Genamson Holdings Pty Ltd v Moreton Bay Regional Council
[2017] QPEC 56
•11 September 2017
PLANNING AND ENVIRONMENT COURT
OF QUEENSLAND
CITATION:
Genamson Holdings Pty Ltd v Moreton Bay Regional Council [2017] QPEC 56
PARTIES:
GENAMSON HOLDINGS PTY LTD
(Appellant)
v
MORETON BAY REGIONAL COUNCIL
(Respondent)
FILE NO/S:
3265 of 2016
DIVISION:
Planning and Environment
PROCEEDING:
Appeal
ORIGINATING COURT:
Planning and Environment Court of Queensland
DELIVERED ON:
11 September 2017
DELIVERED AT:
Brisbane
HEARING DATE:
30, 31 January, 1, 2, 3 February, 10, 27 March and 24 April 2017
JUDGE:
Rackemann DCJ
ORDER:
The appeal is adjourned to allow the parties to formulate conditions of approval
CATCHWORDS:
PLANNING AND ENVIRONMENT – APPLICANT APPEAL – REFUSAL OF EXTENSION SHOPPING CENTRE – proposal for suspended slab supported by piers over waterway – whether proposal would have unacceptable impact on flooding/stormwater – the significance of the potential for the proposal to catch debris – whether the proposal appropriately responds to the flood hazard constraint on the site – where the council’s infrastructure planning includes a detention basin in the vicinity of the site – whether the proposal would potentially prejudice the council’s infrastructure planning – where that can be addressed by conditions – whether the detention basin could be co-located with the development – where construction could be delayed to give the council the opportunity to promptly complete its acquisition of the site
COUNSEL:
T P Sullivan QC with M J Batty for the appellant
A N Skoien for the respondent
SOLICITORS:
HWL Ebsworth for the appellant
Moreton Bay Regional Council Legal Services for the respondent
Introduction
This applicant appeal is against the Council’s refusal of a development application to facilitate the extension of the existing Heritage Plaza Shopping Centre, which lies on the western side of Morayfield Road at Caboolture South. The existing shopping centre is located at 134/140 Morayfield Road and comprises a lettable area of 3,035m². The extension would increase that by 4,375m², bringing eight additional tenancies varying in size from 205m² to 2,750m², together with 225 further car parking spaces. The extension would be effected in the vacant, low lying, western part of the site which has an area of approximately 12,196m2 and would sit atop a suspended slab at ground level supported by piers. A waterway, namely a tributary of Sheepstation Creek, traverses the site.
The locality
The site is located in an existing commercial and retail area, which extends along both frontages of Morayfield Road. The site otherwise lies within a broader urban context. To the immediate south lies an IGA Supermarket development which is, in part, developed on a suspended slab on piers, partially over the same waterway which traverses the subject site. To the west lies a retirement village. To the south-west lies a park (Kate McGrath Park), which lies at the confluence of drainage lines. There is an urban residential catchment generally to the west.
Timing of the application
The development application was made on 30 March 2015, during the life of the Caboolture Shire Plan 2005 (2005 planning scheme). The Moreton Bay Regional Council Planning Scheme 2016 (the 2016 planning scheme) took effect on 1 February 2016. The development application was refused on 15 August 2016.
The assessment regime
This appeal proceeded by way of hearing anew, made under the Sustainable Planning Act 2009 (SPA). The onus lies upon the appellant. Having been made during the life of the 2005 planning scheme, the development application is assessed and decided under that scheme. It is code assessable under that scheme and accordingly is to be assessed having regard to ss 313(2) and (3) of the SPA and decided in accordance with ss 324 and 326 of SPA. The court’s decision must not conflict with a relevant instrument (including a planning scheme) unless there are sufficient grounds to justify the decision. Grounds are matters of public interest. The court may give such weight as it considers appropriate to the 2016 planning scheme, conflict with the 2016 scheme however, does not engage s 326.[1]
[1]Sustainable Planning Act 2009 (Qld) s 495(2).
The issues
The issues in the appeal were identified by reference to the Council’s reasons for refusal, and the appellant’s nominated grounds, which it contends are sufficient to justify approval in the event of any conflict with the 2005 planning scheme.
The Council’s reasons for refusal relevantly included those which assert that the proposal would be inappropriate in relation to:
(i) stormwater and flooding issues; and
(ii) infrastructure planning, in particular the potential for the proposal to prejudice implementation of Council’s planning for the broader management of stormwater/flooding by the construction of a future regional detention basin in the vicinity of the site.
Those two issues were the refusal issues upon which focus centred in the appeal. Other refusal issues fell away. In particular, it was common ground that ecological issues could be dealt with by way of conditions, particularly as to the provision of an ecological offset.
The conclusion that the proposal is otherwise generally acceptable is consistent with the second joint expert report of the town planning experts in which the following point of agreement was recorded:
“The planners agree:
(a) the site is appropriately zoned;(b)the site is situated within a broader and local commercial precinct;
(c)the site is currently used for the same purpose, with the proposal representing an extension on the same site of that same purpose;
(d)adjoining land is already fully developed, with the proposal representing logical infill development in that context;
(e)the ecological experts agreed in the JER that the site contained some environmental values that would be lost as a result of the proposed development;
…
(g)to the extent (ecological) offsetting is required, it can be conditioned as part of an approval; and
(h)conditions can be imposed to address all other overlay and practical planning considerations, as is usually the case for urban infill development of this nature.”
For the reasons discussed later, the infrastructure planning issue, although initially pursued as a refusal issue, was ultimately accepted to be capable of being dealt with by way of conditions if necessary.
Grounds
The grounds upon which the appellant relies as sufficient to warrant approval in the event of conflict with a relevant instrument were summarised as follows:
(a) there is an economic and town planning need for the proposed development;
(b) the proposed development would provide diversity and choice in respect of commercial and retail outlets in the locality;
(c) approval of the proposed development would result in an efficient use of well serviced and well located land;
(d) approval of the proposed development would reinforce a compact form of settlement, resulting in improved efficiency and use of existing infrastructure in the surrounding area;
(e) the proposed development is of a similar size and scale to existing developments in the local area and is therefore in keeping with community expectations;
(f) the proposed development represents an excellent opportunity for infill, commercial and retail development in the location which is served by significant levels of private and public infrastructure supporting commercial and retail uses, and
(g) approval of the proposed development would not generate any unacceptable impacts.
Those grounds were generally supported by the evidence of Mr Reynolds (the town planner engaged by the appellant) and Mr Norling (the economist engaged by the appellant). Mr Norling expressed the view that there is a strong level of community, economic and planning need for the proposed development for the following reasons:
(a) the subject site forms a convenient and integral part of the dominant Caboolture/Morayfield principal Regional Activity Centre, which is designated to serve a regional population that forms an important part of Greater Brisbane’s northern growth corridor;
(b) the proposed development would focus employment on the vibrant and accessible Caboolture/Morayfield Regional Activity Centre;
(c) the proposed development would consolidate and integrate compatible uses to optimise the use of land within an established higher order centre;
(d) the proposed development would contribute to a more compact urban form and strengthen the network of activity centres by expanding the mix of businesses and services conveniently available in the Region’s highest order centre;
(e) the proposed development would serve the Morayfield Catchment population, which is projected to increase at 2.57% per annum over the next 15 years, significantly above the rates projected for the Moreton Bay Region and Greater Brisbane;
(f) the proposed development would satisfy a small part of the Morayfield Catchment’s increase in demand for retail floor space over the next 15 years, which is estimated at a total of 203,000m2, of which about 71,000m2 would be directed to the Caboolture/Morayfield Principal Activity Centre;
(g) interest has been received from prospective tenants wishing to lease 75% of the proposed floor space, which is considered to be strong evidence of need, especially given that a formal marketing campaign has yet to commence and the current successful anchor tenant wishes to expand into the proposed major tenancy in order to better satisfy its existing customer base;
(h) the proposed development would increase the range, convenience and competition of retail facilities available to the Morayfield Catchment, and
(i) the proposed site is centrally located within the northern part of the Morayfield Centre, such that its development would contribute to the consolidation, integration, vigour, vibrancy and convenience of the Centre.
I accept that the subject proposal would assist in meeting a need for further development of the broader Regional Activity Centre over time and would generally have the benefits otherwise referred to by Mr Norling. It was submitted for the respondent however, that the appellant had failed to demonstrate a public or community need which could not be met by another development elsewhere. I accept that there is a level of need, although I do not regard the need case as particularly strong. In any event:
(a) the appellant relies upon its grounds in the event that conflict is found with a “relevant instrument”, for the purposes of s 326 of SPA which, in this case, is the 2005 Planning Scheme;
(b) insofar as the stormwater/flooding issues are concerned:
(i) the respondent asserts conflict with 1 DEO of the 2005 Planning Scheme, but for the reasons discussed later, I am satisfied that:
A. the proposal will have no unacceptable impact in terms of flooding/stormwater, and
B. there is no conflict with the nominated DEO in the 2005 Planning Scheme.
(ii) any conflict with the provisions of the 2016 Planning Scheme does not engage s 326 of SPA.
(c) insofar as the infrastructure planning issue is concerned:
(i) the respondent’s concern relates to the potential for the proposal to remove the subject site as a potential site for the location of a planned regional detention basin, and
(ii) it was ultimately accepted that the respondent’s concern, to the extent it is legitimate, can be accommodated by a condition of approval, rather than by refusal of the application.
In the circumstances, there is no need for the appellant to rely on its “grounds” to justify an approval.
Stormwater/flooding impact
It has already been observed that the subject site is relatively low-lying and is traversed by a tributary of Sheepstation Creek. The site lies towards, but not at, the downstream extremity of the catchment of the waterway which enters the site at its southwest corner and exits at its north-eastern corner, via culverts. It then proceeds east, via the culverts, under Morayfield Road, under the retail and commercial premises to the east, and out into the natural waterway to the east. The waterway is fed from a significant catchment, primarily from the west.
The proposed development would extend above the areas which would be inundated in times of flood, including the waterway. It is however, proposed to be, in effect, substantially vertically separated from those areas by being built on a platform, supported by piers, so as to minimise the interference with those parts of the site or with stormwater/floodwater. The piers are to be placed at least 10m apart and are to be kept clear of the high hazard flow area. It is proposed for there to be some earthworks to achieve the development, but this would result in a net increase in flood storage within the site of in excess of 3000m3 in the 100 year ARI event.[2]
[2]Exhibit 11, page 13.
It was contended, on behalf of the respondent that, notwithstanding the appellant’s endeavours to design the proposal to take account of potential impacts on stormwater and floodwater, it had nevertheless failed to demonstrate that the proposal would have no significant adverse impact. Consequently, it was contended that the proposal conflicts with Desired Environmental Outcome (c)(iv) of the 2005 planning scheme, which speaks of the adverse effects of naturally occurring and man-made hazards on the natural environment and human communities being minimised.
The 2005 Planning Scheme was supported by, amongst other things, planning policy 19, which related to stormwater. It provided a guide to the council’s requirements for information that should be included in a flood study to address stormwater quantity and quality. Relevantly to quantity, it sought a certified flood study from a registered professional engineer to determine, amongst other things, whether the development is likely to cause any nuisance to adjoining, upstream or downstream properties or whether the cumulative impact of development is likely to cause any adverse impact on other properties. The policy provided that the flood study should be based on flood height data up to and including a 100 year ARI storm event.
The impact of the proposal in terms of stormwater and flooding was examined by two suitably qualified engineers, namely Dr Johnson (who was engaged by the appellant) and Mr Clark (who was engaged by the Council). Those experts participated in a joint meeting and report process, in accordance with the usual practice in this court.
In their second joint report, the experts agreed that the sub-model of the proposed development site and the immediate vicinity, as then established by Dr Johnson’s firm, was generally suitable and that the proposed solution:
“With reference to the previous planning scheme as outlined in the Flood Report provides a satisfactory outcome in respect of flood level increases (i.e. flood level increases beyond the boundaries of the site are acceptable) in the absence of debris loading, when considering the Q100 event. However, it is agreed that this analysis does not consider debris loading, and there is disagreement… as to whether this further analysis is required.”
The conclusion of the Flood Report referenced in that point of agreement included that “the proposal development does not cause an actionable adverse impact on flood levels external to the site.” Accordingly, subject to the issue of debris loading, there was agreement between the two nominated experts that the proposed development was acceptable in terms of the 2005 planning scheme.
Mr Clark’s residual concern was that the proposed development could result in unacceptable upstream flood level increases if flood debris came to create a blockage within the pier arrangement and/or the underside of the development platform. Dr Johnson, on the other hand, did not consider blockage by reason of debris to be likely, and disagreed with Mr Clark’s assessment of the potential impact and significance of debris.
It was pointed out for the appellant that there is no provision of the 2005 planning scheme, or the relevant planning scheme policy, which expressly requires a consideration of debris loading. That does not however, justify ignoring Mr Clark’s concern. The relevant provision of the planning scheme does not provide any detail in relation to the matters to be considered. The planning scheme policy provides some greater detail, but is only a guide and does not purport to be a comprehensive list of every matter which could potentially be relevant to a consideration of whether a given development is, in the circumstances, likely to cause a nuisance or adverse impact.
The concern about debris in this case should however, be put into perspective. In that regard:
(i) Not all catchments have the same degree of risk in terms of debris or, more particularly, debris of a kind likely to create a blockage across a well-spaced and placed pier arrangement. The subject catchment, as Mr Clark acknowledged,[3] is relatively highly urbanised. In the second joint report, Dr Johnson expressed the view that any debris would largely be urban detritus and not be expected to cause significant disruption to flow.[4] In his trial report, Mr Clark spoke of a “significant” potential for debris (both vegetation and urban detritus) to be generated within the catchment.[5] Whilst at trial he maintained that there is a “foreseeable risk”,[6] he conceded in cross-examination[7] that “in terms of standard methodologies… this catchment comes up as generally a low risk catchment for debris.” I am satisfied that the catchment is indeed, relatively low risk in this regard.
[3]T6-17.
[4]Exhibit 11, para 2(a).
[5]Exhibit 19, p 19.
[6]T6-29.
[7]T6-16.
(ii) Immediately to the west of the IGA development and to the southwest of the subject site, but east of Adelaide Drive, lies Kate McGrath Park. That is a relatively modest park with a small number of mature trees in an otherwise open grassed area. The trees are grassed to their roots (they do not sit on a river bank with scour). Mr Clark accepted that this area is not one which has a high potential to produce fallen trees to contribute to debris.[8]
(iii) Significant vegetation is otherwise more removed from the site in the upstream area to the west of Adelaide Drive. The flood prone part of that area is again relatively flat and features mature trees grassed to their trunks. There is no formally defined creek line (or associated scour zones). There is some more dense vegetation in a more natural state to the south of the flood zone that would be affected by low-velocity rainfall runoff only. Mr Clark accepted that, in the circumstances, there is a low prospect of trees in this area becoming debris as a result of flooding.[9]
(iv) Mr Clark’s residual concerns about vegetation was not related to trees becoming debris as a result of stormwater/floodwater but rather by reason of high wind and/or lightning strike. He was also concerned about cars potentially becoming washed off a road, presumably Adelaide Drive. Mr Clark made enquiries of the Council about whether it kept records of complaints or problems in relation to previous instances of that kind, but was unable to be provided with any such information. The Adelaide Drive crossing would be expected to be closed in the Q100 event.[10]
(v) The concern about debris relates to the proposal potentially creating an adverse upstream impact by reason of a blockage which would not otherwise occur (in a way which caused a like effect) in any event. As Dr Johnson identified however, there are, in any event, numerous culverts and grated inlets in this catchment already, any or all of which could catch such debris if it occurs. It was pointed out by Mr Clark that blockages downstream of the site may not have the same impact, but two of the examples given by Dr Johnson exist upstream as follows:
(A) There is a road culvert on Adelaide Drive approximately 100m upstream of the land. There is also a guardrail which runs above the level of the road surface. This culvert and guardrail would present a significant impediment to the transmission of debris further downstream. The Q100 flood level at Adelaide Drive is less than the height of the guardrails.[11] Mr Clark accepted[12] that if a tree were to fall, by reason of high wind or lightning strike, to the west of Adelaide drive and be caught up in the stormwater/floodwater, it would likely catch on the Adelaide Drive guardrail. Whilst there was no engineering evidence of its structural strength, it is obviously a substantial structure, permanently attached to the ground, made of steel, located on both sides of the road and non-collapsible.[13] It presents as at least a significant potential impediment;
(B) The immediately adjoining IGA development to the south is developed on piers over the same watercourse immediately upstream of the subject site. Its pier arrangement features only 5m spacings. As Dr Johnson pointed out, it is an obvious catch point for any major debris. He pointed to its existence as consistent with his view that debris is not considered to be a significant concern in this catchment. Mr Clark, who considers the IGA pier system is “not a good design”, and one he would not propose,[14] also conceded that it is a likely spot to catch any significant debris which happened to make its way through to that point, although he thought there was some residual risk of debris making its way to the subject site notwithstanding.[15]
(vi) Whilst the proposal is not cantilevered, and would introduce a greater number of piers across a broader area, the arrangement under the subject proposal features relatively generous spacing of at least double that which is provided for under the adjacent IGA development. The proposal is for a minimum spacing of 10m between piers and no pier will be placed within the high flow channel of the waterway.
[8]T6-18.
[9]T6-20.
[10]T6-34.
[11]T6-28, 33.
[12]T6-21.
[13]T6-8.
[14]T6-26.
[15]T6-60.
Given the nature of the catchment, the potential for debris to be caught in any event before it arrives at the site, the relatively open pier structure and strategic placement of piers, the risk of the pier system on the subject site causing significant additional blockage by way of debris is, I find, relatively low.
Each of the experts considered the impact of a potential blockage in the event that it did occur. Initially, Mr Clark did so by revising Dr Johnson’s model simply by increasing hydraulic roughness to 0.3. This, in effect, modelled a partial blockage across the whole development.[16] That is an unrealistic scenario, given the nature of the development and, not surprisingly, resulted in significantly inflated and overstated predictions of increases in flood levels as a consequence of the development. It is unnecessary to delay upon the approach because Mr Clark, in the course of cross-examination, readily conceded that it was better to consider specific debris scenarios.[17] Each of Dr Johnson and Mr Clark considered some such scenarios.
[16]It is the value which would be adopted for a solid building located across the site. See T6-56.
[17]T6-59.
Dr Johnson’s analysis considered blockages in areas more towards the downstream part of the site and out of the high hazard area, where no piers will be placed. He was criticised on that basis. It is unnecessary for me to discuss those criticisms further because, for the reasons which follow, I am satisfied that the proposal will not have an undue impact even having regard to Mr Clark’s more conservative scenario.
Mr Clark, on the other hand, chose what he acknowledged to be the worst case blockage scenario to give the highest level of upstream increase.[18] That is, a blockage across the high velocity part of the channel (albeit that no pier is, itself, within that part of the channel) near the upstream entry of the site towards the southwest corner proximate to the IGA site. It is also the relatively deep part of the channel. Having selected that part for the scenario, Mr Clark then chose to model a complete (that is 100 percent) blockage for a 10m section. That is a very conservative scenario, which makes the following assumptions:
(i) debris, capable of extending across a 10m span width, is produced upstream in the catchment;
(ii) if it is produced west of the eastern side of Adelaide Drive, it nevertheless makes its way past the culverts and guardrails of Adelaide Drive;
(iii) notwithstanding that the higher velocity part of the channel flows directly under the IGA development before emerging on to the subject site to the point of the assumed blockage, the debris either gets through that tighter pillar arrangement under the IGA before getting blocked at the more widely spaced piers at the assumed blockage point on the subject site or, alternatively, skirts around the IGA and enters the site outside of the high flow channel before entering it in time to create a blockage at the assumed spot.
(iv) Not only does the debris create a blockage at the assumed point, but it also creates a complete (100 percent) blockage for the entire 10m width for the entire depth of that section such, such that the entire section is impermeable. Mr Clark conceded, in cross-examination, that “I absolutely accept that you won’t have a metal sheet that 100 percent blocks those piers”.[19]
[18]T6-29, 30.
[19]T6-29.
The evidence of Dr Johnson was that, in the area of high velocity/risk, the piers either are or could be placed further apart, to further reduce any risk of blockage. That is a matter which could be addressed in conditions. Mr Clark modelled a 10m blockage.
There was, it seems, some attempt by Mr Clark to compare the consequences of his assumed blockage to those which might otherwise occur at the IGA and also at the culverts at the north-eastern part of the site. Unfortunately, they were not very useful comparisons, because he did not model similar blockages. Instead of modelling the same 10m wide debris which, absent the subject development, could be caught, in any event, at the IGA, Mr Clark blocked a 5m blockage at that location. Insofar as the north-eastern culvert is concerned, he modelled only a 50 per cent blockage.
Mr Clark’s hypothetical complete blockage of the most sensitive cell of the proposed development on the subject site produced results which were far from alarming.[20] It revealed that, in such circumstances, there would, as a consequence, be some increase in areas already subject to flood, but no inundation of any habitable building as a consequence. The greatest increase in levels external to the subject site would be below the suspended slab of the piers on the IGA site. That would appear to raise no concern. It would also potentially cause an increase of between 1 and 2 cm in the levels in the already flooded Kate McGrath park east of Adelaide Drive and, to a very minor extent, within the yards of some residential properties which adjoin that park. Mr Clark accepted that there would be no increased damage associated with that afflux.[21] To the west of Adelaide Drive the level of afflux is generally 1cm or less which, it was common ground, is not of significance.
[20]Even ignoring an afflux which might otherwise occur in any event if, in the absence of the subject development, the debris created a blockage downstream.
[21]T6-33.
The Adelaide Drive crossing is already inundated during the Q100 year flood. At its centre, it is inundated by between 75cm and 1m and would be expected to be closed to traffic due to the level of hazard.[22] In the event of a blockage on the subject site as modelled by Mr Clark, there would be some additional flooding, but the increase would be relatively minor (of the order of 10 or 11mm).[23]
[22]T6-34.
[23]T6-35, 6-87.
Whilst I understand Mr Clark’s reluctance to see floodwater on an already flooded and hazardous road increase or indeed to see flood levels on the property of third parties (adjacent to Kate McGrath Park) increased by more than the 1cm generally accepted by hydraulic engineers as within a “no-worsening”, there are some things which need to be borne in mind. Firstly, as Dr Johnson pointed out, the proposal has not been designed to produce greater than 1cm of afflux in a 100 year event. It has been designed to achieve a no-worsening (absent debris). The scenario which has been considered is in the nature of a sensitivity test, in the event that a blockage by way of debris also occurs.[24] Secondly, the likelihood of that afflux occurring is low, bearing in mind the nature of the catchment and the conservative nature of the scenario modelled. Thirdly, as Dr Johnson pointed out, the extent of afflux, if it were to occur, would not have undue adverse effects.[25] In those circumstances, I prefer Dr Johnson’s opinion that the proposal would not have an undue adverse impact in terms of stormwater and flooding.
[24]T6-87.
[25]T6-87, 88.
I find that the proposal does not conflict with DEO(c)(iv) of the 2005 planning scheme.
2016 planning scheme with respect to flood hazard
The respondent alleged conflict with provisions of the 2016 planning scheme with respect to flood hazard.
The subject site falls within the Morayfield Centre Precinct under the 2016 planning scheme. The overall outcomes for that precinct include the following:
“pDevelopment avoids areas subject to constraint… where development cannot avoid these identified areas, it responds by:
(i) adopting a ‘least risk, least impact’ approach when designing, siting and locating development in any area subject to a constraint… to minimise the potential risk to people, property and the environment.”
It was submitted that the proposal involves developing an area subject to a constraint, that is a flood hazard, and that even if it be assumed that the development could not avoid that constraint it did not adopt a “least risk, least impact approach” and did not provide an appropriate response to the flood hazard.
Flood Hazard is more particularly dealt with in the Flood Hazard Overlay Code. That Code applies to land in the Flood Planning Area identified on a flood hazard overlay map and includes land in the following sub-categories:
(a) High risk area
(b) Medium risk area
(c) Balance flood planning area
The subject site is identified on a flood hazard overlay map as containing each of those 3 sub-categories.
The respondent alleges conflict with overall outcomes b and c of the Flood Hazard Overlay Code under the 2015 planning scheme which seeks to avoid inappropriate development in high risk and medium risk hazard areas.
Overall Outcome (b) provides that development in the high risk area is to manage and mitigate the risk of flood hazard by ensuring that a material change of use is only for one of seven types of uses being a dwelling house, outdoor sport and recreation, park, permanent plantation, cropping, tourist park or a home based business. Further, pursuant to this provision, earthworks are not permitted to occur except where associated with a previous approval.
Overall Outcome (c) provides that development in the medium risk area is to manage and mitigate the risk of flood hazard by ensuring that the use of the premises is limited to eight types of uses, being those uses set out above for Overall Outcome (b), but in addition, provides that non-residential uses where not involving a vulnerable land use (flood and coastal) can be accommodated. Again, the provision provides that earthworks do not occur except where associated with a previous approval.
The overall outcomes are designed to achieve the purpose of the flood hazard overlay code which is to:
“(a) identify whether an area is subject to a flood hazard;
(b)minimise the risk to life, property, community, economic development and the environment from the flood hazard by:
(i)limiting development in an area of extremely unacceptable, intolerable risk of flood hazard to avoid the risk of the flood hazard;
(ii)managing development in an area of unacceptable, intolerable risk of flood hazard to mitigate the risk of flood hazard;
(c)ensure that development does not increase the potential for adverse impacts on the premises or other premises, public land, watercourses, roads or infrastructure without appropriate mitigation.”
Insofar as the High Risk area is concerned, it was pointed out, on behalf of the appellant, that whilst its proposed use is not one of those contemplated within such an area under the 2015 planning scheme:
(i) the proposal vertically separates the development from the area of high risk by suspending it, such that it is immune from flood for the Q100 and even for the Q1000 events;
(ii) there will be no piers or associated earth works in the actual area of high risk – noting that the evidence established that the mapping of the high risk area in the 2016 planning scheme is somewhat inaccurate.
It was submitted that, in those circumstances, the court ought find that there is no conflict with Overall Outcome (b). That was based on a contention that the High Risk area should not be identified as applying to that part of the airspace above the surface of the land where the proposed development would be suspended. It is unnecessary however for me to deal with that issue of construction. The provisions of the 2016 planning scheme area a matter of weight only in the assessment of this application. Even assuming that the three-dimensional approach to construction contended for on behalf of the appellant is incorrect, I would not be minded to refuse the development on the basis of the resulting conflict, given that the proposal effectively physically separates the development from the flood risk.
The use does fall within the range of uses contemplated in the medium risk area.
Insofar as earthworks are concerned, the provisions of the 2016 Planning Scheme for both the high and medium risk areas provide that earthworks do not occur except where associated with a previous approval. It was submitted for the appellant that this should not be constructed as a prohibition on new approvals, but rather as a prohibition on earthworks without approval. In any event, the provisions of the 2016 scheme are a matter of weight only. In this case the earthworks are relatively modest[26] and achieve a net increase in flood storage.
[26]Obviously greater earthworks will be involved if the site is used for a regional detention basis as council contends it should be for infrastructure planning reasons.
Mr Clark raised concerns about covering the area of hazard with a slab. He pointed out that the proposal offered a confined space for anyone underneath who might need to escape, but Dr Johnson pointed out that the slab could, and in his view should, be raised to afford a comfortable head height in any event. Mr Clark raised a concern about a lack of casual surveillance, but accepted that this part of the site has low surveillance in any event. Issues of safety associated with covering the site with a slab, and the means by which those concerns can be addressed through conditions are discussed later in the context of a suggested detention basin.
I am satisfied that the proposal, which separates persons and property from the potential flood hazard by vertically removing development clear of the floodwater, whilst sensitively placing the supporting piers in the areas beyond the highest risk, whilst maintaining and modestly increasing on-site flood storage, appropriately responds, or could be conditioned to appropriately respond, to the flood hazard constraint on the site and appropriately minimise the risk.
Infrastructure planning/detention basin
In 2009 a report was prepared by the Moreton Bay Regional Council’s Drainage Waterways and Coastal Planning Unit (the 2009 report). The purpose of that report was to identify the stormwater quantity trunk infrastructure required to meet the future development demands in the Caboolture district.[27] The 2009 report identified many items of future trunk infrastructure, one of which was a proposed 21,000m³ detention basin in Morayfield described as being on Sheepstation Creek and given the code SSC_DB_3. It was described as requiring an area of 12,600m² which, as it happens, is close in size to the vacant rear portion of the subject land which is proposed for development. The required land was described as being privately owned. The total estimated cost was $1,525,650, composed of a land cost of $387,450 and a construction cost of $1,138,200. It was then projected to be built in 2012.
[27]Exhibit 6 p 223.
In 2011, the Council adopted an infrastructure charges resolution (the 2011 resolution) which referenced a number of future infrastructure projects which were the basis for the calculation of charges. One of those projects was SSC_DB_3, which was described as Sheepstation Creek detention basin and shown on the relevant map symbolically by a coloured box straddling the boundary of the subject site and the IGA site to the south. There followed further iterations of the infrastructure resolutions prior to the coming into force of the 2016 planning scheme. The same detention basin was included in each of those iterations and symbolically shown on the accompanying plans, although a future water quality treatment device was symbolically added in the area of Kate McGrath Park to the southwest. The estimated year of completion was moved to 2015.[28]
[28]See exhibit 6, pages 113, 176.
The 2011 infrastructure resolution stated that it did not form part of the planning scheme. Further, it was conceded, on behalf of the respondent, that neither the 2011 resolution nor any of the subsequent iterations constituted a relevant instrument under ss 313 and 326 of the SPA for the purpose of assessing and deciding the subject development application. The respondent did however, point to its infrastructure planning in the context of alleging conflict with DEO(c)(ix) of the 2005 Planning Scheme, which provided as follows:
“The efficient and effective use and provision of physical and social infrastructure in the shire is maximised.”
Further, since the application was made, the 2016 planning scheme has come into effect and its provisions are a matter of weight in the determination of this application. The Council’s infrastructure planning is now embodied in the priority infrastructure plan (PIP) which forms part of the 2016 planning scheme. The purpose of the PIP is to:
(a) integrate and coordinate land use planning and infrastructure planning;
(b) ensure trunk infrastructure is planned and provided in an efficient and orderly manner.
The SSC_DB_3 detention basin is shown on the PIP stormwater network map.
The respondent submitted that the appellant has failed to show its proposal will not have an adverse effect on the Council’s longstanding planning for the provision of planned infrastructure, including as most recently reflected in the PIP.
It was initially contended that the Council’s concern in this respect, if otherwise valid, was a reason for refusal of the development application. The potential for impact upon the realisation of Council’s infrastructure planning however, is related not to an approval of the application per se, but rather to the construction of the development across the site prior to the Council having the opportunity to utilise it for the SSC-DB-3 detention basin. It has already been noted that the council’s infrastructure planning initially contemplated the basin being constructed by now. The council has already given notice of its intention to resume the subject land for the purposes of constructing the basin. In response to a question from the bench, it was accepted, on behalf of the respondent, that its concern would be adequately addressed by condition of approval which postponed the right to commence construction of the development for a reasonable time to give Council the opportunity to complete the acquisition process. Senior counsel for the appellant also embraced the suggestion that such a condition could address any potential prejudice, although reserved the right to be heard about the time to be allowed. Further it was contended for the appellant that any potential prejudice to the council’s infrastructure planning could be met by giving the council the opportunity to impose a different condition.
Ultimately then, at worst for the appellant, this issue goes to conditions of approval rather than to refusal of the application.
The appellant’s primary submission was that no condition to address the asserted potential prejudice ought be attached to an approval of its application, because the site is now simply irrelevant to the Council’s planning for the proposed detention basin, as part of its broader infrastructure planning, as reflected in the PIP. The basis for that submission is the PIP stormwater map, which shows the SSC_DB_3 detention basin by a circular symbol near the common boundary of the subject site and the IGA site. No part of the symbol however, intrudes over the boundary of the appellant’s site.
The nature and purpose of the map must however, be kept in mind. It shows a planned future infrastructure network, rather than a series of existing or proposed projects which have been the subject of detailed design. Whilst the network is depicted over a cadastral base, it does not depict the precise size, shape, area, dimensions or exact location of individual components of the network. The small circle which appears beside SSC_DB_3 could not be anything like the size and shape of a detention basin to serve as trunk infrastructure as contemplated. That which is shown is symbolic and indicative. Relevantly, for present purposes, it reflects the Council’s infrastructure planning for a detention basin in that vicinity.
Given the development which has now occurred over the IGA development to the south, the subject site presents as the obvious site, in the vicinity, which is capable of accommodating the planned detention basin. Council’s interest in acquiring the site and the Council’s concern about the prejudicial effect which development otherwise on the subject site may have on the realisation of its planned infrastructure is understandable. The appellant however, pointed to alternatives to achieve the infrastructure whilst permitting development to proceed.
In his further statement of evidence, Mr Clark pointed out that the subject site is unique in its location at the junction of three separate sub-catchments, such that a detention basin, located on the subject site, can mitigate flows from all three tributaries, prior to flow reaching Morayfield Road. Dr Johnson did not cavil with that, but pointed out that on appropriately sized and located detention basin somewhere further upstream, on one or more catchments, rather than here, could also achieve appropriate attenuation.[29] That however, is not the Council’s infrastructure planning and Mr Clark pointed to the potential inefficiency that could result from such an approach.[30]
[29]T2-89.
[30]T5-26.
Kate McGrath Park, which lies to the immediate southwest, provides an opportunity to provide at least some of the detention basin function. It is, however, in accordance with the PIP, proposed to be developed with a stormwater quality device, most likely a bio remediation device. Dr Johnson pointed out that a detention basin can be co-located with such a device. Mr Clark accepted as much. As he pointed out, and Dr Johnson acknowledged however, there are issues with collocating such devices. Those include as to functional (including the potential for scour and erosion issues) and increased maintenance issues.[31] He accepted that, if space were not an issue, he would try to separate the devices[32] with the high flows diverted to the detention basin.[33] That is consistent with what is shown on the PIP Stormwater map.
[31]T3-42, 43.
[32]T3-44.
[33]T3-45.
Quite apart from the functional and maintenance issues, there is also, as Dr Johnson acknowledged, a potential limitation in terms of capacity. The park, at about 8000m2,[34] is significantly smaller than the subject site, thereby limiting the size of the basin that could be achieved. If something of about the order of 21,000m3 were required (a matter discussed later), then the park would need to be excavated below the level of the existing outlet in order to achieve that volume. If that complication were to be avoided, then only part of the detention volume would able to be achieved within the park, with Council having to look to implement measures elsewhere to find remaining detention volume.
[34]T2-67.
In those circumstances, attention shifts back to the subject site to achieve a regional detention basin in this vicinity. The appellant’s preferred option (supported by Dr Johnson) is that it be achieved on the subject site, underneath the development. This option would see the detention basin being constructed as trunk infrastructure, pursuant to a condition of approval, prior to construction of the appellant’s development over the top and subject to an appropriate infrastructure set off or refund. Appropriate arrangements, including easements, would need to be put in place to facilitate Council’s ongoing access to, and maintenance of, the detention basin.
In the course of the hearing and in submissions, Mr Clark and counsel for the respondent raised concerns about that option in various respects. In the course of addresses however, counsel for the respondent made it clear that the respondent would wish to at least consider that option in the event that the court were to find a co-located basin to be an acceptable option.
The appellant’s preferred alternative condition can be seen in light of the council’s information request of 14 May 2015, in which it drew attention to the infrastructure charges resolution, asserted that the “infrastructure has been identified as a regional device for the catchment and is to have a total capacity of 21,000m3” and asked the then applicant (now appellant) to demonstrate how a detention basin, with a total capacity of 21,000m³, could be achieved on the site, whilst still maintaining conveyance of stormwater conveyance across the site.
The response to that information request demonstrated that it is technically feasible to construct a detention basin of that size on the site. That, of course, involves excavation across the site, so as to provide the storage, whilst still providing a fall, towards the north-eastern end of the site, so that the site drains to the outlet at 7.0 AHD. That involves excavating the site from 8.3AHD to an average 7.5 AHD. The development could then be built over that basin.
The co-location option has the obvious potential benefit of providing a detention basin without prejudice to the potential for the appellant’s site to be developed in a way which I am satisfied is otherwise appropriate from a town planning perspective and provides some benefits as generally described in the appellant’s grounds. Mr Clark however, raised three concerns about the co-location option.
One of Mr Clark’s concerns relates to safety. Whilst there are other developments in the area which feature slabs supported by piers over waterways, Mr Clark was concerned about the safety implications of creating a regional detention basin covered by a slab. Of particular concern to him is the potential for people to be underneath the slab at the start of a rainfall event large enough to cause flooding such as to create a risk of drowning. His concern was exacerbated by the lack of visibility to persons potentially in trouble. He pointed out that this would require the site to be fenced, but that such an arrangement is contrary to best practice detention basin design and that the fence would potentially catch debris.
Dr Johnson acknowledged that, were the co-location option to be adopted then exclusion fencing would be required. He also acknowledged that the relevant section from the Queensland Urban Drainage Manual (QUDM) nominates the provision exclusion fencing as a “last resort”, with minimisation of safety risks through appropriate design being the first preference. He pointed out however, that the depth of water in a 21,000m3 detention basin on the subject site, as shown in the design provided in response to the information request, would be such as to trigger a requirement for fencing in accordance with QUDM, even if it were open. Mr Clark suggested that a standalone detention basin could potentially be designed in such a way that there were some areas of lesser depth which were unfenced. Dr Johnson contended that the site should, and likely would, be fenced off, if it were developed for either a standalone or co-located basin. It appears likely, that a detention basin on the subject site, if of the order of 21,000m3, would involve a level of fencing, whether it is co-located or freestanding.
Insofar as the concern about fencing creating debris issues is concerned, Mr Clark acknowledged that collapsible or swing fences could be used so as to dissuade people from entering the site without causing an issue in terms of debris blockage.[35]
[35]T6-43, 44.
Mr Clark also acknowledged, in the course of his testimony, that the exclusion of people from this part of the site could also be reinforced via conditions requiring both security surveillance of the underside of the slab and daily checks of the fencing.[36]
[36]T-44.
Mr Clark also acknowledged that a design response could be imposed by way of conditions to also ensure that there are means of escape for anyone who nevertheless finds themselves under the slab in times of a rainfall event. In that regard, as Mr Clark acknowledged, stairs could be provided from the detention basin to one way exit doors, made prominent by illuminated “emergency exit” signage at appropriate locations to provide such opportunities.[37]
[37]T6-41.
The presence of the slab will obviously impede surveillance, although the subject part of the site is one which currently has a fairly low degree of casual surveillance in any event.[38]
[38]T6-46; T4-62.
Whilst Mr Clark’s safety concerns are understandable, they are, on the evidence, substantially capable of being addressed by way of the imposition of conditions and do not of themselves make the co-location option unacceptable.
The next issue related to maintenance. Mr Clark pointed out that it will not be possible to see the underside of the slab from surrounding areas. Regular inspections will be necessary to determine whether or not there is debris which needs to be removed. The development as proposed (with no detention basin) provides for a working head height of only 1.6m. Working in such a space is not impossible but, as Mr Clark pointed out, is more resource intensive.[39] Dr Johnson suggested that the underside of the slope could be raised by 400 mm to provide a more comfortable working height. With greater excavation, to achieve a detention basin of 21,000m3 however, an ample head height (of 2.4m) should be available.
[39]T6-48.
That is not to say that the presence of a slab would not likely have some consequences for maintenance. For example, it makes under slab inspections necessary and introduces the need for cleaning any debris from around the piers that are introduced into what would otherwise be an open detention basin. It may limit the exit points to which debris has to be taken and access points for vehicles.[40] Dr Johnson accepted that it would involve a different maintenance regime under the slab, although he said that it was beyond his expertise to say whether it was greater or lesser.[41] He did however, acknowledge that it would be more difficult to remove sediment.[42] These are matters of convenience, and of efficiency.
[40]T6-49.
[41]T4-30.
[42]T4-30.
The third issue in relation to the co-location option relates to the benefit from the volume of storage that can be achieved. It has already been noted that the Council, by its information request, asked the appellant to demonstrate “how the identified trunk infrastructure, and detention basin with a total capacity of 21,000m3, can be achieved on the site whilst also maintaining conveyance of storm water drains across the site”. The appellant, by its response, demonstrated that is achievable. In practical terms[43] however, a greater capacity cannot be achieved.[44] Mr Clark claims that the appellant has failed to show that it can provide a sufficient quantity of storage to both provide the benefits of the trunk infrastructure being SSC_DB_3 and to mitigate the effects of its own proposal.
[43]Without excavating below the level of the outlet.
[44]T4-80.
A 21,000m3 co-located detention basin does not necessarily provide the same benefit for the broader catchment as a free-standing detention basin of the same size on an otherwise undeveloped site. That is because, as Dr Johnson acknowledged,[45] the development of the site increases its runoff characteristics and so, there is a need to compensate for the effects of the development itself. Accordingly, as Dr Johnson also acknowledged,[46] a co-located basin potentially needs to provide a greater volume if it is to provide the attenuation, for the broader catchment, which would otherwise be provided by a standalone detention basin. Further, if the benefits which could otherwise be achieved from a free-standing basin on the subject site were limited in some way, then the council would have to look to achieve that elsewhere.[47]
[45]T2-83.
[46]T4-110.
[47]T4-112.
Dr Johnson suggested that the appellant’s development should be viewed as part of the urbanisation for which the detention basin is to be provided, but he acknowledged, in the course of cross-examination,[48] that the model which was used for the purposes of the flood report assumed no increase in upstream flows onto the subject site and that it did so on the assumption that there will be sufficient detention of those upstream flows through appropriate detention mechanisms, one of which is the plan for a detention basin.
[48]T4-99, 100.
The extent of which the impacts of the development itself consumes the broader benefit which would otherwise flow from a 21,000m3 detention basin was the subject of debate. Dr Johnson pointed to the limited quantity of excavation required on the site, to achieve a no-worsening as modelled in the Flood Report for the subject proposal (without the co-located basin). Mr Clark however, opined that the effect of the development may be the consumption of the flood storage (including airspace) down to the excavated level of RL 8.3 AHD. In the absence of modelling which compares the performance of the co-located and standalone options, there is uncertainty surrounding the extent to which the co-location option would compromise the benefits which could otherwise be achieved from a regional detention basin on the subject site.[49]
[49]As to the modelling which could have been conducted, see Johnson T4-106, 107, Clark T5-23,24.
Any deficiency on the subject site could potentially be made up elsewhere. Mr Clark initially answered in the affirmative to a question from the bench as to whether that could be accomplished relatively easily,[50] but later (reasonably) qualified that answer by saying that he had simply meant that it was physically possible to achieve. He explained that, in the absence of the impact of the development being quantified, he was uncertain of the quantity of storage that might be required to make up for the deficiency.[51] Reliance on the potential to make up an unknown deficiency in an unknown way elsewhere carries the risk of prejudicing the efficiency in the provision of infrastructure.
[50]T5-27.
[51]T5-30.
Dr Johnson dismissed suggestions that he ought to have carried out any further modelling or investigation into the combined requirements for the detention basin and development. He drew attention to the information request, which asked only for the demonstration of how a detention basin with a total capacity of 21,000m3 can be achieved on site and also to a subsequent e-mail exchange between his office and a council officer which confirmed the summary of a discussion. That discussion referred to a regional detention basin with a storage volume of approximately 21,000m3 being required. Dr Johnson took it that a co-located basin of 21,000m3 would be satisfactory. It should be noted that the volume nominated in the information request was for the regional detention basin. Further, the summary in the e-mail exchange went on to say “if council decides a basin is required, council will likely need to purchase the necessary land for the owner, although other engineering options may also be available”. The documents did not expressly raise an issue about the effect of any co-location on the performance of the regional detention basin, but that does not justify the Court ignoring the issue.
Dr Johnson also pointed out that the justification for, or benefits of, a detention basin with the particular volume of 21,000m3 are unknown. The 2009 report (which was withheld from Dr Johnson for some time) referred to a figure of 21,000m3, but is dated and, in his view, unsubstantiated at this time. Mr Clark’s evidence was to the effect that there is the potential for the increase in upstream intensification of development to produce significant increases in inflows in Sheepstation Creek and a detention basin is needed, but the council did not rely on his evidence to justify a particularly sizing. The figure of 21,000m3 was not picked up in any of the infrastructure charging resolutions or in the PIP and the planned detention basin has not been the subject of detailed design. The sizing was referred to in an investigation report which became an exhibit, but that was admitted into evidence on the basis that it was not evidence of the truth of its contents. It remains the case however, that a regional detention basin is a longstanding component of the council’s infrastructure planning for the benefit of the community.
The evidence satisfies me that it is possible to develop a detention basin with a total capacity of 21,000m3 on the site below the proposed development. It would be accompanied by some safety issues, albeit not, of themselves, unacceptable. It would also be accompanied by some maintenance issues, which would likely affect efficiency, to some extent, compared with a free-standing detention basin. It would provide some benefit to the wider catchment, beyond offsetting the impacts of the development of the site itself, but the extent to which it would also do so have not been ascertained. It carries the potential to limit the extent to which the benefits of the council’s planned regional detention basin, if developed on the subject land, can be maximised and also carries the potential to require compensatory benefits to be found elsewhere.
I am satisfied that the proposal has the potential, if constructed prematurely, to prejudice the Council’s infrastructure planning. That does not call for refusal of the development application. It is however, relevant to impose conditions to address that potential prejudice. In my view it is, in the circumstances of this case, and notwithstanding the attractions of co-location, not unreasonable, having regard to matters including maximising the efficient provision of infrastructure, to do so by imposing a condition which delays commencement of construction for a reasonable, but certainly not elongated, time to afford the council an opportunity to promptly complete its proposed acquisition without prejudice to the development of a standalone basin, unless it is prepared, on reflection, to consent to the appellant’s preferred alternative condition involving the co-location option.
Conclusion
For the above reasons, I am satisfied that the appellant has discharged the onus. The appeal will be allowed. The further hearing will, at this time, be adjourned to enable the parties to formulate conditions of approval.
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