Background
In February 2017, Canterbury’s Port Hills suffered significant damage when fire destroyed approximately 200ha of land including 11 homes. Over 1500 people were evacuated from their homes for the duration of the fire which burned for five days. A state of emergency was declared by the Government to enable further resources to assist with the blaze.
Problem
As a result of the vegetation loss on the slopes, the fire exposed highly erodible loess soils as well as a significant amount of ash. The sensitive receiving catchment was subjected to a significant risk as well as an increased sediment loading during autumn rain events washing into the Cashmere Stream and subsequently into the Avon/Heathcote Estuary.
Solution
Vital Bon-Matt Stonewall (IGD) was chosen, based on its proven stabilisation properties, for applications to specific areas to provide immediate point source stabilisation of exposed & fire damaged slopes. Vital Bon-Matt Stonewall (IGD) applications were also undertaken to support the establishment of aerial seeding where specialist seed blends were used to promote revegetation by pinning seed to soil.
Benefit
The employment of Vital Bon-Matt Stonewall (IGD) over 8ha immediately and effectively stabilised at risk areas on the Port Hills. Further, the product employment improved sustainable environmental outcomes by minimising erosion and consequently leading to a reduction in loss of soil and loess. This in turn resulted in reducing the sediment load entering sensitive waterways and promoting long-term stabilisation and revegetation.