Queensland Bulk Water Supply Authority t/as Seqwater v Rodriguez & Sons Pty Ltd

[2021] NSWCA 206

Court of Appeal

Supreme Court

New South Wales

• Summary available

Medium Neutral Citation:

Queensland Bulk Water Supply Authority t/as Seqwater v Rodriguez & Sons Pty Ltd [2021] NSWCA 206

Hearing dates:

17-21 and 24-28 May 2021

Date of orders:

8 September 2021

Decision date:

08 September 2021

Before:

Basten JA; Meagher JA; Leeming JA

Decision:

(A)   In matter 2020/189434 (Seqwater’s appeal) –

(1)   In relation to orders relating to group members not the subject of final orders, grant Seqwater leave to appeal.

(2)   Allow the appeal and –

(a)   set aside order (3) made on 29 May 2020 in Rodriguez (No 23) and orders (3)-(6) made on 7 May 2021 in Rodriguez (No 29);

(b)   set aside order (2) made on 29 May 2020 in Rodriguez (No 23) and order (1) made on 7 May 2021 in Rodriguez (No 29) in so far as the answers to the common questions relate to Seqwater or its employees;

(c)   set aside orders 1-4 made on 28 October 2020 in Rodriguez (No 24), in so far as they relate to costs payable by Seqwater, and remit to the primary judge any outstanding issue as to the costs of the proceeding in the Common Law Division in matter 2014/200854 involving Seqwater.

(3)   Subject to the remittal provided in order (2)(c), dismiss the proceedings in the Common Law Division in matter 2014/200854 as against Seqwater.

(4)   Order that the first respondent (Rodriguez & Sons Pty Ltd) pay the appellant's costs of the appeal.

(B)   In matter 2020/189716 (Rodriguez’ application for leave to appeal) –

Dismiss the summons seeking leave to appeal (with no order as to costs).

Catchwords:

APPEALS – leave to appeal – representative proceedings – interlocutory orders – orders final with respect to the representative party – no finality as to group members claims – challenge to answers to common questions

TORTS – negligence – standard of care – acts or omissions of public authority – exercise of statutory function – statutory protection – application of Wednesbury standard of care – Civil Liability Act 2003 (Qld) s 36

NEGLIGENCE – standard of care – conduct of flood operations – compliance with Flood Operations Manual – construction of Manual written by flood engineers for application by flood engineers – purposive construction – dual purposes of water supply and flood mitigation – concept of flood mitigation – releases not to exceed peak inflows – use of best available rainfall forecasts – degrees of tolerance – scope for professional judgment – role of the senior flood operations engineer in determining strategies

NEGLIGENCE – causation – factual causation – cumulative effect of sequential breaches – series of acts jointly sufficient to cause harm – division of single course of conduct into discrete breaches artificial

TORTS – damage to property – whether liability apportionable – concurrent wrongdoers – whether acting independently of each other – Civil Liability Act 2003 (Qld) s 30

TORTS – damages – prejudgment interest on damages – property damage – awards with respect to cleaning undertaken by volunteers – interest on such awards – interest on subventions in form of charitable relief

COSTS – apportionment of costs – wrongful conduct governed by Queensland law – proceedings brought in New South Wales – Civil Procedure Act 2005 (NSW), s 98 applied

Legislation Cited:

Acts Interpretation Act 1954 (Qld), ss 2, 6, 35C

Brisbane and Area Water Board Act 1979 (Qld), ss 9, 106, 107, 108

Civil Law (Wrongs) Act 2002 (ACT), s 111

Civil Liability Act 2002 (NSW), ss 5D, 43, 43A; Pt 4

Civil Liability Act 2002 (Tas), s 40

Civil Liability Act 2002 (WA), ss 5Y, 5X

Civil Liability Act 2003 (Qld), ss 9, 11, 16, 22, 28, 30, 31, 32A, 32B, 32C, 34, 35, 36, 37, 38; Ch 2, Pt 2, Pt 3, Div 1

Civil Procedure Act 2005 (NSW), ss 56, 58, 98, 100, 162, 180; Pt 10

Civil Proceedings Act 2011 (Qld), s 58

Constitution, ss 51(xx), 73

Federal Court of Australia Act 1976 (Cth), s 33ZC; Pt IVA

Fire Brigades Act 1909-1956 (NSW), s 46

Human Rights Act 1998 (UK), s 6

Jurisdiction of Courts (Cross-Vesting) Act 1987 (NSW), s 9

Jurisdiction of Courts (Cross-Vesting) Act 1987 (Qld), ss 3, 4, 11

Law Reform (Miscellaneous Provisions) Act 1946 (NSW), s 5

Law Reform (Vicarious Liability) Act 1983 (NSW), s 10

Law Reform Act 1995 (Qld), ss 6, 7

South East Queensland Water (Restructuring) Act 2007 (Qld), ss 3, 6, 7, 9, 11, 14, 15, 17, 18, 19, 34, 44, 45, 47, 48, 49, 50, 51, 54, 56, 57, 61, 63, 64, 67, 72, 73, 81; Ch 2, Pt 1, Pt 4, Divs 1, 2, 3, 4, Pt 6; Sch 3 (Dictionary)

South East Queensland Water Board Act 1979 (Qld), s 106

Statutory Instruments Act 1992 (Qld), s 7

Supreme Court Act 1933 (ACT), s 69

Supreme Court Act 1970 (NSW), ss 101, 103

Supreme Court Act 1986 (Vic), Pt 4A

Water Act 2000 (Qld), ss 19, 38, 50, 95, 98,103, 107, 107A, 108, 109, 110, 119, 497, 808, 813, 1071; Sch 4 Dictionary

Water Resources Act 1989 (Qld), ss 215F, 215Y

Water Supply (Safety and Reliability) Act 2008 (Qld), ss 13, 21, 22, 370, 371, 374, 589, 613; Ch 4, Pt 2

Wivenhoe Dam and Hydro-Electric Works Act 1979 (Qld), ss 32, 33, 34, 35

Workers’ Compensation Act 1926 (NSW), s 16

Wrongs Act 1958 (Vic), s 84

Uniform Civil Procedure Rules 2005 (NSW), r 51.40; Pt 58

Cases Cited:

Associated Provincial Picture Houses Ltd v Wednesbury Corporation [1948] 1 KB 223

Aston Cantlow and Wilmcote with Billesley Parochial Church Council v Wallbank [2004] 1 AC 546

Attorney-General for the State of New South Wales v Quin (1990) 170 CLR 1; [1990] HCA 21

Avon Downs Pty Ltd v Federal Commissioner of Taxation (1949) 78 CLR 353; [1949] HCA 26

Bailey v Federal Commissioner of Taxation (1977) 136 CLR 214; [1977] HCA 11

Bankstown City Council v Zraika; Roads and Maritime Services v Zraika (2016) 94 NSWLR 159; [2016] NSWCA 51

Batchelor v Burke (1981) 148 CLR 448; [1981] HCA 30

Blundell v Musgrave (1956) 96 CLR 73; [1956] HCA 66

Board of Fire Commissioners (NSW) v Ardouin (1961) 109 CLR 105; [1961] HCA 71

Boensch v Pascoe (2019) 268 CLR 593; [2019] HCA 49

Bunnings Group Ltd v CHEP Australia Ltd (2011) 82 NSWLR 420; [2011] NSWCA 342

Chapman v Hearse (1961) 106 CLR 112; [1961] HCA 46

Chase Oyster Bar Pty Ltd v Hamo Industries Pty Ltd (2010) 78 NSWLR 393; [2010] NSWCA 190

CHEP Australia Ltd v Bunnings Group Ltd [2010] NSWSC 301

Communications, Electrical, Electronic, Energy, Information, Postal, Plumbing and Allied Services Union of Australia v Queensland Rail (2015) 256 CLR 171; [2015] HCA 11

Coulton v Holcombe (1986) 162 CLR 1; [1986] HCA 33

Crimmins v Stevedoring Industry Finance Committee (1999) 200 CLR 1; [1999] HCA 59

CSR Ltd v Eddy (2005) 226 CLR 1; [2005] HCA 64

Curtis v Harden Shire Council (2014) 88 NSWLR 10; [2014] NSWCA 314

Darling Island Stevedoring and Lighterage Co v Long (1957) 97 CLR 36; [1957] HCA 26

Davidson v J S Gilbert Fabrications Pty Ltd [1986] 1 Qd R 1

Ferguson v Wilson (1866) LR 2 Ch App 77

Fire & All Risks Insurance Co Ltd v Callinan (1978) 140 CLR 427; [1978] HCA 31

George v Federal Commissioner of Taxation (1952) 86 CLR 183; [1952] HCA 21

Giles v Thompson [1994] 1 AC 142

Gill v Donald Humberstone & Co Ltd [1963] 1 WLR 929

Griffiths v Kerkemeyer (1977) 139 CLR 161; [1977] HCA 45

Grincelis v House (2000) 201 CLR 321; [2000] HCA 42

Hamcor Pty Ltd v Queensland [2014] QSC 224

Hamcor Pty Ltd v State of Queensland [2016] 1 Qd R 271; [2015] QCA 183

Hollis v Vabu Pty Ltd (2001) 207 CLR 21; [2001] HCA 44

Housman v Camuglia [2021] NSWCA 106

James Hardie & Coy Pty Ltd v Wyong Shire Council (2000) 48 NSWLR 679; [2000] NSWCA 107

John Pfeiffer Pty Ltd v Rogerson (2000) 203 CLR 503; [2000] HCA 36

Kars v Kars (1996) 187 CLR 354; [1996] HCA 37

Kuru v New South Wales (2008) 236 CLR 1; [2008] HCA 26

Labuda v Langford [2001] ACTSC 126; 36 MVR 154

Leichhardt Municipal Council v Montgomery (2007) 230 CLR 22; [2007] HCA 6

MBP (SA) Pty Ltd v Gogic (1991) 171 CLR 657; [1991] HCA 3

National Insurance Co of New Zealand Ltd v Espagne (1961) 105 CLR 569; [1961] HCA 15

NEAT Domestic Trading Pty Ltd v AWB Ltd (2003) 216 CLR 277; [2003] HCA 35

O'Brien v Dawson (1942) 66 CLR 18

Oceanic Crest Shipping Company v Pilbara Harbour Services Pty Ltd (1986) 160 CLR 626

O’Toole v Charles David Pty Ltd (1990-1991) 171 CLR 232; [1990] HCA 44

Pioneer Mortgage Services Pty Ltd v Columbus Capital Pty Ltd (2016) 250 FCR 136; [2016] FCAFC 78

Plaintiff S157/2002 v Commonwealth of Australia (2003) 211 CLR 476; [2003] HCA 2

Plymouth Brethren (Exclusive Brethren) Christian Church v The Age Company Ltd (2018) 97 NSWLR 739; [2018] NSWCA 95

Powercor Australia Ltd v Thomas (2012) 43 VR 220; [2012] VSCA 87

Prince Alfred College Inc v ADC (2016) 258 CLR 134; [2016] HCA 37

Project Blue Sky Inc v Australian Broadcasting Authority (1998) 194 CLR 355; [1998] HCA 28

Puntoriero v Water Administration Ministerial Corporation (1999) 199 CLR 575; [1999] HCA 45

Queensland v Masson [2020] HCA 28; 94 ALJR 785

R v Panel on Take-overs and Mergers; Ex parte Datafin Plc [1987] 1 QB 815

Re Anti-Cancer Council (Vic); Ex parte State Public Services Federation (1992) 175 CLR 442; [1992] HCA 53

Redding v Lee (1983) 151 CLR 117; [1983] HCA 16

Renmark Hotel Inc v Federal Commissioner of Taxation (1949) 79 CLR 10; [1949] HCA 7

Roads and Maritime Services v Grant [2015] NSWCA 138

Screenco Pty Ltd v R L Dew Pty Ltd (2003) 58 NSWLR 720; [2003] NSWCA 319

Sempra Metals Ltdv Inland Revenue Commissioners [2008] 1 AC 561

Soblusky v Egan (1960) 103 CLR 215; [1960] HCA 9

South West Helicopters Pty Ltd v Stephenson (No 2) (2018) 98 NSWLR 96; [2018] NSWCA 99

Southern Properties (WA) Pty Ltd v Executive Director of the Department of Conservation and Land Management (2012) 42 WAR 287; [2012] WASCA 79

Stovin v Wise [1996] AC 923

Strong v Woolworths Ltd (2012) 246 CLR 182; [2012] HCA 5

Sutherland Shire Council v Heyman (1985) 157 CLR 424; [1985] HCA 41

Suttor v Gundowda Pty Ltd (1950) 81 CLR 418; [1950] HCA 35

Thompson v Australian Capital Television Pty Ltd (1996) 186 CLR 574; [1996] HCA 38

Van Gervan v Fenton (1992) 175 CLR 327; [1992] HCA 54

Voli v Inglewood Shire Council (1963) 110 CLR 74; [1963] HCA 15

Zhang v ROC Services (NSW) Pty Ltd (2016) 93 NSWLR 561; [2016] NSWCA 370

Zheng v Cai (2009) 239 CLR 446; [2009] HCA 52

Texts Cited:

J Carter, The Construction of Commercial Contracts (Hart Publishing, 2013)

P Craig, Administrative Law (8th ed, 2016, Sweet & Maxwell)

R Creyke and J McMillan, “Soft Law versus Hard Law” in Pearson, Harlow and Taggart (eds) Administrative Law in a Changing State: Essays in Honour of Mark Aronson (Hart Publishing, 2008)

R Douglas, G Mullins and S Grant, Annotated Civil Liability Legislation – Queensland, (3rd ed, Lexis Nexus Butterworths 2012)

J Edelman (ed), McGregor on Damages (21st ed, 2021, Thomson Reuters)

R Garnett, Substance and Procedure in Private International Law (Oxford University Press, 2012)

H Luntz and S Harder, Assessment of Damages for Personal injury and Death (5th ed, LexisNexis, 2021)

G Weeks, Soft Law and Public Authorities (Hart Publishing, 2016)

Qld Govt Gazette, vol 353, no 15 published 22 January 2010

Category:

Principal judgment

Parties:

2020/189434:
Queensland Bulk Water Supply Authority t/as Seqwater (Appellant)
Rodriguez & Sons Pty Ltd (First Respondent)
SunWater Ltd (Second Respondent)
State of Queensland (Third Respondent)

2020/189716:
Rodriguez & Sons Pty Ltd (Appellant)
Queensland Bulk Water Supply Authority t/as Seqwater (First Respondent)
SunWater Ltd (Second Respondent)
State of Queensland (Third Respondent)

Representation:

Counsel:

J Stoljar SC, D Klineberg, T Prince – Queensland Bulk Water Supply Authority t/as Seqwater
J Sexton SC, N Owens SC, R Yezerski, J Taylor, S Chordia – Rodriguez & Sons Pty Ltd
HJA Neal – SunWater Ltd
JM Horton QC, D Bampton – State of Queensland

Solicitors:

King & Wood Mallesons – Queensland Bulk Water Supply Authority t/as Seqwater
Maurice Blackburn – Rodriguez & Sons Pty Ltd
Norton Rose Fulbright Australia – SunWater Ltd
Crown Law – State of Queensland

File Number(s):

2020/189434; 2020/189716

 Decision under appeal 

Court or tribunal:

Supreme Court

Jurisdiction:

Common Law Division

Citation:

[2019] NSWSC 1657; [2020] NSWSC 650; [2020] NSWSC 1498; [2021] NSWSC 145; [2021] NSWSC 483

Date of Decision:

29 November 2019

Before:

Beech-Jones J

File Number(s):

2014/200854

headnote

[This headnote is not to be read as part of the judgment]

The appellant, Queensland Bulk Water Supply Authority (“Seqwater”), owns and operates two dams in south-east Queensland, west of Brisbane. Outflows from Somerset Dam on the Stanley River flow into Wivenhoe Dam, which is on the Brisbane River. The dams supply water for south-east Queensland, including the City of Brisbane. The dams also mitigate downstream flooding by storing water at the peak of heavy rains and releasing it over time. The operation of the dams in flood events is directed by flood engineers following strategies described in a Flood Operations Manual. In ascending order of priority, the strategies address the protection of bridges from submergence, urban areas from inundation and the dams from structural failure. The Manual recorded the flows at which the downstream bridges would be submerged, and the maximum flow beyond which urban areas would be inundated.

Releases of water from Wivenhoe flow east down the Brisbane River through Brisbane and Ipswich. Before reaching the city two major tributaries, Lockyer Creek and the Bremer River, flow into the Brisbane River. Roughly half the catchment of the Brisbane River lies above Wivenhoe and half below it. Flows below Wivenhoe are measured at Lowood, being the junction with Lockyer Creek, and at Moggill, just below the Bremer River junction and before the Brisbane River enters the urban areas.

In early January 2011, torrential rains fell in the catchment of the Brisbane River and its tributaries. A large volume of water was released from Wivenhoe Dam to prevent it overtopping, which, once combined with heavy downstream flows, flooded large areas of Brisbane and Ipswich.

In 2014 the respondent, Rodriguez & Sons Pty Limited (“Rodriguez”), the owner of a Brisbane sporting goods store which had suffered loss as a result of the flooding, commenced a class action against Seqwater, SunWater Ltd and the State of Queensland on behalf of some 6500 group members, alleging that negligent operation of the dams had resulted in widespread property damage. Rodriguez alleged that the flood operations engineers should have made substantial releases from the dams before the heaviest of the forecast rain to create extra storage capacity. Rodriguez alleged that had the engineers followed the Manual, they would not have had to make substantial releases of water to prevent the dams from overtopping at a time of high flows from Lockyer Creek and the Bremer River.

The primary judge delivered his principal judgment on 29 November 2019, finding in Rodriguez’ favour on the question of liability. Several additional judgments followed assessing and awarding damages to Rodriguez and three group specific members, answering common questions in respect of group members generally, and dealing with costs. The orders apportioned liability between the three defendants, namely 50% to Seqwater, 30% to SunWater and 20% to the State. (Other questions and the assessment of damages payable to group members remained to be determined.)

Seqwater appealed against these findings. Prior to the hearing of the appeal, Rodriguez settled its claims against SunWater and the State.

The issues before the Court were whether, contrary to findings made by the primary judge:

1. a lower standard of care provided statutory protection to Seqwater, limiting the circumstances in which it could be liable in damages;

2. flood mitigation strategies under the Manual were not to be determined by assuming that no releases of water would be made;

3. the strategies did not require decisions based on forecast rainfall but only “rain on the ground”;

4. releases were not permitted which would take the dams below Full Supply Level;

5. the reference in the Manual to releases not exceeding “peak inflow” precluded high releases in advance of heavy rainfall;

6. the engineers acted reasonably in opening sluice gates at Somerset Dam in order to co-ordinate the storage levels in the two dams;

7. the Senior Flood Operations Engineer bore primary responsibility for determining strategies;

8. the engineers were not required to have made releases in accordance with simulations prepared by Dr Christensen;

9. it was reasonable to terminate the December Flood Event on 2 January;

10. the strategies adopted by the engineers from 6-10 January were reasonable;

11. breaches of duty for which Seqwater was liable had not been shown to cause loss to the claimants where damage resulted from a series of sequential breaches;

12. the commercial value of cleaning undertaken by volunteers was fully recoverable;

13. interest was payable on damages awarded for cleaning services provided gratuitously by volunteers;

14. the apportionment of 50% of the damages against Seqwater was just and reasonable; and

15. costs should have been apportioned on the basis of liability.

The Court (Basten, Meagher and Leeming JJA) held:

As to (1) – statutory protection for Seqwater

1. Section 36 of the Civil Liability Act 2003 (Qld) should not be read down to apply only to proceedings where the cause of action was breach of statutory duty. The omission of “duty” from s 36 suggested that the section was not limited to any particular cause of action; the term appeared only in the heading to that section and did not limit its operation: [69].

2. The reference to “functions” in s 36 applied to the functions of Seqwater provided for by statute, including flood prevention and floodwater control. The case against Seqwater correctly assumed it had functions with respect to the operation of the dam for flood mitigation purposes and that it was required to exercise its powers in accordance with a flood mitigation manual: [82].

3. Where Seqwater employed engineers to carry out its statutory functions, the acts or omissions of the engineers were attributable to Seqwater. Seqwater was therefore vicariously liable for the acts of the flood engineers: [102].

4. Seqwater is a public authority for the purposes of s 36, as it was established under statute, has the functions and powers conferred on it by the statute, does not have members of its corporate body who would benefit from its exercise of its functions, and its dominant purpose was to supply water for the benefit of residents and businesses in south-east Queensland. Although Seqwater was required to carry out its functions as a commercial enterprise, this did not prevent its functions from being those of a public authority: [116], [117], [121].

5. Although s 36(2) adopts the language of Wednesbury unreasonableness, the standard adopted by the statute should not be paraphrased or reformulated by reference to the Wednesbury standard in administrative law cases: [135]-[137]. For an authority to be liable, the exercise of a power must be so unreasonable that the court cannot envisage any authority in that position considering it to be a reasonable exercise of the power: [137].

Civil Liability Act 2003 (Qld) s 36; Acts Interpretation Act 1954 (Qld), s 35C(1), applied.

Board of Fire Commissioners (NSW) v Ardouin (1961) 109 CLR 105, 116; [1961] HCA 71; Darling Island Stevedoring and Lighterage Co v Long (1957) 97 CLR 36; [1957] HCA 26, applied; Attorney-General for the State of New South Wales v Quin (1990) 170 CLR 1; [1990] HCA 21; Avon Downs Pty Ltd v Federal Commissioner of Taxation (1949) 78 CLR 353; [1949] HCA 26; Crimmins v Stevedoring Industry Finance Committee (1999) 200 CLR 1; [1999] HCA 59; Plaintiff S157/2002 v Commonwealth of Australia (2003) 211 CLR 476; [2003] HCA 2; Puntoriero v Water Administration Ministerial Corporation (1999) 199 CLR 575; [1999] HCA 45; Prince Alfred College Inc v ADC (2016) 258 CLR 134; [2016] HCA 37; Renmark Hotel Inc v Federal Commissioner of Taxation (1949) 79 CLR 10; [1949] HCA 7; Re Anti-Cancer Council (Vic); Ex parte State Public Services Federation (1992) 175 CLR 442; [1992] HCA 53; Sutherland Shire Council v Heyman (1985) 157 CLR 424; [1985] HCA 41; Curtis v Harden Shire Council (2014) 88 NSWLR 10; [2014] NSWCA 314; Pioneer Mortgage Services Pty Ltd v Columbus Capital Pty Ltd (2016) 250 FCR 136; [2016] FCAFC 78; Southern Properties (WA) Pty Ltd v Executive Director of the Department of Conservation and Land Management (2012) 42 WAR 287; [2012] WASCA 79; Stovin v Wise [1996] AC 923, considered.

Hamcor Pty Ltd v Queensland [2014] QSC 224, not followed.

As to (2) – the “no release” assumption

1. In determining the appropriate release strategy, the Manual required the engineers to predict the water level of each dam. Although initial assessments could well be based on predicted inflows without releases, the Manual did not require that engineers select a strategy on the assumption that no water would be released during the likely period of the flood. It was not unreasonable for the engineers to have regard to the water which was being released: [261], [285].

As to (3) – “rain on the ground” forecasts

1. Modelling was required to take into account predicted rainfall based on forecasts, not just rain on the ground measurements. The engineers were required to determine strategies and releases having regard to forecast rainfall, which was permitted by their real time flood modelling: [205], [291], [294].

As to (4) – releases bringing the dams below Full Supply Level

1. The Manual did not prohibit releases from being made during a flood event while the dams were below full supply level, however the engineers were not obliged to make releases in such circumstances, including if the December flood event had continued beyond 2 January: [319]-[322].

As to (5) – references to “peak inflow” precluded high releases prior to heavy rainfall

1. While the general purpose of flood mitigation is to reduce the peak levels of flow in the river, rather than exacerbate them, the Manual permitted the use of rainfall predictions to consider in advance what the “peak inflow” during a flood event would be; however, this was not the only reasonable reading of the Manual: [330], [340].

As to (6) – opening sluice gates at Somerset Dam

1. The Manual required coordinated releases from Wivenhoe and Somerset Dams, generally following an Operating Target Line (OTL). On 9 and 10 January releases were made from Somerset Dam by opening its sluice gates. There was no apparent negligence in seeking to follow the OTL: [604].

As to (7) – responsibilities of the Senior Flood Operations Engineer

1. The senior flood engineer was employed by SunWater. It was a relevant consideration in applying s 36(2) and apportioning liability, that Seqwater’s engineers adhered to the strategy determined by the senior flood engineer: [659].

As to (8) – Dr Christensen’s simulations

1. The principal significance of Dr Christensen’s simulations was that they provided a counterfactual, consistent with non-negligent flood operations, which could form a basis for Rodriguez’ causation and damages case. Contrary to Seqwater’s submissions, Rodriguez’ breach case did not require it to establish that on each day from 2 to 11 January the flood engineers were required to conduct flood operations in accordance with one or more of those simulations: [424]-[433].

As to (9) – terminating the December Flood Event on 2 January

1. Seqwater’s engineer on duty on 2 January terminated the Flood Event when the level of Wivenhoe Dam reached 67.1m, when the dam had, for practical purposes returned to the FSL of 67.0m. That decision was not negligent. The Manual recognised that there was a degree of uncertainty inherent in measuring the water level of the dam. In addition, the weather forecasts did not predict significant rainfall: [455]-[460].

As to (10) – strategies on 6-10 January

1. The findings of breach of duty on 6, 7, 8 and 9 January were based on the “no release” assumption. The Manual did not require that assumption to be made. Absent that assumption, the evidence did not support a conclusion that a flood engineer must have adopted the strategies found to constitute reasonable flood operations; nor were there findings of breach if releases could be taken into account: [517], [519], [545], [573], [574], [602].

2. There is no utility in resolving the grounds directed to breach on 10 January. Those breaches involved releasing a relatively small amount of water that was immaterial and had no relevance to the causation analysis: [611]-[614].

3. Applying the s 36(2) standard, the four flood engineers acted by way of consensus, ultimately following the strategy determined by the Senior Flood Operations Engineer. Failure by Seqwater’s flood engineers to depart from that strategy was not proven to be in breach of the s 36(2) standard. Even if their conduct departed from the Manual, that did not of itself entail a breach of that standard: [659], [662], [666], [669], [672], [676], [683], [687].

As to (11) – causation – a series of sequential breaches

1. The primary judge found that losses had been caused by the cumulative effect of several breaches by the flood engineers. That approach was artificial: it involved the dividing of a singular course of conduct into discrete temporal segments and assumed that each flood engineer could and should exercise independent judgment. The flood engineers acted in a collaborative manner. On that basis all were liable for each breach. The fact that a particular engineer was on duty at a particular time was not a critical factor. The complaint as to causation was therefore rejected: [697]-[698].

Civil Liability Act 2003 (Qld) ss 11, 31(1)(a), applied; Strong v Woolworths Ltd (2012) 246 CLR 182; [2012] HCA 5, referred to.

As to (12) – quantifying the commercial value of cleaning by volunteers

1. It was not necessary nor appropriate to deal with the issue as to how cleaning services undertaken gratuitously were to be valued. There were contingent factual disputes, and uncertainty as to the legal basis upon which damages for such services were recoverable: there is doubt as to the application of principles developed in personal injury cases. The approaches to valuation advanced by the parties did not involve any question of law: [712], [715]-[717], [729].

Boensch v Pascoe (2019) 268 CLR 593; [2019] HCA 49 applied; Blundell v Musgrave (1956) 96 CLR 73; [1956] HCA 66; CSR Ltd v Eddy (2005) 226 CLR 1; [2005] HCA 64; Davidson v J S Gilbert Fabrications Pty Ltd [1986] 1 Qd R 1; Griffiths v Kerkemeyer (1976) 139 CLR 161; [1977] HCA 45; Powercor Australia Ltd v Thomas (2012) 43 VR 220; [2012] VSCA 87; Screenco Pty Ltd v R L Dew Pty Ltd (2003) 58 NSWLR 720; [2003] NSWCA 319, referred to.

As to (13) – interest payable on damages for cleaning services

1. Claims for interest were in their nature compensatory and therefore Queensland law applied: [736].

John Pfeiffer Pty Ltd v Rogerson (2000) 203 CLR 503; [2000] HCA 36 applied.

1. In dealing with cleaning costs with respect to damaged chattels or property, there was no error in refusing to award interest: [750].

Screenco Pty Ltd v R L Dew Pty Ltd (2003) 58 NSWLR 720; [2003] NSWCA 319, applied.

1. With respect to interest on damages not reduced for charitable payments, there were issues of principle as to when and on what basis subventions operated to reduce damages; because these issues were not addressed, the approach of the primary judge accorded with current practice: [759].

Batchelor v Burke (1981) 148 CLR 448 at 455; [1981] HCA 30; Fire & All Risks Insurance Co Ltd v Callinan (1978) 140 CLR 427 at 432; [1978] HCA 31; Grincelis v House (2000) 201 CLR 321; [2000] HCA 42, referred to.

As to (14) – apportionment of 50% of the damages against Seqwater

1. There are real doubts as to the statutory basis of apportionment: [704]. In the absence of a finding as to damages it was not appropriate to determine the issue. However, as Seqwater was the sole licensee responsible for controlling releases into the Brisbane River, it was difficult to envisage that its liability would be less than 50%: [709]-[710].

Civil Liability Act 2003 (Qld) ss 28(4) and 30(1) referred to.

As to (15) – apportionment of costs

1. The ground challenging the costs order was brought as of right: [760]. The relevant law to the determination of this question was that of New South Wales, as the services generated in the plaintiff’s costs were in New South Wales: [765]-[767].

Civil Procedure Act 2005 (NSW) s 98 applied; Law Reform Act 1995 (Qld) ss 6, 7; Civil Liability Act 2003 (Qld) s 32A referred to.

Housman v Camuglia [2021] NSWCA 106; applied; James Hardie & Coy Pty Ltd v Wyong Shire Council (2000) 48 NSWLR 679; [2000] NSWCA 107; South West Helicopters Pty Ltd v Stephenson (No 2) (2018) 98 NSWLR 96; [2018] NSWCA 9; Labuda v Langford [2001] ACTSC 126; 36 MVR 154, referred to.

1. To apportion costs by reference to the apportionment of responsibility for damages did not of itself demonstrate error. The decision of the primary judge not to depart from the starting point of 50% liability did not disclose error: [763]; [773]-[774].

Chapman v Hearse (1961) 106 CLR 112; [1961] HCA 46; Voli v Inglewood Shire Council (1963) 110 CLR 74 at 101; [1963] HCA 15; Soblusky v Egan (1960) 103 CLR 215 at 239; [1960] HCA 9 referred to.

Judgment

INDEX

1	Introduction			1
2	Issues on appeal			7
3	Leave to appeal			14
4	Jurisdiction and choice of law			21
5	Factual background			24
6	Operation of the dams: legal structure			33
(1)	Restructuring Act		35
(2)	Water Act and Water Supply Act		50
7	Civil Liability Act – s 36 (ground 1)			59
(1)	Statutory provisions – Civil Liability Act		59
(2)	Breach of statutory duty – Rodriguez’ contention		65
(3)	Exercise of functions		74
(4)	Vicarious liability		83
(5)	“public or other authority”		103
(6)	Application of s 36 – Identification of standard		123
8	Vicarious liability (ground 2)			142
9	Negligence – Overview			143
10	Flood Operations Manual			154
(1)	An overview		154
(2)	The purposes of Wivenhoe Dam and Somerset Dam		160
(3)	Background to the Manual		166
(4)	Legal status of Manual		169
(5)	Overview of contents		177
(a)	Section 1	182
(b)	Sections 2-7	186
(c)	Section 8	194
(d)	Sections 9 and 10 and the Appendices	216
(6)	Key considerations		221
(7)	Degrees of tolerance		234
11	The “no release” assumption – (ground 8)			237
(1)	Significance of the no release assumption		238
(2)	Reasoning of primary judge		246
(3)	Consideration		260
(a)	Textual considerations	264
(b)	Purposive considerations	272
(c)	Circularity	279
(d)	Other considerations	282
(e)	Conclusion	285
12	“Best available forecasts” – (grounds 6, 7)			287
(1)	The grounds		287
(2)	Ground 6 – quantitative use		292
(3)	Ground 7 – “best forecast rainfall”		295
(4)	Rainfall forecasts over time		309
13	Releases below Full Supply Level – (grounds 12, 13)			316
14	Strategy W4 – (ground 9)			325
15	“Peak inflow” – (grounds 10, 11)			331
16	Operation of Somerset Dam – (grounds 14, 15)			343
(1)	Background		343
(2)	Issues at trial		356
(3)	Issues on appeal		363
17	Role of Senior Flood Operations Engineer – (ground 3)			372
18	Breaches of duty – Rodriguez’ application to rely on s 36(2)			380
(1)	Identifying the issues		380
(2)	Rodriguez’ application to rely on s 36(2)		382
(3)	Reasons for ruling on notice of contention		397
(a)	Section 36(2) was in issue at trial	398
(b)	Reliance on schedule of findings	406
(c)	Conditional grant of leave	410
(d)	Submissions in support of contention 3	414
19	Simulations C, F and H (grounds 16-21); breaches on 2-5 January 2011 (grounds 22, 23(a))			415
(1)	Overview		415
(2)	Challenges to overarching findings as to simulations C, F and H (grounds 16-20)		420
(a)	Simulation C	420
(b)	Simulations F and H	422
(c)	Disposition: grounds 16, 17 and 18	424
(d)	Disposition: grounds 19 and 20	431
(e)	Disposition: ground 21	434
(3)	Breach of duty: 2 January (ground 22)		435
(a)	Findings of primary judge	436
(b)	Terminating December Flood Event	444
(c)	Failing to make further substantial releases	461
(4)	Breaches of duty: 3, 4 and 5 January (ground 23(a))		474
(a)	Failure to reduce dam level	474
(b)	Failure to declare further flood event	476
(c)	Disposition: ground 23(a)	483
20	Breaches on 6-10 January – (grounds 23(b), (c), 24 and 25(a), (b))			486
(1)	Overview		486
(2)	Factual background		491
(3)	6 January – Mr Malone’s day shift (ground 23(b))		497
(a)	Summary of shift	497
(b)	Findings of breach	505
(c)	Disposition: ground 23(b)	513
(4)	7 January – Mr Malone’s day shift (ground 23(c))		522
(a)	Summary of shift	522
(b)	Findings of breach	532
(c)	Disposition: ground 23(c)	541
(5)	8/9 January – Mr Tibaldi’s overnight shift (ground 24)		547
(a)	Overview	547
(b)	Summary of Mr Ayre’s day shift	548
(c)	Summary of Mr Tibaldi’s overnight shift	560
(d)	Findings of breach	565
(e)	Disposition: ground 24	573
(6)	9 January – Mr Malone’s day shift (ground 25(a))		576
(a)	Summary of shift	576
(b)	Findings of breach	591
(c)	Disposition: ground 25(a)	600
(7)	10 January – Mr Malone and Mr Tibaldi’s day shift (ground 25(b))		605
(a)	Overview	605
(b)	Summary of shift	608
(c)	Disposition: ground 25(b)	611
21	Rodriguez’ contention par 3		615
(1)	Overview		615
(2)	Paragraph 48(d): 10 January		617
(3)	Paragraphs 48(e) and (f): Use of forecasts		633
(4)	Paragraph 48(b): keeping bridges open on 6 and 7 January		639
(5)	Paragraph 48(c): strategy W1 rather than W3		644
(6)	Relevant matters		650
(7)	Whether breach of s 36(2) standard		656
(a)	Mr Tibaldi’s overnight shift on 8/9 January	660
(b)	Mr Malone’s day shifts on 6, 7 and 9 January	663
(c)	Benefit of hindsight	684
(8)	Conclusions		687
22	Causation (grounds 26, 27)			688
(1)	Introduction		688
(2)	Appellants submissions		692
(3)	Conclusion		698
23	Apportionment (ground 28)			700
24	Damages for cost of cleaning by volunteers (ground 31)			711
25	Pre-judgment interest on damages			731
(1)	Identifying the issues		732
(2)	Applicable Law		734
(3)	Issues raised		737
(4)	Rodriguez’ appeal		741
(5)	Seqwater’s appeal – (ground 32)		752
26	Costs of trial – apportionment (ground 30)			760
(1)	Reasons of primary judge		761
(2)	Consideration		764
27	Costs – generally			776
(1)	Costs of trial		776
(2)	Costs of the appeal		778
28	Orders			780
Appendix A

1. THE COURT:

1. Introduction

In January 2011 a large volume of rain fell in the catchment of the Brisbane River. In its upper catchment, the Brisbane River was contained by the Wivenhoe Dam and, above it, the Somerset Dam. The dams had two functions, namely, to supply water to Brisbane and south-east Queensland, and to mitigate flooding of the Brisbane River. However, at the height of the heavy rainfall a volume of water released from the Wivenhoe Dam which, in combination with the inflows from downstream tributaries, led to the inundation of significant areas of Brisbane and Ipswich.

2. In 2014 a small business which had suffered loss as a result of the flooding, Rodriguez & Sons Pty Ltd (“Rodriguez” or “the plaintiff”), commenced a class action seeking to recover damages from the operators of the Wivenhoe Dam. Relevantly for present purposes, it alleged that the operators had been negligent in failing to commence releasing water from the Wivenhoe Dam several days earlier than they did, in anticipation of the heavy rainfall, so as to avoid the need to release much larger volumes in a short period after the rainfall caused large inflows and a surge in the dam level. The rising level caused fears for the safety of the dam, necessitating releases which, when combined with high flows from downstream tributaries, rendered extensive flooding of urban areas inevitable.

3. A trial held before Beech-Jones J extended from December 2017 through much of 2018, the last written submissions being received in May 2019. The principal judgment (one of many judgments delivered in the proceedings), was published on 29 November 2019 ^[1] and ran to more than 1,500 pages. The judgment was divided into 15 chapters, each with its own paragraph numbering. References to passages in that judgment will take the form “Rodriguez (22) Ch 1 [22].” Subsequent judgments have also given rise to issues addressed by the notice of appeal, the latest being Rodriguez (29) delivered on 7 May 2021, just 10 days before the hearing of the appeal commenced. ^[2]

   1. Rodriguez & Sons Pty Ltd v Queensland Bulk Water Supply Authority trading as Seqwater (No 22) [2019] NSWSC 1657 (“Rodriguez (22)”).

   2. Rodriguez & Sons Pty Limited v Queensland Bulk Water Supply Authority t/as Seqwater (No 29) [2021] NSWSC 483 (“Rodriguez (29)”).

4. Answers were given to numerous common questions which had been identified as appropriate for separate determination. The judgment upheld the claims of the plaintiff in negligence against the State of Queensland, and two statutory agencies responsible for operating the dams, namely Queensland Bulk Water Supply Authority trading as Seqwater (“Seqwater”) and SunWater Ltd. Other than the State of Queensland, each of the parties filed notices of appeal, although the plaintiff’s appeal was confined to a narrow issue. Final orders have been made with respect to the plaintiff itself in Rodriguez (23),^[3] in an amount (payable by Seqwater) in excess of $100,000, and in Rodriguez (29) with respect to three other members of the class, whose claims raised particular issues not raised by the plaintiff’s case. These matters are relevant to whether, and to what extent, Seqwater required leave to appeal, discussed below.

   3. Rodriguez & Sons Pty Limited v Queensland Bulk Water Supply Authority t/as Seqwater (No 23) [2020] NSWSC 650 (“Rodriguez (23)”).

5. Shortly before the appeals were listed for hearing, Rodriguez (in its representative capacity and in its own right), SunWater and the State of Queensland settled all claims between them. As a consequence, the only outstanding issues are those arising between Rodriguez (in its representative capacity and in its own right) and Seqwater. The issues for determination by this Court fall within a far narrower compass than those confronting the primary judge.

6. The trial judgment being divided into 15 chapters, it was inevitable in such a large factual case that findings would be made on specific issues which were then relied upon in the assessment of higher level issues, including ultimately the resolution of questions as to the existence and scope of the duty of care owed by each defendant, whether the duty was breached by each defendant and its employees, whether such breaches caused the harm suffered by the plaintiff, and the assessment of damages. At each of these stages, the judgment meticulously cross-referenced both later and earlier findings, so that the trail of the reasoning was readily ascertainable. That was as true of the complex technical evidence and the computer simulations relied upon by the plaintiff as it was of the factual circumstances as they occurred in January 2011. The tasks to be undertaken by this Court have been immeasurably assisted by the care and ultimately the clarity of the primary judgment.

2.   Issues on appeal

7. As the primary judge noted, practically no aspect of the case presented by the plaintiff was not in dispute at the trial. For example, each defendant challenged the claim that it owed a duty of care to the plaintiff and group members. When Seqwater filed its notice of appeal, it challenged findings by the judge as to its duty of care. However, those challenges (grounds 4 and 5) were abandoned shortly prior to the hearing of the appeal. Nevertheless, there remained 30 grounds, some with sub-grounds. A further amended notice of appeal, filed on 10 May 2021, included two new grounds 31 and 32. The issues in dispute on the appeal primarily focused on the applicable standard of care and the findings as to breach of duty.

7. As the primary judge explained, three factual issues predominated at trial, namely that: ^[4]

1. the flood engineers determined the amount of water to release only by reference to the estimate of inflows into the dam determined by rain that had already fallen, referred to as “rain on the ground” (or ROG), effectively ignoring forecasts as to rain;

2. the engineers wrongly gave priority to avoiding inundation of bridges downstream of Wivenhoe Dam at the expense of avoiding or minimising the risk of urban inundation, and

3. to the extent that the engineers did model future rainfall, they assumed that it would fall in the upper catchment, thus giving insufficient attention to the likely flood levels reached in downstream tributaries.

   4. Rodriguez (22), Ch 1 [28] set out in full at [147] below.

9. The activities of the flood engineers were regulated by a Flood Operations Manual (the Manual) which had been revised in November 2009. ^[5] The plaintiff’s case was identified by the primary judge in broad terms as follows:

“[26]   At the heart of the plaintiff’s case is the contention that during the period from 2 January 2011 to 10 January 2011 the flood engineers were obliged but failed to evacuate water from the dams in advance of rainfall predicted by rainfall forecasts. Critical to this allegation is the contention that the content of any duty of care owed by the flood engineers in relation to flood operations was governed by the Manual. The plaintiff contended that, irrespective of the approach at other dams, the Manual unambiguously required the use of forecasts in conducting flood operations, especially the selection of flood strategies by reference to predictions about reservoir levels based on rainfall forecasts and the making of releases from the dams, determined at least in part by reference to forecast rainfall. The plaintiff also contended that the Manual embodied an overall risk management approach to flood operations. This was said to require that releases from the Dams be made with a view to minimising the risk of urban damage, as well as dam failure, at the expense of the disruption to local communities caused by the inundation of bridges that span the upper part of the Brisbane River below Wivenhoe Dam as well as the risk to the water supply if the full supply level of water was not retained in the dams following the completion of flood operations.”

5. Seqwater, Manual of Operational Procedures for Flood Mitigation at Wivenhoe Dam and Somerset Dam (Revision No 7, November 2009).

10. Three issues as to the Manual arose on this appeal. The first was a matter of legal principle, namely how to construe the Manual. Was it to be construed by the court as a legal document, or was the correct approach to determine whether the conduct of the flood engineers was consistent with an understanding of its terms which was reasonably open in the circumstances? Because, as will be explained, the Manual did not create legally enforceable standards, the latter approach should be adopted.

11. The second and third issues involved specific issues in the application of the Manual. The second issue was whether it was reasonable to construe the Manual as not permitting reduction of the level of Wivenhoe Dam below Full Supply Level (FSL) in anticipation of a possible future flood event. If that were so, the plaintiff’s case as to releases between 2 and 6 January 2011 was difficult to uphold. The third issue was whether assessments of the appropriate “strategy” (as described in the Manual) for managing the dams during a flood event were to be undertaken by reference to expected inflows, without taking account of likely outflows. The strategies were defined by the level to which it was expected water would rise. The plaintiff contended that, in assessing likely dam levels, the engineers were required to assume “no releases”; that meant estimating the likely level to which water would rise during the adopted forecast period on the basis that no water would be released.

12. However, at the forefront of Seqwater’s case on appeal was the legal submission that the standard of care to be applied was not that of reasonable care under s 9 of the Civil Liability Act 2003 (Qld), but rather the attenuated standard required of public authorities under s 36 of the Civil Liability Act. Section 36, if applicable, imposed a higher hurdle for the plaintiff in establishing that Seqwater acted tortiously in the exercise of its functions. Establishing the standard by which Seqwater’s conduct was to be judged was a necessary preliminary to considering the factual elements of the claim in negligence. The primary judge found that s 36 of the Civil Liability Act was not engaged: as a result, the standard of care applied in judging Seqwater’s conduct was the ordinary standard of a failure to take reasonable precautions against a foreseeable and not insignificant risk of harm, as required by s 9 of the Civil Liability Act. However, if engaged, s 36(2) provided that an act or omission was not “wrongful” unless it was “so unreasonable that no public or other authority having the functions of the authority in question could properly consider the act or omission to be a reasonable exercise of its functions.”

13. The challenge to the finding that s 36 was not engaged was identified as ground 1 in Seqwater’s appeal. Determining that issue is a preliminary and necessary step before addressing the factual basis of the alleged negligence. That in turn requires a consideration of the legal framework under which Seqwater operated.

3.   Leave to appeal

14. The issues sought to be raised by Seqwater undoubtedly warrant a grant of leave to appeal, if required: indeed, leave was not opposed and could be granted by consent. However, it is desirable to explain why leave may be required.

15. The Supreme Court Act 1970 (NSW), s 101(2)(e), provides that an appeal shall not lie from an interlocutory judgment of the Court in a Division except by leave. Separately, s 103 requires leave for an appeal from a decision of any question or issue ordered to be decided separately from any other question or issue. Where the answers to the separate questions result in the proceedings being finally determined, it has been held that an appeal lies as of right. In Plymouth Brethren (Exclusive Brethren) Christian Church v The Age Company Ltd,^[6] the principal majority judgment held that such an appeal was as of right, whilst noting that the issue had not been raised or argued. ^[7] That statement relied upon a discussion in the judgment of Brennan J in O’Toole v Charles David Pty Ltd,^[8] a case dealing with questions directed to be answered separately by a judge of the Federal Court, in a matter which was removed to the High Court before any answers were entered in the record of the Federal Court and thus raising a question as to the availability of appellate jurisdiction under s 73 of the Constitution. The other member of the majority in Plymouth Brethren had been party to a decision which took a different view and expressly declined to revisit the question, on the basis that if leave were required it should be granted. ^[9] Support for the conclusion that leave was not required may be found in the dissenting judgment at [120]-[123].

    6. (2018) 97 NSWLR 739; [2018] NSWCA 95.

    7. Plymouth Brethren at [111] (McColl JA).

    8. (1990-1991) 171 CLR 232 at 257; [1990] HCA 44.

    9. Plymouth Brethren at [2] (Beazley P).

16. On one view, the question is to be resolved by the specific provision in relation to stated questions, namely s 103 of the Supreme Court Act. That section appears to remove the issue from the ambit of the generic requirement with respect to an interlocutory order. Giving priority to the specific provision, the need for leave does not depend upon whether it is possible, because of the way the question is answered, to make a final order consequential upon the answer, or whether that is not possible. However, at least on one view, the function of s 103 is to sidestep the issue which troubled Brennan J in O’Toole, which was whether the answer to the separate question affected the rights and liabilities of the parties, or whether the answer was non-conclusive, in the sense that the judge who reserved the question for separate determination would not be bound by the answer in resolving the proceeding: O’Toole at 258. Only the former would result in a judgment, decree or order from which an appeal might lie to the High Court: O’Toole at 259. If that were in fact the function of s 103, there would be no inconsistency with the general approach to interlocutory orders: whether leave was required would turn on the legal effect of the order. Thus an appeal would lie as of right where the answers did give rise to a final order, despite the unqualified language of s 103.

17. The issue is complicated by the fact that the present matter involves a class action. Although a final order has been made as between the plaintiff and Seqwater, which should entitle Seqwater to an appeal as of right, the answers to the common questions have not given rise to final orders involving members of the class, other than three members, who are not parties to the appeal.

18. The proceedings brought by the plaintiff in a representative capacity engaged Part 10 of the Civil Procedure Act 2005 (NSW). Part 10 deals with appeals in s 180, but only by providing for appeals by the representative party. It does not vary the rights or procedures governing appeals by individual defendants, nor appeals by a plaintiff in its own right. It does, however, permit Rodriguez to bring an appeal in its representative capacity, which it did with respect to a limited issue concerning the calculation of damages. Presumably because an appeal is a fresh proceeding, s 180(5) appears to envisage that the class members have the right to opt out under s 162: that issue was not addressed in the present case. ^[10] The Uniform Civil Procedure Rules 2005 (NSW) (“UCPR”), Pt 58 does not take the matter any further. Nor does s 180 address the capacity of a representative plaintiff to be a representative respondent to an appeal.

    10. Cf Federal Court of Australia Act 1976 (Cth), s 33ZC(8), introduced in 2010.

19. Similar legislation with respect to class actions is found in Pt IVA of the Federal Court of Australia Act 1976 (Cth), and Pt 4A of the Supreme Court Act 1986 (Vic). However, the issue as to the nature of a judgment which determines the final outcome for the plaintiff, but not for class members, appears not to have arisen.

20. The correct view may be that to the extent that the appeal seeks relief with respect to the plaintiff’s judgment against Seqwater, which is in an amount in excess of the threshold in s 101(2)(r) of the Supreme Court Act, it is an appeal against a final order and may be brought as of right. However, to the extent the relief sought challenges answers to common questions affecting the basis on which the claims of class members are determined, Seqwater requires leave, pursuant to s 103. Because the issues form a common substratum for the individual and representative claims, and because the representative claims collectively involve a sum many times greater than the threshold, there should be a grant of leave to address the answers to the common questions.

4.   Jurisdiction and choice of law

21. As the primary judge noted, the events in question all occurred in Queensland; the plaintiff is a body corporate located in Queensland, as are the defendant statutory authorities and the State of Queensland. The primary judge suggested that the Court’s jurisdiction to hear the matter may derive, at least in part, from the Jurisdiction of Courts (Cross-Vesting) Act 1987 (Qld), s 4(1). That section purports to vest jurisdiction in the Supreme Court of another state or territory with respect to “State matters.” A “State matter” is one in respect of which the Queensland Supreme Court has jurisdiction otherwise than under a law of the Commonwealth or of another state: s 3(1).

22. However, there is no doubt that the New South Wales Supreme Court also has jurisdiction as to the subject-matter of the claims, which were claims in tort, including causes of action in negligence, trespass and nuisance. Jurisdiction over the defendants depended on service of the initiating process. So far as personal jurisdiction over the defendant Queensland entities is concerned, they were served with the initiating statement of claim and filed appearances. Accordingly, the jurisdiction of the Supreme Court did not depend on the Queensland Act, nor on the reciprocal s 9 of the Jurisdiction of Courts (Cross-Vesting) Act 1987 (NSW), providing that the Supreme Court may exercise jurisdiction in relation to a matter cross-vested by a law of another state.

23. The real issue in this case was identification of the correct State law to be applied. There was no dispute that the substantive law of Queensland governed the liability of both the State and the Queensland authorities, including, so far as necessary, the Acts Interpretation Act 1954 (Qld) in relation to questions of liability. ^[11] That Act states that it applies to “all Acts” (s 2), “Act” being defined to mean, relevantly, an Act of the Queensland Parliament: s 6. Conversely, the Interpretation Act 1987 (NSW) does not apply to statutes enacted by other State legislatures. In any event, the only choice of law questions arose in relation to identification of the interest payable on elements of the damages awarded and the apportionment of costs. For reasons which will be discussed in relation to that topic, the law of Queensland was the applicable law.

    11. John Pfeiffer Pty Ltd v Rogerson (2000) 203 CLR 503; [2000] HCA 36; Rodriguez (22), Ch 11 [1].

5.   Factual background

24. To understand the extensive evidence concerning the storm event in south-east Queensland in January 2011, and the effects of releasing water from the dams, it is necessary to outline the general topography of the affected areas. This was described by the primary judge in the following terms: ^[12]

“The Brisbane River catchment is bounded by the Great Dividing Range to the west and a number of smaller coastal ranges to the east and the north. Its headwaters are at the northern extent of the catchment, bounded by the Brisbane and Jimna Ranges. From there it meanders in a generally south-easterly direction, before running almost north-easterly to enter Moreton Bay near Brisbane. About half of the Brisbane River catchment lies downstream from Wivenhoe Dam.”

12. Rodriguez (22), Ch 2 [37].

25. A plan outlining the different catchments was conveniently set out by the primary judge. (Brisbane is shown on the far right of the map, downstream from Moggill gauge, which was the last measuring point for flows in the Brisbane River before they reached the urban areas of the city itself.)

26. The total catchment area is in the order of 13,570km² of which approximately half, some 7,000km², flow into Wivenhoe Dam (some via Somerset Dam): Ch 2 [39], [40]. The remainder produces flows into tributaries below Wivenhoe. As may be seen from the plan, Brisbane River flows broadly south-east from Wivenhoe Dam until it meets the Bremer River at which point it turns to flow north-east through Brisbane to the sea at Morton Bay. The other major tributary is Lockyer Creek, which joins the Brisbane River below Wivenhoe Dam at Lowood.

27. Somerset Dam was built first, construction being completed in 1956; the construction of Wivenhoe Dam was completed in 1984. The dams have three functions. First, and taken together, they are intended to supply water to south-east Queensland; secondly, they mitigate flooding in the Brisbane River valley and, thirdly, there is a small hydroelectric plant which feeds electricity into the south-east Queensland grid. The third function was irrelevant in the present case, except that the ownership of the dams vested in Seqwater did not allow that authority to control the hydroelectric plant or its operations.

28. The distinction between the first and second functions was identified by the designation of a FSL for each dam. Although the focus of the case was on the operation of Wivenhoe Dam, one particular issue concerned the operation of Somerset Dam. Wivenhoe Dam was considerably larger than Somerset, having a storage capacity at FSL approximately three times that of Somerset. As will be seen from the plan, the outflow from Somerset travelled along the course of the Stanley River a short distance into Wivenhoe.

29. The spillway of Wivenhoe Dam had a crest at an elevation of 57m. ^[13] Above the crest were five radial gates which could be raised to allow the release of water over the spillway. Full Supply Level for Wivenhoe was 67m. The top of the core of the dam was 80m but was described as “not resistant to overtopping”; ^[14] thus, once the dam level reached 80m there was an expectation of a structural failure with potentially “catastrophic consequences.”

    13. All heights are recorded as an Elevation Level (EL) in metres according to the Australian Height Datum (AHD).

    14. Manual at p 9 [3.2].

30. Overtopping was not likely to occur because the dam had an auxiliary spillway below 80m on which were situated three “fuse plug” embankments designed to erode once water flowed over them. Although the erosion was intended to occur in a “controlled manner”, erosion would result in a large and uncontrolled discharge of water. The “trigger levels” for the erosion of the three fuse plug embankments were stated as 75.7m, 76.23m and 76.78m respectively. However, the seeming precision of the trigger levels was qualified by the statement that initiation of the fuse plugs was expected to occur when the lake exceeded those levels by 0.1m-0.15m. ^[15]

    15. Flood Operations Manual, p 21.

31. In broad terms, the water supply function of Wivenhoe was to be met by maintaining the reservoir volume at the FSL of 67m. The area above 67m was identified in the Manual as “temporary flood storage”. However, to avoid uncontrolled discharge of water, it was necessary to keep the water level below 75.7m. The strategies for management of the water level during a “flood event” were identified in the Manual and will be discussed below.

32. As may also be seen from the Brisbane River Basin plan, there are two major tributaries of the Brisbane River below Wivenhoe Dam, but above the city of Brisbane. The first is Lockyer Creek, which flows into the Brisbane River at Lowood. There is a gauge at Lowood which measures combined flows from Lockyer Creek and Wivenhoe releases. The second tributary, the Bremer River, meets the Brisbane River some distance below Lowood. The combined flows from Lockyer, Bremer and Wivenhoe are measured at a gauge upstream from the major conurbation, known as Moggill gauge. Rates of flow likely to cause urban inundation are measured by the readings taken at Moggill.

6.   Operation of the dams: legal structure

33. The references to relevant legislation discussed below identify the provisions at the date of the events giving rise to the plaintiff’s claims, namely January 2011. The early (pre-2007) legislative scheme is not dealt with here, but in Part 10(2) in addressing the Flood Operations Manual.

34. There is no dispute that the “ownership” of both Wivenhoe Dam and Somerset Dam was vested in Seqwater. That was effected by notices published in the Queensland Government Gazette of 26 June 2008, pursuant to a power conferred on the responsible Ministers under the South East Queensland Water (Restructuring) Act 2007 (Qld) (“Restructuring Act”), s 67. ^[16] Nothing was said to turn on the concept of “ownership” in this context. It at least provided a basis for Seqwater to exercise its statutory functions in circumstances where its juristic nature was not entirely clear. Various provisions of the Restructuring Act bore upon submissions regarding the engagement of s 36 of the Civil Liability Act and, in particular, whether Seqwater was a “public authority constituted under an Act”, and what functions it exercised in carrying out flood mitigation activities. It is convenient at this point to address that legislative framework.

1. Restructuring Act

   16. Rodriguez (22), Ch 2 [10].

35. The purposes of the Restructuring Act were set out in s 3:

3   Purpose

The purpose of this Act is to facilitate a restructure of the water industry in south east Queensland to deliver significant benefits to the community, including—

(a)   improved regional coordination and management of water supply; and

(b)   more efficient delivery of water services; and

(c)   enhanced customer service for water consumers; and

(d)   a clearer accountability framework for water supply security.

36. Pursuant to s 6, four “new water entities” were established, including “the Queensland Bulk Water Supply Authority” (Seqwater). Section 6(2) stated that a new water entity was “not a body corporate” and did not “represent the State.” Nevertheless, each new water entity was stated to have “all the powers of an individual” including the power to enter into contracts, and the power to acquire, hold, dispose of and deal with property: s 7(1)(a) and (b). Further, “it” was said to have the powers given to it under an Act, but subject to any limitations under an Act: s 7(2) and (3). A new water entity was able to sue and be sued in the name given under s 6(1): s 7(4). ^[17] Section 14(2) provided that the entity must have a “board”, but was not constituted by the members of its board.

    17. Section 7 is set out at [39] below.

37. Despite the express terms of s 6(2), Seqwater was undoubtedly a trading corporation for the purposes of s 51(xx) of the Constitution: see Communications, Electrical, Electronic, Energy, Information, Postal, Plumbing and Allied Services Union of Australia v Queensland Rail,^[18] dealing with relevantly identical legislation establishing Queensland Rail. It is not aptly described as a corporation aggregate or a corporation sole, but it is clearly an entity having a separate juristic personality. It may well be a corporation for other purposes; however, the only question for present purposes was whether it was a public authority for the purposes of another Queensland statute, namely the Civil Liability Act. No party submitted that s 6(2), defining it as an entity other than a corporation, had any consequence for this purpose.

    18. (2015) 256 CLR 171; [2015] HCA 11.

38. Chapter 2, Pt 1 of the Restructuring Act, identifying the establishment, powers and functions of the new water entities, contained three provisions which were relied upon in considering whether the terms of s 36 of the Civil Liability Act were engaged; it is convenient to set them out in full.

39. First, the generic powers of the new water entities were set out in s 7:

7    Powers of new water entities

(1)   A new water entity has all the powers of an individual and may, for example—

(a)    enter into contracts; and

(b)    acquire, hold, dispose of, and deal with property; and

(c)    employ staff; and

(d)    appoint agents and attorneys; and

(e)    engage consultants; and

(f)    fix charges, and other terms, for services and other facilities it supplies; and

(g)    do anything else necessary or convenient to be done for its functions.

(2)    Without limiting subsection (1), a new water entity has the powers given to it under an Act.

(3)    However, a new water entity’s powers are subject to any limitations under an Act.

(4)    A new water entity may sue and be sued in the name it is given under section 6(1).

40. The functions of the new water entities, including Seqwater, were identified as follows:

9   Functions of new water entities other than the water grid manager

(1)   This section applies to a new water entity other than the water grid manager.

(2)   A new water entity has the following functions to the extent they are consistent with its operational and strategic plans—

(a)   carrying out water activities and other ancillary activities;

(b)   supplying water services and other ancillary services;

Example of an ancillary service—

delivering a community education program relating to the entity’s functions

(c)   supplying other services relating to the water industry, including—

(i)   engineering services; and

(ii)   services for operating or maintaining infrastructure; and

(iii)   business management services; and

Example—

services for managing government or business initiatives to save water

(iv)   energy generation; and

(v)   scientific services;

(d)   developing water supply works;

(e)   improving the supply, delivery and quality of water, including by way of—

(i)   riverine area protection; and

(ii)   soil erosion control; and

(iii)   land degradation treatment and prevention; and

(iv)   nutrient management; and

(v)   vegetation management;

(f)   using or managing the entity’s land in ways that benefit the community, including for recreational purposes;

(g)   anything else likely to complement or enhance a function mentioned in paragraphs (a) to (f);

(h)   another function conferred under an Act.

…

11   Functions to be carried out commercially

(1)   The water grid manager must, as far as practicable, carry out its functions in a way that is consistent with sound commercial principles.

(2)   A water entity other than the water grid manager must carry out its functions as a commercial enterprise.

(3)   Subsection (2) does not apply to a water entity to the extent it is required under this Act to perform a community service obligation other than as a commercial enterprise.

The reference in s 9(2) to “operational and strategic plans” picked up provisions in Ch 2, Pt 4, “Reporting and accountability” and specifically the provision for such plans in Div 4 of Pt 4.

41. Chapter 2, Part 2 of the Restructuring Act (encompassing ss 14-26) dealt with the appointment and membership of the boards of the entities; Part 3 dealt with senior executives. Each new water entity had a board which was “responsible for the way the entity performs its functions and exercises its powers”: s 15(1). A board was to consist of no fewer than two, nor more than five, members appointed by the “responsible Ministers”. The chairperson and deputy chairperson were appointed by the responsible Ministers (ss 17 and 18), who might also end the appointment of a person “at any time” for any reason or none: s 19(4). (The term “responsible Ministers” was defined to mean both “the Minister administering this Act” and “the Minister administering the entity.” ^[19] )

    19. Restructuring Act, Sch 3 (Dictionary), responsible Ministers.

42. Chapter 2, Part 4 recognised that a new water entity is a statutory body under the Financial Accountability Act 2009 (Qld): s 34(1)(a). Part 4 of the Restructuring Act dealt with “reporting and accountability”. Division 1 provided that each new water entity was a statutory body under the Financial Accountability Act and under the Statutory Bodies Financial Arrangements Act 1982 (Qld), and was a unit of public administration under the Crimes and Misconduct Act 2001 (Qld). Division 2 imposed obligations to report to the responsible Ministers. Division 3 provided for annual reports to be prepared in accordance with the Financial Accountability Act. Relevantly for present purposes, Div 4 provided for “Strategic and operational plans”.

43. Division 4 was comprised of ss 44-51. Section 44 recognised that the requirements of the Division overlapped with those of the Financial Accountability Act. Section 45 provided:

45   Draft strategic and operational plans

(1)   Before 31 March each year, a new water entity’s board must prepare, and submit to the responsible Ministers for their agreement, a draft strategic plan and a draft operational plan for the entity for the next financial year.

(2)   The board and the responsible Ministers must try to reach agreement on the draft plans as soon as possible and, in any event, not later than the start of the financial year.

44. Section 47 recognised that agreement between the responsible Ministers and the board might not be reached before the start of a financial year, in which case a draft plan was taken to be the entity’s strategic or operational plan, until s 48 came into effect. That provision read as follows:

48   Strategic or operational plan on agreement

When the draft strategic or operational plan has been agreed to in writing by the responsible Ministers, it becomes the entity’s strategic or operational plan for the relevant financial year.

45. Section 49 required that the entity “must comply with its strategic and operational plans for a financial year”, although there was power to modify a plan: s 50. Finally, s 51 provided for the contents of an operational plan (though not a strategic plan):

51   Content of operational plan

A new water entity’s operational plan for a financial year must include—

(a)   the entity’s objectives; and

(b)   the entity’s capital structure; and

(c)   an outline of the following matters—

(i)   the nature and scope of the activities proposed to be undertaken by the entity during the financial year;

(ii)   the entity’s main undertakings for the financial year;

(iii)   an outline of the borrowings made or proposed to be made by the entity;

(iv)   an outline of the entity’s policies for minimising or managing any risk of investments and borrowings that may adversely affect its financial stability; and

(d)   for a new water entity other than the water grid manager, an outline of the following matters—

(i)   the major infrastructure investments proposed to be undertaken by the entity during the financial year;

(ii)   an outline of the entity’s policies relating to the recreational use of the entity’s premises and other infrastructure; and

(e) the matters required under section 57.

46. Every financial year a new water entity other than the water grid manager (not being a commercial enterprise and not seeking to make a profit) must pay to the State an “annual return” in an amount determined by the Minister but not exceeding its estimated net profit for that year: ss 52-54.

47. Chapter 2, Pt 6 envisaged that a responsible Minister might give a direction in the public interest which was not in the entity’s commercial interests and which was designated a “community service obligation”: s 56. Such obligations were to be set out in the operational plan: s 57(3). Sections 58-63 gave the responsible Minister a degree of direct control over the operations of a new water entity – most notably, s 61 permitted the Minister to give the board of an entity a written direction “in relation to the entity” where, “because of exceptional circumstances”, it was “in the public interest” to do so. To that extent, the obligation to carry out functions commercially (s 11) and the freedom from direction by the government (s 63) were partly qualified. Under Part 9, when a new water entity expires, 99 years after its creation, the State is to be its successor: s 64. The entity was not liable to pay specified State taxes: s 81.

48. Chapter 3 Part 4 dealt with matters incidental to the application to the new water entities of the Water Act 2000 (Qld) (Water Act) and the Water Supply (Safety and Reliability) Act 2008 (Qld) (Water Supply Act). Sections 72 and 73 provided that each entity other than the water grid manager was “a water service provider” and was to be registered on the register of water and sewerage service providers required to be kept by “the regulator” under the Water Supply Act, s 13, although the ordinary procedures governing applications for registration ^[20] did not apply to the new water entities. For the most part, however, Seqwater’s operation of Somerset and Wivenhoe was authorised and regulated by the unqualified operation of those Acts.

    20. See Water Supply Act, ss 21, 22.

49. Returning to the terms of s 9(2), it may be noted that there was no express reference to the flood mitigation functions of the dams. However, the term “water activities” in s 9(2)(a) was defined in the Dictionary (Sch 3) to mean activities mentioned in the definition of the same term in the Water Act. That definition was in the following terms:

water activity, for a water authority, includes an activity for the following—

(a)   water conservation;

(b)   water supply;

(c)   irrigation;

(d)   drainage, including stormwater drainage;

(e)   flood prevention;

(f)   floodwater control;

(g)   underground water supply improvement or replenishment;

(h)   sewerage;

(i)   anything else dealing with water management.

Accordingly, the function of carrying out water activities included activities for flood prevention and floodwater control.

1. Water Act and Water Supply Act

50. The Water Act, s 19 stated that “[a]ll rights to the use, flow and control of all water in Queensland are vested in the State”. It is an offence for a person to “interfere with water” unless authorised to do so under that Act or a similar law of another state or territory: s 808(2). However, by s 107A(1) the holder of a “resource operations licence” is authorised “to interfere with the flow of water to the extent necessary to operate the water infrastructure to which the licence applies.”

51. The Water Act, s 38 permitted the relevant Minister to prepare a “water resource plan” for any part of Queensland, for purposes which might include “defin[ing] the availability of water for any purpose” and “provid[ing] a framework for sustainably managing water and the taking of water”. After the consultation process set out in ss 39-49A, including the preparation and publication of a draft plan, the Minister might prepare a final water resource plan, which would have effect when approved by the Governor in Council: s 50. Section 95 then permitted the chief executive of the relevant department to prepare a “resource operations plan to implement a water resource plan for any water in [all or part of] the plan area”. A draft resource operations plan, which would become a final resource operations plan through the operation of s 103, was to (among other things) “identify any water infrastructure to which the draft plan is intended to apply and how it will be operated”: s 98(1). Resource operations licences were to be granted by the chief executive, in accordance with the resource operations plan, on the day the plan comes into effect: s 107. If the plan set out a process for the granting of licences to meet “future water requirements”, licences might also be granted in accordance with that process: s 108. A resource operation licence could be held by the owner of the water infrastructure to which the licence applied or, if the owner were a subsidiary, its parent company: s 107A(3).

52. Seqwater held a resource operations licence for the Stanley River Scheme under the Moreton Resource Operations Plan (Operations Plan), which implemented the Water Resource (Moreton) Plan 2007. The licence relevantly provided:

“AUTHORITY TO INTERFERE

The licence authorises the licence holder to interfere with the flow of water in the Stanley River Water Supply Scheme, as detailed in the Plan – Chapter 5 – Central Brisbane River and Stanley River Water Supply Schemes, to the extent necessary to operate the water infrastructure to which the licence applies.

WATER INFRASTRUCTURE

The water infrastructure to which the licence applies is detailed in the Plan Attachment 5 – Central Brisbane River and Stanley River Water Supply Schemes.” (emphasis added)

53. Attachment 5 to the Operations Plan described Wivenhoe and Somerset Dams. Chapter 5 was largely concerned with water allocation and water sharing rules in the Central Brisbane River and Stanley River Water Supply Schemes, but it also contained s 72, which set minimum operating levels for infrastructure in the schemes and provided that releases could not be made from that infrastructure unless “necessary” to “meet minimum flow rates specified in section 75” or “supply downstream demand”. There was no reference to releases for flood mitigation purposes but neither party suggested that they were not necessary for either purpose, or that Seqwater was in breach of that condition. Seqwater’s position was that s 72 did not apply to water above the FSL of the dams.

54. There is a question whether the phrase “as detailed in the Plan – Chapter 5 – Central Brisbane River and Stanley River Water Supply Schemes” modified “to interfere with the flow of water”, in which case the grant authorised interference in the manner detailed in that chapter, or whether it merely described “the Stanley River Water Supply Scheme”. The better view may be that it did the latter. Subject to condition 3, condition 1 of the licence required the holder to comply “with the operating arrangements and supply requirements detailed in the Plan Chapter 5”. Condition 3 applied the “transitional arrangements” in schedule 1 of the licence in the event Seqwater was unable to comply with the requirements of the plan on the day the plan commenced. The transitional arrangements relevantly required Seqwater to comply with any “interim program” approved by the chief executive under s 13 of the plan. None of that is consistent with the clause beginning “as detailed” itself imposing an unqualified condition on the authority of the licence holder. That result would also sit awkwardly with the provisions of the Water Act concerning the imposition of licence conditions (ss 109, 110) and the consequences for licence holders of noncompliance: ss 119, 813.

55. In the event, Seqwater was unable to comply with the requirements of the plan, including s 72, and an interim program was approved. The interim program stated that, despite s 72, Seqwater would “continue to make releases from infrastructure for ... flood mitigation”. That part of the program had an indefinite duration and remained in effect in January 2011. It follows that by its licence Seqwater was authorised to interfere with the flow of water to the extent necessary to operate the dams, including for flood mitigation purposes, and that authorisation was not conditioned by s 72.

56. The provisions of the Water Supply Act relevant to flood mitigation were carved out of the Water Act by the enactment of the former. They were relevantly as follows. Section 370(1) provided that the owner of a dam might be nominated by regulation “as an owner who must prepare a manual (a flood mitigation manual) of operational procedures for flood mitigation for the dam”. As the explanatory note to the Water Supply (Safety and Reliability) Bill 2008 explained, “a dam nominated in the regulation will be a dam which was constructed for the purpose of flood mitigation”, and a flood mitigation manual “ensures that such dams make controlled releases of water for flood mitigation purposes in accordance with pre-agreed conditions”. Responsibility for approving and, if necessary, amending the manual rested with the chief executive, who was empowered to consult with an “advisory council” before doing so: ss 371, 372. Unlike the Brisbane and Area Water Board Act 1979 (Qld), which expressly required the Water Board (the former owner and operator of Wivenhoe and Somerset Dams) to prepare and follow flood mitigation manuals, ^[21] the Water Supply Act did not expressly require an owner or operator of a dam to comply with its flood mitigation manual. However, s 374(2) provided that the owner and operator, and its employees and agents, would not “incur civil liability for an act done, or omission made, honestly and without negligence in observing the [manual’s] procedures”. Where that immunity was engaged, “the liability attaches instead to the State”: s 374(3).

    21. Rodriguez (22), Ch 2 [70]-[71].

57. It appears that at the time the relevant version of the manual was approved there was no regulation in force pursuant to Water Supply Act, s 370 requiring Seqwater to produce a flood mitigation manual. Section 589 of the Water Supply Act did not give continuing effect to subordinate legislation made under the equivalent provisions of the Water Act (relevantly the former s 496, in the same terms as s 370). It is therefore not clear whether Seqwater was actually required to produce a manual for approval, but in any event there is no question that the relevant version of the manual was in fact approved under the Water Supply Act, s 371.

764. In these circumstances, the Law Reform Act 1995 (Qld) was not applicable. That is not because the Queensland Act was incapable of applying to the liability to pay a plaintiff’s costs. It is established that the right to recover statutory contribution pursuant to statutes in the form of ss 6 and 7 of the Law Reform Act (which enact the substance of s 5 of the Law Reform (Miscellaneous Provisions) Act 1946 (NSW)) extends to the costs payable to the plaintiff in addition to the damages: see James Hardie & Coy Pty Ltd v Wyong Shire Council; ^[251] South West Helicopters Pty Ltd v Stephenson (No 2). ^[252] (Seqwater made a formal submission to the primary judge that James Hardie was wrongly decided, but that submission was not renewed in this Court.)

     251. (2000) 48 NSWLR 679; [2000] NSWCA 107.

     252. (2018) 98 NSWLR 96; [2018] NSWCA 99 at [66].

765. Rather, the Queensland statute is inapplicable because the question is not determined by the law of Queensland. The services which generated the plaintiff’s costs were, at least in large measure, performed in New South Wales in order to conduct litigation in the Supreme Court of New South Wales. The closest connection between the costs order and any Australian jurisdiction was with New South Wales. In the event of dispute about the quantification of those costs, the order would fall to be assessed under the New South Wales assessment regime. The power to order costs is quintessentially procedural, rather than substantive, as Miles CJ observed in Labuda v Langford. ^[253] Professor Garnett has stated that the position is reasonably settled in Commonwealth countries. ^[254]

     253. [2001] ACTSC 126; 36 MVR 154 at [6].

     254. R Garnett, Substance and Procedure in Private International Law (Oxford University Press, 2012), p 159.

766. Separately from the above, Seqwater submitted that s 32A of the Civil Liability Act prevented the Law Reform Act applying as between concurrent wrongdoers. Section 32A provides:

32A   Contribution not recoverable from concurrent wrongdoer

Subject to this part, a concurrent wrongdoer against whom judgment is given under this part in relation to an apportionable claim—

(a)   can not be required to contribute to the damages recovered or recoverable from another concurrent wrongdoer for the apportionable claim, whether or not the damages are recovered or recoverable in the same proceeding in which the judgment is given; and

(b)   can not be required to indemnify the other concurrent wrongdoer.

769. Seqwater submitted that a declaration that it was liable to contribute to costs payable by a co-defendant contravened this provision. There is a large question as to whether, par (a) being limited to contribution to “damages”, the indemnification referred to in par (b) is also so limited, or whether it extends to costs. However, it is not necessary in order to resolve this ground to express a concluded view on the effect of s 32A, especially in its operation to persons found to be concurrent wrongdoers in litigation in another State. Rodriguez submitted, without contradiction, that the primary judge had not been referred to the section.

770. The source of power is the broadly worded s 98 of the Civil Procedure Act 2005 (NSW), which gives the court “full power to determine by whom, to whom and to what extent costs are to be paid”.

771. Seqwater had two objections against the order made. One was purely formal. It was that a declaration of right could not be made in the form it was. The power was confined to granting a declaration of existing legal rights or legal rights which will come into existence upon the happening of future events. However, Seqwater accepted that s 98(1)(b) conferred a power to make orders that the defendants pay certain proportions of Rodriguez’ costs. Examples may be seen in the form of the orders made in Voli v Inglewood Shire Council ^[255] and Soblusky v Egan. ^[256]

     255. (1963) 110 CLR 74 at 101; [1963] HCA 15.

     256. (1960) 103 CLR 215 at 239; [1960] HCA 9.

772. Seqwater’s substantive point was that the appropriate starting point was not the apportionment of liability for damages between the three defendants, which was not relevant to an assessment of the defendants’ respective responsibilities for the plaintiff’s incurring of legal costs. The point was illustrated by a simple example: suppose two defendants were found liable for 75% and 25% of a plaintiff’s damages, but the former had only disputed quantum while the latter had disputed both liability and quantum. Seqwater submitted that it would be neither just nor reasonable to apportion responsibility for the plaintiff’s costs in accordance with the apportionment for damages. In the proceedings at first instance, it was submitted that the three defendants had in effect made common cause and the starting point for the exercise of the costs discretion was not the apportionment reached at the end of the trial, but the separate liability for the costs of the proceedings which should be divided equally. Seqwater also maintained that that position was supported by contribution in equity in respect of the co-ordinate liability created by the joint and several costs order.

773. It is to be borne steadily in mind that the primary judge merely took the apportionment of liability for damages as a starting point for the exercise of the costs discretion. His Honour was not persuaded that Seqwater had established a sufficiently strong basis to depart from it. That is an approach reflected in many cases. For example, in Chapman v Hearse,^[257] the order which was ultimately confirmed by the High Court was that Mr Hearse was entitled to contribution from Mr Chapman in the amount of one-fourth of the damages and costs he was obliged to pay following the death of Dr Cherry.

     257. (1961) 106 CLR 112; [1961] HCA 46.

774. Indeed, Seqwater’s example proves too much. If a defendant who had conceded liability but disputed quantum was ordered to pay 75% of the plaintiff’s costs, while the other defendant who had contested liability and quantum was only ordered to pay 25% of the plaintiff’s costs, on the basis that the first defendant was ultimately liable to pay 75% of the damages and nothing more, then there would be House v The King ^[258] error. A material consideration to the exercise of the costs discretion would be the fact that the entirety of the plaintiff’s costs incurred in relation to liability were attributable to the stance taken by the second defendant. But that proves merely that the damages ordered against multiple defendants can only be an appropriate starting point for the exercise of the discretion as to costs. The primary judge considered Seqwater’s submission, but determined not to depart from that starting point. That approach does not disclose appealable error. The fact that his Honour relied on an additional source of power which was not available did not vitiate the exercise of discretion.

     258. (1936) 55 CLR 499 at 505; [1936] HCA 40.

775. For those reasons, had this ground arisen, we would have recast the orders in the light of Seqwater’s objection to their form, but not interfered with their substance.

1. Costs – generally

1. Costs of trial

776. Because Seqwater has succeeded in setting aside the judgment against it, the order as to costs of the trial, which followed the event, must also be set aside. As to the appropriate substitute order, this Court does not have before it sufficient information to reassess the costs of the trial, which involved numerous issues and a multiplicity of separate judgments over several years. There would be merit in returning this issue to the mediator who has been involved with the case in the past. However, this is a matter for the parties to consider. It may be that agreement can be reached in any event. The Court will not make orders as to the costs of the trial at this stage, but will grant leave to the parties to seek further orders, such leave to be exercised within 28 days, subject to further order of a judge of the Court.

777. It should be stated expressly that the Court does not intend itself to resolve a dispute as to the proper order for the costs of the trial, in the light of the substantive orders made on the appeal. If the matter cannot be resolved extra-curially, it will be remitted to the primary judge: an order to that effect will be made.

1. Costs of appeal

778. Seqwater, having been successful in setting aside the orders made at trial with respect to its liability, is entitled to its costs of the appeal. Its success turned on the primary ground on the appeal concerning the engagement and application of s 36(2) of the Civil Liability Act. It also succeeded on various grounds concerning the proper construction of the Manual, with the result that all findings of breach of duty have been reversed.

779. Although it has been unsuccessful with respect to specific grounds, these do not warrant a reduction in the award of costs.

1. Orders

780. The Court makes the following orders:

(A)   In matter 2020/189434 (Seqwater’s appeal) –

1. In relation to orders relating to group members not the subject of final orders, grant Seqwater leave to appeal.

2. Allow the appeal and

1. set aside order (3) made on 29 May 2020 in Rodriguez (No 23) and orders (3)-(6) made on 7 May 2021 in Rodriguez (No 29);

2. set aside order (2) made on 29 May 2020 in Rodriguez (No 23) and order (1) made on 7 May 2021 in Rodriguez (No 29) in so far as the answers to the common questions relate to Seqwater or its employees;

3. set aside orders 1-4 made on 28 October 2020 in Rodriguez (No 24), in so far as they relate to costs payable by Seqwater, and remit to the primary judge any outstanding issue as to the costs of the proceeding in the Common Law Division in matter 2014/200854 involving Seqwater.

3. Subject to the remittal provided in order (2)(c), dismiss the proceedings in the Common Law Division in matter 2014/200854 as against Seqwater.

4. Order that the first respondent (Rodriguez & Sons Pty Ltd) pay the appellant's costs of the appeal.

(B)   In matter 2020/189716 (Rodriguez’ application for leave to appeal) –

Dismiss the summons seeking leave to appeal (with no order as to costs).

**********

APPENDIX A

1. WIVENHOE DAM FLOOD OPERATIONS

8.1    Introduction

Wivenhoe Dam is capable of being operated in a number of ways to reduce flooding in the Brisbane River downstream of the dam, depending on the origin, magnitude and spatial extent of the flood. Maximum overall flood mitigation effect will be achieved by operating Wivenhoe Dam in conjunction with Somerset Dam.

The reservoir volume above FSL of EL 67.0 is available as temporary flood storage. How much of the available flood storage compartment is utilised, will depend on the initial reservoir level below FSL, the magnitude of the flood being regulated and the procedures adopted.

Splityard Creek Dam is part of the overall Wivenhoe Area Project and it forms the upper pumped storage for hydro power generation. Splityard Creek Dam impounds a volume of 28,700 ML at FSL (EL 166.5). This volume can be emptied into Lake Wivenhoe within 12 hours and this water can affect the level in Wivenhoe Dam by up to 300mm when Wivenhoe Dam is close to FSL. Operation of the power station and release of water from Splityard Creek Dam to Lake Wivenhoe is outside the control of Seqwater, but should be considered when assessing the various trigger levels of Wivenhoe Dam.

8.2    Flood Release Infrastructure

Radial Gates and an Auxiliary Spillway are the primary infrastructure used to release water during flood events at Wivenhoe Dam. The arrangement of the Radial Gates is shown in the diagram below:

In addition to the five radial gates, the auxiliary spillway was constructed in 2005 as part of an upgrade to improve flood adequacy of this storage. The auxiliary spillway consists of a three bay fuse plug spillway at the right abutment. In association with other works constructed at the dam, this gives the dam crest flood an AEP of approximately 1 in 100,000. Another one bay fuse plug spillway may be constructed at Saddle Dam Two in the future.

Pertinent information about the auxiliary spillway, including the initiation level for the specific bays is given in the following table.

Auxiliary Spillway - Fuse Plug Details table - text version (13866, docx)

The arrangement of the Auxiliary Spillway is shown in the diagram below.

8.3    Initial Flood Control Action

Once a Flood Event is declared, an assessment is to be made of the magnitude of the Flood Event, including:

•    A prediction of the maximum storage levels in Wivenhoe and Somerset Dams.

•    A prediction of the peak flow rate at the Lowood Gauge excluding Wivenhoe Dam releases.

•    A prediction of the peak flow rate at the Moggill Gauge excluding Wivenhoe Dam releases.

The spillway gates are not to be opened for flood control purposes prior to the reservoir level exceeding EL 67.25.

8.4    Flood Operations Strategies

There are four strategies (W1 to W4) used when operating Wivenhoe Dam during a flood event as outlined below. These strategies are based on the Flood Objectives of this manual. As outlined in Section 3, the objectives, listed in descending order of importance, are as follows:

•    Ensure the structural safety of the dams;

•    Provide optimum protection of urbanised areas from inundation;

•    Minimise disruption to rural life in the valleys of the Brisbane and Stanley Rivers;

•    Retain the storage at Full Supply Level at the conclusion of the Flood Event.

•    Minimise impacts to riparian flora and fauna during the drain down phase of the Flood Event.

Within any strategy, consideration is always given to these objectives in this order, when making decisions on dam releases.

The strategy chosen at any point in time will depend on the actual levels in the dams and the following predictions, which are to be made using the best forecast rainfall and stream flow information available at the time:

•    Maximum storage levels in Wivenhoe and Somerset Dams.

•    Peak flow rate at the Lowood Gauge (excluding Wivenhoe Dam releases).

•    Peak flow rate at the Moggill Gauge (excluding Wivenhoe Dam releases).

Strategies are likely to change during a flood event as forecasts change and rain is received in the catchments. It is not possible to predict the range of strategies that will be used during the course of a flood event at the commencement of the event. Strategies are changed in response to changing rainfall forecasts and stream flow conditions to maximise the flood mitigation benefits of the dams.

When determining dam outflows within all strategies, peak outflow should generally not exceed peak inflow. A flowchart showing how best to select the appropriate strategy to use at any point in time is shown below:

Strategy W1 table - text version (14093, docx)

The intent of Strategy W1 is to not to submerge the bridges downstream of the dam prematurely (see Appendix I). The limiting condition for Strategy W1 is the submergence of Mt Crosby Weir Bridge that occurs at approximately 1,900 m³/s.

For situations where flood rains are occurring on the catchment upstream of Wivenhoe Dam and only minor rainfall is occurring downstream of the dam, releases are to be regulated to limit, as much as appropriate in the circumstances, downstream flooding.

The following strategies require a great deal of control over releases and knowledge of discharges from Lockyer Creek. In general, the releases from Wivenhoe Dam are controlled such that the combined flow from Lockyer Creek and Wivenhoe Dam is less than the limiting values to delay the submergence of particular bridges. The diagram above shows the location of the impacted bridges and the approximate river flow rate at which they are closed to traffic.

Strategy W1A    Twin Bridges, Savages Crossing and Colleges Crossing

Lake Level greater than 67.25 m AHD

[Maximum Release 110 m³/s]

Firstly, endeavour to maintain Twin Bridges trafficable by limiting the combined flows from Wivenhoe Dam and Lockyer Creek to a maximum of 50 m³/s.

Once Twin Bridges is closed to traffic, endeavour to maintain Savages Crossing trafficable by limiting the combined flows from Wivenhoe Dam and Lockyer Creek to a maximum of 110 m³/s.

Once Savages Crossing is closed to traffic, endeavour to maintain College’s Crossing trafficable by limiting the combined flows from Wivenhoe Dam and Lockyer Creek to a maximum of 175 m³/s. Note that College’s Crossing can be impacted by tidal influences.

When the flood event subsides, all gates are to be closed when the dam achieves FSL in accordance with Section 8.5.

Strategy W1B    College’s Crossing and Burtons Bridge

Lake Level greater than 67.50 m AHD

[Maximum Release 380 m³/s]

No consideration is given to maintaining Twin Bridges or Savages Crossing open.

Endeavour to maintain College’s Crossing trafficable by limiting the combined flows from Wivenhoe Dam and Lockyer Creek to a maximum of 175 m³/s.

Once College’s Crossing is closed to traffic, endeavour to maintain Burtons Bridge trafficable by limiting the combined flows from Wivenhoe Dam and Lockyer Creek to a maximum of 430 m³/s.

Strategy W1C    Burtons Bridge and Kholo Bridge

Lake Level greater than 67.75 m AHD

[Maximum Release 500 m³/s]

No consideration is given to maintaining College’s Crossing open.

Endeavour to maintain Burtons Bridge trafficable by limiting the combined flows from Wivenhoe Dam and Lockyer Creek to a maximum of 430 m³/s.

Once Burtons Bridge is closed to traffic, endeavour to maintain Kholo Bridge trafficable by limiting the combined flows from Wivenhoe Dam and Lockyer Creek to a maximum of 550 m³/s.

Strategy W1D    Kholo Bridge and Mt Crosby Weir Bridge

Lake Level greater than 68.00 m AHD

[Maximum Release 1900 m³/s]

No consideration is given to maintaining Burtons Bridge open.

Endeavour to maintain Kholo Bridge trafficable by limiting the combined flows from Wivenhoe Dam and Lockyer Creek to a maximum of 550 m³/s.

Once Kholo Bridge is closed to traffic, endeavour to maintain Mt Crosby Weir Bridge trafficable by limiting the combined flows from Wivenhoe Dam and Lockyer Creek to a maximum of 1900 m³/s.

Strategy W1E    Mt Crosby Weir Bridge and Fernvale Bridge

Lake Level greater than 68.25 m AHD

[Maximum Release 1900 m³/s]

No consideration is given to maintaining Kholo Bridge open.

Endeavour to maintain Mt Crosby Weir Bridge trafficable by limiting the combined flows from Wivenhoe Dam and Lockyer Creek to a maximum of 1900 m³/s.

Once Mt Crosby Weir Bridge is closed to traffic, endeavour to maintain Fernvale Bridge trafficable by limiting the combined flows from Wivenhoe Dam and Lockyer Creek to a maximum of 2000 m³/s.

If the level reaches EL 68.5 m AHD in Wivenhoe Dam, switch to Strategy W2 or W3 as appropriate.

Strategy W2 table - text version (14267, docx)

The intent of Strategy W2 is limit the flow in the Brisbane River to less than the naturally occurring peaks at Lowood and Moggill, while remaining within the upper limit of nondamaging floods at Lowood (3,500 m³/s). In these instances, the combined peak river flows should not exceed those shown in the following table:

Strategy W2 Target Maximum Flow table - text version (14061, docx)

Strategy W3 table - text version (14183, docx) 

The intent of Strategy W3 is to limit the flow in the Brisbane River at Moggill to less than 4000 m³/s, noting that 4000 m³/s at Moggill is the upper limit of non-damaging floods downstream. The combined peak river flow targets for Strategy W3 are shown in the following table. In relation to these targets, it should be noted that depending on natural flows from the Lockyer and Bremer catchments, it may not be possible to limit the flow at Moggill to below 4000 m3/s. In these instances, the flow at Moggill is to be kept as low as possible.

Strategy W3 Target Maximum Flow table - text version (12780, docx)

Strategy W4 table - text version (14118, docx)

The intent of Strategy W4 is to ensure the safety of the dam while limiting downstream impacts as much as possible.

This strategy normally comes into effect when the water level in Wivenhoe Dam reaches 74.0 m AHD. However the Senior Flood Operations Engineer may seek to invoke the discretionary powers of Section 2.8 if earlier commencement is able to prevent triggering of a fuse plug.

Under Strategy W4 the release rate is increased as the safety of the dam becomes the priority. Opening of the gates is to occur generally in accordance with the requirements of Section 8.6, until the storage level of Wivenhoe Dam begins to fall.

There are no restrictions on gate opening increments or gate operating frequency once the storage level exceeds 74.0 AHD, as the safety of the dam is of primary concern at these storage levels. However the impact of rapidly increasing discharge from Wivenhoe Dam on downstream reaches should be considered when determining gate opening sequences.

Strategy W4A – No Fuse Plug Initiation Expected

Lake Level between 74.0 and 75.5 m AHD

[No Maximum Release]

Strategy 4A applies while all indications of the peak flood level in Wivenhoe Dam are that it will be insufficient to trigger operation of the first bay of the fuse plug by reaching 75.5 m AHD.

Gate openings are generally to occur at the minimum intervals and sequences as specified in Section 8.6 until the storage level of Wivenhoe Dam begins to fall. However, to protect the safety of the dam, minimum opening intervals can be reduced and gate opening sequences can be modified.

Strategy W4B – Fuse Plug Initiation Possible

Lake Level greater than 75.5 m AHD

[No Maximum Release]

Strategy W4B applies once indications are the peak flood level in Wivenhoe Dam may exceed EL75.5 and trigger the fuse plug under normal operations. Two scenarios are possible under this strategy. The first scenario is where it may be possible to prevent fuse plug initiation by early opening of the gates. The second scenario is where fuse plug initiation cannot be avoided. The actions associated with these scenarios are contained in the following table:

W4B Fuse Plug Initiation Possible table - text version (14471, docx)

8.5 Gate Closing Strategies

In general, gate closing commences when the level in Wivenhoe Dam begins to fall and is generally to occur in the reverse order to opening. The final gate closure should occur when the lake level has returned to Full Supply Level. The following requirements must be considered when determining gate closure sequences:

•    Where possible, total releases during closure should not produce greater flood levels downstream than occurred during the flood event.

•    The maximum discharge from the dam during closure should generally be less than the peak inflow into Wivenhoe Dam experienced during the event. The discharge from Wivenhoe Dam includes discharge from triggered fuse plugs, gates, regulator cone dispersion valve and hydro release.

•    If, at the time the lake level in Wivenhoe Dam begins to fall, the combined flow at Lowood is in excess of 3,500 m³/s then the combined flow at Lowood is to be reduced to 3,500 m3/s as quickly as practicable.

•    The aim should always be to empty stored floodwaters stored above EL 67.0m within seven days after the flood peak has passed through the dams. However, provided a favourable weather outlook is available, this requirement can be relaxed for the volume between EL 67.0m and EL 67.5m, to obtain positive environmental outcomes.

•    If the flood storage compartments of Wivenhoe Dam and Somerset Dam can be emptied within seven days, the maximum flow in the Brisbane River at Lowood should not exceed 3,500 m³/s.

•    To minimise the stranding of fish downstream of the dam, final closure sequences should consider Seqwater policies relating to fish protection at the dam.

There may be a need to take into account base flow when determining final gate closure. This may mean that the lake level temporarily falls below Full Supply Level to provide for a full dam at the end of the Flood Event.

8.6 Gate Operation Sequences

Radial Gate Opening Operations

When dam outflows are less than 4,000 m³/s, rapid opening of the radial gates can cause undesirable rapid rises in downstream river levels. Accordingly, when dam outflows are less than 4,000 m³/s, the aim in opening radial gates is to operate the gates one at a time at intervals that will minimise adverse impacts on the river system. The table below shows the target minimum interval for gate operations in these circumstances. This target interval can be reduced if the gates are at risk of being overtopped or the safety of the dam is at risk.

Target Minimum Interval Radial Gate Opening table - text version(12905, docx)

When dam outflows exceed 4,000 m3/s, the impact of rapid gate openings on downstream water levels is reduced due to the already elevated river levels. Under these circumstances, the safety of the dam will generally be of primary concern and therefore there are no minimum gate opening intervals in these circumstances.

Under extreme circumstances, the mechanical capability of the radial gate operating system provides the facility to open each radial gate more than five metres within a one hour period. Accordingly, unless a mechanical breakdown is experienced, physical gate opening capability in unlikely to be a constraint in meeting projected outflow targets.

Radial Gate Closing Operations

When dam outflows are less than 4,000 m³/s, rapid closure of the radial gates can cause adverse impacts to the river system. Accordingly, when dam outflows are less than 4,000 m³/s, the aim in closing radial gates is to operate the gates one at a time at an interval that will minimise adverse impacts on the river system as outlined in the table below.

Target Minimum Interval Radial Gate Closure table - text version (12774, docx)

When dam outflows exceed 4,000 m3/s, the impact of rapid gate closings is reduced due to the already elevated river levels. However, given that the safety of the dam is unlikely to be at risk if decisions are made to close radial gates, the target of operating the gates one at a time in accordance with the time interval shown in the above table remains.

Rapid closure of radial gates is permissible however, when there is a requirement to preserve storage or to reduce downstream flooding. When determining gate closure sequences, consideration should also be given to following the calculated natural recession of the flood in the river to aim to ensure that the recession impacts are not greater than those that would have been experienced had the dam not been constructed.

Protection of the Spillway Walls

The flip bucket spillway is designed to control the discharge from the reservoir and to dissipate the energy of the discharge. The flip throws the discharge clear of the concrete spillway structures and into a plunge pool where the energy is dissipated by turbulence. Under nonsymmetric flow conditions or when Gates 1 and 5 are not operating, the discharge jet may impinge on the walls of the plunge pool. As these walls have been excavated into erodible sandstone rock, this impingement may cause non-predictable erosion. Upstream migration of this erosion is to be avoided. This can be achieved by operating Gates 1 and 5 to deflect the discharge away from the walls of the plunge pool.

Therefore in operating the spillway, the principles to be observed in order of priority are:

1. The discharge jet into the plunge pool is not to impinge on the right or left walls of the plunge pool.

2. The flow in the spillway is to be symmetrical.

Normal Gate Operation Sequences

Under normal operation, only one gate is to be opened at any one time and the sequences shown in the table below are to be adopted. Generally gates are operated in the order of 3,2,4,1,5. Variations are allowed at any time to protect the structural safety of the dam.

It should also be noted that:

•    Gates are numbered 1 to 5 from the left bank looking downstream

•    Flow in spillway to be as symmetrical as possible.

Radial Gate Opening Sequences - text version (35675, docx)

During the initial opening or final closure sequences of gate operations it is permissible to replace the discharge through a gate by the immediate opening of a regulator valve (or the reverse operation). This allows for greater control of low flows.

Gate Failure or Malfunction Procedures

Gate operating procedures in the event of equipment failure are contained in Appendix G. If one or more gates are inoperable during the course of the flood event, the gate openings of the remaining gates are to be adjusted to provide the required discharge from the dam. These adjustments should ensure that:

•    The impact of the flow on the sidewalls of the plunge pool should be minimised, and

•    The flow in the spillway is as symmetrical as practicable.

Radial Gate Turbulence Considerations

Unless in the process of lifting the gates clear of the flow, the bottom edge of the radial gates must always be at least 500 millimetres below the release flow surface. Having the bottom edge of the gates closer to the release flow surface than 500 millimetres may cause unusual turbulence that could adversely impact on the gates. This procedure has never been undertaken in practice and should be observed closely when being undertaken. Variations to the procedure are allowed to protect the structural safety of the dam.

Lowering Radial Gates that have been lifted Clear of the Release Flow

When lowering radial gates that have been lifted clear of the release flow, the bottom edge of the gates must be lowered at least 500 millimetres into the flow. Lowering gates into the release flow less than this amount may cause unusual turbulence that could adversely impact on the gates. This procedure has never been undertaken in practice and should be observed closely when being undertaken. Variations to the procedure are allowed to protect the structural safety of the dam.

8.7    Modification to Flood Operating Procedures if a Fuse Plug Triggers

Where the operation of a fuse plug spillway bay has been triggered, the flood operation procedures are to be modified such that:

•    The discharge from the triggered fuse plug is to be taken into account when determining total flood releases from the dam;

•    The gates are to be operated, to the extent possible, so that the same discharge restrictions apply as would have if the fuse plug embankment was intact.

8.8    Modification to Flood Operating Procedures if a subsequent flood event occurs prior to the reconstruction of Triggered Fuse Plugs

Where the operation of any or all of the fuse plug spillway bays has been triggered and a flood event occurs before the fuse plug can be reinstated, the flood operation procedures are to be modified such that:

•    The discharge from the triggered fuse plug is to be taken into account when determining total flood releases from the dam;

•    The gates are to be operated, to the extent possible, so that the same discharge restrictions apply as would have if the fuse plug embankment was intact.

•    Discharge from the Auxiliary Spillway will occur before the Gate Trigger Level of EL 67.25 m AHD. This flow should be taken into account when applying the flood operation strategies relevant to the low level bridge crossings.

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Endnotes

Decision last updated: 08 September 2021