Carlisle ‘Steels’ Itself for Superior Storage
Carlisle, Pennsylvania is known to many as the town where the
Pittsburgh Steelers once trained in the summer. This is where the
black and gold faithful would assemble at Dickinson College to watch
Lynn Swann make acrobatic catches and Jack Lambert hunt down running
backs like dinner.
Maybe some of those Steelers remember water breaks on searing August
afternoons—the cool liquid soothing their parched throats or sluicing
down their faces. When the trainer turned on the tap he took for granted
the delivery of water that’s been flowing since 1853, when the Borough
of Carlisle began providing water to the town and surrounding
communities. Today the water plant serves customers throughout the
Borough and portions of North Middleton and Middlesex Townships.
It’s all made possible because the Carlisle Borough Municipal
Authority and its partners insist that water is captured, treated and
pumped under rigorous specifications. Often overlooked but equally
important is how and under what conditions that water is stored, but
it’s something the utility takes seriously. So when it was looking to
upgrade its potable water storage it turned to Arro Consultants and Mid
Atlantic Storage, who recommended the Aquastore® system from CST.
The Borough had operated since the Great Depression with two
in-ground reservoirs with floating covers and recognized it was time to
transition to a more efficient, cost-effective and sustainable system.
The contract was awarded in the summer of 2012 and construction took
place over a 9 to 10-month period. Plans called for draining one cell at
a time during construction to ensure uninterrupted service. The key was
assembling the new storage tanks and putting them in service while the
old units were decommissioned. That’s where the Aquastore® stands head
and shoulders above the competition.
“Because the Aquastore® tank is factory coated there’s no need to
paint it in the field.” said Brian Hyde, Eastern Regional Sales Manager
at Mid Atlantic Storage. “Construction took about a third of the time of
a welded tank and that was a key factor in the successful completion of
Workers poured the foundation and erected the first of two tanks in
late 2012 and early 2013, then put that tank in service and completed
the second tank while taking the old storage cells offline one at a
time. As a result there were no glitches or interruption of service.
Mid Atlantic Storage is in its 31st year and has constructed roughly
3,800 tanks in eight states during that time. This was the company’s
first project for Carlisle Borough and the introduction was made at the
PA-AWWA’s annual conference.
“We’d done multiple tank projects with Arro Consultants and their
familiarity with us made the difference.” said Hyde. “It definitely
shows the importance of working with your partners time after time and
gaining their trust and respect.”
One of the biggest differentiators of CST’s glass-fused-to-steel tank
is its multi-step fabrication process:
- A panel of high strength low carbon steel is blasted and
- The edges of the panel are beveled and then it’s sprayed with a
stainless steel alloy.
- The panel is sprayed with a specially formulated slurry that
gives it durability, consistency and impermeability. Unlike powder
coatings or paint, the slurry is inorganic so it blocks corrosion.
- The panel is then fired at temperatures above 1,500° F (815° C)
to fuse the porcelain coating and the steel.
- Tests are conducted to verify integrity and durability,
including high voltage testing to detect discontinuities.
The Aquastore’s glass coating makes it more resistant to extreme cold
and heat than welded steel tanks. Its seamless surface means there are
no cracks or crevices to attract rust and the absence of corrosion or
leakage greatly mitigates the chance of hazardous runoff or leaching.
The Aquastore’s minimal maintenance requirements translate to
significantly lower long-term costs than that of bolted tanks. For
example, repainting the interior and exterior of a welded tank costs
more than three times as much as replacing the interior and exterior
fillets (sealants) of the glass-fused-to-steel tank. A municipal water
provider in South Dakota estimated that maintenance for a glass-fused to
steel tank over a 60-year span would cost $266,000 compared for $906,000
for a painted welded tank.
Another important feature is the ability to easily expand an
Aquastore® tank. The free-span, geodesic aluminum dome roof is
constructed first, and then lifted into the air with a jacking system so
the individual steel panels can be assembled underneath. Crews don’t
have to leave the ground and the whole process takes as little as four
feet of space beyond the tank foundation.
“This way you can expand the tank vertically.” said Hyde. “We built a
foundation for a larger tank so the Borough can expand from a 28 foot
sidewall height with capacity 1,290,000 gallons to a 48 foot sidewall
height with capacity of 2,170,000 gallons.”
And that brings great efficiencies to the Borough, should it decide
to expand service to other municipalities.
“We’ve seen a great deal of demand for the expanding tanks,” said
Hyde, whose company is an authorized distributor for Aquastore®. “An
increasing number of municipalities have taken advantage of that because
they like to know they can efficiently maximize their storage capacity.”
The job went without a hitch due in part to the adaptability of
Aquastore®, which can easily accommodate internal systems. The Borough
installed a mixing system to maintain acceptable trihalomethane (THM)
levels and to keep the water from freezing. Despite single digit
temperatures for days on end in the winter of 2014-15, the water in the
Aquastore® tanks never froze.
Hyde has taken clients to CST’s factory in DeKalb, Illinois to watch
the firing of the Aquastore® panels. He also shows them the Aquastore®
in the field, including tanks up 25+ years old so they can see firsthand
the beauty and durability of the glass coating.
“They’re often surprised to learn these tanks have already survived a
number of summers and winters because their exquisite finish looks like
new,” said Hyde.
The Borough is already seeing the many advantages of using
glass-fused-to-steel tanks for potable water storage. Besides ease of
assembly, they have greater lifetime value, far lower maintenance costs
and little environmental impact compared with other liquid storage
“We couldn’t be happier with our Aquastore® tanks,” said Pete Selan,
treatment plants director for the Borough of Carlisle. “From performance
to maintenance to appearance, they’ve exceeded our expectations and
given us a permanent solution that will meet our needs for decades to