[105] In cases such as the present, where the extent of the relevant duty is not clear, it is useful to begin by considering the damage which the plaintiff suffered, and the particular want of care which is alleged against the defendant. Asking then whether that damage, caused by that want of care, resulted from the breach of a duty which the defendant owed the plaintiff, may reveal more readily the scope of the duty upon which the plaintiff's allegations of breach and damage must depend."
115 See also the discussion of Gummow J in Vairy at [58] ff; and Hayne J at [116] ff, although there is some difference in their Honours' approaches. Gummow J considered, at 442, that the question at issue in that case was whether the Council's duty of care included a duty to warn against the dangers of diving. In answering this question, Gummow J referred to the starting point suggested by Brennan J in his dissenting judgment in Nagle v Rottnest Island Authority [1993] HCA 76; (1993) 177 CLR 423 at 440, namely, looking to the nature of the danger, assessed prior to the accident, with reference to such matters as the functions of the public authority, the obviousness of the danger, and the care ordinarily exercised by members of the public.
116 Hayne J, at [117]-[118], considered that in that case it was not useful to state the duty of care owed by a statutory authority that had the care, control and management of public land to those who entered too precisely. However, he added, at [118], in what appears to be a statement of general application, depending upon the facts of a particular case:
"… that it is necessary to recognise that the duty of care, owed by a statutory authority to those who enter land of which the authority has the care, control and management, is not a duty to ensure that no harm befalls the entrant. It is a duty to take reasonable care. Beyond that, however, it is not possible to amplify the content of the duty without reference to particular facts and circumstances. In each case, the content of the duty will turn critically upon the particular facts and circumstances ." (Emphasis added)
117 The question of the content of the duty of care arose again recently in Roads and Traffic Authority of NSW v Dederer [2007] HCA 42; (2007) 238 ALR 761. Gummow J, with whose reasons Callinan and Heydon JJ agreed, stated at [43]:
"First, duties of care are not owed in the abstract. Rather, they are obligations of a particular scope, and that scope may be more or less expansive depending on the relationship in question. Secondly, whatever their scope, all duties of care are to be discharged by the exercise of reasonable care. They do not impose a more stringent or onerous burden."
118 It is apparent from the various statements emanating from the High Court that there is no single test or principle as to how the content of a duty of care is to be determined. However, what does emerge, is that the particular circumstances of the case are relevant to that question.
119 In this case, the Council contends that his Honour's formulation of the content of the duty of care was not open on the evidence. Reference was made to the judgment at [65], [113], [126]-[127] and [134]-[136] as being the paragraphs in which his Honour's finding on duty appears to have been based. The challenge to his Honour's judgment in this respect was that the findings and/or conclusions contained therein were either erroneous or not based in the evidence.
120 What follows is an analysis of these paragraphs to determine whether the Council has made out its contention.
121 His Honour accepted, at [66], that the Council had the "relevant expertise" when it created the culvert and up until the date of the accident. I understand this to be a reference to expertise in respect of the installation and maintenance of stormwater drains and the effect of those drains on trees and tree roots, being the evidence of Mr Burn to which his Honour referred at [65]. It also appears from the finding at [66] that his Honour accepted Mr Burn's evidence that one of the things the Council's stormwater drainage experts might look at if inspecting this culvert was "the question of the free drainage of [the] culvert" (also at [65]).
122 The evidence disclosed that there had been no regular or systematised maintenance of the culvert and its drainage system. Indeed, it was unlikely that there had been any maintenance at all. If there was a duty to keep the culvert clear of obstructions as found by his Honour, then, subject to the operation of ss 42 and 45, the finding at [66], combined with the lack of any regular inspection, may have been sufficient to find breach, especially if the evidence of Mr Burn was accepted.
123 However, the present question is whether the Council owed a duty of care, either in the terms found by his Honour, or at all. In this case, that requires a consideration of the purpose for which the culvert was installed and the physical conditions operating at the time of installation. It also requires a consideration of whether an ad hoc duty of care arose, as a result of the inspections that the Council carried out of the culvert on a number of occasions post-1997. I will deal with that question separately, as it raises the question relied upon by Mrs Turano in her Notice of Contention. Both aspects of duty also require regard to be had to the principles stated in s 42.
124 The culvert was intended to drain water under and away from the road surface. It was designed to be free draining across the pasture land to the west by means of the tail-out drain. The road was in a semi-rural area, with no houses or buildings in the immediate vicinity. The immediately surrounding soil conditions were clay. The tree population was sparse. There was no evidence as to when the tree was planted, or whether it was the product of a planting program, although it was likely that it was not, but was naturally occurring.
125 According to Mr Burn, in his report of 21 February 2006, because of the flat grades in the area, the outlet from the culvert needed to be kept clear of obstructions, so as to minimise water build-up leading to soil saturation. If that evidence was accepted, it might be argued it was foreseeable at the time that the culvert and its drainage system was constructed, the drain could become obstructed, so as to prevent the free drainage of water discharged from the culvert.
126 However, there are two more factual circumstances that need to be considered. First, the area into which the culvert discharged was impermeable clay. It would not have been foreseeable in that circumstance that water from the culvert would saturate the surrounding soil, even if the culvert was obstructed for some reason. Further, subject to Mr Burn's evidence as to the culvert silting up, the evidence was that the only relevant obstruction of the culvert was by the water main, possibly contributed to by the Telstra line. Both the water main and the Telstra line were installed long after the culvert was built and there was no evidence that the Council knew that either had been installed. As I have explained earlier, Mr Burn effectively conceded that any obstruction was due to the water main.
127 Accordingly, without needing to consider the other paragraphs to which the Council referred in its submissions, I am not satisfied that there was a duty on the Council in the terms defined by his Honour. Such a duty would only have arisen if the Council knew, or ought to have known, at the time of installation that the culvert and its discharge draining system was likely to become clogged or obstructed, so that water might not drain away but could seep into the surrounding soil, adversely affecting the surrounding vegetation, including trees in the vicinity.
128 None of those things was established: there was no evidence that the culvert was likely to clog, other than the evidence of Mr Burn prior to his concession that there was no evidence that the culvert had clogged; and there was no evidence that the tail-out drain was likely to cease to function. Rather, the evidence was that water would accumulate in the pit after times of heavy rain, but that the ponded water would not seep into the impermeable clay surface.
129 I have reached the conclusion that there was no duty in the terms defined by his Honour without considering the application of ss 42 and 45. As there are separate appeal grounds relating to those sections, their operation is considered below. It is convenient, at this point, to continue with a consideration of the paragraphs to which the Council referred in the submission with which I have been dealing.
130 His Honour stated, at [126], that he was satisfied that the Council's failure to properly maintain the culvert outlet so as to drain water flowing to the west:
"… more likely than not resulted in the area around the western end becoming almost permanently damp and undermining the stability of the tree by causing root damage and soil degradation."
131 This finding appears to have drawn on the finding, at [123], that over a period of about forty years, the culvert would become intermittently blocked by debris, causing the water to pond and the surrounding area to become saturated, "leading to a more or less consistent wet area in the vicinity of the tree that failed". His Honour reiterated this at [125], when he referred to the ground being saturated through intermittent or consistent ponding. His Honour also found, at [124], that there was evidence that the rootball system of the tree was badly damaged by water, making it prone to failure.
132 The effect of his Honour's finding at [126], as I understand it, was that water would have soaked through to the impermeable clay wall for a sufficient distance so as to reach the rootball of the tree. This finding would appear to have been made on the basis of the evidence given by Mr Freeman about the increase in the level of the water table, or possibly the increase in the water levels. I have already explained the difficulties with this evidence.
133 The finding is also inconsistent with his Honour's acceptance of Mr Bewsher's evidence and inconsistent with the unchallenged evidence of Mr Lumsdaine, which his Honour also appears to have accepted. On Mr Lumsdaine's evidence, ponded water at the outlet of the culvert would not have flowed laterally through the surrounding clay: see [42] above. At the most, there would have been some minimal water absorption responsible for the shrink/swell function characteristic of clay soils. On Mr Bewsher's and Mr Lumsdaine's evidence, it was the sand from the water main that caused the water to travel. The water in the culvert discharge pit would not have permeated to the tree roots, because of the impermeable nature of the clay soil. Accordingly, as I will indicate later, I am of the opinion that even if duty and breach were correctly found by his Honour, his finding on causation was contrary to the evidence that he accepted.
134 His Honour made a finding, at [134], that as the Council had constructed the culvert and the system of water flow to the west, it had created the potential for the water to pond, if the tail-out drain was not kept clear. His Honour, at [135], accepted that there had originally been a tail-out drain for the western end of the culvert, but this had been allowed to be overgrown, or dug out over time, due to poor maintenance systems. The findings in these two paragraphs were open on the evidence.
135 His Honour concluded, at [136], that if the Council had properly maintained the culvert, the water would not have ponded and thereby affected the surrounding soil, causing damage to the roots of the tree. For the reasons already discussed, that conclusion was inconsistent with the evidence he accepted. His Honour also concluded that had regular culvert inspections been carried out, the condition of the tree rootball would, more likely than not, have been identified and steps taken to eliminate any potential danger by buttressing the tree or removing it. This finding was premised upon the Council having a duty of care in the terms found by his Honour. As his Honour's formulation of duty cannot, in my opinion, stand, this finding, which is a finding of breach, must also fail.