Method for monitoring water level of layered leachate of refuse landfill

Abstract

The invention relates to the field of safety monitoring of refuse landfills, and provides a layered leachate water level monitoring method. The method comprises the following steps: firstly, determining the position, the thickness and the number of soil covering layers in the middle of the landfill through exploration drill holes, and then burying monitoring holes in a garbage heap body under each soil covering layer to realize layering. After it is confirmed that hole sealing is dense and the water level is stable through one-week observation, the steel ruler water level gauge is adopted for measuring the leachate water level of each monitoring hole. The distance from the water level surface to the pipe orifice is determined by repeatedly monitoring for three times and averaging, and the water level elevation is obtained by leveling. The water level change value is obtained by comparing the water level elevations measured twice, and the accumulated variable quantity is obtained by comparing with the first measurement. The method can be used for intuitively, quickly and accurately measuring the water level of the leachate on each layer of covering soil, analyzing the occurrence form and continuity of the leachate and evaluating the stability of a garbage heap.

Description

Technical Field

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

[0002] At present, with the rapid advancement of economic and urbanization construction, people's quality of life has been significantly improved, but at the same time, the output of urban domestic waste has also increased sharply. For these wastes, my country mainly relies on sanitary landfills for treatment. However, the leachate produced by the degradation of garbage during the landfill process is a kind of wastewater with a high pollution concentration, and the water level, continuity and occurrence state of the leachate have an important influence on the stability of the garbage pile. Therefore, accurately assessing the leachate water level in different soil layers is crucial to ensure the stability of the garbage pile.

[0003] The traditional leachate level monitoring method is relatively direct and does not adopt the method of soil layer layer monitoring, which leads to significant limitations. Specifically, the traditional method cannot accurately measure the leachate level on each layer of covering soil. Due to the low permeability of the middle covering soil layer, water stagnation may occur in the middle covering soil layer, which may lead to the formation of an independent water level on each layer of covering soil, resulting in discontinuity of leachate in the vertical direction. Therefore, the traditional method cannot effectively determine the occurrence form of leachate in the landfill and the continuity of the leachate water level, which will seriously restrict the accurate assessment of the stability of the garbage pile in the 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: A method for monitoring the water level of stratified leachate in a landfill comprises the following steps: S1. First, conduct a survey and drilling sampling of the landfill site, and determine the number of layers of the garbage pile and the location and quantity of the intermediate covering soil layer based on the drilling depth and core sample description; S2. Determine the depth and number of several monitoring holes according to the conditions of the intermediate covering soil layer measured in S1, and ensure that the depth of each monitoring hole reaches each layer of garbage pile on the upper side of each intermediate covering soil layer; S3. A water level monitoring pipe is buried inside the monitoring hole. A bottom cover is fixed at the lower end of the monitoring pipe, and an openable and closable top cover 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 lowest layer of the garbage pile. The gap between the monitoring pipe with holes and the monitoring hole is filled with coarse sand, and the gap between the remaining part and the monitoring hole is filled with expanded soil balls. S4. Observe whether there is any subsidence in the gap between the monitoring hole and the monitoring tube, and 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 and the monitoring tube with expanded soil balls and add water; S5. Open the top cover of the monitoring pipe 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 less than 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 ruler water level gauge at the pipe mouth of the monitoring pipe, repeat the monitoring three times with the steel ruler water level gauge, take the average value of the three monitoring results as the distance h from the leachate water level surface to the pipe mouth of the water level pipe, take a known ground elevation and use leveling to measure the pipe mouth elevation H of the monitoring pipe, the water level elevation is Hh, measure the depth 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.

[0006] 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 with a number of 2m solid tubes through a joint to form the monitoring tube.

[0007] As a further preferred solution, the distance between the monitoring hole and the nearest intermediate covering soil layer above it exceeds 3m.

[0008] As a further preferred solution, the spacing between the monitoring holes is less than or equal to 2m.

[0009] As a further preferred solution, the distance between the top cover and the ground surface is 1 m.

[0010] The beneficial effects of the present invention include: 1. The distance between the monitoring hole and the nearest layer of middle covering 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 middle covering soil, so as to accurately measure the leachate water level.

[0011] 2. The spacing between monitoring holes shall not exceed 2 m, which can ensure the continuity of leachate water level measurement.

[0012] 3. The leachate level is measured in each soil layer, which can accurately measure the leachate 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 level of each covering soil layer of the landfill is continuously and accurately monitored, and the leachate storage form and water level continuity are effectively analyzed, which provides a reliable basis for judging the stability of the garbage pile and significantly improves the management efficiency and safety of the landfill. BRIEF DESCRIPTION OF THE DRAWINGS

[0013] Figure 1It is a schematic diagram of water pipes in each soil layer of the present invention.

[0014] They include: 1. Top cover; 2. Ground surface; 3. Monitoring hole; 4. Garbage dump; 5. Middle covering soil layer; 6. Joint; 7. Bentonite ball; 8. Solid pipe; 9. Flower pipe; 10. Coarse sand; 11. Bottom cover. DETAILED DESCRIPTION

[0015] In order to make the purpose and technical solution of the present invention clearly and completely described, and the advantages more clearly understood, the embodiments of the present invention are further described in detail 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, rather than all of the embodiments, and are only used to explain the embodiments of the present invention, and are not used to limit the embodiments of the present invention. All other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0016] like Figure 1 As shown, a method for monitoring the water level of stratified leachate in a landfill comprises the following steps: S1. First, drilling is performed on the landfill site to determine the location, thickness and quantity of the middle overburden layer 5 according to the drilling depth, drill rod length and core sample description.

[0017] S2, according to the condition of the intermediate covering soil layer 5 measured in S1, determine the depth and number of several monitoring holes 3, and ensure that a monitoring hole 3 is buried in the garbage pile 4 on the upper side of each intermediate covering soil layer 5; Specifically, the spacing between the monitoring holes 3 is less than or equal to 2 m in order to ensure the continuity of measuring the leachate water level.

[0018] S3. A water level monitoring pipe is buried inside the monitoring hole 3. A bottom cover 11 is fixed at the lower end of the monitoring pipe. An openable and closable top cover 1 is provided at the upper end of the monitoring pipe. The distance between the top cover 1 and the ground surface 2 is 1m. The lower end of the monitoring pipe has holes, and the holes on the monitoring pipe are all immersed in each layer of garbage pile 5. The gap between the monitoring pipe without holes and the monitoring hole 3 is filled with expanded soil balls 7, and the gap between the monitoring pipe with holes and the monitoring hole 3 is filled with coarse sand 10. Specifically, if the pipe is too long, the production difficulty will increase, the cost will increase, it will be difficult for workers on site to operate, and it will be easy to break when put into the hole; if the pipe is too short, the number of pipe joints will increase, so 2m is more appropriate. The part with holes at the lower end of the monitoring pipe is a 2m flower pipe 9, which is connected to several 2m solid pipes 8 through joints 6 to form a monitoring pipe; Specifically, the flower tube 9 is filled with coarse sand 10 because the water level needs to be monitored through the flower tube 9, and the coarse sand 10 has strong permeability, so water can flow into the tube through the coarse sand 10; Specifically, the gap between the non-hole portion of the monitoring pipe and the monitoring hole 3 is filled with an expansion ball 7, which is used to plug the hole to prevent leakage of groundwater or other substances. The expansion ball 7 has strong hygroscopicity and expansion properties, can absorb a large amount of water and expand in volume to form a gel and suspension, forming a stable plugging material; 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 flower pipe is between the two intermediate covering soil layers 5, thereby ensuring the accuracy of measuring the leachate water level.

[0019] S4. Observe whether there is any subsidence in the gap between the monitoring hole 3 and the monitoring tube, and 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.

[0020] S5. Open the top cover 1 of the monitoring pipe 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 value fluctuates less than or equal to 20 cm above and below a certain fixed value, and then start formal measurement; Specifically, the water level change is observed for one week to prevent the measured water level change from being unstable due to different soil permeability.

[0021] S6. During the formal measurement, read the reading R of the steel ruler water level gauge at the mouth of monitoring hole 3, repeat the monitoring three times with the steel ruler 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, use the leveling measurement to measure the mouth elevation H of the monitoring pipe, the water level elevation is Hh, and measure in order from shallow to deep according to the buried depth of the monitoring pipe. The difference between each measurement result and the first measurement result is the cumulative change in water level. By observing the numerical values, the occurrence form of leachate and the continuity of leachate water level are analyzed, so as to judge the stability of the garbage dump.

[0022] Although 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 the embodiments without departing from the principles and spirit of the present invention, and that the scope of the present 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, and the number of layers of the garbage pile (5) and the location and amount of the intermediate covering soil layer (5) are determined based on the drilling depth and core sample description; S2, determining the depth and number of the plurality of monitoring holes (3) according to the conditions of the intermediate covering soil layer (5) measured in S1, and 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, burying a water level monitoring pipe inside the monitoring hole (3), wherein a bottom cover (11) is fixed at 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, wherein the lower end of the monitoring pipe has holes, and the holes on the monitoring pipe are all located in the garbage pile (5) at the bottom layer, and 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, and 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 (1) of the monitoring pipe every day for one week, lower the probe of the water level gauge, read the reading of the 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; S6. During the formal measurement, read the reading R of the steel ruler water level gauge at the pipe mouth of the monitoring pipe, repeat the monitoring three times with the steel ruler water level gauge, take the average value of the three monitoring results as the distance h from the leachate water level surface to the pipe mouth of the water level pipe, take a known ground elevation and use leveling to measure the pipe mouth elevation H of the monitoring pipe, the water level elevation is Hh, measure the depth 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. A method for monitoring the water level of stratified leachate in a landfill according to claim 1, characterized in that: The portion with holes at the lower end of the monitoring tube is a 2 m flower tube (9), and the flower tube (9) is connected to a plurality of 2 m solid tubes (8) via a joint (6) to form a monitoring tube.

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

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

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

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