JP2001323437A - Method of preventing leakage of leachate from reclaimed land, facility therefor, and method of repairing it - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent a leachate leaching from a subject to be buried from leaking and permeating under the ground. SOLUTION: Impervious sheets 3, 6 and 8 for preventing the leakage of the leachate are laid along the inner surface of a hollow 46 dug in the form of a recess in the ground, and a member 18 for forming a space is interposed between a pair of impervious sheets 3 and 6 located in positions corresponding to the bottom face 51 of the hollow. The leakage of the leachate resulting from damage to the upper impervious sheet 3 can be monitored or repair can be made.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for preventing leachate leakage from a landfill, the method for preventing leachate leakage from a landfill, and a facility for preventing leachate leakage from a landfill. It is.

[0002]

2. Description of the Related Art Conventionally, various methods and facilities have been researched and developed to prevent infiltration of landfills, for example, leachate leached from industrial wastes and general wastes from penetrating underground. . For example, Nikkei Construction (NI
In the August 13, 1999 issue of KKEI CONSTRUCTION, there is disclosed the following technology for preventing seepage of water into the underground. That is, there is described a technology for preventing seepage of leachate having a five-layer structure in which a sheet having self-healing properties is sandwiched between two water-blocking sheets, and a nonwoven fabric is applied to the top and bottom of the sheet.

[0003] Further, as a technique for early detection of leakage of leachate, a water-impervious sheet including a sensor for detecting leakage of leachate, a leak detection measuring device and a leak position specifying device, and It describes that when the leachate breaks into the water-impermeable sheet due to breakage, the sensors are short-circuited and energized to notify the abnormality.

As another technique for detecting leachate, the depression is divided into several blocks, reference water is flowed between two water-impervious sheets for each block, and water returned from each block is returned. According to the document, the amount, color, and water quality of the sheet are inspected, and if the value is different from the reference water, it is determined that the sheet is damaged and contaminants or the like are dissolved in the reference water.

[0005]

[0005] However, the above 5)
The technology to prevent penetration into the underground with a layered structure is effective in preventing leakage of leachate because it uses two water-shielding sheets and a sheet with self-healing properties between them. It is difficult to directly and visually confirm the damaged portion of the device.

Further, a technique for detecting breakage of a water-impermeable sheet using a water-impermeable sheet having a built-in sensor for detecting leakage of leachate, a leak detection measuring device and a leak position specifying device is a simple and reliable detection technique. Although it has high performance, it is difficult to directly and visually confirm the damaged portion of the laid sheet in the same manner as described above. Furthermore, if the laid sheet is short-circuited for a reason other than damage, the sheet may be determined to be damaged.

Further, a technique of flowing reference water between two water-impervious sheets for each block and measuring the amount and quality of the water is simple and easy to understand as long as the measuring technique is established. However, the measurement requires careful attention and skill, and may require a great deal of labor for management. Above all, it is difficult to identify the broken portion of the laid sheet and directly visually confirm it.

[0008] An object of the present invention is to prevent the leachate leached from a landfill from penetrating into the underground without leaking.

[0009]

SUMMARY OF THE INVENTION In order to solve the above-mentioned problems, the present invention provides a two-layered leakage prevention sheet for digging down the ground to prevent leakage of leachate along the inner surface of a concavely formed depression. Laying above, a member forming a space is interposed between at least a pair of leak prevention sheets at a position corresponding to the bottom surface of the depression, to prevent leakage of the leachate due to damage to the upper leak prevention sheet. It is characterized in that it can be monitored or the leakage site of leachate can be repaired.

[0010] By doing so, the leachate does not leak underground unless all the leak prevention sheets are damaged. A space is formed between a pair of adjacent leakage prevention sheets by interposing a member that forms a space on the facing surface side between the pair of leakage prevention sheets. Through this space, the presence or absence of leakage of leachate due to breakage of the upper leakage prevention sheet is monitored and directly checked visually. If there is a leak, it is possible to repair the site and prevent the leachate leaching from the landfill at the landfill from leaking into the underground without leaking.

Here, the depression is a depression formed by dug down into the ground. In this case, it is preferable to lay crushed stone, mountain sand, or the like so that groundwater flows and can be recharged at the portion forming the bottom surface of the depression. The shape of the bottom surface of the depression is not particularly limited as long as it is not extremely inclined. However, if it is horizontal and flat, the members forming the space described later can be installed horizontally, so that the construction is easy and preferable.

[0012] Leachate is contaminated water that seeps between landfills buried in a landfill, but may be unpolluted depending on the landfills. Further, there is water that is extracted from the components contained in the landfill itself.
Landfills include industrial waste such as sludge and construction waste, household waste and paper waste from offices, general waste such as waste plastic, and other landfills.

The pair of leakage prevention sheets are made of a durable, chemically resistant sheet, such as a flexible synthetic rubber sheet or a synthetic resin sheet, which is impermeable to leachate, resistant to damage such as tearing, and the like. The thickness is about 1 to 5 mm. Depending on where the leak prevention sheet is used, a protective sheet such as a nonwoven fabric may be used on one or both sides.

The member forming the space forms a space capable of monitoring or repairing the leakage of leachate, and has a strength sufficient to withstand the pressure of the landfill buried in the landfill. The material of this member is not particularly limited as long as it is a material having excellent pressure resistance, durability, chemical resistance, and the like.
It may be formed of a synthetic resin, for example, polypropylene. A member forming a space formed of a synthetic resin is excellent in pressure resistance, durability, and chemical resistance, is lightweight, and is excellent in moldability, workability, and economy.

Further, the member forming the space may be formed integrally, but a plurality of members may be interposed between the pair of leakage prevention sheets. Further, the members may be stacked in two or more stages. By making the members forming the space a plurality of members, the weight of one member,
The size is reduced, and the moldability of the member is improved. In addition, it facilitates handling and improves workability. In this case, it is preferable that the plurality of members have a connecting portion so that they can be connected to each other in the vertical and horizontal directions. Further, the member forming the space preferably has a columnar portion. Since the member forming the space has the columnar portion, a gap is formed between the columnar portion and the columnar portion,
Leachate leaks can be easily monitored or repaired.

The porosity or porosity S of the member forming the space, ie, S = (V1-V2) / V1, where V1: the volume of one member forming the space V2: the mass of one member forming the space The larger the volume converted from is, the better. However, if the porosity S is too large, the required strength of the member may not be secured. Space ratio S
Is up to 97%, preferably around 95%. Conversely, if the porosity S is small, the strength of the member can be increased,
The volume occupied by the members increases, the gap between the columnar portions decreases, and monitoring or repair becomes difficult.

In the present invention, in order to make it possible to monitor or repair leakage of leachate due to breakage of the upper sheet, detection means for detecting a damaged portion of the upper leak prevention sheet, and the upper leak prevention sheet A repairing device having an injecting means for injecting an injectable material into the upper surface side of the device, and a traveling means on which the detecting means and the injecting means can be mounted and which can travel. It is preferable that the repair device is formed so as to be inserted between the leakage prevention sheets having a plurality of members interposed therebetween. In this way, the repair device itself can be maintained.

As the detecting means, for example, a sensor using an optical sensor such as a monitoring camera (CCD camera) or a fiberscope (or an endoscope), a sensor using sound, or the like is used. The injection means has, for example, a tubular elongated member having a sharp tip, an injection material tank, an injection material supply opening / closing valve, and the like used for injecting the injection material. The running means is equipped with a detecting means and an injection means, and has, for example, a bogie having wheels and a driving device therefor.

Further, the repair apparatus may have a controller as a control means, or the controller may be installed outside the ground or the like. Furthermore, the detection signal detected by the detection means and the command signal from the controller may use a signal line such as an electric wiring or an optical fiber,
Signals may be exchanged wirelessly. In the above description, the detection means is mounted on the traveling means. However, the detection means may be provided independently of the injection means and the traveling means.

In the above repairing device, when the detecting means detects a damaged portion of the leakage prevention sheet, the repairing device moves to the damaged portion by the traveling means. Next, the injection member is inserted into the upper leakage prevention sheet from the space side of the pair of leakage prevention sheets by the injection means, and the injection material is injected into the upper surface side of the upper leakage prevention sheet to close the damaged portion. In this case, the injected material may be injected into the damaged portion of the upper leakage prevention sheet, or the injected material may be injected into the damaged portion and a plurality of locations near the damaged portion to close the damaged portion.

In the present invention, another leakage prevention sheet is laid further on a pair of leakage prevention sheets provided with members forming a space, and an upper leakage prevention sheet and another leakage prevention sheet above the pair of leakage prevention sheets. It is preferable to lay a layer of dry powder or granules between them. Another leakage prevention sheet is for preventing leakage of leachate, and may have the same material, thickness, and other quality characteristics as the pair of leakage prevention sheets. The layer of dried powder or granules blocks the leachate that breaks and breaks into another leak prevention sheet, making it difficult for the leachate to flow down to the lower layer.

The space formed by the members forming the space can be used as a storage tank for temporarily storing leachate leached from the landfill. Particularly, when the leachate is sewage, the leachate is temporarily stored to prevent the leachate from flowing to the outside carelessly. In addition, it is possible to take out the leachate continuously little by little and treat it. In this way, the treatment equipment for treating leachate is reduced in size and is economical.

[0023]

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is an exploded perspective view of a leachate prevention facility for use in carrying out a method for preventing leachate leakage from a landfill according to the present invention; In FIGS. 1 to 5, the same or equivalent parts are denoted by the same reference numerals.

FIG. 1 is an overall sectional view showing an embodiment of a facility for preventing leachate leakage from a landfill according to the present invention. FIG.
FIG. 2 is a sectional view of a main part of FIG. The facility 1 for preventing leachate leakage from a landfill according to the present invention includes industrial waste such as sludge and building waste.
It reclaims general waste such as household waste and paper waste from offices, and prevents leachate leached from waste from penetrating underground.

As shown in FIG. 1, the depression 46 is dug down into the ground to form a concave shape, and is provided with a peripheral inclined surface 48 and a bottom surface 51 at the bottom. A horizontal surface 49 is formed on the middle of the inclined surface 48. The portion forming the bottom surface 51 is composed of a mountain sand layer 53 described below and a crushed stone layer 55 formed below the mountain sand layer 53, and is inclined downward toward the center so that water can easily flow.

As shown in FIG. 2, leachate leakage prevention facility 1
The upper water-impervious sheet (leakage prevention sheet) 3 and the lower water-impervious sheet (two layers) are laid in two layers along the inner surface of the bottom surface 51 and the inclined surface 48 (including the horizontal surface 49 of FIG. 1) of the depression 46. (Leakage prevention sheet) 6. Further, a member 18 that forms a space, which is a plurality of members, interposed between the upper water-blocking sheet 3 and the lower water-blocking sheet 6 at a position corresponding to the bottom surface 51 of the depression is provided.

The members 18 forming the space are provided between the upper water-blocking sheet 3 and the lower water-blocking sheet 6 so as to be regularly arranged in the left, right, front and rear planes. To support the load on this sheet. The members 18 forming the space are provided in one stage in FIGS. 1 and 2, but the height of the space may be increased by appropriately overlapping in multiple stages according to the purpose of use.

The material of the upper and lower water-shielding sheets 3 and 6 is impermeable to water, and a flexible synthetic rubber or synthetic resin, for example, a sheet of polyethylene, vinyl chloride, or the like is appropriately used. The thickness is about 1 to 3 mm. Further, a protective sheet 14 is provided between the water-blocking sheet 3 and the water-blocking sheet 6 on the side of the inclined surface 48, so as to alleviate unevenness and relative rubbing between the water-blocking sheets and prevent breakage. A protective sheet 16 is laid on the entire lower surface of the water-blocking sheet 6. The protective sheets 14 and 16 are made of a synthetic resin non-woven fabric or the like, and have a thickness of about 3 to 15 mm.

A layer 30 of dry ash (powder) such as coal ash or combustion ash or dried mountain sand (granules) is further provided on the upper water-blocking sheet 3. Ash or mountain sand layer 3
The thickness of 0 is about 300 to 600 mm. A water-blocking sheet 8 (another leak-proof sheet) is provided on the ash or mountain sand layer 30 via the protective sheet 12. further,
Waste (landfill material) 58 is buried on the water-blocking sheet 8 via the protection sheet 10.

FIG. 3 is a perspective view of a member 18 forming a space used in the leachate leaking facility shown in FIGS. The member 18 forming the space has a flat surface 20a, and includes a flat portion 20 having hanging pieces on four sides and a columnar portion 24 provided extending from the flat portion 20. In this embodiment, the shape of the flat surface 20a of the flat portion 20 when viewed directly is a substantially square. Four columnar portions 24 are provided symmetrically with respect to the flat portion 20, and the flat portion side has a tapered outer cylinder 25 having a large diameter,
And an inner cylinder 26 formed in a tapered shape by being turned inward from the front end 25a toward the flat portion. An elongated hole 21 is provided on the upper surface of the flat portion 20. The weight reduction and material saving are achieved by using the flat portion 20 having the hanging pieces, the double cylindrical columnar portion 24 and the long hole 21.

The material of the member 18 forming the space is made of polypropylene in this embodiment. The size of this member is such that the length and width of the flat portion 20 are each about 700 mm,
The length of the columnar portion 24 is about 390 mm. As such a member 18, for example, Shin Shin Block, a trade name of Hayashi Bussan Co., Ltd., is suitably used.

As shown in FIG. 2, the leachate leak prevention facility 1 of the present embodiment is a robot working vehicle with a camera (repair device).
33, which makes it possible to monitor or repair the leakage of leachate due to breakage of the upper water-impervious sheet 3. The camera-equipped robot working vehicle 33 is formed to be insertable between the upper and lower water-shielding sheets 3 and 6 with the member 18 forming a space interposed therebetween. In order to allow the robot working vehicle 33 with a camera to be inserted between the upper and lower water-blocking sheets 3 and 6, it is preferable to provide an insertion hole that allows insertion from the ground surface (not shown).

Further, the camera-equipped robot working vehicle 33 is
A surveillance camera (detection means) (not shown) for detecting a damaged portion of the upper water-impervious sheet 3, an injection device (injection means) 36 for injecting the injection material 44, and a cart equipped with the monitoring camera and the injection device 36 (Running means) 41. The injection device 36 is provided with an injection needle (injection member) 37 for injecting the injection material 44 into the broken portion of the upper water-blocking sheet 3, an injection material tank 38, and a pump 39. The truck 41 is provided with wheels 42 driven by a drive device (not shown).

The injecting material 44 closes a damaged portion of the water-blocking sheet. For example, the injecting material itself is made of a synthetic resin having fluidity and hardens with the lapse of time. A material that hardens the coal ash 30, for example, a fluid mixture of cement and lime and water. Further, cement or lime may be mixed in advance with the mountain sand or coal ash 30, and water may be used as the injection material.

FIG. 4 is a plan view of the crushed stone layer 55 shown in FIGS. The site forming the bottom surface 51 of the hollow is a mountain sand layer 53 (not shown in FIG. 2).
And a crushed stone layer 55 provided thereunder. In the crushed stone layer 55, a crushed stone flow path for discharging groundwater is provided in a fish bone shape, and has a branch flow path 56a and a main flow path 56b,
It is provided so as to become gradually lower in the direction of the end 57.

The leachate leakage prevention facility of the present invention having the above structure operates as follows. That is, as shown in FIGS. 1 and 2, since three layers of water-impermeable sheets are laid along the inner surface of the depression 46, leachate does not leak to the underground unless all the water-impermeable sheets are damaged. A member 18 forming a space is interposed on a pair of water-impervious sheets at positions corresponding to the bottom surface 51 of the depression, that is, on an opposing surface side between the upper water-impervious sheet 3 and the lower water-impervious sheet 6. A space is formed between the pair of water shielding sheets 3 and 6. This space makes it possible to monitor or repair the presence or absence of leakage of leachate due to breakage of the upper water-blocking sheet 3.

Further, by forming the member 18 forming the space into a plurality of members, the weight of each member can be reduced.
The volume is reduced, the moldability of the member is improved and the member is formed economically, and the workability is improved. Further, since the member 18 forming the space has the columnar portions 24, a gap is formed between the columnar portions 24. By inserting the robot working vehicle 33 with a camera into the gap, leakage of leachate can be prevented. It can be easily monitored or repaired.

FIG. 5 is a schematic plan view after repairing a damaged part. In the above-mentioned camera-equipped robot working vehicle 33, the damaged portion 4 of the water-blocking sheet 3
Is detected. When the surveillance camera detects the damaged part 4, the trolley 41 moves the camera-equipped robot working vehicle 33 to the damaged part 4. Next, an injection needle 37 is inserted into the upper water-impermeable sheet 3 from the space side of the pair of leakage prevention sheets 3 and 6 by the injection device 36. Next, the damaged portion 4 on the upper surface side of the water-blocking sheet 3 and the portion 5a near the damaged portion 4
Inject the injection material 44 into ~ 5 g to close the damaged part 4,
It will be repaired.

In the present invention, the layer 30 of dried ash or mountain sand blocks leachate which is about to enter this layer 30, making it difficult for the leachate to flow down to the lower layer. The space formed by the member 18 forming the space can also be used as a storage tank for temporarily storing leachate leached from the landfill. In particular, when the leachate is sewage, the temporarily stored leachate can be taken out little by little and continuously treated. By treating the leachate in this way, the leachate treatment equipment is reduced in size.

Although the present invention has been described in detail with reference to the illustrated embodiments, the present invention is not limited to only those embodiments, and various modifications can be made without departing from the spirit of the present invention. In addition, it goes without saying that a wide variety of modifications can be made.

[0041]

According to the present invention, it is possible to prevent the leachate leached from the landfill from penetrating into the underground without leaking.

[Brief description of the drawings]

FIG. 1 is an overall sectional view showing one embodiment of a facility for preventing leachate leakage from a landfill according to the present invention.

FIG. 2 is a sectional view of a main part of FIG.

FIG. 3 is a perspective view of a member forming a space used in the seepage water leakage prevention facility shown in FIGS.

FIG. 4 is a plan view of the crushed stone layer and the crushed stone channel of the present embodiment.

FIG. 5 is a schematic plan view after repairing a damaged part.

[Explanation of symbols]

 1 Leachate leakage prevention facility at a landfill 3 Upper water-blocking sheet (upper leakage-blocking sheet) 4 Damaged area 5a-5g Nearby area 6 Lower water-blocking sheet (lower-side leakage prevention sheet) 8 Water-blocking sheet (another (Leak prevention sheet) 18 Member forming space 24 Columnar part 33 Robotic working vehicle with camera (repair device) 36 Injection device (injection means) 41 Bogie (running means) 44 Injection material 46 Depressed ground 51 Bottom surface 58 Waste material Landfill)

Claims (4)

[Claims] The present invention further comprises: laying down two or more layers of a leakage prevention sheet for preventing leakage of leachate along an inner surface of a recessed ground formed by digging down the ground, wherein the sheet is provided at a position corresponding to a bottom surface of the recessed ground. A member that forms a space is interposed between at least one pair of leakage prevention sheets, so that the leakage of the leachate due to breakage of the upper leakage prevention sheet can be monitored or the leakage part of the leachate can be repaired. How to prevent leachate leakage from landfills. 2. Between a leak prevention sheet laid in two layers along an inner surface of a concave ground formed by digging down the ground, and the leak preventive sheet at a position corresponding to a bottom surface of the hollow ground. And a plurality of members interposed between the plurality of members, the plurality of members having a columnar portion, the leakage of the leachate due to the breakage of the upper leakage prevention sheet can be monitored or the leakage site of the leachate can be repaired. A facility to prevent leachate from leaking from landfills. 3. The detecting device according to claim 2, wherein the detecting device detects a damaged portion of the upper leakage prevention sheet, an injection device injects an injection material into an upper surface of the upper leakage prevention sheet, and the detecting device includes: A repair device having a traveling means mounted with the injection means and capable of traveling, the repair device includes:
A facility for preventing leachate from leaking in a landfill, which is formed so as to be inserted between the leakage prevention sheets having the plurality of members interposed therebetween. 4. A two or more layers of a leakage prevention sheet for digging down the ground to prevent leakage of leachate along the inner surface of the depression formed in the concave shape, wherein the leakage prevention sheet is provided at a position corresponding to the bottom surface of the depression. A method for repairing a seepage water leakage prevention facility in a landfill where at least a pair of leak prevention sheets has a columnar portion and forms a space between the pair of leak prevention sheets, wherein a space side between the pair of leak prevention sheets is provided. A method for repairing a leachate leakage prevention facility in a landfill, wherein an injection material is injected into the upper surface of the upper leakage prevention sheet from above to close the damaged portion.