Ko v Strathfield Municipal Council

The proposed development and the proposed flood mitigation measures

1. The proposed development comprises a basement level and two storeys above. The basement level contains two car spaces, a turning bay, services room, a cellar and a stairwell leading to upper floors. The basement level is proposed to be at 20.45 AHD, which is below the 1% AEP level.
2. The ground level contains a home office, bedroom, bathroom, cellar, living and dining areas, laundry, kitchen with walk-in-pantry, centralised garden courtyard, and outdoor alfresco area. The ground level is proposed to be at 23.15 AHD, which is above the level for the 1% AEP plus 500mm freeboard.
3. The first floor contains the master bedroom with a walk-in-robe, rumpus room, three bedrooms, study nook, ensuite and front-facing balcony and two bathrooms.
4. The proposed development seeks to mitigate the impact of floodwaters on the basement level by proposing a driveway crest, or hump, that is at the 1% AEP level. It then relies on a 500mm high self-closing flood barrier at the basement entrance to prevent the entry of water into the basement. In support of these proposed design measures, the proposed development relies on a Flood Assessment Report dated 25 December 2020 and amended on 14 January 2021.

The planning framework

1. Section 4.15(1)(a) of the EPA Act requires the Court, in exercising the functions of the consent authority, to consider the provisions of any applicable environmental planning instrument, development control plan, planning agreement, and regulations. Amongst other things, s 4.15(1) also requires consideration of the likely impacts of the development, the suitability of the site for development, any submissions made, and the public interest.
2. The site is zoned R2 Low Density Residential under the Strathfield Local Environmental Plan 2012 ("SLEP 2012"), and dwelling houses are permissible in the zone. Clause 2.3 of the SLEP 2012 requires that the objectives of the zone be considered in determining an application for development consent in the zone. The objectives are as follows: • To provide for the housing needs of the community within a low density residential environment. • To enable other land uses that provide facilities or services to meet the day to day needs of residents. • To ensure that development of housing does not adversely impact the heritage significance of adjacent heritage items and conservation areas.
3. Pursuant to cl 4.3 of the SLEP 2012, the applicable maximum building height development standard is 9.5m. Pursuant to cl 4.4C, the applicable maximum floor space ratio ("FSR") development standard is 0.625:1. The proposed development complies with both the height and FSR development standards.
4. Clause 6.3 of the SLEP 2012 applies to land at or below the flood planning level, and prevents development consent from being granted unless the Court, exercising the functions of the consent authority, is satisfied of certain matters. It provides as follows: 6.3 Flood planning (1) The objectives of this clause are as follows - (a) to minimise the flood risk to life and property associated with the use of land, (b) to allow development on land that is compatible with the land's flood hazard, taking into account projected changes as a result of climate change, (c) to avoid significant adverse impacts on flood behaviour and the environment. (2) This clause applies to land at or below the flood planning level. (3) Development consent must not be granted to development on land to which this clause applies unless the consent authority is satisfied that the development - (a) is compatible with the flood hazard of the land, and (b) is not likely to significantly adversely affect flood behaviour resulting in detrimental increases in the potential flood affectation of other development or properties, and (c) incorporates appropriate measures to manage risk to life from flood, and (d) is not likely to significantly adversely affect the environment or cause avoidable erosion, siltation, destruction of riparian vegetation or a reduction in the stability of river banks or watercourses, and (e) is not likely to result in unsustainable social and economic costs to the community as a consequence of flooding. (4) A word or expression used in this clause has the same meaning as it has in the Floodplain Development Manual (ISBN 0 7347 5476 0) published by the NSW Government in April 2005, unless it is otherwise defined in this clause. (5) In this clause - flood planning level means the level of a 1:100 ARI (average recurrent interval) flood event plus 0.5 metre freeboard.
5. Part A of the Strathfield Consolidated Development Control Plan 2005 ("SCDCP") applies to the proposed development. It applies a storey control to residential dwellings, at Section 4.2.2 at clause 7, which states "Dwelling houses and any ancillary structures are to be no more than two (2) storeys high". Clause 5 of the same section limits the internal floor to ceiling height to a maximum of 3m for any residential level.
6. Section 8.2.3 of Part A of the SCDCP concerns basement vehicle access and parking. It requires that the maximum height of the basement above natural ground level is to be 1m, and that any protrusion above 1m results in a storey that is counted towards the storey control (referred to above). Specifically, it states: "3. Where a basement is proposed, the maximum height of the basement above natural ground level measured to the floor level of the storey immediately above is to be less than 1 metre. Where the basement protrudes above ground level by more than 1 metre, it does not comply with the SLEP 2012 definition of a basement, it will be considered as a storey and the gross floor areas excluded within a basement under SLEP 2012 do not apply and will be included in the floor space ratio. Basement protrusion of more than 1 metre will generally not be accepted especially if it is considered to adversely impact the bulk and scale of the dwelling and may require the setback of the upper level."
7. With respect to flood affected sites, clause 9 of Section 8.2.3 states: "Basements may not be permissible on flood affected sites. Applicants should check with Council and consider submitting a pre-lodgement application."
8. Section 10 within Part A of the SCDCP concerns stormwater management and flood prone areas. The following controls apply: "10.2.1 Stormwater Management and Flood Prone Areas 1. Applicants seeking to develop on lands identified as flood prone are advised to contact Council before designing their proposal. 2. Developments shall comply with Council's Stormwater Management Code. On site detention devices may be required to assist in the management of stormwater on site. 3. Flood affected properties must comply with Council's Interim Flood Prone Lands Policy (Flood Prone Areas and Through Site Drainage). 4. Where a site is subject to flooding applicants should seek written advice from Council's Planning & Environment section in relation to minimum habitable floor height for the site. 5. In areas subject to major overland flow from adjoining properties, applicants are required to engage a suitably qualified hydraulics engineer and lodge a drainage/flood report prepared by a hydraulics engineer. 6. Applicants must comply with Council's Stormwater Management Code with regard to drainage and stormwater detention matters. Full details and plans of the stormwater system are to be submitted for approval as part of the development application."
9. The Council's Interim Flood Prone Lands Policy sets out the following mandatory requirements: "1. All applicants must demonstrate that the development will not cause any increased impact on overland flow paths. It may be necessary to provide a report from a suitably qualified hydraulic engineer demonstrating that a particular proposal complies with this requirement. 2. All developments must be designed so that habitable floors are at least 500mm above the 1 in 100 year flood level and non-habitable floors are no lower than the 1 in 100 year flood level. However, the fact that a development is designed to comply with the floor levels does not guarantee approval unless it can be demonstrated that there will be no adverse impact on the overland flow paths. 3. An exception to the heights in 2 above may be granted in each particular case for minor extensions to an existing building having regard to the size, area and type of extension and the floor levels of the existing building."
10. The Council also has in place a Stormwater Management Code, which is required to be complied with, pursuant to clause 6 of Section 10.2.1 of the SCDCP. Clause 4.10 of the Stormwater Management Code states the following: "4.10 Studies / Analysis In situations where flooding problems have occurred, or there is a risk of such occurrence, a flood study or drainage system analysis of the catchment containing the development / building site will be required. Where such a study is to be carried out, the calculation methods required to demonstrate satisfactory treatment of the development will generally be in accordance with current practice as outlined in Australian Rainfall and Runoff (1987), and subject to the satisfaction of Council's Director Operations."

The expert evidence

1. The Council raised a contention, in its Amended Statement of Facts and Contentions, that the basement car park protrudes more than 1m above the natural ground level, which is considered a storey and results in a breach of the storey control. Evidence on this issue, and on an issue concerning the minimum headroom for the basement, was given by Mr Miguel Rivera, a town planner employed by the Council, and Mr Mark Boutros, a town planner engaged by Ms Ko.
2. Mr Rivera and Mr Boutros agree that conditions of consent can be imposed to resolve concerns relating to the basement protrusion, and to ensure that the basement meets the required headroom and will not be used for habitable purposes. They agree that the appropriate conditions of consent would require the living and the dining room on the ground floor of the dwelling house to be modified to have a maximum finished floor level of 23.00 RL, and for the basement level not to be used for habitable purposes.
3. The expert opinion evidence concerning the flood risk and the flood mitigation measures was given by Mr Richard Dewar, an engineer engaged by the Council, and Mr Pavel Kozarovski, an engineer engaged by Ms Ko.

Evidence on the impact of flooding

1. Mr Kozarovski opines that the subject site is flood free and that the proposed driveway hump and the flood barrier will be sufficient to provide the required protection for the basement garage.
2. Mr Kozarovski prepared the Flood Assessment Report relied upon in support of these measures, in which he concludes that the subject site is flood free. He reaches this opinion based on carrying out modelling in HEC-RAS, which simulated the flood behaviour in what he considers a typical kerb and gutter flow environment. To carry out that modelling, Mr Kozarovski utilised the actual levels of the kerb on Oxford Street, which he considers reflect the current site conditions, rather than what is contained in the flood study. He also incorporated the existing double brick fences into the model, including the brick fence along the rear boundary of the site, and the length of its continuation between 53 and 55 Oxford Street. He certifies that these walls are "more than capable to withstand the forces of flowing water, debris and buoyancy during the 1% AEP flood" (Ex 4 p 4).
3. As a result, the model shows that the site is "flood free with the exception of the small area in the North Western corner with a maximum depth of inundation of 5mm" (Ex 4 p 15).
4. Based on this modelling, Mr Kozarovski's evidence is that the resulting flood levels in the vicinity of the driveway ramp are 200mm lower than those calculated in the flood study. As such, the proposed driveway crest creates a 200mm freeboard above the 1% AEP flood level, which he considers to be adequate.
5. Mr Kozarovski also gave evidence that if the brick walls were removed from the modelling, in a 1 in 100 year flood event, over a period of 5min two thirds of the site would be inundated to levels of between 1 and 20mm.
6. Further, leaving this modelling aside and relying on the levels in the flood study, Mr Kozarovski opines that the proposed driveway ramp crest is sufficient to meet the intent of the control in the interim policy, which requires that "non-habitable floors are no lower than the 1 in 100 year flood level". In addition, he considers that the proposed flood barrier and the walls would provide an additional freeboard of 500mm. He points to J4.6 of the NSW Floodplain Development Manual 2005 as there being acceptance of flood gates as a means for flood management.
7. Mr Kozarovski also relies on the stormwater concept drainage plan to ensure that any surface runoff entering the site from the south is intercepted by a series of pits and grates and dispose into the existing pit in Heyde Avenue, and all roof water is collected in the below ground rainwater tank, which will overlflow to the kerb and gutter in the street.
8. On the other hand, Mr Dewar opines that the modelling relied upon by Mr Kozarovski to conclude that the subject site is flood free relies on brick walls that are not located on the subject site. Mr Dewar's evidence is that, whilst a double brick wall is unlikely to fail, engineers cannot rely on them remaining in place in a flood unless they have been designed and constructed to withstand the appropriate flood and debris loads. Mr Dewar noted at the site inspection that the brick fence between 53 and 55 Oxford Street had some cracking and was held up by bracing, which he opines could be a sign that the wall had been considered to be at risk of failing. Further, Mr Dewar points out that fences can be replaced without a development application and the fence could be replaced in the future with a fence with different hydraulic properties. He also notes that the construction of the brick fence has caused an adverse impact, contrary to the Council's Stormwater Management Code, by diverting runoff from its original path onto another property and has not preserved the surface flow paths. He therefore considers that the construction of the brick fences was not in accordance with the current guidelines, and, if replaced, would be constructed in accordance with those guidelines, causing runoff to flow across the subject property.
9. Further, Mr Dewar's evidence is that the mechanical solution in the form of flood barriers is not acceptable. His evidence is that there is no long term history of the use of flood barriers in NSW to see how they perform over time. He also opines that they are not a fail safe method for flood protection in a dwelling, in circumstances where cars can stop the gate lifting, the gates can be damaged or poorly maintained over time, or can be removed by subsequent property owners. His evidence is that whilst they have been installed for flood management in pre-existing structures, where no other means of flood management is available, they are not appropriate in new builds where a design above the flood planning level can be achieved.
10. Mr Dewar therefore opines that the best way to protect the dwelling is to include a driveway crest that is of a height above the flood planning level, that is, at a level that is 500mm above the 1 in 100 year flood level. His evidence is that this is a raised hump that is a "simple fail safe solution which can be incorporated into the design of a new build and likely for less cost than a gate." He considers that a hump requires no maintenance and is unlikely to be removed by subsequent owners.
11. Mr Dewar's evidence is that the proposed crest or hump at the 1 in 100 year flood level, as proposed, is not sufficient to prevent risk to life. His evidence is that, with water entering the basement in a 1 in 100 year flood, there is a risk to life with residents entering the basement to try to move vehicles from the basement to prevent damage.
12. Mr Dewar further notes that whilst the Interim Flood Prone Lands Policy allows for non-habitable floor levels to be built above the 1 in 100 year flood level (without a requirement for 500mm freeboard above that level), he considers that the terms of the policy do not contemplate the increasing number of dwellings with basement car parking. His evidence is that the policy differs from current practice, where other councils have updated their policies to reflect that basement garages need to be built with a 500mm freeboard above the 1 in 100 year flood level.
13. Mr Dewar also disputes the 1 in 100 year flood level of the basement driveway. Whereas Mr Kozarovski's evidence is that the level is taken from mid-way between the two points on the flood map that correlate with the driveway edges, resulting in a 1 in 100 year flood level of 22.1 AHD, Mr Dewar's evidence is that it is necessary to take the flood level at the higher of the contours, at the south-western point of the driveway at the boundary, which is 22.3784 AHD (Ex 4 p 8 Figure A.1). His evidence is that this level takes into account the direction of the flow of the floodwaters in a 1 in 100 year event. The consequence of Mr Dewar's evidence on this point is that the driveway crest, which is at 22.1 AHD, is below the 1 in 100 year flood level.

The town planning impact of increasing the driveway crest

1. If an increase to the driveway crest created an increase to the floor levels of the dwelling, Mr Rivera and Mr Boutros agree that this will cause an increased protrusion of the basement that will mean that it is counted as a storey, and a consequential breach of the storey control. Whereas Mr Boutros opines that a technical breach may not be of concern, Mr Rivera opines that there ought not be any breach of the storey control due to the adverse visual impact that would be occasioned.

The appropriateness of the flood risk measures

1. As set out above, the site the subject of the proposed development is "at or below the flood planning level" within the meaning of cl 6.3(4) of the SLEP 2012. In exercising the functions of the consent authority, the Court is precluded from granting development consent to the proposed development unless it is satisfied of the matters set out in cl 6.3(3) of the SLEP 2012. This includes that the development "is compatible with the flood hazard of the land" (subcl (3)(a)), and "incorporates appropriate measures to manage risk to life from flood" (subcl (3)(c)).

The applicant's position on flood management

1. Ms Ko's position is that the subject property is not affected by overland flooding, that the proposed development provides an effective solution capable of managing flood risks through the crest in the driveway at the 1 in 100 year flood level together with the site drainage, and that a self-closing flood barrier is an effective way to manage flood waters and mitigate risks.
2. In support of her position, Ms Ko relies on the Flood Assessment Report by Mr Kozarovski. The authorised agent for Ms Ko, Mr Raithby, submits that the modelling in that report more accurately reflects the site conditions and the resulting flood levels. Mr Raithby relies on Chapter 1.5 of the Flood Study, in which it is acknowledged that depth estimates and design flood levels "may change if more accurate field survey is obtained". On the basis of this report, Ms Ko submits that there will be no overland flow on the site. Further, Ms Ko relies on the evidence of Mr Kozarovski that if the fences were excluded from the modelling, the possibility of overland flow is very minimal.
3. Ms Ko also submits that, in relation to the flood modelling that has been carried out, the Court should prefer the evidence of Mr Kozarovski on the basis that "Mr Dewar's demeanour throughout the proceeding and reluctance to review facts in the modelling, demonstrates his partiality as the primary author of the flood study" (written submissions filed 15 February 2021, p 5).
4. Ms Ko also submits that the Council has been inconsistent in its approach to flood planning. She says that this is evident from the various basement garages in the vicinity of the site, and from the initial design solution put forward by the Council for a driveway crest that is 300mm above the 1 in 100 year flood level. She submits that Mr Dewar's evidence that a crest that is 500mm above the 1 in 100 year flood level (i.e. at the flood planning level) is not supported by the Interim Flood Prone Lands Policy, which contains no such requirement and only requires non-habitable floors to be at the 1 in 100 year flood level.
5. In light of the terms of the Interim Flood Prone Lands Policy, Ms Ko submits that a crest at the 1 in 100 year flood level is sufficient and that any flooding over that level will be minimal and can be dealt with by site drainage. In support of this submission, Ms Ko relies on Mr Kozarovski's evidence that a 1 in 100 year flood event over a period of 5 minutes will cause a flood level of up to 50mm within the basement level. Ms Ko says that this is a flood level that is low risk and can be dealt with by site drainage.
6. Additionally, Ms Ko submits that the self-closing flood barrier is an acceptable solution for flood mitigation and is an appropriate measure to manage risk to life from flood. Ms Ko points out that Mr Dewar accepts that flood gates are an acceptable means of flood management for existing structures, and that he has not provided real life examples of failure to support his opinion that they are not fail-safe. Ms Ko relies on the decision of the Court in Our Lady Aged Care Centre Ltd v City of Parramatta Council [2020] NSWLEC 1596, in which flood gates were approved. She submits that this means flood gates were considered an acceptable means of flood management for an aged care centre.
7. Ms Ko therefore submits that, as the proposed development area remains flood free in the 1 in 100 year flood event, as any flooding arising from climate change or fence modification would be dealt with by site drainage, and where the only area potentially affected by flood water is non-habitable, the site is low risk. Accordingly, in these circumstances, she submits that the proposed development is compatible with the flood hazard of the land and the Court can be satisfied of the matters in cl 6.3(3) of the SLEP 2012.

The Council's position on flood management

1. The Council submits that the site is not suitable for basement car parking in a R2 zone on flood prone land, as it increases risk to life and property and is not compatible with the flood hazard of the land. As such, the Council submits that the Court cannot reach the mandatory satisfaction of the matters in cl 6.3 of the SLEP 2012.
2. In considering the flood levels for the basement driveway, the Council submits that Mr Dewar's calculated flood level should be preferred to that of Mr Kozarovski's. The Council submits that Mr Dewar's evidence that it is appropriate to take the higher of the contours, rather than the average, should be preferred as it identifies the highest flood level affecting the site and adopts a precautionary approach to determining flood impact on the development and the immediate environment. Although the Council's written submissions rely on Figure 6 of Ex 4 for the flood levels, on the dispute concerning the appropriate 1 in 100 flood level the evidence of Mr Dewar and Mr Kozarovski was taken from Figure A.1 (Ex 4 p 8).
3. The Council also submits that the modelling by Mr Kozarovski concerning the flood levels of the site cannot be relied upon. Although the experts agree that the position of the brick fence could act as a flood barrier to overland floodwaters entering the property from the side and rear of the site, the Council points out that this does not address the floodwaters entering the basement from the direction of the road. The Council submits that the brick wall cannot be relied upon as a permanent and fail-safe flood barrier, given that its construction and integrity is not known, it was likely built in the 1960s and therefore not subject to current planning controls, and it can be removed without requiring the approval of the Council. Further, the Council submits that allowing reliance on the modelling results in a lower flood planning level for this site, which does not assist in achieving consistent planning decisions for the locality.
4. In addition, the Council submits that the freeboard of 500mm is required given the differences between modelled flood levels and actual surveyed flood levels on flood-affected sites during flood events. It relies on Table 22 of the Flood Study, which provides examples of the discrepancy between modelled results and actual flood levels. The Council says that this comparison gives further clarification on the purpose of the 500mm freeboard, which is to act as a buffer to allow discrepancies in modelled levels as well as other variables that cannot feasibly be factored into the models.
5. The Council's position is also that the flood planning level is clearly defined in cl 6.3 of the SLEP 2012 as "the level of a 1:100 ARI (average recurrent interval) flood event plus 0.5 metre freeboard", and that, given the impact of climate change, the likelihood of flood levels at and above the 1:100 ARI is statistically an event that will occur with more frequency in the future. The Council therefore says that the driveway should be built to the flood planning level as the absolute minimum appropriate measure to manage risk to life. It relies on the evidence of Mr Dewar, who opines that the driveway crest should be built to the flood planning level.
6. The Council points out that the level of the basement does not comply with the Interim Flood Prone Lands Policy, which requires non-habitable floors to be above the 1 in 100 year flood level, and therefore does not comply with Section 10.2.1 of the SCDCP. The Council submits that the self-closing flood barriers are not an appropriate alternative solution on the basis that there is no evidence for their performance in NSW over time and they are not a fail-safe method of flood protection in circumstances where parked cars and poor maintenance can lead to failure. Whereas flood barriers have been considered appropriate in other circumstances, the Council submits that they are not an appropriate solution in low density residential zones where appropriate design and engineering can adequately address the flood risk.
7. The Council submits that in the absence of appropriate flood protection, there is a risk to life by residents seeking to enter their cars during flood events with the purpose of removing them from the basement to protect them from flood damage.
8. The Council made other submissions, including that Ms Ko did not meet with the Council pursuant to the provisions of the SCDCP. Those submissions are not relevant to my consideration.

The proposed flood mitigation measures are not adequate

1. In considering whether it is satisfied of the matters in cl 6.3(3) of the SLEP 2012, the Court's focus is on the acceptability of the proposed development and the associated flood mitigation measures, and not on whether a better, alternative proposal for flood mitigation, such as the increased crest to the level proposed by Mr Dewar, should be pursued.
2. The applicant, Ms Ko, bears the persuasive burden of satisfying the Court of the matters set out in cl 6.3(3) of the SLEP 2012. As explained by Preston CJ in Australian Protein Recyclers Pty Limited v Goulburn Mulwaree Shire Council [2006] NSWLEC 641 at [2], "an applicant for development consent always bears a persuasive burden of proof: the applicant must persuade the consent authority, whether it be the council at first instance or the Court on appeal, that development consent ought to be granted."
3. For the following reasons, I find that the persuasive burden of satisfying the Court of the matters set out in cl 6.3(3) of the SLEP 2012 has not been discharged, and, similarly, that the proposed flood control measures do not meet the objective in the WCDCP to "appropriately manage stormwater and overland flow to minimise damage to occupants and property" (Section 10.1(G)).
4. Firstly, the modelling in the Flood Assessment Report by Mr Kozarovski cannot be relied upon to consider the future flood risk, as it relies on the ongoing presence of a brick fence that is not located on the subject site. The modelling includes both the fence along the rear of the property, as well as its continuation beyond the site and between numbers 53 and 55 Oxford Street. Although the brick fence along the rear of the property could remain in situ and be protected by a condition on the consent for the proposed development, there is no method by which the brick fence between numbers 53 and 55 could be required to be retained into the future. As Mr Dewar points out, the fence can be replaced by a more permeable structure as exempt development. Given that the modelling in the Flood Assessment Report relies on that brick fence remaining in situ in a flood, I cannot accept the conclusion within the report that the site is flood free. For the same reason, I cannot accept Mr Kozarovski's evidence that the flood levels in the vicinity of the ramp are 200mm lower than those in the flood study, as that evidence is similarly based on the modelling that includes the walls. Although that modelling reflects the existing site conditions, the fact that it relies on structures that may not remain in situ means that it cannot be relied upon to determine the flood risk and adequacy of flood mitigation measures into the future.
5. Secondly, the proposed development does not comply with the applicable controls concerning the floor level for the basement garage. As set out above, Section 10 within Part A of the SCDCP (at clause 3 of 10.2.1) requires flood affected properties to comply with the Council's Interim Flood Prone Lands Policy, which requires development to be designed such that non-habitable floors are no lower than the 1 in 100 year flood level. In the area near the basement entrance, the 1 in 100 year flood level is (around) 22.5 AHD, and the finished floor level of the basement is proposed to be 20.45, and therefore does not meet this requirement.
6. In the absence of compliance with the policy, which means that the standard in the SCDCP is not met, s 4.15(3A)(b) of the EPA Act requires that the Court, in exercising the functions of the consent authority, "be flexible in applying those provisions and allow reasonable alternative solutions that achieve the objects of those standards for dealing with that aspect of the development." The relevant objects of clause 3 of 10.2.1 are contained in Section 10.1, and include the following: "A. To encourage the incorporation of Water Sensitive Urban Design (WSUD) and Botany Improvement Plan principles in the development. B. To ensure compliance with Council's Stormwater Management Code. C. To ensure compliance with the NSW State Government's Flood Prone Lands Policy. D. To ensure that appropriate soil erosion and sediment control measures are implemented on all sites that involve soil disturbances during construction. E. To ensure new building work does not detrimentally affect the existing drainage system of any area of the Municipality. ... G. To appropriately manage stormwater and overland flow to minimise damage to occupants and property."
7. Thirdly, I am not satisfied that the mechanical solution in the form of the self-closing flood barriers is an appropriate means to protect the basement from flood water. I accept the evidence of Mr Dewar that self-closing flood barriers are not a sufficiently failsafe method for flood protection in a dwelling, in circumstances where parked cars can stop the gate lifting and the gates can be damaged or poorly maintained by residents or occupants over time. Due to these potential problems, there is a risk that the flood barrier would not be in a ready and functional state in the unexpected and infrequent event of a flood. As such, I accept the Council's submission that reliance on a mechanical solution is not appropriate in the circumstances.
8. The fact that flood barriers have been used in other locations is not sufficient to satisfy me that the above described risks do not arise. Each application must be considered on its own merits, and the consideration will change depending on the applicable flood planning level and the associated flood risk. The decision in Our Lady Aged Care Centre Ltd v City of Parramatta Council provides no guidance on the general appropriateness of flood barriers, as the decision concerned a modification application and did not concern the appropriateness of flood gates. The proposed development can nevertheless be readily distinguished from that considered in Our Lady Aged Care Centre Ltd v City of Parramatta Council given that each concern a different catchment, different flood planning levels and different flood management policies.
9. Further, the use of flood barriers for the protection of an entrance to a dwelling, including the basement garage entrance, is beyond the scope of their contemplated and described use in Section J4.6 of the NSW Floodplain Development Manual 2005, which is to "control flow down a bypass floodway, or to prevent flow along a small creek or drain or other waterway".
10. Fourthly, this means that the flood protection for the basement is the driveway crest, which is at 22.1 AHD, as well as the site drainage. There are two reasons why this is not adequate to satisfy me that this is appropriate to manage risk to life from flood, or that it will appropriately manage stormwater and overland flow to minimise damage to occupants and property. The first reason is that there is insufficient information in support of the stormwater plan (Ex C) to demonstrate the flood levels that the site drainage can accommodate. Exhibit C shows a grate along the driveway at the entrance to the basement, which drains to a pump well which then appears to discharge to flush points. Having reviewed the Flood Assessment Report and the other documents in evidence in the proceedings, there is no information on what flood occurrence and volumes (and rate of flow) the system is designed to accommodate. The second reason that the crest and site drainage is not adequate is that I accept the evidence of Mr Dewar that to calculate the 1 in 100 year flood level it is necessary to take the flood level at the higher of the contours in the area of the driveway, at the south-western point of the boundary, which is 22.3784 AHD (Ex 4, p 8, Figure A.1). This is due to the direction of the flow of the floodwaters, as well as the fact that taking an average does not actually prevent the entry of floodwaters from the higher flood level. Accordingly, the proposed crest level of the driveway is below the 1 in 100 flood level.
11. As such, water will enter the basement in a flood event that occurs more often than the 1 in 100 year event. I accept the evidence of Mr Dewar that this creates a risk to life, as residents enter the basement to try to move vehicles to prevent damage. It also creates a risk to property, given that there are cars, storage and a cellar contained in the basement.
12. I also consider that, contrary to the submission made on behalf of Ms Ko, there was nothing about Mr Dewar's demeanour that would cause me to conclude that his evidence was partial. Mr Raithby, the agent for the applicant, cross-examined Mr Dewar. His questions were often unclear and compounded in a manner that made it difficult to discern what question was being asked. Nevertheless, the cross-examination did not lead Mr Dewar to change or modify his expert testimony, and instead he was able to provide further information to substantiate his opinion.
13. For the reasons set out above, I cannot be satisfied that the driveway crest, the flood barriers and the site drainage, are sufficient to meet the objective in the SCDCP to "appropriately manage stormwater and overland flow to minimise damage to occupants and property" (Section 10.1(G)). Accordingly, the alternative solution provided by Ms Ko, in lieu of compliance with the requirement to build the non-habitable floor at the 1 in 100 year flood level, does not meet the objects of that requirement and is therefore outside the scope of what is to be allowed by s 4.15(3A)(b) of the EPA Act.
14. Similarly, for the same reasons, contrary to cl 6.3(3)(a) and (c) of the SLEP 2012, I am not satisfied that the basement of the proposed development is compatible with the flood hazard of the land, or that the proposed development incorporates appropriate measures to manage risk to life from flood. Accordingly, cl 6.3(3) precludes the grant of development consent for the proposed development.

The outcome of the appeal

1. As I am not satisfied of the matters set out in cl 6.3(3) of the SLEP 2012, the Court, in exercising the functions of the consent authority, is precluded from granting development consent. The appeal must therefore be dismissed.
2. The Court orders that: 1. The appeal is dismissed. 2. The development application (DA 2020/141) for the construction of a two-storey dwelling house with basement garage at 6 Heyde Avenue, Strathfield, is refused. 3. Exhibits 1-5 are returned.

Amendments 09 March 2021 - Correction to typographical error at [7]. DISCLAIMER - Every effort has been made to comply with suppression orders or statutory provisions prohibiting publication that may apply to this judgment or decision. The onus remains on any person using material in the judgment or decision to ensure that the intended use of that material does not breach any such order or provision. Further enquiries may be directed to the Registry of the Court or Tribunal in which it was generated. Decision last updated: 09 March 2021