A comprehensive evaluation method for domestic waste landfill excavation

Abstract

The present application relates to the technical field of municipal solid waste landfill treatment, and particularly relates to a comprehensive evaluation method for excavation of municipal solid waste landfill; comprising the following steps: carrying out all-round investigation on engineering, waste, environment and external conditions of the landfill, and establishing a complete basic database; carrying out stability evaluation of the landfill, determining the stability grade of the stack according to indexes such as methane concentration and organic matter, and determining whether the landfill can be excavated and whether pretreatment is needed; carrying out safety risk evaluation of excavation, quantifying risks from four aspects of stack stability, gas explosion prevention, seepage prevention protection and slope collapse prevention, and giving prevention and control requirements; carrying out environmental impact evaluation by comprehensively evaluating leachate, odor, dust, noise and secondary pollution; carrying out construction and disposal adaptability evaluation; carrying out economic and construction period evaluation; carrying out real-time monitoring and weighted scoring on the whole process; and realizing the treatment requirements of meeting safe construction, reaching environmental protection standards and being controllable in the whole process.

Description

Technical Field

[0001] This invention relates to the field of municipal solid waste landfill remediation technology, and in particular to a comprehensive assessment method for municipal solid waste landfill excavation. Background Technology

[0002] Currently, urban domestic waste in my country is increasing at a rate of 8% to 15% annually. Most formal domestic waste landfills are nearing the end of their service life, resulting in a severe shortage of landfill capacity and increasingly prominent management issues. Domestic waste landfills not only occupy a large amount of land resources but also cause the emission of methane, carbon dioxide, and other harmful gases, as well as leachate pollution of groundwater.

[0003] However, current landfill excavation operations mainly rely on engineering experience and lack a unified, standardized, and quantitative comprehensive assessment system. This poses risks such as biogas explosions, slope collapses, damage to the geomembrane, leachate overflow, and foul odors, and fails to meet the requirements for safe construction, environmental compliance, and full-process control. Summary of the Invention

[0004] The purpose of this invention is to provide a comprehensive evaluation method for the excavation of municipal solid waste landfills. This method aims to solve the technical problems in the existing technology where the excavation of municipal solid waste landfills mainly relies on engineering experience, lacks a unified, standardized, and quantitative comprehensive evaluation system, and has hidden dangers such as biogas explosions, slope collapses, damage to the geomembrane, leachate overflow, and odor nuisance. It also fails to meet the technical requirements of safe construction, environmental compliance, and full-process controllability.

[0005] To achieve the above objectives, the present invention employs a comprehensive evaluation method for the excavation of municipal solid waste landfills, comprising the following steps:

[0006] Conduct a comprehensive survey of landfills, including engineering, waste, environmental and external conditions, and establish a complete basic database.

[0007] The landfill stabilization assessment is conducted based on indicators such as methane concentration and organic matter to determine the stabilization level of the landfill and whether it can be excavated and whether pretreatment is required.

[0008] The safety risk assessment for excavation quantifies the risks from four aspects: stockpile stability, gas explosion prevention, seepage prevention, and slope collapse prevention, and provides control requirements.

[0009] The environmental impact assessment involves a comprehensive evaluation of leachate, odor, dust, noise, and secondary pollution.

[0010] The suitability assessment of construction and disposal was conducted to match the optimal excavation, seepage prevention, drainage, and rainwater and sewage separation processes, and to determine the waste screening and resource recovery disposal pathways.

[0011] Economic and schedule assessments were conducted to calculate the total project cost and reasonable schedule, and to verify the feasibility and cost-effectiveness of implementation.

[0012] The entire process is monitored in real time and weighted, and the feasibility of excavation is determined by level, and a complete implementation plan is output.

[0013] Among the steps involved in conducting a comprehensive survey of the landfill's engineering, waste, environmental, and external conditions to establish a complete basic database:

[0014] Collect data on the volume of the pile, the height of the pile, the slope gradient, the bearing capacity of the stratum, the groundwater level, the thickness / type of the geomembrane, the size of the drainage blind ditch, the diameter of the HDPE pipe, and the spacing and number of the gas wells.

[0015] The tests included the landfill age, waste composition percentage, moisture content (35%–60%), organic matter content (5%–30%), and compaction density (≥0.8 t / m³). 3 and degree of mineralization;

[0016] Monitor groundwater pH, ammonia nitrogen, and heavy metals; leachate COD, BOD5, ammonia nitrogen, and SS; atmospheric ammonia, hydrogen sulfide, and odor concentrations; and soil heavy metal and organic matter indicators.

[0017] Statistics include transportation distance, incineration / disposal / backfill site capacity, distance to surrounding sensitive points, road weight limits, and traffic conditions.

[0018] In the landfill stabilization assessment, the stability level of the landfill is determined based on indicators such as methane concentration and organic matter, which determines whether excavation is permissible and whether pretreatment is required:

[0019] The methane concentration, organic matter content, leachate yield, and pile settling rate are all measured to be ≤5 mm / month.

[0020] The stability is classified into three levels: high stability, medium stability, and low stability. High stability is defined as: methane < 5% and organic matter < 10%; medium stability is defined as: methane 5%–15% and organic matter 10%–20%; and low stability is defined as: methane > 15% and organic matter > 20%.

[0021] The treatment is based on the severity level: high stability requires direct excavation; medium stability requires forced aeration followed by aerobic pretreatment before excavation; and low stability requires prohibition of excavation and continued pretreatment.

[0022] The assessment of excavation safety risks quantifies risks from four aspects: stockpile stability, gas explosion prevention, seepage prevention, and slope collapse prevention, and outlines the steps for prevention and control requirements.

[0023] Calculate the safety factor of the pile body slope, where the slope safety factor is ≥1.2, the slope gradient is ≤1:3, the layered excavation thickness is ≤1.5~3.0m, the platform width is ≥3m, and the platform height difference is 5~10m;

[0024] The methane explosion warning threshold is set at 5%, the methane level at the working face is <5%, the longitudinal and transverse spacing of the gas wells is 30m, and they are arranged in a quincunx pattern.

[0025] Delineate the protection zone of the geomembrane. Mechanical excavation is strictly prohibited within 1.0m of the HDPE geomembrane. The thickness of the protective layer on the geomembrane should be ≥300mm.

[0026] In the working pit, a 30° mechanical ramp is reserved according to the slope ratio of 1:3, and a 12m×6m working platform is set up every 7m of depth.

[0027] In the environmental impact assessment, a comprehensive evaluation of leachate, odor, dust, noise, and secondary pollution is conducted:

[0028] The leachate collection, drainage, and treatment capacity and the effect of rainwater and sewage separation were assessed, and the risk of groundwater pollution spread was calculated. The leachate collection slope was ≥2%, the equalization tank capacity was sufficient for more than 7 days of storage, the rainwater and sewage separation efficiency was ≥95%, and there were 6 groundwater monitoring wells.

[0029] Calculate the intensity of the odor source, verify the coverage of the deodorization equipment, the temporary airtightness of the work surface and the compliance of the site boundary, and ensure that the odor concentration meets the standard of ≤20, the spray radius of the fog cannon is ≥30m, the agent spraying rate is 20~35L / min, and the airtightness of the work surface is 100%.

[0030] The effectiveness of construction machinery noise, road dust control, vehicle washing and closed transportation measures was evaluated, with construction noise ≤70dB, road watering frequency ≥3 times / day, 100% washing of vehicles leaving the site, and tires free of mud.

[0031] Verify the waste transfer, screening residue, and hazardous waste identification, with 100% of waste being transported in a sealed manner, screening impurities content ≤10%, and hazardous waste identification rate 100%, and entrust qualified units to handle the waste.

[0032] Among the steps involved are assessing the compatibility between construction and disposal, matching the optimal excavation, seepage prevention, drainage, and rainwater / sewage separation processes, and determining the waste screening and resource recovery pathways:

[0033] Excavation shall be carried out according to the conditions of the pile body, and the excavation method shall be zoning + layering shallow excavation, with the width of the transport ramp ≥ 5m;

[0034] Matching the groundwater blind drain, leachate collection pipe, HDPE membrane repair and welding inspection process, wherein the groundwater blind drain slope is ≥2%, the leachate main pipe is DN400 and the branch pipe is DN200 HDPE perforated pipe, and the HDPE membrane welding air pressure test is 0.25MPa, with pressure holding for 3~5min;

[0035] The design incorporates a rainwater and sewage separation system consisting of temporary coverings, flexible drainage ditches, intercepting ditches, and sump pits for forced drainage. The rainwater and sewage separation system uses a 1.0mm thick HDPE membrane for covering. The temporary drainage ditches are 0.4m×0.4m~1.0m×0.6m in size, and the sump pits have a forced drainage capacity that meets the storm return period P=1.

[0036] The grading process is based on a drum screen and air classification. The path for the oversize material to be incinerated, the undersize material to be backfilled / resourced, and the hazardous waste to be outsourced for disposal is determined. The particle size is divided into 60mm and 80mm. 60% of the oversize material is transported off-site for incineration, and 40% of the undersize material is backfilled on-site. The moisture content is controlled to be ≤40%.

[0037] Among the steps involved in economic and schedule assessment, calculating the total project cost and reasonable schedule, and verifying the feasibility and cost-effectiveness of implementation:

[0038] The costs of exploration, pretreatment, excavation, screening, transportation, environmental protection, testing, and emergency response are calculated separately.

[0039] Based on the daily excavation and screening capacity, equipment and personnel configuration, the baseline construction period is calculated, with allowances made for the rainy season and environmental constraints. The daily processing capacity is 1000~4500m³. 3 The equipment configuration includes 2-4 excavators, 8-15 transfer vehicles, and 1-2 screening lines;

[0040] Calculate the unit volume treatment cost and resource-saving cost, and evaluate the overall cost-effectiveness. The construction period is calculated by dividing the total amount by the daily production capacity, with a 15% to 20% margin reserved for the rainy season, and the total construction period deviation is ≤ ±10%.

[0041] An economic assessment was conducted, with the provincial cost of resource resolution accounting for ≥15% and the unit disposal cost being lower than the industry average.

[0042] Among the steps, the following steps are involved: real-time monitoring and weighted scoring of the entire process, graded assessment of excavation feasibility, and output of a complete implementation plan:

[0043] Dynamically monitor methane concentration, slope displacement, leachate level, groundwater quality, odor concentration, and seepage prevention integrity, with a monitoring frequency of once per day;

[0044] The comprehensive score is calculated by weighting indicators such as stabilization, safety, environment, construction, and economy. The weighted scores are as follows: stabilization 20%, safety 30%, environment 25%, construction 15%, and economy 10%.

[0045] The classification is as follows: ≥80 points is Grade A, which allows direct excavation; 60~79 points is Grade B, which requires rectification before excavation; <60 points is Grade C, which prohibits excavation.

[0046] Output feasibility reports, construction plans, disposal plans, risk control lists, and emergency response plans.

[0047] This invention provides a comprehensive assessment method for the excavation of municipal solid waste landfills, comprising the following steps: conducting a comprehensive survey of the landfill's engineering, waste, environment, and external conditions to establish a complete basic database; assessing the landfill's stabilization by determining the stability level of the landfill based on indicators such as methane concentration and organic matter, thus determining whether excavation is feasible and whether pretreatment is required; assessing the excavation safety risks by quantifying risks from four aspects: landfill stability, gas explosion prevention, seepage prevention, and slope collapse prevention, and providing control requirements; assessing the environmental impact by comprehensively evaluating leachate, odor, dust, noise, and secondary pollution; and assessing the suitability of construction and disposal. The assessment process involves matching the optimal excavation, seepage prevention, drainage, and rainwater / sewage separation technologies, and determining the waste screening and resource recovery disposal pathways. Economic and timeline assessments are conducted to calculate the total project cost and reasonable construction period, verifying feasibility and cost-effectiveness. Real-time monitoring and weighted scoring of the entire process are implemented to classify excavation feasibility and output a complete implementation plan. By establishing a comprehensive, quantitative excavation assessment system, safety hazards such as biogas explosions, slope collapses, and mechanical damage to the seepage membrane are effectively eliminated. Environmental risks related to leachate drainage, odor diffusion, dust, and noise are precisely controlled, achieving the goals of safe construction, environmental compliance, and full-process controllability. Attached Figure Description

[0048] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0049] Figure 1 This is a flowchart of the steps of the comprehensive evaluation method for municipal solid waste landfill excavation according to the present invention.

[0050] Figure 2 This is a flowchart of steps S100 of the present invention.

[0051] Figure 3 This is a flowchart of steps S200 of the present invention.

[0052] Figure 4 This is a flowchart of steps S300 of the present invention.

[0053] Figure 5This is a flowchart of steps S400 of the present invention.

[0054] Figure 6 This is a flowchart of steps S500 of the present invention.

[0055] Figure 7 This is a flowchart of steps S600 of the present invention.

[0056] Figure 8 This is a flowchart of steps S700 of the present invention. Detailed Implementation

[0057] Exemplary embodiments will now be described in detail, examples of which are illustrated in the accompanying drawings. When the following description relates to the drawings, unless otherwise indicated, the same numbers in different drawings represent the same or similar elements. The embodiments described in the following exemplary embodiments do not represent all embodiments consistent with this application.

[0058] The terminology used in this application is for the purpose of describing particular embodiments only and is not intended to be limiting of the application. The singular forms “a,” “the,” and “the” used in this application and the appended claims are also intended to include the plural forms unless the context clearly indicates otherwise. It should also be understood that the term “and / or” as used herein refers to and includes any or all possible combinations of one or more of the associated listed items.

[0059] It should be understood that although the terms first, second, third, etc., may be used in this application to describe various information, such information should not be limited to these terms. These terms are only used to distinguish information of the same type from one another. For example, without departing from the scope of this application, first information may also be referred to as second information, and similarly, second information may also be referred to as first information. Depending on the context, the word "if" as used herein may be interpreted as "when," "when," or "in response to determination."

[0060] Please see Figures 1-8 This invention provides a comprehensive evaluation method for the excavation of municipal solid waste landfills, comprising the following steps:

[0061] S100: Conduct a comprehensive survey of landfills, including engineering, waste, environmental and external conditions, and establish a complete basic database.

[0062] In this embodiment, a comprehensive survey of the landfill is conducted, including engineering, waste, environmental, and external conditions, to establish a complete basic database. The specific process is as follows:

[0063] S101: Collect data on pile volume, pile height, slope gradient, stratum bearing capacity, groundwater level, geomembrane thickness / type, drainage ditch dimensions, HDPE pipe diameter, and the spacing and number of gas wells.

[0064] S102: Testing includes landfill age, waste composition percentage, moisture content (35%~60%), organic matter content (5%~30%), and compaction density ≥0.8t / m³. 3 and degree of mineralization;

[0065] S103: Monitor groundwater pH, ammonia nitrogen, heavy metals; leachate COD, BOD5, ammonia nitrogen, SS; atmospheric ammonia, hydrogen sulfide, odor concentrations; and soil heavy metal and organic matter indicators.

[0066] S104: Statistics on transportation distance, incineration / disposal / backfill site capacity, distance to surrounding sensitive points, road weight limits and traffic conditions.

[0067] In the above process, the following data were first collected: pile volume, pile height, slope gradient, stratum bearing capacity, groundwater level, geomembrane thickness / type, drainage ditch dimensions, HDPE pipe diameter, and spacing and number of venting wells. Then, the landfill age, waste composition percentage, moisture content (35%–60%), organic matter content (5%–30%), and compaction density (≥0.8 t / m³) were measured. 3 The study also monitors the degree of mineralization; groundwater pH, ammonia nitrogen, heavy metals; leachate COD, BOD5, ammonia nitrogen, SS; atmospheric ammonia, hydrogen sulfide, odor concentrations; and soil heavy metal and organic matter indicators. Further statistics are then compiled on transportation distance, incineration / disposal / backfill site capacity, distance to surrounding sensitive points, road weight limits, and traffic conditions.

[0068] S200: Landfill stabilization assessment, which determines the stabilization level of the landfill based on indicators such as methane concentration and organic matter, and determines whether it can be excavated and whether pretreatment is required.

[0069] In this embodiment, the landfill stabilization assessment is conducted based on indicators such as methane concentration and organic matter to determine the stabilization level of the landfill, thereby determining whether it is excavable and whether pretreatment is required. The specific process is as follows:

[0070] S201: Detect methane concentration, organic matter content, leachate yield, and pile settling rate ≤5mm / month;

[0071] S202: Classification is performed, with grades including high stability, medium stability, and low stability. High stability: methane < 5%, organic matter < 10%; medium stability: methane 5%~15%, organic matter 10%~20%; low stability: methane > 15%, organic matter > 20%.

[0072] S203: Disposal will be carried out according to the assessment level, including direct excavation for high stability, excavation after forced aeration and aerobic pretreatment for medium stability, and prohibition of excavation and continued pretreatment for low stability.

[0073] In the above process, firstly, the methane concentration, organic matter content, leachate yield, and pile settlement rate are measured to be ≤5mm / month; then, a classification judgment is made, including high stability, medium stability, and low stability, where high stability: methane <5%, organic matter <10%; medium stability: methane 5%~15%, organic matter 10%~20%; low stability: methane >15%, organic matter >20%; and then treatment is carried out according to the judgment level, where high stability is directly excavated, medium stability is excavated after forced gas introduction and aerobic pretreatment, and low stability is prohibited from excavation and requires continued pretreatment.

[0074] S300: For excavation safety risk assessment, the risks are quantified from four aspects: stockpile stability, gas explosion prevention, seepage prevention and slope collapse prevention, and prevention and control requirements are given.

[0075] In this embodiment, the excavation safety risk assessment quantifies the risks from four aspects: stockpile stability, gas explosion prevention, seepage prevention, and slope collapse prevention, and provides control requirements. The specific process is as follows:

[0076] S301: Calculate the safety factor of the pile body slope, where the slope safety factor is ≥1.2, the slope gradient is ≤1:3, the layered excavation thickness is ≤1.5~3.0m, the platform width is ≥3m, and the platform height difference is 5~10m;

[0077] S302: Set the methane explosion warning threshold to 5%, methane at the working face <5%, and the longitudinal and transverse spacing of the gas wells is 30m, arranged in a quincunx pattern;

[0078] S303: Define the protection range of the geomembrane. Mechanical excavation is strictly prohibited within 1.0m of the HDPE geomembrane. The thickness of the protective layer on the geomembrane shall be ≥300mm.

[0079] S304: In the working pit, a 30° mechanical ramp is reserved according to the slope ratio of 1:3, and a 12m×6m working platform is set up every 7m of depth.

[0080] During the above process, the safety factor of the pile slope is calculated, with a slope safety factor ≥1.2, slope gradient ≤1:3, layered excavation thickness ≤1.5~3.0m, platform width ≥3m, and platform height difference 5~10m; the methane explosion warning threshold is set at 5%, methane at the working face is <5%, the longitudinal and transverse spacing of the gas wells is 30m, and a quincunx arrangement is adopted; the protection range of the geomembrane is delineated, and mechanical excavation is strictly prohibited within 1.0m of the HDPE geomembrane, and the thickness of the protective layer on the geomembrane is ≥300mm; then, in the working pit, a 30° mechanical ramp is reserved according to the slope ratio of 1:3, and a 12m×6m working platform is set every 7m depth.

[0081] S400: Environmental impact assessment, which involves a comprehensive evaluation of leachate, odor, dust, noise, and secondary pollution.

[0082] In this embodiment, the environmental impact assessment is conducted by comprehensively evaluating leachate, odor, dust, noise, and secondary pollution. The specific process is as follows:

[0083] S401: Evaluate the leachate collection, drainage, and treatment capacity and the effectiveness of rainwater and sewage separation, and calculate the risk of groundwater pollution spread. The leachate collection slope is ≥2%, the equalization tank capacity is sufficient for more than 7 days of storage, the rainwater and sewage separation efficiency is ≥95%, and there are 6 groundwater monitoring wells.

[0084] S402: Calculate the intensity of the odor source, verify the coverage of the deodorization equipment, the temporary coverage and sealing of the work surface, and the compliance of the site boundary. Among these, the odor concentration must be ≤20, the fog cannon spray radius must be ≥30m, the agent spraying rate must be 20~35L / min, and the work surface coverage and sealing rate must be 100%.

[0085] S403: Evaluate the effectiveness of construction machinery noise, road dust control, vehicle washing and closed transportation measures, where construction noise is ≤70dB, road watering frequency for dust suppression is ≥3 times / day, vehicles leaving the site are 100% washed, and tires are free of mud.

[0086] S404: Verify the waste transfer, screening residue and hazardous waste identification, with 100% closed waste transportation rate, screening impurity content ≤10%, hazardous waste identification rate 100%, and entrusted to qualified units for disposal.

[0087] In the above process, the following steps were taken: First, the capacity for leachate collection, drainage, and treatment, as well as the effectiveness of rainwater and sewage separation, were assessed, and the risk of groundwater pollution spread was calculated. Specifically, the leachate collection slope was ≥2%, the equalization tank capacity was sufficient for at least 7 days of storage, the rainwater and sewage separation efficiency was ≥95%, and 6 groundwater monitoring wells were used. Next, the intensity of odor sources was calculated, and the coverage of deodorization equipment, the temporary sealing of the work surface, and the compliance of the site boundary were verified. Specifically, the odor concentration was ≤20, the spray radius of the mist cannon was ≥30m, the chemical spraying rate was 20~35L / min, and the sealing rate of the work surface was 100%. Then, the effectiveness of construction machinery noise, road dust control, vehicle washing, and closed-loop transportation measures was assessed. Specifically, construction noise was ≤70dB, the frequency of road watering for dust suppression was ≥3 times / day, 100% of vehicles leaving the site were washed, and tires were free of mud. Finally, the waste transfer, screening residue, and hazardous waste identification were verified. Specifically, the closed-loop transportation rate of waste was 100%, the content of screening impurities was ≤10%, the hazardous waste identification rate was 100%, and a qualified unit was entrusted with disposal.

[0088] S500: Assess the suitability of construction and disposal, match the optimal excavation, seepage prevention, drainage, and rainwater and sewage separation processes, and determine the waste screening and resource recovery disposal path.

[0089] In this embodiment, the suitability assessment of construction and disposal is conducted to match the optimal excavation, seepage prevention, drainage, and rainwater and sewage separation processes, and the waste screening and resource recovery disposal pathways are determined. The specific process is as follows:

[0090] S501: Excavation shall be carried out according to the conditions of the pile body. The excavation method shall be zoning + layered shallow excavation, and the width of the transport ramp shall be ≥5m.

[0091] S502: Matching the repair and welding inspection process for groundwater blind drains, leachate collection pipes, and HDPE membranes, wherein the slope of the groundwater blind drain is ≥2%, the main leachate pipe is DN400 and the branch pipe is DN200 HDPE perforated pipe, and the HDPE membrane welding pressure test is 0.25MPa, with pressure holding for 3~5min;

[0092] S503: Design a rainwater and sewage separation system consisting of temporary covering, flexible drainage ditches, intercepting ditches, and sump pits for forced drainage. The rainwater and sewage separation system is covered with a 1.0mm thick HDPE membrane. The temporary drainage ditch dimensions are 0.4m×0.4m~1.0m×0.6m. The forced drainage capacity of the sump pit meets the storm return period P=1.

[0093] S504: The grading process adopts a drum screen + air classification process to determine the path of incineration of oversize material, backfilling / resource utilization of undersize material, and outsourced disposal of hazardous waste. The particle size division is 60mm / 80mm. 60% of the oversize material is transported off-site for incineration, and 40% of the undersize material is backfilled on-site. The moisture content is controlled to be ≤40%.

[0094] In the above process, excavation is first carried out according to the conditions of the pile body. The excavation method adopts zoning + layering shallow excavation, and the width of the transport walkway is ≥5m. Matching is the process for groundwater blind drains, leachate collection pipes, HDPE membrane repair, and welding inspection. The slope of the groundwater blind drain is ≥2%, the main leachate pipe is DN400, and the branch pipes are DN200 HDPE perforated pipes. HDPE membrane welding pressure testing is performed at 0.25MPa, with pressure holding for 3~5min. Temporary covering, flexible drainage ditches, intercepting ditches, and sump pits are designed for strong drainage. The system employs a separate stormwater and sewage system, with the stormwater and sewage separated by a 1.0mm thick HDPE membrane. Temporary drainage ditches range in size from 0.4m×0.4m to 1.0m×0.6m, and the sump has a strong drainage capacity that meets the storm recurrence interval P=1. Next, a drum screen + air classification process is used for grading to determine the pathways for incineration of oversize material, backfilling / resource recovery of undersize material, and outsourced hazardous waste disposal. The particle size separation is 60mm / 80mm. 60% of the oversize material is transported off-site for incineration, and 40% of the undersize material is backfilled on-site. The moisture content is controlled to ≤40%.

[0095] S600: Economic and schedule assessment, calculation of total project cost and reasonable schedule, verification of implementation feasibility and cost-effectiveness.

[0096] In this implementation method, the economic and schedule assessments are conducted to calculate the total project cost and reasonable schedule, and to verify the feasibility and cost-effectiveness of implementation. The specific process is as follows:

[0097] S601: Calculate the costs of exploration, pretreatment, excavation, screening, transportation, environmental protection, testing, and emergency response through itemized accounting;

[0098] S602: Based on daily excavation and screening capacity, equipment and personnel configuration, calculate the baseline construction period and allow for the rainy season and environmental protection constraints, with a daily processing capacity of 1000~4500m³. 3 The equipment configuration includes 2-4 excavators, 8-15 transfer vehicles, and 1-2 screening lines;

[0099] S603: Calculate the unit volume treatment cost and resource-saving cost, and evaluate the overall cost-effectiveness. The construction period is calculated by dividing the total amount by the daily production capacity, with a 15%~20% margin reserved for the rainy season, and the total construction period deviation is ≤±10%.

[0100] S604: Conduct an economic assessment, where the cost of resource resolution accounts for ≥15%, and the unit disposal cost is lower than the industry average.

[0101] In the above process, the costs of exploration, pretreatment, excavation, screening, transportation, environmental protection, testing, and emergency response are first calculated item by item. Then, based on the daily excavation and screening capacity, equipment, and personnel configuration, the baseline construction period is calculated, with allowances made for the rainy season and environmental constraints. The daily processing capacity is 1000~4500m³. 3The equipment configuration includes 2-4 excavators, 8-15 transport vehicles, and 1-2 screening lines. The unit volume treatment cost and resource-saving cost are then calculated to evaluate the overall cost-effectiveness. The construction period is calculated as total volume ÷ daily production capacity, with a 15%-20% margin for the rainy season. The total construction period deviation is ≤±10%.

[0102] Subsequently, an economic assessment was conducted, in which the cost of resource resolution accounted for ≥15%, and the unit disposal cost was lower than the industry average.

[0103] S700: Real-time monitoring and weighted scoring of the entire process, graded assessment of excavation feasibility, and output of a complete implementation plan.

[0104] In this implementation method, the entire process is monitored in real time and weighted, the feasibility of excavation is determined in stages, and a complete implementation plan is output. The specific process is as follows:

[0105] S701: Dynamically monitor methane concentration, slope displacement, leachate level, groundwater quality, odor concentration and seepage prevention integrity, with a monitoring frequency of once per day;

[0106] S702: The comprehensive score is calculated by weighting indicators of stabilization, safety, environment, construction, and economy. The weighted scores are as follows: stabilization 20%, safety 30%, environment 25%, construction 15%, and economy 10%.

[0107] S703: Classification and judgment shall be carried out, of which ≥80 points are Grade A and can be excavated directly, 60~79 points are Grade B and can be excavated after rectification, and <60 points are Grade C and excavation is prohibited.

[0108] S704: Output feasibility report, construction plan, disposal plan, risk control list and emergency plan.

[0109] In the above process, methane concentration, slope displacement, leachate level, groundwater quality, odor concentration, and seepage prevention integrity are dynamically monitored once a day. Then, a comprehensive score is calculated by weighting indicators of stabilization, safety, environment, construction, and economy, with the weighted scores as follows: stabilization 20%, safety 30%, environment 25%, construction 15%, and economy 10%. After that, a classification judgment is made, with scores ≥80 being Grade A (direct excavation allowed), 60-79 being Grade B (excavation after rectification), and <60 being Grade C (excavation prohibited). Finally, a feasibility report, construction plan, disposal plan, risk control list, and emergency plan are output.

[0110] Other embodiments of this application will readily occur to those skilled in the art upon consideration of the specification and practice of the disclosure herein. This application is intended to cover any variations, uses, or adaptations of this application that follow the general principles of this application and include common knowledge or customary techniques in the art not disclosed herein.

[0111] It should be understood that this application is not limited to the precise structure described above and shown in the accompanying drawings, and various modifications and changes can be made without departing from its scope.

Claims

1. A comprehensive evaluation method for municipal solid waste landfill excavation, characterized in that, Includes the following steps: Conduct a comprehensive survey of landfills, including engineering, waste, environmental and external conditions, and establish a complete basic database. The landfill stabilization assessment is conducted based on indicators such as methane concentration and organic matter to determine the stabilization level of the landfill and whether it can be excavated and whether pretreatment is required. The safety risk assessment for excavation quantifies the risks from four aspects: stockpile stability, gas explosion prevention, seepage prevention, and slope collapse prevention, and provides control requirements. The environmental impact assessment involves a comprehensive evaluation of leachate, odor, dust, noise, and secondary pollution. The suitability assessment of construction and disposal was conducted to match the optimal excavation, seepage prevention, drainage, and rainwater and sewage separation processes, and to determine the waste screening and resource recovery disposal pathways. Economic and schedule assessments were conducted to calculate the total project cost and reasonable schedule, and to verify the feasibility and cost-effectiveness of implementation. The entire process is monitored in real time and weighted, and the feasibility of excavation is determined by level, and a complete implementation plan is output.

2. The comprehensive evaluation method for municipal solid waste landfill excavation as described in claim 1, characterized in that, In the process of conducting a comprehensive survey of the landfill's engineering, waste, environment, and external conditions, and establishing a complete basic database: Collect data on the volume of the pile, the height of the pile, the slope gradient, the bearing capacity of the stratum, the groundwater level, the thickness / type of the geomembrane, the size of the drainage blind ditch, the diameter of the HDPE pipe, and the spacing and number of the gas wells. The tests included the landfill age, waste composition percentage, moisture content (35%–60%), organic matter content (5%–30%), and compaction density (≥0.8 t / m³). 3 and degree of mineralization; Monitor groundwater pH, ammonia nitrogen, and heavy metals; leachate COD, BOD5, ammonia nitrogen, and SS; atmospheric ammonia, hydrogen sulfide, and odor concentrations; and soil heavy metal and organic matter indicators. Statistics include transportation distance, incineration / disposal / backfill site capacity, distance to surrounding sensitive points, road weight limits, and traffic conditions.

3. The comprehensive evaluation method for municipal solid waste landfill excavation as described in claim 1, characterized in that, In the process of landfill stabilization assessment, which determines the stabilization level of the landfill based on indicators such as methane concentration and organic matter, and determines whether excavation is permissible and whether pretreatment is required: The methane concentration, organic matter content, leachate yield, and pile settling rate are all measured to be ≤5 mm / month. A classification system is implemented, with levels including high stability, medium stability, and low stability. High stability includes: Methane < 5%, organic matter < 10%; Medium stabilization: methane 5%~15%, organic matter 10%~20%; Low stabilization: methane >15%, organic matter >20%; The treatment is based on the severity level: high stability requires direct excavation; medium stability requires forced aeration followed by aerobic pretreatment before excavation; and low stability requires prohibition of excavation and continued pretreatment.

4. The comprehensive evaluation method for municipal solid waste landfill excavation as described in claim 1, characterized in that, In the excavation safety risk assessment, the steps involved quantifying risks from four aspects: stockpile stability, gas explosion prevention, seepage prevention, and slope collapse prevention, and providing control requirements: Calculate the safety factor of the pile body slope, where the slope safety factor is ≥1.2, the slope gradient is ≤1:3, the layered excavation thickness is ≤1.5~3.0m, the platform width is ≥3m, and the platform height difference is 5~10m; The methane explosion warning threshold is set at 5%, the methane level at the working face is <5%, the longitudinal and transverse spacing of the gas wells is 30m, and they are arranged in a quincunx pattern. Delineate the protection zone of the geomembrane. Mechanical excavation is strictly prohibited within 1.0m of the HDPE geomembrane. The thickness of the protective layer on the geomembrane should be ≥300mm. In the working pit, a 30° mechanical ramp is reserved according to the slope ratio of 1:3, and a 12m×6m working platform is set up every 7m of depth.

5. The comprehensive evaluation method for municipal solid waste landfill excavation as described in claim 1, characterized in that, In the environmental impact assessment, a comprehensive evaluation of leachate, odor, dust, noise, and secondary pollution is conducted: The leachate collection, drainage, and treatment capacity and the effect of rainwater and sewage separation were assessed, and the risk of groundwater pollution spread was calculated. The leachate collection slope was ≥2%, the equalization tank capacity was sufficient for more than 7 days of storage, the rainwater and sewage separation efficiency was ≥95%, and there were 6 groundwater monitoring wells. Calculate the intensity of the odor source, verify the coverage of the deodorization equipment, the temporary coverage and sealing of the work surface, and the compliance of the site boundary. Among these, the odor concentration should be ≤20, the spray radius of the fog cannon should be ≥30m, the agent spraying rate should be 20~35L / min, and the coverage and sealing rate of the work surface should be 100%. The effectiveness of construction machinery noise, road dust control, vehicle washing and closed transportation measures was evaluated, with construction noise ≤70dB, road watering frequency ≥3 times / day, 100% washing of vehicles leaving the site, and tires free of mud. Verify the waste transfer, screening residue, and hazardous waste identification, with 100% of waste being transported in a sealed manner, screening impurities content ≤10%, and hazardous waste identification rate 100%, and entrust qualified units to handle the waste.

6. The comprehensive evaluation method for municipal solid waste landfill excavation as described in claim 1, characterized in that, In the steps of assessing the compatibility between construction and disposal, matching the optimal excavation, seepage prevention, drainage, and rainwater / sewage separation processes, and determining the waste screening and resource recovery pathways: Excavation shall be carried out according to the conditions of the pile body, and the excavation method shall be zoning + layering shallow excavation, with the width of the transport ramp ≥ 5m; Matching the groundwater blind drain, leachate collection pipe, HDPE membrane repair and welding inspection process, wherein the groundwater blind drain slope is ≥2%, the leachate main pipe is DN400 and the branch pipe is DN200 HDPE perforated pipe, and the HDPE membrane welding air pressure test is 0.25MPa, with pressure holding for 3~5min; The design incorporates a rainwater and sewage separation system consisting of temporary coverings, flexible drainage ditches, intercepting ditches, and sump pits for forced drainage. The rainwater and sewage separation system uses a 1.0mm thick HDPE membrane for covering. The temporary drainage ditches are 0.4m×0.4m~1.0m×0.6m in size, and the sump pits have a forced drainage capacity that meets the storm return period P=1. The grading process is based on a drum screen and air classification. The path for the oversize material to be incinerated, the undersize material to be backfilled / resourced, and the hazardous waste to be outsourced for disposal is determined. The particle size is divided into 60mm and 80mm. 60% of the oversize material is transported off-site for incineration, and 40% of the undersize material is backfilled on-site. The moisture content is controlled to be ≤40%.

7. The comprehensive evaluation method for municipal solid waste landfill excavation as described in claim 1, characterized in that, In the steps of economic and schedule assessment, calculating total project cost and reasonable schedule, and verifying implementation feasibility and cost-effectiveness: The costs of exploration, pretreatment, excavation, screening, transportation, environmental protection, testing, and emergency response are calculated separately. Based on the daily excavation and screening capacity, equipment and personnel configuration, the baseline construction period is calculated and a margin is reserved for the rainy season and environmental protection constraints. The daily processing capacity is 1000~4500m³, and the equipment configuration includes 2~4 excavators, 8~15 transfer vehicles, and 1~2 screening lines. Calculate the unit volume treatment cost and resource-saving cost, and evaluate the overall cost-effectiveness. The construction period is calculated by dividing the total amount by the daily production capacity, with a 15% to 20% margin reserved for the rainy season, and the total construction period deviation is ≤ ±10%. An economic assessment was conducted, with the provincial cost of resource resolution accounting for ≥15% and the unit disposal cost being lower than the industry average.

8. The comprehensive evaluation method for municipal solid waste landfill excavation as described in claim 1, characterized in that, The process involves real-time monitoring and weighted scoring of the entire process, tiered assessment of excavation feasibility, and output of a complete implementation plan. Dynamically monitor methane concentration, slope displacement, leachate level, groundwater quality, odor concentration, and seepage prevention integrity, with a monitoring frequency of once per day; The comprehensive score is calculated by weighting indicators such as stabilization, safety, environment, construction, and economy. The weighted scores are as follows: stabilization 20%, safety 30%, environment 25%, construction 15%, and economy 10%. The classification is as follows: ≥80 points is Grade A, which allows direct excavation; 60~79 points is Grade B, which requires rectification before excavation; <60 points is Grade C, which prohibits excavation. Output feasibility reports, construction plans, disposal plans, risk control lists, and emergency response plans.

Images