil in
the primary reaction chamber and may have passed through the
treatment process and the scrubbing unit into the exhaust blower
and stack gas.  If the dust did pass through the treatment
process, it is expected that a well designed wet scrubbing system
would be capable of capturing the particulates.  Selection of the
most suitable APC device is necessary before this technology can
be safely implemented.

The demonstration tests also show that not all of the volatile
metals are captured in the vitrified mass at the treatment
completion (EPA 1992d).  These volatile metals should be captured
by the gas treatment system if it is correctly designed.  Metal
emissions during the demonstration tests were almost exclusively
in the solid phase.  The significant vapor phase metals detected
included calcium and mercury.  Copper, iron, potassium, arsenic,
and lead were also detected in the stack gas (EPA 1992d). 
Volatile metals such as mercury, arsenic, lead, and zinc are
therefore expected to be present in the vapor phase during
treatment of the contaminated materials from the CD sites.  The
copper in the stack gas is suspected to originate from the throat
of the furnace and the torch electrode because copper is not
present in high quantities in the feed soil.  The high level of
zinc in the stack gas resulted from the high spiking level and
the relatively low boiling point of this metal in the temperature
range within the furnace.

The presence of chlorine with the zinc at this temperature range
rapidly increases the volatility of zinc.  In all cases, the APC
system should have captured the metals.  Demonstration results
indicate that volatile metals originally present in the feed soil
may appear in the scrubber water, possibly requiring treatment of
the water prior to disposal.