Note: Descriptions are shown in the official language in which they were submitted.
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IMPROVBD FLUID DIRECTING SYSTEMS
The present invention relates to the exercise of
control over the flow of fluid without confining the fluid
to a conduit and is particularly applicable to directing the flow
water in a subterranean environment. More specifically,
this invention is directed to apparatus which faci~itates
the construction of subdrains, leach fields and filter beds
and especially to cellular forms which facilitate the
construction of such drains, fields and beds. Accordingly,
the general objects of the present invention are to provide
novel and improved methods and apparatus of such character.
While not limited thereto in its utility, the present
invention is particularly useful in and as underground
fluid distribution systems. In recent years, because of
the increasing awareness of the need to protect the
environment against contamination by pollutants and to
prevent silting of waterways, municipalities have adopted
regulations which have significantly increased the cost of
constructing various types of subterranean drain systems.
A desire has, accordingly, developed for techniques and
apparatus which will permit the construction of code
conforming drainage systems which require less labor and
less raw material such as, for example, crushed stone.
For a discussion of prior methods and apparatus for
underground water distribution, reference may be had to
U.S. Patents 3,563,038; 4,330,222; 4,538,386; 4,806,043.
The teachings of these prior patent are not directed to
solving the problems of establishing effective and reliable
drainage systems in an economical manner.
P~a~27i ~
The present invention overcomes the above-briefly
discussed and other deficiencies of the prior art by
providing a novel technique for constructing subterranean
drains and the like. The invention also encompasses unique
apparatus for use in such techniques and particularly
light-weight, collapsible, cellular forms which may be
employed to define the paths which the fluid to be
controlled will follow in, for example, flowing from a
first location to a desired second location. The forms in
accordance with the present invention are preferably
fabricated from a biodegradable material, corrugated
cardboard for example, which may be treated in a manner
appropriate to the intended application. The material
from which the forms are fabricated is configured such that
it may assume a flat shape for transportation and storage
and an open cellular, preferably hexagonal, shape when in
use. The form material will typically be provided as a
module which comprises an array of adjacent cells which
can, by any suitable means, be connected to other such
modules to define a flow path of any desired length. The
cell arrays have sufficient flexibility to allow for
installation in, for example, a curved configuration.
The present invention may be better understood, and
its numerous objects and advantages will become apparent to
those skilled in the art, from the following description of
embodiments given by way of example and with reference to the
accompanying drawin~swherein like reference numerals refer to like
elements in the several figures and in which:
Figure 1 is a top view of a portion of a leach field
fabricated employing the teachings of the present
invention;
Figure 2 is a side view of the apparatus of Figure 1;
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Figure 3 is a cross-section view of a portion of a
partially completed subterranean drain constructed in
accordance with the present invention;
Figure 4 is an end view of the drain of Figure 3;
Figure 5 is a perspective view of a modified form of
the drain of Figures 3 and 4; and
Figure 6 is a schematic side-elevation view of a
gas removal and moisture barrier system fabricated in
accordance with the teachings of the present invention.
The present invention is based upon a use of
individual cells which, in accordance with the preferred
embodiment, are collapsible in the interest of minimizing
shipping and storage space. These cells are also
preferably of hexagonal shape and defined by material
which, in its untreated state, is biodegradable. The
dimensions and configuration of the individual cells will
vary depending upon the intended usage. Similarly, the
stiffness, density and other physical properties of the
material from which the cells are fabricated will be varied
in accordance with the dictates of the end use. In the
disclosed embodiments the cells are interconnected to
define serial arrays and the arrays can be interconnected
to form a fluid directing channel of the desired or
requisite length and configuration.
With reference now to the drawings,and particularly
Figures 1 and 2, the present invention enables the defining
of a leach field of a sewage disposal system. When
compared to the prior art, this leach field has, for a
given length, significantly increased fluid transfer
surface area which contacts the native backfill. Figures 1
and 2 show an abbreviated leg of a leach field respectively
in a cross-sectional top view and a side elevation view.
The field leg, which is indicated generally at 10,
comprises a cell unit or array li which is defined by
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plural, interconnected, hexagonal shaped individual cells
12. The array of cells 12 which define field 10 is
fabricated from a fluid pervious, biodegradable material
such as, for example, corrugated cardboard. In accordance
with one reduction to practice, an elongated sheet of
cardboard was treated, for example by scribing or crushing,
to define pre-manufactured joints, the treated sheet
defining the exterior of the array. The sheet was closed
on itself, typically by an overlapping stapled or sewed
joint, in one of the straight portions thereof. The panels
14, which subdivide the array into the individual cells 12,
are inserted as shown and affixed to the sheet material by
any suitable means, through the use of adhesive or a
biodegradable paper tape for example. The resultant product
may be collapsed in accordion-like fashion for shipment and
storage.
The divider panels 14, and the sheet material which
defines the exterior of the array at the two opposing ends
thereof, are provided with aligned openings which are sized
to tightly receive a perforated leachate carrying pipe 16.
As may be seen from Figure 2, in the leach field -
application the holes which receive the pipe 16 are located
near the top of the array. The holes which receive pipe 16
may also be provided at slightly different levels in each
of the panels 14 so as to impart a desired pitch to pipe
16. As an alternative, which would be employed where pipe
16 is of flexible corrugated construction rather than
having a constant outer diameter, each of the panels 14 can
be constructed with a removable tapered knockout which
defines an opening extending from either the top or bottom
of the array so that the pipe 16 can be installed by
forcing it into the tapered opening from the side of the
array to which the tapered opening extends.
In the leach field application, presuming that the
trench has been dug, the array of cells 12 will be
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positioned in the trench and unfolded to the open condition
depicted in Figures 1 and 2. It will be understood, of
course, that a single leg of a leach field may be defined
by a series of the arrays which may be in abutting
relationship. After erection in the trench, and presuming
that the holes in the divider panels 14 will impart the
desired pitch to the pipe 16, the installer need only
ensure, for example by placing a level across the top of
the array, that the array is level. Thereafter, the pipe
16 will be installed, the individual cells 12 will be filled
with stone or aggregate filler 18 and the trench then
backfilled.
In use, the pipe 16 acts to carry leachate liquids
into the cellular system, the liquids being distributed
throughout the length of the field leg. The liquids will
percolate through the fill material 18, which thus acts as
a filter, while being aerated, and thus will permeate
outwardly through the stone or aggregate and into the soil
through the array defining sheet material/soil interface.
The sheet material, i.e., the fluid permeable cardboard in
the disclosed embodiment, surrounds the stone or aggregate
filter on the sides and, most importantly, promotes the
formation of a biological mat as is critical in renovating
the leachate. The sheet material, when used in conjunction
with a geotextile filter material installed in the trench
under the cell array, also acts to protect the biological
mat from failure thus reducing the likelihood of
concentrated mat break-throughs which would result in the
formation of saturated zones beneath the leach field. When
such saturated zones occur, unrenovated leachate liquids
may reach water courses and result in the pollution
thereof. It is to be understood that the sheet material
can be perforated to enhance its permeability.
As will be obvious to those skilled in the art from
the above discussion, the cellular system of the present
invention enables economical, controlled and proper
placement of a leachate distribution pipe and stone or
other aggregate filler and aeration material and, in so
doing, maximizes the efficiency of exfiltration of
liquids. This maximization of exfiltration efficiency
results from the geometric shape of the individual cells
which increases the effective filter material/soil
interface area. Simultaneously, this high degree of
exfiltration efficiency minimizes the amount of lahd
required for a leach field. Where there is biomat buildup,
solids settlement and resultant excess imperviousness occur
on the bottom plane of the leaching system. The present
invention is particularly novel in that it allows for
biomat buildup by having the greatest area of exfiltration
surface on the vertical planes, i.e., on the exposed side
surfaces of the cells. Also, since the cells allow
placement of the filter materials within a closed form, the
quantity of such material which must be trucked to a site
and subsequently used is minimized.
The present invention also contemplates incorporating,
at the point of cell array manufacture, a geotextile
filtering fabric with the sheet material from which the
cell arrays are fabricated. Such geotextile filter fabrics
are known in the art and, for example, may be type EX-130
non-woven Geo-Textile fabric available from Exxon Chemical
Corporation. By incorporating the geotextile filtering
fabric with the sheet material from which the arrays are
fabricated at the point of manufacture, the quantity of
fabric required is minimized. The filtering fabric can be
arranged such that it overlaps both the bottom and sides of
the array of cells. However, the manufacture of the cell
arrays is simplified by having the geotextile filtering
fabric, if employed~ on the sides of the cells only and, if
necessary or dèsirable, placing a layer of the material at
the bottom of the trench and/or over the top of the cells
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at the time of installation. When the geotextile filtering
fabric is utilized, after the cell defining material
degrades, the fabric is left to act as an interface between
the stone filter and soil. The geotextile filtering fabric
also contributes to the formation and subsequent
maintenance of a biological mat.
Although the cellulose in the cardboard sheet
materials is in itself a source of food for the biomat
development, for added protection, and since the
biodegradable cell-defining material is liquid absorbing
and porous in nature, the material can be impregnated with
an agent which promotes the growth and early development of
the biological mat or crust. For example, in the preferred
embodiment where the cell arrays are defined by corrugated
cardboard, the cardboard may be impregnated with a biological
mat/crust promoting agent, such as a biologically
compatible cardboard adhesive, and this agent can be
employed with or without the geotextile filtering fabric.
In addition to the ability to choose the shape of the
individual cells by controlling the degree of expansion of
the cell array from its fully collapsed condition, it is to be
noted that the side panels can be made longer in the
horizontal dimension than the divider panels 14. Also, if
a particular application needs greater cell depth than
afforded by a standard unit, the cell units can be stacked.
In one reduction to practice of the invention, the
leach field defining cell arrays were fabricated from 275
pound C-type cardboard and defined a field section having
eleven (11) individual cells, a total length of eighty-
eigh~ (33) inches (2.24m), and a ~.c?th oF ~irty (3~) inches (75 ~).
The length of the dividing walls 14 may be of the order
of 8 inches (200mm) for example.
Referring now to Figures 3 and 4, the application of
the invention to a drainage system, i.e., a system where
the intended fluid flow is into the cells rather than out
of the cells, is depicted. The arrangement of Figures 3
and 4 is generally the same as that of Figures 1 and 2.
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However, in the embodiment of Figures 3 and 4 the arrays
11' are defined by individual cells 12' which are complete,
i.e., closed on themselves, and each array is formed by
bonding the individual cells to one another. This results
in the dividing walls 14' between individual cells being
double thickness as shown. The use of cell divider or
partition walls of double thickness gives the array
increased strength to side loading and thus permits the
cells to be of greater depth. The individual cells are
joined one to another by any suitable means such as use of
a biodegradable adhesive, sewing, stapling, etc.
The embodiment of Figures 3 and 4 also differs from
that of Figures 1 and 2 in that the holes which receive
pipe 16' are adjacent the bottom of the cells rather than
the top. It will be understood that a geotextile fabric
can be employed in the subdrain application of Figures 3
and 4 to initially reinforce the sheet material and to
prevent, particularly after the sheet material which
defines the cells has degraded, silt infiltration. It will
also be understood that in the subdrain application it may
be desirable to incorporate, in the cell defining
biodegradable material, an agent which promotes the
degradation.
Figure 5 depicts the present invention as it could be
employed to direct liquid away from a wall 20. The
cellular array configuration of either Figures 1 and 2 or
Figures 3 and 4 can be employed in the Figure 5
application. In the Figure 5 embodiment, however, a fluid
impervious sheet material 22 may be applied to the cellular
array on the side which faces the wall. Also, as shown,
the silt control fabric, discussed above and indicated at
24 in Figure 5, may be employed on some or all of the top,
bottom and outer side surface of the cellular array.
Figure 6 depicts an end use similar to that of Figure
5 but having the additional ability of venting radon or other gas
, .
from beneath a building foundation. In the Figure 6
embodiment the foundation rests on a bed of crushed stone
and conventional perforated drain tiles 30 are provided.
Gas which is produced below the foundation, by diffusion from rock or
from decay of vegetation for example, will diffuse throught~.es~neb--d,
flow lnto the draln tiles 30 and be vented upwardly through
the cells of the drain system arrays of the present
invention which are indicted at 32. Fluid communication
between the interiors of the cells of the arrays which abut
the foundation wall and the drain tiles will be through the
stone bed in which the drain tiles 30 are buried. The
arrays of the present invention, in the Figure 6
utilization, are provided with perforated drain pipes 34
adjacent their upper ends. The perforated pipes 34 are
provided with cut-outs which communicate with vertically
extending vent pipes 36, the vent pipes 36 being provided
with caps 38 which prevent inflow of liquid.
While preferred embodiments have been shown and
described, various modifications and substitutions may be
made thereto without departing from the scope of
the invention. Accordingly, the present invention has been
described by way of illustration and not limitation.
