4.4.2.6   Implementability -- Alternative 2

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

As discussed in Section 4.4.1.6, 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 HTTD systems has
been gained.  However, less operating experience has been gained
during full-scale applications of dechlorination.  From an
operational standpoint, dechlorination is easy to implement
because it involves a single reactor batch system.  In addition,
if the dechlorination reaction does not work or if oil cannot be
easily separated from water or fines in the condensing system,
the oil can be treated at an off-site incinerator.

                                 

System Reliability

At the WBD site, thermal and mechanical stresses caused the inner
kiln of the ATP to crack.  The geometry and metallurgy of the
inner kiln were then modified to better accommodate the thermal
and mechanical stresses encountered during operation of the ATP. 
The burner design system was also modified to reduce stresses
caused by high temperatures.  The ATP system can now be used at
combustion zone temperatures of up to about 1,500 ¿F.  A second
drive system was also installed to reduce the load on the motor,
gearbox, and shafts of the ATP system.  The downtime associated
with the inner kiln and drive system replacement was about 2
months.  No problems involving failure of the inner kiln or drive
system occurred during the remedial activities at the Waukegan
Harbor Superfund site. 

Steel debris and conglomerates in the contaminated soil at the
WBD site caused problems with feed throughput into the ATP. 
Pieces of steel that interfered with the sand seal of the retort
zone caused a shutdown to remove the debris.  Problems were also
encountered when soil conglomerates could not pass through the
feed hopper.  As a result, feed had to be prepared for treatment
by removing steel debris with a magnet and pulverizing the soil
conglomerates with an asphalt grinder to reduce the particle size
to less than 2 inches in diameter.  The only problem with the
contaminated soil at the Waukegan Harbor Superfund site occurred
when oily wastes occasionally bridged in the feed hopper.

The results of the WBD SITE demonstration indicate that the ATP
exceeded the PCB and particulate limits specified in its air
permit.  The permit violations resulted from the type of bag used
in the ATP's flue gas baghouse.  During the SITE demonstration,
SoilTech used a fiberglass woven bag that abraded because it was
not sturdy enough for the air pulse system used to clean the bag. 
After the demonstration, SoilTech switched to a felt (Nomex) bag. 
Before the Waukegan Harbor Superfund site remediation project,
SoilTech switched again to a felted glass (Huych) bag.  The Huych
bag is more durable than the Nomex bag at higher (up to 375 ¿F)
temperatures (EPA 1993c).
Administrative Feasibility

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

Availability of Services and Materials

Dechlorination and HTTD services and materials are readily
available.  Many companies offer preconstructed HTTD equipment. 
Dechlorination systems can be designed using off-the-shelf
equipment; however, a license must be obtained to use the APEG or
BCD technology.  Most HTTD systems can be transported on trailers
and can be assembled at the site.  Because HTTD systems have been
used at a significant number of Superfund sites, many experienced
operators are also available.  Materials for dechlorination and
primarily reaction chemicals can be supplied in bulk and are easy
to obtain.

Additional Information Needed to Implement Dechlorination and
High Temperature Thermal Desorption

Additional information, especially additional waste
characterization and treatability testing, is needed to evaluate
the technical feasibility of implementing the dechlorination and
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 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.

Treatability testing is also needed to predict the performance of
dechlorination and HTTD for removing and destroying PCBs.  The
treatability testing should be conducted by the dechlorination
and HTTD contractor that will provide the treatment system.  Most
contractors have established treatability study protocols to
obtain performance data and other information needed to design
the appropriate APC equipment and to establish preliminary
operating conditions for the system.