What is Underground Surveying? Underground Surveying Applications
What is Underground Surveying?
Underground surveying is a type of surveying that is used to measure and map the features of the earth that are below the surface.
This type of surveying is used to map the location and depth of objects such as pipes, cables, and tunnels. It can also be used to locate subsidence, or the movement of the earth’s surface
Underground surveying is the study of geographically buried materials such as those located in the earth. These materials include rocks, minerals, water, gas, and even oil, and other types of liquid.
The goal is to help engineers and construction companies plan designs for underground construction projects.
A typical construction project involves digging trenches for foundations for buildings, roads or other types of infrastructure.
Underground surveying helps the construction worker avoid any unseen underground obstacles that may be lurking below the surface. This will ensure a safe and efficient construction project.
Underground Surveying Methods
There are several methods of underground surveying including:
This is the process of having a surveyor on hand to go underground and map out the subsurface. This requires special safety equipment including breathing apparatus and protective masks as well as boots, gloves, overalls, and a hard hat.
This type of survey requires several people to perform it properly.
One person is responsible for finding a safe location to set up their equipment at while another person works above ground to drive the truck that will transport them underground.
Magnetic Susceptibility Surveys
In this type of survey, a surveyor would simply need to take a magnet and gently drop it into the ground and run an instrument over the surface.
The instrument would cause the magnet to move to indicate any iron that was in the soil that may be hidden.
This is usually done in conjunction with magnetic surveys and requires special equipment such as a small bomb or thermic blasting machine. The machine will be sealed underground and the operator will bang on the ground with explosives to loosen it.
Magnetic Target Surveys
This type of survey requires a very large magnet that is in the shape of a person. It can be suspended by ropes and dropped into the ground as in magnetic surveys to detect any iron that may be present.
Radio-Magnetic Sounding (RMS) Surveys
This type of survey is usually done with a massive coil in conjunction with nuclear magnetic resonance (NMR).
This is a type of survey that uses sound waves to detect the presence of any ferrous metal in the soil. The NMR will create a magnetic field and the sound waves will bounce off this field and be detected by another set of speakers.
Contrary to popular belief, it is not hearing aids that are used in this type of survey; rather, it is due to the nature of the NMR process.
Surveying and geophysical equipment are used to map subsurface material such as bedrock and foundations for buildings. Sometimes this equipment is used to find buried objects such as archaeological ruins and shipwrecks.
Difference between Underground Surveying and Surface Surveying
Underground surveying is very different from surface surveying. The two methods are used for different purposes and types of materials.
Surface mapping is used to create plans and maps for large areas of land while Underground surveying is used to locate underground obstacles such as piping or wiring as well as to locate natural resources that may be present in the ground like oil and gas deposits.
Underground surveying is normally done by professionals who are trained in a set of special rules and regulations. They will wear special clothing, wear breathing apparatus, and protective masks while they work underground.
Surface surveying, on the other hand, does not require all that equipment. The surveyor usually drives along the surface of a road or field looking for landmarks or setting up reference points.
Underground surveying is normally done at night to avoid any dangers while Surface mapping is done during the day while underground surveying is usually performed in the evening or during the night.
Safety of Underground Surveying
Special safety equipment is required for underground surveying. Professional-grade equipment must be used to ensure that the surveyor is safe while underground.
The equipment normally includes a breathing apparatus, protective masks, gloves, and overalls. Thorough training and certification are also required to ensure professional conduct while working underground.
A lot of planning must be done before the project begins including hiring enough workers, establishing schedules and location of equipment based on the type of project being undertaken.
The work is normally done when the Earth’s surface temperatures are very low in the winter or summer months. This is done to avoid any safety risks.
Surface Surveying Regulations
In order to work in an underground environment, professionals must be licensed by the appropriate government agency and have the proper equipment and training to carry out their profession.
Special regulations must also be followed to ensure the safety of the workers while the project is being carried out.
An underground surveyor must wear a mask and overalls while they are underground. They should also use special equipment such as boots and gloves when they are in contact with the subsurface materials.
It is important that all workers know how to safely conduct a survey while underground. This will ensure that there are no surface rocks or other types of debris that may be encountered during the project.
Surveyors must also know who to contact for help in case of an emergency. They should also have an evacuation plan in place and know how to use the equipment that is required for the specific type of project they are working on.
Underground Surveying Applications
Underground surveying is used for all sorts of applications.
- Gas and oil companies. They may use underground surveys to locate specific geological formations that may contain oil and gas deposits.
- Construction companies may use underground surveying to determine the layout of building foundations or the distance between certain structures.
- Cities, states, and countries may use underground surveys to determine how much water or energy is available in any particular place.
- Archaeologists and historians may use underground surveying to investigate archaeological sites and historical structures that are located near surfaces where vandalism could occur (such as overgrown weeds).
- Utility companies may use underground surveying to determine the best location for their underground gas lines and electrical cables.
- Landowners may use underground surveying to determine the exact location of underground obstacles such as pipes and wires.
- Mining companies may use underground surveying to determine the best location to excavate mountains and forests.
- Industrial and commercial companies may use underground surveying to determine the foundation of any existing structure that may be located underground in an inaccessible location like the side of a river or a remote area of land that has not been developed yet.
- Scientists may use underground surveying to determine how much water is available in underground wells, reservoirs, rivers, and other areas where water is required for consumption, industrial purposes, or other uses such as irrigation.
- Soil erosion and land leveling research may be used to determine the best location to work on agricultural land.
Types of Underground Surveying
There are a number of different types of underground surveying that are available including:
These surveys are performed by digging a trench across the area being surveyed with an instrument called a sounding pole. This sounding pole will contain an indicator that shows the surveyor where the trench is in comparison to other ground points nearby.
In this type of survey, the surveyor walks along a path that is marked out in advance. Lifting instruments with the main purpose of determining the distance between each instrument and ground points are used.
Magnetic surveys can be conducted on an existing pipeline, water pipe, or any other underground structure that has metal components. A massive magnet is used to detect any metal in the earth in order to determine where to lay a new pipe or wireline.
Magnetometry surveys can be conducted on many different types of underground material that may contain ferrous or non-ferrous metallic objects. The instrument will detect the presence of the metal and will indicate the depth of that material below ground.
Soft-ground surveys are used to determine where natural resources or utilities lie below a specific area and to collect samples for further analysis. These surveys can be conducted with a large magnet or with a core sample that is removed from the underground material.
Acoustic surveys use sound waves to detect the presence of metal below ground. Various types of sound waves that can be used include ultrasound and infrasound.
Magnetic Particle Sampling (MPS)
In this type of survey, equipment is used to pull small samples from the ground for analysis. This equipment may include a hand-held magnet or a magnetic drum that can be moved over the ground surface.
Electrical Resistance (ER) surveys
In this kind of survey, the resistance of the soil is measured to detect nonmetallic objects below the surface. The soil resistance will change when a metallic object is encountered below ground. This information is used to determine whether or not certain objects are located in specific areas below ground.
Challenges facing Underground Surveying.
1. Safety issues.
Underground surveying involves the use of underground excavation equipment. Crews will work with heavy machinery and other equipment that can damage the subsurface materials.
The ability of a site to support safe and efficient operations is very important when undertaking this type of project.
2. Surface contamination.
In some cases, underground surveys may disturb surface geological formations which may contain contamination from past mining activities or carelessness in waste disposal procedures.
A risk assessment is needed to assess these issues before an underground survey to determine how to handle them safely and effectively.
3. Wider contamination.
Underground surveys may also cause greater levels of contamination than surface surveys. For example, a survey can disturb the buried remains of an old mine that may contain hazardous materials.
Underground surveying is often undertaken by unskilled workers hired from a crew without a background in engineering or surveying.
It’s important to have qualified professionals on-site to perform these surveys and provide safety guidelines so that the project can be done properly, safely, and on time.
5. Depth of construction.
The deeper underground surveys are conducted, the higher the safety and project costs will be.
However, there is a huge chance to find useful deposits below ground. The choice is up to a company if they want to spend more money on project costs or not.
6. Limited survey methods.
Due to the hardness of the rock, the traditional surveying methods that are used on the surface cannot be used below ground which means that underground surveyors have limited options for their surveys and their results may not be very accurate.
Obviously, the farther a survey is conducted below ground, the more it will cost in terms of safety and travel expenses.
8. Terrain conditions.
The terrain conditions where an underground survey is being performed can affect the quality of the results and may even create more risks to the project if there are any unexpected difficulties that cause delays or problems.
9. Environmental concerns.
There may be environmental concerns related to the destruction of a habitat where an underground survey is performed in order to mine the subsurface materials.
Underground surveys can result in radiation, especially if certain types of radioactive material are located below ground. A radiation survey may need to be conducted before any excavation work begins.
11. Geology issues.
Underground operations can change the geological conditions of the subsurface materials which can affect the results of an underground survey.
Underground Surveying Procedure
The procedure for an underground survey will differ depending on the type of survey to be conducted. However, there are common steps that are undertaken when performing any type of underground survey. These include:
1. Site selection
Site Selection is the first step in undertaking any type of underground survey project. It is important to consider many factors when choosing a site for an excavation including surface resource information, population density and land-use zoning.
2. Disposal of waste
Sometimes underground surveys will disturb the subsurface materials which have historical value where the survey was undertaken. In some cases, it may be necessary to remove these materials for safe disposal.
3. Surface preparation
Surface preparation is needed to prepare the surface over which an underground survey is conducted in order to ensure that it can support safe excavation operations and not cause any unwanted damage to surface formations or geological structures underneath them.
4. Excavation location
Underground surveying may involve digging a trench on the surface or performing auger boring to extract samples of subsurface material. Once a trench has been dug or an auger hole has been created, it is necessary to carefully place the machinery and equipment into this excavation in order to carry out the survey.
5. Conveyance of samples
Sometimes the results of an underground survey will require samples to be extracted from below ground for analysis which can be removed using a variety of methods including hand-held magnets and electromagnetics.
In some cases, it may be necessary to document the subsurface materials that have been uncovered during an underground survey so that they can be analyzed later to determine the extent of their existence and discover any other useful information.
7. Ground stabilization
Sometimes it may be necessary to stabilize the ground surface where an underground survey was carried out in order to prevent further damage or erosion.
8. Site restoration
If a site has been disturbed during an underground survey, it may be necessary to restore the area back to its original condition or an alternate location for the project.
Underground Surveying FAQs
What are underground surveys?
Underground surveys are geological surveys that are undertaken below ground in order to discover any potential materials or resources which may be present below the ground surface.
Do underground surveys use radioactive material?
Underground surveying is a process where a geologist explores the subsurface of the earth which may require them to use some radioactive material in order to perform an effective survey. However, it’s very rare for this type of survey to create radiation and there is no need for anyone nearby to worry about their safety.
What are the methods to transfer surface coordinates to underground surveying?
RTK-GPS will be used to establish the coordinate system above ground, and close-range photogrammetry will be used to transfer the coordinates below ground.
Which method is used to connect surface and underground survey?
If the entrance to the underground tunnel system is via an inclined shaft, the surface survey can simply be extended and continued down that shaft and into the tunnel, usually using the traversing method.
Difference between Underground Surveying and surface Surveying?
Surveying is the same in both cases, but while carrying out a surface survey it is not possible to use deep-radar methods or downhole drilling. In contrast, during an underground survey these methods can be used.
Why do we need an underground survey?
With the development of the mining industry and many other fields, our country has also encountered a great demand for underground surveying.
The importance of underground surveys is that it can find precious metals and minerals which are hard to find by yourself. In addition, there is a great demand for information about the geology of a mine site.
Finally, information about the geological conditions of subsurface strata can be used to determine how to extend the mine.
Can underground survey be used for construction site management?
Underground surveys are primarily used for mining and mineral exploration, but since the terrain in underground surveys is usually very flat, it can also be used for construction site management.
How to prevent subsidence?
When you excavate a lot of earth at once, there is a chance that it will collapse. It is necessary to take measures to reduce the risk of subsidence in advance.
How much time does an underground survey take?
The duration of underground surveying depends on the depth of the excavation and the complexity of the geological structure where it takes place. Usually the deeper and more complicated, then longer will be needed for this work.
What is the difference between power-driven and non-power-driven machines?
The power-driven underground surveying machinery is usually heavier, more expensive, and can transport a larger quantity of materials at once.
The advantages of such machines are that they can move safely in places where it cannot be done by man or animal.
What are the standards for the underground surveys?
There are different standards used by researchers when excavating to conduct an underground survey. The two main standards are ISO and OSHA.
The ISO standard is supported by the International Organization for Standardization, which means that all members of the organization have agreed to follow its rules and procedures.
The OSHA standard can be used if you work for a government agency or if you work in a private company which has more than 50 employees.
What are the main methods for underground surveying?
One of the most popular methods used in geological surveys is trenches. This method often involves the drilling into rock, although this is not the only way underground.
There are also other methods which can be used in conducting the survey, such as a variety of robotic machines.
In order to ensure that every step of an underground survey will be done with due care and attentiveness, it is necessary that precautions be taken during all work.
What is underground traversing?
Underground traversing is the standard method used in surface surveying. This technique helps to determine the location of underground structures and materials.
The process starts by choosing a transverse line and marking it on the surface of the ground or in a shaft, tunnel, mine or any other place where you want to conduct a survey.
After this, measurements should be taken from two points A and B along the transverse line above ground. The distance between these two points should be measured, and then the same should be done for points C and D.
Finally, a measurement should be made from one point A to point C, and from another point B to point D. Furthermore, these two measurements can then be compared with the earlier measurements made above ground.