US20030077123A1

US20030077123A1 - Subterranean irrigation device and method of using the same

Info

Publication number: US20030077123A1
Application number: US09/982,738
Authority: US
Inventors: Matthew E. Moulton
Original assignee: Individual
Current assignee: Individual
Priority date: 2001-10-18
Filing date: 2001-10-18
Publication date: 2003-04-24

Abstract

A subterranean irrigation system comprises a conduit that is attached to a soaker sheet having upper and lower permeable membranes that define a hollow interior there between. The hollow interior facilitates fluid flow there through while minimizing fluid flow resistance. The sheet typically includes a heat welded side seam along three sides of the upper and lower membranes to prevent the flow of water there through, wherein the remaining edge of the sheet is secured to the conduit. The sheet further includes a plurality of holes cut into the upper and lower membranes, wherein the hole pattern extends over the entire sheet. The holes allow the roots of grass or ground cover to grow through the soaker mat and simultaneously define channels of water flow around the holes between the upper and lower membranes.

Description

TECHNICAL FIELD

The present invention relates to a subterranean irrigation device for lawns or the like, and more particularly, to a permeable membrane soaker sheet that is placed beneath sod or the like to water the sod from below.

BACKGROUND OF THE INVENTION

Large expanses of grass or ground cover, such as lawns, sport fields, playgrounds, and golf courses, typically are irrigated with an above ground water system. In particular, flexible hoses with attached sprinklers may be manually placed in a variety of locations on the expanse of grass to irrigate the area. To maintain a pleasing aesthetic appearance and to reduce tripping hazards, the hoses and sprinklers must be removed after each irrigation cycle. For some lawn uses, such as golf courses, these manually placed systems are unacceptable.

As a result of the numerous disadvantages of these manually placed sprinkler systems, permanently installed underground sprinkler systems have been developed. These underground sprinkler systems provide water through an underground pipe system, whereupon the water is delivered to “pop-up” sprinkler heads that are raised above the surface of the ground during watering. While these automatic “pop-up” sprinkler heads have reduced the manual labor requirements of watering, these systems are often subject to breakage and leakage at the sprinkler head. Moreover, both the manual and the pop-up sprinkler systems provide water in a fine mist above the grass or ground cover. It is estimated that approximately fifty percent of the water is lost to evaporation prior to reaching the ground.

Accordingly, fully subterranean irrigation systems have been developed. These systems avoid the tripping hazards and water evaporation problems of the above ground watering systems but are also subject to several disadvantages.

U.S. Pat. No. 6,161,776 to Byles discloses a multi-layered, porous mat turf irrigation apparatus and method wherein a continuous, three-layer system is disclosed. The mat comprises a central layer of large pore, lateral water distribution material that is sandwiched between two layers of small pore, vertical water distribution material. The disclosed system has several disadvantages. First, despite the large pore size of the central layer, the central layer of material provides resistance to the flow of water. Accordingly, the size of the mat is restricted due to water pressure restrictions. Second, the continuous sheet of material, having the small pore material layers in contact with the ground, provides a barrier to root growth there through. Accordingly, roots typically are prevented from growing downwardly past the top layer of the irrigation mat.

There is a need, therefore, for a subterranean irrigation system that has reduced resistance to liquid flow and which facilitates healthy root growth of the grass or ground cover there through.

SUMMARY OF THE INVENTION

The present invention provides a permeable membrane soaker sheet that is placed beneath sod to water the sod from below. The invention typically is used on lawns, sport fields, playgrounds, golf courses and the like, where there are large expanses of grass without many trees or shrubs. A water conduit, which typically is manufactured of a solid material such as PVC or copper piping, includes a fastener, such as threads, at one end so that the conduit can be attached to a water supply line, such as an underground watering system similar to an underground sprinkler system. The conduit is attached to a sheet having upper and lower permeable membranes that define a hollow interior there between. The hollow interior facilitates fluid flow there through while minimizing resistance thereto. The sheet typically includes a heat welded side seam along three sides of the upper and lower membranes to prevent the flow of water there through. The sheet further includes a plurality of holes cut into the upper and lower membranes, wherein the hole pattern extends over the entire sheet. The holes are defined by a heat welded seam around each individual hole. In one embodiment the holes have a size of approximately two inches by two inches. However, the holes may be of any size, shape or arrangement. The holes allow the roots of grass or ground cover to grow through the soaker mat and simultaneously define channels of water flow around the holes between the upper and lower membranes.

During installation of a grass lawn, the soaker sheet is placed directly on exposed dirt. The water conduit system is typically buried slightly lower than the soaker sheet (and is connected to a water system) so that the conduit is not easily damaged. Grass sod is placed directly on the soaker sheet or on dirt placed directly on the soaker sheet. The grass is watered by turning on the water supply to the conduit. In this manner, the roots of the grass are watered directly by water that seeps through the permeable material, without evaporation loss. The disclosed invention is believed to result in a fifty percent reduction in water usage for large grass areas such as playing fields and golf courses. The system may also be used to evenly and safely distribute fertilizers, weed killers, insecticides, and other chemicals in liquid form to a large grassy area.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a partial isometric view of the subterranean irrigation device; [0009]
FIG. 2A is a side cross sectional view taken along line [0010] 2A-2A of FIG. 1;
FIG. 2B is a side cross sectional view taken along line [0011] 2B-2B of FIG. 1;
FIG. 3 is a top view of the soaker sheet system sized to fit a specific shaped lawn area; [0012]
FIG. 4 shows a cross sectional, isometric view of another embodiment of the soaker sheet and conduit of the present invention. [0013]
FIG. 5 shows a top view of a [0014] subterranean irrigation system 10 including several patches therein and wherein the system has been trimmed to fit a particular sized turf area.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

FIG. 1 is an isometric view of [0015] irrigation device 10 including a water conduit 12, which may be manufactured of a solid material such as PVC, copper or other rigid piping. Conduit 12 may also comprise flexible piping, such as piping made of rubber, flexible plastic or the like. The conduit includes a fastener 14, such as threads, at one end so that the conduit can be attached to a water supply, such as an underground water source as known in the prior art. Fastener 14 may comprise threads, as shown, a slip fitting, a “grabber” style fitting including an O-ring, or any other type of fastener. Conduit 12 is attached to a sheet 16 manufactured of two fluid permeable membranes that define a space there between. Sheet 16 includes a heat welded side seam 18 that secures the two membranes together and prevents the flow of fluid there through. Side seam 18 typically extends around three sides of sheet 16. Sheet 16 further includes a plurality of holes 20 cut into the fabric, wherein the hole pattern extends over the entire sheet (only a small number of holes are shown for ease of illustration). The holes typically extend through each of the permeable membranes wherein the two membranes are secured together by heat welding, or other such connection means, around each individual hole or aperture. Each of holes 20 typically has a size of approximately two inches by two inches. However, the holes may be of any size, shape or arrangement. The holes allow the roots of grass or ground cover to grow through the mat thereby providing for vigorous root growth and stability of the grass or ground cover. This may be especially important on sloped grassy areas. The edges of the holes are sealed so as to form channels of water flow 22 between and around holes 20. The material that forms channels 22, i.e., the material of the top and bottom layers of the sheet, is manufactured of permeable material so that a large “soaker sheet” is formed having a waffle type or grid type hole pattern therein. Due to the presence of holes 20 in the sheet, the sheet comprises an alternating pattern of semi-permeable material and holes. This pattern facilitates uniform watering of the grassy area above and below the soaker sheet while allowing space for root growth and stability of the turf.
During installation of a grass lawn, the soaker sheet is placed directly on exposed dirt. The water conduit system typically is buried slightly lower than the soaker sheet (and is connected to a water system) so that the conduit is not easily damaged. Grass sod, or other like ground cover, is placed directly on the soaker sheet. Dirt may also be placed on the soaker sheet wherein sod, seeds or small rooted plants are planted in or placed on the dirt. The grass is watered by turning on the water supply to [0016] conduit 12. In this manner, the roots of the grass are watered directly by water that seeps through the permeable material, without evaporation loss. It is anticipated that the disclosed invention will result in a fifty percent reduction in water usage, due to reduced evaporation, for large grass areas such as playing fields and golf courses. Moreover, because the system is fully contained below the ground level, with no “pop-up” sprinker heads, there are no tripping hazards associated with the present invention. Additionally, due the open cavity defined between the top and bottom permeable membranes, the system of the present invention has reduced resistance to fluid flow when compared with subterranean irrigation systems of the prior art.
FIG. 2A is a cross sectional view of one embodiment of the sheet-to-conduit connection means of FIG. 1 taken along line [0017] 2-2. Conduit 12 is shown having a slit 24 along one side, wherein each membrane of sheet 16 includes a recessed slot area that is friction fit along the corresponding edge of slit 24. Accordingly, water 26 flows from conduit 12, through slit 24 and into the central cavity area of permeable soaker sheet 16. Soaker sheet 16 may be secured to slit 24 by any number of means, including adhesive, heat welding, mating tabs and slots, clamping, and the like. Moreover, conduit 12 may be manufactured integral with sheet 16 so that the conduit and the sheet and manufactured as a single unit, requiring no additional securement means there between.
Still referring to FIG. 2A, [0018] soaker sheet 16 comprises a top layer or membrane 16 a, a bottom layer or membrane 16 b and a space or cavity 16 c positioned there between. Top and bottom layers 16 a and 16 b, respectively, typically are manufactured of a semi-permeable material having a pore size large enough to pass fluid such as water at a rate equal to that needed to support vigorous lawn growth. The semi-permeable or permeable material may comprise a polysulfone such as a polyether sulfone, a cellulose material such as cellulose triacetate or cellulose triacitate, a polyolefin, a polyetholene, or any material that will function to distribute fluid there through. In particular, the permeable membranes preferably will have an average pore size in a range of 10 nanometers to 10,000 nanometers, and a sheet thickness of two mils to ten mils or more. Of course, the pore size and sheet thickness utilized will depend on the type of membrane material used and the fluid flow rate that is desired to pass through the membrane. Typically, hydrophilic membranes pass fluid more easily and, threfore, a smaller pore size would be used. Hydrophobic membranes typically pass fluid fluid less easily and, therefore, a larger pore size would be used. In general, planar soaker sheet 16 typically will have a thickness at least ten times smaller than the length and width dimensions of the sheet. However, any pore size or sheet thickness may be used as is desired for a particular application.
[0019] Central cavity 16 c offers minimal resistance to fluid flow so that sheet 16 can be manufactured and installed in large sheets, for example, sections measuring twenty feet by twenty feet, or more. Space 16 c is maintained, i.e., not collapsed, by the water pressure of water flowing there through, and by channel system 22 which is created by the plurality of holes 20 positioned along the sheet. In other words, each of holes 20 is manufactured by sealing sheet 16 a and sheet 16 b together around each hole 20, which provides a somewhat rigid grid shaped structure, thereby ensuring that space 16 c is maintained between sheets 16 a and 16 b along channels 22.
FIG. 2B is a side cross sectional view taken along line [0020] 2B-2B of FIG. 1 showing fluid channels 22, holes 20 and the upper and lower membranes 1 6a and 16b, respectively, secured together. In this figure, turf roots 17 can be seen growing through apertures 20 of the planar soaking sheet.
FIG. 3 shows a top view of a [0021] soaker sheet system 10 sized to fit a specific shaped lawn area. In particular, conduit 12 is connected via piping 28 to a water source (not shown). Conduit 12 is also connected to additional conduits 30 via standard tee or cross-shaped fittings 32. The fittings are capped with caps 33 at their ends along the edge of the soaker sheet system. In the system shown, there are six soaker sheets connected to the water source, wherein each of the sheets includes a hole pattern 21 (only a small section of hole pattern 21 is shown for ease of illustration) across the surface of each soaker sheet. Additionally, a particular sheet 34 also comprises a large hole 36 that is heat welded around its edge 38 so that a tree or shrub may be positioned within hole 36. If the shrub is very large so that it will not fit through hole 36 upon installation, a cut or slice 40 may be made through sheet 16, wherein the slice is heat welded along its edges. Cut 40 typically is aligned perpendicular to conduit 30 so that fluid flow in direction 42 from the conduit through the sheet is not hindered. Upper and lower membranes 16 a and 16 b typically are heat sealed together along the edge of cut 40, similar to the sealing treatment around holes 20 and shrub hole 36. In this manner, subterranean irrigation system 10 can be custom fit around existing trees and shrubs.
By placement of this soaker sheet system beneath a sod lawn, the root system of the lawn is directly irrigated from water delivered via the subterranean system, without evaporation loss and without unsightly and dangerous pop-up sprinkler heads. Moreover, any type of liquid may be delivered to the plant roots by the subterranean irrigation system, thereby avoiding air exposure of dangerous chemicals such as weed killers, insecticides, large doses of fertilizers, and the like. Subterranean application of such chemicals reduces the evaporation of the chemicals and reduces the risk of wind borne chemicals being carried to adjacent locations. Accordingly, the subterranean irrigation system of the present invention is safer for the environment and for humans that use the planted area above and near the installed irrigation system. [0022]
FIG. 4 shows a cross sectional, isometric view of another embodiment of the soaker sheet and conduit of the present invention. In this embodiment, [0023] conduit 12 is secured to top and bottom soaker sheets 16a and 16b, respectively, by adhesive 50. However, other securement means may be utilized such as heat welding methods. Rather than including a slit along the conduit, which may structurally weaken the piping, in this embodiment conduit 12 includes a plurality of holes 52 positioned along a length of the conduit. Holes 52 allow water to freely flow from an interior 54 of the conduit into cavity 16 c between top and bottom sheets 16 a and 16 b. This embodiment is preferred over the slit type embodiment shown in FIG. 1 due to the structural stability of conduit 12, as will be understood by those skilled in the art. In this preferred embodiment, conduit 12 may comprise a three-quarter inch outer diameter header pipe such that the header pipe is easily connected to the standard plumbing fittings of a water source supply line.
Holes [0024] 52 in conduit 12, also called perforations or apertures, typically extend along the header pipe from a location approximately six inches from each end of the pipe. As shown in FIG. 1, the soaker sheet edge positioned adjacent the end of header pipe 12 typically is slightly recessed inwardly from the end of the pipe, such that adjacent soaker sheets can be positioned in direct contact with one another along their edges 18, while allowing for connection of adjacent conduits at threads 14. In this manner, any number of mats can be connected together to form a relatively continuous system to cover any sized turf area. Moreover, multiple water sources may be provided throughout the system so that water pressure is maintained throughout the system. In other words, a water supply source outlet may be provided to every one thousand square foot area.
Spacing of [0025] holes 52 several inches from the end of each conduit ensures that the holes allow the flow of water into space 16 c between the upper and lower membranes 16 a and 16 b while not allowing the flow of water directly from the conduit into the ground. Accordingly, due to the recessed region 56 of the soaker sheet adjacent end 58 of conduit 12, shown in FIG. 1, the length 60 (a partial length is shown) of the header pipe typically is the same as the width 62 (a partial width is shown) of the soaker sheet, also called an irrigation mat, attached thereto. For example, in one embodiment, the irrigation system comprises an individual conduit having a length 60 of eight feet, an irrigation mat having a width 62 of eight feet measured along the conduit, and a length 64 (a partial length is shown) of twenty feet measured perpendicularly from the conduit. These large dimensions of the mat are feasible due to the relatively unrestricted fluid flow cavity area formed between the upper and lower membranes of the soaker mat.
FIG. 5 shows a top view of a [0026] subterranean irrigation system 10 including several patches therein and wherein the system has been trimmed to fit a particular sized turf area. The irrigation mat may be trimmed to fit irregular sized turf areas by simply cutting off the excess mat area from a rectangular mat, such as in region 65, and heat sealing or other wise securing the top membrane of the lower membrane together along edge of region 65. In one embodiment, the upper and lower membranes are simply folded over one another to stop the flow of fluid through the hole created by removing the excess mat area.
Still referring to FIG. 5, repair kits can be provided wherein a [0027] patch 66 may be bonded to the upper or the lower membrane to patch a hole therein. The hole 68 may have been caused by initially cutting a large hole in the mat for the placement of a post or a shrub that subsequently was removed. The hole requiring a patch may also have developed as the result of damage to the mat. Another type of patch 70 may comprise a small mat that is heat welded around three sides and is connected to a small header pipe 72, wherein header pipe 72 is connected to a fitting 74 on the initially installed system. The hole 76 over which patch 70 is placed typically is heat sealed around its edge prior to placing patch 70 over the hole. Locating such damaged areas of system 10 can be accomplished by injecting a brightly colored liquid or foaming dye into the system.
In the preferred embodiment, [0028] conduits 30 are manufactured of non-metallic material such as PVC piping, wherein fittings 32 may be manufactured of metal or may have a metal tab secured thereto, so that a metal detector can be used to located the installed, subterranean fittings.
In the above description numerous details have been set forth in order to provide a more through understanding of the present invention. It will be obvious, however, to one skilled in the art that the present invention may be practiced using other equivalent designs. [0029]

Claims

I claim:

1. A subterranean irrigation system comprising:

a conduit adapted for being secured to a fluid source and including a fluid flow aperture positioned therein;

a first permeable membrane secured to said conduit and defining an exposed top, planar surface of said irrigation system; and

a second permeable membrane secured directly to said first permeable membrane and to said conduit and defining an exposed bottom, planar surface of said irrigation system,

wherein said first and second permeable membranes define an enclosed, hollow cavity therebetween wherein said fluid flow aperture communicates with said enclosed, hollow cavity.

2. The irrigation system of claim 1 wherein said first permeable membrane includes a plurality of apertures extending there through, wherein said second permeable membrane includes a plurality of apertures extending there through and being positioned aligned with corresponding ones of said plurality of apertures of said first permeable membrane, and wherein said second permeable membrane is secured to said first permeable membrane around each of said plurality of apertures of said first permeable membrane so that said irrigation system defines a pattern of apertures extending there through.

3. The irrigation system of claim 1 wherein said fluid flow aperture comprises a slit extending substantially along a length of said conduit.

4. The irrigation system of claim 1 wherein said fluid flow aperture comprises a plurality of apertures extending substantially along a length of said conduit.

5. The irrigation system of claim 1 wherein said first and second permeable membranes are each manufactured of a material chosen from the group consisting of a polysulfone, a cellulose material, a polyolefin, and a polyetholene.

6. The irrigation system of claim 1 wherein said first and second permeable membranes define a first sheet, and wherein said system comprises a plurality of sheets operatively connected to said conduit.

7. The irrigation system of claim 1 wherein said pattern of apertures comprises a waffle type pattern.

8. The irrigation system of claim 1 wherein said conduit comprises a rigid cylindrical member.

9. The irrigation system of claim 1 wherein said conduit is manufactured of a material chosen from the group consisting of metal, polyvinyl chloride, and plastic.

10. The irrigation system of claim 2 wherein said enclosed, hollow cavity defines multiple channels of fluid flow extending around said pattern of apertures.

11. A subterranean, planar irrigation system comprising:

a fluid header adapted for being secured to a fluid source and including a fluid outlet positioned therein;

a first permeable membrane secured to said header and defining an exposed first, planar surface of said irrigation system; and

a second membrane secured directly to said first permeable membrane and to said header and defining an exposed second, planar surface of said irrigation system,

wherein said first permeable membrane includes a plurality of apertures extending there through, wherein said second membrane includes a plurality of apertures extending there through and being positioned aligned with corresponding ones of said plurality of apertures of said first permeable membrane, and wherein said second membrane is secured to said first permeable membrane around each of said plurality of apertures of said first permeable membrane so that said irrigation system defines a pattern of apertures extending there through.

12. The irrigation system of claim 11 wherein said first and second membranes define an open space there between and wherein said fluid outlet communicates with said open space.

13. The irrigation system of claim 11 wherein said first and second membranes define a soaker sheet, and wherein said soaker sheet includes an enlarged aperture extending there through and being adapted for placement around a shrub.

14. The irrigation system of claim 11 wherein said second membrane is secured to said first permeable membrane by heat welding along at least a portion of an edge of said second membrane.

15. The irrigation system of claim 11 wherein said first permeable membrane includes pores therein, wherein said pores have an average diameter size in a range of 10 nm to 10,000 nm and wherein said first permeable membrane has a width, a length and a thickness, and wherein said thickness is less than ten times smaller than said width and said length.

16. The irrigation system of claim 11 wherein said first and second membranes define a soaker sheet, and wherein said soaker sheet is trimmed along an edge to have a predetermined shape.

17. The irrigation system of claim 11 wherein said system comprises a plurality of first permeable membranes secured to corresponding ones of a plurality of second membranes, and wherein said system further comprises a patch positioned on at least one of said first membranes.

18. The irrigation system of claim 11 wherein said patch is connected directly to said fluid header.

19. A method of irrigating a lawn area, comprising the steps of:

providing an irrigation device including a first permeable planar membrane and a second permeable planar membrane wherein said first and second membranes are secured together to define a hollow cavity there between;

placing said irrigation device on a ground surface;

covering said irrigation device with a living plant ground cover;

providing a fluid flow to said hollow cavity such that the fluid flow passes through said first and second permeable membranes to contact said ground surface and said living plant ground cover.

20. The method of claim 19 wherein said irrigation device comprises a plurality of holes extending there through, said holes adapted to allow unhindered root growth through said irrigation device.

21. The method of claim 19 wherein said living plant ground cover comprises dirt and grass seed therein.

22. The irrigation system of claim 11 wherein said second membrane is secured to said first permeable membrane by adhesive along at least a portion of an edge of said second membrane.