GB/T 43934-2024Technical specification for land reclamation and ecological restoration of coal mines (English PDF)

3 Terms and definitions

Mine land reclamation and ecological restoration is defined as the activity that, for the geological environment damage, land destruction and ecosystem damage or degradation caused by the extraction of mineral resources, relies on human support and guidance together with natural restorative capacity and takes preventive and restorative measures so that the mine geological environment becomes safe and stable, the destroyed land is reclaimed for use and the ecosystem function is restored or improved; a note abbreviates it to reclamation and restoration.

Land destruction is the process and state in which the original function of the land is partly or wholly lost through mine production and construction activity. Subsided land is the area where underground extraction has caused the overlying strata to move and the surface to deform, damaging the land resource and the ecosystem. A dumping site is the place where the stripped material of open-pit mining is heaped, called an internal dump when it lies inside the open pit and an external dump when outside. An open-pit field is the collective term for the pit, benches and haul roads formed by open-pit extraction. A mine yard is the site occupied by the shaft mouth, the surface production system, the auxiliary production facilities, the processing and transport system and the living service facilities.

Landform reshaping is defined as forming a new landform in harmony with the surrounding landscape, by orderly dumping, backfilling and land shaping, on the basis of eliminating geological safety hazards and soil erosion hazards, according to the way the mine landform has been damaged and the degree of destruction and taking account of the original relief. Soil reconstruction is the reconstitution of the soil matrix on destroyed mine land by engineering, physical, chemical and biological measures so as to form a soil profile and fertility fit for vegetation growth. Vegetation reconstruction is the rebuilding of a lasting and stable plant community by selecting pioneer and site-adapted species and carrying out their arrangement, planting and tending, having regard to climate, altitude, slope, aspect, the composition of the surface material and the thickness of the effective soil layer. Landscape construction is the building, at the hydro-geomorphic scale of the catchment, of an ecosystem in harmony with the surrounding landscape, following the integrated protection and restoration of mountains, rivers, forests, farmland, lakes, grassland and sand, and taking full account of the structural adjustment and optimal allocation of land, water, biological resources and the human settlement environment during the fragmentation and reintegration of the point, line, area and network landscape of the mining area.

Natural restoration is defined as stopping human disturbance of the ecosystem so as to lighten the load, and relying on the self-regulating and self-organizing capacity of the ecosystem to let it succeed and renew itself in an orderly direction. Assisted restoration makes full use of that self-recovery capacity with the help of artificial promoting measures, so that the degraded or damaged ecosystem gradually recovers and enters a virtuous cycle. Ecological reconstruction applies mainly artificial measures to a mining area whose ecological function is impaired and whose self-recovery capacity is lost or irreversibly changed, rebuilding the ecosystem through biological, physical, chemical, ecological or engineering methods around the restoration of habitat, of vegetation and of biodiversity. Adaptive management is the method and process of gaining experience by monitoring and assessing the management and practical measures taken in the past and of correcting and improving them as the ecosystem changes, given the uncertainty of the ecosystem and the time-bound character of what is known about it.

4 General requirements and basic principles

4.1 The work should follow the concept of integrated protection and restoration of mountains, rivers, forests, farmland, lakes, grassland and sand, and hold to the policy of conservation first, protection first and natural recovery as the mainstay. It should regulate reclamation and restoration at working coal mines and, through mitigation and protection, preventive control and reclamation measures, bring reclamation and restoration and the extraction of mineral resources under one plan and one implementation, reclaim destroyed land for use in good time, restore and raise the diversity, stability and sustainability of the ecosystem of the mining area, advance green mine construction and achieve harmony between people and nature.

4.2.1 Protection first and control at source. Following the concept of protecting while developing and developing while protecting, the siting and alignment of mine land and the design of the production process system are to be optimized so as to reduce at the source the effect on sensitive targets such as farmland and permanent basic farmland, basic grassland, key protected species, public welfare forest, protected areas, water sources and cultural relics; sound preventive control measures are to be used to remove geological environment hazards in real time and to prevent and control environmental pollution and soil erosion, reaching a safe, stable and pollution-free condition; and for the ecological problems unavoidably produced during coal mine production and construction, engineering, biological and chemical measures are to be taken to restore the damaged ecosystem.

4.2.2 Unified planning and coordinated implementation. The targets, direction, standards and measures of reclamation and restoration are to be aligned with territorial spatial planning, mineral resource planning, territorial ecological restoration planning, the overall planning of the coal mining area and the mineral resource development and utilization plan, and to be in harmony with the current land use and the surrounding landscape; the design of reclamation and restoration is to be unified with the mining design, and its technical measures and timing closely combined with the extraction process, so that over the whole life of the mine extraction and reclamation proceed together.

4.2.3 Combination of human guidance and natural recovery. According to the stability of the mine geological environment, the suitability for reclamation and the ecological resilience, the principle of farmland where farmland is fit, forest where forest is fit, grassland where grassland is fit, wetland where wetland is fit and construction where construction is fit is to be held to; engineering, biological and chemical means of human support are to bring the damaged land to a usable state and restore ecosystem function, while respecting, conforming to and protecting nature and making full use of natural restorative capacity so that the composition and structure of the local biological community are gradually restored and the restored ecosystem becomes self-maintaining and self-regulating.

4.2.4 Systematic treatment and functional improvement. The damaged ecosystem is to be protected as a whole, restored as a system and treated in an integrated way, having regard to the geological conditions of the coal mine, the physical geography, the land use and the restoration targets together with the mining process and its timing, so that the geological environment becomes stable, the destroyed land is reclaimed and ecosystem function is restored or raised; planning and implementation are to follow the requirements of biodiversity protection, which is to be carried through the whole process of reclamation and restoration by way of landform reshaping, soil reconstruction, vegetation reconstruction and landscape construction.

4.2.5 Public participation and monitoring throughout. Over the whole life of mine development and of reclamation and restoration, contact with the stakeholders is to be kept up and they are to be given active and meaningful opportunities to take part, so that the drafting, implementation, monitoring, evaluation and adaptive management of the plan reflect their views, and progress is to be reported and updated to the wider group of stakeholders so that the fairness and inclusiveness of the whole project are ensured. Representative stakeholders include the affected land users, communities, government, regulators and enterprises of the mining area, together with investors, industry peers, academia and the media.

6 Baseline survey and problem identification and diagnosis

6.1.1 The baseline survey should be carried out before mine construction and extraction, and continuous follow-up survey, monitoring and evaluation should be carried out at the stages of planning and design, plan preparation, reclamation and restoration, and post-closure management and maintenance. A working mine should progressively build a complete database of baseline survey and monitoring, master the local natural conditions and socio-economic setting, and establish the ecological condition before extraction.

6.1.2 The survey of natural conditions covers the hydro-geomorphology of the catchment, the soil condition, the vegetation condition and the landscape condition of the mining area. For the catchment, the extent and degree of the effect of coal extraction are to be determined from the hydrological, geological and geomorphic type features of the catchment in which the mine lies, and parameters such as surface runoff, groundwater depth and water quality features are to be surveyed following GB 3838 and GB/T 14848; the parameters may be obtained from hydrological statistics together with field survey. For the soil, the selection and layout of field sampling points and the sampling method are to be settled according to the actual situation, and the survey covers soil type, profile structure, effective soil thickness, texture, gravel content, organic matter, pH, electrical conductivity, soil environmental quality and erosion status, the determination of the physical and chemical indices following NY/T 1121 in all its parts, the classification and grading of erosion following SL 190, and the soil environmental survey and monitoring methods following HJ/T 166 and HJ 25.2. For the vegetation, remote sensing survey is combined with field survey; vegetation cover may be measured on sample plots following GB/T 26424 or derived from the normalized difference vegetation index of remote sensing imagery, and canopy density may be estimated visually or obtained from imagery of resolution not coarser than 3 m. For the landscape, the survey covers natural habitat connectivity, the habitat quality index, landscape fragmentation, landscape stability and landscape richness, which may be computed from existing land use maps and remote sensing imagery of the mining area.

6.1.3 to 6.1.5 The socio-economic survey covers the population, agricultural population, arable land per head and production conditions of the last three years for the villages inside the mine area and the neighbouring villages affected; the cultural survey covers geological heritage, cultural relics and monuments, ancient villages, historical and cultural conservation sites and scenic areas. The survey of mine production and construction covers the scale and capacity of production, the position of the workings, the mining method, the state of dumping and stockpiling, and the service life or remaining life, following TD/T 1049, TD/T 1031.1, TD/T 1031.2 and TD/T 1031.3. The survey of the geological environment covers both conditions and problems: conditions include stratigraphy and lithology, geological structure, hydrogeology, engineering geology, mine geology and adverse geological phenomena; problems include their type, distribution, scale and features, with attention focused on solid waste, on the soil around coal stockpiles and on groundwater, following DZ/T 0223 and DZ/T 0287.

6.1.6 The survey of land use covers land use and tenure, undamaged ecology as a reference system, ecology already damaged, and land already reclaimed. Damage types include excavation, subsidence, occupation by stockpiles and occupation by construction. The tenure survey is to make clear the type, quantity and quality of land use and the tenure situation, and to state the changes and adjustments of tenure caused by open-pit or underground extraction and by reclamation, following GB/T 21010, TD/T 1031.1 and TD/T 1055-2019; the distribution of arable land and permanent basic farmland is to be surveyed. The survey of undamaged land is to be completed before mine construction and extraction, a working mine taking the undamaged land around it as reference system, following GB/T 43935. The survey of damaged land covers the extent, type, area and degree of the damage, open-pit damage following TD/T 1031.2 and underground damage following TD/T 1031.3, DZ/T 0223, DZ/T 0287 and GB/T 43935, and covering for underground mines the subsidence, occupation and occupied area and degree together with the deformation of surface buildings and structures and the damage to surface water and aquifers. The survey of land already reclaimed covers the measures used, their effect and the investment standard, the state of natural recovery being described chiefly by vegetation type.

6.1.7 The survey of ecological status covers the ecological baseline of the place where the mine lies, including ecosystem condition, ecosystem pattern and biodiversity, together with the ecological conservation red line, protected areas and biodiversity priority areas, so that the ecological function of the region is made clear. Biodiversity is to be surveyed in particular, covering community features such as species diversity, community structure, dominant species, relative abundance, trophic structure and richness, together with key species and their habitats and the invasion of alien species, and the ecological status survey of forest, grassland, wetland and desert ecosystems, with the species, numbers, distribution and habitat of nationally and locally protected wild animals and plants made explicit, following HJ 1167, HJ 1168, HJ 1169 and HJ 1170.

6.2 Problem identification and diagnosis analyses the geological environment, land resource and ecological damage and degradation produced by coal mine construction and extraction. Geological environment problems chiefly include unstable geological bodies, damage to the relief and landscape and damage to aquifers; land resource problems are chiefly excavation, occupation and subsidence; ecological problems chiefly include the destruction of vegetation together with the soil retention, surface drainage, soil and groundwater pollution and loss of animal and plant species that underlie ecological service function. Damage to the area still to be mined is to be predicted so that the type, area and degree can be determined. Diagnosis identifies the cause, type, process, stage and degree of soil degradation from the survey and evaluation of relief and soil after damage, focusing on the difference from the degradation of the original landform, and then determines the degree of damage and the grade of ecological effect from the present state and the prediction, open-pit mines focusing on the damage caused by pit excavation and by dump occupation and underground mines on that caused by subsidence and by gangue occupation, following TD/T 1068.

9 Execution of the works

9.1 Protective measures comprise avoidance, mitigation and the protection of important species and cultural assets. Avoidance requires that the special environments and sensitive protection targets of coal development be identified according to the features of the mine, the ecological function requirements and the environmental sensitivity of the region; sensitive targets include arable land, permanent basic farmland, basic grassland, public welfare forest, nature reserves, the ecological conservation red line, water sources, cultural relics, railways, roads, groundwater, surface water bodies and towns. Mitigation requires that the mining process be optimized so as to reduce or control the amount and extent of disturbance, and that the space of open-pit dumps be optimized and land-saving techniques applied so that internal dumping is reached as soon as possible, internal and external dumps being joined early so that land is used intensively. Protection requires that the important species, cultural landscapes and relics needing protection be identified and that fencing, warning signs, avoidance and reinforcement be used to protect geological heritage and cultural landscapes of major scientific and cultural value.

9.2.1 Comprehensive utilization of solid waste. Resource recovery of solid waste is encouraged, with suitable techniques chosen so that the volume used is increased and the damage to the relief and the occupation of land reduced; what genuinely cannot be used may be employed as backfill. The main solid wastes of coal mining are gangue and coal slime; the slime washed out at the preparation plant is to be dumped in a dispersed way, and neither slime nor gangue is to be dumped in the surface layer of a dump. Pollution prevention and control is to be strengthened, following GB 36600, and where gangue and slime are used as reconstructed soil the soil environmental quality is to follow GB 15618.

9.2.2 and 9.2.3 Species collection and use, and topsoil stripping and vegetation transplanting. Before extraction, germplasm resources of key ecological or economic value are to be assessed from the ecological survey together with introduction and provenance trials, collected or gathered and preserved, if necessary by building a germplasm collection nursery in the mining area, so that genetic resources are not lost, following LY/T 2356 in particular for grassland, alpine and desert coal mining areas short of soil. Topsoil stripping is to follow the principles of local conditions and ecological protection: the soil resource and the soil seed bank are to be valued and protected, surface vegetation and the remaining biota together with naturally recovered vegetation are to be protected and used, and where transplanting is worthwhile trees, shrubs and herbs are to be transplanted before mining. Where the predicted damage involves the soil, the soil is to be stripped for use in areas fit for reclamation, in particular the topsoil layer, the plough layer of arable land, or the humus layer of garden, forest and grassland; the stripping thickness is set from the original topsoil thickness and the intended land use, and may include weathered rock where useful. In high-altitude and cold mining areas, turf stripping, tending and re-covering is to be applied. Stripping and use should follow the rule of stripping all that can be stripped, using what is stripped at once, and stripping, stockpiling and backfilling layer by layer, with a workable arrangement in time, space and cost for stripping, transport, storage, tending and re-covering. Soil survey and evaluation are to precede stripping, following TD/T 1048 and TD/T 1036. Stripped topsoil is to be collected and stored, the stockpile site protected by retaining, covering and drainage works against loss during storage; where storage is long, annual or perennial herbs are to be sown on the pile; stripping, hauling and stockpiling in the rainy season are to be avoided; and the site is to be kept free of grazing, machinery and vehicles and protected against dust, salt cover, inflowing runoff, water and wind erosion and human damage, following GB/T 50434 and GB 51287.

9.2.4 Removal of stress factors covers the prevention and control of geological environment damage, of potential pollution, of soil erosion and of gangue spontaneous combustion. For geological environment damage the requirements are to ascertain the degree of development of collapse, landslide, ground subsidence, ground fissures and of adverse engineering geological conditions such as faults and karst in the pit and the dumps; to require the dump to be stable as a whole, its stability factor designed for the three states of ordinary, rainstorm and earthquake conditions, so that collapse, landslide and uneven settlement are controlled; to apply GB 50197, GB 51114 and DZ/T 0219 to dumps at risk; to determine control measures for goaf subsidence in underground mines and apply protective development measures so that the area and degree of land damage are reduced; to fix the extent and the expected effect of grouting of the goaf according to the surface protection targets and construction requirements; and to design the grouting from the age, depth, extraction thickness, mining method, roof and overburden properties and mechanics, hydrogeology and engineering geology of the goaf, the grouting material being obtained locally and meeting environmental requirements, the surface subsidence reduction technique following GB 51044. For potential pollution, heavily polluted rock and soil are to be treated by wrapping or by burial and not dumped in the surface layer, the burial depth being set by the degree of pollution, the landfill site provided with an impervious layer and a surrounding drainage system so that too much water does not enter during construction; effective measures are to be taken during extraction to prevent pollutants migrating beyond the mine area; existing soil and groundwater pollution is to be treated so that reclamation does not cause secondary pollution; soil whose heavy metal or other toxic and harmful content exceeds the limit is not to be used for reclamation; and the control measures are to follow GB 18599 and the environmental impact assessment report of the mine. For soil erosion, the measures follow the water and soil conservation plan of the mine, the administrative rules on such plans for production and construction projects, and GB 51018, GB 50433, GB/T 50434 and GB/T 16453 in all its parts, the erosion amount following SL 190. For gangue spontaneous combustion, mines at risk are to use a suitable dumping method, with the dumping pattern, the thickness of the gangue layer and the thickness of the soil cover designed so that each layer is covered and compacted and neither air nor water can enter; once the gangue has been dumped to the final design level, a soil layer of thickness suited to the intended land use is to be applied.

9.3 Reclamation and restoration measures are organized as landform reshaping, soil reconstruction, vegetation reconstruction and landscape construction, with separate provisions for open-pit dumps and for the subsided land of underground mines. For open-pit dumps the requirements cover the siting of the dump from the mining design, the rock to soil ratio and the stripping ratio, using a near-natural landform technique with stripping, dumping and shaping carried out by layer, by class and by zone so that geological hazards are removed and the reshaped landform is safe, stable and free of pollution; the siting of the external dump with regard to the hydro-geomorphology of the catchment, close to the pit, without diverting a river and occupying as little basic farmland, basic grassland and public welfare forest as possible, in a valley where conditions allow so that the valley is filled to create land; blasting treatment of a smooth and inclined base before dumping in the internal dump, with base columns, temporary retaining walls and anti-slide piles where needed; the order of dumping, the even advance of the dumping line, the straight or curved crest line, the presence of a supervisor, the exclusion of non-working staff and the safety bund at the unloading edge; the alternation of platforms and slopes so that secondary degradation by wind and water erosion is controlled, the reshaped relief suiting mechanized modern agriculture where conditions allow; drainage works meeting the site requirements, with micro-relief shaping used to increase water storage and control erosion; a final reverse slope of 2° to 3° on the stabilized platform so that platform runoff does not concentrate into gullies on the slope; flexible drainage structures such as dry masonry and gabions on a newly built dump so that deformation and concentrated seepage scour from uneven settlement are reduced; and, for clusters of open-pit mines, an optimized scheme of mutual excavation and dumping that occupies little land and backfills much, drawn up from the progress and advancing limits of the several mines.

9.3 (continued) For the subsided land of underground mines, the requirements cover slope-to-terrace works where the original ground slope is steep, following the terrace bench slope and bank stability standards of the region; the choice of shaping methods among levelling by blocks, deep digging and shallow filling, and backfilling with material; surface levelling of lightly subsided or non-ponded land after topsoil stripping, so that wave-like subsidence, added slope and surface fissures no longer hinder land use, high ground being lowered and hollows filled to build agricultural land with regular fields, a complete road network and shelter belts and a sound irrigation and drainage system; topsoil stripping before ponding on land not yet fully subsided, the extent and depth of future subsidence being accurately predicted and reclamation carried out after full subsidence; engineering measures for future mining areas in mines with repeated extraction of several seams at long intervals; and, for subsided land with a high water table, a scientifically determined ratio of water surface to land and of the several land uses, a suitable elevation and a matching landform. Soil reconstruction, vegetation reconstruction and landscape construction are then set out in the same way, with rules on the choice of pioneer and site-adapted plants, on the arrangement of the plant community as mixed tree and shrub, shrub and grass, tree and grass or tree, shrub and grass stands, on planting density and method, and on the ancillary works of roads, irrigation, drainage, power supply and buildings, the works for reclaimed arable land following GB/T 30600 and GB 5084 and the water quality of reclaimed water bodies following GB 3838.

10 Management and maintenance, monitoring and evaluation, and adaptive management

10.1 A water supply and surface drainage system consistent with ecological principles is to be built, and roads, irrigation, drainage and structures are to be maintained regularly; where a facility is found not to be working properly or to be damaged, it is to be repaired or replaced in good time.

10.2 Over the whole process of reclamation and restoration, the tending and health management of the reconstructed soil and the rebuilt vegetation are to be strengthened and secondary damage and degradation watched for. Vegetation tending covers the areas of rebuilt vegetation, of supplementary planting and of rebuilt farmland shelter belts; the tending period is chiefly the first three to five years of reclamation and may extend to six to ten years in ecologically fragile coal mining areas; the content is chiefly pest and disease control, fire prevention, pruning and thinning. Pest and disease control comprises routine control, focused on daily monitoring and periodic monitoring by plant protection specialists, and non-routine control, comprising monitoring where a widespread or regional outbreak occurs in the area of the project and treatment after the outbreak. Where the land is reclaimed as forest, firebreak roads are to be opened and fire-resistant belts built, the fire measures following the relevant standards.

10.3 For the maintenance of the structure and function of the ecosystem of an ecologically reconstructed mining area, and of its key species in particular, the key species and the biodiversity of the area are to be observed continuously, the ecosystem function assessed at suitable times and the populations, community composition and structure optimized, so that the restored ecosystem passes gradually from formal recovery to functional recovery and the damaged ecosystem returns to a virtuous cycle; and the risks of flood, drought, insect attack and fire are to be lowered so that the relative stability of the ecosystem is maintained and the sustainable use of land, water, biological and landscape resources and of the human settlement environment is safeguarded.

10.4.1 Monitoring and evaluation are to use the global positioning system, remote sensing and geographic information systems, and even integrated space-air-ground techniques and ecological big data analysis, to monitor the diversity, stability and sustainability of coal mine reclamation and restoration throughout, with typical and representative monitoring points, monitoring lines and a monitoring network established; monitoring is to be carried out over the range of the ecological effect of coal extraction, in particular at mines near important river systems, water supply areas and neighbouring basic farmland or basic grassland; follow-up monitoring of the effect of reclamation and restoration is to be carried out under a combined problem-oriented, target-oriented and effect-oriented approach, in particular the resistance of the restored ecosystem under climatic stresses such as drought and rainstorm; and coal mine reclamation monitoring is to follow GB/T 43935.

10.4.2 Monitoring, evaluation and adaptive management are to run through the whole of coal mine production, construction and reclamation. On the basis of whole-cycle follow-up monitoring and assessment and against the reclamation targets, the effect of the mitigation and protection, preventive control and reclamation measures and techniques is to be assessed and any newly arising ecological problems and latent ecological risks found in good time; whether the damaged ecosystem has stopped degrading and is moving toward positive succession is to be assessed; and, on the principle that results and risks stay controllable and drawing on established practice, production processes, preventive control and reclamation measures and techniques, and the deployment and timing of works that might lead away from the targets or cause fresh damage are to be adjusted and corrected by the holder of the mining right after technical review.

10.4.3 Effectiveness assessment is to be carried out according to the mining method, the degree of ecological damage, the reference ecosystem and the reclamation targets of coal mines in the several bioclimatic zones, the measurable assessment indicators used following GB/T 43935. It covers ecological effectiveness and socio-economic effectiveness, with attention to the reshaped landform, the reconstructed soil, the rebuilt vegetation, the recreated landscape and the reassembled biodiversity, to the distance from and the gain over the reference ecosystem, and to the satisfaction of public participation, and may follow the international five-star assessment method. The assessment covers the outcome where the reference ecosystem is used but adaptive management is not applied, so that performance is poor and no reclamation benefit is obtained; the outcome where adaptive management following the reference ecosystem restores the pre-mining ecological condition; and the outcome where such management exceeds the expected trajectory.