Circular No. 34/2018/TT-BCT on the acceptance and quantity inspection of overburden in open-pit coal mining.

CIRCULAR

Regulations on the acceptance and inspection of earth and rock excavation volumes in open-pit coal mining

Pursuant to Decree No. 98/2017/NĐ-CP dated August 18, 2017, of the Government stipulating the functions, tasks, powers, and organizational structure of the Ministry of Industry and Trade;

At the proposal of the Director of the Department of Oil and Gas and Coal,

The Minister of Industry and Trade issues this Circular to regulate the acceptance and inspection of earth and rock excavation volumes in open-pit coal mining.

PART I

GENERAL PROVISIONS

Article 1. Scope of Regulation

Article 1. This Circular regulates the acceptance and inspection of earth and rock excavation and transportation volumes in open-pit coal mining.

Article 2. This Circular does not apply to open-pit coal slurry mining.

Article 2. Applicability

1. Organizations and individuals engaged in open-pit coal mining (hereinafter referred to as organizations and individuals involved in coal mining).

2. Organizations and individuals related to the acceptance and inspection of earth and rock excavation and transportation volumes in open-pit coal mining.

Article 3. Explanation of Terms

1. Excavated earth and rock refers to the portion of earth and rock that must be excavated according to technical requirements for coal mining operations. The volume of excavated earth and rock is denoted as VĐ, with units measured in cubic meters (m³.

2. Unit weight of solid earth and rock is the mass of one cubic meter of earth and rock in its natural state. The unit weight of solid earth and rock is denoted as DL, with units measured in tons per cubic meter (ton/m³.

3. Expansion coefficient of earth and rock is the ratio between the volume of earth and rock when it is loosened and its volume in its natural state. The expansion coefficient of earth and rock is denoted as .

4. Model vehicle refers to the volume of earth and rock loaded onto a specific-sized truck bed according to a diagram, converted to solid form, with a mass of earth and rock consistent with the cargo capacity specified on the vehicle's certificate of technical safety and environmental protection issued by the competent authority.

5. Direct superior enterprise refers to the direct superior enterprise for an enterprise that is a subsidiary within a corporate group as defined by laws on enterprises.

Chapter II

ACCEPTANCE OF EARTH AND ROCK EXCAVATION VOLUMES

Section 1

 DIVISION OF ACTUAL EXCAVATED EARTH AND ROCK AND LIMITATIONS ON POSITIONAL DEVIATIONS BETWEEN PLANNED AND ACTUAL IMPLEMENTATION

Article 4. Division of actual excavated earth and rock

Actual excavated earth and rock is divided into planned annual excavated earth and rock and unplanned annual excavated earth and rock. Planned annual excavated earth and rock is included in the actual excavation volume for acceptance, while unplanned annual excavated earth and rock is not included in the actual excavation volume for acceptance.

1. Planned annual excavated earth and rock includes:

a) Earth and rock located within the mine design approved by the competent authority and within the annual plan approved by the head of the organization or individual involved in coal mining/direct superior enterprise, which has been excavated, transported, and dumped according to regulations.

b) Earth and rock generated due to sliding and collapse during mining affecting mining layers, benches, transport routes, drainage ditches, and which must be removed to ensure production, shall be included in the actual excavation volume for the planned year. For earth and rock generated outside the mine design boundary, a separate handling plan must be established and approved by the head of the organization or individual involved in coal mining/direct superior enterprise, and it shall not be included in the mine stripping ratio.

2. Unplanned annual excavated earth and rock refers to earth and rock not covered under Clause 1 of this Article. In cases where earth and rock is excavated beyond the annual plan limit but still within the mine design boundary, it may be included in the actual excavation volume for the following year if the subsequent year's plan specifies stripping up to that limit.

3. Previously permitted temporary dumping of excavated earth and rock within the mine design boundary, which has been accepted but must be excavated, transported, and dumped at the disposal site according to the plan period, shall not be included in the mine stripping ratio and must be separately recorded and classified as soft earth and rock with low unit weight, not requiring drilling or blasting, and can only be used to calculate excavation and transportation costs.

Article 5. Limitations on the difference between actual and planned positions for determining overburden within and outside the plan

1. The actual position of permitted layers may differ from the planned layer positions for the year by ±5 m, measured from the bottom of the layer.

2. The actual position of the final layer of the mine boundary may differ from the technical boundary by ±2 m, measured from the bottom of the layer.

3. The actual position of the road lines may differ from the mine design or the annual plan by ±4 m, measured from the center of the road.

4. The actual height of the layer may differ from the planned layer height for the year by ±1.5 m.

Section 2

TIME OF ACCEPTANCE AND DOCUMENTS USED FOR CALCULATING THE QUANTITY OF OVERBURDEN EXCAVATION AND TRANSPORTATION

Article 6. Time of acceptance

1. Monthly, organizations and individuals exploiting coal must conduct acceptance of the quantity of overburden excavation and transportation carried out. The time for accepting the quantity of the previous month shall be conducted from the 1st to the 10th day of the following month. The acceptance data shall be calculated up to the last day of the month. In cases where the quantity of overburden excavation of the exploitation area ≤ 10,000 m³/month, it is allowed to measure and accept quarterly.

2. Quarterly, organizations and individuals exploiting coal base on the results of monthly acceptance of overburden excavation and transportation quantities within the quarter to compile the quarterly acceptance work. The time for compiling the quarterly acceptance work quantity of the previous quarter shall be conducted from the 1st to the 15th day of the first month of the next adjacent quarter.

3. At the end of the year, organizations and individuals exploiting coal base on the results of quarterly acceptance of overburden excavation and transportation quantities within the year to compile the annual acceptance work. The time for compiling the annual acceptance work quantity shall be conducted from the 1st to the 15th day of the first month of the following year.

Article 7. Documents used for calculating the quantity of overburden excavation and transportation

1. Mine design approved according to the provisions of the law.

2. Plan maps approved by the head of the organization or individual exploiting coal or the direct superior of the enterprise.

3. Rock mechanics documents of the mine approved by the head of the organization or individual exploiting coal or the direct superior of the enterprise for use in calculating and accepting the quantity of overburden.

a) For operating mines, rock mechanics documents of the mine must be updated when the depth of exploitation exceeds 75 m compared to the previous update.

b) For new areas of the mine put into operation in the first year and newly expanded exploitation areas, rock mechanics documents of the mine must be established based on exploration documents approved by competent authorities.

4. 3D digital maps; data from the latest monthly, quarterly, and annual measurements; paper maps signed by the heads of relevant departments and the signature and stamp of the head of the organization or individual exploiting coal.

5. Statistical data on the quantity of overburden excavation and transportation.

6. Minutes and maps to determine the haulage distance.

Article 8. Requirements for documents used for calculating the quantity of overburden excavation and transportation

1. Documents and maps used for calculating, accepting, and inspecting the quantity of overburden excavation and transportation must be established in accordance with current regulations.

2. Rock mechanics documents of the mine (represented on maps, cross-sections, descriptions...) must fully list all types of rocks, the weight of each type of rock, as well as the boundaries of each type of rock; maps and cross-sections must be drawn at the same scale as the maps for accepting the quantity of overburden excavation carried out.

3. Statistical data must comply with legal provisions on statistics.

4. It is not allowed to erase or modify documents and data used for calculating the quantity of overburden excavation and transportation.

Article 9. Requirements for Calculation Sheets and Acceptance Certificates

1. Organizations and individuals exploiting coal must have acceptance certificates for the volume of excavation and transportation of overburden and sludge (if any) for each work site according to the acceptance period. The acceptance certificate must be signed by all relevant specialized departments of the organization or individual exploiting coal and must be signed and stamped by the head of the organization or individual exploiting coal.

2. Organizations and individuals exploiting coal must have complete calculation sheets for the volume of overburden and sludge, and the volume of transported overburden for each work site and each means of transport. These calculation sheets must be signed by the person who calculates, the person who checks, and the head of the relevant specialized departments.

Article 10. Maps and Calculated Cross-sections

1. Topographic maps of the mining area must be carried out according to current standards on mine surveying.

2. Calculated cross-sections for determining the volume of overburden must be constructed using specialized software.

3. The edge error of each square cell with a side length of 100 mm on a hard paper map must not exceed ±0.2 mm.

4. On the cross-sections, coordinate axes and contour lines spaced 20 meters apart must be drawn, along with planning year boundaries and mine design limits to analyze volumes. The cross-sections need to be arranged fixedly and perpendicular to most layers.

5. The overall map for calculating the total volume of overburden throughout the mine must be updated at least once every six months.

Section 3

PRINCIPLES AND METHODS FOR DETERMINING THE VOLUME OF OVERBURDEN AND THE VOLUME OF TRANSPORTED OVERBURDEN

Article 11. Principles for Determining the Volume of Overburden

1. The volume of overburden is determined and accepted through geodetic measurement and calculation methods. Measurement data is the official data for calculating the actual volume of overburden. The measurement time for acceptance may be up to ±5 days earlier or later than the last day of the acceptance period.

2. The volume of overburden accepted for early or late measurements compared to the end period is converted from statistical data based on vehicle models multiplied by the ratio difference between measurement data and statistical data based on vehicle models of the previous month and used to add or subtract from the final acceptance measurement results.

3. The final acceptance volume of the period is equal to the total volume calculated from the initial period map to the final period map minus the already accepted volume.

4. In cases where it is impossible to determine the volume of overburden through geodetic measurement and calculation methods, it is permissible to determine it through statistical methods based on vehicle models as stipulated in Article 15 of this Circular.

The determination of the volume of overburden is carried out according to Appendix No. 1 of this Circular.

Article 12. Determination of the Volume of Overburden Using Geodetic Measurement and Calculation Methods

1. Vertical Cross-section Method Parallel to the Strike

For mines extending along strike lines, where the thickness and dip of the strata change little, and the surface is relatively flat, the vertical cross-section method parallel to the strike should be used to determine the volume of overburden. When using vertical cross-sections parallel to the strike to determine the volume of overburden, the following regulations must be followed:

a) For maps at a scale of 1/1000

- The scale of the cross-sections: Horizontal and vertical scales are both 1/1000.

- The maximum distance between cross-sections is 20 meters.

b) For maps at a scale of 1/500

- The scale of the cross-sections: Horizontal and vertical scales are both 1/500.

- The maximum distance between cross-sections is 10 meters.

In areas with folded strata or complex terrain, additional auxiliary cross-sections must be established for calculation.

c) Formula for calculating the volume (V) between two adjacent cross-sections

- When the ratio of the areas of two adjacent cross-sections (S small / S large) ≤ 2/3, use the following formula:

Where:

+ S1, S2: Areas of two adjacent cross-sections, m²²;

+ h: Distance between two cross-sections, m.

- When the ratio of the areas of two adjacent cross-sections (S small / S large) > 2/3, use the following formula:

- For peripheral blocks shaped like pyramids or wedges, use the following formula:

Where:

+ h': Average horizontal length of the peripheral block, m;

+ S: Area of the base, m²².

2. Horizontal Cross-section Method

When calculating the volume of overburden using the horizontal cross-section method, the final state of the mining area at the end of the previous month and the end of the next month must be shown on the map in different colors. Calculations must be performed separately for each area, each layer, and each machine.

b) The actual height of the layer is the difference in the average elevation of all points on the bottom and top surfaces of the layer in the production area. When calculating the volume using the horizontal cross-section method, it must be done according to the provisions of point c, Clause 1 of this Article.

3. Method Using Specialized Software for Calculation

Organizations and individuals exploiting coal decide independently on the use of specialized software for calculation.

Article 13. Allocation of Overburden Excavation Volume to Construction Equipment

1. Organizations and individuals exploiting coal must organize the statistical measurement of overburden excavation and transportation volumes for each piece of equipment and each layer to allocate overburden excavation and transportation volumes to each construction equipment. The allocation of overburden excavation volume to each construction equipment must be consistent with the acceptance data of the entire layer and the whole construction site.

2. In cases where a single excavator or construction transportation equipment operates independently within a specific area, the measured and calculated geodetic volume is the volume executed by the excavator or transportation equipment during the period.

3. In cases where multiple excavators and transportation equipment work together and it is not possible to calculate individual volumes for each piece of equipment, the allocation of overburden excavation volume shall be proportional to the statistical data.

The allocation of overburden excavation volume to construction equipment shall be carried out according to Appendix No. 3 of this Circular.

Article 14. Method for Determining Sludge and Overburden Deposit Volumes in the Pit Bottom

1. The determination of the height of the sludge and overburden deposit surface when the pit bottom is still flooded shall be conducted using water depth measuring devices or by combining rulers with specialized geodetic equipment.

2. In cases where the overburden deposit in the pit bottom originates from the mine design exploitation area and must be excavated and transported during the period, the calculation and acceptance shall be carried out as for overburden in the exploitation area (it must be deducted from the execution volume of the period and can only be accepted after being excavated and transported outside the exploitation area); in cases where the origin is from outside the mine design exploitation area, the determination of the weight, calculation of the volume, and handling of sludge and overburden deposits in the pit bottom shall be carried out according to a separate plan approved by the head of the organization or individual exploiting coal or the direct superior of the enterprise.

3. The weight of sludge and overburden deposits in the pit bottom, old waste rock piles shall be directly determined on-site or reused if previously determined results are similar in nature. This determination shall be decided by the head of the organization or individual exploiting coal.

Article 15. Determination and Acceptance of Overburden Excavation Volume Using Statistical Methods

1. In cases where it is impossible to determine the overburden excavation volume using geodetic measurement and calculation methods (overburden during exploitation causes landslides affecting transport routes, drainage ditches, requiring excavation and transportation), there must be a field confirmation record signed and stamped by the heads of relevant specialized departments and approved by the head of the organization or individual exploiting coal. If the total overburden excavation volume executed in one year ≤ 10,000 m³, statistical handover data based on vehicle models may be used to determine the overburden excavation volume; in cases > 10,000 m³, the organization or individual exploiting coal must develop a handling plan and obtain approval from the direct superior of the enterprise before implementation.³ shall be permitted to use statistical data on loading and unloading according to the truck model to determine the volume of overburden; in cases exceeding 10,000 m³ then organizations and individuals exploiting coal must develop a handling plan and have it approved/submitted to the direct superior authority of the enterprise for approval before implementation.

2. In cases of force majeure (due to floods, mine flooding) where it is impossible to measure maps to determine the overburden excavation volume using geodetic measurement and calculation methods, the organization or individual exploiting coal must establish a separate plan and obtain approval from the direct superior of the enterprise before implementation.

Article 16. Determining the unit weight of each type of overburden rock mass, the average weighted unit weight of overburden rock mass, and the volume of overburden rock mass transportation

1. The unit weight of each type of overburden rock mass is determined based on the mine's geomechanical data and carried out according to Appendix 2 of this Circular.

2. The average weighted unit weight of overburden rock mass in the mining area used for calculating the volume of overburden rock mass transportation is determined based on the mine's geomechanical data and carried out according to Appendix 3 of this Circular.

3. The determination of the volume of overburden rock mass transportation is carried out according to Appendix 3 of this Circular, wherein the haulage distance of overburden rock mass is determined by direct measurement using specialized equipment at the site or determined from a map with a scale of 1/1000 or 1/500.

Chapter III

INSPECTION OF THE VOLUME OF OVERBURDEN ROCK MASS

Article 17. Inspection Time

1. Annually, the immediate superior authority of the enterprise inspects the acceptance of the volume of overburden rock mass excavation and transportation by the enterprise.

2. In cases where necessary, the immediate superior authority of the enterprise may conduct surprise inspections of the acceptance of the volume of overburden rock mass excavation and transportation by the enterprise.

3. The inspection results are confirmed by a protocol signed and stamped by all relevant parties.

Article 18. Deviation in Volume Inspection of Overburden Rock Mass

1. The permissible deviation when inspecting the acceptance of the volume of overburden rock mass by measurement methods is implemented according to the current standard on Mine Surveying.

2. When the difference between the accepted figures and the inspected figures does not exceed the permissible deviation, the accepted figures can be maintained.

3. If the difference between the accepted figures and the inspected figures exceeds the permissible deviation, the inspected figures shall be used as the official acceptance figures. If there is no agreement on the inspected figures, the organization or individual exploiting coal has the right to file a written complaint to a higher competent authority for verification. During the time that the authorities are reviewing, the accepted figures of the organization or individual exploiting coal will be temporarily used; the decision of the highest competent authority is the final decision.

Chapter IV

IMPLEMENTATION AND ENFORCEMENT PROVISIONS

Article 19. Implementation

1. The head of the organization or individual exploiting coal is responsible for:

a) Directing specialized departments to organize implementation in accordance with the provisions of this Circular, including:

- Building vehicle models, mapping open-pit areas, determining the haulage distance of overburden rock mass, calculating the volume of overburden rock mass.

- Preparing the mine's geomechanical data; determining the unit weight and volume of each type of overburden rock mass, the average weighted unit weight of overburden rock mass in the mining area, and the expansion coefficient of overburden rock mass.

- Preparing monthly, quarterly, and annual plans; calculating planned volumes of overburden rock mass; analyzing unplanned volumes at the end of the acceptance period.

- Statistics on the volume of overburden rock mass excavation and transportation; calculating and determining the actual volume of overburden rock mass transportation.

- Preserving and storing documents used for calculating, accepting, and inspecting the volume of overburden rock mass excavation and transportation in accordance with the law on archives.

b) Issuing contents, procedures, and methods for preparing geomechanical maps of the mine suitable for actual production conditions, ensuring the requirements stipulated in this Circular.

c) Being responsible for the accuracy of the documents and software used in calculating the volume of overburden rock mass excavation and transportation and the results of the acceptance of the volume of overburden rock mass excavation and transportation.

d) At least once every five years, organizing the calculation and inspection of the volume of overburden rock mass excavation and transportation; analyzing and comparing with the approved mine design to compare and verify the implementation with the design.

2. The immediate superior authority of the enterprise is responsible for:

a) Implementing the tasks prescribed in this Circular.

b) Directing and inspecting the implementation of the acceptance work of the volume of overburden rock mass excavation and transportation of subsidiary companies in accordance with this Circular.

Article 20. Effective Date

1. This Circular takes effect from November 26, 2018.

2. This Circular replaces the relevant provisions on the acceptance and inspection of the volume of overburden rock mass in Articles 2, 5, 6, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 26, 27, and 28 of the Regulation on the Inspection and Acceptance of the Volume of Overburden Rock Mass and Coal Production in Open-Pit Mines issued together with Decision No. 41/2002/QĐ-BCN dated October 4, 2002 of the Minister of Industry.

3. Relevant organizations and individuals shall be responsible for enforcing this Circular.

4. During the implementation process, if there are difficulties or obstacles, organizations and individuals should report to the Ministry of Industry and Trade for guidance and resolution.