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A Basic Overview of the Underground Locators and The Challenges Faced

Published on by Jon Armstrong

Utility Location Services

With the rapid development of infrastructure and advancement in technologies, the utilities lying underground has increased immensely.

From electrical and telecommunications lines to sewage, gas and water pipes, everything lies underneath and locating them in the safest and non-invasive method has become more complex recently.

Accurate underground utility locating and mapping is essential not only for the crew’s wellbeing but also for the unforeseen benefits of companies as well.

The two most challenges faced in utility location services are: 

  1. Weak signal
  2.  Obstruction from other resource

Underground Utility Locating Methods:

 

Electromagnetic (EM) is emitted by underground utilities. Now as electrical lines carry their current, they generate their signals.

However, due to induction, EM signals are also produced by other lines which mean that the utility line reradiates due to the metal present in it.

Also note that as per the composition, the frequency of the reradiated signal varies extensively. Adjusting the locator to the accurate frequency is the major role of any utility location operator. 

Two types of Underground locating methods:

  • Active:

It involves identifying and locating the known utility’s route. Operator sends a definite frequency signal into the ground which is radiated back or connects the underground locator which helps in getting precise location. 

  • Passive:

This method is generally used for locating unknown lines. With the help of locator's receiver, the location service provider searches the EM signals radiated back which help in sweeping the area.

However, unlike the active location method, the passive method isn't able to differentiate between different types of utility lines. 

Different Types of Underground Locators:

Utility Locator
  • Single-frequency locators:

With a simple design and technology, this locator transmits a single high-frequency EM signal. This locator is highly effective in detecting lines on sites with fewer underground lines.

Nevertheless, it is not able to identify the depth of the utility or determine its specific kind. 

  • Multi-frequency locators:

It allows the underground locating operator to pick a frequency to locate and map utilities.

Although frequencies with low range are highly effective in discovering a specific line, its overall ability of detection is still lower than compared to the high-frequency line.

Often, an operator uses high frequencies to discover utilities and later move to low frequency to classify two different utilities. 

Challenges Faced in Underground Utility Locating:

 

Adjusting the signals transmitted by the locator is the most common answer to the underground line locating and mapping challenges.

Here, the operator needs to imply different techniques in altering the existing current’s flow or inducing a signal in the targeted line which helps the locator's receiver to detect it.

To detect the signal more effective, the operator might need to change the location or size of the antenna as well.

Below listed are some of the most common challenges faced in utility location services:   

  • Bad Insulation

Generally, these are one of the most difficult utilities to detect as their insulation deteriorates over time. This phenomenon usually occurs when the metal surface touches the soil.

Here, the metal surface area that touches earth is directly proportional to the degree of signal loss.

  • Near Other Utilities

When many utilities are established at one single point, it becomes difficult to differentiate between two lines. This phenomenon usually happens when a signal which is induced passes from the targeted utility to the one in close proximity instead of the transmitter. This challenge becomes more severe when two lines are parallel for an extended area.

In such situations, the bond between the two electromagnetic fields exhibit only one electromagnetic field which makes it impossible for the locator to distinguish between two utilities. 

  • Utilities Bonded with Each Other

In order to offer a common surface to redirect current to ground, the utilities are tied together. In such situations, the locator can’t stimulate an electromagnetic signal, making it tough to detect the signal that helps in identifying the location of the targeted utility.  

  • Composition

Unfortunately, locators are only able to detect the utility made of metal, i.e. electrically conductive material. Others which are made of terra cotta or plastic goes undetected by the locator. Even the corroded metallic line which hinders the flow of electron cannot be detected.  

  • Depth of Buried Utilities:

EM fields degraded when passes by a soil or any other conductive material. A thick soil layer between the locator’s receiver and utility line will obstruct the locator from locating specific line.

FINAL THOUGHTS:

 

GeoScan Utility & Structural Investigation offers a complete suite of underground utility location services which helps in accurately detecting and locating underground utilities in a non-invasive and non-destructive manner. To further inquire about our services or know how we can help in your next project, feel free to get in touch with us today!

Author's Bio:

 

Jon Armstrong is the industry-leading operator specialises in the structural investigation and cable fault finding. He is closely associated with GeoScan Utility & Structural Investigation which is Dial Before You Dig accredited and with its extensive knowledge and latest technologies have helped many businesses to perform safe excavation. 
 

 

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The Importance of Choosing a Reputed Utility Location Services Provider

Published on by Jon Armstrong

Utility location services are widely used by the construction companies, environmental engineers, drilling companies and pipeline operators. Before undertaking any project that involves digging up the earth or causing any kind of ground disturbance, you need to hire an expert or professional.

Here are the top ways in which leading service providers create a different.

Prevention


One of the main benefits of hiring the underground utility mapping services is for locating underground utilities that can come in the way of construction work. A thorough examination of the underground utilities is a must for the smooth execution of a project. In the absence of that, the exploration can get delayed due to the presence of hazardous utilities. Further, it can even hamper the execution of the project.

Advanced utility locating equipment make detection easy for metallic and nonmetallic pipes, cables and other utilities at various depths. Only a reputed company would have the right set of tools and expertise to offer this service.

Coverage


Underground utility mapping service is important for locating an array of utilities that include voids, storage tanks, gas pipes, water drains and much more. It is mandatory to have a clear picture of the underground utilities to prevent accidents from taking place.

Leaking pipes are amongst the most hazardous utilities. Detecting dangerous material underground ahead of the commencement of a construction project can save the life of workers. This makes finding a reputed utility location services provider inevitable.

Comprehensive Services


While looking for a proficient utility location service provider, it is important to choose one who makes use of top-notch quality, cutting-edge equipment for reaching inaccessible areas uses the latest technology and carries out complete vacuum excavation services of the project site.

So, hiring a reputed utility location service provider is not a choice, but a necessity before undertaking a construction project. This would not only help in avoiding fatal accidents but would also contribute towards completing a project successfully, smoothly and within the stipulated time period.

The thorough examination of the underground would give the workers the needed safety and assurance to carry out the construction task confidently. This would increase the working efficiency and the productivity of the workers.

Author Bio


Jon Armstrong is an accomplished underground utility service technician who has the technical expertise in underground pipe scanning and faulty cable location. He assists an adept team of technicians in the Geelong and Melbourne areas of Australia.

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Step-by-Step Underground Cable Fault Detection

Published on by Jon Armstrong

Locating underground cable fault is much easier now than ever before. There are several methods and advanced detection techniques that make it easier to diagnose faulty underground cables to make your task easier. However, there is no single best method. It involves a series of steps and exemplary skills for precise and accurate fault finding, without damaging the cable.

Even a minute fault reduces the overall functionality of electrical cables and the entire setup. Furthermore, the situation worsens due to cable location, which is often difficult.  As a result, there is no end to problems. The major challenge is to detect accurate underground cable faults through utilities.

Underground Cable Fault Finding: Steps Involved

#1: Sectionalizing

Sectionalizing is the most basic, destructive, and exhaustive method of underground cable fault finding. In this method, experts dig up the suspected location or property for detection, divide it into sections, cut it through, and inspect. There are series of steps involved in inspecting as well as testing each and every section for faulty cable detection. It may even damage the property.

#2: Thumping

Thumping is an innovative method compared to sectionalizing. In this technique, a high voltage, approx 25kV, is set up on an end of the cable and higher current arc is induced in the faulty cable. This is a better method of detection as an arc forms at the exact fault location. In addition, at high voltage, it causes a strong thumping sound audible even above the ground. It may also detect utility.

However, this method is not foolproof. There are certain disadvantages of this technique as well:

  • Firstly, it is often difficult to access high voltage for medium and low priority testing. Even if surge generators are available, it is a cumbersome process.
  • Secondly, the method is ineffective for longer length cables.
  • Thirdly, there are obviously better methods available.

#3: Transmitter-Receiver Method

The method uses an AC generator that supplies signal current to underground pipes and utility. A receiver is used to detect electromagnetic fields from signal current. In certain circumstances, the transmitter contains relevant information related to the resistance capacity of the current circuit.

This method is effective in most of the circumstances of cable detection and fault finding.

#4: Time Domain Reflectometry

An easier method, also called the Pulse Echo Method, enables a tester to calculate the distance to changes in a cable. Introducing radio frequency pulse at one end along with an integrated timer calculates the frequency of travel along the length of the cable. When the frequency reflects, the timer stops.

In this method, there are certain standard values of different materials used for cable construction of different lengths. Using this information, a tester can detect any disparity based on time. Whenever there is a cable fault it changes the cable impedance, thereby affecting the ability to transmit pulses.

The information needed for accurate cable fault finding includes propagation velocity or the maximum distance displayed on TDR along with pulse width.

Final Word

Irrespective of the method applied for underground cable fault detection, accurate spotting is very important. Testers and engineers use sound amplifiers and microphones for better accuracy.

Author Bio: Jon Armstrong specialises in underground cable fault finding and detection. He ensures that you get accurate readings.

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Concrete X-Ray vs. GPR: How to Choose the Right Approach?

Published on by Jon Armstrong

Concrete X-Ray vs. GPR: How to Choose the Right Approach?

Ground penetrating radar is a geophysical method for imaging the subsurface. This method uses electromagnetic pulse signal to detect subsurface objects, voids or cracks.

GPR structural investigation is widely used by local government authorities, civil engineering, petroleum industries, landscaping and irrigation contractors, railway authorities, road authorities etc.

On the other hand, concrete x-ray gives benefit to any type of project that needs cutting, coring or drilling into concrete structures. This process is used to scan structural steel, post tension cables, live electrical wiring, heating lines etc.

How to Compare?

Both of these two processes have some advantages and some disadvantages. But one is considered to be the more practical means of scanning concrete. Here are some points of comparison between the two approaches:

1. Quality of Image:

In terms of quality, concrete ground X-ray provides a better result. The precise quality of an x-ray scan finds out the contents of a concrete slab.

Although GPR technology gets much closer but both approaches have their limits. Concrete x-ray can’t penetrate the slab thicker than 19 inches.

GPR image can be adjusted to penetrate the deep end of the slab, the image quality drops significantly.

2. Price:

Ground Penetrating Radar is more cost-effective. The main reason behind that is Concrete and structural x-ray requires scans of both sides of the concrete slab for proper imaging, whereas GPR only needs access to one side of the slab.

For that reason, slabs-on-grade cannot be scanned with X-ray but they’re routine and perfect for GPR.

GPR requires almost no set-up time. No costly off-site data processing is needed with GPR. Information is provided immediately and marked on the slab. This allows clients to do their work without delay, making the process cost-efficient.

3. Accessibility:

An X-ray process uses a highly radioactive isotope cobalt-60. This requires extra precautions and the technicians need to go through rigorous training sessions before using this.

An X-ray scanning can take more than 5 hours. Yes, this is true that in areas with high electromagnetic activity, GPR scan results are skewed and unusable.

If there are many objects in a concrete slab, finding the right path for cutting becomes harder with this poor image quality, but in most of the cases, Ground Penetrating Radar gives perfect result.

GPR also gives on-site, on-screen imaging which X-ray does not. GPR unit is equipped with an odometer which enables the technician to back up over a target for another look and evaluation in real-time.

4. Safety:

X-ray generates harmful radio waves, GPR is free from that. So there is no potential danger to the technicians or the clients with GPR.

Also, no designated safe area is necessary with GPR but a clear zone of around 100 feet in all directions away from the work area is needed for X-ray.

Conclusion:

Ground Penetrating Radar provides a safer, cost-effective, more versatile option for concrete scanning than X-ray. GPR (Ground Penetrating Radar) is the concrete scanning technology of the future – the versatility outweighs the quickly reducing shortcomings of the image quality. Concrete x-ray is still not out of the market. When the image quality has to be perfect because of safety precautions or otherwise, the X-Ray is the only option.

Author Bio:

Jon Armstrong is an expert in GPR and ground X-Ray techniques. He uses electromagnetic techniques in GPR structural investigation for great results. With many years of experience, he has excelled in these services.

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