Lady Carrington Drive rehabilitation

Key achievements

• Successful rehabilitation of an environmentally sensitive heritage site.
• Stabilised the bank to prevent further erosion.
• Reinforced river bank to prevent further sediment entering the river system.
• Client is very happy with the outcome and publicly endorsed Soil Conservation Service for the project.

The challenge

Lady Carrington Drive was constructed in the 1880’s as a scenic carriageway for the then newly opened Royal National Park, and follows the upper reach of the Hacking River for most of the 9.5km trail.

Today it is still heavily used as a scenic walk for thousands of visitors to the park each year.

The trail is also categorised as a Category 7 Fire Trail.

During the 2016 east coast low, one of the heritage culverts approximately 5.5km south of the Audley Precinct blocked up. Heavy rainfall caused a mass landslip into the Hacking River, taking most of the culvert, the trail surface in two sections and several large trees and vegetation.

Work undertaken

• Drainage lines along the road were initially cleared of organic matter. The debris was stockpiled for later use in the regeneration process as it was rich in seedbank and nutrients.
• The trees and vegetation that ended up in the river during the landslide formed a natural log crypt wall which would serve as protection to the river bank.
• Behind this natural structure, a sandstone log wall was constructed.
• A scree slope was keyed in behind the sandstone log wall to armour the slope, protecting it from erosion. This was then covered with organic matter and stabilised with jute mesh.
• Coir logs were used for erosion control.
• A larger sandstone log wall was constructed below the landslip site and above the scree slope to reinforce the material and new road surface at the landslip site.
• Finally the culvert was cleared out and redirected through the wall, into a rock-lined drain which led to the river.

Benefits of this work

The project was successful in many aspects. The trail was made trafficable again for park visitors and for National Parks and Wildlife Service vehicles including Category 7 fire tankers. Stabilisation and integrity of the slope has remained.

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