Circular No. 13/2014/TT-BTNMT stipulates technical procedures for investigating and assessing underground water resources.

CIRCULAR

Technical Regulations on Groundwater Resource Investigation and Assessment

_____________

 

Pursuant to the Law on Water Resources No. 17/2012/QH13 dated June 21, 2012;

Pursuant to Decree No. 21/2013/NĐ-CP dated March 4, 2013, promulgated by 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 National Water Resources Management Agency, the General Director of the National Center for Water Resources Planning and Investigation, the Head of the Science and Technology Department, and the Head of the Legal Affairs Department;

The Minister of Natural Resources and Environment issues this Circular on Technical Regulations on Groundwater Resource Investigation and Assessment.

PART I

GENERAL PROVISIONS

Article 1. Scope of Regulation and Applicability

Article 1. This Circular specifies in detail the contents, technical requirements, and products of groundwater resource investigation and assessment tasks:

a) Assessing the quantity and quality of groundwater sources, searching for groundwater sources;

b) Preparing maps of groundwater resources, maps of groundwater source quality zones, specialized maps of groundwater resources;

c) Evaluating the situation of groundwater pollution, degradation, depletion, and salinization; classifying groundwater sources according to levels of pollution, degradation, and depletion;

d) Determining extraction thresholds for aquifers, groundwater storage areas, and areas requiring prohibition or restriction of groundwater extraction;

đ) Evaluating, warning, and forecasting the impacts of climate change on groundwater resources, abnormal changes in the quantity and quality of groundwater sources, and damages caused by water;

e) Determining the potential for artificial recharge of groundwater.

Article 2. This Circular applies to state management agencies for water resources, organizations and individuals implementing projects, programs, and tasks related to groundwater resource investigation and assessment (hereinafter referred to collectively as projects).

Article 2. Purpose of Groundwater Resource Investigation and Assessment

1. To provide information and data on groundwater resources, groundwater exploitation and utilization to serve state management of groundwater resources in territorial areas.

2. To serve as a basis for planning groundwater resources, socio-economic development plans, and related plans.

3. To meet the needs of exploiting and utilizing information for relevant sectors, localities, organizations, and individuals involved in groundwater-related activities.

Article 3. Principles of Groundwater Resource Investigation and Assessment

1. Ensuring compliance with state policies on water resources, basic investigation and assessment plans for water resources that have been approved by competent authorities.

2. Ensuring continuity, synchronization, and uniformity among investigation and assessment scales from general to detailed, and among specialized investigation and assessment types of groundwater resources based on urgent requirements of state agencies.

3. Ensuring synchronization and uniformity between territorial and river basin-based investigations and assessments; between central and local investigations and assessments; and between groundwater and surface water investigations and assessments.

4. Closely combining the provision of information and data to support economic and social development, national defense, security, and sustainable development with the provision of information and data to support state management of water resources.

5. Regularly reviewing, updating, and supplementing information, data, and results of groundwater resource investigations and assessments.

6. Information and data, as well as results of groundwater resource investigations and assessments, must serve the needs of state management, economic and social activities, national defense, security, scientific research, education and training, and other community needs; they must also be compiled and published in the statistical indicators system of natural resources and environment.

Chapter II

CONTENTS AND TECHNICAL REQUIREMENTS FOR GROUNDWATER RESOURCE INVESTIGATION AND ASSESSMENT

Section 1

PROJECT PREPARATION

Article 4. General requirements for project establishment

The content of project establishment work includes: Collecting relevant documents related to the project area, compiling and analyzing documents, designing methods, volume of various types of work, anticipating achievable results and deliverables, planning the organization and implementation, budget estimation, analyzing effectiveness and assessing the level of risk of the project; project establishment work must meet the following basic requirements:

1. Determining the urgency, legal basis of the task, information needs of state agencies and society regarding groundwater investigation and assessment in the project area; the suitability of the investigation task with approved plans and programs.

2. Clearly identifying current information and data, the completeness level of existing information and materials; clearly stating practical issues that need to be resolved.

3. Clearly defining the scope of investigation, natural conditions affecting the construction process; designing technical-scientific solutions, survey and evaluation methods, and volume of work according to professional regulations, ensuring feasibility and suitability with actual conditions in the project area.

4. Clearly defining the implementation plan, funding, organizational structure of the project, leading unit of the project, implementing unit, project leader (if any), cooperating units (if any); clearly assigning responsibilities of the leading unit and cooperating units (if any); developing a detailed schedule for project implementation (from commencement to completion).

5. Clearly defining the quantity and quality standards of expected products, delivery addresses; conditions ensuring the sustainability of the project (management, operation, maintenance after project completion) and anticipated economic, social, and environmental benefits from the project.

Article 5. Requirements for collecting, processing, and summarizing project establishment documents

1. Information and data for project establishment must be complete, accurate, and truthful, collected in accordance with regulations on data collection, management, exploitation, and utilization of natural resources and the environment. In cases where information and data are incomplete, it is necessary to conduct supplementary surveys and investigations to ensure sufficient information for project establishment.

2. Collected documents must be statistically detailed, determining the source of the documents, evaluating the reliability of different sources of information, and assessing the quality of information from survey results in collected documents. Information and data selected for official use must be reliable.

3. Collected information and data must be catalogued, extracting specialized information, classifying information, and creating a data directory on: Geology (quantity, characteristics of geological strata), hydrogeology (aquifer layers, complex systems, water separation, hydrogeological parameters, coordinates, water levels, flow rates, analysis results of water samples at monitoring points, experiments...), geophysics (diagrams, positions of measurement lines and points and parameters), data on water extraction and use (maps, diagrams of locations, coordinates of facilities, extraction data...), current land use data (maps, distribution diagrams of residential areas, industrial zones, craft villages...) and other related data; processing and checking related materials to predict the ability to divide layers, complex systems, water-bearing structures, water separation; boundary conditions of aquifers based on geological characteristics; analyzing characteristics of water-bearing and non-water-bearing layers, dynamics, hydraulic relationships, hydrogeological parameters..., water quality, pollution, salinity, acidification...; evaluated water reserves, ensuring preliminary understanding of natural conditions affecting water resources to guide appropriate investigations.

4. Based on the results of collecting, processing, and summarizing documents, it is necessary to clearly identify missing information, data, and documents that need to be supplemented during project implementation.

Article 6. Requirements for the Content of the Project

1. The content and structure of the project must comply with current regulations on the preparation of investigation and assessment projects for underground water resources.

2. The budget estimate must detail each item of work according to the quantities specified in the project description and consolidate the total budget for the entire project (accompanied by detailed explanations for each item of work); for large projects that cannot yet prepare detailed budget estimates for each item of work, it is possible to prepare general estimates for major items of work, detailed budget estimates can be prepared during the implementation of the project and submitted to the competent authority for approval before implementation; for projects to be implemented over multiple years, the financial requirements must be determined annually to serve as the basis for planning and allocating annual funding.

Section 2

 TECHNICAL REQUIREMENTS FOR ITEMS OF WORK

Article 7. Technical Items of Work in the Investigation and Assessment of Underground Water Resources

Depending on the specific conditions of each region and area, technical items of work used in an investigation and assessment task for underground water resources may include:

1. Collection and analysis of remote sensing data.

2. Field survey and investigation of underground water resources.

3. Geophysical surveys.

4. Drilling investigations and surveys of underground water resources.

5. Experimental pumping, injection (pressurization), and sampling of underground water.

6. Sampling of rock and water samples.

7. Laboratory and field analysis and testing of rock and water samples.

8. Monitoring of underground water resources and related surface water sources.

9. Surveying work.

10. Other specialized tasks.

Article 8. Collection and Analysis of Remote Sensing Data

1. The collection and analysis of remote sensing data used in the investigation and assessment of underground water resources serves the following purposes:

a) To accurately define geological boundaries for the preparation and project formulation stages of small-scale (1:200,000) underground water resource investigation and assessment projects when geological investigation materials are limited, clarifying issues that have been or will be surveyed in the field and designing construction reasonably;

b) To preliminarily identify signs, factors, and delineate areas and zones with potential water-bearing capacity to supplement information during the construction phase of large-scale (1:50,000) underground water resource investigation and assessment projects, enhancing efficiency and shortening the time required for investigation and assessment of underground water resources;

c) To establish geological diagrams at the construction stage of the project to serve detailed research in necessary areas corresponding to larger-scale (greater than 1:50,000) underground water resource investigation and assessment projects in regions without existing geological base maps at the same scale.

2. Principles for Implementing the Collection, Analysis, and Interpretation of Remote Sensing Data are designed for regions with poor transportation, difficult access, complex construction conditions, and limited geological and hydrogeological investigation materials.

3. Contents of the Collection and Analysis of Remote Sensing Data:

a) Collecting remote sensing data within the investigation and assessment area of underground water resources;

b) Calibrating images, registering coordinates, removing noise, and enhancing display quality;

c) Using optical equipment and specialized software to interpret necessary information from collected remote sensing data; interpretation can be carried out at the following levels depending on the degree and scale of investigation and assessment:

- Preliminary interpretation: Serving the preparation and project formulation stages of small-scale (1:200,000) underground water resource investigation and assessment projects;

- Supplementary interpretation: Conducted during the construction phase of large-scale (1:50,000) underground water resource investigation and assessment projects;

- Detailed interpretation: Conducted during the construction phase of the project to serve detailed research in necessary areas corresponding to larger-scale (greater than 1:50,000) underground water resource investigation and assessment projects.

In this context, preliminary interpretation is conducted for the entire project area. Supplementary and detailed interpretations may only be conducted for part of the project area.

4. Design and Construction Requirements:

a) The collection and analysis of remote sensing data must be carried out throughout the investigation and assessment of underground water resources and must be designed reasonably to reduce the density of survey points (reducing the volume of survey points by 20% to 30%) depending on the complexity of the geological structure and the quality of remote sensing materials in the study area;

b) Image interpretation must be conducted from general to detailed, from satellite images to aerial photographs;

c) Depending on the scale of the underground water resource investigation and assessment and the complexity of the geological structure in the study area, the image scale selected must be appropriate to the requirements set forth in Appendix 1 attached to this Circular;

d) The selection of aerial photographs is entirely dependent on the specific situation regarding existing materials in the study area.

5. Product Requirements:

a) For the preliminary interpretation stage:

- An interpretation diagram showing: The location of assembled pieces, scenes used in analysis on the research zoning background; date and time of photography, angle and height of photography, photographic equipment, cloud cover percentage on the image;

- A diagram of interpretation analysis results showing information: Boundaries of geological formations and major geological structures in the region, major fault zones and fracture belts (over 10 km long), zones and areas predicted to have water-bearing capacity;

- A report explaining the interpretation analysis results.

In addition to being shown on the diagrams, the above information must also be directly marked on printed images using highlighter pens or on translucent paper placed directly over printed images using pencils to facilitate field verification and inspection; the analyzed and extracted information does not necessarily need to be verified in the field.

Remote sensing materials used in the preliminary interpretation stage are satellite images (monochrome, color composite, or multispectral) with a resolution of ≥ 30 meters.

These diagrams are displayed at the same scale as the underground water resource investigation and assessment scale.

b) For the supplementary interpretation stage:

- Diagram of image interpretation, showing: The position of assembled pieces, scene images used for analysis; date and time of photographing, angle and altitude of photographing, photographing equipment, cloud cover ratio on the image;

- Diagram of the results of image interpretation analysis, showing information: Boundaries of geological formations, major geological structures in the region and tectonic uplift zones, faults, large fracture zones (over 5 km long); type and predicted movement direction, areas, zones of water outcrop, water collection, potential water storage, and planned detailed investigation and evaluation zones; proposed routes for detailed water resource investigation and evaluation work;

- Diagram of lineament distribution and lineament density, showing: Lineaments with length ≥ 1 km, density (by length, by intersection points) represented by shades and contour lines;

- A report explaining the interpretation analysis results.

In addition to being shown on diagrams, the above information (except for lineament density) must be directly marked on printed images using fluorescent pens or on translucent paper covered over printed images using pencils for field verification purposes. The analyzed and extracted information must be field verified at a ratio of 1:50 (for every 50 information items shown on the diagram, at least one item must be field verified);

Remote sensing materials used in supplementary image interpretation must be satellite images (monochrome, color composite, or multispectral) with resolution ≥ 15 meters;

c) For the detailed image interpretation phase:

- Diagram of image interpretation, showing: The position of assembled pieces, scene images used for analysis; date and time of photographing, angle and altitude of photographing, photographing equipment, cloud cover ratio on the image;

- Diagram of the results of image interpretation analysis, showing information: Boundaries of geological formations, geological structures in the region, tectonic subsidence pits, geomorphic terraces, faults, large fracture zones (over 2 km long); types, widths, and predicted movement directions, water outcrop points;

- Diagram of lineament distribution and lineament density, showing: Lineaments with lengths of 0.5 km or more; density (by quantity - called lineament density, by length - called lineament length density, by intersection points - called lineament intersection point density) represented by shades and/or contour lines;

- A report explaining the interpretation analysis results.

In addition to being shown on diagrams, the above information (except for lineament density) must be directly marked on printed images using fluorescent pens or on translucent paper covered over printed images using pencils for field verification purposes. The analyzed and extracted information must be field verified at a ratio of 1:20 (for every 20 information items shown on the diagram, at least one item must be field verified);

Remote sensing materials used in preliminary image interpretation must be satellite images (monochrome, color composite, or multispectral) with resolution not less than 5 meters, aerial photographs;

d) The project summary phase must establish the following diagrams:

- Diagram of the final adjusted black-and-white aerial photography image interpretation;

- Diagram of the final adjusted satellite image interpretation;

- Digitally processed images, color-combined images, additional digital image classification. Remote sensing analysis method products are considered original intermediate documents and must be submitted for archiving at construction units of the project; remote sensing materials must also be submitted for archiving according to current regulations.

Article 9. Survey and Field Investigation of Underground Water Resources

1. The survey and field investigation work of underground water resources must ensure comprehensive mapping and description according to the investigation scale of all geological entities, topographical, hydrogeological factors, and other factors affecting underground water resources; identify locations where underground water surfaces within the investigation area, delineate the distribution areas of shallow aquifers, degraded underground water areas, saline intrusion, pollution, and address issues related to underground water resources.

2. The survey and field investigation work should arrange routes that traverse the investigation area. The selection of investigation routes to determine the water-bearing structure in the region must ensure cross-sectional cuts through both the structural geology direction and the directions of important aquifers to understand their distribution characteristics, lying conditions, lithological composition, permeability, water richness, and quality. When surveying and investigating stratified water-bearing objects, particular attention should be paid to studying series, systems, groups, layers, and marked strata. Routes should be arranged along erosion basins, places with natural bedrock exposure, and numerous water sources for research. In narrow symmetrical valleys, routes can follow one side with abundant water; in asymmetrical valleys, routes must cover both sides.

Survey and field investigation journeys must be arranged appropriately based on the natural conditions, geological features, and distinctive underground water resources of regions such as Quaternary and Neogene sedimentary formations, karstified carbonate rocks, intrusive and extrusive igneous rocks; coastal plains; folded and faulted regions (regions with exposed bedrock).

3. Content of survey and investigation of underground water resources:

a) Preparation work:

- Accepting the field investigation assignment;

- Determining the content, subject, scope of field investigation: Studying the field investigation assignment and related documents; determining the volume of work to be carried out, identifying the boundaries between major geological formations, faults present in the area on the map; the distribution range on the map of large aquifer complexes, weak aquifers, and water barriers in the investigation area (at scales of 1:100,000 and 1:200,000); the distribution range on the map of aquifer complexes, layers, weak aquifers, and water barriers in the investigation area (at scales of 1:25,000 and 1:50,000);

- Preparing plans, schemes, and routes for field investigation: Determining the positions of the investigation route lines on the topographic map at the investigation scale; developing specific plans and schemes regarding the time schedule for the field investigation work;

- Preparing forms, materials, tools, and machinery and equipment for investigation: Preparing equipment for the investigation work, installing, checking, calibrating, testing, and trial operating machines before field investigation; preparing necessary documents, investigation forms, safety gear, packaging equipment, documents, tools, and supplies for transportation to the site; - Contacting local authorities and completing other preparatory tasks.

b) Conducting field investigations:

- Investigating, collecting, and updating information and data on the characteristics and exploitation and utilization of underground water resources at local agencies in the investigation area;

- Comprehensive route investigation:

+ Investigative journey along lines cutting across aquifer complexes, layers, and structural faults perpendicular to the water-bearing structures in the investigation area to observe, measure, describe, photograph, sketch, delineate, collect information and data on the characteristics and features of aquifer complexes, layers, water barriers, and factors influencing underground water resources; overview the situation of exploitation and utilization, recognize investigation objects and areas, and conduct specialized evaluations;

+ Observing, measuring, describing, photographing, sketching, delineating, collecting information and data on general characteristics of aquifer complexes, layers, including: Distribution ranges of regional domains, discharge zones, groundwater flow directions; current status and trends of water resources, including: water levels, emergence times, discharge volumes, color, taste throughout the year, dry season, flood season, and over multiple years; drought and water shortage situations, flood and depletion conditions, water pollution, and other relevant information and data on underground water resources;

+ Observing, measuring, describing, photographing, sketching, delineating, collecting information and data on certain factors and activities impacting underground water resources, including: Water extraction and utilization projects for various purposes; general characteristics of vegetation cover, terrain slope; main water sources currently being utilized in the investigation area such as rivers, lakes, underground water, water supply facilities, and related information and figures;

+ Identifying and delineating investigation objects and areas for specialized evaluation, including: Main aquifer complexes, layers, and water barriers; regions at risk of pollution and salinity intrusion, and projects affecting water quality; natural recharge and discharge zones and projects affecting water storage; extraction projects and water source characteristics.

- Specialized investigations in regions, areas, and objects: Detailed investigations require observation, measurement, description, photography, sketching, and collection of information and data from various types of investigation points, including:

+ For main aquifer complexes, layers, and water barriers: Distribution range, administrative location, and on the map, main rock and soil components, topographical characteristics, weathering layer, degree of fracturing, administrative and map location of boundaries between aquifer complexes and layers, topographical characteristics, groundwater flow direction, and related factors;

+ Regions at risk of pollution and salinity intrusion: Main types of pollution sources, distribution range, administrative location, and on the map, factors influencing pollution and salinity risks, and related factors;

+ Natural water supply and drainage area: Distribution range, complex system, aquifer layer, administrative location and on map, topographic features, vegetation cover, weathering layer, degree of fracturing; preliminary position, boundary coordinates of the main water supply and drainage areas, primary natural drainage locations, characteristics of the vegetation cover, and some related factors;

+ Drilled wells and excavated wells for groundwater extraction: Coordinates, administrative location, determination of location on the map; preliminary water quality regarding color, smell, taste, pH, electrical conductivity, salinity, DO, temperature; composition, degree of fracturing of soil and rock, topographic features, geomorphology, thickness and characteristics of the weathering layer, vegetation cover; well depth, diameter, static water level, geological stratum for water extraction; flow rate or extraction regime, daily water extraction volume, dynamic water level or pump installation location, suction pipe, water level fluctuation amplitude; purpose of use, water extraction time, and other relevant information;

+ Surface water sources: Coordinates, administrative location, determination of location on the map, exposure position relative to surrounding topography, determination of location on the map; preliminary water quality regarding color, smell, taste, pH, electrical conductivity, salinity, DO, temperature; composition, degree of fracturing of soil and rock, topographic features, geomorphology, thickness and characteristics of the weathering layer, vegetation cover, surface exposure characteristics, surface water source flow rate; current usage status and other relevant information;

+ For karst caves: Coordinates, administrative location, determination of location on the map; preliminary water quality regarding color, smell, taste, pH, electrical conductivity, salinity, DO, temperature; composition, degree of fracturing of soil and rock, topographic features, geomorphology, thickness and characteristics of the weathering layer, vegetation cover, relative height of the cave compared to surrounding topography, current size status of the cave, relationship with groundwater, and other relevant information;

- Collect and preserve water samples for laboratory analysis;

- Organize field investigation data, daily maintenance of equipment including: Checking and organizing investigation records, field notebooks; maintaining machinery and equipment; preliminary assessment of the volume of collected information to adjust the investigation plan and route;

c) Synthesize, organize, and complete the results of the field investigation and submit products:

- Organize and complete field investigation information and data: Investigation forms, field notebooks, maps, and other documents;

- Enter field investigation results, information, and data into computers;

- Process, synthesize, and organize all information, data, and investigation results;

- Prepare reports on field investigation results, diagrams, statistical tables, and summaries of field investigation results;

- Accurately determine the coordinates of locations for drilling investigations, groundwater resource surveys, experimental pumping, experimental scooping, experimental injection, water sample collection, geophysical measurements, and groundwater monitoring locations to carry out survey and measurement tasks arranged alongside the investigation and evaluation mission;

- Complete and hand over the investigation result files and documents.

4. Technical requirements:

a) Groundwater resource field investigation and survey work must clarify key information about the existence characteristics and influencing factors of groundwater resources, including:

- Various types of exposed groundwater sources: Individual point exposures, group source exposures, flowing streams, or seepage;

- Prominent topographic features, geomorphic units, their relationships with geological structure and groundwater resource characteristics;

- Geological exposures: Study distribution characteristics, boundaries of geological sections, soil and rock composition, folds, and fractures;

- Mineral water and hot water sources;

- Artificial structures: Wells, ditches, excavations, boreholes, mine shafts;

- Major hydraulic works: Hydrological stations, irrigation and drainage systems, dams, water conveyance channels;

- Groundwater extraction facilities, treatment, and supply systems;

- Artificial groundwater recharge systems, protected groundwater source areas;

- Marshy areas;

- Pollution points affecting groundwater (cemeteries, mining sites, industrial waste disposal points, village craft waste, chemical warehouses, oil depots);

- Surface water systems: Locations and distribution characteristics of streams, lakes, ponds, marshes, and their relationships with groundwater;

- At each survey and investigation site, observe, investigate, describe, collect samples for analysis, take photographs (if necessary), and record fully the documentation of groundwater and surface water survey points, determine physical properties, and measure certain indicators: pH, TDS;

b) The number of survey routes and sampling points per square kilometer varies depending on the investigation scale and the complexity of the groundwater resource characteristics in the region. With a 1:200,000 scale investigation, the distance between the closest survey points is 2,000 meters; with a 1:100,000 scale investigation, the distance between the closest survey points is 1,000 meters; with a 1:50,000 scale investigation, the distance between the closest survey points is 500 meters; with a 1:25,000 scale investigation, the distance is 250 meters. At moderate complexity levels, there should be at least one survey point per 1 cm² on the map and at least one survey route crossing through; the number of survey routes and points per square kilometer for groundwater resource field investigation and survey is specified in Appendix 3, and the complexity level is determined in Appendix 2;

c) The number of groundwater research points must be at least 60% of the total number of survey points; in areas without exposed points or groundwater survey structures, at least 30% of the survey points must be replaced by drilling and excavation works.

d) In areas where hydrogeological maps at the required scale already exist, groundwater resource surveys and investigations shall be conducted independently; in areas where such maps do not exist or where they were established more than twenty years before the survey period, hydrogeological surveys and investigations combined with groundwater resource surveys shall be carried out; in areas where only part of the surveyed area has hydrogeological maps at the required scale established within the last twenty years, on-site surveys and investigations of groundwater resources shall be conducted independently in that part, while the remaining parts shall be subject to combined hydrogeological surveys and investigations. The content and tasks of supplementary hydrogeological map surveys shall be implemented according to the decision approving the competent state management agency;

đ) Groundwater resource on-site surveys and investigations must be conducted during the dry season of the year;

e) Office processing for all materials for map preparation is regulated as follows:

- Survey and investigation teams must process daily collected data, maintain equipment, and plan for the next day's activities;

- After completing the on-site survey and investigation of groundwater resources in a military camp area (approximately 5 to 6 journeys), before moving to a new location, the results of the survey and investigation team must be reviewed. When unclear information is discovered, a verification journey involving the survey team leader should be organized;

- After each field season, the implementing unit must establish office materials for the entire survey and investigation period, prepare a report on the field results, and prepare acceptance documents for the year;

- The content of office processing includes: Processing description forms, cross-referencing data between survey and investigation teams; preparing actual site documentation maps, on-site groundwater resource maps; completing various sample forms and preparing sample submission forms, preparing lists for sample analysis; preparing plans, material means for the next field season; obtaining analytical results and verifying the reliability of the results using paired check samples; writing reports on field results, preparing annual acceptance documents;

- Field journals must be accurately and truthfully recorded; before each journey, the purpose of the survey, the objects of the survey (geological and hydrogeological sections), types and quantities of survey points, expected number of samples for each object, and the estimated time for the journey must be clearly stated; after each journey, the survey team must summarize and record observations from that journey;

- Actual site documentation maps and office materials must reflect survey points (outcrops, dug wells, drilled wells...), travel routes, sampling points, potential pollution sources affecting groundwater; maps must include geological, hydrogeological cross-sections, standard travel routes;

5. Products of on-site surveys and investigations of groundwater resources:

a) Report on field investigation results:

- Schematic diagrams of actual site documentation along routes and positions of investigation points based on corresponding topographic maps at the investigation scale; all travel routes and research points on these routes must be fully depicted on national topographic maps at the same scale or a larger scale;

- Comparing and verifying remote sensing data interpretation and analysis results (if available) with actual geological, hydrogeological, and groundwater resource factors on travel routes must be conducted, and the accuracy of hydrogeological maps and on-site maps at the same investigation scale compared to survey results must also be verified;

b) Summary and statistical tables of comprehensive and detailed investigation results; statistics of main water extraction and utilization structures by aquifer structure, investigation area, and administrative units;

c) Statistical table of investigated areas;

d) Investigation forms, field journal records, and other investigation materials:

- Groundwater resource field survey and investigation journals must be formatted according to specified models, uniform in size, format, and content. Pages must be numbered, and the name, address of the survey and investigation unit, team name, surveyor names, investigation area, investigation period, and range of survey point numbers included in the journal must be fully recorded. Writing in the journal and field maps must ensure legibility when exposed to water; all descriptions must be written on the right-hand page, illustrative content on the left-hand page; writing cannot be erased, and if errors occur, they can be crossed out and rewritten;

- The content and format of recording and describing in the journal and on field maps must comply with current regulations on the establishment of original survey and investigation materials.

Article 10. Geophysical Work

1. The geophysical methods used in groundwater resource investigation and evaluation must ensure the resolution of one or more of the following main tasks:

a) Clarifying the geological structure characteristics of the region, determining the depth of occurrence of major stratigraphic layers, studying the lithological composition of rocks, identifying folded structures, fault zones, delineating cross-sections around aquifer systems, qualitatively assessing porosity, permeability, and delineating the area of these systems within the survey scope;

b) Evaluating the thickness of the aerated zone;

c) Delineating "windows" in the hydrogeological cross-section;

d) Determining the mineralization level of groundwater, the rate of permeability, and the direction of underground flow;

đ) Determining the location and depth of design for exploration wells;

2. Principles for implementing geophysical work:

a) The geophysical methods used in groundwater resource investigation and evaluation must be selected appropriately according to the investigation tasks and geological, hydrogeological characteristics. The implementation of geophysical work must comply with current regulations on geophysical exploration;

b) General geophysical works can only be carried out after obtaining results from comprehensive works designed in the project such as remote sensing image analysis, groundwater resource investigation and survey. Specifically, geophysical well work can be carried out immediately after the well has been completed and cleaned;

c) The survey ratios for geophysical work must be established based on the investigation tasks for groundwater resource investigation and evaluation; the investigation ratio must correspond to the investigation and evaluation ratio of groundwater resources. In complex geological and topographical conditions, the geophysical survey ratio must be one level more detailed than the investigation and survey ratio of groundwater resources;

d) The distance between geophysical survey lines and points is determined according to the investigation and survey ratio and the investigation tasks for groundwater resource investigation and evaluation. For geophysical well work, the general survey ratio is 1:200 and the detailed ratio is 1:50. The geophysical survey ratios corresponding to the investigation and evaluation ratios of groundwater resources are specified in Appendix 4.1;

3. Technical Requirements:

a) Design requirements for geophysical work: - Geophysical work must be designed based on the principle of inheriting materials from previous stages; - All types of materials collected from previously implemented projects must ensure full information about the project name, spatial coordinates (coordinates), time, and type of equipment used;

b) Requirements for field measurement work:

- Field geophysical measurement work can only be carried out according to plans and technical requirements issued in writing by the leading organization;

- Technical equipment used in geophysical work: Only permitted to use measuring instruments suitable for each method; all types of machines, including newly manufactured ones, must be tested and licensed before being put into production;

- Recording and adjusting field data: Record keeping must follow the templates specified in Appendices 4.2, 4.3, 4.4, 4.5, 4.6, 4.7, 4.8, 4.9, 4.10, 4.11 attached to this Circular and must comply with professional requirements stipulated in the technical regulations for ground electrical, radioactive, and magnetic exploration issued together with Decision No. 79/1998/QĐ-BCN dated December 18, 1998 of the Minister of Industry;

- Operating machines and taking field data must be performed by engineers or technical staff in geophysics;

- The accuracy assessment of geophysical materials is conducted through individual line inspections; inspection results are objective materials based on which the accuracy and quality of geophysical work are evaluated. The amount of inspection may vary depending on the nature and conditions of the work and the quality of field data but must not be less than 5% and more than 10% of the total inspection volume approved for the project;

- Inspections should first be conducted on lines showing unreliable signs; inspectors must be designated by the unit head, and the primary measurer cannot conduct the inspection. If special-purpose measuring instruments are used, the primary inspector may conduct inspections but must be supervised by the inspector;

- Inspection lines must be representative of the quality of completed work in the working area; inspections on lines must be carried out during the field construction period and evenly distributed across the area; inspection errors must meet current requirements;

- During project implementation, the responsible staff member for geophysical work of the construction unit must directly inspect the quality and progress of geophysical work at least three to four times, preliminarily adjust field data, evaluate measurement accuracy, and ensure the required workload;

- The leading unit must appoint personnel to periodically inspect the construction unit's materials at least once during the project construction phase (project). Inspection results must be documented in quality evaluations according to technical regulations for ground electrical, radioactive, and magnetic exploration issued together with Decision No. 79/1998/QĐ-BCN dated December 18, 1998 of the Minister of Industry and Appendices 4.12, 4.13, 4.14, 4.15, 4.16, 4.17, 4.18, 4.19, 4.20 attached to this Circular; it is necessary to clearly record the number of completed items, the number of defective items, and a comprehensive evaluation of the field work materials as the basis for acceptance at various levels;

c) Requirements for office processing and reporting:

- All types of materials must be processed in the office, analyzed comprehensively, and reports prepared;

- Office processing must be carried out by a team of geophysical engineers, with the leader having a professional title equivalent to or higher than that of a senior geophysical engineer;

All geophysical materials must be analyzed qualitatively and quantitatively; quantitative analysis must be conducted using specialized software commonly used.

4. Contents of geophysical works The commonly used geophysical methods include:

a) One-dimensional direct current electrical profiling methods (symmetrical profile, three-electrode profile, dipole-dipole profile with different electrode spacings, intermediate gradient, double symmetrical profile);

b) One-dimensional direct current electrical sounding methods (symmetrical sounding, multi-electrode sounding, loop sounding);

c) Polarization stimulation measurement methods (symmetrical sounding, profiles with different instrument orientations);

d) Natural electric field measurement method;

đ) Induced polarization measurement method;

e) Ground magnetic surveying method;

g) Seismic reflection and refraction measurement method;

h) VLF, GeoRada, geothermal, radiometric, mercury measurement methods;

i) Magnetic and gravity surveying methods for studying geological structures;

k) Electrical logging method for boreholes (determining direction and speed of groundwater flow);

l) Geophysical logging in boreholes. Geophysical methods for investigating and evaluating underground water resources shall be carried out according to the technical regulations currently in force on geophysical exploration in geological and hydrogeological surveys.

5. Requirements for products:

a) Field measurement and data processing products must be presented according to the templates prescribed for each method under the technical regulations on electrical, radiometric, and ground magnetic exploration issued together with Decision No. 79/1998/QĐ-BCN dated December 18, 1998, by the Minister of Industry and relevant current regulations;

b) Office processing products include various types of maps, cross-sections, well geophysical diagrams, and descriptions according to current regulations for each different method.

Article 11. Drilling for investigation and survey of underground water resources

1. Drilling work for investigation and survey of underground water resources must ensure the resolution of one or more of the following tasks:

a) Determining the distribution of water-bearing rock layers and aquifers by depth;

b) Surveying, testing, monitoring, and sampling to study the characteristics of deep groundwater sources;

c) Serving the exploitation of water supply for communities in certain specific cases.

2. Principles of drilling design and construction:

a) The layout of drill holes must be appropriate to the geological and hydrogeological conditions and research purposes, maximizing the utilization of existing wells;

b) The depth of drill holes must be specified in the investigation task. Drill holes in porous aquifers must reach the deepest economically significant aquifer bottom or the planned research aquifer; drill holes in fractured and karstic aquifers must have a drilling depth of at least 40 meters into the fracture zone or the karst development zone; observation wells for hydraulic relationship studies must have filter pipe depths below the lowest possible groundwater level;

c) The structure of drill holes must ensure convenient water testing, stable drill holes, simple technology, minimum cost, and the ability to reuse casing pipes, filter pipes, and easily backfill drill holes;

d) Construction must ensure labor safety and environmental hygiene.

3. Content of drilling work in the investigation and evaluation of underground water resources:

a) Accepting tasks, request files, and surveying to understand construction conditions;

b) Preparing technical design plans for drill hole structures and construction techniques according to the proposed drawings, preparing equipment, tools, and materials;

c) Loading and transporting drilling machinery, equipment, tools, casings, filter pipes, hydrogeological test equipment, raw materials from the assembly point to the site and vice versa or from one site to another during linear construction;

d) Constructing roads to transport equipment, tools, and materials to the drill hole location if necessary, leveling the drilling foundation, excavating the required earth volume for the fluid system and foundation (excavation volume ≤ 5 cubic meters); reinforcing and constructing the drilling foundation and machine base for drill holes deeper than 250 meters or drill holes less than 250 meters placed on weak foundations;

đ) Preparing wood, grinding plates, and other materials to assemble drilling machines and drilling houses; constructing tower and machine bases when the drill hole depth is less than 250 meters (excluding foundation materials);

e) Assembling and disassembling the drilling tower, drilling machine, lighting system, mast, fluid system, and safety system; installing pumps, water pipelines from the water source to the drill hole location, and setting up the fluid mixing station;

g) Selecting isolation grouting methods, preparing grouting materials; machining parts for drilling and isolation grouting; designing fluid pits, producing, and mixing grout;

h) Preparing water supply plans for drilling where drill holes are more than 30 meters away from the water source and the water extraction depth exceeds 8 meters; producing clay slurry, cleaning drill cuttings in the fluid pit system, and checking the quality of clay slurry parameters;

i) Drilling and sampling using alloy bits, ball bits, diamond bits; using mild measures to prevent fluid loss during drilling; describing samples, recording in logbooks, attaching labels, packing samples in sample boxes, and preserving samples;

k) Conducting water level measurements, water sampling, flushing the drill hole with clean fluid, preliminary water pumping for hydrogeological study of the drill hole; protecting and pulling out the casing during drilling; thoroughly flushing the drill hole of drill cuttings, placing the grouting tool plug in the required position, conducting isolation grouting, cleaning, and maintaining machinery and tools after grouting;

l) Backfilling the fluid pit, marking the drill hole, completing drilling documentation, handing over the project; determining the drill hole location before and after drilling, washing the drill hole to serve geophysical and hydrogeological studies; inspecting, completing drilling, handing over the project, and transporting samples from the assembly point to the unit.

4. Drilling construction for the investigation and evaluation of underground water resources must meet the following requirements:

a) The official position and expected depth of the drill hole must ensure compliance with the design requirements indicated based on the results of groundwater resource surveys, geophysical measurements, and other specialized studies; the drilling depth shall be concluded upon achieving the research objectives.

b) Prior to commencing drilling operations, the project leader (project head) must establish a detailed and comprehensive design plan, which must be approved by the head of the leading unit; the construction unit must have a document assigning drilling tasks. The drilling construction design must specify the administrative geographic location (village, commune, district, province), coordinates, purpose of drilling, depth, initial diameter, final diameter, sections for casing pipes, filter pipes, isolation pipes, drilling requirements (core recovery rate, drilling regime and fluid), foundation drilling requirements, transportation route to the drill hole, fuel supply, water washing, drilling materials, organization, labor safety during construction, and data collection requirements during drilling.

c) The drilling method must be suitable for construction conditions, ensuring that the core recovery rate is not less than 65% for loose rock (for gravel, it should not be less than 30-50%) and not less than 75% for hard rock. Drilling fluid must use clean water for fractured hard rock and bentonite slurry with a density of 1.1-1.3 g/cm³ for loose rock, prone to collapse, easy to fill, etc. Natural polymer fluids may be used but must ensure easy cleaning of the drill hole, prevent wall collapse, and be economically effective. After completion, the drill hole must be cleaned with clean water until the water is clear.

d) The diameter of the drill hole must be selected based on the designed flow rate, geological hydrological monitoring and other planned studies, technical requirements for isolation grouting, casing pipe, filter pipe, and the ability to arrange pumps for water blowout testing or experiments.

đ) To isolate water-bearing layers, materials such as clay, cement, a suitable ratio of bentonite+cement mixture, and specialized plugs can be used; after casing and grouting, the drill hole must be inspected for isolation effectiveness; if the isolation is insufficient, the casing and grouting must be redone.

e) Filter pipes for drill holes must be chosen to ensure durability and resistance to chemical, electrochemical corrosion; the water permeability must achieve the maximum possible within the selected diameter, the minimum aperture of the filter pipe must not be less than 20%, and the pipe must allow mechanical cleaning, and in some special cases, chemical cleaning must be allowed if required; the type of pipe must be selected to optimize hydraulic resistance.

g) The diameter of the filter pipe for test pumping drill holes ranges from 91mm to 168mm, while for observation-only drill holes, the filter pipe diameter ranges from 40mm to 90mm. The type of filter pipe (bare, slit, coiled, mesh, grooved, etc.) must be selected appropriately according to the lithology and grain size of the rock in the test aquifer layer.

h) All procedures related to drilling construction, such as construction records, completion, water loss prevention measures, and casing installation, must comply with the regulations stipulated in the Test Pumping Standards for Geological Hydrological Investigations (annexed to Decision No. 46/2000/QĐ-BCN dated August 7, 2000, issued by the Minister of Industry). Each completed drill hole must be inspected and a quality assessment record established; test pumping work can only be conducted at drill holes that have been inspected and found to meet research requirements.

i) Monitoring, describing, and recording in the drilling log during the drilling process must be fully and promptly carried out according to exploration drilling regulations. Factors to monitor include:

- Drilled depth, core recovery rate, lithological composition, condition, degree of fracturing, voids, permeability and water storage capacity, pure drilling time;

- Consumption or additional volume of drilling fluid or wash water, changes in physical properties and parameters of the drilling fluid or wash water;

- Drilling rig drop phenomena and other unusual occurrences during drilling, pre-drill and post-drill water level measurements, observation of water level appearance and stabilization in the drill hole, observation of water spouting or gas emission from the drill hole;

- Arranging core samples into sample boxes and labeling them according to regulations, taking rock and water samples for analysis as required.

5. Requirements for products:

a) Drill holes must meet the requirements regarding research depth, work diameter, allowable deviation, inclination of the drill hole axis, casing pipe material and structure, filter pipe, packing material, grouting material, isolation degree, bottom plug, wellhead protection cap, foundation slab and signboard, and post-drilling ground surface according to the approved design or adjusted design accepted by the competent authority.

b) Technical files and products must be completed and finalized no later than 15 days after the end of drilling. Technical products include: Core samples (which may be condensed according to regulations), drilling logs and geological-hydrogeological observation logs during drilling, actual site diagrams of drill holes, field acceptance records and completed project acceptance records.

c) The technical documentation for drilling must include: Stratification and geological column results of the drill hole, calculation parameters such as core recovery rate percentage, fluid consumption (per meter drilled and per hour), drilling speed, and hydrogeological monitoring charts of the drill hole.

Article 12. Experimental Water Pumping

1. Experimental water pumping used in groundwater resource investigation and assessment must ensure the resolution of one or more of the following tasks:

a) Determining the water richness (flow rate) of aquifers:

- Determining hydrogeological parameters of aquifers (permeability coefficient, hydraulic conductivity, hydraulic transmissivity, head transmission coefficient, release coefficient, seepage, radius of influence, total resistance of riverbed deposits);

- Groundwater flow parameters.

b) Studying boundary conditions of aquifers on maps and cross-sections (relationship between groundwater and surface water, mutual influence of adjacent aquifers);

c) Determining the relationship between flow rate and lowered water level, determining hydraulic resistance near the borehole, water level jump.

2. Principles of water pumping:

a) Experimental water pumping shall be carried out at all exploration and assessment boreholes for groundwater resources and wells that meet the requirements of flow rate and water level;

b) The type of water pumping (single test, cluster test, multi-stage flow rate test, etc.) must be appropriate to the complexity of hydrogeological conditions, actual characteristics of groundwater sources, and project tasks. The basis for selecting the type of water pumping must align with the purpose of pumping, construction methods, equipment, and processing of experimental data.

3. Content:

a) Using air-lift pumps and submersible electric pumps for experimental water pumping in boreholes; using horizontal and vertical centrifugal pumps for experimental water pumping in wells;

b) Experimental water pumping in wells shall be conducted for shallow aquifer domestic wells; application conditions, volume, technical methods, equipment, measurement, and recording of data must be clearly detailed in approved project designs;

c) Experimental water pumping in boreholes shall be performed in various forms such as blowout washing, water testing, and experimental pumping:

- Blowout washing shall be carried out in all boreholes to clean drilling mud, drilling fluid, and other materials blocking the hole, fractures, and filter pipes;

- Water testing shall be carried out in all groundwater exploration and assessment boreholes (except those in cluster tests) to preliminarily assess water richness, storage and permeability properties of aquifer rocks, groundwater quality, and comparative characteristics of different sections of the aquifer;

- Single and cluster experimental pumping shall be carried out in all boreholes meeting project design conditions to determine water richness (flow rate) of aquifers, basic hydrogeological parameters; specifically, cluster tests may determine the hydraulic relationship between groundwater and surface water, mutual influence of adjacent aquifers, and evaluate the groundwater environment according to specific project objectives and tasks.

d) Monitoring water level recovery until complete recovery after stopping pumping or after each stage of lowering the water level during multi-stage tests.

4. Requirements for Design and Construction Requirements for water pumping, duration of pumping, period of conducting pumping, design of pumping, preparation for pumping, organization of manpower during pumping, installation of equipment, sequence of pumping, frequency and method of measuring flow rate, water level, temperature, labor safety requirements, and environmental protection must comply with the Water Pumping Test Regulations for Hydrogeological Investigation issued together with Decision No. 46/2000/QĐ-BCN dated August 7, 2000, by the Minister of Industry.

5. Product Requirements Requirements for data processing, determination of static water level value, average drawdown, and flow rate of pumped boreholes; rules for submitting pumping products must adhere to current water pumping test regulations for hydrogeological investigation.

Article 13. Water injection for testing in drill holes and excavation pits

1. Water injection in excavation pits and drill holes during investigation and evaluation of underground water resources must ensure the determination of soil permeability coefficients at their natural state within the aerated zone.

Clause 2. Implementation principles:

a) Water injection testing in excavation pits and drill holes applies to cohesive soils, naturally structured loose soils, located within the aerated zone, considered homogeneous and isotropic in terms of permeability;

b) The constant head water injection test method or the variable head water injection test method must be suitable for geological and hydrogeological characteristics and the research objectives of the project.

3. Content:

a) Water injection testing in excavation pits:

- Water injection according to A.K. Bondur's method for surface exposed soil layers or those lying at depths not exceeding 2 ÷ 3 meters, with relatively large to very large permeability (large gravel, cobblestone deposits, strongly to moderately weathered soils);

- Water injection according to N.S. Nesterov's experimental method for surface exposed soil layers or those lying at depths not exceeding 2 ÷ 3 meters, with medium to small permeability (fine-grained and clayey soils).

b) Water injection testing in drill holes:

- Using Nasberg's method for incomplete drill holes: Controlling a constant pressure head, measuring seepage flow, stopping the test when seepage flow reaches stability, calculating the soil permeability coefficient based on Darcy's law for laminar flow;

- Using G.I. Barenblatt and B.I. Sekatski's method for complete drill holes: Maintaining a constant water injection rate (Qc) with appropriate values, measuring changes in water level height in the drill hole over time. From the constant water injection rate (Qc) and the changing water level height in the drill hole from H1 to H2 corresponding to measurement times t1 and t2, calculate the soil permeability coefficient based on the theory of unstable fluid motion;

- The water injection testing procedure is detailed in Appendix 5 attached hereto.

4. Design and Construction Requirements:

a) Design requirements:

- The intended location for water injection testing design must collect stratigraphic data in the surrounding area;

- The water injection design must accurately target the object requiring determination of the permeability coefficient.

b) Construction requirements:

- Water used for water injection testing in excavation pits and drill holes must not contain clay particles, suspended dust particles, and other impurities;

- The construction sequence and water injection testing methods must match the object requiring determination of the permeability coefficient.

5. Product Requirements:

a) Intermediate products:

- Compilation and evaluation of collected stratigraphic materials;

- Record book of water injection data for excavation pits and drill holes (details in Appendix 6 attached hereto).

b) Final product (Test Report):

- For water injection in excavation pits: The test report must fully reflect the project name, work item, testing unit, person responsible for the test; the test pit location (coordinates and elevation), test pit number, test pit size; summary of the test pit's geological characteristics accompanied by a geological cross-section of the test pit, equipment used for testing, depth of each ring embedded in the ground, start and end times of the test, constant water column height during the test, processing and calculation procedures for the soil permeability coefficient Kth (cm/s) and evaluation of the soil capillary pressure value, other related information; Detailed procedures for data processing and calculation of the soil permeability coefficient using different methods are provided in Appendix 7.

- For water injection in drill holes: The test report must fully reflect the project name, work item, testing unit, person responsible for the test; the test drill hole location (coordinates and elevation), test drill hole number, drill hole depth and length of the test section, drilling technique and drill hole diameter, distance from the bottom of the drill hole to the groundwater level; summary of the test drill hole's geological characteristics accompanied by a geological cross-section of the test drill hole, equipment used for testing, start and end times of the test, constant water discharge rate (Qc, cm3/s) in the drill hole, processing procedures, calculation of the soil permeability coefficient Kth (cm/s) and evaluation of the soil capillary pressure value, other related information. Detailed procedures for data processing and calculation of the soil permeability coefficient using different methods are provided in Appendix 7.

Article 14. Sampling of rock and water

1. Sampling work in groundwater resource investigation and evaluation must ensure the resolution of one or several of the following tasks:

a) Determining the mechanical, physical, petrographic, chemical characteristics, and permeability of rock layers, air zones, cover layers, separation layers, and bottom sediment layers of rivers, lakes, and swamps selected according to the requirements of the investigation task;

b) Determining the petrographic boundaries of hydrogeological units and aquifers: Determining the chemical composition and quality of water at the sampling location and time according to the design investigation objects;

c) Determining the hydraulic relationship between groundwater and surface water, and among different aquifers;

d) Determining the origin of groundwater.

2. Rock and water sampling must be carried out according to the design, consistent with the research purpose and actual conditions of the investigation area based on the principle that:

a) Samples taken must be appropriate for the distribution of investigation objects and representative of the objects to be studied;

b) The time and location of sampling must ensure typicality;

c) Samples must be collected and preserved using methods suitable for each type of sample, index type, and anticipated analysis and testing methods, without mixing or altering the nature of the samples;

d) Check samples must be taken simultaneously with comparative samples and coded according to the project's regulations.

3. Content of sampling:

a) Sampling of rock and water during the survey and field investigation of groundwater resources;

b) Sampling of rock during the construction of drilling holes and excavation pits for groundwater resource survey and investigation;

c) Sampling of water during water extraction testing work;

d) Sampling of water in monitoring facilities for surface and groundwater dynamics.

4. Requirements for sampling:

a) In the survey and field investigation of groundwater resources, the number of non-intact rock samples taken should be from 5 to 10% of the total number of geological survey points and rock property survey points; the number of water samples allowed to be taken should be from 10 to 20% of the total number of water survey points. Sampling points must be evenly distributed across the areas of aquifers, water-resistant or weakly permeable objects being studied;

b) The number of check samples must reach from 5 to 10% of the total number of research samples, external check samples not less than 2% of the total number of samples;

c) At drilling and excavation works of groundwater resource investigation and evaluation projects, except for core drilling holes, sampling and preservation of rock samples must be carried out. At groundwater and surface water dynamic monitoring facilities, wells and water extraction drill holes, water samples must be taken and sent for analysis to serve water quality assessment;

d) At exposed points (outlet water sources), wells, ditches, samples can only be taken at points representative of an aquifer, a common rock type, a water type, a specific area, or watershed; samples can only be taken after cleaning the sampling location;

đ) Rock samples are taken in the exposed area of the rock under study or where there are drilling and excavation works;

e) Water samples are taken from self-flowing drill holes, water extraction testing sites, and places where water flows out. Samples must be taken at the end of the water level lowering period when the water is completely clear; at monitoring drill holes, samples are taken at the depth of the studied aquifer (at the filter pipe section), samples are taken during characteristic periods, as well as during special changes; before taking water samples, the drill hole must be flushed clean; at rivers, streams, and surface water bodies, samples must be taken away from the shore, at mid-depth (between the water surface and the bottom);

g) Sampling tools, techniques, packaging, and preservation of rock samples must be clean, sealed, ensuring no spillage, mixing, or alteration of the material properties of the samples, affecting their representativeness;

h) Containers for water samples must use glass bottles with rough stoppers, clean polyethylene jugs; before sampling, bottles and jugs must be rinsed three times with the water to be sampled;

i) The size and weight of rock samples must comply with the analysis and testing requirements, specifically designed in the task outline and project;

k) The volume of water samples and the capacity of containers must comply with laboratory regulations; depending on the number of required analysis indices and accuracy requirements, each bottle or jug must have a label according to the regulations; water samples must not contain impurities (sand, algae, debris, sediment, etc.);

l) Processing of various types of samples, transportation, packaging, preservation, or fixation of easily changing materials must follow professional guidance for analysis and testing;

m) The analysis deadline for water samples for each index must comply with technical analysis and testing regulations but not exceed 15 days before sending to the laboratory;

n) For water samples requiring specialized research (gas, radiation, specific elements, etc.), sampling must be carried out according to professional guidelines; water samples for microbiological analysis must be handled according to health authority regulations.

5. Requirements for products:

a) Sampling work must be recorded in relevant documents such as: Survey and field investigation records of groundwater resources, drilling, excavation, water extraction, and resource monitoring documents;

b) Field samples as well as processed and sent for analysis and testing must have labels with sample numbers made of durable materials that prevent tearing, damage, or loss of the sample number;

c) Each water sample must have two labels, one label attached to the bottle or jug, and another label stored in a plastic bag tied to the neck of the bottle or jug; the label content must include: Sampling location, sampling facility (outlet, well, drill hole...), sampling depth, studied aquifer (sampling depth, water temperature, air temperature), sampling time (hour, day, month, year); comprehensive, simple, trace element analysis requirements (Fe, Mn, Cl); sampler (name) must sign;

d) Rock samples must have long-lasting identification numbers, and their investigation locations must be determined. Samples taken during survey and field investigation work need detailed drawings showing the distribution characteristics, composition, and geological structure of the sampling location.

đ) Sampling books and sample submission forms must be established in accordance with regulations; the sample submission form must indicate the sample number, size, weight of rock samples, volume of water samples, number of bottles for one water sample, sampling date, analysis deadline requirements, analysis criteria, tests; the sampling book must include the contents such as sample number, sampling location, sampling depth, size, weight of rock samples, water sample volume, number of bottles for one water sample, physical properties, temperature, analysis and test requirements, sampling date, date sent for analysis, analyzing agency, sampler.

Article 15. Analysis and Testing of Rock Samples and Water Samples (in Laboratory and On-site)

1. The work of analyzing and testing rock and water samples in groundwater resource surveys and assessments must ensure the resolution of one or more of the following tasks:

a) Determining the age, origin, petrographic characteristics, chemical, mechanical composition, and permeability properties of rocks;

b) Determining the chemical, physical properties, quality, and origin of underground water from aquifers.

Clause 2. Implementation principles:

a) The selected analytical and testing methods must be appropriate to the research criteria requirements of the survey task and comply with the project design;

b) The analytical facility and the unit conducting the tests must be assigned based on their capability to meet the research criteria requirements of the project's survey task;

c) Quality assurance in laboratory testing must comply with current professional management regulations;

d) The reliability level of results from laboratory analysis methods for the same task must not be lower than that of on-site testing.

3. Content of Work:

a) On-site Analysis:

- For rock samples: Conduct on-site tests for the mechanical and physical properties of rocks;

- For water samples: Measure and determine the chemical and physical properties of water at the site using portable devices.

b) Laboratory Analysis:

- For rock samples: Analyze geological samples, petrographic composition, mechanical and other specialized analyses of rocks in the laboratory; conduct permeability tests and other types of tests in the laboratory;

- For water samples: Analyze chemical, microbiological, and other specialized criteria of water in the laboratory.

c) Verification Analysis:

- Internal verification analysis conducted immediately in the laboratory to detect random errors in water sample analysis;

- External verification analysis conducted in another laboratory to determine systematic errors.

4. Requirements for Analysis and Testing:

a) Samples must be analyzed in laboratories recognized and permitted by competent state management agencies;

b) Water and rock sample analysis must comply with procedures and standards issued or approved for application by competent state agencies;

c) Analysis and testing results must meet the data usage requirements according to the approved survey task design.

5. Product Requirements:

a) Intermediate products:

- Sample transfer forms must be confirmed by both the sending organization and the analysis and testing organization;

- Analysis and testing result forms: The form must fully display information such as the project name, sampling date, sample submission date, and analysis and testing date; analysis and testing criteria.

b) Final Product (Analysis and Testing Result Report) The report must fully display information such as the project name, sampling date, sample submission date, and analysis and testing date, analysis and testing criteria, correction method and results for different types of samples, evaluation of collected sample results; a summary table of analysis and testing results must be compiled by aquifer, geological water-bearing object, weak water-bearing object, or water barrier; the report must be accompanied by appendices and tables displaying analysis and evaluation results.

Article 16. Groundwater Resource Monitoring

1. Groundwater resource monitoring work must be carried out to ensure the resolution of one or more of the following tasks:

a) Studying the laws of change (immediate, daily, seasonal, long-term) of dynamic factors (water level, flow rate, temperature, chemical composition) of aquifers under natural conditions as well as different destroyed conditions;

b) Studying the relationship between groundwater dynamic factors and natural and artificial factors forming groundwater dynamics;

c) Determining the hydraulic conditions and characteristics of relationships between aquifers and surface water sources (rivers, lakes, seas...);

d) Determining the conditions, properties, and quantities supplied to groundwater from different aquifers under various conditions due to seepage from rainwater, condensation, seepage from surface water, or from other underground water sources; determining the factors and data for calculating and forecasting groundwater reserves;

đ) Determining the conditions, properties, and quantities of drainage from different aquifers into surface flows, into water extraction facilities, into natural outlets in valleys, supplying to other aquifers, or through evaporation from the surface of underground aquifers;

e) Determining the intrusion positions from surface water sources, intrusion from polluted surface water sources into groundwater and their impact on groundwater dynamics;

g) Determining the impact of the aerated zone (thickness, petrology composition, permeability...) on the formation of groundwater dynamics;

h) Determining the impact of soil layers, vegetation cover, and topographic factors on groundwater dynamics.

2. Principles of monitoring in groundwater resource investigation and evaluation projects:

a) The methods and volume of monitoring must be appropriate to the research object and actual construction conditions in the working area;

b) The monitoring design must be suitable for the investigation mission and the planned method, ensuring feasibility in collecting expected data and applying data processing methods;

c) The number and layout of monitoring points must be arranged based on integrating purposes, maximizing the use of existing structures for monitoring, and utilizing current monitoring results in evaluating and processing data.

3. Content of groundwater resource monitoring:

a) Monitoring at exposed sources, drill holes, dug wells, and surface water bodies affecting groundwater with the following parameters and measurement regimes:

- Collecting data from national groundwater resource monitoring stations in the region (if available), consistent with the project's objectives, requirements, and assigned tasks;

- Monitoring water levels, temperature (water and air), and water chemical composition at drill holes and wells;

- Monitoring flow rates, water levels, temperature (water and air), and water chemical composition at self-flowing drill holes;

- Monitoring flow rates, water levels, sampling, and analyzing water samples at water exposure points;

- Monitoring flow rates, water levels, sampling, and analyzing water samples from rivers, streams; for ponds, lakes, swamps, seas, bays, measuring water levels, sampling, and analyzing various types of water samples. The monitoring regime, equipment, tools, techniques, and technology apply according to the Technical Regulations for Groundwater Resource Monitoring issued together with Circular No. 19/2013/TT-BTNMT dated July 18, 2013 of the Ministry of Natural Resources and Environment. Techniques for monitoring flow rates, water levels, and sampling water from rivers, streams, ponds, lakes, swamps, and seas are implemented according to technical regulations for hydrological monitoring. If the survey area has a surface water monitoring station or a national hydrological monitoring station with a position suitable for the required tasks, then collect data from that station without establishing a new one. The use of collected monitoring data or the establishment of a new monitoring station is specifically determined in the approved project. Chemical component indicators to be studied are specifically defined for each region in the project.

b) Field and office data correction:

- Field data correction includes: Converting measured water levels in wells and drill holes to absolute height at fixed measurement points; calculating flow rates to unified units;

- Office data correction includes: Establishing monthly and annual monitoring charts, comparing changes in groundwater dynamic factors with hydrological and meteorological factors. Creating high-water and pressure contour maps. Comparing and assessing correlations and impacts between groundwater and surface water, and among aquifers. Analyzing flow charts, analyzing changes in water levels along monitoring lines to serve calculations and forecasts of potential groundwater reserves, analyzing forecasts of changes in groundwater chemical composition and explaining those changes, predicting groundwater pollution.

4. Requirements for monitoring work:

a) Unpressurized groundwater monitoring (underground water):

- Monitoring work needs to determine the characteristics of the relationship between underground water and surface water and identify and distinguish typical dynamic patterns (coastal type or inter-river type);

- Monitoring work studying coastal dynamic patterns must determine the hydraulic characteristics of the relationship between underground flow and rivers and the river's impact on underground water; the arrangement of monitoring lines studying coastal dynamic patterns and researching the impact of tides on underground water must be perpendicular to the coastline, from the surface water monitoring point to drill holes in sequence moving away from the shoreline, controlling the entire influence zone of surface water;

- Monitoring work studying inter-river dynamic patterns must determine the role of the thickness of the aerated zone and the water conductivity of rocks in this zone; natural underground water dynamics must clarify its dependence on specific meteorological factors (rainfall, humidity, air temperature, pressure, evaporation...) and humidity in the aerated zone. Drill holes for monitoring must be arranged in a line along the flow direction.

- The arrangement of the monitoring network for studying the dynamics of underground water and influencing factors shall be carried out as follows:

+ The monitoring network needs to be arranged to control typical areas of different aquifer layers distinguished by topography, vegetation cover, soil type, lithology of the vadose zone and aquifers, water level depth, drainage conditions;

+ Monitoring points in the alluvial fan and cone of deposition zones at the foot of mountains and adjacent valleys must be arranged along a line from the mountain base (infiltration area) to the lowland (drainage area); some other points need to be arranged along a line following the alluvial fan and cone of deposition zones, including monitoring points located both on the cones of deposition and between them;

+ Boreholes for monitoring in coastal areas where freshwater lenses float above brackish and saline water with the purpose of studying dynamics, explaining formation and balance conditions, understanding spatial (horizontal and vertical) and temporal chemical composition changes under natural conditions as well as when destroyed should be arranged into two lines along the longitudinal and transverse axes of the lens, the final monitoring borehole on the line should be placed outside the lens;

+ Monitoring points in forest areas need to be arranged into two perpendicular lines along the flow direction to control the entire forest area, the final monitoring point should lie outside the influence zone of the forest. Additionally, monitoring points should be arranged at other characteristic locations such as: Watershed divide regions, valleys, abnormally dense areas, places with sudden changes in vegetation cover or lithology;

- Monitoring in forest areas must simultaneously monitor all surface runoff and nearby water bodies to correlate, while also correlating with meteorological data in the region;

- Monitoring work in areas where underground water dynamics have been disrupted by artificial structures such as water extraction, irrigation, and drying out must be arranged both within and outside the influence zone with the following main characteristics:

+ For structures that increase underground water recharge (irrigation), for irrigation canals, monitoring boreholes need to be arranged perpendicular to the canal and start from the water gauge station on the canal, within the irrigated area, there should also be some monitoring facilities arranged in regions with different irrigation regimes;

+ For water extraction structures (for supply or drainage), monitoring points need to be arranged into several characteristic lines starting from the deepest water level drawdown location to beyond the influence range. If the water extraction structure is near a river, lake, or sea with hydraulic connection, a monitoring line from the water extraction structure to the surface water source is required;

- Monitoring work aimed at analyzing changes in underground water dynamics requires collecting research on the operation mode of artificial structures themselves: Operation time, quantity, quality of extracted water for water extraction structures, quota, time, and quality of water for irrigation structures;

b) Monitoring of pressurized groundwater:

- Monitoring work needs to assess the volume and quality of groundwater, predict their changes during exploitation; monitoring points need to be arranged along cross-sections of the water-bearing basin from the supply area to the discharge area, at typical sections ("key sections"), some monitoring facilities need to be arranged to establish "cross-sections" of the flow; monitoring must be conducted simultaneously in all aquifer layers within the cross-section to clarify the relationship between the layers, between pressurized and unpressurized water. Information about the properties of the water-bearing rock (porosity, fracture density, karstification), water level depth, basin type, geochemical conditions when explaining pressure formation processes must be collected;

- When researching pressurized water dynamics disrupted by exploitation, information about the quantity (structures and water), water quality, exploitation regime, as well as the presence of pollution sources within the territory must be collected;

5. Requirements for products:

a) Monitoring products must be established throughout the implementation of monitoring and document correction. Products to be established include:

- Groundwater resource monitoring logbook;

- Groundwater resource monitoring figures;

- Summary of monitoring results;

b) The contents of the products comply with the provisions of the Technical Regulations for Groundwater Resource Monitoring issued together with Circular No. 19/2013/TT-BTNMT dated July 18, 2013 of the Ministry of Natural Resources and Environment.

Article 17. Geodetic Work

1. Geodetic work in groundwater resource investigation and assessment must ensure the completion of one or more of the following tasks:

a) Adjusting topographic map bases to match reality;

b) Transferring works from drawings to the field;

c) Determining the coordinates of survey points according to design, determining the coordinates and elevations of drilling works, groundwater extraction works, test wells for permeability determination, and groundwater and surface water monitoring stations; additionally, delineating geophysical research routes;

d) Transferring works onto maps;

đ) Printing map sheets serving survey work (usually with a scale larger than the investigation scale) and report preparation (maps at the investigation scale);

2. The remaining 60% shall be used to supplement the operating funds of units directly responsible for public debt management at the Ministry of Finance (outside the regular state budget allocation for ongoing operations as currently provided) for the purposes specified in Article 4 of this Decision.

a) Methods and measuring equipment must be designed to suit each region since project planning and approved by competent authorities;

b) Measuring machines must have calibration certificates issued by authorized calibration agencies;

c) Measurement results must comply with permissible errors: On the plane, coordinate error must not exceed 1mm on the map;

d) When conducting the aforementioned geodetic works, regulations, standards, and norms for measurement and mapping issued by state authorities must be followed.

Section 3

 PREPARATION OF INVESTIGATION RESULTS REPORT AND PROJECT COMPLETION REPORT

Article 18. General Requirements for Report Preparation

1. All completed or suspended groundwater resource investigation and assessment projects must prepare an investigation results report and a project completion report for review, approval, and submission to the competent authority and must be archived in the national archives.

2. The investigation and assessment results report approved by the competent authority and submitted for archiving serves as the basis for preparing the project completion report for completed groundwater resource investigation and assessment projects.

3. The investigation and assessment results report must be based on information and data obtained from the implementation of various design works of the project and reliable information and data collected from other sources that have been verified. Project work results must be accepted and evaluated according to the quality management regulations for groundwater resource investigation and assessment.

4. The final report (or project completion report) must reflect comprehensively the entire process of project implementation, actual changes and adjustments compared to the approved content; project products achieved and their potential uses for different purposes and target groups.

Article 19. Content of Investigation and Assessment Results Report Preparation Work

1. Organizing, analyzing, processing, and summarizing all field-collected materials, results of water, soil, and rock sample analysis, previous investigation and research results, and relationships between investigation results of different types of works throughout the groundwater resource investigation and assessment process.

2. Evaluating and concluding on required assessment contents based on processed information and data results.

3. Writing explanatory reports and establishing appendices and drawings in accordance with investigation types and scales.

4. During the final report preparation process, it is necessary to enhance the application of computer tools in processing, statistical summarization, calculation, and presentation of reports to improve work efficiency and product quality.

Article 20. Content of the Report on the Results of Groundwater Resource Investigation and Assessment

The report on the results of groundwater resource investigation and assessment must reflect information appropriate to the type of investigation, the scale and depth of the investigation conducted. The information to be reflected includes:

1. Overview of the main characteristics of water-bearing structures, aquifer formations, large aquifer systems, and weak or impermeable formations within the scope of the investigation and assessment:

a) Distribution area, main rock composition, depth of occurrence, distribution depth on cross-sections, origin of rocks, main areas at some administrative units;

b) Fracturing characteristics, preliminary water-holding capacity;

c) Main hydraulic characteristics, including: Static water level depth, pressure head height, underground water dynamics at outcrops, boreholes, characteristic wells, primary direction of underground water movement;

d) Natural drainage basin characteristics: Distribution range, administrative location, influences on the supply and discharge of underground water sources;

đ) Characteristics of major factors affecting hydraulic properties: Vegetation cover, weathering layer, permeability zone, and other related factors;

e) Characteristics of factors affecting the quantity and quality of water sources: Main constructions and types that affect the quantity and quality of water sources, distribution range, administrative location, and on maps;

g) Summary table of key parameters of water-bearing structures, aquifer formations, large aquifer systems, and weak or impermeable formations with the following main information: Distribution range, administrative location, and on maps, topographic features, vegetation cover, weathering layer, degree of fracturing, positions, coordinates of boundaries between complexes, vegetation cover characteristics, direction of underground water movement, and other related factors.

2. Classification of water-bearing capacity levels of water-bearing structures, aquifer layers, and impermeable formations within the scope of the investigation and assessment:

a) Classification of recharge and discharge zones;

b) Classification of static water level depth and pressure head height zones;

c) Classification of thickness and permeability characteristics of the weathering layer;

d) Classification of permeability characteristics of major water-bearing structures, aquifer formations, and main aquifer systems;

đ) Classification of main vegetation cover distribution.

3. Overview of basic characteristics of dynamic and static groundwater storage according to water-bearing structures, investigation regions, and administrative units:

a) Total storage, dynamic storage, and static storage of groundwater;

b) Spatial and temporal changes in groundwater storage;

c) Characteristics of constructions and major factors affecting groundwater storage;

d) Overview of the potential for exploiting groundwater at investigated extraction facilities: Drilled wells, dug wells, surface springs, karst caves, promising exploitation zones, preliminary exploitable storage.

4. Classification of equivalent modulus of underground flow, average annual infiltration supply, dry season, three-month dry season, and driest month supply for the investigation region.

5. Evaluation of water quality, classification of water quality zones including:

a) General evaluation of water quality for different uses;

b) General evaluation of physical properties, basic chemical component concentrations, total mineralization, main chemical types of groundwater, changes in groundwater quality characteristics over time periods;

c) Characteristics of pollution risk zones, intrusion zones, and main constructions affecting groundwater quality: Main pollution sources, distribution range, administrative location, and on maps; factors influencing pollution risk and intrusion such as: Topographic features, vegetation cover, weathering layer, main constructions affecting water quality, and other related factors;

d) Zoning of water quality suitable for different purposes.

6. Overview of the potential for exploiting and using groundwater to serve rural domestic water supply, urban water supply, and key economic and social areas; evaluation of the potential for exploiting and using groundwater for each sector and field according to administrative units.

7. Appendices and drawings accompanying the report include:

a) List of aquifer systems, aquifer layers, impermeable layers, pollution risk zones, intrusion zones, natural drainage basins, surface springs, karst caves, drilled and dug wells for groundwater extraction;

b) Types of graphs showing current conditions of groundwater extraction and use over time, chemical composition and quality graphs, future groundwater demand prediction graphs for various areas;

c) Diagrams about: Main aquifer system distribution, natural drainage basin areas, pollution risk areas, groundwater extraction facilities, outcrop points, karst caves, distribution and thickness of the weathering layer, vegetation cover;

d) Maps:

- Groundwater resource data map, including information on: Distribution of water-bearing structures, aquifer systems, aquifer layers, impermeable layers, river and lake systems on the surface, land use status, vegetation cover on watersheds, water levels, water level depths, lowered water levels, flow rates, total mineralization at survey points, distribution of hot and mineral water points, areas with different water qualities and exploitable storage, sampling and analysis points for water quality at actual sites, actual survey locations, groundwater drainage zones, primary directions of underground water movement, pollution risk zones, investigation and assessment routes, and other related information from field investigations and assessments;

- Groundwater quality map, including information on: Chemical composition data layer at locations with analytical results, trace element components, organic pollutant components, microbial sample analysis result data layer at each sampling point, pollution zones, intrusion zones, water quality data layer for use objectives, and other information.

- The underground water resource map, including information on: Distribution of water-bearing structures, complexes, aquifers, water flow paths; surface river-lake system, water level, water depth, low water level, flow rate, total mineralization at investigation points, and other relevant information, exploitable regions and layers, potential underground water extraction volume, layers of information on distribution of water-bearing structures, complexes, aquifers, water flow paths, water source characteristics, extraction capacity, and other related information about underground water resources, distribution of hot springs, mineral water, regions with different water quality and potential extraction volumes;

- The subsurface flow modulus map, including information on: Subsurface flow modulus zones, subsurface flow modulus values, points of subsurface flow modulus values, and other relevant information.

8. Special reports accompanying: Characteristics of underground water resources, current status and changes in underground water resources, water quality characteristics.

Article 21. Submission for archival and handover of investigation results

1. All completed project products that have been accepted and meet quantity and quality requirements must be handed over to the user unit (if they are transitional products) or submitted to the storage agency (if they are final products) in accordance with the product submission regulations of the water resources sector issued by competent state agencies. Original samples, primary documents, and other project-related documents not specified in the product submission regulations shall be managed and stored by the project implementing unit in accordance with current laws.

2. The submission dossier includes:

a) One copy of the project and approval decision (including any amendments or supplements if applicable);

b) Project acceptance dossier (in accordance with inspection and acceptance regulations issued by the competent authority);

c) Project products including: Intermediate products (if any), final project products.

3. The submission record serves as the basis for overall project acceptance and approval of project completion in accordance with the provisions.

4. After submission, completed project products must be strictly managed and stored at functional agencies and units responsible for receiving information from specialized state management agencies, and incorporated into the national natural resources and environment information system (excluding classified documents with specific regulations) to provide information for state management needs in each field and exploitation and utilization requirements of ministries, sectors, localities, organizations, and individuals for social welfare purposes and national economic development.

5. All project products must be published in mass media (newspapers, magazines) of state management agencies for natural resources and environment (excluding classified documents according to specific regulations).

Chapter 3

IMPLEMENTING PROVISIONS

Article 22. Implementation organization

1. The Minister, Heads of Ministries equivalent to Ministries, agencies under the Government, Chairpersons of Provincial People's Committees directly under the Central Government, Director of the National Water Resources Management Agency, General Director of the National Planning and Investigation Center for Natural Resources, Heads of subordinate units of the Ministry, and related organizations and individuals are responsible for implementing this Circular.

2. The National Water Resources Management Agency is responsible for guiding and supervising the implementation of this Circular.

Article 23. Effectiveness of Implementation

1. This Circular takes effect from April 7, 2014.

2. During implementation, if there are any difficulties, agencies, organizations, and individuals are requested to promptly reflect them to the Ministry of Natural Resources and Environment for research, amendment, and supplementation./.