JP5545971B2 - Soil purification method - Google Patents

Description

  The present invention relates to a soil purification method for purifying contaminated soil in situ.

  As a technology to purify pollutants that have penetrated underground (for example, VOCs (volatile organic compounds) such as tetrachloroethylene, trichloroethylene, benzene, dichloromethane, etc.), a pumping well or injection well is installed vertically in the ground A method of purifying ground-contaminated areas using this flow by creating a flow of groundwater in an underground aquifer by injecting a purification agent (purifying agent) from (For example, refer to Patent Document 1).

JP 2005-279548 A

  By the way, although this method can be used for an aquifer in which groundwater exists, it has been difficult to apply as a countermeasure for contamination of an unsaturated layer above the groundwater surface.

  In view of the above circumstances, an object of the present invention is to provide a soil purification method that can be effective as a countermeasure against contamination of an underground unsaturated layer.

In order to solve the above-mentioned problem, the soil purification method of the invention of claim 1 is characterized in that the soil pollutant is introduced into the ground in the process of soil purification for detoxifying the soil pollutant penetrating into the ground from the ground surface. Set up a planar area horizontally expanded on the ground surface so as to include the starting point of the path on the ground surface that has penetrated, and then store innumerable voids in this planar area and store the purifier in each void. A purifying agent reservoir that can be stored, and then storing the purifying agent in a state in which the purifying agent is expanded in a planar shape in this purifying agent reservoir, and then, the purifying agent stored in the purifying agent reservoir, A soil purification method for detoxifying the soil pollutants by allowing the soil pollutants to penetrate into the ground by gravity along a path through which the soil pollutants penetrated into the ground. Forming a shallow excavated recess, and then inside said recess The crushed stone layer Construction as agent reservoir, then, is characterized in that to spread in a state of being deployed in a planar form on crushed stone layer the cleaning agent through the dispersion tube placed in the crushed stone layer.

  According to the first aspect of the present invention, the purifying agent is stored in a state where the purifying agent is spread in a flat state in the purifying agent reservoir formed on the ground surface, thereby automatically selecting a path that easily penetrates into the ground. However, the purifier penetrates into the ground by its own weight along the route. In other words, it is difficult to actually identify the path through which contaminants penetrated into the ground, but a large area of the plane area that includes this path is set on the ground surface, and the purifier reservoir is placed in this plane area. By creating and storing the purifying agent, the purifying agent can reach the contaminated area by gravity while automatically tracing the path through which the pollutant has permeated. Therefore, there is no need to adopt a method of injecting the purification agent into the ground while pressurizing with a pump etc. with an injection well, etc., and without using excess energy, soil contamination with an excess and shortage of purification agent Substances can be made harmless efficiently. In this way, the unsaturated layer above the groundwater surface is highly effective as a countermeasure against contamination, and further, it can be detoxified without being accompanied by the movement of pollutants such as using a pumping well. There is no worry of secondary contamination.

In particular, according to the first aspect of the present invention, a crushed stone layer as a cleaning agent reservoir is formed in a recess excavated shallowly on the ground surface, and the clarified agent is distributed to the crushed stone layer through a dispersion pipe. In this state, the cleaning agent can be stored, and the horizontal movement of the cleaning agent in the crushed stone layer can be freely performed. Therefore, no matter what location the purifier penetrates into the ground, the purifier stored in the crushed stone layer can be smoothly guided to the infiltrate.

It is sectional drawing of the target ground which enforces the purification method of embodiment of this invention. It is sectional drawing which shows the state which formed the shallow recess in the ground surface as a 1st process with respect to the object ground. It is sectional drawing which shows the state which spread | laid the crushed stone in the recess and has arrange | positioned the dispersion pipe | tube. It is a top view which shows schematic structure of the said dispersion pipe. It is sectional drawing which shows the state which spreads crushed stone on the said dispersion pipe further, forms a crushed stone layer (purifier storage layer), and stores the cleaning agent in the crushed stone layer through a dispersion pipe. It is sectional drawing which shows the state which the purification | cleaning agent stored by the crushed stone layer osmose | permeated into the ground, and purified the pollutant.

  Embodiments of the present invention will be described below with reference to the drawings.

  FIG. 1 is a cross-sectional view of a target ground for carrying out the purification method of the embodiment, FIG. 2 is a cross-sectional view showing a state where a shallow recess is formed on the ground surface as a first step, and FIG. FIG. 4 is a plan view showing a schematic configuration of the dispersion pipe, FIG. 5 is a plan view showing a schematic configuration of the dispersion pipe, and FIG. 5 is a crushed stone layer (cleaning agent). 6 is a cross-sectional view showing a state where the purification agent is stored in the crushed stone layer through the dispersion pipe, and FIG. 6 shows that the purification agent stored in the crushed stone layer penetrates into the ground and purifies the pollutants. It is sectional drawing which shows the state which carried out.

  In this soil purification method, as shown in FIG. 1, the soil pollutant 5 penetrating from the tank 7 on the ground surface 1 to the unsaturated layer 2 (layer above the aquifer layer 3) in the ground is removed. First, after removing the tank 7 as a pollution source, as shown in FIG. 2, the ground surface 1 includes a starting point of a path on the ground surface where the soil pollutant 5 penetrates into the ground. A flat area developed in the horizontal direction is set, and a recess 8 excavated shallowly (with a depth of about 50 cm) is formed on the ground surface 1 as the flat area. In addition, the code | symbol 5 has also shown the path | route (leakage permeation | transmission path | route of a harmful substance) which the pollutant permeate | transmitted.

  Next, in this recess 8, a purifier storage layer is formed in which innumerable voids exist and the purifier can be stored in each void. Here, as shown in FIG. 5, a crushed stone layer (a layer having a thickness of about 50 cm) 15 is formed as a purifier storage layer. Here, when creating the crushed stone layer 15, first, as shown in FIG. 3, after laying the lower crushed stone 11 on the inner bottom surface of the recess 8, dispersion for spreading the purifier while spreading it in a planar shape A tube 13 is provided.

  As shown in FIG. 4, the dispersion pipe 13 connects a large number of branch pipes 13 a and 13 b to the main pipe 13, and countless discharge holes (not shown) on the pipe walls of the main pipe 13 and the branch pipes 13 a and 13 b. The insertion port 14 is opened on the ground.

  When the dispersion pipe 13 is laid, an upper layer of crushed stone 12 is further laid thereon as shown in FIG. 5 to form a crushed stone layer 15 in which the dispersion pipe 13 is embedded in the layer. Next, by introducing the cleaning agent A from the inlet 14 of the dispersion pipe 13, the purification agent A is spread through the dispersion pipe 13 in a state of being spread on the crushed stone layer 15. The purifying agent A in this case is appropriately selected and determined according to the pollutant 5 to be purified. At that time, it is prepared so as to have a density and viscosity equal to or higher than those of the contaminants.

  As described above, when the purifying agent A is stored in a state where the crushed stone layer 15 is flatly developed, the stored purifying agent A is along the path through which the soil pollutant 5 penetrates into the ground. It penetrates into the ground by gravity and thereby reaches the soil pollutant 5, thereby detoxifying the contaminated area. In other words, the purifier A diffuses and penetrates into the ground while being expanded through the crushed stone layer 15 and selectively permeates along the path through which the soil pollutant 5 penetrates. By going, ensure that the contaminated area is harmless.

  As described above, according to the purification method of the present embodiment, the purification agent A is stored in a state in which the purification agent A is developed in a flat shape in the crushed stone layer (purification agent storage layer) 15 formed on the ground surface 1. While automatically selecting a route that easily penetrates into the inside, the purifier A penetrates into the ground by its own weight along the route. That is, the path through which the pollutant 5 penetrates into the ground is actually difficult to identify, but a large area of the plane area (recess 8) that includes this path is set in the ground surface 1, and this plane By creating the crushed stone layer 15 in the region and storing the purifying agent A, the purifying agent A can reach the contaminated region by gravity while automatically tracing the path through which the pollutant 5 has permeated.

  Therefore, it is not necessary to adopt a method of injecting the cleaning agent into the ground while applying pressure with a pump, etc., and without using excessive energy, the amount of the cleaning agent can be efficiently removed with a sufficient amount of the cleaning agent. It can be detoxified. In addition, since there is no need to use a pumping well or an injection well, it is highly effective as a countermeasure against contamination of unsaturated layers above the groundwater surface, and further, it can be made harmless without decomposing the contaminants. Because it can, there is no worry of secondary contamination.

  In addition, a crushed stone layer 15 as a purification agent reservoir is formed in a recess 8 excavated shallowly on the ground surface 1, and the clarification agent A is distributed to the crushed stone layer 15 through the dispersion pipe 13, so that it is spread in a flat state. The purification agent A can be stored, and the horizontal movement of the purification agent in the crushed stone layer 15 can be freely performed. As a result, even if the purification agent A penetrates into the ground from any location, the purification agent A stored in the crushed stone layer 15 can be smoothly guided to the penetration location.

  Therefore, even for contamination directly under an existing building such as a factory building, if only the tank 7 (see FIG. 1) that is the source of contamination is removed and a crushed stone layer 15 is installed, the building (not shown) remains. In the purification period, the above-ground part can be effectively used for a parking lot or the like.

  In addition, since the unsaturated layer 2 becomes a purification target, it is important to adjust the viscosity so that the purification agent A can surely penetrate into the contaminated area. Further, the purifying agent A may contain a mixture of nutrients and water retention agents for maintaining an environment for decomposing pollutants. Even in that case, it is important to control penetration in the depth direction by using a solution having an appropriate viscosity. In addition, as a countermeasure against contamination of VOCs (volatile organic compounds) and hexavalent chromium, only a nutrient for microbial decomposition in an anaerobic state may be introduced as a purification agent A, or a Fenton method or the like may be used. Oxidizing agent may be added. In addition, the purification agent A may be additionally introduced if necessary according to the confirmation status of the purification effect by monitoring.

  The dispersion tube 13 is preferably embedded in the crushed stone layer 15, but may be installed on the crushed stone layer 15.

DESCRIPTION OF SYMBOLS 1 Ground surface 2 Unsaturated layer in the ground 5 Soil contaminant 8 Depression (plane area)
13 Dispersion pipe 15 Crushed stone layer (cleaning agent reservoir)
A Cleaner

Claims (1)

In the process of soil purification that detoxifies soil pollutants that have penetrated into the ground from the ground surface,
A plane region that is horizontally expanded on the ground surface so as to include the starting point of the route on the ground surface where the soil pollutants penetrated into the ground,
Next, in this planar region, there are innumerable voids and a purifier storage layer capable of storing the purifier in each void is created,
Next, the purifying agent is stored in a state in which the purifying agent is spread in a planar shape in the purifying agent storage layer,
Next, decontamination of the soil pollutant is achieved by allowing the cleaner stored in the purifier reservoir to permeate into the ground by gravity along a path through which the soil pollutant penetrates into the ground. A soil purification method
As the planar region, a recess excavated shallowly is formed on the ground surface, and then a crushed stone layer is formed as the purifier reservoir in the recess, and then the purification is performed through a dispersion pipe arranged in the crushed stone layer. A soil remediation method characterized in that the agent is spread over the crushed stone layer in a flat state .

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