At-Bashy Dam and hydropower scheme was put into operation in December, 1970 with its installed capacity of 40 megawatt. The scheme is located in a high mountain Naryn Rayon of Naryn Oblast on Atbashy River. Atbashy River is the largest left-bank tributary of the Naryn. Its length is 178 km and a water intake area is 5540 square kilometers. The source of the At-bashy River rises at an altitude of 4542 m above sea level, at the junction of Naryn-Too Mountains and the Borkoldoi Range. In this area, the river’s name is Zhanyzher. The river sources are the brooks formed by glacier melt.

The At-Bashy Hydro Power Plant is located near the town of Naryn at 1900 metres above sea level. The installed capacity is 40 MW composed of 4 vertical Francis units each with a rating of 10 MW, which operate with 70.4 m3/sec under a water head of 67.5 m. The annual energy production is 130 to-160 GWh. The hydropower station has a daily storage reservoir with a usable volume of 7 million cubic meters. The geology of the site is complex and characterized by a high permeability.

The scheme is located in a narrow canyon at the place where the At-Bashi River flows into the Naryn Valley. At the dam site, the width of the canyon is only 5-8 m. The faces of the canyon are almost vertical to a height of 30 m and then inclined with 80-85 degrees. The whole site is located in a highly seismic area.The dam is a 79 m high and 50 m long Rockfill dam made from local gravel. In the upper part, there is a diaphragm made from a 0.6 mm geomembrane for water tightness.

The plant is not only important for the local energy supply, but also for the network stability of Southern Kyrgyzstan. Given the importance of the power plant, the complete rehabilitation of the electromechanical equipment was studied and implemented.

Gruner Stucky’s services on the At Bashy rehabilitation project

The rehabilitation was supported by SECO through a grant contribution of almost 20 million Swiss francs.

The overall project goal of the hydropower rehabilitation project in Kyrgyzstan is to contribute to the social-economic development of the Naryn region by ensuring reliable and sustainable generation and supply of electricity to its population and business community. To this end, four key objectives were determined: (1) improve production capacity and reduce technical losses; (2) improve safety; (3) improve corporate governance; and (4) reduce carbon dioxide emissions. Through such initiatives, it was projected that long-term production security and generation stability will be restored and secured, with an increase in production capacity of 10%, annual productivity of the station also increasing. Moreover, through improved management capacities as well as standards of transparency and governance implemented, Hydropower operations and management staff capacity also increased. Finally, the project will support the reduction of non-renewable power resources and thus has a positive impact on the environment, especially via climate change mitigation. Altogether, these initiatives provided a pathway towards achieving the overall goal of this hydropower rehabilitation project.

Gruner provided the owner’s engineer services for the At Bashy hydropower rehabilitation project.

Gruner Stucky Ltd thus acted as Owner’s engineer for the rehabilitation and upgrade of the hydropower plant with the specific project targets of re-establishment of uninterrupted and stable production of electricity; improvement of production capacity and reduction of technical losses, increase by at least 10% to more than 45.8 MW; thus the annual productivity shall be increased to 160-180 GW.

Gruner thus provided the design, planning and works supervision services for the

• The rehabilitation and upgrade of the Electro mechanical equipment rehabilitation which included Francis turbines; Generators; Electrical equipment; Control and communication systems, Protection; and Transformers.
• The rehabilitation and upgrade of the hydro mechanical equipment: Francis turbines; Auxiliary systems.
• Civil works and auxiliary powerhouse equipment: Power house fire fighting system, Ventilation and heating system; Fire protection walls.

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