China - Western Provinces Rural Water Supply, Sanitation and Hygiene Promotion Project : environmental assessment (Vol. 5 of 5) : Abstract of dam safety in 20 percent of project areas for Shaanxi Province

Page 1 1 Shaanxi Rural Drinking Water Supply and Sanitation Project by Using World Bank Loan and DFID Donation Abstracts on the Dam Safety in 20% project areas Shaanxi Institute Environmental Science Research & Design Dec. 2006 E1491 v 5 Page 2 2 In this project, Yaozhou Maju water supply scheme, Baocun water supply scheme and Yintai Xiyuan water supply scheme will take raw water from three different reservoirs respectively. These three existing reservoirs currently are under normal operation. And the dams just passed a comprehensive safety evaluation recently. The dams are classified as Category II, non-dangerous dams. Since the heights of the three dams are over 15 meters, a separate dam safety evaluation report (See Annex 5) was prepared for this project according to the World Bank safeguards policy OP4.37 and requirement of the World Bank deputation, which is summarized below. (1) Overview of the related dams The three dams in the project are Taoqupo Reservoir Dam for Maju Water Supply Scheme, Baocun Reservoir Dam for Baocun Water Supply Scheme, and Mashaogou Reservoir Dam for Xiyuan Water Supply Scheme respectively. Table 1 Shows the General Situations of the Three Dams (details please see Annex 5 of full Chinese Report) Dam name Heights (m) Volume (1,000m3) Compositions Built time Remarks Taoqupo Dam 61 36,020 1979 Homogeneous earth-filled dam Baocun Dam 27.7 1,370 1985 Homogeneous earth-filled dam Mashaogou Dam 40 3,120 Dam, flood spillway, water discharge facility 1980 Roller compacted homogeneous earth-filled dam (2) Overview of the operation of the related dams The three dams have been in operation since construction was completed. Their operation status is summarized below: i) Taoqupo reservoir started storing water on March 9, 1974. It took about 5 years (1975-1979) to repair seepages. It has been operated normally since the construction was fully completed. Page 3 3 ii) The construction of Baocun reservoir was started in the winter of 1978. The construction was completed in 1985. The reservoir has been operating normally for about 21 years. iii) The construction of Mashaogou reservoir was started in 1970 and completed in May 1980. The height of the dam was 25 meters at that time. The engineering work of increasing the dam height was started in 1980 and finished in 1982. The dam was increased to 38.0 meters. The remaining works were finished in March 1983. The dam was finally increased to 40.0 meters. A 1.0 meter high breakwater wall was built at the top of the dam. The inclined pipe of the dam was maintained in 1997. This dam has been normally operated for about 26 years since it was put into operation in 1980. (3) Dam Safety Evaluation and the Conclusions. Based on the Methodology of Dam Safety Evaluation (Shuiguan [1995] No.86) which is issued by Ministry of Water Resource, each dam is required to conduct a comprehensive safety inspection or evaluation every 6-10 years during operation. The management agencies of the three dams set up specialist teams and organized evaluations for the dams in 2001 and 2002. Table 2 lists general of safety inspections. Table 2 Details of Safety Inspections for the Dams Dam name Date Organizer & Implementation Agency Conclusion Taoqupo Dam Oct. 2001 Shannxi Water Conservancy and Hydropower Investigation and Design Institute; Shaanxi Dam Safety Management Monitoring Center; Xi