4.4.1.6   Implementability -- Alternative 1

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

Technical Feasibility

The technical feasibility of implementing the HTTD technology
depends on (1) operating experience and technical difficulties,
and (2) system reliability.  These considerations are discussed
below.  




Operating Experience and Technical Difficulties

HTTD systems have been widely used during the past 5 years to
remediate hazardous waste sites containing organic contaminants. 
Therefore, a significant amount of knowledge concerning the
operation of the systems has been gained.  The systems are highly
automated and automatically shut down when lower or higher than
desired temperatures occur and when positive pressure occurs in
the processor.  Because of this automation, most HTTD systems are
technically easy to control.  However, heterogenous wastes
containing various amounts of hydrocarbons, moisture, or material
types may increase the difficulty of maintaining steady
temperatures and pressures in the processor; therefore,
contaminated materials should be blended or mixed with treated
inert material for better control of the system.

System Reliability

During POP testing at the Waukegan Harbor Superfund site, the ATP
system had problems meeting the site-specific requirement for the
PCB DRE of 99.9999 percent and total dioxin and furan emissions
requirement of 30 ng/dscm at 7 percent oxygen.  Process
modifications implemented in March 1992 resulted in improvements
in ATP stack emissions.  The process modifications included the
following:

          The carbon bed depth in the stack was increased to 24
inches.

          The scrubber was taken out of service and converted to
          an adsorption unit by addition of two new carbon beds
          to the scrubber.

          The retort zone residence time was increased by
          reducing the amount of solids recycled from the
          combustion zone to the retort zone through the sand
          seal.

          Activated carbon beds were installed in the preheat and
          retort zone noncondensable vapor return lines to the
          burners.

          The burners were operated at their maximum capacity to
          maintain the combustion zone temperature at the maximum
          operating level.

          Possible leaks in the GAC adsorption system were
sealed.

These process modifications enabled the ATP system to meet the
PCB DRE and dioxin and furan emissions requirements at the
Waukegan Harbor Superfund site.

On-line percentage, the percentage of time that a system
operates, is one measure of the reliability of a treatment
system.  SoilTech reports achieving an on-line system percentage
of 85 percent at the Waukegan Harbor Superfund site.  

Administrative Feasibility

The administrative feasibility of HTTD depends primarily on the
ability of an HTTD system to receive all necessary federal,
state, and local permits.  The HTTD system would have to be
tested to evaluate whether the system can meet the required
performance standard for PCB removal of 2 ppm.

Availability of Services and Materials

HTTD services and materials are readily available.  Many
companies offer preconstructed HTTD equipment.  Most HTTD systems
can be transported on trailers and be assembled at the site. 
Because HTTD systems have been used at a significant number of
Superfund sites, many experienced operators are also available.  

Operation of many HTTD systems requires maintenance supplies and
services such as welding supplies and tools, PPE, and leased
equipment such as front-end loaders.   An adequate supply of
spare parts such as pumps, flow meters, and piping should also be
available from an on-site supply or from a nearby industrial
supply center.  For hollow-auger heating systems, additional
heating fluid should be kept on site to replenish minor losses in
the heating system.

Additional Information Needed to Implement High Temperature
Thermal Desorption

Additional information, especially additional waste
characterization, is needed to evaluate the technical feasibility
of implementing the HTTD technology to treat wastes from the six
CD sites.  For wastes that contain a large concentration of
organics such as the solid waste and sludge, waste
characterization studies should be conducted to determine the
British thermal unit (Btu) content, ash content, and moisture
content.  An ultimate analysis should also be conducted to
determine the elemental makeup of the solid waste and sludge. 
These parameters are important to evaluate the heating and
cooling requirements for the HTTD system.  The particle size
distribution of all contaminated materials should also be
determined to estimate the amount of fines in the contaminated
materials.