Canadian Underground Infrastructure Logo

Reduce project risk with underwater laser scanning

By Jason Gillham & Sherry Slejska

ULS-200 underwater laser scanner from 2G Robotics.
ULS-200 underwater laser scanner from 2G Robotics.

Thirty-five million Canadians rely on safe drinking water, making the maintenance, rehabilitation and expansion of water tunnel systems a top priority for service providers. The necessity to fund these projects was partially answered by the 2013 Canadian Federal Budget, calling for a proposed $2 billion to be allocated to municipal water infrastructure projects. Water tunnel systems are about to get the attention they deserve and with the help of improved inspection tools, projects will move forward with a higher level of confidence, ensuring optimal budget allocation.

Regardless of the nature and scope of your water system project, understanding the current condition of the infrastructure is a necessary starting point. Collection of detailed measurements of existing infrastructure can be undervalued at the onset of a project. Project managers may default to traditional methods of data collection, which rely on making significant assumptions. Lack of crucial measurements and incorrect assumptions can derail a project, causing budget, quality and schedule risk.

Our neighbours to the South are embracing improved methods of measuring water infrastructure by using Canadian made laser technology. Commonly used for terrestrial applications, laser scanning is now capable of operating deep inside water tunnel systems to capture detailed measurements. 2G Robotics of Waterloo, Ontario develops and manufactures underwater laser scanners which are reducing the level of assumption and project risk for municipalities by providing precise measurements and 3D models of infrastructure.

The City of Bellingham, Washington understands that more informed decisions are possible when you fully understand the current state of your water infrastructure. They are raising the standards of data collection by using underwater laser scanning.

Needing to understand the condition of the municipality's raw water intake system, accurate measurements of the tunnel system was required. It had been over 30 years since the last inspection, at which time the tunnels had been de-watered. Removal of water can add extra stress to the tunnel, increase down time and increase project cost. The decision to maintain water fill during the Bellingham inspection reduced the risk of further damage.

On this project, the City of Bellingham contracted Interactive Pipeline Inspections (IPI) to perform the survey. IPI deployed an Inuktun Versatrax 150TM crawler which was equipped with submersible cameras, lights and the ULS-200 underwater laser scanner from 2G Robotics.

Inuktun Versatrax 150TM crawler being lowered into the tunnel system.

The ULS-200 laser scanner is designed for close range scanning. Its small size allowed for easy integration into the crawler. The precise geometry of the tunnel was captured as the head of the laser rotated a full 360 degrees, generating a 3D point cloud CAD model. The resulting data provided an accurate digital record of the 3D geometry of the tunnel from which, ovality was assessed and irregularities identified. The 3D point cloud model generated during underwater laser scanning can be exported into CAD software for engineering analysis.

Not every condition is ideal for laser scanning. If there is an excessive amount of light or turbidity in the water a good scan might not be possible. Silt filtering algorithms are able to deal with a surprising level of turbidity in the water but laser scanning would not be the tool of choice for untreated sewer water. 2G Robotics suggests that if you can see the target surface with video, laser scanning is often a good measuring solution.

Under operational conditions, IPI Group inspected the Bellingham tunnel system from several entry points. The cameras fixed to the Inuktun Versatrax 150TM documented the general condition of the tunnel. The ULS-200 underwater laser scanner captured sub-millimetre measurements of areas of interest to understand tunnel deformation and more specifically determine ovality with millimetre precision. The resulting data was conclusive in determining the geometry of the tunnel over its length. The measurements were compared to existing engineering drawings. Changes in the tunnel geometry, cracks and other areas of concerns were understood to the level required to make confident decisions on maintenance priorities.

Currently, when assessing underground water infrastructure a significant level of assumption is required. Underwater laser scanning is replacing assumption with high resolution, quantifiable measurements. This information is equipping project managers with the data needed to understand with greater certainty the condition of their water infrastructure and move projects forward with reduced assumption and thus fewer risks.

3D point cloud of a tunnel section.

The ULS-200 laser scanner is designed for close range scanning. Its small size allowed for easy integration into the crawler. The precise geometry of the tunnel was captured as the head of the laser rotated a full 360 degrees, generating a 3D point cloud CAD model. The resulting data provided an accurate digital record of the 3D geometry of the tunnel from which, ovality was assessed and irregularities identified. The 3D point cloud model generated during underwater laser scanning can be exported into CAD software for engineering analysis.

Not every condition is ideal for laser scanning. If there is an excessive amount of light or turbidity in the water a good scan might not be possible. Silt filtering algorithms are able to deal with a surprising level of turbidity in the water but laser scanning would not be the tool of choice for untreated sewer water. 2G Robotics suggests that if you can see the target surface with video, laser scanning is often a good measuring solution.

Under operational conditions, IPI Group inspected the Bellingham tunnel system from several entry points. The cameras fixed to the Inuktun Versatrax 150TM documented the general condition of the tunnel. The ULS-200 underwater laser scanner captured sub-millimetre measurements of areas of interest to understand tunnel deformation and more specifically determine ovality with millimetre precision. The resulting data was conclusive in determining the geometry of the tunnel over its length. The measurements were compared to existing engineering drawings. Changes in the tunnel geometry, cracks and other areas of concerns were understood to the level required to make confident decisions on maintenance priorities.

Currently, when assessing underground water infrastructure a significant level of assumption is required. Underwater laser scanning is replacing assumption with high resolution, quantifiable measurements. This information is equipping project managers with the data needed to understand with greater certainty the condition of their water infrastructure and move projects forward with reduced assumption and thus fewer risks.

The ULS-200 laser scanner is designed for close range scanning. Its small size allowed for easy integration into the crawler. The precise geometry of the tunnel was captured as the head of the laser rotated a full 360 degrees, generating a 3D point cloud CAD model. The resulting data provided an accurate digital record of the 3D geometry of the tunnel from which, ovality was assessed and irregularities identified. The 3D point cloud model generated during underwater laser scanning can be exported into CAD software for engineering analysis.

Not every condition is ideal for laser scanning. If there is an excessive amount of light or turbidity in the water a good scan might not be possible. Silt filtering algorithms are able to deal with a surprising level of turbidity in the water but laser scanning would not be the tool of choice for untreated sewer water. 2G Robotics suggests that if you can see the target surface with video, laser scanning is often a good measuring solution.

Under operational conditions, IPI Group inspected the Bellingham tunnel system from several entry points. The cameras fixed to the Inuktun Versatrax 150TM documented the general condition of the tunnel. The ULS-200 underwater laser scanner captured sub-millimetre measurements of areas of interest to understand tunnel deformation and more specifically determine ovality with millimetre precision. The resulting data was conclusive in determining the geometry of the tunnel over its length. The measurements were compared to existing engineering drawings. Changes in the tunnel geometry, cracks and other areas of concerns were understood to the level required to make confident decisions on maintenance priorities.

Currently, when assessing underground water infrastructure a significant level of assumption is required. Underwater laser scanning is replacing assumption with high resolution, quantifiable measurements. This information is equipping project managers with the data needed to understand with greater certainty the condition of their water infrastructure and move projects forward with reduced assumption and thus fewer risks.