Construction method of injection well for repairing polluted soil and underground water

Abstract

The invention discloses a construction method of an injection well for repairing polluted soil and underground water, and relates to the technical field of polluted soil and underground water repairing, and the construction method comprises the following steps: step 1, determining site hydrogeological conditions and a repairing depth range: finding out site parameters such as a stratigraphic structure of the position of the injection well and the repairing depth range; according to the construction method of the injection well for repairing the polluted soil and the underground water, the provided construction scheme of the injection well for in-situ injection and chemical oxidation is simple in construction procedure, and the process of injecting chemicals by adopting the injection well is safe and efficient. According to the design of the injection well, the combination of ozone and hydrogen peroxide in an in-situ chemical oxidation technology is realized, the two medicaments are simultaneously injected into a remediation horizon in the same injection well through different pipelines, and the ozone and the hydrogen peroxide react underground (the remediation horizon) to generate hydroxyl free radicals with higher oxidability, so that the remediation horizon can be restored. And reacting with pollutants in soil and underground water within the range of the remediation position to achieve the purpose of removing the pollutants.

Description

Technical Field

[0001] The invention relates to the technical field of contaminated soil and groundwater restoration, and in particular to a method for constructing an injection well for restoring contaminated soil and groundwater. Background Art

[0002] In-situ chemical oxidation remediation technology refers to the injection of oxidants into contaminated soil in solid, liquid or gaseous form. The oxidants diffuse and cover the contaminated area under the action of groundwater flow, infiltration, gravity or buoyancy, and then come into contact with the pollutants and oxidize and destroy the pollutants to achieve the purpose of remediation. The successful and effective application of in-situ chemical oxidation remediation technology depends on three basic requirements: first, there must be a strong and effective oxidant that reacts with the target compound; the contact between the target pollutant and the oxidant must be guaranteed; finally, a sufficient amount of oxidant must be delivered to the target remediation area and the duration must meet the time requirements for effective reaction required for pollutant remediation.

[0003] The oxidants available for in-situ chemical oxidation remediation technology include permanganate, hydrogen peroxide, Fenton's reagent, persulfate and ozone. In past project practices, the oxidant used in most projects that adopted chemical oxidation technology in the field of contaminated soil and groundwater remediation was sodium persulfate. As an oxidant, sodium persulfate has the advantages of safety, stable properties, convenient operation and good oxidation effect. However, in recent years, with the continuous increase in the price of chemical reagents, the price of sodium persulfate has remained high, resulting in the continuous increase in the cost of using oxidation technology to remediate contaminated soil and groundwater, and even restricting the practical feasibility of using sodium persulfate as an oxidant for oxidation remediation technology.

[0004] Therefore, other more practical oxidants are urgently needed in the field of soil remediation. As an oxidant, ozone has the advantages of strong oxidizing property, fast reaction, small dosage, easy on-site preparation, no secondary pollution, and low cost. However, ozone is a gas with poor controllability and explosion hazard. It is rarely used in in-situ injection chemical oxidation remediation technology, and even rarely used in the field of contaminated soil and groundwater remediation.

[0005] In addition, the practice of advanced oxidation technology has shown that the combination of ozone and hydrogen peroxide can generate more oxidative hydroxyl radicals, which can more efficiently degrade pollutants.

[0006] In summary, in the field of contaminated soil and groundwater remediation technology, it is urgent to overcome the technical barriers to the practical application of ozone and realize the application of ozone, a high-quality oxidant, in the field of in-situ injection chemical oxidation remediation technology. By proposing an innovative design for the injection well construction plan, strengthening the combined use of ozone and hydrogen peroxide, and achieving more convenient, safer, more controllable and more efficient in-situ injection of ozone and hydrogen peroxide, it provides an innovative and optimized solution for the in-situ chemical oxidation remediation technology of the site. Summary of the invention

[0007] The present invention provides a method for repairing contaminated soil and constructing a groundwater injection well to solve the problems raised in the above background technology.

[0008] In order to solve the above technical problems, the technical solution adopted by the present invention is:

[0009] A method for remediating contaminated soil and constructing a groundwater injection well comprises the following steps:

[0010] Step 1: Determine the site hydrogeological conditions and remediation depth range: Find out the site parameters such as the stratigraphic structure of the injection well location and the remediation depth range;

[0011] Step 2: Drilling construction: Use Φ400 drilling tools to drill holes to the depth of the target layer for repair and drill holes;

[0012] Step 3: Well pipe connection: The injection well pipe includes a hard PVC pipe with a specification of DN110 and a 304 stainless steel pipe with a specification of DN60. The bottom of the pipe is sealed with a PVC well bottom seal and a 304 steel well bottom seal respectively. The hard PVC pipe and the 304 stainless steel pipe are firmly fixed with a different diameter double pipe clamp;

[0013] Step 4: Lower the well pipe: Lower the pre-connected well pipe into the borehole. During the lowering process, continue to connect the well pipe according to the previous step until the well pipe is lowered to the bottom of the well pipe, leaving the surface 0.5-1.0m above the ground, and keep the hard PVC pipe and 304 stainless steel pipe at the same height;

[0014] Step 5: Filling and water-stopping: fill the gaps between the hard PVC screen tube and the 304 steel open-hole aeration tube and the borehole wall with quartz sand filter material, fill the gaps between the hard PVC solid tube and the 304 steel solid tube and the borehole wall with shrinkage-compensating fine stone concrete water-stopping from 1m below the surface to the surface, and fill the rest of the area with bentonite water-stopping; after the concrete reaches the required strength, the injection well is completed;

[0015] Step 6: Wash the well: Pump water repeatedly to wash the well until the water is clear and the sand is gone;

[0016] Step 7: Well platform construction: A concrete well platform is set up on the ground. The hard PVC pipe and 304 stainless steel pipe are connected to the hydrogen peroxide solution injection quick connector and the ozone injection quick connector respectively. The injection well construction is completed.

[0017] Preferably, in step one: clarify the remediation tasks, provide a construction plan, and identify whether it is applicable to the remediation of contaminated soil and groundwater on the site.

[0018] Preferably, in step three: the length of the ground pipeline connection should not be too long, and the length should be convenient for pipe lowering operation.

[0019] Preferably, in step 4: a hard PVC screen tube and a 304 steel open-hole aeration tube are set in the repair depth section, and the remaining sections are hard PVC solid tubes and 304 steel solid tubes.

[0020] Preferably, the construction plan of the in-situ injection well can realize the simultaneous injection of ozone and hydrogen peroxide in one injection well using a 304 stainless steel pipe and a hard PVC pipe respectively. The two agents are safely and efficiently mixed underground, reacting with the target pollutants to degrade the pollutants, thereby achieving the purpose of repairing contaminated soil and groundwater.

[0021] Preferably, the structure of the in-situ injection well mainly includes hard PVC solid pipe, hard PVC screen pipe, 304 steel solid pipe, 304 steel open-hole aeration pipe, quartz sand filter material, bentonite water stop, shrinkage compensating fine stone concrete, PVC well bottom seal, 304 steel well bottom seal, hydrogen peroxide solution injection quick connector, ozone injection quick connector, and concrete platform.

[0022] Preferably, the hard PVC pipe and the 304 stainless steel pipe in the injection well structure are firmly fixed with a different-diameter double pipe clamp, and the bottom of the well is sealed with a PVC bottom seal and a 304 steel bottom seal respectively.

[0023] Preferably, the injection well construction plan adopts bentonite and shrinkage-compensating fine stone concrete. The combination of the two materials stops water and seals the injection well. A concrete well platform is constructed on the surface to enhance the sealing effect, and precise repair is achieved for the target repair layer, ensuring the safety and efficiency of the injection process of the injection well.

[0024] Due to the adoption of the above technical solution, the present invention has the following technical advances compared with the prior art:

[0025] 1. The present invention provides a method for constructing an injection well for repairing contaminated soil and groundwater, and provides a construction scheme for an in-situ injection chemical oxidation injection well. The construction process is simple, and the injection well is safe and efficient for injecting agents. The design of the injection well realizes the combined use of ozone and hydrogen peroxide in the in-situ chemical oxidation technology. The two agents are injected into the repair layer at the same time through different pipelines in the same injection well. Ozone and hydrogen peroxide react underground (repair layer) to generate more oxidizing hydroxyl radicals, which react with pollutants in the soil and groundwater within the repair layer to achieve the purpose of removing pollutants.

[0026] 2. The present invention provides a method for constructing injection wells for repairing contaminated soil and groundwater. The innovative design of the injection well construction plan overcomes technical barriers such as poor controllability and explosion hazards of ozone in practical applications, and realizes a more efficient application of ozone, a high-quality oxidant, in the field of in-situ injection chemical oxidation remediation technology, providing an innovative and optimized solution for in-situ chemical oxidation remediation technology for contaminated soil and groundwater.

[0027] 3. The present invention provides a method for constructing an injection well for repairing contaminated soil and groundwater. Through the innovative design of the in-situ injection chemical oxidation repair injection well construction plan, an injection well is used to simultaneously inject ozone and hydrogen peroxide using a 304 stainless steel pipe and a hard PVC pipe respectively. The two agents are safely and efficiently mixed underground, react with the target pollutants, degrade the pollutants, and achieve the purpose of repairing contaminated soil and groundwater. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] Figure 1 It is a schematic diagram of the process flow of the present invention;

[0029] Figure 2 It is a schematic diagram of the injection well structure of the present invention;

[0030] Figure 3 The present invention is a schematic diagram of an in-situ ozone and hydrogen peroxide injection system for a specific implementation of the present invention.

[0031] In the figure: 1. Hydrogen peroxide solution injection quick connector; 2. PVC solid pipe; 3. Bentonite; 4. PVC screen tube; 5. Quartz sand filter material; 6. PVC bottom seal; 7. Ozone injection quick connector; 8. Concrete platform; 9. Shrinkage-compensating fine stone concrete; 10. 304 steel solid pipe; 11. Different diameter double pipe clamp; 12. 304 steel open-hole aeration pipe; 13. Drill hole wall; 14. 304 steel bottom seal; 15. Hardened ground; 16. Surface non-polluted layer; 17. Groundwater level; 18. Repair layer; 19. Waterproof bottom plate. DETAILED DESCRIPTION

[0032] In order to make the technical means, creative features, objectives and effects achieved by the present invention easy to understand, the present invention is further explained below in conjunction with specific implementation methods.

[0033] like Figure 1-Figure 3 As shown, a method for remediating contaminated soil and constructing a groundwater injection well comprises the following steps:

[0034] Step 1: Determine the site hydrogeological conditions and remediation depth range: Identify site parameters such as the stratigraphic structure of the injection well location and the remediation depth range; clarify the remediation tasks, provide a construction plan, and identify whether it is applicable to the remediation of contaminated soil and groundwater within the site.

[0035] Step 2: Drilling construction: Use Φ400 drilling tools to drill holes to the depth of the target layer for repair and drill holes;

[0036] Step 3: Well pipe connection: The injection well pipe includes a hard PVC pipe with a specification of DN110 and a 304 stainless steel pipe with a specification of DN60. The bottom of the pipe is sealed with a PVC well bottom seal and a 304 steel well bottom seal respectively. The hard PVC pipe and the 304 stainless steel pipe are firmly fixed with a different diameter double pipe clamp; the length of the ground pipeline connection is 3m; the length of the ground pipeline connection should not be too long, and the length should be convenient for the pipe lowering operation.

[0037] Step 4: Lowering the pipe: Lower the pre-connected well pipe into the borehole. During the lowering process, continue to extend the well pipe according to the previous step until the well pipe is lowered to the bottom of the well pipe, leaving the surface 0.5-1.0m above the ground, and keep the hard PVC pipe and 304 stainless steel pipe at the same height; set a hard PVC screen pipe and a 304 steel open-hole aeration pipe at the repair depth section, and the remaining sections are hard PVC solid pipes and 304 steel solid pipes.

[0038] Step 5: Filling and water-stopping: fill the gaps between the hard PVC screen tube and the 304 steel open-hole aeration tube and the borehole wall with quartz sand filter material, fill the gaps between the hard PVC solid tube and the 304 steel solid tube and the borehole wall with shrinkage-compensating fine stone concrete water-stopping from 1m below the surface to the surface, and fill the rest of the area with bentonite water-stopping; after the concrete reaches the required strength, the injection well is completed;

[0039] Step 6: Wash the well: Pump water repeatedly to wash the well until the water is clear and the sand is gone;

[0040] Waterstopping is the most critical process in the construction of injection wells: a combination of bentonite and shrinkage-compensating fine stone concrete is used to stop water and seal the injection wells. A concrete well platform is built on the surface to strengthen the sealing effect. Accurate repair is achieved for the target repair layer to ensure the safety and efficiency of the injection process of the injection well. The locations of concrete filling and bentonite filling should meet the design requirements, and well washing should be carried out after the concrete has solidified.

[0041] Step 7: Well platform construction: A concrete well platform is set up on the ground. The hard PVC pipe and 304 stainless steel pipe are connected to the hydrogen peroxide solution injection quick connector and the ozone injection quick connector respectively. The injection well construction is completed.

[0042] After the construction of all the injection wells is completed, the hydrogen peroxide solution injection quick connector and the ozone injection quick connector are connected to the ground injection system. After debugging, the injection system is operated, and finally the contaminated soil and groundwater in the site are remediated to meet the standards.

[0043] The formation structure and remediation depth range of the injection well were identified, and the remediation tasks were clarified according to the site pollution situation and project requirements, and the application of the target site was verified. According to the design documents and on-site conditions, small and medium tests were carried out to determine parameters such as the impact radius of the agent injection, and the injection well structure and plane layout were designed.

[0044] According to the injection well design and injection well construction content, the following materials need to be prepared:

[0045] (1) Well pipe: Prepare well pipe materials according to the injection well structure design. Rigid PVC pipes with a specification of DN110 and 304 stainless steel pipes with a specification of DN60 need to be equipped with filter pipes or aeration pipes at the beginning of the corresponding sections according to the design requirements. The filter pipes or aeration pipes should be wrapped with mesh and fixed with wire. All well pipes should be made of strong, corrosion-resistant and pollution-free materials.

[0046] (2) Quartz sand: Pure quartz sand should be used, and the particle size should be 40 mesh or 60 mesh.

[0047] (3) Pengrun soil: Use high-quality Pengrun soil, specification 25kg / bag, permeability coefficient ≤10-9cm / s.

[0048] (4) Concrete raw materials and additives: Concrete raw materials should be pure, and the coarse aggregate gradation should be controlled at 5-10mm. Additives mainly include early strength agent, air-entraining admixture (anti-seepage), etc. Waterstop concrete uses shrinkage-compensating fine stone concrete.

[0049] (5)Other materials.

[0050] The in-situ injection well construction plan allows ozone and hydrogen peroxide to be injected simultaneously in one injection well using 304 stainless steel pipes and hard PVC pipes respectively. The two agents mix safely and efficiently underground, react with target pollutants, degrade the pollutants, and achieve the purpose of repairing contaminated soil and groundwater.

[0051] The structure of the in-situ injection well mainly includes hard PVC solid pipe, hard PVC screen pipe, 304 steel solid pipe, 304 steel open-hole aeration pipe, quartz sand filter material, bentonite water stop, shrinkage-compensating fine stone concrete, PVC well bottom seal, 304 steel well bottom seal, hydrogen peroxide solution injection quick connector, ozone injection quick connector, and concrete platform.

[0052] The hard PVC pipe and 304 stainless steel pipe in the injection well structure are firmly fixed with different-diameter double pipe clamps, and the bottom of the well is sealed with PVC bottom seal and 304 steel bottom seal respectively.

[0053] The injection well construction plan uses bentonite and shrinkage-compensating fine stone concrete. The combination of the two materials stops water and seals the injection well. A concrete well platform is built on the surface to enhance the sealing effect. Precise repair is achieved for the target repair layer to ensure the safety and efficiency of the injection process of the injection well.

[0054] The construction plan of the injection well for in-situ injection of ozone and hydrogen peroxide to repair contaminated soil and groundwater has a simple construction process, and the injection process of the injection well is safe and efficient. The innovative design of the injection well construction plan realizes the combined use of ozone and hydrogen peroxide in the in-situ chemical oxidation technology. The two agents are injected into the repair layer at the same time in the same injection well through different pipelines. Ozone and hydrogen peroxide react underground (repair layer) to generate more oxidizing hydroxyl radicals, which react with pollutants in the soil and groundwater within the repair layer to achieve the purpose of removing pollutants.

[0055] Working principle of the present invention: In the field of contaminated soil and groundwater remediation technology, compared with traditional technologies, the present invention overcomes technical barriers such as poor controllability and explosion hazards of ozone in practical application. The injection well construction plan proposed in the present invention ensures that the in-situ injection process of the agent is convenient, safe, controllable and efficient through the innovative design of the injection well structure, and realizes a more efficient application of ozone, a high-quality oxidant, in the field of in-situ injection chemical oxidation remediation technology. The combined use of ozone and hydrogen peroxide enhances the remediation efficiency, providing an innovative and optimized solution for the in-situ chemical oxidation remediation technology of the site.

[0056] The above shows and describes the basic principles and main features of the present invention and the advantages of the present invention. It should be understood by those skilled in the art that the present invention is not limited to the above embodiments. The above embodiments and descriptions are only for explaining the principles of the present invention. Without departing from the spirit and scope of the present invention, the present invention may have various changes and improvements, which fall within the scope of the present invention to be protected. The scope of protection of the present invention is defined by the attached claims and their equivalents.

Claims

1. A method for repairing contaminated soil and groundwater injection wells, characterized in that: The following steps are involved: Step 1: Determine the site hydrogeological conditions and remediation depth range: Find out the stratigraphic structure of the injection well location and the site parameters of the remediation depth range; Step 2: Drilling construction: Use Φ400 drilling tools to drill holes to the depth of the target layer for repair and drill holes; Step 3: Well pipe connection: The injection well pipe includes a hard PVC pipe with a specification of DN110 and a 304 stainless steel pipe with a specification of DN60. The bottom of the pipe is sealed with a PVC well bottom seal and a 304 steel well bottom seal respectively. The hard PVC pipe and the 304 stainless steel pipe are firmly fixed with a different diameter double pipe clamp; Step 4: Lower the well pipe: Lower the pre-connected well pipe into the borehole. During the lowering process, continue to connect the well pipe according to the previous step until the well pipe is lowered to the bottom of the well pipe, leaving the surface 0.5-1.0m above the ground, and keep the hard PVC pipe and 304 stainless steel pipe at the same height; Step 5: Filling and water-stopping: fill the gaps between the hard PVC screen tube and the 304 steel open-hole aeration tube and the borehole wall with quartz sand filter material, fill the gaps between the hard PVC solid tube and the 304 steel solid tube and the borehole wall with shrinkage-compensating fine stone concrete water-stopping from 1m below the surface to the surface, and fill the rest of the area with bentonite water-stopping; after the concrete reaches the required strength, the injection well is completed; Step 6: Wash the well: Pump water repeatedly to wash the well until the water is clear and the sand is gone; Step 7: Well platform construction: A concrete well platform is set up on the ground. The hard PVC pipe and 304 stainless steel pipe are connected to the hydrogen peroxide solution injection quick connector and the ozone injection quick connector respectively. The injection well construction is completed.

2. A method for repairing contaminated soil and groundwater injection wells according to claim 1, characterized in that: In step one: clarify the remediation tasks, provide a construction plan, and identify whether it is applicable to the remediation of contaminated soil and groundwater on the site.

3. A method for repairing contaminated soil and groundwater injection wells according to claim 1, characterized in that: In the step 3, the length of the ground pipeline connection should not be too long, and the length should be convenient for the pipe lowering operation.

4. A method for repairing contaminated soil and groundwater injection wells according to claim 1, characterized in that: In the step 4: a hard PVC screen pipe and a 304 steel open-hole aeration pipe are set in the repair depth section, and the remaining sections are hard PVC solid pipes and 304 steel solid pipes.

5. A method for repairing contaminated soil and groundwater injection wells according to claim 4, characterized in that: The in-situ injection well construction plan allows ozone and hydrogen peroxide to be injected simultaneously in one injection well using 304 stainless steel pipes and hard PVC pipes respectively. The two agents mix safely and efficiently underground, react with target pollutants, degrade the pollutants, and achieve the purpose of repairing contaminated soil and groundwater.

6. A method for repairing contaminated soil and groundwater injection wells according to claim 5, characterized in that: The structure of the in-situ injection well mainly includes hard PVC solid pipe, hard PVC screen pipe, 304 steel solid pipe, 304 steel open hole aeration pipe, quartz sand filter material, bentonite water stop, shrinkage compensating fine stone concrete, PVC well bottom seal, 304 steel well bottom seal, hydrogen peroxide solution injection quick connector, ozone injection quick connector, and concrete platform.

7. A method for repairing contaminated soil and groundwater injection wells according to claim 6, characterized in that: The hard PVC pipe and the 304 stainless steel pipe in the injection well structure are firmly fixed by using a different-diameter double pipe clamp, and the well bottom is sealed by using a PVC well bottom seal and a 304 steel well bottom seal respectively.

8. A method for repairing contaminated soil and groundwater injection wells according to claim 7, characterized in that: The injection well construction plan adopts bentonite and shrinkage-compensating fine stone concrete. The combination of the two materials stops water and seals the injection well. A concrete well platform is constructed on the surface to enhance the sealing effect, and precise repair is achieved for the target repair layer, ensuring the safety and efficiency of the injection process of the injection well.

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