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The Problem

After Cyclone Gabrielle, State Highway 5 experienced extensive slips, presenting a severe hazard to commuters and jeopardizing the structural integrity of the highway. The slips, spread over seven days of cyclonic activity, created an urgent need for stabilization and erosion control to mitigate further damage and ensure the safety of both drivers and critical infrastructure.


The affected area covered crucial sections along State Highway 5, a major transportation artery in New Zealand. The weeklong cyclone had triggered multiple slips, demanding a comprehensive and expedited solution to address the extensive erosion and instability issues. Given the vital role of this highway in local and interstate travel, the project's scope extended to cover all slips caused by Cyclone Gabrielle, requiring a thorough and efficient response to minimize disruptions.

Our Solution

Hydro Mulch

  • With New Zealand wooden fibre and Site Loc Polymer. Application rate 2,500kg/ha. To provide stabilisation while the grass germinated and vegetation succession underway.

Seed blend used was our Erosion Control seed blend. Deep rooted species that thrive in poor quality soils. 12 months after application some species can have a root structure up to 30cm deep!


The tight timeframe required meticulous planning, coordination, and execution to ensure minimal disruption to traffic flow. Nighttime work, specialized equipment, and lighting arrangements were essential for efficient implementation. The unpredictable weather conditions, including the potential for rain, added complexity and risk to the project's success


Despite challenges, the hydromulching on State Highway 5 was completed in three nights, preventing slips, ensuring commuter safety, and preserving highway integrity. The application fostered vegetation growth for long-term stability, minimizing disruptions to one of New Zealand's busiest state highways. This underscores hydromulching's effectiveness in emergency erosion control after prolonged weather events.

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