Attached as Exhibit B-2 is BC Hydro's presentation from the Stave Falls Spillway Gates Project Workshop held on January 18, 2010.

Transcription

1 BChydro CD FOR GEf\lE IONS B-2 Joanna Sofield Chief Regulatory Officer Phone: (604) Fax: (604) January 19, 2010 Ms. Erica M. Hamilton Commission Secretary British Columbia Utilities Commission Sixth Floor Howe Street Vancouver, BC V6Z 2N3 Dear Ms. Hamilton: RE: Project No British Columbia Utilities Commission (BCUC) British Columbia Hydro and Power Authority (BC Hydro) Stave Falls Spillway Gates Replacement Project Attached as Exhibit B-2 is BC Hydro's presentation from the Stave Falls Spillway Gates Project Workshop held on January 18, For further information, please contact Lyle McClelland at Yours sincerely, Joanna Sofield Chief Regulatory Officer Enclosure c. BCUC Project No Stave Falls Spillway Gates Project' Registered Distribution List. Intervenor British Co1umbia Hydro and Power Authority, 333 Dunsmuir Street, Vancouver BC V6B 5R3

2 Stave Falls Spillway Gates Replacement Project Workshop January 18, 2010

3 Introduction BCUC Order Introduction to Spillway Gate Systems Spillway Gates Program Facility Description Need for the Project Project Description Alternatives Considered Project Costs Project Schedule Project Effects (Rate Impact, Environmental & Social) Project Risks Project Consultation Conclusions 2

4 BCUC Order 44.2 (3)(a) of the Utilities Commission Act (the UCA) BCUC acceptance that the expenditures for Stave Falls Spillway Gates Replacement Project are in the public interest Considerations: > the Government s energy objectives; > BC Hydro s most recent Long-Term Resource Plan; > whether the expenditure schedule is consistent with sections and of the UCA in respect of electricity self sufficiency and clean and renewable resources; and > the interests of present and future ratepayers. Project Costs: > Expected Cost: $61.5M > Authorized Cost: $70.6M BCUC Order 3

5 Functions of a Gate Water barrier Part of the dam Don t open without demand Flood discharge Open on demand Close on demand Introduction to Spillway Gate Systems 4

6 Spillway Gate Operations Operated to ensure: safe release of excess flows or floods to prevent overtopping essential to ensure safe dam operation Other Operations : proper regulation of water flow downstream rapid release of water for emergency or precautionary reservoir drawdown post catastrophe operational requirement Introduction to Spillway Gate Systems 5

7 Emergency Reservoir Drawdown Zipingpu Dam, China, 2005 Concrete Face Rockfill Dam Damage to upstream concrete face slabs Reservoir was immediately lowered Declared structurally stable and safe Introduction to Spillway Gate Systems 6

8 Precautionary Reservoir Drawdown W.A.C. Bennett Dam, 1996 Introduction to Spillway Gate Systems

9 Post-Catastrophe Operational Requirement Sayano Hydroelectric Plant, Russia, August 17, MW Facility Unreliable backup power Overtopping potential in 2 days Just made it in time. Introduction to Spillway Gate Systems 8

10 Examples of Spillway Gate Failures Structural Failures: Folsom Dam, California Commissioned in 1956 Failed, July 1995 Trunnion friction not included in design; not checked Introduction to Spillway Gate Systems 9

11 Examples of Spillway Gate Failures Operational Failures: Manatee Dam, Florida Spillway Gate jammed in half-open position in July homes evacuated Workers managed to open Gate before dam overtopped Introduction to Spillway Gate Systems 10

12 Examples of Spillway Gate Failures Tirlyan Dam, Russia August, 1994 Spillway Gate jammed in half-open position Introduction to Spillway Gate Systems 11

13 Examples of Spillway Gate Failures Catastrophic Embankment failure Introduction to Spillway Gate Systems 12

14 Examples of Spillway Gate Failures caused about 20 deaths significant property destruction Introduction to Spillway Gate Systems 13

15 Spillway Gates Program In 2005, BC Hydro began an initiative to improve equipment and procedures to ensure reliable operation of spillway gate systems Equipment Power supplies Control systems Testing and Maintenance, Management 2005 Condition evaluated against a set of design and operation principles Spillway Gates Program 14

16 Reliability Principles and ALARP Formalized and adopted in 2006, based on work by external consultant on spillway gate systems New concept to hydroelectric industry, but common practice in other high-hazard industries System should operate on demand with less than a 1 in 1000 chance of failure Reduce risk to As Low As Reasonably Practicable Spillway Gates Program 15

17 Prioritization of Sites All 22 sites with spillways were evaluated and prioritized based upon: Current physical condition of equipment Availability of alternative ways to control water Frequency of use Current reliability Possibility of interim risk management methods Consequences of failure Spillway Gates Program 16

18 Summary Spillway Gate Systems are: Critical Infrastructure for Public Safety Cannot be taken for granted Spillway Gates Program 17

19 Stave Falls Facility Stave Falls Facility Stave Falls Facility is located about 16 kilometres northwest of the town of Mission, on the Stave River. Facility Description 18

20 Stave Falls Facility Facility Description 19

21 Stave Falls Facility Originally constructed between 1910 and 1927 Facility includes Stave Reservoir, Stave Falls Generating Station, main dam, two intake structures and the Blind Slough Dam (provides flood discharge control) Part of the Alouette-Stave Falls Hydroelectric System which consists of three facilities: Alouette (upstream), Stave Falls, and Ruskin (downstream) Operation of Stave Falls and Ruskin facilities closely coordinated in order to maximize use of water and ensure water licence compliance Facility Description 20

22 Stave Falls Facility (Blind Slough Dam) Blind Slough Dam constructed to impound Stave Reservoir and to provide controlled release of water during flood conditions Passing of water to the spillway is controlled via 4 radial gates and 10 vertical gates When all 14 gates are fully open, they allow safe passage of the most severe inflow flood The four radial gates provide about 45% of the overall discharge capacity and are the preferred means of passing water through Blind Slough because they allow BC Hydro to more precisely control water releases Facility Description 21

23 Stave Falls Facility (Blind Slough Dam) Longitudinal view of Blind Slough Dam Spillway Gates Facility Description 22

24 Stave Falls Facility (Blind Slough Dam) Radial Gate (Side Profile) Vertical Gate (Side Profile) Facility Description 23

25 Operating History The Blind Slough Dam s radial gates were originally installed around 1923 BC Hydro refurbished the radial gates in 1997/1998 in order to extend their life by about 15 years; refurbishment consisted of replacing corroded components and repainting of the gates New radial gates are scheduled be installed in 2011 & 2012; about 14 years after the 1997/1998 refurbishment Radial Gate ropes replaced in 2007 as a result of rope failure Facility Description 24

26 Key Concerns 1. Installed in the 1920s, the four radial gates and hoists are at end-of-life and do not meet current seismic criteria. 2. Existing design deficiencies could lead to a common cause failure which could result in all spillway gates becoming inoperable. Consequently, the Spillway Gate System cannot currently be relied upon to operate effectively during flood conditions Need for the Project 25

27 Key Concerns Hoist System Portion of Radial Gate Need for the Project 26

28 Consequences of Failure Dam Overtopping If the spillway gates become inoperable during flood conditions, the Stave Falls Dam and Blind Slough Dam could be overtopped by 1 to 2 metres depth of water flow This level of overtopping would result in a catastrophic dam failure at both the Stave Falls facility and the downstream Ruskin facility Catastrophic dam failures have the potential to result in loss of life and significant financial and environmental damage Need for the Project 27

29 Consequences of Failure Other Failure Modes Given the current condition of the Spillway Gates system, the gates could experience the following failure modes: gates not opening when commanded, gates opening when not commanded, gates over-travelling (moving beyond the intended position) Failures of this type could lead to serious public and worker safety and environmental impacts Need for the Project 28

30 Project Scope This project focuses on the upgrade of the radial gates and hoists and does not include the 10 vertical gates The radial gates are more critical because: The radial gates provide quick push button operation The radial gates can more easily be designed and Upgraded to meet a high level of reliability The radial gates are required to draw down the reservoir after a seismic event Tighter hydraulic control Project Description 29

31 Project Scope The Project will address: Replacement of radial gates and radial gate hoists, Installation of new seals, rollers and maintenance access for radial gates, and Upgrades to electrical power supply system, protection and controls. Project Description 30

32 Alternatives Alternatives that were considered but found to be unacceptable include: Doing nothing Deferring capital improvements A component-by-component review of the Spillway Gate System was then carried out to determine whether components should be replaced or refurbished Alternatives Considered 31

33 Alternatives Replacement Selected Replacement was selected over refurbishment due to the following factors: Age and condition of components (installed in 1920 s), Levels of corrosion for certain components, Inherent design deficiencies that would not be addressed through refurbishment Alternatives Considered 32

34 Project Cost PROJECT COMPONENT PROJECT COST ($ Millions) Identification Phase (Direct) 0.1 Definition Phase (Direct) 3.3 Capital Overhead and IDC 1.0 Total Identification and Definition Phase Cost 4.4 Direct Construction Cost 30.1 Project Management and Engineering 5.8 Project Contingency for Expected Cost 9.1 Dismantling and Removal and Inflation 0.5 Inflation, Capital Overhead and IDC 11.4 Implementation Phase Costs 57.0 TOTAL EXPECTED COST 61.5 Project Reserve 9.2 TOTAL AUTHORIZED COST 70.6 Project Cost 33

35 Project Schedule Date December 2009 March 2010 June 2010 August 2011 September 2011 September 2012 May 2013 Decision Points and/or Milestones Application Submitted to the BCUC Radial Gate and Hoist supply-install contract award BCUC Decision Issued Completion of installation of electrical power supply upgrade Completion of installation of two of four radial gates and hoists Completion of installation of remaining two radial gates and hoists Project Completion Project Schedule 34

36 F2031 F2032 F2033 F2034 Annual Incremental Rate Impacts 0.25% 0.20% 0.15% 0.10% 0.05% 0.00% Project Effects 35 F2030 Expected Cost Authorized Cost Per cent % F2010 F2011 F2012 F2013 F2014 F2015 F2016 F2017 F2018 F2019 F2020 F2021 F2022 F2023 F2024 F2025 F2026 F2027 F2028 F2029 Fiscal Year

37 Environmental and Social Effects There are minimal adverse impacts as the project footprint does not extend beyond existing BC Hydro property BC Hydro has carried out an archeological assessment of portion the site being disturbed BC Hydro will continue to operate within the current water license and water use plan. Potential for road closures of Dewdney Trunk Road will be coordinated with the District of Mission and the Ministry of Transport. Project Effects 36

38 Project Cost Risks Cost risks have been mitigated by: Clearly defining project scope Applying previous experience gained on other Spillway Gates projects Monte Carlo simulations and appropriate contingency level to accommodate risks Project procurement strategy Contract termination clauses should BC Hydro decide to delay the Project Project Risks 37

39 Project Schedule Risks Schedule risks are being managed by: Proactive project oversight including scheduling and construction reviews Development of detailed project schedule Managing progress and contractor performance relative to the approved construction schedule Project Risks 38

40 Safety & Environmental Risks Safety Risks are mitigated by: BC Hydro and Contractor Safety Management Plans which incorporate site specific safety and security work practices Monitoring by BC Hydro during construction Environmental Risks are mitigated by: Environmental Management Plans and Environmental Protection Plans enforced through the contracts On-site Environmental Monitor Project Risks 39

41 Consultation BC Hydro has undertaken consultation with First Nations and with public stakeholders to identify issues specific to the Project No or very minimal adverse Project impacts have been identified No opposition to the Project has been identified BC Hydro is of the view that the consultation conducted for the Project to date has been adequate Consultation will be ongoing as the Project progresses Consultation 40

42 Conclusions BC Hydro is seeking BCUC acceptance that expenditures to replace Stave Falls Spillway Gates system are in the public interest. Project costs are: > Expected cost of $61.5 Million > Authorized cost of $70.6 Million BC Hydro has significant reliability concerns given the age of assets and design deficiencies in the existing spillway gate system The project: 1. Addresses end-of-life condition of assets 2. Addresses design deficiencies that could lead to common cause failures and safety risks BC Hydro has identified and is managing project risks through measures such as firm contractor pricing as well as schedule and performance guarantees Consultation 41

43 Questions? 42