Webster v Muswellbrook Shire Council

Case •

[2013] NSWLEC 1146

•

12 August 2013

Land and Environment Court


New South Wales

  • Amendment notes
Medium Neutral Citation: Webster v Muswellbrook Shire Council [2013] NSWLEC 1146
Hearing dates:7 August 2013
Decision date: 12 August 2013
Jurisdiction:Class 1
Before: Hussey C
Decision:

(1)The appeal is dismissed.

(2)Development application No 162/2012 for the installation of a manufactured home to create a detached dual occupancy at 119 Sydney Street, Muswellbrook is refused.

(3)The exhibits may be returned except A, 1, 7, 8 and 9.

Catchwords: DEVELOPMENT APPLICATION - Detached dual occupancy, site located within floodplain, flooding risk, precedent, public interest
Legislation Cited: Muswellbrook Shire Development Control Plan 2009
Muswellbrook Local Environmental Plan 2009
NSW Floodplain Development Manual 2005
Category:Principal judgment
Parties:

Mr Len Webster and Mrs Jennifer Webster (Applicants)

Muswellbrook Shire Council (Respondent)
Representation: Ms M L Saw
Direct access brief (Applicant)
Mr A Seton
Marsdens Law Group (Respondent)
File Number(s):10244 of 2013

Judgment

Background

  1. This appeal is against Council's refusal of a development application for the installation of a manufactured home at 119 Sydney Street, Muswellbrook to create a detached dual occupancy development.

  1. The subject land is relatively large with an area of 2,294 m2 and a depth of 140 m. The rear of the property extends to the Hunter River, which is liable to flooding.

  1. Consequently, the contentions identified for the appeal concern:

  • Flood risk to life and property, due to the land being located within/adjacent to the floodway
  • Precedent, in terms similar development opportunities being available for several nearby properties
  • Compatibility of the development
  • Public interest

  1. The appeal commenced by way of a s 34AA conference onsite. Initial discussions took place with the parties concerning procedural matters and the documents to be relied upon, including the over due joint engineering report. It was agreed that the site inspection proceed and the procedural matters be resolved on return to the Court.

  1. On return to the Court and following discussion of the contentions, there was no agreement and the s 34 conference was terminated and the appeal proceeded for determination.

The site

  1. The subject property is described as Lot 7 in DP 745572 and it is located on the northwest fringe of Muswellbrook, within a designated "High Hazard Floodway". It has a total area of 2,294 m2 and a frontage of 16.1 m to Sydney Street and side boundaries in the order of 140 m.

  1. A number of existing structures are located on the land, including a single storey weatherboard dwelling and sheds in the back yard.

  1. The locality is predominantly residential in character and consists of single storey, detached residential dwellings, with ancillary structures in the rear yards.

The proposal

  1. The proposal is to install the manufactured home within a footprint of 198.7 m2 behind the existing dwelling on the site to create a dual occupancy development. Consequently, the new dwelling will be substantially screened from the street by the existing dwelling and is to have a setback in the order of 70 m. This will then result in a setback of approximately 60 m from the sites rear boundary adjacent to the Hunter River.

  1. In response to the flooding contention, the finished floor level (FFL) of the new dwelling is to be RL 145.25, which includes a freeboard of 0.5 m above the 1% AEP flood level. The natural ground level is relatively flat in the vicinity of the building location, so that FFL will be approximately 1.5 m above natural ground level. The dwelling is to secured on engineer designed piers.

Planning controls

  1. The following planning controls apply:

.1 Muswellbrook Local Environmental Plan 2009 (MLEP), under which the site is zoned R1 General Residential. Dual occupancies are permitted with consent in the R1 General Residential Zone.

.2 Muswellbrook Shire Development Control Plan 2009 (MDCP).

The following sections of the Muswellbrook DCP apply to all new development on the site:

Section 5 - Subdivision

Section 6 - Residential Development

Section 13 - Flood Prone Land

Section 20 - Erosion and Sedimentation Control

Section 21 - Contaminated Land

Section 25 - Stormwater Management

.3 NSW Floodplain Development Manual 2005 (FDM).

The evidence

  1. Detailed evidence in the form of joint planning and engineering reports were presented by:

  • Mr C Thomas - Council's consulting engineer
  • Mr R Thomson - Applicant's consulting engineer
  • Mr I Scammell - Council's town planner
  • Mr K Nash - Applicant's consulting planner.

Flooding

  1. The threshold issue in this matter concerns the potential flooding risk due to the site being located within the Hunter River floodplain. The planning framework for the assessment of this issue includes the provisions of MLEP wherein cl 2.3 deals with the zone objectives and land use table and provides:

(2) The consent authority must have regard to the objectives for development in a zone when determining a development application in respect of land within the zone.

  1. Accordingly, the stated objectives for the R1 General Residential zone are:

1 Objectives of zone
· To provide for the housing needs of the community.
· To provide for a variety of housing types and densities.
· To enable other land uses that provide facilities or services to meet the day to day needs of residents.
· To enable sensitive infill development of other housing types.
· To allow people to carry out a reasonable range of activities from their homes, where such activities do not adversely affect the living environment of neighbours.
· To promote the principles of ecological sustainable development including energy and water efficient subdivision and housing design.
· To minimise the impact of non-residential uses and ensure these are in character and compatible with surrounding development.
· To ensure that development is carried out in a way that is compatible with the flood risk of the area. (my emphasis).

  1. The associated development controls are contained in the MDCP, which came into force on 10 January 1994. Section 13 contains the controls for flood prone land as follows:

13.1.3 Aims and Objectives
This plan aims to:
· Provide planning provision and guidelines for the determination of development in accordance with the Floodplain Management Plan;
· Minimise the public and private costs of flood damage and risks to life associated with flood events.
· The objectives of the plan are to:
· Inhibit the intensification of residential and other inappropriate uses in flood affected areas;
· Ensure that any developments which do take place are designed and constructed in a manner which is compatible with the flood risk of the area.

  1. Clause 13.2 contains the controls for new residential development, including:

...
c) The floor level of all habitable areas shall be at least 0.5m above the 1% AEP flood level, as determined by Council.
d) Materials used are in conformity with the flood proofing code, Section 13.8.
e) The proposed structure can withstand the force of flowing floodwaters including debris
and buoyancy forces.

  1. The MDCP contains "Flood Prone Land" diagrams, which show the subject land within the 'High Hazard Floodway'. Clause 13.1.2 contains the following definitions:

High Hazard means possible danger to persons; evacuated by trucks difficult, potential for structural damage; possibility of high social disruption and financial losses.
Floodway means those areas of land where a significant volume of water flows during floods and includes the channel of a river or stream and those portions of the flood plain adjoining the channel which constitute the main flow path for floodwaters.

  1. For their assessment of the proposal, the engineers considered these controls together with updated hydrodynamic modelling results that has been undertaken in 2013 as part of the draft 'Updated Muswellbrook Flood Study'. This includes plots of the variation in peak 1% AEP flood level and velocity in the vicinity of 119 Sydney Street.

  1. Insofar as the updated modelling has not been formulated into a new policy by council, for the development of dwellings in the floodplain, nevertheless both engineers agree with the modelling methodology and that the use of the results to predict flooding outcomes is consistent with current engineering practice.

  1. Interestingly, the flood mapping for the 1% AEP shows that in the vicinity of the subject property there are the following 3 flood runners as indicated on Figure 1.

■ Flood Runner A - A flood runner that emanates from the meander bend of Muscle Creek near the intersection of the New England Highway and Mill Street and which carries floodwaters across the eastern floodplain of the main channel, along Sydney Street.
■ Flood Runner B - A flood runner that emanates from the Hunter River immediately downstream from the rear boundary of 119 Sydney Street, and which directs floodwaters from the main channel into the flood runner that originates from overflows of Muscle Creek.
■ Flood Runner C - A flood runner that emanates from the western bank of the Hunter River between Mitchell and Skellatar Streets, and which directs floodwaters onto the western floodplain of the main channel.

  1. The effect of Flood Runner A is a critical consideration because of the significant flowpath along Sydney Street caused by the upstream breakout from Muscle Creek. This consequently results in a "Low Flood Island"(LFI) effect within the allotment at the proposed building site.

  1. The engineers delineated their assessment of this LFI on Exhibit 9. Accordingly, Mr Thomas provisionally defined a smaller LFI, over which there would be:

  • velocities ranging from 0.4 - 0.7 m/s
  • velocity at the edge of the provisional floodway extent = 0.8 m/s (approx).
  • depth at edge of provisional floodway extent line = 0.7m.

  1. According to Mr Thomson, there would be a considerably wider LFI extending closer to the riverbank. Consequently, he classifies this as flood storage area. Considering the velocity x depth multiplier and flow distribution, he estimates that:

  • the approximate velocity at the NW boundary is 1.2 - 1.4 m/s.
  • approximate depth at NW boundary is 0.3m.
  • on the SE side, velocity is 0.9 m/s and depth is 1m.

  1. In response to the contentions, the engineers agree that the development site would be classified as high hazard because of the isolation of the property from high ground caused by the high hazard flow along Sydney Street. However the engineers disagree on whether the site is located within a floodway.

  1. Mr Thomas says that the 'footprint' of the proposed development falls between Flood Runners A and B, which are both floodways that extend through a number of properties located upstream of the greyhound track, including part of 119 Sydney Street. Therefore he considers this is consistent with the floodway delineation currently adopted by Council in the MDCP.

  1. He acknowledges that whilst the 'footprint' of the proposed development could be considered to be technically outside of the floodway corridor, nevertheless sound floodplain management practice should recognise that the central area of 119 Sydney Street is completely bounded by floodway corridors and that the hydraulic classification of the land should be modified to floodway. Therefore, in his opinion the site would be classified as a high hazard floodway, which recognises the substantial risk that existing and future residents would be subject to during times of isolation or when evacuation is required through the adjoining high hazard floodway corridors, particularly Sydney Street.

  1. Whilst Mr Thomson agrees that both the Hunter River and Sydney Street can be classified as a floodway, he disagrees that the site should therefore be classified as a floodway based on a risk to life considerations. He says that a floodway is determined through hydraulic considerations and represent areas, which carry a significant portion of the flood flow (as per the NSW Floodplain Development Manual (NSW Government, 2005).

  1. With regard to the risk to life, the engineers agree that the initial flooding will occur from Sydney Street and that there would be a warning time of about 7 hours. This could allow evacuation across Sydney Street and up Fleming Street to higher ground. However, once flows start to proceed down Sydney Street, evacuation would no longer be safe.

  1. Accordingly, Mr Thomson contends that an evacuation plan should be prepared and this could be covered by a condition of consent. Also, if the property is raised by 300 mm, then the floor level would be above the three times 1% AEP level, which is indicative of an extremely rare event of the order of a Probable Maximum Flood (PMF). This could a "last resort" shelter-in-place option, should evacuation not be undertaken.

  1. Apart from this, the engineers addressed the other issues concerning intensification of land use within the floodplain, structural integrity of the proposed building and impact on emergency services. Having considered this evidence, I am satisfied that the threshold flooding issue concerns whether the site should be classified as a floodway and consequently whether the development should be conditionally approved under the existing controls.

  1. However, the engineers also considered the precedential effect of approving this development. Mr Thomas is of the view that approval of the development will set a precedent that could lead to development of those lots that back on to the Hunter River between 119 Sydney Street and Mitchell Street, thereby leading to intensification of residential land-uses in the floodplain. In his opinion, this outcome could result in up to 26 properties being developed for dual occupancy, which could mean an additional 65 persons living in this area.

  1. Insofar as he does not support the proposal, he says that the development of more similar type developments would unnecessarily increase the risk to life and property and burden on the emergency services in a flood event.

  1. Contrary to this, Mr Thomson says that as the proposed residential development is on zoned residential land similar to the adjoining land, then the relevant authorities (Council and the SES) can assess the cumulative impact of any such developments together with arrangements for existing residents. Consequently, he does not consider that the impact of the proposal on emergency services should result in the refusal of the application.

Planning issues

  1. The main planning issue concerns precedent. This is in the context of there being a number of similar sized allotments nearby situated in the floodplain, where the owners may have similar development expectations, if the current application is approved.

  1. Mr Scammell does not support the dual occupancy proposal because:

  • In terms of residential land uses containing habitable floor space, Muswellbrook Shire Council has historically only approved single occupancy dwelling houses on land that is both residentially zoned and identified as 'High Hazard Floodway' in the Muswellbrook DCP 2010.
  • The majority of dwelling houses on the northern side of Sydney Street and within land identified as High Hazard Floodway were approved many years ago, and all pre-date the local planning instruments currently in force, i.e. Muswellbrook LEP 2009 and Muswellbrook DCP 2010.

  1. Therefore, he considers that the approval of the subject development will establish a precedent. In his opinion, such precedent is undesirable as it likely to pave the way for other residential development of a similar, or potentially greater density, on land identified as High Hazard Floodway, where the risks to life and property and impact on flooding and the flood plain would to be high.

  1. Against this, Mr Nash says that the determination of this issue should be determined on merit taking account of the particular circumstances. Accordingly, he does not consider the approval of the proposal will create a precedent and supports it on the following basis:

  • Reference to the aerial photograph at Figure 1 indicates that there are only four (4) other similar deep allotments with the potential to accommodate a similar form of detached dwelling in the rear yard (113-121 Sydney Street).
  • All of these allotments have a depth in the order of 140 metres, with frontages of 16.145 metres and direct frontage to the Hunter River.
  • Hypothetically, each of these four (4) sites (113, 115, 117 and 121) could accommodate an additional detached dwelling on the allotments.
  • Other allotments in the vicinity are of a more traditional size and shape to be unlikely to accommodate an additional dwelling.
  • In terms of the potential for an increase in the resident population in the Sydney Street Precinct, it is likely to be limited to 8-10 persons given the average household size of 2.5 persons for Muswellbrook Urban Area in the 2011 Census.
  • The subject lot is well located to the evacuation route in Fleming Street.

  1. However, after cross examination of the planners, they generally agreed that there was a possibility that between 17 - 20 properties on the northern side of Sydney Street could be developed in a similar way, which would result in a population increase in the order of 42 - 50 extra people.

  1. Apart from this, Mr Nash also referred to other developments in the vicinity, particularly the recently approved development for a 'rural supplies business and veterinary hospital' to the west of the site, just downstream of the subject proposal. From reference to the following Council report on that development, he considers the approval of the proposal would be consistent with the approach taken by council as follows:

"Flooding
The site is located within an area identified as high hazard flood risk from the Hunter River and within an overflow flood path from Sydney Street. Council requested further information on flooding to assess the impacts of the development on the floodplain, the proposed filling and the potential increase in flood heights. A Flood Assessment Study was prepared by RHM Consulting Engineers on behalf of the applicant to support the development. The study makes the following conclusions:
1. The impact of the development on the flood height would be 10mm over the width of the flood plain.
2. The suggested increase in flood height will have little to no impact on both downstream properties and properties that front Sydney Street.
3. The proposed structure will be founded at 144.4 and will be above the predicted flood height.
4. Predicted velocities in and around the proposed development are within a range that will ensure excessive scouring and de-stabilisation of earth embankment will not occur. That said, vegetation of this area is highly recommended to minimise any potential impacts.
5. Given the nominal increase in the flood height the cumulative impacts on other developments within the flood prone areas is deemed negligible primarily due to:
· The small potential increases in flood heights
· The width of the flood plain and hence the ability of the flood plain to absorb future reducing in flood plain storage
· The flood extents on the outskirts especially Sydney Street are remaining relatively unchanged i.e. the area of land that is inundated by floodwater will remain similar to current levels.
In response to the flood risk, a filled building pad (1.0-1.5 metres above natural ground level) is proposed at the rear of the site to maintain a finished floor level for the proposed building at the 1:100 year flood level (RL 144.4 AHD). The access driveway is also proposed to be raised 500mm - 800mm above natural ground level. Community Infrastructure have reviewed the Flood Assessment Study and concluded that the access driveway has the potential to obstruct the natural flow path of floodwater through the site during a 1:20 year flood event and they have recommended that the driveway be lowered to natural ground level, to maintain the natural flow of flood water across the site. In addition Community Infrastructure has recommended that a secondary emergency access should be provided to the north of the Telstra Depot which would be trafficable when the main access is flooded and a Flood Evacuation Plan is also to be prepared for the development. These additional requirements are satisfactory to the applicant and have been included as conditions of consent."

Conclusion

  1. Having considered the evidence, submissions and undertaken a view, I initially acknowledge that appropriate dual occupancy development is permissible within the R1 General area that applies throughout the Shire. However any such development should reasonably satisfy the MLEP objective:

"To ensure that development is carried out in a way that is compatible with the flood risk of the area".

  1. Furthermore, any such development should satisfy the objectives of the MDCP, which include to:

"Inhibit the intensification of residential and other inappropriate uses in flood affected areas."

  1. From the engineer's evidence, I note their initial agreement to the recent flood modelling that the subject land is subject to high hazard flooding from the Hunter River (Runner B) and the Sydney Street (Runner A), see Figure 1. I also consider it appropriate to rely on this agreed modelling as an appropriate basis for assessment of the current merits of the proposal.

Figure 1 Velocity-Depth Mapping showing the alignment of Flood Runners at Peak of the Design 1% AEP Flood

  1. The consequence of these two flood runners is that there is there is an area of 'low flow island', or designated "red line" area marked on Exhibit 9, in the vicinity of the proposed building footprint, which was differently delineated by the engineers. From my consideration of the evidence, I consider it more appropriate to rely on Mr Thomas's smaller red line area because:

  • I consider it is based on a better interpolation of the slower floodwater velocity range of 0.4 - 0.7 m/s vectors, together with a provisional depth of 0.7m.
  • Mr Thomson's comparatively larger area includes more of the 1.2 - 1.4 m/s vector range adjacent to the river (at 0.3m depth), which I do not consider is consistent with the MDCP flood storage definition. It also includes more of the area 0.8m/s at 1m depth near the front of the property fronting Sydney Street, which again I do not consider adequately satisfies the following MDCP definition for 'Flood Storage Area'
Flood Storage Area means those parts of the floodplain which are used for the temporary storage of floodwater during the passage of a flood (my emphasis).

  1. For the hazard assessment, I note that the engineers referred to the provisions of the FDM for hydraulic and hazard categorisation. I accept that these classifications are primarily for strategic planning and not recommended for isolated development assessments. However the definition of 'high hazard' in the MDCP is quite similar to the same definition in Appendix L of the FDM and therefore a useful reference.

  1. Also, relevant information is provided in the FDM dealing with 'Islands' as follows:

G9.5 Islands
The formation of islands in the floodplain during a flood is a potentially dangerous situation. This is especially so when floods larger than the flood used to derive the FPL totally inundate the island (see Figure G1). People trapped on the island and their rescuers will be placed at undue risk. Thus, the development of land that becomes isolated prior to ultimate inundation needs to be considered with great care.

  1. Another principle expressed in the FDM is a range of flooding events should be investigated to assess the flood behaviour. I then think these factors indicate that a cautious approach should be undertaken. On this basis, Mr Thomas' concern that in flood events rarer than the 1% AEP the "island" area would be reduced and the whole site would effectively result in the property being categorised as a high hazard floodway is relevant.

  1. In the particular circumstances, I think the classification of the LFI as 'flood storage area' by Mr Thomson at the building footprint, but surrounded by high hazard floodway, may of be of technical significance, but nevertheless the more important consideration is the practical risk to life and property consideration.

  1. In my assessment there is an unacceptable level of risk because:

  • The new dwelling is to be erected some 1.5m above the natural ground level and in the event of evacuation residents would have leave via Sydney Street through a high hazard area.
  • Even though the warning time is in the order of 7 hours, residents would need to be aware that the flooding will first enter the property from Sydney Street, not the river and if departure is delayed, then evacuation will be compromised.
  • If the evacuation is required in the dark, then some particular arrangements should be made. No such details were provided to the Court and the submission that this could left for a condition of consent requiring some subsequent "evacuation plan" is unacceptable to the Court, considering the matters that would need to be addressed, including those listed in cl 1.6.7 of the FDM.
  • In any case, such a condition that evacuation relies on a private plan seems contrary to SES practice.
  • The alternative design approach of a "shelter in place" design to avoid evacuation was not detailed to the Court and I give this little weight as a realistic option.

  1. For these reasons, I then rely on the engineering evidence of Mr Thomas that the effect of the flood runners, which are categorised as high hazard floodways, and which surround the site, is that they influence the hydraulic category of the land in question. Therefore I consider the site should be classified as "high hazard floodway".

  1. As such, the proposal is not consistent with the MDCP objective to inhibit or restrain intensification of residential development, in this high hazard floodway.

  1. Furthermore, I do not consider the proposal to allow a new residential unit to be constructed within the floodway is consistent with the compatibility with the flood risk considerations, stated in the objectives of the R1 zone.

  1. Insofar as other issues were discussed, I am satisfied that the examination of the planners revealed that there are some 17 - 20 other similar properties whose owners may be interested similar applications. Based on the current policy information, it would seem that the cumulative effect of such approvals would unlikely result in a positive safety risk outcome but I give this little weight because each application would be considered on its merits.

  1. Also, I give little weight to the recently approved 'rural supplies business and veterinary hospital within the floodplain area because it is in a different zone and different category of development. As no specific flooding details were presented to the Court, I do not consider its approval in the rural zone establishes any precedent for the subject proposal.

  1. In summary then I give these matters little weight considering the subject application does not merit consent because it is effectively and practically located within a high hazard floodway and does not satisfy the relevant MLEP and MDCP aims and objectives for appropriate development within the floodplain.

Court orders

  1. The Court orders that:

(1)   The appeal is dismissed.

(2)   Development application No 162/2012 for the installation of a manufactured home to create a detached dual occupancy at 119 Sydney Street, Muswellbrook is refused.

(3)   The exhibits may be returned except A, 1, 7, 8 and 9.

R Hussey

Commissioner of the Court

Amendments

13 August 2013 - Figure 1 note added


Amended paragraphs: 42

13 August 2013 - Image resized


Amended paragraphs: 42

Decision last updated: 13 August 2013

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