Some standard content:
Industry Standard of the People's Republic of China
Design Regulations for Chemical Waste Landfill
HG 20504-92
Main Editor: Environmental Protection Design Technology Center of the Ministry of Chemical Industry Approving Department: Ministry of Chemical Industry
National Studies Industry
Engineering Construction Standard Editing Center of the Ministry of Chemical Industry
1 General Provisions
1.0.1 These regulations are formulated in accordance with the "Environmental Protection Law of the People's Republic of China", "Environmental Protection Design Regulations for Construction Projects" and "Chemical Industry Environmental Protection Management Regulations" and other documents. 1.0.2 These regulations are intended to prevent harmful solid wastes generated in chemical production from causing harm to human health and the environment.
1.0.3 These regulations apply to all new, expanded and renovated chemical construction projects, including foreign-funded, Sino-foreign joint ventures and imported projects.
1.0.4 In addition to complying with these regulations, the design of chemical waste landfills shall also comply with the relevant laws, decrees, standards and specifications currently in force in the country and the Ministry of Chemical Industry. 2 Site selection
2.1 General provisions
2.1.1 The site selection requires a reasonable layout and should not hinder the normal production of the factory. 2.1.2 The waste residue landfill (hereinafter referred to as the landfill) should be arranged on the leeward side of the dominant wind direction throughout the year or in summer or on the upwind side of the minimum wind frequency in the chemical production area. 2.1.3 A sanitary protection distance should be set between the landfill and the residential area. Its width should be determined in accordance with the provisions of the current national "Technical Principles and Methods for Formulating Local Air Pollutant Emission Standards" (GB3840-83). Green protection forest belts should be set in places with conditions. 2.1.4 The landfill should be more than 60m away from the land boundary and must be outside the water source sanitary protection belt. The water source sanitary protection belt can refer to the "Sanitary Standards for Drinking Water" (GB5749-85). 2.1.5 The landfill selection should make full use of natural conditions, minimize the amount of earthwork, and make the dam construction work small and convenient.
2.1.6 Do not choose a site near an airport or military test site to avoid accidents. It should be far away from warehouses and tank areas for inflammable and explosive dangerous goods, and away from high-voltage transmission lines. 51
2.1.7 It should avoid precious areas of archaeological, historical, and paleontological interest, precious animal and plant habitats, humid areas, and various protected areas and tourist scenic spots. 2.1.8 It should be far away from cities, and considering urban planning and development, it should avoid residential areas and intersection areas (parks, scenic areas), cultural and educational areas. 2.2 Hydrogeological requirements
2.2.1 The filling site should be selected in an area with stable engineering geological conditions and low construction costs. It should avoid ground haze areas, sliding areas, fault areas, and areas with mineral deposits, limestone pits and karst caves below. Avoid being affected by mudslides, volcanoes, tides, etc. 2.2.2 The soil near the site should be as low-permeability soil as possible (clay, sandy clay, etc.). wwW.bzxz.Net
2.2.3 The landfill site should be located in an area with low groundwater level. The foundation of the structure must be 1.5m above the groundwater level. It should avoid the dedicated water source aquifer and groundwater recharge area, and try to choose it downstream of the local drinking water source. 2.2.4 Choose an area that will not be flooded, and must be outside the 100-year flood zone. 2.3 Preliminary work for site selection
2.3.1 The site selection of the landfill should take into account the local natural environment and social environment. Before the site selection, the topography, landform, geology, hydrometeorology, industrial and agricultural layout, urban and rural planning, and the status of nature reserves in the proposed site area should be investigated. On the basis of collecting background data on basic environmental elements such as the local atmosphere, water bodies, and upper soil, a comprehensive analysis and demonstration should be conducted to formulate a site selection plan that may have the least impact on the environment. 2:3.2 Before determining the site, the hydrogeological conditions of the landfill site must be ascertained, existing data must be collected and analyzed, and on-site surveys must be conducted. Based on the field investigation, hydrogeological exploration is carried out through various drilling technologies to further evaluate the impact of the construction of the slag dump on groundwater resources, and reasonable anti-seepage measures are proposed to provide a basis for the technical design and construction design of the slag dump. 52
2.3.3 Draw a more detailed site map based on the survey data. The main contents of the site map should be marked as follows:
a. Contour lines: b. Land boundaries: c. Roads: d. Existing or planned above-ground or underground public facilities: e. Groundwater discharge outlets: f. Groundwater flow direction: g. Wells, springs; swamps; i. Civilian water supply, . Quarries, sand and gravel pits, earth piles, k. Underground and surface mineral deposits, natural gas and oil wells; 1. Buildings, walls. 2.3.4 Determination of site area
2.3.4.1 The site should be large enough to accommodate the waste generated during the use of the production equipment, meet the overall layout requirements, and leave appropriate space according to the plan for future expansion.
2.3.4.2 The service life of the effective landfill area should be between 10 and 20 years. 2.3.4.3 After the area of the effective landfill area is determined, it is also necessary to consider retaining an appropriate buffer zone and determine the site boundary according to the corresponding standards. The landfill area should be at least 15 meters away from the boundary.
2.3.4.4 In addition to the buffer zone, 5% to 10% of the area is reserved for auxiliary operations.
3 Requirements for landfill materials
3.0.1 The moisture content, solid content, permeability, etc. of the landfilled waste should not affect the long-term stability of the waste itself.
3.0.2 The landfill should not dispose of combustible waste, reactive waste, volatile waste, most liquids, semi-liquids, and sludge.
3.0.3 For wastes with high toxicity, they must be properly pre-treated before they can be sent to the landfill for disposal. It is strictly forbidden to landfill wastes with special toxicity and radioactivity. 3.0.4 When two or more wastes are mixed, they should be compatible and will not react, burn, explode or emit harmful gases. 53
3.0.5 Wastes such as garbage generated in the production area, construction residues, boiler ash and slag that do not contain toxic and harmful pollutants shall not be sent to the landfill. 4 Design and operation of structures
4.1 Design of village cushion layer
In order to prevent the waste residue filtrate from polluting the groundwater, the slag yard should be equipped with an impermeable cushion layer. The cushion layer can be a natural lining of a single low-permeability earth weir, or an artificial lining of artificial synthetic materials, or a composite lining composed of natural and artificial synthetic materials. 4.1.1 Natural lining system
4.1.1.1 The natural lining system can only be used when the soil and hydrogeological conditions of the site allow it. The general requirement is that the natural evaporation should exceed the precipitation by 50cm, and the design of the natural lining system should meet the following principles. (1) Clay is laid and compacted at the bottom and sides of the landfill. The permeability coefficient of the compacted clay should be less than 10 cm/s, the thickness should be at least 1 m, and the bottom should be at least 1.5 m from the highest groundwater level.
(2) In addition to low permeability, the natural soil lining should also meet relevant soil standards, requiring the clay particle content of the soil to be greater than 30%, the liquid limit to be greater than 30%, the plasticity index to be greater than 17, and the pH ≥ 7.
(3) The natural lining should be compatible with the expected leaching solution. Permeability should not increase due to contact with the leaching solution.
4.1.2 Artificial lining system
4.1.2.1 Artificial lining shall meet the following requirements: (1) Permeability coefficient less than 10-7cm/s
(2) Appropriate strength:
(3) Laid on a stable foundation;
Resistant to erosion by ozone, ultraviolet rays, soil bacteria and fungi:
(4)
(5) Appropriate weather resistance, able to withstand rapid changes in temperature; (6) Sufficient tensile strength to withstand the pressure of the entire facility and the impact of filling machinery and equipment. The pressure of the equipment
can resist the puncture, wear and scratch of various substances that may be contained in the waste (7)
(8) To ensure that the joints are continuous and have appropriate strength, all joints should be able to be inspected during the lining assembly process: (9) The thickness is uniform, without thin spots, cracks, and wear: (10) Under special conditions, in order to ensure long-term use, it should have sufficient thickness. The thickness of the organic lining should generally not be less than 0.5mn (11) It has sufficient chemical stability and can resist corrosion from various substances in the waste.
4.1.3 Composite lining system
For poor hydrogeological conditions, high environmental protection requirements, and no other slag dump with good conditions available, the lining layer can consider using a composite lining. The technical requirements of the composite lining should be the same as those of the natural lining and the artificial lining. 4.2 Design of leachate collection and control system
4.2.1 The leachate collection system shall be able to collect all leachate that may be leached and flow smoothly to the treatment device or disposal site.
4.2.2 A single-layer leachate collection system may be set up for a single-layer leachate collection system, and a double-layer leachate collection system shall be set up for a composite lining.
4.2.3 The design of the leachate collection system may refer to the following requirements: 4.2.3.1 The liner should have a slope of 1% so that the overflowing liquid can flow into the collection location along the slope by gravity.
4.2.3.2 In order to protect the liner and allow the leachate to flow quickly into the collection pit, a protective layer composed of permeable gravel or sandy soil can be set on the liner. The thickness is generally about 30cm and the slope is 1%:
4.2.3.3 A porous pipe drainage system can also be set in the permeable layer so that the leachate can be collected in the collection pit more quickly:
4.2.3.4 The capacity of the collection pit should be greater than the expected leachate volume for three months. 4.2.3.5 When the pump or riser is damaged, the leachate should be easily removed; 4.2.3.6 The leachate should be pumped out regularly to reduce the hydraulic pressure of the liner. The leachate must be treated and qualified before it can be discharged.
4.3 Gas collection and control system design
For waste landfills that emit harmful gases such as methane, carbon dioxide, hydrogen sulfide and odor during storage, a waste gas collection system should be designed. Commonly used gas collection systems are permeable exhaust and impermeable barrier exhaust. 4.3.1 Permeable exhaust
In the design of permeable exhaust system, gravel and other materials with good permeability should be used as fillers to build exhaust channels. The spacing of exhaust channels is generally 20m~150m, and the thickness of the gravel layer is 30cm~45cm.
4.3.2 Impermeable exhaust
Impermeable exhaust means that the vertical exhaust pipe is introduced from the top cover layer of the impermeable landfill and communicated with the horizontal porous pipe set under the cover layer. The spacing of the horizontal porous pipe can be determined according to the size of the site, the gas generation rate and the gas permeability of the filler. 4.4 Design of surface water diversion system
4.4.1 In order to prevent surface runoff water from entering the landfill and reduce leachate, the landfill should be equipped with engineering barriers such as diversion channels, surface stabilization, underground drainage and diversion dams to divert surface runoff water.
4.4.2 The design of the diversion system is determined by the site characteristics such as the permeability and adsorption of local rock and soil, and the surface water runoff and flow rate. It must ensure that all surface water in the disposal site can be drained away smoothly.
4.4.3 Usually the runoff water is collected in the diversion channel, which should be excavated around the entire site. The construction materials of the channel can be natural soil lining with grass, soil lining asphalt, crushed stone concrete or asphalt fragments. In addition, metal corrugated pipes separated from it can be used as temporary drainage facilities.
The size of the runoff channel can be calculated using 25-year or 50-year storm data. 4.4.4 The final cover material should be selected in the surface stabilization design to minimize the penetration and erosion of the cover. 4.4.5 For rainwater that has penetrated the surface cover layer, a series of porous pipes can be laid under the cover layer above the fill field to discharge it into the collection system. 4.4.6 Stream dams can also be built around the site to intercept surface runoff water and divert it into drainage and facilities. The diversion dam design should prevent the diversion water from contacting the filtrate. 4.5 Dam design
4.5.1 If the terrain conditions require dam construction, a slag dam can be set up. The selection of the slag dam site should be based on the principle of small dam construction (pile) engineering volume, the formed reservoir capacity and avoidance of adverse engineering geology and hydrogeology conditions, and comprehensively consider factors such as the source of dam construction materials, construction conditions and the layout of drainage structures.
4.5.2 The slope of the inner and outer slopes of the slag dam should be determined by stability calculation based on factors such as the physical and mechanical properties of the dam construction materials and foundation soil and the dam construction rise speed. It should be able to resist all loads acting on the dam.
4.5.3 The slag dam should be equipped with the same anti-seepage facilities as the lining layer to avoid leakage. The outer slope of the slag dam and the intersection of the bank slope should be equipped with drainage ditches and intercepting ditches to drain water to the outside of the dam foot to avoid scouring the foundation.
4.5.4 The outer slope of the slag column and the dam top should be different according to the dam construction materials, and combined with the dam drainage facilities, turf planting or gravel slope protection should be considered.
4.6 Design of auxiliary facilities
4.6.1 Rainwater interception ditches should be set up around the landfill to ensure that the flood is drained in time. The rainfall duration of the design flood is generally calculated as 24 hours. 4.6.2 The access roads of the landfill should be designed as permanent all-weather roads with appropriate width and bearing capacity, which can provide two-way transportation and avoid transportation blockage. The specific design can refer to the provisions of the "Design Code for Factory and Mine Roads" (GBJ22-87). 4.6.3· Equipment maintenance and storage places, staff rest rooms and sanitary facilities should be set up near the landfill or within a suitable distance. 4.6.4 Public facilities such as power, water, radio and telephone should be equipped. 4.6.5 A weighing room should be set up to record and measure the amount of waste transported to the site. 4.6.6 Cleaning facilities for transport vehicles and water spraying facilities to prevent dust can be set up. 4.6.7 In order to ensure the smooth progress of landfill, the landfill should have certain mechanical equipment. Commonly used equipment includes crawler and tire bulldozers, scrapers, and road machines, which can be selected according to specific needs.
4.6.8 The landfill should be equipped with walls, window whistles or other natural barriers to prevent the entry of idle people and livestock.
4.7 Filling operation
4.7.1 The landfill operation of waste should be determined based on the characteristics of the landfill site terrain conditions, climate conditions, hydrogeological conditions and the properties of the lining materials. 4.7.2 In flat areas, landfilling from bottom to top or from one end to the other can be selected. The method of starting from one end and pushing forward to the other end has the advantage of reducing the exposure time of waste and helping to reduce leaching liquid. 4.7.3 In sloped areas or canyon areas, landfilling from the uphill end to the downhill end can be selected. This will not accumulate surface water and reduce leaching liquid. 58
4.7.4 When handling relatively wet solid waste, pre-landfilling pretreatment or adding adsorbent desiccant must be carried out, or a rotating work area system must be adopted to ensure smooth landfilling. 4.7.5 When handling relatively dry solid waste, attention should be paid to dust prevention, and dust from hazardous waste should be strictly limited. Dust from harmless waste can be controlled by spraying water or dust removers. 4.7.6 When handling barreled solid (or paste) materials, a forklift or loader should be used to place the barrels in a regular pattern, and sufficient adsorbents should be placed around the barrels containing waste liquid to prepare for leaking waste.
4.7.7 Two or more incompatible wastes should be landfilled separately. Wastes in containers and wastes not in containers should also be placed separately, and the landfill location and placement time should be recorded in detail.
4.7.8 In order to ensure the smooth progress of landfill operations, a complete landfill operation plan must be formulated to specify the operating procedures, records, blue detection procedures, accident handling and safety measures for operators according to the landfill method selected in the design. 5 Closure
5.0.1 Closure should be considered together with surface water management, leachate collection, blue detection and gas control measures.
5.0.2 When the landfill is closed, a 15cm thick layer of permeability of 10-7cm/s should be covered on the landfill. In order to better prevent the infiltration of surface water, an organic liner can also be laid. A 45cm thick natural topsoil is then covered on it to support the growth of ten-plants.
5.0.3 When planting shallow-rooted plants on the landfill after site closure, a 15cm thick surface soil must be laid on top of the two covering layers. If deep-rooted plants are planted, a surface soil at least 1m thick must be laid on top. 5.0.4 The final slope of the final covering layer should not exceed 33%. 5.0.5 In order to prevent the slope from being too steep and causing rainwater to scour the covering layer, a buffer platform 59
steps can be appropriately constructed. The steps should be of sufficient width and strength to withstand the largest storm within 24 hours once in 25 years.
5.0.6 The design standards of the site should be maintained for at least 20 years after site closure, and the groundwater and leachate detection system and the gas monitoring and collection system should continue to operate normally.
5.0.7 After site closure, the soil should continue to be leveled, and the slope covering vegetation and surface water diversion facilities should be protected.
5.0.8 The roads leading to the landfill should be restricted and the original signs should be maintained. 6 Site Monitoring System
The impact of waste landfill on the environment is mainly reflected in the pollution of groundwater. Therefore, site blue monitoring is mainly the monitoring of groundwater. Groundwater blue monitoring should include background blue monitoring, aeration zone monitoring and saturation zone monitoring. 6.1 Background Monitoring
6.1.1 The background monitoring well is located in the hydraulic uphill area of the landfill so that the sampling can represent the basic properties of the groundwater flowing through the site and provide background data. 6.1.2 The setting of the background monitoring well is generally no more than 3km away from the site. The depth can be determined according to the hydrogeological conditions of the site and should be 3m below the groundwater level so that sampling can be carried out at any time within one year.
6.1.3 Background monitoring is best carried out before the landfill operation begins to truly reflect the natural conditions. Sampling can be carried out every month for full analysis, and land filling disposal can be carried out three months later. 6.2 Saturation zone blue test
6.2.1. Saturated zone monitoring refers to the monitoring of groundwater in the hydraulic downslope area of the site. The purpose is to monitor whether the groundwater is contaminated by harmful substances leached from the site. 6.2.2 The structure of the saturated zone monitoring well is similar to that of the background monitoring well. The depth should be below the groundwater level so as not to be affected by regional water level fluctuations. 6.2.3 The saturated zone monitoring wells should include at least three wells. One well provides data on leachate diluted by groundwater far away from the site, and the other two wells are close to the site to provide groundwater data directly affected by the site. If the site is large, the number of monitoring wells can be appropriately increased.
6.3 Aerated zone monitoring
6.3.1 The aerated zone refers to the soil layer between the land surface and the groundwater level. The soil voids in this area are partially filled with air and water, and the leachate must pass through it to enter the groundwater.
6.3.2 Aerated zone monitoring is mainly carried out using pressure vacuum water seepers. The water seepage device can be set up along the periphery of the landfill site, preferably directly under the landfill lining, but the integrity of the lining system should not be damaged. 6.3.3 In order to facilitate sampling and grasp the migration position of the reaction leachate, several water seepage devices can be set up vertically in the same monitoring well.
6.4 Sampling and analysis
6.4.1 Monitoring and analysis are divided into two categories. One is key factor analysis and the other is full analysis. 6.4.2 Key factor analysis is to detect signs of water pollution early based on obvious changes in one or more parameters of water quality through selective analysis, which can reduce costs. 6.4.3. Key analysis should include the following parameters: a. Specific conductivity, b. pH; c. Chloride: d. Heavy metals: e. Total organic carbon f. Main harmful components.
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