Soil organic pollutant risk management and control multifunctional well and operation method thereof

Abstract

The invention belongs to the technical field of environmental protection, and relates to a multifunctional well for risk management and control of soil organic pollutants and an operation method of the multifunctional well. The multifunctional well comprises a segmented screening well pipe, a filter material layer, a water stop layer and the like, the outer side of the well pipe is filled with the filter material layer and the water stop layer in a segmented surrounding mode according to functional requirements, a soil gas guide pipe, an underground water guide pipe and an online monitoring device are arranged in the well pipe, a volatile organic compound adsorption device is arranged on the upper portion, and an underground hidden wellbay is arranged on the top. The operation method comprises underground water and soil gas monitoring, abnormity early warning and emergency treatment measures. Compared with the prior art, the multifunctional well has the advantages that the multifunctional well is designed in an integrated mode, repeated construction of underground water monitoring wells and other functional wells is reduced, and therefore the number of built wells is reduced, the construction period is shortened, and the investment cost is saved; meanwhile, pollutants, water level and pressure in a multiphase medium can be monitored online for a long time, emergency measures can be taken for abnormal conditions in the blocking structure in time, and the risk of pollution leakage is effectively prevented.

Description

Technical Field

[0001] The present invention belongs to the technical field of environmental protection, and relates to a multifunctional well for soil organic pollutant risk control and an operation method thereof. Background Art

[0002] According to the differences in "pollution source - exposure pathway - receptor", soil and groundwater pollution prevention and control technologies can be divided into remediation technologies for treating pollution sources, risk control technologies for blocking exposure pathways, and institutional control measures for reducing receptor risks. Among them, isolation is a commonly used risk control technology for contaminated soil, which cuts off the exposure pathway of pollutants by adding covers or building vertical or horizontal barriers to achieve the purpose of risk control.

[0003] Different types of barrier control systems can be constructed for different target pollutant types, hydrogeological conditions and on-site environmental conditions. ZL201922479365.8 discloses an in-situ barrier control system for organic contaminated soil, including an underground relatively impermeable layer, organic contaminated soil, a vertical isolation wall and a horizontal barrier layer, which can block pollutants within the in-situ barrier control system. 202111429743.7 discloses a risk control method for volatile organic contaminated sites, which respectively utilizes the low permeability barrier properties of yellow clay, the water-proof and sealing characteristics of two cloths and one membrane, and the air extraction function of the negative pressure air conducting layer to achieve multiple barrier guarantees for volatile organic pollutants in the contaminated area. ZL202110269165.9 discloses a method for calculating the critical thickness of soil covering for soil covering barrier measures, which can provide guidance for the design of horizontal barrier covering.

[0004] Isolation and control measures seal pollutants inside through vertical and horizontal barriers. Pollutants may migrate and diffuse in groundwater, or accumulate in soil gas. It is necessary to regularly monitor the concentration of pollutants in groundwater and soil gas inside the isolation structure to provide data support for the operation and maintenance of isolation measures and effectiveness warning. In addition, when the groundwater and soil gas in the isolation structure are abnormal, or the effectiveness of the isolation measures is reduced, emergency measures need to be taken to prevent the risk of pollution leakage. However, current inventions on isolation and control mainly focus on the improvement of isolation forms and materials, and there is little research on the monitoring and operation management of media inside the isolation structure. Summary of the invention

[0005] The purpose of the present invention is to provide a multifunctional well for soil organic pollutant risk control and an operation method thereof to meet the needs of groundwater and soil gas monitoring, early warning and management of barrier control projects.

[0006] A multifunctional well for soil organic pollutant risk control, comprising a segmented screened well pipe, a filter layer, a water-stop layer, a soil air conduit, a groundwater conduit, a volatile organic compound adsorption device, an online monitoring device, a concealed well platform, etc., characterized in that the outer side of the segmented screened well pipe is segmentedly surrounded and filled with a filter layer and a water-stop layer according to functional needs, the inside of the segmented screened well pipe is provided with a soil air conduit, a groundwater conduit, an online monitoring device, etc., the upper part of the segmented screened well pipe is provided with a volatile organic compound adsorption device, and the top of the segmented screened well pipe is a concealed well platform under the ground.

[0007] Furthermore, the segmented open-screen well pipe is provided with an air-entraining zone open-screen section above the groundwater level to collect soil gas, and a saturated zone open-screen section below the groundwater level to collect groundwater; a sedimentation pipe is provided at the bottom layer with a length of not less than 0.5 m, and the bottom of the sedimentation pipe is sealed with a pipe plug.

[0008] Furthermore, the outer side of the segmented screened well pipe segment is surrounded by a filter material layer, and the upper part of the filter material layer to the wellhead is surrounded by a water stop layer.

[0009] Preferably, the diameter of the segmented screened well pipe should not be less than 110 mm, and the diameter should meet the installation and maintenance requirements of the internal soil air conduit, groundwater conduit, online monitoring device, etc.

[0010] Preferably, the segmented screening well pipe should be selected with appropriate well pipe material according to the type of pollutant. Stainless steel pipes should be used for sites contaminated by high concentrations of chlorinated organic matter. The connections between the well pipes should be fixed by threaded connection, hot melt welding or stainless steel screws, and glue should not be used for bonding.

[0011] Preferably, the screening section of the segmented screening well pipe can be in the form of slits or holes, the ratio of the gap area to the well pipe surface area should not be less than 30%, and it is ensured that the mechanical strength of the well pipe is not affected by the screening.

[0012] Furthermore, the filling height of the filter material layer should be higher than 0.5m above the top of the screening section, and the filling thickness should not be less than 0.1m. The filter material layer should preferably be selected from filter materials with good sphericity and roundness, no pollution, and stable structure. The particle size of the filter material is determined according to the particle size of the target layer soil, and should be greater than the aperture of 90% of the filter holes or the width of the seam, generally with a particle size of 1-2mm.

[0013] Furthermore, the permeability coefficient of the water stop layer should not be greater than 10 -7 cm / s, and materials such as red clay slurry, cement mortar, bentonite, cement-bentonite slurry, etc. can be used.

[0014] Furthermore, the volatile organic compound adsorption device is arranged between the open screening section of the air-entraining zone and the top of the well pipe. The volume has a certain compressibility. The diameter of the device is slightly larger than the diameter of the well pipe. It is pressed down to the supporting ring by extrusion to ensure that soil gas can enter the wellhead area after passing through the adsorption device. A lifting vertical line is installed on the top, and the adsorption device is replaced by lifting the vertical line.

[0015] Preferably, the specific surface area of ​​the adsorption material of the volatile organic compound adsorption device should be greater than 900m 2 / g, the iodine adsorption value should be greater than 1000mg / g, and activated carbon, zeolite, silica gel and other materials can be used.

[0016] Preferably, the support ring is made of hard plastic material, which will not be corroded or loosened in an environment containing polluted soil gas.

[0017] Furthermore, the lower end of the soil gas conduit is arranged in the open screening section of the air-encapsulating zone, and the upper end is connected to the outside of the well pipe through an external interface and a valve. The conduit is divided into two branches, and the sampling ports are respectively located at the upper and lower parts of the volatile organic compound adsorption device. An electric regulating valve is installed on each branch pipe, which can be connected to a vacuum pump after merging into a main pipe. The soil gas can be sent to the online monitoring device by the vacuum pump, and the valve is closed during non-sampling time.

[0018] Preferably, the soil air conduit should be made of corrosion-resistant inert material, and low-density polyvinyl chloride tubes, silicone tubes, and polyethylene tubes should not be used, and the inner diameter of the tube should not be greater than 4 mm.

[0019] Furthermore, the lower end of the groundwater conduit is located in the saturated zone screen section, and the upper end is connected to the outside of the well pipe through an external interface and a valve. The corrosion-resistant inert material should be selected according to the type of groundwater pollutants.

[0020] Furthermore, the online monitoring device can realize online monitoring, data recording, transmission and early warning of the water level, air pressure and pollutant concentration inside the well pipe.

[0021] Furthermore, the height of the concealed well platform should not exceed 0.1m from the ground. The annular gap between the well casing and the well pipe should not be filled with any material. The lower part of the well casing should be buried underground and fixed. The outside of the well casing should be fixed with cement and built into a slope. A manhole cover-type protection device should be used on the top, and a special-shaped safety lock should be installed.

[0022] Preferably, the inner diameter of the well casing should be 250-350 mm and the height should not be greater than 500 mm.

[0023] Another object of the present invention is to provide a method for monitoring, early warning and operation management using the above-mentioned multifunctional well for soil organic pollutant risk control, including: (1) groundwater and soil gas monitoring; (2) monitoring abnormality early warning; (3) emergency disposal measures.

[0024] Furthermore, the groundwater and soil gas monitoring includes the following:

[0025] 1) Groundwater sampling and testing: connect the groundwater external conduit to the groundwater conduit, collect groundwater samples using a water pump, and detect the concentration of pollutants in the groundwater;

[0026] 2) Soil gas sampling and detection: connect the soil gas external conduit to the soil gas conduit, collect soil gas samples using a vacuum pump, and detect the concentration of pollutants in the soil gas;

[0027] 3) Online real-time monitoring: Utilize the online monitoring device built into the multifunctional well to monitor parameters such as water level and air pressure in the well.

[0028] Furthermore, the monitoring abnormality warning includes the following situations:

[0029] 1) Groundwater quality abnormality warning: If the pollutant concentration in the groundwater exceeds the control target value, or the pollutant concentration shows a continuous upward trend during the monitoring process for two consecutive quarters, an early warning will be triggered;

[0030] 2) Abnormal soil gas quality warning: If the concentration of pollutants in the soil gas exceeds the control target value, or the concentration of pollutants shows a continuous upward trend during the monitoring process for two consecutive quarters, an early warning will be triggered;

[0031] 3) Groundwater level abnormal warning: If the groundwater level inside the functional well is higher than the water level outside the control range, or the groundwater level shows a significant upward trend, an early warning will be triggered;

[0032] 4) Abnormal soil gas pressure warning: If the soil gas pressure inside the functional well exceeds 101kPa, an alarm will be triggered.

[0033] Furthermore, the emergency response measures include the following:

[0034] 1) Emergency treatment of abnormal groundwater quality: connect the groundwater external conduit to the groundwater conduit, use a water pump to pump the groundwater to a mobile groundwater treatment device for treatment, or inject chemical oxidants, microbial nutrients, microbial agents, etc. into the groundwater, and continuously observe the treatment effect until the pollutant concentration in the groundwater is lower than the control target value and shows a continuous downward trend during the monitoring process for four consecutive quarters;

[0035] 2) Emergency treatment of abnormal soil gas quality: If the soil gas quality of the upper part of the volatile organic compound adsorption device is abnormal, the adsorption device shall be replaced; if the soil gas quality of the lower part of the volatile organic compound adsorption device is abnormal, the soil gas external conduit shall be connected to the soil gas conduit, and the soil gas shall be extracted to the mobile soil gas treatment device for treatment by using a vacuum pump, and the emergency treatment of abnormal groundwater quality shall be implemented at the same time, until the pollutant concentration in the soil gas is lower than the control target value, and shows a continuous downward trend during the monitoring process for four consecutive quarters;

[0036] 3) Emergency treatment of abnormal groundwater level: First, check and repair the damage of horizontal and vertical barriers; then, connect the groundwater external conduit to the groundwater conduit, and use a pump to pump the groundwater to the ground until the groundwater level inside the functional well is lower than the water level outside the control range;

[0037] 4) Emergency response to abnormal soil gas pressure: First, investigate and analyze the causes of abnormal soil gas pressure. If the abnormal pressure is caused by rising groundwater level, implement the emergency response to abnormal groundwater level. If the abnormal pressure is caused by accumulation of volatile organic matter, implement the emergency response to abnormal soil gas quality until the soil gas pressure inside the functional well returns to normal.

[0038] Compared with the prior art, the present invention has the following beneficial effects:

[0039] This technical solution integrates multiple functions into a multifunctional well, avoiding the duplication of building wells with different functions separately. Within a certain area of ​​control, only a small number of multifunctional wells need to be laid out to meet various monitoring and emergency needs, which significantly reduces the number of wells built compared to traditional methods. The reduction in the number of wells built means a reduction in construction links, thereby shortening the project implementation period, while reducing the material costs of well pipes, filter materials, water-stopping materials, and other materials, as well as construction costs such as construction equipment rental and labor costs. The cost of maintaining and managing multiple wells in the later stage is also reduced accordingly, effectively saving project investment costs.

[0040] The soil gas conduit, groundwater conduit and online monitoring device installed inside the multifunctional well can conduct long-term online monitoring of the accumulation level of pollutants in multiphase media (groundwater and soil gas). Information such as the concentration of pollutants in groundwater and soil gas can be obtained in a timely and accurate manner, providing data basis for a comprehensive understanding of the pollution situation. At the same time, it can also monitor parameters such as the water level and air pressure in the well in real time, which helps to understand the dynamic changes of groundwater and soil gas pressure, and thus provide an important basis for analyzing the effectiveness of barrier measures and the migration laws of groundwater and soil gas.

[0041] Corresponding emergency disposal measures have been formulated for different abnormal situations. When the groundwater quality is abnormal, the groundwater can be pumped out to a mobile groundwater treatment device for treatment, or chemical oxidants, microbial nutrients, microbial agents, etc. can be injected into the groundwater for repair; when the soil gas quality is abnormal, if the soil gas quality of the upper part of the volatile organic adsorption device is abnormal, the adsorption device can be replaced, and if the lower part is abnormal, the soil gas is pumped out to a mobile soil gas treatment device for treatment, and combined with the abnormal groundwater quality disposal measures for coordinated management; when the groundwater level is abnormal, first check and repair the damage of horizontal barriers and vertical barriers, and then pump water to lower the water level; when the soil gas pressure is abnormal, first check and analyze the cause. If it is caused by the increase in groundwater level, combine it with the abnormal groundwater level disposal measures. If it is caused by the accumulation of volatile organic matter, combine it with the abnormal soil gas quality disposal measures for treatment. And in the process of emergency disposal, continue to observe the treatment effect until all indicators return to normal, to ensure that the emergency disposal measures are effective, fundamentally solve the pollution problem, and ensure the safety of the site environment. BRIEF DESCRIPTION OF THE DRAWINGS

[0042] Figure 1 This is a schematic diagram of the structure of a multifunctional well for soil organic pollutant risk control of the present invention;

[0043] Figure 2 This is a schematic diagram of the operation effect of the multifunctional well for soil organic pollutant risk control of the present invention;

[0044] Figure 3 This is a process flow chart of a method for monitoring, early warning and operation management using the multifunctional well for risk control of soil organic pollutants of the present invention;

[0045] Figure 4 Schematic diagram of the installation of a multifunctional well in Example 1 of the present invention;

[0046] Figure 5 Schematic diagram of the installation of the multifunctional well in Example 2 of the present invention.

[0047] In the figure: 1. Segmented screening well pipe; 2. Screening section in the air-entraining zone; 3. Screening section in the saturated zone; 4. Sedimentation tube; 5. Filter material layer; 6. Water-stop layer; 7. Soil gas conduit; 8. Groundwater conduit; 9. Volatile organic compound adsorption device; 10. Support ring; 11. Concealed well platform; 12. Groundwater external conduit; 13. Water pump; 14. Online monitoring device; 15. Mobile groundwater treatment device; 16. Soil gas external conduit; 17. Negative pressure sampling box; 18. Mobile soil gas treatment device; 19. Air pump. DETAILED DESCRIPTION

[0048] The present invention is further described below in conjunction with the accompanying drawings and embodiments. The advantages and features of the present invention will become more apparent from the following description and claims. It should be noted that the drawings are in very simplified form and in non-precise proportions, and are only used to conveniently and clearly assist in explaining the purpose of the embodiments of the present invention.

[0049] Embodiment 1:

[0050] In this embodiment, an organic contaminated site for risk control is selected. The site survey results show that the soil and groundwater pollutants are mainly chlorinated hydrocarbons, DDT, benzene series, and polycyclic aromatic hydrocarbons. The lithology of the submerged aquifer in the plot is mainly silt, silt sand, and silt sand with silt soil, with good permeability and strong water-richness. The bottom plate is a silty clay layer with a certain thickness and stable distribution, which is a good submerged aquifer. The maximum groundwater pollution depth is 40m (reaching the top plate of the submerged aquifer). The existing monitoring wells and emergency disposal wells have single functions and complex operations, which are not conducive to long-term environmental risk control.

[0051] like Figure 1 and Figure 2 As shown, a multifunctional well for soil organic pollutant risk control provided according to the present embodiment includes a segmented screen well pipe 1, a filter layer 5, a water stop layer 6, a soil air conduit 7, a groundwater conduit 8, a volatile organic compound adsorption device 9, an online monitoring device 14, a concealed well platform 11, etc., characterized in that: the outer side of the segmented screen well pipe 1 is segmentedly surrounded and filled with a filter layer 5 and a water stop layer 7 according to functional needs, the segmented screen well pipe 1 is provided with a soil air conduit 7, a groundwater conduit 8, an online monitoring device 14, etc., the upper part of the segmented screen well pipe 1 is provided with a volatile organic compound adsorption device 9, and the top of the segmented screen well pipe 1 is a concealed well platform 11 under the ground. It is applied and implemented by the following method:

[0052] (1) Within a range of 4000m 2 Survey and lay out within the control range to determine the location of the multifunctional wells, and use drilling rigs to carry out the construction of the multifunctional wells. A total of 10 multifunctional wells were laid out, with a depth of 40m and a spacing of 30m between wells.

[0053] (2) The segmented screened well pipe 1 is made of stainless steel pipe, and the connection between the well pipes is threaded, with a diameter of 110 mm, which meets the installation and maintenance requirements of the internal soil air conduit, groundwater conduit, online monitoring device, etc.

[0054] (3) The outer side of the screening section of the segmented well pipe 1 is surrounded by a filter material layer 5, and the upper part of the filter material layer 5 to the wellhead is surrounded by a water stop layer 6. An air-entraining zone screening section 2 is set above the groundwater level to collect soil gas, and a saturated zone screening section 3 is set below the groundwater level to collect groundwater. A sedimentation pipe 4 is set at the bottom layer. The length of the sedimentation pipe 4 is not less than 0.5m, and the bottom is sealed with a pipe plug. The screening section of the segmented well pipe adopts a slit form, and the gap area accounts for 50% of the surface area of ​​the well pipe, and it is ensured that the mechanical strength of the well pipe is not affected by the screening.

[0055] (4) The filling height of the filter material layer 5 is 0.6m above the top of the screen section, and the filling thickness is 0.2m. The filter material layer 5 is made of quartz sand with a particle size of 1-2mm. The permeability coefficient of the water stop layer 6 is less than 10 -7 cm / s, cement-bentonite slurry was used as water-stopping material.

[0056] (5) The volatile organic compound adsorption device 9 is arranged between the open screen section 2 of the air-encapsulating zone and the top of the well pipe. The diameter of the device is slightly larger than the diameter of the well pipe and is pressed down to the support ring 10 by extrusion. The support ring 10 is made of hard plastic material and will not be corroded or loosened in an environment containing polluted soil gas. The specific surface area of ​​the internal adsorption material is 1000m 2 / g, the iodine adsorption value is 1200mg / g, and activated carbon is used as the adsorption material.

[0057] (6) The lower end of the soil gas conduit 7 is arranged at the open screen section 2 of the air encapsulation zone, and the upper end is connected to the outside of the well pipe through an external interface and a valve. The conduit is divided into two branches, and the sampling ports are respectively located at the upper and lower parts of the volatile organic adsorption device 9. An electric regulating valve is installed on each branch. After merging into a main pipe, it can be connected to a vacuum pump. The soil gas can be sent to the online monitoring device 14 by the vacuum pump. The valve is closed during non-sampling time. The soil gas conduit 7 is made of corrosion-resistant inert material, and the inner diameter of the pipe is 3 mm.

[0058] (7) The lower end of the groundwater conduit 8 is located in the saturated zone screen section 3, and the upper end is connected to the outside of the well pipe through an external interface and a valve. A stainless steel pipe is selected as the groundwater conduit 8 according to the type of groundwater pollutants.

[0059] (8) The online monitoring device can realize online monitoring, data recording, transmission and early warning of the water level, air pressure and pollutant concentration inside the well pipe.

[0060] (9) The height of the concealed well platform 11 is flush with the ground. The annular space between the well casing and the well pipe is not filled with any material. The lower part of the well casing is buried underground and fixed. The outside of the well casing is fixed with cement and built into a slope. A manhole cover type protection device is used on the top, and a special-shaped safety lock is installed.

[0061] (10) The monitoring functions of the multifunctional well include the following: 1) Groundwater sampling and detection: connect the groundwater external conduit 12 to the groundwater conduit 8, use the water pump 13 to collect groundwater samples, and detect the concentration of pollutants in the groundwater; 2) Soil gas sampling and detection: connect the soil gas external conduit 16 to the soil gas conduit 7, use the water pump 19 to collect soil gas samples, and detect the concentration of pollutants in the soil gas; 3) Online real-time monitoring: use the online monitoring device built into the multifunctional well to monitor parameters such as the water level and air pressure in the well.

[0062] (11) The multifunctional well operates stably and continuously monitors multiple indicators within the scope of risk control to reduce the risk of leakage of polluted groundwater.

[0063] Embodiment 2:

[0064] In Example 1, the multifunctional well is used for long-term monitoring. Example 2 of the present invention provides a method for monitoring, early warning and operation management using the multifunctional well for risk control of soil organic pollutants, such as Figure 3 , Figure 4 and Figure 3 As shown, the implementation is applied by the following method:

[0065] (1) During the long-term monitoring process using the multifunctional well, the concentration of pollutants in groundwater and the concentration of pollutants in the soil gas below the volatile organic compound adsorption device 9 showed a continuous upward trend during the monitoring process for two consecutive quarters, triggering an abnormal warning of groundwater quality and an abnormal warning of soil gas quality. According to the abnormal warning situation, emergency measures for abnormal groundwater quality and abnormal soil gas quality are taken respectively.

[0066] (2) Emergency treatment of abnormal groundwater quality: connect the groundwater external conduit 12 to the groundwater conduit 8, use the pump 13 to pump the groundwater to the mobile groundwater treatment device 15 for treatment, inject chemical oxidants into the groundwater at the same time, and continuously observe the treatment effect until the pollutant concentration in the groundwater is lower than the control target value and shows a continuous downward trend during the four consecutive quarters of monitoring;

[0067] (3) Emergency treatment of abnormal soil gas quality: connect the soil gas external conduit 16 to the soil gas conduit 7, use the vacuum pump 19 to extract the soil gas to the mobile soil gas treatment device 18 for treatment, and at the same time combine the implementation of the emergency treatment of abnormal groundwater quality until the pollutant concentration in the soil gas is lower than the control target value and shows a continuous downward trend during the four consecutive quarters of monitoring.

[0068] (4) The multifunctional well conducts long-term online monitoring of the accumulation level of pollutants in groundwater and soil gas, groundwater level, and wellhead pressure. When an abnormal warning occurs, emergency measures can be taken in time to prevent the risk of pollution leakage.

[0069] The above description is only a description of the preferred embodiments of the present invention, and is not intended to limit the scope of the present invention. Any changes or modifications made by a person skilled in the art in the field of the present invention based on the above disclosure shall fall within the scope of protection of the claims.

Claims

1. A multifunctional well for soil organic pollutant risk control, comprising a segmented screen well pipe (1), a filter material layer (5), a water stop layer (6), a soil air conduit (7), a groundwater conduit (8), a volatile organic compound adsorption device (9), an online monitoring device (14), and a concealed well platform (11), characterized in that: The outer side of the segmented screened well pipe (1) is surrounded and filled with a filter material layer (5) and a water stop layer (6) in segments according to functional requirements; the interior of the segmented screened well pipe (1) is provided with a soil air conduit (7), a groundwater conduit (8), and an online monitoring device (14); the upper part of the segmented screened well pipe (1) is provided with a volatile organic matter adsorption device (9); and the top of the segmented screened well pipe (1) is a concealed well platform (11) under the ground.

2. The multifunctional well for soil organic pollutant risk management according to claim 1, characterized in that: The segmented open-screen well pipe (1) is provided with an air-encapsulating zone open-screen section (2) above the groundwater level to collect soil gas, and a saturated zone open-screen section (3) below the groundwater level to collect groundwater, and a sedimentation pipe (4) is provided at the bottom layer, and the bottom of the sedimentation pipe is sealed with a pipe plug; The outer side of the screening section of the segmented screening well pipe (1) is surrounded by a filter material layer (5), and the upper part of the filter material layer (5) to the wellhead is surrounded by a water stop layer (6); the segmented screening well pipe (1) selects a suitable well pipe material according to the type of pollutants, and stainless steel pipes are used for sites contaminated by high concentrations of chlorinated organic matter. The well pipes are connected by threaded connection, hot-melt welding or stainless steel screws; the screening section of the segmented screening well pipe (1) is in the form of slits or holes, and the gap area accounts for no less than 30% of the well pipe surface area.

3. The multifunctional well for soil organic pollutant risk management according to claim 1, characterized in that: The volatile organic compound adsorption device (9) is arranged between the open screen section (2) of the air-encapsulating zone and the top of the well pipe, has a certain degree of compressibility, and the diameter of the device is larger than the diameter of the well pipe. It is pressed down to the supporting ring (10) by extrusion to ensure that soil gas can enter the wellhead area after passing through the adsorption device (9). A lifting vertical line is installed on the top, and the adsorption device (9) is replaced by lifting the vertical line.

4. The multifunctional well for soil organic pollutant risk management according to claim 1, characterized in that: The lower end of the soil gas conduit (7) is arranged at the open screening section (2) of the air encapsulation zone, and the upper end is connected to the outside of the well pipe through an external interface and a valve. The conduit is divided into a plurality of branch pipes, and the sampling ports are respectively located at the upper and lower parts of the volatile organic compound adsorption device (9). An electric regulating valve is installed on each branch pipe, and after merging into a main pipe, a vacuum pump (19) can be connected. The soil gas can be sent to the online monitoring device (14) by the vacuum pump (19), and the valve is closed during non-sampling time; the soil gas conduit (7) is made of corrosion-resistant inert material.

5. The multifunctional well for soil organic pollutant risk management according to claim 1, characterized in that: The lower end of the groundwater conduit (8) is located in the saturated zone screen section (3), and the upper end is connected to the outside of the well pipe through an external interface and a valve. A corrosion-resistant inert material is selected according to the type of groundwater pollutants.

6. The multifunctional well for soil organic pollutant risk management according to claim 1, characterized in that: The online monitoring device (14) is used to realize online monitoring, data recording, transmission and early warning of the water level, air pressure and pollutant concentration inside the well pipe.

7. The multifunctional well for soil organic pollutant risk management according to claim 1, characterized in that: The height of the concealed well platform (11) does not exceed a certain height above the ground. The annular space between the well casing and the well pipe is not filled with any material. The lower part of the well casing is buried underground and fixed. The outside of the well casing is fixed with cement and built into a soil slope. The top adopts a well cover type protection device and is equipped with a special-shaped safety lock.

8. A method for operating a multifunctional well for soil organic pollutant risk management, characterized in that: Multifunctional wells are used for monitoring, early warning, and operation management, including: (1) groundwater and soil gas monitoring; (2) monitoring abnormality early warning; and (3) emergency response measures.

9. The method for operating a multifunctional well for soil organic pollutant risk control according to claim 8, characterized in that: The groundwater and soil gas monitoring includes the following: 1) Groundwater sampling and testing: connect the groundwater external conduit to the groundwater conduit, collect groundwater samples using a pump, and test the concentration of pollutants in the groundwater; 2) Soil gas sampling and detection: connect the soil gas external conduit to the soil gas conduit, collect soil gas samples using a vacuum pump, and detect the concentration of pollutants in the soil gas; 3) Online real-time monitoring: using the online monitoring device built into the multifunctional well to monitor the water level and air pressure parameters in the well.

10. The method for operating a multifunctional well for soil organic pollutant risk control according to claim 8, characterized in that: The monitoring abnormality warning includes the following situations: 1) Groundwater quality abnormality warning: If the pollutant concentration in the groundwater exceeds the control target value, or the pollutant concentration shows a continuous upward trend during the monitoring process for two consecutive quarters, an early warning will be triggered; 2) Abnormal soil gas quality warning: If the concentration of pollutants in the soil gas exceeds the control target value, or the concentration of pollutants shows a continuous upward trend during two consecutive quarters of monitoring, an early warning will be triggered; 3) Groundwater level abnormal warning: If the groundwater level inside the functional well is higher than the water level outside the control range, or the groundwater level shows a significant upward trend, an early warning will be triggered; 4) Abnormal soil gas pressure warning: If the soil gas pressure inside the functional well exceeds 101kPa, an alarm will be triggered.

11. The method for operating a multifunctional well for soil organic pollutant risk control according to claim 8, characterized in that: The emergency response measures include the following: 1) Emergency treatment of abnormal groundwater quality: connect the groundwater external conduit to the groundwater conduit, use a water pump to pump the groundwater to a mobile groundwater treatment device for treatment, or inject chemical oxidants, microbial nutrients, and microbial agents into the groundwater, and continuously observe the treatment effect until the pollutant concentration in the groundwater is lower than the control target value and shows a continuous downward trend during the monitoring process for four consecutive quarters; 2) Emergency treatment of abnormal soil gas quality: If the soil gas quality above the volatile organic compound adsorption device is abnormal, replace the adsorption device; If the soil gas quality at the bottom of the volatile organic compound adsorption device is abnormal, the soil gas external conduit is connected to the soil gas conduit, and the soil gas is extracted by a vacuum pump to the mobile soil gas treatment device for treatment, and at the same time, the emergency treatment of groundwater quality abnormality is implemented until the pollutant concentration in the soil gas is lower than the control target value and shows a continuous downward trend during the monitoring process for four consecutive quarters; 3) Emergency treatment of abnormal groundwater level: First, check and repair the damage of horizontal and vertical barriers; then, connect the groundwater external conduit to the groundwater conduit, and use a pump to pump the groundwater to the ground until the groundwater level inside the functional well is lower than the water level outside the control range; 4) Emergency response to abnormal soil gas pressure: First, investigate and analyze the causes of abnormal soil gas pressure. If the abnormal pressure is caused by rising groundwater level, implement the emergency response to abnormal groundwater level. If the abnormal pressure is caused by accumulation of volatile organic matter, implement the emergency response to abnormal soil gas quality until the soil gas pressure inside the functional well returns to normal.

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