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FIELD OF THE INVENTION 
     The present invention relates to the field of systems for the control of termites and other pests that access building structures from underground. More particularly, the present invention relates to the field of distribution structures and methods of using the structures to control termites and other pests that access a building structure from underground. 
     BACKGROUND 
     Prior to the 1988 ban on the use of chlordane for termite protection, a single treatment of a building site prior to construction provided long-term protection against termites. The practice at that time entailed a single application to the soil prior to the pouring of foundations and cement slabs. Tests conducted as long as 52 years after such treatment indicated no signs of breakdown. 
     However, because of environmental problems associated with chlordane, other chemicals have had to be substituted. The chemicals in use today for termite control are considerable more expensive. Further, their effective life has not been reliably tested. Typically, the industry guarantees the life of such products applied as a pre-treat for only five years. 
     At the end of five years, the homeowner must decide whether to gamble and risk a termite invasion or to apply a re-treatment. When possible, the re-treatment consists of drilling holes no less than every two feet around the perimeter of the home and also adjacent to plumbing protrusions. The chemical is then injected, typically at the rate of four gallons per ten lineal feet. Frequently, the process becomes even more difficult and expensive. If the homeowner has planted trees or shrubs or has installed sidewalks or pools that interfere, it becomes necessary to apply treatment from inside the structure. This entails, in many cases, pulling up carpets, drilling holes through ceramic tiles and cement slabs and then applying the chemicals through the holes. After all this, and at a cost more than twice that of the original pre-treat, the re-treatment is typically only guaranteed one more year. 
     Accordingly, inventions involving structures and methods directed at a solution for preventative termite re-treatment have been heretofore disclosed in related art patents. The relevant related art patents have in common an underground distribution system comprised of tubes through which the termiticide is dispensed into the surrounding underground area. Examples of these inventions are disclosed in the patents listed below: 
     
       
         
               
               
             
           
               
                   
               
               
                 U.S. Pat. No. 
                 Inventor 
               
               
                   
               
             
             
               
                 5,960,584 
                 Aesch, Jr. 
               
               
                 5,007,197 
                 Barbett 
               
               
                 5,184,418 
                 Fletscher 
               
               
                 5,819,466 
                 Aesch et al. 
               
               
                 5,394,642 
                 Takoaka 
               
               
                 5,378,086 
                 Campbell, Jr. et al. 
               
               
                 4,625,474 
                 Peacock, deceased et al. 
               
               
                 2,842,892 
                 Aldridge et al. 
               
               
                   
               
             
          
         
       
     
     What these patents fail to disclose or suggest is a structure or method of delivering termiticide that affects an effective delivery while minimizing the potentially adverse environmental impacts of delivering termiticide chemistry under a constructed building. 
     The prior art designs disclose “open systems” that use high pressure underground termiticide delivery systems that are accessible from an above ground access port. In other words, the prior art underground delivery systems do not disclose a system capable of recapturing residual termiticides. Accordingly, any residual termiticide that remains in the deliver system after treatment may out gas through the above ground access port of the underground delivery system. 
     Further, the use of high pressure delivery methods affects an inefficient delivery of termiticide. Maintaining a constant elevated pressure throughout an underground piping system during delivery is difficult. ordinarily, high pressure underground delivery systems result in pressure gradients throughout the underground delivery system. The magnitude and dispersion of the pressure gradients in the system depends on many variables including the overall length of the delivery system, the diameter of the delivery piping, the radius of curvature of the delivery system piping corners, the distance of the delivery aperture from the pressure source, and the circumference of the delivery apertures. However, the adverse effect of each of these variables, and as a result the magnitudes of the pressure gradients, is augmented by the use of a relatively high-pressure delivery source. Accordingly, the effectiveness of termiticide delivery can be improved through a low-pressure delivery system. 
     Thus, there is a need for a pesticide deliver system that offers an improved and safer alternative to this dilemma in the form of an underground termiticide delivery system for periodic or “as needed” pesticide applications after construction of buildings. The present invention enables high-volume pesticide delivery to underneath a building structure while minimizing airborne or above ground pesticide dispersal and exposure to people as a result thereof. Accordingly, the present invention provides a more effective barrier to pests while minimizing the adverse consequences of relatively high-pressure underground pesticide delivery systems. 
     SUMMARY OF THE INVENTION 
     The present invention is a closed pesticide delivery system comprising a pesticide delivery apparatus and method of using the pesticide delivery apparatus. The pesticide delivery apparatus comprises a low-pressure pesticide propellant source, a propellant recovery reservoir, a prewetting &amp; purging source, underground pesticide delivery tubing, and above ground hoses to connect the components of the apparatus. The method of using the present invention comprises the steps of: 1) prewetting with a water-based solutions of the underground adjacent to the underground pesticide delivery tubing; 2) propelling a pesticide solution through the underground pesticide delivery tubing and into the underground adjacent to the underground delivery tubing; and 3) purging, and verifying the purge, of the underground pesticide delivery tubing. Implementations of the invention are contemplated wherein the pesticide comprises a termiticide. Alternate implementations are also contemplated wherein the pesticide comprises biologically active nematodes either in place of or in combination with the termiticide. 
     The novel features that are considered characteristic of the invention are set forth with particularity in the appended claims. The invention itself, however, both as to its structure and its operation together with the additional object and advantages thereof will best be understood from the following description of the preferred embodiment of the present invention when read in conjunction with the accompanying drawings. Unless specifically noted, it is intended that the words and phrases in the specification and claims be given the ordinary and accustomed meaning to those of ordinary skill in the applicable art or arts. If any other meaning is intended, the specification will specifically state that a special meaning is being applied to a word or phrase. Likewise, the use of the words “function” or “means” in the Description of Preferred Embodiments is not intended to indicate a desire to invoke the special provision of 35 U.S.C. §112, paragraph 6 to define the invention. To the contrary, if the provisions of 35 U.S.C. §112, paragraph 6, are sought to be invoked to define the invention(s), the claims will specifically state the phrases “means for” or “step for” and a function, without also reciting in such phrases any structure, material, or act in support of the function. Even when the claims recite a “means for” or “step for” performing a function, if they also recite any structure, material or acts in support of that means of step, then the intention is not to invoke the provisions of 35 U.S.C. §112, paragraph 6. Moreover, even if the provisions of 35 U.S.C. §112, paragraph 6, are invoked to define the inventions, it is intended that the inventions not be limited only to the specific structure, material or acts that are described in the preferred embodiments, but in addition, include any and all structures, materials or acts that perform the claimed function, along with any and all known or later-developed equivalent structures, materials or acts for performing the claimed function. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 depicts an embodiment of the present invention implemented on a building. 
     FIG. 2 depicts the detail within the encircled area of FIG.  1 . 
     FIG. 3 depicts an embodiment of the tubing of the invention. 
     FIG. 4 depicts an embodiment of a first routing plan of the tubing of the invention. 
     FIG. 5 depicts an embodiment of a second routing plan of the tubing of the invention. 
     FIGS. 6,  7  &amp;  8  depict alternate embodiments of access inlets or outlets implemented on a structure. 
     FIGS. 9 &amp; 10 depicts the preferred orientation of the pesticide output apertures. 
     FIG. 11 shows the preferred alternating pesticide output aperture distribution. 
     FIG. 12 depicts a plurality of access inlets and outlets. 
     FIGS. 13 &amp; 14 depict a preferred manner of delivering the service to a job site. 
    
    
     DESCRIPTION OF PREFERRED EMBODIMENTS 
     Referring to FIGS. 13 &amp; 14, the preferred low-pressure pesticide source comprises a pesticide source tank  1316  coupled to a propellant mixture tank  1318  by a pesticide source line  1330  and controlled by a pesticide source valve  1324 . A gas pressure generator  1304  (e.g. air compressor) is also coupled to the propellant mixture tank  1318  by a gas pressure generator line  1306 . The preferred gas pressure generator  1304  is regulated to prevent damaging pressure potentials in the system that can be hazardous and costly to repair. The pesticide source tank  1316  further includes a pesticide source tank inlet  1312  and is coupled to a pesticide vapor recovery reservoir  1326  by a pesticide vapor recovery line  1314 . 
     The preferred prewetting &amp; purging source is implemented with a prewetting &amp; purging solution source tank  1308  that is coupled to the propellant mixture tank  1318  by a prewetting &amp; purging solution source line  1322  and controlled by a prewetting &amp; purging solution control valve  1320 . The propellant mixture tank  1318  is coupled by a propellant delivery line  1328  to a rolled propellant delivery line  210  that includes a propellant delivery control valve  208 . FIGS. 13 &amp; 14 also depict the preferred manner of transporting the pesticide source and prewetting &amp; purging source to a jobsite (e.g. either by truck  1302  with trailer  1332  or by truck  1302  with flatbed  1402 ). 
     Referring to FIG. 2, the underground pesticide delivery tubing is situated underneath the bottom slab  220  of the foundation a building  104  and within the fill  222  beneath the foundation perimeter  102 . Moreover, alternate embodiments of the actual underground pesticide delivery tubing are possible as depicted in FIGS. 4 &amp; 5. The underground pesticide deliver tubing is situated in the fill  222  beneath the building at areas that provide, the highest likelihood of access by pests. Preferably, the underground pesticide delivery tubing is routed in the fill  222  beneath and just inside the foundation perimeter  102  of the building  104 . Moreover, the underground pesticide deliver tubing is routed through the fill  222  around any water and sewage apertures  502  that penetrate the bottom slab  220  of the foundation. 
     Pressure gradients in the underground pesticide delivery tubing effect a substantially unequal distribution of pesticide to the fill  222  beneath the building  104  and are therefore undesirable. Thus, preferred alternate routing plans for the underground pesticide delivery tubing as depicted in FIGS. 4 &amp; 5 provide an ability minimize the potential pressure gradients in the delivery tubing. The routing plan in FIG. 5 is appropriate for larger foundation perimeters  102  where a return routing of the underground pesticide delivery tubing, as depicted in FIG. 4, would effect a undesirable or unworkable pressure gradient in the underground pesticide deliver tubing. The routing plan in FIG. 4 is also appropriate in regions of the country where pests pose a greater problem. The return routing effects a broader lateral distribution  402 ,  404 , than does a single buried line of tubing. 
     At a jobsite, the propellant delivery line  210  is connected to a first inlet of the underground pesticide delivery tubing as depicted in FIGS. 1 &amp; 2. FIG. 12 depicts several pesticide delivery tubing inlets and outlets  1202 ,  1204 ,  1206 ,  1208 ,  1212 ,  1214 , that are tapped and adapted to receive a connector on the end of the propellant delivery line  210 . Thereafter, the prewetting solution is dispersed from the pesticide source tank  1312  into the propellant mixture tank  1318  and mixed with pressurized air from the gas pressure generator  1304 . The propellant delivery control valve  208  is opened and the prewetting solution is allowed to disperse into the underground pesticide delivery tubing. It is preferred that the gas pressure generator  1304  regulation prevent the pressure potential in the underground pesticide delivery tubing from exceeding 23 p.s.i. during dispersal of the prewetting solution. Finally, the pesticide and purging solutions are subsequently dispersed into the underground delivery tubing in a similar manner and with the same preferred pressure limit in the underground pesticide delivery tubing. 
     The propellant recovery reservoir is connected to the tubing outlet that corresponds with the corresponding tubing inlet and permits verification of the propellant dispersal throughout the underground pesticide delivery tubing. The preferred propellant recovery reservoir is a mobile propellant recovery tank  202 , as depicted in FIGS. 1 &amp; 2, to minimize the pressure potential necessary to effect the delivery of pesticide throughout the underground pesticide delivery tubing. The pesticide recovery tank  202  is coupled by a pesticide recovery tank inlet line  204  to the outlet access aperture of the underground pesticide delivery tubing. A second pesticide recovery tank valve  206  permits verification and recovery of propellant dispersal. 
     FIGS. 3, and  9 - 11  depict the preferred distribution of underground pesticide delivery tubing pesticide output apertures. FIG. 11 shows the preferred alternating pattern of the 45-degree output aperture  902  and the 315-degree output aperture  1002  of FIGS. 9 &amp; 10. The angles of the apertures are measured relative to a cross sectional vertical bisection of a representative portion of the underground pesticide delivery tubing. The preferred length between adjacent output apertures is no more than eighty inches. The preferred aperture diameter is less than one sixteenth of an inch in diameter. 
     There exist various access structures to the underground pesticide deliver tubing. Three alternate embodiments are depicted in FIGS. 6,  7  and  8 . FIG. 6 depicts a raised recessed pesticide inlet cavity  602  that houses an access aperture to the underground pesticide deliver tubing. FIG. 7 depicts an inline recessed inlet aperture  704 . FIG. 8 depicts a partially sunken access inlet cavity  804  that is non-destructive to the building  104  structure. 
     The preferred embodiment of the invention is described above in the Drawings and Description of Preferred Embodiments. While these descriptions directly describe the above embodiments, it is understood that those skilled in the art may conceive modifications and/or variations to the specific embodiments shown and described herein. Any such modifications or variations that fall within the purview of this description are intended to be included therein as well. Unless specifically noted, it is the intention of the inventor that the words and phrases in the specification and claims be given the ordinary and accustomed meanings to those of ordinary skill in the applicable art(s). The foregoing description of a preferred embodiment and best mode of the invention known to the applicant at the time of filing the application has been presented and is intended for the purposes of illustration and description. It is not intended to be exhaustive or to limit the invention to the precise form disclosed, and many modifications and variations are possible in the light of the above teachings. The embodiment was chosen and described in order to best explain the principles of the invention and its practical application and to enable others skilled in the art to best utilize the invention in various embodiments and with various modifications as are suited to the particular use contemplated.

Summary:
A closed high-volume low-pressure pesticide delivery and recovery system including under building pesticide delivery tubing and a method of using the pesticide delivery tubing.