Actual or likely environmental harm: s 241(1)(a) POEO Act
(a) General
47In the present case, it is not in dispute that actual harm to the environment was occasioned by the discharge of bentonite slurry into the Partridge Creek wetland. In the context of the general ecology of the wetland, the discharge of the bentonite slurry had the effect of smothering some plants and preventing or limiting access to food sources by species using those areas in which there was standing water. In the case of the Wallum Froglet, the deposition of the slurry into standing water areas had the potential to impair the feeding of tadpoles. During the containment and clean-up operations, the existence of sandbags and booms are likely to have impaired movement of Froglets around or through the area. While these impacts may be stated at a level of generality, the extent to which they reflected an impact is not at all clear. This observation requires further elaboration.
48The area of the Partridge Creek wetland in which the second and third frac-outs occurred is an area that had been disturbed by road construction undertaken by the Council. The construction of that road was the subject of a prosecution against the Council and a senior employee of the Council by the present prosecutor ( Garrett v Freeman (No 3) [2009] NSWLEC 1; (2009) 164 LGERA 287). It was constructed to accommodate two-way traffic, surfaced with clay gravel and complete with culverts and other features appropriate for such a road. As a consequence of the prosecution brought against the Council, the road was removed, to the intent that the area that had been disturbed should be rehabilitated so that regeneration of local plant communities could take place. At the time of the commission of the present offences, the path of the old road was apparent with regeneration of many plant species yet to occur. Works associated with road construction and removal had the effect of significantly confounding any conclusions that might otherwise be drawn about harm, actual or likely, occasioned by the events giving rise to the present proceedings.
(b) Wetland ecology
49A further confounding element was the consequence of action taken by the Council in about 2002. The area in which horizontal drilling was taking place was an area that had been identified as an acid sulphate soil "hotspot". As a consequence, an acid sulphate soil remediation program was undertaken. That program involved construction of a weir on Partridge Creek, designed to maintain groundwater in the wetland at a level of 0.9m AHD. The purpose of so doing was to limit the exposure of acid sulphate soils to air during periods when the water level otherwise receded. Exposure of sulphidic soils to air has the effect of releasing acid into the environment. The change brought about by construction of the weir clearly impacted upon the ecology of the area.
50General assessment of harm as a consequence of the spill was the subject of evidence from Dr Neil Saintilan, a Principal Research Scientist and Head of the Rivers and Wetlands Unit in the Department of Environment Climate Change and Water. Dr Saintilan first visited the sites of the second and third frac-outs on 26 November 2009. Soil samples were taken from both within and outside the areas affected by those frac-outs. As would be expected, Dr Saintilan stated that by reason of the depth of bentonite then observed in the area of the third frac-out, "herbaceous vegetation growing within the impacted site would have been smothered by this clay layer." Dr Saintilan described the area of the second frac-out as being largely unvegetated, having previously been cleared for the construction of a road. Trampling of regrowth was evident. He indicated "that regrowth of some species at this site may have been arrested by smothering from the bentonite frac-out."
51Having regard to his observations made on that inspection and with the benefit of testing of core sediments which he had taken, he noted two matters:
(i) as the fine texture of the bentonite clay was "in common with the texture of the inorganic (clastic) material of the swamp" long-term problems were unlikely to be imposed upon the plant community occupying the wetland; and
(ii) although the bentonite profile was of lower phosphorus than the natural soil of the site, it was unknown whether phosphorus was a limiting nutrient in the swamp and, in any event, he expected that "most species present would be capable of accessing phosphorus from beneath the bentonite layer."
52Dr Saintilan returned to the site of the three frac-out locations on 22 March 2010. He observed that, with the exception of heavily vegetated patches, the bentonite observed on his first visit had been removed to depths below 50mm. He recommended against any further attempts at removal, given the prospect of damage to dense vegetation by attempting that removal. Importantly, he observed that regrowth was evident at those sites earlier impacted by the removal of bentonite.
53Ultimately, Dr Saintilan indicated that only one long-term impact was possible. That was the prospect of expansion of the exotic grass Setaria sphacelate . This species could spread to those areas disturbed by the discharge of bentonite slurry and also disturbed by the remediation activities. Setaria species had established in the vicinity of the second frac-out site but, as Dr Saintilan acknowledged, that was due to the disturbance of the area associated with the roadworks that had been carried out by the Council. He acknowledged that there was no evidence of recent colonisation of disturbed areas by Setaria species.
54In order to assess the likely long-term impacts, if any, from the frac-outs that had occurred in November 2009, Dr Saintilan relied upon observation that he and fellow scientists from his Department made at a wetland located at Coopernook, some 80km from the present site. A discharge of bentonite into the Coopernook wetland had occurred in September 2004. Having regard to the description given by Dr Saintilan, the vegetation communities present in that wetland would appear to be similar to those found in the Partridge Creek wetland, at least in those parts where the frac-outs occurred.
55Physical damage to wetland vegetation by smothering with bentonite had occurred at Coopernook. As was the case at Partridge Creek, damage had also occurred by trampling during operations to remove the bentonite. The scientist who had assessed the consequences of that spill had concluded that long-term damage to the aquatic plant communities was unlikely on the basis that bentonite was a naturally occurring clay which would not inhibit root penetration. Regrowth of damaged plants was estimated to occur in one or two growing seasons.
56Dr Saintilan revisited Coopernook in March 2010. Sites where the 2004 discharge of bentonite slurry had occurred were not identifiable by surface observation and could only be detected through tests of the soil profile. He indicated that there were no obvious ongoing impacts, with regrowth of understorey appearing to be complete.
57Based on observations of the subject site and conclusions that could be drawn from re-visiting the Coopernook site, Dr Saintilan concluded that bentonite discharges "did not lead to significant long-term impacts in wetlands, with the exception of minor structural changes due in part to the nature and extent of the clean-up procedures". He acknowledged that a confounding factor in the present case was both the disturbance resulting from road construction carried out by the Council and the impact upon the ecology by reason of the weir construction on Partridge Creek. He had not appreciated that the latter event had occurred. Moreover, since the frac-outs in the wetland in 2009, there was no evidence of Setaria species extending into the areas affected by either the bentonite deposits or the clean-up operation to remove it.
(c) Wallum Froglet
58Impact upon the Wallum Froglet was the subject of evidence from Dr Mahony and Mr Lee. There is little difference between them in their expressions of opinion. To the extent that there are differences, those differences seem to me to be of little consequence in determining the issues on this matter. They are agreed that the Partridge Creek wetland, as an area in general, provides habitat for the Wallum Froglet and did so at the time at which each of the two frac-outs occurred. The species is recorded as being present in areas that were reasonably proximate to those parts of the wetland into which the bentonite slurry discharged. However, prior to those occurrences, there is no evidence that the Froglet had been located within the areas so affected, although surveys conducted in March 2011 revealed the presence of the Froglet within those areas. Finally, they agree that the species is capable of travelling significant distances across the terrain which defines the extent of their habitat.
59Another amphibian known to have habitat in the Partridge Creek wetland is the Common Eastern Froglet, regarded as being a competitor of the Wallum Froglet. Some surveys of the wetland indicate that the two Froglets co-occur, notwithstanding that the Wallum Froglet is seen as a "habitat specialist", occupying areas where the pH level of the water is lower than that preferred by other species, including the Common Eastern Froglet.
60Related to the issue of increased competition between the two Froglets was the effect of the bentonite slurry on the pH level of waters into which it discharged. Both experts accepted that the slurry had the prospect, at least in the short term, of elevating the pH level of that water. They also agreed that the pH level of waters in the Wallum Froglet habitat is in a range of 2 through to 6.7. Mr Lee had tested water in the area of each of the three frac-outs which indicated a range of 4.92 to 6.01. That compared with a range of pH values for water outside the frac-out areas as being between 2 and 5.99. While Dr Mahony posited that the discharge of bentonite slurry into these areas might have elevated the pH levels of water immediately after discharge, he could not identify what that level might have been nor the impact, if any, upon the Wallum Froglet, assuming a change in pH level. In short, he accepted that levels measured by Mr Lee were well within the range expected of habitat for the Wallum Froglet.
61If there was any increase in competition from the Common Eastern Froglet in the frac-out areas, Dr Mahony was unable to indicate whether that could be due to a change in pH level of the water or by reason of disturbance occasioned by the road construction and its subsequent removal. It should be noted that there was no evidence presented indicating that the areas affected by frac-out reflected an increased population of the Common Eastern Froglet compared to that which had existed prior to the commencement of horizontal drilling.
62There was a difference between Dr Mahony and Mr Lee as to whether the precise areas affected by the frac-outs were themselves habitat for the Wallum Froglet. The distinction that Mr Lee sought to draw was between the overall area where the calls or presence of Wallum Froglets had been recorded and the absence of any recording of the Froglet within any of the three frac-out areas. In drawing this distinction, he did not resile from the observation that the Partridge Creek wetland, having an area of about 120 hectares, was a recognised habitat for the Froglet. He maintained his position of the basis that prior to the commencement of horizontal drilling, no recording of Froglet on the site of the frac-outs had been made, and that their presence in those locations was unlikely given the disturbance created by the Council road construction and its subsequent removal.
63While Dr Mahony could not identify any record which placed the Wallum Froglet precisely within the site of any of the three frac-outs, he was confident that those areas should properly have been regarded as habitats, given the population of the Froglet within the wetland area generally. He based his conclusion upon the capacity of the Froglet to travel considerable distances and also to occupy reasonably disturbed areas provided both water and bordering vegetation conditions were appropriate. He saw no reason why this would not be the case in the frac-out areas and considered that the Froglet would, at the very least, have moved through those areas.
64I accept the evidence of Dr Mahony in this regard. The characteristics of the Froglet, its movement patterns and its capacity to occupy recently disturbed areas, as evidenced by its presence on the frac-out sites in 2011, are all matters supporting Dr Mahony's opinion. Those characteristics that I have identified were not challenged by Mr Lee, his fundamental position being the absence of any recorded finding of the Froglet in those areas.
65However, this does not result in any finding of significant environmental harm upon the Froglet. Dr Mahony readily acknowledged the abundance of the species in the area and the fact that the affect, if any, upon the Froglet would only have been short term. This short term affect may have been had upon tadpoles being unable to feed at the base of the water body, due to the smothering of benthic material. Nonetheless, Dr Mahony did acknowledge that the capacity of the tadpoles to swim some distance would have allowed most to move into areas unaffected by the benthonite deposit.
66The second area of impact was possible impairment of movement of the Froglet through the area due to sandbag placement, silt curtains, booms and other measures taken in order to contain the spill areas. This impact would, of course, have been short term.
67One final matter raised in relation to the effect upon the Froglet was the disturbance to the water body in the frac-out areas occasioned during the clean-up operation. Because of the very fine nature of the bentonite sediment, it was readily suspended in the water column as workers moved through the area carrying out clean-up activities. While the National Recovery Plan for the Wallum Froglet had identified areas of water with very low turbidity as being desirable for repopulation of the Froglet, Dr Mahony acknowledged that no research had been done to indicate the effect, if any, upon the Froglet where water bodies were subject to periodic turbidity or suspension of particulate matter.
(d) General assessment of harm
68Taking all these matters into account, I accept the submission of the prosecutor that the incident did occasion actual harm to the environment, having regard to the manner in which that expression is defined in the POEO Act. The area affected by that harm was agreed to be about a quarter of one hectare within a wetland area occupying about 120 hectares. That harm was clearly short term. As I have indicated, it involved the smothering of some plants when the second and third frac-outs occurred, followed by additional harm occasioned by clean-up activities. That harm includes indirect harm to those having an ecological relationship to those areas that were directly harmed ( Bentley v BGP Properties Pty Ltd [2006] NSWLEC 34; (2006) 145 LGERA 234 at [174]).
69As will be apparent from my discussion of the evidence, both the nature of the bentonite slurry pollutant and the remedial action directed to its removal have combined to ensure, so far as it can presently be determined, that there is no long-term impact upon the Partridge Creek wetland. So to indicate does not, of course, suggest that discharge of the pollutant does not have significance ( Environment Protection Authority v Coe Drilling Australia Pty Ltd [2005] NSWLEC 719 at [164]).
70I have discussed at some length the evidence directed to the Wallum Froglet. Having regard to the onus that is born by the prosecutor, I am not satisfied that actual harm to the Froglet has been proved. I accept that there is evidence of "likely harm" in that some tadpoles may have been affected and the movement of the Froglet inhibited by the protective and clean-up measures taken. However, the evidence of both Dr Mahony and Mr Lee must be acknowledged by which they indicated that, following the initial impact, there seems not to have been any long-term impact upon these species within the Partridge Creek wetland.
71To similar effect is the evidence of Dr Saintilan in relation to the wetland ecology generally. The evidence does not establish that even on the basis of likelihood, the discharge of bentonite slurry during either the second or third frac-out events is likely to increase the propensity of the exotic grass Setaria sphacelate from spreading into those areas. This conclusion is reinforced by the evidence of Dr Saintilan that upon inspection of the "benchmark" site at Coopernook, no evidence of the spread of the exotic grass species had been observed in those areas that had been the subject of bentonite spill at that location.
72I therefore conclude that while the actual harm was significant, having regard to its duration and the apparent absence of long-term impact, my assessment under this head is that the overall harm was at a low level.