DUSHANBE, September 2, 2014, Asia-Plus -- The Assessment Studies for the proposed Roghun Hydropower Project in Tajikistan (Roghun HPP) have been finalized after the fifth round of riparian consultations was completed and comments from government and civil society stakeholders were carefully considered.  This is the result of four years of independent, transparent, and consultative analysis to assess the feasibility of the proposed Roghun HPP from the technical, economic, environmental, and social perspectives.

The final Techno-Economic Assessment Study (TEAS) Phase 2 Summary Report and the final Environmental and Social Impact Assessment (ESIA) Report were disclosed on September 1, 2014 on the Government of Tajikistan’s and the World Bank’s websites. 

The World Bank also disclosed on September 1 the “World Bank Note - Key Issues for Consideration on the Proposed Roghun Hydropower Project.”  The Note summarizes the process and key findings from the assessment.  It also identifies additional issues for consideration in the context of the proposed project, including Sector and Economic Management Framework and Transboundary Water Management.

In response to a request by the Government of Tajikistan, the World Bank supported two studies to evaluate the viability of the proposed Roghun according to international standards: Techno-Economic Assessment Study (TEAS); and  Environmental and Social Impact Assessment (ESIA).

These Assessment Studies were conducted by international consultant firms contracted on a competitive basis by the Government of Tajikistan and financed through an IDA project with assistance of World Bank experts.   A consortium led by Coyne & Bellier undertook the TEAS while Poyry Energy Ltd. of Switzerland directed the ESIA.

The Assessment Studies examined the potential benefits and risks of the proposed Roghun HPP and comprehensively evaluate its technical, economic, social, and environmental viability based on international standards and practices and in accordance with the World Bank’s policies and procedures.  

The Techno-Economic Assessment examined basic geological and hydrological data, engineering and design issues, construction costs and schedule, and economic and financial feasibility, as summarized below.

Three possible dam heights were assessed (defined as full supply levels of 1290, 1255, and 1220 meters above sea level with total reservoir capacities of 13.3, 8.6, and 5.2 bcm, respectively) and three different levels of installed generation capacity for each dam height, yielding nine different design options.  All of the dam height options are “high” dams and for ease of reference are hereafter referred to as the 1290m, 1255m, or 1220m design options.

The studies conclude that, subject to modifications in the original design and the implementation of identified mitigation measures, a large dam could be built and operated at the Roghun site in line with international safety norms.

The assessment of existing works concludes that several of the underground structures, including the two existing diversion tunnels and the powerhouse cavern, would require strengthening and remedial measures, as well as comprehensive monitoring, in order to meet international norms.

The study concludes that, with implementation of appropriate mitigation and monitoring measures, the Roghun site is suitable for a rockfill dam of any of the proposed heights.

Based on the seismic design parameters derived from a deterministic approach, the assessment study concludes that all three dam height alternatives can withstand the Maximum Credible Earthquake.

The design modifications proposed in the assessment study make all three dam heights capable of withstanding the Probable Maximum Flood.

The study concludes that the large amount of sediment carried by the Vakhsh River (a) makes higher dams more attractive since they provide a longer lifespan (i.e., before being filled with sediment) and (b) necessitates design modifications that incorporate specific end-of-life strategies irrespective of dam height.