Coffs Harbour Groyne Extension

International Coastal Management

The objectives of the project were two-fold:

Reduce surge within the boat ramp and
Reduce build-up of sediment within the entrance to the harbour

This involved the extension of the existing groyne by ~30m with a crest level at approximately mean sea level. ICM acted as consultants to Coffs Harbour City Council regarding construction design and supervision.

While the existing groyne is rock, the extension was constructed using a combination of sand-filled geotextile mega-containers [25 - 30m long and 4m in diameter] and smaller 5t units used to link it to the existing rock groyne. The Terrafix mega-containers were rolled out empty and filled with sand slurry using an onshore pump while the 5t units were filled on shore and craned into place. Construction was commenced in late 2004. The ‘sand bag’ groyne is popular with locals and is becoming home to a range of fish and marine growths.

Photo courtesy of Coffs Harbour City Council