Situated on the East Coast of the Scottish Highlands, at the town of Invergordon, the port of Cromarty Firth provides a natural deepwater harbour. Owned and operated by the Cromarty Firth Port Authority, the Invergordon Service Base offers port engineering facilities which play an important role in the North Sea oil and gas sector, and within Scotland’s offshore renewable energy market. To better service its growing customer base, Invergordon Service Base is undergoing a £25million redevelopment programme which will increase the capacity of both berthing and laydown areas.
NAUE Terrafix geotextile wrapping has provided erosion resistance and scour protection in the construction of a new deepwater berth as part of the redevelopment of Invergordon Port.
Construction of the project includes: reclaiming 3.48ha of land from the sea; a new heavy lift capacity quayside; increased water depth at the quayside; and associated utilities. Reclaiming such a sizeable area of land required the dredging of around 21,000m3 of silt from the seabed and the construction of a rip-rap aggregate bund to enclose the sections to be reclaimed. Forming a spur which extends out into the Cromerty Firth, the aggregate bund will be protected from the power of the sea by a rock armour system. Prior to placement of the heavy rock armour, NAUE geotextile sand mats were installed along the embankments of the spur, and underwater onto the seabed, to provide erosion resistance and scour protection to the structure. Naue’s Terrafix® B813 sand mats, specially developed for such hydraulic engineering applications, were specified for the project. Terrafix® B813 sand mats have an integral sand ballast layer encapsulated between multi-layered, needle-punched filter geotextiles, and their proven robustness and filtration characteristics prevent fines washing into and out of coastal structures. The 4.8m wide sand mat rolls were installed by simply unrolling using a spreader bar and an excavator and, because the sand ballast causes the geotextile to sink rapidly in water, underwater installation was quick and easy without the need for specialist divers. Also, the durability of Terrafix® meant that the geotextile could be covered directly with armour stone. Working closely with main contractor McLaughlin & Harvey, NAUE’s design consultants provided design support for the project and a total 10,000m3 of Terrafix® B813 was successfully installed. Using Terrafix enabled the cost efficient completion of a key element in the line-up of works at the port, which is scheduled to take 18 months to complete.