Day v Lyons
[1989] TASSC 100
•8 June 1989
B22/1989
COURT: SUPREME COURT OF TASMANIA
CITATION: Day v Lyons [1989] TASSC 100; B22/1989
PARTIES: DAY
v
LYONS
FILE NO: 607/1987
DELIVERED ON: 8 June 1989
JUDGMENT OF: Crawford J
Judgment Number: B22/1989
Number of paragraphs: 44
Serial No B22/1989
File No 607/1987
DAY v LYONS
REASONS FOR JUDGMENT CRAWFORD J
8 June 1989
This is an action between neighbours for damages for withdrawal of the natural right to support of land and for a mandatory injunction to compel construction of a sufficient retaining wall, to prevent further subsidence of the plaintiff's land. The most difficult matter arising for determination is whether an excavation on the defendant's land withdrew support and caused the plaintiff's land to move and certain improvements to be damaged.
GENERAL BACKGROUND
The plaintiff purchased his two storey brick house at 60 Fisher Avenue, Sandy Bay in 1984. It was constructed in 1982. The defendant purchased the neighbouring vacant land immediately to the north east at 58 Fisher Avenue, in March 1986. For the purpose of building the house in which he now resides, he had an excavation carried out near his boundary with the plaintiff's property, in about August 1986. The house was constructed between August and December 1986 and he then moved into residence.
The two properties front on to the south eastern side of Fisher Avenue. At that point the avenue proceeds in a north easterly direction down hill, described by a witness as a slope of about 12%. The two blocks of land are roughly rectangular and run down hill in a south easterly direction away from the avenue. The evidence establishes that the natural slope of the land of both blocks is, when viewed from the avenue, roughly 30 degrees to the north of the common boundary of the two blocks. A consultant engineer, Mr Casimaty, said that "the maximum slope in the maximum direction" would be approximately 30 to 33 degrees. Whether or not that statement is accurate, it is a steep slope. A sketch plan, adopted with alterations from one of the exhibits, shows part of each property.
The plaintiff's house can be approached from the avenue by a bitumen driveway. Running down the north eastern side of it is a concrete kerb. Across the bottom or south eastern side of it is a concrete drain and kerb which extends along the north western side of the house and out to the common boundary, meeting and joining with the kerb on the north eastern side of the driveway. In fact the drain and its kerb extends about 1.6 metres north easterly from the northern corner of the landing shown on the plan and encroaches into the defendant's property by about 100mm The concrete of the drain and kerb is not reinforced. At a point in the drain there is a vertical 90mm PVC pipe for the purpose of carrying away storm water from the drain. It is shown in the plan as a "drainpipe". On the north eastern side of the plaintiff's house, at the northern corner, is a concrete landing supported underneath on the north eastern and south eastern sides by a brick wall. The bricks of the wall are different from those of the house indicating that the landing was probably constructed at some time after the construction of the house. Just to the north east of the landing is a concrete step and path running downhill away from the drain, past the landing and the north eastern side of the house until it reaches the rear of the house. At that point it butts at the eastern corner of the house, with a concrete path running along the rear (south eastern) side of the house.
At the time the plaintiff purchased his property there was and still is a paling fence dividing the two properties. It has since been discovered to be 100mm on the defendant's side of the true boundary. The defendant's excavation came very close to that fence. The maximum depth of the excavation from natural ground level is 2.3 metres at the end nearest the avenue, which end is about 2 metres, or a little more, uphill or northwest of the drain. At that point the top of the cut of the excavation is about 600mm northeast of the concrete kerb which runs down the side of the driveway. The excavation tapers in depth as it proceeds further down the block, close to the fence. The length of the excavation was not established by the evidence but is probably 6 to 8 metres. The bottom end of the excavation, according to the plaintiff's evidence, is at a point 6 metres up hill from the back or south eastern side of his house. I suspect that this is an over estimation, but the evidence satisfies me that the excavation ends at a point well above the line of the rear of the plaintiff's house. The top of the cut of the excavation is within 450mm of the fence (that is 550mm from the true boundary between the properties). The face of the excavation is shaped steeply downward at an angle of about 70 to 80 degrees to the vertical.
The north eastern wall of the plaintiff's house is 2.4 metres from the boundary, 2.5 metres from the fence and 2.95 metres from the edge of the excavation. The landing is 900mm wide and therefore its north eastern edge is about 2.05 metres from the edge of the excavation. The path running down the north eastern side of the house is, I estimate from photographs, about 600mm in width and it is about 300mm from the side of the outside wall of the landing, with the north eastern side of the path being about 1.15 metres from the edge of the excavation.
In 1984 the plaintiff noticed that both the fences on the north eastern and south western sides of his property had slight leans to the north east. No doubt he attributed that to the general slope of his land in the direction of the lean. He noticed no other movement in the fence between his property and that of the defendant, or any movement in any other part of his property until about December 1986, which was about four months after the excavation had been carried out. What he then noticed was that the fence had increased its lean, which was of course towards the excavation. He also said that pebbles on his side of the fence were slipping into the excavation but that was not further explained nor do I fully understand it taking into account that if the bottom of the fence touched the ground it should have stopped any pebbles from moving further. It should also be understood that the excavation was about 550mm from the true boundary and the fence was on the defendant's side of the boundary, and from where the pebbles moved was not stated.
In February 1987 the plaintiff noticed that cracks were appearing in the bottom of the bitumen driveway near its north eastern boundary. This caused him to look further. He discovered that the drain across the bottom of the driveway had cracked at the position of the PVC drainpipe and the north eastern end of the drain from that point had commenced to subside and move away from the rest of the drain. He also found that the landing had moved away from the house and the balustrade around it had tilted away from the house. At some later time he realised that the step and path down the north eastern side of the house had moved down the block and that the path along the rear of the house had moved away from the south eastern corner of the house.
I accept the evidence of the defendant that on an occasion in about July 1986, prior to the excavation, he visited the plaintiff's house and noticed that there was a crack, but no significant separation of the concrete, in the drain at about the place where the PVC pipe is situated.
Concerned about the observed movement, the plaintiff consulted Mr Casimaty in March 1987. Mr Casimaty has investigated the problem and visited the property on a number of occasions since. On 29 April 1987 he conferred with the plaintiff and the defendant. His observations have established that the movement has continued up to the date of the trial.
In March 1987 the defendant commenced to construct a terrace block wall up the face of the excavation. He stopped work but completed the wall in March 1988. In the meantime, he consulted an engineer, Mr Gandy, in October 1987, and received advice that to prevent the wall moving (there was no evidence that it was doing so) he should pin its bottom blocks with steel pins set in a rock base. He adopted the advice he received. The terrace block wall, since March 1988, has effectively covered the entire face of the excavation.
THE DRIVEWAY
The cracks in the bitumen driveway have increased in size and number since first being observed until the date of the trial. To remove the cracks about 12 to 14 square metres of the driveway needs to be replaced. The driveway is about 5 metres wide and the cracks extend almost from the street to the northern corner of the house for a width of about 1 to 1½ metres on the north eastern side of the driveway. The cracks run roughly across the contour of the slope and give the impression that the north eastern side of the driveway is slipping downhill and towards the defendant's excavation, both of which are in the same direction. The defendant's engineer, Mr Gandy, said that the movement in that direction is because of the natural slope of the land, whereas the plaintiff's engineer, Mr Casimaty, said that the movement has been caused by the excavation itself.
THE DRAIN
The drain has fractured at the site of the PVC drainpipe installed within it and the length of the drain from that point to its north eastern end at about the boundary of the two properties has moved in three directions as measured by Mr Casimaty. That is to say lengthwise north easterly towards the defendant's property, vertically down and sideways in a south easterly direction towards the rear of the plaintiff's property. The movement has increased from April 1987 to April 1989. Assuming that the balance of the drain has not moved (it may possibly have done so slightly) the measurements indicate that the total movement to April 1989 was 33mm north east, 33mm vertically down and 25mm south east. The evidence, particularly of Mr Gandy, satisfies me that the cause of the fracture and movement has been the tendency of the drive to move towards its bottom (eastern) corner putting pressure on the drain until it fractured at is weakest point, which is the position of the PVC drainpipe.
THE SIDE PATH
The evidence establishes that the north eastern side path and the step at its top, have moved down the hill in a south easterly direction. The evidence does not establish that there has been any movement of the path in a north easterly direction towards the excavation. The bottom of the path is substantially downhill from the lowest end of the excavation. As a result of its movement it has pushed the path running along the side of the rear of the house away from the rear wall of the house. Photographs show that the step at the top of the path has moved away from the drain immediately above it, thereby establishing that the path has moved down the block at a faster rate than the drain. For this reason I do not accept the evidence of the plaintiff when he claimed that the drain had put pressure on the path and was pushing it down the slope. I am satisfied that the path has moved independently of the drain.
THE LANDING
The length of the landing along the north eastern side of the house, from the northern corner, is about 2.25 metres and it is 900mm wide. It consists of a concrete slab which has been poured so that it extends into a doorway in the side of the house, thereby keying it to the house at that point. The landing is supported by a brick wall along its north eastern and south eastern sides. The state of the foundations of the wall is not known, but they are not on rock, otherwise the movement would not have occurred to the extent it has. The landing simply rests on top of the brick wall and is not fixed to it. On top of the landing is a concrete balustrade around the north eastern and south eastern edges. Movement of all parts of the structure has continued since February 1987. The top of the balustrade has moved to about 57mm from the house at the eastern end of the landing. The landing itself has moved away from the house by 21mm at the north western end and 6mm at the south eastern end. This smaller movement at the south eastern end can be attributed to the fact that the landing is keyed into the doorway. The top of the supporting brick wall has moved away from the house to about 65mm and at the ground level to about 22mm, indicating that the wall is tilting at the top. The wall has also dropped vertically down, but the distance of that movement cannot be measured relative to the landing slab because it has moved down with the wall. It is possible that the foundation of the wall where it butts against the house is resting on the edge of the solid foundation of the house, but that is a matter of speculation.
THE PALING FENCE
The fence is 100mm on the defendant's side of the boundary. It is only about 450mm from the top of the excavation. Since the making of the excavation the fence has leant further towards it and was described by Mr Casimaty as dangerous. Given its proximity to the excavation, the movement is not surprising. Further it has not been supported by a fence post at its highest point for possibly two years, and that no doubt has allowed the fence to lean further. Another section of the fence near the rear of the properties, is leaning in the same direction but the excavation could not in any way have been the cause of that.
THE STEEL POST
In April 1987 the defendant placed a steel post on the true boundary just below the drain. He dug a hole about 650mm deep to a rock base, the hole being about 300mm square. He placed the post in the hole and filled it with concrete. I accept Mr Casimaty's evidence that it is leaning at the top by about 50mm north easterly towards the excavation. However, the effect of that evidence is lost because Mr Casimaty did not ascertain whether or not the post was also leaning to the south east. It is possible that the post is simply leaning directly in line with the natural slope of the land and not just towards the excavation.
THE GROUND
Three test holes were dug in the defendant's property in March 1986. They revealed a heavy black top soil for a depth of 250 to 300mm, then heavy dark brown clay to a depth of between 550 and 650mm from the surface, then a layer of decomposed rock and finally solid rock commencing at depths varying between 600 and 950mm below the surface. The face of the excavation at its steepest point, which I estimate to be 2 metres, or a little more, uphill from the drain towards the avenue, was measured by Mr Casimaty as having a height of 2.3 metres of which the top 900mm was top soil and clay and the bottom 1.4 metres was decomposed and fractured rock.
Mr Gandy used an auger to dig a test hole, on the boundary 500mm downhill (south east) from the steel post. He found 650mm of top soil and clay, and then rock which sounded solid. The top 150mm contained what he variously described as "top soil with rubble, or bits of stone and that sort of material in it", "I was not able to identify whether that was builder's rubble or builder's rubble mixed up with natural soil, but there was some sort of material in it at the surface", "there were chips of bricks and stone and things" and "top soil, chips of rock". In cross–examination he said that he did not think there would have been fill because the lie of the land appeared natural. But he was not looking for fill and was concentrating on finding the depth of the rock. His finding that the rock was 650mm down is important, because the test hole was directly opposite and 1.5 metres away from the north eastern edge of the landing. Mr Gandy did not see the face of the excavation before it was covered by the terrace block wall erected by the defendant.
The defendant gave no evidence of encountering fill when he dug the 650mm hole for the steel post on the boundary. However he did say that the face of the excavation revealed a vein, 2mm thick, extending through the cutting for about 7 metres at a constant depth of 300mm below the surface of the ground, which he said consisted of building sand, small particles of decomposed grass and mortar droppings. Below the vein was clay and above it a dark clay and top soil mixture. The evidence does not satisfy me that there was in fact any significant depth of filling above the natural ground level in the area of the excavation and between the north eastern side of the landing and the excavation. The vein described by the defendant was very thin, only 2mm, and his description of what was above it was not consistent with there being materials which were not naturally there. It may well be however that there exists quite an amount of filling underneath the eastern corner, or thereabouts, of the driveway. In a photograph this fact is certainly visible at the extreme eastern corner where some of the fill has fallen out, but no investigations were carried out to establish what fill was under the driveway at any other point.
The foundation report for the defendant's property prepared in March 1986 stated that the property was a steeply sloping, grassed block with severe cracking in the surface, the cracks having an average width of 50mm and a depth of 200mm.
I conclude that for relevant purposes the ground consists of black top soil and clay to a depth of about 650mm in the vicinity of the eastern corner of the driveway and of the landing, and to a depth of about 900mm at the highest point of the excavation about 2 metres uphill from that corner. I accept the evidence of Mr Gandy that the top soil is heavy and black containing clay which is highly expansive when made wet. The lighter coloured clay below is also highly expansive although not as much as the clay in the top material.
THE OPINION OF MR CASIMATY
Mr Casimaty has practised as a consulting engineer for about 25 years. His opinion is that the movement of the various items was caused by the excavation. He said that the movement is a lateral one, due to the swelling and shrinkage of the clay which is common to the Sandy Bay area and which is noted for its expansive nature. He said that "you can't take away 2 metres of lateral support within a distance of less than 2 metres of what's happening and expect no movement to occur". Both Mr Gandy and Mr Casimaty agree that the origin of the movement can be found in the movement of the clay in the course of its expansion and contraction. There was no suggestion from either of them that the rock, decomposed or otherwise, under the clay, has been in any way involved in the movement processes. For this reason it seems to me that Mr Casimaty's comment that "you can't take away 2 metres of lateral support within a distance of less than 2 metres and expect no movement to occur" is not a sound basis for his opinion as to the cause of the movement of the landing. In so far as the excavation exceeded the depth of the clay (which was 650mm in the vicinity of the landing), and passed into rock, that excess is not relevant.
It was explained by Mr Casimaty that Sandy Bay clays contract in summer to the extent of there being 2 inch wide cracks, which close in winter. He said:
"If you take away the lateral support suddenly, very close, each time the clay expands the outside bit will stay there and when it contracts that bit won't come back because there's nothing to push it back".
When he said this I had difficulty accepting it, for it seemed to me that in the swelling and contracting process, clay contracts because it dries, not because it is pushed. I asked Mr Casimaty this and he seemed to agree and accept that in the swelling process the clay would not be prevented from moving towards the excavation, but nothing would prevent it from contracting. In fact the evidence satisfied me that at the edge of the excavation itself there would be a likelihood of greater cracking and contraction than anywhere else, because the clay would dry out more at that point.
Mr Casimaty suggested two analogies as appropriate to explain his opinion. One involved a flat surface, such as a pad of paper being held at an incline and shaken with an object lying on it, the object eventually sliding off. He equated the object to the landing, for example. I do not see that as an appropriate analogy at all. His theory is that the landing and other items have been carried by the moving clay, and not that they have slid down towards the excavation on top of the expanding and extracting surface. This comment is particularly pertinent to the landing itself which has its foundations at the bottom of the brick wall, somewhere underground. If those foundations are moving, or if the brick walls are moving, I consider that it is not due to any sliding of the foundations on top of a surface such as clay. The other analogy was that of a person standing in a box of sand, a side of the box being removed and the sand falling out because of the loss of lateral support. That gives rise to two questions. The first is whether the movement would have occurred notwithstanding the weight of the man, for the law only permits damages for loss of the natural support of the land as opposed to the structures on it. The second is at what point back from the side of the box, assuming that it is an extremely large box, would the sand remain stationary.
The opinion of Mr Casimaty was that because of the expansive forces of clay it will keep shifting towards the void and eventually fall into it. If the forces moved the clay beyond the point of the excavation, he would expect subsidence at say, the landing location. The problem I have in accepting this is that no evidence has been produced to satisfy me that clay has in fact moved or is in the course of moving into the void. The terrace block wall has not moved to any noticeable extent. Further, so far as the landing is concerned I have difficulty accepting that between the time of the excavation in August 1986 and when the movement in the landing was discovered in February 1987, the expansion and contraction of clay would have occurred to such an extent that the clay at the landing would have moved vertically down and also sideways.
I am also uncomfortable with the view of Mr Casimaty that "the whole body of clay" is moving towards the excavation and slightly downhill. No investigation of the clay itself has taken place which has demonstrated this. Mr Casimaty accepted that the fact that the fence was already leaning in 1984, two years prior to the excavation, would indicate some movement in the clay had occurred by then.
In relation to the landing, he thought that the initial movement was for the brickwork to drop vertically and then to tilt outwards. He agreed that if any structure on the plaintiff's land was outside an angle of 45 degrees from the top of the rock face of the excavation, the structure would not be exerting any lateral force on the defendant's land. Taking into account that the weight of the landing is on the footings of its supporting brick walls it is therefore clear that the weight of the landing itself would not have been exerting any lateral force on the defendant's land. Mr Gandy gave evidence that the landing, underneath its slab, is full of rubble. Accepting this, I do not consider its weight would have been imposing any lateral forces on the defendant's land either, because of the distance of that rubble from the face of the excavation. The height of the clay on the face of the excavation, adjacent to the landing, is only 650mm deep and the nearest point of the landing is about 2 metres away. But Mr Casimaty commented that shrinkage is "a different ball game".
THE OPINION OF MR GANDY
Mr Gandy's qualifications to express an opinion were impressive. He has practised as a consultant engineer for about 19 years. His firm has been commissioned by A.V. Jennings on a routine basis for some years to investigate the ground conditions of home sites and to report on the appropriate foundations for them. Every two to four weeks his firm is engaged by home owners to investigate the cracking of houses. His firm has carried out soil investigations for "dozens" of homes in the vicinity of Fisher Avenue over the last six years. He has been called in to report on cracking and movement of retaining walls, houses, brickwork and other structures, in the Fisher Avenue area on four to six occasions over the years.
He explained the highly expansive nature of Sandy Bay clay. Samples removed and dried commonly revealed a shrinkage of 20%. If the clay becomes wet enough it "becomes so soft you can stick your finger in it".
Except at the very eastern corner of the driveway where fill can be seen under it, there was no evidence revealing to me what is under the bitumen of the driveway, particularly where the cracks have appeared. Mr Gandy thought there would be a sub–base of brown gravel type material under the asphalt. But I in fact heard no evidence of such a state of affairs and I am left without knowing whether the materials under the asphalt were appropriate and properly compacted.
Mr Gandy said that it is very common for driveways on that type of soil, in that particular area, to "creep" downhill. He distinguished between "creep" and "slip". He explained that he went for a walk up and down the street and he believed that every driveway he saw had evidence of cracking of some kind.
The opinion expressed by Mr Gandy was that the cause of the movement of the driveway can be found in frequent swelling and contracting of the clay, with the formation of cracks, combined with the pull of gravity on a steep slope, thereby causing a very small tendency to creep downhill. He said that the extent to which this would occur would depend on the amount of moisture in the clay getting into it under the driveway, and the extent to which the clay dried. He said the growth of shrubs and trees along the north eastern edge of the driveway would tend to suck out moisture and dry up the soil near them. Having explained how creep can occur with frequent swelling and contracting of the clay because of fluctuating water content, Mr Gandy then gave evidence which conflicted very much with the effect of his earlier evidence. He explained that the surface of the driveway itself would protect the clay from obtaining more water, as would the sealed surface of Fisher Avenue and its drains at the top of the driveway, and those matters would tend to maintain the clay in a stable state. He also explained that the driveway was cut into the bank at the top, probably virtually to rock level, thus cutting off ingress of water underneath the driveway at that point. He repeated however that the bottom edge of the driveway would be susceptible to drying, particularly as the garden grew next to it.
Mr Gandy also said that there could be a tendency for the driveway to slip a little on top of the clay surface if it became wet, but he did not explain how that wetting may have occurred. In cross–examination he said that the most likely cause of the cracking was that the kerb around the north eastern edge of the driveway, and everything associated with it, slipped slightly on top of the clay bed taking the sub–base and the clay with it. The movement would most likely have been caused by the maturing of the garden and the roots of the plants getting underneath the driveway causing shrinkage of the clay through removal of moisture. He said another cause would be that "it just crept downhill because it slipped on the clay surface".
I have difficulty understanding what, in Mr Gandy's opinion, was the cause of the movement of the driveway. Having explained how "creep" can occur with frequent swelling and contracting of the clay, his evidence then suggested that there is unlikely to have been any substantial, and certainly not frequent, swelling and contraction. He thought there could be a slip of the driveway on top of the clay surface if it became wet but did not explain how that wetting would have occurred. He thought vegetation at the edge of the driveway was an important factor but the problem with that is that there was no oral evidence of the extent of that vegetation. Photographs do not reveal to me substantial growth, certainly not to the extent that I could come to any conclusion in favour of Mr Gandy's view. A photograph taken in August 1986 indicates, near the north east corner of the driveway a plum tree, not fully developed. Little else is shown in the photograph apart from geraniums.
I accept Mr Gandy's opinion that the drain fractured at the site of the PVC drainpipe because of the force of the driveway moving downhill. He then explained that water would have spilled from the drain onto the ground, missing the pipe, and then down to the path and the landing. With extra water flowing down to that area at times of rain, there would have been far more expansion of the clay. Because of the weight of the walls under the landing and the weight of the fill inside them, he expected that the clay under the landing would have been restrained from moving upwards and would have pushed out sideways and then up once it was outside the porch. There would therefore have been a heave in the area of the path. With drying the ground would have contracted and the landing would have dropped and also moved downhill.
Concerning the side path, Mr Gandy contributed its downhill movement to the fact that it is a characteristic of paths built on black soil on slopes that such movement occurs.
Mr Gandy disagreed with the opinion of Mr Casimaty, saying that it was based on a movement occurring when the clay was wet, whereas he considered movement would occur on drying out. He also said that the direct effect of lack of lateral support is only effective for a distance equal to about the depth of the clay at the cut of the excavation. Therefore the excavation could not have been the cause of the movement of the landing.
Monthly rainfall figures were referred to by Mr Gandy but I am unable to come to any conclusion from them. They do not appear to reveal substantially wet or dry periods or abnormally heavy or light rainfall.
CONCLUSION AS TO LIABILITY
I am not satisfied on the balance of probabilities, that the cause of the movement of the plaintiff's driveway, drain, landing and its supporting wall was the defendant's excavation, for the following reasons:
1There was no direct evidence that the natural ground has in fact moved towards or into the excavated area. The evidence of movement was confined to the structures and improvements on that ground. There was no evidence that the terrace block wall against the face of the excavation has moved under the pressure of ground movement.
2I accept that prior to the making of the excavation there was already a crack in the drain which indicates that movement had commenced in the driveway prior to the making of the excavation.
3The section of fence adjacent to the excavation was on a lean prior to the making of the excavation. Another section of the fence, further down the hill, is on a lean for reasons which can have nothing to do with the excavation. The section adjacent to the excavation has leant further since the excavation was made because of lack of a supporting post at the top. In addition the fence is closer to the top of the excavation than any other improvement and movement at that point might have been caused by the excavation, but the fence is not the subject of a claim.
4The side path has moved down the plaintiff's block in a south easterly direction. There was no evidence that it has moved towards the excavation. It has moved at a greater pace than the fractured drain above it and has therefore not been pushed by that drain or the driveway above. Further, it has moved to such an extent downhill that it has pushed, away from the house, the path running along the rear which is quite a distance downhill from the excavation. The strong impression I have is that the path's movement is unassociated with the making of the excavation.
5I am unable to find precisely why the driveway has moved. Obviously the steepness of the slope is a cause. The plaintiff is not entitled to have the driveway or any other improvements supported by the defendant's land. Only the natural land underneath is entitled to such support. As I said, there is no direct evidence that the natural land has moved. It appears to me that the nature of the material immediately beneath the bitumen surface would be relevant but little evidence was provided in that regard. Clearly some fill was placed under the driveway towards its eastern corner, but whether some material movement has occurred in fill I cannot decide. The evidence of Mr Casimaty does not satisfy me that expansion and acontraction of the clay under the driveway, and between it and the excavation, occurred to such an extent that within six months of the making of the excavation, and because of the excavation, the ground underneath moved to the extent indicated by the evidence.
6The landing has dropped vertically at its eastern corner. Because there is no evidence that the ground has itself dropped in the same direction it is difficult to say why. It may well be for the reason explained by Mr Gandy, that being that with the fracture of the drain at the position of the PVC pipe, water running off the driveway and otherwise getting into the drain was allowed to flow down to the area of the landing, thereby causing a subsidence. The leaning of the supporting wall of the landing, away from the house, may be associated with this wetting and consequent softening and expansion of the clay under the landing, and perhaps also with the weight of the rubble and the concrete of the landing pressing down on the damp clay inside the wall. At the excavation adjacent to the landing the depth of clay is only 650mm and I have difficulty believing that the excavation of the clay to that depth (ignoring as I do the further excavation into rock as being irrelevant) would have caused an expansion of the clay, as described by Mr Casimaty, to such an extent that the landing's wall and its footing, 2.05 metres away with the footing itself being somewhere underground, would have had time to move vertically down to the extent indicated by the evidence in the time available. On 26 March 1987 Mr Casimaty measured that downwards movement to be 23 mm relative to the slab.
7The lateral movements of the driveway, drain, landing, side path and fence are consistent with movements in the direction of the natural fall of the steep land.
8I gained the impression that Mr Casimaty quickly came to the conclusion that the excavation was the cause of movement, and he then looked for a theory to support that conclusion. This causes me to doubt the validity of his theory, although I do not doubt his honesty. I am influenced in this by the fact that he initially suggested that the cause of the movement was that the clay removed by the excavation was no longer available to force the remaining adjacent clay to contract, which seems to me to be obviously based on a false premise, and also by the fact that he only made a measurement of the lean of the steel post directly towards the excavation without looking for a lean in any other direction such as in a south easterly direction, which if it existed would have been consistent with the post leaning in the direction of the natural slope of the land. I gained a similar impression with regard to Mr Gandy and his conclusion and theory for the cause of the movement of the driveway, although I prefer his theory as to the cause of the movement of the other structures and improvements to that of Mr Casimaty.
I have anxiously considered the fact that the first observation made by the plaintiff of movements of substance occurred within six months of the making of the excavation. In the end that coincidence does not assist to persuade me, on the balance of probabilities that those movements were caused by the withdrawal by the defendant of the natural right to support of the land of the plaintiff.
DAMAGES
I accept the evidence of Mr Freeman, that the reasonable cost of repairing the driveway, the drain and the landing and its associated works would be $3,345.00. If I had found for the plaintiff I would have assessed his damages in that sum together with the sum of $644.00 which he paid to Mr Casimaty for initial investigation into the problem. In addition I would have been prepared to order a mandatory injunction in favour of the plaintiff requiring the defendant to strengthen the terrace block wall in the matter proposed by Mr Casimaty in his evidence.
However, for the reasons I have stated there will be judgment for the defendant.
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