Storage yard polluted groundwater remediation method based on coupling and blocking of permeable reactive barrier

Abstract

The invention is applicable to the technical field of pollution remediation, and particularly relates to a remediation method for polluted underground water in a storage yard based on coupling and blocking of a permeable reactive barrier, and the method comprises the following steps: acquiring site hydrogeological conditions and distribution conditions of pollution plumes, and constructing a stretching arm type water stop guide wall; constructing a lifting type PRB system, wherein the lifting type PRB system is constructed in a closure area of two downstream arms of the arm-expanding type water stop guide wall; the PRB filler is determined according to the water quality, the flow and the flow velocity of the underground water, the lifting type PRB system is filled with the PRB filler, and the polluted underground water is repaired through the PRB filler. Polluted underground water at the bottom of the tailing pond and around the tailing pond is blocked, guided and converged by the aid of the arm-expanding type water-stopping and flow-guiding wall, the polluted underground water is guided into the lifting type PRB system, and the polluted underground water naturally flows through the PRB system under the converging action of the water-stopping and flow-guiding system. Therefore, the underground water flowing to the downstream through the PRB system reaches the underground water environment quality standard requirement or meets the ecological function requirement of regional underground water.

Description

Technical Field

[0001] The present invention belongs to the technical field of pollution remediation, and in particular relates to a method for remediating contaminated groundwater in a storage yard based on permeable reaction wall coupling isolation. Background Art

[0002] my country has a well-developed mining and smelting industry, resulting in a large number of tailings dumps nationwide. Cyanide tailings are primarily produced during the gold ore extraction and smelting process. Depending on the cyanidation process, tailings can be divided into gold ore cyanidation tailings, heap leaching cyanidation tailings, and gold concentrate cyanidation tailings. Gold concentrate cyanidation tailings are listed on the 2025 National List of Hazardous Wastes due to their high cyanide concentration (liquid-phase cyanide concentrations can reach 800-10,000 mg / L). Cyanide tailings are produced in large quantities and contain high levels of highly toxic substances such as cyanide and thiocyanate, posing a significant threat to human health and the ecological environment. Currently, cyanide tailings are primarily stored in tailings ponds, which are constructed in low-lying terrain to store these wastes. Older landfills rarely have anti-seepage treatment at the bottom of the landfill or tailings pond, allowing tailings leachate to seep directly into the groundwater. Newer landfills generally have anti-seepage treatment, but statistics show that most landfills experience leachate leakage due to damage to the anti-seepage layer during the landfill process. This leachate contains large amounts of cyanide and heavy metal pollutants such as gold, silver, copper, lead, and zinc. It generates acidic wastewater through biogeochemical reactions with sulfides. Once it enters the groundwater, it pollutes the groundwater and spreads to the surrounding areas of the landfill, posing a serious threat to human health and harming the ecological environment. This is a major and persistent environmental concern.

[0003] Leachate from cyanide tailings storage facilities contains high concentrations of cyanide, heavy metals, sulfides, and other pollutants. Currently, the main technologies used include in-situ chemical oxidation, permeable reactive walls, extraction-and-treatment, barrier walls, and high-load underground infiltration systems. In-situ chemical oxidation involves injecting oxidants (such as persulfate, ozone, or Fenton's reagent) into the contaminated area. This oxidation reaction converts cyanide into non-toxic substances (such as CO2 and N2) while simultaneously degrading some heavy metal complexes. Advantages of this method include rapid treatment and effective oxidation. Disadvantages include the need for precise matching of the oxidant to the pollutant's characteristics, which can result in the formation of more toxic intermediates (such as cyanate). Furthermore, the method is incapable of treating heavy metals, leading to high remediation costs. Permeable reactive wall technology involves placing a wall filled with reactive material in the contaminated groundwater flow path. The wall fixes heavy metals and decomposes cyanide through adsorption, precipitation, or chemical reduction. Advantages include minimal environmental impact, low energy consumption, and suitability for low-concentration contaminated groundwater. Disadvantages include the tendency of reactive materials to become passivated or saturated, requiring regular replacement, and the difficulty of construction in complex geological conditions, resulting in high initial investment. Extraction-and-treatment involves extracting contaminated groundwater through wells and combining it with surface treatment processes (such as chemical precipitation, membrane separation, and biodegradation) for purification before reinjection or discharge. Its advantages are mature technology, wide applicability, and the flexibility to address complex contaminants. However, its disadvantages include the "tailing effect" and "rebound effect" associated with extraction, the complexity of surface treatment systems, and the high and unsustainable long-term operating costs. Barrier walls are constructed downstream of the landfill to block the migration and spread of contaminated groundwater. Their advantages are mature technology and ease of construction. However, they must be combined with extraction-and-treatment, otherwise there is a risk of overflow, which can have serious consequences. High-load subsurface infiltration systems utilize buried artificial soil and microorganisms to intercept, adsorb, and biodegrade pollutants. Their advantages are reusable surface areas, low equipment costs, and low operating expenses. However, their disadvantages are low treatment efficiency, insufficient nitrogen removal capacity, the need for anaerobic filtration, the need for pretreatment to treat high-concentration cyanide, and the large footprint required, which significantly limits their application. Therefore, due to these limitations, these technologies have not been effectively used in the treatment of contaminated groundwater at cyanide tailings landfills.

[0004] Among the above technologies, permeable reaction walls are a promising technology suitable for the control and remediation of contaminated groundwater in storage yards. However, this requires the rational development and setting of suitable active materials to extend their service life, improve the ability to deal with complex pollutants, and reduce operating costs. In addition, they need to be coupled with other barrier technologies to optimize the control of groundwater migration paths and reduce the remediation and treatment interface in order to achieve long-term, low-cost remediation of groundwater contaminated by cyanide tailings storage facilities. Summary of the Invention

[0005] The purpose of the present invention is to provide a method for remediating contaminated groundwater in a storage yard based on permeable reaction wall coupling barrier, aiming to solve the problems of high treatment cost and impact on the stability of the mine foundation in the existing technology.

[0006] The present invention is achieved by providing a method for remediating contaminated groundwater in a storage yard based on a permeable reactive wall coupled barrier, the method comprising:

[0007] Obtaining the site's hydrogeological conditions and the distribution of the pollution plume, and constructing a cantilevered water-stopping diversion wall, wherein the cantilevered water-stopping diversion wall has an arm angle determined by the site's hydrogeological conditions and the distribution of the pollution plume;

[0008] Construct a lifting PRB system, which is built in the closing area of the two arms downstream of the cantilever water-stop diversion wall;

[0009] The PRB filler is determined based on the groundwater quality, flow rate and flow velocity, and is filled into the elevated PRB system to repair the contaminated groundwater.

[0010] Preferably, the cantilever type water-stopping diversion wall adopts a porous replacement continuous wall combined with sleeve valve pipe grouting, the medium weathered and above strata are water-stopped by the porous replacement continuous wall, and the medium weathered layer is waterproofed by sleeve valve pipe grouting.

[0011] Preferably, during the construction of the cantilever water-stop diversion wall, the depth of the bite pile reaches the top surface of the fully weathered granite, and the grouting pipe enters the medium weathered layer for no less than 1 m.

[0012] Preferably, the unconfined compressive strength of the cantilever water-stop diversion wall after 28 days under the water curing condition of the test block is not less than 0.5 MPa, and the permeability coefficient is not less than 10 -6 cm / s.

[0013] Preferably, the cement slurry uses P.C42.5 grade cement, the cement dosage is 150 kg / m2, and the water-cement ratio is 0.8-1.0.

[0014] Preferably, the grouting liquid ratio is cement: bentonite: water glass = 100: 10-20: 2-5.

[0015] Preferably, the lifting PRB system is coupled with the cantilevered water-stopping diversion wall by means of a bite.

[0016] Preferably, the solid filler of the elevated PRB system includes manganese sand, activated carbon, iron carbon and limestone.

[0017] Preferably, the particle size of activated carbon is between 1-2 mm, the particle size of manganese sand is between 2-4 mm, and the average particle sizes of iron carbon and limestone are both between 2-4 cm.

[0018] Preferably, the method further includes setting up pairs of long-term monitoring wells inside and outside the cantilever water-stop diversion wall, the spacing between each pair of long-term monitoring wells is in the range of 10-30 meters, and the distance between the long-term monitoring wells and the cantilever water-stop diversion wall is between 1-3 meters.

[0019] The method for remediating contaminated groundwater in a storage yard based on permeable reactive wall coupling barrier provided by the present invention has the following beneficial effects:

[0020] A cantilevered water-stop diversion wall is used to block, guide and converge the contaminated groundwater at the bottom of the tailings pond and its surroundings, and direct the contaminated groundwater into the elevated PRB system; in the vertical direction, the PRB is constructed on the water-stop wall constructed in the direction of the two arms closing downstream of the cantilevered water-stop diversion wall. The water-stop wall blocks the water flow below the bottom of the PRB system, allowing the PRB system to be elevated; the contaminated groundwater naturally flows through the PRB system through the convergence effect of the water-stop diversion system, and the contaminated groundwater flowing through the PRB system is repaired and purified through the adsorption and redox reaction of the filler, so that the groundwater flowing downstream through the PRB system meets the groundwater environmental quality standards or meets the regional groundwater ecological function needs. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 A schematic diagram of the principle of a method for remediating contaminated groundwater in a storage yard based on a coupled barrier of a permeable reactive wall provided by an embodiment of the present invention;

[0022] Figure 2 A schematic diagram of the top treatment of the cut-off wall provided in an embodiment of the present invention;

[0023] Figure 3 A large-scale plan view of the sleeve valve tube provided in an embodiment of the present invention. DETAILED DESCRIPTION

[0024] In order to make the purpose, technical solutions and advantages of the present invention more clearly understood, the present invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not intended to limit the present invention.

[0025] like Figure 1 FIG. 1 is a schematic diagram of a method for remediating contaminated groundwater in a storage yard based on a coupled barrier of a permeable reactive wall according to an embodiment of the present invention. The method includes:

[0026] The hydrogeological conditions of the site and the distribution of the pollution plume are obtained, and a cantilevered water-stopping diversion wall is constructed. The arm angle of the cantilevered water-stopping diversion wall is determined by the hydrogeological conditions of the site and the distribution of the pollution plume.

[0027] In this step, a cantilevered water-stop diversion wall is constructed according to the site hydrogeological conditions and the distribution of the pollution plume, and a suitable arm angle is designed according to the above conditions. The water-stop diversion wall (i.e., a cantilevered water-stop diversion wall, hereinafter referred to as the diversion wall) is used to prevent pollutants from spreading outside the site, thereby achieving the isolation, diversion and collection of polluted groundwater. The arm shape of the cantilevered water-stop diversion wall can be reasonably designed according to the distribution of the groundwater pollution plume and its engineering implementation requirements, and is not limited to a straight type. During construction, the depth of the interlocking pile should reach the top surface of the fully weathered granite, and the grouting pipe should enter the medium weathering layer for no less than 1m. The water-stop diversion wall adopts a porous replacement continuous wall combined with sleeve valve pipe grouting, that is, the medium weathering and above strata are water-stopped by a porous replacement continuous wall, and the medium weathering layer is waterproofed by sleeve valve pipe grouting.

[0028] The porous replacement continuous wall is pre-adopted The holes were drilled with a down-the-hole hammer (spacing 400mm) using P.C42.5 grade cement, with a cement dosage of approximately 150kg per square metre and a water-cement ratio of 0.8-1.0.

[0029] The 28-day unconfined compressive strength of the porous replacement continuous wall specimen under underwater curing conditions should be no less than 0.5 MPa, and the permeability coefficient should be less than 10-6 cm / s.

[0030] To prevent surface water from flowing out of the site, a 2.0m-high plain concrete diaphragm wall was cast between the double rows of diaphragm walls to block surface water runoff. The grouting mix for the sleeve valve pipes was cement: bentonite: water glass = 100:10-20:2-5, with a grouting pressure of 0.5-1.0 MPa and approximately 200 kg of cement per meter. Grouting for the sleeve valve pipes was performed in intervals and layers, using slow static pressure and multiple injections per hole. Grouting was terminated when the pressure reached 1.0 MPa.

[0031] Construct a lifting PRB system, which is constructed in the closing area of the two downstream arms of the cantilevered water-stop diversion wall.

[0032] In this step, a lifted PRB system is constructed in the direction of the two arms closing downstream of the cantilever water-stop diversion wall, that is, the PRB system is constructed on the water-stop barrier wall. The water-stop barrier wall can block the water flow at the bottom of the lifted PRB system. The entire lifted PRB system and the cantilever water-stop diversion wall together form a closed system, making the filler reaction area of the lifted PRB system the only flow direction of contaminated groundwater.

[0033] The elevated PRB system is coupled with the water-stop diversion wall through a bite-type method. The construction depth of the elevated PRB system is generally 2-5 meters below the normal water level. Water-stop walls need to be constructed on both sides of the bottom of the elevated PRB system parallel to the water flow direction. The filler of the elevated PRB system extends horizontally in layers in the direction of water flow, and the surface of each layer of filler is perpendicular to the water flow direction. The filler thickness, filling amount and its ratio need to be determined according to actual conditions. The elevated PRB system can be replaced regularly to maintain its long-term stable and efficient operation.

[0034] The PRB filler is determined based on the groundwater quality, flow rate and flow velocity, and is filled into the elevated PRB system to repair the contaminated groundwater.

[0035] In this step, the main solid fillers of the elevated PRB system include manganese sand, activated carbon, iron carbon and limestone, etc. The particle size of activated carbon is preferably between 1-2 mm, the particle size of manganese sand is preferably between 2-4 mm, and the average particle size of iron carbon and limestone is preferably between 2-4 cm. Different filler formulas will be set for different water quality fillers in cyanide tailings sites. The filler types mentioned in the present invention and their various formula compositions for groundwater treatment and disposal of cyanide tailings sites all fall within the scope of protection of the present invention. The pollutants in contaminated groundwater mainly applicable to the present invention include cyanide and metal ions such as manganese, but are not limited to the above-mentioned pollutants. Other pollutants that can be removed by the present invention are also within the scope of protection of the present invention.

[0036] The water-stopping diversion wall in this invention differs from traditional water-stopping curtains. It uses a porous replacement continuous wall to stop water in strata above moderately weathered rock, while sleeve valve pipe grouting is used for seepage control in moderately weathered rock layers. The vertical anti-seepage function extends directly into the moderately weathered rock layer. The cantilevered design completely captures the pollution plume within the control area, preventing any boundary overflow. The appropriate arm angle is designed to converge and guide the pollution plume into the liftable PRB system. This design structure is highly innovative.

[0037] The fillers of the PRB system (elevated PRB system) of the present invention are layered in the horizontal direction, and different dominant pollutants are removed in each layer of filler. Different PRB fillers are filled according to the physicochemical properties and characteristic pollutants of the contaminated groundwater in different cyanide tailings landfills. The contaminated groundwater naturally flows through the PRB system through the convergence effect of the water-stopping and diversion system. The contaminated groundwater flowing through the PRB system is repaired and purified through the adsorption and redox reactions of the fillers. The above functions that can be achieved by this elevated PRB system break the key defects of the traditional PRB system and directly promote the engineering application of the PRB system.

[0038] The fillers in each layer of the PRB system in this invention have their own corresponding main functions to treat different pollutants. The main functions of each layer are as follows:

[0039] Enhanced manganese removal layer: Enhanced manganese and sulfate removal; the filler is composed of manganese sand and limestone.

[0040] Enhanced cyanide removal and coordinated manganese removal section: adsorption of manganese and cyanide; the filler is composed of activated carbon and limestone.

[0041] Cyanide and manganese deep treatment section: enhances cyanide removal and synergistically removes manganese; the filler is a mixture of activated carbon, iron-carbon balls, limestone, etc.

[0042] The effectiveness of the present invention is demonstrated by comparative experiments below.

[0043] In one specific embodiment of the present invention, the project is implemented at a cyanide tailings storage site. The temporary storage site is located southwest of the main plant, covering an area of 71,349 m². The tailings are dumped from the north to the south of the site, with a total volume of approximately 200,000 m³ already filled. The project involves a coordinated system of water-stopping diversion walls and permeable reaction tanks. The system primarily consists of three components: a water-stopping diversion wall system, a raised PRB system, and a groundwater monitoring well system.

[0044] Example 1

[0045] The specific repair steps are as follows:

[0046] (1) Construction of porous continuous wall

[0047] 1. Such as Figure 2 As shown, a porous replacement diaphragm wall is installed in the gully downstream of the tailings dump backfill platform. It is arranged in two rows, with a single row approximately 58.5 meters in plan. Two additional rows of grouting holes are placed where diaphragm wall construction is impractical on the slope to ensure that the waterstop curtain extends at least 10 meters into the slope. According to preliminary geological survey results, groundwater flows downward along the gully, following the terrain. The gully is high on either side, and groundwater flows from both sides toward the center of the gully, converging there. Therefore, the waterstop walls in this project extend at least 10 meters into the mountains on both sides to prevent groundwater bypass.

[0048] 2. The bottom of the porous replacement continuous wall reaches the top of the medium-weathered bedrock. The medium-weathered layer should be determined based on the geological survey report and the on-site drilling conditions. The permeability of the medium-weathered bedrock on the site is about 10 -4 ~10 -5 cm / s, and has a certain permeability, so the weathered layer needs to be grouting treated.

[0049] 3. Pre-use of porous replacement continuous wall The holes were drilled with a down-the-hole hammer (spacing 400mm) using P.C42.5 grade cement, with a cement dosage of approximately 150kg per square metre and a water-cement ratio of 0.8-1.0.

[0050] 4. In order to prevent surface water from flowing out of the site, a 2.0m high plain concrete continuous wall is cast in the middle of the double rows of continuous walls to isolate the surface water runoff.

[0051] 5. The strength test of the continuous wall test block should be carried out. The unconfined compressive strength of the test block under underwater curing conditions for 28 days should be no less than 0.5MPa, and the permeability coefficient should be less than 10 -6 cm / s.

[0052] (2) Construction of sleeve valve tube grouting curtain:

[0053] 1. Such as Figure 3 As shown, the horizontal spacing of the sleeve valve pipe grouting holes is 1m, and they are set along both sides of the plain concrete continuous wall. The depth of the sleeve valve pipe grouting drilling holes is based on entering the slightly weathered layer, and the grouting section is 3m above the bottom of the continuous wall to the bottom of the medium weathered layer.

[0054] 2. The grouting ratio of sleeve valve pipe is cement: bentonite: water glass = 100:10-20:2-5. The grouting pressure is 0.5-1.0 MPa, and the amount of cement injected per meter is about 200 kg.

[0055] 3. Grouting termination condition: grouting pressure reaches 1.0MPa.

[0056] (3) Construction of the lifting PRB system:

[0057] The dimensions of the elevated PRB system are 10m x 15m x 5.0m (length x width x depth). The groundwater inlet of the PRB system is located above the waterstop wall, where it intersects with the waterstop wall. The PRB is elevated 0.5m above the ground. A roof is installed on the PRB tank to prevent rainwater from entering directly.

[0058] (4) PRB system filling enhanced cyanide removal and manganese removal section

[0059] The manganese sand / limestone mass ratio is 5 / 2 and mixed and filled to form an enhanced manganese removal section of 4m×10m×5.0m (length×width×depth).

[0060] (5) Sampling analysis

[0061] By monitoring the PRB effluent quality, the operating status of the PRB and its manganese removal performance can be judged.

[0062] Example 2

[0063] The specific repair steps are as follows:

[0064] The first four steps in this embodiment are the same as steps (1), (2), (3), and (4) in Example 1.

[0065] (5) PRB system filling enhanced cyanide removal and manganese removal section

[0066] The activated carbon / limestone mass ratio is 1 / 1 and mixed to form a 4m×10m×5.0m (length×width×depth) enhanced cyanide removal and coordinated manganese removal section.

[0067] (6) PRB system filling cyanide and manganese deep processing section

[0068] The iron-carbon / limestone mass ratio is 1 / 2 and mixed and filled to form a 2m×10m×5.0m (length×width×depth) cyanide and manganese deep treatment section.

[0069] (7) Sampling analysis

[0070] By monitoring the PRB effluent quality, the operating status of the PRB and its manganese and cyanide removal performance can be judged.

[0071] Comparative Example 1:

[0072] No water-stop diversion wall was constructed, and water samples were taken from each monitoring well for analysis. A double-arm water-stop diversion wall was constructed and a PRB system was built, but only the enhanced cyanide removal and coordinated manganese removal section filler was filled, and the enhanced cyanide removal and coordinated manganese removal section and the cyanide and manganese deep treatment section filler were not filled.

[0073] Comparative Example 2:

[0074] A double-arm water-stop diversion wall was constructed and a PRB system was built, but only the enhanced cyanide removal and coordinated manganese removal section filler was filled, and the enhanced cyanide removal and coordinated manganese removal section and the cyanide and manganese deep treatment section filler were not filled; a double-arm water-stop diversion wall was constructed and a PRB system was built, and all three sections of fillers were filled.

[0075] The results of the test and analysis showed that the penetration systems of the three core samples were 4.47×10 -7 cm / s、4.60×10 -7 cm / s、4.98×10 -7 cm / s, all less than 10 -6 cm / s; the construction of the water-stop diversion wall effectively blocked the flow of the contaminant plume, significantly improving water quality downstream of the wall. A similar patent family has demonstrated that water-stop walls of similar design and structure have excellent convergence and diversion performance. The differences between the manganese and cyanide test indicators in the original four wells were all within 10%. Table 1-1 shows the target pollutant test indicators for the four wells after the construction of the double-arm water-stop diversion wall, the establishment of the PRB system, and the installation of the enhanced cyanide removal and manganese removal filler. The implementation of this structure has significantly reduced manganese in groundwater, meeting relevant requirements.

[0076] Table 1-1 Monitoring well monitoring analysis results

[0077] project Well No. 1 Well No. 2 Well No. 3 Well No. 4 Manganese (mg / L) 31.7 32.5 1.25 1.08 Cyanide (mg / L) 1.52 1.48 1.55 1.50

[0078] Table 1-2 shows the results of sampling and analysis of four wells after the full implementation of the PRB system. Compared with the system without fillers for enhanced cyanide removal, coordinated manganese removal, and cyanide and manganese deep treatment, the completed system achieved the design requirements for the removal efficiency of the target pollutants manganese and cyanide. The PRB filler ratio of this project is specially designed according to the water quality and is the preferred formula after dual verification by experiments and practice. The present invention will set different filler formulas for different water quality fillers in cyanide tailings sites. The filler types mentioned in the present invention and their various formula compositions for groundwater treatment and disposal of cyanide tailings sites are all within the scope of the claims of the present invention and should be protected.

[0079] Table 1-2 Monitoring well monitoring analysis results

[0080] project Well No. 1 Well No. 2 Well No. 3 Well No. 4 Manganese (mg / L) 31.7 32.5 1.15 1.02 Cyanide (mg / L) 1.52 1.48 0.15 0.23

[0081] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions and improvements made within the spirit and principles of the present invention should be included in the scope of protection of the present invention.

Claims

1. A method for remediating contaminated groundwater in a storage yard based on a coupled barrier of a permeable reactive wall, characterized in that: The method comprises: Obtaining the site's hydrogeological conditions and the distribution of the pollution plume, and constructing a cantilevered water-stopping diversion wall, wherein the cantilevered water-stopping diversion wall has an arm angle determined by the site's hydrogeological conditions and the distribution of the pollution plume; Construct a lifting PRB system, which is built in the closing area of the two arms downstream of the cantilever water-stop diversion wall; The PRB filler is determined based on the groundwater quality, flow rate and flow velocity, and is filled into the elevated PRB system to repair the contaminated groundwater.

2. The method for remediating contaminated groundwater in a storage yard based on permeable reactive wall coupling barrier according to claim 1 is characterized in that: The cantilever type water-stop diversion wall adopts a porous replacement continuous wall combined with sleeve valve pipe grouting. The porous replacement continuous wall is used to stop water in the moderately weathered strata, and the sleeve valve pipe grouting is used to prevent seepage in the moderately weathered strata.

3. The method for remediating contaminated groundwater in a storage yard based on permeable reactive wall coupling barrier according to claim 1, characterized in that: During the construction of the cantilever water-stop diversion wall, the depth of the interlocking piles reaches the top surface of the fully weathered granite, and the grouting pipe enters the medium weathered layer for no less than 1m.

4. The method for remediating contaminated groundwater in a storage yard based on permeable reactive wall coupling barrier according to claim 1, characterized in that: The unconfined compressive strength of the cantilevered water-stop diversion wall after 28 days of water curing of the test block is not less than 0.5Mpa, and the permeability coefficient is not less than 10 -6 cm / s.

5. The method for remediating contaminated groundwater in a storage yard based on permeable reactive wall coupling barrier according to claim 2, characterized in that: The cement slurry uses P.C42.5 grade cement, the cement dosage is 150 kg / m2, and the water-cement ratio is 0.8-1.

0.

6. The method for remediating contaminated groundwater in a storage yard based on permeable reactive wall coupling barrier according to claim 2, characterized in that: The grouting liquid ratio is cement: bentonite: water glass = 100: 10-20: 2-5.

7. The method for remediating contaminated groundwater in a storage yard based on permeable reactive wall coupling barrier according to claim 1, characterized in that: The lifting PRB system is coupled with the cantilevered water-stop diversion wall by interlocking.

8. The method for remediating contaminated groundwater in a storage yard based on permeable reactive wall coupling barrier according to claim 1, characterized in that: The solid fillers of the elevated PRB system include manganese sand, activated carbon, iron carbon and limestone.

9. The method for remediating contaminated groundwater in a storage yard based on permeable reactive wall coupling isolation according to claim 8, characterized in that: The particle size of activated carbon is between 1-2 mm, the particle size of manganese sand is between 2-4 mm, and the average particle size of iron carbon and limestone is between 2-4 cm.

10. The method for remediating contaminated groundwater in a storage yard based on permeable reactive wall coupling isolation according to claim 1, characterized in that: The method also includes setting up pairs of long-term monitoring wells inside and outside the cantilever water-stopping diversion wall, with the spacing between each pair of long-term monitoring wells ranging from 10 to 30 meters, and the distance between the long-term monitoring wells and the cantilever water-stopping diversion wall being between 1 and 3 meters.

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