8.
Project Activities on BC Hydro Dams The safety status of BC Hydro dams is assessed through ongoing surveillance, periodic Dam Safety Reviews, and Deficiency Investigations. Capital improvements
The capital dam safety improvement projects are listed in Table 1 in Appendix C.
Projects Completed Strathcona Dam
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The upstream erosion protection had deteriorated and locally exposed the underlying dam shell materials. The deficient slope protection was upgraded by placement of riprap over the existing slopes. The work was successfully completed in the spring of 2002 under the planned cost, due to favourable bids as well as favourable reservoir conditions during construction.
Strathcona Dam – Erosion Protection
Sugar Lake Dam
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Stability improvements of Sugar Lake Dam for flood and earthquake were completed in the early part of 2002. The improvements consisted of installing six post-tensioned anchors through the downstream concrete buttress into the bedrock foundation, as well as installation of steel strap anchors on the buttresses in the overflow section of the dam. Sugar Lake – Anchor Installation
Active Projects The major active capital improvement projects include: -
Seven Mile Elsie Coursier Mica WAC Bennett
Dam Safety Program Annual Report 2002/2003
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Seven Mile Dam
The total estimated cost for the Seven Mile upgrade is $84 million. The work includes dam anchoring, spillway gate improvements and operational reliability improvements.
Seven Mile – Guide and Support for Installing Anchors
Final design was completed for the 92-strand dam anchors. Three anchors were successfully completed in Phase 1 of the program, and installation of the remaining 54 anchors is in progress. Design was completed for replacement of the concrete spillway gate hoisting supports with a steel structure. Construction mobilization has commenced. Design of the electrical, protection and control improvements are in progress. Six technical Advisory Board meetings have been held to-date during the development of the risk control options and design. ¾
Elsie Dam
The Elsie Dam project commenced in June 2001 and the loose layers within the earthfill dams (Main dam and Saddle dam #1) were excavated and the dams reconstructed in F2002. In F2003, modifications to the low level outlet tower and intake structure to improve their seismic performance was completed. The original intake tower has been removed and a new trashrack, gate, operating equipment and gate hoist structure were constructed. Total project cost to date is $10.8 million. A claim by the dam reconstruction contractor is proceeding to arbitration. Elsie Saddle Dam – Upgraded Intake structure
Due to higher-than-anticipated costs, the remaining design of improvements to the downstream portion of the low level outlet conduit is being re-evaluated and optimized. Completion of the remaining improvements is expected in 2004. ¾
Coursier Dam
The project to decommission Coursier Dam commenced in early 2002 and an application to the Environmental Assessment Office was submitted in December 2002. A Project Approval Certificate is expected in May 2004. A submission is being prepared for British Columbia Utilities Commission in April 2004. Coursier Dam
Consultation activities are continuing and comments from the public and First Nations are being reviewed and addressed. Detailed engineering design has begun, with construction activities scheduled to start in summer 2003. ¾
Mica Dam
Construction of the major portion of the Dutchman's Ridge Adit Portal upstream of Mica Dam was completed late in 2002 to replace and upgrade the badly deteriorated temporary timber structures built during original construction of the adit. The electrical and tunnel ventilation upgrades will be completed in early 2003 as soon as weather conditions permit access. Mica Dam - Dutchman’s Ridge Adit Portal (Upgraded)
The adit was constructed to lower the water table, thereby increasing the stability of this large rock slide immediately upstream of Mica Dam. The portal structure, lighting and ventilation are essential for monitoring and maintenance of the drainage system. Dam Safety Program Annual Report 2002/2003
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WAC Bennett Dam
Improvements were initiated at WAC Bennett Dam to enhance the seepage collection system in the main canyon section by sealing the dam foundation and redirecting the seepage to the downstream weir.
WAC Bennett Dam - Drilling and grouting at dam toe
Deficiency Investigations
Phase 1 construction work to seal the upper granular materials overlying bedrock was completed in October 2002. Additional exploratory drilling investigations were also carried out to assist with the design of the Phase 2 grouting program. Design of the Phase 2 work to seal the pervious upper bedrock layers is currently underway, with construction scheduled for summer 2003. Ongoing deficiency investigations (Table 2 in Appendix C) which are expected to require significant risk control measures include: • Coquitlam • La Joie • Ruskin/Stave Falls (Blind Slough) • Strathcona • Hugh Keenleyside • John Hart ¾
Coquitlam Dam
Interim reservoir restrictions are being maintained at Coquitlam Dam as remedial options are being developed. Following the Advisory Board meeting in June 2002, studies were initiated to investigate an option consisting of an embankment dam upstream of the existing dam for comparison with other options. Final assessment and consultation with interested parties is underway. The next scheduled meeting of the Advisory Board is in July 2003. Implementation of permanent remedial measures is now scheduled to be complete by 2006 at an estimated cost of about $40 million. Coquitlam Dam
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La Joie Dam
A preliminary report has been prepared which confirms a seismic deficiency with the upstream face of La Joie dam. In addition, the intake tower is predicted to fail in a major earthquake. The feasibility and constructability of various remedial options are being assessed. Estimated costs, which have significant uncertainty, are $33 million. An Advisory Board meeting is scheduled for September 2003 to consider the engineering recommendations and proposed solutions. La Joie Dam
Dam Safety Program Annual Report 2002/2003
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Ruskin/Stave Falls (Blind Slough)
Seismic deficiencies for Ruskin Dam and Blind Slough spillway at Stave Falls were confirmed, and preliminary remediation dam anchoring options were identified. An Advisory Board meeting was held in September 2002 and further options were identified, including possible reconstruction of the upper spillway piers at Ruskin Dam. Remediation options are also being developed for the right earth abutment to address seepage related issues.
Ruskin Dam
Potential remediation costs for anchoring at Blind Slough are about $6 million. The studies are not as advanced at Ruskin Dam and remediation costs for the concrete dam and right abutment are uncertain at this time, but total costs could be in the order of $25 million or more. ¾
Strathcona
Seismic deficiencies with the intake tower, the conduit within the embankment dam and the dam filters have been identified at Strathcona Dam. An Advisory Board was convened in January 2003. Further engineering analysis is required, particularly with respect to seismic performance of the intake tower. Potential future remediation costs to address the deficiencies of the embankment dam are of the order of $17 million. Strathcona Dam
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Hugh Keenleyside Dam
A review of remediation options for Hugh Keenleyside Dam have been initiated with due consideration of the most recent advances in technology. An Advisory Board meeting was held in June 2002 to consider the future direction of the project and to assist with development of the safety case. Vibro-densification trials at Hugh Keenleyside Dam
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John Hart Dam
There are two separate aspects to the John Hart Dam deficiency investigations - reliability of the spillway gates and the potential for landslides in the reservoir. An Advisory Board meeting was held in November 2002 to review the gate reliability issue. Seismic triggers have been installed at the upstream Ladore dam to stop flow releases from Ladore Dam into John Hart Lake to mitigate system flow imbalance. John Hart Dam - Spillway
A potential spillway deficiency has been identified, such that the existing spillway may not have adequate capacity to pass the design flood.
Dam Safety Program Annual Report 2002/2003
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Business Summary The progress of dam safety activities over the fiscal year, compared to the F2003 plan, is shown on the table below. Dam Safety Program Costs versus Plan $ Millions Plan
Actual
Total OMA
5.0
4.5
Deficiency Investigations
5.8
5.4
Capital improvements
44.0
20.0
TOTAL CAPITAL
49.8
25.4
Operation, Maintenance and Administration (OMA) Program
The OMA target for F2003 was reduced to $4.5 million during the year, as part of an overall Generation strategy. This was accomplished by a reduced effort and scope on some lower priority surveillance and risk management activities.
Capital Program
The overall capital program, which consists of Deficiency Investigations and Capital Improvements, was underspent by $24.4 million or 49%. Of this, Capital Improvement projects were underspent by $24.0 million and Deficiency Investigations by $0.4 million. The major variances are described below. The scope and schedules of various deficiency investigation and capital upgrade projects were revised from the F2003 plan during the year. The revisions were required due to the reorganization of BC Hydro Engineering Services. The reorganization resulted in project reassignments for many technical resources and project management personnel.
Capital Improvement Projects - Variances
The Seven Mile Capital Improvement project was under plan by $16 million. The final design of the anchors for the concrete dam resulted in a project cost reduction of about $6 million, as reported in the first quarter report. The Contractor's modification of the anchoring on-site shift work in July 2002 resulted in efficiencies and a cost reduction of $4 million. A delay in design of the Spillway Improvements and the Site Systems Improvements resulted in a shift of about $5 million from F2003 into F2004. These items resulted in a total fiscal year reduction of about $15 million from the original forecast of $28 million for Seven Mile Dam. The remaining $1 million represents other minor schedule shifts over fiscal year boundaries for this multi-year project. The projects affected by reorganization and staffing included seven projects, with planned expenditures of about $8 million, which did not commence because the associated deficiency investigations were not completed during F2003.
Dam Safety Program Annual Report 2002/2003
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The seven planned Capital Improvement projects which did not begin in F2003 were: Project
Variance from Annual Plan ($ Million)
Ruskin Stave Falls (Blind Slough) Seton Coquitlam Hugh Keenleyside LaJoie Strathcona
-0.5 -0.5 -0.4 -2.0 -0.3 -2.7 -1.6
TOTAL Deficiency Investigation Projects - Variances
$8.0 million
Four lower priority Deficiency Investigations were delayed or not initiated, due to higher priorities for specialist engineering resources within the dam safety program. •
John Hart - Reservoir slope stability
•
Peace Canyon - Instrumentation and dam performance
•
Spillimacheen - Structural stability
•
Terzaghi - Earthquake performance
These projects, along with scope or schedule adjustments in other deficiency investigation projects, account for the -$400,000 variance.
Dam Safety Program Annual Report 2002/2003
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Strategic Issues and Other Initiatives External Advisory Boards, Learned Societies, and Dam Safety Practices
External Advisory Boards The Director of Dam Safety was invited to sit on the following Advisory Boards to advise the owners on the dams poor performance, and appropriate risk mitigation or control measures. • Dickson Dam, Alberta Environment (with Dr. N.R. Morgenstern) • Suorva Dam, Vattenfall Vattenkraft, Sweden • Shikwamkwa Dam, Brascan Power, Ontario (with Drs. Peck and Morgenstern) Canadian Dam Association (CDA) • • •
R.A. Stewart is Vice President. C.B. Raska is regional director for British Columbia BC Hydro took a lead role in the organizing a very successful Annual CDA Conference in Victoria, which attracted more than 250 dam practitioners from Canada and overseas.
Spanish Committee on Dams (SEPREM) •
SEPREM hosted an International Dam Safety Conference in Madrid in November 2002. R.A. Stewart was invited to present the keynote address.
Federal Energy Regulatory Commission (FERC) •
The FERC Director for Dam Safety invited R.A. Stewart and D.N. Hartford to Washington, D.C. to discuss dam safety practices, in February 2003. The discussions also addressed dam security practices.
International Commission on Large Dams (ICOLD) •
Dam Safety Research
D.N. Hartford continues to represent BC Hydro and Canada as one of the authors of the ICOLD Bulletin on Risk Assessment in Dam Safety Management, expected to be completed in June 2003.
IMPACT Project, Norway and European Union • •
•
D.N. Hartford was invited to participate as an Industry Representative on the European Union’s research project Investigation of Extreme Flood Processes and Uncertainty (IMPACT). BC Hydro in partnership with Vattenfall Vattenkraft and Elforsk of Sweden has developed an agreement with the IMPACT project presently underway in Norway. We will be able to modify an embankment dam that they are constructing, and study the value of some geophysics methods under the conditions of controlled dam failure. Our contribution of $100,000 research funds has provided BC Hydro an opportunity to include our test program into this unique multi-million euro European research program.
Dam Safety Program Annual Report 2002/2003
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Canadian Electricity Association (CEA) Dam Safety Interest Group (DSIG)
Strategic Co-operation
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BC Hydro’s Director of Dam Safety is a sponsor of this Group and provides leadership to the Group’s research projects on Geophysical Methods for Investigating the Internal Erosion Behaviour of Earth Dams, and on Dam Risk Management. K.Y. Lum and D.N. Hartford are leading these activities respectively. The Interest Group now includes 16 members of which 9 are from other countries including the United States.
•
The Director of Dam Safety is the sponsor of the innovative Life Safety Model, a virtual-reality approach to managing dam emergencies. The model has attracted significant international interest in Japan, the Netherlands, Sweden, the United Kingdom and the United States.
BC Hydro continues to provide Vattenfall Vattenkraft’s (Sweden) dam safety office with guidance and implementation advice on its dam safety program and dam risk management. In particular Vattenfall is adapting BC Hydro’s dam safety management system and prioritization scheme, with our assistance. BC Hydro is performing dam breach inundation studies for the Columbia River jointly with the United States Bureau of Reclamation.
Dam Safety Program Annual Report 2002/2003
