10 Planning for Fault Rupture Hazard
10.1 The Resource Management Act and the Building Act
Councils need to take a strategic and prepared response to fault rupture hazard in regional policy statements and district plans. A combination of controls through the Resource Management Act (RMA) and the Building Act can avoid or mitigate the effects of fault rupture hazard.
The Resource Management Act 1991 covers land use issues such as the location of a building and the effects of its intended use (amongst others), while the Building Act contains provisions that set legal requirements for a building's construction and the safety and integrity of the structure.
Under the Building Act, all building work must comply with the mandatory Building Code 1992. The Building Code sets out a series of minimum performance criteria for buildings. The council must be satisfied that the criteria of Clause B1 of the Building Code will be met before it issues a building consent. However:
- no guidance is available to councils to help them decide whether a design will comply with Clause B1
- no existing technology will prevent damage to buildings sited across a fault, meaning significant damage can occur even if the Building Code is complied with.
Therefore, relying solely on the Building Act to address the adverse effects of fault rupture is not effective. Councils need to consider and develop a proactive policy response in their district plans, with the Building Act being one of the methods that can avoid or mitigate the risk.
Using controls under the Resource Management Act 1991 and Building Act are just part of a council's response to managing hazards. Protecting essential infrastructure and undertaking civil defence emergency management planning are also required under other Acts, such as the Civil Defence Emergency Management Act 2002.
10.2 Responsibilities under the Resource Management Act
Under the Resource Management Act 1991, both regional councils and territorial authorities have responsibilities for natural hazards. Sections 30 and 31 reflect the fact that some natural hazards are best managed at a regional council level, and others at a territorial authority level.
Section 30 of the Resource Management Act 1991 lists the functions of regional councils. They include "the control of the use of land for the purpose of... the avoidance or mitigation of natural hazards". Within the broad scope of their functions regional councils are required to:
- prepare a regional policy statement, which helps to set the direction for the management of all resources across the region
- produce regional plans where appropriate
- co-ordinate investigations into natural hazards, and maintain information about hazards of regional significance
- integrate the approaches to manage the risk posed by fault rupture, and work with the territorial authorities as to who will do what.
Section 31 of the Resource Management Act 1991 says that territorial authorities are responsible for, among other things, "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 ...".
Within the broader scope of their functions territorial authorities are required to:
- prepare a district plan, the primary document for setting out district wide policies and managing the effect of land use, including through the control of subdivision
- gather information on hazards associated with land use.
Generally, provisions in the regional policy statement should set out what approach the district plan will take. The district plan should contain the specific policies to address hazard risk, and any controls concerning land use and fault rupture.
10.3 Agreement among councils
Regional councils and territorial authorities must agree on their respective responsibilities for managing hazards under the Resource Management Act 1991. It is not effective for councils in the same region and subject to the same hazards to work independently.
The way that councils work together to reach agreement will depend on the issues and resources within each district in a region. Councils can reach agreement:
- during the regional policy statement development process
- by consulting during plan or policy statement preparation
- through a Memorandum of Understanding (MOU).
The issues that need to be agreed on include:
- who will be the key information provider (and what this information is)
- who will identify and map hazards
- who will carry out education and communication campaigns
- who will be responsible for planning and responding to hazards (under the Resource Management Act 1991 as well as a Civil Defence response)
- who will develop and implement specific hazard mitigation plans for particular hazards
- who will be responsible for writing objectives, policies, and rules in plans.
Section 62(1)(i)(i) of the Resource Management Act 1991 says that a regional policy statement must state "the local authority responsible in the whole or any part of the region for specifying the objectives, policies, and methods for the control of the use of land to avoid or mitigate natural hazards or any group of hazards". If the regional policy statement does not clarify these responsibilities, then they default to the regional council.
However, territorial authorities issue building consents, and control the subdivision of land and most land uses. District plans are usually the best place to control land use to avoid or mitigate fault rupture hazard.
10.4 Role of the regional policy statement
One of the matters which need to be contained in a regional policy statement is to identify the regional council's and territorial authority's agreed responsibilities for planning for fault hazards.
The regional policy statement should therefore:
- state clearly which council (regional or district) has the primary responsibility for dealing with fault rupture
- be quite specific as to what each will do.
For example: the regional council will co-ordinate hazard investigation, and the district councils will develop objectives, policies and methods to control use of land to avoid or mitigate fault rupture hazard.
In one of its objectives Environment Waikato recognises the need for the regional and district councils to agree on their roles:
- "The roles of all relevant agencies for the management of natural hazards in the Waikato Region clearly identified and their responsibilities consistently implemented" (Waikato Regional Policy Statement)
The Greater Wellington Regional Council (GWRC) spells out the division of responsibilities in a table contained in its Regional Policy Statement. In it, the GWRC:
- takes responsibility for developing objectives, policies and rules for the coastal marine area
- takes responsibility for developing objectives, policies and rules for the beds of river and lakes
- takes primary responsibility for the development of objectives for other land with secondary responsibility allocated to territorial authorities in the region
- takes shared responsibility (with territorial authorities) for the development of policies for other land in its region
- takes secondary responsibility for the development of rules for other land in its region (territorial authorities have primary responsibility).
10.5 Provisions in a regional policy statement
A regional policy statement also:
- provides an overview of the resource management issues facing the region
- sets region-wide objectives and policies
- identifies the methods to be used across the region to address the objectives and implement the policies.
Regional policy statement provisions tend to be reasonably generic (for example, by considering all natural hazards within the same objective or policy). However, a regional council can be more specific if it wishes, and can set a clear policy direction for the districts to follow. The regional policy statement can identify fault rupture hazard as an issue across the region, and then state the objectives and policies that explain how the issue will be addressed.
Regional policy statements also tend to have similar objectives. The objective is usually to avoid or mitigate the adverse effects of natural hazards on life, property and the environment.
For example:
- "To avoid or mitigate the adverse effects of natural hazards upon human life, infrastructure and property, and the natural environment" (horizons.mw Regional Policy Statement)
- "Any adverse effects of natural hazards on the environment of the Wellington Region are reduced to an acceptable level" (Wellington Regional Policy Statement)
- "To avoid or mitigate natural hazards within the Taranaki region by minimising the net costs or risks of natural hazards to people, property and the environment of the region" (Taranaki Regional Policy Statement)
Environment Waikato also seeks to increase public resilience to natural hazards:
- "The adverse effects associated with natural hazards minimised, the resilience of the community and public awareness of the causes and potential effects of natural hazards events increased"
Policies in regional policy statements vary, but can be grouped into the following categories:
- raising awareness
- improving knowledge
- imposing planning controls, especially with respect to high risk areas
- preparing for hazard events and Civil Defence response.
10.6 Role of the district plan
The district plan should contain the specific policies to address fault rupture hazard risk, and any controls concerning land use and fault rupture.
Section 75(2)(b) of the Resource Management Act 1991 states that a district plan must "not be inconsistent" with the regional policy statement.
Before developing and adopting objectives, policies, and methods for the district plan, councils need to:
- gather information about fault rupture hazards
- assess the risk of fault rupture hazard
- identify and assess earthquake and fault rupture issues.
Plan provisions need to be appropriate to the community's circumstances. No one policy response to fault rupture hazard will work for all communities within New Zealand. The issues and objectives between districts affected by active faults may be similar, but the methods (or mix of methods) used to address the risk will often be different.
10.7 Gathering information
The first step is to determine whether there are any active faults in the district.
Information can be gathered from:
- the regional council, especially hazard information and hazard maps (the territorial authority might create more detailed maps after assessing the active faults in the district)
- geotechnical information provided as part of resource consent applications
- data gathered from site-specific investigations
- Crown Research Institutes, such as the Institute of Geological and Nuclear Sciences
- private companies involved in the geology, earthquake engineering, and geotechnical professions.
The data may be very general in nature, incomplete, or contain conflicting conclusions. Initial information gathering may show the need for further studies. Data also needs to be kept up to date - section 35(5)(j) of the Resource Management Act 1991 requires councils to keep records of natural hazards that are sufficient for the local authority to discharge its functions effectively.
The cost of obtaining fault data can be expensive and prohibitive for smaller councils. Cost sharing between neighbouring councils and agreements with the regional council may help.
The most hazardous faults in the district need to be accurately located, surveyed and mapped in enough detail to provide accuracy at property boundary level (a scale of 1: 5000 to 1: 10,000). This enables the development of appropriate objectives, policies, and methods.
It is not feasible to map all faults in the district, and not always possible to know where they are. Highest priority needs to be given to faults with recurrence intervals of less than 5000 years, and faults closest to urban areas or set aside for future urban development.
10.8 Assessing the risk
Having identified active faults in its district, the council needs to define a fault avoidance zone around each active fault in the district planning maps. It then needs to assess the fault hazard risk within each fault avoidance zone.
The main elements that determine the risk of fault hazard are the fault recurrence interval and the fault complexity.
The likely displacement along active faults is also important. Vertical and horizontal displacement along the fault plane will result in more damage during a fault rupture.
In assessing the fault hazard risk, the council should also take account of:
- community values and expectations (what the community wants and what it does not want)
- which areas of the district are, or are likely to be, under pressure for development
- what infrastructure already exists near faults (buildings, network utilities etc) and the value of that infrastructure
- what level of risk the community is prepared to accept or not accept (in practice, it is easier to define what the community will not accept).
Risk assessment requires an understanding of the likely magnitude or consequences of events, and the risks of injury or loss of life and damage to property and investment. It also requires consideration of the cost of clean-up or repair or replacement of damaged property or services after the event.
10.9 Identifying the issues
Gathering information and assessing the risk will determine whether the risk is a significant issue that the community wants addressed. If so, the issue needs to be included in the district plan, and a policy response developed (objectives, policies, and methods, including rules, to address the issue) to help to avoid or mitigate the fault hazard risk.
10.10 Developing objectives and policies
Many district councils take an 'all-hazards' approach to developing hazard-related objectives and policies in their plans. This provides simplicity and may be acceptable for an overall hazard objective and some policies. However, a hazard-specific approach is likely to be more effective and easier to implement.
When formulating policies, it is important to focus on the effects that need to be addressed to achieve the objective, and to state how those effects are going to be dealt with.
As in regional policy statements, objectives in district plans tend to relate to the territorial authority's statutory function for natural hazards prescribed in section 31 of the Resource Management Act 1991 - to avoid or mitigate adverse effects of the use of land for the purpose of avoiding or mitigating natural hazards.
For example:
- "The avoidance, remedying or mitigation of the adverse effects of natural hazards on the environment" (Objective 14.3.1 of the Upper Hutt District Plan);
- "To avoid or reduce the risk to people and their property from natural hazards associated with seismic action, landslides, flooding and coastal hazards" (Objective in Section 14H 1.1.1 of the Hutt City Proposed District Plan); and
- "To avoid or mitigate the adverse effects of natural and technological hazards on people, property and the environment" (Objective 4.2.7 of the Wellington City District Plan).
The Tasman District Council takes a different approach. Its objective (subject to appeal) is:
- "Management of areas subject to natural hazard, particularly flooding, instability, coastal and river erosion, inundation and earthquake hazard to ensure that development is avoided or mitigated, depending on risk" (Objective 13.1.0 of the Tasman Proposed Resource Management Plan).
A less common objective seeks to ensure that land use activities do not increase or worsen the effects of the natural hazard:
- "Activities and development do not create, accelerate, displace, or increase the effects of a natural hazard" (Objective 31.2.2 of the Proposed Taupo District Plan)
- "Safe land use practices which do not increase the risk of adverse effects from natural hazards on the environment, people and their property" (Objective 11.2.3 of the South Waikato District Plan).
The use of a specific earthquake objective is rare. Examples include:
- "To minimise the risk from earthquakes to the wellbeing and safety of the community" (Objective C12.1 of the Porirua City District Plan)
- "To minimise the risks of earthquakes affecting people and property in the District as far as practicable" (Objective 5 in Section 3.2 of the Matamata Piako Proposed District Plan).
In low-risk areas, the objective may instead seek to improve knowledge of potential risk:
- "Increase Council and community understanding of the earthquake risk and associated natural hazard" (Objective 8.3.1 of the Waimakariri Proposed District Plan).
Policies in district plans generally fall into the same groupings as in regional policy statements, but are at a more detailed level. Essentially, policies can specify:
- collection of information, development of a hazards register or database, and identification of at-risk areas
- provision of information and advice, to raise public awareness and to encourage good practices
- inclusion of controls in plans, so that activities are located and designed to avoid or mitigate adverse effects in at-risk areas
- required standards for emergency responses and essential services following an earthquake event.
For example:
- "To develop a database on natural hazards including implementing a hazards identification system for risk assessment" (Policy 15.2 of the Masterton District Plan)
- "Promote community awareness of natural hazards to encourage avoidance of adverse effects of hazards" (Policy 5 in Section C.15.1 of the Kapiti Coast District Plan)
- "In areas of known susceptibility to natural hazards, activities and buildings are to be designed and located to avoid, remedy, or mitigate, where practicable, adverse effects of natural hazards on people, property and the environment" (Policy 14.4.2 of the Upper Hutt District Plan)
- "To provide warnings and emergency response systems for areas at risk from or affected by natural hazards" (Policy 13.1.6 of the Tasman Resource Management Plan).
Hutt City has a policy specific to fault rupture in its plan:
- "That the area at risk from fault rupture causing permanent ground deformation along the Wellington Fault be managed by the Wellington Fault Special Study Area to address the effects of subdivision and development on the safety of people and their property".
South Waikato acknowledges the importance of working with the regional council on hazard issues in its district plan policies:
- "To work with Environment Waikato to develop measures to ensure that land use practices do not cause or promote natural hazards" (Policy 11.3.6 of the South Waikato District Plan).
10.11 Developing methods
Although it is not practical or possible to eliminate fault rupture hazard risk completely, doing nothing is not an option. Methods should be developed specifically to address the effects of fault rupture.
The plan needs to contain methods that address different aspects of the risk: what is the likelihood of the hazard occurring? What are the consequences? Does the risk need treating?
District plan rules are not necessarily the only option - a mixture of rules and other methods can be adopted. The exact makeup will vary, depending on the level of risk and the outcome of the section 32 analysis (see below).
Methods can become more permissive as the risk of fault rupture decreases, for example by:
- allowing a greater range of buildings to be located in an area of fault rupture
- allocating a less restrictive consent activity category
- relying more on the Building Act for controls
- relying more on non-regulatory approaches such as education and advocacy.
10.12 Non-regulatory methods
Non-regulatory methods are good for encouraging people to avoid putting themselves at risk. One of the more important things a council can do is communicate the risk to the community.
Some of the non-regulatory methods available to councils include:
- purchasing at-risk land for passive recreational purposes
- exchanging at-risk land with land that can be put to some other purpose
- allowing greater development rights if land is retired or covenanted
- taking at-risk land as a condition of subdivision consent (reserves contribution)
- using financial incentives (for example, rates relief on at-risk land if it is not built upon)
- promoting and helping fund the use of covenants (privately or through the QEII National Trust) for the voluntary protection from development of open space on private land
- educating to raise awareness of the risk and to encourage people to locate buildings away from the fault rupture hazard
- using the Building Act to ensure that structures are safe and will remain intact throughout the life of the building
- including fault hazard information in Land Information Memoranda (LIM) and Project Information Memoranda (PIM) reports.
Fault avoidance zones still need to be clearly identified on district plan maps if non-regulatory methods are used. This ensures that risk is communicated, and that landowners and building occupiers can be made aware of the hazard.
10.13 Regulatory methods (rules)
Building within a fault avoidance zone should be discouraged wherever possible. Even when a fault has a long recurrence interval, the chance exists that the fault may move during the lifetime of a building.
Rules in the district plan can allow development in a fault avoidance zone only if resource consent is granted. This approach is suitable for well-defined faults, or distributed faults that have been accurately located. Section 11 describes how the fault recurrence interval, fault complexity, and Building Importance Category can be used to establish resource consent categories.
Rules need to be based upon risk. The approach used in built-up areas should differ from the approach used in a greenfields area. In greenfields areas it is much easier to require a subdivision to be planned around the likely fault rupture zone and buffer zone (ie, the fault avoidance zone). In built-up areas, buildings may have been established without the knowledge of the risk posed by fault rupture. The community may have an expectation to continue living there and be prepared to live with the risk despite the potential for damage.
Existing use rights under the Resource Management Act 1991 also mean that when an existing building over a fault is damaged or burnt down, or requires rebuilding for whatever reason, it can be rebuilt, even once the risk has been realised.
The district plan may have to include provisions to ensure that the risk is not increased by intensified land use (such as urban infill) or by new building on sites not already occupied. It can also require geotechnical investigations and appropriate earthquake-resistant design where appropriate.
Some councils have taken a precautionary approach to fault rupture.
For example:
- "To take a precautionary approach to development in suspected risk areas until further information on the extent and nature of earthquake risk becomes available" (Policy P1 in Section 3.2.2.5 of the Matamata Piako Proposed District Plan).
The council can also require a report, including certification from an appropriately qualified person, stating that the land is suitable for the activities anticipated.
Nelson City Council has the following rule:
- "Construction or alteration of a building within the Fault Hazard Overlay is permitted if:
a) in the case of any site where a fault trace is identified and can be precisely located by reference to the Council conditions book, subdivision files, site files, or GIS database, buildings are set back 5 metres from the fault trace" (Rule REr.71.1 of the Nelson Proposed Resource Management Plan).
The faults identified in Nelson City have low activity and long recurrence intervals. However, Nelson City Council considered that it was best to design new subdivisions in such a way that avoided buildings being built on faults.
10.14 Section 32 analysis
Before a council adopts any objective, policy, rule, or other method, it has a duty under section 32 of the Resource Management Act 1991 to consider alternatives.
Essentially, the council is required to evaluate the costs and benefits of its proposed objective, policy, or method.
Section 32 ensures that the proposed provisions are necessary, and that accurate data has been used to carry out the evaluation.
It means that a council cannot simply adopt the approach of a neighbouring council - it must first justify its reasoning. Any response the council chooses to take has to be supported by the community and backed up by a section 32 analysis.
10.15 Cross-boundary issues
Natural hazards do not stop at local authority boundaries. It is important to consider how the plan will co-ordinate with the plans of territorial authorities that share the same hazards, to ensure that provisions are integrated across councils.
10.16 Monitoring
The plan needs to specify measurable outcomes that will ensure that issues are addressed, and objectives and policies achieved.
These can be measured by looking at:
- number of houses being built on at-risk land
- type of houses being built (construction and use)
- land subject to active faults being set aside/purchased
- the level of awareness of the community and their acceptance of risk-based plan provisions.
If monitoring shows that the provisions are not reducing fault rupture hazard risk, councils need to revise the provisions. If new information becomes available, councils need to review the level of acceptable risk, and revise the provisions.
Advances in scientific information and technology will affect existing data held by councils, and create new data that needs to be considered for incorporation into planning policy. Councils need to identify new information and this should happen on an ongoing basis, to ensure plan provisions are kept up to date, and ensure decisions based on the most accurate data.
Regional and district plan reviews are a good time to consider new information and data relating to active faults. A programme of consultation should accompany any changes to hazard information gained by the council.
To measure the effectiveness of policies and methods contained in plans, section 35(2A) of the Resource Management Act 1991 requires that the results of plan monitoring be made available to the public every five years. Keeping communities informed about the hazards they face, and changes to existing fault knowledge is important because it not only lets them know what is going on in terms of plans development, but raises awareness of hazards in the community.
10.17 Does your district plan need amending?
In deciding whether to amend a district plan, the council responsible for it first has to decide whether there are active faults within their territorial authority boundaries. If there are none, then there is no need to amend the district plan. Information on the location and type of faults to be found in New Zealand is contained on the website: http://data.gns.cri.nz/af/index.jsp
If there are active faults within a council's territorial authority boundaries the next step is to check the district plan to see whether it contains specific provisions in regard to the use and development of land on or close to active faults. If there are no such provisions, then it is strongly recommended that a plan change or variation be prepared (using the risk-based approach to plan provisions) that will avoid or mitigate effects of or on development located on or close to active faults.
If the district plan contains risk-based provisions that will avoid or mitigate effects of or on development located on or close to active faults then there is no need to change the plan. However if provisions are contained in a district plan in regard to active faults, but do not take a risk-based approach, amending the district plan to incorporate the risk-based approach is recommended.
