How development should respond to severe weather events

The recent case Catalina Island Pty Limited v Pittwater Council [2014] NSWLEC 1125 demonstrates how the Land and Environment Court takes into consideration severe weather events in assessing development applications.

This case was an appeal against the refusal by Pittwater Council of a development application by Catalina Island for the construction of eight apartments pursuant to the State Environmental Planning Policy (Housing for Seniors and Persons with a Disability) 2004 (SEPP) on a sloped site overlooking the Careel Headland Reserve in North Avalon. The primary issue in the proceedings was the risk of on-site flooding from the nearby Careel Creek, including the failure to comply with Council’s flood controls contained in its Development Control Plans (DCP).

Zoning and flood study

The site was zoned 2(a) Residential under the Pittwater Local Environmental Plan 1993, which usually prohibited the development of apartment complexes. However, because the complex was to be built for the use of persons over the age of 55 or with a disability, the development was permissible under the SEPP.

The Court noted that Council had carried out a flood study of the catchment of Careel Creek, which included the proposed development site. This study showed that, under current climatic conditions, the site would be affected during a 1:100 year flood (that is, there is a one percent probability, in any year, that such a flood will occur). Council’s modelling showed that the site would also be significantly inundated during a probable maximum flood (PMF) – which is the highest flood level predicted to occur under the most extreme predicted rainfall conditions in the Careel Creek catchments. Senior Commissioner Moore noted that when anticipated climate change impacts are factored in, these risks are exacerbated.

Council’s development control plan

Council’s primary contention was that the development did not comply with Part B 3.21 of Council’s DCP. The DCP required that developments of this kind have a pedestrian access through a “low flood hazard area to a ‘safe haven’  that was a minimum of above 300mm below the level of the PMF.” Further, as  the proposal was for persons over 55 of with a disability, the development was categorised as a “Special Flood Protection” development and  therefore all floor levels had to be at or above or raised to the PMF.

Council’s expert raised concerns that in the event that there was exceptional and continuing intensity of rain reaching the PMF, it was likely that Careel Creek would flood. If flooding occurred, the design and location of the development was such that it would be under 30 minutes until there would be significant volumes of water in the garages and ground floor levels of the complex.

While Catalina Island amended the plans to raise the floor level by 175mm, there still remained only a few minutes for occupants to evacuate to the residential first level of the complex before it was unsafe to do so. Given the predicted climate changes increased the likelihood of such severe rainfall, and the fact that the occupants would be elderly and disabled, Council was concerned that this alternative still did not meet the requirements of the DCP.

Alternative means of  compliancestopsign

In light of s 79C(3A)(b) of the Environmental Planning and Assessment Act 1979 (NSW), the Court had to consider whether, despite the proposal’s failure to comply with the DCP standard, there was a reasonable alternative solution for the development such that it still achieved the overall objects of the standards imposed by the DCP.

The Court considered the following alternative solutions proposed by Catalina Islands:

Flood impact mitigation works on the lift

Council was concerned that the hydraulic lifts between the ground and first floor of the development had the potential to be “rendered inoperable” in the event of a flood if the electrical circuitry were to become water affected. Catalina Islands argued that the control mechanisms of the electrical circuitry could be waterproofed or their location changed in order to prevent this occurring. However, expert evidence indicated that it would be difficult to adequately waterproof all the control mechanisms or to move them to a position that was still accessible to persons in wheelchairs. Further, there had been no known examples of such measures, and the lack of evidence as to the practical workings of this alternative did not satisfy the Court that this was a reasonable alternative solution.

The resting point of the lifts was also a concern in the event of flooding. Catalina Islands suggested that if the lift were to fail in the event of flooding, it could default to the upper level rather than resting at the inundated ground floor level. However, once the lift defaulted to the upper level, it would not be able to move again until the flooding was under control and a technician could fix the lift, leaving anyone on the ground floor stranded. The lifts only had capacity for one wheelchair or two standing people, which would not accommodate all evacuating residents, and it was likely that residents being elderly or disabled might struggle to use the stairs safely. Therefore, this too failed to be a reasonable alternative solution.

Reinforcing entrance doors

Catalina Islands also suggested that the entrance doors to the development could be reinforced to mitigate the impacts of a flood. However, evidence suggested that in the event of a flood, the water was likely to flow directly down the driveway and into the garages, not through the entrance doors. Most of the evidence tendered did not address the need to redesign the garage doors to address flood impacts, but focussed on the entrance doors and therefore did not provide a reasonable alternative solution.

Detention sump capacity

Catalina Islands also proposed to add 100m3 of storage creating a detention sump to hold extra water. However, the Court found that according to unchallenged Council expert evidence, for a sump to be effective, there would need to be storage capacity of 2000m3, not merely 100m3. The sump proposed by Catalina Islands would therefore only buy a few extra seconds in time in the event of evacuation, and was not a reasonable alternative solution.

A rainfall duration/intensity alarm system

Catalina Islands also suggested installing an alarm which might alert the residents of potential flooding from a broad networking base. Expert evidence indicated that there would still be a considerable time delay in transmitting the data from the networked monitoring system that was likely to be longer than the time the effects of flooding would be felt on the development.

Catalina Islands proposed in the alternative that an alarm based on the site rather than from a broad network might address this issue. However, the experts did not know of any alarms of the kind operating on an individual location basis, and even if there were, the short amount of time within which evacuation could occur safely was such that residents would be subjected to a number of false alarms in anticipation of flooding that might never eventuate. Given that these alarms would be a nuisance, the Court was concerned that residents were likely to disable the alarm and therefore it was not a reasonable alternative solution.

What’s the wash up?

The Court concluded that it was not possible for the objectives of the DCP to be met by the plans brought forward by Catalina Island, nor on any possible alternatives brought before the Court during submissions. Therefore, the appeal was dismissed and the development application refused.

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