FAQ

The preferred response package sets out the different elements that will be applied to manage different levels of rockfall and debris flow risk identified across Brewery Creek and Reavers Lane. 

The preferred response package includes the following four elements:

The preferred response package recommends a set of approaches to manage the different types and levels of natural hazard risk identified across Brewery Creek and Reavers Lane. For example, it is recommended that the reduce approach apply to significant levels of risk and that the manage approach apply to tolerable levels of risk. 

However, there are no national or legislated standards which define significant, tolerable, or acceptable risk. Therefore, Council has a choice about where to place lines on the ground that identify the specific area subject to each element of the preferred response package. A further work programme will need to be undertaken to inform where the different elements recommended by the preferred response package will be applied, and their detailed design. 

Development of the preferred response package has taken into account a number of factors, including: 

• Technical advice on risk, engineering options, loss modelling, and social and economic impact assessments
• Feedback received from the community consultation undertaken in November and December 2021
• Policy direction in the Resource Management Act (RMA), RPS, and the PDP.

The preferred response package was endorsed by Queenstown Lakes District Councillors on 30 June 2022. Endorsement of the package does not trigger any ‘on the ground’ implementation at this time. Instead, it signals Councillor support for the different elements that make up the preferred response package. Further work is required to develop the details of the different elements of the Preferred Response Package, and to comprehensively understand its costs and benefits. This additional work will inform future advice to Councillors.

Important decisions still need to be made, such as where the different elements recommended by the preferred response package will be applied, detailed design of rockfall structures, and different ways to support the implementation of any reduce approach, and the package itself.

Detailed planning and scheduling of the further work programme has begun. It is estimated that it may take 18 – 24 months to complete this important further work.

A further work programme will need to be undertaken to inform where the different elements recommended by the preferred response package will be applied, and their detailed design. This further work programme will need to be progressed before the costs and benefits of the preferred package are fully understood, and before the package could be ready for implementation. 

This further work will address a wide range of matters including engineering, legal, financial, and funding matters, as well as responsibilities for and the timing of implementation. It is estimated that it may take 18 – 24 months to complete this.

The review aims to understand the nature and scale of natural hazard risk across two alluvial fans, and which options are most appropriate to manage this risk. These two areas are known as Brewery Creek and Reavers Lane. They are located off Gorge Road near the Queenstown CBD. They have not yet been considered by the current District Plan review to allow natural hazard risk to be considered.

Alluvial fans are cone shaped landforms which typically form where streams emerge from hill country onto valley floors. Alluvial fans are dynamic landscapes that can be associated with natural processes such as debris flows, rockfalls, landslides, flooding and liquefaction. These processes can create natural hazard risks where they interact with people and built form.

The land being reviewed includes two areas near the Queenstown CBD, on the western side of Gorge Road. These two areas are located on the surface of geological features known as ‘alluvial fans’. The northernmost alluvial fan is referred to as Brewery Creek, while the southernmost alluvial fan is referred to as Reavers Lane.

Beca undertook a comprehensive assessment of natural hazard risk. Their report is available on our lets talk page and can be found here. A brief summary of Beca’s risk assessment findings is provided below.

Liquefaction: The assessment of liquefaction hazard found that liquefaction damage is possible for the lower areas of the two fans, and unlikely for the upper fan areas. This risk can be managed through usual building consent processes.

Flooding: The assessment of flooding hazard has shown that during a 100 year Average Return Interval event, small areas of minor flooding may occur in the Brewery Creek area, while minor flooding with small areas of significant flooding may occur in the Reavers Fan area. This risk can be managed through usual building and resource consent processes.

Debris flow and rockfall: The assessment of risk to life  from debris flow and rockfall hazard has shown high levels of risk  are present on the upper parts of both fans. Some areas are subject to levels of life risk that are similar or higher than levels of risk where other Councils have taken specific actions  to reduce risk.

Our risk assessment has shown that debris flow and rockfall also present a high risk to property in the upper parts of both fans. Modelling of damage to properties as a result of debris flow events gives us an estimate of the monetary losses from property damage. Information on this can be found in the GNS Science 2021 Loss Modelling report which can be accessed here. Key results from the loss modelling assessment are set out below:

• For Reavers Lane, the loss estimates range from $13.5M for a small event, to $17.1M for a medium event, and $39.2M for a large event.
• For Brewery Creek, the loss estimates range from $1.1M for a small event, $11.1M for a medium event, and $14.1M for a large event.  

The high levels of risk to life and property from debris flow and rockfall hazards are of concern to Council, and we expect they are likely to be of concern to property owners and residents. Usual building and resource consent processes are not the most effective or efficient way to deal with these high levels of risk, and Council has considered specific response options for managing this risk.

Council has undertaken a number of technical assessments relating to natural hazards in the Brewery Creek and Reavers Lane areas, including:

• An assessment of natural hazard risk in the area (by Beca Limited)
• An assessment  of engineering options to manage rockfall and debris flow risk (by Beca Limited)
• A report on potential property damage and losses (by GNS Science)
• An assessment of the social and economic impacts of the different options being considered to manage elevated levels of risk (by Market Economics Limited).

Council staff have shared this information with QLDC Councillors and the Brewery Creek and Reavers Lane community. All of the technical assessments are available on our lets talk website.

Council staff developed four separate options that could be applied to manage rockfall and debris flow risk across Brewery Creek and Reavers Lane. These four original options were developed to help inform assessments of the various costs and benefits that might be associated with different ways to manage natural hazard risk. 

The four original options were shared with QLDC Councillors and presented to the Brewery Creek and Reavers Lane community at our consultation events during November and December 2021. 

A summary of the four original options can be found here. They included:

• Option A – Status Quo 
• Option B – Engineering 
• Option C – Manage
• Option D – Reduce

Beca prepared an assessment of engineering options that could be applied to manage rockfall and debris flow risk. Their assessment can be found here.

Beca found that rockfall fences would be able to reduce the risk from rockfall to tolerable levels on both fans. The construction cost of these fences would be in the order of $1M for each fan. The ongoing maintenance costs of these fences has not yet been calculated in detail.

Beca also considered engineering options to control debris flow events. They included fences in the gullies above the fans, works to create a channel on Reavers fan, and to deepen and widen the existing channel at Brewery Creek. These options are not able to reduce debris flow risk to  to a tolerable level. This means  engineering options are not able to satisfactorily address risk from debris flow hazard.

GNS Science was commissioned to model the effectiveness of the original options at reducing property damage.. They demonstrated that the Reduce option was the most effective at reducing property damage. This is because this option removes built form from the areas of highest risk. The Manage option was the next best at reducing property damage, as it puts restrictions on future development in the high risk areas. The engineering option was shown as being able to reduce some property damage in small events only (not for medium or large events). The Status Quo option was the worst at reducing property damage, as it does very little to manage development in the high risk areas.

Market Economics was commissioned to assess the socio-economic impacts of implementing each of the original risk management options. Their report is available on our lets talk page here. The report tells us that:

• for Reavers fan, all options except the engineering option (rockfall fences and debris flow fences) would result in more economic costs than economic benefits, when compared to the Status Quo
• for Brewery Creek, all options would result in more economic benefits than economic costs, with the engineering option (rockfall fences and debris flow fences) having the biggest economic benefit, when compared to the Status Quo. 

Market Economics was commissioned to assess the socio-economic impacts of implementing each of the original risk management options. Their report is available on our lets talk page here. The report us that:

• the Reduce option has the most social benefits for both fans, and the status quo has the least social benefits. The Engineering and Manage options have social benefits between the Reduce and Status Quo options.
• The Reduce option has the highest social costs on both fans, and the Manage option has the least social costs. The Engineering options have social costs between the Reduce and Manage options.

QLDC is gathering a wide range of information to inform its decision on how to deal with the higher levels of risk. A key part of this information is the opinions of the community. QLDC acknowledges the technical nature of this issue, and it’s very personal impact on those that live, work or own property in the area. We are committed to working with the community to understand the technical information on the levels of risk and what it means for people and their homes/businesses/properties. We are also committed to considering a range of response options, and understanding the community views on these options. Each option has different pros and cons, or costs and benefits. It is a challenging task to figure out which benefits are the most important and which costs are too high. This is what we would like feedback on.

The coming phase of community consultation is expected to be completed before Christmas. In the New Year, the feedback from the consultation will be incorporated with the technical information on the options for responding to the higher levels of risk. QLDC will then need to make a decision on which option, or combination of options, to move forward with. This will involve considering what level of benefit is sought by QLDC and the community, and what QLDC and the community are prepared to pay or sacrifice for that benefit. This will be a difficult decision to make. Our work so far suggests there is no ‘easy’ option in this situation.    

QLDC will keep the community informed as the process moves forward, and there will be further opportunities to provide feedback in the future.

Over November and December 2021, Council staff invited the Brewery Creek and Reavers Lane communities to a series of consultation events. The purpose of these consultation events was to share information about the hazard and risk, let people know about the costs and benefits of management response options, and seek feedback on views and preferences from those affected by the hazard and the original management options. 

The consultation events included drop in sessions that were open to everyone, as well as smaller group discussions which focused on specific levels of risk and the options available to manage that risk.

The 2021 consultation events provided important information from the Brewery Creek and Reavers Lane communities. They provided information on the views and preferences of those affected by the hazard and the original management options. 

The consultation events were facilitated by independent Dr Margaret Kilvington. Following the consultation, Dr Kilvington produced a report which details the views and feedback that was received from the events. The consultation report can be found on our Let's Talk page here.

A summary of the key points from the consultation report are provided below:

• There was considerable concern about the risk, and almost no one considered it to be acceptable.
• There was general acceptance that QLDC will need to act to manage the risk, but it was considered that the response should be proportional.
• None of the four options were positively viewed by everyone. 
• Status quo was the least preferred option, and engineering was the most preferred option.
• The reduce option was regarded as a last resort.
• The manage response was not favoured as a means of protecting the existing community as it does nothing tangible for those currently living and owning property in the area.
• There was a degree of uncertainty about what implication of each of the options would look like and what it might cost for each option.

The views and preferences collected from the 2021 consultation events have directly influenced the development of the preferred response package. A key finding from the consultation is that something should be done to manage risk on the fans. Another key finding is that there is no single preferred option. The preferred response package acknowledges these findings by intervening to manage elevated levels of risk and combining the most effective components of the various original management options. 

Engineering interventions were supported by the community, and this has been included in the preferred package in the form of rockfall fences and mesh. The most restrictive components of the original manage option were not well supported by the community and these have not been included in the preferred response package. Instead, the manage approach is recommended across areas subject to tolerable levels of risk to ensure risk does not become significant overtime. The reduce option was reluctantly accepted as having benefits for risk reduction, but it was also clear that it should be a last resort. The preferred response package includes a reduce component as it is acknowledged as the only way to reduce significant levels of risk. The preferred package recommends only applying a reduce approach across areas of significant risk.   

Public consultation was held over November and December 2021. During our consultation events we welcomed feedback from the diverse community that lives and works in the area, including landowners, renters, business operators, families, and employees. This feedback has been used to develop the preferred response package. The preferred response package was endorsed by Queenstown Lakes District Councillors on 30 June 2022. 

Staff are now preparing to undertake a further work programme to support the detailed development of the different parts of the preferred response package. Consideration will be given to undertaking further engagement with the affected community.

Any and all feedback is welcome and can be provided via email at letstalk@qldc.govt.nz.

More information and technical reports can be found on letstalk.qldc.govt.nz. We’d also encourage you to get in touch, either via email to letstalk@qldc.govt.nz or phone on 03 450 0350.  

QLDC has sent letters to property owners and residential occupiers in the Brewery Creek and Reavers lane area. If you live, own residential and/or commercial property or work in an area near the hazard areas but not in a location subject to the plan review, you will not have been sent a letter. You are however welcome to provide feedback, even if you did not receive a letter.  

Risk can be understood as the combination of likelihood and consequence. Likelihood is the chance of a hazard event happening. Consequence is the result or impact of the hazard event occurring. 

Risk can range from no or very low risk to very high or significant risk. Consider a hazard event such as a flood. A river may have small floods that occur frequently (say once every couple of years) and that small flood may have minor impacts on properties. Overall, the risk would be considered low. The same river may have a large flood that causes catastrophic damage to property, but that only occurs occasionally (say once in 200 years). Overall, the risk would be considered high, even though it is not a common occurrence, because of the significance of the resulting damage to property.

Different controls can be applied to manage different levels of risk. For example, no controls where the risk is low, and quite restrictive controls where the risk is high. In some cases, risk can be significant enough to consider moving people out of harm’s way.

The community can help inform which controls are used at different levels of risk, by providing feedback on tolerance for risk – what level of impact can be tolerated at what frequency. Or put another way, how strong an intervention is justified at different levels of risk.

AIFR stands for ‘Annual Individual Fatality Risk’. It is the probability that an individual most at risk is killed in any one year as a result of debris flow or rockfall. The methodology for calculating AIFR is set out in the Australian Geomechanics Society Guidelines for Landslide Risk Management (2007).

It is important to note that AIFR is the probability for an individual – it is not a measure of societal risk. AIFR doesn’t take account of the number of individuals that may be present in a particular area. However, it is a well-recognised metric for understanding the level of risk present in a particular area.  

No, these are not the only known alluvial fans in the District. There are other alluvial fans which we know about. Some of these have little or no development located on them. Others have a degree of more recent development that has been subject to assessment through the resource consent process. These other alluvial fans are not subject to the current review, but the zoning and plan controls may be reviewed in the future.

Rockfall refers to blocks of material which roll, fall or bounce down a slope, either on their own, or in small clusters.

The old rubbish tip is located within Warren Park and not within the area of land that is subject to this plan review process.

Natural hazards are something we live with. They come with the territory of living in many places across New Zealand and Queenstown is no different. They are a product of what makes our district such a special place to live, work and play – the alpine environment, our mountains, rivers and lakes which can be highly dynamic and changeable.

It’s important to remember that these two areas are known to have been associated with alluvial fans and natural hazards for quite some time. For example, debris flows occurred in this area in 1986 and 1999. The current plan review process has therefore enabled us to refine what we know about existing natural hazards in this area. Council is obliged to manage risk from natural hazards under the Resource Management Act.

Changes to planning rules don’t necessarily result in changes to insurance premiums or property values. Insurance companies have their own methods for understanding risks.

An assessment of the likely effect of climate change on debris flow AIFR was undertaken. The results indicate an increase in AIFR of just under one order of magnitude between current climate conditions and the most extreme climate change scenario for the year 2090.

For flooding, peak flows would be 30-35% higher, with a 16% increase in flood volume, by 2090.

Climate change is not expected to affect the risk from rockfall or liquefaction.

Both catchments are mostly forested, with a mix of native mountain beech forest and wilding douglas fir. Trees can influence natural processes in various ways, for instance:

• trees can help stabilise soils and other material on the slopes of the catchments (limiting the movement of material towards people and property on the alluvial fan surfaces)
• tree trunks and other vegetation have the potential to form small dams that can fail and result in pulses of debris during significant rainfall events

The risk assessment has considered both the current forested, and theoretical un-forested situations. In the un-forested situation, the levels of risk extend further down the fan surfaces, because material is deposited further down the slope when there is no vegetation to inhibit initiation and transportation of the debris.

The wilding douglas fir in the catchments is managed by the Wakatipu Wilding Conifer Control Group. Work has been undertaken in recent years to suppress the wilding trees at the treeline. QLDC planners working on this plan review have been, and will continue to be, in regular contact with both the Infrastructure and the Parks and Reserves department staff on this matter.

It is possible to manage tree removal through the use of land use rules in the District Plan. This may be an option considered as part of the response to managing the levels of risk on the fans.

The site of the previous Wakatipu High School is located outside of the area being reviewed because it is not located on the surface of either the Brewery Creek or Reavers Lane alluvial fans. It is located between the two fan surfaces. It is therefore not subject to the same types of natural hazards (e.g. debris flow and rockfall) that the fan surfaces are. Even so, any future development on the old school site will need to consider the effects of natural hazard events.

The impact of natural hazard events on developed alluvial fans can be significant. Debris flow and rockfall events, in particular, have the potential to catastrophically damage homes and other buildings, and result in loss of life and serious injury. At the same time, planning controls to manage risk from natural hazards can have a significant impact on the economic and social wellbeing on individuals and communities. Council needs a comprehensive understanding of the degree of risk present, so that any intervention is targeted and appropriate to manage the degree of risk to property and people.     

The first phase of the risk assessment, completed in May 2019, indicated potentially high levels of risk on the upper parts of the alluvial fans. In response, Council decided to do further, more detailed, investigations into the levels of risk, to allow these to be refined. In addition, Council decided to undertake technical assessments of the risk management options available to manage the levels of risk, so that the impact of these options on individuals and the community could be understood.

Community consultation is an important part of managing natural hazard risk, particularly in circumstances where risk to property and life is high, and where the risk management options have social and economic impacts on the community.  Community consultation was undertaken over November and December 2021. 

These investigations and consultation take time. While it means the process to arrive at a proposed option to manage risk from natural hazards will take a long time, it also means the decision-making process will be based on sound technical information and be informed by feedback from the community.

This is the first area-specific natural hazard risk assessment that QLDC has conducted and follows recent updates to national, regional and district level planning documents. These changes direct QLDC to manage significant risk from natural hazards and to understand the community’s tolerance to natural hazard risk.  

The Brewery Creek and Reavers Lane areas are not the only alluvial fans within our district - it is anticipated that other areas subject to natural hazard risk will go through a similar process at some later stage.

This part of the District Plan review is a little different from other topics as it is specific to natural hazard risk that affects a small defined area. It also involved a period of targeted community pre-consultation specifically on the matter of natural hazards.