MH Property No 2 Pty Ltd v Wollongong City Council - [2024] NSWLEC 1568 - NSWLEC 2023 case summary — Zoe

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MH Property No 2 Pty Ltd v Wollongong City Council

[2024] NSWLEC 1568

Land and Environment Court (NSW)|2023-12-20

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At a glance

Source facts

Court

Land and Environment Court (NSW)

Decision date

2023-12-20

Source

Original judgment source is linked above.

Judgment (46 paragraphs)

[1]

Judgment

COMMISSIONER: The land to the east of the Woonona Bulli RSL Memorial Club (Woonona RSL) has been vacant for some time, and is zoned for medium density residential development. MH Property No 2 Pty Ltd (MH) seeks approval for the development of the land, known as 15 Nicholson Road, Woonona, for multi-dwelling housing containing 26 townhouses over a common basement with 52 residential parking spaces and 7 visitor parking spaces. MH lodged a development application with Wollongong City Council (the Council) on 26 September 2022 for an earlier iteration of what is now proposed. Following the expiry of the period after which a development application is deemed to be refused, MH lodged the present appeal, pursuant to s 8.7 of the Environmental Planning and Assessment Act 1979 (EPA Act).
At the hearing, the Council approved an amendment to the development application pursuant to s 38 of the Environmental Planning and Assessment Regulation 2021 (EPA Regulation 2021). The proposed development, as amended, is for a mix of two and three-storey townhouses across six buildings, with a common basement. The proposed development includes associated landscaping and stormwater infrastructure works, including works to manage overland flow of floodwater.
The Council remains opposed to the grant of development consent. It contends that the proposed development does not maintain the flood function of the land, and will adversely affect flood behaviour and increase the flood risks to other properties. The Council says that the flood modelling carried out by MH is inaccurate, the proposed development does not comply with the relevant controls for development in an area affected by flood, and that it inappropriately seeks to divert floodwater away from the site. The Council also raises a number of other contentions concerning site analysis, stormwater management, inconsistencies between landscaping and flood mapping, and amenity.
For the reasons that are set out below, I consider that the impacts of the proposed development on flooding and flood behaviour are acceptable. The modelling is sufficiently accurate to discern the projected changes to flood behaviour and the proposed development complies with the relevant standards. I find that the piping of some overland flow under Nicholson Road is acceptable in circumstances where the flow will continue to the same receiving catchment with a decrease in peak flows. Further, I find that none of the other contentions warrant refusal of the development application.

[3]

The site and the locality

The site has an area of 6402m2 and a frontage of 41.785m to Nicholson Road. It is legally identified as Lot 101 DP 1279511 and is known as 15 Nicholson Road, Woonona. It is irregular in shape, and partly contains a redundant overflow car park associated with the Woonona RSL, which is located immediately to the west of the site.
The site generally falls away from the western boundary to the east, where there is an open concrete drainage channel along the eastern boundary of the site. Immediately to the west of the channel is a landscaped area, which is separated from the redundant car park by a row of 10 broad leaf paperbark trees. The site has a cross fall of approximately 4m with a significant change of grade of around 2m along an embankment between the trees and the redundant car park area.
The site is burdened by two easements, an easement to drain water that benefits the Council in the location of the open concrete drainage channel, and another to drain water that is 2.8m wide that benefits Woonona RSL (RSL Easement). Within the RSL Easement is an underground pipe running in a general west to east direction, and the water draining through the RSL Easement discharges into the concrete drainage channel. The water then flows into Collins Creek, which conveys water from the escarpment to the beach. The inlet for Collins Creek into which water from the site flows is located to the south east of the site, on the other side of Nicholson Road. The site is affected by flooding in the 1% annual exceedance probability (AEP) event, with three distinct flood flow paths, two of which arise from overtopping flows in the area of the RSL Easement and from the concrete drainage channel.
The site is located on the southern fringe of the Woonona town centre area, with a combination of low and medium density housing types to the north, south and east of the site. Immediately to the south of the site is open space associated with the school grounds of Woonona Public School, which is an item of local heritage. Immediately east of the site towards the frontage is 17 Nicholson Road, comprising of 3 townhouses. On the other side of the concrete culvert is a townhouse development known as 19 Nicholson Road, and the rear yards of some of the townhouses face the concrete culvert.
The subject site is located midway along Nicholson Road, which intersects with the Princes Highway to the west, and transitions to medium and low density residential development to the east.

[4]

The planning framework

The site is zoned R3 Medium Density Residential pursuant to the provisions of Wollongong Local Environmental Plan 2009 (WLEP). The surrounding area to the north, south and east is zoned R2 Low Density Residential. The site of the Woonona RSL is zoned SP3 Tourist.
Multi dwelling housing is a nominated permissible use in the R3 zone. The objectives of the zone are as follows: • To provide for the housing needs of the community within a medium density residential environment. • To provide a variety of housing types within a medium density residential environment. • To enable other land uses that provide facilities or services to meet the day to day needs of residents.
Clause 4.3 of the WLEP imposes a height development standard of 11m for the site, and cl 4.4 of the WLEP imposes a floor space ratio development standard of 0.75:1. The proposed development complies with both development standards, as well as with the minimum site width requirement for multi dwelling housing in cl 7.14 of the WLEP.
The site is within the flood planning area, and therefore cl 5.21 of the WLEP applies. The terms of cl 5.21 were amended by the Standard Instrument (Local Environmental Plans) Amendment (Flood Planning) Order 2023. However, cl 8 of the Standard Instrument (Local Environmental Plans) Order 2006 applies such that the amendments made by the amending order do not apply to a development application lodged prior to its commencement on 10 November 2023. The applicable wording of cl 5.21 of the WLEP is therefore as follows: 5.21 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 flood function and behaviour on the land, taking into account projected changes as a result of climate change, (c) to avoid adverse or cumulative impacts on flood behaviour and the environment, (d) to enable the safe occupation and efficient evacuation of people in the event of a flood. (2) Development consent must not be granted to development on land the consent authority considers to be within the flood planning area unless the consent authority is satisfied the development - (a) is compatible with the flood function and behaviour on the land, and (b) will not adversely affect flood behaviour in a way that results in detrimental increases in the potential flood affectation of other development or properties, and (c) will not adversely affect the safe occupation and efficient evacuation of people or exceed the capacity of existing evacuation routes for the surrounding area in the event of a flood, and (d) incorporates appropriate measures to manage risk to life in the event of a flood, and (e) will not adversely affect the environment or cause avoidable erosion, siltation, destruction of riparian vegetation or a reduction in the stability of river banks or watercourses. (3) In deciding whether to grant development consent on land to which this clause applies, the consent authority must consider the following matters - (a) the impact of the development on projected changes to flood behaviour as a result of climate change, (b) the intended design and scale of buildings resulting from the development, (c) whether the development incorporates measures to minimise the risk to life and ensure the safe evacuation of people in the event of a flood, (d) the potential to modify, relocate or remove buildings resulting from development if the surrounding area is impacted by flooding or coastal erosion. (4) A word or expression used in this clause has the same meaning as it has in the Considering Flooding in Land Use Planning Guideline unless it is otherwise defined in this clause. (5) In this clause - Considering Flooding in Land Use Planning Guideline means the Considering Flooding in Land Use Planning Guideline published on the Department's website on 14 July 2021. flood planning area has the same meaning as it has in the Floodplain Development Manual. Floodplain Development Manual means the Floodplain Development Manual (ISBN 0 7347 5476 0) published by the NSW Government in April 2005.
Clause 7.4 relates to riparian land and prevents the grant of consent unless the consent authority has considered the impact of the proposed development on "the land and any opportunities for rehabilitation of aquatic and riparian vegetation and habitat on that land." The area mapped as riparian land is co-located with the area of the concrete drainage channel near the eastern boundary of the site.
Clause 7.5 of the WLEP concerns acid sulfate soils and applies to the site. The site contains Class 5 Acid Sulfate Soils. However, the proposed development is not expected to lower the water table within the adjacent Class 4 land. The Detailed Site Investigation dated 16 June 2022 includes the results of soil sampling and concludes that soils at the site are not actual or potential acid sulfate soils, and that an Acid Sulfate Soils Management Plan is not required.
The proposed development includes earthworks for the basement and pipe construction, and therefore cl 7.6 of the WLEP applies. It provides: 7.6 Earthworks (1) The objectives of this clause are as follows - (a) to ensure that any earthworks will not have a detrimental impact on environmental functions and processes, neighbouring uses or heritage items and features surrounding land, (b) to allow earth works of a minor nature without separate development consent. (2) Development consent is required for earthworks, unless - (a) the work is exempt development under this Plan, or (b) the consent authority is satisfied the work is of a minor nature. (3) Before granting development consent for earthworks, the consent authority must consider the following matters - (a) the likely disruption of, or any detrimental effect on, existing drainage patterns and soil stability in the locality, (b) the effect of the proposed development on the likely future use or redevelopment of the land, (c) the quality of the fill or of the soil to be excavated, or both, (d) the effect of the proposed development on the existing and likely amenity of adjoining properties, (e) the source of any fill material or the destination of any excavated material, (f) the likelihood of disturbing Aboriginal objects or other relics, (g) proximity to and potential for adverse impacts on any watercourse, drinking water catchment or environmentally sensitive area.
Based on the Geotechnical Investigation Report by Fortify Geotech, dated May 2022 and August 2023, and the Detailed Site Investigation dated 16 June 2022, I have considered the matters in cl 7.6(3) of the WLEP.
The Wollongong Development Control Plan 2009 (WDCP) applies to the site, and contains specific provisions concerning landscaping, floodplain management and stormwater management. Those provisions are outlined in detail below where they are relevant to my consideration of the contentions.

[5]

The resident evidence

The development application was notified between 26 October and 25 November 2022, and an amended application was placed on public exhibition between 12 and 26 September 2023. Written submissions were received in response to both periods of notification. In addition, a number of local residents attended the site view and made oral submissions concerning the proposed development. The issues raised in their written submissions, and in the oral submissions made onsite, can be summarised as follows:

Increased risk of flooding;
Increased risk to safety of flood evacuation;
Traffic congestion and insufficient parking;
Loss of views to the trees and the escarpment;
Privacy impacts;
Tree loss; and
Solar access and overshadowing.

The issues raised concerning flooding and flood evacuation are dealt with in my consideration below. It is notable that the flood modelling for the proposed development demonstrates that adjoining properties to the north and east of the site will benefit from significant flood impact reduction for most storm events, including reductions in flood levels and flood velocity. It is therefore apparent that the proposed development will go some way to resolving existing issues concerning flooding that have been identified by the residents.
Further, the issues concerning traffic, parking, solar access and privacy do not warrant refusal of the development application.
With respect to traffic and parking, the development application is supported by a Traffic Impact Assessment dated 29 August 2022, which concludes that there is adequate parking with a basement car park and visitor car park that is compliant with the relevant standards. Further, the assessment concludes that the additional traffic generated by the proposed development "is considered to be minor and could not be expected to cause any discernible traffic implications, nor result in any safety or operational issues on the surrounding road network" (Ex F, Tab 25, p 10).
With respect to solar access, the Statement of Environmental Effects dated December 2023 concludes that, by reference to the shadow diagrams, the solar access requirements of the WDCP are met so that windows to living rooms of adjoining dwellings will receive 3 hours of sunlight between 9am and 3pm on 21 June, and 50% of the private open areas of adjoining residential properties will continue to receive 3 hours of sunlight between 9am and 3pm on 21 June.
In relation to privacy, the existing boundary fences provide adequate privacy to adjoining neighbours.

[6]

Expert evidence

Expert evidence on flooding and stormwater was given by:

Ms Kylee Smith, a civil engineer with expertise in flooding and hydrology, engaged by MH,
Mr Minh Vu, a civil engineer, engaged by MH, and
Mr Mathew Carden, a stormwater development engineer employed by the Council.

Ms Smith, Mr Vu and Mr Carden gave their evidence in joint reports filed on 4 December 2023, 17 December 2023 and 4 March 2024, and in court at the hearing. They agree that the primary flood function of the site is flood conveyance, including floodway areas and flood fringe areas. They also agree that the proposed development adequately provides for on-site refuge within the dwellings during a probable maximum flood (PMF) event. However, Ms Smith and Mr Carden disagree on the appropriate Manning's coefficients used for flood modelling and whether the site maintains its flood function post-development. Their evidence is considered in more detail below.
Expert evidence on groundwater was given in a joint report by Mr Lee Douglass, an environmental scientist and hydrogeologist engaged by MH, and Mr Karl Batshon, an environmental scientist employed by the Council. They agree that the construction of a tanked basement design would result in no more than minimal harm, such that the contentions concerning groundwater are resolved. They agree that the conditions of consent can impose requirements for the tanked basement design.
Evidence on town planning, design and landscaping was given by:

Mr Brian Bass, an architect engaged by MH,
Mr David Jarvis, an architect and urban designer engaged by the Council,
Mr David Vago, a landscape architect engaged by MH,
Mr John Madry, a landscape architect employed by the Council,
Mr Luke Rollinson, a town planner engaged by MH, and
Ms Kristy Robinson, a town planner employed by the Council.

They prepared a joint report that was filed on 12 December 2023, a supplementary report filed on 4 March 2024, and gave evidence in court. They agree that the proposed communal open space meets the area requirement in the WDCP, and they agree on an appropriate design strategy for the landscaping design of the western swale. These experts also agree that the concerns with respect to setbacks and building separation are now resolved, and that the proposed development complies with the solar access requirements of the WDCP.
The town planners, Mr Rollinson and Ms Robinson, disagree as to whether the proposed development meets the landscaping requirements of the WDCP, and the landscape architects, Mr Vago and Mr Madry, disagree on the deep soil zone calculations and also on whether there is sufficient soil volume in the communal open space to accommodate the proposed planting. Whilst there remained some concerns with respect to privacy and noise issues concerning the use of equipment in areas of the communal open space, it was agreed that this could be addressed by conditions of consent or through the strata management plan. Their evidence with respect to the issues that remain in dispute is considered further below.

[8]

Flood planning framework

The "flood planning area" referred to in cl 5.10 of the WLEP is defined in the Floodplain Development Manual (ISBN 0 7347 5476 0) published by the NSW Government in April 2005 (FDM). It is "the area of land below the FPL and thus subject to flood related development controls".
Flood planning levels, or FPLs, are defined in the FDM as follows: "the combinations of flood levels (derived from significant historical flood events or floods of specific AEPs) and freeboards selected for floodplain risk management purposes, as determined in management studies and incorporated in management plans."
The flood planning level is defined in the WLEP as "the level of a 1:100 ARI (average recurrent internal) flood event plus 0.5 metres freeboard".
In addition to the provisions of cl 5.21 of the WLEP, Chapter E13 of the WDCP contains provisions concerning flood planning and applies "to all floodplains and land below the flood planning level area". Consistent with WLEP, the WDCP defines the flood planning level as "the level of a 1% AEP flood event plus 0.5 metres freeboard, unless otherwise stated in an adopted Floodplain Risk Management Study and/or Floodplain Risk Management Plan".
The objectives of Chapter E13 are as follows: "a) Maintain the existing flood regime and flow conveyance capacity; b) Maintain the function of floodway and flood storage areas; c) Reduce the impact of flooding and flood liability on individual owners and occupiers of flood prone land; d) Reduce private and public losses from flooding; e) Improve public safety with respect to flooding; f) Minimise the potential impact of development and other activity upon the aesthetic, recreational and environmental value of the waterway corridors; g) Increase public awareness of the hazard and extent of land affected by the full range of potential floods; h) Ensure new development must, as far as practical, reduce the existing flood risk, and in no circumstances should the flood risk be worsened; i) Ensure new development (with the exception of waterway crossings) does not encroach within areas susceptible to channel erosion, migration, bank failure and slumping; and j) Deal equitably and consistently with all matters requiring Council approval on flood affected land, in accordance with the principles within the latest version of the NSW Floodplain Development Manual or its update."
At Section 5 of E13, the WDCP requires the preparation of a flood study, and at Section 6.3 it describes the classification of land as either High Flood Risk Precinct, Medium Flood Risk Precinct or Low Flood Risk Precinct. The prescriptive controls for all development are contained in Section 6.4.3, with specific controls in Schedule 8 for the Collins Creek Floodplain. Section 6.4.2 contains the performance criteria, which include the following two relevant criteria: "a) The proposed development should not result in any increased risk to life; b) Development should not detrimentally increase the potential flood affectation on other development or properties either individually or in combination with the cumulative impact of development that is likely to occur in the same floodplain"
Section 6.4.3 then provides the controls, as follows: "6.4.3 Prescriptive Controls a) Appendix C (Schedules 1 - 10) outlines the prescriptive controls that apply to each of the floodplains to which this Plan applies; b) Table 2 provides permissible impacts for various development types for flood events up to the 1% AEP flood; c) Flood impacts in the PMF will be assessed on merit and will consider: i) Impacts to evacuation routes and onsite refuge service levels; ii) Additional flood affected allotments; iii) Flood warning times; and iv) Changes to above yard and above floor flooding. New development must not increase the frequency of over floor flooding for residential, commercial or industrial buildings in a 20%, 1% or PMF event. Additionally, new development must not cause additional lots to be impacted by the 1% or PMF event."
Schedule 8 stipulates that residential uses are an "unsuitable land use" in the High Flood Risk Precinct.
In the Medium Flood Risk Precinct, Schedule 8 applies the following controls for floor levels, building components and structural soundness: Floor Level: "2. Habitable floor levels to be equal to or greater than the 1% AEP flood level plus freeboard." "7. Garage and all other non-habitable internal floor levels to be no lower than the 1% AEP flood level minus 300mm or 300mm above finished adjacent ground (whichever is the greater)." Building Components: "1. All structures to have flood compatible building components below or at the 1% AEP flood level plus freeboard." Structural Soundness: "2 Applicant to demonstrate that any structure can withstand the forces of floodwater, debris & buoyancy up to & including a 1% AEP flood plus freeboard, PMF plus freeboard if required to satisfy evacuation criteria (see below)."
In the Medium Flood Risk Precinct, for flood affectation, Schedule 8 requires compliance with either of the following: "1 Engineers report required to certify that the development will not increase flood affectation elsewhere, includes medium & high density residential proposals. 2 The impact of the development on flooding elsewhere to be considered, includes low density residential."
In addition, the following note is contained in Schedule 8 concerning flood affectation: "Note: When assessing flood affectation the following must be considered: 1. Loss of storage in the floodplain. 2. Changes in flood levels & velocities caused by alteration of conveyance of flood waters."

[10]

Changes to the flood flow paths

On the evidence of Mr Carden, the site is located immediately upstream of "what was historically the confluence between two natural watercourses". On his evidence, these watercourses have been modified over time, "with the north/south oriented watercourse being straightened and formed into a concrete channel, and the east/west oriented watercourse being piped beneath and through the site" (Ex 7, p 4).
Both Mr Carden and Ms Smith agree that the existing conditions include three flood flow paths. The first is along the eastern boundary of the site, from north to south in the location of the open concrete drainage channel. Flooding occurs from overbank flood flows in excess of the capacity of the concrete drainage channel, and the floodway depths outside of the channel can be up to 360mm deep in the 1% AEP event.
The second flood flow path is through the northern portion of the site, which the flood report describes as "breakaway flow from Collins Creek to the northwest" (Ex H Tab 3) and which Mr Carden describes as "a result of an upstream diversion from the north/south oriented watercourse, originating from Campbell Street to the north" (Ex 7, p 6). This flow results in flood depths averaging 175mm but up to a maximum of around 375mm across the northern boundary of the site.
The third flood flow path is from west to east towards the southern portion of the site, which forms shallow sheet overland flow from the west with depths within the order of 30 - 100mm through the centre of the site, flowing to the existing concrete drainage channel via an adjoining property. This sheet flow is partially from overflows of the pipe within the RSL easement. Whilst Mr Carden describes this as a floodway, he concedes that it would only meet the criteria for a floodway in the PMF.
The existing conditions flood depth on the site in the 1% AEP is shown at Figure 1.
The proposed development proposes a series of swales and pipes to manage the second and third flood flow path described above. The flow path from the northwest is proposed to be split around the buildings, with most of the flow conveyed in a southerly and then easterly direction through a new swale along the western boundary. The overland flow path from the west is split between a new underground drainage system that flows south towards Nicholson Road, and a central swale through the site. The proposed development includes an underground pipe along Nicholson Road that discharges to Collins Creek, to convey water that would have otherwise flowed over the site. The design of the ground level drainage plan is shown at Figure 2.
The result is that, in the developed conditions, there is a decrease in flood levels across residential properties upstream of the proposed development site and decreases in flood levels on the neighbouring RSL site. The afflux map at Figure 3 shows the change in flood levels between the proposed developed conditions and existing conditions in the 1% AEP event.
The modelling also shows that the proposed built form is wholly outside of the High Flood Risk Precinct, and that the hazard is mostly H1, with a small portion of H2 in one of the swales and also adjacent to the concrete drainage channel.
Figure 4 shows the change in flood levels between the proposed developed conditions and existing conditions in the 1% AEP event when taking into account rates of rainfall forecasted in the climate change scenario (referred to as 1% AEP climate change), and Figure 5 shows the change in the PMF event.

[11]

Evidence on the changes to flood behaviour

Mr Carden's evidence is that the flood that affects the site is mainstream flooding and not overland flow, and the flood flow paths fulfil a significant flood flow conveyance function which is not maintained by the proposed development.
His evidence that the flood function for the first flood flow path is altered as Building D2 encroaches into the 1% AEP climate change floodway area, which is not compatible with the floodway's function. He notes that, for this flood flow path, the afflux mapping for the 1% AEP climate change scenario shows an increase in flood levels that exceed the permissible flood impacts in Table 2 of Chapter E13 of the WDCP, with flood level increases up to the range of 0.05-0.1m on the adjoining land to the west and increases up to the range of 0.1m-0.25m on the adjoining property to the east. Further, for the third flood flow path, his evidence is that the reduction in width of the PMF floodway through this path causes increase in flood levels on the RSL site, within Nicholson Road and within properties fronting the southern side of Nicholson Road. He refers to the changes to this PMF floodway as a 'blockage' as it diverts floodwaters around the site onto other properties.
On the other hand, the evidence of Ms Smith and Mr Vu is that the proposed development results in stormwater and flooding improvements, as the design flood conveyance is maintained through the site for storm events up to and including the 1% AEP climate change event through a series of swales and underground drainage, with no offsite impacts during those storm events other than a small area of afflux for the 1% AEP climate change event contained in the channel. The flood level increases up to the range of 0.05-0.1m on the adjoining land to the west, raised by Mr Carden, is confined to the RSL car park. Their evidence is that adjoining properties to the north and east of the site will benefit from flood impact reduction for all storm events up to the PMF storm event. Their evidence is that the impacts are within the acceptable tolerance for the 1% AEP, which meets the requirement of the WDCP, and that there are no additional lots affected by the PMF as a result of the proposed development. That is, their evidence is that all lots that will be affected by the PMF in the post development scenario are already affected by the PMF in the existing condition.

[12]

The Council's position on the impacts

The Council contends that the proposed development should be refused on the basis that it is inconsistent with cl 5.21 of the WLEP and with the relevant provisions in Chapter E13 of the WDCP. It makes a number of submissions in support of this position.
Firstly, the Council submits that the flood modelling has used inappropriate inputs, and cannot be relied upon for the assessment of the impacts on flooding. It makes this submission for several reasons. The Council disputes the chosen Manning's 'n' values for various areas of the flood conveyance, asserts that there has been 'double counting' of flood storage areas and raises an issue with respect to the modelling of water around the north of the RSL building.
Specifically, the Council says that it is inappropriate for the model to use a different Manning's 'n' roughness value for the channel in the pre and post-development scenarios. The Council submits that it is wrong to assume that the channel within the site in the post-development scenario is resurfaced concrete with a Manning's 'n' value of 0.012 and the channel outside the development site is well maintained concrete with a Manning's 'n' value of 0.015.
The Council also says the Manning's 'n' value of 0.03 is inappropriate for the landscaped area adjacent to the concrete drainage channel, as this is what is utilised for a well-maintained lawn, whereas the landscape plan shows native grasses. Further, the Council says the landscape strip between the concrete drainage channel and the western boundary has not been appropriately modelled.
The Council also raises issues concerning 'double counting' of flood storage in the post-development model. It relies on the cross-examination of Ms Smith, in which she acknowledged that the flood storage within a proposed OSD tank on neighbouring RSL land as well as within a bowling green had been included in the post development modelling, notwithstanding that the bowling green is to be demolished in the course of the works on the RSL land.
Additionally, the Council says that the flows around the RSL building have not been properly modelled due to the reliance by Ms Smith on the HEC-RAS model, which is a 1D model and therefore not as accurate as a TUFLOW model.
The Council submits that the above issues do not enable an accurate comparison of the pre and post-development scenarios, and leave the Court unable to reach the level of satisfaction required by cl 5.21 of the WLEP.
Secondly, the Council submits that the Court could not be satisfied that the development is "compatible with the flood function and behaviour on the land", as required by cl 5.21(2)(a) of the WLEP as the proposed development diverts some of the flood flow path to a pipe on Nicholson Road, rather than retaining it on the site. The Council says that, for the third flood flow path, the flow conveyed through the site in the PMF is reduced to approximately 15% by the proposed development, with the flow instead conveyed through Nicholson Road. The Council relies on the evidence of Mr Carden, who refers to this as a 'blockage' in the PMF, as the flow is diverted around the site rather than being conveyed through the site.
The Council says that the diversion of floodwater into a pipe on Nicholson Road is contrary to common law, as expressed in Gartner v Kidman (1962) 108 CLR 12, that the lower proprietor has no action against the higher proprietor because of natural unconcentrated flow of water from its land, and the lower proprietor is not bound to receive it, but it is not entitled to divert it to the land of a third proprietor.
The Council also says that the diversion of floodwater from the site to the street is contrary to the controls in the WDCP, which state, at Control 9.3.17 of Chapter E14, that: "c) No obstruction to the overland flow of stormwater runoff from adjacent properties is permitted. Allowance must be made for this overland flow component and adequately catered for on the subject property. In calculating this component, the entire catchment upstream of the subject property must be taken into account. d) The diversion of this overland flow to the street, the rear of the subject property or in any other direction other than that in which it would naturally flow will not be permitted."
In addition, the Council relies on the evidence of Mr Carden that the Council does not have funds for the ongoing maintenance and eventual replacement of the proposed pipe, and submits that the maximisation of development yield through transfer of flood flow conveyance from the development site to a public road reserve is not ecologically sustainable development, because it increases costs to the community with no public benefit.
The Council also says that the applicant has not specified the mechanism of transfer of the pipe to the Council's ownership, which could not appropriately be done through a voluntary planning agreement.
Thirdly, the Council submits that the proposed development does not comply with the WDCP with respect to the PMF and climate change scenario. On the Council's position, the extent of the impacts exceeds the permissible flood impacts in Table 2 of Chapter E13 of the WDCP and the performance criteria in Section 6.4.2(b) because the development will detrimentally increase the potential flood affectation of other properties. Further, the Council says that the PMF impacts are extensive and affect a large list of properties, which is contrary to the merit-based consideration in Section 6.4.3(c), as the development results in increased yard flooding and occurs at locations where there are existing dwellings and so will likely increase above floor flooding.
In support of its position that the impacts on flood behaviour in the PMF are unacceptable, the Council relies on the FDM, which is also referred to in cl 5.21 of the WLEP.
The Council points out that the FDM emphasises the importance of planning for the PMF, by requiring flood studies "for the full range of flood events up to and including the PMF" (Ex 3, Tab 4c, p 7) and making it clear that: "investigating the full range of flood events up to and including the PMF enables changes in the nature and consequences of flooding to be assessed as flood severity increases. These may include increases in velocity and depth, changes in hazard category, the creation of 'islands' (which may be completely inundated in larger events), and the number of properties inundated etc" (Ex 3, Tab 4c, p 8).
The FDM also states that "Unless the PMF is used as the basis for any FPL, a larger flood than the one used to determine the FPL, can always occur. It is not a matter of if but when." It goes on to say: "The difference in flood levels, damages, and the area of inundation and the number of dwellings to be evacuated in the PMF event relative to the event upon which the FPL is based, serves to alert a council to the upper limit of the costs and consequences of flooding."
Fourthly, the Council submits that the failure of the proposed development to maintain the site's flood function (as both floodway and flood fringe areas) is contrary to ecologically sustainable development, as it results in the potential for cumulative impacts to occur as a result of multiple similar developments in the same floodplain. The Council says that ecologically sustainable development would avoid the potential for those cumulative impacts. It submits that this is why cl 5.21 of the WLEP is concerned with cumulative impacts, and submits that these impacts are what the objectives of Chapter E13 of the WDCP are seeking to avoid, at (1)(a) and (1)(b). The Council submits that the 'blocking' of the third flood flow path by the development during the PMF flood results in substantial flow diversion and flood level increases in isolation, and, if development were undertaken in a similar manner across the floodplain, this would result in flood level increases cumulatively across and throughout the wider floodplain.
Fifthly, the Council also tendered a Draft Floodplain Risk Management Study for Collins Creek (Draft Study), which was on exhibition in March 2024. It says that this document comprises stages 3 and 4 of the Council's floodplain risk management process for Collins Creek, and also updates the 2019 Collins Creek Flood Study. The Council relies on the mapping in the Draft Study, which contains updated modelling that identifies that a portion of the site in the east-west direction is a floodway and is a High Flood Risk Precinct. The Council submits that this is consistent with Mr Carden's assessment of the true flood function of the site, which is as a floodway in the 1% AEP with climate change and the PMF.
Finally, the Council submits that the application does not enable an assessment of the planning impacts of the additional flood storage relied upon in the flood model because there is no plan that shows the relative levels (RLs) for the area identified for regrading near the southern part of the channel.

[13]

The applicant's position that the impacts are acceptable

Conversely, MH submits that the Court can be satisfied of the matters in cl 5.21 of the WLEP and that the operative controls in Chapter E13 of the WDCP are met.
Firstly, MH points out that the operation of cl 5.21 of the WLEP contemplates development on flood liable land, which is consistent with the rezoning of the site in January 2011 for R3 Medium Density Residential. The rezoning was supported by a site-specific flood study, which, contrary to the evidence of Mr Carden, considered flooding from all flood flow paths including from the northwest, where the larger catchment flood overflows into the smaller catchment through Campbell Street. MH submits that Mr Carden's position that the historical watercourses need to be preserved will stymie development of the site in favour of preserving its historical function in the PMF. MH submits that these watercourses no longer exist in the common law sense as described in Gartner v Kidman, and there is no legal right for any person to drain water through the second and third flood flow path other than through the 2.8m wide RSL Easement.
Secondly, MH submits that limited weight can be given to the objectives in cl 5.21(1) in circumstances where there is no operative provision that requires their consideration or their satisfaction.
Thirdly, MH submits that, on the evidence of Ms Smith, the Court has sufficient information to consider the matters in cl 5.21(3) and can be satisfied of each of the matters in cl 5.21(2), and that the proposed development does meet the objectives in cl 5.21(1).
In relation to cl 5.21(2)(a), the requirement for the proposed development to be "compatible with the flood function and behaviour on the land" does not equate to 'sameness'. MH submits that compatible means "capable of existing together in harmony", relying on Project Venture Developments v Pittwater Council (2005) 141 LGERA 80; [2005] NSWLEC 191, and says that the site will, in its post-development state, enable the flood function of the site to continue, even for the PMF event, by distributing floodwater through open swales and pipes and diverting part of the PMF through the car park, in each case depositing the same waters in Collins Creek.
In relation to cl 5.21(2)(b), MH submits that there is no evidence that the proposed development will have an adverse or harmful affectation on flood behaviour resulting in detrimental increase in potential flood affectation for other development or properties. To the contrary, MH relies on the flood report, which indicates improvements to a significant number of other properties, and shows only minor increases in flood height in the PMF on a few backyards, which the experts agree are already flooded in the PMF. MH points out that Woonona RSL has given its written consent concerning increased flood levels during the PMF on its site.
With respect to cl 5.21(2)(c), (d) and (e), MH submits that there is no evidence that the proposed development will adversely affect the safe evacuation of people, or will have a harmful effect on the environment or cause erosion, siltation, destruction of riparian vegetation or a reduction in the stability of river banks or watercourses. It relies on the evidence of Ms Smith that there is no increased risk to life and land in all events up to the 1% AEP climate change, there is a reduction in flood risk in the north and east of the site in all events up to and including the PMF storm event, there are no changes to evacuation routes, and safe occupation and shelter-in-place is provided for all future residents of the proposed development.
Fourthly, MH submits that the proposed development complies with the performance standards in the WDCP and relies on s 4.15(3A) of the EPA Act, which precludes a consent authority from requiring more onerous standards in the event that the development meets the relevant standards, and requires flexibility in the event that the relevant standards are not met.
MH submits that Mr Carden's evidence is contrary to s 4.15(3A)(a) of the EPA Act, as he departs from the WDCP by effectively requiring the design flood event to be the PMF, or the 1% AEP with climate change. However, neither events are the flood events against which acceptability is measured in Chapter E13 of the WDCP. In particular, the proposed development complies with the prescriptive permissible impacts in Table 2 of Section 6.4.3 for flood events up to the 1% AEP flood, consistent with the requirements of control (b). Further, the proposed development complies with the requirement that new development must not cause additional lots to be impacted by the 1% AEP or PMF event, and there is no evidence that it will increase the frequency of over flood flooding for other buildings in a PMF event. MH submits that the proposed development meets the relevant standards of the performance criteria in Section 6.4.2 at (a) and (b), as Ms Smith's evidence is that the proposed development does not result in increased risk to life or detrimentally increase the flood affectation on other land. As such, MH says that the proposed development meets the relevant standards and it is therefore unnecessary to consider the objectives of those standards.
However, if the Court considers that the relevant criteria are not met, MH submits that the Court will first need to determine whether the criterion is inconsistent with cl 5.21 of the WLEP, in which case it is of no effect, pursuant to s 3.43(5) of the EPA Act. If it is not inconsistent, MH relies upon s 4.15(3A)(b) of the EPA Act and submits that the Court would then need to consider whether there are reasonable alternative solutions that achieve the objects of that criterion. MH says that those objectives are found in Section 6.4.1, and relies on Ms Smith's evidence that the objectives are met. MH submits that the Council's reliance on the objectives in Section 3 of Chapter E13 is misplaced, as these are the general objectives of Chapter E13 and are not "the objects of those standards" referred to in s 4.15(3A)(b) of the EPA Act.
Fifthly, MH submits that the flood modelling carried out by Ms Smith is accurate and that none of the matters raised by Mr Carden form a basis for not accepting the modelling. Specifically, with respect to overtopping flows, MH submits that the Court ought not to accept Mr Carden's evidence that the pedestrian bridges should be included in the model, given Ms Smith's evidence that overtopping flow is not relevant as the projected flows do not exceed the capacity of those structures.
With respect to the Manning's 'n' value for the planting beds, MH submits that the appropriate 'n' value has been chosen and that the management of the grass can be conditioned to maintain the 'n' value.
In relation to the detention storage and pit/pipe network on the RSL site, MH submits that there is sufficient evidence that the RSL has commenced the approved works, and that, therefore, those works ought to be included in the flood modelling for the proposed development.
Further, in relation to the Manning's 'n' value for the channel, MH relies on Ms Smith's evidence that the industry standard for a well-maintained concrete channel is 0.012 to 0.015. The Council has a legal obligation to maintain drainage assets, and the Council has recently cleaned out a section of the channel, such that Ms Smith's evidence is that the channel is performing much better and the adopted Manning's 'n' values are appropriate in the circumstances. Further, the Council has tendered the Review of Environmental Factors for maintenance works on the channel from Campbell Road to Collins Creek, which works have commenced and will be completed in mid-2024. MH also points out that, in reliance on the decision in Gales Holdings Pty Ltd v Tweed Shire Council (2003) 85 NSWLR 514, the Council is liable for nuisance if it allows the escape of water from its drainage channel onto the site, if it fails to take reasonable steps to avoid that occurring.
Sixthly, MH submits that the Council has not advanced any real reason why it is not appropriate to divert floodwater flows to Nicholson Road. It relies on the evidence of Ms Smith that the introduction of new infrastructure within public roads is considered industry standard practice to respond to proposed new developments. Further, contrary to the Council's position, MH points out that the proposed swale does not result in uncontrolled flow onto Nicholson Road, but is collected by the proposed pit and pipe drainage and drained to Collins Creek. MH submits that, as the High Court envisaged in Gartner v Kidman, a lower owner has a legal right to protect its land by penning back the waters, in the same way that a portion of the PMF floodwaters will be penned back onto the RSL land. MH also points out that, on the evidence of Ms Smith, those waters will drain to Nicholson Road and then to Collins Creek, with the same volume of water arriving at Collins Creek without material alteration or additional impact.
On the basis of those submissions, the applicant's position is that the proposed development will not have an unacceptable impact on flooding and flood behaviour.

[15]

The flood modelling is adequate
In order to understand the impacts of the proposed development on flood behaviour, it is imperative that the flood modelling accurately predict flood levels and velocity in the pre- and post-development scenarios. The aim, as with any environmental impact, is to ensure that the impact is acceptable in the circumstances. However, all modelling of future impacts (including agreed modelling) will inevitably involve an element of uncertainty and potential for error. As Preston CJ of LEC states in Ulan Coal Mines Limited v Minister for Planning and Moolarben Coal Mines Pty Limited (2008) 160 LGERA 20; [2008] NSWLEC 185, "there will always be uncertainty in environmental impact assessment." His Honour goes on to say (at [95]): "By its nature, environmental impact assessment involves a prediction of likely future impacts of a project that has not yet occurred on an environment about which there will invariably be imperfect knowledge… Nevertheless, decisions need to be made. The question is whether there is sufficient, credible information upon which to assess the impacts of a project and make a decision. That is a factual question for the decision-maker to answer."
I consider that the flood modelling carried out by Ms Smith provides sufficient, credible information upon which the assess the impacts of the proposed development. None of the matters raised by Mr Carden or by the Council compromise that credibility.
Firstly, I consider that the Manning's 'n' values used for each portion of the concrete channel in the post-development scenario are acceptable. Each value adopted in the model for the concrete channel, 0.012 for the resurfaced channel within the site, and 0.015 for the channel outside the site, are within the accepted parameters in the relevant industry standard. As summarised by Ms Smith, the accepted industry standard is between 0.012 and 0.017 in accordance with Table 6.2.1 of the Australian Rainfall and Runoff: A guide to flood estimation (2019) (ARR 2019), which is specific to channel conditions, unlike Table 6.2.2 which relates to land use. Based on Table 6.2.1 of the ARR 2019 and her experience, I accept Ms Smith's evidence that the standard industry adopted value of concrete for a concrete channel is n = 0.013 and that it is conservative to adopt an upper value of 0.015 where the channel is legally required to be maintained. I do not accept Mr Carden's evidence, which is based on speculation that there may not be regular maintenance of the channels, that the value should be higher than what is in the specific table for concrete channels in the ARR 2019.
Secondly, I consider that use of different Manning's 'n' values in the pre-development scenario is appropriate in the circumstances. The adopted value of 0.02 for the pre-development scenario is that which is reflected in the 2019 Collins Creek Flood Study, there is evidence that the channel is presently not fully maintained, and the post-development scenario reflects the fact that the works to be carried out in the proposed development will include channel restoration works. I accept the submission made by Mr Robertson SC that the Council will then have a legal obligation, consistent with the principles in Gales Holdings Pty Ltd v Tweed Shire Council, to carry out maintenance to prevent a nuisance arising from water escaping from the drainage channel onto the site.
Thirdly, the channel width used by Ms Smith in the model, to which the Manning's 'n' value for concrete was applied, is acceptable. When cross-examined on the inputs used for the channel width, Ms Smith confirmed that the data utilised was that which was provided by the Council and consistent with the 2019 Collins Creek Flood Study. She confirmed that the channel width used did not change in the model for both pre- and post-development scenarios. As such, the Manning's 'n' value adopted for the channel was applied to the appropriate width of the channel. Whilst this resulted in some of the landscaped area being included in the model as part of the channel, I accept Ms Smith's evidence that, with that Manning's roughness over a depth of only 100mm, the resultant increase in flooding will be negligible, and, given that there is a decrease in flooding overall "it wouldn't even come back to neutral" (Tcpt, 6 March 2024, p 9(22)). Given her familiarity with her flood model for the proposed development, I prefer her evidence concerning the outcome of changes in input values to that of Mr Carden.
Fourthly, the Manning's 'n' value of 0.03, used for the landscaped area near the channel is acceptable. It is within the parameters for "Open pervious areas, minimal vegetation" in Table 6.2.2 of the ARR 2019, which is between 0.03 and 0.05. Given that there will be native grasses in this area, I consider that it meets the description of an open pervious area with minimal vegetation, consistent with Table 6.2.2. The evidence of Mr Carden with respect to the movement of water through native grasses was pure speculation, and the facts that informed that opinion were not identified.
Fifthly, I accept the evidence of Ms Smith that the averaging of the roughness across the landscaped area results in a model that is representative of the landscape plans. Each trunk size has been represented as 0.5m in the model and modelled with a Manning's value of 1, whereas in reality, all trunk sizes are 0.2m, resulting in a more conservative approach to the averaged Manning's 'n' value across each landscaped area. I accept Ms Smith's evidence that averaging the roughness across each landscaped area with the tree trunk size of 0.5m across grassed areas for which a Manning's 'n' value of 0.03 was used, results in a resulting roughness that is representative of the landscape plans that form part of the development application.
Sixthly, the inclusion of the detention storage facility and pit/pipe drainage network on the upstream RSL site in the model is acceptable. This has been included in both the pre- and post-development modelling, and assumes that in both scenarios the works on the RSL site will be carried out in accordance with the stormwater design for the development consent granted. I accept that there is evidence that the development consent that applies to the RSL site has commenced, with a photograph of the site on 24 December 2023 showing the sediment and erosion fencing as well as construction fencing (see Ex 5) and a letter from the RSL confirming that the works would commence in December with an expected completion date of mid-May (Ex J, Tab 16). Given that the detention storage facility and pit/pipe drainage network on the RSL site will be in place in both the pre- and post-development scenario, it is appropriate to include those works in the flood modelling.
Although there was criticism by the Council and Mr Carden concerning the failure of the model to remove the bowling green on the RSL site, neither the Council nor Mr Carden provides evidence on the extent of change that its removal would make to flood behaviour in either the existing conditions or the post-development scenario, and the plans for the development of the RSL site are not in evidence to inform how surface flood storage may occur on the RSL site once developed. Without that evidence, Mr Carden's assertion that there may be an underestimation of the flows arriving at the site as a result of the failure to remove the bowling green is not sufficient to bring into doubt the accuracy of the model.
Sixthly, I accept Ms Smith's evidence that the pedestrian bridges are not required to be included in the model because the projected flows do not exceed the capacity of those structures. Further, I accept her evidence that blockage due to the upstream culvert inlet does not apply in this context as the site is significantly downstream from the culvert inlet. As such, the modelling adequately deals with the debris blockage requirements in Section 5.2 of Chapter E13 of WDCP.
Finally, contrary to the Council's submission, the use of HEC-RAS in the modelling of flows around the RSL building does not compromise the accuracy of the modelling. Ms Smith provided clear justification for her use of this one-dimensional model, which blocks out the RSL building so that flow traverses either side of the building. This is distinct from the two-dimensional TUFLOW model in the 2019 Collins Creek Flood Study, which shows water flowing through the building. However, due to the floor level of the RSL building, as a matter of fact, her evidence is that water will not flow through the building in the PMF. Whilst Mr Carden says that this can be dealt with by inserting a Manning's 'n' value for the RSL building into the two-dimensional data, Ms Smith's preference is to not to do so, as that can cause anomalous flood behaviour through the whole model due to it causing storage effects in the buildings. Accordingly, I am satisfied that the use of one-dimensional data to inform how the water will flow around the RSL building does not compromise the accuracy of the model.
For the above reasons, the flood modelling carried out by Ms Smith is adequate and credible, and provides accurate information on the impacts of the proposed development on flood behaviour in the various storm events. This informs the assessment of the acceptability of those impacts.

[19]

The PMF is an event between 1 in 10,000 years and 1 in 100,000 years, which means it has less than a 0.01% chance of occurring over a 100-year period (Ex 3, Tab 4C, p A-1). Section 6.4.3 of Chapter E13 of the WDCP requires that flood impacts in the PMF be "assessed on merit", considering the following: "i) Impacts to evacuation routes and onsite refuge service levels; ii) Additional flood affected allotments; iii) Flood warning times; and iv) Changes to above yard and above floor flooding"
In addition, following Table 2, there is an unnumbered control that states: "New development must not increase the frequency of over floor flooding for residential, commercial or industrial buildings in a 20%, 1% or PMF event. Additionally, new development must not cause additional lots to be impacted by the 1% or PMF event."
The words "merit approach", although not used in Section 6.4.3, are defined in Chapter E13 as an approach that involves a number of broad principles taken from the FDM. The definition provides limited assistance to the merit assessment required to be carried out in accordance with Section 6.4.3(c).
For the following reasons, I consider that the flood impacts in the PMF are acceptable.
Firstly, the uncontested evidence of Ms Smith is that there are no additional lots affected by the PMF as a result of the proposed development. All of the lots that will be affected by the PMF in the post-development scenario, which Mr Carden lists in his evidence, are already affected by the PMF in the pre-development condition.
Secondly, the flood afflux in the PMF is largely confined to rear yards of residential properties, as well as to the RSL car park. I accept the evidence of Ms Smith that the residential properties that may be impacted are impacted to between 50-100mm at the location of rear sheds, and 100mm to a maximum of 200mm in rear yards behind sheds. Contrary to Mr Carden's opinion that these increases will increase risk to property and life by increasing inundation of car parking and public areas that may be potentially used as an evacuation route, the flood depth mapping shows that these car parking and public areas are already inundated in a PMF event in the pre-development scenario and cannot be used as an evacuation route in the PMF. For the same reasons, there is no increased risk of property damage from yard and shed flooding in circumstances where these areas are already inundated in the PMF.
Thirdly, the PMF event is of such low frequency that it is immaterial if there are marginal increases in "the frequency of over floor flooding" of residential properties that are already inundated in a PMF event. On the evidence of Mr Carden and based on the PMF flood afflux modelling, the projected changes in flood levels on areas within the footprint of residential dwellings is between 2 and 5cm for most dwellings, with up to 25cm at 7 Nicholson Road, where onsite refuge is not available during the PMF in any event. Any impact from this change in flood levels can only be described as de minimis, as it is concerned with marginal increases in depth of flooding in areas where there is already flooding, in an event that has a less than 0.01% chance of occurring in a 100-year period. I accept the evidence of Ms Smith that such small changes in flood levels on residential properties in a PMF would have no impact on onsite refuge on those properties.
Fourthly, I accept the evidence of Ms Smith that there are no changes to evacuation routes and flood warnings in the PMF as a result of the proposed development. As set out in the flood report (Ex H, Tab 3), in "both existing and developed conditions, the PMF hazard categories suggest that evacuation along Nicholson Road is blocked in both an easterly and westerly direction with Hazard Categories H6 and H5 respectively" (p 48). As a result, evacuation can occur only prior to the onset of the storm event, and there is no change to that in the post-development scenario. For the same reason, flood warning times do not change as they are required to be given prior to the storm event.
Finally, there are areas where there is a reduction in flood heights in the PMF as a result of the proposed development, and adjoining properties and residents to the north and east of the site will benefit from flood impact reduction in the PMF events. This can be seen in Figure 5.
For those reasons, a merit assessment of flood impacts in the PMF leads to the conclusion that the impact of the proposed development on flood behaviour in the PMF is satisfactory.

[20]

(d) The performance criteria in the WDCP are met

Contrary to the Council's position, I am satisfied that the proposed development will not result in any increased risk to life. As set out above, there is compliance with the prescriptive controls with respect to the 1% AEP event, and the flood impacts in the PMF are satisfactory. It is uncontested that the proposed development provides adequate shelter in place in the event of a flood, up to the PMF. With respect to other residential properties, there are benefits from flood impact reduction in all storm events up to the PMF storm event, with only a small area of afflux in the 1% AEP climate change scenario and no additional lots affected by the PMF storm event.
Further, I am satisfied that the development does not "detrimentally increase the potential flood affectation on other development or properties" in circumstances where there is a decrease of flooding across residential areas surrounding the site. Any increase in potential flood affectation on other development or properties is confined to the PMF event and does not actually result in any identified disbenefit, given the extent of the PMF flood affectation in the existing conditions. There is no increase in potential flood affectation in the 20% AEP or the 1% AEP, which are the other two events required by the WDCP to be modelled. The development, individually, does not detrimentally increase the potential flood affectation, and there is not a skerrick of evidence to support the Council's position of a cumulative detrimental impact on potential flood affectation. There is no evidence concerning "development that is likely to occur in the same floodplain", and Mr Carden's opinion concerning a cumulative detrimental impact is purely hypothetical, and plainly ignores the reduction in flood levels across residential areas as a result of the development in the 1% AEP, which means there are no detrimental impacts with which the impacts of another development could be cumulative.
I am therefore satisfied that the proposed development is consistent with the performance criteria in Section 6.4.2 of Chapter E13 of the WDCP.

[21]

The piping of some flood conveyance under Nicholson Road is acceptable
I also find that the capture and conveyance of some of the overland flow to a pipe under Nicholson Road, as proposed, is acceptable, for the following reasons.
Firstly, contrary to the evidence of Mr Carden, the third flood flow path cannot be considered a natural watercourse. I accept the position advanced by MH that there is no watercourse at common law, for the reason that there is no indicia of a channel through which the water would flow, such as beds, banks or sides: see Gartner v Kidman at [27]. Instead, it is agreed that this flood flow path is sheet flow in a 1% AEP and PMF event, and only meets the description of a floodway in the PMF. As such, there is no reason why this path of overland flow needs to be maintained in favour of collecting the water and conveying it in some other way.
Secondly, I accept the submission made by MH that, other than the RSL Easement, there is no legal right for any person to drain water through the site through either the second or third flood flow path. Again, this means there is no reason why this flow cannot be collected and conveyed in some other way.
Thirdly, only some of the overland flow that exists in the pre-development scenario is proposed to be piped through Nicholson Road. In the post-development scenario, the site continues to receive flows from upstream sites and maintains its conveyance of those flows, but, after receiving it, diverts some of it to the proposed pipe under Nicholson Road. Indeed, that part of the flow conveyance that is maintained wholly within the site is not reduced to the extent that Mr Carden opines. Mr Carden's evidence is that for the third flood flow path, approximately 19.8m3/s is conveyed within the site during the PMF and 25.8m3/s is conveyed within Nicholson Road south of the site, with the proposed development reducing conveyance within the site to 3.2m3/s and increasing conveyance within Nicholson Road to 40.8m3/s. I prefer Ms Smith's evidence on this point, which is that Mr Carden neglected the swale drainage incorporated into the design, and that flow conveyance through the site within the PMF event is reduced to around 50% of the current conveyance of 19.8m3/s, with the proportion of flood conveyance retained on the site increasing for the 1% AEP climate change event. Accordingly, this is not a case where all of the flood flow conveyance is being diverted to a new pipe under the road. Instead, all of the water will be conveyed across the site and most of it will be contained within the site, except that in the PMF the flood flow conveyance that occurs wholly within the site is reduced to around 50% of the pre-development flood flow conveyance within the site.
Fourthly, whilst the piping of some of the overland flow through Nicholson Road is contrary to control (c) in Section 9.3.17 of Chapter E14 of the WDCP controls, which requires all overland flow of stormwater runoff from adjacent properties to be "adequately catered for on the subject property", s 4.15(3A)(b) of the EPA Act operates to require flexibility and "allow reasonable alternative solutions that achieve the objects of those standards for dealing with that aspect of the development". There are two respects in which the piping of overland flow through Nicholson Road is an alternative solution to achieve the objects of this standard.
The first is that, whilst there are no stated objectives for this particular standard, it is axiomatic that the objective is to ensure that the same volume of overland flow continues to be conveyed to where it would naturally flow. I accept the submission made on behalf of MH in that regard. I accept Ms Smith's evidence that the fact that there is no upstream afflux within all storm events up to and including the 1% AEP climate change, means that the proposed development maintains flow conveyance in these storm events, even with the piping of some of the overland flow through Nicholson Road.
The second is that the proposed development achieves the objectives of Chapter E14 at 1.1 that are relevant to this control, which are as follows: "c) Reduce the probability of downstream flooding; … g) Minimise the drainage infrastructure cost of development; and h) Increase public convenience and public safety as well as protection of property."
With respect to these objectives, I accept the evidence of Mr Vu that they are achieved as the design maintains the existing trunk drainage alignment and overland flow path from west to east of the site, and improves downstream flood impacts by introducing an appropriately sized stormwater trunk drainage infrastructure to convey upstream runoff in a safe manner. I also accept his evidence that the cost is minimised by adopting the shortest distance, and that containing the flows within the stormwater infrastructure will ensure public safety and protection of properties.
For those reasons, I accept that the proposed design is an alternative solution that achieves the objects of control (c) in Section 9.3.17 of Chapter E14. Given the rareness of the PMF, there is no requirement for flow conveyance within the site to be maintained to its full extent in the post-development PMF.
I also consider that there is no breach of control (d) of Section 9.3.17 of Chapter E14, as the overland flow is not diverted "to the street" but rather to a pipe, and it continues to flow in the direction that it would naturally flow.
Fifthly, I do not accept the submission of the Council that any principle in Gartner v Kidman is offended by the proposal to divert some of the overland flow through pipes to the same receiving catchment. The diverting of the flow, as proposed, does not result in it causing a nuisance to the property of a third party. Instead, the flow is to be conveyed through infrastructure ordinarily used for conveying stormwater flow, in a location where such infrastructure is commonly located.
Finally, it is ordinary practice for infrastructure that conveys stormwater within a catchment area to be managed and maintained by the Council, just as the existing concrete channel along the east of the site is managed and maintained by the Council. I accept the evidence of Ms Smith that the introduction of new infrastructure within public roads is considered industry standard practice to respond to new developments. The Council has not advanced any reasonable basis upon which this practice should be constrained to infrastructure required to capture stormwater that falls on the site of the proposed development. Further, assertions that the Council has insufficient funding are not persuasive. The proposed pipe is no different to other stormwater infrastructure that the Council already manages and maintains. This is consistent with the decision of Preston CJ of LEC in Goldcoral Pty Ltd (Receiver and Manager Appointed) v Richmond Valley Council [2024] NSWLEC 77, in which his Honour found that bioswales were appropriate to be dedicated to the relevant council for maintenance and management (at [172]-[175]).
For all of those reasons, the diversion of part of the overland flood flow to a pipe under Nicholson Road, which will be constructed by MH and maintained into the future by the Council, is entirely acceptable.
I note that, insofar as owner's consent is required for the development application as it relates to the works on Nicholson Road, pursuant to s 39(2) of the Land and Environment Court Act 1979 the Court can exercise the function of the Council to give the owner's consent required by s 23 of the EPA Regulation 2021. An approval for the works under s 138 of the Roads Act 1993, if required, will nonetheless need to be obtained prior to the carrying out of the works.

[22]

Satisfied of matters in cl 5.21
On the evidence, I have considered the matters in cl 5.21(3) of the WLEP and I am satisfied of each of the matters in cl 5.21(2).
Firstly, I am satisfied that the development is "compatible with the flood function and behaviour on the land" (cl 5.21(2)(a)). The parties agree that the flood function of the site is flood conveyance, and "flood function" relates to floodway areas, flood storage and flood fringe areas.
I accept the submission made on behalf of MH that compatibility does not require the same flood function and behaviour to be replicated on the site post-development, with the same depths and velocity of flow maintained in the same locations for each storm event. Instead, the focus is on the compatibility of "the development", which includes both the works on the site and those within Nicholson Road, with flood function and behaviour on the site. It is therefore concerned with ensuring that the development will enable the flood function and behaviour of the site, which is flood conveyance, to continue in its post-development state. I accept the evidence that this will occur. Flood conveyance (through both floodway and flood fringe areas) is maintained, even for the PMF event, by distributing floodwater through open swales and pipes, with some overland flow diverted to the car park in the PMF. The flow continues to be deposited in Collins Creek in the same volume, with a decrease in peak flows for the full range of storm events up the 1% AEP (Ex H, Tab 4). Accordingly, I am satisfied that the proposed development is compatible with the site's flood function as flood conveyance (including floodway and flood fringe areas) and is compatible with flood behaviour on the site, as the flood will continue to flow through the site albeit directed to Collins Creek utilising a different path. This compatibility exists for the full range of storm events, up to the PMF, where there is some diversion to the RSL car park.
Secondly, I am satisfied that the proposed development will not impact flood behaviour in a manner that will adversely affect other properties (cl 5.21(2)(b)). I accept the evidence of Ms Smith and Mr Vu that the proposed development results in improvements to the flood affectation of other properties for storm events up to and including the 1% AEP climate change event, with no offsite impacts other than a small area of afflux for the 1% AEP climate change event contained in the channel. Even in the PMF storm event, adjoining properties to the north and east will benefit from flood impact reduction, and all lots that will be affected by the PMF in the post development scenario are already affected by the PMF in the existing condition. Given the rareness of the PMF, I do not accept that an increase in flood levels that only occurs in the PMF event to properties already affected by the PMF in the pre-development scenario is an impact that offends cl 5.21(2)(b).
Thirdly, I am satisfied that, consistent with cl 5.21(2)(c) of the WLEP, the proposed development "will not adversely affect the safe occupation and efficient evacuation of people or exceed the capacity of existing evacuation routes for the surrounding area in the event of a flood". I accept the uncontested evidence of Ms Smith that there is no change to evacuation routes. I accept her evidence that the afflux mapping shows that there are no offsite impacts affecting dwelling footprints in flood events up to and including the 1% AEP climate change scenario. Accordingly, there remains safe occupation in the 1% AEP flood for anyone whose floor levels are already above the 1% AEP flood.
With respect to Mr Carden's concerns about safe occupation in the PMF, as set out above at [123], the prospect that there might be over floor flooding because of an increase in flood levels by 5cm or 25cm within dwelling footprints on flood affected properties in an event that occurs between 1 in 10,000 and 1 in 100,000 years is the quintessence of an affectation that is de minimis.
Fourthly, I am satisfied that the proposed development "incorporates appropriate measures to manage risk to life in the event of a flood", in accordance with cl 5.21(2)(d), as it meets the WDCP requirements concerning floor levels to enable safe refuge in a flood event, incorporates a flood emergency response plan, and will be required by conditions to ensure that the materials used in its construction will withstand the force of floodwaters.
Fifthly, consistent with cl 5.21(2)(e), I am satisfied that the proposed development "will not adversely affect the environment or cause avoidable erosion, siltation, destruction of riparian vegetation or a reduction in the stability of river banks or watercourses". The proposed development includes works to the concrete channel that will result in improved conditions for the watercourse within the channel, and includes the construction of a swale and pipe system that will result in a reduction of debris that will be washed from the site to Collins Creek.
Further, based on the evidence in the proceedings, I have considered the matters in cl 5.21(3). In doing, so there is nothing that arises that warrants refusal of the development application, for the same reasons as those given in relation to cl 5.21(2) above.
Finally, contrary to the Council's position, there is no requirement to be satisfied of the matters in cl 5.21(1) of the WLEP, which set out the objectives of the clause. In the absence of any provision that gives those objectives an operative effect, such as requiring their consideration or satisfaction, the objectives can be informative but are not a measure of the acceptability of the proposed development (Micro Nest No 1 Pty Ltd on behalf of Micro Nest Ashfield Trust v Inner West Council [2019] NSWLEC 1320 at [53]-[54]). I accept the submission of MH that it can be expected that the objectives are met if the matters in cl 5.21(3) have been considered and there is satisfaction of the matters in cl 5.21(2).
In any event, for the reasons set out above concerning cl 5.21(2), I am satisfied that the proposed development is consistent with the objectives in cl 5.21(1). In the 1% AEP event and the 1% AEP climate change event, there are no adverse impacts on flood behaviour and the environment, safe refuge is maintained for residential properties, and there is no change to the evacuation routes or warning times. Even in the 1% AEP climate change scenario the proposed development is consistent with the flood function of the site, as flood conveyance is maintained by distributing floodwater through open swales and pipes to Collins Creek. Given the lack of impacts in flood events up to the 1% AEP climate change, there is no concern about cumulative impacts, there being no impacts with which to 'cumulate'. Indeed, the Council concedes in its written submissions that "cumulative impact assessment is not necessary if key LEP and DCP objectives and controls are satisfied by each individual development in the floodplain" (RWS, par 58).

[23]

The remaining matters raised by the Council are not persuasive
None of the remaining matters raised by the Council concerning impacts on flooding are persuasive.
Firstly, the Council relied upon the FDM to emphasise the importance of considering the impacts of the proposed development on flooding in the PMF. However, the FDM is a strategic management document to provide "councils with a framework for implementing the policy to achieve its primary objective" (at 1.2). The reference to "the policy" is to the NSW Flood Prone Land Policy, which is contained at 1.1 of the FDM. The FDM is concerned with the implementation of this policy at various levels of government, including by councils, and provides for "a merit based approach to selection of appropriate flood planning levels" (at 1.1.2). That is, the FDM recognises that is the role of each council to select appropriate flood planning levels. It provides guidance on selecting the flood planning level at Appendix K, stating that: "development controls, including FPLs for future development, aim to reduce the likelihood that properties and buildings flood and reduce the exposure of people to dangerous flood situations. As it is generally not feasible nor socially, environmentally nor economically desirable to safeguard development against the PMF, a continuing risk from rare flood remains. The selection of a flood event upon which a FPL is based is therefore essentially a matter of balancing: □ the social, economic, environmental and cultural costs of restricting land use in flood prone areas; against □ the social, economic, environmental and cultural benefits of a reduction in the frequency, inconvenience, damage and danger to people caused by flooding."
The FDM, therefore, is not a set of controls against which individual development applications can be assessed. Instead, the development controls are those contained within the WDCP, against which the impacts have been assessed above at [107] to [129]. The FDM discourages councils from safeguarding against the PMF, yet the WDCP requires a merit assessment of impacts on flooding in the PMF, which has been carried out above at [120] to [126]. The FDM does not compel any further assessment of the impacts in the PMF.
Secondly, the Draft Study relied upon by the Council is not a document required to be considered in assessing the development application. MH has carried out flood modelling in a manner consistent with the requirements of Section 5 of Chapter E13 of the WDCP, relying on the ARR 1987 and the 2019 Collins Creek Flood Study, the latter being the adopted flood study in relation to the Collins Creek catchment. The development application therefore complies with what is required by the WDCP, including controls with respect to how the modelling is to be carried out and how the development is required to perform in the defined flood events. In these circumstances, pursuant to s 4.15(3A)(a) of the EPA Act, the consent authority "is not to require more onerous standards with respect to that aspect of the development".
Thirdly, contrary to the Council's position, there is adequate information to consider the planning impacts of the additional flood storage relied upon in the flood model, which is identified for regrading in Civil Plan DA-0102 and is also shown on the cut and fill plan. The Council has not identified anything unacceptable about the excavation of that area for flood storage.

[27]

Easement width

The control in Section 9.3.6 of Chapter E14 of the WDCP requires the drainage easement to have a width that is described as follows: "Width required for maintenance, but not less than the width of conduit plus 2m." The current pipe within the existing RSL Easement is 1050mm in diameter, and is proposed to be replaced with a 2400mm wide x 600mm high rectangular box culvert in a new easement to be created of a width of 2.7m.
Mr Carden opines that the width of 2.7m is not sufficient to enable adequate space to safely maintain, repair and/or replace stormwater infrastructure, and this will increase the maintenance cost for the lot benefitted by the easement for both ongoing maintenance and any requirement to replace parts of the pipe.
On the other hand, Mr Vu's evidence is that the shoring trench boxes proposed have an external width of 2.7m (if maintenance or replacement is required) and that the pipes are designed so that there are frequent entry points for maintenance. Mr Vu also relies on the Culvert Construction and Management Plan (CCMP) that explains how they can be maintained in situ (Ex 9, Attachment J).
None of the issues advanced by Mr Carden concerning the width of the easement can be sustained. I accept Mr Vu's evidence that the proposed easement width is adequate to enable ongoing maintenance and repair in accordance with the CCMP. The CCMP makes it clear that any excavation within the easement can be supported by building walls on either side, without the need for the shoring that was speculated by Mr Carden to be required. Further, as submitted by MH, the maintenance is the responsibility of the servient owner under the terms of the proposed easement (Ex U), and would not impose additional costs for the lot benefitted by the easement. In addition, I accept the submission of MH that the requirements of Section 9.3.6 relate to the creation of an easement on a downstream property over which water from the development drains, rather than the creation of an easement on the property the subject of the development application.
For these reasons, the proposed width for the new RSL easement is adequate and does not form a basis for refusal of the development application.

[28]

Encroachments over proposed easements

Section 9.4.3 of Chapter E14 of the WDCP sets out conditions "to be met in the construction of buildings over common stormwater lines/easements". It includes a condition, at (d), that: "(d) No part of the structure, including footings, eaves and gutter overhang will be permitted to encroach into the drainage easement, except in special circumstances and subject to the approval of Council."
There are two proposed easements that the Council says are encroached by the proposed development.
The first is the proposed new RSL easement, which is of a reduced width and Mr Carden points out will be immediately adjacent to buildings, landscaping, vegetation, retaining walls, pedestrian bridges and a basement encroachment. Mr Carden is concerned by the existence of a permanent structure on the stormwater line or easement, and says that written approval from all owners is required.
However, Mr Vu is of the opinion that the stormwater pit access provided in the new structure will provide better access for maintenance. His evidence is that: "An additional 9 raised access chambers along the length of the stormwater line have been provided for maintenance purposes. These raised access chambers have been introduced at intervals of 6m along the alignment of the proposed trunk drainage to allow for safe access and maintenance at regular intervals. Therefore, there are a total of 11 entry locations along the entire length of the culvert. Each access chamber has internal step irons to allow for clear access down to the culvert for maintenance" (Ex 7, p 67)
Further, the RSL has agreed to the release of the RSL Easement and the creation of a new easement, which will require the owner of the site to be responsible for the maintenance of the stormwater infrastructure the subject of the new easement.
Based on the evidence of Mr Vu and the fact that the owner of the site will be responsible for maintenance, I cannot accept that there is any issue concerning basement encroachment in the proposed new RSL easement.
The second proposed easement that the Council says will be encroached is that of Swale No 01, which functions as an overflow path and is annotated as "'A' = easement to drain water 3.7m and variable width". Mr Carden says that the proposed private open space decks of four dwellings encroach on this easement, which contains a 3 x 0.9m x 0.45m reinforced concrete box culvert. Mr Carden considers that this encroachment, although there is a vertical clearance of 0.5m, will obstruct access for maintenance and is inappropriately located in an overflow path.
Mr Vu's evidence is that the clearance of 0.5m between the swale and private open space soffit is reasonable given that it is only partial encroachment of the easement, and the swale width (3m) and length is sufficient to allow free access for maintenance.
I accept the evidence of Mr Vu, which is again supported by the CCMP concerning maintenance of the culverts. The encroachment by the private open space is minimal and I accept Mr Vu's evidence that there remains sufficient access for maintenance purposes.
As such, neither of the encroachments identified by the Council are sufficient to warrant refusal of the development application. In both cases, there is a way in which access is made available for ongoing maintenance and repairs, without the encroachments causing an issue. There is no evidence that the encroachments will obstruct the free flow of waters through the culverts or swales.

[31]

Bund in the northeast corner

The Council contends that the bund on the northeast corner of the site, which prevents afflux on adjoining properties, has the effect of trapping water on the adjoining property and is therefore contrary to Control 9.3.17 of Chapter E14 of the WDCP, which makes it clear that "no obstruction to the overland flow of stormwater runoff from adjacent properties is permitted". It relies on the evidence of Mr Carden that this bund is likely to result in "nuisance type stormwater impacts" that are not shown in the flood modelling because the model is not capable of simulating local nuisance type effects.
Mr Vu's evidence is that the 200m high bund on the northeast corner was introduced to prevent increased flood levels on adjoining properties, and the flood mapping demonstrates that it has a significant net benefit to properties to the north and east of the bund. Mr Vu points out that no adverse impacts from the bund are demonstrated in the flood afflux mapping in the storm events up to the 1% AEP in the climate change scenario. His evidence is as follows (Ex 7, p 77): "If there was adverse impacts due to the placement of the bund, there would be afflux shown on the adjoining properties. However, there is no afflux shown on adjoining properties at this location in all storm events up to and including the Climate Change scenario. This also includes nuisance flooding in the 20% AEP storm event. Therefore it can be concluded that the bund has a beneficial effect. TUFLOW is capable of modelling local nuisance flooding, and the 20% AEP event is considered a more frequent nuisance flood event. The modelling demonstrates that there are no offsite impacts in the nuisance flooding events."
Contrary to the Council's position, there is no evidence that the bund will cause obstruction to the overland flow of stormwater runoff from adjacent properties. Mr Carden's opinion in that respect is speculation, and it is not based on any of the modelling. Instead, I prefer the evidence of Mr Vu that, even with the modelling of mainstream flooding, the TUFLOW model will capture local nuisance flooding and the modelling demonstrates that there are no offsite impacts of the bund in the nuisance flooding events.

[37]

Adequacy of soil volume

Section 6.4 of Chapter E6 of the WDCP sets average soil depth and volume requirements for trees, shrubs, groundcover and lawns on structures or podiums. It requires a minimum of 150m3 for large trees, 36m3 for medium trees and 16m3 for small trees.
The evidence of Mr Madry is that there is insufficient soil volume for some of the planting proposed in the communal open space. He says that the Waterhousea floribunda, the weeping lilly pilly is a medium tree species requiring 36m³ of soil but only 10m³ is proposed.
However, Mr Vago is of the opinion that Waterhousea floribunda is a small tree when planted in development projects and, under the Apartment Design Guide (which does not apply to the proposed development), the soil requirement would be 9m³ to sustain the tree to grow to the size anticipated (6-8m in height and 4m wide).
I prefer Mr Vago's evidence, given his experience with planting the species on development sites, that the Waterhousea floribunda will grow within a smaller soil volume than that required by the WDCP for medium trees, and will achieve the size he anticipates, of 6-8m in height and 4m wide. I note that even if I was to accept Mr Madry's evidence that additional soil volume was required for this species, this would not be a basis to refuse the development application.
Further, the parties have agreed to a condition of consent, at condition 70, that requires the submission of a final landscape plan to the principal certifier, prior to the issue of the construction certificate. One of the requirements of the final landscape plan is that it includes "minimum soil volumes to be achieved for planting over structure & drainage infrastructure in accordance with Section 6.4.2 of Wollongong Development Control Plan" (at (f)). As it is assumed that the beneficiary of a development consent will comply with the conditions imposed on the consent (TL & TL Tradings Pty Ltd v City of Parramatta Council [2019] NSWLEC 160 at [13]), it seems that the agreed condition renders otiose this issue raised by the Council concerning inadequate soil depth in the communal open space.

[39]

Area of deep soil

There is conflicting evidence concerning the area of deep soil. Mr Bass' evidence is that the deep soil landscape area is 16.88%, which has not excluded areas with stormwater infrastructure beneath it given that the infrastructure has no material effect on the deep soil planting. His evidence is also that there are additional areas of deep soil landscaping that are not included because they do not meet the minimum width of 6m, however, if included, the total deep soil area of the site would be 17.87%.
Mr Rollinson opines that Section 5.9.2(2) of the WDCP only requires deep soil to be provided at 15% where the deep soil zone is not located at the rear of the site. As there is deep soil zone located at the rear of the site that complies with the minimum width of 6m, Mr Rollinson considers that there is no percentage threshold to be achieved.
On the other hand, Ms Robinson considers that the proposed development does not achieve the minimum of 15% deep soil zone requirements because it cannot include areas with stormwater infrastructure beneath it and must have a minimum dimension of 6m. Further, she considers that land containing a dry creek bed swale does not meet the definition of "deep soil zone" as it does not leave an area of deep, soft soil for substantial deep-rooted vegetation, natural vegetation and natural drainage. If these areas are excluded, only 11.2% of the site is deep soil zone.
Similarly, Mr Madry considers that areas should be excluded from the deep soil zone, including the north-west corner of the site that has stormwater drainage infrastructure, Swale 1, and the rock lined deltas of swales 1 and 3.
In my view, there is sufficient deep soil zone. The notion that you cannot count certain areas of deep soil because they do not meet other requirements for deep soil areas, such as minimum dimensions or contiguity, is not supported by the wording of Section 5.9.2 of Chapter B1 of WDCP. Section 5.9.2 includes separate controls with respect to:

The minimum area for deep soil if the deep soil zone is not at the rear of the site (5.9.2(2)),
The location of the deep soil area (5.9.2(2)),
The requirement for it to be continuous (5.9.2(2)),
The requirement for there to be no structures within the deep soil zone (5.9.2(3)), and
The requirement for it to be densely planted (5.9.2(4)).

A non-compliance with the second to fifth dot points above does not mean that the area cannot be counted toward the first. There is nothing in the wording of Section 5.9.2 that suggests such an interpretation. The deep soil zone is defined in Appendix 4 as "an area of the site that is not to be built upon, or underneath, leaving an area of deep, soft soil for substantial deep-rooted vegetation, natural vegetation and natural drainage…".
I am satisfied that the proposed development complies with the minimum area for deep soil. The total deep soil area of the site is 17.87%. This is demonstrated by the area calculations in Figure 7, which can be compared with the areas of unlimited soil depth in Figure 8.

[40]

Viability and adequacy of plantings

The landscape zoning strategy proposes various zones within the site for different landscape designs, as shown in Figure 9, with the detail of the plantings then particularised in the landscape plans.
The architects, town planners and landscaping experts agree that the loss of the existing mature stand of Melaleuca quinquenervia will be adequately compensated by the design of the Melaleuca meadow, and habitat boxes will be provided to the local bush care. They agree that the proximity of the Melaleuca meadow to the private open space of Units TH21-23 & TH25-26 provides a sufficient level of amenity to those units.
They also agree that an appropriate design strategy for the landscaping design of the western swale should include locating groundcover planting adjacent to the western boundary, providing a transparent open balustrade to allow visual connection to the landscaping, providing a shade tree to each courtyard and incorporating a 2.2m high fence at the boundary (with an opening on the lower portion to accommodate overland flow). Whilst Ms Robinson disputes that this can be achieved, it is agreed in their supplementary report that at the halfway point along that western swale there is 560mm of soil available for planting, and at the point where the western swale turns east there is 700mm of soil available for planting. Mr Vago's evidence is that this is sufficient depth for the species of tree selected, Leptospermum laevigatum, to achieve a height of 3m, which is sufficient in this context as no screening of the full height of the building is required. Further, Mr Vago points out that in this location, there are two trees situated at the north end of the western boundary over an average soil depth of 660mm including 100mm depth river pebble mulch (with a soil volume of 18m3 per tree) and two trees situated at the southern end over soil depth of approximately 800mm including 100mm river pebble mulch, with a soil volume of 22m3 per tree. He says that these volumes comply with the volumes specified in Section 6.4 of Chapter E6 of the WDCP for small trees. The trees are each beside rear decks that are permeable (approx 600mm above the soil level) and the soil below the deck will facilitate tree root growth and can be counted as volume. Accordingly, his evidence is that the trees proposed along that western swale are viable and will grow in that context.
Based on the evidence of Mr Vago, I am satisfied that what is contained in the landscape plan can be achieved. I also accept the evidence of Mr Rollinson that the proposed landscape and deep soil design promotes the linkage of landscaping to adjacent properties and spaces, and represents a thoughtful response to the site's specific conditions. Contrary to the evidence of Ms Robinson, there is no requirement for the landscaping to screen the development from the RSL car park. I accept Mr Rollinson's evidence that the overall landscape design and the natural drainage swales provide amenity to residents of the development, as well as contribute to habitat creation for native indigenous plants and birdlife, which supports the broader objective of enhancing biodiversity. The landscaping proposed is therefore both viable and adequate.

[44]

Conditions of consent

There is a dispute between the parties on a number of the conditions of consent. In outlining each parties' position on the disputed conditions below, references to the condition numbers are to those in the draft conditions filed on 25 March 2024.
Firstly, the Council seeks the imposition of a condition of consent that requires a Construction Dewatering Management Plan to be submitted to the Council for approval prior to the issue of any construction certificate (condition 23). MH consents to the insertion of this condition, on the basis that the principal certifying authority (PCA) should be able to approve this plan. The Council submits that a PCA may not have the qualifications to assess the adequacy of the plan.
Given the breadth of the powers of a certifier under the Environmental Planning and Assessment (Development Certification and Fire Safety) Regulation 2021, including the enabling provision in cl 73 that allows certifiers to be satisfied of certain matters where conditions of consent require the council to be satisfied of those matters, it is appropriate that the function of approving the Construction Dewatering Management Plan also be permitted to be carried out by a PCA. The speculation concerning the qualification of a certifier is not sufficient to constrain the approval power to the Council. I have therefore added the words "or principal certifying authority" after the word "Council" to condition 23.
Secondly, the Council has included a condition that sets out the flood level requirements that must be incorporated in the construction certificate plans (condition 26). At (c), that condition requires the proposed development to be "designed to withstand the forces of floodwater, debris and buoyancy up to and including the Probable Maximum Flood (PMF) level plus 0.5m freeboard". The position of MH is instead that the flood level reference in (c) should be to the 1% AEP flood rather than the PMF.
The Council submits that the structural soundness criteria needs to be applied up to the PMF plus freeboard, in accordance with Schedule 8 of Chapter E13 of the WDCP. It says that this is required to satisfy evacuation criteria, as the evacuation response is on-site refuge.
In response, MH submits that the Council misunderstands the structural soundness criterion in Schedule 8 of Chapter E13. The criterion is: "2. Applicant to demonstrate that any structure can withstand the forces of floodwater, debris & buoyancy up to & including a 1% AEP flood plus freeboard, PMF plus freeboard if required to satisfy evacuation criteria."
MH points out that "PMF plus freeboard" is not required to satisfy the evacuation criteria, as neither of the evacuation criteria that apply to the development require the same. The applicable evacuation criteria are 3 and 4, which are: "3. Reliable access for pedestrians or vehicles is required from the building, commencing at a minimum level equal to the lowest habitable floor level to an area of refuge above the PMF level, or a minimum of 20sqm of the dwelling to be above the PMF level. 4 The development is to be consistent with any relevant flood evacuation strategy or similar plan."
MH points out that criterion 4 is satisfied by the Flood Emergency Response Plan, and criterion 3 is satisfied by providing for each unit an area of at least 20m2 above the PMF level on an upper floor, as described in the Flood Emergency Response Plan, so that shelter in place can occur.
I accept the submissions made by MH. The applicable evacuation criteria is to ensure there is an area of 20m2 above the PMF level. There is no requirement for evacuation above the PMF plus freeboard. Accordingly, to meet the structural soundness criterion it is sufficient that the proposed development be "designed to withstand the forces of floodwater, debris and buoyancy up to and including the 1% AEP level plus 0.5m freeboard". I therefore accept MH's proposed wording of the condition.
Thirdly, the Council has included a condition that requires the submission of a detailed civil engineering plan for the proposed drainage channel upgrade (condition 40). The condition specifies the design plans required to be submitted, and includes at (m) the requirement for a 2D flow analysis of the pre and post-development scenario for "the proposed system showing calculated flows, shear forces, velocity, and stream power, confirming that the proposed structural design of the drainage channel is suitable for the full range of storms up to and including the Probable Maximum Flood". MH has no issue with condition 40, but opposes the submission of the 2D flow analysis and says that (m) ought to be deleted.
The Council says that the 2D flow analysis is required to ensure that the works to the existing channel will be in accordance with good engineering practice and will be structurally adequate to withstand the forces during storm and flood events. MH instead submits that the condition is unnecessary in circumstances where the channel already exists. MH is concerned about the interpretation of the condition to require the channel to convey the PMF flow, in circumstances where it was only ever designed for lesser flows.
I agree with the submissions made by MH. A 2D flow analysis is not necessary in circumstances where the channel is already in existence and the extent of the works are for its maintenance and repair. Further, there is no basis upon which MH ought to be required to demonstrate that the "structural design of the drainage channel is suitable for the full range of storms up to and including the Probable Maximum Flood", given that there is no proposal for it to be upgraded in capacity to convey the full extent of the PMF flow. I accept that this component of condition 40 ought not be imposed.
Fourthly, the Council seeks the imposition of a condition of consent that requires a structural soundness report to verify that the development can "withstand the forces of floodwater, debris and buoyancy up to and including the Probable Maximum Flood (PMF) level plus 0.5m freeboard" (condition 155). MH agrees with the condition, but again says that the appropriate flood level reference should be to the 1% AEP flood rather than the PMF. For the reasons set out above at [235], the appropriate structural soundness criterion is for the structure to withstand the forces of floodwater, debris and buoyancy up to and including the 1% AEP level plus 0.5m freeboard, and the condition ought be modified accordingly.
Fifthly, the Council seeks the imposition of a condition that requires an engineer to submit a report that certifies that the 'as constructed' development "will not have any detrimental effects to adjoining properties or upon the subject land with respect to the loss of flood storage, changes in flood levels and alteration of flood conveyance, as a result of flooding or stormwater run-off" (condition 154). MH opposes this condition in its entirety.
The Council says that this condition is required to implement the requirements of Schedule 8 in Chapter E13 of the WDCP concerning flood affectation. These requirements are: "1 Engineers report required to certify that the development will not increase flood affectation elsewhere, includes medium & high density residential proposals. 2 The impact of the development on flooding elsewhere to be considered, includes low density residential."
These requirements are in the alternative for residential development in the Medium Flood Risk Precinct, such that only one of them needs to be satisfied with respect to the proposed development. They are operative by way of Section 6.4.3 of Chapter E13, which is concerned with the assessment of a development application. That assessment against the provisions of the WDCP has been carried out above at [107] to [129], based on the specific flood modelling that was undertaken by Ms Smith, and outlined in multiple flood reports, including a report dated 20 October 2023 and a supplementary report dated 14 December 2023 to support the joint report. As such, I have considered the impact of the development on flooding elsewhere in accordance with criterion 2, and found that the proposed development is acceptable. The proposed condition operates to require an engineer to undertake a further assessment of this same impact. It is simply not appropriate to require a further assessment of an impact that has already been fully considered in the assessment of the development application, in circumstances where criterion 2 has already been met in the development assessment process. The condition will not be imposed.
Sixthly, the Council seeks the imposition of a condition that requires a restriction to be registered on the title of the site to allow for "onsite manoeuvrability" (condition 170). MH opposes the condition in its entirety. The terms of the instrument are specified in the condition to be as follows: "The registered proprietor of the lot burdened must provide sufficient manoeuvring area for vehicles and plant required for monitoring, maintenance, and renewal of the tanked basement systems".
The Council says that this condition is required as the issue of access was not addressed on the plans, and the restricted area will need to be specified by a diagram and established on title to protect ongoing access.
The condition is entirely inappropriate. I accept the submission made by MH that a restriction on title is reserved for creating or modifying interests in land, such as rights of way and easements. A restriction on title is not appropriate for the imposition of an obligation concerning the use of an area of land or as a substitute for something that can be dealt with as a condition on the carrying out of development (Macdonald v Mosman Municipal Council (1999) 105 LGERA 49). Further, it is axiomatic that, if a strata manager or owners corporation is required to carry out maintenance on any part of the development, it will need to provide access for that to occur. It is unnecessary for it to be required as a restriction on title.
The conditions of consent provided by the parties have been amended to reflect my findings above, and are contained in Annexure A to the orders below.