JP3831769B2 - Purification equipment and purification method for contaminated soil - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a facility and method for purifying and repairing soil that has been infiltrated with contaminants.
[0002]
[Prior art]
Volatile organic compounds such as trichlorethylene, tetrachloroethylene, 1,2 dichloroethane, 1,1,1-trichloroethane, 1,1,2-trichloroethane have high utility value and are widely used in various industrial fields. However, if these volatile organic compounds are discarded into the soil or leak into the soil, serious contamination of the soil and groundwater will occur. Also, when oils and fats such as gasoline are discarded or leaked into the soil, the soil and groundwater are contaminated. That is, the pollutant in the soil penetrates deep into the ground and stays in a liquid state or vaporizes and stays as harmful gas in the soil.
The organic compounds are known to have carcinogenicity, and the mixing of such substances into groundwater must be strictly regulated. In addition, fats and oils may emit a strong odor, and it is necessary to eliminate contamination with groundwater.
[0003]
Under such circumstances, a method for extracting / removing contaminants in the soil gap has been proposed. For example, JP 2000-51834 A discloses the following method.
In this method, as shown in FIG. 7, a water-impervious wall 102 is constructed so as to surround the contaminated ground 101, and a water injection well 103 and a pumping well 104 are formed in a desired area in the region surrounded by the water-impervious wall. Build at intervals. Water is injected into the water injection well 103 from the outside by a pump 105, and a submersible pump 106 is disposed in the pumping well 104. And after pumping up groundwater with the pumping well 104, water is injected from the water injection well 103, the contaminated ground 101 is fully moistened, and pumped up again. The pumped-up groundwater is sent to the treatment tank 107 installed on the ground and detoxified. These operations are repeatedly performed as appropriate, and the contaminated ground 101 is purified.
[0004]
[Problems to be solved by the invention]
However, the method of treating groundwater containing pollutants on the ground as described above requires a large treatment facility on the ground, and if the period required for purification becomes longer, the cost for operating the treatment facility and maintenance management are required. The cost will be enormous and the economy will deteriorate.
In addition, the pollutants are likely to stay in the vertical direction depending on the specific gravity. Oils and fats having a small specific gravity tend to stay at the upper part of the groundwater surface, and volatile organic compounds having a large specific gravity can stay in a deep position. For this reason, if the equipment is changed depending on the position where the pollutant stays, or if a plurality of equipments are installed for purification, the time required for purification becomes longer or the cost increases.
[0005]
The present invention has been made in view of the circumstances as described above, and an object of the present invention is to provide a contaminated soil purification facility and a contaminated soil which can efficiently purify by simple equipment without diffusing the contamination. It is to provide a purification method.
[0006]
[Means for Solving the Problems]
In order to solve the above-mentioned problems, the invention according to claim 1 is characterized in that an underground impermeable wall formed so as to surround an area including soil contaminated with a harmful substance, and is surrounded by the underground impermeable wall. A treatment agent for detoxifying a harmful substance contained in groundwater or an adsorbent for adsorbing a harmful substance is set so that a well into which groundwater flows from a region that is in contact with the groundwater flowing into the well. A purification means including: a pump for pumping up water in the well and returning it to a region surrounded by the underground water-impervious wall; and contamination concentration monitoring for detecting a concentration of harmful substances contained in the groundwater flowing into the well And the pump pumps up the water in the well when the contamination concentration of the water in the well detected by the contamination concentration monitoring device is higher than a predetermined value. Underground shielding Providing clean equipment contaminated soil, characterized in that return to the walled area.
[0007]
In this purification facility, a groundwater flow is formed from the area surrounded by the underground water-impervious wall into the well, and the pollutants in the soil are moved by the groundwater flow. And when the harmful substance contained in groundwater flows in into a well, it is detoxified by contact with a purification | cleaning means, or it adsorb | sucks to adsorption agent. The purified groundwater is returned to the area surrounded by the underground water-impervious wall by the pump and circulated in the soil, so that the soil is well purified in the basement without installing large-scale facilities on the ground. be able to. Moreover, since the contaminated soil is surrounded by the underground water-impervious wall, harmful substances contained in the soil do not diffuse outside the enclosed region.
[0008]
The invention according to claim 2 includes an underground impermeable wall formed so as to surround an area including soil contaminated with a harmful substance, a well into which groundwater flows from an area surrounded by the underground impermeable wall, A purification means comprising a treatment agent that is set so that the groundwater flowing into the well contacts and detoxifies a harmful substance contained in the groundwater or an adsorbent that adsorbs the harmful substance; A pump for pumping water and returning it to the area surrounded by the underground impermeable wall; and a water supply means for supplying water to the area surrounded by the underground impermeable wall; and the well is the underground impermeable wall It is provided so as to be in contact with both the enclosed area and the outside of the area, and includes an openable / closable gate that discharges the water in the well into the soil outside the area surrounded by the underground impermeable wall. It provides a purification facility for contaminated soil.
[0009]
In this purification facility, the water supplied to the area surrounded by the underground impermeable wall flows down in the contaminated soil as an osmotic flow, and flows into the well with the pollutant. At this time, the contaminant comes into contact with the purification means and is adsorbed by the purification treatment or the adsorbent. And if the groundwater in a well is fully purified, it can open | release a gate and can discharge | release it out of the area | region enclosed by the underground impermeable wall. On the other hand, when pollutants remain in the groundwater, they are returned to the area surrounded by the underground water-impervious wall with a pump to prevent the diffusion of the pollutants and continue the purification of the soil by the groundwater flow. Can be made.
[0010]
The invention according to claim 3 is the purification equipment for contaminated soil according to claim 2, wherein the water supply means is a groundwater in an area surrounded by the underground water-impervious wall from the upstream side of the groundwater flow in the surrounding ground. It is assumed that the well is provided in the region and downstream of the groundwater flow.
[0011]
The groundwater flows from the upstream side of the groundwater flow into the region surrounded by the impermeable wall, passes through the soil, and flows into the well. Since the well is provided on the downstream side of the groundwater flow, by opening a gate provided in the well, the groundwater in the well flows out of the region surrounded by the impermeable wall. Therefore, it is possible to continuously purify contaminated soil using natural groundwater flow.
[0012]
The invention according to claim 4 includes an underground impermeable wall formed so as to surround a downstream side and a side portion in the direction of the groundwater flow in an area including soil contaminated with a harmful substance, and A downstream portion of a region surrounded by a wall, provided at a position in contact with both the region and the outside of the region, so that a well into which groundwater flows from the region and a groundwater flowing into the well are in contact with each other A purification means including a treatment agent that is set and detoxifies a harmful substance contained in groundwater or an adsorbent that adsorbs a harmful substance, and pumps up water in the well and is surrounded by the underground impermeable wall The present invention provides a contaminated soil purification facility comprising a pump for returning to a closed area, and an openable and closable gate for discharging water in the well into the soil outside the area surrounded by the underground impermeable wall.
[0013]
In this purification facility, the groundwater flows into the area surrounded by the underground impervious wall by the natural groundwater flow, and moves to the downstream with the pollutants. And when it flows into a well, it contacts with a purification | cleaning means and the detoxification process or adsorption removal of a contaminant is performed. When the contamination concentration of the water flowing into the well is low, the gate can be opened and discharged downstream. Further, when the concentration of the water flowing into the well is high, the pump can return to the area surrounded by the underground water-impervious wall and perform the purification process again. Therefore, it is possible to treat pollutants using a natural groundwater flow, and to reduce the cost for operating the equipment during the purification period.
[0014]
The invention according to claim 5 is the purification equipment for contaminated soil according to claim 2 or claim 4, wherein the well is surrounded by steel pipe sheet piles in which vertical steel pipes are arranged in the ground and these side surfaces are connected. The steel pipe in a portion in contact with the area surrounded by the underground water-impervious wall includes an inlet for introducing ground water into the steel pipe, and a drain for discharging ground water from the steel pipe into the well. It is assumed that the purification means for treating a harmful substance is disposed in the steel pipe.
[0015]
In this purification equipment, a well having a predetermined depth and a predetermined range can be easily formed by the steel pipe sheet pile. Further, by disposing the purification means in a part of the steel pipe forming the well and providing the steel pipe with the introduction port and the discharge port, the contaminant contained in the groundwater can be purified with a simple configuration. Further, the purification means can be pulled up from the steel pipe to the ground, and can be easily replaced or repaired.
[0016]
The invention according to claim 6 is the purification equipment for contaminated soil according to claim 2 or claim 4, wherein the well is surrounded by steel sheet piles in which vertical steel pipes are arranged in the ground and these side surfaces are connected. A first small hole group that communicates from the inside of the well to the steel pipe, and the underground from the inside of the steel pipe. A second small hole group communicating outside the region surrounded by the water-impervious wall is provided, and the gate includes a range in which the first small hole group is provided in the steel pipe, a second small hole group, It is assumed that it is provided so as to partition the range in which is provided.
[0017]
In this purification equipment, since the steel pipe is provided with the gate, the gate can be easily opened and closed from the top of the steel pipe. And in the state where the gate is closed, the groundwater that has flowed into the steel pipe in the portion in contact with the outside of the area surrounded by the underground water-impervious wall is blocked by the gate of the steel pipe, and therefore contains harmful substances. Groundwater is prevented from flowing out of the area surrounded by the impermeable walls. Also, by opening the gate, groundwater is discharged outside this area, that is, uncontaminated soil.
[0018]
The invention according to claim 7 is the purification equipment for contaminated soil according to claim 1 or claim 4, wherein a plurality of the wells are provided, and the flow leads from the region surrounded by the underground impermeable wall to the well. It is assumed that the inlet position in the vertical direction varies depending on each well.
[0019]
Hazardous substances contained in contaminated soil include fats and oils, volatile organic compounds, and the like, and these organic compounds have different specific gravities, and therefore have different residence locations in the vertical direction in the soil. In this purification facility, a plurality of wells are provided, and the inlets to the wells are provided at positions corresponding to the locations where the harmful substances stay in the vertical direction, so that each harmful substance flows into a different well. . A plurality of harmful substances can be efficiently removed simultaneously by disposing a treatment agent or adsorbent corresponding to each harmful substance in the steel pipe that flows into the well.
[0020]
According to an eighth aspect of the present invention, in the contaminated soil purification facility according to the fourth aspect of the present invention, there is provided a contamination concentration monitoring device for detecting the concentration of harmful substances contained in the groundwater flowing into the well.
[0021]
The contamination concentration monitoring device measures the contamination concentration of groundwater flowing into the well. If a concentration higher than a preset value is detected, the groundwater is surrounded by an underground impermeable wall with a pump. Return to the original area and circulate again for repeated treatment of contaminants. And it is possible to prevent the pollutant from diffusing outside the region by discharging only the groundwater whose contamination concentration is below a predetermined value to the outside of the purification region.
[0022]
The invention according to claim 9 is characterized in that an underground impermeable wall is formed so as to surround an area including soil contaminated with a harmful substance, and the underground water in the area surrounded by the underground impermeable wall flows in. A well is provided, and groundwater flowing into the well is brought into contact with a treatment agent that detoxifies the harmful substance or an adsorbent that adsorbs the harmful substance under the ground surface , and the contamination concentration of groundwater in the well is reduced. When the detected contamination concentration is equal to or higher than a predetermined value, the groundwater pumped from the well is returned to the area surrounded by the underground impermeable wall, and the detected contamination concentration is lower than the predetermined value. Until now, the present invention provides a method for purifying contaminated soil, characterized in that groundwater pumped from the well is circulated between the well surrounded by the underground water-impervious wall and the well .
[0023]
In this purification method, the contaminated soil is surrounded by the underground water-impervious wall, so that harmful substances contained in the soil can be prevented from diffusing outside the enclosed region. And groundwater containing a hazardous | toxic substance can be guide | induced in a well and it can be made to contact with a processing agent or adsorption agent in the process, and groundwater can be purified. Groundwater that has flowed into the well is circulated by returning it to the area surrounded by the underground water-impervious wall, and purification can be continued without requiring large-scale facilities on the ground.
[0024]
The invention according to claim 10, in the purification method for polluted soil according to claim 9, wherein the underground impervious wall is upstream of the groundwater flow in the surrounding ground, may be provided to intake of groundwater, the well When the contamination concentration detected in the inside is not more than a predetermined value, the groundwater in the well is discharged out of the region surrounded by the underground water-impervious wall.
[0025]
In this purification method, the contamination concentration of groundwater flowing into the well is measured, and if a concentration below a preset value is detected, this groundwater is discharged outside the area surrounded by the impermeable walls. can do. This makes it possible to remove harmful substances in the soil at low cost by using the groundwater flow. In addition, when a concentration equal to or higher than a predetermined value is detected, the groundwater can be returned to the region surrounded by the impermeable wall, and sufficient purification can be performed without diffusing harmful substances.
[0026]
The invention which concerns on Claim 11 forms an underground impermeable wall so that the area | region containing the soil contaminated with the harmful substance may surround the downstream and the side part in the direction of a groundwater flow, The underground impermeable wall A well is provided in a downstream portion of the region surrounded by the region and in contact with both the region and the outside of the region so that groundwater flows from the region, and the groundwater flowing into the well is When the contamination concentration of the water in the well is higher than a predetermined value, it is brought into contact with a treatment agent for detoxifying the substance or an adsorbent for adsorbing a harmful substance under the ground surface. The water in the well is pumped up and returned to the area surrounded by the underground water-impervious wall, and when the concentration of water in the well is lower than a predetermined value, the water in the well is Contaminated soil released into soil outside the area surrounded by water walls There is provided a purification method.
[0027]
In this method, pollutants can be moved using natural groundwater flow, and detoxification treatment or adsorption removal can be performed when the groundwater flows into the well. Therefore, the use of power for purification is reduced, and the cost can be reduced.
[0028]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, embodiments of the invention according to the present application will be described with reference to the drawings.
FIG.1 and FIG.2 is the schematic plan view and schematic sectional drawing which show the purification equipment which is one Embodiment of the invention which concerns on this application.
This purification equipment is provided in the soil where the groundwater flow exists, and a water shielding wall 2 is constructed so as to surround the soil 1 contaminated with fats and oils and volatile organic compounds. The purification equipment is provided with a plurality of wells 3a and 3b provided on the downstream side of the groundwater flow in the contaminated area A surrounded by the impermeable wall 2, and water in the well is provided on the upstream side in the contaminated area. The main parts are composed of the pumps 5a and 5b sent to the injected water injection wells 4a and 4b and the contamination concentration monitoring device 6 for detecting the contamination concentration of groundwater in the well.
[0029]
And the fats and oils which are pollutants generally have specific gravity smaller than water, and are staying in the soil 1a near a groundwater surface. Further, the volatile organic compound has a specific gravity greater than that of water and stays in the soil 1b on the bottom of the groundwater flow, that is, on the upper side of the impermeable layer 7.
[0030]
The water shielding wall 2 is provided with a steel sheet pile 2a so as to surround the contaminated soil 1, and the upstream side is opened as a water intake 2b so that the groundwater flows into the contaminated area A by the groundwater flow. Has been. The steel sheet pile 2a is vertically built up to a depth that reaches or exceeds the depth at which the soil 1 is contaminated or, if there is an impermeable layer, They are connected to each other to form a wall.
[0031]
The wells 3a and 3b are provided in the downstream portion of the groundwater flow in the contaminated area, and are formed by excavating the inside surrounded by the steel pipe sheet pile. And a part of side wall which consists of a steel pipe sheet pile faces the pollution area | region enclosed by the said water-impervious wall 2, and another part faces the contamination area outside. These steel pipe sheet piles are arranged in a rectangular shape or a circular shape, and are embedded to a depth similar to that of the water shielding wall 2. For example, as shown in FIG. 3, joints 51 and 52 are provided in each of the steel pipe sheet piles, and the adjacent steel pipe sheet piles are connected to each other by the joints 51 and 52 so as to shield groundwater.
[0032]
Further, in each of the wells 3a and 3b, a pumping pipe for pumping up the ground water in the well is built, and water in the well is pumped from the suction ports 5a 'and 5b' by the pumps 5a and 5b. Moreover, the detection part 6a, 6b of the contamination concentration monitoring apparatus 6 is provided in the well, and the density | concentration of the contaminant in a well is detected.
[0033]
As shown in FIG. 2 or 3, the steel pipe sheet piles 21 a and 21 b have groundwater inlets 22 a and 22 b at a portion facing the contaminated area A, and discharge ports 23 a and 23 b at a portion facing the well. , Respectively, are provided corresponding to the positions in the vertical direction where the pollutants stay. And the inside of the pipe | tube of the vicinity in which the inlets 22a and 22b of this steel pipe sheet pile 21a and 21b are formed is filled with the purification agents 24a and 24b which detoxify a harmful substance.
[0034]
As shown in FIG. 3 (b), the purifiers 24a and 24b are accommodated in a bowl-shaped container so that they can be collected, replenished, exchanged, etc. from the upper part of the steel pipe. The portion of the flange 56 that faces the introduction port 22 and the portion that faces the discharge port 23 are composed of a water-permeable member 53 such as a fine mesh or cloth. Moreover, the side part between these is formed with the thin steel material 54 so that water may not permeate | transmit, and the water stop member 55 which consists of an elastic material is attached to the outer surface. Therefore, the water that has flowed into the steel pipe from the introduction port 22 permeates the portion having water permeability and enters the rod 56, and comes into contact with the cleaning agent 24 to treat the contaminant. Then, the water is led from the drain 23 into the well.
[0035]
As the purification agent 24, for example, an oxidizing / reducing agent such as potassium permanganate, iron powder or the like, or an adsorbent such as zeolite or activated carbon is used. A member 53 having water permeability such as a net or cloth is selected so that the above-mentioned housed material does not leak.
[0036]
On the other hand, as shown in FIG. 2 or 4, the first small hole groups 26 a and 26 b are contaminated at the portion facing the inside of the well in the portion separating the steel pipe sheet piles 25 a and 25 b from the outside of the contamination region . Second small hole groups 27a and 27b are formed at positions substantially equal to the inlets 22a and 22b and the outlets 23a and 23b formed in the steel pipe sheet piles 21b and 21b, respectively, in the portion facing the outside of the region A. .
[0037]
And in the steel pipe sheet piles 25a and 25b, it can be opened and closed to partition the range in which the first small hole groups 26a and 26b are provided and the range in which the second small hole groups 27a and 27b are provided. Gates 28a and 28b are provided. The gate 28 can be moved up and down from the upper part of the steel pipe along the guide 57, and can be easily opened and closed from the ground. The guide 57 is provided with an elastic body 58 as a sealing material at a contact portion with the gate 28.
[0038]
Next, a method for purifying contaminated soil using this purification facility will be described.
When groundwater flows in from the water intake 2b where the impermeable wall 2 is opened due to a water head difference and passes through the soils 1a and 1b, oils and fats contained in the soil 1a and volatile organic compounds contained in the soil 1b flow into the groundwater. However, it is discharged downstream with this groundwater. Since fats and fats and volatile organic compounds have different specific gravities, each harmful substance flows into the steel pipe sheet piles 21a and 21b through the inlets 22a and 22b corresponding to the contamination positions in the vertical direction together with the groundwater. And it processes by contacting with the purification agents 24a and 24b in the steel pipe sheet piles 21a and 21b, and the fats and oils and the volatile organic compounds flow into different wells 3a and 3b, respectively.
[0039]
The groundwater flowing into the wells 3a and 3b enters the steel pipe sheet piles 25a and 25b on the downstream side from the first small hole groups 26a and 26b, but is blocked by the gates 28a and 28b in the steel pipe. The contamination concentration monitoring device 6 detects the contamination concentration of groundwater in the well. For each hazardous substance, a reference contamination concentration is set. If the contamination concentration of groundwater is below the reference value, the gate 28 that blocks the groundwater is opened, and the groundwater It flows out of the contaminated area A by its own flow from the two small hole groups 27. On the other hand, when the contamination concentration of the groundwater is equal to or higher than the reference value, the groundwater is pumped up by the pump 5 and returned from the water injection well 4 to the contaminated area. And it passes through the soil 1 containing a harmful substance again, is purified by the purification agent 24 in the steel pipe sheet pile 21, and the groundwater is pumped between the contaminated area A and the well 3 by a pump until the groundwater becomes below the reference value. Circulate.
[0040]
FIG.5 and FIG.6 is the schematic plan view and schematic sectional drawing which show the purification equipment which is other embodiment of the invention which concerns on this application.
This purification equipment is provided in soil where there is no groundwater flow, and purifies soil 31a, 31b contaminated with fats and oils and volatile organic compounds. The contaminated area B including the soils 31a and 31b is surrounded on all sides by a water shielding wall 32, and water is supplied into the contaminated area B from the outside by a pump 33.
[0041]
In the region surrounded by the water shielding wall 32, if the side supplied with water by the pump 33 is the upstream side, wells 34a and 34b are installed on the downstream side. The wells 34a and 34b are similar to the purification equipment shown in FIG. 1, and include steel pipe sheet piles 35a and 35b filled with the purification agents 36a and 36b, and steel pipe sheet piles 37a and 37b including gates 38a and 38b. It is constituted by a plurality of steel pipe sheet piles.
[0042]
In the well, suction ports 39a 'and 39b' of pumps 39a and 39b for pumping up the ground water in the well are provided, and the ground water flowing into the well from the contaminated region B by the pumps 39a and 39b, The water is returned to the contaminated area B from the water injection wells 40a and 40b. A water flow can be generated in the contaminated area B by the circulation of groundwater by the pumps 39 a and 39 b and the water supply to the contaminated area B by the pump 33.
[0043]
When the groundwater supplied into the contaminated area B by the pump 33 passes through the soils 31a and 31b and then flows into the well through the steel pipe sheet piles 35a and 35b, the groundwater comes into contact with the purifiers 36a and 36b and is rendered harmless. Is done. Then, the groundwater is measured for contamination concentration by the contamination concentration monitoring device 41. Depending on the measured value, the groundwater is discharged to the outside of the contamination region B or sent into the contamination region B by the pumps 39a and 39b and purified again. The In addition, when the gates 38a and 38b of the steel pipe sheet piles 37a and 37b are opened, the groundwater flows out due to a water head difference.
[0044]
【The invention's effect】
As described above, in the contaminated soil purification equipment and method according to the present invention, since the contaminated soil is surrounded by an underground impermeable wall, harmful substances contained in the soil are enclosed. The soil is efficiently purified by groundwater without spreading out of the area. The harmful substances contained in the groundwater are easily detoxified or adsorbed by the purification means. In addition, the purified groundwater can be returned to the area surrounded by the underground impermeable wall and purified again by the purification means. On the other hand, well-purified groundwater can be discharged from wells outside the contaminated soil area. In this way, the purification can be continuously performed in the soil, and the purification of the soil can be efficiently performed at a low cost without providing a large-scale facility on the ground.
[Brief description of the drawings]
FIG. 1 is a schematic plan view showing a contaminated soil purification facility according to an embodiment of the present invention.
FIG. 2 is a schematic sectional view of the purification equipment shown in FIG.
3 is a perspective view and a plan sectional view of a portion of a steel pipe sheet pile used in the purification equipment shown in FIG. 1 and filled with a purification agent.
4 is a steel pipe sheet pile used in the purification equipment shown in FIG. 1, and is a perspective view and a plan sectional view of a portion provided with a gate that leads to the outside of a contaminated area.
FIG. 5 is a schematic plan view showing a contaminated soil purification facility according to another embodiment of the present invention.
6 is a schematic sectional view of the purification equipment shown in FIG.
FIG. 7 is a schematic sectional view showing a conventional contaminated soil purification facility.
[Explanation of symbols]
1, 31 Soil 2, 32 Impervious wall 3, 34 Well 4, 40 Injection well 5, 39 Pump 6, 41 Monitoring device 7 Impermeable layer 21, 35 Steel pipe sheet pile 22 Inlet 23 Outlet 24, 36 Purifier 25, 37 Steel pipe sheet pile 26 First small hole group 27 Second small hole group 28, 38 Gate 33 Pump

Claims (11)

An underground impervious wall formed to surround an area containing soil contaminated with harmful substances;
A well into which groundwater flows from an area surrounded by the underground water-impervious wall;
Purifying means that is set so that the groundwater flowing into the well is in contact, and includes a treatment agent that detoxifies harmful substances contained in the groundwater or an adsorbent that adsorbs harmful substances,
A pump that pumps up the water in the well and returns it to the area surrounded by the underground impermeable wall;
A pollution concentration monitoring device that detects the concentration of harmful substances contained in the groundwater flowing into the well, and
When the contamination concentration of water in the well detected by the contamination concentration monitoring device is higher than a predetermined value, the pump pumps up the water in the well and is surrounded by the underground impermeable wall. Purification equipment for contaminated soil, characterized in that it is to be returned to the area . An underground impervious wall formed to surround an area containing soil contaminated with harmful substances;
A well into which groundwater flows from an area surrounded by the underground water-impervious wall;
Purifying means that is set so that the groundwater flowing into the well is in contact, and includes a treatment agent that detoxifies harmful substances contained in the groundwater or an adsorbent that adsorbs harmful substances,
A pump that pumps up the water in the well and returns it to the area surrounded by the underground impermeable wall;
Water supply means for supplying water to the area surrounded by the underground impermeable wall ,
The well is provided so as to contact both the area surrounded by the underground impermeable wall and the outside of the area,
A contaminated soil purification facility comprising an openable and closable gate that discharges water in the well into soil outside the region surrounded by the underground water-impervious wall . The water supply means is a water intake provided so that the groundwater flows from the upstream side of the groundwater flow in the surrounding ground into the region surrounded by the underground water shielding wall,
The said well is the purification | cleaning equipment of the contaminated soil of Claim 2 provided in the downstream of the said groundwater flow in this area | region. An underground impermeable wall formed so as to surround a downstream side and a side part in the direction of the groundwater flow in an area including soil contaminated with a harmful substance;
A downstream portion of a region surrounded by the underground water-impervious wall, provided at a position in contact with both the region and the outside of the region, a well into which groundwater flows from the region;
Purifying means that is set so that the groundwater flowing into the well is in contact, and includes a treatment agent that detoxifies harmful substances contained in the groundwater or an adsorbent that adsorbs harmful substances,
A pump that pumps up the water in the well and returns it to the area surrounded by the underground impermeable wall;
A contaminated soil purification facility comprising an openable and closable gate that discharges water in the well into soil outside the area surrounded by the underground impermeable wall. The well is formed by arranging steel pipes in the vertical direction in the ground and surrounding the steel pipe sheet pile connecting these side faces,
The steel pipe in a portion in contact with the region surrounded by the underground water-impervious wall has an inlet for introducing ground water into the steel pipe, and an outlet for discharging ground water from the steel pipe into the well,
The purification equipment for contaminated soil according to claim 2 or 4, wherein the purification means for treating harmful substances is disposed in the steel pipe. The well is formed by arranging steel pipes in the vertical direction in the ground and surrounding the steel pipe sheet pile connecting these side faces,
The steel pipe in a portion in contact with the outside of the area surrounded by the underground water-impervious wall is surrounded by a first small hole group that communicates from the inside of the well to the steel pipe, and the underground water-impervious wall from the steel pipe. A second group of small holes leading to the outside of the region,
The gate is provided so as to partition a range in which the first small hole group is provided and a range in which the second small hole group is provided in the steel pipe. Or the purification equipment of the contaminated soil of Claim 4. A plurality of the wells are provided, and an inflow port leading from the region surrounded by the underground water-impervious wall into the well has different vertical positions depending on the individual wells . The purification equipment of the contaminated soil of Claim 2 or Claim 4 . 5. The contaminated soil purification facility according to claim 4, further comprising a contamination concentration monitoring device for detecting a concentration of harmful substances contained in groundwater flowing into the well. An underground impermeable wall is formed to surround the area containing soil contaminated with harmful substances,
A well is provided so that the groundwater in the area surrounded by the underground impermeable wall flows.
The groundwater flowing into the well is brought into contact with a treatment agent that detoxifies the harmful substance or an adsorbent that adsorbs the harmful substance under the ground surface,
Detecting groundwater contamination concentration in the well,
When the detected contamination concentration is equal to or higher than a predetermined value, the groundwater pumped from the well is returned to the area surrounded by the underground impermeable wall ,
Purification of contaminated soil, wherein groundwater pumped from within the well is circulated between the area surrounded by the underground water-impervious wall and the well until the detected contamination concentration becomes a predetermined value or less. Method. The underground impermeable wall is provided with a groundwater intake on the upstream side of the groundwater flow in the surrounding ground,
The contamination according to claim 9, wherein when the contamination concentration detected in the well is equal to or lower than a predetermined value, the groundwater in the well is discharged outside the region surrounded by the underground water-impervious wall. Soil purification method. Form an underground impermeable wall so as to surround the downstream side and the side part in the direction of the groundwater flow in the area containing soil contaminated with harmful substances,
In the downstream part of the region surrounded by the underground water-impervious wall, a well is provided at a position in contact with both the region and outside the region so that groundwater flows from the region,
The groundwater flowing into the well is brought into contact with the treatment agent for detoxifying the harmful substance or the adsorbent for adsorbing the harmful substance under the ground surface,
When the concentration of water contamination in the well is higher than a predetermined value, the water in the well is pumped up and returned to the area surrounded by the underground impermeable wall,
The contaminated soil is characterized in that when the concentration of water in the well is lower than a predetermined value, the water in the well is discharged into the soil outside the region surrounded by the water shielding wall. Purification method.

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