A method for monitoring the water level of layered leachate in a landfill site

Abstract

The present application relates to the field of safety monitoring of waste landfill, and proposes a layered leachate water level monitoring method. The method first determines the position, thickness and number of the middle soil layer in the landfill through exploration drilling, and then embeds monitoring holes in the garbage pile under each soil layer to realize layering. After a week of observation to confirm the sealing and water level stability, the steel ruler water level meter is used to measure the leachate water level of each monitoring hole. The distance from the water level surface to the pipe opening is determined by taking the average value of three repeated measurements, and the water level elevation is obtained by combining the leveling measurement. By comparing the water level elevations measured twice, the water level change value is obtained, and the cumulative change value is obtained by comparing with the first measurement. The method can intuitively, quickly and accurately measure the leachate water level on each layer of soil, analyze the occurrence form and continuity of leachate, and evaluate the stability of the garbage pile.

Description

Technical Field

[0001] The invention belongs to the field of landfill safety monitoring, and in particular relates to a method for monitoring the water level of stratified leachate in a landfill. Background Art

[0002] With the rapid development of the economy and urbanization, people's quality of life has significantly improved. However, this has also led to a sharp increase in the amount of municipal solid waste produced. my country primarily relies on sanitary landfills to dispose of this waste. However, the leachate produced by the degradation of waste during the landfill process is a highly pollutant wastewater. The leachate's water level, continuity, and distribution have a significant impact on the stability of the landfill. Therefore, accurately assessing the leachate level in different soil layers is crucial to ensuring the stability of the landfill.

[0003] Traditional leachate level monitoring methods are relatively direct and do not employ a stratified soil layer monitoring approach, which results in significant limitations. Specifically, traditional methods are unable to accurately measure the leachate level on each layer of cover soil. Due to the low permeability of the intermediate cover soil layer, water stagnation may occur in the intermediate cover soil layer, which in turn may result in an independent water level forming on each layer of cover soil, causing the leachate to be discontinuous in the vertical direction. Therefore, traditional methods are unable to effectively determine the distribution form of leachate within the landfill and the continuity of the leachate level, which will seriously restrict the accurate assessment of the stability of the garbage pile at a later stage. Summary of the Invention

[0004] The present invention provides a method for monitoring the water level of stratified leachate in a landfill, which has the characteristics of high accuracy, strong adaptability, and easy operation, and aims to solve the problems existing in the above-mentioned background technology.

[0005] To achieve the above object, the present invention provides the following technical solutions:

[0006] A method for monitoring the water level of stratified leachate in a landfill comprises the following steps:

[0007] S1. First, conduct a survey and drilling sampling of the landfill site. Based on the drilling depth and core sample description, the number of layers of the garbage pile and the location and amount of the intermediate overburden layer are determined;

[0008] S2. Determine the depth and number of monitoring holes based on the conditions of the intermediate cover soil layer measured in S1, ensuring that the depth of each monitoring hole reaches each layer of garbage pile on the upper side of each intermediate cover soil layer;

[0009] S3. Bury a water level monitoring tube inside the monitoring hole. A bottom cover is fixed to the lower end of the monitoring tube, and an openable and closable top cover is installed at the upper end of the monitoring tube. The lower end of the monitoring tube has holes, and the holes are all located in the lowest layer of the garbage pile. The gap between the monitoring tube with holes and the monitoring hole is filled with coarse sand, and the gap between the remaining part of the monitoring tube and the monitoring hole is filled with expanded soil balls.

[0010] S4. Observe the gap between the monitoring hole and the monitoring tube for any subsidence. Shake the monitoring tube to see if it shakes. If there is any subsidence or shaking, continue filling the gap between the monitoring hole and the monitoring tube with expanded soil balls and adding water.

[0011] S5. Open the top cover of the monitoring pipe every day for one week, lower the probe of the steel water level gauge, read the reading of the steel water level gauge, and test the leachate water level in different soil layers until the leachate water level fluctuates within or equal to 20 cm above or below a certain fixed value, then start formal measurement;

[0012] S6. During the formal measurement, read the reading R of the steel tape water level gauge at the mouth of the monitoring pipe. Repeat the monitoring three times using the steel tape water level gauge. Take the average value of the three monitoring results as the distance h from the leachate water level surface to the mouth of the water level pipe. Take a known ground elevation and use leveling to measure the mouth elevation H of the monitoring pipe. The water level elevation is Hh. Measure the depths of each monitoring pipe from shallow to deep. The difference between each measurement result and the water level measurement result in the shallowest monitoring pipe is the cumulative change in water level.

[0013] As a further preferred solution, the portion with holes at the lower end of the monitoring tube is a 2m flower tube, and the flower tube is connected to several 2m solid tubes through a joint to form the monitoring tube.

[0014] As a further preferred solution, the distance between the monitoring hole and the nearest intermediate covering layer above it is more than 3m.

[0015] As a further preferred solution, the spacing between the monitoring holes is less than or equal to 2m.

[0016] As a further preferred solution, the distance between the top cover and the ground surface is 1 m.

[0017] The beneficial effects of the present invention include:

[0018] 1. The distance between the monitoring hole and the nearest layer of soil above it must be more than 3 m, which can ensure that the entire section of the flower pipe is between the two layers of soil, so as to accurately measure the leachate water level.

[0019] 2. The spacing between monitoring holes shall not exceed 2 m, which can ensure the continuity of leachate water level measurement.

[0020] 3. The leachate water level is measured in each layer of soil, which can accurately measure the leachate water level on each layer of covering soil. Through detailed exploration drilling and monitoring hole setting, combined with the precise burial and reading of water level monitoring pipes, the leachate water level of each covering soil layer of the landfill is continuously and accurately monitored, effectively analyzing the leachate distribution form and water level continuity, providing a reliable basis for judging the stability of the garbage pile, and significantly improving the management efficiency and safety of the landfill. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 Schematic diagram of water pipes in each soil layer of the present invention.

[0022] Among them are: 1. Top cover; 2. Ground surface; 3. Monitoring hole; 4. Garbage dump; 5. Middle covering layer; 6. Joint; 7. Expanded soil ball; 8. Solid pipe; 9. Flower pipe; 10. Coarse sand; 11. Bottom cover. DETAILED DESCRIPTION

[0023] In order to clearly and completely describe the objectives and technical solutions of the present invention and make the advantages more clearly understood, the embodiments of the present invention are further described in detail below with reference to the accompanying drawings. It should be understood that the specific embodiments described herein are part of the embodiments of the present invention, not all of them, and are only used to explain the embodiments of the present invention, not to limit the embodiments of the present invention. All other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of the present invention.

[0024] like Figure 1 As shown, a method for monitoring the water level of stratified leachate in a landfill comprises the following steps:

[0025] S1. First, a survey drilling is carried out on the landfill site. The position, thickness and quantity of the intermediate cover soil layer 5 are ascertained based on the drilling depth, drill rod length and core sample description of each drilling.

[0026] S2. Determine the depth and number of monitoring holes 3 based on the condition of the intermediate covering layer 5 measured in S1, ensuring that a monitoring hole 3 is buried in the garbage pile 4 on the upper side of each intermediate covering layer 5;

[0027] Specifically, the spacing between the monitoring holes 3 is less than or equal to 2 m in order to ensure the continuity of the leachate water level measurement.

[0028] S3. Bury a water level monitoring pipe inside monitoring hole 3. A bottom cover 11 is fixed to the lower end of the monitoring pipe, and an openable and closable top cover 1 is installed at the upper end of the monitoring pipe. The distance between top cover 1 and the ground surface 2 is 1 meter. The lower end of the monitoring pipe has holes, and the holes on the monitoring pipe are all submerged in each layer of the garbage pile 5. The gap between the non-hole portion of the monitoring pipe and the monitoring hole 3 is filled with expanded soil balls 7, and the gap between the hole portion of the monitoring pipe and the monitoring hole 3 is filled with coarse sand 10.

[0029] Specifically, if the pipe is too long, production becomes more difficult, costs increase, and it becomes difficult for workers on site to operate. It can also easily break when inserted into the hole. If the pipe is too short, the number of pipe joints increases. Therefore, 2 meters is a more suitable length. The portion with holes at the lower end of the monitoring pipe is a 2-meter flower pipe 9. This flower pipe 9 is connected to several 2-meter solid pipes 8 via joints 6 to form the monitoring pipe.

[0030] Specifically, the flower tube 9 is filled with coarse sand 10 because the water level needs to be monitored through the flower tube 9. The coarse sand 10 has strong permeability, and water can flow through the coarse sand 10 into the tube.

[0031] Specifically, the gap between the non-hole portion of the monitoring pipe and the monitoring hole 3 is filled with expanding soil balls 7. The expanding soil balls 7 are used to plug the holes and prevent the leakage of groundwater or other substances. They have strong hygroscopicity and expansion properties, and can absorb a large amount of water and expand in volume to form a gel and suspension, forming a stable plugging material.

[0032] Specifically, the distance between the monitoring hole and the nearest intermediate covering soil layer 5 is more than 3 m, in order to ensure that the entire section of the floral pipe is between the two intermediate covering soil layers 5, thereby ensuring the accuracy of measuring the leachate water level.

[0033] S4. Observe whether there is any subsidence in the gap between the monitoring hole 3 and the monitoring tube, shake the monitoring tube to observe whether it shakes. If there is any subsidence or shaking, continue to fill the gap between the monitoring hole 3 and the monitoring tube with expanded soil balls 7 and add water.

[0034] S5. Open the monitoring pipe cover 1 every day for one week, lower the probe of the steel ruler water level gauge, read the reading of the steel ruler water level gauge, and test the leachate water level in different soil layers until the leachate water level fluctuates within or equal to 20 cm above or below a certain fixed value, and then start formal measurement;

[0035] Specifically, the water level change is observed for one week to prevent the measured water level change from being unstable due to different permeability of the soil layers.

[0036] S6. During the formal measurement, read the steel tape water level gauge reading R at the mouth of monitoring hole 3. Repeat the measurement three times using the steel tape water level gauge. The average of these three monitoring results is taken as the distance h from the leachate water level surface to the mouth of the water level pipe. Use leveling to measure the monitoring pipe mouth elevation H. The water level elevation is Hh. Measurements are made sequentially, starting from the shallowest to the deepest buried depth of the monitoring pipe. The difference between each measurement result and the initial measurement is the cumulative change in water level. By observing these values, the distribution pattern of leachate and the continuity of the leachate water level are analyzed, thereby determining the stability of the landfill.

[0037] While embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that various changes, modifications, substitutions, and variations may be made to these embodiments without departing from the principles and spirit of the invention, and that the scope of the invention is defined by the appended claims and their equivalents.

Claims

1. A method for monitoring the water level of stratified leachate in a landfill, characterized in that: The following steps are involved: S1. First, the landfill is surveyed and drilled to sample the landfill. Based on the drilling depth and core sample description, the number of layers of the garbage pile (4) and the location and amount of the intermediate cover soil layer (5) are determined; S2, determining the depth and number of several monitoring holes (3) based on the conditions of the intermediate covering soil layer (5) measured in S1, ensuring that the depth of each monitoring hole (3) reaches each layer of garbage pile (4) on the upper side of each intermediate covering soil layer (5); S3. A water level monitoring pipe is buried inside the monitoring hole (3). A bottom cover (11) is fixed to the lower end of the monitoring pipe, and an openable and closable top cover (1) is provided at the upper end of the monitoring pipe. The lower end of the monitoring pipe has holes, and the holes on the monitoring pipe are all located in the garbage pile (4) at the bottom. The gap between the monitoring pipe with holes and the monitoring hole (3) is filled with coarse sand (10), and the gap between the remaining part of the monitoring pipe and the monitoring hole (3) is filled with expanded soil balls (7); S4. Observe whether there is any subsidence in the gap between the monitoring hole (3) and the monitoring tube, shake the monitoring tube to observe whether it shakes, if there is any subsidence or shaking, continue to fill the gap between the monitoring hole (3) and the monitoring tube with expanded soil balls (7) and add water; S5. Open the top cover of the monitoring pipe (1) every day for one week, lower the probe of the steel ruler water level gauge, read the reading of the steel ruler water level gauge, and test the leachate water level of different soil layers until the leachate water level fluctuates within or equal to 20 cm above or below a certain fixed value, and then start formal measurement; S6. During the formal measurement, read the reading R of the steel tape water level gauge at the mouth of the monitoring pipe. Repeat the monitoring three times using the steel tape water level gauge. Take the average value of the three monitoring results as the distance h from the leachate water level surface to the mouth of the water level pipe. Take a known ground elevation and use leveling to measure the mouth elevation H of the monitoring pipe. The water level elevation is Hh. Measure the depths of each monitoring pipe from shallow to deep. The difference between each measurement result and the water level measurement result in the shallowest monitoring pipe is the cumulative change in water level.

2. The method for monitoring the water level of stratified leachate in a landfill according to claim 1, wherein: The portion with holes at the lower end of the monitoring tube is a 2m flower tube (9), and the flower tube (9) is connected to a plurality of 2m solid tubes (8) via a joint (6) to form the monitoring tube.

3. The method for monitoring the water level of stratified leachate in a landfill according to claim 2, wherein: The distance between the monitoring hole and the nearest intermediate covering soil layer (5) above it exceeds 3m.

4. The method for monitoring the water level of stratified leachate in a landfill according to claim 1, wherein: The spacing between the monitoring holes (3) is less than or equal to 2m.

5. The method for monitoring the water level of stratified leachate in a landfill according to claim 1, wherein: The distance between the top cover (1) and the ground surface (2) is 1 m.

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