Supreme Court New South Wales Medium Neutral Citation: Rodriguez & Sons Pty Ltd v Queensland Bulk Water Supply Authority trading as Seqwater (No 10) [2018] NSWSC 149 Hearing dates: 19 February 2018 Date of orders: 19 February 2018 Decision date: 19 February 2018 Jurisdiction: Common Law Before: Beech-Jones J Decision: Tender of simulations rejected Catchwords: EVIDENCE – simulations in expert's report – based on inflows that expert now disavows – rejected under s 135 Evidence Act Legislation Cited: Evidence Act 1995 (NSW), ss 55, 79, 135 Cases Cited: Rodriguez & Sons Pty Ltd v Queensland Bulk Water Supply Authority trading as Seqwater (No 9) [2017] NSWSC 1116 Category: Procedural and other rulings Parties: Rodriguez & Sons Pty Limited (Plaintiff) Queensland Bulk Water Supply Authority t/as Seqwater (First Defendant) SunWater Limited (Second Defendant) State of Queensland (Third Defendant) Representation: Counsel: J Sexton SC; N Owens SC; R Yezerski; J Taylor (Plaintiff) B O'Donnell QC; A Pomerenke QC; D Piggott; D Klineberg (First Defendant) D Williams SC; HJA Neal; N Simpson (Second Defendant) GA Thompson QC; JM Horton QC; E Morzone (Third Defendant) Solicitors: Maurice Blackburn Pty Ltd (Plaintiff) King & Wood Mallesons (First Defendant) Norton Rose Fulbright (Second Defendant) Crown Solicitor for the State of Queensland (Third Defendant) File Number(s): 2014/200854 EX TEMPORE Judgment 1. The plaintiff seeks to tender part of a report from Dr Christensen provided in February 2015 which sets out the details of four simulations of what Dr Christensen then described as reasonably competent flood operations, specifically, flood operations that assumed a start date of either 6, 7 or 9 January 2011, as well as a simulation which assumed that, at some point, there was a "fuse plug breach" leading to a discharge down the auxiliary spillway of Wivenhoe Dam. 2. I will deal with the objection to the tender of the simulations involving start dates of 6, 7 and 9 January first. 3. All of the defendants object to the tender of this material. Firstly, they contended it did not meet the test of relevance in s 55 of the Evidence Act 1995 (NSW). Secondly, they contended, for reasons that I will outline, that it does not satisfy s 79. Thirdly, they contended that it should otherwise be excluded under s 135. 4. I outlined the progression of the reports given by Dr Christensen in Rodriguez & Sons Pty Ltd v Queensland Bulk Water Supply Authority trading as Seqwater (No 9) [2017] NSWSC 1116 at [7] and [33] to [40]. Ultimately, in Dr Christensen's response report there was produced a number of simulations, including what has been described as "Simulation I", which is the plaintiff's primary case. Simulation I assumes a start date for flood operations of 2 January 2011 (Rodriguez (No 9) at [35]). The statement of claim was amended to incorporate all of the simulations included in Dr Christensen's response report (Rodriguez (No 9) at [53]. 5. However, those simulations do not embrace all of the various permutations that might follow if the plaintiff was to be "successful" in establishing a breach of duty by the flood engineers but not successful in demonstrating they adopted an erroneous approach on all issues in dispute. For example, the statement of claim pleads in paragraph 245 an alternative case, that even if flood operations did not have to commence on 2 January 2011, they should have nevertheless commenced on 6 January 2011 and done so "substantially in accordance with the simulation in [the] Christensen Report, Chapter X, [1426] to [1572]", that is, being the simulation with a start date of 6 January 2011 the subject of this objection. 6. The difficulty is that since the time of Dr Christensen's report in February 2015, there have been substantial revisions to the method by which he has determined the volume of inflows of water into the Somerset and Wivenhoe Dams during the relevant period. Without being exhaustive, these revisions include a change from the use of a method known as the curve number method to the utilisation of the real‑time flood model that was available to the flood engineers, changes to the initial and continuing loss rates and various corrections of some particular errors. 7. At the risk of gross oversimplification, any simulation has as a crucial step in its analysis a determination of the forecast inflow of water into the dams. Based on that analysis, there is then a determination of what the likely lake levels will be, assuming no water is released, which then in turn affects both the choice of the relevant strategy to adopt under the flood mitigation manual as well as the various water release rates. 8. All of the simulations throughout the various reports of Dr Christensen have been accompanied by a detailed spreadsheet which sets out the inflows and outflows into the various dams as occurred, as well as under the simulations, together with the actual and simulated lake levels. 9. The essence of the objections to the simulations is that in circumstances where, in his response report, Dr Christensen makes it clear that given the changes that have occurred to inflow estimates, he does not "suggest that the flood engineers should have operated the dams on the basis of the inflow estimates that I used in my simulations" in his February 2015 report, then it follows that those simulations are not relevant, are not supported by his expert opinion and are otherwise liable to be excluded under s 135. 10. Senior counsel for the plaintiff, Mr Sexton SC, confirmed that the simulations with commencing dates of 6, 7 and 9 January as set out in Dr Christensen's February 2015 report are being adduced in circumstances where there was included in the pleading an alternative claim that flood operations should have commenced on those days in accordance with Dr Christensen's methodology and because updated simulations involving those start dates were not provided by Dr Christensen in his response report. Thus, the overall utility of this material from the plaintiff's perspective is to leave open the potential for it to argue, based on the findings that may ultimately be made, that it can succeed on an alternative case involving those start dates. 11. I have previously observed that I am not in a position to determine whether it would be open to the plaintiff to take advantage of the Court's findings and ultimately bring in some further simulation not specifically the subject of evidence from Dr Christensen in his response report (Rodriguez (No 9) at [24] to [31]). I am not in a position to decide that now. However, that possibility will not be advanced by the tender of this material. Given that Dr Christensen does not suggest that the inflow estimates which underpin these simulations should have been adopted, it would follow that these simulations could never form the basis of a finding by the Court as to what reasonable flood operations would entail. 12. In terms of relevance, I accept these simulations have some relevance in that they are examples of the methodology adopted by Dr Christensen, particularly as it involves the use of rain forecasts. However, in other parts of various reports, Dr Christensen opines in detail on that topic and there are a number of other simulations which do not have the same difficulties with inflow estimates. 13. Thus, whilst I accept that the material may have some relevance, I do not attribute to it any high probative value. 14. I will pass over the question of s 79 of the Evidence Act and its application to this material. It is not necessary to determine whether an earlier version of a simulation given by an expert based upon what was, at the time, a limited set of resources where the expert later says that that material has been superseded, satisfies s 79. 15. In my view, the material should, however, be excluded under s 135. 16. In light of the other parts of the evidence that will be adduced from Dr Christensen, to which I understand there is to be no objection, and bearing in mind the difficulties with the inflow estimates for these three simulations, the probative value of this material is very low. However, its tender has the potential to be both "misleading" and cause an "undue waste of time." 17. The material has the potential to be misleading because, in the absence of knowing the application of Dr Christensen's methodology to the particular start date using the approach to inflows from his response report, one will not be able to ascertain at any particular time what the likely lake levels would have been during the course of the simulation, ie, the lake levels presented in the simulations the subject of this objection simply do not represent Dr Christensen's current opinion as to what they would have been, assuming starting dates for flood operations of 6, 7 or 9 January. 18. The material is likely to be productive of an undue waste of time because of the difficulties for the defendants in testing the material when the numbers that are being put forward in the simulations do not represent the approach that Dr Christensen would now adopt if he were to re‑do them. 19. Accordingly, the 6, 7 and 9 January simulations as set out in Dr Christensen's report of February 2015 will not be admitted. 20. The same reasoning applies to the simulation that assumes a fuse plug breach. As I understood the relevance of that simulation, it was that it would demonstrate that, even if an application of Dr Christensen's methodology had led to a fuse plug breach, an outcome that everyone would regard as quite serious, it nevertheless would, according to the plaintiff, have yielded a better result downstream than that which resulted from the defendants' operations. 21. Pitched at that level of generality, its potential relevance can be accepted. Nevertheless, when one bears in mind the significance of estimating inflows to the testing of the details of a simulation, then it follows that the tender of that simulation would also cause an undue waste of time and be misleading. 22. Accordingly, I reject the tender of that simulation as well. ********** 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. Decision last updated: 23 February 2018