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McRobert introduces 3D sewer asset scanning

McRobert Contracting Services has modified standard surveying technology to develop a specialised 3D laser scanning service that provides a comprehensive and detailed view of an asset’s condition.

The development was motivated by the idea that existing technology could be used to make asset inspection safer for personnel and more economical for its clients. The new service was recently used to inspect a Water Corporation asset, which has since been scheduled for refurbishment.

Based in Perth, Western Australia, McRobert Contracting Services is a pipeline project management specialist with nearly 30 years experience providing pipeline maintenance, inspection, plastic welding and fabrication services. To provide the best to service the company’s customers, McRobert has developed a specialised service completing 3D laser scans and CCTV sewer asset inspections.

On the job

A screenshot of point cloud data using RealWorks software.

Recently, the company used 3D laser scanning and CCTV to complete the inspection of a Water Corporation sewer pump station in southwest WA, which is now scheduled for refurbishment. Using this method, the client was able to comprehensively assess the asset’s condition and prioritise the pump station for refurbishment sooner than anticipated.

McRobert was able to use the highly detailed and accurate inspection data in order to precisely prefabricate all of the refurbishment components required for the project. This allows the refurbishment team to spend the minimum amount of time on site, reducing the safety risks to all personnel and the cost to the client in the form of reduced labour costs and other expenses, such as the cost of flow control.

Service delivery change

Without McRobert’s 3D laser scan service, a standard – level two – asset inspection for Water Corporation requires a four-man crew; sewer isolation of the pump station or access chamber; confined space entry; and core sampling of the asset wall. The on-site inspection may take up to 10 hours to complete.

After this, the core sample would be sent to an Australian National Association of Testing Authorities laboratory, where it would be tested for deterioration due to biogenic sulphide corrosion. Sample testing is expensive and time consuming and, when combined with the process of completing an on-site inspection, could result in this level of inspection costing more than AU$20,000.

The scanner and equipment set up in a custom vehicle

By using the 3D laser scanning methodology, the company has been able to reduce the resources needed to complete a level two inspection. This method only requires a two-man crew. The inspection can be conducted while the sewer is live, so no isolations are required, no confined space entry is needed, and no core sampling is required.

Using this method reduces the on-site inspection process to a maximum of three hours, reducing expenditure to approximately 10 per cent of the original cost.

Modifying existing technologies

McRobert developed the 3D scanning methodology by adapting the standard surveying technology currently available on the market.

To provide accurate measurements of McRobert has designed a custom-built safety barrier with a linear rail system, which allows the scanner and CCTV equipment to be lowered into the asset for surveillance. A customised lighting system increases visibility in the asset during inspections and a customised vehicle is used to easily transport equipment between sites.

So far, McRobert’s has completed more than 200 3D laser asset inspections and, of these, approximately 30 per cent showed the asset was in critical condition and requiring immediate attention.

Building a picture

After an inspection, the data collated from the scanner is entered into specialised software and allows the creation of 3D point cloud imagery of the asset, which provides an interactive model that shows the internal structure of an asset as if physically inside it. The model created by these images is then used to assess the structural integrity of the asset walls and to determine the amount of deterioration.

The 3D scanner and a custom built light ring.

From this model, a detailed report assessing all internal components of the asset is generated. Laser imagery, high-definition photographs and videos are also incorporated to provide a detailed snapshot of the asset condition at the time of inspection.

The model can be referred to without the need to see the physical asset and can be accessed well after the inspection has been completed, from anywhere the report can be retrieved.

Making an impact

McRobert’s core business function is to provide access chamber and sewer pump station refurbishments using patented polyvinyl chloride (PVC) methods, as well as plastic fabrications, pressure jetting and CCTV sewer inspection. The company enhances these services by incorporating this new inspection methodology into projects.

The 3D scanning technology is applied as a prelude to sewer access chamber and pump station refurbishments.

Prior to completing a PVC refurbishment, a scan will be performed to find accurate measurements of the asset in its current condition. This supports planning and prefabrication to minimise time spent on site and increase safety.

This article was featured in the March edition of Trenchless Australasia. To view the magazine on your PC, Mac, tablet, or mobile device, click here.

For more information visit the McRobert Contracting Services website.

If you have a project you would like featured in Trenchless Australasia contact Assistant Editor Chloe Jenkins at

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