3.1 Oroville Dam Spillway Accident
27
Physical Inspections: The roots of this lesson were found in the use of visual inspections as the primary part of the risk management program structured to monitor the
integrity of the water retaining facility on an ongoing basis. The IFT identified the
need for owners and operators to be better informed to identify risks and manage
dam integrity by expanding the inspection program to include supporting information provided by subsurface and non-destructive testing, ongoing facility reviews and
risk analysis methodologies.
Regulatory Compliance: The lesson here is very simple. It is that “Compliance
with regulatory requirements is not sufficient to manage dam owners’ and public
risk.” The IFT recognizes that regulators play an essential role in the management of
dam facilities but notes that their efforts are typically narrowly focused and restricted
by available resources. Despite such limitations the IFT noted that DWR had relied
too heavily on the regulators and the regulatory process.
Dam Safety Program and Risk Management: The IFT is generally of the view
that a dam owner should have: (1) a strong commitment to dam safety based on
strong top-down leadership; (2) a comprehensive risk management framework with
risk-informed dam safety decision-making as an integral part; (3) sufficient staff
and funding to identify and manage dam safety issues on a proactive basis, rather
than merely struggling to keep up with regulatory requirements on a reactive basis.
While this lesson was directed at DWR, it is included here because of its general
applicability.
3.2 The Xe-Pian Dam Disaster
In this section we briefly discuss another hydro-dam failure and draw some links to
the tailings dams world portfolio.
A series of events starting Sunday, 22 July 2018, led to a Laotian hydro-dam
collapse with catastrophic consequences on the population downstream (Fig. 3.2).
The collapsed dam was part of the Xe-Pian Xe-Namnoy hydroelectric power project,
then still under construction. The project is located in the Attapeu Province in central
Laos and involves Laotian, Thai and South Korean firms. Lao PDR is particularly
rich in vertical drops with hydro-generating potential. As a matter of fact, the country
had forty-six operational hydroelectric power plants in 2017 with a further fifty-four
under construction.
The feasibility study for this particular project was reportedly completed in
November 2008, construction began in February 2013 and commercial operations
were expected to begin in 2019 (Poindexter 2015). The project includes two main
dams (Xe-Pian and Xe-Namnoy) and five subsidiary dams. The dam that collapsed
was the “Saddle Dam D”, one of the subsidiary dams. The structure was reportedly
8 m wide (at the crown), 770 m long and 16 m high. The purpose of the subsidiary
dams of this project is to “help divert water around a local reservoir”, as reported by
the owner and delivered by local media.
27
Physical Inspections: The roots of this lesson were found in the use of visual inspections as the primary part of the risk management program structured to monitor the
integrity of the water retaining facility on an ongoing basis. The IFT identified the
need for owners and operators to be better informed to identify risks and manage
dam integrity by expanding the inspection program to include supporting information provided by subsurface and non-destructive testing, ongoing facility reviews and
risk analysis methodologies.
Regulatory Compliance: The lesson here is very simple. It is that “Compliance
with regulatory requirements is not sufficient to manage dam owners’ and public
risk.” The IFT recognizes that regulators play an essential role in the management of
dam facilities but notes that their efforts are typically narrowly focused and restricted
by available resources. Despite such limitations the IFT noted that DWR had relied
too heavily on the regulators and the regulatory process.
Dam Safety Program and Risk Management: The IFT is generally of the view
that a dam owner should have: (1) a strong commitment to dam safety based on
strong top-down leadership; (2) a comprehensive risk management framework with
risk-informed dam safety decision-making as an integral part; (3) sufficient staff
and funding to identify and manage dam safety issues on a proactive basis, rather
than merely struggling to keep up with regulatory requirements on a reactive basis.
While this lesson was directed at DWR, it is included here because of its general
applicability.
3.2 The Xe-Pian Dam Disaster
In this section we briefly discuss another hydro-dam failure and draw some links to
the tailings dams world portfolio.
A series of events starting Sunday, 22 July 2018, led to a Laotian hydro-dam
collapse with catastrophic consequences on the population downstream (Fig. 3.2).
The collapsed dam was part of the Xe-Pian Xe-Namnoy hydroelectric power project,
then still under construction. The project is located in the Attapeu Province in central
Laos and involves Laotian, Thai and South Korean firms. Lao PDR is particularly
rich in vertical drops with hydro-generating potential. As a matter of fact, the country
had forty-six operational hydroelectric power plants in 2017 with a further fifty-four
under construction.
The feasibility study for this particular project was reportedly completed in
November 2008, construction began in February 2013 and commercial operations
were expected to begin in 2019 (Poindexter 2015). The project includes two main
dams (Xe-Pian and Xe-Namnoy) and five subsidiary dams. The dam that collapsed
was the “Saddle Dam D”, one of the subsidiary dams. The structure was reportedly
8 m wide (at the crown), 770 m long and 16 m high. The purpose of the subsidiary
dams of this project is to “help divert water around a local reservoir”, as reported by
the owner and delivered by local media.