ASI Group

It’s a Team Effort: Underwater Inspection and Repair

ASI Diver, Kris, entering the water - ASI Group

How an Inspection and Repair of a Steel Pile Wall Utilized ASI’s ROV and Dive Teams

When a pier pile wall located on the Fraser River in the Lower Mainland region of BC required an underwater inspection and repair, a Team of ASI’s ROV technicians were there to collect the data and provide a fully detailed condition assessment for our client.

This underwater inspection used two sonar configurations to locate and identify areas of interest. Areas of interest included any signs of erosion that had occurred since the last inspection of the pier. ASI ROV Technicians used a sonar side scan mounted on a Universal Sonar Mount. They then performed a multibeam survey along the steel pile wall, deploying the systems from a custom-equipped survey vessel.

Side scan sonar often identifies biofouling or biological fouling on wetted surfaces. During this inspection, welds could be seen spiraling the circumference on all piles. Therefore, no biofouling was believed to be present on the piles.  

3D Sonar Image of Pile Wall – Erosion Location
3D Sonar Image of Pile Wall – Erosion Location

The resulting data and report provided the client with a baseline of information for future inspections. But it also showed areas in need of current repair. Images also showed large clusters of debris scattered along the riverbed. These mostly consisted of large wood or trees, as well as rock and gravel in other areas.

Hand-off to the Dive Team

The underwater inspection showed repair work that required underwater welds. ASI’s certified and trained commercial divers stepped in and completed the repairs. Divers, equipped with a surface supplied air system, were tasked with welding filer strips in the gaps between piles and a steel beam. Adding sealing material slows the water ingress through any structural deficiencies or weaknesses.

For this project, ASI assigned a four-person dive crew to perform the repair work. This crew consisted of a diving supervisor, diver, a standby diver and a diver’s tender to facilitate the daily diving routine.

The role of the Diving Supervisor is there to direct and monitor the diver’s progress in real-time. ASI diving personnel are certified with the Diver Certification Board of Canada (DCBC). This is in accordance with the CAN CSA 275.4 Competency Standard for Diving Operations.

The divers also used a support barge as a work platform. This provided additional deck space for the dive crew and plenty of room for their equipment.

Working underwater can provide unique challenges. Diving operations were scheduled during times of high/slack water in consideration of the freshet. This does not always enable accurate tidal and water current predictions. Underwater visibility during the time of the repair was zero to <50 mm (2”).

What this means to our clients

When it comes to underwater inspections and repairs, technology plays an important role in condition assessments. Sonars identify detailed areas of damage, scour, erosion and debris accumulation. They provide a baseline for future inspections. And they provide valuable information by identifying areas that need immediate repairs and attention.

By combining our in-house services, ASI is able to provide our clients with full-service options when assessing and repairing their underwater assets.

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