U.S. patent application number 11/591420 was filed with the patent office on 2008-05-08 for drainage element and method and machine for making same.
Invention is credited to Buddy Harry Bussey, Harry Bussey.
Application Number | 20080107482 11/591420 |
Document ID | / |
Family ID | 39359864 |
Filed Date | 2008-05-08 |
United States Patent
Application |
20080107482 |
Kind Code |
A1 |
Bussey; Harry ; et
al. |
May 8, 2008 |
Drainage element and method and machine for making same
Abstract
The drainage element is made with a tubular membrane that
encasing a mass of discrete aggregate. The membrane being gathered
together at each end thereof, is water-permeable and has a
plurality of interstices characterized in being of a size for the
passage of water therethrough and the filtering of fine particles
of solid material from the water passing through the membrane. A
short length of pipe may be fabricated into one end only of the
drainage element to provide for a hook-up to a sewage system or
other system.
Inventors: |
Bussey; Harry; (Marco
Island, FL) ; Bussey; Buddy Harry; (Atlantic
Highlands, NJ) |
Correspondence
Address: |
Francis C. Hand, Esq.;c/o Carella, Byrne, Bain, Gilfillan, Cecchi,
Stewart & Olstein, 5 Becker Farm Road
Roseland
NJ
07068
US
|
Family ID: |
39359864 |
Appl. No.: |
11/591420 |
Filed: |
November 2, 2006 |
Current U.S.
Class: |
405/45 |
Current CPC
Class: |
E02B 11/00 20130101 |
Class at
Publication: |
405/45 |
International
Class: |
E02B 11/00 20060101
E02B011/00 |
Claims
1. A drainage element comprising a mass of discrete aggregate
defining passageways for a flow of fluid therethrough; a tubular
membrane encasing said mass of discrete aggregate, said membrane
being gathered together at each end thereof and being
water-permeable and having a plurality of interstices characterized
in being of a size for the passage of water therethrough and the
filtering of fine particles of solid material from the water
passing through said membrane; and tie means closing around each
gathered end of said membrane to retain said aggregate therein.
2. A drainage element as set forth in claim 1 wherein said membrane
has a grab tensile strength of 61/61 lbf as measured under ASTM
D-5034 and a grab elongation to break in % of 45/50 as measured
under ASTM D-5034.
3. A drainage element as set forth in claim 1 where said membrane
is made of spun bonded non-woven polyester.
4. A drainage element as set forth in claim 1 wherein said membrane
has at least a pair of overlapped longitudinal edges adhesively
secured to each other.
5. A drainage element as set forth in claim 1 wherein said membrane
has at least a pair of sewn together longitudinal edges.
6. A drainage element as set forth in claim 1 further comprising a
pipe extending from within said mass of aggregate and beyond one
end of said tubular membrane, said pipe being of a length less than
the length of said tubular membrane.
7. A drainage element as set forth in claim 5 further comprising a
screen disposed over an end of said pipe within said mass of
aggregate for blocking entry of said aggregate into said pipe.
8. A drainage element as set forth in claim 5 wherein said tie
means at said one end of said tubular membrane is secured about
said pipe.
9. A drainage element as set forth in claim 1 further comprising a
pipe extending from within said mass of aggregate and beyond each
end of said tubular membrane.
10. A drainage element as set forth in claim 1 wherein said
membrane is embossed to increase the surface area thereof.
11. A drainage element comprising a mass of discrete aggregate
defining passageways for a flow of fluid therethrough; a tubular
membrane encasing said mass of discrete aggregate; a pipe extending
from within said mass of aggregate and beyond one end of said
tubular membrane, said pipe being of a length less than the length
of said tubular membrane. tie means closing around each end of said
membrane to retain said aggregate therein.
12. A drainage element as set forth in claim 10 further comprising
a screen disposed over an end of said pipe within said mass of
aggregate for blocking entry of said aggregate into said pipe.
13. A drainage element as set forth in claim 10 wherein said tie
means at said one end of said tubular membrane is secured about
said pipe.
14. A drainage element as set forth in claim 10 wherein said
membrane is embossed to increase the surface area thereof.
15. A method of making a drainage element comprising the steps of
forming a longitudinal strip of a membrane into a tubular
cross-section about a longitudinal axis thereof with a pair of
longitudinal edges disposed in overlapping relation to each other,
said membrane characterized in being of a size for the passage of
water therethrough and the filtering of fine particles of solid
material from the water passing through said membrane; securing
said longitudinal edges together to define a tubular sleeve;
closing one end of the sleeve; moving said sleeve along a linear
path while filling said sleeve with aggregate; moving a pipe
coaxially into a rear of said sleeve while continuing to fill said
sleeve with aggregate; and closing the opposite end of said sleeve
about the pipe to form a drainage element.
16. A method as set forth in claim 15 further comprising the step
of placing a longitudinal bead of adhesive between said
longitudinal edges of said membrane and pressing said edges
together to bond said edges to each other.
17. A method as set forth in claim 15 further comprising the step
of placing a screen over an open end of said pipe prior to said
step of closing one end of said sleeve.
18. An apparatus for making a drainage element comprising a tube
for passing a flow of aggregate therethrough; a forming collar for
shaping a continuously supplied membrane strip having a pair of
longitudinal edges into a sleeve about said tube with the
longitudinal edges thereof in overlapping relation to receive a
flow of aggregate therein; first means for securing the overlapped
edges of the strip together; second means spaced from said tube for
intermittently applying tie means about the sleeve; third means for
moving a flow of aggregate through said tube for filling the sleeve
with aggregate; fourth means for moving the sleeve from said tube
during filling of the sleeve with aggregate; and drive means for
intermittently moving a pipe coaxially through said tube into a
rear of the sleeve while filling the sleeve with aggregate.
19. An apparatus as set forth in claim 18 wherein said first means
adhesively secures the overlapped edges of the strip together.
20. An apparatus as set forth in claim 19 wherein said first means
includes at least one roller for pressing the overlapped edges of
the strip together.
21. An apparatus as set forth in claim 18 further comprising a
cutting means for cutting through the strip and pipe.
Description
[0001] This invention relates to a drainage element and to a method
and machine for making the same. More particularly, this invention
relates to method and apparatus for making drainage elements having
a light weight aggregate encased in a tubular membrane.
[0002] As is known, drainage elements have been constructed of
loose aggregate, such as foam plastic elements, beads, and other
lightweight materials with or without a perforated plastic pipe
extending through and surrounded by the aggregate. Also, various
techniques have been known for making such drainage elements in a
manufacturing plant so that the individual drainage elements may
then be shipped to a construction site for use. Examples of such
techniques are described in U.S. Pat. Nos. 5,015,123; 5,154,543;
5,535,499; 5,657,527; and 6,173,483. Generally, these techniques
use a process in which a supply of aggregate is fed under gravity
into a horizontally disposed tubular mandrel through which a
corrugated pipe is passed horizontally and on which a length of
netting is mounted and fed off the mandrel as the aggregate fills
the netting. In some embodiments, the aggregate is pneumatically
conveyed into the netting while a reciprocating frame is provided
for feeding the netting from a sleeve.
[0003] One of the drawbacks of this type of technique is that the
length of the netting that is fed off the tubular mandrel is
limited. Further, the apparatus, as described, requires a positive
means for feeding the netting from the mandrel in order to prevent
the netting from narrowing and becoming frictionally engaged with
the outer surface of the mandrel.
[0004] Another drawback for this type of apparatus is that the
apparatus requires an expenditure of energy to drive the loose fill
material horizontally into the sleeve of netting.
[0005] Further, the drainage elements that are made in accordance
with these techniques have been relatively flexible. As a result,
drainage elements that are of long lengths, for example ten feet or
more, run a risk of the netting catching on equipment in the field
and becoming tom. In such cases, there is a risk that the aggregate
within the netting may spill out. Where the netting is made of thin
filaments so that the netting may be bunched up on the mandrel,
there is also the risk of the filaments bursting to an extent that
the aggregate can spill out of the drainage element. Also, the use
of a netting allows the netting to catch on other elements during
transport or during placement in a trench.
[0006] Further, use of a netting to contain the aggregate within
the drainage elements while allowing water and/or effluent to pass
through also allows fine particles of solid material to pass
through into the aggregate from the surrounding environment. As a
result, over time, the solid material can build up in the drainage
element to such a degree that the drainage element becomes clogged
and prevents a flow of water therethrough. In some cases, use has
been made of covers in order to prevent top dirt fill from falling
into the darinage elements. In other cases, such as described in
U.S. Pat. No. 6,854,924, proposals have been made to incorporate a
barrier material in a drainage element between the netting and the
aggregate to prevent the passage of outside media, such as sand,
dirt and soil, through the netting.
[0007] Accordingly, it is an object of the invention to provide a
drainage element that is able to filter fine particles of solid
material from entering into the drainage material.
[0008] It is another object of the invention to prevent clogging of
drainage elements employing discrete aggregate when in use.
[0009] It is another object of the invention to avoid catching of a
tubular drainage element on other elements during transport or
being placed in a trench.
[0010] It is an object of this invention to provide an apparatus
for making lightweight drainage elements on a substantially
continuous basis.
[0011] It is another object of the invention to provide a method
and apparatus of making drainage elements of compact construction
in an inexpensive manner.
[0012] It is another object of the invention to provide a drainage
element made with a tubular membrane that is tear-resistant.
[0013] It is another object of the invention to provide a drainage
element that is relatively rigid.
[0014] It is another object of the invention to provide a simple
means to prevent top dirt fill from falling between successive
placed drainage elements in a trench.
[0015] It is an object of this invention of to provide a simple
apparatus for making a drainage element of lightweight aggregate
with a plastic pipe at one end only.
[0016] Briefly, the invention provides a drainage element
comprising a mass of discrete aggregate defining passageways for a
flow of fluid therethrough; a tubular membrane encasing the mass of
discrete aggregate with the membrane being gathered together at
each end thereof and tie means closing around each gathered end of
the membrane to retain the aggregate therein.
[0017] In accordance with the invention, the membrane is
water-permeable and has a plurality of interstices characterized in
being of a size for the passage of water therethrough and the
filtering of fine particles of solid material from the water
passing through the membrane. In addition, the material has a high
tear strength and does not run, for example in the manner of a
nylon stocking. The membrane is made, for example, of spun bonded
non-woven polyester.
[0018] A method of making the drainage element comprises the steps
of forming a longitudinal strip of the membrane into a tubular
cross-section with a pair of longitudinal edges disposed in
overlapping relation to each other, securing the longitudinal edges
together to define a tubular sleeve, closing one end of the sleeve,
moving the sleeve along a linear path while filling the sleeve with
aggregate and closing the opposite end of the sleeve about the pipe
to form a drainage element.
[0019] In accordance with the invention, the overlapping edges of
the membrane strip are adhesively secured to each other or are sewn
together. For example, a longitudinal bead of adhesive, such as a
heat sensitive glue, is placed between the longitudinal edges of
the membrane and the edges are pressed together to bond the edges
to each other.
[0020] In another embodiment, a pipe is moved coaxially into a rear
of the sleeve while the sleeve is being filled with aggregate and
the trailing end of the sleeve is secured to the pipe at an
intermediate point of the pipe so that a length of the pipe
projects from the rear end of the drainage element. In this
embodiment, a screen is placed over the end of the pipe within the
aggregate in order to prevent aggregate from entry into and out of
the pipe. The resulting drainage element thus has a pipe at only
one end that can be used to connect to a hook-up arrangement while
the main body of the drainage element serves to convey water or an
effluent therethrough. Also, the pipe may extend completely through
the drainage element.
[0021] An apparatus for making the drainage element comprises a
tube for passing a flow of aggregate therethrough, a forming collar
for shaping a continuously supplied membrane strip into a sleeve
about tube with the longitudinal edges thereof in overlapping
relation to receive a flow of aggregate therein and a first means
for securing the overlapped edges of the strip together. This means
may adhesively secure the overlapped edges of the strip together by
applying a bead of adhesive between the edges pressing the edges
together using a roller.
[0022] The apparatus also includes a second means spaced from tube
for intermittently applying tie means about the sleeve, a third
means for moving a flow of aggregate through the tube for filling
the sleeve with aggregate and a fourth means for moving the sleeve
from the tube during filling of the sleeve with aggregate.
[0023] In making the drainage element of the second embodiment, the
apparatus includes a drive means for intermittently moving a pipe
coaxially through the tube into a rear of the sleeve while the
sleeve is being filled with aggregate.
[0024] In each embodiment, the apparatus has a cutting means for
cutting through the strip and pipe where inserted in order to form
a single drainage element.
[0025] The aggregate that is employed in the drainage element may
be a loose fill, plastic material or any other suitable
aggregate.
[0026] As the membrane is being formed into a sleeve and placed
over the tube, the membrane is gathered together at a point
downstream of the tube and a tie means is applied to seal off one
end of the sleeve. Aggregate is then passed through the tube and
into the sleeve in a conventional manner. After a determined length
of sleeve has been filled, the membrane is again gathered together
and a tie means applied to seal off a second end of the sleeve. The
cutting means is then operated to cut through the sleeve to form a
drainage element. A series of interconnected drainage elements can
thus be fabricated and shipped as such or the drainage elements may
be separated from each other by severing the gathered together
portions of the membrane at a mid-point for individual
handling.
[0027] In the second embodiment of the apparatus, a pipe is fed
coaxially into the tube from the rear and held in a fixed position.
Thereafter, as above, the membrane is formed into a sleeve and
placed over the tube. Then, the membrane is gathered together at a
point downstream of the tube and a tie means is applied to seal off
one end of the sleeve. Aggregate is then passed through the tube
and into the sleeve moving around and past the pipe. After a
determined length of sleeve has been filled, the pipe is fed
forwardly a predetermined distance while the aggregate continues to
fill the sleeve. The feeding of the pipe and aggregate then ceases,
the rear end of the sleeve is gathered about the pipe and a tie
means applied to secure the rear end of the sleeve to and about the
pipe. The cutting means is then operated to cut through the
trailing end of the sleeve and the pipe to for a drainage
element.
[0028] In another embodiment, a plurality of strips of membrane may
be supplied from different sources spaced peripherally about the
tube, particularly where a large diameter drainage element is to be
fabricated. In this embodiment, each strip is disposed peripherally
about one part of the tube with the longitudinal edges overlapped
with the adjacent strips. As above, the overlapped edges of the
strips are secured together thereby forming multiple seams along
the resulting sleeve.
[0029] The apparatus may be constructed so as to form the drainage
elements along a vertical axis, for example in a manner as
described in pending patent application Ser. No. 11/106,108 filed
Apr. 14, 2005. Likewise, the apparatus may be mounted so that the
drainage elements are formed on an angle to the horizontal. Also,
the apparatus may be employed so as to form the drainage elements
along a horizontal axis.
[0030] Where the apparatus is constructed to form a drainage
elements along a vertical axis, the aggregate may be fed under
gravity or may be fed pneumatically through the tube. Where the
apparatus forms drainage elements along a horizontal axis,
mechanical means or pneumatic means may be used to move the
aggregate horizontally through the tube.
[0031] These and other objects and advantages of the invention will
become more apparent from the following detailed description taken
in conjunction with the accompanying drawings wherein:
[0032] FIG. 1 illustrates a side view of a drainage element in
accordance with the invention;
[0033] FIG. 2 illustrates a partial side view of an apparatus for
making the drainage element of FIG. 1 at start-up;
[0034] FIG. 3 illustrates a partial side view of the apparatus of
FIG. 2 during an aggregate filling step in production;
[0035] FIG. 4 illustrates a partial side view of the apparatus of
FIG. 2 during an insertion of a pipe in accordance with the
invention;
[0036] FIG. 5 illustrates a partial side view of the apparatus of
FIG. 2 during a final tieing step;
[0037] FIG. 6 illustrates a side view of a series of drainage
elements laid in trench;
[0038] FIG. 7 illustrates a side view of an apparatus for making
the drainage element of FIG. 1;
[0039] FIG. 8 illustrates a view of the apparatus of FIG. 7 rotated
90.degree.;
[0040] FIG. 9 illustrates a schematic view of the apparatus of FIG.
7; and
[0041] FIG. 10 illustrates a perspective view of a cover placed
over two abutting drainage elements in accordance with the
invention.
[0042] Referring to FIG. 1, the drainage element 10 is comprised of
a tubular membrane 11 and a mass of aggregate 12 within the tubular
membrane 11. The aggregate 11 is made of discrete elements of a
size to define passageways for a flow of fluid therethrough.
[0043] The tubular membrane 11 encases the mass of discrete
aggregate 12 and is gathered together at each end with tie means
13, for example in the form of ties, closing around each gathered
end of the membrane 11 to retain the aggregate therein.
[0044] In the illustrated embodiment, a pipe 14 extends from one
end only of the drainage element 10. This pipe 14 extends into the
aggregate 12 for a minor length of the drainage element 10. In
addition, a screen 15 is placed over the internal end of the pipe
for blocking entry of the aggregate 12 into the pipe 14 while
allowing water to flow through.
[0045] The characteristics of the membrane 11 are such that the
membrane is tear resistant. Hence, there is a reduced risk of
netting being torn apart by catching on equipment in the field and
spilling of the aggregate 12 out of the drainage element 10.
Further, the membrane is water-permeable and has a plurality of
interstices characterized in being of a size for the passage of
water therethrough and the filtering of fine particles of solid
material from the water passing through the membrane 11.
[0046] The membrane 11 is made of a spun bonded polyester material
supplied by Oxco, Inc. of Charlotte, N.C. under model number
PROWALL 70, A070F01WT1 for use in landscaping, specifically, as a
weed retardant. Such a material is a non-woven material that has a
grab tensile strength of 61/61 lbf (in each of two trasverse
directions) and a grab elongation in % to break of 45/50 as
measured under ASTM D-5034 and a tear strength of 23/23 lbf as
measured under ASTM D-5733.
[0047] The membrane sleeve 11 is made of a material that is
sufficiently flexible so that the ends of the sleeve 11 can be
readily gathered together either about the pipe 14 or on itself to
allow the tie means to be applied.
[0048] Of course, any other suitable material may be used for the
membrane so long as the characteristics of strength,
permeability,filtering and flexibility are provided.
[0049] The aggregate 12 is made of an expanded thermoplastic
material and may be made of an expended thermoplastic material that
has a residual capacity to expand upon further curing so that when
fed into the membrane, a relatively rigid drainage element is
obtained after curing, for example as a manner disclosed in
copending patent application Ser. No. 11/248,753, filed Oct. 12,
2005.
[0050] Referring to FIGS. 7 and 8, the apparatus 16 for making a
drainage element includes a delivery tube 17 disposed on a
horizontal axis for passing a flow of aggregate (not shown)
therethrough from top to bottom. The aggregate may be supplied in
any suitable fashion, for example, the aggregate may be
pneumatically conveyed into the tube 17 via a blower or the
aggregate may be supplied through a vertical chute under gravity.
The aggregate is preferably a loose-fill material, such as discrete
elements of an expanded thermoplastic material.
[0051] In addition, the apparatus 16 includes a forming collar 18
disposed about the tube 17 for shaping a continuously supplied
strip 19 of the membrane into a tubular shape about the tube 17
with the longitudinal edges 20,21 of the membrane 19 disposed in
overlapping relation. The forming collar 18 is of any known
suitable type such as that supplied by DSL Forming Collars of
Houston, Tex.
[0052] During operation of the apparatus 16, the membrane strip 19
is supplied from a supply spool 22 on a continuous basis to the
forming collar 18 so as to be shaped into a sleeve about the tube
17 in a known manner. The strip 19 is supplied in a width suitable
to encompass the diameter of the tube 17 and to provide an overlap
of the two edges 20, 21, for example of one or two inches or
more.
[0053] The apparatus 16 also has a means of any suitable
construction for securing the overlapped edges 20, 21 of the strip
19 together. In one embodiment, this means includes an applicator,
such as a glue gun, 22' (see FIG. 7) for applying a bead of
adhesive between the overlapped edges 20,21 and a roller 23 for
pressing the overlapped edges 20,21 together to ensure that the
adhesive secures the overlapped edges 20,21 together. The adhesive
may be a heat sensitive glue that cools quickly.
[0054] A Teflon.RTM. strip 24 is also applied to the tube 17
opposite the roller 23 to reduce wear on the tube 17 from the
rotation of the roller 23 and to prevent the glue from sticking to
the tube 17.
[0055] A cooling means may also be provided for cooling of the
glue. Such a means may include a blower for blowing air onto the
outside of the overlapped edges 20,21. Also, the tube 17 may be
provided with holes where the overlapped edges 20,21 pass so that
the air that is blown through the tube 17 may exit through the
holes to cool the overlapped edges 20,21.This feature also provides
an air cushion between the tube 17 and the sleeve 11 so as to
prevent the sleeve 11 from sticking to the tube 17 while cooling
the sleeve 11.
[0056] In another embodiment, a sewing, machine (not shown) may be
used to sew the edges 20, 21 of the membrane strip 19 together. In
this case, the edges 20, 21 would be disposed radially of the tube
17 and in parallel relation to each other.
[0057] The apparatus 16 is provided with a means in the form of a
capstan arrangement 25 on diametrically opposite sides of the tube
17 in order to move the formed sleeve of membrane material along
the tube 17. The capstan arrangement 25 is comprised of a pair of
endless belt devices which are automatically operated in
synchronism in order to move the sleeve 11 off the tube 17.
[0058] Referring to FIG. 9, wherein like reference characters
indicate like parts as above, the apparatus 16 includes a hopper
(not shown) for receiving loose fill elements, the elongated sleeve
11 that extends horizontally from the hopper, a means in the form
of a blower 26 for blowing the loose fill elements from the hopper
into the sleeve 11 and the capstan arrangement 25 near one end of
the tube 17 for feeding the sleeve 11 off the tube 17.
[0059] The apparatus also employs a means 27 spaced from the tube
17 for intermittently applying the ties 13 to the gathered ends of
the membrane 11 as well as a cutting means 28 for cutting through
the gathered ends of the membrane 11 and any pipe 14 thereat.
[0060] In addition, a sleeve 29 is spaced from the tube 17 to
receive the forward end of a drainage element (not shown) that is
being fabricated. A sensor 30 is also disposed within the sleeve 29
at a pre-determined point for sensing the forward end of a drainage
element being fabricated.
[0061] A means such as a perforated pipe feeder 31 is provided for
delivering a continuous length of perforated pipe 14 within the
tube 17. When this option is used, the loose fill elements surround
the pipe in a circumferential manner within the tube 17.
[0062] The hopper (not shown) is of conventional structure to
receive and deliver a flow of loose fill elements vertically,
horizontally or on an incline.
[0063] The blower 26 is an off-the-shelf item, for example, a
Quickdraft 20 HP with Venturi that receives the loose fill elements
from the hopper and blows the elements into the elongated tube 17.
The operation of the blower 26 is such that only approximately six
to eight inches of the tube 17 at the exit end is filled with the
loose fill elements. The air that is blown into the tube 17 escapes
through the loose fill elements and the exit end of the tube 17 and
through the sleeve 11.
[0064] The tube 17 is of circular shape with an outside diameter,
for example of 10 inches and is initially loaded with the membrane
sleeve 11 of a 10 inch diameter.
[0065] Referring to FIG. 2, wherein like reference characters
indicate like parts as above, at start-up, the pipe feeder 31 (see
FIG. 9) of the apparatus 16 is operated so that a length of pipe 14
is moved to the front of the tube 17. A screen 15 is then fitted
over the end of the pipe 14. During this time, aggregate is not fed
into the tube 17.
[0066] Thereafter, the forward end of the membrane 11 is gathered
and a tie 13 applied to close this end of the membrane sleeve
11.
[0067] Next, referring to FIGS. 3 and 4, the blower 26 (see FIG. 9)
is actuated to blow aggregate into the sleeve 11 and the capstan
arrangement 25 is actuated to move the sleeve 11 from the tube 17
while the pipe remains fixed. The drainage element being formed
then moves into the sleeve 29 (see FIG. 9) until reaching the
sensor 30.
[0068] Referring to FIG. 5, when the sensor 30 detects the presence
of the drainage element being formed, a signal is emitted to the
pipe feeder 31 (see FIG. 9) to move the pipe 14 forwardly a
predetermined distance, for example 6 to 10 inches or more while
aggregate is still being fed into the sleeve. After a programmed
time, the blower 26 is stopped to cease delivery of aggregate into
the sleeve. However, the feeding of the sleeve 11 off the tube 17
continues for a short time sufficient to allow the rear end of the
sleeve 11 to be tied about the pipe 14 without interference from
the aggregate 12. Alternatively, the feeding of the sleeve 11 may
be interrupted or not during this time.
[0069] After feeding of the aggregate ceases, the tying means 27 is
actuated to gather the rear end of the membrane 11 about the pipe
14 and to apply a tie 13 to close the rear end of the membrane 11
onto the pipe 14. The cutting means 28 is then actuated to cut
through the gathered end of the membrane 11 and the pipe 14 to form
the drainage element 10 with the pipe 14 projecting from 1 to 6
inches from the end of the drainage element 10.
[0070] Thereafter, the exposed end of the pipe 14 within the tube
17 is fitted with a screen and the process repeated.
[0071] The apparatus 16 is operated so that the membrane strip 19
is continuously formed into a sleeve about the tube 17 and moved
off the tube 17 via the conveyors 25 while aggregate is delivered
on an intermittent basis through the tube 17 for passage into the
formed sleeve outside the outlet of the tube 17. Any suitable
valving may be used to interrupt the flow of aggregate into the
tube 17 or from the tube 17 during which time the tying means 27
spaced from the tube 17 is operated to gather and secure the
membrane 11 to form an end of a drainage unit and to contain the
aggregate therein.
[0072] Referring to FIG. 6, the drainage element 10 with the pipe
14 extension may be aligned in a trench with a series of drainage
elements 10' made without a pipe. In this case, the pipe 14 of the
drainage element 10 is connected to a source of effluent, such as
in a sewage system or to any other hook-up arrangement. The
effluent passing longitudinally through the drainage element 10
then passes longitudinally into the next drainage element and so
on.
[0073] Where the drainage elements are employed in a drainage
system, water is able to pass through the membrane sleeve 11 of
each drainage element in a filtered manner to flow through the
aggregate 12. The water may percolate downwardly to again pass
through the sleeve into the ground or the water may flow
longitudinally of the drainage elements to flow away from the
source. In either case, clogging of the aggregate with soil is
prevented.
[0074] Referring to FIG. 6, a cover 32 is placed in bridging
relation over the ends of two abutting drainage elements 10,10' in
order to prevent soil and the like from dropping into the space
between abutting drainage elements 10,10'. As shown in FIG. 10,
each cover is preformed into a generally U-shape with sides 33 that
extend downwardly about 12 inches and a central arched section that
conforms to the periphery of a drainage element. Typically, a stack
of these covers 32 would be supplied in the field so that each may
be individually placed over a joint between two drainage elements.
The length of each cover 32 is about 6 to 12 inches to ensure
bridging over of any gaps between successive drainage elements. The
use of the small length of the covers 32 is more economical than
using elongated covers that cover the entire length of a drainage
element.
[0075] The combination of the rigid drainage elements 10,10' and
the covers 32 form a worm hole for water to pass through.
[0076] The use of a drainage element with a stub pipe of limited
length makes the drainage element less expensive to make and faster
to manufacture.
[0077] The illustrated embodiment shows the tube 17 being disposed
on a horizontal axis. However, the tube 17 may also be disposed at
an angle to the vertical or may be disposed on a vertical axis.
[0078] The material of the membrane 11 is such that the diameter of
the membrane remains constant throughout the operation of the
apparatus 16. That is to say, there is no necking-down of the
membrane during travel on or off the tube. Thus, the membrane is
able to slide off the tube 17 without undue frictional grabbing of
the tube 17. Further, the membrane may be formed of a diameter
greater than the diameter of the tube 17 to allow the membrane to
be loosely held on the tube 17.
[0079] The strength of the membrane 11 allows the aggregate to be
fed under a high compaction force so that the resulting drainage
element has a high degree of rigidity. Further, where the aggregate
expands upon curing within the membrane, such as described in
copending patent application Ser. No. 11/248,753, filed Oct. 12,
2005, the degree of rigidity is increased without tearing of the
membrane.
[0080] The nature of the membrane 11 is such that the membrane may
be printed. This may be of value in designating the use of a
drainage element in the field. Further, the membrane may be
embossed, for example, with hemisperical embossments 34 as shown in
FIG. 1 of up to 1/8 inch in height to increase the surface area for
water to pass through.
[0081] The drainage elements that are formed may be of any suitable
diameter. In this respect, the tube 17 may be made of a diameter to
suit the diametric size of the drainage element desired. Also, for
very large diameter drainage elements, the strip 19 of membrane may
be made of multiple lengths of membrane that are spliced together
in parallel relation to provide a greater width of strip.
[0082] Where the cross-section of a drainage element is to be made
other than circular, for example, of an oval or elliptical shape,
the tube 17 may be made of a complementary shape and the forming
collar may be made to form the strip 19 about such a tube.
[0083] The invention thus provides a drainage element that is able
to filter fine particles of solid material from effluent entering
into the element and that prevents clogging of the discrete
aggregate when in use.
[0084] Further, the invention provides a drainage element that is
provided with a tear resistant cover that reduces the risk that the
drainage element may be tom open if snagged on equipment in the
field.
[0085] Still further, the invention provides an economical method
for making a drainage element with light weight aggregate that
prevents soil and the like from passing into the aggregate.
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