Environment Canterbury

3634-22/23 Native Enhancement of Southern Canterbury Rivers Scour Bays

This procurement involves the installation of 27,300 native plants into various sites across the Ashburton, Orari and Opihi Rivers in and around gravel flood management structures. Each site was impacted during the floods of 2021, with significant erosion damaging riverbanks, inundating private farmland, and destroying tree belts. Environment Canterbury quickly built immediate flood management structures into the ‘Scour Bays’ carved out by the flood. These structures largely consist of gravel groynes arranged in a herringbone pattern with the goal of deflecting the energy of flood flows back into the river corridor, with the whole bay acting as a somewhat sacrificial scour site, to minimise scour and erosion damage to other assets.
This project is designed to improve the stability of the ‘Scour bay’ sites as well as the aesthetic and natural character of these assets through the addition of eco-sourced native vegetation in and around the existing flood-protection willow poles.
We are inviting a proposal to install native vegetation at 9 sites across the three rivers while minimising environmental disturbance and any impacts on existing flood management infrastructure and willows. The sites are still relatively clear of regrowth with only a handful requiring weed clearance prior to planting. The installation of the native vegetation at the sites will be entirely specified and will require the use of small excavators, augers or similar. It is not considered that any technical native-plant knowledge will be required to perform this work.
It is important to us that we work co-operatively with adjacent landowners. Access to the sites may require crossing private property, and we would require the contractor to seek permission and to adhere to any requests that the landowner makes regarding access through their land. Should adjacent landowners request to be notified when works are taking place in the river, we would also require the contractor to adhere to those requests.
Our target date for completion of this work is 30 November 2023, with all plants to be installed by the end of September.

Department/Business Unit: Field Services