New drills for big dam build

This is what the valley looked like before the giant drills moved in Now the site is stripped to become a 'virtual quarry'.
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Rock conditions feature a mix of very hard and abrasive volcanic basalt, granites, granite diorite and quartz with a hardness factor of between 5 – 7.5.

Blasting is carried out twice daily at shift change and lunch.

All five hydraulic rigs are fitted with the Sandvik T51 3.6 m long mf drill rods.

Depending on the rock conditions three different bits are used. Retrac ‘normal face’ 89 mm diameter bits are predominantly used, particularly in the harder rock.

Retrac ‘drop center’ and ‘flat face’ bits are also used when the rock conditions dictate. If the contractor is drilling less than 10 m in soft ground, standard drop center 89’s are used.

Kolín is also shortly to introduce guide tubes for poor ground conditions to also achieve much straighter holes.

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Abrasive rock

But it is the abrasiveness of the rock which is the prime consideration where the drill bit life can be as low as 100 drill metres.

The rig operators confirmed however that the bits are frequently lasting each 10 hour shift with around 400 drill metres.

“This performance is very high and quite exceptional considering the abrasiveness and inconsistencies of the rock,” said Mehmet Tuncay, adding, “Another challenge is being able to meet the speed of the drill and blast cycles.”

“The MF rods are also providing high performances and exceptional long life.”

Each drill rig is producing 200 m3/h per rig to ensure the specified 2000 m3/rig is produced each 10 hour shift.

Drilling to 15 m depths, each hole takes an average 20 minutes depending on the rock conditions.

On completion the project, which features a 1219 m high penstock makes it the highest head on an hydro-power plant scheme in Turkey to date.

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