Circular No. 32/2024/TT-BTNMT stipulates technical procedures for investigating and assessing marine sand mineral resources.

CIRCULAR

Technical Regulations for Surveying and Evaluating Marine Sand Mineral Resources

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Pursuant to the Law on Minerals dated November 17, 2010;

Pursuant to Decree No. 158/2016/NĐ-CP dated November 29, 2016 of the Government detailing implementation of certain provisions of the Minerals Law;

Pursuant to Decree No. 68/2022/NĐ-CP dated September 22, 2022 of the Government stipulating the functions, tasks, powers, and organizational structure of the Ministry of Natural Resources and Environment;

At the proposal of the Director of the Vietnam Geological Survey;

The Minister of Natural Resources and Environment promulgates this Circular on technical regulations for surveying and evaluating marine sand mineral resources.

PART I
GENERAL PROVISIONS

Article 1. Scope of Regulation

This Circular stipulates the technical contents of the work of surveying and evaluating marine sand mineral resources.

Article 2. Applicability

This Circular applies to state management agencies, organizations, and individuals related to the activities of surveying and evaluating marine sand mineral resources.

Article 3. Explanation of Terms

In this Circular, the following terms shall be understood as follows:

1. Marine sand is loose granular material of natural origin accumulated in the marine environment within the range from the river mouth boundary seaward.

2. River mouth boundary is the point where the river meets the sea determined by the straight line connecting the outermost points of the lowest tide level over many years on both sides of the river.

3. Evaluation works are construction works carried out to take samples to determine the thickness and quality of marine sand by drilling machines and vibro probes.

4. Bathymetric map is a map drawn based on the results of echo soundings along the survey and evaluation lines and coordinate and depth data of geophysical and geological survey points and other relevant survey points.

Article 4. Sequence and Scale of Surveying and Evaluation

1. The sequence of surveying and evaluating marine sand mineral resources is divided into two stages:

a) Surveying marine sand mineral resources aims to forecast resource class 334a and delineate areas with potential for transitioning to the evaluation stage;

b) Evaluating marine sand mineral resources aims to clarify the scale and quality of marine sand minerals, determine resource classes 333 and 222, and delineate areas meeting conditions for transferring to exploration and exploitation.

2. Proportion of Surveying and Evaluating

a) Surveying marine sand mineral resources is conducted at a scale of 1:50,000;

b) Evaluating marine sand mineral resources is conducted at a scale of 1:25,000.

Article 5. Contents of Surveying Marine Sand Mineral Resources

1. Office work before fieldwork

a) Collecting geological, mineral, environmental, engineering geological, hydrographic, and other relevant materials;

b) Synthesizing, processing, analyzing, and predicting areas with marine sand mineral resources based on geological and geophysical premises and signs.

2. Surveying work

3. Geophysical work

a) High-resolution shallow seismic survey;

b) Side-scan sonar survey.

4. Geological work

Establishing surface sediment maps, prospecting zone maps, and forecasting resource class 334a at a scale of 1:50,000.

5. Construction of survey works and sample collection during survey works.

6. Sample collection, processing, and analysis.

7. Compilation of materials, calculation of resource class 334a, delineation, and recommendation of prospective areas.

Article 6. Contents of Evaluating Marine Sand Mineral Resources

1. Surveying work

2. Geophysical work

a) High-resolution shallow seismic survey;

b) Side-scan sonar survey.

3. Geological work

Establishing various types of surface sediment maps, hydro-geological dynamic maps, and environmental-geological disaster maps.

4. Seabed morphology survey work.

5. Construction of evaluation works and sample collection during evaluation works.

6. Sample collection, processing, and analysis.

7. Forecasting the impact of exploitation activities.

8. Determining utilization capacity, methods, and technologies for marine sand exploitation.

9. Compilation of materials, calculation of resource classes 333 and 222, delineation, and recommendation of prospective marine sand mineral resource areas for transfer to exploration and exploitation.

Article 7. Network for Investigating and Evaluating Marine Sand Mineral Resources

1. Investigation and evaluation lines shall be designed basically perpendicular to the length of the marine sand distribution area or perpendicular to the coastline.

2. The network for investigating and evaluating shall be designed in accordance with the characteristics of the distribution, structural morphology, and size of the marine sand body; topographical features, laws, and degree of variation in thickness and quality.

3. The network of tasks for investigating and evaluating marine sand mineral resources shall be carried out in accordance with Appendix I issued together with this Circular.

4. The network of works for investigating and evaluating marine sand mineral resources shall be carried out in accordance with Appendix II issued together with this Circular.

Article 8. Digital Conversion of Original Documentation

1. Original investigation and evaluation materials on marine sand minerals shall be established in digital form, fully reflecting information as prescribed in Circular No. 43/2016/TT-BTNMT dated December 26, 2016, of the Minister of Natural Resources and Environment on technical regulations for collecting and establishing original materials in basic geological surveys and mineral exploration.

2. Tools, software, applications used must ensure safety and confidentiality.

3. Digital information and data shall be stored and updated on devices of organizations and individuals assigned to perform the tasks.

4. In cases where printing from updated digital files in the system database is necessary, permission is granted;

Article 9. Classification of Geological Structure Complexity Levels, Classification of Areas Based on Difficulty Levels

1. The classification of geological structure complexity levels shall be applied to select the network of tasks and works for investigating and evaluating marine sand mineral resources as prescribed in Appendix III issued together with this Circular.

2. The classification of areas based on natural and socio-economic difficulty levels shall be applied to determine related economic-technical factors as prescribed in Appendix IV issued together with this Circular.

Article 10. Preparation of Investigation and Evaluation Project for Marine Sand Mineral Resources

1. Collection, Synthesis, and Processing of Materials

a) Collecting and compiling research and geological and mineral survey materials, environmental conditions in the investigation and assessment area;

b) Collecting materials on topographical and geomorphological features, seabed depth; climate and hydro-meteorological conditions in the investigation and evaluation area;

c) Collecting materials on economic and cultural characteristics; infrastructure, coastal economic activities, environmental protection; relevant water and land transportation networks in the investigation and evaluation area;

d) Synthesizing and processing materials, delineating preliminary prospective areas for investigation and evaluation;

đ) Conducting preliminary surveys to supplement construction conditions for the project;

e) Analyzing and synthesizing materials, establishing current status maps of the investigation and evaluation area, geological and mineral maps, preliminary investigation and evaluation area maps, and preliminary layout maps for works in the investigation and evaluation areas.

2. Content and Form of the Investigation and Evaluation Project

Article 11. Final Report on Investigating and Evaluating Marine Sand Mineral Resources

1. Content of Work for Preparing the Final Report on Investigating Marine Sand Mineral Resources

a) Processing and summarizing all types of project implementation materials;

b) Establishing drawings with accompanying explanations to accurately reflect the actual geological and mineral conditions in the investigation area;

c) Calculating class 334a mineral resources;

d) Delineating potential areas and proposing to move to the evaluation phase;

đ) Writing the final report on the project.

2. Content of Work for Preparing the Evaluation Report on Marine Sand Mineral Resources

a) Processing and summarizing all types of project implementation materials;

b) Establishing drawings with accompanying explanations to accurately reflect the actual geological and mineral conditions in the evaluation area;

c) Calculating Class 333 and Class 222 mineral resources with appropriate reliability as prescribed;

d) Preliminarily assessing and forecasting the impact of mineral extraction on the environment;

đ) Determining the potential and fields of use for marine sand; proposing suitable extraction methods and technologies;

e) Delineating potential areas and proposing to move to exploration and exploitation phases;

g) Writing the final report on the project.

3. Content and Presentation Format of the Final Report

a) The content and presentation format of the final report shall be carried out in accordance with the management regulations for specialized tasks of the Ministry of Natural Resources and Environment;

b) The content and scientific requirements for specialized maps and accompanying explanatory reports shall be carried out in accordance with the provisions of Appendix V issued together with this Circular.

Chapter II
SEABED MINERAL RESOURCES INVESTIGATION

Article 12. Surveying Work

1. Contents of work:

a) Collect and compile relevant seabed topographic maps;

b) Geodetic positioning and guiding: position, guide, and measure depth for geophysical survey (high-resolution seismic and side-scan sonar scanning), establish physical survey route maps;

c) Measure depth along the route using multi-beam echo sounder;

d) Determine coordinates and depths of sampling points (geological survey stations, drilling machines, vibro-flotation pipes, tide gauge stations);

đ) Tide gauge monitoring;

e) Establish control network for coordinates and elevations to serve the connection of national elevation benchmarks to tide gauge stations;

g) Draw seabed depth maps at a scale of 1:50,000.

2. Technical Requirements

a) Geodetic positioning and guiding: carried out according to Circular No. 06/2022/TT-BTNMT dated June 30, 2022, issued by the Minister of Natural Resources and Environment on National Technical Standards for Topographic Maps at scales of 1:50,000 and 1:100,000;

b) Depth measurement along the route using multi-beam echo sounder according to regulations on depth measurement and establishment of seabed topographic maps using multi-beam echo sounder as stipulated in Circular No. 24/2010/TT-BTNMT dated October 27, 2010, issued by the Minister of Natural Resources and Environment on depth measurement and establishment of seabed topographic maps using multi-beam echo sounder;

c) Determine coordinates and depths of sampling points using satellite GPS technology according to Circular No. 06/2022/TT-BTNMT; coordinate positioning error for geological survey stations is ± 0.7 mm on the map scale (in real field conditions: ± 35 m for a scale of 1:50,000);

d) Tide gauge monitoring and tidal data processing at coastal water level observation stations according to Circular No. 06/2022/TT-BTNMT;

đ) Establish control network for coordinates and elevations: according to Vietnam National Technical Regulation (QCVN) 04:2009/BTNMT issued with Circular No. 06/2009/TT-BTNMT dated June 18, 2009, issued by the Minister of Natural Resources and Environment on National Technical Standards for Coordinate Network Construction; QCVN 11:2008/BTNMT issued with Decision No. 11/2008/QĐ-BTNMT dated December 18, 2008, issued by the Minister of Natural Resources and Environment on National Technical Standards for Elevation Network Construction.

3. Products

a) Original documents as prescribed;

b) Physical survey route maps at a scale of 1:50,000;

c) Seabed depth maps at a scale of 1:50,000;

d) Report on surveying work results;

đ) Surveying work products must be transferred to serve geological and geophysical work.

Article 13. Geophysical Work

1. High-resolution shallow seismic survey

a) Content of implementation

- Conduct high-resolution shallow seismic surveys along designed lines;

- Determine and predict the distribution characteristics, thickness, boundary morphology of geological formations, and stratigraphic division according to different lithological components up to the depth of investigation;

- Detect and link ancient riverbeds, zones containing coarse material with mineral potential; sand banks close to the seabed and buried;

- Forecast shallow gas structures and areas prone to geological hazards;

b) Technical requirements

- Conduct high-resolution seismic surveys according to the following Vietnam National Technical Regulations (TCVN): TCVN 12298-1:2018, Mineral Resource Investigation, Evaluation, and Exploration - High-Resolution Seismic Survey Methods on the Sea; TCVN 12298-2:2018, Mineral Resource Investigation, Evaluation, and Exploration - High-Resolution Seismic Survey Data Analysis and Processing Methods on the Sea; TCVN 12298-3:2018, Mineral Resource Investigation, Evaluation, and Exploration - Part 3: Quality Assessment Methods for High-Resolution Seismic Survey Data on the Sea;

- Seismic survey data must be compared and contrasted with construction project data (drilling machines, vibro-flotation pipes) to calibrate and verify;

c) Products

- Field diary of high-resolution shallow seismic survey work;

- Diagrams of high-resolution shallow seismic survey lines, tapes (including original tapes, original data files, and processed tapes);

- Geological and geophysical cross-sections show boundaries between different sedimentary layers and other geological factors;

- Report on high-resolution seismic survey results;

- Seismic survey work products must be transferred to serve geological work.

2. Side-scan sonar profiling

a) Content of implementation

- Acquire seabed topography characteristics, predict surface sediment composition of the seabed, and delineate marine sand distribution areas;

- Identify seabed topographical and morphological features, submerged objects;

b) Technical requirements:

- Scan width: ≥15 meters each side;

- Resolution: ≤10 cm;

- Side-scan sonar data quality is evaluated based on images obtained at intersections between regular survey lines and check lines. At these intersections, visual examination of the two recorded bands is conducted, compared, and their similarity assessed to evaluate quality. The check line is designed to coincide with the check line of the high-resolution seismic method;

c) Implementation procedure

- Select measurement parameters to obtain the best quality field data and minimize background noise;

- Install equipment and winch systems;

- Set system parameters;

- Adjust the winch up and down to position the towfish at an appropriate distance from the bottom, avoiding noise caused by ship propellers and waves; prevent the towfish from colliding with submerged rocks;

- Data retention includes: original data files in device standard format; data converted to *.tif format;

- Record field diary;

- Process materials using specialized software after completing the survey line, serving geological survey work.

d) Products

- Diagram of side-scan sonar profiling lines;

- Sonar image dataset of the seabed (including original files with integrated coordinates; side-scan sonar bands stitched together by specialized software to fully reflect seabed topography and surface sediment characteristics of the surveyed area);

- Seabed surface maps based on processed sonar data, delineating characteristic topographical and morphological forms, and predicted sediment distribution areas;

- Report on implementation results;

- Side-scan sonar survey work products must be transferred to serve geological work.

Article 14. Geological Work

1. Implementation Content

a) Field construction according to the design network including: taking sediment samples using shovels, core tubes; if sediment samples taken with shovels are mud, then continue taking samples using core tubes; describing and preliminarily determining the characteristics and composition of surface sediment layers; washing and sieving heavy mineral sand samples, evaluating the preliminary content of associated valuable minerals (ilmenite, zircon, monazite, cassiterite).

b) Synthesizing, analyzing, and processing materials for project layout.

c) Synthesizing results from geophysical, topographic, seabed morphology measurements; project construction results, sample analysis results to establish surface sediment layer maps and prospecting and resource prediction maps at scale 1:50,000.

d) Calculating level 334a resources for marine sand bodies.

2. Products:

a) Geological diary, collected specimens, photographic materials;

b) Actual site maps fully displaying all items and quantities of construction works: survey lines, sampling stations, locations; geophysical measurement lines; evaluation works; monitoring stations;

c) Surface sediment layer maps;

d) Prospect zoning and resource prediction maps at scale 1:50,000;

e) Report on implementation results.

Article 15. Construction of Survey Works and Sampling in Survey Projects

1. The location of survey works is designed based on a comprehensive synthesis of seabed morphology, geological, geophysical, and related materials. The survey work network is stipulated in Appendix II issued together with this Circular.

2. Based on water depth, construction conditions, and equipment capacity to select appropriate types of works: drilling machines, vibrating core tubes.

3. Sampling ratio: for drilling machine projects ≥ 80%; for vibrating core tubes ≥ 75%.

4. Drilling at sea using a drilling rig

a) Sea drilling rig

- Using drilling machine equipment XY-1A or equivalent, capable of offshore drilling to depths >20 meters to meet technical requirements;

- The drilling rig must have load-bearing capacity, stability, ensuring a flat installation and operation surface for drilling machine equipment, sample storage, and technical staff working space. Operating depth up to 15 meters of water, hydraulic lifting system or chain hoist, moved by tugboat;

- Service equipment must meet technical requirements for work, construction, and safety at sea;

b) Technical requirements for offshore drilling

- Using rotary drilling technology with a drill diameter of 91 mm; drilling and sampling within a water-proof casing; using saline-resistant drilling fluid and additives to clean the borehole to the next drilling depth;

- Drilling equipment must be placed vertically and attention must be paid to avoid any movement during drilling;

- Water-proof casing must be installed before drilling to protect the borehole wall; using steel casing with a diameter of 110 mm or 127 mm (depending on construction conditions); from the drilling floor to the full drilling depth;

- Continuous sampling and storing in trays while recording detailed information in the drilling log: well name, depth encountered and end of sediment layer, sediment layer thickness, sampling depth, core length, sampling ratio, elevation, coordinates of the well, observer's name, start and end date of the well. After completing drilling, stratigraphic sections of the well are divided and a well stratigraphic column is established, rock samples are collected for each layer, various types of samples are taken as required, and a well acceptance record is established according to current regulations.

c) Sequence of offshore drilling construction

- Moving the drilling rig to the construction area;

- Installing the drilling rig, installing the water-proof casing;

- Checking the rig's stability to ensure drilling construction conditions;

- Conducting drilling and sampling according to the drilling machine technical procedures;

- Collecting drilling data; collecting and packaging various types of samples as specified and designed; ending drilling when the requirements are met;

- Ending the well, establishing a stop-work record confirmed by the Rig Commander, geological technician, and drilling team;

- Lowering the drilling rig after completion, moving to another position;

5. Sampling using vibrating core tubes

a) Installation of equipment

- Installing lifting equipment (A-frame crane, hydraulic crane and equivalents) on the ship, the height of the lifting equipment above the construction deck (ship deck) must not be less than 7 meters;

- Installing parts of the vibrating core tube assembly;

- Synchronizing between lifting equipment, winch, vibrating core tube assembly, checking safety, and conducting trial operations.

b) Construction process for sampling

- The crane lifts the equipment off the construction deck, moves it outside the ship deck, and releases it to move down to the seabed;

- When the equipment touches the seabed, the vibration system starts operating. The sample tube penetrates deeper into the sediment layer under the seabed and the sample remains in the tube. When reaching maximum depth or survey depth, the tube retention mechanism is activated to keep the sample intact in the tube;

- Pulling the entire equipment back onto the deck. Removing the sample tube, numbering, describing, and photographing.

6. Work on collecting and establishing original documentation

a) Work on collecting and establishing original documentation is carried out according to Article 8 of this Circular;

b) Collected samples are placed in trays, divided into layers, described, and estimated for sampling. Sample trays are 1.0m long, divided into 5 compartments, with lids. All collected samples are brought ashore for sampling by splitting the samples. One half is stored in the sample tray as prescribed, the other half is processed according to the principle of splitting the apex and sending various types of samples for processing and analysis.

7. Products

a) Project description book, actual site diagram, project drawing, statistical book, photographs of core samples or samples taken by vibrating core tubes every meter; photographs of project coordinates;

b) Comprehensive stratigraphic columns of projects clearly showing the characteristics of marine sand layers including: distribution depth, thickness, layering, interbedding degree; sediment composition, structure, color of layers, and supplemented with analytical results;

c) Sampling record book for various types.

Article 16. Sampling, processing, and analysis of samples

1. Sample for particle size analysis

a) Sampling: at evaluation projects where the target mineral sand has been identified, 100% of the sample quantity shall be analyzed. For evaluation projects where the marine sand target is not clearly defined, 25-30% of the sample quantity shall be analyzed for surface sediment layer survey samples. The weight of each sample sent for analysis shall range from 1.0 kg to 2.0 kg.

b) Sample analysis: particle size distribution shall be analyzed using sieving and hydrometer methods according to TCVN 4198:2014.

c) Result processing: construct cumulative curve charts, particle size distribution charts, mean grain size (Md), sorting coefficient (So), skewness coefficient (Sk), uniformity coefficient (Cu), gradation coefficient (Cc), run the program, and classify sedimentary environments according to the construction soil classification method TCVN 5747:2008.

d) Quality control samples shall be taken from each batch of samples at a rate of 10%.

2. Comprehensive quantitative sampling

a) Sampling: group sampling shall be conducted from drill holes on representative cross-sections within the marine sand deposit. Sample weight: 2.0 kg/sample.

b) Sample analysis: use a sieve set to separate particles into different size fractions (0.063-0.1; 0.1-0.25; 0.25-0.5; 0.5-1.0; >1.0 mm), then analyze each fraction under a microscope.

c) Result processing: evaluate the basic characteristics of the particle size and major minerals in the marine sand deposit.

3. Thin section analysis of loose sediments

a) Sampling: take samples from the product layers of evaluation projects on representative cross-sections of the marine sand deposit.

b) Sample weight: 0.5 kg/sample.

c) Result processing: evaluate the basic features of the marine sand minerals and interpret the origin of the sediments.

4. Heavy mineral samples

a) Sampling: representative heavy mineral group samples shall be taken from evaluation projects; comprehensive heavy mineral samples shall be taken from drill holes on representative cross-sections within the marine sand deposit. Sample weight: heavy mineral group samples, ranging from 1.0 kg to 2.0 kg, washed and separated to obtain heavy minerals; comprehensive heavy mineral samples have a weight ranging from 2.0 kg to 4.0 kg.

b) Sample analysis: carried out according to TCVN 13380:2021 Coastal Heavy Minerals - Determination of Mineral Content - Heavy Mineral Method.

c) Result processing: evaluate the content of heavy minerals (ilmenite, monazite, zircon, cassiterite, etc.) in marine sand.

5. Thermal and X-ray diffraction analysis

a) Sampling: take fine-grained sediment (clay, silt) from the core samples of evaluation projects, representing the marine sand deposit. Sample weight: 0.2 kg/sample.

b) Sample analysis: carried out according to TCVN 13597-1:2022 Soil, Rock, Ore - Determination of Kaolinite Mineral Composition by X-ray Diffraction Method and TCVN 13597-2:2022 Soil, Rock, Ore - Determination of Kaolinite Mineral Composition by Thermogravimetric Analysis Method.

6. Comprehensive silicate analysis: determine the main oxide composition of marine sand: SiO2, Al2O3, FeO, Fe2O3, CaO, Na2O, K2O, MgO, MKN,...

a) Sampling: group sampling shall be conducted from drill holes on representative cross-sections within the marine sand deposit. Sample weight: 1.0 kg/sample.

b) Sample analysis: carried out according to the standards for Silicate Group Soil, Rock, Ore TCVN 9910:2013; TCVN 9911:2013; TCVN 9911:2013; TCVN 9912:2013; TCVN TCVN 9913:2013; TCVN 9914:2013; TCVN 9915:2013; TCVN 9916:2013; TCVN 9917:2013.

c) Result processing: evaluate the main composition in the marine sand deposit and its potential release into the environment during extraction.

7. Spectroscopic analysis of elements in soil and rock to determine the content of major elements (Mg, B, Br, I, Sb, As, Mn, Cu, Zn, Cd, Hg, Pb, Cd,...) in marine sand.

8. Analysis of biological and chemical carbonates (CaCO3, FeCO3, MgCO3, MnCO3)

a) Sampling: samples shall be taken from evaluation projects, representing the ore body. Sample weight: 0.5 kg/sample.

b) Result processing: evaluate the percentage content of biological and chemical carbonates in the ore body.

9. Collection and preliminary environmental water quality analysis in accordance with Table 1 of QCVN 10:2023/BTNMT National Technical Regulation on Marine Water Quality, issued by Circular No. 01/2023/TT-BTNMT dated March 13, 2023, of the Minister of Natural Resources and Environment.

Article 17. Compilation of documents, estimation of resources, delineation, and proposal of areas with potential

1. Compilation and processing of field survey documents on geophysics, topography, construction project results, and sample analysis results.

2. Estimation of level 334a resource.

a) Documents used for estimating marine sand resources include seabed surface layer survey results, geophysical measurements of sand layers verified by projects; quality analysis results of marine sand.

b) Method for estimating marine sand resources: using geological block or cross-section methods, encouraging the use of specialized software when estimating marine sand resources.

c) Resources are estimated in cubic meters.

3. Proposal of areas with potential marine sand resources to be transferred to the evaluation phase when the area has a level 334a resource scale >10 million cubic meters.

Article 18. Products of mineral resource investigation

1. The report on the investigation of marine sand minerals must fully, truthfully, and scientifically reflect the achieved results; propose areas with potential for transfer to the evaluation phase.

2. Accompanying drawings and appendices must reflect the entire results of each project phase.

3. The original document system shall be implemented according to the provisions of Article 8 of this Circular.

Chapter III
ASSESSMENT OF MARINE SAND MINERAL RESOURCES

Article 19. Geodetic work

1. Scope of work

a) Geodetic positioning tasks for route guidance, depth measurement along the route using echo sounders, determination of coordinates and depths of sampling points, sea level monitoring, establishment of control grids for coordinates and elevations shall be carried out according to the provisions of Clause 1, Article 12 of this Circular;

b) Drawing seabed depth maps at a scale of 1:25,000 to serve the establishment of thematic maps of the project and the calculation of marine sand mineral resources.

2. Technical Requirements

a) Route guidance geodetic positioning: carried out according to Circular No. 06/2022/TT-BTNMT; the deviation between the design and physical geophysical route shall not exceed ± 1.0 mm on the map scale (in reality: ± 25m for a scale of 1:25,000); coordinate positioning error of survey points ≤ ±10 m;

b) Depth measurement along the route using multi-beam echo sounders according to regulations on hydrographic surveys and seabed topographic mapping using multi-beam echo sounders issued together with Circular No. 24/2010/TT-BTNMT;

- The mean square error of the depth of the geophysical measurement point after conversion to the national height system is determined by the formula and shall not exceed the following limits: m ≤ ± 0.30m when the depth is up to 30m; m ≤ 1.5% of the depth when the depth is from 30-100m, where: m is the mean square error of depth; n is the number of intersection points; Δ is the difference in depth between the sounding line and the verification line at the intersection point of two sounding lines; the depth at this intersection point is interpolated from the two nearest sounding points before and after the intersection point on each sounding line;

- The difference in depth between the sounding point and the verification point shall not exceed 1.5 times the allowable mean square error of depth (not exceeding ± 0.30m when the depth is up to 30m and 1.5% of the depth value when the depth exceeds 30m.

c) Determination of coordinates and depths of sampling points using satellite GPS positioning technology according to Circular No. 06/2022/TT-BTNMT; the coordinate positioning error of geological survey stations is ± 0.7 mm on the map scale (in reality: ± 17.5 m for a scale of 1:25,000);

d) Tide gauge monitoring and tidal data processing at coastal water level observation stations according to Circular No. 06/2022/TT-BTNMT;

d) Establishment of control grids for coordinates and elevations: according to Technical Regulations QCVN 04:2009/BTNMT; QCVN 11:2008/BTNMT;

e) Drawing seabed depth maps at a scale of 1:25,000

- Seabed depth maps at a scale of 1:25,000 are drawn based on the results of echo sounder depth measurements along the route and the coordinates and depths of geophysical, geological, and other relevant survey points of the project;

- Seabed depth maps at a scale of 1:25,000 have basic contour intervals of 1 meter; technical specifications, mathematical basis, content, and symbols of the map are implemented according to Circular No. 06/2022/TT-BTNMT; Circular No. 12/2020/TT-BTNMT dated September 30, 2020 promulgating Technical Regulations on the content and symbols of national topographic maps at scales of 1:10,000 and 1:25,000.

3. Products

a) Original documents: coordinate and depth logbooks; tidal water level observation logbooks; geophysical traverse measurement logbooks; GPS measurement books; leveling books; depth tapes;

b) Geophysical survey route maps at a scale of 1:25,000;

c) Seabed depth maps at a scale of 1:25,000;

d) Report on surveying work results;

đ) Surveying work products must be transferred to serve geological and geophysical work.

Article 20. Geophysical Work

1. High-resolution shallow seismic measurements shall be carried out in accordance with Clause 1, Article 13 of this Circular.

2. Side-scan sonar profiling shall be carried out in accordance with Clause 2, Article 13 of this Circular.

Article 21. Geological Work

1. Scope of work

a) Implement field construction according to the design network as stipulated in Point a, Clause 1, Article 14 of this Circular;

b) Synthesize, analyze, and process geological and geophysical data to design evaluation works;

c) Synthesize results from geophysical and topographic surveys, seabed geomorphology, construction results of evaluation works, and sample analysis results to calculate marine sand resource volumes;

d) Calculate Class 333 and Class 222 resources for marine sand bodies.

2. Products

a) Geological diary, collected specimens, photographic materials;

b) Actual documentation maps fully displaying all project items and quantities: survey lines and stations, sampling locations; geophysical measurement lines; evaluation works; monitoring stations;

c) Surface sediment layer maps;

d) Drawings serving resource calculation and tables summarizing marine sand body resources in the evaluation area;

e) Report on implementation results.

Article 22. Seabed Morphological Survey Work

1. Scope of work

a) Conduct field construction along geological survey lines and stations, collecting comprehensive information on seabed topography, surface sediment layers, and hydrodynamic factors. During the survey, process information to propose supplementary surveys or checks for areas with special seabed morphologies (long depressions, high submerged banks, etc.); identify geological formations related to mineral resource concentrations;

b) Process, synthesize survey documentation, analytical results, and research outcomes from other methods to establish seabed morphology maps.

2. Products

a) Morphological diary; reference images (if available);

b) Actual documentation seabed morphology map at a scale of 1:25,000;

c) Seabed morphology map at a scale of 1:25,000 established based on morphodynamic principles and displayed on the seabed depth map, meeting the following requirements:

- On the map, different morphological units with distinct formation characteristics must be delineated;

- Special topographical features (high ridges, depressions, ancient riverbeds, old shorelines, etc.), lithological characteristics, and hydrodynamic factors should be represented using symbols;

- Any changes in shoreline and seabed movement (if present) should be shown as lines and zones;

- Morphological units favorable for marine sand accumulation or prone to geological hazards (if present) should be indicated using non-proportional symbols.

Article 23. Construction of Evaluation Works and Sampling within Evaluation Works

The construction of evaluation works and sampling within evaluation works shall be carried out in accordance with Article 15 of this Circular.

Article 24. Sample Collection, Processing, and Analysis

1. Group of samples for evaluating marine sand quality: sample collection, processing, and analysis shall comply with the provisions of Article 16 of this Circular.

2. Group of samples for determining usage fields

a) Samples for analyzing usage criteria for marine sand

- Sampling: collect group samples at representative evaluation works according to resource volume calculations. Sample weight: 10 kg/sample;

- Analytical criteria orientation: particle size distribution; bulk density, volume density, and water absorption; void volume density and porosity; moisture content; clay, dust, and silt content; organic impurities; alkali-silica reactivity; chloride content, etc.;

- Sample analysis to determine suitability for construction sand use shall follow TCVN 13754:2023 for saline sand in concrete and mortar;

- Result processing: determine the fineness modulus of marine sand, evaluate construction and fill material criteria;

b) Mechanical and physical sample analysis: ensure one comprehensive mechanical and physical sample per sediment layer to determine the mechanical and physical properties of marine sand bodies and underlying sediment formations

- Sampling: collect undisturbed core samples from evaluation works representing marine sand deposits, sample length: 25 cm;

- Analytical criteria: particle size distribution, bulk density, volume density, moisture content, porosity, void ratio, saturation, internal friction angle, cohesion force, compression coefficient, modulus of deformation, swelling, disintegration, permeability coefficient, etc.;

- Result processing: evaluate the mechanical and physical properties of the deposit and marine sand materials;

c) Embankment sand compaction tests

- Standard compaction test to determine optimal moisture content (Wt.ư) and maximum dry unit weight according to TCVN 4201:2012 and 22TCN333:06. Sample weight: 15 kg/sample;

- Test to determine CBR index and compaction factor K according to 22TCN332:06. Sample weight: 35 kg/sample;

- Laboratory tests to determine soluble sulfate and chloride ion content in water;

- Sampling: collect group samples from representative cross-sections of marine sand deposits in evaluation works;

- Result processing: evaluate embankment properties of marine sand materials;

d) Total radioactivity analysis:

- Sampling: collect group samples from representative cross-sections of marine sand deposits in evaluation works. Sample weight: 1.0 kg/sample;

- Sample analysis: conduct according to TCVN 10758-6:2016 (ISO 18589-6:2009) on Radioactivity Measurement in the Environment - Soil - Part 6: Determination of Total Alpha Activity and Total Beta Activity or equivalent standards;

- Result processing: evaluate radiation safety for humans when using marine sand materials;

đ) Technical (technology) samples: to assess the usability of marine sand in its raw state and after processing and treatment.

- Sampling: collect large representative samples of marine sand deposits through trial suction. Number of samples: 1-2 samples. Sample weight required: 15-20 m³/sample;

- Analytical criteria: particle size distribution, fineness modulus; void volume density, bulk density, porosity, dry unit weight, saturated unit weight, dust, silt, organic impurities, surface dry moisture content, chloride content, SO3 content, 14-day expansion rate of mortar in 1M NaOH at 80°C.

- Processing results: report on evaluation, comments, and recommendations regarding extraction technology, sand recovery factor; results of processing mixed impurities and salt-contaminated sand; physical and chemical properties of salt-contaminated sand samples; assessment of the cleaning capacity of salt-contaminated sand samples; assessment of the concrete manufacturing capability of salt-contaminated sand samples; assessment of the salt-silicate alkali corrosion resistance of salt-contaminated sand samples; recommendation for areas of use for marine sand.

3. Sample group: Environment

a) Marine sediment environmental assessment

- Sampling requirements:

+ Collect fine-grained sediment samples (clay, mud, sandy mud, etc.) intercalated within core samples of evaluation projects, representing the mineral body. Weight of each sample: 0.3 kg/sample;

+ Four column samples of fine-grained sediments representing different mineral bodies (two samples from mineral bodies characteristic of river mouth areas with high modern material accumulation, and one sample from other mineral bodies) to assess persistent organic compounds;

+ Sampling and preservation methods follow TCVN 6663-15:2004 standards (ISO 5667-15:1999) Water Quality - Sampling - Part 15: Guidance on preservation and handling of mud and sediment samples.

- Analysis requirements:

+ Analyze exchangeable ions of clay for 15 parameters; Quantitative analysis of Fe2+, S in pyrite minerals, Fe2+ in siderite minerals, easily soluble Fe2+, easily soluble Fe3+, reduced S, total S; Persistent organic compound analysis; Microfossil assemblage sample analysis including microfossil, pollen, nanoplankton, and diatom samples;

+ Determine sediment quality parameter values according to QCVN 43:2017/BTNMT National Technical Regulation on Sediment Quality, issued by Circular No. 78/2017/TT-BTNMT dated December 29, 2017 of the Minister of Natural Resources and Environment.

- Assess marine sediment environment based on the limit values of sediment quality parameters specified in Table 1 of QCVN 43:2017/BTNMT.

b) Marine water environmental assessment

- Sampling requirements:

+ Samples taken at the assessment area. Number of samples: 01 sample;

+ Sampling and preservation methods follow TCVN 5998:1995 standards (ISO 5667-9:1992) Water Quality - Sampling - Guidelines for Sampling Seawater.

- Analysis requirements:

+ For coastal waters, analyze according to the criteria specified in Table 1 of QCVN 10:2023/BTNMT;

+ For nearshore waters, analyze according to the criteria specified in Table 3 of QCVN 10:2023/BTNMT;

+ For offshore waters, analyze according to the criteria specified in Table 4 of QCVN 10:2023/BTNMT;

+ Determine seawater quality parameter concentration values according to QCVN 10:2023/BTNMT.

- Assess marine water environmental quality based on the limit values of parameters specified in QCVN 10:2023/BTNMT.

Article 25. Impact Prediction of Extraction Activities

1. Hydrodynamic Investigation Work

a) Survey route, collection of bottom current, surface current, tide, wave, and physical water parameters; trend of sediment movement (erosion zone, accumulation, and balance);

b) Measure meteorological and oceanographic factors as follows:

d) Evaluation results include wind regime; current; waves; water level; trend of near-bottom sediment transport; characteristics of beach accretion and erosion; predict pollution areas based on hydrodynamic conditions of the investigation area.

2. Geological Environmental and Geohazard Investigation Work

a) Survey and collect information on surface sediment and marine water environment. Surface sediment requires determination of sediment composition, color, taste, toxicity potential, basic environmental sediment parameters; bottom-dwelling organism composition and ratio; representative sampling to evaluate sediment environmental quality (according to QCVN 43:2017/BTNMT). Marine water environment requires identification of human activity pollution signs (oil slicks, waste, other discharges), assess dispersion potential under hydro-oceanographic conditions; measure and collect parameters; representative water sampling to evaluate water environmental quality (according to QCVN 10:2023/BTNMT);

b) Survey geohazards, including coastal erosion, channel filling, subsidence, environmental pollution, sand flow, erosion, shelf collapse, shallow gas manifestations;

c) Conduct environmental monitoring combined with hydrodynamic monitoring. Monitoring contents are stipulated in Clause 3 of this Article;

d) Compile geophysical, surface sediment, geomorphology, hydrodynamic data, analytical results, clarify environmental characteristics, delineate and forecast pollution areas when extracting marine sand; propose solutions to minimize environmental pollution during and after extraction;

đ) Prepare a report on implementation results, establish a geological environment - geohazard map at scale 1:25,000, and other required documents.

3. Continuous Monitoring Station Work

a) Establish monitoring stations, collect data in the investigation area. Minimum number of marine stations in the 0-30 meter water depth area: 02 stations;

b) Monitoring must be conducted for at least one year, with two rounds per year (dry season and rainy season). Each round of continuous monitoring lasts seven days at fixed stations, and may extend up to fourteen days if necessary;

c) Orientation of monitored factors, frequency of monitoring:

Frequency of monitoring at continuous stations

d) Monitoring techniques: at continuous monitoring stations, carried out in accordance with Article 9 "Technical Regulations for Comprehensive Survey of Marine Resources and Environment from Depths of 20m and Above Using Ships" issued together with Circular No. 57/2017/TT-BTNMT dated December 8, 2017 of the Minister of Natural Resources and Environment;

đ) Preparing reports on the results of implementation and monitoring at continuous monitoring stations, comprehensive monitoring logs, sample logs, original data files for marine elements and other documents as prescribed.

4. Building numerical models

a) Information and data must be collected from official sources, legally recognized, ensuring reliability and accuracy. The collected data need to ensure detail according to the requirements of the computational domain, grid of the model and scale of the map products that use the model results for editing;

b) Based on specific calculation and forecasting requirements, conditions for applying the model and practical information and data available to analyze and select appropriate models;

c) The models used must ensure the calculation and prediction of dynamic factors (water level, waves, current flow), sediment transport (erosion, deposition) and the dispersion of suspended sediments caused by marine sand extraction activities. For areas with interaction between rivers and seas, the model must integrate factors affecting from rivers and factors affecting from the sea;

d) The current flow model and the model of the dispersion of suspended sediments caused by marine sand extraction activities are three-dimensional models;

đ) The model must be calibrated and validated before application for calculation and must ensure permissible accuracy according to current regulations;

e) To assess the impact of marine sand extraction on the environment and ecology, the numerical model must calculate two scenarios: the current status scenario and the marine sand extraction scenario. For these two scenarios, the models, parameters, and calculation scenarios include:

Marine sand extraction scenarios include the following factors: area, volume of marine sand extracted; extraction technology; marine sand extraction capacity; duration of each round/trip of extraction; average speed of vessels used to transport marine sand after extraction; marine sand extraction route; total time of marine sand extraction;

g) Products: dynamic field diagrams (waves, currents) according to seasons for the current status scenario and the marine sand extraction scenario, run files with parameters; erosion and deposition forecast diagrams for the current status scenario and the marine sand extraction scenario; run files with parameters; diagrams of the dispersion of suspended sediments caused by marine sand extraction activities under different scenarios; report analyzing and evaluating the impacts of marine sand extraction activities according to scenarios on the environment and ecology in the extraction area and adjacent areas; proposals for solutions to control and minimize the impacts of marine sand extraction activities on the surrounding environment and ecology;

h) After preliminary assessment and prediction of the impacts of marine sand extraction activities, the results of the model must be reviewed by experts before officially reporting to competent authorities.

Article 26. Determination of Utilization Capacity, Methods, and Technology for Seabed Sand Extraction

1. Determination of Seabed Sand Utilization Capacity

a) Conducting technology sample experiments to determine suitable types of construction materials that can be processed from seabed sand (aggregates for mortar, fine aggregates for concrete, fill material), and defining processing and washing procedures. The quality of seabed sand used in construction and transportation must meet technical requirements according to national standards (TCVN).

b) Technology samples must assess the utilization capacity of seabed sand in both untreated and treated states. Based on this, propose areas of use for seabed sand within mineral bodies.

2. Research and Proposal of Seabed Sand Extraction Technology

a) Study global and Vietnamese seabed sand extraction technologies; select and propose appropriate methods, equipment, and technologies for seabed sand extraction;

b) Test extraction to serve technology sample collection and monitoring the impact of seabed sand extraction on the environment;

c) Preliminarily evaluate economic and technical factors, the cost of extracting seabed mineral resources based on: social needs, market conditions; infrastructure; forecasted and estimated resources; mineral quality; capability and methods of extraction and processing; the degree of environmental impact through preliminary forecasts.

Article 27. Requirements for Evaluation Level and Boundary Delimitation for Resource Tier 333

1. Requirements for Evaluation Level of Seabed Sand Mineral Resources

a) Determine basic characteristics regarding shape and distribution of ore bodies;

b) Determine thickness, structure, and stability of ore bodies;

c) Ore quality is determined based on analysis results of samples from evaluation works in the assessment area;

d) Technical sample analysis or extraction and processing technology testing has been conducted to preliminarily determine extraction technology, reasonable and effective resource utilization;

đ) Preliminary assessment and prediction of the impact of seabed sand extraction and use activities on the ecological environment; propose solutions to mitigate and protect the environment.

2. Requirements for Resource Boundary Delimitation

a) The boundary of tier 333 resources is delineated within the scope of the seabed sand body, based on evaluation projects meeting resource calculation criteria, permitted extrapolation with limits according to geological, geomorphological, geophysical data or boundaries of higher-tier resource blocks;

b) The reliability level of tier 333 resources must ensure at least 20%.

Article 28. Requirements for Evaluation Level and Boundary Delineation for Resource Tier 222

1. Requirements for Evaluation Level of Seabed Sand Mineral Resources

a) Determine the size, shape, and establish general laws regarding distribution; internal structure of the seabed sand body, assess changes in thickness, shape, quality of the seabed sand body; delineate the boundary of the seabed sand body meeting resource calculation criteria and other geological objects within the evaluation area;

b) Identify beneficial and harmful components in the seabed sand body; preliminarily determine extraction, processing, and rational use technologies;

c) Regarding marine characteristics, clarify flow factors; delineate affected areas when mining;

d) Hydro-geological dynamics research must determine sediment deposition rates, material sediment movement direction, and assess the potential impact on the natural environment, aquaculture and fisheries areas, and shoreline trends;

đ) Mining activities (if any) within the tier 222 resource boundary do not affect the ecological environment or preliminary selection of mitigation measures to reduce environmental impacts;

2. Requirements for Resource Boundary Delimitation

a) The boundary of tier 222 resources is delineated within the scope controlled by evaluation projects;

b) The reliability level of the resource tier must ensure at least 50%.

Article 29. Compilation of documents, estimation of third-level (333) and second-level (222) mineral resources, delineation, and proposal of prospective marine sand mining areas for transfer to exploration and exploitation.

Clause 1. Estimation of third-level (333) and second-level (222) mineral resources.

Point a) The criteria for estimating marine sand resources shall be determined in specific proposals based on the objectives of using marine sand as fill material and/or other usage fields.

Point b) Methodology for estimating mineral resources: use geological block method, cross-sections, or specialized software; resources are estimated in cubic meters (m3).

c) For accompanying valuable minerals, depending on their variation compared to the main mineral and their concentration, they may be classified at the same level or reduced by one level.

Clause 2. Delineation of areas for transferring exploration and exploitation: compile assessment results, relevant economic and social factors, and delineate areas with conditions for transferring exploration and exploitation.

Clause 3. Implementation of digital transformation in accordance with Article 8 of this Circular.

Article 30. Products of mineral resource evaluation for marine sand.

Clause 1. The report on the assessment results of marine sand resources and accompanying drawings and appendices must reflect all outcomes of the project tasks, evaluate third-level (333) and second-level (222) marine sand resources; forecast the impact and influence of marine sand mining on the environment; delineate areas with conditions for transferring exploration and exploitation.

2. Accompanying drawings and appendices must reflect the entire results of each project phase.

3. The original document system shall be implemented according to the provisions of Article 8 of this Circular.

Chapter VI
IMPLEMENTING PROVISIONS

Article 31. Effective Date

Clause 1. This Circular takes effect from January 28, 2025.

2. In cases where referenced documents in this Circular are amended, supplemented, or replaced, they shall be implemented according to the new provisions.

3. Transitional Provisions

Point a) For projects approved before the effective date of this Circular, continue to implement the establishment of original documents according to Circular No. 43/2016/TT-BTNMT until the completion of the project.

Point b) For projects not covered by point a, Clause 3 of this Article, establish original documents according to Article 8 of this Circular.

Article 32. Implementation Organization

Clause 1. The Director of the Vietnam Geological Survey is responsible for guiding and inspecting the implementation of this Circular.

Clause 2. Units under the Ministry of Natural Resources and Environment and related organizations and individuals are responsible for implementing this Circular.

Clause 3. During the implementation of this Circular, if difficulties arise, related organizations and individuals should report to the Ministry of Natural Resources and Environment for consideration and resolution.

Appendix I

NETWORK OF INVESTIGATION AND ASSESSMENT WORKS FOR MINERAL RESOURCES
MARINE SAND

(Annexed to Circular No. 32/2024/TT-BTNMT dated December 13, 2024 issued by the Minister of Natural Resources and Environment)

Note: Geology* - Geological network: distance between lines/(distance between survey stations on the line).

 

ANNEX II

NETWORK OF INVESTIGATION AND ASSESSMENT CONSTRUCTIONS FOR MINERAL RESOURCES OF MARINE SAND
(Annexed to Circular No. 32/2024/TT-BTNMT dated December 13, 2024 issued by the Minister of Natural Resources and Environment)

 

ANNEX III

CLASSIFICATION OF DEGREE OF COMPLEXITY IN GEOLOGICAL STRUCTURE
(Annexed to Circular No. 32/2024/TT-BTNMT dated December 13, 2024 issued by the Minister of Natural Resources and Environment)

 

ANNEX IV

CLASSIFICATION OF REGIONS BY DEGREE OF DIFFICULTY IN NATURAL AND ECONOMIC-SOCIAL CONDITIONS
(Annexed to Circular No. 32/2024/TT-BTNMT dated December 13, 2024 issued by the Minister of Natural Resources and Environment)

 

ANNEX V

CONTENTS AND SCIENTIFIC REQUIREMENTS FOR SPECIALIZED MAPS AND ACCOMPANYING REPORTS
(Annexed to Circular No. 32/2024/TT-BTNMT dated December 13, 2024 issued by the Minister of Natural Resources and Environment)