Cox's Creek improvement project
Background |
Options assessment | Proposed
works | Expected benefits
Proposed works
Stream re-grading
To
improve stream flushing and address amenity issues, Cox's Creek will be dredged
using a system that will effectively remove unwanted sediment while minimising
adverse impacts. Details regarding the exact dredging methodology are currently
being developed. Extracting the sediment will enable a more suitable tidal flow.
The dredged material will be transferred to trucks and exported to a licensed
facility.
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| Main scour pool, near Richmond Road. |
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Appropriate sediment and erosion control measures, monitoring, pedestrian and
traffic management will be adopted to ensure that potential adverse impacts are
minimised whilst carrying out the works effectively.
Scour pool re-contouring
To
avoid the entrapment of sediment and stagnation of polluted water at the head of
Cox's Creek, the scour pool near Richmond Road will be re-contoured to promote
stream flushing. This will involve filling the pool, creating a rock channel and
landscaping the area to restore amenity.
Vegetation removal
In
order to undertake the work described above, some vegetation clearance
(including a section of mangroves) will be required for access and to restore
tidal flow. Removal of desirable species will be kept to a minimum. The
opportunity will also be taken to generally "clean up" some of the park by
removing weed species.
Supplementary works
As
there are a number of areas where the stream bank is falling away, we also
propose to regrade the stream banks, remove a small portion of mangroves causing
the problem, and plant the affected stream banks to improve stability.
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| Buid up of sediment in Cox's Creek. |
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Restoration planting
Given
that plants have high aesthetic and ecological value, we propose a restoration
planting programme. Native species that complement the existing mangroves will
be used, especially those that provide habitat and a food source for native
birds.
The
planting will incorporate a request by Ngati Whatua to include native flax
species, as the north-facing slopes overlooking Cox's Creek are customarily
known as "Tukituki Muka" - a name given to a treatment for rendering flax fibre
for fine garments, lashings and specialist necessities.
Proposed maintenance
To avoid this problem recurring, minor stream maintenance
will probably be needed approximately every five years. However, additional
influencing factors may increase the frequency of maintenance required,
depending on the rate of sediment build-up. The initial dredging operation has
been designed so that the impact of future maintenance works is minimised.
