20th July 2022
Pipeshield, a Tekmar Group Company, has completed the design, manufacture, and supply of a marine scour and quay wall erosion protection solution, which is successfully installed on an LNG terminal in Canada. The project was our largest marine civils work scope to date and our fourth major marine civils project in successive years.
What is scour? Scour is the displacement of sand, silt and soil on the seabed caused by underwater structures interfering with the natural flow of near seabed water velocity. As the water flow accelerates around the installation, it has the potential to erode the seabed at the base of the structure, adversely affecting its strength and stability. Scour is a natural occurrence caused by currents, tides and storms and is intensified by turbulent ship propellers, especially in shallow water environments like ports and harbours.
Based on environmental data, project specifications and customer expectations, our internal design team developed a bespoke scour protection solution to protect the terminal’s quay wall and a specified area of the riverbed from scour and erosion.
In the delivery of the project, over 1,150 Bi-flex concrete mattresses were manufactured using purpose-built modular moulds. The design included our patented N2 Edge block profile, which has long been third-party verified as conservatively three times more stable than standard block mattresses. The mattresses are installed end-to-end from the quay wall out to around 30m into the port, creating a complete system to protect the area from scour damage.
To further complete the scour barrier, all concrete mattresses were pre-fitted with Pipeshield’s GEO-MAT before installation. Fixed to the underside of the concrete mattresses, our GEO-MATS include an overlaying geotextile flap so that, once installed, neighbouring mattresses can be installed on top of the flaps to form a continuous protective barrier providing enhanced stability and protection as they lock in place.
At the toe of the quay wall, where conditions are most volatile, sat a continuous row of over 650 two-tonne Precise Rock Placement Units (PRPs) filled with locally sourced rock. The PRPs act as a filter to slow the turbulent velocities down and provide additional scour prevention at this critical location, thus completing the scour protection solution.
Two bespoke 16m Quick Release frames were designed and fabricated to simultaneously install two mattresses longitudinally. For further adaptability, these highly versatile purpose-built frames were designed to split into two 8m Quick Release frames that can be used independently of each other should it be required, enabling four frames to be in use simultaneously. The frames were fitted with a surface-operated hydraulic release kit (HRK). This allows divers to radio the crane operator when the mattresses are in position, and the frames quick release system can be operated remotely using the HRK. This provides a safer environment for the divers and requires less diver time.
Pipeshield’s ability to mobilise equipment and personnel around the world meant we were able to team up with a local specialist concrete pre-caster and manufacture our products in Canada, near the project, saving a considerable amount in transportation time and cost. All products were manufactured under Pipeshield’s supervision to our expected quality and on schedule over five months.