Vatnsafl

Dariali vatnsafls­virkjun

Georgia

  • Dariali

Verkís services was feasibility study, project design, tender documents, detail design of civil works and design review.

 Stærðir: installed capacity 108 MW, rated discharge 33m3/s, head 379,3 m
 Verktími:  2011 - 

Almennt um verkefnið:
The Dariali hydroelectric project is located in the Tergi river in Kazbegi district near the town of Stepantzminda in northern Georgia. The site is located about 160 km north of Tbilisi and characterized by high mountains and deep valleys, typical of the Caucasus region. The capacity of the project has been set at 108 MW and annual energy generation is estimated 500 million kWh. 

The Tergi river is to be dammed at elevation about 1.725 m with a low concrete dam spillway structure. Two sand sluices will be provided also acting as a gated spillway in case of floods. A fish ladder will be provided between the spillway and the sand sluices. An intake structure is to be constructed and from there, a 4,0 m diameter steel pipe will convey the water to a sand basin. A 200 m long and up to 40 m wide sand basin will be provided on the head race canal route, some 845 m from the intake structure. 

From the sand basin the water will be conveyed through a buried steel pipe of diameter 4,0 m and 1.125 m long to the tunnel entrance. The head race tunnel will be about 5.040 m long from the tunnel intake to the pressure shaft. It is constructed with a 5,5 m diameter tunnel boring machine (TBM). The head race tunnel will convey the water from the diversion pipe to the pressure shaft feeding the power units in an underground powerhouse. A surge shaft will be provided to reduce water hammer in the head race tunnel system and to facilitate grid regulation by the power units. 

The powerhouse will be underground, a 71 m long, 13,5 m wide and about 28 m high conventional underground cavern supported with rock bolts and shotcrete, housing three Pelton units on vertical axis. Each unit will be 36 MW at rated load. The top of the powerhouse will be about 110 m below the overlying ground surface. The tail race tunnel runs from the powerhouse to the Dariali valley conveying the tail water back to the Tergi river. It will be excavated by drill and blast technique from outside towards the powerhouse. The tail race tunnel will be 500 m long, 5 m high and 5 m wide and will convey the tail water to a short tail race canal entering the Larsi project headworks pond in the Tergi river. The switchyard will be located outside on the right Tergi riverbank near the head race tunnel adit, and guarded by a safety fence. The substation consist of the unit power transformers, intermediate station transformers, air insulated (AIS) switchgear with circuit breakers and disconnecting switches, instrument transformers, surge arrester and steel structure.