District Plan Hauraki Gulf Islands Section - Proposed 2006
(Notified version 2006)
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Part 8 Natural hazards
Part 8 -Natural hazards
8.1 Introduction
8.2 Resource management issue
8.3 Objectives and policies
8.4 Resource management strategy
8.5 Rules - restricted discretionary activities
8.6 Rules - discretionary activities
8.7 Relationship with rules in other parts of the Plan
8.1 Introduction
The council's functions as outlined in section 31 of
the RMA include the control of any actual or potential effects of the
use, development, or protection of land, including for the purpose of
the avoidance or mitigation of natural hazards. Section 7 also requires
the council to have regard to the effects of climate change.
Natural hazards are any atmospheric or earth or water
related occurrence (including earthquake, tsunami, erosion, volcanic
and geothermal activity, landslip, subsidence, sedimentation, wind,
drought, fire or flooding) the action of which adversely affects or
may adversely affect human life, property or other aspects of the environment.
8.2 Resource management
issue
The significant resource management issue which needs
to be addressed in the Plan is:
- How to manage irregular or periodic exposure
to naturally occurring events such as earthquakes, fires, drought, landslides,
cyclones, floods, erosion, slope instability and subsidence, sea storm
surge, tsunami, and volcanic and geothermic activity.
Explanation
The frequency and magnitude of these events will vary
and their effects on the environment, including people, property and
infrastructure will vary as a result. Many natural hazards are not well
understood, in terms of their possible location, frequency, magnitude
and consequences.
8.3 Objectives
and policies
8.3.1 Objective
To avoid the adverse effects of natural hazards on the
environment, including life, property and infrastructure as far as is
practicable.
Policies
- By adopting a precautionary approach
when there is a lack of information about natural hazards with a high
return period (such as a 1 in 10 year or 1 in 50 year flood).
- By preventing new development and
activities in high risk areas where the effects of the natural hazard
cannot be adequately avoided or mitigated.
- By taking into account the potential
effects of tsunamis, coastal erosion and deposition processes and the
possibility of sea level rise when planning for development near the
coast.
Explanation
As well as the requirements of section 31 of the RMA,
the Building Act 2004 also requires territorial authorities to place
limitations and restrictions on buildings in natural hazard areas. Section
71 of the Building Act 2004 requires a building consent authority (such
as the council) to refuse to grant a building consent for construction
of a building, or for major alterations to a building:
- if the land on which the building work
is to be carried out is subject to or likely to be subject to one or
more natural hazards; or
- if the building work is likely to accelerate,
worsen or result in a natural hazard on that land or on any other property.
Section 71 of that Act goes on to provide for the granting
of consent in certain circumstances.
The Building Act 2004 also requires building consent
authorities to issue a building consent if the building work will not
accelerate, worsen, or result in a natural hazard on land subject to
hazards and it is reasonable to grant a waiver or modification of the
building code in respect of the natural hazard concerned.
8.3.2 Objective
To avoid the creation or exacerbation of the risks of
natural hazards by human activities as far as is practicable
Policies
- By controlling earthworks, and vegetation
clearance (including riparian vegetation clearance), to avoid or mitigate
the effect of activities which may exacerbate the risk of natural hazards.
- By protecting hazard prone areas
from activities which will accelerate erosion, inundation, and other
natural hazards.
- By limiting the extent of impervious
surfaces to decrease the peaks in stormwater flow occurring during high
rainfall.
- By requiring development and activities
to adapt to, or retreat from, areas likely to be severely affected by
natural hazards.
Explanation
Activities such as earthworks and vegetation clearance
(including riparian vegetation clearance) can decrease the stability
of land, making it more prone to erosion and slippage. The extent of
this will depend on such factors as the slope of the land, the extent
of the area modified, the soil type and rainfall.
8.3.3 Objective
To protect existing physical resources and natural defences
which moderate the effects of natural hazards.
Explanation
Natural defences include vegetation cover, sand dunes,
mangroves, coastal cliffs and other naturally occurring physical resources
that can lessen the impacts of flooding, soil instability, storm surge,
tsunami, earthquakes and other natural hazards.
Policies
- By protecting natural defences (eg dunes)
which provide protection from natural hazard events.
- By avoiding the use of hard engineering
structures (such as sea walls and groynes) as far as is practicable,
especially those within the coastal environment (above mean high water
springs) which adversely affect public access to coastal areas or landscape
values.
Explanation
Coastal erosion is a natural process on almost all coastlines.
It only becomes a hazard when it poses a real or perceived threat to
things that humans value. Sea walls, groynes and other methods of shoreline
armouring may protect private property but may cause the loss of the
dry sand beach area available to the public or have adverse effects
on the local environment. They also adversely affect the natural appearance
of coastal areas and replace natural processes that may protect the
coast from coastal erosion. The presence of armouring structures may
also encourage inappropriate intensification or development in coastal
hazard areas and place greater liability on the council and the Auckland
Regional Council should these structures fail. Failure of sea walls
and groynes may lead to further inappropriate modification of the coastal
environment. Sea walls in one area may affect the accretion or movement
of sand in other areas. Seawalls enable beachfront interests to enjoy
the benefit of a near-shore location while externalising the costs onto
a wider community.
Soft solutions in the coastal environment such as the
protection of dunes, beach nourishment and planting may be more effective
in mitigating the effects of coastal hazards.
8.4 Resource management
strategy
The resource management strategy is to implement rules
to avoid or mitigate natural hazards. The frequency and magnitude of
these natural hazard events will vary and their effects on the environment,
including people, property and infrastructure will vary as a result.
The rules concentrate on avoiding or mitigating those natural hazards
with a higher probability of occurring in shorter time frames (eg in
the next 100 years), including flooding and erosion, coastal erosion,
and land slippage. Provisions within the Building Code provide protection
for buildings from other natural hazards such as high winds, earthquakes
and land settlement. The development and subdivision of land subject
to a natural hazard will be subject to appropriate limitations. The
planning maps contain information on known natural hazard areas, but
in the absence of information on the maps, the Plan sets limitations
on activities in areas that have a high probability of being affected
by natural hazards.
8.5 Rules - restricted
discretionary activities
8.5.1 Activities
The following are restricted discretionary activities:
- The removal of any vegetation (except
for any species listed in appendix 14 - List of plant pest species)
on any piece of land where the slope is steeper than 1 in 3 (18o).
- The removal of any vegetation (except
for any species listed in appendix 14 - List of plant pest species)
within 5m of the centreline of any stream or river or the edge of any
lake or wetland.
- The removal of any indigenous vegetation
greater than 2m in height within 10m of the centreline of any stream
or river or the edge of any wetland.
8.5.2 Notification
requirements
Except as provided for by section 94C(2) of the RMA,
applications for a resource consent for the above activities will be
considered without public notification or the need to obtain the written
approval of or serve notice on affected persons (in accordance with
section 94D(2) and (3) of the RMA).
8.5.3 Matters
of discretion
The council has restricted its discretion to considering
the following matters:
- The extent of vegetation removal.
- The replacement of any vegetation
removed.
- Methods to avoid or mitigate erosion
or slippage of the land as the result of the removal of vegetation.
8.6 Rules - discretionary
activities
8.6.1 Activities
The activities listed below are discretionary activities.
- Any of the following:
- The location of any land use development
activity, building, permanent structure, fence or wall.
- Exterior additions or alterations
to, or change of use of, any building or structure.
- The placement of any septic tank,
wastewater treatment and disposal system, effluent disposal field, underground
storage tank, water tank or stormwater pipe or soakage field.
- Any earthworks.
- The storage of any hazardous substance
in volumes that exceed the permitted activity rules in part 9 - Hazardous
facilities and contaminated land.
- When located as follows:
- In any natural hazard area identified
on the planning maps; or
- In any of the following locations,
subject to any more accurate natural hazard information identified in
the planning maps to the contrary:
- at an elevation less than 1m above the
edge of any adjacent permanent stream, river, wetland or lake
- within a horizontal distance of 20m from
the top of any coastal cliff with a slope angle steeper than 1 in 3
(18o)
- on any slope with an angle greater than
or equal to 1 in 2 (26o)
- at an elevation less than 3m above mean
high water springs if the activity is within 20m of mean high water
springs
- at an elevation less than 2m above mean
high water springs if the activity is located more than 20m from mean
high water springs.
Exception
Provided that (a) to (e) above do not apply to
any land located within (i) or (ii) where a report from an appropriately
qualified engineer establishes that the land is not subject to, and
will not be subject after any proposed activity, building or other structure
is completed, to any of the following:
- flooding, in a 1 in 100 year storm
- coastal erosion over a 50 year time frame
- instability or erosion.
- The placement of any material, objects
or structures, in or on any beach above mean high water springs in a
manner that may serve as a defence against coastal erosion.
- The modification, alteration or
removal of sand dunes and vegetation (except for any species listed
in appendix 14 - List of plant pest species) on sand dunes within 40m
of mean high water springs.
8.6.2 Explanation
Natural hazard areas as identified on the planning maps
include flood prone areas, areas identified as filled, unstable or weak
ground, including areas of suspected slope instability or where soils
reports are held; refuse tip sites with weak ground, and coastal erosion
risk areas. It does not include any wind zone identified for the purposes
of the Building Act 2004.
Flood prone areas include type A flood plains, type
B flood risk areas and secondary or overland flow paths taken by stormwater
on its way to a flood plain in a storm that is more severe than a 1
in 10 year storm. Type A flood plains shown on the council's planning
maps and geographic information system ('GIS') are considered by the
council to be a reasonably accurate assessment of flooding in a 1 in
100 year storm. Type B flood risk areas shown on the planning maps or
GIS are not as accurate as type A areas and may be based on incomplete
information.
8.6.3 Additional
requirements
There may be instances where the requirements of section
71 of the Building Act 2004 will prevent a building consent being issued,
even though the activity is authorised under the RMA by virtue of the
above rules, if the council believes the land on which the building
work is to be carried out is subject to or likely to be subject to one
or more natural hazards. The council is likely to refer to any information
it has, including information stored on its GIS when making this determination.
The placement of any structure in, on, under or over
the bed of a lake or any river or stream or below mean high water springs
is controlled by the Auckland Regional Council.
8.6.4 Assessment
criteria for discretionary activities
The council's assessment of an application for a discretionary
activity will include consideration of the following matters:
- The likelihood of a natural hazard event
occurring, and the likely extent of damage occurring as the result of
that event. In considering this, regard will be had to the extent to
which site specific analysis of the hazard (such as engineering stability
or flooding reports) and its effects have been undertaken and any other
information the council may have on the site and surrounding land.
- The extent to which the proposal
affects the potential impacts of the natural hazard present, or has
the potential to create a new natural hazard on the subject land and
any adjacent land. In considering this, regard will be had as to whether
the proposal is likely to:
- avoid, remedy or mitigate the potential
impacts of the natural hazard; or
- accelerate or exacerbate the probability
of a natural hazard occurring and/or the potential impacts of the natural
hazard.
- The extent to which the proposal
ensures that any storage tanks (above ground or underground) installed
in hazard prone areas are protected from damage, flooding, spilling,
dislocation and leakage in the event of a natural hazard event.
- The extent to which the proposal
ensures the replacement of any vegetation which is removed or damaged.
- The extent to which the proposal
ensures that hazardous substances stored in hazard prone areas are protected
from flooding, spillage and leakage in the event of a natural hazard
event.
- The extent to which the proposal
includes non-structural solutions such as planting to avoid, remedy
or mitigate the hazard rather than hard engineering solutions.
- The extent to which landscape values,
and public access are affected by any structure used to avoid, remedy
or mitigate any natural hazard.
- The extent to which any existing
natural features (eg sand dunes in coastal hazard areas) will provide
protection from the natural hazard present.
- The extent to which any building,
structure or activity listed in clause 8.6.1 located in a natural hazard
area near the coast, can be relocated in the event of severe coastal
erosion and shoreline retreat.
- The extent to which any proposed
coastal protection works located outside of the coastal marine area
will be located and designed so as to avoid adverse environmental effects
including:
- long term visual effects on the coastal
landscape and amenity values
- any likely increase in the coastal hazard
posed to the coastline in question, including increased rates of erosion,
accretion, subsidence or slippage
- undermining of the foundations at the
base of the structure
- erosion in front of, behind or around
the ends of the structure
- settlement or loss of foundation material
- movement or dislodgement of individual
structural elements
- off shore or long shore loss of sediment
from the immediate vicinity.
8.7 Relationship
with rules in other parts of the Plan
Refer to part 12 - Subdivision for the rules for subdividing
in natural hazard areas.
Part 14 - Definitions must be referred to as it is likely
to contain definitions of terms used in this part of the Plan.
