Abstract:
A method of retrieving a liquid sample comprises providing a portable lysimeter including a semi-permeable membrane and a chamber in fluid communication with the semi-permeable membrane; making a hole at a site from which a liquid sample is desired; evacuating the chamber by applying a vacuum to the chamber; lowering the portable lysimeter into the hole; obtaining a sample in the chamber; and retrieving the lysimeter from the bore; wherein it is not necessary to backfill the bore. A portable lysimeter includes a semi-permeable member and a chamber in fluid communication with the semi-permeable membrane.

Description:
[0001] The United States Government has rights in this invention disclosed under contract number DE-AC07-99ID13233 between the U.S. Department of Energy and Bechtel BWXT Idaho, LLC. 
     
    
     
       TECHNICAL FIELD  
         [0002]    The invention relates to suction samplers and lysimeters. The invention also relates to methods of obtaining liquid samples from wells.  
         BACKGROUND OF THE INVENTION  
         [0003]    As understanding of the effects of soil and water contamination advances, it is increasingly desirable to facilitate groundwater sampling and analysis. Various methods have been employed to extract a soil water sample, including extraction of a soil core, introduction of vacuum-based or absorptive devices or materials, use of suction lysimeters, solution samples, and other methods. There are several types of lysimeters including weighing lysimeters and suction lysimeters. The term “lysimeter,” as used below, refers to a suction lysimeter.  
           [0004]    A suction lysimeter is a hydrological instrument used to sample liquids or monitor in soil or like substrates. The lysimeter accomplishes this function by application of vacuum or pressure gradient principles such that the liquid of interest is drawn toward the lysimeter permitting collection of a liquid sample. A filter arrangement is frequently employed in conjunction with a lysimeter such that undesired particulate or other solids are not accumulated with the desired sample liquid.  
           [0005]    A lysimeter is primarily a sampling device but can also be used to provide an indication of the water pressure (positive or negative). This is done by applying a vacuum, allowing the sampler to pressure equilibrate with the surrounding material being sampled, and then retrieving the sampler to land surface and quickly connecting to a pressure measurement device to obtain an estimate of the in situ soil water potential.  
           [0006]    The desired sample liquid is sometimes present only in very thin layers or the material to be sampled may be unsaturated (pores are not filled to capacity with water) and it may be desired to extract liquid samples at various depths within the region of interest; this introduces the difficulty of collecting larger volume liquid samples from the borehole walls of uncased wells at intermediate depths. Another difficulty that is encountered is that the desired liquid may not be flowing freely within the soil but may be held in place by capillary forces. This condition requires the use of vacuum or hydraulic gradient forces to overcome the capillary action and secure the desired sample from its present location, be the sample region saturated or unsaturated.  
           [0007]    Liquid sampling with a non-permanent device is performed using several techniques. An absorbent technique (sponge or filter paper) can be used, however this provides small volume samples that are often mixed (contaminated) with sediment/foreign debris.  
           [0008]    Prior art devices utilize direct burial or insertion of lysimeter devices into direct contact with the soil region of interest. For example, U.S. Pat. No. 4,759,227 to Timmons teaches of a direct burial method at the sampling location, utilizing a backfill arrangement of bentonite and silica slurry located below, around and above the installed lysimeter. Additional detail is given by Timmons as to the preparation of filter material from a fluoroplastic resin.  
           [0009]    In U.S. Pat. No. 4,923,333 to Timmons, the inventor reveals a leak detection scheme utilizing lysimetery at landfills and similar locations. In this case, complete contact burial of the lysimeter(s) is again disclosed.  
           [0010]    U.S. Pat. No. 5,000,051 to Bredimeier discloses a lysimeter probe introduced into the ground via force placed upon a horizontal rod or shaft. The instrument is pressed into intimate hydraulic contact with the sediment to be sampled.  
           [0011]    U.S. Pat. No. 5,465,628 to Timmons discloses sampling at multiple depths through the installation of a tube body into which a second mechanism may be inserted for extraction of liquids at a level coinciding with any one of several permeable zones located along the length of the installed tube. 
       
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0012]    Preferred embodiments of the invention are described below with reference to the accompanying drawings, which are briefly described below.  
         [0013]    [0013]FIG. 1 is a front elevational schematic showing a suction bailer in accordance with one embodiment of the invention in use in a well.  
         [0014]    [0014]FIG. 2 is a perspective view of a suction bailer in accordance with an alternative embodiment of the invention.  
         [0015]    [0015]FIG. 3 is a sectional view taken along line  3 - 3  of FIG. 2.  
         [0016]    [0016]FIG. 4 is a perspective view, partly in section, of a suction bailer in accordance with an alternative embodiment of the invention.  
         [0017]    [0017]FIG. 5 is an exploded view of a suction bailer and detachably coupled evacuation apparatus in accordance with another alternative embodiment.  
         [0018]    [0018]FIG. 6 is a elevational view, partly in section, of a deep lysimeter in accordance with another embodiment of the invention.  
         [0019]    [0019]FIG. 7 is a bottom view of the deep lysimeter of FIG. 6.  
         [0020]    [0020]FIG. 8 is a front elevational view of a suction lysimeter for an uncased well in accordance with another embodiment of the invention, including semi-permeable member assemblies and a water reservoir.  
         [0021]    [0021]FIG. 9 is a rear view of a semi-permeable member assembly included in the lysimeter of FIG. 8.  
         [0022]    [0022]FIG. 10 is a side view of the semi-permeable member assembly of FIG. 9.  
         [0023]    [0023]FIG. 11 is a front elevational view of the suction lysimeter of FIG. 8 with semi-permeable member assemblies removed.  
         [0024]    [0024]FIG. 12 is a cut away view of the suction lysimeter of FIG. 8 showing inflation of the bladder. 
     
    
     SUMMARY OF THE INVENTION  
       [0025]    The invention provides a method of retrieving a liquid sample comprising providing a portable lysimeter including a semi-permeable member and a chamber in fluid communication with the semi-permeable member; providing a hole into the earth at a site from which a liquid sample is desired; applying a vacuum pressure to the chamber; lowering the portable lysimeter into the bore; obtaining a liquid sample in the chamber; and retrieving the lysimeter from the bore; wherein it is not necessary to backfill the hole.  
         [0026]    Another aspect of the invention provides a portable lysimeter, comprising a tube having an inner surface and an outer surface, a first end, and a second end, and defining a chamber; a semi-permeable member bonded to the first end of the tube; a plug sealing the second end of the tube, the plug having an aperture through it in fluid communication with the chamber; a vacuum line in fluid communication with the aperture and in fluid communication with the chamber via the aperture; a valve in the vacuum line; and line connection structure attached to the lysimeter wherein the lysimeter may be retrieved from the sampling location.  
         [0027]    Another aspect of the invention provides a portable lysimeter comprising collection vessel including a cavity defining a collection chamber, a first end including a porous member, and a second, threaded, end; and a connector portion including a first threaded coupling selectively threaded to the second, threaded, end and having a second coupling including a check valve connector including an integral check valve, the check valve connector having a quick-disconnect connector portion for use with a quick-disconnect connector coupled to a pump.  
         [0028]    Another aspect of the invention provides a lysimeter system, comprising a portable lysimeter and a selectably attachable pressure measurement device, the portable lysimeter including a collection vessel including a tubular portion having an inner surface and an outer surface having a diameter, the tubular portion having first and second ends, the collection vessel further including a porous member at the first end of the tubular portion, a chamber being defined by the inner surface and the porous member, the collection vessel including a fitting portion extending from the second end of the tubular portion, having an outer threaded cylindrical surface having a diameter less than the diameter of the tubular portion, and having an aperture therethrough in fluid communication with the chamber; a connector portion including a first coupling including a first cylindrical portion having a first end having an inner threaded surface selectively threadable onto outer threaded surface of the fitting portion of the collection vessel and having a second end, the first coupling having an aperture extending from the first end to the second end, the connector portion further including a plate secured to the second end of the first coupling, the plate having a threaded aperture therethrough in fluid communication with the first end of the first coupling, the connector portion further including a second coupling secured to the side of the plate opposite of the first coupling and including a second cylindrical portion and having an inner cylindrical surface, the inner cylindrical surface having an inner diameter and defining a receptacle, the second coupling further including a check valve connector including an integral check valve, the check valve connector having an outer cylindrical surface having a diameter less than the diameter of the inner cylindrical surface, the check valve connector having a threaded portion threadably mounted in the threaded aperture of the plate and having a quick-disconnect connector portion extending from the plate into the receptacle. The pressure measurement device includes a quick-disconnect connector portion being in fluid communication with the pressure measurement device and further being selectably matable with the quick-disconnect connector portion in the receptacle of the connector portion, and including a vacuum gauge in fluid communication with the pressure measurement device, the pressure measurement device further including a barbed fitting in fluid communication with the pressure measurement device, for selective coupling with a pump, wherein fluid communication between the pump and the chamber may be selectably established via the connector portion and pressure measurement device.  
         [0029]    Another aspect of the invention provides a lysimeter, comprising a hollow vessel having first and second closed ends and defining a chamber, the first and second ends having respective apertures therethrough; a fill conduit having first and second ends and extending into the chamber from the aperture through the second end of the hollow vessel such that the second end of the fill conduit is between the first and second ends of the vessel; and a semi-permeable member mounted to the second end of the vessel and in fluid communication with the first end of the fill conduit.  
         [0030]    Another aspect of the invention provides a deep lysimeter, comprising a body including an inner surface having a diameter, a first end, and a second end, and defining a chamber; a plate having a first surface, and a second surface secured to the second end of the body and having an aperture therethrough; a fill tube including an outer surface having a diameter, a first end, and a second end, the diameter of the outer surface being less than the diameter of the inner surface of the body, the first end of the fill tube being in fluid communication with the chamber via the plate aperture, the fill tube extending into the chamber such that the second end of the fill tube is between the plate and the first end of the body; a spacer having a first surface, and a second surface secured to the first surface of the plate, the spacer having an aperture therethrough; a semi-permeable member mounted to the first surface of the spacer, wherein a cavity is formed bounded by the semi-permeable member, spacer, and plate; a screen supported within the cavity to filter fluid entering the chamber; a cap sealing the first end of the body, the cap having an aperture or apertures in fluid communication with the chamber; and a line connection structure secured to the cap whereby the lysimeter may be retrieved from the sampling location. Valves or plugs are received in the apertures.  
         [0031]    Lysimeters of various embodiments of the invention can be installed on a semi-permanent basis in boreholes that either need to be withdrawn for each sampling event or that can be left in place and the sample retrieved without disturbing the sampler. For lysimeters used at shallow depths, e.g., much less than 20 feet, the interior may be designed to allow a vacuum to be provided at land surface to pull samples to the surface, for a nearly permanent installation. For use at greater depths, a lysimeter can be retracted to land surface and the sample withdrawn, or the lysimeter with dual tubes extending to land surface is left at sampling depth and a second tube is pressurized to push the sample to land surface using a first tube. For very deep installations the water reservoir may be separated to two chambers with a one way check valve to prevent the pressure from pushing fluid back through the semipermeable membrane.  
         [0032]    For a deep version lysimeter, a vacuum is applied before installation or once installed using a tube that leads to land surface and can attach to an optional vacuum tank. Over time, as a sample moves into the device, the vacuum decreases so there is less driving force to collect additional sample material. The volume of the sample collected can be increased by, for example, enlarging the volume of the vacuum chamber connected to the deep version so that as sample material enters the deep version, it has less of an effect on the change in pressure in the vacuum tank. Alternatively, a vacuum can be reapplied (manually or using an automatic vacuum pump) to keep the pressure relatively constant over time.  
         [0033]    Another aspect of the invention provides a portable lysimeter, comprising a body structure; an inflatable bladder supported by the body; a gas conduit in fluid communication with the bladder; a semi-permeable member assembly at least partially movable in response to inflation of the bladder; a sample conduit in fluid communication with the semi-permeable member assembly; and a reservoir supported by the body, and being in fluid communication with the sample conduit.  
         [0034]    Another aspect of the invention provides a portable lysimeter, comprising a tube having an outer surface and an inner surface, a first end, and a second end and defining a body, with an aperture therethrough; an inflatable bladder having first and second ends, and an inner tubular surface slidingly telescopically received over the outside surface of the body, the aperture being between the first and second ends of the bladder, such that the bladder covers the aperture, and the bladder being inflatable via the aperture; a first band fitted over the first end of the bladder to secure the first end of the bladder to the body and form a gas-tight seal between the first end of the bladder and the body; a second band fitted over the second end of the bladder to secure the second end of the bladder to the body and form a gas-tight seal between the second end of the bladder and the body; a gas line in fluid communication with the aperture, through which gas may by selectably introduced to inflate the bladder; a plurality of semi-permeable member assemblies, each having a front side, and a back side, located about the outside of the body and having the front side facing away from the body; a belt to secure the semi-permeable member assemblies to the body; a reservoir to collect the sample fluid; a line suspending the reservoir from the body; a sample line fluidly coupling each of the semi-permeable member assemblies and the reservoir, whereby fluid communication is established between each semi-permeable member assembly and the reservoir; and a retrieval line selectably secured to the body using which the lysimeter may be retrieved from the sampling location. If there is a tube leading to the land surface, it can be used to place and remove the lysimeter as desired.  
         [0035]    Another aspect of the invention provides a liquid sampling process for collecting a sample of a desired liquid found in an earth cavity, in which the earth cavity has known cross-sectional wall dimensions, comprising the steps of: providing a portable lysimeter having a probe with cross-sectional dimensions sufficiently less than the known cross-sectional dimensions of the earth cavity to enable the portable lysimeter to be lowered and raised in the earth cavity without hindrance; providing the probe with a bottom opening; providing the portable lysimeter with a semi-pervious membrane enclosing the bottom opening of the probe having a solid filter in which the solid filter is air impervious when wetted with a selected liquid, but is pervious to the desired liquid when the desired liquid engages the solid filter; attaching the portable lysimeter to a lowering/lifting line; lowering the portable lysimeter to a desired elevation within the earth cavity while supporting the lysimeter in the earth cavity by the lowering/lifting line for enabling the desired liquid to engage the solid filter; applying a vacuum pressure of a sufficient magnitude for causing the a sample of the desired liquid to pass through the wetted solid filter and into the probe when the desired liquid engages the solid filter; and after the sample of the desired liquid passes into the probe, raising the portable lysimeter with the lowering/raising line from the earth cavity.  
         [0036]    Still another aspect of the invention provides a liquid sampling apparatus for collecting a sample of a liquid found in an earth cavity, in which the earth cavity has known cross-sectional dimensions, comprising: providing a portable lysimeter probe having cross-sectional dimensions less than the known cross-sectional dimensions of the earth cavity; said lysimeter probe having an open substantially planar bottom wall; a substantially planar semi-permeable member affixed to the probe enclosing the bottom wall to provide an air impervious enclosure when the member is wetted with a selected liquid and provide a liquid pervious enclosure to enable the desired liquid to pass through the member into the interior probe when the desired liquid engages the solid filter; a lowering/raising line attached to the probe for lowering the probe into the earth cavity and supporting the probe at a desired level to enable the desired liquid to engage the member and for raising the probe from the earth cavity after a sample of the desired liquid has been collected; and a vacuum generator attachable to the probe for creating a vacuum of sufficient magnitude within the probe to draw a sample of the desired liquid through the filter and into the probe when the desired liquid engages the solid filter.  
         [0037]    Another aspect of the invention provides a suction bailer or lysimeter which can collect liquid samples of variable volumes and containerizes a sample in a relatively clean environment until the liquid is removed. This idea of a portable lysimeter was not considered feasible because it was previously thought that there had to be firm contact with the material being sampled and the sampling device; the inventors have determined that this is not the case.  
       DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS  
       [0038]    [0038]FIG. 1 shows a portable fluid sampling device or lysimeter  20  for collection of fluid samples in either the saturated or unsaturated zone. It can be used, for example, for collecting water samples from the vadose zone, ground water, geologic media, or buried waste.  
         [0039]    The suction bailer or lysimeter  20 , in accordance with one embodiment of the invention, can collect water in very thin layers of standing water (e.g., &lt;1 mm deep) or unsaturated porous material (need to make a partial hydraulic connection to material if unsaturated). It can also collect fluid from discrete depths. The device  20  can be used to selectively collect water or other fluids from a mixture of a fluid mixed with a solid. In one embodiment, the device can remove fluids where the fluid is held by capillary forces at pressures from above saturation to a theoretical limit of about −1.0 atmosphere, though a practical limit has been observed at about −0.5 atmosphere (−7.3 psi) relative to atmospheric pressure.  
         [0040]    The device  20  can be used, for example, to collect fluid samples from intermittent sources of water (i.e. waiting for a fluid to come in contact with the device and then collect and hold a fluid sample until an operator removes the sample). In one embodiment, the samples that are removed from the device  20  are filtered to remove particulate matter (various filter sizes can be used). The combination of portability along with other sampling characteristics makes the device  20  useful for environmental/industrial applications.  
         [0041]    [0041]FIG. 1 shows the lysimeter  20  in its simplest form. It is a portable sampling device used to collect fluid (water or other fluid) located in the saturated or unsaturated zone within a hole  22  excavated through existing materials  26  (having a well casing  23  shown in FIG. 1) at the location of interest and extending to the desired depth below the surface  24 . In a typical sampling situation, the saturated zone is that depth or strata of the hole in which the surrounding media (earth or other material) is completely imbued with liquid, to the exclusion of additional liquid entering the same region. The unsaturated zone has liquid present within the surrounding media, but not in sufficient quantity as to prevent additional liquid from entering the same region. The lysimeter  20  includes a chamber  34  and semi-permeable or porous member  30  in fluid communication with the chamber  34 . The lysimeter  20  is lowered into the hole  22  via a line  28  until contact is made between the semi-permeable member  30  of the lysimeter  20  and fluid bearing strata  32 . In operation, a vacuum pressure applied to the chamber  34  to draw the fluid sample into the chamber  34  through the semi-permeable member  30  and maintain the sample until the lysimeter  20  is retrieved via the line  28 . In operation, the semi-permeable member  30  is typically wet up with fluid (known as wetting fluid) so that a vacuum-pressurized condition of the chamber  34  is maintained until contact is established between the semi-permeable member and the target fluid. The lysimeter  20  includes valves  36  in fluid communication with the chamber  34  for connection to a pump and/or for draining of the fluid sample at retrieval time. The lysimeter may also have a conduit to the surface  24  so that continuous vacuum pressure may be applied without requiring that the vacuum pump be lowered into the hole. This yields an extremely simple technique for securing and retrieving the fluid sample.  
         [0042]    [0042]FIG. 2 shows a portable lysimeter  120  in accordance with an alternative embodiment of the invention. The lysimeter  120  includes a tube  122  having an inner surface  138  and an outer surface  140 . The tube  122  is formed of plastic, such as clear or translucent plastic, in one embodiment, or metal or other suitable rigid material. The tube  122  further has a top  124 , and a bottom  126 . The lysimeter further includes a resilient stopper  142  or other suitable seal selectively closing the top  124  of the tube  122 , and a semi-permeable member  130 . Semi-permeable member  130  is supported by or secured to the bottom  126  of the tube  122 . In an alternative embodiment, the top  124  is closed or integral with the inner surface  138  and the stopper  142  is omitted. Other suitable methods of sealing top  124  may be employed. The inner surface  138 , top  124 , bottom  126 , stopper  142  and semi-permeable member  130  collectively define a chamber  128 . The lysimeter  120  further includes a valve  132  in fluid communication with the chamber  128  via an aperture  144  through the stopper  142 . The valve  132  may be used to connect a pump to pre-evacuate the chamber  128 , to connect a continuously applied vacuum pressure, or to drain the collected sample. The lysimeter  120  further includes a vacuum gauge  134  in fluid communication with the chamber  128  via an aperture  146  through the stopper  142 , and may be used to monitor the degree of chamber  128  pressurization.  
         [0043]    [0043]FIG. 3 shows that the semi-permeable member  130  is secured to the tube bottom  126  via glue  136 , in one embodiment. Other methods could, of course, be employed.  
         [0044]    [0044]FIG. 4 shows a portable lysimeter  220  in accordance with an alternative embodiment of the invention. The lysimeter  220  comprises a tube  221 , having an inner surface  232 , and further having a top  222  that is selectably detachable from the tube  221  for removal of the sample. The top  222  has a through aperture  230 , and the lysimeter  220  further includes a vacuum tube  228  in fluid communication with the aperture  230  or extending from partially or completely through the aperture. The lysimeter  220  further includes a vacuum line  238  and a clamp  240 . The vacuum line  238  is in fluid communication with vacuum tube  228  and secured to the vacuum tube  228  with the clamp  240 , such that a vacuum pressure may be applied to the chamber  234  via the vacuum line  238  leading to the land surface. The lysimeter  220  further includes an O-ring  224  that enhances the seal between the top  222  and the tube  221  during the mating of these components. The lysimeter  220  further includes semi-permeable member  226  that is supported by or secured to the bottom end of the tube  221 . The top  222 , inner surface  232 , semi-permeable member  226  collectively define a chamber  234 . The lysimeter  220  further includes retrieval loops or apertures  236  which selectively receive a line for raising, lowering, or supporting the lysimeter  220  and line  238 .  
         [0045]    [0045]FIG. 5 shows a lysimeter system  320  in accordance with another embodiment of the invention. The lysimeter system  320  comprises aportable lysimeter  322 . The portable lysimeter  322  includes a collection vessel  324 . The collection vessel  324  includes a tubular portion  328 , having an inner surface  333 , an end  330 , and an end  332 . The collection vessel  324  further includes a semi-permeable member  334  supported by or secured to end  330  of the tubular portion  328 . The collection vessel  324  further includes a chamber  326  defined by the inner surface  333  of the tubular portion  328  and semi-permeable member  334 . In the illustrated embodiment, the semi-permeable member  334  is in the form of a plate. In alternative embodiments, the semi-permeable member  334  (or  226 , or  130 , etc.) can be a porous cup, and can be made of ceramic, plastic, glass, or metal, and may be rigid or may be partially or wholly flexible. Other forms such as a cluster of fibers (not shown), capable of wicking a sample liquid into the chamber, may also be used. The semi-permeable member  334  can be formed integrally with the end  330  of the tubular portion  328  or secured to the end  330  in any appropriate manner, such as by bonding with glue, securing with screws, securing the screen embodiment with a hose clamp or similar sealing mechanism to the outer wall of the tubular portion  328 , etc.  
         [0046]    The collection vessel  324  includes a fitting portion  336  extending from the end  332  of the tubular portion  328 . In the illustrated embodiment, the fitting portion  336  has an outer threaded cylindrical surface  338  having a diameter less than the diameter of the tubular portion  328 , and has a through aperture  337  in fluid communication with the chamber  326 .  
         [0047]    The portable lysimeter  322  further includes a connector portion  340  including a coupling  342 . The coupling  342  includes a cylindrical portion  344  having an end  346 . In alternative embodiments, other shapes are employed. The end  346  has an inner threaded surface  348  selectively threadable onto the outer threaded surface  338  of the fitting portion  336  of the collection vessel  324 . The first coupling  342  further has a second end  350 . In alternative embodiments (not shown), the fitting portion of the collection vessel can have an inner threaded surface and the first end of the first cylindrical portion can have an outer threaded surface. The first coupling  342  further has an aperture extending from the end  346  to the end  350 .  
         [0048]    The connector portion  340  further includes a barrier or plate  352  secured to the end  350  of the coupling  342 . The barrier or plate  352  has a threaded aperture  353  in fluid communication with the end  346  of the coupling  342 . The connector portion  340  further includes a coupling  354  extending from, supported by, or secured to the side of the plate  352  opposite of the coupling  342  or integral with the cylindrical portion  344 . The coupling  354  includes a cylindrical portion  356  and having an inner cylindrical surface  358 . In alternative embodiments, other shapes are employed. The inner cylindrical surface  358  has an inner diameter and defines a receptacle  360 .  
         [0049]    The coupling  354  further includes a check valve connector  362  having an integral check valve. Suitable connectors are available from Swageloc of Solon, Ohio. The check valve connector  362  includes an outer cylindrical surface  363  having a diameter less than the diameter of the inner cylindrical surface  358 . The check valve connector  362  has a threaded portion  364  threadably mounted into the threaded aperture  353  of the plate  352 . In alternative embodiments, the check valve connector is non-threadably supported by the plate  352 . The check valve connector  362  further has a quick-disconnect connector portion  366  extending from the plate  352  into the receptacle  360 . The coupling  354  further includes one or more through apertures  369  such that selectable connection of a line (not shown) may be used to retrieved the lysimeter  322  from a sampling location. Alternatively, a loop or eyebolt is provided anywhere appropriate on the lysimeter  322  for receipt of a removal line.  
         [0050]    The overall arrangement of the connector portion  340  is readily constructed from available components and facilitates easy interface of the collection vessel  324  to an evacuation arrangement to be described hereafter. Additionally, the connector portion  340  may be easily removed from the collection vessel  324  to allow draining of the collected fluid sample.  
         [0051]    The lysismeter system  320  further includes a pressure measurement device  368 . The pressure measurement device includes a quick-disconnect connector portion  370  selectably matable with the quick-disconnect connector portion  366  in the receptacle  360 . The pressure measurement device  368  further includes a vacuum gauge  372 , a valve  376 , and a barbed fitting  374 , such that the three are in common fluid communication with the quick-disconnect connector portion  370 . The barbed fitting  374  permits selective coupling of a pump (not shown) to the collection vessel  324  via the pressure measurement device  368  and connector portion  340 . Due to the compact size and portable nature of the lysimeter system  320 , a hand actuated pump may be utilized, realizing a portable lysimeter  322  that can be vacuum pressurized and placed into service in remote areas without need for power.  
         [0052]    [0052]FIG. 6 shows a lysimeter  420  in accordance with another embodiment of the invention. This embodiment may be retrieved from the sampling location to gather the liquid sample, or left in place while the sample is extracted by pressure or vacuum means and transported to the land surface. The lysimeter  420  includes a tube  422  having closed ends  440  and  442 . The tube  422  defines a chamber  424 . The lysimeter  420  further includes an aperture  425  through the end  442 , and further includes apertures  432  and  434  through the end  440 . The lysimeter  420  further includes a fill tube  426  in fluid communication with the aperture  425  and extending into the chamber  424 . The lysimeter further includes a spacer  444 , a screen  430  as required, and a semi-permeable member  428 . The screen  430  is optional if the semi-permeable member is rigid. The spacer  444  is secured to the end  442  of the tube  422 . The semi-permeable member  428  is secured to the spacer  444  opposite of the end  442 . The configuration of closed end  442 , spacer  444 , and semi-permeable member  428  form a cavity, and further support screen  430  (if a flexible membrane) within the cavity. Semi-permeable member  428  and screen  430  are in fluid communication with the chamber  424  via the aperture  425  and fill tube  426 . The lysimeter optionally further includes valves, plugs, or fittings  436  respectively received in each of the apertures  432  and  434  in fluid communication with the chamber  424 . In one alternative embodiment, one plug is provided in one of the apertures  432  and  434  and one valve is provided in one of the apertures  432  and  434 .  
         [0053]    The lysimeter  420  further includes a sample extraction tube  438  in fluid communication with the aperture  434  and respective fitting  436 , and extending into the chamber  424  toward the end  442  of the tube  422 . The lysimeter  420  may be selectably connected to a pump for vacuum pressurization of the chamber  424  via the fitting  436  in the aperture  432 . The fitting  436  in the aperture  434  may be utilized to drain the collected sample fluid from the chamber  424 . Selectably stopping the first aperture  432  and the second aperture  434  by blocking the respective fittings  436  maintains the vacuum pressure while the lysimeter is being placed into service. Other uses for the fittings  436  may also be realized. For example, optional tubes  446  and  448  in fluid communication with respective fittings  436  may be used to deliver the fluid sample to the land surface, by pressurizing the chamber  424  through optional tube  446  such that the fluid sample is transported to the land surface through optional tube  448 .  
         [0054]    The fill tube  426  and chamber  424  arrangement retains the sample fluid until the lysimeter is retrieved by an operator, and further serves to reduce the loss of fluid from backflow of fluid contained in chamber  424 . Further, a one way flow valve or check valve (not shown), may be used instead of the fill tube  426  to protect the semi-permeable member  428  and/or screen  430  from excessive pressure when the sample is being retracted from the hole by applying pressure into chamber  424  by way of tube  446 . Lysimeter  420  further includes a line connection structure  450  secured to the closed end  440 . Selective attachment of a line to structure  450  facilitates raising, lowering, or supporting the lysimeter  420 .  
         [0055]    [0055]FIG. 7 shows an end view of the portable lysimeter  420  of FIG. 6, including a typical arrangement of the semi-permeable member  428 , the screen  430 , the aperture  425  and the end  442  of the tube  422 .  
         [0056]    [0056]FIG. 8 shows a portable lysimeter  520 , in accordance with an alternative embodiment of the invention. The lysimeter  520  includes a tube  522  having an inner surface  560  and an outer surface  562 , an end  564 , and an end  566 . The tube  522  defines a body  524 , having an aperture  526 . The lysimeter  520  further includes an inflatable bladder  528 , having ends  568  and  570  and an inner tubular surface slidingly telescopically received over the outside surface of the body  524 . The aperture  526  is located between the ends  568  and  570  of the bladder  528 , such that the bladder  528  covers the aperture  526 . The bladder  528  is inflatable via the aperture  526 . The lysimeter  520  further includes a band  530  fitted over the end  568  of the bladder  528  to secure the end  568  of the bladder  528  to the body  524  and form a gas-tight seal between the end  568  of the bladder  528  and the body  524 . The lysimeter further includes a band  532  fitted over the end  570  of the bladder  528  to secure the end  570  of the bladder  528  to the body  524  and form a gas-tight seal between the end  570  of the bladder  528  and the body  524 .  
         [0057]    The lysimeter  520  further includes a gas line  534  in fluid communication with the aperture  526 , through which gas may by selectably introduced to inflate the bladder  528 . The lysimeter  520  further includes a plurality of semi-permeable member assemblies  536 . Each assembly  536  has a front side  538 , and a back side  540 , located about the outside of the bladder  528 . The front side  538  of each assembly  536  faces away from the body  524 . The lysimeter  520  further includes a belt  542  securing the semi-permeable member assemblies  536  to the body  524  at respective locations beyond the end of the bladder  528  such that the belt  542  does not hinder the inflation of the bladder  528 . The lysimeter further includes a reservoir  544  to collect the sample fluid. While reservoir  544  is shown as being separate from tube  522 , in one embodiment a single part defines both reservoir  544  and tube  522 . The lysimeter further includes a line  546  and associated structure such that the body  524  supports the reservoir  544  via the line  546 .  
         [0058]    The lysimeter  520  further includes a sample line  548  fluidly coupling each of the semi-permeable member assemblies  536  and the reservoir  544 . The sampler line  548  provides a conduit through which sample fluid collected by the respective semi-permeable member assemblies  536  is transported to the reservoir  544 . The lysimeter  520  further includes a plurality of valves  552  each respectively in fluid communication with the reservoir  544 . The reservoir  544  has an interior that defines a chamber. The lysimeter  520  further includes a retrieval line  550  that is selectably secured to the body  524  permitting retrieval of the lysimeter  520  from the sampling location. More particularly, the lysimeter  520  includes a diametrically extending wire or line attached to the end  564  of the tube  522  to which the line  550  can be tied.  
         [0059]    In operation, the semi-permeable member assemblies  536  are wet up with wetting fluid, and the chamber is vacuum pressurized prior to placement into service. The lysimeter  520  is lowered into a sample hole, with support provided by the retrieval line  550 . The bladder  528  is then inflated via the gas line  534  until the bladder  528  has expanded sufficiently to urge at least a portion of the front side  538  of each semi-permeable member assembly  536  into contact with the interior of the hole. Fluid traveling along the walls of the hole and coming into contact with the front side  538  of any semi-permeable member assembly  536  is captured and routed to the reservoir  544  for collection. To gather the fluid sample, the bladder  528  is deflated via the gas line  534  prior to retrieval and the lysimeter  520  is then brought to the surface via the retrieval line  550 . The collected fluid sample may then be selectably drained from the chamber. In one embodiment, retrieval of the sample fluid is facilitated by a collection line extending from one of the valves  552  (e.g., the top valve) to the land surface to allow a vacuum to be applied once the lysimeter  520  placed in the hole and the bladder expanded.  
         [0060]    [0060]FIGS. 9 and 10 show front and side views, respectively, of a typical embodiment of the semi-permeable member assembly  536 . The front side  538  comprises flexible semi-permeable material  554 . The back side  540  is secured to the front side  538  via cement about the periphery. The semi-permeable member assembly  536  includes scrim material  556  that maintains a cavity  557  between the front side  538  and the back side  540 , with the cavity in fluid communication with the flexible semi-permeable material  554 . The back side  540  of the semi-permeable member assembly  536  further includes an aperture  572 . The semi-permeable member assembly  536  further includes with a plate fitting  558  in fluid communication with the cavity  557  via the aperture  572 . The plate fitting  558  provides fluid communication to the reservoir  544  via the sample line  548 .  
         [0061]    [0061]FIG. 11 provides an illustration of the portable lysimeter  520  with the semi-permeable member assemblies  536  not shown, for clarity. The bladder  528  typically underlying the semi-permeable member assemblies  536  (not shown in FIG. 11) is fully exposed.  
         [0062]    [0062]FIG. 12 provides a cutaway view of the lysimeter  520  such that further details of a typical bladder  528  and gas line  534  arrangement are revealed. Further shown are typical designations for vacuum V and drain D connections to the valves  552  included at the reservoir  544 .  
         [0063]    Under typical operation the portable lysimeter is left in place in a hole to collect the sample for a time period and then retrieved to the surface to remove the sample for analysis. The semi-permeable member(s) utilized on any given embodiment are commercially available from a variety of suppliers. They may be made of porous metals, ceramics, glass or plastics. The semi-permeable member is generally wetted with deionized water or with water of known quality prior to sampling to fill the pores and prevent air entry into the device. More particularly, in the various embodiments, the semi-permeable member is generally wet up with fluid (known quality of wetting fluid) and a vacuum is applied prior to lowering into the hole. The semi-permeable member generally will not hold a vacuum (air enters the device) unless the semi-permeable member has been prewetted. An exception is if there is standing water in the hole, in which case the lysimeter could be lowered so that the semi-permeable member is in contact with the water, and then a vacuum is applied following the lowering. This requires a tube to the lysimeter from the land surface. Also, the semi-permeable member has pores sized to transmit water but exclude air transport across the member.  
         [0064]    The lysimeter may include a removable top to allow the chamber to be cleaned and emptied. A disposable version (not shown) just has a way to seal the chamber, apply a vacuum pressure and then remove the sample.  
         [0065]    If the semi-permeable member of the lysimeter is supported an appropriate distance above the material or fluid to be sampled, then it will only collect the fluid if the fluid level rises to the level of the semi-permeable member. It may, for example, be used to collect intermittent sources of water such as perched water or when the fluid level reaches a given depth. The lysimeter can also be used to collect water from discrete depths by pressurizing the chamber, lowering it to a specified depth, then applying a vacuum pressure to the chamber to collect a sample. This configuration also allows samples to be collected from very thin layers of fluids and to accumulate large samples. This fluid is also filtered while collecting the sample. Several different pore-sized materials are commonly available that would be acceptable.  
         [0066]    The various semi-permeable members  30 ,  130 ,  226 ,  334 , and  428  can be flat, slightly rounded, or in cup shape or highly rounded shape. One type of semi-permeable member is called a hollow fiber, is used for dialysis, and looks like a hollow thread. These fibers come in different pore sizes and is used, in one embodiment, in place of the semi-permeable member of the various embodiments. For example, the hollow fibers are cut to three to six inch lengths, both cut ends are placed in the end of a long tube with the loop extending out below and the cut fiber ends in the tube. A sealant is used to pot the fibers in place (with the loops extending out below the tube and the cut ends open to the inside of the tube). The tube is sealed on the top, a partial vacuum is applied to the tube, and the fibers are placed in contact with the material to be sampled. Sample fluid is pulled through the fibers in the tube. The tube is then pulled to the land surface for sample collection.  
         [0067]    Thus, a sampling mechanism or lysimeter has been provided that is easily transportable, being of size that is easily handled in the field. This aspect permits servicing of several installed locations within a typical work period.  
         [0068]    Further, a portable lysimeter has been provided capable of using a vacuum pressure technique to urge the sample fluid into a collection chamber, with the vacuum pressure existing as either a pre-pressurized state within the collection chamber or via communication between the chamber and a remotely located pump, typically at the surface of the ground. In the pre-pressurized mode, no connection between the in-service lysimeter and any vacuum system is required. This mode permits operation with a reduced equipment count and eliminates the need to install, maintain or energize vacuum pump devices in remote areas.  
         [0069]    A method has been provided to extract fluid samples from a well or borehole in such a manner that backfill or direct burial is not required. This allows for repeated use of the same sample location, typically part of a matrix of strategically located sampling boreholes, without the need to excavate the installed location at sample gathering time or backfill the borehole when a fresh lysimeter is placed into service. This eliminates considerable labor and heavy machine operating time. Further, a lysimeter suspect of malfunction may be easily retrieved and replaced.  
         [0070]    In compliance with the statute, the invention has been described in language more or less specific as to structural and methodical features. It is to be understood, however, that the invention is not limited to the specific features shown and described, since the means herein disclosed comprise preferred forms of putting the invention into effect. The invention is, therefore, claimed in any of its forms or modifications within the proper scope of the appended claims appropriately interpreted in accordance with the doctrine of equivalents.