Quality Level A (QL-A) | Subsurface Utility Information (SUI) Survey

Understanding Quality Level A (QL-A) Subsurface Utility Information (SUI) Survey

Have you ever wondered what a Quality Level A (QL-A) Subsurface Utility Information or SUI Survey is?

At Geoscope, we offer Quality Level A (QL-A) Subsurface Utility Information (SUI) Survey services to ensure your construction, design, or development work is done without damaging the subsurface utilities.

Our team of experts are knowledgeable and skilled in conducting QL-A SUI surveys, adhering to the Australian Standard AS5488 guidelines.

Importance of QL-A SUI Survey

Imagine starting a construction project and accidentally going through an underground fibre optic cable. It raises questions such as whether it was located, and to what confidence level it was achieved. Utility information can sometimes be tricky to decipher with different standards and quality, which can lead to confusion.

An SUI survey and strategically positioned QL-A investigations can help avoid such a nightmare scenario by accurately mapping and locating subsurface utilities. Collecting precision data before any disasters like this can happen is essential.

At Geoscope, we understand that accidentally damaging underground utilities can be a costly and dangerous mistake. That is why our QL-A SUI surveys accurately map and locate subsurface utilities, providing precision data before excavation or any other digging activities are proposed.

Proper training of utility locators on-site conducted by Geoscope

What is Quality Level A (QL-A) Subsurface Utility Information
Survey to the Australian Standard AS5488?

The Australian Standard AS5488 outlines the readers and users’ confidence level when interpreting the
subsurface utility information on a given utility plan, map, or report. Quality level A (QL-A) is the highest quality level and consists of the positive identification of the attribute and location of a subsurface utility at a point to an absolute spatial position in three dimensions.

A validated subsurface utility is considered quality level A. Validation means that it has been proven and confirmed.
The QL-A SUI survey is typically carried out in areas where construction, design, or development work is planned to help prevent damage to the subsurface utilities during excavation or when other digging activities are proposed.

Our team at Geoscope strictly follows the AS5488 standards and requirements to provide our clients with the highest quality level of SUI survey. 

Requirements for QL-A Classification

To classify a utility as a Quality Level A (QL-A), we follow the minimum requirements as per the Australian Standard, which include:

  • Location of surveyed points on surface and subsurface features must be on point
  • Conducting the survey according to Australian Standard AS5488 and providing precise horizontal and vertical location data of the utilities
  • Maximum tolerance of +or- 50 mm, along with other essential information such as the attributes, utility justification, and metadata.

We need to also gather some information on the physically located utility, which we call Attributes:

Attributes for QL-A:

Our QL-A SUI surveys include the following attribute information:

  • Utility owner
  • Utility type
  • Status
  • Material
  • Size
  • Pipe or conduit configurations

Quality level A points should also include important digital information stored as Metadata:

Metadata for QL-A:

Our QL-A SUI surveys also include important digital information stored as metadata, such as:

  • The quality level A acronym conveyed as QL-A
  • The date the data was captured
  • The source of the information
  • The survey locating methods used to obtain attribute information
  • Survey control information used to determine the absolute position of the utility
  • Who were the locators, and who surveyed the utility data?
  • Other technical information that conveys the certainty of the information to clients

Obtaining QL-A Location Level

How do we get a QL-A location level? 

To obtain a QL-A location level, our team physically sights the asset or opens manholes and pits to verify the location through potholing. Once we have located the pipes, we record the data with utility surveying instruments.

We use non-destructive potholing methods to verify Quality Level B SUI survey data obtained through ground penetrating radar and electromagnetic detection methods to locate and map the utilities.

However, if the whole line segment cannot be verified by line of sight, Quality Level A should not be attributed to the line segment between our validated points. This means that if you cannot physically verify it or meet the requirements set by the Australian Standards, the confidence in this location level should be lowered.

Non-Destructive Potholing in SUI Utility Surveys

Non-destructive potholing, also known as hydro excavation or vacuum excavation, is a method of digging that uses pressurised water and a vacuum to excavate soil around subsurface utilities without causing damage. This technique can be beneficial for a SUI utility survey in several ways:

Accurate location of utilities

Non-destructive potholing allows for precise and safe excavation around utilities, making it easier to locate and identify them accurately. This information can be used to update utility records and maps, providing a better understanding of the location and depth of the utilities.

Reduced risk of damage

Potholing can minimise the risk of damage to underground utilities during excavation. This technique can help to prevent costly damage to utility lines, reduce project delays, and increase safety.

Faster surveying

Using non-destructive potholing, utility surveyors can quickly and accurately locate buried pipes and cables, reducing the time required for the survey. This can save time and reduce project costs.

Minimal disruption

Non-destructive potholing causes minimal disruption to the surrounding area, reducing the impact on traffic, pedestrians, and nearby structures. 

Additionally, non-destructive potholing can help increase the accuracy and precision of utility location data. By safely exposing underground utilities, surveyors can gather more detailed information on the location, depth, and condition of the utility. This information can help improve the quality of utility maps and reduce the risk of excavation-related accidents.

Overall, non-destructive potholing is an effective technique for conducting an SUI utility survey. It can provide accurate location data, reduce the risk of damage, speed up the survey process, and minimise disruption to the surrounding area.

Our non-destructive potholing technique increases the accuracy and precision of utility location data. By safely exposing underground utilities, our surveyors can gather more detailed information on the location, depth, and condition of the utility.

Call Geoscope before you dig.


Just because we see a pipe or conduit from the outside, it doesn’t mean quality level A SUI data is without its limitations.

Quality level A utility survey may not identify the internal structure or content within the asset. For example, redundant conduits and pipes may be subsequently used by another utility owner for another purpose. Additionally, in some cases, the asset may be damaged, displaced or corroded, and its original alignment may no longer be maintained.

It’s also important to note that quality level A utility surveys do not guarantee the absence of all underground utilities in the surveyed area. There may be utilities that have not been identified, or their location could be incorrect due to issues with the survey method or limitations of the technology used. Therefore, it’s important to continue to exercise caution and follow safe digging practices, even when quality level A SUI data is available.

Advantages of High Utility Quality Level Data in Excavation Projects

Having the highest utility quality level data when working on an excavation project has several advantages, including: 

Increased accuracy

The higher the quality of underground data on the pipes and cables, the more accurate the results will be when working in close proximity. With accurate utility data, you can take actions that are based on having reliable information on the impact of your work.

Better decision-making

High-quality utility information provides better insights, which enables you to make better decisions. With the right information on depth and location, you can identify clashes and opportunities that might otherwise go unnoticed with a lower confidence in utility information accuracy along certain proposed work routes.

Improved efficiency

High-quality utility information data can help you streamline project scheduling and reduce the time it takes to complete work on a certain area, such as a main road upgrade or a congested construction site near the Sydney CBD. With accurate and reliable SUI utility information at your fingertips, you can avoid wasting time and resources on unnecessary hand digging or painfully slow mechanical excavation.

Enhanced productivity

With the right utility data, the ground crews and excavation teams can work more efficiently and effectively, which can help you achieve more work ahead of time. Increased productivity and better overall performance. 

Greater confidence

When it comes to Quality Level A (QL-A) Subsurface Utility Information (SUI) Survey, having high-quality data gives you greater confidence in your project management decisions. Out of the 4 quality levels, A, B, C, and D, QL-A info gives us the greatest confidence in the utility information as we have physically verified the service with our own eyes. Having that confidence that you are making the right choices, I guess, is a good feeling.

By having precise information on the location of underground utilities, contractors can avoid costly delays and unexpected expenses that may arise from damage to critical infrastructure

Measuring the depth of underground utilities
Engineers and Utility locators planning a construction project in Sydney

The Importance of QL-A SUI for Construction Projects

Having accurate and reliable subsurface utility information is critical to the success of construction projects. By using quality level A SUI data, project managers and contractors can avoid damaging underground utilities during excavation and construction activities, reducing the risk of utility strikes and the associated safety hazards, project delays, and cost overruns.

For example, if a contractor accidentally damages a high-voltage electrical cable, it could result in injury to workers, damage to equipment, and even the shutdown of the entire site until the issue is resolved. This can result in significant downtime and project delays, which can be costly and time-consuming.

By obtaining quality level A SUI data, construction professionals can confidently identify the location and attributes of subsurface utilities, ensuring that any excavation or construction work is carried out safely and efficiently.

Contact us today to learn more about our QL-A SUI survey services and how we can help you with your construction, design, or development project.

Non-Destructive Digging Services provided by Geoscope in Sydney, NSW
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Client Testimonials

Know what our clients are saying about us.

Warren Brettoner
Warren Brettoner
Easy to contact and prompt, came back at no extra charge, as they had missed identifying some underground services. Great service would recommend.
Sarah Grima
Sarah Grima
Great service. Explained in detail everything i needed.
Scott Murray
Scott Murray
Job done, nice and easy. Thank you
Najie Kaidbay
Najie Kaidbay
Great response time, easy to communicate with and very accommodating. Highly recommended.
Darryl Savory
Darryl Savory
Punctual, polite and excellent work . A pleasure to deal with
Adam Fitzhenry
Adam Fitzhenry
Great service and report thanks Geoscope.
Geoscope performed Utility/Service services at my property in prep for excavation. The whole process was easy and very friendly staff all round. Impressed by the overall communication and regular checking in post completion of works. I don't think I would have received that from any other company to be honest and gives me a level of comfort that I can call and ask questions if I need to even after works were completed. Will definitely use again! 5 stars from me.
Natasha Donati
Natasha Donati
Geo scope are amazing to deal with and have been very responsive. Everyone on their team is lovely to deal with and also deliver high quality work. Would highly recommend.

Trust Geoscope for Precise & Reliable QL-A SUI Survey Services in Sydney

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