Note: Descriptions are shown in the official language in which they were submitted.
2153114
TITLE OF THE lNv~NllON
SECONDARY CONTAINMENT FOR ABOVEGROUND
FLAMMABLE AND COMBUSTIBLE LIQUID STORAGE TANKS
BACRGROUND OF THE lNv~NLION
The present invention relates to a secondary
containment unit for closed storage tanks which hold hazardous
and non-hazardous liquids, such as petroleum and the like.
More particularly, the invention provides an above-ground,
transportable containment unit, or dike, which can fit new or
existing storage tanks of varying sizes.
National safety and fire standards require that when
an above-ground liquid storage tank is used on site, it must
be contained within a containment unit in order to contain any
spills or leaks which might contaminate the environment or
otherwise pose a hazard. These containment units, commonly
referred to as "dikes", are generally open-topped tubs and
must be a prescribed size so as to accommodate the volume of
liquid held by the tank. The open top is prescribed by safety
standards which prohibit the use of a cover with the dike.
However, an open top permits the entry of precipitation and
debris into the dike thus allowing contact with any liquid
which may accumulate in the dike. This contamination would
prevent any future re-use of the liquid and could pose
disposal problems requiring the use of a specialized waste
disposal system.
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Many of the dikes currently in use do not provide a
means for protecting against the collection of precipitation
and debris in the dike. For those that do, the protection
device typically interferes with the venting, piping or
pumping equipment located on the top of the tank.
Further, in order to meet the existing safety
standards, many of the existing dikes require 1.5 metres
spacing between the dike wall and any surface of the tank
while in use. The storage and transportation constraints
which result from this oversizing are obvious and often
prevent a dike from being transported beyond a minimal
distance from site to site. The configuration of these dikes
also prevents the units from being easily transported over
anything other than a small distance, thus giving the industry
a regional nature.
For those secondary units which do provide some
means of portability, there is no provision for transporting
the dike with the tank in place. While many of the existing
units, as disclosed in combination with a tank, may be
transported over a short distance those that are secondary
units for existing tanks cannot be transported with the tank
in place because the dike does not provide means for securing
the tank during transport. Therefore, in the event that a
storage tank is needed at a different work site, it must be
removed from the dike and each piece must be transported
separately. This not only represents increased labour and
time, it may also result in increased costs to the user of the
dike.
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U.S. Patent No. 5,273,180 of Whatley Jr., issued
December 28, 1993 relates to a rectangular, open topped
containment tank in co-mbination with a liquid storage tank.
The containment tank is mounted on skids to facilitate
movement across the ground, with a towing bar at least one end
of the skids. There is also provided within the containment
tank a means for supporting the storage tank in position
during usage.
Canadian Patent Application Serial No. 2,070,939 of
Burton published December 11, 1993 relates to a cylindrical
inner tank in combination with a rectangular, open topped
outer tank. The outer tank is provided with cover means
permanently affixed to the walls of the outer tank and
extending to the outer surface of the inner tank.
Canadian Patent No. 2,041,556 of Harp issued March
1, 1994, relates to a hooded rectangular containment dike with
access means provided in the hood aligned to the expected
input or output lines on an inner storage tank.
U.S. Patent No. 5,287,986 of Frost issued February
22, 1994 describes a cylindrical outer containment unit
provided with a cover or hood.
It is an object of the present invention to provide
an above-ground secondary containment unit for existing
storage tanks of varying sizes and designs which m;n;m;zes or
prevents the entry of precipitation and debris within the unit
while the storage tank is in place yet permits easy access to
all pumping, piping and venting on the storage tank. It is a
further object of the invention to provide a means for
convenient storage of the unit which permits shipment over
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greater distances than is currently feasible with existing
units. Yet a further object is to provide means for securing
the storage tank within the unit so as to meet safety
standards and eliminate the need to remove the tank prior to
transporting the unit.
SUMMARY OF THE lNv~N-lION
In one aspect of the invention there is provided an
above-ground secondary containment unit for holding closed
liquid storage tanks. The unit is made up of a rigid base,
side walls extending upward from the base on either side and
end walls extending upward from the base connecting the side
walls. The unit has an open top. There is provided a
plurality of linear straps affixed at spaced locations to a
side wall extending across the top to the opposite side wall,
for releasably securing the storage tank within the unit
during usage and during transport thereof. There is further
provided side cover means secured to the side walls by hinges
and extending from the side walls to a side outer surface of
the storage tank during usage to minimize or prevent the entry
of precipitation and other materials between the tank and the
side walls of the unit. There is also provided end cover
means affixed to and extending from the end walls and resting
on an end outer surface of the storage tank while in use to
similarly minimize or prevent the entry of precipitation and
the like into the unit.
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In a preferred embodiment of the invention, the unit
is mounted on a horizontal planar skid member to provide a
means for transporting the unit either with or without the
storage tank in place within the unit.
In another preferred embodiment of the invention,
slotted apertures are provided on the end cover means for
releasably securing the cover means to the end walls while
allowing for lateral adjustment of the cover means. This
lateral adjustment permits the cover means to be in abutting
relation to portions of an end surface of storage tanks of
varying sizes.
The side walls and end walls preferably extend
upwardly from the rigid base at relative outwardly projecting
angles. This permits the unit to be stacked within another
unit for storage and shipment.
In another aspect of the invention, the unit is
combined with a closed storage tank suitable for the safe
storage of liquids. The tank is releasably secured within the
unit by the straps.
The dike of the present invention thus provides an
above ground, transportable containment unit made to
accommodate storage tanks of varying sizes. The dike's open
top and movable side shields and end shields facilitate easy
insertion of the tank within the dike and unimpeded access to
any vents, piping or pumps located on the top of the tank.
While in place, the shields minimize or prevent entry of
precipitation and debris between the dike and the tank. The
dike is provided with tie-down straps to secure a tank in
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place during usage and also providing a means for securely
transporting the tank and the dike as a single unit.
Accordingly, the invention comprises an above-ground
secondary containment unit for containing closed storage tanks
comprising a rigid base, upwardly extending side walls,
upwardly extending end walls transversely connecting the side
walls and open top, attachment means for releasably securing
the tank within the unit during usage and during transport
thereof, side cover means affixed to and extending from the
side walls, to rest on a side outer surface of the storage
tank below the uppermost portion thereof during usage for
m;n;m;zing or preventing entry of precipitation and other
materials into the containment unit, end cover means affixed
to and extending from the end walls, resting on the end
outside surface of the storage tank during usage for further
m;n;m;zing or preventing entry of precipitation and the like
into the unit.
The invention also comprises an above-ground
secondary cont~;nment unit in combination with a closed tank
suitable for the safe storage of liquids, the unit comprising
a rigid base, upwardly extending side walls, upwardly
extending end walls transversely connecting the side walls and
open top, the tank seated within and secured therein against
relative movement by an attachment means, side cover means
affixed to and extending from the side walls, resting on side
outer surfaces of the storage tank below the uppermost portion
thereof for m;n;m;zing or preventing entry of precipitation
and other materials between the tank and the containment unit
when in use, end cover means affixed to and extending from the
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end walls, resting on the end outside surface of the storage
tank for further minimizing or preventing entry of
precipitation and the like therebetween while in use.
BRIEF DESCRIPTION OF THE DRAWINGS
These and other advantages of the invention will
become apparent upon reading the following detailed
description and upon referring to the drawings in which:-
FIGURE 1 is a perspective view of the secondary
cont~;nment unit in combination with a closed storage tank
according to the present invention.
FIGURE 2 is a top plan view of the secondary
containment unit alone.
FIGURE 3 is an end view of the secondary containment
unit of Figures 1 and 2.
FIGURE 4 is a perspective partial view of an end of
the unit in Figure 1 showing in more detail a strap, a side
cover means in open position, a side cover hinge and end
cover.
While the invention will be described in conjunction
with an example em~bodiment, it will be understood that it is
not intended to limit the invention to such embodiment. On
the contrary, it is intended to cover all alternatives,
modifications and equivalents as may be included within the
spirit and scope of the invention as defined by the appended
claims.
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DET~TT.T~'.T~ DESCRIPTION OF THE lNVL llON
In the following description, similar features in
the drawings have been given similar reference numerals.
Turning to the drawings, Figure 1 shows an above-
ground secondary containment unit 2 in accordance with thepresent invention for an existing liquid storage tank 4. The
unit 2 comprises a rigid base 6, two opposite facing side
walls 8 extending upwardly and outwardly from the base 6 and
two end walls 10 connected to the side walls 8 at either end
thereof. This tapered shape, as shown in Figures 1 and 3,
facilitates shipment by permitting one unit 2 to be nested
within another similarly shaped unit (not shown). Two tie-
down straps 12 are provided with means 13 for affixing the
straps to the side walls at a position shown in Figure 1.
There is mounted on each of the side walls 8, by way
of a plurality of hinges 14, a side cover means 16, which
rests on a side surface 18 of the tank 4 while in use. These
cover means 16 m;n;m; ze or prevent the entry of precipitation,
debris and the like between the unit 2 and the tank 4. The
side cover means 16 pivots about the hinges 14 to allow easy
access to the tank 4 or the interior of the unit 2. The side
cover means 16 in open position is shown in Figure 4.
At the top of each of the end walls 10 is an end
cover means 20, adjustably mounted by way of a slotted
aperture 24 in combination with a nut 26 and bolt 28
arrangement. The slotted aperture 24 allows for lateral
adjustment of the end cover means 20 relative to the length of
the tank 4. When in position, the end cover means 20 rests
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against an end surface 22 of the tank 4, thus further
preventing the entry of precipitation, debris and the like
between the unit 2 and the tank 4.
In a preferred embodiment of the invention as
S illustrated, the unit 2 is mounted on a transport means in the
form of, for example, a horizontal planar skid member 30 as
shown in Figures 1 and 3 under the rigid base 6 for support
during usage and transport of the unit 2.
Thus, it is apparent that there has been provided in
accordance with the invention an above-ground secondary
containment unit that fully satisfies the objects, aims and
advantages set forth above. While the invention has been
described in conjunction with an example embodiment thereof,
it is evident that many alternatives, modifications and
variations will be apparent to those skilled in the art in
light of the foregoing description. Accordingly, it is
intended to embrace all such alternatives, modifications and
variations as fall within the spirit and broad scope of the
invention.
