Patent Abstract:
A waste collection site having a fluid distribution structure, and the structure and related method, the structure including a geocomposite for placement on and between levels of collected waste and at least one pipe extending up from the geocomposite and adapted to receive the fluid from horizontally extending feeder headers. The permeable material includes a spacing layer between top and bottom layers, and a discharge manifold at the bottom of the pipe discharges the fluid between the top and bottom layers. The bottom layer has a flow rate F B  of fluid therethrough and the top layer has a flow rate F T , where F B &lt;F T , and the spacing layer maintains a space between the top and layers to permit flow of fluid therein to distribute the fluid. A geotextile usable as a layer of the geocomposite may be formed by modifying a non-woven needle punched geotextile, including the steps of calendaring the non-woven needle punched geotextile, and needle punching the non-woven needle punched geotextile after the calendaring step to create openings greater than 0.3 mm.

Full Description:
BACKGROUND OF THE INVENTION 
     The present invention is directed toward waste collection sites, and particularly toward the distribution of leachate at such sites. The invention further relates to an improved geotextile which may be advantageously used to distribute leachate. 
     Waste collection sites are, of course, well known and unavoidable requirements of today&#39;s societal structures. Such sites can require large amounts of valuable land, particularly in urban areas where land is most in demand. Also, while desirable uses can be made of such lands (for example, golf courses have been built on such sites), such desirable uses typically have to wait until the land is no longer being used for collect further waste and the often high pile of waste has stabilized. While use and stabilization of such sites can take many years, there is nevertheless a desire to have that accomplished as quickly as possible, not only to increase the safety of those who might have to be at the site but also to allow for the desired use of others (for example, golfers) and to enhance the environment of those who live in the area as soon as is reasonably possible. 
     Toward that end, bioreactor landfills have been used to modify solid waste landfills by re-circulating and injecting leachate/liquid and air to enhance the consolidation of waste and reduce the time required for landfill stabilization. To accomplish this, vertical injection pipes and horizontal pipe fields have most often been used. With these structures, a liner is commonly provided at the bottom of the site, which liner may be used to trap leachate which has run through the collected waste above, with pipes in that area used to collect the leachate and draw it out for re-circulation by pumping it out and distributing/dispersing the leachate back into the upper portions of the waste site through, for example, perforated pipes and/or horizontal trenches. 
     Unfortunately, vertical injection pipes and horizontal pipe fields have been costly, time consuming to install and maintain, and not entirely effective for a number of reasons. As one example, the pipes are susceptible to clogging. As another example, the necessary use of a large number of pipes in a pipe field in order to widely distribute the leachate over a large area is not only costly, but even then virtually impossible to evenly distribute the leachate over that large area. That is, the leachate will be distributed in large part to those areas adjacent to the pipes or trenches and less so to the areas between the pipes or trenches. Typical trench spacing may be 100 to 200 feet horizontally and 40 feet vertically. As a result, such spacing significantly risks uneven or differential settling of the waste. Such differential settling, particularly in the context of such systems being in place for a number of years during which time additional layers of tons of additional waste are added on top of the original waste layers and pipe fields (and during which time heavy equipment is frequently moving around on top of the site), causes such pipe systems to be very susceptible to stress cracks and other damage, particularly given the common use of high density (stiff) resin to manufacture the pipes. 
     The present invention is directed toward overcoming one or more of the problems set forth above. 
     SUMMARY OF THE INVENTION 
     In one aspect of the invention, a fluid distribution structure is provided for use with a waste collection site. The structure includes a permeable material adapted for placement on one level of collected waste and adapted to receive another level of collected waste thereon, and further includes a pipe extending upwardly from the permeable material and adapted to receive the fluid. The permeable material includes a top layer, a bottom layer, and a spacing layer between the top and bottom layers, and the pipe has a lower end secured to the permeable material to discharge the fluid between the permeable material top and bottom layers. The fluid may be liquid, including leachate, or gas, or a combination thereof. 
     In different forms of this aspect of the invention, the top layer is one of a woven geotextile, needle punched non-woven geotextile or continuous filament geotextile, and/or the bottom layer is one of a woven geotextile, needle punched non-woven geotextile or continuous filament geotextile. 
     In another form of this aspect of the invention, the pipe lower end has discharge openings therein disposed above the bottom layer, and the top layer is secured around the discharge openings whereby fluid discharged from the openings is between the top and bottom layers. 
     In still another form, the pipe lower end includes an outwardly tapered discharge manifold, and the top layer is secured around the manifold whereby liquid discharged from the manifold is between the top and bottom layers. The manifold may be a downwardly facing cone over an aggregate fill adapted to allow flow of the fluid therethrough. The cone may also be perforated about its surface to discharge fluid out of the cone and beneath the top layer. 
     In further forms, one or more feeder headers extend generally horizontally through a level of collected waste above the one level of collected waste and discharge fluid into a plurality of horizontally spaced pipes. 
     In still another form of this aspect of the invention, the permeable material bottom layer has a flow rate F B  of liquid therethrough, and the top layer has a flow rate F T  of liquid therethrough, where F B &lt;F T . 
     In yet another form of this aspect of the invention, the spacing layer maintains a space between the top layer and the bottom layer, with the space being open to permit flow of liquid therein to distribute the liquid through the permeable material. The spacing layer may, in one form, be a geonet, geogrid, or mesh. 
     In another aspect of the present invention, a waste collection site is provided, including three layers of waste. A first geocomposite is between the first two layers of waste, and a second geocomposite is between the second and third layers of waste. A first plurality of pipes extend upwardly into the second layer of waste from the first geocomposite, and a second plurality of spaced pipes extending upwardly into the third layer of waste from the second geocomposite. At least one feeder header feeds leachate into an upper end of each of the pipes. The first and second geocomposites each include a top layer, a bottom layer, and a spacing layer between the top and bottom layers, and each of the pipes has a lower end secured to the geocomposite to discharge leachate between the top and bottom layers. 
     In one form of this aspect of the present invention, the pipe lower ends have discharge openings therein disposed above the bottom layer, and the top layer is secured around the discharge openings whereby leachate discharged from the openings is between the top and bottom layers. The spacing layer of the geocomposites may be disposed between the discharge openings and the top layer at each pipe lower end. 
     In another form of this aspect of the invention, the pipe lower ends include an outwardly tapered discharge manifold, and the top layer is secured around the discharge manifold whereby leachate discharged from the manifold is between the top and bottom layers. The discharge manifold may be a downwardly facing cone over an aggregate fill adapted to allow flow of leachate therethrough, and the cone may be perforated about its surface to discharge leachate out of the cone and beneath the top layer. 
     In yet another form of this aspect of the invention, the feeder header includes generally horizontal pipes in at least one of the second and third layers of waste, wherein the horizontal pipes discharge leachate into the tops of the first and second plurality of pipes. 
     In still another form of this aspect of the present invention, the bottom layer of the first geocomposite has a flow rate F 1B  of leachate therethrough, and the top layer of the first geocomposite has a flow rate F 1T  of leachate therethrough, where F 1B &lt;F 1T . Similarly, the bottom layer of the second geocomposite may have a flow rate F 2B  of leachate therethrough, and the top layer of the second geocomposite a flow rate F 2T , where F 28 &lt;F 2T . 
     In a still further form of this aspect of the invention, the spacing layer maintains a space between the top layer and the bottom layer, with the space being open to permit flow of leachate therein to distribute the leachate through the geocomposite. 
     Additionally, the spacing layer may comprise one of a geonet or mesh, and the top and/or bottom layers may comprise one of a woven geotextile, needle punched non-woven geotextile or continuous filament geotextile. 
     In still another aspect of the present invention, a method of distributing leachate at a waste collection system is provided, comprising the steps of providing a geocomposite on one level of collected waste, adding collected waste above the material layer, and inputting leachate at spaced locations in the added collected waste above the material layer. The provided geocomposite includes a top layer, a bottom layer, and a spacing layer between the top and bottom layers, and inputting leachate includes injecting leachate between the top and bottom layers of the geocomposite whereby the spacing layer allows flow of the leachate between the top and bottom layers. 
     In one form of this aspect of the invention, the provided geocomposite has a bottom layer with a flow rate F B  of leachate therethrough and a top layer with a flow rate F T  of leachate therethrough, where F B &lt;F T . 
     In yet another aspect of the invention, a method of modifying a non-woven needle punched geotextile is provided, including the steps of calendaring the non-woven needle punched geotextile, and needle punching the non-woven needle punched geotextile after the calendaring step. 
     In one form of this aspect of the invention, the calendaring step includes passing the non-woven needle punched geotextile between two heated cylinders. The non-woven needle punched geotextile may also be pressured between the heated cylinders. 
     In another form of this aspect of the invention, the needle punching creates openings greater than 0.3 mm. 
     In yet another form, the needle punching step comprises passing the calendared non-woven needle punched geotextile through a needle loom. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 is a side cross-sectional view of the connection of a vertical pipe to a geocomposite in accordance with the present invention; 
     FIG. 2 is a detailed cross-sectional view of a portion of FIG. 1; 
     FIG. 3 is a cross-sectional view of a geocomposite which may be used in accordance with the present invention 
     FIG. 4 is a schematic illustrating a side view of a waste collection site (in the nature of a cross-section along a vertical plane through the waste collection site) according to the present invention; and 
     FIG. 5 is a schematic similar to FIG. 4, but in the nature of a cross-section along a horizontal plane through the waste collection site. 
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     In accordance with the present invention and as described in detail below, a leachate distribution structure  10  is provided whereby a waste collection site such as a landfill may be created as a bioreactor landfill in which leachate may be continuously and evenly re-circulated so as to pass down through the collected waste at the site. Geocomposites  14  formed of permeable material are used to cover layers of the waste as it is collected, with vertical pipes  22  extending up through the collected waste to allow leachate fed though feeder headers  26  to be distributed not only down into different levels of the collected waste, but to be distributed laterally throughout the commonly large area of the collected waste through the geocomposites  14  as described in more detail below. Such excellent distribution of the leachate significantly enhances the consolidation of waste, significantly reduces the risk of differential settlement, and reduces the time required for stabilization of the collected waste. 
     FIG. 1 illustrates a portion of the leachate distribution structure  10 . In particular, a portion of a geocomposite  14  is illustrated as it is connected to a vertical pipe  22 . In accordance with the present invention, the geocomposite  14  will be placed on top of a layer of collected waste  30  and will extend to cover a large surface area of such waste  30 . 
     At spaced locations (e.g., at 4-5 locations per acre) around that area such as illustrated in FIG.  5  and discussed further below, a vertical pipe  22  will be secured to the geocomposite  14  as illustrated in FIGS. 1-2. In the advantageous form illustrated in these figures, an inverted conical support  32  is suitably secured around the lower end of the pipe  22 , for example by a clamp  36  and an extrusion weld  38 . Suitable fill  40  such as stone aggregate is provided within the conical support  32  to help to secure the pipe  22  on the geocomposite  14  (particularly, e.g., when it is placed on top of the geocomposite  14  and before additional waste for a new layer is added around it), and also to help to strengthen the support  32  against collapse from the weight of additional waste added around and on top of it thereafter. The fill  40  also helps to distribute the migration or flow of leachate as described below, with the conical support  32  thereby also serving as a radial distribution manifold as described hereafter. While not intended to limit the scope of the invention in any way, to give an appreciation of the workings of the invention for illustrative purposes only, it should be noted that the flow of leachate through the manifold/conical support  32  may be on the order of 100 gallons per minute. 
     The lower portion of the vertical pipe  22  includes perforations  42  through which leachate pumped into the pipe  22  may pass. From the vertical pipe perforations  42 , the leachate will pass through the fill  40  and then ultimately through perforations  46  in the tapered side walls and bottom wall of the conical support  32  (see FIG.  2 ). 
     Broadly, as best seen in FIG. 3, the geocomposite  14  is a composite of three different layers: a top layer  50 , a bottom layer  52 , and a spacing layer  54  between the top and bottom layers  50 ,  52 . Leachate may desirably leak through both the top and bottom layers  50 ,  52  as described hereafter. Further, the bottom layer  52  may have a flow rate F B  of leachate therethrough, and the top layer  50  may have a flow rate F T  of leachate therethrough. The spacing layer  54  provides a suitable path whereby leachate at a location in the spacing layer  54  which is more than may immediately leak through the bottom layer  52  will migrate laterally through the spacing layer  54  until it is able to leak through the bottom layer  52 . In this manner, unequal pockets of leachate may be advantageously dispersed out over the site. As further explained hereafter, F B  may also advantageously be less than F T . As one example, the top layer  50  may have openings on the order of greater than about 11% of its surface (it has been found that woven geotextiles with openings of greater than about 11% are difficult to clog in applications of this type) and the bottom layer  52  may have openings on the. order of 5-6%. Still further details of advantageous aspects of these layers  50 ,  52 ,  54  are described further below. 
     Where secured to a vertical pipe  22 , the top layer  50  of the geocomposite  14  is removed so that the vertical pipe  22  and support  32  essentially sit on the spacing layer  54 . Moreover, a spacing layer  54 ′ and top layer  50 ′ are also secured over the conical support  32 . Specifically, a section of top layer material is provided over the conical support  32 , and is suitably secured at its upper end to the vertical pipe  22  (as by the clamp  60 ) and is suitably secured to the top layer  50  (as by a heat bond  62 ) around the perimeter of the area in which the top layer is removed. 
     It should be appreciated that, with the above structure, leachate which is supplied into the vertical pipe  22  will pass out the pipe perforations  42  and migrate through the fill  40  until it passes out the support perforations  46  into a space which is beneath the top layer  50 ′, with the spacing layer  54 ′ between the outer surface of the conical support  32  and the top layer  50 ′. The leachate may thus migrate through the conical spacing layer  54 ′ down to the spacing layer  54  at the bottom of the conical support  32  and about its perimeter, from which it may then migrate outwardly through the spacing layer  54  between the top and bottom layers  50 ,  52  as described further below. Of course, leachate may also migrate through the fill  40  to the perforations  46  in the bottom of the conical support, and from there pass directly to the spacing layer  54  therebeneath. 
     As one example, the vertical pipe  22  may be a 4 inch diameter SDR21 HDPE pipe with a stub end  66  which may be secured to a similar pipe extension where required. The conical support  32  may be filled with 57+stone, and may be vacuum formed 100 mil HDPE, with a height on the order of 16 inches and a base diameter on the order of 40 inches. The base of the conical support  32  may be formed of ⅜ inch thick HDPE, with a diameter on the order of 48 inches, with an extrusion weld  68  (see FIG. 2) securing the base and conical portions. The perimeter of the area in which the top layer of the geocomposite  14  is removed may have a diameter on the order of 72 inches (providing a space of about 12 inches around the base of the conical support to simplify locating the support on the geocomposite  14 ). However, it should be understood that these details are merely examples provided to give a general of one workable construction of the vertical pipe  22  and conical support  32 , without intending to limit the scope of the invention in any way. It should be understood that many different variations of this structure could be used within the scope of the invention described herein, including different sizes, materials and shapes. For example, while the conical shape of the support  32  may advantageously be used to disperse leachate as is further described herein, still other shapes could also be used within the scope of the present invention, including the cylindrical shape of the pipe  22 . 
     FIGS. 4-5 (which are not intended to be of scale) illustrate the manner in which the present invention may be used in a waste collection site over time. 
     Specifically, as illustrated in FIG. 4, as the site is initially used, a first level of collected waste  30   a  is accumulated, after which a geocomposite  14   a  is placed thereon with spaced vertical pipes  22   a . At that point in time in the “life” of the waste collection site, the vertical pipes  22   a  will extend above the ground layer and leachate may be pumped into the vertical pipes  22   a  using suitable hoses or the like. Thereafter, further waste will be added to the site, ultimately forming a second level of collected waste  30   b  on top of the first geocomposite  14   a , and a second geocomposite  14   b  may then be placed thereon with spaced vertical pipes  22   b . Pipe extensions  70  may be added to the stub ends  66  of the vertical pipes  22   a  to extend their upper end to the level of the upper end of the vertical pipes  22   b , whereby feeder headers  26  may ultimately be attached to the upper ends of the vertical pipes (or their extensions) to facilitate circulation of leachate of all of the vertical pipes for re-circulation through the collected waste  30   a ,  30   b  beneath the geocomposites  14   a ,  14   b . Again, as still more waste is collected and added to the site, a third level of collected waste  30   c  may ultimately be formed on top of the second geocomposite  14   b , at which point a third geocomposite  14   c  may be placed thereon with spaced vertical pipes  22   c.    
     Progressive addition of collected waste may then similarly proceed to a fourth level of collected waste  30   d , with a fourth geocomposite  14   d  and vertical pipes  22   d , and a fifth level of collected waste  30   e  and geocomposite  14   e  thereon. Such continued accumulation of waste may continue in this manner until it is determined that no more waste should be added to the site. During that time, the present invention as described may be used to advantageously re-circulate leachate through the waste whereby the site will be a bioreactor landfill which will relatively quickly stabilize with minimal differential settling. 
     This is further illustrated in FIG. 5, where an advantageous spacing of vertical pipes  22  on a particular geocomposite  14  is illustrated (though not to scale). The pipes  22  are hidden beneath the feeder headers  26 , and therefore the conical supports  32  are seen. Specifically, each of the vertical pipes  22  may be considered to radiate outwardly to cover a circular field  80 . With the disclosed arrangement, the entire site may be covered by the fields. Of course, the migration of leachate through the spacing layer  54  of the geocomposite  14  is not expected to be a over an exact circle such as illustrated in FIG. 5, nor is such migration from a particular pipe  22  limited to the circular field  80  illustrated. Nonetheless, it should be appreciated that such an arrangement may provide a configuration which will advantageously allow for relatively uniform migration of leachate over a given level of the waste collection site. That is, where the leachate is input through the vertical pipe  22  at a rate which is, for example, a function of the flow rate F B  through the bottom layer  52  of the geocomposite  14  and the area of its field  80 , the leachate will not be able to simply leak through the geocomposite bottom layer  52  directly beneath the pipe  22  and conical support  32 , but instead will migrate, through the spacing layer  54  whereby it may leak into the waste level therebeneath across substantially the entire field  80 . 
     It should also be appreciated that the leachate will not only reach the geocomposites  14  directly from the spaced vertical pipes  22 , but will also drain down through the level of collected waste  30  on the geocomposite  14 . Thus, while the provision of the invention described herein on that level of collected waste will assist in ensuring that leachate will migrate relatively uniformly therethrough, given the variations in the waste and shifting which can occur during the years of use the reality is that even a perfectly uniformly distributed leachate leaking into the top of the layer will no longer be so evenly distributed at the bottom of the layer. In that case, where the leachate migration in a heavy flow area is greater than the flow rate F T  of the top layer  50  will permit to immediately pass therethrough, the top layer  50  will hold up the leachate to some degree, during which time it will tend to migrate outwardly and thereby disperse the heavy flow in that area. Similarly, where the bottom layer  52  is advantageously formed with a flow rate F 8  of leachate therethrough which is less than the flow rate F T  of leachate through the top layer  50  as previously noted, it should be appreciated that still further outward dispersion from the heavy flow areas will occur through the spacing layer  54  before the leachate passes through the bottom layer  52 . 
     As illustrated in FIG. 4, the geocomposites  14  may be extended so as to slope downwardly on the ends. This may be used to assist in diverting leachate to the side of the waste collection site from which it may more freely drain, particularly in the event that excessively heavy leachate is entering the site. 
     It should also be understood that while the system may be advantageously used with a liquid such as leachate, the present invention may similarly be used in applications in which other fluids, including gases such as air and mixes of liquids and gases, are desired to be dispersed in a mass. 
     Reference will now be had to the geocomposites  14  which may be advantageously used with the present invention. 
     As one example, one geocomposite which may be advantageously used with the present invention may be a HDPE bi-planar geonet or geogrid forming the spacing layer  54  and laminated with a woven geotextile on one side (forming the top layer  50 ) and a non-woven geotextile on the other side (forming the bottom layer  52 ). Either of the geotextiles advantageously may, however, be a woven geotextile, a non-woven needle punched geotextile, or a continuous filament geotextile. 
     In the present example, the woven geotextile forming the top layer  50  may advantageously have the following properties: 
     
       
         
               
               
             
           
               
                   
               
               
                   
                 Polyethylene, Polypropylene, Polyester 
               
               
                 Material Type 
                 or Polyvinyl chloride (fibers) 
               
               
                   
               
             
             
               
                 Percent Open Area (%) 
                  9.0 to 13.0 
               
               
                 Apparent Opening Size (mm) 
                  1.0 to 0.300 
               
               
                 Thickness (mils) 
                  10 to 200 
               
               
                 Permittivity range (sec −1 ) 
                 0.2 to 1.5 
               
               
                 Mass per unit area (oz/yd 2 ) 
                  4 to 20 
               
               
                 Water flow rate range (gpm/ft 2 ) 
                  15 to 300 
               
               
                 Grab tensile strength (lbs) 
                 100 to 500 
               
               
                 Grab elongation range (%) 
                  20 to 100 
               
               
                 Puncture strength range (lbs) 
                  50 to 300 
               
               
                 Mullen burst strength (psi) 
                 200 to 800 
               
               
                 Trapezoidal tear strength (lbs) 
                  50 to 170 
               
               
                 Permeability rate (cm/sec) 
                 0.01 to 0.5  
               
               
                   
               
             
          
         
       
     
     In the present example, the non-woven geotextile forming the bottom layer  52  may advantageously be manufactured with multiple layers and may have the following properties: 
     
       
         
               
               
             
           
               
                   
               
               
                   
                 Polyethylene, Polypropylene, Polyester, 
               
               
                 Material Type 
                 or Polyvinyl chloride 
               
               
                   
               
             
             
               
                 Mass Per Unit Area, g/m 2   
                  4.0 to 32.0 
               
               
                 Apparent Opening Size (mm) 
                 0.1 to 0.5 
               
               
                 Thickness (mils) 
                  10 to 200 
               
               
                 Permittivity range (sec −1 ) 
                 0.2 to 1.5 
               
               
                 Mass per unit area (oz/yd 2 ) 
                  4 to 20 
               
               
                 Water flow rate range (gpm/ft 2 ) 
                  15 to 300 
               
               
                 Grab tensile strength (lbs) 
                 100 to 500 
               
               
                 Grab elongation range (%) 
                  20 to 100 
               
               
                 Puncture strength range (lbs) 
                  50 to 300 
               
               
                 Mullen burst strength (psi) 
                 200 to 800 
               
               
                 Trapezoidal tear strength (lbs) 
                  50 to 170 
               
               
                 Permeability rate (cm/sec) 
                 0.01 to 0.5  
               
               
                   
               
             
          
         
       
     
     The geonet or geogrid forming the spacing layer  54  may advantageously have the following properties: 
     
       
         
               
               
             
           
               
                   
               
               
                   
                 Polyvinyl chloride, Polypropylene, 
               
               
                 Material Type 
                 Polyester, Polyethylene, HDPE 
               
               
                   
               
             
             
               
                 Weight (oz/yd 2 ) 
                  1 to 20 
               
               
                 Ultimate tensile strength (lb/ft 2 ) 
                 10 to 70 
               
               
                 Thickness mils 
                 160-300 
               
               
                 Tensile strength (ppi) 
                   0 to 2000 
               
               
                 Aperture size (inches) 
                 0.01 to 2.0  
               
               
                 Density (gm/cm 3 ) 
                 0.92 to 0.95 
               
               
                   
               
             
          
         
       
     
     It should be understood, however, that the above characteristics of materials which may be used for the geocomposite layers  50 ,  52 ,  54  are only examples, and that a large number of materials which may or may not meet all of the above characteristics could still be used within the scope of various aspects of the invention. For example, any geocomposite having a bottom layer with a lower flow rate than the top layer and with a space maintained between the layers to allow lateral flow of leachate in that space would be suitable to obtain that previously described advantage. As another example, different opening sizes than indicated in the example may be used if the spacing layer  54  maintains an adequate spacing between the top and bottom layers  50 ,  52  so that lateral leachate dispersion is allowed such as described. 
     Additionally, woven geotextiles may not be readily laminated to geonets. Therefore, in order to provide a desired securement between the bottom and spacing layers  52 ,  54 , the bottom layer  52  of the geocomposite  14  may advantageously be non-woven. (Securement of the top layer  50  to the spacing layer  54  is not as difficult, or as important, to maintain, thereby allowing the advantageous use of a woven geotextile for the top layer  50  in the above example, particularly where significantly larger opening sizes are provided.) Non-woven geotextiles having maximum opening size of about 0.2 mm are generally available, but non-woven (needle punched) products having opening sizes larger than 0.3 mm are not so readily available, with woven geotextiles generally required for such larger opening sizes. However, as indicated in the example above, non-woven geotextiles having opening sizes larger than 0.3 mm may be advantageously used in the bottom layer  52  with the present invention. Particularly given the long term use of the geocomposites  14  such as described, such larger size openings allow fine soil particles to move through the geotextile and make it less prone to severe clogging by fine particulates, suspended solids and microbial growth. Therefore, applicant has additionally developed such an advantageous non-woven needle punched geotextile which may be advantageously used as a part of the geocomposite  14  of the present invention. 
     Specifically, a suitable geotextile may be formed by further processing of a non-woven needle punched geotextile, including specifically (1) calendaring the non-woven needle punched geotextile by passing it between two heated cylinders which pressure the geotextile therebetween, and then (2) needle punching the non-woven needle punched geotextile after the calendaring step, where the needle punching is accomplished by passing the calendared non-woven needle punched geotextile through a needle loom which creates openings greater than 0.3 mm. 
     For example, applicant has produced a geotextile using as a starting geotextile the NW6 6 oz. geotextile of GSE Lining Technology, Inc. of Houston, Tex. Processing in accordance with the above method produced a geotextile with the following characteristics (with the characteristics of the NW6 starting geotextile also shown for comparison): 
     
       
         
               
               
               
             
               
               
               
             
           
               
                   
               
               
                   
                   
                 NW6 Geotextile after 
               
               
                   
                 NW6 
                 Calendaring and Needle 
               
               
                 Test Property 
                 Geotextile 
                 Punching 
               
               
                   
               
             
             
               
                   
               
             
          
           
               
                 Mass (oz./sq. yard) 
                 6 
                 6.5 
               
               
                 Thickness (mils) 
                 80 
                 53 
               
               
                 Grab strength (lbs) 
                 170 
                 209 
               
               
                 Grab tensile elongation (%) 
                 50 
                 86 
               
               
                 Mullen burst strength (psi) 
                 330 
                 345 
               
               
                 Puncture strength (lbs) 
                 110 
                 110 
               
               
                 Apparent opening size (mm) 
                 0.21 
                 0.45 
               
               
                 Permittivity (sec −1 ) 
                 1.5 
                 2.0 
               
               
                   
               
             
          
         
       
     
     This calendared geotextile has a stiffness, drape and physical appearance which is similar to a heat bonded geotextile and, therefore, like heat bonded geotextiles, will advantageously result in less intrusion into a geonet of the spacing layer  54  to which it may be secured and therefore may provide advantageous transmissivity of the formed geocomposite  14 . 
     Of course, the improved geotextile described above may also have advantageous use in applications other than the leachate distribution system described herein. 
     Still other aspects, objects, and advantages of the present invention can be obtained from a study of the specification, the drawings, and the appended claims. It should be understood, however, that the present invention could be used in alternate forms where less than all of the objects and advantages of the present invention and preferred embodiment as described above would be obtained.

Technology Classification (CPC): 8