Reported Decision : 121 LGERA 1 (2002) Aust Torts Reports 81-631 New South Wales Supreme Court CITATION : Bonnici & Anor v Ku-ring-gai Municipal Council [2001] NSWSC 1124 revised - 20/12/2001 CURRENT JURISDICTION: Common Law Division FILE NUMBER(S) : SC 13609/85 19 June 2001 21 June 2001 HEARING DATE(S) : 26 - 29 June 2001 2 - 5 July 2001 6 - 8 August 2001 10 August 2001 JUDGMENT DATE : 12 December 2001 Joseph Anthony Bonnici PARTIES : Sheryll Ann Bonnici Ku-ring-gai Municipal Council JUDGMENT OF : Sperling J at 1 COUNSEL : Mr P Tomasetti for the Plaintiffs Dr G Flick SC with Mr A Pickles for the Defendant SOLICITORS : Hunter Lawyers for the Plaintiffs Abbott Tout Solicitors for the Defendant CATCHWORDS : Private Nuisance - stormwater incursion from the street - elements of private nuisance - adopting a nuisance - meaning of "liberty to apply" - whether the court was functus officio by reason of earlier consent orders in the proceedings - whether unreasonable delay in exercising liberty to apply - whether there was a nuisance for which defendant was responsible - whether defence of statutory immunity - whether injunction should be granted - special damages - general damages - payment for use of land not the subject of an easement LEGISLATION CITED : Local Government Act 1993, s731, s733 Supreme Court Act, s94, Schedule J Abigroup v Abignano (1992) 112 ALR 497 Attrill v Richmond River Shire Council (1993) 30 NSWLR 122 Attrill v Richmond River Shire Council (1995) 38 NSWLR 545 Blair & Sumner v Deakin, Eden & Thwaites v Deakin (1887) 57 LT 522 Bonnington Castings Ltd v Wardlaw [1956] 2 WLR 707 Brodie v Singleton Shire Council (2001) 180 ALR 145 CASES CITED : Holbeck Hall Hotel Ltd v Scarborough Borough Council [2000] 2 All ER 705 Phillips v Walsh (1990) 20 NSWLR 206 Pride of Derby & Derbyshire Angling Association Ld v British Celanese Ld [1952] 1 All ER 1326 Roberts v Gippsland Agricultural and Earth Moving Contracting Co. Pty Ltd [1956] VLR 555 Sedleigh-Denfield v O'Callaghan [1940] AC 80 St George v Wallis [2001] NSWSC 23 Thorpe v Brumfitt (1873) 8 Ch. App. 650 DECISION : See paragraphs 232 - 235. IN THE SUPREME COURT OF NEW SOUTH WALES COMMON LAW DIVISION Sperling J Wednesday, 12 December 2001 13609/85 Bonnici & Anor v Ku-ring-gai Municipal Council JUDGMENT His Honour: Contents 1. Introduction [1] 2. Topography and roadworks [5] 3. Drainage lines affecting the plaintiffs' property as at 1984 [11] 4. History of drainage lines affecting the plaintiffs' property [16] 5. Natural watercourse on No. 48? [22] 6. Stormwater incursion 1977-1984 [28] 7. The proceedings 1984-1986 [36] 8. The 1987 works [47] 9. Stormwater incursion 1987-1998 [49] 10. Reactivation of the proceedings in 1998 [61] 11. The 1999 works [63] 12. Procedural history 1999 to date [74] 13. Stormwater incursion from 1999 [96] 14. Mr Lucas' evidence [105] 15. Mr Turner's evidence [112] 16. Evidence of other residents [124] 17. Mrs Bonnici not a witness [133] 18. Mr Pollock's evidence [139] 19. Tender of Patterson affidavit [145] 20. The true nature and extent of street water incursion onto the plaintiffs' property [151] 21. Natural watercourse revisited [160] 22. The defence of functus officio and available relief [163] 23. Nuisance and Negligence [182] 24. Law: nuisance [185] 25. Nuisance, subject to special defences [192] 26. Special defences [200] Statutory Immunity [202] Authorisation [211] Injunctive relief and cost of compliance [214] 27. The easement over No. 48 [219] 28. Special damages [227] 29. General damages [230] 30. Conclusion [232] 31. Annexure A 32. Annexure B Introduction 1 The plaintiffs are the owners and occupiers of No. 48 St Johns Avenue, Gordon. The defendant is the Local Government authority with responsibility in relation to roads in the area. 2 The plaintiffs are husband and wife. Mr Bonnici is an architect. In 1977 they acquired No. 48 St Johns Avenue, Gordon. It was then undeveloped land. Construction of a house, designed by Mr Bonnici, commenced in mid 1978 and was completed in June 1979. A rear deck was added in 1980 or 1981. A swimming pool was built in 1987. 3 St Johns Avenue runs roughly east-west. It lies to the west of the Pacific Highway adjoining the highway at right angles. The roadway slopes steeply downhill from the highway and then flattens out to some extent before reaching No. 48 and nearby properties. There is a slight bend in the roadway towards the north where the road passes No. 44, just uphill from No. 48. 4 The plaintiffs' land is on the southern side of St Johns Avenue. Topography and roadworks 5 Annexed to this judgment as Annexure A is a contour map of the area, onto which has been drawn the naturally occurring catchment area relative to No. 48. Features of the map to be noted are the knoll at the top of St Johns Avenue (where a church and graveyard are situated) and the natural depression running between the knoll and No. 48. The natural depression to which I have referred passes through the plaintiffs' land and on through other properties to the south-west. 6 The natural fall of the plaintiffs' land, as shown by contours recorded before any construction work was done on the plaintiff's land, is, from the street to a point about halfway along the block, broadly north to south. From about halfway along the block, the fall is broadly to the south-west. So the back half of the property – the back yard once the house was built – sloped away from the house towards the south-west corner of the property. Within those falls the natural depression on the plaintiffs' land is to the south-west. It is not in dispute that, at times of heavy rain, there would have been a flow of stormwater across the plaintiffs' land, in the natural state following the natural depression which passed through it. 7 Roadworks enlarged the natural catchment area above No. 48 by about 50 per cent. This is shown in a further contour map, Annexure B to this judgment. 8 As a result of the roadworks, much of the stormwater shed to the east by the knoll now flowed, via the Pacific Highway, into St Johns Avenue. Stormwater from the north western face of the knoll was taken up by St Johns Avenue directly or indirectly via Oberon Crescent (which discharged into St Johns Avenue). Stormwater from additional residential lots on the northern side of St Johns Avenue discharged stormwater into St Johns Avenue. The top half of St Johns Avenue was within the enlarged catchment area. Run off from the additional area of the catchment above No. 48 was thus largely concentrated in St Johns Avenue itself. 9 Substantially, stormwater flowing in St Johns Avenue after the roadways were installed would not have flowed naturally onto the plaintiffs' land. Axiomatically, any water which spilt from St Johns Avenue and then flowed, directly or indirectly, onto the plaintiffs' land was, substantially, in excess of what would have flowed naturally onto that land. 10 I do not believe that anything I have said in this section of the judgment is contentious. Drainage lines affecting the plaintiffs' property as at 1984 11 These proceedings were commenced in 1984. 12 As at 1977, when the plaintiffs purchased No. 48, there was no drainage of stormwater from the incline of St Johns Avenue between the Pacific Highway and No. 48, until one came to gutter traps a little uphill from the plaintiffs' property, on either side of the roadway opposite No. 42. These fed into a drainage line from the street which ran within No. 46 (the property to the east of the plaintiffs), along the boundary with No. 48. The line fed into a pit on No. 46 about half way along the common boundary with No. 48. I will refer to that line as the SDL (the street drainage line). 13 There was also, at that time, a drainage line crossing uphill properties, commencing in No. 42 and crossing No. 44 and No. 46, which fed into the pit at the boundary of No. 46 and No. 48. The line more or less followed the natural depression to which I have referred. I will refer to that line as the IADL (the interallotment drainage line). 14 The pit had an opening on its western side (that is, towards No. 48) to which was attached a short length of pipe, protruding into the plaintiffs' land. When the plaintiffs' purchased the property, the protruding pipe was covered by soil and / or vegetation. It was discovered by Mr Bonnici some time after the house was built. 15 Thus, the situation, when these proceedings were commenced in 1984, was that stormwater from uphill properties and from the street was concentrated at the junction pit on No. 46 near the boundary with No. 48. From there it could flow only onto the plaintiffs' property via the outlet pipe or from overtopping of the pit because of the outlet pipe being clogged. History of drainage lines affecting the plaintiffs' property 16 The history of drainage lines which existed when the plaintiffs' purchased No. 48 in 1977 appears from Appendix B to an internal Council memorandum dated 31 August 1983 (Exhibit F, tab 47) and from Mr Pollock's affidavit sworn in these proceedings on 5 June 1985. Mr Pollock is an engineer, previously employed by the defendant. 17 The defendant has made the following formal admissions: The defendant is the "roads authority" within the meaning of those words as they appear in the Roads Act 1993 in respect of St Johns Avenue and Oberon Crescent, Gordon Both St Johns Avenue and Oberon Crescent are roads the fee simple of which is vested in the defendant. 18 The drainage easement which now contains the SDL was granted to the defendant in 1917. It did not extend as far into No. 46 at that time. The road pavement, kerb and gutter in St Johns Avenue were made in about 1929. I infer that the SDL was installed in the easement, by or with the authority of the defendant, at about that time, if not earlier. At that stage, the easement and the SDL within it did not extend to the bottom of the depression. The SDL fed into an open channel which fed, in turn, into the natural depression on No. 46. 19 As at 1960 or thereabouts, the IADL was in place from No. 42, across No. 44 and into No. 46. It stopped short of the junction between the open channel from the SDL and the bottom of the depression. It carried stormwater into the depression from No. 42. That would have included stormwater arriving at No. 42 from higher land. 20 At that time, 1960 or thereabouts, the defendant installed the pit on No. 46 near the boundary with No. 48, and connected the IADL and the IADL to it. The easement on No. 46 was extended to accommodate the extra length of the SDL. Presumably, the pit was installed with the opening into No. 48 to which I have referred. Otherwise, there would have been no exit for water delivered to the pit. 21 This work improved the amenity of No. 46 by putting the drainage system underground at the confluence of the SDL and the IADL, but it was of no advantage to No. 48. Stormwater from the street and from uphill properties continued to be discharged onto No. 48. Natural watercourse on No. 48? 22 This question was the subject of a good deal of evidence and a good deal of argument. However, as the evidence came out, I regard the issue as largely semantic, probably unresolvable and ultimately unimportant. 23 As I have said, in the natural state, stormwater run off would have crossed the plaintiffs' land through the natural depression to which I have referred. 24 There was reference in the evidence to a low point in the depression on the plaintiffs' land and to undulations. Natural run off would have become concentrated in one or more pathways in that part of the depression. It appears that, at an earlier time, there was a well defined creek bed or channel within the natural depression on the plaintiffs' land. Such a water course may have been natural. On the other hand, it may have been made by a previous owner to concentrate and confine the run off from the higher land. It might have been in part natural and in part man-made in a variety of ways. 25 The evidence does not enable me to say which of these possibilities is the case. Words such as "natural watercourse", "creek" and "channel" convey the opinion of the speaker on the question, but do little to resolve it. Descriptions of such a watercourse as it appeared at one time or another do little to indicate whether, as so described, it came to be there naturally. That is because of the possibility of human involvement at an earlier time. A man-made channel, for example, might take on a natural look over time. 26 The present day appearance of the land is of little value in this regard either, because the extent to which that is the result of man-made changes to the natural topography is unknown and unknowable. For example, a temporary channel was dug across the land in 1986 and filled in again after the 1987 works had been carried out. 27 I will return to this topic. As will be seen later, the outcome of the proceedings does not depend on whether there was, at some stage, a natural watercourse on the plaintiffs' land, in the sense of a well defined, natural flow path. Stormwater incursion 1977-1984 28 The following is Mr Bonnici's account of water incursion in the period 1977 to 1984. 29 The construction of the house in 1979 was followed by a dry period. 30 During 1980, the backyard of the property was landscaped, preserving the broad contours of the land. The land was cleared or partially cleared at that time. In that year, following light rain, Mr Bonnici noticed what he described as a stream of water traversing the property in an east-west direction. Enquiries by Mr Bonnici revealed the existence of the stormwater easement on No. 46 running along the boundary with No. 48. A year or so later, he discovered the junction pit on No. 46 at the end of that easement, including the outlet pipe protruding into his property. The outlet pipe had been covered over. 31 In late 1982, following heavy rain, water poured from under the concrete lid of the junction pit on No. 46, flooding almost the entire backyard of No. 48. Flooding of that kind was observed on several occasions. 32 In 1983, during heavy rain, the water level extended to beneath the house and surrounded the foundation piers. The stormwater disposal drain on No. 48 became blocked by back pressure and fractured on one occasion. The hot water system failed. The backyard and the area beneath the house was reduced to a quagmire after the rain ceased. The depth of water adjacent to and under the house was said to be approximately 450 to 600 mm. 33 Up to December 1983, the property had been flooded more than 17 times, causing the hot water service to fail on more than one occasion, with water depth of up to 500 mm against the walls of the house. 34 Exhibit G is a bundle of 15 photographs taken before 1986. These include photographs showing very extensive flooding of the plaintiffs' back yard. The photographs are compelling. They show a large expanse of land under water, including the land adjacent to the house and extending over a substantial length of the boundary with No. 46. Photographs taken in the street show the extent of water in the gutter and on the footpath. Overtopping of laybacks from the street and water flowing on driveways is demonstrated in relation to No. 34, No. 40, No. 42, and No. 48. 35 Following several complaints by the plaintiffs to the defendant, these proceedings were commenced in August 1984. The proceedings 1984-1986 36 It is and continues to be the plaintiffs' case that their property has been repeatedly inundated by stormwater from St Johns Avenue, flowing directly from the street and indirectly through uphill neighbouring properties. 37 On 28 August 1984, these proceedings were commenced by statement of claim. An amended statement of claim was filed on 28 May 1985. The plaintiffs' claim was framed in nuisance and negligence. The plaintiffs claimed an injunction, an order for abatement works and damages. 38 There was a hearing before Smart J, commencing on 16 September 1985. This culminated in orders being made by consent on 20 September 1985. The orders were not expressed to be without admission of liability. They were in the following terms 1. The Defendant its servants and agents be restrained from permitting, allowing or causing the flow of water from St. Johns Avenue, Gordon and the footpath adjacent thereto onto the Plaintiff's land at No. 48 St. Johns Avenue, Gordon ("the land") so as to create a nuisance. 2. Suspend operation of Order 1 until the 30th June, 1987. 3. The Defendant terminate the flow of interallotment drainage onto the Plaintiff's land which is presently contained in a 300 mm pipe by the connection of a rebuilt pipe to the proposed mainline drainage system as shown on the plans annexed hereto and marked with the letter "A" by 28th February, 1987 and to execute such works in a manner and to a standard which will ensure that the works themselves and the interallotment drainage contained by those works do not in the future cause nuisance to the Plaintiff. 4. The Defendant shall pay the Plaintiffs general and special damages assessed and agreed in the sum of $17,500. 5. The Defendant shall pay the costs of proceedings No. 13609 of 1985 and No. 15340 of 1985 as agreed or taxed to date. 6. The parties have liberty to apply to the Court for further orders on 2 days notice to the other. 7. All orders made on 20th September, 1985 in the proceedings are vacated. 39 Agreement as to matters not immediately material was also recorded in the minutes of order. 40 The consent orders include no agreement, finding or determination that a nuisance in fact existed. The injunction in paragraph 1 was framed in terms which did not include that concession. However, the consent to an injunction in the agreed terms, the agreement to carry out abatement work, the agreement to pay damages and the agreement to pay the costs of the proceedings constituted an admission by conduct that a nuisance in fact existed. 41 The work specified involved work on private property. A property owner withheld consent. The defendant applied for a variation of the orders. There was a further hearing before Smart J, commencing on 18 October 1985. It proceeded intermittently. 42 On 27 December 1985, Smart J delivered a judgment, which included some provisional findings, but which made no final determination or order at that stage. Accordingly, the judgment gives rise to no res judicata or issue estoppel. His Honour did, however, record the following admission in the course of the judgment: The orders made on 20 September 1985 have not been passed and entered. The Council made it clear that it did not seek to vary order 1 which restrained it from allowing or causing the flow of water from St John's Avenue, including the footpath, onto 48 so as to create a nuisance. It accepted that there was a nuisance and that it had to cease. 43 The admission does not, of course, bind the defendant but the admission is further evidence that there was a nuisance for which the defendant was responsible. 44 The hearing resumed, again intermittently. The parties agreed to the suspension of the orders made on 20 September 1985 and consent orders were made to that effect from time to time pending the outcome of the proceedings. 45 On 11 November 1986, further orders were made by consent, including an order vacating the orders of 20 September 1985, an order in the same terms as the injunction in the earlier orders, an order for payment of damages in materially the same terms as before and an order that a new scheme of specified abatement work be carried out by the defendant. Again, the orders were not made without admission of liability, the defendant was to pay the plaintiffs' costs and, again, liberty to apply was reserved. There was no order that the proceedings be otherwise dismissed. The orders were entered on 6 February 1987. 46 The same implied admission of an existing nuisance was again made by the consent to these orders. The 1987 works 47 The specified work required by the orders made on 11 November 1986 is shown in Annexure A to the orders (Exhibit F, tab 58). A trap was to be installed in the footpath outside No. 46 and connected to the SDL. The 500 mm SDL was to be replaced with a new 600 mm line. The 300 mm IADL was to be relaid, and was to have grated inlet pits at the boundary of No. 42 and No. 44, and at the boundary of No. 44 and No. 46. The pit on No. 46, at the boundary of No. 46 and No. 48, was to be remade and sealed without the opening into No. 48. A new line was to be installed, from the pit to the rear of No. 46, across the rear of No. 48, and from there across other properties into an existing major drainage line. There was provision for an easement across the back of the plaintiffs' property to accommodate the part of the new line which was to pass through their property. 48 The work specified in the consent orders of 11 November 1986 was carried out by the defendant between February and June 1987. Stormwater incursion 1987-1998 49 This is the period between completion of the work done in 1987, pursuant to the orders of 11 November 1986, and the filing of a notice of motion in November 1998 with a view to reactivating the proceedings. 50 What follows is Mr Bonnici's account of water incursions during that period. 51 Work on the Bonnicis' swimming pool commenced in September 1987. In November 1987, Mr Bonnici saw street water flow across the layback to his property and from the footpath, then down his driveway. The water also flowed from the boundary with No. 46 across the walkway, within his property, at the front of the house. Mr Bonnici observed water flowing in a sheet onto No. 46 from the backyard of No. 44 and from there onto No. 48. Most of the water flowed towards the back of the house, intruded under the back deck and extended over the area where the pool was being built. A side of the pool excavation collapsed due to the flow of water coming from No. 46. 52 In severe storms, the flow on No. 46 was some 10-15 m wide. The pattern was that, even after the rain stopped, water continued to flow down the street for several days, and into No. 48 from the easement on No. 46. The ground on No. 48, particularly near the boundary with No. 46, remained water logged for days. 53 In January 1988, following heavy rain, Mr Bonnici saw surface water flowing across No. 46 onto the plaintiffs' property, although not as severe as previously. There were surface flows at the back of his house, under the deck and around the pool. 54 In April 1988, there was a large flow of water across No. 46 onto No. 48. In the same month there was further flooding. Over a period of about two weeks there were flows of stormwater onto No. 48 from No. 46. There was also water overtopping the layback of the driveway of No. 48, with flow down the driveway. 55 Exhibit J consists of three photographs taken in April 1988. One photograph shows the trap in the gutter outside No. 46, next to the layback for that property. The debris shows the path taken by water flowing from the gutter onto the driveway of No. 46. Another photograph shows a large expanse of water. The water is shown cascading from one level to another on No. 46, to a depth at the lip of the upper level assessed by Mr Bonnici as at least 50 mm, then pooling on No. 46 adjacent to the boundary to a depth assessed by Mr Bonnici as in the order of 150 to 200 mm. Mr Bonnici says, the water was flowing towards No. 48. The third photograph shows water on No. 48 between the boundary and the coping of the swimming pool, with barkchips (put down for landscaping) having been picked up and now floating on the water. 56 Photographs, Exhibit K, taken in late April or early May 1988, show the aftermath of flooding of the plaintiffs' property. The area of flooding was very extensive as shown by the way in which woodchip has been swept away and across the ground. Dirt and silt is depicted, scoured from the ground and moved against the fence line on the boundary of Nos. 48 and 50. The effect of water flowing around the front of the house and down the driveway of No. 48 is also depicted. The effect of flooding in the carport and adjacent to the front door is shown. 57 A further series of photographs, at tab 82 in Exhibit F, also show the aftermath of the April flooding. 58 Further episodes of flooding in January 1991 and April 1994 are mentioned in Mr Bonnici's evidence. Mr Bonnici said in evidence that he had not included every instance of such flooding. 59 Meanwhile, there was correspondence with the defendant concerning the situation and discussion with the defendant's staff. 60 The plaintiffs' notice of motion was filed on 5 November 1998. Reactivation of the proceedings in 1998 61 On 5 November 1998, the plaintiffs sought to reactivate the proceedings by filing a notice of motion, claiming further orders, including an order that the defendant comply with the orders of 11 November 1986 and orders that the defendant carry out further specified abatement work. 62 The notice of motion was returnable on 16 November 1998. It was stood over on the defendant's application to 8 February 1999, and was again adjourned on that date to 8 March 1999. The 1999 works 63 According to Mr Bonnici, the incursion of water continued. He mentioned a heavy flow of water entering the driveway of No. 48 from the footpath in January 1999, and water entering No. 46 from the footpath and then flowing onto No. 48 in April 1999. 64 On 22 February 1999, the defendant produced plans for further work to be carried out by it (Exhibit F, tab 123). The work is also described in the defendant's internal memorandum dated 19 March 1999 (Exhibit F, tab 126). None of the proposed work was on the plaintiff's land. 65 The work planned by the defendant commenced in May 1999. It was partly done and was discontinued soon after. Alterations were made to an existing pit over the IADL in No. 46 and an additional inlet pit to that line was installed on No. 46. Adjacent to the footpath outside No. 40, a new inlet pit was constructed with a connection that fed into the SDL. The work carried out in 1999 also included extension of the drainage system for collecting water from the gutter of St Johns Avenue. The extension was to a point further to the east, that is, further uphill from No. 48. The drainage system from the roadway continued to be fed into the SDL. 66 Work in the 1999 plans which was not implemented included some regrading on No. 44, a small kerb along the boundary of No. 46 with No. 48, adjustment to crossfalls on the footpath between No. 40 and No. 46, installation of bitumen strips to direct water flow into the dish drain adjacent to the footpath between No. 40 and No. 46, alterations to the kerb crossings at No. 38, reconstruction of the driveway on No. 46, and regrading at the front boundary of No. 46. Some of the unfinished work required the consent of the owners of No. 46, as to which the evidence was silent. 67 The circumstances giving rise to the 1999 planned works are unclear. Mr Turner said he was informed by his superior, Mr Tucker, of what had been requested by Mr Bonnici and agreed to by the defendant. Mr Bonnici said he pointed out to Mr Tucker on site what the problems were and that the only further contact, before the final drawings were produced and the work began, was a meeting at which Mr Tucker gave him some incomplete drawings. The only contribution to the design which Mr Bonnici would concede was a letter he wrote in January 1999 suggesting additional stormwater inlets on Nos. 42, 44 and 46. Mr Tucker was not called and his absence was not explained. 68 I find that the production of the 1999 drawings and the undertaking of those works was the defendant's response to the reactivation of the proceedings by the plaintiffs in November 1998, and that Mr Bonnici had minimal input into what the defendant decided, of its own accord, to do. 69 The defendant's proposal for the 1999 works and its part performance of those works is an admission that the work done in 1987 was inadequate to prevent the incursion of street stormwater onto the plaintiffs' land and that this constituted a continuing nuisance for which the defendant was responsible. The admission is, again, not conclusive. 70 The circumstances in which the 1999 works were discontinued is also unclear. The work remaining to be done was all on property other than the plaintiffs' property. Mr Turner's explanation is that council employees on the job were told by residents that, if the defendant continued with the work, Mr Bonnici would apply for an injunction to prevent it. Mr Turner did not suggest that Mr Bonnici had so informed the defendant. 71 Mr Bonnici's only contribution to this topic is his evidence that in September 1999 he moved the court for an order that the defendant construct a high retaining wall on the boundary between No. 46 and No. 48. On that occasion he told the court that the low kerb in the 1999 plans would be a waste of money. He said it was not his intention to stop the defendant from completing the 1999 planned works. 72 There is no persuasive evidence that anything said or done by Mr Bonnici frustrated completion of the 1999 planned works. 73 Conformably, counsel for the defendant told the court, in the course of the hearing before me, that, if it were found that there was a continuing nuisance (contrary to the defendant's denial and the defendant's objection to the plaintiffs' present claims being entertained), the defendant would complete the 1999 planned works. Procedural history 1999 to date 74 On 17 May 1999, Kirby J gave the plaintiffs leave to file "an amended summons or notice of motion" (although no previous summons had been filed). On 16 July 1999, the plaintiffs filed a summons in the same proceedings, asserting a continuing breach of the orders of 11 November 1986 and claiming orders which included declaratory orders, an order for further work (unspecified on this occasion) to be undertaken, and damages. 75 On 14 September 1999, Hulme J refused an application to amend the summons. However, on 15 November 1999, Kirby J gave the plaintiffs leave to file further evidence and also leave to amend the summons. On 29 February 2000, an amended summons was filed. The amended process does not appear to have been materially different in substance. 76 On 6 June 2001, the defendant filed a notice of motion claiming orders revoking the leave given by Kirby J to the plaintiffs on 15 November 1999 to adduce further evidence and, on 1 February 2000, to file an amended summons. By that notice of motion, the defendant also sought an order that the proceedings be dismissed on grounds which included a statutory defence pursuant to s733 of the Local Government Act, and an argument that the proceedings had been finalised by the orders of 11 November 1986, that the Court was functus officio, that any rights which the plaintiffs had were merged in those orders and that what is now sought by the plaintiff was not within the ambit of liberty to apply. The claim for revocation of the order giving leave to amend the summons was based on substantive arguments of a similar kind, and on the argument that the pleading included a new cause of action post-dating the commencement of the proceedings. This is a brief summary of the defendant's extensive argument, which was outlined in a document dated 18 June 2001 (MFI 2). 77 On 7 June 2001, the plaintiffs produced a draft further amended summons and draft points of claim. The defendant objected to these documents and they were not filed at that stage. 78 The draft further amended summons dated 7 June 2001 was in substantially shorter form than the earlier editions. It claimed orders including a declaration that there was a continuing nuisance, an order that the defendant cease to cause that nuisance, an order for specified new drainage work to be carried out in the street, a declaration that water flowing in and over the drainage line situated on uphill neighbouring properties was causing a nuisance, an order that the defendant cease to use that line and install a new line directing water on those properties to the rear of the properties, and an order for a retaining wall as specified to be built on the boundary of number 46 and 48. The document also included a claim for special and general damages. Relative to earlier editions of the summons, the new document, although very much briefer, included more in the way of specific claims than had previously been the case. 79 The draft points of claim of 7 June 2001 pleaded the initial alleged nuisance, the orders of 11 November 1986 and, the work done pursuant to those orders. It went on to assert the continuation of the nuisance and, further, that the work was carried out in breach of common law duty, in breach of statutory duty, negligently and such as to cause a nuisance. Particulars of damage allegedly caused in November 1987, January 1988 and April 1988 were included. 80 The proceedings came on for hearing before me on Tuesday 19 June 2001. There were adjournments. The hearing concluded on 13 August 2001. 81 Mr Tomasetti of counsel appeared for the plaintiffs and Dr Flick of senior counsel and Mr Pickles of counsel appeared for the defendant. 82 At the commencement of the hearing, Dr Flick applied to have the defendant's notice of motion heard in the first instance. That was deferred. Mr Tomasetti opened the plaintiffs' case. Following discussion, Mr Tomasetti was given the opportunity of redrafting the first plaintiff's principle affidavit in shorter form and of producing, for consideration, such further amended process as he was advised. That was without prejudice to the defendant's notice of motion. The Court did not sit on Wednesday 20 June to enable this to be done. 83 When the hearing resumed on Thursday 21 June, Mr Tomasetti produced for consideration a draft further amended summons dated 20 June 2001 and draft points of claim dated 20 June 2001. The new draft further amended summons, relative to the previous edition, involved both amplification and truncation. In truncation, no order was now sought for specific work to be done. In amplification, the claim for declaratory orders was more extensive. The claim for an order that the defendant cease to cause a nuisance, for a declaration that the drainage system on the uphill neighbouring properties was continuing to cause a nuisance and the claim for special and general damages remained. A further declaration was now sought that the defendant had failed to abate the alleged nuisance by the works carried out following the orders in November 1986 or by the works carried out in 1999, that such failure constituted a breach of the orders of 11 November 1986, and that the work proposed by the defendant in 1999 would be ineffective to abate the nuisance. 84 The draft points of claim dated 20 June 2001 were in materially identical form to those of 7 June 2001 except that an additional paragraph appeared (paragraph 13) asserting that the work proposed in 1999 would be ineffective to abate the nuisance. Particulars were included as to why that was allegedly so. 85 Mr Tomasetti sought leave to amend the summons and the points of claim as above. He also sought leave to read a new affidavit by the first plaintiff sworn on 20 June 2001 in place of lengthier affidavits previously filed. He also sought leave to read an affidavit by the plaintiffs' expert witness, Mr Lucas, sworn on 20 June 2001. 86 On behalf of the defendant, Dr Flick opposed these applications and, in the alternative, sought an adjournment of the hearing for not less than three weeks. On the application, the defendant read an affidavit sworn on 20 June 2001 by Ms L R Finn, the solicitor having carriage of the proceedings for the defendant. The affidavit particularised matters relied upon as differences between the documents now sought to be relied upon by the plaintiffs and those previously on file. It advanced argument opposing what was sought by the plaintiffs and reasons for requiring time to meet the changes in the plaintiffs' case if the court acceded to the plaintiffs' applications. The following documents were tendered by the defendant on the application: draft further amended summons dated 7 June 2001 (Exhibit 1), draft points of claim dated 7 June 2001 (Exhibit 2), draft further amended summons dated 20 June 2001 (Exhibit 3), draft points of claim dated 20 June 2001 (Exhibit 4), affidavit Mr E P J Lucas sworn 20 June 2001 (Exhibit 5), affidavit Mr E P J Lucas sworn 16 July 1999 (Exhibit 6), the affidavit sworn by the first plaintiff on 20 June 2001 (Exhibit 7). 87 The plaintiffs tendered, on the application, an affidavit sworn by the first plaintiff on 3 October 2000 (Exhibit A), an affidavit sworn by Mr J Turner on 6 March 2001 (Exhibit B), an affidavit sworn by Mr J Turner on 13 June 2001 (Exhibit C), an affidavit sworn by Mr J Turner on 9 September 1999 (Exhibit D), and a letter written by the defendant to another householder in St Johns Avenue dated 22 February 1999 (relied on as allegedly containing an admission of water inundation continuing to affect properties in the street) (Exhibit E). Mr Tomasetti also read an affidavit by the plaintiffs' solicitor, Mr A Pascale, sworn 21 June 2001, providing reasons against an adjournment which related to the first plaintiff's health. 88 Having heard argument I made the following orders on 21 June 2001: 1. Leave to the plaintiffs to amend the summons in the form of the further amended summons Exhibit 3. 2. Leave to the plaintiffs to amend the points of claim in the form of the points of claim Exhibit 4. 3. Orders 1 and 2 are subject to the defendant's notice of motion filed on 6 June 2001 and the matters raised in support thereof as appear from the defendant's outline of submissions dated 18 June 2001, a copy of which will be MFI 2 and placed with the papers. 4. The defendant's said notice of motion will be heard concurrently with the cause. 5. On the hearing of the cause the plaintiffs may read the affidavit sworn by the first plaintiff on 20 June 2001 and the affidavit sworn by Mr E P J Lucas sworn 20 June 2001, subject to all proper objections as to relevance or form. 6. The plaintiffs' claim for general and special damages will be determined at the hearing of the cause rather than being referred unless other order is subsequently made. 7. The defendant's application for an adjournment of the hearing of the cause for three weeks is refused. 8. I adjourn the hearing of these proceedings until 10 am on Tuesday next. I said I would give reasons for these orders in due course. The following are my reasons. 89 The affidavit sworn by Mr Lucas on 16 July 1999 related to an inspection of the property on 22 June 1999. The 1999 works had not then been commenced. However, Mr Lucas had the drawings for that work (see paragraph 5) and had been asked to review the prospective work and to comment on its prospective effectiveness (paragraph 6). The balance of the report is technical and was not easy to assimilate. It was not clear to me to what extent Mr Lucas was directing attention in the balance of the report to the likely effectiveness of the prospective work as distinct from the effectiveness of the work carried out to date. However, it was clear from his recommendations (paragraph 27 and following) that, in his opinion, the prospective work would be ineffective. That was so because the work which he recommended was more extensive and, in some respects, different from the 1999 scheme. 90 In his affidavit sworn on 9 September 1999, Mr Turner responded to Mr Lucas' affidavit of 16 July 1999. In a further affidavit of 6 March 2001, Mr Turner specified those items of the 1999 work which had been completed and those items which had not been carried out. He attributed cessation of that work to the plaintiffs threatening to obtain an injunction and stated a belief that the defendant had agreed to an injunction in relation to the balance of the work. That might not have been accurate. For present purposes, however, it was sufficient to note the defendant's case that the balance of the work was not carried out because of objection by the plaintiffs. That provided a basis upon which the defendant could argue that it should not be held to be in breach of the injunction by reason of any failure to carry out the balance of the work. 91 Mr Lucas' affidavit sworn on 20 June 2001 related substantially to the 1999 scheme, advancing reasons as to why that scheme does not, in Mr Lucas' opinion, provide a solution to what he perceives as the problems. 92 Reviewing the draft further amended summons of 20 June 2001, the draft points of claim of the same date, the affidavit of the first plaintiff sworn on that date and the affidavit of Mr Lucas sworn on that date, it seemed to me that the only additions of substance referable to earlier documentation related to the plaintiffs' assertion that the 1999 scheme of work, done and not done, was ineffective to abate the alleged continuing nuisance. That assertion was implicit, if it was not express, in Mr Lucas' affidavit of 16 July 1999. In the context of a claim, consistently made by the plaintiffs, that the alleged nuisance has continued, the defendant had been on notice, certainly since July 1999, that the 1999 works would not be effective to abate the alleged nuisance. Additionally, the defendant's understanding that the plaintiffs objected to the 1999 work being completed was further notice to the defendant of the plaintiffs' contention that the 1999 scheme of work would, if completed, be ineffective and might be counterproductive. True it is that Mr Lucas' reasons for that assertion were not spelled out in detail, or in full detail, before his affidavit of 20 June 2001. However, it seemed to me that, Mr Turner being fully conversant with the 1999 scheme, the defendant was in a position to deal with the detail in Mr Lucas' report of 20 June 2001 at short notice. Accordingly, I allowed the amendments that were sought, allowed the two affidavits in question to be read and refused the application for an adjournment for not less than three weeks. 93 I initially proposed an adjournment until 10 am Monday 25 June, which would have given the defendant the Friday and the weekend to prepare, but acceded to Dr Flick's suggestion that the hearing resume at 10 am on Tuesday 26 June. 94 My reasons for declining to hear the defendant's notice of motion prior to the hearing of the cause can be stated shortly. That application related closely to the case which the plaintiffs sought to make in the cause. Although that case was now specified with a good measure of precision in the summons, points of claim and affidavit evidence, the shape and content of the plaintiffs' case could be affected by the way the evidence came out (including evidence given in cross-examination) or by some further change of position by the plaintiffs to which the court might accede. It seemed to me that it would be unsafe to determine the defendant's notice of motion prior to the hearing of the cause in these circumstances, possibly to the detriment of the plaintiffs if the defendant were successful and possibly to the detriment of the defendant if the plaintiffs were successful. It also seemed to me that the defendant would not be irreparably prejudiced by deferring the determination of its notice of motion because the points raised under the notice of motion would be just as good at the end of a trial of the cause as they were beforehand. The effect of my ruling was really no more than to convert a preliminary objection to the plaintiffs' claim into points of defence. The amendments to the pleadings were allowed subject to the defendant's notice of motion. 95 As to damages, it seemed to me that the plaintiffs' claim in that regard was within a narrow compass and that it was, accordingly, in the interests of the parties to dispose of the whole of the proceedings, including the claim for damages, at the one hearing. Stormwater incursion from 1999 96 The following is Mr Bonnici's account of water incursion as from 1999. 97 Following the work carried out in 1999, Mr Bonnici made further observations. On 14 July 1999 there was heavy rain. Mr Bonnici saw that the gutters in St Johns Avenue between Oberon Crescent and No. 42 were carrying heavy flows of water. At the intersection of Oberon Crescent and St Johns Avenue, where the water from the two streets converges, there was white water. Similarly, at the cross over at No. 30, where water was jumping. Outside No. 34 there was flow across the footpath and onto that property. From the rear of No. 36, water was flowing across the driveway of No. 36A and into No. 38 and No. 36A, in two distinct streams. The larger stream was about a metre wide and 75mm deep and was flowing rapidly. Water was flowing at the rear of No. 46. The inlet to the drain on the footpath outside No. 46 was significantly blocked with leaves and silt over the grate. Water bypassed that drain and flowed onto No. 46, across the driveway at No. 46 and into No. 48. 98 On 29 August 1999, it was again raining. Mr Bonnici observed that the gutters were flowing full, especially on the south side of St Johns Avenue. Water overtopped the laybacks at No. 32, No. 34 and No. 36. The water flowed across the footpath, into No. 34 and towards the back of that house, across the driveway of No. 36A, from No. 36 and into No. 38. The water continued to flow down the footpath outside No. 42 and No. 44, and down the driveways of those properties. Water on the footpath flowed past No. 46, bypassing the pit adjacent to the footpath opposite No. 46, and flowing partly down the driveway of No. 46 and partly into the driveway of No. 48. Water flowed from the rear of No. 46 onto the plaintiffs' property. There was a heavy flow of water across the front of No. 48 to a depth of 50 mm, through which Mr Bonnici had to walk to enter the house. Water flowed through the carport on No. 48 to the back of the house between the rear deck and the swimming pool. 99 In June 2001, water from the gutter was again observed overtopping the laybacks of driveways uphill from No. 48. Again, the water flowed down the driveways and along the footpath into lower properties, including No. 48. 100 Speaking generally, Mr Bonnici said that, since 1987, he had observed, repeatedly, during rain, what he described as a "sea of water" flowing under the fence of No. 44 and covering No. 46. That, he said, happened quite regularly throughout the 1990's. He said that, on very many occasions, he saw water build up and then flow over the backyard of No. 48 in increasing volume. The earlier photographs illustrate such an event. 101 Also speaking generally, Mr Bonnici said that since 1987 water has continued to overtop the gutter and run onto the footpath uphill from No. 48. Large quantities of water have been observed running down the driveways into those properties and towards the rear of the properties. From there the water has flowed across the rear of No. 44 and No. 46 onto No. 48. 102 As at 20 June 2001 (the date of one of Mr Bonnici's affidavits), Mr Bonnici said he has observed, in recent times, that water continues to leave the street, flow down the footpath and onto No. 48 via various routes. The ground at the side and back of the house was damp virtually all the time, with significant flows of water episodically. 103 Under cross-examination, Mr Bonnici adhered to his evidence that he observed water from the street flowing down the driveways of Nos. 32 to 46, with water escaping from the gutter particularly at No. 32 and No. 34. 104 He said that, to his observations, the 1987 works had made no difference. The only improvement since the 1999 planned works were partially carried out was that there was less water incursion when flow levels were low. Impliedly, there was no improvement under heavy storm conditions. Mr Lucas' evidence 105 Mr Lucas is a consulting engineer with special expertise in urban flood mitigation and drainage investigation. He was retained by the plaintiffs as an expert and gave evidence at the hearing before me. 106 Mr Lucas' evidence related to the situation as from 22 June 1999 when he made his first inspection. That takes in the 1987 works and so much of the planned 1999 works as were carried out. 107 In reference to storm events generally, Mr Lucas used the technical phrase "average recurrence interval", abbreviated to "ARI". There is a 50 per cent chance that a storm event with an ARI of 2 or more will occur in any one year, 20 per cent for a storm event with an ARI of 5, and so on. 108 I will refer to a storm event with an ARI of 2 as a "1:2 storm", with an ARI of 5 as a "1:5 storm", and so on. I will refer to the capacity of a drainage system to accommodate stormwater flow associated with a 1:2 storm as "a capacity of 1:2", and so on. 109 An uncontentious feature of drainage lines mentioned by Mr Lucas is that the capacity of a pipe in a drainage line limits the capacity of an inlet to that line. Once the capacity of the pipe is reached, no more water can enter it. Thus, if a line has a capacity of 1:5, the excess storm water will not be accommodated and will flow on or pool on the ground, or both. 110 Mr Lucas said that he agreed with paragraphs 3 and 5 of Mr Patterson's affidavit sworn on 11 September 1985. For convenience it was agreed that these passages would be copied and tendered. That was apparently overlooked. I have had the extracts prepared and they are marked as the plaintiffs' Exhibit Z. I have included Annexures A and B to that affidavit in the exhibit. They were freely referred to in the proceedings and which are now (as mentioned earlier) annexed to this judgment. 111 Mr Lucas' evidence was, in summary and so far as is material, as follows: (a) The gutter on the southern side of St Johns Avenue has a capacity of 1:1. Stormwater from a storm greater than 1:1 would overtop the gutter and flow onto the footpath. (b) Some laybacks (for driveways) are lower than the kerb and the capacity of the gutter system to hold stormwater is less than 1:1 at those points. (c) A 1:1 storm would overtop the laybacks at Nos. 34 to 44, flow onto the footpath and down driveways, including No. 46. From there, water would flow overland onto No. 48. (d) The SDL has a capacity of 1:5. (e) The inlet pit adjacent to the footpath outside No. 46 has a capacity of 1:2. Stormwater in excess of that would flow down the driveways of No. 46 and No. 48. (f) The AIDL has a capacity of 1:5 but the inlet pits at the boundaries of Nos. 42 and 44 and Nos. 44 and 46 have a capacity of only 1:1. Accordingly, stormwater arriving on No. 44 and No. 46 in excess of 1:1 would flow overland to No. 48. (g) The 1:5 capacity of the SDL and the AIDL is mandated by the 1:5 capacity of the extended line as it passes across the rear of the plaintiffs' property. (h) Mr Lucas calculated the expected overland flow of stormwater at various points (which he called "nodes"), for storm events of various intensities. He also calculated the proportion of stormwater at those points which would naturally flow to that point and the proportion coming from the street. (i) A relevant node was the junction pit on No. 46 near the boundary of No. 48. Overland flow went from there onto the plaintiffs' land. Stormwater from the street would arrive at that node via the driveway of No. 46 and via properties further uphill. The proportion of water from the street arriving at that node, in association with a 1:1 storm, was 20 per cent, 1:2 44 per cent, 1:5 70 per cent and 1:20 81 per cent. Water from that node on No. 46 did not include stormwater entering No. 48 at the front of No. 48. Mr Lucas did not calculate the extent of that flow. (Such as it is, water incursion at the front of No. 48 would be wholly, or at least substantially, in excess of the natural run off. (j) The 1987 works did improve the situation, but were not effective to prevent stormwater from the street flowing onto the plaintiffs' land even in a 1:1 or 1:2 storm. (k) The part of 1999 planned works which have been carried out have further improved the situation, but only to a slight extent. Completion of those works would not address the basic problems with the existing system. (l) The preferred solution was to, dispense with the SDL and to extend the in-road drainage system uphill to about No. 34 and downhill to an existing pit at the corner of Vale Street, a total distance of about 200 m. There would be some discharge onto the roadway from the system at that point which could, however, be accommodated by road surfaces and ultimately taken up in a major drainage system further down. This would reduce the flow of water in the gutter of St Johns Avenue to the point where water would not escape from the street. The estimated cost was $200,000. (m) The only other alternative would be to build a 1.5 m wall at the south-western corner of No. 46 which would accumulate sufficient water to drive the extended line (across the rear of No. 48) beyond its existing capacity of 1:5 by the pressure of the head of water. This would require the consent of the owners of No. 46 or resumption. (Such an open pond did not seem to me to be a practical solution. It was not accepted as practicable by counsel for the defendant, who attacked the proposal). Mr Turner's evidence 112 Mr Turner, as an engineer employed by the defendant, designed the 1999 planned works. 113 He had no argument with Mr Lucas' assessment of the capacity of various elements in the existing drainage system, except for the gutter and laybacks. He said one had to allow for more than the height of the kerb because of the ground level behind the kerb. Mr Lucas' approach related, however, to water leaving the gutter via laybacks rather than via the kerb proper. 114 Mr Turner disputed the likelihood of water leaving the road at laybacks, particularly at the layback of No. 34 (which was emphasised by Mr Lucas). I resolve that issue in Mr Lucas' favour. I noted, on a view of the locality, that there is a pathway for water to leave the gutter across the nature strip adjacent to the layback of No. 34 which would allow water to escape from the gutter at a level below the height of the kerb. I resolve the question of the level of laybacks generally in favour of Mr Lucas, having seen the locality for myself and in view of Mr Bonnici's evidence, including his photographs. 115 Mr Turner agreed generally with Mr Lucas' assessment of flow lines for stormwater run off over the developed catchment area above No. 48. His calculations were much less comprehensive than Mr Lucas'. His assessment of the total volume of water arriving overland at the junction pit on No. 46 was somewhat less than Mr Lucas' but still substantial. 116 Mr Turner had made no calculations himself concerning the relationship between the pre- and post-development flow of stormwater onto the plaintiffs' land. He presented, as an annexure to his affidavit of 25 June 2001, a table prepared by a Mr Patterson which had appeared as an annexure to Mr Patterson's affidavit, sworn in those proceedings on 11 September 1985. That affidavit was not read at the hearing before me. 117 The Patterson table was to the effect that there was little, if any, additional flow of stormwater onto the plaintiffs' land following the roadworks. There were two criticisms of the table by Mr Lucas. First, the method used to estimate post-development flows was different from the methods used to calculate pre-development flows. Secondly, Mr Lucas said that the factor adopted by Mr Patterson for absorption pre development did not make sufficient allowance for absorption of stormwater by the ground in the undeveloped state. These criticisms were cogent, and I accept them. 118 In consequence, I do not accept the Patterson table as reliable evidence of the relative pre and post development flow of stormwater onto the plaintiffs' property. 119 Mr Turner did not suggest that the planned 1999 works have made or would, if completed, make any material difference to the present situation. He agreed that they would not increase the capacity of the drainage lines now in place. He made no attempt to justify the planned 1999 works. He said he designed them according to what he was told Mr Bonnici had requested. He said, for example, that there was no engineering reason for the kerb on No. 46 at the boundary with No. 48 boundary, which was one of the items in the 1999 plan not carried out. 120 Mr Turner estimated that the extended in-road drainage system recommended by Mr Lucas would cost $600,000 rather than the $200,000 estimated by Mr Lucas. The main reason for the difference appears to be Mr Turner's opinion that placing the pipe behind the kerb would be impracticable because of trees planted in the nature strip. Mr Lucas said that hand digging around the roots would avoid that problem. That seemed reasonable to me. 121 Mr Turner said the Mr Lucas' scheme would have to be extended much further downhill to avoid street water from St Johns Avenue being discharged into the drainage system for a different catchment area. The cost of the work would then be $1.6 to $2.3 million. I thought the reasons for having to avoid a different catchment area were unpersuasive. 122 It is relevant that, in 1985 or 1986, the defendant's staff gave consideration to the concept of extending the in-road drainage system. The cost estimate then was $74,000. That was 15 years ago, but the estimate is more consistent with Mr Lucas' current estimate of cost than Mr Turner's. 123 I prefer Mr Lucas' estimate of the likely cost of an in-road solution. Evidence of other residents 124 Mr F K Curtin said in his affidavit that he has resided at No. 44 St Johns Avenue since 1998. He said he had never seen water overtop gutters and flow over the footpath or down the driveway of No. 44, before 1999 or since, even in periods of heavy rain. 125 I have no reason to doubt Mr Curtin's veracity. But most people stay in doors in bad weather. He might not have had the opportunity or the interest to make the relevant observations. 126 Mrs N Garwood has resided at No. 46 St Johns Avenue for about 30 years. She said in her affidavit that, before 1987, with long periods of heavy rain, water built up and ponded in the rear of her property. She also said that, with heavy rain, water came down the driveway of her property but caused no concern or damage. 127 This evidence was corroborative of the plaintiffs' case that stormwater leaves the street and flows down the driveway of No. 46. The fall of the land is then towards No. 48. 128 What Mrs Garwood meant by long periods of heavy rain is not known. Hours perhaps. At all events, a build up of stormwater at the rear of No. 46 was also corroborative of the plaintiffs' case. Again, the fall of the land was then towards No. 48. 129 According to Mrs Garwood, the 1987 works eradicated the ponding of stormwater at the rear of her property. It was in 1987 that the old junction pit which discharged onto No. 48 was replaced by a new pit a little further to the south and an extension line was added leading from the pit to the rear of No. 46 and then across the rear of No. 48. It may be that some alteration to the levels on No. 46, associated with that work, eradicated what Mrs Garwood referred to as ponding. But that is not the point. There is nothing in her evidence to suggest that, after 1987, the volume of water flowing onto No. 48 via No. 46 was any less. Whether or not it continued to pond on No. 46 after 1987 is immaterial. Mr Bonnici's photographs also preclude any inference from Mrs Garwood's evidence that, following the 1987 works, significant incursion of stormwater from No. 46 onto No. 48 ceased. 130 Unfortunately, Mrs Garwood was not available for cross-examination due to the illness of her husband and her evidence was not tested. 131 I do not regard the evidence of either of these witnesses as militating, in any significant way, against the account of events given by Mr Bonnici. 132 Nor do I attach significance to the absence of other residents, as witnesses, to corroborate Mr Bonnici's account. People do not want to get involved, particularly in confrontation with a government authority, and a person in Mr Bonnici's position does not want to involve neighbours unnecessarily in his own problems. Mrs Bonnici not a witness 133 Mrs Bonnici did not give evidence. She is a relevant witness. She was available. Not giving evidence was obviously a conscious choice. 134 If I would have expected her to be called and there is no explanation for her absence, I would be entitled to infer that her evidence would not have assisted the plaintiffs' case. I would also be entitled to give greater weight to opposing evidence than I would otherwise do, and to any available adverse inferences from the evidence. 135 No explanation was offered for Mrs Bonnici's absence as a witness. I am not surprised however by the fact that Mrs Bonnici has not been called. This litigation has been a large exercise, with substantial investment in time and cost by Mr Bonnici. For a self-employed person such as him, time is money. Many a spouse would not be supportive of such a venture, and might be decidedly adverse to it. Why then be a plaintiff? If Mr Bonnici was going to press on anyway, why not? 136 This was not proferred as the explanation for Mrs Bonnici's absence as a witness, but it is a plausible explanation. And, if it were the true explanation, I would not expect to hear it spelled out, in denigration of Mr Bonnici and of his campaign against the defendant. 137 That is, however, only one possible explanation. Experience shows that, in family matters, there may be reasons for things being done and not being done which are quite different from an explanation which looks superficially obvious, and which one would then not expect to be recounted. 138 I give little weight to Mrs Bonnici's absence as a witness. Mr Pollock's evidence 139 This witness was called by the defendant. He was from December 1973 to February 1985 the Deputy Engineer of the defendant. Thereafter, he was, for a time, Director of Engineering and Parks. Mr Pollock retired from employment with the Council in about 1991. 140 In his affidavit sworn on 24 June 2001, he gave evidence of two visits to the plaintiffs' property, one on 7 December 1982 and the other on 12 November 1984. Substantially, the affidavit records conversations with Mr Bonnici. It leaves to inference the purpose of the visits but it is clear enough that they resulted from complaints by Mr Bonnici concerning the incursion of water onto his land. 141 I find it unnecessary to review the evidence concerning those visits. 142 Mr Pollock was referred in cross-examination to an affidavit sworn by him in these proceedings on 5 June 1985. Later, in the course of the hearing before me, Dr Flick submitted that Mr Tomasetti was obliged to tender that affidavit and that, if he failed in that application, he would tender the affidavit himself. Mr Tomasetti submitted that he was not obliged to tender the affidavit but that he would not object to the tender by Dr Flick. 143 In these circumstances, I will not take time to resolve whether Mr Tomasetti was obliged to tender the affidavit. The defendant wishes to have the affidavit in evidence and the plaintiffs do not object. I have marked the affidavit as defendant's Exhibit 25. 144 I have drawn on Mr Pollock's affidavit of 5 June 1985 for earlier parts of this judgment concerning the topography of the area and the history of the drainage lines affecting No. 48. Tender of Patterson affidavit 145 As I have mentioned, Mr K W Patterson swore an affidavit for the defendant in these proceedings on 11 September 1985. He was, it seems, retained by the defendant as an expert witness at that time. His affidavit was not read by the defendant in the hearing before me. 146 Paragraphs 3 and 5 of Mr Patterson's affidavit are in evidence before me, with Annexures A and B to that affidavit, being drawings of the pre- and post-development catchment areas above number No. 48. These were not in dispute at the hearing before me. 147 In his affidavit, Mr Patterson also presented, as annexure E, a table of pre- and post-development flow rates for stormwater run off arriving at No. 48 from the pre- and post-development catchment areas above that property. In the hearing before me, Mr Turner presented that table as an annexure to his affidavit of 25 June 2001, which was read. 148 The only cross-examination of Mr Turner concerning any matter in issue at the hearing before me, which involved reference to Mr Patterson's affidavit, was in relation to Mr Patterson's annexure E. Mr Turner said in cross-examination that he did not check the calculations in that table. He said he adopted the table without more because he thought it had been accepted by the Court at the earlier hearing. 149 There was nothing in Mr Turner's answers in cross-examination which makes it necessary, as a matter of fairness, for the whole or any part of Mr Patterson's affidavit to be tendered other than paragraphs 3 and 5 and Annexures A and B. 150 Mr Turner's affidavit was also mentioned in the cross-examination of Mr Pollock. However, the reference was cursory and does not warrant further consideration. The true nature and extent of street water incursion onto the plaintiffs' property 151 As to the extent and incidence of stormwater incursion onto the plaintiffs' property from No. 46, Mr Bonnici's evidence and Mr Lucas' evidence corroborate each other. What Mr Bonnici says happens Mr Lucas says is what is to be expected. I accept Mr Bonnici's evidence as to the extent and incidence of stormwater incursion from No. 46. 152 I have no reason to doubt Mr Bonnici's reliability as a witness. I did not have the impression that he was exaggerating his account of events. I was impressed by the photographs. I accept his evidence concerning the extent and incidence of stormwater incursion from No. 46, corroborated as it is by Mr Lucas' evidence. I also accept Mr Bonnici's evidence concerning the extent and incidence of stormwater incursion at the front of No. 48. Mr Lucas corroborates that evidence also, albeit in concept only (ie without qualification). 153 I find that the plaintiffs' property has, since 1982, been periodically inundated with stormwater from No. 46, via the natural depression to which I have referred. That stormwater has included a substantial quantity of stormwater from the street. 154 Water incursion from No. 46 has also been from the driveway of that property further to the north. Stormwater arriving via that route has been substantially if not totally from the street. 155 In addition, there has been inundation at the front of No. 48 from the footpath and from the layback of No. 48 itself. Incursion via that route has also been substantially if not totally from the street. 156 Stormwater from the street has been substantially additional to the natural run off of stormwater onto the plaintiffs' land. 157 I find, conformably, that the works carried out in 1987 and 1999 have not prevented the incursion of stormwater from the street onto the plaintiffs' property, which has continued with much the same incidence and to much the same extent as was occurring before 1987. 158 I do not think it is necessary or that it is useful for me to decide whether completion of the 1999 planned works would make a material difference. If the defendant is guilty of nuisance, it is for the defendant to devise and implement the means of abatement. My opinion as to whether a particular course would be effective or ineffective will not make that course effective or ineffective. But, since the question has been litigated, I will make the finding. 159 Mr Lucas says that completing the 1999 planned works would be of no material use because the present problem is related to the capacity of the existing drainage system and the 1999 planned works are not directed to that. That seems to me to be correct. Mr Turner does not advocate completion of these works. I find that completion of the 1999 planned works would not materially reduce the flow of stormwater from the street onto the plaintiffs' land. Natural watercourse revisited 160 I return, at this point, to the question of whether there was, at some earlier time, a well defined natural watercourse, on the plaintiffs' land. I have said it is impossible to resolve that question on the evidence. 161 The reason why the question is also irrelevant now becomes apparent. The stormwater incursion as described by Mr Bonnici (which I have accepted) has been such in extent and in relation to points of entry that it would not have been contained harmlessly within a natural watercourse of the kind postulated by the defendant, if such a natural watercourse - assuming it ever existed as such - had been retained. 162 Furthermore, if the defendant has been discharging onto the plaintiffs' land stormwater in excess of the natural run off, it would be no answer – even if factually correct – that the amenity of the plaintiffs' property would not have been affected had a natural watercourse been preserved. Actionable nuisance is not answered by failure on the part of an injured property owner to maintain the natural state of the land as a prophylaxis against such a civil wrong. The defence of functus officio and available relief 163 By its notice of motion the defendant sought summary dismissal of the plaintiffs' present process. The defendant submits, in effect, that the court will not entertain the plaintiffs' attempt to revive the proceedings. The argument is put in a number of ways, including that the orders of 11 November 1986 were a final determination of the proceedings, that the court is functus officio, that the plaintiffs' rights have merged into those orders, and that the plaintiffs' present claims are an abuse of process. 164 The defendant's objections are answered if the plaintiffs' present process is within the ambit of the liberty to apply reserved by the orders of 11 November 1986. 165 The usual effect and scope of liberty to apply is succinctly stated by McLelland J in Phillips v Walsh (1990) 20 NSWLR 206, 209: The question whether any particular application can properly be made in existing proceedings is a matter to be determined according to general law principles as modified by any relevant statutory provision. One such principle of the general law is that when proceedings have been disposed of by a final order which has been entered, the proceedings are at an end and cannot be revived: see generally Bailey v Marinoff (1971) 125 CLR 529; Gamser v Nominal Defendant (1977) 136 CLR 145; and FAI General Insurance Co Ltd v Southern Cross Exploration NL (1988) 165 CLR 268. There are a number of exceptions and qualifications to this principle but none that has any relevance to the present application, unless it be that subsequent to a final order application may be made for the purpose of dealing with a matter involved in, or arising in the course of, working out that order; for example, by making more specific provision for its implementation or by modifying its operation to take account of some subsequent change of circumstance or by enforcing it. This exception or qualification does not, however, extend to an application made for the purpose of giving substantive relief not sought in the statement of claim or which is substantially different to that given by the final order: see generally Haviland v McLeary (1894) 15 LR (NSW) (Eq) 22; 10 WN (NSW) 146; Poisson & Woods v Robertson & Turvey (1902) 86 LT 302; 50 WR 260; 46 Sol Jo 196; Dowdle v Hillier (1949) 66 WN (NSW) 155; Re Porteous [1949] VLR 383; [1950] ALR 89; Cristel v Cristel [1951] 2 KB 725 and Re Scott (1964) 82 WN (Pt 1) (NSW) 313; [1964-5] NSWR 1636. 166 The principles as to the usual scope of liberty to apply were restated in Abigroup v Abignano (1992) 112 ALR 497 as follows (per Lockhart, Morling & Gummow JJ) at 509: The reservation of liberty to all parties to apply to a court is a provision directed essentially to questions of machinery which may arise from the implementation of a court's orders. They include cases where a court may need to supervise the enforcement of orders after they have been made. They relate essentially to orders (not often to declarations) in practice in our experience. We agree with the submission of counsel for the appellant that orders of this kind relate to enforcement and not to statements of the rights of the parties. Historically orders reserving liberty to apply are for limited purposes. They arise, for example, upon a decree for specific performance where the unsuccessful defendant declines to sign all documents and do whatever is necessary to ensure that the contract the subject of the suit is performed. The reservation of liberty to apply ensures that the court may then make orders to secure that the relevant contract is enforced by the defendant by, for example, appointing the appropriate officer of the court to execute the necessary documents of conveyance so as to give title to the successful plaintiff. Historically the reservation by the Court of Chancery of further consideration of a decree was intended to cover the circumstance where following the pronouncement of the decree (a final decree) a further hearing was necessary for the court to deal with some outstanding issue sometimes requiring taking further evidence and making further declarations or orders. But this did not detract from the initial orders as being final orders. Rather it was a mechanism designed by the Court of Chancery to obviate the necessity of a further suit being instituted to deal with matters that were essentially consequential upon the making of the initial final decree. This demonstrates that there is no inconsistency between the making of final decrees, judgments or orders or declarations and subsequent orders of the court. It all depends upon the circumstances of the case and the particular orders or decrees formulated by the court. See generally the discussion with respect to liberty to apply and further consideration in Ritchie's Supreme Court Practice ( NSW ), paras 42.12.2 and 42.12.3. 167 Relevantly, the reference was to the following passage in Ritchie's [42.12.2]: Liberty to apply in relation to final orders Where liberty to apply is granted in relation to a final order, it is limited to matters concerning the implementation of the earlier order: Dowdle v Hillier (1949) 66 WN (NSW) 155; Cristel v Cristel [1951] 2 KB 725 at 730; Re Porteous [1949] VLR 383. It does not extend to the variation or amendment of the judgment or orders in respect of which the liberty to apply was granted ( Wentworth v Woollahra Municipal Council (CA(NSW), 31 March 1983, unreported)) 168 The statements of principle in these cases and in Ritchie's should be read as applicable to the ordinary case. The context may show that a more liberal meaning was intended in a particular case. 169 As appears from the judgment of McLelland J in Phillips, the usual limitation on the scope of liberty to apply arises from the proceedings "[having] been disposed of by a final order". That, speaking generally, forecloses further proceedings in the same cause. Exceptions do not extend to "an application made for the purpose of giving substantive relief not sought in the statement of claim or which is substantially different to that given by the final order". 170 In the present case, the proceedings have not been disposed of and the present claims are not outside the scope of the earlier process or substantially different from the orders previously made. In 1984, the plaintiffs sought relief against nuisance by the defendant. The consent orders of 11 November 1986 did not determine the issue as to whether any nuisance was being committed. In particular, the injunction in paragraph 1 of the orders left open whether the flow of water from St Johns Avenue onto the plaintiffs' land constituted a nuisance. Any attempt by the plaintiffs to enforce the injunction would have required proof that the situation in that regard constituted a nuisance. The order in paragraph 3 was a mandatory injunction limited to the stormwater which would be carried within the upgraded IADL. It did not relate at all to overland flow of stormwater. The core of the plaintiffs' case that the defendant was guilty of nuisance by discharging stormwater onto the plaintiffs' land, which would not naturally have flowed onto it, was not determined by those orders. 171 For an order to be made now declaring that there has been a nuisance in that regard since the commencement of these proceedings would be to determine a claim made by the plaintiffs in the proceedings which was not determined by the orders made on 11 November 1986; and such an order made now would not be inconsistent with those orders. 172 In the circumstances of the present case, such an order can be made within the ambit of the reservation of "liberty to apply" construed in that context. 173 An injunction restraining the defendant from committing that nuisance (if so found) would follow as a matter of course, damages being an inadequate primary remedy. 174 The present claim for special and general damages to date is consequential. It is limited to the period from 11 November 1986. An award of damages to the date of an injunction restraining a defendant from committing a nuisance is a normal incident of an action for nuisance. Damages are awarded only to the date of the injunction because it is assumed that the nuisance will then cease. If the nuisance is not abated, further damages are recovered. If a finding of nuisance is now made and an injunction granted restraining the defendant from committing that nuisance, damages are recoverable to date in the ordinary course. In the present case, that would not include damages for harm suffered prior to 11 November 1986 because damages for that period have been agreed and paid. 175 The claim for $8,000 and interest, in relation to the agreement to grant an easement and the installation of the extended drainage line on the plaintiffs' land, arises in consequence of the orders made in that regard on 11 November 1986, and is comprehended by the reservation of liberty to apply. Any procedural impediment to that course should be waived in the interests of resolving all matters still in dispute concerning the subject matter of these proceedings. 176 There would be an implication in the reservation of liberty to apply that such reservation should be exercised without undue delay. In the present case, delay in reactivating the proceedings is to be seen as arising in the following circumstances. First, the nature of the nuisance has been that the harm done is episodic. Secondly, the plaintiffs have kept the defendant informed about the situation since the orders were made and have persistently complained about it. If the plaintiffs have a case for complaint, they should not be penalised for their restraint in not reactivating the proceedings earlier. The defendant has been kept informed and has had the opportunity of dealing with the situation. It has not been prejudiced by the lapse of time. 177 In the circumstances, I do not regard the lack of earlier action by the plaintiffs as unreasonable. 178 It is unnecessary to explore the circumstances in which the courts will entertain action on a compromise in the same proceedings: Roberts v Gippsland Agricultural and Earth Moving Contracting Co. Pty Ltd [1956] VLR 555; Phillips v Walsh (1990) 20 NSWLR 206; St George v Wallis [2001] NSWSC 23. Those cases show, however, that there is no rigid rule that a compromise concludes the proceedings irrevocably. 179 There is an alternative route to the same result. It is important to recognise that the hearing of these proceedings in November 1986 was not concluded by a determination of the court. The hearing was discontinued pursuant to an agreement. The parties agreed to discontinue the hearing on the basis of certain orders to be made concerning things to be done and not done, and a supplementary recorded agreement concerning further things to be done, without the proceedings being otherwise expressly dismissed or terminated. The agreed orders included an injunction in terms which left unresolved whether a continuation of the existing conditions would be in breach of the injunction. 180 It must have been contemplated, in these circumstances, that, if it became necessary to resolve that question, the parties would have to come back to the court. Liberty to apply was reserved. 181 Can it have been intended that, in that eventuality, the plaintiffs would have to commence fresh proceedings? It cannot. To so intend would serve no purpose. It would be absurd. Contractually, liberty to apply in this case included the right to move for a determination that the conditions existing at the commencement of the proceedings and continuing thereafter constituted a nuisance. The defendant is estopped by contract from opposing an application for that purpose. Nuisance and Negligence 182 It was submitted on behalf of the defendant that the law of nuisance is now assimilated to that of negligence. Reference was made to the decision of the High Court in Brodie v Singleton Shire Council (2001) 180 ALR 145. That case was, however, limited to public nuisance. 183 Reference was also made to the decision of the Court of Appeal in England in Holbeck Hall Hotel Ltd v Scarborough Borough Council [2000] 2 All ER 705. Hewitt-Smith LJ with whom the other members of the court agreed referred to the law relating to adoption of a nuisance. He referred to the old law that, in private nuisance, only the person who by himself or his servant or agent created the nuisance on his land which interfered with the use and enjoyment of his neighbour's land was liable: at [29]. He referred to Sedleigh-Denfield v O'Callaghan [1940] AC 80, where it was held that an occupier of land continues a nuisance if, with knowledge or presumed knowledge of its existence, he fails to take reasonable means to bring it to an end: at [30]. The concept of presumed knowledge equated with what the occupier should or ought to have known: at [41]. His Lordship went on to refer to developments in the law of negligence as a basis upon which to confine the wrongdoer's responsibility to damage which was no greater in extent than that which was foreseen or foreseeable. 184 I do not read Holbeck Hall as having so radical an effect as to assimilate the law of private nuisance to that of negligence (although the headnote may suggest otherwise). At all events, I am not bound by that decision and, at my level of the judicial hierarchy, I would not presume to depart so radically from the settled law in this jurisdiction. For a full discussion of the differences between private nuisance and negligence, see Fleming, The Law of Torts, 9th ed (Sydney: Law Book, 1998), at 473-4. Law: nuisance 185 The basic legal principles applicable to the present case are clear and well settled. I take the following summary of the relevant law from Fleming, The Law of Torts, 9th ed (Sydney: Law Book, 1998), Ch.21. 186 The gist of private nuisance is interference with an occupier's interest in the beneficial use of his or her land. The interest protected is a broad and comprehensive notion. It includes the pleasure, comfort and enjoyment which a person normally derives from the occupancy of land. The gravity of the harm is related to its character and duration. 187 In relation to private nuisance, negligence on the part of the defendant is not required, and the exercise of reasonable care to avoid harm is not a defence. 188 The standard of unreasonable interferences is objective. It has regard to the reactions of normal persons in the locality, not to the idiosyncrasies of the particular plaintiff. 189 An occupier continues a nuisance and is liable for it if the occupier knows or ought reasonably to know of its existence. An occupier adopts a nuisance and is responsible for it if the occupier utilises whatever constitutes the nuisance. 190 An occupier responsible for a nuisance is under a duty to abate the nuisance by reasonably prompt and effective action to terminate it. 191 A public authority is immune from an action for nuisance if the harm done is an inevitable consequence of the exercise of statutory authority. The burden of proving inevitability is on the defendant. If the cost of avoiding harm arising from the only practicable means of exercising statutory authority would be prohibitive, the harm is inevitable. Nuisance, subject to special defences 192 The incursion of stormwater onto the plaintiffs' land has significantly interfered with the plaintiffs' use and enjoyment of their property. 193 The increment of stormwater from the street, being in excess of stormwater arriving at the plaintiffs' land naturally, has made a material difference to the plaintiffs' use and enjoyment of their property. 194 That, however, is not a necessary finding. The question is one of causation of harm. The legal concept of causation is that harm results from an act or omission if the act or omission causes or materially contributes to the harm. 195 In Bonnington Castings Ltd v Wardlaw [1956] AC 613, the plaintiff was injured by dust in the course of his employment. The dust came from hammers and from grinders. It was practicable to prevent dust from the grinders from entering the workplace atmosphere and the employer was negligent in failing to do so, but it was not practicable to prevent dust coming from the hammers. The House of Lords held that the dust from the grinders materially contributed to the worker's injury, provided only that dust from that source was not a negligible contribution. It was unnecessary for the worker, in that case, to establish that, but for the dust from the grinders, he would not have suffered harm. 196 Conformably, where more than one person contributes to a nuisance, all are individually liable notwithstanding that the contribution of any one of them would be insufficient on its own to constitute a nuisance: Thorpe v Brumfitt (1873) 8 Ch. App. 650, 656; Blair & Sumner v Deakin, Eden & Thwaites v Deakin (1887) 57 LT 522, 525; Pride of Derby & Derbyshire Angling Association Ld v British Celanese Ld [1952] 1 All ER 1326 (per Harman J at 1331 – 1333). 197 In the present case, it is sufficient that the aggregate stormwater incursion onto the plaintiffs' property has significantly interfered with the plaintiffs' use and enjoyment of the land – as it has done – and that the incursion of stormwater from the street, in excess of stormwater arriving naturally, has not been negligible – as is also the case. The interference with the plaintiffs' use and enjoyment of their land is then to be seen, in legal concept, as resulting from the incursion of stormwater from the street. 198 Having regard to the findings of fact which I have made, the defendant has prima facie been guilty of nuisance at and since the commencement of these proceedings in 1984, by reason of the discharge of stormwater from St Johns Avenue onto the plaintiff's land via various routes, and notwithstanding the works carried out in 1987 and 1999. 199 It remains to consider whether the defendant has an answer by way of special defence. Special defences 200 The defendant denies nuisance on the ground that there has been no unreasonable interference with the plaintiffs' beneficial use of their land. That general defence has been rejected. 201 The defendant raises more particular defences. These are as follows. Statutory Immunity 202 The defendant invokes sections 731 and 733 of the Local Government Act 1993, which re-enacted identical provisions in earlier legislation. 203 Section 731 does not apply to liability on the part of a municipal council, as distinct from the council's members, employees, etc. 204 Section 733(1) provides an immunity against liability for anything done or omitted in good faith by a council "in so far as it relates to the likelihood of land being flooded or the nature or extent of any such flooding". 205 Uninstructed by authority, I would have read this provision as effectively limited to flood mitigation work. I would read the likelihood of flooding as a condition antecedent to the act or omission. If the legislature had intended to grant a blanket immunity against liability for flooding private land that could have been said in much plainer words. (The true intention of the legislature is clear from the reference to "flood liable land" in the heading to the section, but the courts are, strangely, precluded from having regard to such headings by the Interpretation Act 1987, s 35.) 206 That having been said, I am precluded from implementing my own view by the decision of Hodgson J in Attrill v Richmond River Shire Council (1993) 30 NSWLR 122, relevantly approved by the Court of Appeal: Attrill v Richmond River Shire Council (1995) 38 NSWLR 545. 207 The decision relates to the identically worded forerunner of s733. The basic element in Hodgson J's approach was that the section covered any acts or omissions giving rise to the likelihood of land being flooded, but the immunity related only to past acts and omissions. Accordingly, damages for acts or omissions committed before the proceedings were commenced were refused but an injunction against committing prospective acts or omissions was granted. 208 Conformably, his Honour expressed the tentative opinion that damages in lieu of injunction would not be barred provided the damages related to prospective events. That, with respect, would seem to follow necessarily from the basic reasoning. 209 On appeal, the only challenge was to the rejection of the claim for damages in relation to past events. Hodgson J's approach was approved and the appeal was dismissed. There was no cross appeal challenging the injunction in relation to prospective events. 210 So construed, s733 and its forerunner provide no answer to the plaintiffs' claim in the present case. Attrill permits an injunction, and damages are claimed in the present case only from 11 November 1986. They relate to the continuance of a nuisance as from that date. The claim is not related to events occurring before action, the proceedings having been commenced in 1984. The claim in relation to the easement across the rear of the plaintiffs' property is not affected by the statutory provision. Authorisation 211 The defendant is authorised by statute to carry out roadworks including associated drainage works. There is an implied immunity against action for interference with private rights, if such interference is the inevitable consequence of the exercise of such authority. 212 Expense is a consideration. I am not satisfied, however, that the defendant is incapable of applying or raising the funds required to avoid the adverse effect on the plaintiffs of the defendant's exercise of statutory authority, nor that to do so would be intolerably or even unreasonably disruptive of discharge by the defendant of its public responsibilities or of the defendant's programmes and budgetary plans in that regard. 213 The interference with the plaintiffs' rights is not, in the relevant sense, an unavoidable incident of the exercise of statutory authority by the defendant. Statutory authority is, therefore, not an answer to the plaintiffs' claim in that regard. Injunctive relief and cost of compliance 214 Injunctive relief is discretionary. Insofar as cost of compliance may be a relevant consideration, I make the following observations. 215 The costs of compliance has not been fully explored. The preferred solution to the problem of street stormwater being discharged onto the plaintiffs' land is, according to Mr Lucas, to abandon the SDL and extend the in-road street drainage line uphill, and downhill to link up with an existing drainage system. On the available evidence, I have found the likely cost of that solution to be in the order of $200,000. 216 There is, possibly, another solution available. That is to extend the in-road line uphill as proposed by Mr Lucas and to increase the capacity of the existing SDL and of the line across the rear of the plaintiffs' property and beyond, by installing a larger diameter pipe. The evidence suggests that this may be necessary only where that line is relatively flat. The proposal may require resumption with compensation, in the absence of agreement, since the defendant is presently limited to the existing 600 mm pipe. The utility, practicability and cost of this approach was not fully explored in the evidence. It may be feasible and cheaper. 217 In these circumstances, I take the cost of compliance with an injunction as being in the order of $200,000, although that has not been satisfactorily established because of the possible alternative, which may be practicable and cheaper. 218 I do not regard that cost as disproportionate. Such expenditure can reasonably be expected of the defendant in order to prevent the discharge of stormwater from the street onto the plaintiffs' land. The proposed easement over No. 48 219 The orders of 11 November 1986 included, in paragraph 3, that the defendant carry out the works in Annexure A to the orders. That included the extension of the pre-existing drainage system to the rear of No. 46, across the rear of No. 48, and then on to a connection further downhill. 220 The minutes of order included a note of further matters agreed between the parties. I have not reproduced the note. These matters included provision for the grant of an easement across the rear of the plaintiffs' land to accommodate that section of the proposed extension of the drainage system, for an agreed consideration of $8,000. 221 The defendant installed the new line across the rear of the plaintiffs' property without waiting for the plaintiffs to execute a transfer granting the easement. The defendant is not to be criticised for that. 222 A transfer was submitted for execution. There were communications in relation to its form. One way or another, whether for that reason or some other reason, a transfer has not been executed to this date. The defendant has not moved the court for specific performance, but has declined to pay the agreed sum of $8,000. 223 The plaintiffs claim $8,000 and interest. 224 The plaintiffs have no contractual right because the easement has not been granted and they do not say they have been ready and willing to execute a transfer conforming in terms with the agreement noted on 11 November 1986. However, the defendant has taken the benefit of use of the plaintiffs' land, for the purpose of enabling it to carry out works intended to abate the nuisance, which it admitted existed at that time. That the works carried out have not abated the nuisance is beside the point. In these circumstances, the plaintiffs have a quasi-contractual entitlement to a reasonable price for the use of their land by the defendant. The value of that use was agreed in 1986 at $8,000. That should be taken as the reasonable price for what has been provided. 225 The plaintiffs should accordingly have judgment for $8,000 plus interest. 226 No special reason is established for compound interest. Interest should be awarded pursuant to s94 at Schedule J rates. The works were carried out between February and June 1987. 1 July 1987 should be taken as the start date for the interest calculation. Special damages 227 There is a claim for special damages in relation to costs incurred by the plaintiffs between November 1987 and January 1988 and between January 1999 and April 2001 in an aggregate amount of $12,887.30. The evidence in support of this claim is in Mr Bonnici's affidavit sworn on 15 June 2001 paragraphs 6 to 12. None of what is said there was challenged factually in cross-examination, either as to causation or quantum. 228 The damages are claimed on a cause of action for nuisance which existed when these proceedings were instituted in 1984 and which has continued to this date. The claim for special damages is not barred by time. 229 There should accordingly be judgment for the plaintiffs under this head of claim for $12,887.30 plus interest at Schedule J rates from the dates or approximate dates on which the costs were incurred. (I suggest a broad brush approach to fix the dates on which these costs were incurred referrable respectively to the two parcels of costs to which I have referred.) General damages 230 For the same reason as mentioned in relation to special damages, the claim for general damages is not barred by time. 231 I assess general damages for the period 11 November 1986 to date at $50,000 for the plaintiffs jointly. Interest should be added at the rate applicable to general damages. Conclusion 232 I make no final orders at this stage. 233 Subject to matters of detail and fine tuning, the plaintiffs are entitled to the following relief: (1) An order declaring that, as at commencement of these proceedings and since, the defendant has been guilty of nuisance in causing or allowing stormwater from St Johns Avenue, Gordon, to flow, directly and indirectly, onto the plaintiffs' land, No. 48 St Johns Avenue, Gordon. (2) That the defendant, its servants and agents be restrained from causing or allowing stormwater to flow, whether directly or indirectly, from St Johns Avenue, Gordon, and from the footpath adjacent thereto onto the plaintiffs' land, No. 48 St Johns Avenue, Gordon. (3) The foregoing injunction should be suspended for 6 months. (4) Judgment in the sum of $8,000 plus interest in relation to the proposed easement across the rear of the plaintiffs' property. (5) Judgment in sum of $12,887.30 plus interest in relation to special damages. (6) Judgment in the sum of $50,000 plus interest in relation to general damages. 234 Counsel should bring in short minutes of order on a date specified by me. 235 I will hear argument as to costs on that occasion if the order as to costs is not agreed. -o0o- Last Modified: 12/21/2001 DISCLAIMER - Every effort has been made to comply with suppression orders or statutory provisions prohibiting publication that may apply to this judgment or decision. The onus remains on any person using material in the judgment or decision to ensure that the intended use of that material does not breach any such order or provision. Further enquiries may be directed to the Registry of the Court or Tribunal in which it was generated.