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COAL TAR RECOVERY UPDATE
Thick, viscous, oily, and sticky, coal tar tops the list
in the field of contaminated site remediation and source recovery
when it comes to being the ugliest and most stubborn substance
to clean up in quantity. Due to the difficult nature of coal
tar, initial recovery efforts at the 30-acre Calhoun Park
Area Superfund Site in the historic harbor district in Charleston,
SC, which began in 1998, were skimpy and sporadic until March
2001, when a Blackhawk Electric Piston Pump was brought in
to do the job. This pump worked so well at removing coal tar,
three additional Blackhawk Electric and Pneumatic Piston Pumps
were put to work. Where once only a few gallons of gunk could
be collected or skimmed away, more than 11,000 gallons of
coal tar have been pumped out from the substrate at depths
to 32 ft. below grade.
The coal tar being removed is the byproduct from a manufactured
gas plant (MGP) that operated at the Calhoun Park Area Site
from 1855 to 1957. Prior to the use of natural gas and electricity,
coal gas was used first for lighting, then for cooking purposes.
Coal gas was created by heating or “cooking” coal
in large airtight ovens. As the gas cooled in the piping and
large gas holders, substantial amounts of coal tar as a byproduct
were generated. The use of coal gas became obsolete with the
widespread availability and lower cost of natural gas. The
aboveground MGP facility was demolished, yet the coal tar
residues below surface remained. These were assessed for remediation
in the early 1990s for removal by South Carolina Electric
& Gas (SCE&G), the principal subsidiary of SCANA,
an $8 billion (assets) energy holding company serving customers
in North Carolina, South Carolina and Georgia.
“The first area we tackled for coal tar recovery was
the gas holder area. An electric Blackhawk Anchor 101 pump
with electrical controls was used in this area, where at 32
ft. underground, the coal tar is extremely thick and heavy.
An automated controller was utilized and adjusted to ensure
a slow and controlled recovery rate of one minute every hour
around the clock. A second automated electric pump was added
to a coal tar recovery trench. These pumps have worked for
us very well given the conditions, and we have recovered on
average three 55-gallon drums of coal tar per month from both
wells,” said Thomas Effinger, who manages SCANA’s
MGP remediation program.
“We’re also pleased with the results we’ve
had with our two Blackhawk Trident Pneumatic Piston pumps.
In order to tackle other areas of the site, our contactor,
Management and Technical Resources (MTR), excavated as much
of the coal tar as possible, then dug a trench around the
perimeter of the site, which is where we move the pneumatic
pumps from well to well to recover coal tar from 15 to 20
feet below the ground surface.”
Blackhawk Pumps are ideal for use in urban environments,
such as this one in Charleston, S.C., because they do not
emit any fugitive emissions. Therefore there is no smell or
stink in the city air from the pumped coal tar. The top head
drive motors of the Blackhawk Pumps ensure that an operator
has minimum contact with any liquid being pumped and that
the pump discharge air is free of contaminants, providing
a safe, clean and healthy working environment.
Effinger continued, “We’ve had impressive, consistent
and reliable pumping results with Blackhawk pumps, and a challenge
or two along the way. When cold weather hits, coal tar is
practically impossible to pump. By placing heat tape on the
pump along with a drum heater, this problem has been alleviated.
We’ve also learned that because the tar is so thick,
oily and sticky, the pneumatic pumps have to be cleaned every
night for top performance the next day and, due to the viscosity
of the coal tar, the seals have to be replaced frequently.
The great news is that despite encountering a few glitches
here and there, we’ve got everything under control and
when there is not enough tar material left in the well to
fill the pipe, we’ll have a job well done.”
Blackhawk Environmental’s Anchor Electric and Trident
Pneumatic Piston Pumps act like a syringe to extract product
from the bottom of the well with every stroke. Because the
pump inlet is at the bottom of each pump, liquid is pulled
into the pump intake, and the pump operates consistently whether
the pumping action is clean or dirty. The positive displacement
action resists slowdown or stoppage even in the most sticky
or oily situations. There are few moving pump parts in the
well to cause problems. The pump drive mechanism is positioned
on top of the wellhead, so each pump is easy to install, inspect,
trouble shoot, and maintain.
SCANA Corporation is headquartered in Columbia, SC. Its businesses
include regulated electric and natural gas utility operations,
telecommunications and other non-regulated energy-related
businesses. SCANA’s subsidiaries serve nearly 571,000
electric customers in South Carolina and more than one million
natural gas customers in South Carolina, North Carolina, and
Georgia.
Blackhawk Environmental Co. specializes in manufacturing
quality pumps and controls for demanding pumping applications.
Blackhawk pumps can be powered pneumatically or electrically
and can work in hazardous or potentially hazardous environments.
For more than a decade, Blackhawk pumps have been successfully
operating in a wide range of pumping applications across the
United States. Blackhawk’s pumps are custom manufactured
in a variety of sizes and designs depending on the application.
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