Coastal Pathway Reinforcement – Christchurch

Coastal Pathway is a joint project between Christchurch City Council and Christchurch Coastal Pathway Group. It will run from Ferrymead Bridge to Scarborough Beach when completed – a total of 6.5km, with a 4m wide shared pathway.

Design

A heavyweight geotextile was required to protect the seawall and backfill from erosion caused by the tidal waves. DuraForce 1200c and TerraTex 900H were selected for this project. Due to a lot of heavy wash from the waves and the placement of very large rock it is critical to overlap the geotextile so it does not separate and allow for the fines to wash out of the gaps.

Installation

The project was carried out by Fulton Hogan, with all the bulk earthwork and placement of rocks completed by Protranz. The excavation of the rock revetment area goes underneath by 2m, and then up the bank.

The DuraForce heavyweight geotextile used provided the following benefits to the project:

• Prevents erosion behind riprap
• Protects and preserves shoreline from wind, wave and tidal action