1. The parties are to jointly file agreed conditions for a permit within 14 days from the date of these reasons.

2. If the parties are unable to agree conditions in accordance with (1) then within 14 days from the date of these reasons the Council is to file and serve proposed conditions and the appellant is to file any submissions in respect to the proposed conditions within 7 days following filing and service of the proposed conditions.

3. The parties have liberty to apply in respect to this timetable.

Environment and Planning - Planning appeal - Subdivision proposal with in a flood prone hazard area - whether the proposal would achieve a tolerable risk

Land Use Planning and Approvals Act 1993;

Hobart City Council v Rich Tapestry Pty Ltd (ACN 667 999 055) [2024] TASSC 54

West Tamar Council v Resource Management and Planning Appeal Tribunal [2015] TASFC 12;

Au v Glenorchy City Council (No 2) [2024] TASCAT 50;

Meander Valley Council v Resource Management and Planning Appeal Tribunal [2013] TASSC 42

1. The appellant has appealed a decision by the Northern Midlands Council to refuse a permit for a subdivision at Longford. The refusal relates to flood risk.
2. Although the Tasmanian Water and Sewerage Corp Pty Ltd was joined as a party it did not appear the hearing.

1. The proposed subdivision will consist of a five lots. Lots 1, 2 and 3 will each be 600m² residential building blocks. Lot 4 will be a 409m² lot set aside for public open space. It will be transferred to the council to ensure that the adjoining Back Creek levee bank is on public land. Lot 5 contains the balance of 5471m² and includes an existing dwelling.

1. The site of the proposal is within the town of Longford. It is located within the General Residential Zone in cl 8.0 of the Tasmanian Planning Scheme - Northern Midlands (the Scheme). No standards in cl 8.0 were raised for consideration on the appeal.
2. The site is roughly rectangular with the long sides running approximately north and south. The western boundary is approximately 25m east of Back Creek. The southern boundary has a frontage of approximately 60m with Paton Street. A detention basin is located to the south of the site, across Paton Street. The southwest corner of the site adjoins a sewer pump-station. Residential dwellings adjoin the eastern boundary. The Longford football ground is adjacent of the site to the north.
3. Evidence was called from two civil engineers, Mr Hein Poortenaar for the appellant and Mr Daniel Wood for the Council. Mr Poortenaar described the general context of the site in the following terms:

The site is adjacent to Back Creek which is a sizable creek. Floodwaters from the South Esk back up the low lying valley. The South Esk is one of the bigger rivers in Tasmania making its way through the flat Northern Midlands before joining the Meander River and discharging to the Tamar through the Gorge. It has extensive flood plains. Longford is located on its bank and has a long history of flooding and flood protection works.

1. The site is located within the Longford flood levee. The levee consists of a main levee on the South Esk River, a levee on Back Creek and the Back Creek flood gates. The purpose of the flood gates is to prevent flooding in the South Esk River from backing up into Back Creek. In a significant flood event the flood gates would be closed once the Back Creek flood peak has passed and before the South Esk flood peak arrives at Longford.

1. A single revised ground of refusal by the Council was in issue:

The proposal does not comply with clause C12.7.1 P1 of the Tasmanian Planning Scheme - Northern Midlands in that each lot, or a lot proposed in the plan of subdivision, within the flood-prone hazard area, creates an opportunity for use or development that cannot achieve a tolerable risk from flood, having regard to:

(a) any increase in risk from flood for adjacent land;

(b) the level of risk to use or development arising from an increased reliance on public infrastructure;

(c) the need to minimise future remediation works;

(d) any loss or substantial compromise by flood of access to the lot, on or off site;

(e) the need to locate building areas outside the flood-prone hazard area;

(f) any advice from a State authority, regulated entity or a council; and

(g) the advice contained in a flood hazard report.

1. The ground of refusal asserts that the proposal will not comply with the performance criterion P1 of cl C12.7.1 of the Scheme. The appellant contends that the proposal will satisfy P1.

1. Clause C12.7.1 is located in the Flood-Prone Areas Hazard Code (the Code) in cl C12.0 of the Scheme. The purpose of the Code is stated in cl 12.1:

The purpose of the Flood-Prone Areas Hazard Code is:

C12.1.1 To ensure that use or development subject to risk from flood is appropriately located and managed, so that:

(a) people, property and infrastructure are not exposed to an unacceptable level of risk;

(b) future costs associated with options for adaptation, protection, retreat or abandonment of property and infrastructure are minimised; and

(c) it does not increase the risk from flood to other land or public infrastructure.

C12.1.2 To preclude development on land that will unreasonably affect flood flow or be affected by permanent or periodic flood.

C12.7.1 Subdivision within a flood-prone area

That subdivision within a flood-prone hazard area does not create an opportunity for use or development that cannot achieve a tolerable risk from flood.

A1

Each lot, or a lot proposed in a plan of subdivision, within a flood-prone hazard area, must:

(a) be able to contain a building area, vehicle access, and services, that are wholly located outside a flood-prone hazard area;

(b) be for the creation of separate lots for existing buildings;

(c) be required for public use by the Crown, a council or a State authority; or

(d) be required for the provision of Utilities.

P1

Each lot, or a lot proposed in a plan of subdivision, within a flood-prone hazard area, must not create an opportunity for use or development that cannot achieve a tolerable risk from flood, having regard to:

(a) any increase in risk from flood for adjacent land;

(b) the level of risk to use or development arising from an increased reliance on public infrastructure;

(c) the need to minimise future remediation works;

(d) any loss or substantial compromise by flood of access to the lot, on or off site;

(e) the need to locate building areas outside the flood-prone hazard area;

(f) any advice from a State authority, regulated entity or a council; and

(g) the advice contained in a flood hazard report

1. It was common ground that the proposal would not satisfy the acceptable solution A1 and that the proposal falls to be assessed against the performance criterion P1. The ground of refusal mirrors the elements of P1.
2. The test in P1 is that each proposed lot "must not create an opportunity for use or development that cannot achieve a tolerable risk from flood". It apples to proposed lots within a flood-prone hazard area. P1 directly reflects the objective in cl C12.7.1:

That subdivision within a flood-prone hazard area does not create an opportunity for use or development that cannot achieve a tolerable risk from flood.

1. It was common ground that the site is within a flood prone hazard area as defined in cl C12.3.
2. The focus of the hearing was on the question of tolerable risk. 'Tolerable risk' is defined in table 3.1 of the Scheme as:

means the lowest level of likely risk from the relevant hazard:

(a) to secure the benefits of a use or development in a relevant hazard area; and

(ii) by specific hazard management measures for the intended life of each use or development

1. The Tribunal considered that definition in Au v Glenorchy City Council (No 2) [2024] TASCAT 50 and said at [39]:

39. In assessing whether a risk is tolerable, we must consider the benefits of the development in the relevant area and the measures that can be put in place to manage the risk from the hazard. Assessing tolerable risk is not a purely quantitative or binary exercise. Nor does it involve replication of the Handbook's H1 through to H6 risk categorisation.

The reference by the Tribunal to 'the Handbook' is to the Australian Disaster Resilience Handbook 7 referred to below.

1. The benefit of the proposed development is the provision of residential building blocks at the edge of a developed residential area within the General Residential Zone, the purpose of which includes, at cl 8.1.1, the provision for residential use or development that accommodates a range of dwelling types. The relevant hazard is periodic flooding, in particular from the Back Creek watercourse. The issue is whether the benefit may be secured by management of the likely flood risk through measures to achieve a tolerable risk. This will require consideration of the likely risk and the measures to address that risk.
2. In considering compliance with P1, we are to have regard to the matters listed (a)-(g) in the standard. The obligation to have regard to those matters does not raise them to the status of separate standards with which the proposal must comply, but means that we are required to take them into account as a fundamental element of our decision-making in respect to the test in the standard: Hobart City Council v Rich Tapestry Pty Ltd (ACN 667 999 055) [2024] TASSC 54 at [36].

1. Mr Poortenaar's evidence was that the flood levee is designed for a 1 in 100 year flooding event, also known as 1% annual exceedance probability, or 1% AEP. A 1% AEP flood has a 1% chance of occurring, or being exceeded, in any one year. He noted that the levee has no freeboard above that level. A 2016 flood study recommended raising the Back Creek levee, but there are no current plans to do so. The crest of the levee varies between 139.6 and 139.75m AHD, which is height above sea level. A 1% AEP event with the Back Creek flood gate open would result in a flood level of 139.6m AHD. However, modelled with climate change the level would be 140.16m AHD, which is 600mm higher than crest of the existing levee.
2. Mr Poortenaar's evidence was that if the levee was overtopped flood waters would spill in a broad flow, inundating 26ha of low lying area on the west side of Longford, and affecting approximately 350 properties. Some properties, including the three proposed building lots and the balance lot, would be inundated by up to 2m.
3. The Australian Institute for Disaster Resilience publishes a guide to best practice in flood risk management, known as the Australian Disaster Resilience Handbook 7. Guideline 7.3 in the handbook includes general flood hazard classifications that were relied on by both experts. The classifications include vulnerability curves which are a product of depth and velocity of flood water. The vulnerability curves provide ratings in a range from H1 to H6, increasing in severity. Mr Poortenaar considered that a flood depth of 2m at the site would correspond to a flood rating between H4 and H5. H4 is unsafe for people and vehicles. H5 is unsafe for vehicles and people, with buildings vulnerable to structural damage and some less robust building types vulnerable to failure.
4. Mr Poortenaar observed that there is a risk that the levee could breach, which would result in a more destructive flow in the location of the breach, but he considered that the risk of breach was low.
5. Mr Poortenaar noted that the site is currently at a height of 137.75 to 138m AHD, which is 2.4m below the 1% AEP flood level. He considered that the site could be raised to 138.25m AHD using fill without disadvantaging neighbours.
6. Mr Poortenaar recommended that the habitable floor levels of buildings on the lots should be above the 1% AEP level, which would be achieved by having a non-habitable basement with the floor level at 140.5m AHD, allowing a 0.3m freeboard. The basement would need to be constructed so as to be able to be inundated without damage. He noted that the National Construction Code provides requirements for buildings in flood areas.
7. In addition to raising the level of the site and raising floor levels above the 1% AEP, Mr Poortenaar observed that mitigation options included evacuation. His evidence was that a major flood would have a couple of days warning with ample time for evacuation.
8. Mr Poortenaar stated that the functional life of a new residential dwelling in Australia is normally 50-60 years. Having regard to climate change, he calculated the likelihood of a flood overtopping the levee in a period of 60 years at 66%.
9. Mr Wood has extensive experience specialising in floodplain management and hydraulic modelling. He undertook an assessment of the proposal against the elements in P1.
10. Mr Wood agreed that elevating the habitable floor levels above the defined flood level would mean that the habitable level of a proposed dwelling would meet the requirements of tolerable flood risk with regard to protection of persons from flood water which would overtop the levee. He observed that flooding from Back Creek which overtopped the levee adjacent to the site would occur rapidly with little time to safely evacuate, and with access to the site cut off.
11. Mr Wood considered that with the flood gates open a 1% AEP event would result in Back Creek overtopping the levee within a short timeframe. Once flood waters overtopped the levee, drainage of the areas behind the levee would be constrained to the stormwater drainage network with effective discharge only occurring once levels outside the levee have receded. He considered that the duration of flood water above 138.5m AHD, equating to between .5 and 1m of flood depth on the site, may exceed two days at the site. He considered that there was a risk that occupants of dwellings on the site may be isolated for extended periods of time.
12. Mr Wood said that the depth of flow through the site at 2m would create a very high hazard that would be unsuitable for people and vehicles to enter and would put property and buildings at risk. Buildings would need to be designed to be compatible with that risk. He observed that not every conceivable flood can be accounted for and it is never possible to completely eliminate risk.
13. Mr Wood considered that any construction would need to adhere to flood resilient design principles. He considered it preferable that the void underneath the habitable floor level be unenclosed to avoid that area being used for habitable space. Mr Wood observed that damage may occur to non-building property, such as cars, lawn mowers and so forth.
14. Mr Wood accepted that a strategy such as a car lift could be used to avoid non-building property damage, although he observed that a car lift would require a sufficient void above it, which may make it unrealistic. The possibility of using a car lift would increase with using fill to raise the level of the site. He did not consider that development on the site was totally unviable and noted that similar areas had been viably developed elsewhere in Australia and Tasmania.
15. Mr Wood considered that there was minimal risk to the site from flooding from the South Esk and that Back Creek was the primary risk. The speed of flooding from Back Creek would make it difficult to formulate an evacuation strategy.
16. Mr Wood considered that the risk of collapse of the levee is low. He agreed that in the event of collapse the risk level would be at an H5 event. He considered that residential building could be constructed to cope with such an event, with the lower uninhabited area constructed to withstand those forces.
17. Setting aside evacuation, Mr Wood accepted that raised floor levels above 1% AEP, building design to cope with an H5 event and raising the ground level with fill would result in a tolerable risk to the occupants and the building, although non-structural property would be at risk.
18. Mr Wood had a significant concern in respect to evacuation given the speed of flooding from Back Creek if the levee were overtopped. He did not, however, consider that it would be impossible to establish an evacuation plan. He considered that risk would not be tolerable unless there was a safe zone of evacuation on the property in the circumstances of an extreme event, inundating the habitable floors of the dwelling. This did not need to be a floor, but could be access to the roof in the event of a worst case scenario.
19. Mr Wood said that evacuation may not be the preferred option. Remaining in a property may be a reasonable response to risk. He said that advising people that they should stay in their home was not a matter to consider lightly, but equally he said that caution needed to be taken in recommending evacuation given the risks of entering flood waters. For that reason a safe zone of evacuation should be provided in any dwelling in the event of a catastrophic flood exceeding the 1% EAP level and inundating the habitable floors.
20. Mr Poortenaar and Mr Wood prepared a statement of agreed matters. They agreed that the existing flood warning network, based on South Esk River flooding, may not provide sufficient warning before a Back Creek dominated flood or a combined Back Creek and South Esk flood. They agreed that in a scenario where the South Esk is in flood and Back Creek is not, the flood gates should prevent flooding from impacting the site. They agreed that raising the ground level of proposed dwellings with fill resulting in a 1.0m or less depth in the defined flood event would reduce the structural risk and reduce the hazard to a level that is safe for buildings. They agreed that once the levee is overtopped or breached the time for inundation would be short and that there would be limited time to react to the event.
21. Mr Poortenaar suggested that a condition requiring the entering into of a part 5 agreement would be an appropriate response to risk. A part 5 agreement is one entered into with a planning authority under Pt 5 of the Land Use Planning and Approvals Act 1993, which is registered on the title to a property and which binds subsequent owners. The Council will not agree to a part 5 agreement. The Tribunal can impose a condition making subdivision conditional on the entering into of a part 5 agreement, but cannot force the Council to enter an agreement: West Tamar Council v Resource Management and Planning Appeal Tribunal [2015] TASFC 12 at [23], [36] and [54].

1. The test in P1 is that a lot must not create an opportunity for use or development that cannot achieve a tolerable risk from flood. The subdivision will create an opportunity for residential use and development by creating three residential building blocks. If the construction and use of a dwelling cannot achieve a tolerable risk from flood then P1 will not be satisfied. The test does not require that any or every form of residential dwelling must achieve a tolerable risk, but that the use and development cannot achieve a tolerable risk. The issue then is whether a residential dwelling and it occupation can achieve a tolerable risk. There is no difference between each lot in respect to this assessment.
2. We are required to have regard to the elements (a) to (g) in P1. In respect to (a), any increase in risk from flood for adjacent land, the evidence did not establish that development on the proposed lots would cause increased flood risk to adjacent land. There would be negligible loss of flood storage volume as a result of development on the lots. The risk identified by Mr Wood is increased pressure on emergency services and evacuation centres. Even if they might be considered as an increase in risk for adjacent land, the increase is not significant in the context of three additional dwellings in an area where there are some 350 dwellings already prone to inundation in a flood event.
3. In respect to (b), the level of risk to use or development arising from an increased reliance on public infrastructure, the only relevant public infrastructure is the levee itself. The proposal will rely on the levee but will not have any effect on the levee or consequentially on other use or development.
4. In respect to (c), the need to minimise future remediation works, the only remediation work identified is the possibility of raising the height of the levee, which would not be impacted by the proposal.
5. In respect to (d), any loss or substantial compromise by flood of access to the lot, on or off site, it is clear that a flood event where the levee is overtopped would result in the proposed new lots being cut off from access by flood waters. This would be the same for other development in the area. It would require a response by way of an evacuation plan and safety zones in any dwelling constructed on the lots.
6. In respect to (e), the need to locate building areas outside the flood-prone hazard area, the entire site is within the flood-prone hazard area, as is the surrounding residential area generally. There is no opportunity to locate building areas outside the flood-prone hazard area.
7. In respect to (f), any advice from a state authority, regulated entity or a council, no particular advice was relied on other than the Council's modelling of the 1% AEP event.
8. In respect to (g), advice contained in a flood hazard report, a report was prepared by Mr Poortenaar for the development application. The report concluded that a tolerable risk would be achieved if the habitable floor levels of dwellings were required to be at 140.50m AHD or higher.
9. The current 1% AEP flood level is at the levee height, so that flooding will only occur for events greater than the 1% AEP event. However, the risk of overtopping will increase with climate change, and Mr Poortenaar's evidence establishes a likelihood that a 1% EAP event overtopping the levee will occur within the life of a dwelling erected on the site. In that event the site will be flooded to a depth greater than 2m and experience a flood rating between H4 and H5.
10. Mr Woods evidence as to risk arising from a Back Creek flood event is compelling. He explained that it would be rapid, with perhaps less than 12 hours between the onset of rain and inundation, and that inundation may occur while the rain event is in progress. There is presently no alarm system in place and evacuation may be challenging given short notice.
11. However, on Mr Woods evidence, a tolerable risk can be achieved for a residential building and its occupants by raising the level of the lots, ensuring an appropriate floor level for the habitable areas of a dwelling, and having an appropriate evacuation plan, including an evacuation area on the site.
12. These are matters that would be addressed in the assessment of a development application for a residential dwelling on a lot, which would be subject to the development standards in the Code. Those standards include cl 12.6.1, which requires that buildings and works within a flood-prone hazard area must achieve and maintain a tolerable risk having regard to the type, form, scale and intended duration of the development. Residential uses are either no permit required or permitted in the General Residential Zone under the use table in cl 8.2. However, cl 12.6.1 contains no acceptable solution, requiring each development to meet performance criteria and so establishing a discretion to grant or refuse a permit for no permit required and permitted uses: see cl 6.6.1(b), cl 6.7.1(b) and cl 6.7.2(b) of the Scheme.

1. The proposed development is able to secure the benefit of providing residential building lots in circumstances where the flood hazard can be managed through hazard management measures. We are satisfied that lots 1-3 and 5 do not create the opportunity for use or development that cannot achieve a tolerable risk from flood. Lot 4 is to be provided for public open space.
2. The appeal should succeed. A permit for the proposal would normally issue subject to conditions. The decision whether to grant a permit and the conditions to be imposed on such a grant are not separate considerations but components of a single process: Meander Valley Council v Resource Management and Planning Appeal Tribunal [2013] TASSC 42 [10]. In accordance with usual practice the Council provided a draft set of conditions prior to the hearing. It would be reasonable to give the parties the opportunity to consider the conditions in the light of this decision before proceeding to a final determination and orders.
3. Accordingly:
   1. The parties are to jointly file agreed conditions for a permit within 14 days from the date of these reasons.
   2. If the parties are unable to agree conditions in accordance with (1) then within 14 days from the date of these reasons the Council is to file and serve proposed conditions and the appellant is to file any submissions in respect to the proposed conditions within 7 days following filing and service of the proposed conditions.
   3. The parties have liberty to apply in respect to this timetable.