JPH11207316A - Method for preventing ground water contamination and treatment of contaminated ground water - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for preventing ground water from being contami nated, capable of preventing the contaminated ground water from flowing to the downstream side from a cutoff wall by closing an aperture disposed at this cutoff wall when the ground water has been contaminated. SOLUTION: This method for preventing the contamination of ground water consists of forming an underground dam D with the cutoff wall 4 which partitions the underground water permeable layer 2 and is provided with an aperture. An intake means 9 which takes out the ground water stored on the upstream side of the cutoff wall 4 to the outside and an opening/closing means for opening and closing the aperture are provided. When the ground water taken in by this intake means 9 is contaminated, th flow of the contaminated ground water to the downstream side from the cutoff wall 4 is prevented by closing the aperture 10 by the opening/closing means 9, to prevent the expansion of the contaminated region.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a method for preventing groundwater contamination and a method for treating contaminated groundwater.

[0002]

2. Description of the Related Art Conventionally, as a sewage leakage monitoring device at a waste disposal site, there is one disclosed in Japanese Patent Application Laid-Open No. 6-63527, for example.

[0003] In this publication, it is detected whether or not a waterproof sheet covering a waste disposal site is broken by dumped waste or the like, so that waste water leaks out of the disposal site. Attempts are made to prevent pollution by keeping it to a minimum.

[0004]

However, although there is a sewage leak monitoring device at a waste disposal site, once sewage leaks and groundwater is polluted,
There is no effective means.

The present invention has been made on the basis of the above circumstances. When groundwater is contaminated, an opening provided in a water stop wall is closed to prevent the contaminated groundwater from flowing downstream from the water stop wall. It is an object of the present invention to provide a method for preventing groundwater contamination and a method for treating contaminated groundwater that can be made as described above.

[0006]

According to a first aspect of the present invention, there is provided a method for preventing underground water pollution, comprising forming a subsurface dam by a water blocking wall having an opening and partitioning a permeable layer underground. An intake means for taking in the groundwater stored on the upstream side of the water stop wall to the outside, and an opening / closing means for opening / closing the opening, wherein the opening / closing means is provided when the groundwater taken by the intake means is contaminated. By closing the opening, the contaminated groundwater is prevented from flowing downstream from the water stop wall, thereby preventing the contamination area from expanding.

According to a second aspect of the present invention, there is provided a method for treating contaminated groundwater, comprising forming an underground dam with a water-stop wall provided with an opening and partitioning an underground permeable layer, and storing the groundwater at an upstream side of the water-stop wall. A water intake means for taking water to the outside, and an opening / closing means for opening and closing the opening, and when the groundwater taken in by the water intake means is contaminated, the opening and closing means closes the opening and is contaminated. The groundwater is prevented from flowing downstream of the water stop wall to prevent the contamination area from expanding, and the contaminated ground water stored upstream of the water stop wall is taken in by the water intake means for purification treatment. Things.

[0008]

An embodiment of the present invention will be described below with reference to the drawings. In FIG. 1 to FIG. 4, D is an underground layer above an impermeable layer 3 made of rock or a clay layer in a valley topography in order to dam the flow of groundwater and store water in the groundwater layer 2 (permeable layer). It is an underground dam formed by the water blocking wall 4 (water blocking wall) provided in the area. The groundwater layer 2 (permeable layer) is located below the surface layer 1 formed of a poorly permeable layer or a permeable layer, and is formed of a gravel layer or the like.

[0009] The underground dam D is located downstream of a groundwater pollution source such as a waste disposal site, a farm, a golf course, a factory, an excrement disposal site, etc., not shown.

The water blocking wall 4 is provided so as to partially penetrate into the water impermeable layer 3 from the bottom of the surface layer 1 and is made of concrete which partitions the water permeable layer 2 in the vertical direction. A storage section 5 for groundwater flowing through the permeable layer 2 is formed on the upstream side of 4. An opening 10 is provided in the water blocking wall 4, and the opening 10 is opened and closed by opening and closing means.

The opening / closing means is provided, for example, in a cylindrical tubular member 6 in an opening 10 provided in a part of the water blocking wall 4, and is rotatably provided inside the tubular member 6, and has an outer diameter of the tubular member. 6
3. More specifically, a tubular inner member 7 having substantially the same inner diameter as that of FIG.
As shown in FIG. 4, slit-shaped openings 6a, 6b, 6c, and 6d are formed on the peripheral surface facing the water-permeable layer 2 on the upstream side and the downstream side of the water blocking wall 4 so as to face each other. ing.

The inner member 7 also has openings 7a, 6b and 6c, 6c, 6d corresponding to the openings 6a, 6b, 6d of the tubular member 6.
7b, 7c and 7d are formed.

A disk portion 7e is provided on the upper portion of the inner member 7, and an operating member 8 for rotating the inner member 7 from the disk portion 7e through the surface layer 1 is provided on the ground portion. You have been in court.

Reference numeral 9 denotes a water intake means for taking in groundwater in the storage unit 5 to the outside. The water intake means is constituted by an intake well communicating from the surface layer 1 to the permeable layer 2, and the groundwater stored in the storage unit 5 is supplied by a water supply device (not shown). It is possible to take water.

Then, the groundwater is periodically taken by the water intake means 9 and a water quality test is performed to determine whether the groundwater is contaminated.

[0016] When groundwater is contaminated, for example, cadmium and its compounds, cyanide, organic phosphorus compounds, lead and its compounds, hexavalent chromium, arsenic, total mercury, PCB, etc. Is not exceeding a reference value (for example, 0.002 mg / liter in the case of cadmium and its compound), and whether or not a contaminant (for example, alkylmercury) is detected. In addition, as living environment items, PH, BOD, COD, SS, coliform count, oil content,
Whether phenol or the like does not exceed a reference value (for example, 1 mg / liter for phenol), and other items such as copper, zinc,
Iron, manganese, chromium, fluorine, nitrogen, phosphorus, etc. are standard values (for example, chromium is 2 mg /
Liters).

As a result, if the groundwater taken in by the water intake means 9 is not contaminated and it is desired to flow the groundwater downstream from the water stop wall 4, the operation member 8 is manually operated or a motor (not shown) or the like is used. The inner member 7 is rotated by the driving means, and as shown in FIG.
7b and 7c, 7d are the respective openings 6a, 6b of the tubular member 6.
When the inner member 7 is controlled to open the opening of the tubular member 6 so as to coincide with the positions of 6c and 6d, the water in the reservoir 5 is moved to the opening of the tubular member 6 as shown by the arrow. 6d and 6b, and through each opening of the inner member 7, from the openings 6a and 6c of the tubular member 6 to the water blocking wall 4.
Outflow downstream of.

Conversely, when the groundwater taken in by the water intake means 9 is contaminated, the opening 10 is closed by the above-mentioned opening / closing means to prevent the contaminated groundwater from flowing downstream from the water stop wall 4. .

That is, from the state of FIG. 3, the inner member 7 is rotated clockwise by 90 degrees as shown in FIG. 4, and the openings 7a, 7b and 7c, 7d of the inner member 7 are
When the operation is controlled so as not to coincide with the positions of the openings 6a, 6b and 6c, 6d, that is, the inner member 7 closes the opening of the tubular member 6, the outflow of water from the reservoir 5 is prevented. .

Further, by specifying the contaminants from the contaminated groundwater, a waste treatment plant, a farm, a golf course, a factory, excrement, which is located on the upstream side of the water blocking wall 4, which is a source of the contamination, may be specified. A treatment plant or the like can be specified, and groundwater contamination can be more effectively prevented.

Further, when the groundwater is contaminated, the contaminated groundwater stored upstream of the cutoff wall 4 is removed from the water supply means 9.
Thus, the purified water can be removed, the purified water can be drained, the polluted underground dam D can be purified, and the contaminated underground dam D can be reused.

The means for purifying the contaminated groundwater that has been taken in by the water intake means 9 includes:
Well-known contact aeration tank, rotary plate contact tank, biological filter bed tank, aeration tank, sedimentation tank (biological sludge), inclined plate (including inclined pipe) sedimentation tank, coagulation tank, pressurized flotation tank, filtration tank, Reverse osmosis equipment, ultrafiltration equipment, granular activated carbon processing equipment, powdered activated carbon processing equipment,
Ozone treatment equipment, chemical injection equipment (for the chemicals used, for example, depending on the purpose of use, for example, polyaluminum chloride, bansulfate, ferric chloride, slaked lime, caustic soda, polymer flocculant, sodium hypochlorite, Solid chlorine, hydrogen peroxide, formalin, citric acid, oxalic acid, hydrochloric acid, sulfuric acid, sodium carbonate, sodium nitrate, salt, etc.).

[0023]

According to the method for preventing groundwater contamination according to the first aspect, when the groundwater taken in by the water intake means is contaminated, the opening provided in the water stop wall is closed by the opening / closing means to remove the contaminated groundwater. By preventing the water from flowing downstream from the water stop wall, the expansion of the contaminated area can be prevented.

According to the method for treating contaminated groundwater according to claim 2, when the groundwater taken in by the water intake means is contaminated, the opening provided in the water stop wall is closed by the opening / closing means, and the contaminated groundwater is contaminated. Can be prevented from flowing downstream from the water stop wall, thereby preventing the expansion of the contaminated area.
Further, the contaminated groundwater stored on the upstream side of the water stop wall can be purified by taking the groundwater by the water intake means.

[Brief description of the drawings]

FIG. 1 is a schematic longitudinal sectional view of an underground dam used in one embodiment of the present invention.

FIG. 2 is a schematic sectional view taken along line AA of FIG. 1;

FIG. 3 is a schematic cross-sectional view taken along line BB of FIG. 2, showing an opening operation of an opening / closing unit.

FIG. 4 is a schematic cross-sectional view taken along line BB of FIG. 2, showing a closing operation of the opening / closing means.

[Explanation of symbols]

 D Underground dam 2 Permeable layer 4 Water blocking wall 10 Opening

Claims (2)

[Claims] 1. An underground dam formed by a water blocking wall provided with an opening and partitioning an underground permeable layer, and a water intake means for drawing groundwater stored upstream of the water stopping wall to the outside, and the opening Opening / closing means for opening and closing, when the groundwater taken in by the water intake means is contaminated, the opening is closed by the opening / closing means to prevent the contaminated groundwater from flowing downstream from the water stop wall. Thus, a method for preventing groundwater contamination, comprising preventing an expansion of a contaminated area. 2. A water intake means for partitioning an underground permeable layer and forming an underground dam with a water stop wall provided with an opening, and for taking ground water stored upstream of the water stop wall to the outside, Opening / closing means for opening and closing, when the groundwater taken in by the water intake means is contaminated, the opening is closed by the opening / closing means to prevent the contaminated groundwater from flowing downstream from the water stop wall. A method for treating contaminated groundwater, wherein the contaminated groundwater stored on the upstream side of the water stop wall is taken in by the water intake means for purification while preventing the expansion of the contaminated area.