JP4318747B1 - Contaminated soil purification method - Google Patents

Abstract

Provided is a method for purifying contaminated soil that can purify volatile organic substances (VOC) that have penetrated into cohesive soil using microorganisms.
SOLUTION: A step of drilling a boring hole (4), a step of forming a notch (6) in the drilled boring hole (4), and pressurizing a cleaning agent (P) to the boring hole (4). And supplying a material useful for the growth of microorganisms that decompose contaminated soil as the cleaning agent. In the supplying step, the cleaning agent supplied under pressure is supplied to the borehole (4). The split (7) is advanced from the formed incision (6) to the contaminated area (Zv) in the soil, and the purification agent (P) is injected into the contaminated area (Zv) through the split (7).
[Selection] Figure 4

Description

 The present invention relates to a contaminated soil purification technique, and more particularly to a technique capable of purifying contaminated soil using microorganisms.

Conventionally, excavation and removal has been the mainstream for the purification of contaminated soil, which is environmental purification. However, the purification of contaminated soil by excavation and removal requires transportation costs such as the removal of excavated contaminated soil and the introduction of non-contaminated soil to be newly replaced, and the processing of the removed contaminated soil requires a large amount of cost. There was a problem.
Therefore, it is predicted that environmental purification by microorganisms will become the mainstream in the future.
As a method for environmental purification by microorganisms, for example, a method of injecting nutrient salts (materials useful for the propagation of microorganisms) into the ground can be mentioned.
Here, the VOC may contaminate the soil over a wide area by groundwater. Therefore, in Europe and the United States, for soil contamination, the concentration of contamination such as volatile substances (VOC) contained in groundwater is a criterion for evaluation.
On the other hand, in Japan, the pollutant elution amount per unit volume (for example, 1 m ³ ) of soil is a criterion for evaluation.

In Europe and the United States, where the contamination level of groundwater is the standard for evaluation, the soil contamination standard can be cleared by purifying the groundwater.
On the other hand, in Japan, where the amount of pollutant elution in the soil is the standard, it is not possible to clear the standard for soil contamination simply by purifying the groundwater. In particular, when VOC penetrates into the poorly permeable layer, it has been difficult to purify to the extent that the soil contamination standard can be cleared without excavating and removing the hardly permeable layer into which the VOC has penetrated.
In other words, it has been conventionally requested to purify the VOC penetrating into the poorly permeable layer by a technique other than excavation and removal, but at the present time, such a request cannot be met.
In addition, as described above, as for the technique for purifying contaminated soil using microorganisms, the actual situation is that a good technique is not sufficiently disclosed.

As another conventional technique, a wall for purification using microorganisms is constructed on the downstream side of the VOC-contaminated area, and groundwater flowing through the contaminated area passes through the wall, so that the VOC contained in the groundwater is A technique for decomposing has been proposed (see Patent Document 1).
However, such a prior art (Patent Document 1) is effective when the groundwater can be purified as in Europe and the United States, but it is effective, but the VOC penetrating into the poorly permeable layer is purified. There is no contribution to the problem.

JP 2008-238027 A

  The present invention has been proposed in view of the above-described problems of the prior art, and provides a method for purifying contaminated soil that can purify volatile organic substances (VOC) that have permeated into a poorly permeable layer using microorganisms. It is an object.

  The method for purifying contaminated soil according to the present invention comprises a step of drilling the boring hole (4) with a drilling and cleaning agent injection device (monitor 2) provided at the tip of the injection rod (1), and a drilling and cleaning agent injection. A step of forming a notch (6) at a position on the inner wall surface (4s) of the borehole (4) and forming a split (7) in the region of the hardly water-permeable layer (Gc) by the device (2); 6) Disposing and expanding the packer (10) above and below the region where the region is formed, and supplying the purifier (P) while pressurizing the region sandwiched between the upper and lower packers (10) In the supply step, the splitting (7) is generated in the hardly water-permeable layer (Gc) from the notch (6) formed in the borehole (4) by supplying the purifying agent (P) under pressure. And the split (7) reaches the contaminated area (Zv) Supplied cleaning agent while applying (P) is characterized by being injected into the contaminated area (Zv) through Wari裂 (7) which developed (claim 1).

  In this invention, it is preferable that the notch | incision (6) formed in a boring hole (4) is formed over the circumferential direction perimeter of a boring hole inner wall surface (4s) (refer FIGS. 1-4).

Or it is preferable that the notch | incision (6) formed in a boring hole (4) is formed in a part of circumferential direction of an inner wall surface (4s) of a boring hole (refer FIGS. 8-11).
At that time, it is preferable that the range of the notch (6) formed in the boring hole (4) is narrowed to cause the split (7) to develop into a single crack (see FIGS. 12 to 16).

  Further, in the present invention, prior to the supplying step, it is preferable to excavate a second boring hole (guide hole) (14) in a region where the splitting (7) should progress (a region where contaminants are present) ( FIG. 17 to FIG. 21).

  Further, the method for purifying contaminated soil according to the present invention includes a step of drilling the boring hole (4) by a drilling and cleaning agent injection device (monitor 2) provided at the tip of the pouring rod (1), and drilling and purification. A step of forming a notch (6) at a position where the agent injection device (2) forms a split (7) in the inner wall surface (4s) of the boring hole (4) and the region of the hardly water-permeable layer (Gc); A step of disposing and expanding the packer (10) above and below the region where the cut (6) is formed, and supplying the purifier (P) while pressurizing the region sandwiched between the upper and lower packers (10). In the supply step, the splitting agent (Pc) is split into the hardly permeable layer (Gc) from the cut (6) formed in the boring hole (4) by supplying the purifier (P) under pressure. ) Progresses and the split (7) reaches the contaminated area (Zv) Then, the purifier (P) supplied while being pressurized is injected into the contaminated area (Zv) through the advanced split (7), and split when the purifier (P) is pressurized and supplied in the supply step. (7) is characterized by having a step of separately drilling a boring hole (24) for injecting a cleaning agent within a range in which (7) progresses.

Furthermore, the contaminated soil purification method of the present invention includes a step of drilling the borehole (4) with a drilling and cleaning agent injection device (monitor 2) provided at the tip of the injection rod (1), and a drilling and cleaning agent. A step of forming an incision (6) at a position where the splitting (7) of the region of the hardly water-permeable layer (Gc) is formed by the injection device (2) on the inner wall surface (4s) of the borehole (4); The incision is continuous in a direction perpendicular to the inner peripheral surface of the borehole, and the step of disposing and expanding the packer (10) above and below the region where the incision (6) is formed, and the upper and lower packers ( 10) having a supply step of supplying the purifying agent (P) while pressurizing the region sandwiched in 10). In the supply step, the purifying agent (P) is pressurized and supplied to form the bore hole (4). From the cut (6) made in the poorly permeable layer (Gc) The split (7) develops, the split (7) reaches the contaminated region (Zv), and the purifier (P) supplied while applying pressure to the contaminated region (Zv) through the advanced split (7). It is characterized by having an injecting step (Claim 4: see FIGS. 23 to 26).
However, it is also possible to form the cut (7) in the inner peripheral surface of the boring hole intermittently in the vertical direction (see FIGS. 1 to 22).

 Here, it is preferable to measure the position of the contaminated region prior to the step of drilling the boring hole (4) (see FIGS. 5 to 7).

  The upper packer (10) can be provided on a rod (1) to which a drilling and cleaning agent injection device (2: monitor) is attached, or a rod (1) provided separately from the rod (1). (Not shown).

  In carrying out the present invention, in the step of supplying the purifying agent (P) while pressurizing, the pressure of supplying the purifying agent (P) is dynamically changed (the injection pressure of the purifying agent P is dynamically changed). preferable.

In implementing the present invention described above, in the step of forming the notch (6), the vertical interval (Δy = 2ΔL) of the notch (6) is:
It is represented by the formula “2 (k · Δh · T) ^1/2 ” (cm),
Here, “k” is the hydraulic conductivity (cm / year) of the soil where the incision (6) (or split 7) is formed, and “Δh” is the pressure of the split (7) adjacent to the pressure of the split (7) in the vertical direction. Water head difference (cm) corresponding to the differential pressure of pore water pressure at the intermediate point, “T” is the set time (year) for the purifier (P) to penetrate the intermediate point of the split (7) adjacent in the vertical direction. It is preferable (Claim 3).

According to the present invention having the above-described configuration, the purifying agent is injected into the contaminated area through the split developed by the purifying agent supplied while pressurizing the purifying agent into the borehole, and the purifying agent decomposes the contaminated soil. Because it contains materials useful for the growth of microorganisms, microorganisms in the soil (microorganisms that decompose contaminated soil) are activated by the supply of a cleaning agent, and pollutants in the contaminated area are activated by activated microorganisms. Since it is decomposed, purification of contaminated soil by microorganisms can be realized.
Here, since the cleaning agent is injected into the contaminated area in the soil by splitting, the amount of slime (for example, a mixed fluid of the cleaning agent and the soil) generated in the construction of the present invention is, for example, when excavated by a jet Compared to Therefore, the labor and cost for processing the slime, which is industrial waste, are also greatly reduced.
Moreover, since the splitting progresses from the cut formed in the borehole, the splitting surely progresses to the contaminated region by forming the cut at an appropriate position.

  In the present invention, if the cut formed in the boring hole is formed in a part of the inner wall surface of the boring hole in the circumferential direction (Claims 3 and 4), the split is developed only in a predetermined range in the circumferential direction. Thus, it is possible to prevent the splitting from progressing in the area where the contaminated area does not exist, thereby saving the amount of the purifier used.

Here, in the case where the progress direction of the split is limited (claims 3 and 4), there is a possibility that the split does not progress in a region where the contaminant exists.
On the other hand, according to the present invention, if the second boring hole is excavated in the region where the splitting should progress, that is, the contaminated region, before supplying the purifying agent under pressure (Claim 5), the excavated second Therefore, when the cleaning agent is supplied under pressure, the splitting surely progresses to the contaminated area.
Therefore, the purification agent is reliably injected into the contaminated area, the microorganisms are activated and propagated in the contaminated area, and the contaminants present in the contaminated area to be purified are reliably decomposed by biological action. And waste of a purifier is prevented.

 In the present invention, if a drilling hole is separately drilled within a range in which splitting progresses when the purifying agent is supplied under pressure (Claim 6), the purifying agent is additionally charged using the borehole as an injection well. It is possible to activate and propagate microorganisms in the ground. Alternatively, it is possible to observe and measure the progress of soil purification by microorganisms using the borehole as an observation well.

Further, in the present invention, if the incision in the inner peripheral surface of the boring hole is formed intermittently in the vertical direction (Claim 7), the splitting reaches any one of the vertical regions of the contaminated soil, and thus progresses. The number of splits and the amount of cleaning agent can be saved.
However, when the vertical dimension of the contaminated soil is extremely short (in the case of a contaminated area that is thin in the vertical direction), for example, as shown in FIG. 25, the developed split may not hit the contaminated area.
On the other hand, in the present invention, if the cuts are continuously formed in the vertical direction (Claim 8), the vertical dimension of the contaminated soil is extremely high because the vertical splits propagate in the soil. Even in the short case (in the case of a thinly contaminated area in the vertical direction), the splitting can surely hit the contaminated soil and supply a cleaning agent to activate and propagate the microorganisms.

 In the present invention, if the position of the contaminated area is measured prior to the step of drilling the boring hole (Claim 9), the position of the contaminated area can be grasped in advance by the process, so that the splitting progresses. Thus, the position of the incision can be determined so as to reliably reach the contaminated area.

  Furthermore, in the present invention, when the packer is disposed above and below the region where the cut of the boring hole is formed and the purifier is pressurized and supplied, the packer is expanded (Claim 10). Prior to the development of splitting in the soil, it is possible to prevent a situation where the pressure-supplied purifying agent is ejected to the ground side or leaked downward from the bottom of the borehole into the formation. As a result, the splitting surely progresses in the soil by the purifier supplied under pressure.

It is a figure which shows the drilling process in 1st Embodiment of this invention. It is a figure which shows the notch formation process in 1st Embodiment. It is a figure which shows the process of expanding a packer in 1st Embodiment. It is a figure which shows the split propagation process in 1st Embodiment. It is a figure which shows the method of grasping | ascertaining the position of a contamination area | region. It is a figure which shows the method of grasping | ascertaining the position of a contamination area | region. It is a figure which shows the method of grasping | ascertaining the position of a contamination area | region. It is a figure which shows the notch formation process in 2nd Embodiment of this invention. It is the C2-C2 sectional view taken on the line of FIG. It is a figure which shows the split propagation process in 2nd Embodiment. FIG. 10 is a sectional view taken along line C4-C4 of FIG. It is a plane sectional view showing the cut formation process in a 3rd embodiment of the present invention. In 3rd Embodiment, it is a plane sectional view showing the process in which a split progresses linearly. It is a plane sectional view showing the state where a branch and leaf-like splitting advances in a 3rd embodiment. In 3rd Embodiment, it is a vertical direction sectional view which shows the state where many branch-and-leaf-like splits branched from the linear split apart in the perpendicular direction. In 3rd Embodiment, it is a top view which shows the state which a linear split progresses radially from each of the bore holes created separately, and a branch-and-leaf split progresses between linear splits. In 4th Embodiment of this invention, it is a top view of the state which drilled the several boring hole. In 4th Embodiment, it is a top view which shows the state which drilled the induction hole. In 4th Embodiment, it is a plane sectional view showing the state where a cut was formed. It is a plane sectional view showing the splitting progress process in a 4th embodiment. It is a plane sectional view showing the positional relationship between a boring hole, a developed split and an induction hole in a fourth embodiment. It is a top view which shows 5th Embodiment of this invention. It is a perspective view which shows the notch formation process in 6th Embodiment of this invention. It is a perspective view which shows the split propagation process in 6th Embodiment. It is a figure which shows the inconvenient state when not using 6th Embodiment. It is a figure which shows the effect of 6th Embodiment. It is sectional drawing explaining the space | interval of the notch | incision formed in a boring hole.

Embodiments of the present invention will be described below with reference to the accompanying drawings.
First, a first embodiment of the present invention will be described with reference to FIGS.
In the first embodiment of FIGS. 1 to 4, in the process shown in FIG. 1, for example, in order from the ground surface Gf, the soil composed of the surface layer G1, the sandy soil layer G2, the hardly permeable layer G3, the sandy soil layer G4, A boring hole 3 having a diameter of 10 cm is drilled.
In the illustrated embodiment, the depth from the ground surface Gf to the lower surface of the hardly permeable layer G3 is, for example, 5 m, and the thickness of the hardly permeable layer G3 is, for example, 2 m.

In the step of drilling the boring hole 4 in FIG. 1, the lower and lower ends of the hardly water-permeable layer Gc (with the sandy soil layer Gs) are formed by the drilling hole and the purifier injection device (monitor) 2 attached to the tip of the injection rod 1. Drill to the boundary). In FIG. 1, for example, a 10 cm diameter boring hole 4 is drilled to a depth of 5 m.
When drilling the boring hole 4, it is not preferable to drill with water. This is because the generated slime flows out to the ground side, and there is a possibility that the VOC entrained by the slime may diffuse into the atmosphere. However, such a problem does not occur if slime processing equipment is provided on the ground side to prevent VOC diffusion.
The boring hole 4 is preferably drilled by driving or pushing the monitor 2 into the construction ground. If the boring hole 4 is drilled by driving and pushing the monitor 2, in addition to no slime being generated during drilling, there is no gap between the monitor 2 and the inner peripheral surface of the drilled boring hole 4. This is because the effect of using the packer described later is easily exhibited.

In FIG. 2, the process of forming the notch 6 in the drilled boring hole 4 is shown.
In FIG. 2, a cut 6 is formed by a high-pressure jet in the horizontal direction of the monitor 2 located in the poorly permeable layer Gc of the soil.
In the first embodiment shown in FIGS. 1 to 4, a plurality of cuts 6 having a depth of, for example, 5 cm are formed over the entire circumference in the circumferential direction of the bore wall surface 4s. The notch 6 is formed using, for example, a high-pressure jet. Here, the high-pressure jet forming the cut 6 may be a cross jet (so-called cross jet) which is a pair of jets crossing each other, or a normal single jet (jet).
By forming the cut 6, an artificially weak portion (cut 6) is formed in the hardly water-permeable layer Gc, and the formation and progress of the split 7 described later can be artificially adjusted by the notch effect or stress concentration.

Next, as shown in FIG. 3, the packer 10 built in the monitor 2 is disposed above and below the hardly water-permeable layer Gc in which the cut 6 is formed (installed as a so-called double packer) and inflated.
Here, the upper packer 10 functions as a “plug” that prevents the purifier P injected into the poorly permeable layer Gc from permeating or leaking into the sandy soil layer Gs above the hardly permeable layer Gc. On the other hand, the lower packer 10 functions as a “plug” that prevents the purifier P from permeating or leaking into the sandy soil layer Gs below the hardly water-permeable layer Gc.
The upper packer 10 can be provided on the rod 1 to which the monitor 2 is attached, or can be provided on a rod (not shown) provided separately from the rod 1.
When the lower packer 10 expands and seals, the rod (not shown) for the lower packer is pulled out, and the rod 1 is inserted into the boring hole 4 again.
By disposing and expanding the packer 10 above and below the poorly permeable layer Gc to be subjected to VOC purification treatment, when the pressure-injection of the purification agent described later is performed, purification is performed on the sandy soil layer Gs above and below the hardly permeable layer Gc. It is possible to prevent a situation where a cleaning agent leaks and a cleaning agent is wasted.

FIG. 4 shows a process of supplying the purifying agent P while pressurizing it in a region (the hardly water-permeable layer Gc) sandwiched between the packers 10 in the upper and lower portions in the boring hole 4.
By pressure-injecting the cleaning agent P from the monitor 2, the injection pressure is concentrated on the notch 6 formed in the above process, and the split 7 develops from the notch 6. Here, in FIG. 4, the developed split 7 schematically shows a state of reaching the contaminated region Zv.

As the purifier P to be injected under pressure, a material that has good permeability and is a nutrient for microbial propagation and supplies hydrogen and oxygen as required. Further, as the cleaning agent P, it is preferable to select a material having a large specific gravity, and a hydrophilic material is preferable. From such a viewpoint, for example, sand and a viscous agent are selected as the purifier P.
Even if the poorly water-permeable layer Gc forms a gap, there is a possibility that the time-lapse shrinks. However, since the cleaning agent P is injected under pressure, the split 7 is held without contracting. And since the big space of the split 7 is formed in the poorly water-permeable layer Gc, microorganisms can inhabit easily.

When pressurizing and injecting the purifier P, the drive source of the pump for injecting the purifier P (not shown) arranged on the ground side is controlled to dynamically adjust the injection pressure of the purifier P, for example, sinusoidal, It can be varied as a mixture of pulses.
By dynamically changing the injection pressure of the cleaning agent P, it is possible to promote the development of splitting in the ground and to facilitate the penetration of the cleaning agent P.

  1 to 4, the splitting agent 7 is advanced by the purifier P supplied while being pressurized to the boring hole 4, and the purifier P is supplied to the contaminated region Zv through the split 7. Here, since the purification agent P includes materials useful for the growth of microorganisms that decompose Zv in the contaminated soil, microorganisms in the soil (microorganisms that decompose the contaminated soil) are supplied by the supply of the purification agent P. Activate. And since the pollutant (for example, VOC) in the pollution area | region Zv is decomposed | disassembled by the activated microorganism, the purification | cleaning of the contaminated soil by a microorganism is realizable.

Here, since the cleaning agent P is injected under pressure into the contaminated area Zv in the soil by the split 7, the contaminated soil is cut, mixed, stirred, for example, by jetting the cleaning agent as a jet, and the contaminated soil and Compared to the case of replacement, the amount of the purifier used is much smaller. Therefore, the cost of the purifier can be kept low.
In addition, the amount of slime (for example, a mixture of a purifying agent and VOC-contaminated soil) generated upon implementation in the first embodiment of FIGS. 1 to 4 is also mixed by cutting the contaminated soil by injecting the purifying agent. Compared to the case of stirring, the amount of labor and cost for treating slime, which is an industrial waste, can be greatly reduced because it is much less.
It is also possible to suck VOC from the split region.

FIG. 4 shows a state in which the split 7 has reached the contaminated area Zv, but in order to effectively perform the construction method according to the first embodiment of FIGS. At this stage, it is preferable to grasp the position of the contaminated area Zv.
Therefore, in the illustrated embodiment, as shown in FIGS. 5 to 7, the position of the contaminated area Zv is measured each time the boring hole 4 is excavated. As a result, the Zv position of the contaminated area can be grasped by the prior investigation, and when the purifier is injected under pressure, the split 7 can be developed and reliably applied to the contaminated area Zv.

In order to grasp the position of the contaminated area Zv, the soil is excavated by the monitor 2 provided at the tip of the injection rod 1 (FIG. 5).
As shown in FIG. 6, when excavation is performed until the VOC contamination area Zv is penetrated, the VOC concentration measuring device 8 (FIG. 7) provided at the tip of the monitor 2 detects the VOC.
Thereby, detection of the VOC contamination area | region Zv is attained.

 The preliminary investigation of the VOC contamination area Zv shown in FIGS. 5 to 7 (the step of measuring the position of the contamination area Zv) is not limited to the embodiment of FIGS. 1 to 4, but the second embodiment of FIGS. It is preferable to be executed also in the third embodiment of FIGS. 12 to 15, the fourth embodiment of FIGS. 17 to 21, the fifth embodiment shown in FIG. 22, and the sixth embodiment of FIGS. 23 to 26. .

Next, a second embodiment of the present invention will be described with reference to FIGS.
In 1st Embodiment of FIGS. 1-4, the notch | incision 6 is formed over the perimeter of the circumferential direction of 4s of inner wall surfaces of boring holes. In contrast, in the second embodiment of FIGS. 8 to 11, the notch 6 is not formed over the entire 360 ° circumference, but the notch 6 is formed only in a predetermined partial range, and the partial range is included. The split 7 is advanced from the notch 6 formed only in this. By advancing the split 7 from only a part of the borehole inner wall surface 4s, labor required for forming the notch 6, labor required to advance the split 7 (labor required for high-pressure injection of the purifier P), and The amount of the purifier used can be saved.

In the construction of the second embodiment of the present invention, first, as shown in FIG. 8, a boring hole 4 is excavated in the hardly permeable layer Gc where the VOC contamination region Zv exists, and a notch 6 is formed in the boring hole 4. To do.
A C2-C2 cross section in FIG. 8 is shown in FIG. 9, and a cut 6 is formed in a predetermined range in the circumferential direction of the boring hole 4, that is, a range limited to the central angle θ.
As shown in FIG. 10, when the pressurized cleaning agent P is injected from the monitor 2, the split 7 develops from the cut 6.
As shown in FIG. 11 (C4-C4 cross section in FIG. 10), the split 7 covers the contaminated area Zv. Therefore, the purification agent is reliably supplied to the contaminated region Zv through the split 7 and the labor for generating the split 7 in the region other than the contaminated region Zv (the pressurizing agent P is applied to the region other than the contaminated region Zv). The labor for injection) and the amount of use of the purifier P (injection amount) can be saved.

  In the second embodiment, configurations and operational effects other than those described above are the same as those in the first embodiment shown in FIGS.

A third embodiment will be described with reference to FIGS.
In the third embodiment, the split 7p is linearly developed, and the “width” dimension (horizontal dimension: vertical dimension in FIG. 13) of the developed linear split 7 is extremely small.
The cut 6p is formed in a “hole” shape or a “point” shape in a very narrow range so that the split 7p progresses linearly. By forming the cut 6p in this manner, it is possible to save labor and the amount of the purifier injected for the formation of the cut 6p and the progress of the split 7p.

FIG. 12 shows a horizontal section of the boring hole 4 in the contaminated region Zv, and a dotted (hole-shaped) notch 6p is formed in a part of the inner surface 4s of the boring hole in the circumferential direction. . When the packer (see FIG. 15) is arranged and the cleaning agent P is injected under pressure, as shown in FIG. 13, a single crack-like shape is formed radially outward from the dot-like (hole-like) cut 6p. The split 7p develops. In addition, in order to express easily, in FIGS. 13-15, the single crack-like split 7p is expressed linearly.
When the straight split 7 progresses in the hardly water-permeable layer Gc into a single crack shape, the split 7 branches in a “branch-like shape” at a weak portion in the hardly water-permeable layer Gc, as shown in FIG.
In FIG. 15, in the boring hole 4 closed by the packer 10, a large number of splits 7e are branched from two single crack-like splits 7p that are separated in the vertical direction and extend in parallel in the horizontal direction. Is formed. In FIG. 15, the branch and leaf-shaped split 7 e progresses in a three-dimensional manner.

 In this way, since the splits 7e that grow in a single crack shape are the center (or trunk), a large number of splits 7e progress in the weakly permeable layer, so the cleaning agent P is split 7p. Therefore, the inside of the hardly water-permeable layer Gc is injected three-dimensionally by a large number of branch and leaf-shaped splits 7e.

Further, as shown in FIG. 16, the splits 7e, 7e,... Develop in the form of branches and leaves from the plurality of splits 7p, 7p,. As a result, the splits 7p, 7e develop between the boring holes 4, 4 as a whole and finely, and the purification agent is supplied uniformly and finely to the poorly permeable layer between the boring holes 4, 4, Biological purification of the area contaminated by VOC is performed.
15 and FIG. 16, by forming the linear split 7p, it is possible to finely supply the purifying agent in a three-dimensional manner over the entire contaminated area Zv.

  In the third embodiment shown in FIGS. 12 to 16, the configuration and operational effects other than those described above are the same as those in the first embodiment shown in FIGS. 1 to 7.

A fourth embodiment of the present invention will be described with reference to FIGS.
The fourth embodiment is characterized in that the progress direction of the split 7 is controlled.
In the fourth embodiment shown in FIGS. 17 to 21, the split 7 is advanced from the plurality of boring holes 4 toward the contaminated region Zv in the hardly water-permeable layer Gc.

In the example of FIG. 17, a state is shown in which the contaminated region Zv is present at substantially the center of each boring hole 4 drilled at a location corresponding to the apex of the triangle.
As shown in FIG. 18, in each boring hole 4, a notch 6 is formed in the circumferential direction of the boring hole 4 toward the contaminated region Zv, so that the split 7 can be reliably formed in the contaminated region. It is trying to make progress toward Zv.

In addition, as shown in FIG. 19, a second boring hole (guide hole) 14 is drilled in a substantially central portion of the three boring holes 4 in parallel (that is, in a vertical direction) with the boring holes 4. Yes.
Since the ground is easy to loosen in the area of the ground where the guide hole 14 is drilled, the splits 7a to 7c easily develop from the three bore holes 4.
As shown in FIG. 20, splitting 7 a, 7 b, 7 c develops from the cut 6 when the purifier is injected under pressure in each of the bore holes 4 a, 4 b, 4 c in which the cut 6 is formed. Such splits 7a, 7b, 7c progress toward the region (contamination region Zv) where the guide hole 14 is formed and the ground is easily loosened.
Although not clearly shown, the developed splits 7a, 7b, 7c cover the contaminated area Zv. Therefore, the purification agent is supplied to the contaminated area Zv through the splits 7a, 7b, and 7c.

As described above, according to the fourth embodiment, by cutting the guide hole 14 in the contaminated region Zv in the hardly permeable layer Gc, the splits 7a, 7b, and 7c can be advanced toward the region Zv. .
Further, since the splits 7a to 7c are advanced from the plurality of boring holes 4 and the purifying agent is injected under pressure from the plurality of boring holes 4, the work of injecting the purifying agent into the contaminated region Zv and the biology after the injection It is also possible to shorten the period required for efficient VOC decomposition.
The guide hole 14 can also be used as an injection well and an observation well.

  In the fourth embodiment shown in FIGS. 17 to 21, configurations and functions other than those described above are the same as those in the first embodiment shown in FIGS. 1 to 7.

The fifth embodiment will be described with reference to FIG.
In the fifth embodiment shown in FIG. 22, for example, after the split 7 is formed around the borehole 4, the second borehole 24 (injection well or observation well) is drilled separately from the borehole 4. A cleaning agent is separately injected from the second bore hole 24.
In each embodiment of FIGS. 1-21, the surface of the inner wall surface 4s of the boring hole 4 may not necessarily be smooth (or good). In such a case, even if the packer 10 (see FIGS. 3 and 4) is applied to the boring hole 4, the sealing effect by the packer 10 is hardly exhibited, and the pressure injection of the purifier P may not be performed well. is there.

On the other hand, as shown in FIG. 22, if the cleaning agent injection hole 24 is excavated separately from the bore hole 4, a notch 6 (shown by a dotted line in FIG. 22) is provided to form the split 7. Compared with the bored hole 4, the hole 24 for injecting the purifying agent is not disturbed, the sealing effect by the packer 10 is easily exhibited, and the purifying agent P can be press-fitted well. And since the packer effect is easy to be exhibited, the efficiency of purifier injection improves.
FIG. 22 is a plan view of the construction site, and the radially outer edge of the split 7 in the ground or the radially outermost edge of the extension range of the split 7 is indicated by a dotted line in FIG.

  In the fifth embodiment shown in FIG. 22, the configuration and operational effects other than those described above are the same as those in the first embodiment shown in FIGS. 1 to 7.

The sixth embodiment will be described with reference to FIGS.
In the sixth embodiment, a split (so-called “vertical split”) 7 extending in the vertical direction is formed in the hardly water-permeable layer Gc.
As shown in FIG. 25, there is a case where the contaminated region Zv including VOC (including the sandy soil layer Gs having a high VOC concentration) in the hardly water-permeable layer Gc is extremely thin (the vertical dimension of the contaminated region Zv is extremely small). .
As shown in FIG. 25, when such a thin contaminated region Zv exists between the plurality of splits 7 formed in the borehole 4, even if the split 7 is developed, it does not hit the contaminated region Zv. The cleaner is not injected under pressure into the thin contaminated area Zv.

 On the other hand, as shown in FIGS. 23 and 24, if the split 7 extending in the vertical direction develops, even if the vertical dimension of the region Zv contaminated by the VOC is small, it extends in the vertical direction. Since the existing split 7 is reliably in contact with the contaminated area Zv, the cleaning agent P can be reliably supplied to the contaminated area Zv through the split 7.

In order to advance the split 7 that extends in the vertical direction, first, as shown in FIG. 23, in the boring hole 4, the vertical of the portion L where the split (vertical split) 7 that extends in the vertical direction is to be developed. A continuous cut 6 is formed over the entire directional area.
Then, as described in each of the embodiments of FIGS. 1 to 22, if the purifying agent is pressure-injected into the boring hole 4, as shown in FIG. 24, the vertical split (from the notch 6 shown in FIG. 23). 7 develops over the longitudinal length L.

FIG. 26 shows a state in which the vertical split 7 in FIG. 24 hits the thin contaminated area Zv shown in FIG.
In the state shown in FIG. 25, the cleaning agent P cannot be injected into the vertically contaminated region Zv. However, in the case of the vertical split 7 as shown in FIGS. The region Zv is split and can be biologically purified by supplying a purification agent.
Note that depending on the vertical length L of the vertically split split 7, there is a risk of providing a route for the VOC to move to the sandy soil layer. Therefore, when implementing the sixth embodiment of FIGS. Therefore, careful consideration should be given to the soil layer.

  In the sixth embodiment shown in FIGS. 23 to 26, the configuration and operational effects other than those described above are the same as those in the first embodiment shown in FIGS.

In the embodiment of FIGS. 1 to 22, a plurality of cuts 6 are formed in the region of the poorly water-permeable layer Gc of the borehole 4, but the interval between the cuts 6 in the vertical direction (arrow Vt direction in FIG. 27) ( (Pitch) will be described with reference to FIG.
In FIG. 27, the boring hole 4 is excavated in the hardly permeable layer Gc, and the split 7 extending in the horizontal direction (arrow H direction) is shown near the bottom of the boring hole 4. The split 7 is formed by forming notches (not shown in FIG. 27) in the boring hole 4 and then sealing the upper and lower portions of the notches with packers (not shown) and pressurizing and injecting the cleaning agent P with an injection device (not shown). ing.

In FIG. 27, the pressure at the tip position P7 of the split 7 (pressure after pressure injection) is indicated by a water head h1. Then, on the extension of the split 7, the pressure (pore water pressure) at the position P8 that is separated from the tip position P7 by the distance ΔL is indicated by the water head h2.
Here, in FIG. 27, the code | symbol LH has shown the free water surface.
In the state shown in FIG. 27, the purifier P penetrates from the tip position P7 of the split 7 toward the position P8 as shown by the arrow A27.

Considering the distance that the purifier P moves, with the hydraulic conductivity of the viscous soil constituting the hardly water permeable layer Gc being “k”.
Since the moving gradient (dynamic gradient) “i” of the purifier P is “hydraulic head difference / permeable layer length”,
i = Δh / ΔL = (h1−h2) / ΔL (Formula 1)
If the speed at which the purifier P penetrates the poorly permeable layer Gc is “V”,
V = k · i (Formula 2)
If the time for the cleaning agent P to move from the tip position P7 of the split 7 to the position P8 is T,
V = ΔL / T (Formula 3)
From Formula 2 and Formula 3, V = ΔL / T = k · i (Formula 4)
Substituting Equation 1 into Equation 4,
ΔL / T = k · Δh / ΔL
∴ (ΔL) ² = k · Δh · T
ΔL = (k · Δh · T) ^1/2 (Formula 5)

Here, if the clay is the same, the speed V at which the purifier P penetrates is considered to be substantially the same in the horizontal direction (arrow H direction) and in the vertical direction (arrow Vt).
If the plurality of splits 7 are formed at intervals in the vertical direction in the embodiment of FIGS. 1 to 22, the interval between the splits 7, that is, the vertical interval of the cuts 6, is sandwiched between the splits 7 adjacent in the vertical direction. The region should be determined so that the purifier P penetrates when the predetermined time T has elapsed.
In the region sandwiched between the splits 7 adjacent in the vertical direction, the purifier P penetrates from both the upper split 7 and the lower split 7. As described above, the purifier P permeates the distance ΔL when the time T elapses. Therefore, when the time T has elapsed, the vertical interval between the splits 7 is 2ΔL in order for the purifier P to penetrate all the regions sandwiched between the splits 7 adjacent in the vertical direction.
In other words, the vertical interval Δy of the cut 6 is expressed by the following expression 6.
Δy = 2ΔL = 2 (k · Δh · T) ^1/2 (Formula 6)
Here, “k” is a hydraulic conductivity, “Δh” is a hydraulic head difference corresponding to the differential pressure of the pore water pressure at the midpoint of the split 7 adjacent to the pressure of the split 7 in the vertical direction, and “T” is the split adjacent to the vertical direction. 7 is a set time for the purifier P to permeate into the middle point.

The hydraulic conductivity k of a general clay is k = 1 × 10 ⁻⁵ cm / sec≈315 cm / year.
In addition, the pore water pressure at the position P8 in FIG. 27 is substantially equal to the pore water pressure at the intermediate point between the splits 7 adjacent in the vertical direction. Assuming that the water head difference between the position P7 and the position P8 in FIG. 27 is 10 cm, the water head difference “Δh” corresponding to the pressure difference between the pore water pressure at the midpoint of the split 7 adjacent to the pressure in the vertical direction is also 10 cm. It becomes.
Then, assuming that the time T during which the purifier P penetrates into the midpoint between the splits 7 adjacent in the vertical direction is half a year (0.5 years), T = 0.5 (years).
Substituting such conditions into Equation 6,
Δy = 2 · {315 (cm / year) · 10 (cm) · 0.5 (year)} ^1/2
= 2 · {1575 (cm)} ^1/2
The vertical interval between the notches 6 is Δy≈80 cm.

The illustrated embodiment is merely an example, and is not intended to limit the technical scope of the present invention.
For example, in the illustrated embodiment, the progress of splitting and the injection of the purifying agent are performed in the order from the vertically lower region to the upper region. However, conversely, the splitting may progress and the cleaning agent may be injected in the order from the vertically upper region to the lower region.

Gs ... Sandy soil layer Gc ... Viscous soil layer, poorly permeable layer P ... Purifier Zv ... Contamination zone 1 ... Injection rod 2 ... Monitor 4... Boring hole 4 s... Bore wall surface 6... Cut 7 .. split 8 .. VOC concentration measuring device 14. .... Hole for injecting cleaner

Claims (4)

The step of drilling the boring hole (4) by the drilling and cleaning agent injection device (2) provided at the tip of the injection rod (1), and the boring hole (4) by the drilling and cleaning agent injection device (2). A step of forming a cut (6) at a position on the inner wall surface (4s) where the split (7) of the region of the hardly permeable layer (Gc) is formed, and above and below the region where the cut (6) is formed. A step of disposing and expanding the packer (10) and a supply step of supplying the purifier (P) while pressurizing the region sandwiched between the upper and lower packers (10). When the agent (P) is pressurized and supplied, the split (7) develops from the notch (6) formed in the borehole (4) into the poorly permeable layer (Gc), and the split (7) becomes a contaminated region. The purifier (P) that has reached (Zv) and was supplied with pressure has progressed Purification method of contaminated soil, characterized in that via the Wari裂 (7) are injected into the contaminated area (Zv). The step of drilling the boring hole (4) by the drilling and cleaning agent injection device (2) provided at the tip of the injection rod (1), and the boring hole (4) by the drilling and cleaning agent injection device (2). A step of forming a cut (6) at a position on the inner wall surface (4s) where the split (7) of the region of the hardly permeable layer (Gc) is formed, and above and below the region where the cut (6) is formed. A step of disposing and expanding the packer (10) and a supply step of supplying the purifier (P) while pressurizing the region sandwiched between the upper and lower packers (10). When the agent (P) is pressurized and supplied, the split (7) develops from the notch (6) formed in the borehole (4) into the poorly permeable layer (Gc), and the split (7) becomes a contaminated region. The purifier (P) that has reached (Zv) and was supplied with pressure has progressed Injecting into the contaminated area (Zv) through the split (7), the cleaning agent injection boring within a range where the split (7) develops when the cleaning agent (P) is pressurized and supplied in the supplying step. A method for purifying contaminated soil, comprising a step of separately drilling holes (24). In the step of forming the cut (6), the vertical interval (Δy) of the cut (6) is:
It is represented by the formula “2 (k · Δh · T) ^1/2 ” (cm),
Here, “k” is the hydraulic conductivity (cm / year) of the soil where the incision (6) (or split 7) is formed, and “Δh” is the pressure of the split (7) adjacent to the pressure of the split (7) in the vertical direction. Water head difference (cm) corresponding to the differential pressure of pore water pressure at the intermediate point, “T” is the set time (year) for the purifier (P) to penetrate the intermediate point of the split (7) adjacent in the vertical direction. A method for purifying contaminated soil according to any one of claims 1 and 2. The step of drilling the boring hole (4) by the drilling and cleaning agent injection device (2) provided at the tip of the injection rod (1), and the boring hole (4) by the drilling and cleaning agent injection device (2). A step of forming a cut (6) at a position on the inner wall surface (4s) where the split (7) in the region of the hardly permeable layer (Gc) is formed, and the cut is perpendicular to the inner peripheral surface of the borehole The step of disposing and expanding the packer (10) above and below the region where the incision (6) is formed and the region between the upper and lower packers (10) and the purifier (P ) In a pressure supply state, and in the supply step, the hardly permeable layer (Gc) is formed from the cut (6) formed in the borehole (4) by supplying the purifier (P) under pressure. ) During which the split (7) develops and the split (7) becomes contaminated A purification method for contaminated soil, characterized in that it has a step of injecting the purifying agent (P) that has reached (Zv) and supplied under pressure into the contaminated area (Zv) through the advanced split (7). .

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