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3.3 Ecological Guidelines
(cont)
3.3.4
Soil
(a) Siting,
design and construction of any structure should result in minimal disturbance
to soils.
Construction works
involving excavation and cut and fill on slopes can cause considerable
problems with soil erosion in unstable sandy coastal soils.
- Buildings should not be located on steep slopes.
- Structures should be designed to minimise cut and fill. Where possible,
on sloping sites, buildings should utilise footings which allow the
natural slope to be maintained, e.g. pole structures.
- Topsoil should be stockpiled and used on-site.
(b) Permanent
structures should not be located on or adjacent to foredunes, unstable
or mobile soils.
- Where structures are necessary, the following strategies should
be adopted:
> minimise increases in water run-off rate and volume and in particular
avoid the concentration of run-off into one location;
> site structures to minimise wind funnelling and consequent wind
erosion;
> stabilise all ground surfaces which are exposed to erosive forces
during and after construction; > permanently stabilise all slopes
greater than 1:4 with protective coverings, such as mulch under fabric,
or retaining walls. Where slopes are mulched, soil binding ground
cover plants should be established;
> minimise vegetation removal, particularly on slopes and in loose
wind blown soils, e.g. sand dunes.
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3.3.5
Coastal Waters
(a) Siting,
design and construction of any structure should minimise changes to
the natural patterns of movement and supply of marine sediments.
The beaches at
a number of locations along the coast have been depleted by a number
of factors, including coastal recession and as a result of walls, breakwaters
and groynes interrupting the flow of sand to the beach.
Marine structures
such as walls have also accentuated erosive pressures on the coastline
in some locations, resulting in increased erosion and loss of beaches.
- Wherever possible, the natural erosion of coastlines should be allowed
to take place without interference by walls, groynes or similar structures.
Such erosion supplies sediment to form beaches in the area and further
down the coast, where these are maintained by the littoral drift of
sediment. Sediment is also supplied by streams flowing into the bay
and this supply similarly should not be restricted by works and structures
in the streams or catchments.
- Structures in the water may impede the transport of marine sediments
along the shoreline and thus reduce the supply of sand to beaches.
These should be designed to keep to a minimum the effect on littoral
sediment movement, and strategies such as sand pumping should be considered
to overcome unavoidable interference with natural patterns of erosion
and accretion.
- In some instances, it is necessary to control erosion where it threatens
developments, such as buildings or roadways, on the coast. The construction
of protective structures, such as walls, may be necessary in these
instances. The construction of breakwaters for sheltered boat moorings,
piers, jetties and structures associated with navigation is often
necessary, even though those structures may affect natural patterns
of coastal erosion and accretion.
- Where it becomes necessary to control erosion, alternative techniques
such as beach renourishment, should be considered. Where possible,
structures or other development on sites threatened by coastal erosion
should be relocated to obviate the need for protection works.
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3.3.6
Ecological Sustainability and the Recognition of Environmental Processes
All siting and
design should be based on ecologically sustainable principles and recognise
the significance of environmental processes such as the greenhouse effect
and ozone depletion.
- The use of solar and innovative environmentally friendly techniques,
such as composting toilets, roof water, recycled materials, etc.,
should be encouraged.
- Avoid siting and designing structures/facilities that may be subject
to adverse effects from the ocean rising due to the influence of the
Greenhouse Effect.
- The depletion of the ozone layer may cause a re-evaluation of how
people use and interact with the coast. Siting and design of structures
should be mindful to provide maximum solar protection to the coast
user.
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3.3.7
Recognition and Protection of Marine Biological Values
Protection and improvement of marine biological values
is critical in coastal environments, and these should be recognised
in any proposed actions along the coast.
These values can
be conserved and improved in a variety of ways, for example:
- Creation of breakwaters in appropriate locations which can serve
as fish and bird habitat areas.
- Creation of wetland and stormwater systems to enhance vegetation
and, therefore, habitat areas.
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