Liquid fertilizer manufacturer chooses steel walled secondary containment system
By Glenn Stokes,
Layfield Geosynthetics & Industrial Fabrics Ltd.
Containment system nearing completion.
After years of service, a solution was required for
the replacement of an eroding earthen dyke containing
an 88,000 imperial gallon steel walled
tank, for a liquid nitrogen fertilizer manufacturer
in Southern Ontario.
The task was to supply and install a new secondary containment
system to replace the current substandard earthen
berm. This project required a lining system to be sealed
around the existing concrete pad while providing chemical
resistance to the fertilizer. Design criteria and job constraints
included: speed of installation, ability to withstand a catastrophic
tank failure, and a 10 ft x 10 ft x 1 ft sump area also
had to be built. Down time of the tank had to be kept to a
minimum with the approaching growing season, plus attention
to design detail and shape of the containment system
had to be adhered to in order to allow easy access to the
tank with delivery trucks.
All existing pipe penetrations were removed and the
berms demolished. A 6 inch compacted sand base was constructed
while allowing for a low-lying area for the sump.
The site had good access and the project was to go ahead
during dry weather conditions in February 2002. An irregular
shaped 12 gauge, galvanized, 50 ft x 120 ft x 46 in high
containment system was chosen, manufactured by Grit Industries
Inc. and supplied by Layfield Geosynthetics and
Industrial Fabrics Ltd.
Plan layout of the new secondary containment system.
The G-55 system from Grit, is a free standing system,
which does not require support posts so the entire wall system
was installed in a matter of days. The unique footprint,
due to the flexible nature of the G-55 wall panels, allowed
space for delivery trucks to drive up close to the rounded
end of the system and the square end provided the 110%
required capacity. The narrow walls allowed for a tighter
design radius of the system while maintaining capacity as
compared to the wide base of an earthen berm. By choosing
this system the owner has the option of altering the tank
farm size, thus capacity, by adding or removing wall panels
as the tank farm grows in size.
The geomembrane containment liner was prefabricated
and shipped to site in two large panels premeasured to fit
this system thus minimizing
waste. Supplied by Layfield, the
Enviro Liner 30 was chosen for
its low cost, UV and chemical
resistance. The largest panel,
roughly 60ft x 132ft, was deployed
and a relief cut was made
on site to fit around the concrete
pad that supports the tank and
then seamed in the field extending
to the G-55 wall. The
geomembrane was then mechanically
attached to the concrete
pad using concrete bolts,
flat bar, neoprene gasket and finally
caulked. The second liner,
roughly 15ft x 15ft, was seamed
on site for the sump area, and the
perimeter of the overall liner was
attached to the top of the G-55
system and trimmed to fit.
Prefabrication of the liner reduced 90% of field welding
and allowed the entire 5,049 square foot area (does not include
the tank area) to be lined and tested for seaming integrity
and the walls assembled by Layfield in about three
days with a crew of four.
As there are several geomembrane liners available with
varying chemical resistance properties, this system can be
used in numerous secondary or primary containment applications.
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