JP2001289751A - Soil contamination investigating method and land treatment device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method allowing highly accurate investigation of soil contamination degree. SOLUTION: In this investigating method, contamination degree of soil is investigated by means of a land treatment device provided with a suction well 2 which reaches the vicinity of a contaminated position P contaminated with a contaminant, a suction means 3 suction gas inside the suction well 2 so as to evaporate the contaminant in the contaminated position P and so as to collect it with the gas inside the well 2, and a collection pipe 4 having a collection port 4a reaching the vicinity of the contaminated position P. In this method, the gas inside the suction well 2 is collected through the collection pipe 4 to be analyzed.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a technique for investigating soil contamination by volatile pollutants such as organochlorine compounds such as trichlorethylene and tetrachloroethylene.

[0002]

2. Description of the Related Art FIG. 3 shows a purifying apparatus for removing contaminants from a contaminated site contaminated by volatile contaminants such as an organic chlorine compound. The purifying apparatus shown here comprises a suction well 2 composed of a suction pipe 1 buried in soil S so as to reach a vicinity of a polluted point P contaminated with a pollutant such as an organic chlorine compound, and a ground of the suction pipe 1. And a suction blower 3 connected to the end on the side and capable of sucking the gas in the well 2. A sampling hole 1b through which the gas in the suction tube 1 can be collected is provided in the ground portion 1a of the suction tube 1.
Is provided. In order to purify the soil using the apparatus shown here, as shown by the arrow in the figure, the gas in the well 2 for suction is reduced by sucking the gas in the well 2 for suction, thereby reducing the pollution. The contaminants present at the point P are volatilized and flow into the well 2, and are collected together with the gas in the well 2 through the suction pipe 1.

[0003] In order to investigate the degree of soil contamination (contaminant content in soil S at a contaminated site P) for the purpose of checking the degree of purification, etc., when sampling gas in the suction well 2, Sampling hole 1b provided in ground part 1a
Is opened, and the gas in the suction tube 1 is collected therefrom. The collected gas is used for analysis such as pollutant concentration measurement.

[0004]

However, according to the above prior art, it is relatively accurate to investigate the degree of soil contamination during the suction operation, that is, during the operation of sucking the gas in the well 2 by the suction blower 3. However, when investigating the degree of contamination when the suction operation is stopped, there is a problem that it is difficult to investigate the degree of contamination with high accuracy, especially when the contamination point P exists at a deep position. This is because the specific gravity of the volatile contaminants (organic chlorine compounds, etc.) is generally higher than that of air, so that the contaminants move to the lower part of the well 2 when the suction operation is stopped. 1b, the concentration of pollutants in the gas collected from
This is considered to be because the contamination degree at the underground contamination point P is not accurately reflected. The present invention has been made in view of the above problems, and has as its object to provide a method capable of conducting a highly accurate pollution degree survey when investigating a soil pollution degree.

[0005]

According to a first aspect of the present invention, there is provided a method for investigating soil contamination, comprising: a suction well reaching near a contaminated site of soil contaminated with volatile contaminants; and suctioning gas in the well. Using a soil purifying device including a suction means for volatilizing contaminants at the contaminated site and collecting the gas together with the gas in the well, and a collection pipe installed so that the collection port reaches near the contaminated site in the well. This is a method for investigating the degree of soil contamination, wherein a gas in a suction well is sampled from a sampling port through a sampling tube, and the gas is analyzed. In this method, the gas in the well is collected using a collection pipe whose collection port is located near the contaminated point, so that it is possible to collect gas containing a contaminant at a concentration corresponding to the degree of soil contamination at the contaminated point. . Therefore, highly accurate pollution degree investigation is possible.

According to a second aspect of the present invention, there is provided a method for investigating soil contamination, wherein a sampling pipe capable of adjusting a depth position of a sampling port is used, and gas in the suction well is sampled by changing the depth position of the sampling port. This is a method characterized by being performed a plurality of times. In this method, by analyzing each gas sampled while changing the depth position of the sampling port, even if the contaminated site extends over a wide range in the depth direction, the contamination level distribution in the depth direction of the contaminated site can be easily determined. And it can be grasped accurately.

According to a third aspect of the present invention, there is provided a soil purification apparatus, comprising: a suction well reaching a vicinity of a contaminated site of soil contaminated with a volatile contaminant; and a gas in the well being suctioned to volatilize the contaminated material at the contaminated site. The apparatus further comprises a suction means for collecting the gas together with the gas in the well, and a sampling pipe provided so that a sampling port reaches near a contaminated site in the well.

[0008]

FIG. 1 shows a soil purification apparatus which can be used for carrying out an embodiment of the method for investigating soil contamination according to the present invention. A suction well 2 composed of a suction pipe 1 buried in soil S so as to reach the vicinity of a contaminated point P contaminated with a toxic contaminant, and suction means as suction means capable of sucking gas in the well 2 The blower 3 and the sampling port 4a at the lower end are near the contaminated point P in the well 2 (preferably the contaminated point P
(Substantially the same depth as that of the sampling pipe 4).

The material of the suction tube 1 constituting the suction well 2 is preferably stainless steel, polyvinyl chloride, or the like, and can be appropriately selected and used according to the contaminant concentration at the contaminated site P. It is preferable to set the diameter of the suction tube 1 so that the inner diameter is about 10 cm. The suction pipe 1 extends substantially vertically from the lower end located near the contaminated point P toward the ground, is formed in an L-shape bent in the horizontal direction on the ground, and has a suction blower 3 at the ground end. It is connected to the. It is preferable that the suction pipe 1 is installed so that its lower end is located slightly below (preferably about 1 m below) the lowermost part of the contaminated point P. Suction tube 1
The underground part has been subjected to strainer processing so that air in the soil can flow into the pipe.

The collection pipe 4 is for collecting gas in the suction well 2, and extends from the collection port 4 a at one end located near the contaminated point P in the well 2 in the ground direction along the well 2. It extends to the outside of the suction pipe 1 at the ground part 1a, the ground side end 4b is connected to the suction pipe 1, and gas near the contaminated point P below the well 2 flows through the collection pipe 4 from the collection port 4a. The air flows toward the ground-side end 4b and can flow again into the suction pipe 1 on the ground.

As the sampling tube 4, a tube made of a material to which contaminants hardly adhere, for example, Teflon (registered trademark) (polytetrafluoroethylene) is preferable. It is desirable to set the inner diameter of the sampling tube 4 to about 2 to 10 mm.

A three-way valve 5 is attached to a portion of the sampling pipe 4 extending outside the suction pipe 1 on the ground, and guides the gas in the sampling pipe 4 to a branch pipe 6 connected to the three-way valve 5. You can do it.

In order to purify the soil using the apparatus shown here, as shown by the arrow in the figure, the gas in the suction pipe 1 is sucked by the suction blower 3 to lower the pressure in the well 2. In addition, the air in the soil around the well 2 is caused to flow into the well 2, and the volatilization of the pollutants existing at the polluted point P is promoted. As a result, the volatile contaminants flow into the well 2 together with the air in the soil around the well 2 and are collected by the blower 3 through the well 2 (hereinafter, this operation is referred to as a suction operation). When the pollutant volatilizes, the amount of volatilization is a value corresponding to the degree of soil contamination (contaminant content in the soil) at the contaminated site P. The amount depends on the degree of contamination at the point P.

During the suction operation, the gas in the well 2 is constantly circulated in the well 2 and is agitated, so that the gas is made uniform. Therefore, the concentration of the contaminant in the gas in the well 2 depends on the degree of soil contamination (contaminant content in the soil) at the contaminated site P regardless of the position in the well 2.

When performing the suction operation, the three-way valve 5 attached to the collection pipe 4 is used to allow the gas in the collection pipe 4 to flow through the collection port 4.
If it is set so that the gas can flow from the a side to the ground side end 4b side, the gas in the well 2 near the contaminated point P flows through the collection pipe 4 from the collection port 4a to the ground side end 4b. And the concentration of pollutants in the gas in the sampling pipe 4 becomes equal to the concentration of pollutants in the gas in the well 2, eliminating the need to discharge the residual gas in the sampling pipe 4 at the time of gas sampling described below. Is preferred.

Next, taking the case where the above-mentioned device is used as an example,
An embodiment of the method for investigating soil contamination of the present invention will be described.
Volatile pollutants to be investigated in the present invention include, for example, dichloromethane, carbon tetrachloride, 1,2-dichloroethane, cis-1,2-dichloroethylene,
Examples thereof include 1,1-trichloroethane, 1,1,2-trichloroethane, trichloroethylene, tetrachloroethylene, benzene, 1,1-dichloroethylene, and 1,3-dichloropropene.

In the method of this embodiment, by operating the three-way valve 5 attached to the collection pipe 4, the collection port 4a
After allowing the gas in the well 2 introduced into the collection pipe 4 to flow into the branch pipe 6, the gas in the well 2 is collected through the collection pipe 4, the three-way valve 5, and the branch pipe 6. At the time of gas sampling, the gas in the sampling pipe 4 can be sucked using a sampling blower (not shown) as necessary.

When the gas is collected during the suction operation, the gas in the well 2 that has been made uniform is collected through the branch pipe 6. As described above, the concentration of the pollutant in the gas in the well 2 depends on the degree of contamination of the soil at the polluted point P. Therefore, the collected gas is analyzed by a method such as gas pollutant concentration measurement using gas chromatography or the like. , It is possible to conduct a highly accurate pollution degree survey.

According to the investigation method of the present embodiment, even when the suction operation is stopped in the well 2 where the pollutant concentration tends to be uneven, the contamination degree can be investigated with high accuracy as in the case of the suction operation. This is for the following reason. When the suction operation is stopped, the gas is not circulated in the well 2, and contaminants such as an organic chlorine compound having a higher specific gravity than air are unevenly distributed in the lower part of the well 2. In the lower part of the well 2, since the gas inside and outside the well 2 is balanced by diffusion, the contaminant concentration is a value corresponding to the degree of soil contamination (contaminant content in soil) at the contaminated point P located in the lower part of the well 2. Becomes

For this reason, by collecting the gas in the well 2 through the collection pipe 4 whose collection port 4a is located near the contaminated point P, the contaminant having a concentration corresponding to the degree of soil contamination at the contaminated point P is contained. The gas in the lower part of the well 2 can be collected. Therefore, by using the collected gas for analysis such as measurement of contaminant concentration using gas chromatography or the like, highly accurate pollution degree investigation can be performed.

Since the gas can be collected from the branch pipe 6 by operating the three-way valve 5 provided on the collection pipe 4, the gas can be collected by a simple operation. Therefore, when the soil is purified using the soil purification device, the progress of the purification can be easily and accurately grasped. In order to perform gas sampling when the suction operation is stopped, it is preferable to extract the gas in the sampling pipe 4 after discharging the residual gas in the sampling pipe 4 through the branch pipe 6.

In the above-mentioned soil purification apparatus, the suction well 2 reaching the vicinity of the contaminated point P, the suction blower 3 for sucking the gas in the well 2, and the sampling port 4a are connected to the contaminated point P in the well 2. Sampling tube 4 installed to reach near P
The gas in the suction well 2 is collected at the sampling port 4a.
, Through the collection pipe 4, a gas containing a pollutant having a concentration corresponding to the degree of contamination of the soil at the contaminated point P can be collected. Therefore, highly accurate pollution degree investigation is possible.

Also, in the present invention, as shown in FIG.
It is also possible to configure so that the depth position of 4a can be adjusted. When investigating the degree of soil contamination using the sampling pipe 14, the depth of the sampling port 14a of the sampling pipe 14 is changed and the gas in the well 2 is sampled a plurality of times. I do. According to this method, even if the contaminated point P 'extends over a wide range in the depth direction, the contamination degree distribution in the depth direction of the contaminated point P' can be easily and accurately grasped.

The configuration in which the depth position of the sampling port can be adjusted is not limited to a telescopic sampling tube, but may be a sampling tube whose height can be adjusted. Further, the gas sampling may be performed a plurality of times, or may be performed continuously while changing the depth position of the sampling port.

[0025]

As described above, in the method for investigating soil contamination according to the first aspect, a suction well reaching the vicinity of a contaminated site of soil contaminated with volatile contaminants, Soil provided with a suction means for volatilizing contaminants at a contaminated site by sucking gas and collecting the gas together with the gas in the well, and a sampling pipe provided so that a sampling port reaches near the contaminated site in the well. Using a purification device,
Since the gas in the suction well is collected from the collection port through the collection pipe, a gas containing a pollutant having a concentration corresponding to the degree of soil contamination at the contaminated site can be collected. Therefore, highly accurate pollution degree investigation is possible. Also, when performing soil purification using the above soil purification device,
The progress of purification can be accurately grasped.

In the method for investigating soil contamination according to the second aspect of the present invention, the sampling pipe is used to adjust the depth position of the sampling port, and the gas in the suction well is sampled at the depth position of the sampling port. Is performed a plurality of times while changing the contaminated point, even if the contaminated point extends over a wide range in the depth direction, the contamination degree distribution in the depth direction of the contaminated point can be accurately grasped.

[0027] In the soil purification apparatus according to claim 3,
A suction well reaching the vicinity of the contaminated site of the soil contaminated with the volatile contaminants; and a suction unit for volatilizing the contaminated material at the contaminated site by suctioning the gas in the well and collecting the gas together with the gas in the well. And a sampling pipe installed so that the sampling port reaches the vicinity of the contaminated site in the well. By collecting the gas in the suction well through the sampling tube from the sampling port, the degree of contamination of the soil at the contaminated site is improved. A gas containing a contaminant at a concentration corresponding to the temperature can be collected. Therefore, highly accurate pollution degree investigation is possible.

[Brief description of the drawings]

FIG. 1 is a schematic configuration diagram showing a soil purification device that can be used to carry out an embodiment of the method for investigating soil contamination of the present invention.

FIG. 2 is a schematic configuration diagram showing a soil purification device that can be used to implement another embodiment of the method for investigating soil contamination of the present invention.

FIG. 3 is a schematic configuration diagram showing a soil purification device capable of implementing an example of a conventional soil contamination investigation method.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Suction pipe, 2 ... Suction well, 3 ... Suction blower (suction means), 4, 14 ... Sampling pipe, 4a, 14a ... Sampling port, P ... Contamination Location, S ... soil

Claims (3)

[Claims] 1. A suction well reaching near a contaminated site in a soil contaminated with volatile contaminants, and a gas in the well is sucked to volatilize the contaminated material in the contaminated site and to remove the contaminated material together with the gas in the well. A method for investigating the degree of contamination of soil using a soil purification device having a suction means for collecting and a collection pipe installed so that a collection port reaches near a contaminated point in the well, comprising: A method for investigating soil contamination, characterized in that gas is collected from a sampling port through a collection pipe and this gas is analyzed. 2. The method according to claim 1, wherein the sampling pipe is capable of adjusting the depth position of the sampling port, and the gas in the suction well is sampled a plurality of times by changing the depth position of the sampling port. 1. The method for investigating soil contamination according to 1. 3. A suction well reaching the vicinity of a contaminated site in soil contaminated with volatile contaminants, and a gas in the well is sucked to volatilize the contaminated material at the contaminated site and to collect the gas in the well. A soil purification apparatus comprising: a suction means for collecting; and a collection pipe installed so that a collection port reaches near a contaminated site in the well.