Note: Descriptions are shown in the official language in which they were submitted.
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STORMWATER RECEIVING DEVICE AND ASSEMBLY
Description
Technical Field
The present invention relates to the management of stormwater runoff, and more
particularly concerns devices which minimize and facilitate sediment
maintenance,
expand the storage capacity of stormwater management systems, and facilitate
the
infiltration of stormwater into the surrounding substrate.
Background Art
Culverts, catch basins, and storm sewers are the common practices for
collecting
and conveying stormwater runoff. In some instances such water is discharged
directly
into the nearest available water body despite the potentially adverse
environmental
effects of such action. In some other instances, stormwater management
facilities are
constructed to help manage the quantity and quality of the stormwater. Wet or
dry
retention or detention basins/ponds represent the most common structural
approach to
stormwater management. Although more environmentally sound than direct
discharge
into an existing body of water, such stormwater management approaches preclude
other
uses of the land. This is of particular importance where land values are high
andlor space
is limited. The open ponds may also be undesirable in locations near airports
because of
CA 02491126 2004-12-29
birds attracted by the pond, or in locations where health, liability or
aesthetic
considerations make them undesirable. Even the use of "dry" detention basins
frequently
results in the same type of problems associated with wet ponds. Without proper
maintenance, dry detention basins frequently transform into wet ponds.
Underground systems have also been developed to help manage stormwater
effluent. Such systems include the use of plastic arch-shaped, open bottom
stormwater
chambers arranged end-to-end in rows. However, all current underground
stormwater
management systems are limited by the amount of area available for their
installation.
This is particularly relevant to the plastic stormwater chambers. The largest
plastic
l0 chamber currently on the market has an arched cross-sectional area of 34
inches high by
60 inches wide and a length of eight and one half feet. The creation of larger
chambers is
limited by the forming capacity of molding machinery.
In a typical installation of plastic stormwater chambers, elongated hollow
plastic
chambers are emplaced in the ground to form a leaching field for receiving
stormwater
15 and dispensing the water into the surrounding earth. Such chambers have a
central cavity
for receiving inflow water. An open bottom, and apertures optionally located
in the sides
of the chambers provide the means whereby the water is allowed to exit the
central cavity
and disperse into the surrounding earth. The chambers are usually attached
endwise to
form long rows extending in side-by-side juxtaposition and seated upon a
granular
20 substrate such as crushed rock in a mufti-row array that constitutes a
leaching field The
CA 02491126 2004-12-29
stormwater is generally conducted to the array of rows by a large diameter
manifolded
pipe system that runs orthogonally to the rows closely adjacent one extremity
thereof.
Examples of stormwater dispensing chambers are disclosed in U.S. Patents
5,017,04 I ; 5,156,488; 5,336,017; 5,401,116; 5,441,363; 5,556,23 l and
6,361,248.
Stormwater typically carries considerable amounts of suspended particulate
material, commonly referred to as Total Suspended Solids (TSS), which
eventually
settles out as sediment within the stormwater management system. The
accumulation of
such sediment adversely affects the storage capacity of stormwater management
facilities, decreasing their effective life. The ef~'ective life of such
facilities can be
significantly extended with a maintenance program for sediment removal. Such
sediment
removal can generally be achieved by a vacuuming operation conducted by a
suitably
equipped truck. In such operation, a tube is extended from the truck through a
manhole,
through an associated riser pipe, and into the bottom of the chamber. The
sediment in the
bottom of the chamber is then removed by vacuuming.
Unfortunately, the maintenance of stormwater management systems is often
neglected, and typically occurs only when the system fails or sediment
accumulates to a
point where flooding occurs because of diminished storage capacity of the
system. This
problem has become so serious that some municipalities have imposed a
stormwater
maintenance "fee' on property owners to help pay for private-sector stormwater
facility
maintenance.
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Unlike stormwater wet and dry ponds, which are readily observable and
accessible,
removal of sediment from underground stormwater management facilities has
historically
been inherently more inconvenient and costly, resulting in resistance to their
use by some
municipalities. Some types of underground stormwater management facilities
even have
to be replaced in order to remove accumulated sediment.
United States Patent 6,719,490, issued 04/13/04 to the same inventor,
discloses a
sediment-accumulating accessory device which, when deployed beneath a plastic
chamber having a top portal, facilitates the accumulation and removal of TSS.
It has
been found, however, that the installation of such accessory devices is
difficult because
they tend to be buoyed upwardly when the granular backfill material is poured
into
surrounding relationship with the accumulating device and associated chamber.
It is accordingly an object of the present invention to improve the sediment
handling capacity of an underground stormwater management system.
It is another object of this invention to provide an accumulating accessory
device
interactive with a plastic stormwater dispensing chamber to increase the
sediment
handling capacity of an underground stormwater management system comprised of
said
chambers.
It is a further object of the present invention to provide a plastic
stormwater
dispensing chamber combined with an accumulating accessory in a manner to
facilitate
removal of accumulated sediment.
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It is yet another object of this invention to provide an accumulating device
of the
aforesaid nature which resists buoyant upward movement produced by granular
backfill
material.
It is an additional object of the present invention to provide a combined
stormwater
dispensing chamber and accumulating accessory of the aforesaid nature of
durable,
simple construction amenable to low cost fabrication and installation.
These objects and other objects and advantages of the invention will be
apparent
from the following description.
to Summary of the Invention
The above and other beneficial objects and advantages are accomplished in
accordance with the present invention by a stormwater receiving assembly
comprised of
an accumulating device interactive with a stormwater dispensing chamber
comprised of a
plastic wall elongated between inlet and exit ends and having an arched cross-
sectional
shape with upwardly directed peak and spaced apart parallel lowermost edge
extremities
defining an open bottom, said wall having clean out portal means in said peak.
The accumulating device is comprised of a compartment bounded by sidewall
structure elongated upon a vertical axis between upper and lower extremities,
said upper
extremity being open and having a perimeter disposed in a plane orthogonal to
said axis.
The improved accumulating device of this invention has retaining means
protruding
outwardly from said sidewall structure for receiving downward gravity force
from
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granular backfill material. The retaining means may be attached to or integral
with said
sidewall structure and may have the form of shelves, pockets or flanges
directed radially
outward from the sidewall structure.
The accumulating device is operatively positioned below said dispensing
chamber
in a manner such that the clean out portal means of the chamber is in centered
vertical
alignment with the lower extremity of said compartment.
In preferred embodiments, the sidewall stmcture of the compartment of the
accumulating device is downwardly convergent toward its lower extremity which
is
closed by way of a bottom panel. The sidewall structure may be fabricated of
four flat
panels joined in an inverted pyramidal configuration having a rectangular
upper
extremity. Alternatively, the sidewall structure may be of cylindrical or
conical
configuration, fabricated of plastic by way of a molding operation. Said
sidewall may
have apertures to permit water drainage. The size and configuration of said
upper
extremity may be such as to support the edge extremities of the overlying
chamber.
Brief Description of Drawings
For a fuller understanding of the nature and objects of the invention,
reference
should be had to the following detailed description taken in connection with
the
accompanying drawings forming a part of this specification and in which
similar
numerals of reference indicate corresponding parts in all the figures of the
drawings:
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Figure 1 is a top and side perspective view of an embodiment of the
accumulating
device of the present invention.
Figure 2 is a top and side perspective view of a stormwater receiving assembly
employing the accumulating device of Figure I .
Figure 3 is a schematic top and side perspective view of the assembly of
Figure 2
shown in functional association with a suction tube that removes accumulated
sediment.
Figure 4 is a top view of the assembly of Figure 2 with the chamber component
shown in phantom outline so as to reveal underlying features.
Figure 5 is a side view of a first alternative embodiment of the accumulating
device
of this invention shown in schematic functional association with components of
a
stormwater leaching field.
Figure 6 is a top view of a second alternative embodiment of the accumulating
device.
Figure 7 is a fragmentary top perspective view of the embodiment of Figure 6.
Figure $ is a fragmentary side view of the embodiment of Figure 6.
Detailed Description of the Preferred Embodiment
Referring now to Figure 2, an embodiment of stormwater receiving assembly is
shown comprised of receiving chamber 22 and an accumulating device 10
positioned
below said chamber. The accumulating device exemplified in Figure 2, as best
illustrated
in Figure I, is shown as a monolithic structure fabricated of polyethylene,
polypropylene
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or equivalent thermoplastic polymer and having a substantially uniform
thickness
throughout of between 2 and 10 mm. The accumulating device is comprised of a
compartment 1 1 having an open upper extremity 12 and closed lower extremity
13. Said
compartment is further defined by sidewall structure 14 which, at least in
part, is
preferably downwardly convergent upon center vertical axis I 5. The degree of
convergence is such that the cross-sectional area of the lower extremity,
taken in a plane
orthogonal to said axis is I 0% to 40% of the cross-sectional area of said
open upper
extremity. The height of the accumulating device, measured between said upper
and
lower extremities is preferably between 20 and 72 inches. In alternative
embodiments,
the sidewall structure may be comprised of an upper portion 77 of non-
convergent
configuration, such as cylindrical or rectangular shape, and a lower portion
78 of
convergent configuration. Said upper and lower portions may be interconnected
separate
pieces, or may be integral portions of a monolithic molded structure.
In the embodiment of Figures I-4, said sidewall structure is comprised of four
flat
panels 17 disposed in an inverted pyramidal configuration, causing upper
extremity 12 to
have a rectangular perimeter 19 defined by straight edges 16. Flat apron
panels 18.
emergent from opposed straight edges 16, are directed outwardly from said
compartment
within the plane of perimeter 19. Alignment means in the form of paired
retaining lips 20
are emergent from said apron panels and directed upwardly from said
compartment. Said
retaining lips engage the interior surface of the associated chamber 22
adjacent its
lowermost edge 25, thereby stabilizing the interaction of the chamber with the
underlying
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accumulating device and further serving to achieve lateral alignment of said
device with
associated chamber 22. Additional alignment means, which may be in the form of
indicia
66 on apron panels 18 and chamber 22, facilitate axial alignment of chamber 22
with
respect to accumulating device 10. Sidewall structure 14 may be provided with
a
multitude of apertures 21 which facilitate drainage of water from said
compartment. The
diameter of the apertures may range from 1/8" to 1 ". The total area of said
apertures
preferably occupies between 1 % and 10% of the total area of sidewall
structure 14.
Retaining means 68 extend outwardly from said sidewall structure, namely in a
direction away from axis I 5. Said retaining means are conrigured to
supportively receive
the surrounding granular back fill material, thereby enabling the weight of
said material
to force the accumulating device downward. Such downward force overcomes the
buoyant force otherwise produced by the backfill material, which tends to push
the
accumulating device upward.
In the embodiment shown in Figures 1-3, the retaining means are exemplified as
trough or pocket-shaped structures 69 attached to the sidewall structure in
symmetrical
disposition thereabout. Each of the four panels of the sidewall structure are
shown having
one continuous length of pocket structure 69. In related embodiments, second
or third
similar pockets may be spaced upwardly on the panels. In other embodiments,
the
pockets may be separate, discontinuous units. Regardless of the number or
configuration
of said retaining means, it is preferred that they be disposed in a
gravimetrically
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symmetrical manner with respect to axis 15, namely disposed in a manner which
will not
produce tilting of axis 15.
Figures 2-5 illustrate the manner in which the accumulating device 10 is
combined
with a stormwater dispensing chamber 22 for the purpose of increasing the
amount of
sediment that the chamber can hold, and also for facilitating the removal of
such
sediment from the chambers. Chamber 22 is comprised of a wall 23 extending
upon a
longitudinal axis between inlet and exit ends, 31 and 32, respectively, and
having an arch
shape cross-section with an upwardly directed peak 24, and opposed lowermost
spaced
apart parallel edges 25 which define an open bottom 26. Wall 23 has a
multiplicity of
corrugations 27 disposed in planes orthogonal to edges 25, thereby causing
said wall to
have increased compressive strength.
Chambers useful in the practice of the present invention are fabricated
preferably
of polypropylene or high density polyethylene by way of thermal vacuum forming
or gas
assisted injection molding techniques, generally in accord with the technology
described
in U.S. Patents 5,401,459; 5,087,15 I ; 4,247,5 I S; 4,234,642; 4,136,220 and
4,1 O l ,617.
During molding, the plastic is configured to form a chamber having outwardly
directed
hollow ribs or corrugations 27.
The chamber preferably has opposed axially elongated base panels 29 integral
with
said edges 25 of wall 23. Said base panels support the chamber, discouraging
its descent
into the underlying substrate.
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The terminal or first rib or corrugation 30 adjacent inlet end 31 may be
slightly
larger than the multitude of ribs, and terminal rib 33 adjacent exit end 32 is
slightly
smaller than the multitude of ribs. Such configuration of the terminal ribs
facilitates
end-to-end joinder of successive chambers wherein vertical lowering of a
chamber
automatically causes the larger rib of one chamber to embrace the smaller rib
of the next
successive chamber.
Typical chambers of this invention may have a length of 6-12 feet measured
between inlet and exit ends and a height up to 50 inches. The width of the
chamber,
measured between said opposed base panel 29, may range to 80 inches, including
the
width of said base panels.
Side inlet portal means 38 may be disposed in wall 23 for the purpose of
accommodating horizontally disposed conduits that deliver stormwater to the
chamber.
Top portal means 39 is disposed in the peak of wall 23 adjacent exit end 32.
Said top
portal means is either a circular aperture or an indented portion of the wall
which
facilitates the cutting of a circular aperture. This permits visual
observation of sediment
level and removal thereof by vacuum equipment. The expression "adjacent exit
end 32",
is intended to denote a site along the horizontal length of the chamber which
is within
20%, and preferably within 10% ofthe distance going from said exit end toward
the
opposed inlet end. The diameter of said portal means is preferably less than
the diameter
of the closed lower extremity 13 of said compartment.
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The exit end 32 of the chamber may be provided with flow impeding means in the
form of transverse panel 42, as best shown in Figure 2, having a lower
impervious
portion 43 and an apertured upper portion 44. Said transverse panel functions
to reduce
the velocity of water flow, thereby causing sediment to accumulate in the area
of exit end
32 of the chamber, and directly below top portal means 39.
Accumulating device l0 is intended to be functionally associated with a
stormwater dispensing chamber as shown in Figures 2-5, wherein said chamber is
positioned atop the accumulating device. It is to be further noted that the
device is
positioned such that its vertical axis I 5 intersects the center of top portal
means 39.
As shown in Figures 3 and 5, the combined chamber and accumulating device of
this invention is installed in an excavation and engulfed by granular material
such as
gravel or crushed rock 45 that extends to the top of the chamber. A filter
fabric 46 may
be disposed atop the granular substrate. A zone of compacted clean fill,
gravel or
crushed stone 47 extends from filter fabric 46 to an overlying layer such as
pavement 48.
A manhole 49 may be disposed in a concrete pad 50 centered above top portal
means 39.
A riser conduit 51 communicates between said manhole and top portal means.
Accumulated sediment is removed from the chamber by causing a suction tube 52
to pass
through conduit 51 to the bottom of the accumulating device. A vacuuming
operation
then transports the sediment upwardly into a servicing truck.
The first alternative embodiment of accumulating device 10, exemplified in
Figure
5, has an upper sidewall structure 77 in the form of a corrugated perforated
pipe of
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substantially cylindrical contour. The lower portion 78 of the sidewall
structure has a
conical configuration with a multitude of apertures 21. Retaining means in the
form of
annular shelf 73 is disposed at the juncture of the upper and lower portions
of the
sidewall structure. Said shelf may protrude outwardly about 3 to 9 inches.
The second alternative embodiment of accumulating device 10, shown in Figures
6-8, is similar to the embodiment in Figure 5, with the exception that the
retaining means
is now a series of radially oriented pockets 74 disposed as an annular array
about the
juncture of the upper and lower portions of the sidewall structure, said upper
portion
being shown in fragmentary phantom view. Said array of pockets is a single
shaped
structure 75 which is bolted or otherwise attached to the sidewall structure.
While particular examples of the present invention have been shown and
described,
it is apparent that changes and modifications may be made therein without
departing from
the invention in its broadest aspects. The aim of the appended claims,
therefore, is to
cover all such changes and modifications as fall within the true spirit and
scope of the
invention.
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