Sampler device for sampling underground water, and associated sampling method

Abstract

The invention relates to a sampler device (10) for sampling underground water, the sampler device (10) being characterized in that it comprises a sampling rod (11) suspended by suspension and extraction means (100) connected to the surface (S) and comprising a tubular intermediate column (12) extending along a longitudinal reference axis (A) between an upper end (13) and a lower end (14), and in that: the upper end (13) comprises a connection interface (23) connected to a circuit (15) connected to one or more pumps (16) for sucking in underground water from the lower end (14), passing through the intermediate column (12), and delivering the sucked-in water up to the surface (S); and in that the lower end (14) comprises a valve (141) configured to open and close a flow channel (142) so as to open and close, respectively, the lower end (14) of the sampling rod (11).

Description

DESCRIPTION SAMPLING DEVICE FOR GROUNDWATER SAMPLING AND ASSOCIATED SAMPLING METHOD TECHNICAL FIELD OF THE INVENTION

[0001] The invention relates, in general, to the technical field of water sampling.

[0002] The invention relates more specifically to a sampling device for groundwater sampling. PREVIOUS STATE OF THE ART

[0003] There are various solutions for carrying out groundwater sampling, each of which is generally adapted to a given environment and / or the nature of the sampling sought.

[0004] Passive sampling devices, such as sampling poles or samplers, are well-known. These allow for sampling the surface layer of the water column, with the exception of automatic, trigger-activated samplers that allow for sampling at greater depths, generally in response to one or more external data points. While such passive sampling devices are practical for occasional or diagnostic sampling, their use for routine water column renewal is impractical.

[0005] Active, submerged sampling devices such as surface pumps or peristaltic pumps are also known. These sampling devices allow for purging or sampling via dip tubes. Their use is limited to a few meters of depth due to the boiling of water at piezometric levels beyond approximately 7 meters. Furthermore, these types of devices Samplers can cause the sample to become depressurized, and therefore potentially alter the characteristics of the sample taken (degassing, isotopic fractionation...).

[0006] Solutions for immersed active sampling devices are also known, for example equipped with submerged or inertial pumps, or even equipped with a hydrosensor.

[0007] Submersible pumps, for example, are generally used for purging or sampling, with depth limits depending on the pump type. Their use is limited to dewatering, particularly if the well's productivity is insufficient relative to the minimum pumping flow rate, due to the device's dewatering. With the exception of "low-flow" devices, their minimum flow rate is often greater than 1 L / min. A major drawback of this type of device is that the movement of the pump blades can break certain molecules, and cavitation at their surface can potentially alter the sample's characteristics (outgassing, isotopic fractionation, etc.).

[0008] Inertia pumps are generally equipped with a valve at the base of the dip tube and allow for sampling in small-diameter, relatively deep boreholes. A vertical reciprocating motion of the pump draws water into the dip tube during its descent, and during its ascent, it closes the valve, preventing the collected water from escaping. However, this reciprocating motion within the borehole can cause significant sediment resuspension, necessitating additional filtration and potentially compromising sample quality.

[0009] In general, it is observed that sampling using submersible pumps carries the risk of disturbing the samples due to their passage through constituent materials: physicochemical exchanges between the water and the materials (pumps, pipes, fittings, etc.), cavitation, passage through pump impellers, etc. The use of a gas with pumps to perform purging is This gas can also compromise a sample when it comes into direct contact with the groundwater sampled. Similarly, groundwater sampling using valve samplers does not allow for the renewal of the water column (resulting in non-representative samples), nor does it allow for the selection of the sampling depth, except by using automatic trigger samplers, which are more complex and therefore more expensive. DESCRIPTION OF THE INVENTION

[0010] The invention aims to remedy all or part of the drawbacks of the state of the art by proposing in particular a solution which allows both the renewal of the water in a borehole and the collection of groundwater samples, undisturbed by pumping systems (depression, cavitation, etc.), at determined depths, according to the recommendations in force, in a manner that is as representative as possible.

[0011] Another objective is to offer a solution simple enough to be used routinely.

[0012] A desired advantage of the solution is also to limit the volumes pumped, in order to limit the extraction of the fine fraction of the formation, in accordance with the recommendations of the authorities.

[0013] To this end, according to a first aspect of the invention, a sampling device for the sampling of groundwater is proposed, the sampling device being characterized in that it comprises a sampling pole suspended by means of suspension and extraction connected to the surface and comprising an intermediate tubular column extending along a longitudinal reference axis between an upper end and a lower end, and in that: the upper end comprises a connection interface connected to a circuit connected to one or more pump(s) to draw groundwater from the lower end, through the intermediate column and pump the drawn water to the surface; the lower end includes a valve configured to open and close a flow channel so as to open and close, respectively, the lower end of the sampling cane.

[0014] Thanks to this combination of features, the sampling device has a sampling probe configured both to replenish the water in a borehole during one phase of use, when it is connected in series with the groundwater suction circuit connected to the pump, and during another phase of use, to collect groundwater samples as representatively as possible without having to pass through a pump. The sample is then contained within the closed sampling probe and can be retrieved after being extracted to the surface. Such a sampling device is therefore designed for implementing the groundwater sampling process described later, which allows for sampling without risk of disturbing the samples.

[0015] In one embodiment, the connection interface at the upper end is directly and mechanically connected to a pipe in a circuit linked to one or more pumps. Groundwater can thus be drawn by the pump(s) from the lower end, passing through the intermediate column, and then through the connection interface at the upper end to be pumped to the surface, guided by the pipes of the circuit. The circuit pipe preferably comprises a flexible hose for connecting the sampling probe to the surface when the sampling probe is immersed in the groundwater, particularly during a groundwater pumping step through the sampling device.Thanks to a direct mechanical connection between the circuit pipe and the upper end, groundwater is guided directly and sequentially from the sampling probe to the pipe, without any intermediate components, to the surface. The connection interface includes, for example, a fitting between the upper end and the pipe.

[0016] In one embodiment, the valve is a non-return valve, preferably consisting of a ball. Such a configuration provides simplicity of operation using well-known physical principles related to the gravitation of the ball without having to use external energy requiring a special energy source.

[0017] According to one embodiment, the upper end comprises a separate upper connecting piece from the intermediate column, the upper connecting piece having a connection interface with an upper end of the intermediate column and comprising the connection interface.

[0018] According to one embodiment, the lower end comprises a lower end separate from the intermediate column, the lower end having a connection interface with a lower end of the intermediate column and delimiting the flow channel.

[0019] According to one embodiment, the upper end connection interface and the lower end flow channel are axially aligned with respect to the reference axis.

[0020] According to one embodiment, the connection interface and the connection interface of the upper connecting piece and / or the connection interface and the flow channel of the lower nozzle are axially aligned with respect to the reference axis of the intermediate column.

[0021] In one embodiment, the valve is configured to be controlled by an actuator accessible from the outside. The valve actuator preferably comprises a movable lever, preferably rotating about an axis orthogonal to the reference axis, between an open and a closed position of the flow channel. Such a lever is particularly simple to implement. Preferably, the lever is manual, that is, it is configured to be moved between its closed and open positions of the flow channel by manual actuation. The lever is preferably elastically constrained by energy storage means, for example, a torsion spring, towards an equilibrium position corresponding to the closed position.

[0022] In one embodiment, the upper connecting piece and / or the lower end fitting is / are manufactured as a single unit. For example, the corresponding part can be manufactured using an additive manufacturing process. In the case of the lower end fitting, for instance, a lever is produced directly using the additive manufacturing process and positioned directly onto the end fitting, thus simplifying the manufacturing process as much as possible.

[0023] In one embodiment, the upper connecting piece and the lower end are connected by means of connecting elements separate from the intermediate column. These connecting elements preferably comprise suspension cables extending parallel to the reference axis and around the intermediate column in its assembled position. In this way, in the operating position, the tubular column rests on the lower end, which is itself suspended from the upper connecting piece by means of the connecting elements. In practice, it is noted that no sealing means are required for the sampling device to function.Such a construction is also simple and reliable and allows, for good maintenance, to replace if necessary any of the parts such as the upper connecting piece, the lower end, the tubular column or the connecting elements, which minimizes maintenance costs.

[0024] In one embodiment, the connecting elements are at least two, preferably at least three, distributed evenly radially around the sampling cane, or around its reference axis. In this way, even tightening of the elements is ensured.

[0025] Of course, the connecting elements can include different means of connection than cables. For example, they can be wires or ropes of different types, or even rods.

[0026] According to one embodiment, the upper connecting piece defines an interior space within which are housed hooks configured to support, in the assembled position for use, a portion of the end attachment upper part of the intermediate column, the attachment portion preferably including at least one spacer extending orthogonally to the reference axis.

[0027] In one embodiment, the upper connecting piece has, relative to the reference axis, a first angular assembly position with the upper end of the intermediate column achieved by axial sliding of the upper end of the intermediate column within the connecting interface of the upper connecting piece, and a different angular assembly position in which, after pivoting the upper connecting piece relative to the intermediate column, the hooks in the upper connecting piece engage with the hook portion of the intermediate column. This configuration allows the tubular column to be suspended at its upper end, which is engaged with the upper connecting piece.

[0028] According to one embodiment, the sampling device includes sealing means between the upper connecting piece and the intermediate column and / or between the lower end and the intermediate column.

[0029] According to another aspect of the invention, it relates to a method of sampling groundwater by a sampling device having all or part of the characteristics described above, the sampling method comprising at least the following steps: immersion of the sampling rod (11) at least in groundwater, for example through a borehole; pumping of groundwater through the sampling device so as to purge the sampling rod, the groundwater being drawn by the pump(s) from the lower end, passing through the tubular column and then being pumped at least in part to the surface; stopping of the pumping; closing of the valve so as to block the groundwater sample contained in the sampling rod; extraction from the groundwater surface of the sampling device containing the groundwater sample taken; recovery of at least part of the groundwater sample taken contained in the sampling pole.

[0030] With this method, once purging is complete and the physicochemical parameters have stabilized, pumping is stopped, and the sample is held in the sampling tube without passing through the pump. This makes it possible to obtain a representative sample of the environment, eliminating the potential effects of the pumps and avoiding the limitations and influences on samples described in the prior art.

[0031] In one embodiment, the step of recovering at least a portion of the groundwater sample collected and contained in the sampling pole includes a step of actuating an externally accessible actuator configured to control the valve at the lower end of the sampling pole. Thus, simply opening said valve by actuating said actuator allows for the easy collection of the sample once the sampling pole has been extracted from the groundwater at the surface.

[0032] The pumping stage is preferably carried out without applying direct pneumatic pressure to the groundwater, so as not to risk rendering it unfit for its intended use. BRIEF DESCRIPTION OF THE FIGURES

[0033] Other features and advantages of the invention will become apparent from the reading of the following description, with reference to the attached figures, which illustrate: figure 1: a schematic view of a sampling device according to one embodiment; figure 2: a view of an embodiment of the suspension and extraction means connected to the surface and from which a sampling rod is intended to be suspended; Figure 3: A view of a sampling cane according to one embodiment; Figure 4: An exploded isometric perspective view of an upper connecting piece of an upper end of the sampling cane of Figure 3 and of part of an intermediate tubular column; Figure 5: A sectional view AA of Figure 4; Figure 6: A side view of Figure 4; Figure 7: A sectional view BB- of Figure 6; Figure 8: A sectional view CC of Figure 6; Figure 9: An isometric perspective view of a lower tip of a lower end of the sampling cane according to Figure 3; Figure 10: An axial sectional view about a vertical reference axis of the lower tip of Figure 9; Figure 11: A sectional view DD of Figure 10.

[0034] For clarity, identical or similar elements are identified by identical reference symbols across all figures. DETAILED DESCRIPTION OF A METHOD OF IMPLEMENTATION

[0035] Figures 1 and 2 illustrate a sampling device 10 according to one embodiment, the sampling device 10 being adapted for sampling groundwater.

[0036] The sampling device 10 includes a sampling rod 11 forming a sampling tube and suspended by suspension and extraction means 100 connected to the surface S.

[0037] The suspension and extraction means 100 include, in particular, at least one tripod or a gantry 101 for slinging the sampling rod 11 to the surface S. The associated sling 102 is suspended from a suspension point 103 located at the level of a borehole 104 from which a sample is to be taken. The suspension point 103 may be equipped with a right-angle means such as a pulley. In this case, the sling extends to a remote anchor point; that is, a taut end of the sling extends between the suspension point 103 formed at the pulley and a remote anchor point (not shown), for example, to the ground. This anchor point may also include a means of storing a reserve of sling, for example equipped with a drum, these means being motorized or manual, to allow the winding and unwinding of the cable 102.In a particular configuration, such a cable reserve storage means can be placed directly at the suspension point 103 opposite the drilling point 104. In this configuration also, these means can be motorized and / or manual, for example by means of a crank as the main means, or even as a secondary means to compensate for example in the event of a possible failure of the motor or geared motor.

[0038] In this way, the sling 102 is connected: on the one hand to motorized and / or manual means located on the surface S to allow the associated cable to be deployed or wound up, and on the other hand, to the sampling rod 11 so as to be able to lower or raise said sampling rod 11 in the borehole 104, i.e. in the borehole or a casing of sovereign delimiting the borehole.

[0039] Using a sling 102 to lift the sampling pole 11 limits any direct pulling force on a drainage pipe 106. Furthermore, such a sling 102 is preferably configured to maintain chemical neutrality to avoid any interaction. It should be noted that the sling 102 used can, for example, be made of a cable. According to another variant, the sling 102 may include a cable of a material of choice (nylon, steel, etc.), a rod such as a threaded rod, a rope, a chain or any other wire.

[0040] The sampling pole 11 comprises a tubular intermediate column 12 extending along a longitudinal reference axis A between an upper end 13 and a lower end 14. The reference axis A extends vertically in the operating position of the sampling pole 11, when it is suspended from the sling 102 in the borehole 104. The sampling pole 11 is designed to be immersed in groundwater during sampling, specifically in an area deep enough to be submerged in the saturated ZI zone of the aquifer.

[0041] A sampling rod 11 according to the invention is illustrated in more detail in Figure 3. The tubular intermediate column 12 has a cylindrical profile. A constant cross-section of the intermediate column 12 ensures ease of use when the sampling rod 11 is moved within the borehole, and also facilitates its guidance during vertical movements. Furthermore, a circular cross-section of the intermediate column 12 ensures proper water flow within it, and externally adapts more easily to boreholes with a circular cross-section resulting directly from the drilling tools used.

[0042] As mentioned previously, the intermediate tubular column 12 extends axially between its upper end 13 and lower end 14.

[0043] Figures 4 to 8 illustrate details of the upper end 13 of the sampling cane 11 of Figure 3.

[0044] The upper end 13 of the sampling pipe 11 includes a connection interface 23 connected to a circuit 15 linked to one or more pumps 16, connected in series in the case of a plurality of pumps, for drawing groundwater from the lower end 14, passing through the intermediate column 12 and discharging the aspirated water to the surface S via the discharge pipe 106. In this embodiment, the upper end 13 includes an added piece forming A top connecting piece 30, separate from the intermediate column 12. This top connecting piece 30 ensures the connection between the intermediate column 12 and the circuit 15. The top connecting piece 30 has, on one side, a connection interface 31 with an upper end 121 of the intermediate column 12 and, on the other side, the connection interface 23. The top connecting piece 30 extends axially between two axial ends formed by the connection interfaces 31 and 23.

[0045] Figures 9 to 11 illustrate details of the lower end 14 of the sampling cane 11 of Figure 3.

[0046] The lower end 14 of the sampling tube 11 includes a flow channel 142 in communication with the environment external to the sampling tube 11. This lower end is provided with a valve 141 configured to open and close the flow channel 142 so as to open and close, respectively, the lower end 14 of the sampling tube 11. In this embodiment, the lower end 14 includes an added part forming a lower end piece 40, separate from the intermediate column 12, the lower end piece 40 having a connection interface 41 configured to ensure its connection with a lower end 122 of the intermediate column 12. This lower end piece 40 makes it possible to close, from below, the intermediate column 12 while allowing fluidic communication of water between an internal space of the sampling tube 11 and its external environment.The valve 141, in particular a non-return valve, ensures the opening of the sampling tube 11. This opening of the flow channel 142 by the valve 141 occurs, in particular, when the tube is submerged for groundwater sampling, when the pump(s) 16 are drawing groundwater, and when the sampling tube 11 is handled at the surface, notably to retrieve the sample and transfer it into a suitable container (not shown). The lower end 40 has, on the one hand, a connection interface 41 with a lower end 122 of the intermediate column 12 and, on the other hand, the flow channel 142 which it defines. The lower end 40 extends axially between two ends formed by the connection interface 41 and the flow channel 142.

[0047] In a vertical reference position, where the reference axis A is parallel to a vertical axis, the lower end piece 40 is located below the intermediate column 12 and the upper connecting piece 30 is located above it, with the intermediate column 12 interposed between these two components 30, 40. For these two components 30, 40, their associated connecting interface 31, 41 includes a complementary sleeve for the associated upper end 121 or lower end 122 of the intermediate column 12, such that said associated upper end 121 or lower end 122 can be inserted into the complementary sleeve of the corresponding connecting interface 31, 41. In an alternative embodiment, a shrink fit, i.e., a tight fit, of the components of the lower end piece 40 and / or the upper connecting piece 30 with the associated end 121, 122 of the intermediate column 12 can be performed to secure them.

[0048] Other means of fastening, complementary or in combination, can obviously be considered. In the illustrated embodiment, the tubular intermediate column 12 is placed on the lower end piece 40, in particular on an internal shoulder 43 of the lower end piece 40, i.e., projecting inwards from the lower end piece 40. The shoulder 43 is dimensioned to receive, in planar contact extending here in a plane parallel to a horizontal plane perpendicular to the vertical axis, a lower edge of the lower end 122 of the intermediate column 12. This continuous planar contact defines a closed contour contributing to the sealing of the assembly.

[0049] In this way, in the vertical reference position, the tubular intermediate column 12 rests on the lower end piece 40. In addition, the upper connecting piece 30 and the lower end piece 40 are connected together by connecting elements 50 separate from the intermediate column 12 so that the lower end piece 40 is suspended from the upper connecting piece 30.

[0050] The connecting elements 50 include, in particular, suspension cables extending parallel to the reference axis A around the intermediate column 12 in its assembled position. At one lower end, the cables (not shown) are attached to eyelets 51 located on the outer periphery of the lower end piece 40. Such eyelets 51 can each be simply a single hole. To ensure the stability of the cables with the lower end piece 40, a portion of the lower end is housed in sheaths 52 forming vertical guide channels and also located on the outer periphery of the lower end piece 40. Such a sheath 52 is provided axially and vertically above each attachment eyelet 51. The cables are tensioned to the upper connecting piece 30, which is also equipped with vertical axial sheaths 52 located on the outer periphery of said upper connecting piece 30.Each connecting cable is therefore tensioned at least between the upper connecting piece 30 and the lower end fitting 40, where it is guided by a pair of associated sheaths 52 provided on each of the two attachments 30, 40. Each pair of sheaths is aligned along an axis parallel to the reference axis A, so that the connecting cables are kept parallel to the reference axis A, i.e., vertically, in the vertical reference position, and distributed around the reference axis A. In this embodiment, the sheaths are located on the outer periphery of the upper end fittings 13 and lower end fittings 14, namely the upper connecting piece 30 and the lower end fitting 40, respectively. However, other configurations are possible. For example, the sheath can be integrated into the body of the attachment 30, 40 so that only its entry and / or exit opening is visible.In this configuration, the guide sleeves 52 have no protrusion outside the intermediate column 12, thus limiting the risk of snagging on the inside of the borehole. The use of the sampling device 11 is therefore facilitated. Alternatively, the eyelets 51 can be located entirely inside the associated add-on 30, 40 relative to its outer periphery or flush with its outer surface so as not to create any protrusion.

[0051] One end of each of the connecting cables can be attached, for example, to cable tensioning means (not shown). In this case, the sling 102 can be attached directly to the upper connecting piece 30. In another In this configuration, these connecting cables between the upper connecting piece 30 and the lower end 40 can each be attached directly to the sling 102.

[0052] Instead of several connecting cables, each linking the upper connecting piece 30 and the lower end 40 separately, the number of connecting cables can be reduced. For example, a single cable can be used, repeatedly and alternately linking the upper connecting piece 30 and the lower end 40. In this case, the connecting cable can pass successively and alternately through all the sheaths 52 between each end 13, 14. Each end of the cable can be held securely by crimping a fastener, such as a flattened metal tube. Alternatively, two connecting cables can be used, each cable linking the upper connecting piece 30 and the lower end 40 separately twice, like a loop, for example, a "U" shape.As in the previous example, each connecting cable is held securely in place by crimping its ends. Generally, using multiple connecting cables provides redundancy, thus improving the device's safety in the event of a cable break. Again, these cables can be replaced with any other wire or flexible means to form such a loop.

[0053] The lower end fitting 40, which defines the flow channel 142, is configured to be opened and closed by the non-return valve 141. The valve 141 consists of a ball 141' with negative buoyancy, meaning that the ball is heavier than the water it displaces when submerged. Preferably, this ball 141' is metallic, meaning it is made of one or more metals. In this way, in a vertical reference position, the ball 141' naturally settles at the bottom of the sampling tube 11, inside the lower end fitting 40, whether the sampling tube 11 is submerged or not. The flow channel 142 has a smaller cross-section than the ball 141', so the flow channel 142 is configured to be closed by the ball 141'.Preferably, one end of the channel 142 opening into the interior space of the sampling tube 11 has a flared shape towards the interior of the sampling tube 11, the flow channel 142 having a circular section of smaller diameter than that of the column. Intermediate 12. This flared inner portion of the sampling pipe 11 is concave so that the decrease in cross-section of the intermediate column 12 towards the flow channel 142 is gradually guided by concave inner walls, i.e., walls whose hollow shape is radially open outwards. In this way, a shape is ensured that guarantees better stability for the ball 141' when it is in the equilibrium position of closing the flow channel 142. When the pump(s) 16 are activated to draw groundwater, the vacuum allows water to infiltrate through the flow channel 142 from the outside into the sampling pipe 11. Since the ball 141' does not obstruct this flow, it is moved along with the flow of water flowing in the sampling pipe 11.When the pump(s) 16 are stopped, the mass of the ball 141' is such that it descends vertically to the bottom of the sampling tube 11, to come to rest in the flared inner portion of the end of the channel 142 inside the lower tip 40.

[0054] The valve 141 is configured to be controlled by an actuator 42 accessible from the outside. The actuator 42 of the valve 141 has a movable lever, rotating about a horizontal axis A' orthogonal to the reference axis A such that the lever 42 is movable between an open position and a closed position of the flow channel 142. The lever 42 extends at least between a gripping portion accessible on the outside of the lower end 14 of the sampling tube 11, and an actuating portion located at least partially within the flow channel 142.

[0055] In the closed position, the lever 42 is positioned so that its actuating portion is away from the ball 141', vertically below it. In this position, the ball 141' can rest in the flared inlet of the flow channel 142 to close it.

[0056] In the open position, lever 42 is positioned so that its actuating portion is placed in the path of the ball 141' to its closed position. The actuating portion comes into contact with ball 141', displacing it from its closed position and forcing the opening of the flow channel 142. At the surface, lever 42 can be actuated to retrieve the sample while keeping the sampling tube 11 vertical. In other words, and generally speaking, the actuator allows the lower orifice of the sampling cane 11 to be cleared, namely the flow channel 142, which is obstructed by a valve, here constituted by the ball 141'.

[0057] As described above, the upper connecting piece 30 has a connecting interface 31 forming a complementary sleeve to the upper end 121 of the intermediate column 12 so that the upper end 121 can fit into said sleeve.

[0058] An additional fastening means is also associated with this fitting. In particular, the upper end 121 of the intermediate column 12 is provided with a fastening mechanism comparable to a bayonet fitting. Specifically, the upper connecting piece 30 defines an internal space 32 within which are housed hooks 33 configured to support, in the assembled operating position, a mounting portion 123 of the upper end 121 of the intermediate column 12. The mounting portion 123 includes, in particular, at least one transverse spacer or lug extending orthogonally to the reference axis A.

[0059] The fixing of the upper connecting piece 30 with the intermediate column 12 is ensured by: a fitting of the upper end 121 of the intermediate column 12 into the connecting interface 31, and by a rotation of the upper connecting piece 30 relative to the intermediate column 12 so as to move the spacers forming the hooking portion 123 into the hooks 33 of complementary shape.

[0060] In other words, the upper connecting piece 30 has, relative to the reference axis A: a first angular assembly position with the upper end 121 of the intermediate column 12 by axial sliding from the upper end 121 of the intermediate column 12 in the connecting interface 31 of the upper connecting piece 30 to fit them together, and a different angular assembly position in which after pivoting the upper connecting piece 30 relative to the intermediate column 12, the hooking portion 123 of the intermediate column 121 is engaged with the hooks 33 in the upper connecting piece 30.

[0061] A configuration in which the lower end 14 and upper end 13 of the sampling cane are formed by separate parts of the tubular intermediate column 12, namely respectively the lower tip 40 and the upper connecting piece 30, with in addition simple and effective removable fixing means, makes it possible to ensure efficient and rapid cleaning of the internal space of the sampling cane 11. This also makes maintenance easier.

[0062] To facilitate the flow of groundwater aspirated in the sampling tube 11, while ensuring good verticality during its use, the connection interface 23 of the upper end 13 and the flow channel 142 of the lower end 14 are aligned axially with respect to the reference axis A. Similarly, the connection interface 31 and the connection interface 23 of the upper connecting piece 30 and the connection interface 41 and the flow channel 142 of the lower end 40 are aligned axially with respect to the reference axis A of the intermediate column 12.

[0063] It should be noted that these means of fixing the lower end 40 and the upper connecting piece 30 to the tubular intermediate column 12 are removable and do not require additional sealing. However, depending on the quantities of groundwater extracted, it may be desirable to use such sealing, particularly between the upper connecting piece 30 and the intermediate column 12 and / or between the upper connecting piece 30 and the intermediate column 12. These sealing means may include in particular at least one O-ring.

[0064] In this embodiment, the upper connecting piece 30 and the lower end piece 40 are each formed as a single unit from plastic material(s), in particular obtained by additive manufacturing. This process also allows for the simple and inexpensive manufacture of the lower end piece 40, including the lever 42 mounted on its axis A' with the body of the lower end piece 40.

[0065] The groundwater sampling process using the sampling device 10 as described above will be better understood in light of the following description.

[0066] After drilling well 104, the suspension and extraction means 100 are installed. For example, a tripod or a gantry 101 forming a support is positioned at the borehole 104. A sampling rod 11 is then suspended from this support 101, allowing the sampling rod 11 to be deployed in the borehole 104 and extracted.

[0067] The sampling probe 11 is then deployed in the borehole 104 until it is completely submerged in the groundwater from which the sample is to be taken. Groundwater is then pumped through the sampling device 10 to purge the sampling probe 11. During this immersion, the sampling probe 11 is immersed in unfiltered groundwater. The sampling probe 11 is suspended only by the sling 102 and is free laterally or radially, meaning it is not held laterally. The sampling device 10 allows groundwater to be pumped from the borehole to a given depth using at least one pump 16, for example, a low-flow pump, via the sampling probe 11 fixed below this pump 16, through which the pumped water flows.Indeed, during this purging, groundwater is sucked up by at least one pump 16, from the lower end 14 of the sampling pipe 11, passing successively through the tubular column 12 and the end. upper 13 then pumped at least in part to the surface S by the circuit 15 connected to the pump(s) 16. The circuit 15 takes the form of a pipe along the path of which two pumps 16 are positioned.

[0068] In the case of deep piezometric levels, intermediate booster pumps can be added along the circuit, as illustrated, for example, in Figure 1, for instance, every 8 meters. The spacing of the pumps depends on the characteristics of the booster pumps, in order to compensate for the lifting capacities of the pumps used. These pumps can be adjusted before immersion, for example, using at least one adjustment knob, to regulate the pump start-up to the desired value. Alternatively, or in combination, remote control means for the pump(s) can be provided.

[0069] At least one of the pumps 16 must be submerged for the entire duration of the sampling operation. If there are multiple pumps 16, this must be at least the pump closest to the sampling pipe 11 in relation to the circuit 15. In practice, depending on the type of pump used, it is possible to submerge the pump 16 only during priming and then have it emerge due to the drawdown of the water table. This option allows, in the case of shallow water levels, for the sampling pipe 11 not to be lowered to the bottom of the structure, which could be detrimental in terms of suspended solids.

[0070] When the purging is sufficient to ensure a representative sample is obtained, the pumping is stopped. The pump(s) 16 are stopped. Stopping the pumping automatically closes the valve 141 because the ball 141' falls back to the bottom of the sampling tube and seals the sampling channel 142. The valve 141 thus blocks the groundwater sample contained in the sampling tube 11. The groundwater in the sample, even though it is contained in the sampling tube 11 and in the path of the pumped water, has not passed through the pumps and is therefore not disturbed by them.

[0071] Once the groundwater sample is secured in the sampling tube 11, said sampling tube 11 is retrieved by means of suspension and extraction 100 until extraction to the surface S from the groundwater of the groundwater sample taken.

[0072] Finally, at least part of the groundwater sample taken from the sampling pole 11 is then recovered, in particular by means of the movable lever 42 actuated from its closed position to the open position.

[0073] During the sampling process, from the immersion stage to the extraction stage at the surface of the sampling rod 11, said sampling rod 11 is only suspended from the sling 102. This sling 102 thus constitutes its only support.

[0074] Given that sample retrieval requires the complete removal of the sampling tube 11, and does not allow for repeating the operation while ensuring an identical sample, it is necessary to size the sampling tube 11 according to the required volume. For example, a sample volume of 2 liters may be necessary to perform an analysis. Considering potential losses, such as a leak at the base of the sampling tube 11, and the physicochemical measurements to be carried out, a larger volume, for example 3 liters, may be chosen.

[0075] Thus, a user can choose the height of the sampling tube 11 based on a diameter to obtain a predetermined usable volume. Specifically, the diameter of the sampling tube 11, particularly the tubular intermediate column 12, can be adapted to match the diameter of a pump, for example, a low-flow pump. For a diameter of 45 mm, for instance, the height of the sampling tube 11 should be approximately 1.90 m. To better suit conventional boreholes, most of which measure between 80 and 105 mm in diameter, a predetermined diameter of 70 mm could be used, with the sampling tube 11 extending to a height of 78 cm to obtain a usable volume of 3 L. The sampling tube 11 thus defines a sample containment space with a predetermined usable volume. A volume of groundwater sampled to form the sample is contained within this sampling tube 11.The internal containment space for the sample is closed. laterally by the tubular intermediate column 12, inferiorly by the lower end 40 of the lower end 13 in a closed position of the flow channel 141, and superiorly by the upper connecting piece 30. This upper connecting piece 30 is only open towards the circuit 15 at the level of its connection interface 23 which is connected to the circuit 15. However, during the extraction step at the surface S of the groundwater sampled and contained in the sampling tube 11, and due to the pumping step carried out previously, said circuit 15 is filled with groundwater locally homogeneous with the nature of the sample (at the level of the connection interface 23), which is therefore not of a nature to disturb the sample taken and contained in the sampling tube 11.Indeed, once the pumping is stopped, the groundwater contained in circuit 15 will remain there without being further drawn in and will also be retained by the closed position of the flow channel 141. In this way, the sampling tube 11 is closed from the external environment, particularly during the extraction steps at the surface and then the recovery of the sample taken from inside the sampling tube 11.

[0076] Thanks to the described invention, the sampling device 10 represents a device for representative sampling of undisturbed groundwater.

[0077] On the one hand, the collected sample does not pass through the pump(s): due to the absence of cavitation usually generated by pressure, the sampling device 10 preserves the species in solution (dissolved gas, large molecules).

[0078] Furthermore, the collected sample does not come into contact with the pipes or metal parts, but only with the sampling tube 11 and the inert parts used to operate it, such as the lower end 14 and upper end 13, the lower nozzle 40, the upper connecting piece 30, and the tubular intermediate column 12. The sampling device 10 allows the sampling tube 11 to be emptied without contact with unrinsed parts, as the parts enabling the emptying of the sampling tube 11 are integrated into the base of the sampling tube 11, specifically at the lower nozzle 40, and are operated without any contact with water.

[0079] Furthermore, water renewal in the borehole is possible and ensured through the sampling pipe 11. Finally, water sampling is made possible at a given depth by limiting the vertical mixing of waters in the borehole.

[0080] The sampling device 10 thus offers an economical solution for collecting undisturbed, representative samples. This economy is achieved in particular by the fact that certain components exist and are widely available, such as the pumps and the tubular intermediate body, and that the sampling probe 11 is easy to assemble when it is composed of several elements with parts 30 and 40 attached to its ends.

[0081] It should be noted that the sampling device 10 according to the invention could be used in a general way for the sampling of fluids whose exchange with the atmosphere is to be limited, and more particularly samples intended for the search for large molecules, such as Polycyclic Aromatic Hydrocarbons (PAHs), pesticides, etc., which could thus not be influenced by the pumps 16.

[0082] Naturally, the invention described above is by way of example. It is understood that a person skilled in the art is capable of carrying out different embodiments of the invention without departing from its scope.

[0083] It is emphasized that all features, as they are apparent to a person skilled in the art from this description, the drawings and the attached claims, even if in practice they have only been described in relation to other specific features, both individually and in any combinations, may be combined with other features or groups of features disclosed herein, provided that this has not been expressly excluded or that technical circumstances render such combinations impossible or meaningless.

Claims

CLAIMS Method of groundwater sampling by a sampling device (10) for the sampling of groundwater, the sampling device (10) comprising a sampling pole (11) suspended by suspension and extraction means (100) connected to the surface (S) and comprising a tubular intermediate column (12) extending along a longitudinal reference axis (A) between an upper end (13) and a lower end (14),: the upper end (13) comprising a connection interface (23) connected to a circuit (15) connected to one or more pump(s) (16) for drawing groundwater from the lower end (14), passing through the intermediate column (12) and pumping the drawn water to the surface (S);the lower end (14) comprising a valve (141) configured to open and close a flow channel (142) so as to open and close, respectively, the lower end (14) of the sampling rod (H), the sampling method being characterized in that it comprises at least the following steps: immersion of the sampling rod (11) at least in groundwater, for example through a borehole (104); pumping of groundwater through the sampling device (10) so as to purge the sampling rod (11), the groundwater being drawn by the pump(s) (16) from the lower end (14), passing through the tubular column (12) and then pumped at least partially to the surface (S); stopping the pumping; closing of the valve (141) so as to block the groundwater sample contained in the sampling rod (11); Extraction at the surface (S), from groundwater, of the sampling device (10) containing the groundwater sample; recovery of at least a portion of the groundwater sample contained in the sampling rod (11). A groundwater sampling method according to claim 1, characterized in that the step of recovering at least a portion of the groundwater sample contained in the sampling rod (11) comprises a step of actuating an externally accessible actuator configured to control the valve (141) at the lower end (14) of the sampling rod (11). A sampling device (10) designed for carrying out the groundwater sampling method according to any one of the preceding claims.Sampling device (10) according to claim 3, characterized in that the valve (141) is a non-return valve, preferably consisting of a ball (141'). Sampling device (10) according to claim 3 or 4, characterized in that the upper end (13) comprises an upper connecting piece (30) separate from the intermediate column (12), the upper connecting piece (30) having a connection interface (31) with an upper end (121) of the intermediate column (12) and comprising the connection interface (23). Sampling device (10) according to any one of claims 3 to 5, characterized in that the lower end (14) comprises a lower end (40) separate from the intermediate column (12), the lower end (40) having a connection interface (41) with a lower end (122) of the intermediate column (12) and defining the flow channel (142).

7. Sampling device (10) according to any one of claims 3 to 6, characterized in that the connection interface (23) of the upper end (13) and the flow channel (142) of the lower end (14) are axially aligned with respect to the reference axis (A).

8. Sampling device (10) according to the preceding claim dependent at least on claim 5 and / or 6, characterized in that the connection interface (31) and the connection interface (23) of the upper connecting piece (30) and / or the connection interface (41) and the flow channel (142) of the lower end (40) are axially aligned with respect to the reference axis (A) of the intermediate column (12).

9. Sampling device (10) according to any one of claims 3 to 8, characterized in that the valve (141) is configured to be controlled by an actuator (42) accessible from the outside, the actuator (42) of the valve (141) preferably comprising a movable lever, preferably rotating about an axis (A') orthogonal to the reference axis (A), between an opening position and a closing position of the flow channel (141).

10. Sampling device (10) according to any one of claims 3 to 9 dependent at least on claims 3 and 4, characterized in that the upper connecting piece (30) and the lower end (40) are connected together by connecting elements (50) distinct from the intermediate column (12), the connecting elements (50) preferably comprising suspension cables extending parallel to the reference axis (A) and around the intermediate column (12), in the assembled position.

11. Sampling device (10) according to any one of claims 3 to 10 dependent at least on claim 3, characterized in that the upper connecting piece (30) delimits an internal space (32) within which are housed hooks (33) configured to support, in the assembled position of use, a hooking portion (123) of the upper end (121) of the intermediate column (12), the hooking portion (123) preferably comprising at least one spacer extending orthogonally to the reference axis. Sampling device (10) according to claim 11, characterized in that the upper connecting piece (30) has, relative to the reference axis (A), a first angular position for assembly with the upper end (121) of the intermediate column (12) by axial sliding of the upper end (121) of the intermediate column (12) in the connection interface (31) of the upper connecting piece (30), and a different angular assembly position in which, after pivoting of the upper connecting piece (30) relative to the intermediate column (12), the hooks (33) in the upper connecting piece (30) engage with the hooking portion (123) of the intermediate column (121). Sampling device (10) according to any one of claims 3 to 12 dependent at least on claims 5 and 6, characterized in that it comprises sealing means between the upper connecting piece (30) and the intermediate column (12) and / or between the lower end (40) and the intermediate column (12).

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