Abstract:
A device for treating the ground in the vicinity of buried structures, comprises a plurality of probes which are driven into the subsoil and are connected to a control unit provided with an air generating device for generating, within the ground, a flow of dry air. The probes are arranged so as to make the generated air flow lap all the surfaces of the buried structures.

Description:
[0001]    This is a Continuation-in-Part of prior U.S. Ser. No. 08/982,375 filed on Dec. 2, 1997  
     
    
     
       BACKGROUND OF THE INVENTION  
         [0002]    The present invention relates to a device for treating the soil in the vicinity of buried structures.  
           [0003]    The wide range of problems that occur due to the presence of structures underground, particularly tanks and pipelines, is known.  
           [0004]    In the case of tanks for containing pollutants, there is the danger of corrosion of the walls of the tanks, with the consequent leakage of the substances in the neighboring soil; measures such as cathodic protection or the sheathing of the walls with substances such as fiberglass-reinforced plastics have accordingly been proposed.  
           [0005]    These measures, however, entail high costs and are also often questionably effective.  
           [0006]    The requirement of avoiding subsoil pollution also causes the need to install systems for detecting any leakage from tanks and lines; for this purpose, either installation is performed of probes constituted, in the prior art, by slotted tubes which are driven into the ground and by means of which the gas contained in the subsoil is extracted in order to analyze it, or micrometric indicators are inserted in the tanks which detect any decrease in the level of the contained liquid.  
           [0007]    Various systems, mainly based on the injection of air, which is suitable to facilitate biodegradation of pollutants, into the subsoil by means of probes, are also currently known for reclaiming polluted soils.  
           [0008]    It is evident that the current situation is characterized by independent and different approaches to the different problems, with high costs and anything but ideal functional effectiveness.  
         SUMMARY OF THE INVENTION  
         [0009]    The aim of the present invention is to provide a device for treating the soil in the vicinity of buried structures which allows a global action that seeks to solve all the problems posed, consequently reducing costs and improving the results obtained.  
           [0010]    Within the scope of this aim, an object of the present invention is to provide a probe which, once driven into the ground, allows variations in its operating characteristics.  
           [0011]    This aim, this object and others which will become apparent hereinafter are achieved by a device for treating the soil in the vicinity of buried structures, according to the present invention, characterized in that it comprises a plurality of probes which are buried in the subsoil and are connected to a control unit provided with means for generating, in the soil, a flow of dry air, said probes being arranged so that the flow that they generate laps all the surfaces of said buried structures.  
           [0012]    Advantageously, means are provided for heating the dry air and the probes are furthermore divided into an injection set and an extraction set, the extraction set being connected to the control unit with at least one line which comprises at least means for detecting characteristics of the flow.  
           [0013]    According to the present invention, a probe also comprises an outer tubular jacket, provided with through holes at its entire wall, and a tubular core, which has a solid wall and is shorter than the outer jacket; said core is associated in contact with the inner surface of said jacket and is provided with means which allow to arrange it in any position.  
       
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0014]    Further characteristics and advantages of the present invention will become apparent from the following detailed description of a preferred but not exclusive embodiment thereof, illustrated only by way of non-limitative example in the accompanying drawings, wherein:  
         [0015]    [0015]FIG. 1 is a view of an application of the device to the treatment of the soil in the vicinity of a buried tank;  
         [0016]    [0016]FIG. 2 is a partially sectional view of a probe;  
         [0017]    [0017]FIGS. 3 and 4 are views of two different operating conditions that can be provided with probes according to the present invention.  
     
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS  
       [0018]    With reference to FIG. 1, the reference numeral  1  designates a tank which is meant to contain a pollutant, such as for example gasoline, and the reference numerals  2 ,  3  and  4  designate conventional probes which are driven into the subsoil above the tank in order to inject air, which is fed by means of a line  5  through the action of a compressor  6 .  
         [0019]    The compressor is in turn supplied with atmospheric air, aspirated through a filter  7  and passed through a drying device  8 , which reduces the relative humidity of said air to an optimum value.  
         [0020]    The reference numerals  9  and  10  further designate two extraction probes, also of a known kind, which are open only at end portions  9   a,    10   a  located at a level lying below the tank  1 , and are shielded in an upward region; the extraction probes are connected to a line  11 , which leads into the atmosphere at  12  and is provided with an offtake  13 , which conveys the extracted flow to devices for analyzing the composition of the flow and to devices for detecting the temperature and relative humidity of said flow, which are contained in a box  14  comprised within a building  15  that accommodates the described multipurpose control unit.  
         [0021]    The control unit is completed by a line  16  for mutually connecting the air injection and extraction lines, and there are valves  17 ,  18  and  19  which allow to cut out the line or to convey along said line the flow extracted by the probes  9  and  10  in order to return it into the soil.  
         [0022]    It is immediately evident that the present invention operates effectively from many points of view which will be set forth.  
         [0023]    The dried air flow, indicated by the arrows in  1 , strikes the walls of the tank and dehumidifies the soil in the vicinity of said tank, thus preserving it from corrosion; it also keeps the soil ventilated enough to maintain the activity of the biological processes that degrade any pollutants present due to leaks or dumping.  
         [0024]    The aspiration of the flow on the part of the probes  9  and  10  also allows to analyze the flow so as to continuously monitor the state of the treated soil: it is noted, by way of example, that a recording performed by the instruments in the box  14  of a decrease in relative humidity, combined with an increase in the temperature of the air flow after a first period of operation, is assuredly an indicator of a correct development of the flow in the soil that lies around the tank  1  and accordingly of good efficiency in the anticorrosion treatment of the tank and in the reclamation of the soil.  
         [0025]    This recording can therefore be followed by a certification of the adequacy of the treatments.  
         [0026]    The monitoring of the state of the soil that can be performed with the device according to the present invention further allows, again by way of example, to record in real time the occurrence of a leak of pollutant, detected by the analyzers in the box  14 , and to control the development of the subsequent reclamation treatment.  
         [0027]    What has been described above with reference to a tank also applies, of course, to any buried structure and particularly in the case of pipelines that convey pollutants.  
         [0028]    The above description clearly shows the high efficiency of the present invention, which combines the ability to perform a plurality of functions which are currently assigned to different devices: anticorrosion treatment of the buried structures, soil monitoring and reclamation of the soil.  
         [0029]    The multifunctional nature of the device does not negatively affect the effectiveness of any of the operations it performs; on the contrary, a synergistic effect among the operations is observed which completes their optimization.  
         [0030]    It should also be noted that substances, such as tracers suitable to be detected by the analyzers of the extracted flow, or nutrients suitable to facilitate biodegradation of the pollutants, can be introduced in the air injected into the subsoil.  
         [0031]    Attention is drawn, within the framework of high functional efficiency that has been described, to the low installation cost of the invention, especially if the installation is performed during the installation of the structures to be protected, and to the low cost both in terms of labor and energy consumption.  
         [0032]    The position of the injections and extraction probes may as well be exchanged without altering the inventive concept of the invention. Thus, the injection probes may be arranged below the tank and the extraction probes may be arranged above the tank.  
         [0033]    As an alternative, the injection probes may be arranged at each side of the tank, as illustrated in detail in FIGS. 3 and 4, as well as in FIG. 1 in dashed lines.  
         [0034]    The injection probes  2 - 4  may be exchanged in operation with the aspiration probes  9 ,  10 .  
         [0035]    As a further alternative, the probes may be arranges so that, as illustrated in FIGS. 3,4, the probes arranged on one side of the tank are only one type of probes, and the probes arranges at the opposite side are the other type of probes. In this way the injection probes and the extraction probes are arranged one opposite the other with respect to the tank.  
         [0036]    Each of the probes  2 ,  4  and  9 ,  10  is provided with an valve  30  which is adapted to put the probe in connection with the line  5  or the line  11 , according to the involved probe.  
         [0037]    This allows a selective activation of each probe  2 - 4  and  9 , 10  and also allows detection of leaks at particular regions of the tank at a time, with the advantage of being able to more precisely locate the leak.  
         [0038]    The compressor  6  is used to inject the air in the injection probes  2 - 4  and the same compressor is used to let the probes  9 ,  10  aspirate the flow. In fact, through line  16  the air flow aspirated by the extraction probes is sent to the drying device  8  and then to the compressor  6 : a closed circuit is thus formed when the valves  18 ,  19  are open and the valve  17  is closes.  
         [0039]    In addition, the injections probes may inject liquid substances and/or vapour substances.  
         [0040]    Still further, the dehumidification function performed by the heating means has also the purpose of increasing the efficiency of the other functions performed by the device, since the reduction of the humidity content of the soil increases the air permeability of the soil.  
         [0041]    Attention is now drawn to the probes driven into the ground, which in the known embodiment, adopted for example in the probes  9  and  10 , which are constituted very simply by a slotted tube, have the disadvantageous characteristic that they allow no operating flexibility since their configuration cannot change at all.  
         [0042]    A probe according to the present invention, which once driven into the ground allows variations to its operating characteristics, is illustrated in FIG. 2.  
         [0043]    With reference to the above figure, the reference numeral  20  designates an outer tubular jacket, which is provided, at its entire wall, with through holes such as  21 ,  22  and is shaped, at the end meant to be arranged inside a manhole, as a spigot joint  23 , which allows connection to a fluid conveyance line.  
         [0044]    The part now described relates substantially to a conventional probe.  
         [0045]    An important characteristic of the present invention is the presence of a tubular core  24 , which has a not holed, solid wall and is shorter than the jacket  20 .  
         [0046]    The core  24  is sliding fit with the inner surface of the jacket  20 , with a fit which allows tight-fit sliding as a consequence of an action applied by an operator to engagement means, such as an upward traction or a downward thrust applied by means of a rod which is in contact with a bar  25  fixed to the upper end of the core; through the friction that occurs between the mutually contacting surfaces of the jacket and the core, the core remains locked in any position in which it is placed.  
         [0047]    The core has, at its lower end, a threaded portion  26  for fixing a closure plug, which can be useful if it is necessary for example to isolate the upper part of the probe from the lower part, which is placed in a waterlogged region.  
         [0048]    [0048]FIGS. 3 and 4 illustrate the operating flexibility of the present invention in the case of probes  27  and  28  arranged proximate to a buried tank  29  in order to inject air into the ground in the vicinity of the tank, with the dual purpose of keeping said ground ventilated and dehumidified, so as to preserve the metal plates from corrosion, and of continuously monitoring the condition of the soil.  
         [0049]    The adoption of probes according to the invention allows to change, very quickly and conveniently, the flow of air in the ground between the injection probe  27  and the extraction probe  28  from the situation shown in FIG. 3 to the one shown in FIG. 4.  
         [0050]    In the case of FIG. 3, the flow is determined by placing, in both probes, the corresponding cores in the uppermost position, so that the holes in the jacket that are located in the lower region remain open; in order to change to the circulation shown in FIG. 4 it is sufficient to push down the core of the probe  27 , thus freeing the holes of the upper region of the jacket, while the position of the core of the probe  28  remains unchanged.  
         [0051]    The combinations that can be provided by placing the core of the probes in different positions, including intermediate ones, are obviously numberless, thus allowing specific choices as a function of the morphology of the ground affected by the treatment; this fact can be important also in view of optimizing the conditions for injecting into the soil substances, such as water or nutrient liquids, added to the air.  
         [0052]    The described invention is susceptible of numerous modifications and variations, all of which are within the scope of the inventive concept.  
         [0053]    Thus, for example, it is possible to heat the input air in order to increase the effectiveness of the treatment and reduce, in the case of fuel tanks, the thermal storage loss; in particular, the heating action can be controlled by means of a thermostat, so as to assuredly obtain air at a higher temperature than the ground.  
         [0054]    This additional condition causes the above-described flow generation method to be particularly effective.  
         [0055]    The tubular core of the probe according to the present invention can also be provided with means of any kind to allow it to move inside the jacket and to place it in the intended position.  
         [0056]    In the practical embodiment of the invention, all the details may be replaced with other technically equivalent elements; the materials employed, as well as the shapes and the dimensions, may also be any according to requirements.