JP4010793B2 - How to repair contaminated soil - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
  The present invention relates to a method for purifying and repairing contaminated soil in which a contaminant has permeated into the soil gap.
[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, methods for extracting and removing contaminants in the soil gap have been proposed. For example, in Japanese Patent Laid-Open Nos. 4-22587, 5-212366, and 5-231086. As disclosed, some pipes with a large number of openings are driven into a contaminated soil and suctioned under reduced pressure to remove the pollutants evaporated in the soil.
[0004]
  In addition, a technique of drilling a well in soil and extracting both the pollutant vaporized in the soil and the contaminant contained in the groundwater from this well is disclosed in JP-A-3-202586 and JP-A-4-309626. Is disclosed.
[0005]
  In any of the techniques disclosed in these publications, a well hole is formed in the soil in the contaminated area, and groundwater or gas in the soil is sucked and extracted through a pipe. And the gas containing the pollutant contained in the ground water or the pollutant vaporized in the soil is processed by the processing equipment provided on the ground.
[0006]
[Problems to be solved by the invention]
  However, the conventional techniques as described above have the following problems.
  Soil contamination with organic compounds is generally distributed in areas with high and low levels of contamination, and when it is attempted to purify the entire contaminated area using a uniform method, the period required for purification is extremely high. It becomes longer and the economy becomes worse. In other words, in order to aspirate the gas in groundwater or soil as in the conventional method, it is necessary to use a well with a small diameter. It takes a long time to bring the concentration below a predetermined value. In addition, excavation of the entire contaminated area and removal of contaminated soil can be performed in a short period of time, but the cost becomes excessive.
  In addition, the method of extracting gas or groundwater in soil and treating it on the ground generally requires a longer period for purification, and this tendency is particularly great in soils that are not good in water permeability and air permeability.
[0007]
  The present invention has been made in view of the circumstances as described above, and its purpose is to repair contaminated soil that can be easily dealt with according to the situation of the distribution of contaminated soil and can be purified at an early stage. Is to provide a method.
[0008]
[Means for Solving the Problems]
  In order to solve the above problem, the invention according to claim 1 divides a region including soil contaminated with a hazardous substance into a high concentration contamination region and a low concentration contamination region in a plane, and In the contaminated area, soil is excavated and removed from the ground surface, backfilled with non-contaminated material, and a plurality of pressurized wells are provided at predetermined intervals near the periphery in the backfilled area with the non-contaminated material. A pumping well is provided in the low-concentration contaminated area around the concentration-contaminated area, a liquid containing a treating agent for pollutants is injected into the pressurized well, the inside of the pressurized well is pressurized, and groundwater is pumped from the pumped well Thus, there is provided a “contaminated soil repairing method” for forming a permeation flow of a liquid containing a treatment agent from the peripheral portion of the high-concentration contaminated region into the surrounding soil in the low-concentration contaminated region.
[0009]
  In this way, highly contaminated soil can be decontaminated in a short time by replacing it with non-contaminated material. Therefore, it becomes possible to repair high concentration contamination at an early stage. Moreover, the permeation | transmission flow of the radial direction of the liquid containing a processing agent can be formed to the outer side from the peripheral part of the area | region which performed replacement | exchange with respect to the low concentration contamination area | region of the peripheral part of the area | region which replaced soil. . Thereby, the processing of the pollutant is performed in the soil gap by the processing agent in the liquid.
  Generally, there is a tendency that the contamination concentration gradually decreases as the distance from the high-concentration contamination region increases, and in the osmotic flow as described above, the liquid containing the treatment agent is in a portion where the contamination concentration is large. The flow rate is concentrated and efficient purification becomes possible.
  In general, the distribution of pollutants in the soil is not uniform, and the contamination spreads along the part where the seepage flow of groundwater tends to occur. On the other hand, when a liquid containing a treatment agent is injected into the soil, the osmotic flow is generated along the contamination path, and the contaminated portion can be efficiently treated.
[0010]
  The high-concentration contamination region and the low-concentration contamination region are determined based on a predetermined contamination concentration based on the contamination concentration distribution obtained in the contamination investigation. The value of the predetermined contamination concentration can be determined as appropriate based on conditions such as soil quality, a purification method, and the like.
[0011]
  The invention according to claim 2 is the “remediation method for contaminated soil” according to claim 1, wherein the non-contaminating material for refilling the high-concentration contaminated area is water permeable in the vicinity of the periphery where the pressurized well is provided. Soil, sand, gravel or a mixture of these is used, and a slurry in which cement or a solidifying material and water are mixed in the soil is used inside.
[0012]
  In this method, the vicinity of the periphery of the high-concentration contaminated region can be backfilled with a material having good water permeability, and a pressure well can be easily provided at the time of backfilling. And the part backfilled with the material with favorable water permeability functions as a large-diameter pressurized well, and the liquid can be efficiently infiltrated into the contaminated soil.
  On the other hand, since the inside of the portion backfilled with the material having good water permeability is backfilled with the slurry, this portion has low water permeability, and it is possible to prevent the contamination of the peripheral portion from penetrating into the backfilled material again. it can.
[0013]
  The invention according to claim 3 is the “method for repairing contaminated soil” according to claim 2, wherein a processing agent for pollutants is mixed with the slurry.
[0014]
  In this method, even if liquid contaminated from the periphery slightly permeates into the slurry, it can be rendered harmless by the treatment agent mixed in the slurry.
[0015]
  The invention according to claim 4 is the “remediation method for contaminated soil” according to claim 1, wherein the pumping well provided in the low-concentration contaminated area excavates a substantially vertical borehole in the ground and has good water permeability. It shall be provided in the area backfilled with a backfill material made of natural soil, sand, gravel or a mixture thereof.
[0016]
  In this method, the water permeability around the pumping well is improved, and this portion has a function corresponding to a large-diameter well, so that the efficiency of collecting the liquid in the soil in the pumping well can be improved.
[0017]
  The invention according to claim 5 is the “contaminated soil remediation method” according to claim 2, wherein the high-concentration contaminated region is backfilled with a slurry in which cement or a solidified material and water are mixed in the soil. The region is formed by excavating the inside of the cylindrical member while penetrating the cylindrical member from the ground surface into the ground, and filling the excavation hole with a slurry of cement or a solidifying agent and water mixed in the soil. After the slurry is solidified and the slurry is solidified, the contaminated soil is removed by repeatedly performing the excavation and backfilling steps adjacent to each other so that a part of the excavation range overlaps.
[0018]
  In this method, the contaminated soil can be surely replaced without leaving the contaminated soil within a predetermined range, and the soil contaminated with a high concentration can be repaired in a short period of time. Further, after the slurry is solidified, the water permeability is low, and it is possible to prevent the contaminants from penetrating again even if the contaminants remain in the peripheral portion.
[0019]
  The invention according to claim 6 is the "method for repairing contaminated soil" according to claim 1, wherein the pressurized well is excavated inside the cylindrical member while penetrating the cylindrical member into the ground. When refilling with soil, sand, gravel or a mixture thereof having good water permeability, the cylindrical member is supported with the upper part protruding above the ground surface, and a contaminant treatment agent is contained in the cylindrical member. The liquid to be contained is stored, and the inside of the pressurizing well is pressurized by the liquid pressure in the cylindrical member.
[0020]
  In this method, the inside of the pressurized well is pressurized by the water head pressure of the liquid stored in the cylindrical member, and the penetration of the liquid into the soil is promoted by this pressure. Moreover, equipment such as a pressure pump is not required, and when purification is performed over a long period of time, the cost is reduced and management is facilitated.
[0021]
  The invention according to claim 7 is the “remediation method for contaminated soil” according to claim 1, wherein the pumping well includes an outer pipe provided with a plurality of small holes that allow inflow of groundwater on a peripheral surface thereof, and Inserted into the outer tube so that it can be pulled out, and includes an inner tube that sucks and pumps the liquid in the outer tube, and a contaminant treatment agent, and is detachably attached to the outside of the water inlet of the inner tube. It shall have a contamination treatment cartridge.
[0022]
  In this method, even if contaminants remain untreated in the liquid that has flowed through the soil and reached the vicinity of the pumping well, it will come into contact with the processing agent contained in the pollution processing cartridge before being pumped from the pumping well. Further processing is performed. Therefore, contamination in the liquid pumped to the ground is reduced. Further, the contamination treatment cartridge can be exchanged by pulling out the inner tube from the outer tube, and can treat the liquid pumped in a good state at all times.
[0023]
  The invention according to claim 8 divides a region including soil contaminated with a harmful substance into a high concentration contamination region and a low concentration contamination region in a plane, and the high concentration contamination region removes soil from the ground surface. Excavation and removal, backfilling with non-contaminated material, a plurality of pumping wells are provided at predetermined intervals near the periphery in the backfilled region with the non-contaminated material, and the low-concentration contaminated region around the high-concentration contaminated region A pressurized well is provided, and a liquid containing a treatment agent for a pollutant is injected into the pressurized well, the inside of the pressurized well is pressurized, and groundwater is pumped from the pumped well, thereby Provided is a “contaminated soil remediation method” that forms a osmotic flow of a liquid containing a treatment agent in a direction toward the high-concentration contaminated region in the soil.
[0024]
  In this method, as in the invention according to claim 1, the contamination in the high-concentration contaminated region can be removed in a short time. And in the low-concentration contaminated area in the surrounding area, an osmotic flow in the direction toward the high-concentration contaminated area is formed in the soil. Can do. Therefore, efficient purification is performed in the soil gap.
[0025]
  The invention according to claim 9 is the “remediation method for contaminated soil” according to claim 8, wherein the non-polluting material for refilling the high-concentration contaminated area has a water permeability in the vicinity of the periphery where the pumping well is provided. Good soil, sand, gravel, or a mixture thereof is used, and a slurry in which cement or a solidifying material and water are mixed with soil is used for the inside.
[0026]
  In this method, the vicinity of the periphery of the high-concentration contaminated region can be backfilled with a material having good water permeability, and a pumping well can be easily provided at the time of backfilling. And the osmotic flow from a peripheral part can be efficiently collected in a part with good water permeability, and quick purification can be performed. That is, the region backfilled with a material having good water permeability has a function corresponding to a large-diameter well, and the osmotic flow quickly flows into the pumping well.
  On the other hand, since the inside of the portion backfilled with the material having good water permeability is backfilled with the slurry, this portion has low water permeability, and it is possible to prevent the contamination of the peripheral portion from penetrating into the backfilled material again. it can.
[0027]
  The invention according to claim 10 is the “repair method of contaminated soil” according to claim 9, wherein a processing agent for pollutants is mixed with the slurry.
[0028]
  In this method, even if liquid contaminated from the periphery slightly permeates into the slurry, it can be rendered harmless by the treatment agent mixed in the slurry.
[0029]
  The invention according to claim 11 is the “remediation method for contaminated soil” according to claim 8, wherein the pressurized well provided in the low-concentration contaminated area excavates a substantially vertical hole in the ground, and has a water permeability. It shall be provided in an area backfilled with backfill material consisting of good soil, sand, gravel or a mixture thereof.
[0030]
  In this method, the water permeability around the pressurized well is improved, and this part has a function corresponding to a large-diameter well, so that the liquid containing the treatment agent can permeate into the soil or in the soil. The efficiency of collecting liquid in the pumping well can be improved.
[0031]
  The invention according to claim 12 is the “repair method of contaminated soil” according to claim 9, wherein the high-concentration contaminated region is backfilled with a slurry in which cement or a solidified material and water are mixed in the soil. The region is formed by excavating the inside of the cylindrical member while penetrating the cylindrical member from the ground surface into the ground, and filling the excavation hole with a slurry of cement or a solidifying agent and water mixed in the soil. After the slurry is solidified and the slurry is solidified, the contaminated soil is removed by repeatedly performing the excavation and backfilling steps adjacent to each other so that a part of the excavation range overlaps.
[0032]
  In this method, the contaminated soil can be surely replaced without leaving the contaminated soil within a predetermined range, and the soil contaminated with a high concentration can be repaired in a short period of time. Further, after the slurry is solidified, the water permeability is low, and it is possible to prevent the contaminants from penetrating again even if the contaminants remain in the peripheral portion.
[0033]
  The invention according to claim 13 is the "repair method of contaminated soil" according to claim 8, wherein the pressurized well is excavated inside the cylindrical member while penetrating the cylindrical member into the ground. When refilling with soil, sand, gravel or a mixture thereof having good water permeability, the cylindrical member is supported with the upper part protruding above the ground surface, and a contaminant treatment agent is contained in the cylindrical member. The liquid to be contained is stored, and the inside of the pressurizing well is pressurized by the liquid pressure in the cylindrical member.
[0034]
  In this method, the inside of the pressurized well is pressurized by the water head pressure of the liquid stored in the cylindrical member, and the penetration of the liquid into the soil is promoted by this pressure. Moreover, equipment such as a pressure pump is not required, and when purification is performed over a long period of time, the cost is reduced and management is facilitated.
[0035]
  The invention according to claim 14 is the “remediation method for contaminated soil” according to claim 8, wherein the pumping well has an outer pipe provided with a plurality of small holes that allow inflow of groundwater on a peripheral surface thereof, and Inserted into the outer tube so that it can be pulled out, and includes an inner tube that sucks and pumps the liquid in the outer tube, and a contaminant treatment agent, and is detachably attached to the outside of the water inlet of the inner tube. It shall have a contamination treatment cartridge.
[0036]
  In this method, even if contaminants remain untreated in the liquid that has flowed through the soil and reached the vicinity of the pumping well, it will come into contact with the processing agent contained in the pollution processing cartridge before being pumped from the pumping well. Further processing is performed. Therefore, contamination in the liquid pumped to the ground is reduced. Further, the contamination treatment cartridge can be exchanged by pulling out the inner tube from the outer tube, and can treat the liquid pumped in a good state at all times.
[0037]
  The invention according to claim 15 divides a region containing soil contaminated with a harmful substance into a high concentration contaminated region and a low concentration contaminated region in a plane, and the high concentration contaminated region removes soil from the ground surface. Excavated and removed and backfilled with non-contaminated material, and the low-concentration contaminated area is provided with a pressurized well and a pumped well at predetermined intervals, and the pressurized well is filled with a liquid containing a contaminant treatment agent. Injecting and pressurizing the inside of the pressurized well, and by pumping up groundwater from the pumped well, the treatment agent in the direction from the pressurized well to the pumped well is introduced into the soil in the low concentration contaminated area. Provided is a “remediation method for contaminated soil” that forms an osmotic flow of liquid containing the same
[0038]
  In this method, soil in a high concentration contaminated area can be removed in a short time and replaced with non-contaminated material. Therefore, it becomes possible to repair high concentration contamination at an early stage. Moreover, in the low concentration contamination area | region of the peripheral part, the osmosis | permeation flow of the liquid containing a processing agent in soil is formed toward a pumping well from a pressurized well, and a process is performed in a soil gap. Therefore, the process proceeds early and the purification is completed in a short period.
[0039]
  The invention according to claim 16 is the “method for repairing contaminated soil” according to claim 15, wherein at least one of the pressurized well and the pumped well is excavated in a substantially vertical hole in the ground. , And formed in a region backfilled with a backfill material made of soil, sand, gravel or a mixture thereof having good water permeability.
[0040]
  In this method, the permeability of the periphery of the pressurized well or the pumping well is improved, and this region comes into contact with the contaminated soil over a wide area. Therefore, inflow of the treatment liquid into the contaminated soil or outflow from the contaminated soil is promoted, and the liquid containing the treatment agent smoothly penetrates in a wide range.
[0041]
  The invention according to claim 17 is the “method for repairing contaminated soil” according to claim 16, wherein the step of excavating a pit in the ground is performed by inserting the cylindrical member into the ground from the ground surface. A step of excavating the inside of the cylindrical member, and the step of refilling the excavated pothole is performed by inserting the backfilling material while drawing out the cylindrical member and compacting.
[0042]
  In this method, it is possible to prevent the wall surface of the pit hole from collapsing by the cylindrical member, and it is possible to excavate a predetermined range to a predetermined depth safely and reliably. And the pipe material used as a pressure well or a pumping well can be easily built when the excavated range is backfilled with the backfill material with favorable water permeability.
[0043]
  The invention according to claim 18 is the “method for repairing contaminated soil” according to claim 15, wherein the pressurized well is excavated inside the cylindrical member while penetrating the cylindrical member into the ground. When refilling with soil, sand, gravel or a mixture thereof having good water permeability, the cylindrical member is supported with the upper part protruding above the ground surface, and a contaminant treatment agent is contained in the cylindrical member. The liquid to be contained is stored, and the inside of the pressurizing well is pressurized by the liquid pressure in the cylindrical member.
[0044]
  In this method, the inside of the pressurized well is pressurized by the water head pressure of the liquid stored in the cylindrical member, and the penetration of the liquid into the soil is promoted by this pressure. Moreover, equipment such as a pressure pump is not required, and when purification is performed over a long period of time, the cost is reduced and management is facilitated.
[0045]
  The invention according to claim 19 is the “remediation method for contaminated soil” according to claim 15, wherein the pumping well includes an outer pipe provided with a plurality of small holes that allow inflow of groundwater on a peripheral surface thereof, and Inserted into the outer tube so that it can be pulled out, and includes an inner tube that sucks and pumps the liquid in the outer tube, and a contaminant treatment agent, and is detachably attached to the outside of the water inlet of the inner tube. It shall have a contamination treatment cartridge.
[0046]
  In this method, even if contaminants remain untreated in the liquid that has flowed through the soil and reached the vicinity of the pumping well, it will come into contact with the processing agent contained in the pollution processing cartridge before being pumped from the pumping well. Further processing is performed. Therefore, contamination in the liquid pumped to the ground is reduced. Further, the contamination treatment cartridge can be exchanged by pulling out the inner tube from the outer tube, and can treat the liquid pumped in a good state at all times.
[0047]
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 is a diagram showing, for example, soil contamination by volatile organic compounds as a line connecting equal concentration positions. This contamination distribution has the highest concentration in almost the central portion of the contaminated area, and the concentration of contamination decreases as the distance from the central portion increases. In the present embodiment, an area where soil is contaminated with such a distribution has a predetermined contamination concentration as a reference value, a high concentration contamination region (region indicated by a broken line A in FIG. 1) and a low concentration contamination region (a broken line in FIG. 1). (Region indicated by B), and a purification process is performed on each of them.
  The method for repairing this contaminated soil isClaim 1, Claim 2, Claim 3, Claim 4 or Claim 5It is one Embodiment of the invention which concerns.
[0048]
  The purification treatment of the high-concentration contaminated area employs a method of excavating and removing soil and backfilling with non-contaminated material. The excavation is to form a hole with a substantially circular cross section vertically, and the excavation proceeds while preventing the wall of the hole from collapsing using a cylindrical member made of steel, that is, a casing.
[0049]
  In this excavation method, as shown in FIG. 3A, the casing 1 having the excavation blade 1 a attached to the tip is press-fitted into the ground 4 while being rotationally driven by the press-fitting device 2. Then, as shown in FIG. 3B, the drilling bucket 3 is suspended from the upper opening of the casing, and the inside of the casing is excavated to a predetermined depth. As the excavator, various devices capable of excavating the casing such as a hydro grab and a hammer grab in addition to the drilling bucket can be used. Further, the excavation depth is set to be greater than the depth at which soil contamination occurs, and when there is an impermeable layer, it is generally set to a depth that reaches the impermeable layer.
[0050]
  When the pollutant generates a strong odor, an opening / closing door (not shown) can be provided on the upper portion of the casing 1 to prevent the odor from spreading. Moreover, when there is a possibility that the pollutant may explode or ignite, safety can be ensured by preparing the nitrogen tank 5 and excavating the casing 1 while supplying nitrogen.
[0051]
  After excavation in the casing 1 is completed, the hole is backfilled with non-contaminating material to complete the soil replacement. The material to be backfilled will be described later.
[0052]
  In the excavation using the casing 1, as shown in a plan view in FIG. 2, the entire high-concentration contaminated area A is excavated and refilled without leaving contaminated soil, and one cylindrical borehole is excavated. After completion of the backfilling, the adjacent portion is excavated so that a part of the excavation range overlaps.
[0053]
  The pothole drilled in the high-concentration contaminated area is refilled as follows.
  As shown in FIG. 4, the central portion of the high-concentration contaminated area (the range indicated by the symbol C in FIG. 4) is a mixture of solidified material such as cement and water with the excavated soil, and further contains contaminants as necessary. Backfill with a stirred slurry mixed with treating agent. And the surrounding part (range shown with the code | symbol D in FIG. 4) is refilled with the sandy soil 11 with favorable water permeability. When this portion is backfilled, a plurality of pressurized wells 6 are provided at the peripheral portion of the high-concentration contaminated region A by building a steel pipe to be a pressurized well and then backfilling the periphery thereof. At this time, the pressurized wells may be provided in all the pits excavated using the casing and backfilled with sandy soil, or may be provided at predetermined intervals.
  Moreover, in order to maintain the effect of pressurizing the inside of the pressurized well, the upper layer portion 20 is backfilled with viscous soil or slurry having low air permeability.
[0054]
  On the other hand, a plurality of pits 8 are excavated in the low-concentration contaminated area B in the peripheral portion at positions distant from the high-concentration contaminated area A. And the steel pipe for the pumping well 7 is built, and the circumference | surroundings are refilled with the sandy soil 9 with favorable water permeability. The excavation depth of the hole is a depth that reaches the impermeable layer 10 below the layer contaminated with soil.
[0055]
  As shown in FIG. 5, in the pressurized well 6 provided at the peripheral portion of the high-concentration contaminated area A, the steel pipe 12 built in the sandy soil 11 backfilled has a large number of small holes in the lower part. A processing liquid containing a processing agent is injected from the tank 13 into the steel pipe 12. Moreover, compressed air is sent from the blower 14 and the inside of the steel pipe is pressurized. Thereby, the penetration of the treatment liquid from the portion backfilled with the sandy soil 11 to the soil 15 in the low concentration contaminated region is promoted.
[0056]
  Moreover, the pumping well 7 provided in the low concentration pollution area | region B is provided with the outer pipe | tube 16 which has many small holes, and the inner pipe | tube 17 for pumping up the ground water and process liquid which were collected in this outer pipe | tube. Yes, groundwater and processing liquid are pumped up by the pump 18 through the inner pipe 17, and ground processing is performed in the processing tank 19 as necessary.
[0057]
  Thus, by injecting the treatment liquid into the pressurized well 6 and pumping up the pumping well 7, an osmotic flow is formed in the soil as shown by the arrow E in FIGS. As a result, the treatment liquid is dispersed in the soil of the low-concentration contaminated area B, and the detoxification treatment of the pollutant is performed effectively and promptly.
  In addition, the code | symbol C in FIG. 5 shows the part backfilled with the slurry of the high concentration pollution area | region.
[0058]
  next,Claim 8, Claim 9, Claim 10, Claim 11 or Claim 12An “embodiment for repairing contaminated soil” according to an embodiment of the present invention will be described with reference to FIGS. 6 and 7.
  This method repairs the soil in the area where the contamination is distributed as shown in FIG. 1, and the purification of the high-concentration contaminated area A is performed in the same manner as in the embodiment shown in FIGS. However, the pumping well 27 is provided in the portion D where the soil in the high concentration contaminated area A is replaced with sandy soil, and the pressurized well 26 is provided in the surrounding low concentration contaminated area B.
[0059]
  Similarly to the embodiment described above, the pressurized wells 26 are dispersed at positions distant from the high-concentration contaminated area A, and the pits 28 are excavated and provided in a portion where the sandy soil 29 is backfilled. However, the upper layer 30 of the portion backfilled with sandy soil is filled with viscous soil having low air permeability.
[0060]
  As shown in FIG. 7, the pressurized well 26 and the pumped well 27 have the same configuration as that adopted in the previous embodiment, and the pressurized well 26 pressurizes the treatment liquid into the soil. The pumping well 27 collects and pumps the processing liquid and groundwater. Thereby, as shown by the arrow F in FIG.6 and FIG.7, the osmosis | permeation flow in soil is formed in the direction which goes to the high concentration contamination area A of the center part from the low concentration contamination area | region B, and in a low concentration contamination area | region. Pollutants in the soil are detoxified.
[0061]
  FIG. 8 and FIG.Claim 15, claim 16 or claim 17It is the schematic plan view and elevation sectional view which show "the repair method of contaminated soil" which is one Embodiment of the invention which concerns.
  This embodiment also purifies soil contaminated with a distribution as shown in FIG. 1, and the high-concentration contaminated area A excavates a pit using a casing and replaces contaminated soil with non-contaminated material. . However, in this embodiment, the entire high concentration contaminated area A is replaced with the slurry 41.
[0062]
  On the other hand, in the low-concentration contaminated region B, the pits 38 are excavated at predetermined intervals using a casing, and the sandy soil 39 having good water permeability is backfilled, and a pumping well 37 is provided in this portion. The pumping well 37 has the same configuration as that used in the embodiment shown in FIGS.
[0063]
  A pressurized well 36 is provided between the pumping wells 37 provided at predetermined intervals. The pressurized well 36 is formed by driving a steel pipe 42 having a large number of small holes in the lower part into the soil, and a treatment liquid containing a treatment agent is injected into the steel pipe from the tank 43. Moreover, compressed air is sent from the blower 44, and the inside of the steel pipe is pressurized.
[0064]
  In such a “contaminated soil repair method”, as shown by arrows G in FIGS. 8 and 9, an osmotic flow of the treatment liquid is formed in the soil of the low-concentration contaminated region B, and the pollutants in the soil gap are formed. Is detoxified.
[0065]
  FIG. 10 and FIG.Claim 15, Claim 16 or Claim 17It is the schematic plan view and standing sectional view which show other embodiment of invention.
  Also in this method, the entire high-concentration contaminated area A is replaced with the slurry 61 to complete the purification in a short period of time, and the low-concentration contaminated area B is provided with a pressurized well 56 and a pumping well 57 at intervals. However, a pressurized well 56 is provided in a portion where the well 58 is excavated and backfilled with sandy soil 59 having good permeability, and the pumping well 57 is formed by driving a steel pipe into the soil. The driven steel pipe is used as an outer pipe 66, an inner pipe 67 is inserted into the outer pipe 66, and water is pumped through the inner pipe by a pumping pump 68.
[0066]
  In this method, since the pressurized well 56 is provided in the portion replaced with the sandy soil 59, the treatment liquid can easily penetrate into the soil, and the osmotic flow in the direction indicated by the arrow H in FIGS. Is formed.
  In addition, the code | symbol 60 in FIG. 11 shows the viscous soil with which the upper layer part replaced with the sandy soil 59 was filled. This cohesive soil has low air permeability and is for maintaining the pressure in the pressurized well.
[0067]
  FIG.Claim 18It is sectional drawing which shows one Embodiment of the invention which concerns.
  In this method, similar to the embodiment shown in FIGS. 9 and 11, the contaminated soil in the high-concentration contaminated area A is replaced with slurry, and the pressurized well 76 and the pumping well 77 are spaced apart in the low-concentrated contaminated area B. However, the structure of the pressurized well 76 is different from that of the previous embodiment. The pressurized well 76 used in this embodiment has a casing 82 whose upper part is on the ground surface when excavating a hole in the soil using a cylindrical casing made of steel and then backfilling with sandy soil 79. Support in the protruding state and leave without removing. And as shown in FIG. 12, the part which replaced the sandy soil 79 with the water head pressure by storing the process liquid 83 in this casing 82 is pressurized. As a result, the penetration of the treatment agent into the soil from the portion replaced with the sandy soil 79 is promoted, and an osmotic flow is generated in the soil as indicated by an arrow I in FIG. Thereby, the pollutant in soil is detoxified.
  Such a pressure well can be used in place of the pressure well shown in FIG.
  Note that a stand pipe for supporting the casing may be used instead of the casing.
[0068]
  FIG. 13: is a schematic sectional drawing which shows the other example of the pumping well which can be applied in embodiment described above.
  The pumping well 91 includes an outer tube 92 having a large number of small holes in the lower portion, an inner tube 93 inserted inside thereof, and a contamination treatment cartridge 94 detachably attached to the outer side of the water inlet 93a of the inner tube. And. The outer tube 92 and the inner tube 93 are the same as those used in the embodiment described above.
[0069]
  The contamination treatment cartridge 94 is a cloth-like member that permeates water or a member that aggregates fibers, and contains a contaminant treatment agent such as potassium permanganate. When such a pumping well 91 is used and the water in the well is sucked by the pumping pump through the inner pipe 93, the groundwater or the processing liquid flowing into the outer pipe 92 from the soil through the small holes is contaminated. It passes through the cartridge 94 and is taken into the inner tube 93. Accordingly, the groundwater or the processing liquid to be pumped comes into contact with the processing agent in the contamination processing cartridge 94. For this reason, even if the pollutants in the soil may flow into the wells without being treated, they are detoxified in contact with the treatment agent.
[0070]
【The invention's effect】
  As described above, in the method for repairing contaminated soil according to the present invention, it is possible to efficiently and safely replace contaminated soil with non-contaminating material for an area where the soil is contaminated with harmful substances at high concentration, The processing can be completed reliably between the two.
  Moreover, about the area | region where the soil is contaminated by low concentration, the pollutant in a soil crevice can be efficiently processed at low expense by making the liquid containing a processing agent penetrate | invade in soil efficiently. Then, the region contaminated with the toxic substance is divided into a high-concentration contamination region and a low-concentration contamination region, and different treatments are appropriately performed on these regions, thereby enabling economical detoxification processing in a short period of time.
[Brief description of the drawings]
FIG. 1 is a plan view showing the distribution of soil contamination.
2 is a schematic plan view showing a processing method for a high-concentration contaminated region in the contamination distribution shown in FIG. 1. FIG.
FIG. 3 is a schematic diagram illustrating a method for excavating a pit in a contaminated area.
FIG. 4 is a plan view showing a range in which soil is replaced in order to treat the contaminated area shown in FIG. 1, and the arrangement of pressurized wells and pumping wells.
5 is an elevational sectional view showing a state of treatment in the contaminated area shown in FIG. 4;
6 is a plan view showing another example of a range in which soil is replaced in order to treat the contaminated area shown in FIG. 1, and an arrangement of pressurized wells and pumping wells. FIG.
7 is an elevational sectional view showing a state of treatment in the contaminated area shown in FIG. 6. FIG.
FIG. 8 is a plan view showing another example of the range in which soil is replaced to treat the contaminated area shown in FIG. 1 and the arrangement of pressurized wells and pumping wells.
9 is an elevational sectional view showing a state of treatment in the contaminated area shown in FIG. 8. FIG.
10 is a plan view showing another example of a range in which soil is replaced in order to treat the contaminated area shown in FIG. 1, and an arrangement of pressurized wells and pumping wells. FIG.
11 is an elevational sectional view showing a state of treatment in the contaminated area shown in FIG.
FIG.Claim 18It is a schematic sectional drawing which shows the "repair method of contaminated soil" which is one Embodiment of the invention which concerns.
FIG. 13Other pumping wells that can be used in place of the pumping wells shown in FIG. 5, FIG. 7, FIG. 9, FIG. 11 or FIG.FIG.
[Explanation of symbols]
    1 casing
    2 Press-fitting device
    3 Drilling bucket
    4 ground
    5 Nitrogen tank
    6, 26, 36, 56, 76 Pressurized well
    7, 27, 37, 57, 77 Pumping well
    8, 28, 38, 58
    9, 29, 39, 59, 79 Sandy soil
  11 Sandy soil
  12, 42 Steel pipe
  13, 43 tanks
  14, 44 Blower
  15 soil
  16, 66 Outer pipe
  17, 67 Inner pipe
  18, 48, 68 Pumping pump
  19, 49 Treatment tank
  41, 61 Slurry
  82 casing
  83 Treatment liquid
  91 Pumping well
  92 Outer pipe
  93 Inner pipe
  94 Contamination purification cartridge

Claims (19)

The area containing soil contaminated with harmful substances is divided into a high-contaminated area and a low-contaminated area in a plane.
The highly contaminated area is excavated and removed from the ground surface and backfilled with non-contaminated material,
Providing a plurality of pressurized wells at predetermined intervals near the periphery in the region backfilled with the non-contaminating material,
A pumping well is provided in the low concentration contaminated area around the high concentration contaminated area,
Injecting a liquid containing a pollutant treatment agent into the pressurized well, pressurizing the pressurized well,
Remediation of contaminated soil, characterized by forming an osmotic flow of a liquid containing a treatment agent from the periphery of the high-concentration contaminated area into the surrounding low-concentration contaminated soil by pumping groundwater from the pumping well Method. The non-contaminating material for refilling the high-concentration contaminated area is made of soil, sand, gravel or a mixture thereof having good water permeability in the vicinity of the peripheral edge where the pressurized well is provided. The method for repairing contaminated soil according to claim 1, wherein a slurry obtained by mixing a solidifying material and water is used.     The method for repairing contaminated soil according to claim 2, wherein a treating agent for pollutants is mixed in the slurry. The pumping well provided in the low-concentration contaminated area should be provided in an area where a substantially vertical borehole is excavated in the ground and backfilled with a backfill material made of soil, sand, gravel or a mixture thereof having good water permeability. The method for repairing contaminated soil according to claim 1. The high-concentration contaminated area, the area to be backfilled with a slurry of cement or solidified material and water mixed in the soil,
Excavating the inside of the cylindrical member while penetrating the cylindrical member from the ground surface into the ground,
Pulling out the cylindrical member while refilling the excavation hole with a slurry of cement or a solidifying agent and water mixed in the soil,
3. The repair of contaminated soil according to claim 2, wherein after the slurry is solidified, the contaminated soil is removed by repeatedly performing the excavation and backfilling steps adjacent to each other so that a part of the excavation range overlaps. Method. The pressure well is formed by excavating the inside of the cylindrical member while penetrating the cylindrical member into the ground, and then backfilling with soil, sand, gravel or a mixture thereof having good water permeability. Is supported with the upper part protruding above the ground surface,
The liquid containing a treating agent for contaminants is stored in the cylindrical member, and the inside of the pressurizing well is pressurized by the liquid pressure in the cylindrical member. How to repair contaminated soil. The pumping well is
An outer pipe provided with a large number of small holes allowing the inflow of groundwater on the peripheral surface;
An inner tube that is inserted into the outer tube so as to be able to be pulled out, and sucks and pumps the liquid in the outer tube;
2. The method for repairing contaminated soil according to claim 1, further comprising a contamination treatment cartridge that includes a treatment agent for contaminants and is detachably attached to the outside of the water inlet of the inner pipe. The area containing soil contaminated with harmful substances is divided into a high-contaminated area and a low-contaminated area in a plane.
The highly contaminated area is excavated and removed from the ground surface and backfilled with non-contaminated material,
A plurality of pumping wells are provided at predetermined intervals near the periphery in the region backfilled with the non-contaminating material,
A pressure well is provided in the low-concentration contaminated region around the high-concentration contaminated region,
Injecting a liquid containing a pollutant treatment agent into the pressurized well, pressurizing the pressurized well,
Remediation of contaminated soil by pumping groundwater from the pumping well to form a osmotic flow of a liquid containing a treatment agent in a direction toward the high concentration contaminated region in the soil of the low concentration contaminated region Method. The non-polluting material for refilling the high-concentration contaminated area is made of soil, sand, gravel or a mixture thereof having good water permeability in the vicinity of the periphery where the pumping well is provided, and the inside is cemented or solidified in the soil. The method for repairing contaminated soil according to claim 8, wherein a slurry obtained by mixing wood and water is used.     The method for repairing contaminated soil according to claim 9, wherein the slurry is mixed with a treating agent for contaminants. The pressurized well provided in the low-concentration contaminated area is provided in an area where a substantially vertical borehole is excavated in the ground and backfilled with a backfill material made of soil, sand, gravel or a mixture thereof having good water permeability. The method for repairing contaminated soil according to claim 8. The high-concentration contaminated area, the area to be backfilled with a slurry of cement or solidified material and water mixed in the soil,
Excavating the inside of the cylindrical member while penetrating the cylindrical member from the ground surface into the ground,
Pulling out the cylindrical member while refilling the excavation hole with a slurry of cement or a solidifying agent and water mixed in the soil,
The contaminated soil is repaired according to claim 9, wherein after the slurry is solidified, the contaminated soil is removed by repeatedly performing the excavation and backfilling steps adjacent to each other so that a part of the excavation range overlaps. Method. The pressure well is formed by excavating the inside of the cylindrical member while penetrating the cylindrical member into the ground, and then backfilling with soil, sand, gravel or a mixture thereof having good water permeability. Is supported with the upper part protruding above the ground surface,
9. The liquid containing a processing agent for pollutants is stored in the cylindrical member, and the inside of the pressurizing well is pressurized by the liquid pressure in the cylindrical member. How to repair contaminated soil. The pumping well is
An outer pipe provided with a large number of small holes allowing the inflow of groundwater on the peripheral surface;
An inner tube that is inserted into the outer tube so as to be able to be pulled out, and sucks and pumps the liquid in the outer tube;
The method for repairing contaminated soil according to claim 8, further comprising a contamination treatment cartridge that includes a treatment agent for contaminants and is detachably attached to the outside of the water inlet of the inner pipe. The area containing soil contaminated with harmful substances is divided into a high-contaminated area and a low-contaminated area in a plane.
The highly contaminated area is excavated and removed from the ground surface and backfilled with non-contaminated material,
In the low-concentration contaminated area, a pressurized well and a pumping well are provided at a predetermined interval,
Injecting a liquid containing a contaminant treatment agent into the pressurized well, pressurizing the pressurized well,
Pumping groundwater from the pumping well to form an osmotic flow of the liquid containing the treatment agent in the direction from the pressurized well to the pumping well in the soil in the low-concentration contaminated region. How to repair contaminated soil.     At least one of the pressurized well and the pumped well is excavated in a substantially vertical hole in the ground, and backfilled with a backfill material made of soil, sand, gravel or a mixture thereof having good water permeability. The method for repairing contaminated soil according to claim 15, wherein the method is formed in a closed area. The step of excavating a hole in the ground includes a step of excavating the inside of the cylindrical member while penetrating the cylindrical member from the ground surface into the ground.
The method for repairing contaminated soil according to claim 16, wherein the step of refilling the excavated pothole is one in which the backfill material is introduced and compacted while the cylindrical member is pulled out. The pressure well is formed by excavating the inside of the cylindrical member while penetrating the cylindrical member into the ground, and then backfilling with soil, sand, gravel or a mixture thereof having good water permeability. Is supported with the upper part protruding above the ground surface,
The liquid containing a treating agent for contaminants is stored in the cylindrical member, and the inside of the pressurized well is pressurized by the liquid pressure in the cylindrical member. How to repair contaminated soil. The pumping well is
An outer pipe provided with a large number of small holes allowing the inflow of groundwater on the peripheral surface;
An inner tube that is inserted into the outer tube so as to be able to be pulled out, and sucks and pumps the liquid in the outer tube;
The method for repairing contaminated soil according to claim 15, further comprising a contamination treatment cartridge that includes a treatment agent for contaminants and is detachably attached to the outside of the water inlet of the inner pipe.

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