JP4538804B2 - How to restore dumping sites and disposal sites - Google Patents

Description

The present invention relates to a dumping site and a disposal site repair method .

In recent years, in the waste disposal sites and illegal dumping sites in the recycling business, restoration work has been carried out to dig up and remove waste buried in the ground. There are cases where a large amount of gases such as methane, hydrogen sulfide, and volatile toxic substances exist in the waste layer that is the target. For this reason, it is a common practice to collect soil and gas by drilling or the like for each area to be dug during a restoration work, and to investigate the gas concentration and range of the soil, and contaminated species.
As a method for investigating this soil gas, there is a method in which a sampling hole or a sampling tube is provided in the ground from the viewpoint of sampling according to depth, for example, proposed in Patent Document 1 and Patent Document 2.
Patent Document 1 includes a sampling hole drilled in the contaminated soil, a sampling device inserted into the sampling hole, and a sampling container communicated with the sampling device via a pipe, and uses a suction pump. Then, the soil gas is sucked and the concentration of the gas accumulated in the collection container is measured. Specifically, the gas permeability is measured according to the time until the pressure accumulated in the collection container rises to a predetermined pressure by descending while sequentially drilling at a certain depth at each observation point and collecting the soil gas at the same time. Is used to estimate the soil gas pollution distribution.
In Patent Document 2, a hole having a predetermined depth and diameter is drilled in the soil to be investigated, a sampling tube is inserted into the soil, soil gas is collected, and the soil is analyzed by an analyzer connected to the sampling tube. The gas is analyzed.
JP 2000-9721 A JP 2004-184105 A

However, in the above-mentioned restoration work, the illegal dumping site and the disposal site are divided into predetermined restoration areas, and excavation work is performed, and a gas survey is carried out for each of these divided restoration areas. The present situation is that the distribution state of soil gas at the dumping site and the entire disposal site is not grasped. In addition, there is a possibility that construction may be performed in a state where dangerous gas that may cause danger to human life or explosion may not be completely removed, and repair work based on planned gas management has not been carried out. Therefore, there was a problem that sufficient safety was not ensured.
Moreover, since patent document 1 is the method of pressure-controlling the extract | collected soil gas, it took time for the investigation in the observation point per place. In addition, since Patent Document 2 is configured to directly measure with an analyzer from a sampling tube, for example, when water is present in the soil, the water can enter the analyzer and cause a failure. Careful measurement work was required. As described above, the conventional soil gas investigation methods including Patent Document 1 and Patent Document 2 are unsuitable for quick and simple measurement at many observation points.

The present invention has been made in view of the above-described problems, and an object thereof is to provide a dumping site and a disposal site repair method that improve safety by managing soil gas in the dumping site and the entire disposal site. It is said.

In order to achieve the above object, in the dumping site and disposal site repair method according to the present invention, the dumping site and disposal site where waste is buried and the dumping site and disposal site are regenerated after removing soil gas. This is a method that collects and analyzes soil gas at a predetermined location to conduct gas surveys on the dumping site and the entire disposal site, and creates concentration distributions for the entire survey target to grasp the existence range and concentration of various gases . A removal device that replaces the soil gas with air by feeding air into the soil simultaneously with the suction of the soil gas and removes it according to the components of the soil gas at one step and the predetermined location based on the created concentration distribution I am characterized in that the gas concentration in the layer comprising the waste has a second step of removing the soil gas until safe, and a third step of removing the waste after removal of the soil gas by That.
In the present invention, a gas survey is performed on the dumping site and the entire disposal site to manage the soil gas, and the dangerous soil gas can be removed systematically and accurately based on the analysis result of the gas survey. . Then, after confirming the safe gas concentration, the removal work of the waste is performed, and the construction can be performed in a state in which the safety is improved.
At this time, by sending air into the soil, there is no residual residue of the soil gas and suction can be performed reliably. And the suction | inhaled soil gas can be efficiently removed by using the removal apparatus suitable for the component of gas.

Further, in the dumping site and disposal site repair method according to the present invention, when there are a plurality of layers of waste, a series of steps from the first step to the third step is sequentially performed for each layer or for each of the plurality of layers. It is preferable to repeat.
In the present invention, since the distribution and concentration of the soil gas is managed for each layer where the excavation work is performed and dangerous gas is removed, safety can be improved.

  According to the dumping site and disposal site repair method of the present invention, the soil gas distribution state is managed after investigating the soil gas in the dumping site and the entire disposal site, and systematically based on the analysis result of the gas survey. In addition, it is possible to accurately remove dangerous soil gas. Then, after confirming the safe gas concentration, the removal work of the waste is performed, and the construction can be performed in a state in which the safety is improved.

Hereinafter, a dumping site and a disposal site repair method according to an embodiment of the present invention will be described with reference to FIGS.
FIG. 1 is a diagram showing gas survey means according to an embodiment, wherein (a) is an overall view thereof, (b) is an enlarged view of a bottom of a sampling tube, FIG. 2 is a diagram showing an operation of removing soil gas, FIG. Fig. 4 is a diagram showing a waste layer removal operation, Fig. 4 is a diagram showing a second layer soil gas removal operation at the dumping site, Fig. 5 is a diagram showing a substitution state of soil gas and air in the gas removal operation, 6 is a concentration distribution diagram showing a first result case of the soil gas survey, and FIGS. 7A and 7B are concentration distribution diagrams showing a second result case of the soil gas survey.

The dumping site and disposal site repair method according to the present embodiment targets the dumping site 1 including a waste disposal site, an illegal dumping site, and the like.
As shown in FIG. 1A, the dumping site 1 in the present embodiment is formed by alternately stacking a plurality of waste layers 2 (layers made of waste) and covering soil 3 in which wastes are buried. (See FIG. 2).

As shown in FIGS. 1 to 3, the repair method at the dumping site 1 uses gas survey means 4 (soil gas survey mechanism) that collects and analyzes soil gas such as methane, hydrogen sulfide, and volatile toxic substances. The first step of conducting a gas survey (see FIG. 1), the second step of removing soil gas (see FIG. 2) using the gas removing means 5 based on the analysis result, and then confirming safety It consists of a third step of digging up and removing the waste layer 2 and the covering soil 3 (see FIG. 3).
Such a repairing operation including a series of steps from the first step to the third step is sequentially performed for each layer from the waste layer 2 on the ground surface 1a side (see FIG. 4).

As shown in FIG. 1, the gas survey means 4 includes a sampling pipe 6 that passes from the ground surface 1a through the first layer of covering 3 and penetrates to a predetermined position of the waste layer 2 that is the lower layer, and a sampling pipe 6 is an outline of a gas-liquid separator 7 that separates the substance sucked from 6 into gas-liquid and sends out only the soil gas to the outlet side, and an analysis means 8 that detects and analyzes the soil gas sent out by the gas-liquid separator 7. It is configured.
The sampling tube 6 and the gas-liquid separation device 7 are connected by a connection tube 9, and the gas-liquid separation device 7 and the analysis means 8 are connected by an introduction tube 10. A valve 11 is provided at an intermediate portion of the connecting pipe 9. A filtration member 12 for filtering gas is provided in the middle of the introduction pipe 10.

As shown in FIGS. 1A and 1B, the collection tube 6 is made of, for example, aluminum or stainless steel, and for example, a tube material having a diameter of about 5 mm is used. Further, the sampling tube 6 is provided with a plurality of suction holes 6c for sucking soil gas at the outer periphery 6b of the end portion. Further, since the tip 6a is blocked in a pointed shape, it is possible to prevent the tube from being blocked by soil or the like during penetration.
The gas-liquid separation device 7 shown in FIG. 1 (a) separates the liquid contained in the soil gas into gas-liquid when, for example, liquid such as ground water or a puddle is sucked, and the liquid is, for example, gas-liquid separation device. 7 is discharged to a container (not shown) or the like, and gas (soil gas) is sent to the introduction pipe 10 connected to the outlet side. As a result, it is possible to prevent the analysis means 8 from malfunctioning or contaminating due to liquid mixture. In addition, when what was suck | inhaled with the collection pipe | tube 6 is gas (soil gas), it is naturally possible to let the gas-liquid separation apparatus 7 pass to the exit side as it is, and it is another mechanism which removes a water | moisture content. Also good.
Further, the analysis means 8 shown in FIG. 1A is provided with an outlet 10a of the introduction tube 10 so that it can be taken back to a portable handy type analyzer which can be directly analyzed at the outlet 10a of the introduction tube 10 or taken into a test room. An analysis means 8 that is excellent in portability and simple in analysis work, such as a sample pack in which soil gas is sealed in, is preferable.

As shown in FIG. 2, the gas removing means 5 includes a gas suction pipe 14 made of a steel pipe or the like having a tip 14 a penetrating the waste layer 2, and a blower 15 that is connected to the gas suction pipe 14 and sucks soil gas. And a removing device 16 for removing the sucked soil gas for each component and releasing it into the atmosphere. An air inflow pipe 17 such as a steel pipe is disposed at a predetermined location of the waste layer 2. At this time, the position and the number of the air inflow pipes 17 are adjusted by the soil layer 2 and the density of the waste.
The removal device 16 includes, for example, a combustion device 16A that forcibly incinerates methane gas, a first removal device 16B that adsorbs hydrogen sulfide gas to an alkaline solvent, an adsorbent, and the like, and a second removal that adsorbs an organic chlorine compound gas to activated carbon. Device 16C. In addition, it is naturally possible to remove harmful gases by other methods, and it is also possible to install a removing device for removing other harmful substances.
As shown in FIG. 2, the air inflow pipe 17 can efficiently remove soil gas by sending air into the waste layer 2 simultaneously with suction of the soil gas and replacing the soil gas with air. In this way, by sending air into the soil, it is possible to aspirate reliably without leaving any residual soil gas.

Next, a soil gas investigation method using the gas investigation means 4 and a dumping site 1 restoration method will be described with reference to the drawings.
In the soil gas survey, as shown in FIG. 6, an appropriate number of survey points P are set in the survey target area of the dumping site 1, for example, every 10 to 30 m intervals. At each point P, the gas survey means 4 is installed. Here, as shown in FIG. 1 (a), the sampling tube 6 is installed from the ground surface 1a to a predetermined sampling position using, for example, a hand-held electric drill, and has a larger outer diameter than the sampling tube 6. 13 is drilled and the sampling tube 6 is inserted to a predetermined depth, and the gap between the sampling tube 6 and the drilling hole 13 is backfilled with a filler (not shown). And the gas investigation means 4 is prepared and the 1st waste layer 2 near the ground surface 1a is measured (refer FIG. 1).
In this gas survey means 4, since the drilling work of the drill hole 13 is easy, the time required for installation at one survey point P can be reduced.

In the present embodiment, for example, the analysis means 8 using a portable analyzer is used, and as shown in FIGS. 1A and 1B, when soil gas is sucked from the suction hole 6c of the sampling tube 6, for example, The PID value (total amount of volatile organic compounds including petroleum hydrocarbons), TC (total amount of oily hydrocarbons), methane (CH ₄ ), carbon dioxide (CO ₂ ), and oxygen (O ₂ ) are measured simultaneously.
And in the case of such an analyzer, soil gas can be measured on the spot in real time with high accuracy, and it is extremely efficient.

From the analysis results of soil gas obtained at each survey point P as described above, a concentration distribution map (contour diagram) of the entire survey target in the analyzed waste layer 2 is created, and the presence of various gases in the ground The situation can be grasped. Such a density distribution diagram can be easily created by data processing using, for example, appropriate computer software (see FIG. 6).
Furthermore, if such a distribution map is created, it directly reflects the contamination status, and it is possible to visually and intuitively grasp the contamination status of the entire survey target.

Next, as shown in FIG. 2, after grasping the range and concentration where the soil gas exists from the above-described gas concentration distribution diagram, the gas removal means 5 is installed at a predetermined location, and the removal device 16 is highly dangerous. The soil gas is removed and then released into the atmosphere. During the suction removal operation, for example, as shown in FIG. 5, the concentration of the sucked soil gas and the inflowing oxygen (O ₂ ) is confirmed over time, and the removal operation is continued until the concentration becomes lower than the dangerous concentration. . The graph of FIG. 5 shows methane (CH ₄ ), hydrogen sulfide (H ₂ S), and inflowing oxygen (O ₂ ) as soil gas to be removed. According to this, it is confirmed that with the passage of time, the concentration of soil gas decreases and the concentration of oxygen increases. Then, when the soil gas falls below a prescribed concentration, the removal by the removal device 16 is stopped, and the suction of the soil gas and the inflow of air are further terminated. Thus, the hazardous gas in the waste layer 2 is removed.

Subsequently, as shown in FIG. 3, the waste layer 2 and the cover soil 3 from which the removal of the dangerous gas has been completed are removed by the excavating machine 18 and the transporting machine 19, and the repair work of the first layer is completed.
In this removal operation, it is preferable to provide a protective member 20 made of, for example, a film material or the like as shown in FIG. Thereby, scattering of a harmful substance and a strange odor can be prevented in the vicinity.
In the second and subsequent layers, the waste in the dumping site 1 is sequentially repeated while repeating the above-described gas survey (first step), gas removal (second step), and soil removal (third step). The layer 2 and the covering soil 3 are removed (see FIG. 4). When all of the dumping sites 1 are completed, the restoration work is completed by, for example, backfilling uncontaminated soil.

Next, an example of the result of specific analysis by the gas survey method of the present invention will be shown.
FIG. 6 is an example of the first result when a soil gas survey is conducted, and shows the concentration distribution of methane (CH4). In the figure, the darker the portion, the higher the concentration of methane, and the lighter the portion is the concentration. Can be confirmed. According to this, it can be seen that methane having a concentration of 35000 mg / m 3 or more, which is regarded as an explosion limit (line B shown in FIG. 6), exists in more than half of the ground of the dumping site 1.
Further, FIG. 7, in one study point P, a second result cases were further analyzed in detail the collected soil gas, FIG. 7 (a) 1,2-dichloro methane, FIG. 7 (b) PID As shown in FIG. 6, the darker the color, the higher the density. Thus, the existence of each component of the volatile organic compound (VOC) contained in the soil gas can be visually confirmed as a distribution map.

In the method for repairing the dumping site 1 according to the above-described embodiment, the distribution state and gas concentration of the soil gas in the entire survey target area of the dumping site 1 are managed, and the dangerous soil gas is surely removed to be safe. The waste layer 2 can be removed after securing the property.
Further, the gas surveying means 4 has a simple structure, and a substance such as soil gas or groundwater collected at the survey point P is passed through the gas-liquid separation device 7. In order to detect, failure of the analysis means 8 due to liquid intrusion can be prevented. Furthermore, since the analysis work can be performed using the analyzing means 8 at the spot where the gas is investigated, and the soil can be detected immediately after the soil gas is sucked, it can be accurately investigated without taking time.
For this reason, even when a large number of survey points P are required in a waste disposal site having a large area, it is possible to conduct a survey more quickly than the conventional survey method, which is extremely effective. is there. Moreover, since it is easy and low cost can be realized, for example, it is possible to have a large number of gas surveying means 4 and investigate a plurality of survey points P simultaneously.

Having described embodiments of the dumping site and disposal site method of repair according to the present invention, the present invention is not intended to be limited to the above embodiments, and can be suitably changed without departing from the scope thereof .
For example, in the present embodiment, the repair work of the waste layer 2 is performed for each layer. However, in the case of a dumping site 1 composed of a plurality of waste layers 2, the first step to the third step are performed for each of the plurality of waste layers 2. You may work on the process.

It is a figure which shows the gas investigation means by embodiment of this invention, Comprising: (a) is the whole figure, (b) is an enlarged view of a collection pipe bottom part. It is a figure which shows the removal operation | work of soil gas. It is a figure which shows the removal operation | work of a waste layer. It is a figure which shows the removal operation | work of the 2nd layer soil gas in a dumping site. It is a figure which shows the substitution state of soil gas and air in a gas removal operation | work. It is a density | concentration distribution figure which shows the 1st result example of a gas survey. (A), (b) is a density | concentration distribution map which shows the 2nd result example of a gas investigation.

Explanation of symbols

1 dumping site 2 waste layer (layer consisting of waste)
3 Covering soil 4 Gas survey means (Soil Gas Survey Organization)
5 Gas removing means 6 Sampling pipe 6c Suction hole 7 Gas-liquid separator 8 Analyzing means 13 Perforated hole 14 Gas suction pipe 16 Removing apparatus 17 Air inflow pipe P Investigation point

Claims (2)

A dumping site and a disposal site for reclaiming a dumping site and a disposal site where waste is buried after removing soil gas,
The first step of collecting and analyzing the soil gas at a predetermined position to conduct a gas survey on the dumping site and the entire disposal site , creating a concentration distribution of the entire survey target, and grasping the existence range and concentration of various gases ; ,
In the predetermined location based on the created concentration distribution, the soil gas is replaced with the air by sending air into the soil simultaneously with the suction of the soil gas, and the removal device is configured to remove the soil gas according to the components of the soil gas. A second step of removing the soil gas until the gas concentration in the layer of waste is safe ;
A third step of removing the waste after removing the soil gas;
A dumping site and a disposal site repairing method characterized by comprising:   2. The method according to claim 1, wherein when a plurality of layers made of the waste are stacked, a series of steps from the first step to the third step is sequentially repeated for each layer or for each plurality of layers. How to restore the dumping site and disposal site.

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