Patent Publication Number: US-11047101-B2

Title: Low-profile fluid conduit/collector and system

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
     This application is a continuation-in-part of U.S. Non-Provisional patent application Ser. No. 16/190,917 filed on Nov. 14, 2018, which claims the benefit of U.S. Provisional Patent Application Ser. No. 62/585,586 filed on Nov. 14, 2017, the entirety of which is hereby incorporated herein by reference for all purposes. 
    
    
     BACKGROUND 
     Technical Field 
     In many instances, a fluid needs to be moved over a large distance or collected over a large area. For example, as waste material decomposes in a landfill, it gives off various gases. In the past, it has been known to use pumps, piping, and wellheads to extract the gases from the landfill and collect the same. Such wellheads are often spaced about one per acre in a grid pattern. Such systems of collecting the gases can be shut down by many factors, including power failures. To prevent the undesirable build-up of such gases in the event of non-operation of the extraction system, it has often been known to employ a grid pattern of vents spaced between the extraction wellheads, often at the same one per acre density. 
     As described in published U.S. Patent Application Number 20060034664, conventional gas extraction wells at landfills often involve deep wells attached to a network of pipes and a gas pump (blower) that applies vacuum (negative pressure) to extract the gas from the stored waste as the waste decomposes. 
     A prior art arrangement according to the above published patent application is shown in  FIG. 1 . Landfill  1  containing waste  2  generates biogas (biogas flows shown by the arrows). Biogas is collected and extracted through a well  3 . The well  3  includes a gas-collecting well screen  16  and a gas-impermeable conduit  17  linking the well screen to the surface to draw biogas from the wellhead to the surface. Overlaying the majority of the waste  2  is a gas-permeable layer  5 . The term “wellhead” refers to a portion of the gas-extraction well from which gas can be extracted. The well often includes a section of pipe having slots or other gas-flow apertures cut in it, referred to as a “well screen”. Often, the well screen is also surrounded with gravel. 
     The gas-permeable layer is typically composed of a conductive porous matrix with gas flow paths. Often it is composed of rigid or semi-rigid particles of a large enough size to leave a significant void volume between particles. For instance, the gas-permeable layer may contain sand, gravel, wood chips, or shredded tires. Above the gas-permeable layer is a gas-containment layer  7 . Biogas that rises from the landfill reaches the gas-permeable layer where it is trapped by the overlying gas-containment layer  7 . The biogas migrates horizontally in the gas-permeable layer until it comes close to a well. Gas extraction from the well creates a vacuum that draws gas into the well. This vacuum draws biogas from the overlying gas-permeable layer down through the waste mass of the landfill to reach the well. 
     The area immediately beneath the gas-permeable high conductivity layer  5  through which a substantial fraction of the biogas from the gas-permeable layer passes as it travels to the gas-collection wellhead is the entrainment zone  9 . On its passage through the waste  2 , the gas from the gas-permeable layer mixes with biogas produced in the waste mass that has not gone through the gas-permeable layer. This helps to give a consistent content to the biogas that is withdrawn from the well. If gas is withdrawn directly from the gas-permeable conductive layer, the gas composition will vary more dramatically over time, sometimes containing a high air content and sometimes not. It is sometimes desirable to place an even more impermeable layer, such as geomembrane  15 , directly over the zone of entrainment of gas from the permeable layer that is created by the deep well. Moreover, sometimes the entire landfill is covered with such a membrane. 
       FIG. 2  shows another prior art arrangement, this time showing a more shallow wellhead  26  used to withdraw near-surface or sub-surface gas from beneath a membrane M capping a waste W. The wellhead  26  is attached to an above-ground conduit by way of a vertical pipe. 
       FIG. 3  shows another prior art arrangement, this time depicting a landfill with multiple wellheads  30  used to withdraw near-surface or sub-surface gas from beneath the surface. The wellheads  30  are attached to an above-ground vent  31 . 
       FIG. 4  shows another prior art arrangement similar to that in  FIG. 2 , this time showing a field of wellheads  40  spaced to extract the gases from a landfill and collect the same. Such wellheads are often spaced about one per acre. 
     SUMMARY OF THE INVENTION 
     In an example form, the invention relates to a low-profile fluid collection conduit, such as for use at landfills and the like. In one example, the fluid collection conduit includes an elongate outer cover having an upper portion and a lower portion generally opposite the upper portion, with the outer cover being much wider than it is tall and defining an interior volume. A rigid spacer is fitted within the interior volume of the elongate outer cover, with the spacer allowing the majority of the interior volume to be unfilled so as to permit the flow of fluid along and within the elongate outer cover. 
     Optionally, the elongate outer cover is non-perforated. Alternatively, the elongate outer cover can be perforated. 
     Preferably, the elongate outer cover is much thinner than it is tall and is flexible. Preferably, the elongate outer cover is made from one or more polymers. 
     Preferably, the elongate outer cover has an aspect ratio of width to height of more than 10:1. More preferably, the elongate outer cover has an aspect ratio of width to height of more than 20:1. In a preferred example, the elongate outer cover has an aspect ratio of width to height of more than 50:1. 
     Optionally, the elongate outer cover has a height of between about ½ inch and about 3 inches. More preferably, the elongate outer cover has a height of about one inch. Optionally, the elongate cover can have a width of between about one foot and about 8 feet. 
     In another example form, the present invention relates to a low-profile subsurface fluid conveyance conduit grid. The fluid conveyance grid includes at least one high-volume, low-profile fluid trunk conduit. It also includes at least two medium-volume, low-profile fluid branch conduits connected to and feeding into the at least one high-volume, low profile trunk conduit. Further, it includes at least four lower-volume, low-profile collector conduits connected to and feeding into the at least two medium-volume, low profile branch conduits, with each branch conduit being connected to at least two of the collector conduits. With this construction, surficial fluid can be drawn into the smaller collector conduits, gathered into the somewhat larger branch conduits, and finally into the trunk conduit. At least one of the trunk conduit, the branch conduits, and the collector conduits includes an elongate outer cover having an upper portion and a lower portion generally opposite the upper portion, with the outer cover being much wider than it is tall and defining an interior volume and including an elongate rigid spacer fitted within the interior volume of the elongate outer cover, the elongate spacer allowing the majority of the interior volume to be unfilled so as to permit the flow of fluid along and within the elongate outer cover. 
     Optionally, the fluid conveyed within the conveyance conduit grid includes at least some water. Optionally, the fluid includes surficial landfill gas. 
     Optionally, the grid is adapted for use under the surface of a landfill, with the grid further comprising an impermeable membrane positioned under the surface of the landfill and over the conduits. 
     Preferably, the grid is substantially cruciform in shape and at intersections of various conduits an adapter T or cross is provided. Optionally, the adapter T or cross has an upper opening and is provided with a cover for covering the upper opening. 
     Preferably, the grid includes at least one trunk conduit and the at least two branch conduits each comprise an elongate, non-perforated outer cover. Optionally, the at least four collector conduits each comprise an elongate perforated outer cover. 
     Preferably, the elongate outer cover comprises a polymer. 
     Preferably, the collector conduits have an aspect ratio of width to height of more than 10:1. More preferably, the aspect ratio is more than 20:1. Indeed, even an aspect ratio of more than 50:1 can be achieved. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWING FIGURES 
         FIG. 1  is a schematic illustration of a first prior art wellhead for extracting sub-surface gas from a waste landfill. 
         FIG. 2  is a schematic illustration of a second prior art wellhead for extracting sub-surface gas from a waste landfill. 
         FIG. 3  is a schematic illustration of a prior art waste landfill with multiple wellheads for extracting sub-surface gas from a waste landfill. 
         FIG. 4  is a schematic illustration of a prior art waste landfill with multiple wellheads for extracting sub-surface gas from a waste landfill. 
         FIG. 5A  is a schematic, sectional view of a low-profile fluid collection conduit for extracting and/or conveying sub-surface gas from a waste landfill according to a preferred example form of the present invention. 
         FIG. 5B  is a schematic, perspective, partially cut-away view of a low-profile fluid collection conduit of  FIG. 5A  for extracting and/or conveying sub-surface gas from a waste landfill according to a preferred example form of the present invention. 
         FIG. 5C  is a schematic, sectional view of a low-profile fluid collection conduit of  FIG. 5A  for extracting and/or conveying sub-surface gas from a waste landfill according to another preferred example form of the present invention. 
         FIG. 5D  is a schematic, perspective, partially cut-away view of a low-profile fluid collection conduit of  FIG. 5C  for extracting and/or conveying sub-surface gas from a waste landfill according to another preferred example form of the present invention. 
         FIG. 6A  is a schematic, sectional view of a low-profile fluid collection conduit for extracting and/or conveying sub-surface gas from a waste landfill according to a preferred example form of the present invention. 
         FIG. 6B  is a schematic plan view of a conduit of the present invention. 
         FIGS. 7A and 7B  are schematic, sectional and plan views of a junction connector for connecting conduits in a cruciform pattern. 
         FIG. 8  is a schematic view of a collection and conveyance grid for extracting and/or conveying sub-surface gas from a waste landfill. 
         FIG. 9  is a schematic view of the collection and conveyance grid for extracting and/or conveying sub-surface gas from a waste landfill of  FIG. 8 , shown in conjunction with a three-dimensional landfill site. 
         FIG. 10  is a schematic view of another example collection and conveyance grid for extracting and/or conveying sub-surface gas from a waste landfill. 
         FIG. 11  is a schematic view of a portion of the example collection and conveyance grid of  FIG. 10 . 
     
    
    
     DESCRIPTION OF EXAMPLE EMBODIMENTS 
     In an example form, the invention relates to a low-profile fluid collection or conveyance conduit, such as for use at landfills and the like. In another example form, the present invention relates to a low-profile subsurface fluid conveyance conduit grid. Examples of these follow. 
     A Low-Profile Fluid Conduit and/or Collector and Related Components 
     In one example form, the present invention relates to a sub-surface collection or conveyance fluid conduit  50  for collecting and/or conveying sub-surface gas and the like from near the surface of landfills, typically for use with a geomembrane for capping a waste field. The geomembrane is generally impermeable to fluids in order to contain or cap the waste below, and thereby restrict the sub-surface gas from flowing into the atmosphere and to restrict atmospheric air from flowing into the waste below the geomembrane. 
       FIG. 5A  is a schematic, sectional view of the conduit  50  for extracting and/or conveying sub-surface gas from a waste landfill according to a preferred example embodiment of the present invention. The conduit  50  includes a generally box-like outer casing  52  forming an enclosure with a substantially flat upper portion  53 , a flat lower portion  54 , and defining an interior volume  55 . The casing  52  can include, or not include, perforations formed therein to provide for the admission of sub-surface gas into the interior volume, as desired. Preferably, the outer casing  52  comprises a fluid-impermeable membrane and the interior volume  55  provides an inner gas or fluid flow channel. Optionally, an upper orifice or inlet opening  58  is formed in the upper portion  53  of the enclosure or casing  52 . 
     Preferably, the outer casing  52  is thin, and forms a conduit with a large aspect ratio of width to height. Also, the conduit  50  is adapted to be quite long and the interior volume is supported and maintained with the aid of a reinforcement corrugation  100 . The corrugation  100  serves to provide structural rigidity and integrity against collapse, in order to maintain an open flow volume, despite forces that may otherwise tend to crush the casing  52 . 
     Thus, in one form the low-profile fluid collection conduit  50  is adapted for use at landfills and the like. In one example, the fluid collection conduit  50  includes an elongate outer cover  52  having an upper portion  53  and a lower portion  54  generally opposite the upper portion, with the outer cover  52  being much wider than it is tall and defining an interior volume  55 . An elongate rigid spacer  100  is fitted within the interior volume  55  of the elongate outer cover  52 , with the elongate spacer  100  allowing the majority of the interior volume  55  to be unfilled so as to permit the flow of fluid along and within the elongate outer cover  52 . 
     Optionally, the elongate outer cover  52  is non-perforated. Alternatively, the elongate outer cover  52  can be perforated (see perforations  56  in cover  52  as depicted in  FIG. 5B ). 
     Preferably, the elongate outer cover  52  is much thinner than it is tall and is flexible. Preferably, the elongate outer cover is made from one or more polymers. 
     Preferably, the elongate outer cover  52  has an aspect ratio of width to height of more than 10:1. More preferably, the elongate outer cover  52  has an aspect ratio of width to height of more than 20:1. In a preferred example, the elongate outer cover  52  has an aspect ratio of width to height of more than 50:1. 
     Optionally, the elongate outer cover  52  has a height of between about ½ inch and about 3 inches. More preferably, the elongate outer cover has a height of about one inch. Optionally, the elongate cover  50  can have a width of between about one foot and about 8 feet. So for example, the cover  50  can be a foot wide, two feet wide, 3.5 feet wide, 4 feet wide, 6 feet wide, etc. 
     While the outer cover  52  can be made of flexible or rigid materials, the spacer  100  should be sufficiently rigid to maintain the shape of the conduit  50 . The conduit  50  can be made much longer than the spacer  100  such that several or many such spacers  100  are employed along the length of the conduit  50 . By using many spacers  100  of shorter lengths than the conduit  50 , the conduit can be assembled with the spacers inside of it and then rolled up for convenient transport. The rolled-up assembly then can be unrolled at the installation site. The rigid spacer  100  can be made as long as the conduit  50 , but at the expense of decreasing the flexibility of the assembly, making rolling it up for transport and unrolling it at the jobsite more difficult or impractical. 
     Preferably, a collection disk or cover  150  is provided over the aperture or opening  58  for shrouding the orifice/opening against becoming clogged with debris. The collection disk  150  is formed similarly to the conduit  50 , with a thin upper covering  151  and a rigid spacer  152  supporting the thin upper cover  151 . In this way, the thin upper cover  151  can be fabricated as a flexible element or as a rigid element, as desired. 
       FIG. 5B  is a schematic, perspective, partially cut-away view of a low-profile fluid collection conduit of  FIG. 5A  for extracting and/or conveying sub-surface gas from a waste landfill according to a preferred example form of the present invention. As shown in this example, the fluid collection conduit  50  includes an elongate outer cover  52  having an upper portion  53  and a lower portion  54  generally opposite the upper portion. The outer cover  52  has a width W which is much wider than the height H of the cover  52 . The aspect ratio between the width and the height is on the order of a magnitude and can even be approach two orders of magnitude. As noted earlier, the length L can be hundreds of feet. The elongate rigid spacer  100  fitted within the interior volume of the elongate outer cover  52  in this example takes the form of an elongate ribbed element, with ribs  101 ,  102 ,  103 , etc., extending upwardly from a base plate or substrate  110 , with the elongate spacer  100  allowing the majority of the interior volume  55  to be unfilled so as to permit the flow of fluid along and within the elongate outer cover  52 . The ribs can be hollow or can be solid, as desired. As shown in this figure, the cover  52  can be provided with a large number of perforations, such as perforations  56  to allow gas/fluids to be drawn into the interior volume  55 . 
       FIG. 5C  is a schematic, sectional view of a low-profile fluid collection conduit of  FIG. 5A  for extracting and/or conveying sub-surface gas from a waste landfill according to another preferred example form of the present invention. In this example, the elongate rigid spacer  200  fitted within the interior volume of the elongate outer cover  52  in this example takes the form of an elongate dimpled element, with dimples or cones, such as cone  201 , extending upwardly from a base plate or substrate  210 , with the elongate spacer  100  allowing the majority of the interior volume  55  to be unfilled so as to permit the flow of fluid along and within the elongate outer cover  52 . The cones, such as cone  201 , are frusto-conical in shape. But a wide variety of shapes can be employed, such as hemispherical nubs, cylinders, pyramids, etc. 
       FIG. 5D  is a schematic, perspective, partially cut-away view of a low-profile fluid collection conduit of  FIG. 5C  for extracting and/or conveying sub-surface gas from a waste landfill according to another preferred example form of the present invention. In this example the cones can be seen to include a large number of cones, including cones  201 ,  202 ,  203 ,  204 ,  205 , etc., extending upwardly from the base plate or substrate  210 , 
       FIG. 5C  and  FIG. 5D  show how the first end portion  57  of the cover  52  overlies and abuts the opposite (second) end portion  59  of the cover  52 . Indeed, these two end portions are secured to one another, as by heat bonding, adhesives, chemical bonding, etc. 
       FIG. 6A  shows the conduit  50  in a plan view with a gas collection disk  150  thereupon positioned over a gas aperture  58 . As depicted rather schematically, the length of the conduit  50  can be on the order of 200 feet, while the width of the conduit  50  would typically be on the order of 1 foot. The collection disk  150  is a low profile, high gas flow capacity structure. The collection disk  150  is generally a 4 inch (round or square) diameter and is placed over the collection orifice  58  to ensure gas flow into the system. 
     Preferably, the components of this rather flat pipe/conduit provide a gas collection lateral which is a low profile (flat pipe) high gas flow capacity structure encased within an impermeable membrane (hdpe, Ilpe, pvc, etc. . . . ). The unit is utilized as both a gas conveyance and collection point. The gas collection lateral is generally, but not necessarily, 200 ft. in length with a 1 inch height and widths from 1 to 2 foot. The lateral is sealed on one end with an orifice cut into the membrane and a collection disk placed over the orifice to ensure gas flow into the orifice and lateral. The body of the lateral can be fluid-impermeable with a collection orifice on one end and an opening on the other for installation into a reducer tee. 
       FIG. 6B  shows a straight run section of conduit which can be inserted into a reducer tee at one end  61  and into a reducer tee or a pipe transition at the opposite end  62 . This can be a low profile, high gas flow capacity structure encased within an impermeable membrane (hdpe, Ilpe, pvc, etc) and utilized for gas conveyance from one point (such as a reducer tee) to another. The sub-header (flat conduit) is generally 200 ft. in length with a 1 inch height and varying widths (8′, 6.5′, 4′ and 2′) depending upon gas flow capacity design requirements for the specific section of sub-header. Of course, these dimensions can be varied as desired. But such a structure allows for these advantageous dimensions in which a long run conduit can be very wide, very short in height and very long in length. While the body of the sub-header (flat pipe) is generally impermeable, the ends are left open for installation into the reducer tee. 
       FIGS. 7A and 7B  are schematic, sectional and plan views of a junction connector for connecting conduits in a cruciform pattern. This junction connector  70  comprises a reducer tee as a low profile, high gas flow capacity structure (spacer  78 ) encased within an impermeable membrane  72  (hdpe, Ilpe, pvc, etc.) and utilized as both a gas collection point and an intersecting point between sub-headers  50  and Gas collection laterals  60 . The reducer tee  70  in an example form is 1 inch in height and designed to receive two gas laterals (1 to 2 ft in width) along with one or two gas collection sub-headers. Each reducer tee is sized according to the subheader width requirements (flow capacity design) for the specific location in the field. 
     The above-described components can be assembled and secured to one another by being welded, glued, taped, clamped or otherwise physically attached to one another, or by other means. 
     The sub-surface gas to be collected and withdrawn with the present invention can be any of several sub-surface gases, such as natural gas. The fluid collected and conveyed can be gaseous or liquid. 
     A Low-Profile Subsurface Fluid Conveyance or Collection Conduit Grid 
     In another example form as shown in  FIGS. 8-11 , the present invention relates to a low-profile subsurface fluid conveyance conduit grid  80 . The fluid conveyance grid includes at least one high-volume, low-profile fluid trunk conduit  81 . It also includes at least two medium-volume, low-profile fluid branch conduits  82  connected to and feeding into the at least one high-volume, low profile trunk conduit  81 . Further, it includes at least four lower-volume, low-profile collector conduits  83  connected to and feeding into the at least two medium-volume, low profile branch conduits  82 , with each branch conduit  82  being connected to at least two of the collector conduits  83 . With this construction, surficial fluid can be drawn into the smaller collector conduits  83 , gathered into the somewhat larger branch conduits  82 , and finally into the trunk conduit  81 . 
     At least one of the trunk conduit  81 , the branch conduits  82 , and the collector conduits  83  includes an elongate outer cover having an upper portion and a lower portion generally opposite the upper portion, with the outer cover being much wider than it is tall and defining an interior volume and including an elongate rigid spacer fitted within the interior volume of the elongate outer cover, the elongate spacer allowing the majority of the interior volume to be unfilled so as to permit the flow of fluid along and within the elongate outer cover. 
     Optionally, the fluid conveyed within the conveyance conduit grid includes at least some water. Optionally, the fluid includes surficial landfill gas. Optionally, the grid is adapted for use under the surface of a landfill, with the grid further comprising an impermeable membrane positioned under the surface of the landfill and over the conduits. 
     Preferably, the grid is substantially cruciform in shape and at intersections of various conduits an adapter T or cross is provided. Optionally, the adapter T or cross has an upper opening and is provided with a cover for covering the upper opening. 
     Preferably, the grid includes at least one trunk conduit and the at least two branch conduits each comprise an elongate, non-perforated outer cover. Optionally, the at least four collector conduits each comprise an elongate perforated outer cover. 
     Preferably, the elongate outer cover comprises a polymer. 
     Preferably, the collector conduits have an aspect ratio of width to height of more than 10:1. More preferably, the aspect ratio is more than 20:1. Indeed, even an aspect ratio of more than 50:1 can be achieved. 
     The system is similar to a surficial gas collection system in that it also works with the landfill&#39;s continual gas generation and resulting internal positive pressures to push gas to the surface where it is trapped below an impermeable membrane. However, the present gas collection system is differentiated from all other gas collection methods by utilizing a sealed flat piping network with collection points (collection disks) below the membrane (final closure, interim) at locations determined by landfill gas generation modeling. 
     The system design, coupled with a membrane cover, creates a superior barrier and conveyance system for fugitive emissions. The radius of influence of the system can be every square foot between the waste mass and the atmosphere. 
     The system requires no drilling (wells), no trenching (buried piping), and no above-ground piping. It also produces no condensate, and allows for a significant reduction in effort in monitoring of collection points. 
     The system is a designed and manufactured solution that provides for an easy and quick installation of a gas collection system that requires reduced capital costs, lowered O&amp;M costs, stability in gas collection management along with a significant reduction in condensate generation. 
     It is to be understood that this invention is not limited to the specific devices, methods, conditions, or parameters described and/or shown herein, and that the terminology used herein is for the purpose of describing particular embodiments by way of example only. Thus, the terminology is intended to be broadly construed and is not intended to be limiting of the claimed invention. For example, as used in the specification including the appended claims, the singular forms “a,” “an,” and “one” include the plural, the term “or” means “and/or,” and reference to a particular numerical value includes at least that particular value, unless the context clearly dictates otherwise. In addition, any methods described herein are not intended to be limited to the sequence of steps described but can be carried out in other sequences, unless expressly stated otherwise herein. 
     While the invention has been shown and described in exemplary forms, it will be apparent to those skilled in the art that many modifications, additions, and deletions can be made therein without departing from the spirit and scope of the invention as defined by the following claims.