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GB 51173-2016: Code for design of dewatering and draining in open pit mine of coal industry
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Code for design of dewatering and draining in open pit mine of coal industry
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GB 51173-2016
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Basic data | Standard ID | GB 51173-2016 (GB51173-2016) | | Description (Translated English) | Code for design of dewatering and draining in open pit mine of coal industry | | Sector / Industry | National Standard | | Classification of Chinese Standard | P41 | | Word Count Estimation | 58,511 | | Date of Issue | 2016-04-15 | | Date of Implementation | 2016-12-01 | | Regulation (derived from) | Ministry of Housing and Urban - Rural Development Notice No. 1101 of 2016 | | Issuing agency(ies) | Ministry of Housing and Urban-Rural Development of the People's Republic of China; General Administration of Quality Supervision, Inspection and Quarantine of the People's Republic of China | GB 51173-2016: Code for design of dewatering and draining in open pit mine of coal industry---This is a DRAFT version for illustration, not a final translation. Full copy of true-PDF in English version (including equations, symbols, images, flow-chart, tables, and figures etc.) will be manually/carefully translated upon your order.
1 General
1.0.1 This specification is formulated to standardize the dewatering and drainage design of open-pit mines, prevent and reduce water damage, ensure production safety, and improve production efficiency.
1.0.2 This code is applicable to the dewatering and drainage design in the preliminary feasibility study, feasibility study and engineering design stages of newly-built, reconstructed and expanded open-pit coal mines.
1.0.3 The dewatering and drainage design of open-pit coal mines should actively adopt domestic and foreign advanced technology, practical experience and mature and reliable new technologies, new processes, new equipment and new materials.
1.0.4 Drainage and drainage shall be carried out simultaneously with the design of open-pit coal mines. The technical proposal shall be determined by technical and economical comparison.
1.0.5 In addition to implementing this code, the dewatering and drainage design of open-pit coal mines should also comply with the current relevant national standards.
2 Terms and symbols
2.1 Terminology
2.1.1 hydrogeological condition hydrogeological condition
The general term for groundwater burial, distribution, recharge, runoff and discharge conditions, water quality and quantity, and its formation geological conditions.
2.1.2 dewatering
According to reasonable economic and technical principles, various drainage projects are used to drain the aquifer that threatens the mining, transportation, and soil discharge of open-pit mines.
2.1.3 groundwater control groundwater control
According to reasonable economic and technical principles, water interception and drainage works are adopted to carry out water interception and drainage of aquifers that threaten open-pit mining, transportation, and soil discharge.
2.1.4 open-pit drainage
Adopt reasonable technical and economical drainage methods to eliminate atmospheric precipitation, surface water catchment, and groundwater infiltration into the open-pit mining field, and technical measures to ensure safe work in the mining field.
2.1.5 Surface water prevention and drainage
Technical measures to prevent surface water from flowing into the open-pit mine excavation site or dump site, improve the stripping efficiency of the open-pit mine, and ensure the safety of the excavation site or dump site.
2.1.6 Prevention and control of groundwater and surface water
A general term for groundwater control, mining site drainage, and surface waterproofing and drainage.
2.1.7 movable substation
It is composed of primary side power supply device, power transformer, secondary side power distribution and protection device, chassis and protective casing, and can be moved as a whole or disassembled and moved as a complete set of power transformation and distribution device.
2.1.8 Distributed control system distributed control system
A microprocessor-based control system for centralized monitoring, operation, management and decentralized automatic control of the production process.
2.2 Symbols
2.2.1 Normal rainfall runoff
aj——the runoff coefficient of each section;
Fj—— catchment area of each section;
H1——Monthly average precipitation in the multi-year rainy season;
Q1——Normal rainfall runoff.
2.2.2 Storm runoff
ai——the runoff coefficient of each segment;
Fi——catchment area of each section;
H2 - the amount of rainstorm in the time period T of the design rainstorm return period;
Q2——storm runoff in time period T.
2.2.3 Water inrush coefficient
M——thickness of floor waterproof layer;
p—head pressure on the aquifer of the bottom plate;
Ts—water inrush coefficient.
2.2.4 Drainage water quality of mining sites
SS - suspended matter;
CODcr - chemical oxygen demand.
3 Groundwater control
3.1 General provisions
3.1.1 The dewatering and drainage design of the preliminary feasibility study stage of the open-pit mine should be prepared according to the reviewed and filed detailed investigation or exploration geological report; the feasibility study stage and preliminary design stage should be prepared according to the reviewed and filed exploration geological report.
3.1.2 Ore fields with complex hydrogeological conditions should comply with the current national standard "Code for Hydrogeological and Engineering Geological Exploration in Mining Areas" GB 12719 and the requirements for mine water prevention and control. The reliability of hydrogeological exploration data and the degree of hydrogeological exploration should be analyzed and evaluated. When the hydrogeological survey data cannot meet the design requirements for dewatering, a supplementary hydrogeological survey requirement should be put forward.
3.1.3 When surface water has a recharge effect on groundwater drainage, measures such as diversion, seepage prevention, and interception should be taken for the surface water system.
3.1.4 In the following situations, groundwater control measures such as dewatering or blocking must be taken.
1 Groundwater has a serious impact on the mining, transportation and soil discharge of open-pit mines;
2 The groundwater reduces the stability of the open-pit mine slope, and the slope of the excavation site or the slope of the dump site may become unstable;
3 The aquifer with high water pressure and rich water content in the coal seam floor may produce water inrush during the mining process.
3.1.5 When pre-draining is used to lower the groundwater level, the pre-draining time and water level lowering depth should be determined according to the strength requirements of the stripping advancement and development of the descending section, and in combination with the hydrogeological conditions.
3.1.6 For open-pit mines with special groundwater control engineering or open-pit mines where groundwater is harmful to mining, a groundwater dynamic observation system should be established.
3.1.7 When dredging groundwater has a serious impact on important buildings (structures), civilian wells, and farmland irrigation around the open-pit mine, preventive measures should be taken.
3.1.8 Drainage water should be comprehensively utilized as water resources.
3.2 Groundwater control methods
3.2.1 The groundwater control method shall be determined after technical and economical comparison according to the hydrogeological conditions of the mining area.
3.2.2 For aquifers with a permeability coefficient greater than 2m/d, groundwater control should adopt the ground vertical precipitation hole method.
3.2.3 When the groundwater supply conditions are poor, reduce the groundwater pressure of the open-pit mine slope or discharge the remaining water in the aquifer, and the groundwater control should adopt the horizontal water hole method.
3.2.4 For unconsolidated aquifers with simple hydrogeological conditions, shallow buried depth, small thickness and relatively stable occurrence, open ditch and hidden ditch method should be adopted for groundwater control.
3.2.5 Under the following circumstances, the roadway method should be adopted for groundwater control.
1 It can be drained by self-flowing drainage in the adit;
2 Multiple aquifers with complex hydrogeological conditions and small hydraulic connections, or aquifers with large changes in thickness, hydraulic pressure and water permeability, buried deep and not suitable for dewatering by the precipitation hole method.
3.2.6 When one of the following conditions is met, the groundwater control should adopt the underground diaphragm wall method.
1.The hydrogeological conditions are complex, and it is difficult to effectively reduce the groundwater level by means of dewatering and drainage;
2 For loose aquifers that are mainly recharged, have abundant recharge sources, have a stable water-resisting layer at the bottom, and are relatively shallow, the underground water-retaining wall method can be used.
3.2.7 When the water is cut off by the underground water wall, the position of the water wall shall ensure the stability of the excavation site slope.
3.3 Hydrogeological calculation
3.3.1 For the calculation of the groundwater inflow in the mining site, an appropriate calculation method should be selected according to the hydrogeological conditions of the mining area, the location of the mining site, and the hydrogeological boundary conditions. For mining areas with complex hydrogeological conditions and high degree of hydrogeological exploration, it is advisable to use numerical methods to calculate the groundwater inflow at the mining site, and to predict the groundwater level after dewatering.
3.3.2 The initial groundwater level of the aquifer should be determined according to the observation data, and the continuous observation time of groundwater level observation data should not be less than one hydrological year.
3.3.3 Hydrogeological calculations shall meet the following requirements.
1 For the calculation of the groundwater inflow in the mining site, the highest value of the groundwater level observation data in the calculation area should be selected;
2 The drainage capacity of the groundwater storage shall be determined according to the water supply degree of the aquifer, the dewatering range, and the stripping progress of the open-pit mine;
3 The drainage capacity of the groundwater control facilities shall be greater than the sum of the groundwater recharge capacity and the drainage capacity of the groundwater storage;
4 The dynamic water level and water pressure of the groundwater shall meet the water level and water pressure required by the safety requirements of open-pit mining.
3.3.4 When calculating the water inflow from the downhole, the hydraulic jump value may not be calculated for the unpressurized aquifer, and the influence of the hydraulic jump value should be considered when determining the groundwater drop curve.
3.3.5 When the water head of the underlying confined aquifer under the coal seam floor is higher than the top surface of the overlying aquifer, the water inrush coefficient method shall be used to check the water inrush (inrush), and pressure reduction measures shall be taken if necessary.
3.4 Drainage project layout
3.4.1 The precipitation hole should be selected in the part with strong permeability, low elevation of aquifer floor and thick aquifer.
3.4.2 The permanent drainage hole row should be close to the protected area, and should be arranged 20m away from the final boundary line of the surface of the open-pit excavation site.
3.4.3 Horizontal water discharge holes should be arranged on the sides where groundwater collects and landslides are prone to occur.
3.4.4 Open ditches and hidden ditches should be arranged on the surface or flat plate with artesian conditions, and the mechanical erosion of the slope by water should be checked. Slope protection measures should be taken when necessary. The longitudinal slope of the open ditch shall be determined through hydraulic calculation according to the nature of rock and soil and the type of retaining masonry. The longitudinal slope of the ditch should be 2‰～3‰, and when conditions permit, geomembrane can be laid in the open ditch and the hidden ditch.
3.4.5 The roadway should be arranged in a stable water-resisting layer or a weak aquifer. If there is no water-resisting layer or a weak aquifer on the roof and floor of the coal seam, the roadway can be arranged in an aquifer. When a roadway is set on the floor of the loose aquifer, the depth of the bottom of the roadway embedded in the water-resisting rock layer should be 0.5m to 1.0m. The longitudinal slope of the roadway should not be less than 2‰.
3.4.6 The underground water-resisting wall shall be arranged on a stable water-resisting rock formation with a permeability coefficient less than 5×10-8m/s, and the depth of its bottom embedded in the water-resisting rock formation shall not be less than 1m. Diaphragms shall be subject to stability and seepage calculations. When a concrete water-dividing wall is used, the strength of the water-dividing wall should also be calculated based on the maximum water level difference on both sides of the wall.
3.4.7 The structure of the dewatering hole shall be determined according to the lithology of the stratum, the characteristics of the stratum structure, the buried depth of groundwater, the drilling technology and other conditions, and shall meet the following requirements.
1 The hole diameter of the pump section should be determined according to the hole forming requirements;
2 The variable diameter of the hole and its corresponding length and opening diameter should be determined according to the formation and drilling technology;
3 The hole depth should be comprehensively determined according to factors such as the buried depth and thickness of the water-filled aquifer in the excavation field.
3.5 Draining equipment and filters
3.5.1 For the drainage equipment of downholes and roadways, appropriate submersible pumps should be selected according to the water quantity and quality. After the technical and economic comparison, the drainage equipment of the roadway can adopt horizontal water pumps.
3.5.2 The drainage capacity of the downhole drainage pump shall be calculated as 24 hours a day and night. The number of precipitation holes should be 1.2 times the number of calculated precipitation holes.
3.5.3 The number of standby and maintenance pumps for downhole drainage should be 40% to 50% of the number of working units; when the number of working units is less than 10, it should not be less than 50% of the number of working units.
3.5.4 The number of roadway drainage pumps and the volume of water tanks, etc., shall comply with the relevant provisions of the current national standard "Coal Industry Mine Design Code" GB 50215.
3.5.5 The type of filter shall be selected according to Table 3.5.5 according to the nature of the aquifer.
Table 3.5.5 Filter Types
3.5.6 The filter material should be determined according to factors such as groundwater quality, stress conditions and economic rationality.
3.5.7 The filter material specifications and thickness of the gravel-filled filter, the hole or gap size of the skeleton tube and the porosity of the wire-wrapped surface of the wire-wrapped filter shall comply with the relevant provisions of the current national standard "Technical Specifications for Water Supply Tube Wells" GB 50296.
3.5.8 The flow rate of water entering the filter pipe allowed by the downhole should not be greater than 0.03m/s.
3.5.9 The diameter of the filter should be comprehensively determined based on factors such as the designed water output, the maximum outer diameter of the pump and motor, and the allowable water inlet flow rate of the filter pipe. The minimum inner diameter of the filter shall not be less than the regulations in Table 3.5.9.
Table 3.5.9 Filter Inner Diameter
3.5.10 The porosity of filter screen pipe should be 20%-35% for steel pipes, 20%-25% for cast iron pipes, 15%-20% for reinforced concrete pipes and asbestos cement pipes, and 10% for plastic pipes ~13%.
3.5.11 For the settling holes in the unconsolidated aquifer, the bottom-closed settling pipes shall be installed, and the length shall not be less than those specified in Table 3.5.11.
Table 3.5.11 Length of grit chamber
3.6 Draining pipes
3.6.1 The drainage pipelines around the mining field should be arranged on the side away from the surface boundary of the mining field.
3.6.2 The water flow angle at the turn of the drain pipe and at the connection between the main pipe and the branch pipe should not be less than 90°.
3.6.3 The drain pipe should be steel pipe, cast iron pipe or plastic pipe. Steel pipes should be used for frequently moving drainage pipes. Open ditch drainage can be used when conditions permit.
3.6.4 When the drainage pipeline is laid for a long time, a mud discharge valve should be installed at the lowest point of the pipeline, and an exhaust valve should be installed at the highest point.
3.6.5 The foundation of the draining pipeline shall be determined according to the pipeline material, interface form and geological conditions. For areas with soft ground and uneven settlement, reinforcement measures should be taken for the pipeline foundation.
3.6.6 External anti-corrosion measures shall be taken for metal pipelines. The external anti-corrosion of buried metal pipelines should use epoxy coal coatings; the external anti-corrosion of metal pipelines for exposed metal pipelines should be selected according to factors such as weather and environment.
3.6.7 The pipe connection shall be determined according to the pipe material and geological conditions. Rigid joints or flexible joints may be used, and flexible joints should be used for confluent pipes. When the pipeline passes through the silt and fine sand layer and is below the highest groundwater level, or in the fortified area with the seismic fortification intensity of 8 degrees, the flexible interface shall be adopted.
3.6.8 When pipelines cross railways and roads, protective measures such as adding protective sleeves or pipe trenches should be taken.
3.6.9 The minimum covering soil thickness of the pipeline shall be determined according to factors such as freezing conditions, external loads, pipe material performance, and anti-floating requirements, and antifreeze and heat preservation measures shall be taken as required. The covering soil thickness of the pipe top shall not be less than the maximum local frozen soil depth. Pipelines passing through farmland in non-cold regions should not hinder farming, and for pipelines buried in farmland, the minimum covering soil thickness at the top of the pipe should not be less than 1m.
3.6.10 Expansion and contraction caused by temperature difference shall be considered for exposed pipelines, and corresponding pipeline compensation measures shall be taken as required.
3.6.11 Pipelines and materials should be reserved according to different varieties and specifications, and the spare quantity of pipes of different materials should be selected according to the following regulations.
1 Prestressed reinforced concrete pipe should be 10% to 15%;
2 cast iron pipe should be 7% to 12%;
3 Steel pipes and plastic pipes should be 5% to 10%.
3.6.12 The design of permanent drainage pipes and ancillary facilities should comply with the current relevant national standards.
3.7 Observation of groundwater dynamics
3.7.1 The layout of the groundwater dynamic observation system shall be determined according to the degree of influence of groundwater on open-pit mining and hydrogeological conditions, and shall comply with the provisions of Article 3.1.6 of this code.
3.7.2 The hole network for groundwater dynamic observation should be centered on the mining field. Groundwater dynamic observation holes should be intensified in the main water incoming direction, around the mining field, near the surface water body, and on both sides of the water-conducting structural belt.
3.7.3 The depth of the observation hole should be based on the water level of the aquifer controlled for observation, and the diameter of the observation hole should be greater than 91mm, and the diameter of the observation hole should be greater than 150mm in cold regions.
3.7.4 Filter materials and specifications can be determined in accordance with Articles 3.5.5~3.5.7 and Article 3.5.10 of this code.
3.7.5 The orifice pipe of the observation hole should be 0.5m above the ground, and a protective device should be installed at the orifice.
4 waterproofing and drainage
4.1 Drainage of mining sites
4.1.1 The drainage design of the excavation field shall be combined with groundwater control and ground waterproofing system to comprehensively determine the drainage mode of the excavation field.
4.1.2 The drainage of the mining field shall include the runoff of atmospheric precipitation and the inflow of groundwater entering the mining field. Drainage in open-pit excavation shall adopt the drainage methods of prevention, drainage, storage and their combination, and shall comply with the following regulations.
1 Open-pit mines with topographic height difference conditions should adopt artesian drainage;
2 When there are segmental closure conditions, the segmental closure drainage method should be adopted;
3.The water storage at the bottom of the excavation pit has little impact on the production of the sunken open-pit mine, and the water storage and drainage method at the bottom of the pit should be adopted;
4 When water pumps are used for drainage, mobile or semi-fixed pump stations can be used for drainage, and submersible pumps should be used for drainage pumps;
5.When the water catchment is large and the water storage space at the bottom of the pit is limited, and when there are old roads or dredged roadways available in the open-pit coal mine, the drainage method of water storage in the well roadway can be adopted after technical and economic comparison.
4.1.3 The drainage design of shafts and lanes shall comply with the relevant provisions of the current national standard "Code for Mine Design in the Coal Industry" GB 50215.
4.1.4 The drainage design of the excavation site shall meet the following requirements.
1 Calculate the average monthly rainfall in the multi-year rainy season when the normal rainfall should be 10a or more;
2 The runoff of the mining field shall be the long-duration heavy rainfall;
3 The runoff of the drainage ditch shall be the short-duration heavy rainfall.
4.1.5 The designed rainstorm return period for drainage calculation of excavation site shall not be less than 50a for large-scale open-pit coal mines, and shall not be less than 20a for medium-sized open-pit coal mines.
4.1.6 The drainage period of the collected water formed by the storm runoff shall be less than the provisions in Table 4.1.6.
Table 4.1.6 Discharge period
4.1.7 The normal rainfall runoff and storm runoff shall be calculated by the runoff coefficient method, and the soil-rock runoff coefficient shall be the measured value. When there is no measured value, it can be selected according to Table 4.1.7.
Table 4.1.7 Runoff coefficient
Note. 1.When the runoff coefficients of rock and soil types 1 to 7 in the table are used in the calculation of long-duration storm runoff, 0.1 to 0.2 should be subtracted from their values;
2 When there are a few cracks in the coal rock, the runoff coefficient should be subtracted by 0.1 to 0.2; when there are medium cracks, the runoff coefficient should be subtracted by 0.3 to 0.4.
4.1.8 Excavation field drainage can be divided into normal rainfall drainage and storm drainage, and shall meet the following requirements.
1 When groundwater flows into the excavation field, the discharge volume shall include the groundwater gushing volume. Normal rainfall discharge and storm discharge should not be lower than normal rainfall runoff and storm runoff.
2 The normal rainfall runoff can be calculated by the following formula.
In the formula. Q1——normal rainfall runoff (m3/h);
H1——Monthly average precipitation in the multi-year rainy season (m);
aj——the runoff coefficient of each segment;
Fj—— catchment area of each section (m2).
3 Storm runoff can be calculated by the following formula.
In the formula. Q2——storm runoff in period T (m3);
H2——the amount of heavy rainfall (m) in the time period T of the design heavy rain return period;
ai——the runoff coefficient of each segment;
Fi—— catchment area of each section (m2).
4.1.9 Drainage equipment in the excavation site shall be selected according to the drainage stages and shall meet the following requirements.
1 The working time of the drainage pump shall be calculated as 20 hours per day;
2 For open-pit mines with small storm drainage, the storm drainage pumps and normal rainfall drainage pumps installed on the same level should choose the same type of pumps;
3 When the drainage of the storm is 3 times or more than that of the normal rainfall, the storm drainage pump and the normal rainfall drainage pump can choose different types of pumps;
4 Normal rainfall drainage pumps shall be equipment pumps and maintenance pumps, and their quantity shall be 50% of the number of working water pumps;
5 The storm drainage pump can be used without equipment.
4.1.10 The pool volume of the excavation field drainage pump station should not be less than the 0.5h displacement of the normal rainfall drainage pump.
4.1.11 The selection of drainage pipes shall meet the following requirements.
1 should meet the requirements of working pressure;
2 The diameter of normal rainfall drainage pipes should be determined according to the economic flow rate of 1.5m/s to 2.2m/s, and the diameter of storm drainage pipes should be determined according to the flow rate not greater than 3.5m/s;
3 The number of drainage pipes should not be less than 2, each of which should be able to meet the drainage requirements of normal rainfall, and all the drainage pipes should be able to meet the requirements of storm drainage.
4.1.12 The equipment layout of the drainage pump room shall comply with the relevant provisions of the current national standard "Code for Design of Outdoor Drainage" GB 50014.
4.1.13 The technical requirements for drainage pipes in mining sites shall comply with the provisions in Section 3.6 of this code.
4.2 Ground waterproofing and drainage
4.2.1 When open-pit mines are threatened by floods, special waterproof and drainage facilities should be installed, and open-pit mines with large water catchment should be equipped with drainage (cutting) ditches and dams.
4.2.2 The waterproof and drainage system of the open-pit mine shall have the feasibility of combining with the local surface water body, flood control and drainage and other water conservancy systems.
4.2.3 The design of large-scale flood control projects such as river diversions and flood control reservoirs shall comply with the relevant current national standards.
4.2.4 The construction materials of flood control dams shall be obtained locally. When conditions permit, the stripping material can be used to build flood control dams.
4.2.5 The flood peak discharge of small and medium-sized rivers and natural gullies shall be determined according to the actual measurement data of the local hydrological station. When there is no actual measurement data, the following methods can be used for calculation, and other methods should be used for verification when conditions permit.
1 Morphological survey method;
2 Simplified formula method of Institute of Highway Science;
3 Local empirical formula method.
4.2.6 The flood control standard shall be determined according to factors such as the scale and service life of the open-pit coal mine, and shall comply with the provisions in Table 4.2.6-1 and Table 4.2.6-2.
Table 4.2.6-1 Flood control standards for river diversions, dams and drainage ditches
Note. 1 Class I drainage ditch refers to the drainage ditch that endangers the safety of the mining site during flooding;
2 Category II drainage ditches refer to drainage ditches that do not endanger the safety of the mining site when floods occur;
3 The service life is short and the consequences of flooding are not serious. The lower limit is taken.
Table 4.2.6-2 Design return period of flood diversion reservoir
4.2.7 When the open-pit mine and the mine share the flood control project, the flood control standard shall comply with the relevant provisions of the current national standard "Coal Industry Mine Design Code" GB 50215.
4.2.8 The design of drainage ditches shall meet the following requirements.
1 The ground drainage ditch should not be less than 50m away from the surface boundary of the mining site;
2 The design of flat drainage ditches in excavation sites and dumps should avoid side landslides caused by leakage, and the longitudinal slope should not be too large, and the slope difference should not be too large;
3 The stone drainage ditch should adopt a rectangular section, and the soil drainage ditch should adopt a trapezoidal section. The soil drainage ditch can be reinforced with slurry (dry) rubble stones or slurry (dry) block stones, and the reinforcement thickness should not be less than 300mm. It can be laid when conditions permit. Geomembrane;
4 The minimum radius of the curved section of the ground drainage ditch shall not be less than 5 times the width of the water surface at the design water level;
5 The intersection angle between the ground drainage ditch and the river channel junction should be less than 60°, and the bottom elevation of the drainage ditch outlet should be higher than the normal water level elevation of the river channel;
6 The safe height of the drainage ditch shall be determined according to the design water depth. When the water depth is greater than or equal to 2m, the safety height shall not be less than 0.5m; when the water depth is less than 2m, the safety height shall not be less than 0.3m.
4.2.9 Sedimentation tanks should be installed at the outlet of the drainage ditch.
4.2.10 The diversion of the river shall meet the flood control and safety requirements of the excavation field, and the distance between the new river course and the surface boundary of the excavation field shall be determined after technical demonstration based on the influence of the river on the slope.
4.2.11 The river diversion project shall be approved by the local water conservancy authority, and shall be completed by a design unit with corresponding qualifications.
4.2.12 When there is waterlogged water in the excavation site or dump site, drainage measures shall be taken. When the topographical conditions are suitable, the method of interception or earth discharge shall be adopted to fill up the depression.
4.2.13 It is advisable to build a retaining dam in the natural channel upstream of the excavation site and dump, and the construction time is determined according to the stripping and dumping plan. When the accumulated water cannot evaporate naturally, mobile pumping stations can be used to disperse and dredge.
4.2.14 The safe height of flood control dams should not be less than 0.5m in plain areas and 1m in hilly areas.
5 auxiliary engineering
5.1 Power supply and distribution and automatic control
5.1.1 The power load division of dewatering and drainage in open-pit mines shall meet the following requirements.
1 When the dredging roadway needs roadway inspection and maintenance, the water pump should supply power according to the first-level load;
2 The excavation field drainage pumping station shall supply power according to the secondary load;
3 Drainage equipment that does not belong to the primary and secondary loads can...
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