Patent Abstract:
A leaching chamber having an arch-shaped cross-section, a pair of contiguously molded, opposing end walls, and alternating peak and valley corrugations along its length, is provided interior chambers and fluid communication openings along the base on each extending side of the chamber. Formed within the chamber at locations corresponding to each peak corrugation, an inner wall is attached to an interior surface and extends substantially within the peak corrugation to the base of the chamber. An aperture is formed in both the inner wall and in the opposing outer wall of the chamber, enabling fluid communication through the interior chamber—and thus into and out from the interior of the leaching chamber itself.

Full Description:
CROSS-REFERENCE TO RELATED APPLICATION 
       [0001]    This application claims the benefit of U.S. Provisional Patent Application Ser. No. 60/908,933, filed Mar. 29, 2007. 
     
    
     TECHNICAL FIELD 
       [0002]    The present invention relates to leaching chambers for receiving and dispersing water and wastewater when buried in the soil, and more particularly, to such pre-molded leaching chambers as are corrugated and arch-shaped in cross-section with contiguously molded end walls, and lateral interior chambers having fluid communication openings at the chamber base. 
       BACKGROUND ART 
       [0003]    The use of above-ground watering systems, particularly in dry climates such as the southwestern regions of the United States and in the Mediterranean regions of Europe, the Middle East, and Africa, brings with it a list of known problems. In addition to water loss through evaporation during the watering process, if watering is provided too lightly, shallow plant rooting results. Additionally, repeated surface applications of water tend to produce the buildup of mineral salts, which are detrimental to healthy plant growth. 
         [0004]    As increasing population pressures result in greater demands upon fresh water supplies, the benefits of underground irrigation have become increasingly attractive. Such systems place water almost directly into the plant root zone and eliminate evaporative water losses. Their protected location also minimizes the risk of damage from surface activities. 
         [0005]    The subsurface fluid distribution system described in my previous patent, Sipaila, U.S. Pat. No. 5,921,711, provides such a subterranean system with reserve fluid storage capacity to maintain soil dampness as well as replace water taken up by plants. As used in a passive subsurface irrigation system, capillary physics and gravity are relied upon to deliver water and nutrients to plants through an interconnected series of chambers and pans. Such systems are capable of reducing the amount of irrigation water required by 50-80% over the more traditional above-ground systems. 
         [0006]    As is typical for such systems, the leaching chamber has sloped sidewalls that extend to a curved, arched top. When installed, such extended-arch chambers must resist both top and side loadings. The slots in the sidewalls permit the transport of water from within, but act to weaken the sidewall structure. 
         [0007]    While thickening the sidewall would provide additional strength, it also results in an increase in the amount of material required—which is a polyolefin, and is thus tied to the rising cost of petrochemicals. In addition, the added weight of the resulting product adds to the cost of transporting the chambers to the installation site. Also, while it is vital that such chambers are able to efficiently stack for transport, the stacking of such bulked-up chamber walls must not result in forcing the sidewalls out, resulting in the overall flattening and weakening of the arch-shaped chamber. 
         [0008]    It thus is desirable to provide additional solutions that increase the structural integrity of the arched chamber in a manner that enhances the operational efficiency and is not negated by increased transportation costs or product damage during shipment. 
       DISCLOSURE OF THE INVENTION  
       [0009]    These and other objects are achieved by providing a pre-molded leaching chamber of arch-shaped cross-section, having a pair of contiguously molded, opposing end walls, alternating peak and valley corrugations along its length, and interior chambers formed at the base of the chamber at each peak corrugation providing fluid communication between the exterior and interior of the leaching chamber. The interior chambers are formed by an inner wall attached to an interior surface of the leaching chamber and extending substantially within the peak corrugation, spaced from the outer wall, to the base of the chamber. Vertically off-set apertures are formed in the inner wall and in the opposing outer wall, enabling fluid flow within the inner chamber. 
         [0010]    A leaching chamber comprising: a corrugated outer shell extending along a longitudinal axis in a manner defining alternating peak corrugations and valley corrugations, said corrugated outer shell having an arch-shaped cross-section with a pair of opposed lateral end walls formed therein and no floor; and a plurality of inner walls attached to an interior wall of said corrugated outer shell, each at a location within a separate interior valley formed in said interior wall, with each of said interior valleys corresponding to a peak corrugation formed in said outer shell, said plurality of inner walls extending from a location of attachment to said interior wall to a terminus of a respective one of said interior valleys, each of said plurality of inner walls extending in a manner inwardly spaced from said corrugated outer shell to define a plurality of interior chambers, wherein each of the plurality of interior chambers has an inner wall aperture formed in said respective inner wall and an outer shell aperture formed in the corrugated outer shell. 
         [0011]    A leaching chamber having an arch-shaped cross-section and alternating peak corrugations and valley corrugations along its length comprising: a pair of opposed end walls attached to said leaching chamber at opposite ends thereof, each of said pair of opposed end walls having a connecting pipe aperture formed therein; and a plurality of inner walls attached to an inner surface of said leaching chamber and extending towards a base of said leaching chamber, each of said plurality of inner walls extending in a spaced-apart manner from a separate one of such adjacent lateral wall segment of said leaching chamber as defines one of said alternating peak corrugations, each of said plurality of inner walls and each of said respective adjacent lateral wall segments define an individual interior chamber formed therebetween, each of said inner walls and said adjacent lateral wall segments have an aperture formed therein, whereby fluid communication between an interior of said leaching chamber and an outer environment of said leaching chamber may occur through each of said plurality of interior chambers. 
         [0012]    These and various other advantages and features of the present invention are pointed out with particularity in the claims. Reference should also be had to the drawings which form a further part hereof, as well as to the accompanying descriptive matter in which are illustrated and described in various examples of with the invention. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0013]      FIG. 1  is a partial top perspective view of a leaching chamber in accordance with the present invention. 
           [0014]      FIG. 2  is a partial bottom perspective view of the leach chamber of  FIG. 1 . 
           [0015]      FIG. 3  is a cross-sectional view, with portions shown in phantom, taken along line  3 - 3  of  FIG. 1 . 
           [0016]      FIG. 4  is a partial cross-sectional view taken along line  4 - 4  of  FIG. 1 . 
           [0017]      FIG. 5  is a partial cross-sectional view taken along line  5 - 5  of  FIG. 1 . 
           [0018]      FIG. 6  is a partially exploded cross-sectional view of a plurality of stacked leaching chambers, the cross-sectional views of each of the chambers taken along line  3 - 3  of  FIG. 1 . 
           [0019]      FIG. 7  is a partial cross-sectional view showing a connecting pipe enabling fluid communication between an adjacent pair of leaching chambers. 
           [0020]      FIG. 8  is a cross-sectional view, similar to  FIG. 3 , with portions shown in phantom, taken along line  3 - 3  of  FIG. 1  showing an alternative embodiment of the present invention. 
       
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
       [0021]    Reference is now made to the drawings wherein like numerals refer to like parts throughout. In  FIG. 1 , a leaching chamber  10  includes a corrugated outer shell  14  and an end wall  18 . A connecting pipe aperture  22  is centrally located in the end wall  18 , and is appropriately sized to receive a connector pipe that extends between and is used to connect adjacent leaching chambers (not shown in the Figures). 
         [0022]    The end wall  18  also includes a pair of outer fluting extrusions  26  that are centrally located and extend between the connecting pipe aperture  22  and a base  24  of the end wall  18 . Functioning as stiffeners, the outer fluting extrusions  26 , together with a single inner fluting extrusion  28  (see  FIG. 3 ), provide three-dimensional structural support to the end wall  18  without compromising the extrusion process of fabricating the leaching chamber  10 . 
         [0023]    Additional structural support is provided by a footing flange  32  that is attached to and extends from the base  24  of the end wall  18 . A plurality of triangular braces  34  are arranged in a spaced-apart manner along the footing flange  32  to provide lateral rigidity to the flat end wall  18 . Each of these end wall reinforcement features may be fabricated as part of the extrusion process used to form the end wall and corrugated outer shell of the leaching chamber  10 . 
         [0024]    A support footing  42  extends along each lateral terminus of the corrugated outer shell  14 , providing a stable support base when the leaching chamber  10  is positioned for use in an irrigation system or drainage system as well as when it is stacked for transport. In regard to the latter function, a stacking nub  46  is formed on and projects at a lateral location on the corrugated outer shell  14 . The stacking nubs  46  are positioned in a manner that provides support to the support footing  42  when a plurality of leaching chambers  10  are vertically stacked (see  FIGS. 3 and 6 ). 
         [0025]    The corrugated outer shell  14  exhibits a repeating outer pattern of peak corrugations and valley corrugations (ridges and grooves), with these outer peaks and valleys inversely corresponding to peaks and valleys from a perspective within the leaching chamber  10  (see  FIG. 2 ). An inner wall  52  is formed within each of the interior valleys, and extends from the support footing  42  to a fused attachment seam  54  formed in the corrugated outer shell  14 . 
         [0026]    The inner wall is inwardly spaced from the corrugated outer shell  14  at its location of attachment to the support footing  42 , forming an interior chamber  58  (see  FIG. 4 ). A plurality of such interior chambers  58  are formed in, and laterally extend along, in a spaced-apart manner, both longitudinal sides of the leaching chamber  10 . Each of the interior chambers  58  is provided an inner wall aperture  62  formed in the inner wall  52  and an outer shell aperture  64  that is formed in the corrugated outer shell  14 . 
         [0027]    In a presently preferred embodiment, the inner wall aperture  62  and the outer shell aperture  64  are vertically off-set, with the outer shell aperture  64  at a vertical location that is lower than the inner wall aperture  62  when the leaching chamber  10  is in operation. As is best shown in  FIG. 4 , this vertical off-set inhibits the reverse flow of particulate matter from the outer environment through the interior chamber  58 , which would otherwise result in the fouling of the primary chamber of the leaching chamber  10 . 
         [0028]    As discussed previously, most applications require a series of leaching chambers  10  that are connected together using discrete connecting pipes, with each pipe extending between opposing connecting pipe apertures to connect together adjoining leaching chambers  10 . It is essential that each leaching chamber  10  remain in fluid communication with any adjoining leaching chamber  10  with which it shares a connecting pipe  70  (see  FIG. 7 ). 
         [0029]    As is depicted in both  FIGS. 5 and 7 , a stop nub  68  is formed in an interior wall of the corrugated outer shell  14  and extends downwardly to provide a surface against which an end of the connecting pipe  70  can rest. The stop nub  68  resists any further inward migration of the connecting pipe  70  after installation. Such longitudinal movement—in either direction, could result in the dislodgement of the connecting pipe  70  from an adjoining leaching chamber  10 , which in turn would abruptly end or severely impair the fluid communication therebetween. The distance between the adjacent, connected leaching chambers  10  can be as short as a few inches or as long as ten feet, depending upon the particular application. Separation in typical athletic fields is about one foot between the end walls  18 . 
         [0030]    In an alternative embodiment of the present invention shown in  FIG. 8 , the connecting pipe aperture  22  has been repositioned close to the base  24  of the end wall  18 . Under this embodiment drainage occurs at the bottom of the leaching chamber  10 , and no or only a very slight amount of water remains within the leaching chamber  10 —unlike the reservoir of water created within the leaching chamber  10  when the connecting pipe aperture  22  is positioned at a higher location on the end wall  18  (see  FIG. 3 ). 
         [0031]    The embodiment of  FIG. 8  is also provided a lower profile, having a preferred height A of 4 inches instead of 6.3 inches, and a width B of 8.25 inches instead of the previous 13.25 inches. These dimensions provide a reduced profile having less cost in material, the ability to be placed at a shallower depth and with less fill—both lowering installation costs. The remaining dimensions are preferably much the same as in the previously discussed embodiment, the connecting pipe aperture  22  having a diameter C of 2.375 inches, the inner wall aperture  62  having a height D of 0.875 inches, and the outer shell aperture  64  having a height E of 1 inch (preferably reduced by one-half inch as compared to the previously-discussed embodiment). 
         [0032]    The embodiment shown in  FIG. 8  is best suited for applications in which drainage is the primary and/or only intended function. However, in flat arrays of the system, water backup can be obtained by utilizing an up-turned elbow as a terminating connecting pipe (not shown in the Figures). Such a terminus would create a pressure head, resulting in the flooding of the connector pipe and all intermediate leaching chambers—making irrigation a possible, but not preferred function of the alternative embodiment shown in  FIG. 8 . 
         [0033]    In a presently preferred embodiment, and recognizing that other dimensions are possible—and considered within the scope of the present invention, the leaching chamber  10  is fabricated by extruding a plastic such as high density polyethylene, polypropylene or other suitable polymers. By positioning all of the offset and connecting apertures in an injection mold cavity, all of the improvements can be monolithically molded to produce a one-piece leaching chamber without any other machining. The inner wall apertures and the outer shell apertures are spaced approximately one-and-a-half inches apart, on center, and are vertically offset approximately 1 to 1½ inches. The ½ inch stacking nub  46  and ¼ diameter and ½ inch-long stop nub  68 ; the ¼ inch by 3 inch-long fluting extrusions, the 2 inch height of the inner wall  52 ; the 1 inch width of the footing flange  32 , the ½ inch triangular braces  34 , and the 1 inch wide support footing  42  can all be incorporated in the same injection mold process to produce a single piece integrated chamber. 
         [0034]    The installation of the leaching chambers in accordance with the present invention is initiated by the excavation of a series of trenches, fourteen to eighteen inches deep and eighteen to forty-eight inches wide. The length and width of the trenches will vary, depending upon the design requirements for the particular leaching bed, irrigation field or drainage tile. At a minimum, an excavated section of length four feet is leveled, and if downward leaching of water is not desired, water impermeable liners or enclosing boxes are installed in the leveled trench. Thereafter a series of leaching chambers are placed within the trench, and laid end-to-end so that the lateral leaching chamber water discharge apertures are substantially aligned. The leaching chambers are then connected to one another utilizing the end panel connector pipes. 
         [0035]    A layer of sand or suitable fine gravel for drainage applications is then back-filled over the leaching chambers. Since the upward capillary draw of most sands exceeds a ten-inch vertical above the waterline, a preferred depth of the fill sand over the leaching chambers is approximately twelve inches from the trench bed. The present invention can make use of sands of varying coarseness, with a sand coarseness of 0.3 mm to 0.6 mm grain size being viewed as particularly appropriate. 
         [0036]    Finally, the sand layer may be optionally covered with top soil to a depth of between approximately zero to four inches. Because of the arched cross-section of the outer shell  24 , the leaching chambers  10  are sufficiently strong to withstand the weight of vehicles on top of the replaced soil. Additionally, the individual settling of the leaching chambers within the trenches will not cause a break in the sand seal of the system, since the connector pipes  70  are self-adjusting with the apertures  22  in the end wall  18 . 
         [0037]    Depending upon the slope of the particular terrain, several different arrangements of the leaching chamber arrays are possible. Since the leaching chamber units act independently throughout their (preferred) four foot length, on sloping terrain the trenches are preferably excavated level along the slope contours. The “adjacent” leaching chambers can then be connected perpendicularly across the slope contours, with such adjacent leaching chambers located on different vertical levels, utilizing longer connector pipes where required. 
         [0038]    My invention has been disclosed in terms of a preferred embodiment thereof, which provides an improved half-pipe leaching chambers for subterranean fluid distribution that is of great novelty and utility. Various changes, modifications, and alterations in the teachings of the present invention may be contemplated by those skilled in the art without departing from the intended spirit and scope thereof. It is intended that the present invention encompass such changes and modifications.

Technology Classification (CPC): 4