First details of tar ponds cleanup strategies released
By Tanya Collier Macdonald
Cape Breton Post
Thurs., Jan. 6, 2005
Cape Bretoners have received
their first detailed look at proposed
cleanup strategies for the
tar ponds and coke ovens sites.
An expression of interest
was advertised by the provincial
government Wednesday on the
tenders Web site.
The Department of Transportation and Public Works is
calling for an engineering firm
interested in monitoring the
planned remediation effort.
In that public tender, a project description summary
reveals some specifies on the
planned project, expected to cost
up to $400 million.
It reports that incineration is
the contaminated destruction
technology selected for both the
coke ovens and tar pond sites
remediation projects.
"PAH contaminated sediment from coke ovens brook,
contaminated material from the
tar cell at the former Domtar
site, and PCB contaminated sediment
greater than 50 ppm from
the north and south ponds, will
be incinerated."
The tender states the preferred
location of the incinerator
has not been selected, but
adds it won't be located at either
the coke ovens or tar ponds sites
due to restrictions.
"The incinerator will be used
as a temporary incinerator, it
will roll to the site on two to five
flatbed trailers, and be set up,"
the tender details.
"The facility will then
undergo a commissioning period
during which the operating
and control systems will be
calibrated for the waste feed.
Operation of the incinerator
will be governed by the operating
procedure established during
calibration. The incinerator
will be operated for a period
of approximately five years
at 15 tonnes per hour, 24 hours
a day, seven days a week for 250
days per year. The incinerator
and ancillary facilities will
occupy a land area of approximately
two to five hectares."
It also explains that once
contaminated material has
been excavated, it will be transferred
from its current location to an
incinerator staging area.
Rail cars or trucks are the
options listed as transport
methods.
A comprehensive monitoring
program will be developed
and implemented to ensure
the incinerator is operating
within regulatory requirements, it continues.
Wastewater treatment is
also required during the
cleanup and will serve as a
long-term function for
groundwater treatment after
the remediation projects have
been completed.
"Treatment will be
required for contaminated
wastewater produced at the
incinerator site, the sediment
dewatering area, truck and
equipment decontamination
pads, from personnel decontamination
areas, and others,"
the tender continues. "Treatment
is also required for contaminated
groundwater and surface water
at the coke oven site."
The tender states that
bioremediation and capping
is the selected treatment technologies
for the coke ovens work.
However, exposed sediment in
the former coke ovens
brook bed will be transferred
to the incinerator.
In addition, contaminated
soils in the tar cell will be
excavated to a depth of about
two metres below grade. An
enclosure will be constructed
during excavation to prevent
harmful discharges to the
environment and to provide
air treatment.
Vertical cut off walls will
be constructed on the coke
ovens site to control the movement
of clean and contaminated
groundwater and surface water.
The wall will be installed
north and south of the area to
prevent influx of clean
groundwater. They'll also be
installed to the west to prevent
the movement of contaminants
from the Sysco site
and walls will be installed to
prevent the movement of coal
tar from the Sysco site into
Coke Ovens brook.
Landfarming for parts of
the co-ke ovens sites is also
planned.
Oxygen, nutrients and
water will be applied to treat
the top half-metre of hydrocarbon
impacted soil at rates
most beneficial for biological
degradation of organic contaminants.
If it's determined that
odours and dust production
during the landfarming could
be a problem, the need for
vapour treatment facilities
will be investigated.
The tender confirms that
incineration, solidification,
stabilization and capping are
selected as the treatment technologies
for the tar, ponds portion of the cleanup.
The containment system
will consist of impervious
vertical walls installed at
various locations around the
edges of the tar ponds.
"Selected PCB contaminated
sediment will be dredged
and or excavated using a
combination of conventional
shore and water based technologies,"
the tenders details.
Impact to the water column
will be reduced by installing
turbidity control systems.
"Sediment removal could
work on 12 hours per day, seven
days per week for seven to
nine months per year. An
average dredging rate will
vary for a low of 400 to a high
of 1,500 tonnes per day."
PAH contaminated sediment
within the ponds will be
solidified and stabilized in
place using a binding agent
such as Portland cement.
A surface cap will then be
constructed.
Additional caps may be
necessary for contaminated.
sediments that remain.
tcmacdonald@cbpost.com
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