JP6402656B2 - Underground purification wall - Google Patents

Description

  The present invention relates to an underground purification wall for purifying groundwater contaminated with contaminated soil in situ.

  Conventionally, in a site with ground contaminated by pollutants such as heavy metals and organochlorine compounds, groundwater has been established by installing a pumping well in the site to prevent the pollutants from flowing out of the site via groundwater. Is known, and a method for purifying the pumped ground water with a water treatment facility is known. However, this method requires regular maintenance in order to maintain the pumping function in the pumping well. In addition, in a water treatment facility, it is necessary to secure an installation location, and not only to maintain and manage chemicals and equipment but also to manage the quality of treated water. Therefore, the labor required for maintenance is complicated and the running cost tends to be enormous.

  On the other hand, as a means of eliminating the need for pumping wells and water treatment facilities, a ground wall for purifying groundwater should be installed on the downstream side of groundwater within the site, and the groundwater should be allowed to permeate through the ground wall. A method for removing contaminants in groundwater is known.

  As a method for constructing such a purified underground wall, for example, in Patent Document 1, a trench is formed in the ground, or a plurality of columnar holes are excavated so as to partially overlap to form columnar row holes. A method is disclosed in which a wall-shaped excavation hole is formed in the ground and a pollutant removing component is filled therein.

  Patent Document 2 discloses a method in which a unit body in which permulite that adsorbs pollutants in contaminated groundwater is enclosed in a bag is stacked on a wall-shaped excavation hole formed in the ground.

Japanese Patent Laid-Open No. 2004-283760 Japanese Patent Laid-Open No. 2003-300064

  However, in the method described in Patent Document 1, since the pollutant removing component is directly filled in the wall excavation hole, the pollutant removing component having a small particle diameter is removed from the wall excavation hole by aging in an area where the flow rate of groundwater is high. There is a case where it is easy to be washed away in the surrounding soil and the predetermined wall thickness cannot be maintained. In addition, when the purification function of groundwater is deteriorated due to the use of the pollutant removal component over time, it is complicated to replace the pollutant removal component while protecting the wall of the wall-shaped excavation hole. For this reason, it is often not necessary to replace the wall without replacing it, and a new purification ground wall is added, which is not economical and secures a site for constructing a new purification wall. Need to do.

  Furthermore, when the underground wall-shaped excavation holes are formed by columnar row holes, the chord length formed in the overlapping portion of adjacent columnar holes satisfies the wall thickness required for the purified underground wall. Form row holes. In this case, the wall thickness of the columnar hole itself becomes larger than the wall thickness required for the purification ground wall, so if the entire interior of the columnar hole is filled with the pollutant removing component, the pollutant removing component is wasted. .

  Further, in the method described in Patent Document 2, since the unit body is formed by enclosing permulite in a bag, the replacement work when the purification function of groundwater is reduced is easy, and the soil around the wall-shaped excavation hole is It is also difficult to run away. However, in the method of stacking unit bodies in the underground wall-shaped excavation hole, there is no permulite in the wall-shaped excavation hole because gaps are likely to occur between the hole wall and the unit bodies and between the unit bodies. A hollow part will be formed, and the case where the groundwater which passes an underground wall cannot fully be purified arises.

  The present invention has been made in view of such problems, and its main object is to provide an underground purification wall that is inexpensive, has good purification efficiency of groundwater, and can be rehabilitated easily when the purification function is reduced. It is to be.

  In order to achieve this object, the underground purification wall of the present invention is an underground purification wall for purifying contaminated groundwater, and the underground purification wall comprises a contaminant adsorbing material and a water-permeable shape retaining frame. It consists of an underground purification wall main body and a drain material covering the underground purification wall main body, and penetrates the casing into the ground and evacuates the interior, and the cross section in plan view has a size inscribed in the casing. The shape holding frame formed in a rectangular shape having at least one side as an opening is inserted into the casing, and then the contaminant adsorbing material is filled inside the shape holding frame and the drain material is filled outside. The casing is removed, and the casing is positioned so that the outer peripheral surface is close to the opening of the shape-retaining frame, penetrates into the ground, and the interior is evacuated. A new step of inserting the new shape-retaining frame, filling the inside of the shape-retaining frame with the contaminant adsorbing material, filling the drain material with the outer side, and removing the casing. It is characterized by that.

  Moreover, the underground purification | cleaning wall of this invention repeats a 2nd process in multiple times, It is characterized by the above-mentioned.

  According to the above underground purification wall, it consists of a simple structure consisting only of the underground purification wall main body made of the shape retaining frame and the contaminant adsorbing material and the drain material covering it, so that the contaminated groundwater is pumped by the pumping equipment. Compared to the purification method using water treatment facilities, there is no need to secure a site for installing water treatment facilities, and no maintenance is required, greatly reducing costs and management burden. It becomes.

  In addition, since the pollutant adsorbent is filled into the shape retaining frame, not only does the pollutant adsorbent run away into the surrounding soil due to the use of the underground purifying wall, but also the underground purifying wall body Since the drainage material is covered with the drainage material, the groundwater collection efficiency is improved, so that the groundwater can be efficiently purified over a long period of time.

  Further, the cross section in plan view of the shape holding frame is formed in a rectangular shape having a size inscribed in the casing and having at least one side as an opening, and when installing the shape holding frame in the ground, A casing is penetrated in the vicinity of the opening of the shape holding frame installed in advance, and a new shape holding frame is inserted into the casing.

  As a result, when the casing is pulled out, the new shape holding frame installed downstream is connected at the opening position of the shape holding frame installed in advance, and the columnar hole formed in the first step is connected to the first shape holding frame. A linear wall body having a wall thickness having a length equal to the chord length formed in the overlapping portion with the columnar hole formed in the step 2 is formed.

  Therefore, the underground purification wall main body is a linear wall body that occupies only the central part of the columnar row hole constructed by continuously connecting a plurality of columnar holes. Compared with the case where the pollutant adsorbent is filled in, the pollutant adsorbent is not wasted.

  In the underground purification wall of the present invention, the shape holding frame is made of a water-permeable belt-like material, and holds a pair of water-permeable surface members facing each other in parallel with an interval, and an arrangement interval of the water-permeable surface members. The pair of water-permeable surface members are inserted into the casing so that the short sides thereof are in the horizontal direction and the long sides are in the vertical direction.

  According to the above underground purification wall, since the shape holding frame is held by the connecting member, when the purification function of the groundwater in the contaminant adsorbing material is lowered, the shape holding frame causes the hole wall It is possible to easily remove and replace the contaminant adsorbing material without enclosing the surrounding earth and sand. Thereby, since the underground purification | cleaning wall main body used as the purification | cleaning area | region of groundwater can be renovated easily, it becomes possible to use the underground purification | cleaning wall provided with this underground purification | cleaning wall main body continuously over a long period of time.

  In the underground purification wall according to the present invention, the connecting member is a rod-shaped member, and a plurality of intervals are provided so as to be substantially central portions of the short sides of the water-permeable surface member and to be parallel to the long sides. It is characterized by being arranged.

  According to the above underground purification wall, since the internal spaces of the adjacent shape holding frames communicate with each other, when removing the pollutant adsorbent whose purification function of groundwater is reduced, for example, any of the adjacent shape holding frames By sucking the pollutant adsorbent in one place, all the pollutant adsorbent in the underground purification wall main body can be sucked and removed at a time. This makes it possible to perform the removal / replacement operation of the contaminant adsorbent more quickly.

  The underground purification wall of the present invention is characterized in that the connecting member is made of a water-permeable belt-like material, and is arranged so as to connect the long sides facing each other in the pair of water-permeable surface members.

  According to the above-described underground purification wall, the inside of the underground purification wall main body is divided by the shape holding frame adjacent to each other by the connecting member. When a decrease in the groundwater purification function in the contaminant adsorbent is observed, only the contaminant adsorbent in the compartment where the decrease in the groundwater purification function is observed can be removed and replaced. Thereby, since the healthy contaminant adsorbent located in the other section can be left, it becomes possible to perform removal and replacement work more economically.

  According to the present invention, the underground purification wall is constituted by the underground purification wall main body made of the contaminant adsorbing material and the shape holding frame, and the drain material covering the underground purification wall main body. Not only does it have the effect of collecting groundwater, but it can easily remove and replace contaminant adsorbents while protecting the hole walls with a shape-retaining frame. When lowered, the underground purification wall body provided with the contaminant adsorbing material can be easily rehabilitated.

It is a figure which shows the installation condition of an underground purification | cleaning wall. It is a figure which shows the plane of an underground purification | cleaning wall. It is a figure which shows the shape holding frame which comprises a underground purification | cleaning wall main body. It is a figure which shows the cross section of the extending direction in an underground purification | cleaning wall. It is a figure which shows the construction method of an underground purification wall. It is a figure which shows the relationship between a shape holding frame and a casing. It is a figure which shows the cross section of the wall thickness direction in an underground purification | cleaning wall.

  Below, the underground purification wall 1 which is one Embodiment of this invention is explained in full detail using FIGS. 1-7.

  The underground purification wall 1 of the present invention is a groundwater permeable underground wall containing a underground purification wall body 2 having a contaminant adsorbing material 4 and is contaminated with contaminants such as heavy metals and organochlorine compounds. It is installed near the contaminated ground 11 and downstream of the groundwater 12. Since the groundwater 12 contaminated by flowing down the contaminated ground 11 is purified by naturally passing through the underground purification wall 1, the pollutant 11 flows downstream from the underground purification wall 1 through the underground water 12. It is possible to prevent this.

  In the present embodiment, as shown in FIG. 1, it is located on the downstream side of the groundwater 12 in order to prevent contaminants from flowing out of the site such as a factory having the contaminated ground 11 through the groundwater 12. The case where the underground purification wall 1 of the present invention is constructed in the vicinity of the site boundary L will be described in detail.

  As shown in FIGS. 1 and 2, the underground purification wall 1 has a columnar hole 151 formed at a depth extending from the vicinity of the ground surface to a water-impermeable layer 13 located below the water-permeable layer having the contaminated ground 11. 12 is constructed in a columnar row hole 15 constructed in a continuous manner in a direction orthogonal to the flow-down direction, and includes a drain material 2 and an underground purification wall body 3.

  The drain material 2 is filled between the hole wall of the columnar row hole 15 and the underground purification wall main body 3, holds the hole wall of the columnar row hole 15, and supplies groundwater to the underground purification wall main body 3. Provided to lead to. In the present embodiment, crushed stone is adopted as the drain material 2, but it is not necessarily limited to crushed stone, and when the ground purification wall body 3 and the hole wall are filled, the contaminated ground 11 is removed. Any material such as sand and gravel may be used as long as the water permeability coefficient is larger than the water permeability layer.

  The underground purification wall main body 3 covered with the drain material 2 serves as a purification region for purifying the contaminated ground water 12, and as shown in FIG. And a shape holding frame 5 to be formed. In addition, although mentioned later, FIG. 2 (a) and FIG.2 (b) are the underground purification | cleaning walls 1 which employ | adopted the shape holding frame 5 from which a shape differs in the underground purification | cleaning wall main body 3, respectively.

  The pollutant adsorbent 4 is a material capable of removing pollutants that fall under the items listed in, for example, “Environmental Standards for Groundwater Water Pollution” (March 13, 1997, Notification of the Environment Agency No. 10). Among these, an optimum material is appropriately selected according to the contaminant to be removed, and this is processed into a granular or powdery body. The particle size is adjusted to a size having a specific surface area that does not impair the performance of removing contaminants contained in the groundwater 12 while ensuring the water permeability required for the underground purification wall body 3.

  As a specific material used for the pollutant adsorbing material 4, for example, when it is desired to remove fluorine or the like, activated alumina is employed for the pollutant adsorbing material 4. When hexavalent chromium or 1,4-dioxane is to be removed, an optimum material such as activated carbon is used as the contaminant adsorbent 4 according to the contamination concentration of the contaminated groundwater 12.

  The pollutant adsorbent 4 may be composed of a single material, or when it is desired to remove a plurality of types of pollutants from the contaminated ground water 12, it is a granular material made of a material corresponding to the pollutant to be removed. A plurality of bodies or powder bodies may be mixed.

  As shown in FIG. 3, the shape holding frame 5 filled with the contaminant adsorbing material 4 is configured as a long member including a pair of water-permeable surface members 51 and a connecting member 52 that holds the arrangement interval therebetween. Has been.

  As shown in FIGS. 3A and 3B, the water-permeable surface member 51 is formed of a water-permeable belt-like material, prevents passage of the contaminant adsorbing material 4, and passes through the drain material 2. Any material may be employed as long as it has a strength that does not cause damage even when a lateral pressure is applied to the hole walls of the columnar row holes 15. In the present embodiment, as shown in FIG. 3C, a pair of lath nets 512 is disposed on both surfaces of a nonwoven fabric 511 and a band-shaped material formed integrally with a rectangular frame 513 is used. As shown in FIGS. 3A and 3B, a pair of water-permeable surface members 51 made of these belt-shaped materials are arranged so as to face each other with a gap therebetween, and are connected by a connecting member 52.

  The connecting member 52 has any shape as long as the connecting member 52 has a strength capable of maintaining the arrangement interval of the water-permeable surface member 51 even when a lateral pressure is applied from the hole wall of the columnar row hole 15 via the drain material 2. A thing may be adopted. The arrangement position is also arranged at any position as long as at least one of the two openings formed between the long sides facing each other in the pair of water flow surface members 51 can be secured as the opening w of the shape holding frame 5. May be.

  For example, the connecting member 52 shown in FIG. 3A employs a belt-like material having water permeability similar to that of the water-permeable surface member 51 described above, and this is opposed to the pair of water-permeable surface members 51. It is arranged between the long sides. As a result, the shape retaining frame 5 becomes a long member formed in a U-shaped cross section, that is, a rectangular cross section having one side as the opening w.

  The shape retaining frame 5 formed in this way is installed in the columnar row hole 15 so that the short side of the water-permeable surface member 51 faces the horizontal direction and the long side faces the vertical direction. Then, as shown in the plan view of FIG. 2A, a plurality of water-permeable surface members 51 are connected to each other at the position of the opening w, with the columnar holes 15 adjacent to each other.

  Thereby, one of the water-permeable surface members 51 which make a pair forms the groundwater inflow surface 31 in the underground purification wall main body 3, and the other forms the groundwater outflow surface 32 parallel to the groundwater inflow surface 31. The length of the connecting member 52 is the wall thickness of the underground purification wall main body 3.

  Therefore, the length of the connecting member 52 is necessary for the underground purification wall main body 3 calculated according to the contaminant concentration of the groundwater 12, the flow velocity of the groundwater 12, the durable years required for the underground purification wall main body 3, and the like. Create it to the same length as the wall thickness.

  By the way, as shown in FIG. 2A, when the shape retaining frame 5 in which a water-permeable belt-like material as shown in FIG. The contaminant adsorbing material 4 filled in the underground purification wall main body 3 is apparently continuously filled in the extending direction of the underground purification wall main body 3, but in the extending direction of FIG. As shown in the sectional view, the connecting member 52 is divided into a plurality of sections.

  Therefore, when the purification function of the groundwater 12 in the pollutant adsorbent 4 is deteriorated due to aged use of the underground purification wall 1, the removal / replacement work of the pollutant adsorbent 4 is performed for each section according to the degree of the functional degradation. It can be carried out. As a result, when the degradation of the function of the pollutant adsorbent 4 is local, it is possible to leave the healthy pollutant adsorbent 4 located in other sections, so that the removal and replacement work can be performed more economically. Can be done.

  Further, as another example of the connecting member 52, the connecting member 52 shown in FIG. 3B employs a rod-shaped member, which is a central portion on the short side of the water-permeable surface member 51, and is long. A plurality are arranged at intervals so as to be parallel to the side. Thereby, the shape holding frame 5 becomes an elongate member formed in an H-shaped cross section, that is, a rectangular cross section having two sides as the opening w.

  Then, as shown in FIG. 2B, when the shape retaining frame 5 in which the rod-shaped member as shown in FIG. As shown in the sectional view in the extending direction of b), the contaminant adsorbing material 4 filled in the underground purification wall main body 3 is continuously and uniformly filled in the extending direction of the underground purification wall main body 3. Will be.

  Thereby, when the purification function of the pollutant adsorbent 4 is deteriorated due to the use of the underground purification wall 1 over time, it is filled by performing a suction operation at an arbitrary place in the underground purification wall main body 3. The pollutant adsorbing material 4 can be discharged at a time. Similarly, by performing the filling operation from any one place in the underground purification wall main body 3, the contaminant adsorbing material 4 can be replaced at a time, and the renewal operation of the underground purification wall main body 3 can be performed quickly and efficiently. It becomes possible to carry out.

  In any of the shape holding frames 5 employing any of the connecting members 52, the contaminant adsorbing material 4 is prevented from leaking into the shape holding frames 5 positioned at both ends of the underground purification wall main body 3. FIG. It is preferable to adopt a member using a water-permeable band for the connecting member 52 as shown in a).

  Thus, since the underground purification wall 1 fills the inside of the shape holding frame 5 with the pollutant adsorbing material 4, the pollutant adsorbing material 4 is washed away into the surrounding soil by the use of the underground purifying wall 1 over time. There is nothing. Moreover, since the underground purification | cleaning wall main body 3 is covered with the drain material 2, the water collection efficiency of the groundwater 12 improves.

  In addition, since the shape holding frame 5 is held by the connecting member 52, the pollutant adsorbing material can be easily obtained without protecting the hole wall of the columnar wall hole 15 by the shape holding frame 5 and involving surrounding earth and sand. 4 can be removed and replaced. Thereby, the underground purification | cleaning wall main body 3 used as the purification | cleaning area | region of the groundwater 12 can be renovated easily.

  A construction method of the underground purification wall 1 having the above-described configuration will be described below with reference to FIGS. 5 and 6. In the present embodiment, the case where the U-shaped holding frame 5 having a U-shaped cross section using the water-permeable belt-like material shown in FIG.

<First step>
First, the casing 14 is positioned at the planned construction position of the underground purification wall 1, and as shown in FIG. 5 (a), this is penetrated into the ground and the inside thereof is discharged. As for the method of penetrating the casing 14, for example, an earth auger or the like is inserted into the inside of the casing 14, and after excavating and discharging the ground with the earth auger, the intermediate excavation method or the casing 14 is press-fitted, Any means such as a method of discharging the inside with a bucket may be used.

  When the tip of the casing 14 reaches the impermeable layer 13, the penetration and earth removal work is finished, and as shown in FIG. 5B, the shape holding frame having a rectangular shape whose size is inscribed in the casing 14. 5 is inserted into the casing 14, and as shown in FIG. 5C, the pollutant adsorbing material 4 is filled inside the shape retaining frame 5 and the drain material 2 is filled outside. At this time, the shape holding frame 5 is positioned in the casing 14 so that the opening w faces the extending direction of the underground purification wall main body 3.

<Second process>
Next, after the casing 14 is pulled out from the ground, as shown in FIG. 5D, the casing 14 is positioned so that the outer peripheral surface is in contact with the opening w of the shape retaining frame 5 installed in advance. In a manner, the casing 14 is re-penetrated into the ground and the inside thereof is discharged. Thus, the opening w of the shape retaining frame 5 installed in advance leads to function as a guide for penetrating the casing 14 adjacent thereto.

Thereafter, as shown in FIG. 5 (e), a new shape holding frame 5 is inserted inward of the casing 14, and as shown in FIG. 5 (f), the inside of the shape holding frame 5 and the shape holding frame. 5 is filled with the contaminant adsorbing material 4 in the space surrounded by the connection member 52 and the casing 14, and the drain material 2 is filled in the space surrounded by the water-permeable surface member 51 and the casing 14 of the shape holding frame 5. Then, the casing 14 is pulled out. Also at this time, the shape retaining frame 5 is positioned in the casing 14 so that the opening w faces the extending direction of the underground purification wall body 3.
Such a 2nd process is repeated until the underground purification | cleaning wall 1 becomes desired wall body length.

  According to the method described above, the shape holding frame 5 installed downstream is connected at the opening w position of the shape holding frame 5 installed in advance as shown in FIG. A linear wall body having a wall thickness with a length equal to the chord length formed in the overlapping portion between the columnar hole 151 formed in the step and the columnar hole 151 formed in the second step is formed.

  Accordingly, the underground purification wall main body 3 is a linear wall body that occupies only the central portion of the columnar row holes 15 whose outer shape is constructed by continuously connecting the plurality of columnar holes 151. Compared with the case where the entire pollutant adsorbing material 4 is filled in the holes 15, there is no waste in the pollutant adsorbing material 4.

  In addition, in said method, the clearance gap for the member thickness of the casing 14 arises between the opening part w of the shape holding frame 5 installed previously, and the shape holding frame 5 adjacent to this. When there is a possibility that the contaminant adsorbing material 4 flows out from the gap, as shown in FIG. 3 (d), it can be deformed along the inner peripheral surface of the casing 14 and restored when the casing 14 is pulled out. Then, an elastic member 53 such as a brush or a rubber plate for preventing the contaminant adsorbing material 4 from flowing out may be provided in advance on the long side on the side where the opening of the shape holding frame 5 is formed.

  Further, as described above, the wall thickness of the underground purification wall main body 3 can be freely adjusted by the length of the connecting member 52. Therefore, when it is desired to secure a large wall thickness, as shown in FIG. 6A, the shape holding frame 5 in which the connecting member 52 is longer than the short side of the water-permeable surface member 51 may be employed. On the other hand, when it is desired to reduce the wall thickness of the underground purification wall main body 3, as shown in FIG. 6 (b), the shape holding frame 5 in which the connecting member 52 is shorter than the short side of the water-permeable surface member 51 is adopted. do it.

  Thus, by using the shape retaining frame 5 in which the length of the connecting member 52 is adjusted while ensuring a cross section in a size inscribed in the casing 14, the underground purification wall main body 3 formed to have a desired wall thickness. It becomes possible to construct the underground purification wall 1 containing the.

  By the way, in this Embodiment, in order to grasp | ascertain the degree to which the purification function of the groundwater 12 fell in exchanging the contaminant adsorption material 4, the water sampling pipe | tube 6 is installed in the underground purification | cleaning wall main body 3. FIG.

  Specifically, as shown in FIG. 2, in the vicinity of the groundwater outflow surface 32 of the underground purification wall main body 3, a plurality of water sampling pipes 6 are installed at intervals along the water-permeable surface member 51. All of the height positions of the water sampling ports 61 are installed within the same height range as the permeable layer having the contaminated ground 11, and the groundwater 12 in the underground purification wall body 3 is collected through the water sampling pipe 6. .

  Then, the ground water 12 is periodically collected from the water sampling pipe 6 to monitor the pollutant concentration in the ground water 12. When the pollutant concentration increases and the purification target value is no longer met, or immediately before that, it is determined that the degradation of the function of the pollutant adsorbent 4 has progressed to the groundwater outflow surface 32 side of the underground purification wall body 3. Then, the contaminant adsorbing material 4 is replaced.

  In this way, the water sampling pipe 6 is installed near the groundwater outflow surface 32 in the underground purification wall main body 3, and the groundwater 12 in the underground purification wall main body 3 is regularly monitored by the pollutant concentration. It becomes possible to evaluate the soundness of the substance adsorbing material 4 and objectively determine the optimum replacement time.

  The plurality of sampling pipes 6 may be installed at any arrangement interval. For example, as shown in the cross-sectional view in the extending direction of FIG. When the shape retaining frame 5 employing a water-permeable belt-like material is used, the water sampling pipes 6 may be arranged in the regions divided by the connecting member 52. Thereby, since the soundness of the pollutant adsorbent 4 can be evaluated for each section, the replacement timing of the pollutant adsorbent 4 can be grasped for each section, and the maintenance work of the underground purification wall body 3 is economical. It becomes possible to carry out.

  In addition, as shown in the cross-sectional view in the extending direction of FIG. 4B, the plurality of water sampling pipes 6 have a height position of the water sampling port 61 within the same height range as the water permeable layer having the contaminated ground 11. It may be installed differently. If it carries out like this, it will become possible to evaluate the soundness of the contaminant adsorption material 4 for every depth direction in the underground purification | cleaning wall main body 3. FIG.

  Furthermore, the arrangement method of the water sampling pipe 6 is not limited to the above-described method, and as shown in the sectional views in the wall thickness direction of FIGS. A plurality of the three wall thickness directions may be arranged at intervals.

  Of course, as shown in FIG. 7A, the contaminant adsorbent 4 in the underground purification wall main body 3 has a function deterioration in the vicinity of the groundwater inflow surface 31 after the start of operation, and the function deterioration due to the use over time. As shown in FIG. 7 (b), it gradually proceeds toward the groundwater outflow surface 32.

  Accordingly, the groundwater 12 is periodically collected from each of the plurality of sampling pipes 6 arranged with an interval in the wall thickness direction, the pollutant concentration is measured, and the number of years until the pollutant concentration does not satisfy the purification target value. That is, the time required for the contaminant adsorbent 4 in the vicinity where each of the water sampling pipes 6 is located to function is measured.

  Thus, the operation of the underground purification wall 1 is performed based on the relationship between the distance from the groundwater inflow surface 31 to the arrangement position of each of the sampling pipes 6 and the time required for the function deterioration of the contaminant adsorbent 4 located in the vicinity of the drainage pipe 6. After the start, it is possible to predict the period of time required for the deterioration of the function of the contaminant adsorbing material 4 to reach the groundwater outflow surface 32 side, that is, the lifetime of the underground purification wall 1. Thereby, it becomes possible to grasp in advance the replacement time of the pollutant adsorbent 4 and to carry out the renovation work of the underground purification wall main body 3 in a planned manner.

  In the present embodiment, the number of sampling pipes 6 arranged in the wall thickness direction of the underground purification wall main body 3 is three, but the number is not necessarily limited to this. What is necessary is just to adjust the number of the water sampling pipes 6 according to the wall thickness of the underground purification | cleaning wall main body 3, the precision calculated | required by lifetime prediction, etc. suitably.

  Needless to say, the underground purification wall 1 of the present invention is not limited to the above embodiment, and various modifications can be made without departing from the spirit of the present invention.

  For example, in the present embodiment, the shape retaining frame 5 is formed as a long member that reaches the water-impermeable layer 13 from the vicinity of the ground surface by one body. You may form so that it may become the length which reaches the impermeable layer 13 from the earth surface vicinity by connecting to.

DESCRIPTION OF SYMBOLS 1 Underground purification wall 2 Drain material 3 Underground purification wall main body 31 Groundwater inflow surface 32 Groundwater outflow surface 4 Contaminant adsorption material 5 Shape retention frame 51 Water permeability surface member 511 Non-woven fabric 512 Wire net 513 Rectangular frame 52 Connection member 53 Elastic member 6 Sampling pipe 61 Sampling port 11 Contaminated ground 12 Ground water 13 Impermeable layer 14 Casing 15 Drilling hole L Site boundary

Claims (5)

An underground purification wall for purifying contaminated groundwater,
The underground purification wall is composed of an underground purification wall main body made of a pollutant adsorbing material and a water-permeable shape retaining frame, and a drain material covering the underground purification wall main body,
The shape retaining frame formed in a rectangular shape having a plan view cross-sectional size inscribed in the casing and having an opening in at least one side is inserted into the ground and the inside of the casing is earthed. A first step of removing the casing by filling the pollutant adsorbing material inside the shape retaining frame and filling the drain material outside the shape holding frame, respectively.
The casing is positioned so that the outer peripheral surface is close to the opening of the shape retaining frame, penetrates into the ground, and the inside of the casing is evacuated, and then the new shape retaining frame is inserted into the casing. A subsurface purification wall formed by a second step of filling the contaminant adsorbing material inside the holding frame and filling the drain material outside and removing the casing. In the underground purification wall according to claim 1,
An underground purification wall characterized by repeating the second step a plurality of times. In the underground purification wall according to claim 1 or 2,
The shape holding frame is made of a water-permeable belt-like material, and has a pair of water-permeable surface members facing each other in parallel with a gap, and a connecting member installed so as to hold the arrangement interval of the water-permeable surface members. Prepared,
An underground purification wall, wherein the pair of water-permeable surface members are inserted into the casing such that the short sides are in the horizontal direction and the long sides are in the vertical direction. In the underground purification wall according to claim 3,
The connecting member is a rod-shaped member,
An underground purification wall, wherein a plurality of the water-permeable surface members are arranged at intervals so as to be substantially in the center of the short side and parallel to the long side. In the underground purification wall according to claim 3,
The connecting member is made of a water-permeable belt-like material,
An underground purification wall characterized by being arranged so as to connect the long sides facing each other in the pair of water-permeable surface members.