Polluted soil ectopic risk management and control system and risk management and control method thereof

Abstract

The invention discloses a polluted soil ectopic risk management and control system and a risk management and control method thereof. The system comprises a concrete anti-seepage structure used for containing polluted soil, a rainwater guide and drainage ditch, an underground drainage ditch, a wastewater emergency treatment system and an underground water monitoring well. The risk management and control method comprises the following steps: cleaning and digging the original polluted soil of the polluted site, transferring the polluted soil to the risk control site, and carrying out sealing treatment on the polluted soil by building the system. According to the system, pollutants in the polluted soil can be prevented from being diffused, and the purpose of risk management and control is achieved; the system is high in efficiency and low in cost, and can be used as a new technical means for contaminated soil ectopic risk management and control.

Description

Technical Field

[0001] The present invention relates to the technical field of risk control in contaminated soil remediation, and particularly to a system for off-site risk control of contaminated soil and its risk control method. Background Art

[0002] Due to the relatively low cost of risk control technology, it has been used more frequently in soil remediation projects in recent years. In projects using risk control technology, in-situ risk control is generally adopted at present. However, for some remediation plots that need to be used as first-class land, in-situ risk control is not applicable. In this case, a suitable plot planned as second-class land can be selected near the remediation plot for off-site risk control. However, there are currently technical defects in off-site risk control in contaminated soil remediation, such as easy occurrence of secondary pollution, environmental and health risks of second-class land, problems in controlling construction costs in second-class land, and problems in controlling construction efficiency and cycle of off-site risk control. Summary of the Invention

[0003] In view of the above technical defects, the purpose of the present invention is to provide a system for off-site risk control of contaminated soil and its risk control method to provide new ideas for off-site risk control technology and achieve the purpose of off-site risk control. The purpose of the present invention is achieved through the following technical solutions: A system for off-site risk control of contaminated soil, the system includes a concrete anti-seepage structure for accommodating contaminated soil, a rainwater drainage ditch, an underground drainage ditch, a waste water emergency treatment system, and a groundwater monitoring well; The concrete anti-seepage structure adopts a reinforced concrete structure. The concrete anti-seepage structure is a ground structure or includes both an underground structure and a ground structure. The walls around the ground part of the concrete anti-seepage structure are of a slope structure; after the contaminated soil is filled into the concrete anti-seepage structure, an HDPE geomembrane is covered on it; The rainwater drainage ditch is located above the HDPE geomembrane on the upper part of the concrete anti-seepage structure and on the slope of the wall, and all the rainwater drainage ditches are connected to each other and finally connected to the urban drainage system; The water inlet of the underground drainage ditch is located at the bottom end inside the concrete anti-seepage structure, and the water outlet of the underground drainage ditch is connected to the waste water emergency system; The waste water emergency system includes a regulating pool for storing the sewage flowing out of the underground drainage ditch, a temporary sewage treatment station connected to the water outlet of the regulating pool, and a clear water pool connected to the water outlet of the temporary sewage treatment station. The water outlet of the clear water pool is connected to the urban drainage system; The groundwater monitoring well is arranged on the outer periphery of the concrete anti-seepage structure for regularly monitoring the surrounding water quality.

[0004] For further optimization, real-time water quality monitoring devices are installed in both the regulating tank and the clean water tank of the emergency wastewater treatment system, and the real-time water quality monitoring devices are connected to the PCL control system.

[0005] Furthermore, a circulation pipeline is provided between the clean water tank and the temporary sewage treatment station, and a two-way control valve is installed on the circulation pipeline to control the drainage from the temporary sewage treatment station to the clean water tank and the water in the clean water tank to flow back to the sewage treatment station for secondary treatment.

[0006] A method for off-site risk control of contaminated soil, using the described system, includes the following steps: Step 1: Determine the original contaminated site and the risk control sites around the original site. Step 2: Excavate and repair the contaminated soil at the original contaminated site and transport the contaminated soil. Step 3: Construction and risk control of the risk control sites: S31: Support the foundation pit and drain water in the risk control area. S32: Construct the bottom of the concrete anti-seepage structure and build the underground drainage ditch, the emergency wastewater treatment system and the surrounding groundwater monitoring wells. S33: Place the contaminated soil transported from the original contaminated site at the bottom of the concrete anti-seepage structure, add medicine and stir for stabilization treatment or degrade the pollutants. S34: After passing the self-inspection of the medicine addition treatment, carry out landfilling; the landfilling operation starts from the bottom of the concrete anti-seepage structure, evenly spreads the soil material and compacts it layer by layer from bottom to top, and build the walls around the concrete anti-seepage structure while carrying out the landfilling operation, and the construction of the walls is carried out synchronously with the landfilling operation. S35: After the landfilling is completed, cover the upper surface of the contaminated soil heap with a layer of clean clay not less than 50 cm and compact it, and then lay a layer of HDPE geomembrane. S36: Build a rainwater drainage ditch to divert the rainfall blocked by the HDPE geomembrane to the regulating tank of the emergency wastewater treatment system. S37: Monitoring and treatment inside the concrete anti-seepage structure: If the real-time water quality monitoring device in the regulating tank shows that the water quality is qualified, it can be directly discharged; if not, it will be treated by the temporary sewage treatment station; if the real-time water quality monitoring device in the clean water tank shows that the water quality is qualified, it can be directly discharged; if not, it will be treated by the temporary sewage treatment station again. S38: Monitoring and treatment outside the concrete anti-seepage structure: Regularly detect the groundwater around the concrete anti-seepage structure through the groundwater monitoring wells, and check the anti-seepage of the concrete anti-seepage structure if the monitoring results are unqualified.

[0007] Among them, the contaminated soil is organic contaminated soil, heavy metal contaminated soil or a mixture of organic matter and heavy metals contaminated soil.

[0008] For further optimization, the specific operations in Step 2 include: S21 Carry out foundation pit support and dewatering at the original site of the contaminated site; S22 Excavate the contaminated soil at the original site of the contaminated site and transport the excavated contaminated soil to the risk control site; S23 Treat the contaminated groundwater, foundation pit dewatering and construction wastewater at the original site of the contaminated site; S24 Self-inspection of the effect of the excavated contaminated soil at the original site.

[0009] For further optimization, in S34, the heavily contaminated soil is preferentially landfilled at the bottom of the concrete anti-seepage structure to reduce the precipitation of pollutants caused by rainfall scouring.

[0010] Furthermore, the underground drainage ditch described in S32 is a hidden ditch composed of a perforated pipe wrapped with a sand and gravel filtering material. A concrete pipe foundation should be laid at the lower part of the ditch, and the pipe should be covered with gravel around.

[0011] Furthermore, in S35, after the surface HDPE geomembrane is laid, a layer of clean clay with a thickness of not less than 50 cm is covered on the surface to form a double anti-seepage layer and serve as a buffer layer for the growth of later landscape vegetation.

[0012] The advantages and beneficial effects of the present invention are: The system of the present invention can prevent the spread of pollutants in the contaminated soil and achieve the purpose of risk control; and the system has high efficiency and low cost, and can be used as a common system for the off-site risk control technology of contaminated soil.

[0013] For some remediation plots that need to be used as first-class land, conventional risk control is not applicable. Using the system and method of the present invention, the remediation purpose can be achieved. The risk control method of the present invention adopts a comprehensive strategy of source removal and engineering barrier control for remediation and risk control, with low cost, high control efficiency, can effectively control each key pollution link during construction, effectively control secondary pollution prevention, and minimize the environmental and health risks during construction. BRIEF DESCRIPTION OF THE DRAWINGS

[0014] The present invention will be further described below with reference to the drawings and embodiments.

[0015] Figure 1 It is a schematic diagram of the overall planar structural contour of the concrete anti-seepage structure in Embodiment 1; Figure 2 It is a schematic diagram of the partial planar structure of the concrete anti-seepage structure in Embodiment 1; Figure 3 It is a schematic diagram of the sectional structure of the concrete anti-seepage structure in Embodiment 1; Figure 4Schematic structural diagram of the underground drainage ditch in Embodiment 3; Figure 5 Schematic connection diagram of the underground drainage ditch in Embodiment 1; Figure 6 Schematic connection diagram of the flow deflector in Embodiment 1.

[0016] Reference numerals: 1. Concrete anti-seepage structure; 2. Rainwater drainage ditch; 3. Underground drainage ditch; 3-1, Cushion; 3-2, Groove; 3-3, Inner lining; 3-4, Cover plate; 3-5, Non-woven fabric; 3-6, Flow deflector; 3-7, Check valve; 3-8, Drainage hole; 3-9, Piston plate; 3-10, Crankshaft; 3-11, Reducer; 3-12, Connecting rod; 4. Wastewater emergency treatment system; 5. Groundwater monitoring well; 4-1, Regulation tank; 4-2, Temporary sewage treatment station; 6. Polluted soil; 7. HDPE. Detailed implementation manners

[0017] Embodiment 1: A system for off-site risk control of polluted soil, as Figure 1 , 2 shown, the system includes a concrete anti-seepage structure 1 for accommodating polluted soil, a rainwater drainage ditch 2, an underground drainage ditch 3, a wastewater emergency treatment system 4 and a groundwater monitoring well 5. The anti-seepage structure 1 is an integral closed-loop structure.

[0018] The concrete anti-seepage structure 1 adopts a reinforced concrete structure. The concrete anti-seepage structure 1 is a ground structure or includes both underground and ground structures. As Figure 3 shown, the walls around the ground part of the concrete anti-seepage structure 1 are slope structures; after the polluted soil 6 is filled into the concrete anti-seepage structure 1, an HDPE 7 geotextile anti-seepage membrane is covered.

[0019] The rainwater drainage ditch 2 is located above the HDPE geotextile anti-seepage membrane on the upper part of the concrete anti-seepage structure 1 and on the slope of the wall, with a slope not greater than 25%, and all the rainwater drainage ditches 2 are interconnected and finally connected to the urban drainage system.

[0020] The water inlet of the underground drainage ditch 3 is located at the inner bottom end of the concrete anti-seepage structure 1, and the water outlet of the underground drainage ditch 3 is connected to the wastewater emergency system 4.

[0021] The wastewater emergency system 4 includes an adjustment tank 4-1 for storing the sewage flowing out of the underground drainage ditch, a connection to the water outlet of the adjustment tank, and a clear water tank connected to the water outlet of the temporary sewage treatment station 4-2. The water outlet of the clear water tank is connected to the urban drainage system. Water quality real-time monitoring devices are installed in both the adjustment tank 4-1 and the clear water tank of the wastewater emergency system 4, and the water quality real-time monitoring devices are connected to the PCL control system. A circulation pipeline is provided between the clear water tank and the temporary sewage treatment station 4-2, and a two-way control valve is installed on the circulation pipeline to control the drainage of the temporary sewage treatment station to the clear water tank and the return of the water in the clear water tank to the sewage treatment station for secondary treatment.

[0022] The groundwater monitoring well 5 is arranged outside the perimeter of the concrete impervious structure 1 for regularly monitoring the surrounding water quality.

[0023] Embodiment 2 A method for risk control and management of contaminated soil remediation, using the described system, includes the following steps: Step 1: Determine the original contaminated site and the risk control and management sites around the original site. Step 2: Excavation and remediation of contaminated soil at the original contaminated site and transportation of contaminated soil: S21: Carry out foundation pit support and dewatering at the original contaminated site. S22: Excavate the contaminated soil at the original contaminated site and transport the excavated contaminated soil to the risk control and management site. S23: Treat the contaminated groundwater, foundation pit dewatering and construction wastewater at the original contaminated site. S24: Self-inspection of the effect of excavating contaminated soil at the original site.

[0024] Step 3: Construction and risk control and management of the risk control and management site: S31: Carry out foundation pit support and dewatering in the risk control area.

[0025] S32: Carry out the construction of the bottom of the concrete impervious structure 1 and the construction of the underground drainage ditch 3, the wastewater emergency treatment system 4 and the surrounding groundwater monitoring well 5. The underground drainage ditch 3 is a concealed ditch composed of a perforated pipe wrapped with sand and gravel filter materials. A concrete pipe foundation should be laid at the lower part of the pipe trench, and the pipeline should be covered with gravel around.

[0026] S33: Place the contaminated soil transported from the original contaminated site at the bottom of the concrete impervious structure 1, add medicine and stir for stabilization treatment or degrade the pollutants; the contaminated soil is heavy metal (copper, lead, zinc) contaminated soil. By adding medicine, the toxic heavy metals in the soil are wrapped up to form a relatively stable form, restricting the release of soil heavy metals to the environment. The addition ratio is controlled between 1% and 2%. Direct mixing is carried out in the concrete impervious structure using an ALLU bucket.

[0027] After adding medicine and stirring for mixing in S34, the treated soil is cured. After standing for 12 hours, a spot check is carried out. After passing the self-inspection, landfill is carried out; the landfill operation starts from the bottom of the concrete anti-seepage structure 1, and the soil materials are evenly spread and compacted in horizontal layers from bottom to top. And while carrying out the landfill operation, the walls around the concrete anti-seepage structure 1 are built, and the construction of the walls is carried out synchronously with the landfill operation. To ensure the stability of the landfill body, the landfill slope should not be greater than 25%. The heavily polluted soil is preferentially landfilled at the bottom of the concrete anti-seepage structure to reduce the precipitation of pollutants caused by rainfall scouring.

[0028] After the landfill in S35 is completed, a layer of clean clay not less than 50 cm thick is covered on the surface of the polluted soil heap and compacted, and then a layer of HDPE geomembrane is laid. After the laying of the surface HDPE geomembrane is completed, a layer of clean clay not less than 50 cm thick is covered on the surface, forming a double anti-seepage layer and serving as a buffer layer for the growth of later landscape vegetation.

[0029] In S36, a rainwater drainage ditch 2 is built to divert the rainfall blocked by the HDPE geomembrane to the regulating pond of the wastewater emergency system 4.

[0030] Monitoring and treatment inside the concrete anti-seepage structure 1 in S37: If the water quality real-time monitoring equipment in the regulating pond shows that the water quality is qualified, it can be directly discharged; if it is unqualified, it will be treated through the temporary sewage treatment station; if the water quality real-time monitoring equipment in the clear water pond shows that the water quality is qualified, it can be directly discharged; if it is unqualified, it will be treated through the temporary sewage treatment station again.

[0031] Monitoring and treatment outside the concrete anti-seepage structure 1 in S38: The groundwater around the concrete anti-seepage structure 1 is regularly detected through the groundwater monitoring well 5. If the monitoring result is unqualified, the anti-seepage of the concrete anti-seepage structure 1 will be inspected.

[0032] Example 3: A system for off-site risk control of polluted soil, as Figure 4 、 Figure 5 shown, the underground drainage ditch 3 includes a cushion layer 3-1, a trench 3-2, a lining 3-3 and a cover plate 3-4. The trench 3-2 is arranged on the cushion layer 3-1 with an open upper end. The lining 3-3 is arranged on the inner wall and bottom wall of the trench 3-2. The cover plate 3-4 is embedded in the upper end of the trench 3-2 in a hollow shape. There are two layers of cover plates 3-4, and a non-woven fabric 3-5 is laid between the two layers of cover plates 3-4.

[0033] As Figure 5 、 Figure 6As shown in the figure, a flow guide cover 3-6 is arranged in the groove 3-2 along its length direction. The flow guide cover 3-6 is buckled and fixed to the lower end surface of the cover plate 3-4, and there are gaps between the two sides of the flow guide cover 3-6 and the two sides of the inner lining 3-3. A plurality of one-way valves 3-7 are arranged at intervals on the upper side wall of the flow guide cover 3-6. The one-way valves 3-7 only allow outward exhaust, and a drain hole 3-8 is arranged through the lower side wall of the flow guide cover 3-6.

[0034] As Figure 6 shown, a piston plate 3-9 is horizontally arranged in the flow guide cover 3-6. The piston plate 3-9 is vertically slidably connected to the flow guide cover 3-6. A crankshaft 3-10 is horizontally rotatably connected to the lower end of the flow guide cover 3-6. A waterproof speed reducer 3-11 is arranged at the end of the crankshaft 3-10. A plurality of connecting rods 3-12 are rotatably connected to the crankshaft 3-10, and the upper end of each connecting rod 3-12 is rotatably connected to the lower end surface of the piston plate 3-9.

[0035] Therefore, when the underground drain 3 works, the piston plate 3-9 is located at the lowermost end of the flow guide cover 3-6 and below the drain hole 3-8. At this time, a part of the wastewater inside the concrete impervious structure 1 is directly discharged into the underground drain 3 along both sides of the cover plate 3-4, and another part enters the flow guide cover 3-6 along the cover plate 3-4 and then is discharged into the underground drain 3 through the drain hole 3-8 after being collected.

[0036] When it is necessary to accelerate the external discharge efficiency of the wastewater inside the concrete impervious structure 1, the speed reducer 3-11 can be started. The speed reducer 3-11 drives the crankshaft 3-10 to rotate, and under the combined action of the crankshaft 3-10 and the connecting rods 3-12, the piston plate 3-9 is controlled to move up and down reciprocally.

[0037] When the piston plate 3-9 moves downward, the one-way valves 3-7 are in a closed state. At this time, a negative pressure is formed inside the flow guide cover 3-6, and the wastewater inside the concrete impervious structure 1 is pressurized and sucked into the flow guide cover 3-6. When the piston plate 3-9 moves to below the drain opening, the pressure inside the flow guide cover 3-6 is relieved, and the wastewater is discharged outward along the drain hole 3-8.

[0038] When the piston plate 3-9 moves downward and reaches a position above the drain hole 3-8, a positive pressure is generated inside the flow guide cover 3-6, and the one-way valves 3-7 are controlled to automatically turn over and open, so that the piston plate 3-9 can smoothly slide upward without causing pressure on the internal air of the concrete impervious structure 1.

[0039] Then, it reciprocates in turn to realize the intermittent pressurized suction of the wastewater inside the concrete impervious structure 1, improve the external discharge efficiency of the wastewater, and facilitate the centralized and rapid unified treatment of the wastewater.

[0040] Finally, it should be noted that the above is only used to illustrate the technical solution of the present invention and not to limit it. Although the present invention has been described in detail with reference to the preferred arrangement, those of ordinary skill in the art should understand that the technical solution of the present invention can be modified or equivalently replaced without departing from the spirit and scope of the technical solution of the present invention.

Claims

1. A system for off-site risk control of contaminated soil, characterized in that: The system includes a concrete anti-seepage structure (1) for containing contaminated soil, a rainwater drainage ditch (2), an underground drainage ditch (3), a wastewater emergency treatment system (4), and a groundwater monitoring well (5); The concrete anti-seepage structure (1) adopts a reinforced concrete structure. The concrete anti-seepage structure (1) is a ground structure or includes both underground and ground structures. The walls around the ground part of the concrete anti-seepage structure (1) are of a slope structure; after the contaminated soil is filled into the concrete anti-seepage structure (1), an HDPE geomembrane is overlaid; The rainwater drainage ditch (2) is located above the HDPE geomembrane on the upper part of the concrete anti-seepage structure (1) and on the slope of the wall, and all the rainwater drainage ditches (2) are interconnected and finally connected to the urban drainage system; The inlet of the underground drainage ditch (3) is located at the inner bottom end of the concrete anti-seepage structure (1), and the outlet of the underground drainage ditch (3) is connected to the wastewater emergency system (4); The wastewater emergency system (4) includes a regulating tank for storing the sewage flowing out of the underground drainage ditch, a temporary sewage treatment station connected to the outlet of the regulating tank, and a clear water tank connected to the outlet of the temporary sewage treatment station. The water outlet of the clear water tank is connected to the urban drainage system; The groundwater monitoring well (5) is arranged outside the perimeter of the concrete anti-seepage structure (1) for regularly monitoring the surrounding water quality.

2. The system for off-site risk control of contaminated soil according to claim 1, wherein: Water quality real-time monitoring devices are arranged in both the regulating tank and the clear water tank of the wastewater emergency system (4), and the water quality real-time monitoring devices are connected to the PCL control system.

3. The system for off-site risk control of contaminated soil according to claim 2, wherein: A circulation pipeline is arranged between the clear water tank and the temporary sewage treatment station, and a two-way control valve is arranged on the circulation pipeline to control the drainage of the temporary sewage treatment station to the clear water tank and the water in the clear water tank to flow back to the sewage treatment station for secondary treatment.

4. A method for off-site risk control of contaminated soil, which uses the system described in any one of claims 1 to 3, characterized in that, It includes the following steps: Step 1: Determine the original site of the contaminated site and the risk control sites around the original site; Step 2: Excavate and repair the contaminated soil at the original site of the contaminated site and transport the contaminated soil; Step 3: Construction and risk control of the risk control sites: S31 Support the foundation pit and dewater in the risk control area; S32 Construct the bottom of the concrete anti-seepage structure (1) and construct the underground drainage ditch (3), the wastewater emergency treatment system (4), and the surrounding groundwater monitoring well (5); S33 Place the contaminated soil transported from the original site of the contaminated site at the bottom of the concrete anti-seepage structure (1), add medicine and stir for stabilization treatment or degrade the pollutants; After the self-inspection of the medicine addition treatment is qualified, carry out landfilling; the landfilling operation starts from the bottom of the concrete anti-seepage structure (1), and the soil materials are evenly spread and compacted in horizontal layers from bottom to top. And while carrying out the landfilling operation, construct the walls around the concrete anti-seepage structure (1), and the construction of the walls is carried out synchronously with the landfilling operation; After the landfilling is completed, cover a layer of clean clay with a thickness of not less than 50 cm on the surface of the contaminated soil pile and compact it, and then lay an HDPE geomembrane; Construct the rainwater drainage ditch (2) to divert the rainfall blocked by the HDPE geomembrane into the regulating tank of the wastewater emergency system (4); Monitoring and treatment inside the S37 concrete anti-seepage structure (1): If the real-time water quality monitoring equipment in the regulation pond shows that the water quality is qualified, it can be directly discharged; if not, it will be treated through the temporary sewage treatment station; if the real-time water quality monitoring equipment in the clean water pond shows that the water quality is qualified, it can be directly discharged; if not, it will be treated again through the temporary sewage treatment station. Monitoring and treatment outside the S38 concrete anti-seepage structure (1): Regularly detect the groundwater around the concrete anti-seepage structure (1) through the groundwater monitoring well (5). If the monitoring result is unqualified, check the anti-seepage of the concrete anti-seepage structure (1).

5. The off-site risk control method for contaminated soil according to claim 4, characterized in that: The polluted soil is organic polluted soil, heavy metal polluted soil or a mixture of organic matter and heavy metals.

6. A method for off-site risk control of polluted soil according to claim 4, characterized in that: The specific operations in step two include: S21 Carry out foundation pit support and dewatering at the original site of the polluted site. S22 Excavate the polluted soil at the original site of the polluted site and transport the excavated polluted soil to the risk control site. S23 Treat the polluted groundwater, foundation pit dewatering and construction wastewater at the original site of the polluted site. S24 Self-inspection of the effect of excavating the original site polluted soil.

7. A method for off-site risk control of polluted soil according to claim 4, characterized in that: In S34, give priority to landfilling heavily polluted soil at the bottom of the concrete anti-seepage structure to reduce the precipitation of pollutants caused by rainfall erosion.

8. A method for risk control of polluted soil remediation according to claim 4, characterized in that: The underground drainage ditch (3) in S32 is a hidden ditch composed of a perforated pipe wrapped with sand and gravel filter material. A concrete pipe foundation should be laid at the lower part of the ditch, and the pipeline should be covered with gravel around.

9. A method for risk control of polluted soil remediation according to claim 4, characterized in that: In S35, after the surface HDPE geomembrane is laid, a layer of clean clay with a thickness of not less than 50 cm should be covered on the surface to form a double anti-seepage layer and serve as a buffer layer for the growth of later landscape vegetation.

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