LOCATED in northeastern Turkey close to the Georgian border, the Borcka and Muratli dams are situated on the Coruh river 30km and 40km from the city of Artvin respectively. The twin dams form part of an overall project which includes a total of seven hydroelectric dams and power plants on the Coruh river, which will supply power to the northeastern Black Sea region of Turkey.

Both dams are being constructed by a joint venture comprising Yüksel Construction and Temelsu Construction from Turkey, along with Austria’s strabag.

On both projects, Yüksel construction is responsible for drilling and blasting as well as earthmoving involving 600,000m3 of rock per month. The company is using a total of eight Tamrock drilling rigs all equipped with Sandvik rock drilling tools including CAPP bits.

Seven of the rigs are using 76mm and 89mm diameter bits in conjunction with Sandvik T45 drilling rods, while an eighth unit is equipped with T51 rods.

Borcka dam

Construction of the Borcka dam and hydroelectric power plant commenced in 1999, with completion scheduled for 2005. The dam’s height will be 86m, with a crest elevation of 189m, crest length of 557m and crest width of 10m.

The Borcka dam’s construction involves 7.7M m3 of rockfill, as well as 580,000m3 of concrete. For the rock, a drilling, blasting and earthmoving operation is taking place. Rock is drilled, blasted and hauled from what will be the dam’s 30km long reservoir and then deposited at the dam’s rockfill face.

Four Tamrock Ranger 600 drilling rigs equipped with Sandvik drilling tools are operating at the Borcka project. Drilling to a depth of 15m, with approximate 150cm spacings, the rigs drill 100/150 holes before blasting takes place.

The rock is volcanic and very hard, and consequently Yüksel had been pleased with the performance and longevity of the Sandvik bits. According to a site spokesman, the bits are averaging nearly 3000m.

The drill rigs work approximately ten hours a day, which equates to nearly seven hours drilling time. Blasting at Borcka takes place everyday. Every month over 400,000m3 of rock is hauled from the drilling and blasting area, and hauled the 1km to the rockfill site. The contractors have an extensive fleet of earthmoving equipment on-site to compliment the drilling rig, including over ten haulers and 25 trucks.

The Borcka dam will be equipped with four radial spillway gates, with a discharge capacity of 10.639m3/sec. The dam will have two diversion tunnels each with a length of 350m, while the power plant will feature 2 x 150MW turbines.

Muratli dam

Located 10km further upstream, the Muratli dam and hydroelectric power plant is situated on the Turkish side of the Georgian border, in what was a military zone during the Cold War era. Likewise, this project began in 1999 and is scheduled for completion by 2005.

The Muratli dam will have a height of 44m, a crest elevation of 100m, a crest length of 438m and a crest width of 10m.

Here the construction process requires 1.9Mm3 of rockfill and 417,770m3 of concrete. Rock is drilled and blasted from what will be the dam’s reservoir and hauled the approximate 2km to the rockfill site.

One Tamrock Ranger 600 and a Tamrock 1100 drill rig are currently operating on the Muratli dam site. Both unit are equipped with Sandvik 76mm and 89mm CAPP bits; the Ranger 600 using Sandvik T45 rods and the larger Tamrock 1100 being equipped with Sandvik T51 rods.

Drilling to a depth of 15m with 150cm spacings, the rigs work seven hours a day drilling 100/150 holes before blasting takes place.

The Muratli dam and hydroelectric power plant will have four radial spillway gates with a discharge capacity of 10.961m3/sec. Two 350m long diversion tunnels are currently under construction, while the power plant will be equipped with 2 x 57.5MW turbines.

As the Muratli area was a military zone, access to the site had to be improved. Originally only a single-track road existed, but this is currently being widened so as to improve access and allow heavy equipment to be delivered. Two Tamrock Ranger 600 drilling rigs also running with Sandvik drilling tools are currently operating on the mountainous Muratli road.