Dam Safety and Hydro Asset Management: Capacity building in Asia Dr Patrice Droz Mr U Min Khaing Dr Federico Ferranti Dr Stefan Muetzenberg Stucky Ltd Ministry of Electricity and Stucky Asia Stucky Ltd Rue du Lac 33 Energy 10/161, 19th floor, Trendy Rue du Lac 33 1020 Renens Department of Hydro Office Bldg Soi Sukhumvit 13 1020 Renens Switzerland Power Implementation (Sangchan) North Klong Toey, Switzerland Building No 27 Wattana Nay Pyi Taw – TH-10110 Bangkok Myanmar Thaïlande Introduction Capacity building and training are becoming major issues, either in the domain of dam safety or in the framework of operation and maintenance of hydropower plants. In the domain of dam safety, many countries face an absence or a poor dam safety regulatory framework as well as dedicated procedures for ensuring the sustainability of their dams: although some monitoring instrumentation is installed, no systematic analysis is performed; no independent assessment of the behaviour and of the evolution of the structure is made. Dam safety issues are treated on a reactive basis although a proactive attitude should be adopted. A proactive dam safety basis leads the owner of the dam, whatever its own structure might be, public or private, to a politics of asset management which is highly valuable in terms of maintenance budget and investment strategy. This phenomenon is particularly acute for small and medium dams. Rehabilitating hydropower plants often leads to the question of sustainability after rehabilitation: operation procedures and maintenance plans may not be followed and the training performed in the framework of the HPP is limited to the plant and is not used as an example to promote sustainability of other plants of the energy producer. The paper presents the Dam Safety Enhancement Program (DaSEP) and its programs of knowledge transfer between Switzerland and China and Switzerland and Myanmar. The programs aimed at preventing the risks of failure through the improvement of the surveillance and maintenance of the water retention structures. It also describes the main objectives of capacity building and corporate governance to be reached in the framework of the At Bashy HPP rehabilitation project in Kirghizstan. 1. Dam Safety Enhancement Program in China 1.1 China’s water storage issues China counts some 98'002 dams including 756 large dams (volume of the reservoir > 100 million m3), 3’938 of medium importance (10-100 million m3) and 93’308 small ones (0.1-10 million m3) [1]. With almost 98’000 dams, of which some 9’000 are over 30 meters high, China presents the largest number of dams in the world. The total storage capacity of artificial lakes and reservoirs reaches 830 km3, which is about 30% of the total annual river runoff of 2’711 km3 [2], [1]. Given the climate change impacts [3], [4], [5], the China’s storage infrastructure will play an increasingly important role in water resource and watershed management in the future. Facing the number of dams, especially the small and medium ones, there is an urgent need to improve the surveillance and the maintenance of existing China water storage infrastructure. The Dam Safety Enhancement Program (DaSEP-China) consists in implementing a cooperation program between Switzerland and China, in order to improve the management of the surveillance of the existing dams through a transfer of know-how related to methods, practices, information flows and organization in the field of surveillance and monitoring of dams under the responsibility of the Ministry of Water Resources. 1.2 Dam Surveillance in Switzerland The Swiss dam safety concept applies to all dams, whatever their purpose. It is based on the three following pillars [7]: . structural safety, mainly regarding design of the dam . surveillance of the dam behavior and its environment . emergency preparedness and alarm Most of the medium and large dams in Switzerland have been built between 1950 and 1980. After successful dam commissioning, the dam Owners could benefit from several decades of safe and quiet routine dam operation, usually without observing any dam abnormal behavior. This favorable situation gradually changed: after 50 years, the effect of aging is beginning to impact the dams. This situation has required from the dam Owner as well as the Federal Dam Supervisory Authority much more attention and surveillance in order to assure a safe operation of the dams. The global surveillance and maintenance concept of Swiss dams is defined by the flow chart illustrated in the Figure below. The organization of the dam surveillance in Switzerland calls for four competence and responsibility levels: Level 1 The dam warden proceeds to periodical detailed visual inspection, measurements with adapted monitoring equipments. Tests and checks of the monitoring and safety equipment such as bottom outlet gates are also performed under his responsibility as well as the necessary maintenance works. Level 2 An experienced engineer nominated by the dam owner and accepted by the Dam Supervisory Authority analyses regularly the results of the monitoring measurements in order to identify behaviour anomalies of the structure. With the dam wardens, he performs an annual inspection of the dam and prepares an annual report. Figure 1. Global surveillance and maintenance concept (Source: Swiss guidelines, Swiss Federal Office for Energy, Dam Safety Supervisory Authority) Level 3 Only for the largest dams, two confirmed independent experts, one civil engineer and one geologist, proposed by the dam owner and approved by the Authority, assess every five years the safety of the dam. The engineer makes a thorough inspection of the structure condition, analyses the behaviour of the dam and its foundations on the basis of the annual reports of the period. In case of anomaly, he provides recommendations on measures to be taken and on the serviceability of the dam. He checks the condition and the maintenance of the structure and of its monitoring system. He prepares a report to the Owner and to the Dam Supervisory Authority, in which he exposes his observations and recommendations. The geologist assesses the behaviour of the dam abutments and foundation, as well as of the reservoir banks. The Dam Supervisory Authority (Level 4) controls the organization of the three levels above and makes sure that the various procedures and documents are in line with the legal dam safety framework. If necessary, complementary studies and analyses may be requested, as well as temporary lowering of the reservoir level before rehabilitation or repair measures. The Figure below summarizes the four levels of the dam surveillance concept described here above. The owner’s and operator’s experiences demonstrate the critical importance of the Levels 1 and 2 in the organization of the dam surveillance. Figure 2. Organization chart of the four dam safety levels (height > 40m or height > 10m and reservoir volume > 1 Mm3) The premonitory signs of a disorder of the structure can generally be observed through the evolution of relevant monitored parameters and visually before it evolves towards a critical or fateful situation on a safety point of view. The risk prevention thus relies primarily on: . The detection by the dam warden (Level 1) of premonitory signs of a disorder in the structure. The preliminary analysis by the specialist (Level 2) of the observations and measurements made at Level 1. 1.3 Dam surveillance in China The organization of dam safety in China depends not only on the dimension of the reservoir, rather than the dam itself, but also on the purpose of the dam. Hence, dams dedicated to flood control, irrigation and water supply have distinct administrative procedures from those dedicated to hydropower. Nevertheless, the Ministry of Water Resources (MWR) is responsible for the safety of most of the dams in China. Dam safety is supported by a comprehensive regulatory framework defining in particular responsibilities, design standards, reservoir management and emergency preparedness plans. Technical specifications for monitoring are also defined. For the dams depending on the MWR, in general, large dams are under the responsibility of the Provincial Water Resources Dpt., medium size dams under the responsibility of the Prefectures or Cities and the small ones under the responsibility of the districts or townships. The reservoir management in terms of operation, inspection and monitoring is often assumed by Reservoir Management Units (RMU) who report to either the Provincial Water Resources Dpt., or to the equivalent at the district or city level. The RMU's must produce a yearly planning report describing the forecasted operations schedules. If some abnormality is detected through visual inspections, a report is prepared and sent to the above administrative level. The report contains the monitoring data collected if any. For the small and medium dams, no systematic analysis of these data is performed prior to the identification of the abnormality. Before the flood season, an inspection or a coordination meeting is organized by the above administrative level to make sure that the dam and its appurtenant structures will function correctly. If State funding allocation is required for Dam improvements, the above administrative level is informed and the Dam Safety Management Center expertise is requested for Dam Safety Review. 1.4 Comparison between Swiss and Chinese dam surveillance procedures . In China, most of the dams are aiming at flood protection and used for water supply for domestic and irrigation purposes. In Switzerland, all the large dams are dedicated to power generation. In China, there is no systematic reporting for the small and medium dams. Therefore the procedure can be qualified as reactive instead of the Swiss procedure which is more proactive, trying to detect defects as early as possible. In China, the enforcement tools seem reduced since the usefulness of each dam is essential for flood protection and water supply. In Switzerland, the Dam Supervisory Authority has the power to impose the dam owner to lower the reservoir level in case of abnormal behaviour which may present a risky situation to the populations living downstream.