Mine Subsidence Board v Maria Vervoon

The AGL representatives have instructed the [respondent] not to use the Natural Gas service owing to the severe movement of the ground where the gas metre is located and the lines past into the home. This has existed for the past two winters.

The [respondent] believes that the home is well beyond economic repair." 5 This claim was also rejected and the respondent appealed to the Land and Environment Court under s 12B of the Mine Subsidence Compensation Act. That appeal was heard by Talbot J, who held, at [157], that the major contributing cause of damage to the house was the settlement at the rear of the property due, in major part, to the presence of the abandoned mine workings immediately underneath it. His Honour held that damage to the front of the house where the front steps were coming away from the porch was unrelated to mine subsidence. In reaching his determination that mine subsidence had been a cause of the damage, his Honour preferred the expert witnesses who had been called on behalf of the respondent to the Board's expert witnesses. 6 His Honour assessed the proportion of damage attributable to mine subsidence at 60 per cent: see judgment [157]. At [158], his Honour determined that the compensation to be awarded to the respondent was 60 per cent of the value of the house and other improvements on the land, other than those located at the front of the house in the direction of Birdwood Street. 7 The Board has appealed to this Court from his Honour's determination of liability. The respondent has cross-appealed from his Honour's assessment of the proportion of damage due to mine subsidence and his determination that the compensation payable was as to 60 per cent of the value of the house. 8 The appeal and the cross-appeal are in respect of a question of law only: s 57 of the Land and Environment Court Act 1979.

The appeal 9 On the appeal, the Board contends that the trial judge failed to consider six matters of which evidence had been given by experts and which were critical to the Board's case. Those six matters were:

That there had been cyclic movement some 400-500 m away from the respondent's residence, outside any area claimed to be influenced by mine subsidence and that such cyclic movement was inconsistent with mine subsidence at the respondent's residence: ground 1(b);

That an Angle of Draw analysis had been undertaken that produced measurements outside those expected, should the property have been affected by subsidence: ground 1(c);

That a worst case scenario pursuant to calculations from the Voussoir beam analysis, showed that predictions of subsidence could not be obtained which correlated with the measured movements at the subject property: ground 1(d);

That the evidence of the extent of movement and change on the surface above the disused mine would lead to the expectation that the coal pillars would be highly distressed, whereas they were not: ground 1(e);

That given the evidence of the amount of movement and change on the surface, it would be expected that there would be a volume of material lost or moved in the order of 10 m3, or 25 tonnes, whereas little or no material was observed in the workings: ground 1(f);

That the direction of movement to be expected if there was mine subsidence, namely, 90 degrees to the centre of the mine roadway, did not accord with the measurements recorded in the surveys: ground 1(g).

Each of these matters had arisen in the evidence of the Board's expert, Dr Galvin. 10 The Board says that it submitted to the trial judge that each of the above matters was critical to the determination of whether or not the cause of the damage to the respondent's house was mine subsidence. Each was advanced as a factual matter, supporting the Board's contention that subsidence was not the cause of the damage. It was submitted that his Honour's failure to deal, or to properly deal, with these matters was such that his judgment had not provided "sufficient reasons to enable a party to be able to exercise his right of appeal and for the court on appeal to understand the rationale by the judge to reach the decision he did": Apps v Pilet (1987) 11 NSWLR 350; Housing Commission (NSW) v Tatmar Pastoral Co Pty Ltd [1983] 3 NSWLR 378; (1983) 53 LGRA 325; Pettitt v Dunkley [1971] 1 NSWLR 376. It was submitted that the effect of the findings of the trial judge was that the Board was left with no rationale as to why cogent factual arguments against a finding in favour of subsidence were not dealt with: see Wiki v Atlantis Relocations [2004] NSWCA 174; (2004) 60 NSWLR 127 at [59]; Mifsud v Campbell (1991) 21 NSWLR 725 at 728. 11 It was submitted that the matters upon which the Board adduced evidence and relied before the trial judge were not merely supplementary or ancillary. It was accepted that if they were, then the Board had no basis for complaint: see Kiama Constructions Pty Limited v Davey (1996) 40 NSWLR 639 at 647, where Meagher JA said that a judge's duty did not extend to stating their reasons in respect of every matter raised during proceedings. Rather, what was necessary was to deal with the evidence critical to an issue in a case: see Mifsud v Campbell per Samuels JA at 728. It was submitted in this case that the six items of evidence specified in the Board's grounds of appeal, taken individually or cumulatively, could be seen to be "unassailably reliable evidence" that the damage to the respondent's property was not caused by mine subsidence and that his Honour's decision to the contrary was, therefore, erroneous: State Rail Authority of New South Wales v Earthline Constructions Pty Ltd (In Liq) [1999] HCA 3; (1999) 160 ALR 588. 12 An argument was also advanced that his Honour's decision was both inconsistent with incontrovertible facts and that his Honour's conclusion was not able to be rationally reconciled with those facts: see Fox v Percy [2003] HCA 22; (2003) 214 CLR 118 at [29] and [49]. This argument was significantly modified in the Board's submissions in reply, where it was said that the six items of evidence were not "incontrovertible facts", but rather were matters that were contentious at the trial. The Board contends that the respondent's experts did not deal with the six items of evidence that form the basis of its appeal, other than for the movement of the permanent markers. However, the Board's complaint is not that these matters were not dealt with by the respondent's experts, but that his Honour did not deal with them. 13 The Board acknowledged that his Honour preferred Dr Thomas' evidence and did not accept the Board's expert witnesses. However, it was said that where specific matters, such as the six which it was said were not dealt with by his Honour, were able to provide an antidote to the failure mechanism contended for by Dr Thomas, it was inadequate for the trial judge simply to express a preference for a body of evidence over other evidence. 14 Having regard to the nature of the challenge to the trial judge's decision, it will be necessary to deal with each aspect of the evidence the Board says was critical and which it contends was overlooked by the trial judge. Before doing so, however, it is convenient to have regard not only to the procedures that govern the giving of expert evidence in the Land and Environment Court, but also to understand how those procedures were implemented in the case at hand.

The manner in which the expert evidence was given 15 At the time of the directions hearing, the relevant practice direction for the appointment of expert witnesses in the Land and Environment Court was Practice Direction No 22: Expert Witnesses. This Practice Direction enabled the Court to direct expert witnesses to: a) confer and to specify the matters on which the experts were to confer; b) endeavour to reach agreement on outstanding matters; and c) provide the Court with a joint report specifying matters agreed and matters not agreed and the reasons for any non-agreement. The Practice Direction also contained directions for the tendering of the joint report in evidence, an Expert Witness Code of Conduct and the Requirements for a Joint Conference of Expert Witnesses. 16 In accordance with those procedures, Talbot J, on 10 November 2006, directed the parties' experts to:

(c) identify the matters upon which they disagreed;

(d) prepare a joint written report identifying: (i) the matters upon which they agreed and the basis of the agreement; (ii) the issues upon which they disagreed and the reasons for any disagreement. 17 In this case, three "conclaves of experts" were held pursuant to the Court's directions. The first was held on 7 December 2006; the second on 13 March 2007; and the third was held on 19 June 2007. Due to some dissatisfaction with the presentation of the joint experts' report, the experts were required to again meet and the report was finally prepared at the conclusion of the first day of the hearing on 25 June 2007. That report is in the usual form of a joint experts' report: Uniform Civil Procedure Rules 2005, r 31.26. It sets out the relevant issues and the matters upon which there was agreement or disagreement. The basis of any disagreement was specified. 18 Individual expert reports were also tendered. I will deal with that later in these reasons. Each of the experts then gave oral evidence in the manner which has become known in the profession as "hot tubbing".

The house 19 As already indicated, the respondent's house is built partially over a mine roadway and partially over what is referred to as a "T" junction, at the barrier pillar of an old disused coal mine. The barrier pillar is the wall which signifies the finish of the mine workings, beyond which there was no extraction. Originally, there were railway lines branching off and a set of points at this location: [6]. 20 The original house consisted of a cavity wall brick construction and has probably been extended twice. The land upon which the house is built slopes downwards in a northerly direction towards Birdwood Street. The house itself fronts Birdwood Street and has at least one high retaining wall and two lower retaining walls. There is a set of concrete steps from the street level in two flights up to the front of the house, where a path runs east / west and leads to a verandah. 21 As the respondent specified in her application to the Board (see [4] above), there is significant cracking to the walls and floor of the main portion of the house and to the adjoining bedsitting room, as well as cracking of the front verandah and patio, including the floor tiles. The steps to the front verandah have moved away from the house. His Honour found that the movement of the front verandah and steps was not due to subsidence. There is no appeal from that finding. Indeed, senior counsel for the respondent stated that such concession had been made at trial. 22 The Board denies that any of the damage to the respondent's residence has been caused by subsidence. Rather, according to its experts, there were a number of possible causes, namely: reactive soil (the reaction of the soil to water); soil creep (the movement of soil down a hill); poor foundation design; land slip and / or groundwater flow. 23 The respondent's experts contended that the slab of the house itself is moving downwards and twisting to the east, with the result that the slab is moving both south and east. Their evidence is that this is inconsistent with soil creep. The respondent's experts also reject the other possible causes of the damage to the house advanced by the Board's experts. According to Dr Thomas, a mining engineer, whose evidence the trial judge accepted, the mechanism that has operated to cause damage to the respondent's house is: "… one of progressive rock fracture and attrition of joints [resulting] in a slow settlement of roof strata above and around a T-junction. This is a subsidence mechanism at shallow mine depths." 24 According to Dr Thomas: "The [mine] workings are not in pristine condition. The coal ribs are fractured, there are signs of water erosion on the floor, and debris has accumulated on the floor. Water was [seen] trickling down the boreholes while the video footage [of the interior of the mine] was obtained."

Trial judge's reasons for accepting the damage was due to mine subsidence 25 The respondent's case that the damage to her property was caused by mine subsidence was supported by Dr Thomas. His Honour's summary of Dr Thomas' evidence is to be found at [25]-[31]. It is convenient to set it out in full: "[25] Dr Thomas explained that in his opinion the mode of failure demonstrated by the data in respect of [the respondent's] house, is a straightforward textbook example of shallow roadway practical rock mechanics. The rock in this case is buried deep enough not to have any elastic compression or any substantial deformation. It is essentially dead weight deformation.

[26] Dr Thomas explained that all rocks have a sheer strength that differs. Over a period of time a network of cracks appears through the surface. As water comes through it tends to wash out the small grains thereby lubricating the horizontal bedding plains enabling the individual rocks to move past each other. Sometimes clay material is washed down and provides further lubrication. An unstable structure is created whereby small pieces of rock are chaffed. There is never really an enormous lowering into a roadway or void. The movement is small. The pattern of fractures and settlement goes to the surface. All of the joints are worn away to a small extent. Eventually at the surface there are small depressions in the order of 50mm -100mm.

[27] In relation to the [respondent's] house, there is a sequence beginning with coal which is a tough woody material immediately over the roadway with some tensile strength. It will sag slightly over the roadway between 10mm and 20 mm in the middle with some sheering at the edges of the pillars. It will pan across an opening if there is sandstone above to help support it. Above the sandstone there is some siltstone. Above that there is a pebbly coarse sandstone followed by a mix of carbonaceous siltstone. Above that again there is some weathered shale. Accordingly, there are two strong beds and some weaker beds.

[28] Dr Thomas says: - The softer materials can wear away much more easily and the clay weathered shales, silt stones, at the top of the sequence, can break up and wash away, and go down through these fractures in the rock, and if you have really heavy rainfall you can steadily lose maybe sort of a few millimetres of material each time, and the weathered shales becomes a bit honeycombed porous, you have cracks in them, and they will start to settle under their own weight.

[29] He went on further to say: - It's a progressive settlement from the bottom roadway up, but probably from experience most of it is happening in, say, the top third of the sequence because that's where the action is taking place. You find this sort of exposure as a fairly regular thing because rocks behave the same way. It was my speciality to go and look at rock forms.

[30] He says that a fracture pattern will be found above any intersection, T-intersection or square intersection.

[31] To his mind the bore hole cores and bore hole logs show the sort of disturbance in them that he would associate with the type of deflection and fractures he has identified. He says that the upper part of the borehole logs show water loss and cavities and that the pictures show an increasing flow of water down the borehole. The water that is coming down through the borehole is actually coming from the intervening strata and it is running down into the mine underneath." 26 His Honour next analysed the evidence of the other experts. At [127]-[144], his Honour summarised the alternatives to mine subsidence advanced on behalf of the Board. Again, the following is a substantial reproduction of his Honour's summation of the evidence.

(1) Reactive soil 27 His Honour first referred to the evidence of Mr Kotze, an engineering geologist specialising in slope stability, retained on behalf of the respondent. Mr Kotze had the relevant expertise to assess whether the damage was caused by reactive soil. He carried out soil tests and determined that the soil could be classified as class S to class M, with class S having the lowest category of reactivity: [34]. Mr Kotze's tests showed that the soils were slightly to moderately reactive to changes in moisture content. Soils of that degree of reactivity could typically create minor cracking under some conditions. However, at [34], his Honour noted the extent of damage to the respondent's residence was not minor, but rather, the house was uninhabitable. Mr Kotze had formed the opinion that the shrink / swell activity of the ground upon which the house was positioned had not caused the damage: [34]; [128]. Because of the significant cracking in the house and the fact the cracks were most often more widely open at the top, Mr Kotze considered there was the possibility of a relationship between the cracks, the damage and the mine workings beneath the house. He sought the opinion of Dr de Ambrosis, a geotechnical engineer. Dr de Ambrosis also formed the view that the ground settlement was too large to be due to soil reactivity, given the low to moderate reactive nature of the soil on the site: at [35]; [127]. 28 The Board's experts, Professor Galvin, Mr Hawkins and Mr Appleyard, all supported the view that the damage was caused by reactive soil: [128]-[130]. Professor Galvin's primary thesis was that the damage was due to reactive soil, although he considered that it was a combination of reactive soil, poor footing design, soil creep and changes in the groundwater regime: at [128]. The trial judge, at [128], observed that Professor Galvin's conclusions in respect of soil reactivity, "are not positive. They are derived in the context of eliminating mine subsidence". 29 Professor Galvin considered that when dealing with ground movement, one of the fundamental tools used is survey measurements: [38]. He noted that survey stations had been installed on the property in 1995 and that in the period 1995-1996, the measurements showed that, in general, the ground had a tendency to be moving up: [39]. He considered that the survey data, overall, demonstrated that the whole area surrounding the residence was undergoing cyclic movements, that is, periods of rising and falling: [39]. 30 His Honour recorded, at [40], the following matters as being relevant to the formation of Professor Galvin's opinion as to the cause of the damage to the residence: "1. Soil in the vicinity of [the respondent's] house is moderately reactive.

Movements of less than 20mm are to be disregarded because they can be attributed to and cannot be distinguished from natural ground movement.

There are only four measured points that show movement in excess of 20mm; one is 23mm; two are in the range of 30mm and two are in the range of 40-50mm. The two in the range of 30mm are marked on a slab at the front of a lean-to on the side of the house. It is not keyed in to the house. The other two points showing movement of 40-50mm are located on the extension of the rear of [the respondent's] house.

Obviously something happened before 1995 that caused [the respondent] to first bring this matter to the attention of the board. That was in 1991. He assumes something else happened to trigger the installation of survey stations in 1995.

Mine Subsidence movements are in a downward direction.

Uplift occurs around the edges of the workings, associated with very strong rigid stratum that overhangs the workings.

The old workings are in pristine condition." 31 Professor Galvin concluded that, as the mine workings were in pristine condition and as the survey information indicated to him cyclic movements of rising and falling, the most likely cause of the damage was reactive soil: [41]. However, as already indicated, he considered that there were signs of soil creep and groundwater changes. Defective foundations also played a part in his opinion, as did landslip: [58]. 32 Professor Galvin considered there was no evidence the structural damage to the property could be attributed to mine subsidence and he considered the theories advanced by Dr Thomas to be remote: at [60]. 33 Notwithstanding that he relied upon the cyclic up and down movement of the soil over the survey period of 1998 to March 2007 to support his primary thesis that the cause of the damage was reactive soil, Professor Galvin agreed in cross-examination that, in absolute terms, the survey points in March 2007 were lower than in 1998 and that at least two points at the rear of the house, identified as survey points 23 and 24, showed a trend of downward movement between March 2004 and March 2007: at [62] and [63]. Professor Galvin also agreed there was evidence that water had entered the mine, shown by calcium carbonate on the walls of the mine workings and ironstone stains, and agreed there was evidence of water flowing through the floor of the mine. He considered this was most probably caused by water flowing through old workings a bit further up the hill: at [64]. He accepted, however, that the percolation of water from the surface, as described by Dr Thomas, was a possible cause of the entry of water into the mine underneath the residence: [65]. 34 It appears this cross-examination was based upon survey plans that demonstrated between March 2004 and March 2007, five points on the western side of the house were shown as moving uphill: [79]. Two survey points on the eastern side of the house were in the same position. Between March 2004 and July 2005, the survey measurements showed a 45 degree movement relative to the hill at the rear of the premises. Although Professor Galvin apparently agreed the survey plans showed the house moving uphill, he would not agree that the movement was uphill, but rather, that it showed movement across the hill, with an upward component: at [79]. 35 Professor Galvin's evidence was the subject of adverse comment by the trial judge. At [84], his Honour stated that when assessing the weight to be given to Professor Galvin's evidence, it was important that his: "… apparent expertise and understanding of his obligations expressed in the witness box be balanced against his long and intimate association with the Board as a consultant and the pivotal role he has adopted in managing the development and presentation of the evidence." 36 His Honour was particularly critical of the fact that Professor Galvin had taken it upon himself to express opinions in fields of knowledge which were not part of his own area of specialty: [83]. 37 Mr Hawkins, an engineer specialising in geology, also expressed the view that soil reactivity had played a part in causing the damage to the house. He was not able to explain the observed additional movement beyond the normal expectation of the consequence of soil reactivity: [129]. However, Mr Hawkins' investigation of the causes had been substantially limited. He had no information as to the state of the house since 2005 and had not been able to return to the site since then, due to fee constraints imposed by the Board: [97]. Further, the Board failed to provide him with rainfall patterns for relevant periods to enable him to consider the effect of weather on soil reactivity. Mr Hawkins agreed that the survey readings from 2005 through to 2007 showed a downward trend at the rear of the house and that this trend was inconsistent with soil reactivity being the sole cause of the movement: [98]. He agreed that the downward movement during that period was greater than he would normally expect from soil reactivity: [100].

(2) Landslip 38 In his summary at [131], his Honour observed that Mr Kotze had found no evidence of large scale or significant landslides or landslip. Professor Galvin had only identified it as a possibility at the early stages of his investigations, but did not pursue it. Mr Hawkins had identified slope instability, or landslip (which he considered to be the same thing) as a possible, or plausible, contributor: [88]. He concluded, however, that it was probably unlikely to be a cause, but rated it "more likely" than mine subsidence being a cause: [88]. Mr Appleyard, a civil and structural consulting engineer retained by the Board, although not considering himself to be sufficiently knowledgeable technically to give a report in respect of soil creep, landslip and groundwater flow, nonetheless considered the damage to the respondent's residence "may have something to do with slope instability": [107]; [112]; [131]. Overall, he was of the opinion that there were a combination of mechanisms taking place which had contributed to the damage to the residence: [112].

(3) Groundwater 39 His Honour summarised, at [133]-[134], the evidence in relation to the percolation of groundwater as being a cause of the ground movement which ultimately caused damage to the house. His Honour noted that Professor Galvin initially placed some emphasis on the history of water travelling downhill from the reservoir in the direction of the house, but was not able to maintain that opinion "with the same vigour" as the case progressed. This conclusion was derived from the concessions Professor Galvin had made in cross-examination, particularly his acknowledgment that he did not know the course that the water from the reservoir had taken and his inability to state whether the water would have made its way to the back of the house: [66]. He also conceded in cross-examination that statements he had made in his report relating to water discharge could not be maintained: [66]. Mr Hawkins had originally concurred with Professor Galvin's opinion about the effect of groundwater, but eventually conceded he was unable to say whether the damage to the respondent's property was caused by groundwater or not: [93]; [134].

(4) Soil creep 40 The respondent's expert, Mr Kotze, was firmly of the view that the damage to the rear and central portions of the house was not caused by soil creep: [135]. Dr de Ambrosis agreed that the crack pattern in the house was inconsistent with soil creep. Professor Galvin had advanced soil creep as being one of the causes of the damage to the house. However, in cross-examination, he conceded that some of the plans of the house showed it was moving in an uphill direction and that would be highly improbable, if the cause of movement was soil creep: [79]. The survey points between March 2004 and March 2007 indicated there were five points on the western side of the house shown as moving uphill, whereas two points on the eastern side of the house were in the same position. Between March 2004 and July 2005, the surveyed measurements showed a 45 degree movement relative to the hill at the rear of the house. Professor Galvin, however, would not concede the movement thus depicted was in fact uphill, but rather, said that what was demonstrated was a movement "across the hill with an upward component": [79]. Mr Hawkins' evidence was that the damage to the front of the house was due to soil creep, but that the "horizontal movement at the rear of the house" was not: [95]; [137]. As I have said, there is no issue about the cause of the damage to the front of the house. 41 Mr Appleyard, who deferred to the opinion of others on this issue, ventured a view that whilst damage to the rear of the house might be related to slope instability, he was not able to say there was positive evidence showing that it was affected by soil creep: [107]; [111]. He considered that damage to the front of the house was due to soil creep: [138].

(5) Inadequate foundations and footings 42 Dr de Ambrosis found no evidence of footings settlement: [139]. Mr Appleyard was the Board's primary witness on this aspect. His evidence was that the footings of the respondent's residence were shallow and therefore likely to be affected by the transfer of ground strains: [45]. However, he had seen no evidence "whatever" that the observed damage was in fact as a result of ground strain transfer: [45]; [140]. He also observed the construction used on the residence was out of date and there was "unorthodox construction" of the floor under an external verandah and the lounge room. However, he had not examined the precise construction details of the footings in that area: [45]; [140]-[141]. Nonetheless, he expressed the opinion that it was "highly likely" the foundation material under the footings system of the extension was significantly wetter than other footings around the house: [45]. It was his view that the addition on the western side had moved away from the residence due to inadequate footings and inadequate bonding into the building itself" [46]; [140]. He considered the south-western portion of the residence, including the addition, had settled due to a combination of poor construction practices and overloaded original footings founded on wet and compressible soil: [46]; [108]; [111]. Mr Appleyard had also reported to the Board that the subfloor construction of the house was quite substandard. However, the opinions he expressed in respect of the house had all been made in circumstances where he had not undertaken a visual inspection of the footings or the foundations: [111]. 43 It was against that background, where none of the possible causes of the damage to the respondent's house advocated by the Board had been established beyond a possible cause, and the inability of any of the Board's experts to demonstrate that Dr Thomas' thesis was not possible, that his Honour accepted Dr Thomas' explanation that the damage had been caused by mine subsidence.

Were the six items of evidence identified by the Board critical to its case? 44 The matters relied upon the Board as being evidence that confounded Dr Thomas' theory and which it is alleged were not dealt with by the trial judge, each require separate consideration.

Item 1: permanent markers 400-500 m away 45 The Board contended there was uncontradicted evidence that permanent survey markers located 400-500 m away from the subject property, outside any possible influence from mine subsidence, showed cyclic movements consistent with the type of movement recorded at the respondent's house. Professor Galvin concluded from this evidence that the whole area was undergoing cyclic movement and therefore this confounded the possibility that the damage to the respondent's residence was caused by mine subsidence. 46 There is no dispute that as at the date of the July 2005 survey, State Survey Marker 7792 (SSM 7792) was at an elevation 13 mm higher than on the date of the March 2004 survey. Permanent Marker 6327 (PM 6327) was at an elevation 4 mm higher than on the date of the March 2004 survey. There was another variation between the March 2007 survey as compared to the July 2005 survey. SSM 7792 was at an elevation 10 mm lower and PM 6327 was at the same elevation. 47 The two survey markers had also changed position relative to each other. On the July 2005 survey, the vertical elevation of SSM 7792 relative to PM 6327 was 9 mm higher than on the date of the March 2004 survey. In March 2007, the vertical elevation of SSM 7792 relative to PM 6327 was 10 mm lower than that of the July 2005 survey. 48 On 8 May 2007, a meeting of the experts was requested by the Mines Subsidence Board to address the anomalies presented by the survey data during the period 1998 to March 2007. Representatives of the survey firm Craven, Elliston & Hayes were present, including Mr Grosfeld, who gave evidence in the proceedings. Professor Galvin and Mr Appleyard represented the Board and Dr Thomas and Dr de Ambrosis represented the respondent. The specific concern raised by the Board at this meeting was the change in the relative level between SSM 7792 and PM 6327, which had been used as assumed stable points of reference in undertaking the surveys of the respondent's property. Those present at the meeting agreed that the 12 mm discrepancy in the July 2005 survey was accurate and SSM 7792 and PM 6327 had moved relative to each other by that amount. 49 There was a discussion during the meeting regarding the soil reactivity in the area and the observation was made by Mr Craven, one of the surveyors, that soil reactivity had caused damage to the walls of the local technical college, damage which had initially been thought due to mine subsidence. Mr Craven noted that survey stations needed to be drilled down to bedrock, so that they were not affected by soil reactivity and, accordingly, it was agreed at the meeting that all of the survey data relating to the respondent's property should be re-analysed, adopting a more "stable" local reference point. The front wall of the respondent's garage on the Birdwood Street boundary, was agreed upon as a suitable reference point, because the garage was excavated into rock and was well clear of the old mine workings. It was agreed that the surveyors Craven, Elliston & Hayes, would prepare new level and vector plots for all of the survey data between May 1998 and March 2007, adopting the front garage wall as a reference point. 50 Professor Galvin, in the course of his oral evidence before the trial judge, referred to these matters and maintained that the back of the respondent's house, the house itself, the front yard and the road in front of the house, as well as the State Survey Markers (SSM 7792 and PM 6327) 400-500 m away, were moving in a similar way, which indicated that the whole area was undergoing cyclic movements, that is, periods of rising and falling. 51 Mr Grosfeld, in examination in chief, said that it was not possible to ascertain from the measurements taken on the respective survey dates the direction in which the two registered Survey Markers had moved. There was an objection raised at this point as to whether senior counsel for the Board was raising either irrelevant material, or "another theory" in respect of which there was no evidence. The discussion revolved around whether the movement being discussed was a vertical movement of the markers or their horizontal movement. Senior counsel explained he was not dealing with vertical movements, but with vectors. He stated: "Q: … The problem with vectors as I was just putting to Mr Grosfeld is that we don't know when the State markers have moved, one or both of them relative to each other. What direction they've moved in hence Mr Grosfeld we don't know whether the original assumed, or the original deduced fixed direction remains or not, we don't know?"

Mr Grosfeld responded that was true. He was then asked: "Q: But it's true, is it not that it doesn't matter insofar the directions at [the respondent's property], which you show on your reproduced documents … are again … relative one to each other on [the respondent's property]? A: That's correct.

Q: So even if the fixed direction at the State markers have moved the vectors on [the respondent's property] are still pretty much accurate because they relate one to the other on [the respondent's property] over time? A: That's correct." 52 There was some further discussion as to what this evidence meant, without any meaningful clarification, other than in respect of what was meant by "true north" and "site north", a matter which is presently not relevant. Most importantly, this discussion did not assist in ascertaining whether the fact that there had been movement of the permanent markers, discounted the likelihood of mine subsidence at the respondent's property. 53 Dr Thomas was also cross-examined on the movement of the State markers. He maintained that the movement on the respondent's property and the movement between the State markers, were due to totally different mechanisms. Professor Thomas also pointed out during this part of his evidence that the State markers 400-500 m away from the respondent's house were not over a mined area. 54 The Board also relied upon the evidence of Mr Kotze on this topic, to the effect that there was evidence of soil creep on two or three allotments 50-60 m west of the subject property. The point it sought to make was that this was also evidence that there was soil movement near to the respondent's property not due to mine subsidence, so it followed that the movement on the respondent's property must have been caused by the same mechanisms as on nearby properties. However, it is necessary to understand the context in which Mr Kotze gave this evidence. 55 Mr Kotze explained that, as an engineering geologist, it was his role to inspect the site and assess the mechanisms, or processes, which might have been causing the damage to the respondent's property. Those processes, typically, would include landslide or landslip, soil creep and reactive clay soils. He said he could find no evidence of significant landslide or landslip affecting the residence. He said he did observe soil creep in the two or three allotments 50-60 m to the west of the respondent's property. However, the slope angles on those properties were significantly greater than the respondent's property. He described the slope angles on those properties as being 20-25 degrees from the horizontal. Mr Kotze identified the presence of irregular and leaning trees and a hummocky ground surface on those properties as indicative of soil creep. He said there was no such evidence of soil creep on the respondent's property, with the exception of the front of the property. He assessed there was no soil creep acting around the rear and central portions of the subject allotment: [33]. 56 Before turning to the complaint as to the manner in which the trial judge dealt or failed to deal with this issue, reference should again be made to the joint experts' report. In the joint report prepared on 25 June 2007, at the conclusion of the first day of the hearing, reference was made to the absolute movements of SSM 7792 and PM 6327 and their movements relative to each other. It is apparent from the joint experts' report that a disagreement arose between the Board's and respondent's experts as to the purpose of the 8 May 2007 meeting at which the new stable datum point on the respondent's property was agreed upon. 57 From the respondent's experts' point of view, the purpose of the meeting was to reach agreement as to a stable reference point on the respondent's property. As I have already indicated above, that was agreed to. In the joint experts' report, the respondent's experts complained that the references in the minutes of that meeting to survey points in clay soils being influenced by changes in moisture level, and to the cause of damage to the local Technical College, constituted an attempt to introduce unrelated subsidence information, not applicable to the respondent's land. In particular, the respondent's experts complained that the comment in the minutes that where survey reference points were located in clay soils, they were likely to be influenced by changes in soil moisture regimes, was inapplicable. They also complained that the information was provided by surveyors instructed by the Board and was thus not independent. 58 It is apparent that when the information as to the movement of the registered State Markers came to the attention of the Board, and in particular, Professor Galvin, a view was formed that it demonstrated that the cause of the damage to the respondent's property was caused by movement due to reactive soils: [41]. The Board sought to reinforce this view by reference to the damage to the nearby Technical College, that had originally been thought to be due to mine subsidence, but was subsequently determined to be due to soil reactivity. 59 The evidence of soil movement 400-500 m away from the property had to be assessed along with other evidence. The most relevant of that other evidence was that the registered State Markers were not located over a mine, whereas a portion of the respondent's residence was. It is also relevant to note that Mr Kotze was able to explain why there was nothing to indicate soil creep on the respondent's property, notwithstanding his assessment that there was soil creep on two properties 50-60 m away. 60 The trial judge, at [154], noted that there was a great deal of "confusion, disagreement and debate about the accuracy and implications to be drawn from the survey information". His Honour found that: "Ultimately, nothing turned on the problem encountered by the surveyor as a consequence of unstable State marks as he was able to establish a workable and accurate relationship with other stable marks in the sandstone floor of the garage." 61 His Honour concluded that the survey measurements taken on the property were capable of providing a proper demonstration of the movements that had occurred on the property: [154]. 62 The 'discovery' that the State Survey Markers had moved relative to each other demonstrated no more and no less than that there was soil movement at a distance of 400-500 m from the respondent's property, in circumstances where there was no mine underneath the location of those markers. There was also evidence of soil movement 50-60 m to the west of the respondent's property. Evidence such as this may have been relevant to the experts in seeking to ascertain the cause of damage to the respondent's property. As with any investigative task, however, once the material is analysed, it has to be taken for what it in fact demonstrates. This evidence demonstrated that different mechanisms were causing movement in different places. The fact that movement could be found to be attributable to one mechanism in one area, did not thereby mean that the same mechanism was operative, or at least operative in any substantial way, in another area. 63 The respondent's experts explained why the movement of the permanent markers was not critical to the Board's case. 64 The Board's complaint, however, is that the trial judge failed to deal with its submission that the movement of the registered State Markers some distance from the respondent's residence confounded Dr Thomas' theory that subsidence was a cause of the damage to the respondent's house. 65 In my opinion, this complaint is not made out. His Honour, at [154], in the passage set out above, specifically rejected that the movement of the registered State Markers was of any consequence. His Honour's treatment of the survey information indicates that he was aware that in order to make accurate survey readings on the respondent's property, it was necessary to have a stable reference point. The surveyors' initial concern was that a stable point had not been established because the registered State Markers had been used as the reference points and those markers had been moving relative to each other. Once that problem was addressed by finding a stable reference point on the property, reliable survey data could be and was collected. 66 Accordingly, even though his Honour did not deal in express terms with the direct submission concerning non-subsidence movement 400-500 m away from the respondent's property, I consider his Honour properly considered the evidence relating to the registered State Markers and dealt with the relevance of establishing a stable survey mark on the respondent's property and considered the evidence that related to the respondent's property on that basis. In short, Professor Galvin's reliance on the movement of the registered State Markers did not establish that the damage to the respondent's property was caused by soil reactivity, nor did it confound Professor Thomas' conclusion that the damage to the respondent's property was due to mine subsidence. Accordingly, I would dismiss this complaint.

Item 2: angle of draw 67 The next aspect of evidence the Board contended was not dealt with by his Honour related to the concept known as the angle of draw. This concept was first referred to in Professor Galvin's report dated 21 June 2007, which Professor Galvin produced after the conclave of experts held on 19 June 2007. It is necessary to deal with that report in greater detail than merely focussing upon the angle of draw, so as to attempt to put that analysis in context. 68 In the report of 21 June 2007, Professor Galvin noted that after the first conclave, Dr de Ambrosis withdrew as a technical expert regarding mine subsidence and underground behaviour and that Dr Thomas was retained by the respondent to provide that aspect of expert evidence in her case. Professor Galvin observed that Dr Thomas had produced a report, dated 17 January 2007, that not only rejected the reasons Dr de Ambrosis had at that stage put forward as indicating that the damage to the respondent's property was caused by mine subsidence, but produced a totally new thesis to establish that mine subsidence was the cause of the damage. Professor Galvin observed that this new theory was outside his 30 years of international experience in geotechnical and mine subsidence engineering. Nonetheless, he considered that as geomechanics was an inexact science, due diligence required that careful consideration should be given to Dr Thomas' view. 69 Professor Galvin noted that at the second conclave, held on 13 March 2007, it had become apparent that there were inconsistencies and errors in the survey data collected up to that point and that there was confusion as to which plan of the shape of the respondent's house was accurate. It was after the second conclave that the new surveys were obtained. Those surveys were completed in March 2007. Thereafter, the meeting of experts was held at the offices of Craven, Elliston & Hayes on 8 May 2007 to which reference is made above. Professor Galvin reported that the first opportunity for the experts to meet in respect of the new survey data was on 19 June 2007, which constituted the third conclave. Professor Galvin stated that as a result of that conclave, he could finalise his conclusions, which are set out in the report of 21 July 2007. In that report, he stated that he remained of the firm opinion that the probability of mine subsidence being the cause of damage to the respondent's house was extremely remote. He advanced four reasons for that opinion: first, the mine workings were in pristine condition; secondly, theoretical considerations and analysis produced outcomes consistent with the mine workings having a very high level of stability; thirdly, there were a number of more probable causes for the structural damage to the respondent's house; and fourthly, there was factual evidence to demonstrate that those probable causes were active. He then gave reasons indicating why the mine workings were in a pristine and stable state. 70 Professor Galvin next dealt with surface subsidence. He said first, at para 4 of his report, that most of the survey measurements could not be considered precise measurements of ground movement, because the survey stations were located on surface structures, rather than in the ground. He stated reliance had to be placed on those survey stations installed at the base of structures. He stated this was not considered to introduce significant error. In this regard, it should again be noted that a stable datum point was established after the meeting of 8 May 2007. 71 Professor Galvin, at para 5 of this report, then said that the surveyed ground movements were not absolute, because measurement only commenced in 1998, after damage to the respondent's house was reported to the Board. He rejected a proposition advanced by Dr Thomas at the third conclave, that perhaps 15 mm of additional subsidence had occurred prior to the establishment of the survey stations. He advanced a number of reasons for this, including that as the respondent's house was displaying significant signs of structural damage as at May 1998, it is inconceivable and unheard of that such damage would result from only 15 mm of subsidence. He said: "As noted in the next point, the consequences of this level of movement are so negligible that this level of movement is ignored when surface subsidence [sic]." 72 The "next point" is, as I understand it, the point he makes in para 6 of the report in relation to the angle of draw. I will turn to that in a moment. I should record, however, that Professor Galvin then reiterated what was central to his thesis, namely, the survey results demonstrated that the survey stations were in a period of uplift, whilst other survey stations had displayed cycles of uplift and settlement. His firm opinion was that mine subsidence does not result in fluctuating ground levels. 73 Professor Galvin then turned his attention to the angle of draw. He stated at para 6 of his report that surface ground movement due to factors other than mine subsidence was a well-known phenomenon. He said: "The angle of draw is a term used in subsidence engineering to define the lateral extent of surface subsidence due to mine workings in an attempt to address this problem. It is the angle between the vertical and the line joining the edge of the mining void with the subsidence trough. Holla and Barclay (2000) report that: Kratzsch (1983) defines the trough margin as the point where a clear subsidence of 10 or 20mm can be found by levelling, provided 'there is no question of ground settlement through non-mining causes'. An estimate of non-mining subsidence movements in the proposed mining area can be obtained either by monitoring movements in an area located close to but outside the mining area or by monitoring movement over a period of time well before the commencement of mining. Measurement of surface movement in areas outside underground mining in New South Wales has shown that movements of up to 20mm can occur in response to such factors as soil moisture movement, variations in water table and other climatic fluctuations. Therefore, a cut-off subsidence of 20mm can be taken for fixing the limit of mining influence . " (Citations omitted; emphasis added) 74 Professor Galvin then analysed the latest survey results, which I understand to be the 2007 survey undertaken by Craven, Elliston & Hayes in March 2007. He considered the survey results demonstrated that, as compared to the May 1995 baseline survey, settlement exceeding 20 mm only occurred at seven of the survey stations. Of those seven, three exceeded 20 mm by 1, 2 and 3 mm respectively. He considered that those differences fell within the range of "survey error" which he said was 2 mm. Of the remaining four, he considered that two, survey stations 21 and 22, initially rose, before settling back to elevations of minus 32 mm and minus 30 mm respectively as at March 2007. The remaining two survey stations (stations 23 and 25) indicated movements of minus 51 mm and minus 40 mm respectively. 75 In questioning from the trial judge, Professor Galvin stated that the survey markers at stations 21 and 22, which revealed a subsidence of minus 32 mm and minus 30 mm, related to the movement of the slab of the floor of a lean-to on the side of the respondent's property. Professor Galvin noted that the lean-to was not keyed into the house and stated, "it's broken away from the house". He observed that it had been referred to in the conclave as an "anomalous slab". 76 The remaining two survey stations, stations 23 and 25, that showed movements of minus 51 mm and minus 40 mm, were located on the verandah extension of the house. In that regard, Professor Galvin considered the foundation design was problematic and the cause for its deficiencies was in the realm of the structural engineers. Professor Galvin expanded upon this in his oral evidence. He said: "So the point being that the two points that exceed the angle of draw, the criteria, the two points that are 40 to 50, are in the extension of the house which has been the subject of discussion amongst the structural engineers as to the nature of the foundations and their compliance with Australian design standards." 77 Professor Galvin said that this had been the subject of comment in the joint report and that others were better qualified to comment upon it. Professor Galvin concluded that the fact that the survey stations which exceeded 20 mm were consistent with his experience, that the measured movements at the residence were not unique to areas overlaying mine workings. 78 The relevance of the angle of draw was raised by the Board's senior counsel in Professor Galvin's oral evidence. Professor Galvin was asked to describe what the angle of draw meant, how it was applied and what its relevance was to the circumstances here. 79 Professor Galvin explained that any type of mining could result in some form of surface movement. He said the extent that the mine affects the surface is defined by the angle of draw. He explained it was calculated by going to the edge of the mine workings and drawing a vertical line to the surface. He said that surveyors measure the subsidence over the mine workings and continue to do so until they get down to a value of 20 mm or less. He said the surveyors stop at that point and draw a line to the edge of the workings. He explained that this point was over the solid, that is, the edge of the mine workings, not over the mine workings themselves. 80 He explained that before the mining starts, the surveyors run a line of pegs "over the solid and out over the proposed workings". He said that when the mining starts, the surveyors continue to measure the subsidence on the pegs and as they move back from the mine workings and back over the solid, the subsidence decreases until they get to a point where it is 20 mm. He said it is at that point, so far as subsidence engineering is concerned, that it is considered there is no distinction between subsidence from mine workings and subsidence from other natural ground movements. Accordingly, the surveyors draw a line from that point down to the edge of the mine workings. The angle between that line and a vertical line straight to the surface is called the "angle of draw". 81 Professor Galvin explained that when mining is undertaken and it is intended that structures on the surface be protected, the mine workings were designed so that they fell outside the angle of draw. By way of explanation, he said that if there was a power station near intended mine workings, the angle of draw would be established and once the workings get to within that angle, the mining is stopped, so that the subsidence from the mine workings does not affect the structure. He said that as a matter of mining practice in New South Wales, the angle of draw was 26.5 degrees. He further explained: "… [therefore] the lateral extent of mining - the extent of mining extends for half the depth, so if the depth is 10 metres I would expect subsidence to continue to 5 metres outside the edge of the workings." 82 Professor Galvin was then asked to explain the way the angle of draw operated in this case. He said: "In this case, beyond the abutment [that is, the barrier pillar] that runs diagonally across the house … [then, if] you were to go out another 5 metres you would then not expect under any type of mining with any type of circumstance, you would not expect to see effects of mining on the surface." 83 There were other references to the angle of draw in the evidence. On 18 April 2007, the respondent's experts, Dr Thomas, Dr de Ambrosis and Mr Kotze, prepared a position statement. The paper was stated to be in response to the position paper of the Board's experts dated 19 March 2007. The Board's position statement was not in evidence, although the respondent's position statement was. In that paper, the respondent's experts stated, at para 11.1: "We … disagree that a location directly above the barrier pillar will exclude damage by mine subsidence. The house's location 'hinged' over the barrier pillar, places it in the most vulnerable position for damage. Further, subsidence is not confined to the edge of the barrier pillar, as the 'draw angle' phenomenon associated with underground subsidence, causes ground settlement to extend back beyond the edge of the pillar ." (Emphasis added) 84 There was also a reference to the angle of draw in the joint experts' report, but only by the respondent's experts. The Board's experts had stated that the most severely damaged portion of the respondent's house was located directly above a barrier pillar "which is in unmined ground". The respondent's experts disagreed, reiterating what they had stated in their report of 19 March set out above at [*83]. 85 As will be apparent from the foregoing, the relevance of the angle of draw in this case was to explain that, as the survey evidence between 2005 and 2007 demonstrated there had only been downward movement greater than 20 mm in respect of four of the survey markers, when account was taken of "survey error" of 2 mm, it could not be concluded that the house was within the angle of draw. It followed, on the thesis advanced by Professor Galvin, that any downward movement of the ground was not referable to mine subsidence. However, the respondent's experts, who were not cross-examined on their report, or their comment in the joint report, refuted the Board's experts' reliance on the angle of draw and their contention that there could be no damage due to subsidence because of the location of the barrier pillar. 86 The trial judge, at [40], summarised the factors Professor Galvin took into account in reaching his opinion that mine subsidence was unlikely to be the cause of the damage to the respondent's house and in concluding that the most probable cause was reactive soil. In doing so, his Honour recorded Professor Galvin's evidence that movements of less than 20 mm were to be disregarded, because they could be attributed to and could not be distinguished from natural ground movement. His Honour then set out the evidence of the four measured survey points showing movements in excess of 20 mm. His Honour's short summary reflects the matters to which I have referred above. In setting out this information, his Honour did so without comment, merely summarising the evidence. 87 His Honour referred again to this part of Professor Galvin's evidence at [63], where he noted that Professor Galvin had agreed that two points at the rear of the house (survey stations 23 and 24) showed a trend of downward movement between March 2004 and March 2007. In the preceding paragraph, his Honour had referred to Professor Galvin's evidence comparing the first survey in 1998 with the last survey in 2007, where he had conceded that in absolute terms, the survey points had demonstrated a downward movement. Professor Galvin had qualified this by saying that in terms of trends, they were up and down. 88 At [78], his Honour again referred to Professor Galvin's evidence relating to the vertical movement at the rear of the house, noting that the Professor would not agree that they showed the ground trending downwards. Rather, he had maintained his position that the surveyed points indicated up and down movement, which supported his contention that the damage to the house was due to a combination of factors, including soil reactivity. 89 His Honour considered that in order to clarify the survey evidence generally and to resolve the disputes over what the readings demonstrated, it was necessary to have regard to the evidence of the surveyor Mr Grosfeld: [85]-[87]. Having briefly made reference to Mr Grosfeld's surveys, his Honour dealt with the oral evidence of Mr Hawkins, the soil engineer retained by the Board. In the course of his oral evidence, Mr Hawkins expressed the view that slope instability or landslip were an unlikely cause of the damage to the respondent's residence, but were more likely than mine subsidence: [88]. He was asked to explain what he based that opinion on. In doing so, he noted there was "no stable datum that is not on top of the coal seam": [88]. He said that all the evidence showed was a differential movement. Importantly, however, Mr Hawkins agreed that in the surveys taken from 2005 through to 2007, a "downward trend" was shown at the rear of the house. He agreed that a downward trend was inconsistent with soil reactivity being the sole cause of the movement: [98]. 90 It is also to be remembered that Professor Galvin's evidence was not the only evidence relating to the angle of draw. I have set out the respondent's experts' statement that subsidence was not confined to the edge of the barrier pillar, as the "draw angle phenomenon causes ground settlement to extend back beyond the edge of the pillar": see above at [*83]. This was a direct refutation of Professor Galvin's opinion, given in reports prior to the hearing and included in the joint experts' report. It was not the subject of a single question in cross-examination of the respondent's witnesses. 91 In my opinion, contrary to the submission advanced by the Board, his Honour clearly had in the forefront of his mind the evidence showing that there was a different rate of downward movement at different points on the house and that different witnesses placed different emphasis on this movement and proffered different reasons for it. The real question for his Honour's consideration, therefore, was not whether the house was located within the angle of draw, a matter which was never established in the evidence. Rather, the question was what was the significance of the extent of the movement, which was recorded as between 20 mm and 52 mm at different points of the property and whether what was being exhibited was a permanent downward movement, or as Professor Galvin considered, an up and down movement. His Honour explored these matters in his judgment. At the end of the day, his Honour did not accept the evidence of the Board's witnesses and he gave his reasons for not accepting their evidence. 92 In my opinion, it has not been established that the evidence relating to the angle of draw was critical to confounding Dr Thomas' theory. First, as I have said, it was never established that the respondent's residence fell within or without the angle of draw. Thus, although his Honour did not deal with the Board's submission as to the angle of draw head on, his approach to the evidence indicates that he clearly understood the basis of the challenge being made relating to the extent of movement of the land. 93 Secondly, Professor Galvin had used the angle of draw in a deductive sense, that is, because movements in the centre of the respondent's house had been recorded as being in the order of 20 mm, the house must not have been within the angle of draw. 94 Thirdly, the respondent's experts did not accept Professor Galvin's thesis relating to the angle of draw and they were not cross-examined. If the Board considered that Professor Galvin's evidence on this was critical, it has an obligation to cross-examine the respondent's experts. Its failure to do so meant that there was uncontradicted evidence that refuted this particular aspect of his evidence. 95 Further, other experts commented on the causes of the movements on the respondent's land, which was the essential matter for determination. In this regard, Mr Hawkins' evidence was particularly relevant. It was not consistent with Professor Galvin's evidence. Indeed, if anything, it confounded Professor Galvin's evidence, because he considered that there was no stable datum on top of the coal seam from which the angle of draw could have been established. 96 I would reject this ground of appeal.

Item 3: Voussoir beam analysis 97 The next complaint relates to the failure of the trial judge to deal with Professor Galvin's Voussoir beam analysis. This "analysis" first emerged in Professor Galvin's report dated 21 June 2007. In that report, Professor Galvin referred to the revised survey measurements undertaken by Craven, Elliston & Hayes accepted at the third conclave held on 19 June 2007. Professor Galvin notes that the survey measurements taken pertaining to survey stations above the old mine workings were summarised in a table which he had produced. He stated that from that table: "A comparison can now be made between these measured settlements and those predicted by Voussoir beam, or linear arch, analysis." 98 Professor Galvin explained that Voussoir beam analysis: "… finds widespread application to the calculation of ground movement on a micro scale (such as above a single narrow opening such as a tunnel) and on a macro scale (such as over mine openings exceeding more than 150m in width)." 99 He concluded: "Worst case Voussoir beam analysis based on simulating the 10m thickness of roof strata over the old mine workings as comprising a beam only between 1 and 2.75m thick that is required to support some 8 to 9m of pure deadweight load fails to produce settlement predictions that vaguely approach those measured over the old mine workings underlying [the subject property]. The outcomes are more consistent with those normally associated with beam deflection in the circumstances under consideration, albeit that the settlements are still significantly over predicted." 100 Professor Galvin's report of 21 June 2007 was tendered as part of a bundle of expert reports on 25 June 2007, the first day of the hearing. The tender came shortly before lunch on that day. At that point, there was considerable confusion relating to the tender of reports. It finally settled down, with Mr P McEwen SC, who appeared for the Board, stating that he would make two separate tenders. The first would be his experts' reports. He stated that those expert reports had "flags" on them for his Honour. Just before that, he had explained that he had spent the lunch hour flagging those parts of his experts' reports that he wanted his Honour to read. That bundle included Professor Galvin's report of 21 June 2007, which was solely devoted to the Voussoir beam analysis. There has been no indication in the Board's submissions to this Court as to whether that document was flagged for his Honour's consideration, although specific reference was made to this analysis in the Board's written submissions to his Honour at trial. 101 In its written submissions to this Court, the Board submitted that the Voussoir beam analysis demonstrated that in a worst case scenario, predictions of subsidence could not be obtained which correlated in any way with movements as measured at the respondent's property. The Board contends that this issue was dealt with in the joint report at pp 4-8. There is no reference to a Voussoir beam analysis in this section of the report. Rather, a number of issues are discussed, focussing on the movement of the house, including the movements around the T-junction, and the question whether these movements were merely due to cyclic movements, as contended by Professor Galvin. There was originally a complaint that the trial judge had failed to deal with that issue, however that ground of appeal was not relied upon. 102 There was no oral examination of Professor Galvin on this issue. There was no explanation, in his evidence, or in the Board's written submissions, to assist his Honour in understanding the mathematical table that Professor Galvin had produced. To the extent that the Board's written submissions refer to Professor Galvin having given evidence on this issue, the transcript reference does not relate to this analysis in express terms. There is a reference to the roof conditions and the pristine condition of the workings. Mr Hawkins also made reference to the stable condition of the roof, the thickness of the roof beam and the extent of settlement. There was no mention of the mathematical formula, which I understand to be the basis of the Voussoir beam analysis in this evidence. 103 The stable condition of the mine, to which the evidence of Professor Galvin and Mr Hawkins related in these passages, was dealt with by his Honour. Importantly, there was no cross-examination of any of the respondent's experts as to the validity of, or appropriate application of, this particular analysis. To the extent there was any cross-examination of the respondent's experts, it was in relation to the roof sagging, including the sandstone level above the coal. Although these matters appear to be part of the underlying concepts (no assistance was provided as to whether this was so), there was otherwise no reference to the mathematical analysis itself. 104 If the actual mathematical analysis undertaken by Professor Galvin was a critical matter, it should have been the subject of specific reference in the joint report, it should have been explained in the evidence, and the respondent's experts should have been cross-examined upon it. It is not sufficient, in a case involving technical expert evidence, if a party contends that particular evidence is critical, for a party to merely include it in a bundle of documents and then make a single reference to it in submissions to the trial judge. 105 In this case, it is not apparent that his Honour was ever directed to the evidence. To the extent that the Voussoir beam analysis was reflected in the comments in the joint experts' report and the evidence given by the experts at the hearing, relating to the degree and location of movement, and damage to that portion of the house located over the barrier pillar, there is no complaint that those matters were not dealt with by the trial judge. 106 I would also reject this ground of appeal.

(1) the pillars 107 Mr Hawkins, the Board's engineering expert (specialising in geology), surveyed the mine by drilling bore holes into which a CCTV camera was inserted, both to inspect the walls of the bore holes in the roof stratum, as well as to survey the layout and condition of the mine workings. Mr Hawkins explained in his evidence that there had been very little "spalling" from the walls of the pillars, and there was very little material accumulated on the floor at the base of the pillars. The roof was intact, with very few areas suggesting that rocks had fallen from the roof. Mr Hawkins had also examined the record traces of the mine and had concluded that the factors of safety of the pillars was such that pillar failure would definitely not be expected. 108 Professor Galvin had expressed an opinion that with the amount of surface movement recorded on the respondent's property, it would be expected that the pillars would be in a highly distressed condition if that movement was due to mine subsidence. However, the CCTV footage demonstrated that the pillars were not in a highly stressed state. 109 This evidence was significant, in the Board's submission, because Dr de Ambrosis had originally advanced a theory that the relatively recent onset of damage to the house was more in keeping with the character of subsidence where a roof or pillar had collapsed, whereas the CCTV footage showed that had not occurred. However, Dr de Ambrosis' evidence on this was not relied upon by the respondent, and Dr Thomas was put forward as the respondent's expert on mine subsidence. Dr de Ambrosis, in cross-examination, reminded senior counsel for the Board of this. He said that initially he had thought that the ground settlement at the uphill end of the house was most likely related to mine subsidence and that he considered one of the mechanisms as having caused that was pillar failure. Dr de Ambrosis stated, however, that he had subsequently deferred to Dr Thomas, regarding the mechanism of mine subsidence. In his report, upon which the respondent did rely, Dr de Ambrosis stated: "… what we postulate as the most likely cause is not any voluminous and/or catastrophic collapse of the roof of the old workings either locally over an old intersection or more generally, as might occur if several pillars collapsed - quite clearly the recent drilling has shown this not to be the cause. What we propose as more likely is that of elastic shortening of the pillars due to an increase in stress induced in them by time related spalling." 110 The trial judge dealt with the CCTV evidence in a number of passages in his judgment. It is not necessary to refer to all of them. It is sufficient to mention his Honour's observation, at [153], where he noted the CCTV footage showed that the roof and pillars were substantially intact, in that they had not collapsed. His Honour went on to observe, however, that he was satisfied with Dr Thomas' theory, which did not depend upon the pillars having collapsed. 111 It therefore follows that this aspect of Professor Galvin's opinion was not critical to confounding the respondent's case, as Dr Thomas' theory did not depend upon the presence of distressed pillars.

Item 5: volume of material 112 Professor Galvin, in the course of his oral evidence, stated that if Dr Thomas' theory was that the settlement on the surface was due to surface material disappearing, that is, by being washed into the mine, then "tonnes of material" had disappeared. In re-examination, Professor Galvin calculated this to be conservatively in the order of 10 m3, or 25 tonnes of material. Professor Galvin also stated that if the explanation for the damage was based on a percolation theory and material was being lost, he would expect that bigger subsidence troughs would have developed. 113 In his additional submissions to this Court, senior counsel for the Board provided a number of other references to the transcript where this issue was said to have been referred to. A review of those references and material around them indicates that they do not appear to relate to this question. Nonetheless, the complaint made is that the CCTV footage did not demonstrate that material of the volume indicated by Professor Galvin had escaped into the mining void. It was said that this was not addressed by his Honour. 114 It is correct that his Honour does not specifically deal with this evidence, which was referred to by the Board in its written submissions to the trial judge. As I have said, it arose during the course of Professor Galvin's cross-examination and he gave evidence in re-examination as to the quantity of material that would have been involved. By the time Professor Galvin gave this evidence, the respondent's experts had completed their oral evidence and no attempt was made to recall them. If this matter was of critical importance to the Board's case, then it ought to have been the subject of discussion in the joint experts' reports and Dr Thomas should also have been cross-examined on it. Rather than being critical, it seems to have been little more than a 'thought' which occurred to Professor Galvin during the course of his evidence. 115 In any event, it is apparent from Dr Thomas's evidence that there was no question of tonnes of soil from the top being lost into the mine. Rather, it was a question of gradual settlement that goes to the surface as the softer materials in the rocks wore away and the rocks themselves started to settle with the settlement going from the bottom up to the surface. 116 For the foregoing reasons, this ground of appeal should also be rejected.

Item 6: movement at 90 degrees to the centre line 117 The Board asserts that the evidence of Mr Hawkins and Professor Galvin as to the expectation that in the event of subsidence, movement would be at 90 degrees to the centre of the mine roadway, was not contradicted by the witnesses for the respondent. It was submitted that the fact that the movements were not towards the centre line contra-indicated the likelihood that the damage to the respondent's property was caused by mine subsidence. 118 This evidence arose during the course of the examination of the expert witnesses. There was no reference to this factor in any of the experts' reports or in the joint experts' report. It was first raised by Mr Hawkins. He was explaining why he rejected the notion there was any mine subsidence affecting the premises. One factor he considered to be relevant was that if the movement was related to mine subsidence, it would be expected that movement would either be at 90 degrees to the centre line of the roadway, or diagonally towards the T-intersection. He said the survey readings indicated the direction of movement had been obliquely out into the workings, but not towards the centre line. Some movements had been essentially parallel to the direction of the mine workings. Dr Thomas was asked about this in cross-examination. Senior counsel for the Board referred to Mr Hawkins' evidence and said: "Q: You heard him give some evidence about the corners and the way they moved? … It was in relation to movement relative to subsidence, if the movement was related to subsidence, rather, you would expect to see 90 degrees to the centre of the roadway or diagonally towards the T-void the effects that you're looking at." 119 There then ensued a discussion between Dr Thomas and senior counsel for the Board, during which Dr Thomas questioned what precisely Mr Hawkins had been talking about. In particular, Dr Thomas considered that Mr Hawkins was referring to the movement of the house on the surface and pointed out that the house was independent of the ground. He went on to explain why the house would move in certain ways, because it was sitting on the slab and pier foundations. 120 It is not correct to say, therefore, that Mr Hawkins' evidence was not contradicted by the respondent's experts. The matter was dealt with by Dr Thomas, who, to the extent he understood what Mr Hawkins was talking about considered that in this part of his evidence, Mr Hawkins was dealing not with movement of the ground, but with movement of the house. 121 The Board contends that Professor Galvin also dealt with this evidence in re-examination. However, the suggested transcript reference by senior counsel does not appear to have any connection with this topic. Senior counsel for the respondent also observes in his written supplementary submissions that the surveys and the direction of movement referred to by Mr Hawkins and upon which he based his comment, were not identified in the evidence, in submissions, or in addresses. 122 The trial judge dealt with Mr Hawkins' evidence at [53]. His Honour, at [54], noted that Mr Hawkins agreed there may not be one single factor causing movement of the house and noted Mr Hawkins' acknowledgment that other possible factors were construction problems with the residence itself, soil creep, soil reactivity and discharge of water from upslope. His Honour made an overarching observation, however, that Mr Hawkins' comments in relation to "possible causes" were not definitive, because his brief was only to determine whether or not the cause was mine subsidence. 123 His Honour dealt further with Mr Hawkins' evidence, at [88] ff, as part of his analysis of the cross-examination of Mr Hawkins. His Honour observed that Mr Hawkins was not asked to carry out a detailed investigation into the actual cause of the damage. Rather, his instructions were confined to answering the specific question whether the cause of the damage was mine subsidence or not. His Honour recorded, at [89], Mr Hawkins' evidence in cross-examination that he would require "a whole lot more data" before he could confirm the cause was not mine subsidence. 124 Given the confusion as to what Mr Hawkins was referring to in his evidence and the failure of this part of his evidence to be dealt with in any meaningful way by the Board in the proceedings before the trial judge, it is unsurprising that his Honour did not advert to it. In any event, the Board has not demonstrated this evidence was critical to confounding Dr Thomas' evidence. 125 I would also reject this ground of appeal

Conclusion on the appeal 126 It follows that, having concluded that the Board has not established that any of the matters upon which it relied was critical to confounding Dr Thomas' evidence, the appeal must fail.

The cross-appeal 127 The respondent raises four grounds by way of cross-appeal. However, those grounds may be reduced to two essential issues: first, whether his Honour's apportionment of 60 per cent / 40 per cent as between the rear and centre of the house, and the steps and verandah, was within an appropriate discretionary range. In this regard, the respondent contends those proportions were erroneous and were not supported by the evidence (grounds 1, 2 and 3). The second issue is whether his Honour erred in ordering that the compensation to which the respondent was entitled was to be assessed by reference to the value of the house and other improvements to the land. 128 The respondent's claim for compensation was made under s 12 of the Mine Subsidence Compensation Act. That section provides, relevantly: " Claims for damage arising out of subsidence

(1) Claims may be made under this Act for payment from the Fund of : (a) compensation for any damage to improvements that arises from subsidence , except where the subsidence is due to operations carried on by the owner of the improvements, (b) an amount to meet the proper and necessary expense incurred or to be incurred as a result of such damage in : (i) building retaining walls or bolting together or underpinning or otherwise supporting , raising or repairing buildings and walls, (ii) altering the approaches to or the levels of lands or buildings, (iii) raising, lowering, diverting or making good roads, tramways, railways, pipelines, bridges, fences, sewers, drains or other improvements, (c) an amount equivalent to the rent which would have been payable for such period as may be prescribed in respect of any buildings or works which by reason of such damage are untenantable, under repair or in course of construction, or where such buildings or works or any part thereof are or is occupied by the owner thereof such sum in lieu of rent as the Board deems just, (d) compensation for any damage to household or other effects that arises from subsidence, except where the subsidence is due to operations carried on by the owner of the household or other effects. … Where damage, caused by subsidence, to an improvement is greater, by reason of the negligent or improper manner in which the improvement was constructed or maintained, than it would have been had the improvement not been so constructed or maintained, the Board may reduce the amount of compensation in respect of the damage by such amount as it considers is attributable to the fact that the improvement was so constructed or maintained." 129 Senior Counsel for the respondent indicated to this Court that the primary basis upon which it sought compensation was under s 12(1)(b). That is not apparent from the original claim filed with the Mine Subsidence Board, nor from the Application and Points of Claim filed in the Land and Environment Court. Rather, the claim made was a "claim for damage". 130 However, and importantly, the respondent indicated that not only did she seek to have her compensation assessed under s 12(1)(b), it was possible that the Board might act under s 13 and purchase the damaged improvements and the land, or alternatively, resume the land, or itself effect remedial works. She indicated that was, and still is, a course she would urge upon the Board. Should the Board decide to enter into an agreement to purchase the improvements or to undertake the works, then s 13(1) provides that the Board may, in lieu of making payments in respect of claims under s 12: "(a) agree with the owner of the land or improvements to which the claim relates for the purchase of the land, or the improvements and the land on which the improvements are erected, or any estate or interest therein, at a price not greater than an amount determined, as at a date not more than one month before the date of the agreement, as being the value of the land, or the improvements and the land, or the estate or interest therein, as the case may require, by a valuer with the prescribed qualifications who shall be appointed by the Board to make the valuation (which appointment the Board is hereby authorised to make), without regard to any damage caused by subsidence or by works to prevent or mitigate any such damage, (b) execute or cause to be executed such works as may be necessary to restore the damaged land or improvements to a condition as nearly as practicable equivalent to that in which such land or improvements were before the damage to such land or improvements arose." 131 His Honour, having found the house had been destroyed for habitable purposes, held that the major contributing cause of the damage was the settlement at the rear, due in major part, to the presence of the abandoned mine workings: [157]. His Honour estimated that the proportion of the damage due to mine subsidence was more than half. He determined it was 60 per cent. His Honour noted, at [158], that the parties had agreed that an assessment of a percentage of damage would be sufficient to enable a commercial settlement to be reached. His Honour then concluded that the respondent: "… is entitled to compensation for damage to her house pursuant to s 12 of the Mine Subsidence Compensation Act 1961 in such sum as represents 60 percent of the value of the house and other improvements on the land other than any improvements situated forward of the house in the direction of Birdwood Street." (Emphasis added) 132 The respondent has informed the Court in her written submissions that it had been agreed between the parties that his Honour should apportion the damage to the house in respect of the areas damaged by mine subsidence. However, there is an issue between the parties as to the precise extent of the agreement. 133 The respondent contends that there was no agreement that his Honour determine the compensation to which she was entitled by reference to the 'value' of the improvements. As I have indicated, the respondent asserts that her claim was directed to the provisions of s 12(1)(b)(i). She contends that in order to assess the damage claimable under that section, it was necessary to find the percentage of damage to the house. That involved determining which portions of the house had been damaged, not what percentage value of the house was payable by way of compensation. Senior counsel explained in his written submissions that: "The reason why the parties indicated to His Honour that the parties would reach a commercial settlement was because the Board also had power under section 13 to agree to resume the land. It was envisaged that the commercial resolution of the matter would be based upon the costs associated with repairing the damage to the house in comparison to the question of resumption. In making the orders that he did, based upon the value of the house, His Honour did not make orders in accordance with either section 12 or section 13 and therefore this Court should re-assess the claim in accordance with the requirements of the sections. In order to assist the Court in this regard, we have provided the surveyor's estimate of the areas of the house which were damaged ..." 134 Senior counsel for the respondent further argued that, in making the assessment he did, his Honour failed to make an order under either s 12 or s 13. It was submitted that this Court could re-assess the claim in accordance with the requirements of the sections. 135 Although the Board sought to uphold his Honour's judgment as being within the agreement, it was, I believe, conceded that there had been no express agreement that his Honour determine a proportion of the "value of the house". The Board's position is, however, that his Honour was invited to apportion damage in respect of the areas of the house damaged by mine subsidence. It was said that the agreed position was that it was open to his Honour "to identify a percentage of the value of the house" (original emphasis). It was submitted that this was what his Honour did in selecting the split of 60 per cent / 40 per cent and then attributing that percentage to the basis of the compensation to be awarded viz, to the value of the house. It was submitted that in any event, that approach was open to his Honour under s 12(1)(a). 136 It was further submitted that the only pragmatic and practical way to make an assessment of the compensation to which the respondent was entitled, based on damage attributable to mine subsidence for which the Board was liable, was for a percentage calculation of the type made by his Honour to be identified and for that to be implemented by reference to the value of the structures found to be impacted by mine subsidence. 137 When the parties requested his Honour to make an assessment of the proportion of damage due to mine subsidence they did so on the basis of an approach taken by Bignold J in Cogger v The Mine Subsidence Board (Land and Environment Court, Bignold J, 31 July 1992, unreported). In that case, there was an issue between the experts as to whether damage to the applicant's house was due to the shrink/swell movement of soils upon which it was built, or to mine subsidence. Bignold J accepted the evidence of the applicant's witness that some 70 per cent of the damage, by way of major cracks in the internal walls of the applicant's house, could be attributed to mining-induced subsidence. The question arose as to how the Court should deal with the applicant's claim for compensation. His Honour ordered that the Board's refusal of the claim for compensation under the Mines Subsidence Compensation Act should be set aside. He remitted the matter to the Board for the purposes of assessing the amount of compensation payable from the fund under the Act. In that regard, his Honour stated, at 7: "In respect of assessing the quantum of compensation the Board will be assisted by my finding that some 70% of the damage caused by the serious cracks should be regarded as arising from subsidence." 138 The trial judge in this case was referred to Cogger, and both parties requested that his Honour adopt the same approach as had been adopted by Bignold J. This is apparent from the transcript of submissions to his Honour made on 6 August 2007. In those submissions, senior counsel for the Board referred his Honour to the approach taken by Bignold J in Cogger, including the remittal of the matter to the Board for the assessment of compensation. The following exchanged ensued: "HIS HONOUR: I see.

NOCK: And indeed, your Honour those are my instructions, to ask your Honour to do a very similar thing.

McEWAN: And if your Honour comes to that conclusion, we--

McEWAN: I thought that might be of assistance your Honour." 139 The question as to how his Honour should proceed if the appeal was successful was raised by his Honour at the conclusion of the respondent's senior counsel's address: "HIS HONOUR: Just allay my concern about the way you're leaving the potential, if relevant assessment of compensation. Is there an appeal against the board's decision in that respect?

HIS HONOUR: There'd be no question of the appeal rights having been exhausted by these proceedings if that became necessary I take it, and secondly there's no prospect that if a further appeal arose limited to the issue of quantum of damages the issues would be a reactivation of the issues in this case. If I make a finding as Justice Bignold did to 40 per cent, well it's 40 per cent of something.

HIS HONOUR: He found 70 per cent, but it's a percentage of damage. Now was Justice Bignold faced with contributing factors?

HIS HONOUR: The earthquake which is the equivalent of our land slip or whatever it is at the front.

NOCK: Probably easier for your Honour in this case, Justice Bignold in his case I suspect because the nature of the earthquake damage would have been not as clear cut as the damage situation we've got her in this place and probably not - I mean here it's related to a specific area we say and I think we all agree about it, so Bignold J probably had a much more difficult task than your Honour.

McEWAN: Can I say this your Honour, we didn't know about this case until last Friday. That is Justice Bignold's. And without binding my client your Honour the board in fact deals with compensation throughout the State on a regular basis in situations not dissimilar to the one that your Honour's contemplating here. And those instructing me tell me that no appeals have ever arisen in relation to the compensation to be paid out of the fund to those persons whose properties have been damaged because it's resolved in a proper way which is consistent with the public duty the board has.

HIS HONOUR: Well if I'm told from both sides of the bar table that there would be an appeal irrespective of that fine record and that the issues on that appeal would not require a re-agitation of the whole of this case then I'm confident that that may well be a satisfactory way of dealing with the issue that I raised last Friday in the event that I make a certain finding. And of course we're only discussing it on the basis of the prospect that the court may but not necessarily make such a finding." 140 As the Board refused the respondent's claim, it has not made any assessment of the respondent's claim for compensation under s 12. Nor has it made any determination of whether, rather than pay compensation, it will exercise its powers under s 13(1)(a) or (b). So far as I can ascertain, there was no evidence before the trial judge of the value of the property or the cost of repair. This seems consistent with the intention of the parties that there would be a post-trial commercial negotiation of the amount of compensation payable and that if that failed, there would be an available appeal to the Land and Environment Court under s 12A in respect of any assessment of compensation that the Board in fact made. 141 During the course of the appeal, senior counsel for the respondent made statements from the Bar table indicating what the value of the property was and what the cost was to repair the house. To the extent that it is appropriate to refer those statements, it is sufficient to note that the cost of repairing the building would be considerably in excess of its value. 142 This state of affairs raises the question of what this Court can and should do. The respondent has urged that the Court should itself "re-assess the claim in accordance with the requirements of the sections". This submission, however, fails to come to grips with the problem that arises from the manner in which the parties conducted the matter before the trial judge. I have already referred to the fact that there has been no determination of compensation by the Board, nor was there any evidence before the trial judge either of the value of the house or the property (that is the house and the land) or the cost of repairs to the property. 143 More relevantly for present purposes, however, is that there was no argument before the trial judge as to the proper basis for the assessment of compensation to which the respondent was entitled. The respondent contends that the claim she seeks to advance is under s 12(1)(b). She has not had an opportunity to advance that case, either before the Board or before the Court. However, by making the determination that the respondent was entitled to compensation of 60 per cent of the value of the house and improvements (other than those at the front of the property), his Honour has effectively foreclosed the respondent's case, in circumstances where she has not had a hearing at either the Board level or before the Court as to the basis upon which she is entitled to compensation. 144 However, I am of the opinion that his Honour was entitled to make an assessment of the extent to which the property was affected by subsidence. Indeed, in a case where it was conceded that a portion of the property was not affected by mine subsidence, the question for his Honour was whether the remainder of the property was so affected. It was appropriate for his Honour in those circumstances to specify the parts of the property (if any) that were affected by subsidence. Alternatively, it was open for him to specify the proportion of the property that was so affected. However, in doing so, it was necessary for him to specify what he was referring to, as the matter needed to be remitted to the Board for a determination of the compensation payable. As is apparent from the statutory regime, there are a number of differing bases upon which compensation might be paid. 145 The respondent contends that his Honour's finding as to the proportion of damage due to mine subsidence was so unreasonable as to amount to appealable error: House v The King [1936] HCA 40; (1936) 55 CLR 499. 146 The trial judge at various times in his judgment referred to the damage to the house that was caused by mine subsidence as "the centre and rear of the house", the "core and rear sections", and "rear and central portions" [33], [135], [144], [145]. At [144], his Honour held he was not satisfied that the damage to the core and rear sections was solely as a direct consequence of the presence of reactive soils, landslip, groundwater movement, soil creep or inadequate foundations and footings. His Honour said: "… I have not been persuaded on the balance of probabilities that the damage to the core and rear sections of the house is solely as a direct consequence of the presence of reactive soils, landslip, groundwater movement, soil creep or inadequate foundations and footings. They may have collectively rendered the house more vulnerable to damage but, even in combination, I am not satisfied it is more likely than not that the damage would have occurred without there being a further major catalytic, innovative, primary or initiating cause."

That further " cause " was, on his Honour's finding at [153]: "… the presence of the abandoned mine [which] has contributed in a major way to the damage caused by sinking or settlement of the rear section of the house which carried through into the main part." 147 His Honour then dealt with the evidence that the roof and pillars of the mine were substantially intact. Nonetheless, he was satisfied that: "… the truncation of the stratum that created a void has facilitated the process described by Dr Thomas thereby enabling the surface to subside or settle to a degree that is sufficient to destroy the stability of the house structure in the southern section and to an extent that would not have occurred solely as a consequence of any other identified potential factor." 148 His Honour then stated his conclusion, at [157], that the major contributing cause to the house being destroyed for habitable purposes was the settlement at the rear due "in major part to the presence of the abandoned mine workings". 149 The respondent relies upon Exhibit C, a survey drawing of the house and surrounds, as demonstrating that the core and rear of the house, which his Honour found was subject to mine subsidence, make up more than 60 per cent of the house. It was submitted that Craven, Elliston & Hayes have estimated that as a proportion of the total area, the core and rear sections of the house constitute approximately 91 per cent, not 60 per cent. As I understand it, the estimate of 91 per cent was a calculation made after trial and was not the subject of specific evidence at the trial. 150 The Board objects to any reliance upon a calculation made by Craven, Elliston & Hayes based upon Exhibit C. It contends that this is new evidence which should not be admitted by the Court. It was further submitted that it was inaccurate for the respondent to assert that the only apportionment of damage that was required was between the front steps and verandah, which had not been damaged by mine subsidence, and the remainder of the house, which had been damaged by mine subsidence. It was submitted that this submission was not put at trial. Rather, it was said that at trial the respondent's experts had identified a "hinging action" over the barrier pillar located across the middle of the respondent's house. This was identified as the centre line of the barrier pillar over which the house folded: see joint experts' report. 151 The Board contended that the basis of his Honour's finding of 60 per cent could be found by a comparison of the diagram at p 7 of the joint experts' report (Exhibit D) in relation to the hinging action and the effect of soil creep at the front of the house. It was submitted that it was apparent that his Honour accepted this was the case, as it explained his assessment of 60 per cent of the damage being due to subsidence. I would also add that at para 16 of the joint experts' report there is a reference by the Board's experts to the most severely damaged portion of the house, being the front 55 to 60 per cent, located above a barrier pillar. The Board's experts contended there would be no subsidence above the barrier pillar. The respondent's experts, however, disagreed that the most severely damaged portion of the house constituted 55 to 60 per cent of the dwelling. They also considered that the hinging effect of the structure over the pillar was part of the effect of mine subsidence: see above at [*84]-[85]. Indeed, they considered that the location of the house, "hinged" as it was over the barrier pillar, placed it in the most vulnerable position for damage. 152 I do not agree that a consideration of the plan in the joint experts' report either provides the explanation for his Honour's assessment, or supports that assessment. If his Honour did rely on the plan, it might have been expected he would have made some reference to it. More particularly, if he considered that the damage to that portion of the house over the barrier pillar was not due to subsidence, he would and should have said so. He made no such finding. 153 A 60 / 40 division of the land is possibly supported by the plan in the joint experts' report. An estimate of the area from the verandah to the boundary of the land (including structures on the land) at the front is about 40 per cent (assuming the plan is drawn to scale, of which there was no evidence). However, there is no indication in his Honour's reasons whether that was the basis of his assessment and that approach does not appear to accord with his earlier reasoning, where he makes reference to the structures only. By contrast, a consideration of the survey plan which was Exhibit C, which was drawn to scale, supports the respondent's submission if regard is had to the proportion of damage to the house. It is not necessary in this regard for the Court to be concerned with the surveyors' post trial assessment of the relative percentage. A visual inspection of the plan is sufficient. 154 In my opinion, on the premise that his Honour only had regard to the extent of the physical damage to the house and that damage due to subsidence included the portion of the house over the barrier pillar, his Honour's assessment of 60 per cent was so unreasonable that appellate intervention is required. However, if his Honour intended to act upon the Board's experts' opinion that the area over the barrier pillar was to be excluded, then error of law has also been established as his Honour failed to make a primary finding of fact to support his conclusion and failed to give reasons. Likewise, if his Honour was basing his assessment on the area of the property rather than a proportion of the structures: see Waterways Authority v Fitzgibbon [2005] HCA 57; (2005) 221 ALR 402 at [129]-[130]. 155 For example, a possible explanation for his Honour's assessment of 60 per cent in [157], is that he considered the extent of the damage to the house (other than the verandah and steps) due to mine subsidence was 60 per cent, having regard to his finding that mine subsidence was the "major cause", but that there were other causes (for example, soil creep) which would have made the house more vulnerable to damage. However, there is no statement in his Honour's reasons that this is the approach he took. Nor did the respondent raise any challenge to the finding that suggested a misconstruction of s 12 and s 13. Likewise, there was no submission by the Board that s 12 required or permitted that approach. Rather, its submission was confined to supporting his Honour's finding as to proportion. As I have indicated, the Board's position seems to relate to a proportion of damage to the land affected by subsidence and not merely to the structures on the land. 156 I should indicate that even if this was a possible approach to the assessment of an entitlement to compensation under s 12, there would have been a real question as to whether such an approach was available in this case, given his Honour's finding that although there were other factors that contributed to making the house more vulnerable, the damage would not have occurred without the effect of the mine subsidence. 157 On whatever basis his Honour proceeded, and error of law having been established, the question arises as to what this Court can and should do. The respondent sought that this Court itself determine the correct percentage. However, the matter is not so straightforward. As I have indicated, the appeal to this Court is on a question of law only: s 57 of the Land and Environment Court Act. That section provides: "57(1) A party to proceedings in Class 1, 2 or 3 of the Court's jurisdiction may appeal to the Supreme Court against an order or decision (including an interlocutory order or decision) of the Court on a question of law.

(2) On the hearing of an appeal under subsection (1), the Supreme Court shall: (a) remit the matter to the Court for determination by the Court in accordance with the decision of the Supreme Court, or (b) make such other order in relation to the appeal as seems fit." 158 The operation of s 57 was considered by this Court in Thaina Town (On Goulburn) Pty Ltd v City of Sydney Council [2007] NSWCA 300; 156 LGERA 150 in relation to the question whether this Court could itself make an order as to costs, if it found that the order made by the primary judge was wrong. Previously, this Court had held that it could not do so and the matter had to be remitted for re-determination: see Maurici v Chief Commissioner of State Revenue (2001) 51 NSWLR 673. The decision in Maurici had been based on the provisions of s 32(2) of the Compensation Court Act 1984. Decisions relating to that section had held that the Court's power extended only to correcting errors of law. The Court could not make findings of fact, nor exercise a discretion so as to finally dispose of a matter: see North Broken Hill Ltd v Tumes [1999] NSWCA 309; (1999) 18 NSWCCR 412. 159 In Thaina Town, it was held that s 57 was not in identical terms to s 32(2) and that the Court had power to re-exercise an erroneously exercised discretion as to costs: see Spigelman CJ at [102] ff. His Honour expressly refrained from reconsidering the earlier line of authority relating to the restrictions on this Court making findings of fact. His Honour confined his comments to the statement, at [102], that "[p]lainly, it is generally undesirable for this Court to exercise such a power, if any". 160 On one view, the error in the present case related to a factual finding of an evaluative nature, that is, the percentage of the damage to the house that was due to subsidence. If that was the error, appealable error in the House v The King sense has been demonstrated. House v The King error is typically found where a discretion has been wrongly exercised. However, it is also invoked where the error made is in respect of an evaluative judgment of the kind here. That being so, it might be argued that this Court would be in as good a position as the trial judge to make the assessment and that on the authority of Thaina Town, this Court could do so. 161 However, even if this Court itself makes the determination of the percentage of damage due to subsidence, the relevant error may not be of the House v The King type. The error may have been a failure to engage in a proper fact finding process and a failure to express reasons for any finding made. 162 It follows, in my opinion, that the matter should be remitted to the Land and Environment Court for determination. It will be a matter for the Court to decide whether it is appropriate to make any further determination itself, or whether the matter should merely be remitted to the Board for the determination of the compensation to which the respondent is entitled. If it decides to remit the matter, then it would be on the basis of there being a binding decision of the Court that there has been damage to the house and other structures on the land, other than the front verandah and steps and any structures situated forward of the house caused by mine subsidence: see [158]. 163 His Honour was also asked to award compensation pursuant to s 12(1)(c) in respect of the rent payable by the respondent whilst unable to live in her house. The Court has been told this formula was agreed between the parties and was the subject of evidence before his Honour. In those circumstances, the parties should be able to reach agreement as to the proper order to be made in that regard. Such an order should be made in the Land and Environment Court. 164 There was also a separate application relating to costs that was not dealt with by his Honour. However, the Board informed the Court that the question of costs has been resolved. As I understand it, no order as to costs has been made. Clearly that should also be attended to. 165 Accordingly, the orders I propose are as follows:

3. Remit the following matters to the Land and Environment Court for determination in accordance with these reasons and for the making of orders for the disposition of the application (including orders of remitter to the Board) relating to: (a) the compensation to which the respondent is entitled as a result of damage to her property due to mine subsidence; (b) the compensation to which the respondent is entitled in relation to rent under s 12(1)(c) of the Mine Subsidence Compensation Act 1961; (c) costs of the hearing before Talbot J;

4. Order that the appellant (the Mine Subsidence Board) pay the respondent's costs of the appeal and the cross-appeal. 166 McCOLL JA: I agree with Beazley JA. 167 NICHOLAS J: I agree with Beazley JA. **********

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