EIGHT TAMROCK drilling rigs fitted with Sandvik rock tools are helping to shift 600,000m 3of rock for the construction of two Turkish dams.
The Borcka and Muratli dams are being built on the Coruh River in north eastern Turkey, close to the border with Georgia, 30km and 40km respectively from the city of Artvin.
A joint venture of Turkish firms Yüksel Construction and Temelsu Construction, with Austria's Strabag, is undertaking both projects.
Seven hydroelectric dams and power plants are being built on the river to supply the Black Sea region of Turkey.
Construction of the 86m high Borcka Dam began in 1999 and is due to finish in 2005. It will have a 557m long, 10m wide crest with an elevation of 189m.
The dam's four radial spillway gates will have a discharge capacity of 10.639m 3/s. It will have two 350m long diversion tunnels, while the power plant will have two 150MW turbines.
Yüksel Construction is drilling, blasting and moving 7.7M. m 3of very hard volcanic rock from the reservoir area to form the dam face. More than 400,000m 3of rock is hauled 1km to the fill site every month.
The firm is using four Tamrock Ranger 600 drilling rigs fitted with Sandvik bits and rods to bore the holes for the charges.
The machines drill to 15m on a 1.5m grid, with between 100 and 150 holes drilled before blasting.
Despite the hard rock, the bits are 'holding up well' according to Sandvik, averaging 4000m of drilling before needing to be replaced.
About 10km upstream, the Muratli Dam sits next to the Georgian border in what was a military zone during the Cold War era. This project also began in 1999 and is due to finish in 2005.
The 44m high dam has a 438m long and 10m wide crest with an elevation of 100m. Construction follows a similar pattern to Borcka, with Yüksel Construction drilling, blasting and moving 1.9M. m 3of rock fill.
The firm is using a Tamrock Ranger 600 and a Tamrock 1100 drill rig, both equipped with Sandvik drill tools, to drill blast holes, again 15m deep on a 1.5m grid.
The Muratli Dam and hydroelectric power plant will have four radial spillway gates and a discharge capacity of 10.961m 3/s.
Two 350m long diversion tunnels are being built, equipped with two 57.5MW turbines.
Two Tamrock Ranger 600 rigs are also working on the blasting operation to widen the 20km long access road to the site.