Blacks Beach Coastal Protection

A high wave environment caused dropouts along the coastal road.  The intent of this project was to repair the dropouts while maintaining the existing road width and protecting the toe of the slope from further damage from coastal erosion.

The work involved designing and constructing a 260m long revetment, including sand-filled geotextile bags and the placement of rock protection, the construction of an MSE wall, upgrading of stormwater culverts and slope planting.

We proposed three different schedules, one for priority work that needed to doing immediately (Stage 1), one for work to be done in the near future to avoid further undermining and erosion of the slope and road (Stage 2), and improvements possible to the uphill area (Stage 3).

The priority work (Stage 1) was the MSE Wall, the area with the “Reinforced Slope below Road with Earth Anchors” and all the culvert improvements, including the bunding and drainage channel to minimise the risk of further storm damage.  The reinforced slope and the culvert sections were to be planted as specified after completion.

Stage 2 works would then consist of the remaining area of the revetment, the planting above it and the remaining slope areas of the anchored reinforcement matting.

Finally, stage 3, the stabilisation of the slope above the road.

We still had to protect the sandbags with a layer of rock at the base as the revetment continued down to the beach, and the area was prone to washed-up large logs during storm events.

LDE resolved a problematic section of the Blacks Beach Road Revetment for the Wairoa District Council with the use of ElcoRock sandbags rather than a traditional rock revetment (the nearest Limestone was in Patutahi, Gisborne, and of course, sand was available as a cheap local resource).