a Report Dams and Weirs Capital Works Program Dams and 27 May2014 Weirs Capital 42627348/01/01 Works Prepared for: Program Seqwater Prepared by URS Australia Pty Ltd AUSTRALIA DOCUMENT PRODUCTION / APPROVAL RECORD Issue No. Name Signature Date Position Title Prepared by Mike Phillips 27 May 2014 Senior Associate 27 May 2014 Checked by Christopher Dann Senior Principal 27 May 2014 Approved by Christopher Dann Senior Principal Report Name: DOCUMENT REVISION RECORD Dams and Weirs Capital Works Program Issue No. Date Details of Revisions Report No. 42627348/01/01 Status: Final Client Contact Details: Seqwater Issued by: URS Australia Pty Ltd Level 17, 240 Queen Street Brisbane, QLD 4000 GPO Box 302, QLD 4001 Australia T: +61 7 3243 2111 F: +61 7 3243 2199 © Document copyright of URS Australia Pty Limited. 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Storage of this electronic information should at a minimum comply with the requirements of the Electronic Transactions Act 2000 (Cth). 42627348/01/01 J:\BNE\42627348\5 Works\42627348 - Seqwater Dams Capital Works Program.docx TABLE OF CONTENTS 1 INTRODUCTION ............................................................................................................................. 2 2 BACKGROUND .............................................................................................................................. 3 2.1 Seqwater Dam Safety Management Program ............................................................................. 3 2.2 Referable Dams Portfolio Risk Assessment .............................................................................. 3 3 DAMS CAPITAL WORKS PROGRAM .......................................................................................... 7 3.1 Methodology .................................................................................................................................. 7 3.2 Investment Drivers ........................................................................................................................ 7 3.2.1 Improvements ................................................................................................................................ 7 3.2.2 Compliance .................................................................................................................................... 7 3.2.3 Growth ............................................................................................................................................ 7 3.2.4 Flood Mitigation............................................................................................................................. 7 3.2.5 Expected Future Requirements ................................................................................................... 8 4 AUSTRALIAN DAM SAFETY REGULATION ............................................................................... 9 4.1 Queensland Dam Safety Regulation - Regulatory Framework ................................................. 9 4.2 Australian practice and industry ............................................................................................... 10 5 AUSTRALIA AND INTERNATIONAL DAM SAFETY PRACTICE .............................................. 11 5.1 State Water, NSW ........................................................................................................................ 11 5.2 Goulburn Murray Water, VIC ...................................................................................................... 11 5.3 Melbourne Water, VIC ................................................................................................................. 11 5.4 U.S. Dams Practice ..................................................................................................................... 12 6 SEQWATER REFERABLE DAMS PRA ...................................................................................... 13 7 MAJOR INVESTMENTS ............................................................................................................... 15 7.1 Discussion ................................................................................................................................... 17 8 REFERENCES .............................................................................................................................. 19 9 LIMITATIONS ............................................................................................................................... 20 TABLES Table 7-1 Summary of key Water Storage projects sorted by Commission Year ..................................... 15 FIGURES Figure 2-1 Seqwater Existing Portfolio of Dams F-N Curve ......................................................................... 5 Figure 2-2 Seqwater Existing Portfolio of Dams - Individual Risk ................................................................ 6 Figure 7-1 Expenditure profile for Water Storage Assets over 13 years .................................................... 16 42627348/01/01 1 INTRODUCTION URS Australia Pty Ltd (URS) was engaged by Seqwater to develop a Capital Works Program to deliver on the Dam Safety Risk Management Strategy developed as an output to the Portfolio Risk Assessment that URS completed for Seqwater’s 26 referable dams and Mt Crosby Weir. Seqwater’s portfolio of 26 water storage assets fulfill multiple functions, including: • the storage of raw water to be treated to drinking water quality • the storage of raw water for irrigation and environmental purposes • flood mitigation • hydro power generation • recreation The purpose of the Capital Works Program is to provide Seqwater with an overview of the required upgrades identified under the organisations Dam Safety Management Program. These have been prioritised as part of the outcomes of the Seqwater Referable Dam Portfolio Risk Assessment including the development of a capital program for the next 13 years, to reduce dam safety risks as set out in the Dam Safety Management Strategy. The Dams Asset Portfolio Capital Works Program is intended to be used as a source document for development of the Asset Portfolio Master Plan which will be a core part of Seqwater’s economic regulation review submission. The primary driver for the Dams Asset Portfolio Capital Works Program is to satisfy regulatory compliance, namely dam safety and to manage Seqwater’s business risks associated with ownership of a large portfolio of dams. 42627348/01/01 2 2 BACKGROUND 2.1 Seqwater Dam Safety Management Program In 2008, Seqwater assumed ownership and responsibility for the operation of 26 referable dams from various Southeast Queensland councils, the South East Queensland Water Corporation, Aquagen and SunWater. Some of these dams are more than 100 years in age with varying structural condition. As required by the Queensland Guidelines on Dam Safety Management (2002), a Dam Safety Management Program was prepared and implemented by Seqwater. Since 2008, Seqwater has embarked on an investigation and review program to better understand the key risks within their dam portfolio and has undertaken upgrade works and repairs to a number of dam assets to reduce their risk profiles in the short term. As part of the Seqwater Dam Safety Management Program, a program of investigations has been undertaken since 2009 to assess the compliance of the referable dams with the DEWS Guidelines on Acceptable Flood Capacity (AFC), initially published in 2007 and revised in 2013. This program has identified that 12 of the 26 referable dams owned and operated by Seqwater require flood capacity upgrades to comply with the Guidelines. In parallel with the AFC assessment program, the Seqwater Dam Safety Management Program has also identified a number of other dam safety issues relating to earthquake and piping. Recognising that the fall-back method specified by the AFC guidelines may result in a higher design requirement and consequent higher cost of a dam upgrade, Seqwater has adopted the alternative risk assessment procedure (incorporating ALARP). The risk assessment procedure also provides more detail to allow the prioritisation of the various upgrades. This procedure requires that the risk assessment be carried out in accordance the following guidelines: • Australian National Committee on Large Dams (ANCOLD) Guidelines on Selection of Acceptable Flood Capacity for Dams (ANCOLD, 2000) • ANCOLD Guidelines on Assessment of the Consequences of Dam Failure (ANCOLD, 2000) • DEWS Guidelines for Failure Impact Assessment of Water Dams (DEWS 2012) (for the dam breach sizes and timings and the estimation of population at risk); • ANCOLD Guidelines on Risk Assessment (ANCOLD, 2003) (with particular attention to the quantitative studies at advanced or very advanced levels). 2.2 Referable Dams Portfolio Risk Assessment