Gulf Construction Online - Sandvik in Waterfront dewatering role

Dubai Review

Sandvik in Waterfront dewatering role

01 April 2009

DEWATERING well drilling techniques using Sandvik Tophammer drill rigs on the Dubai Waterfront project are achieving faster penetration rates in sand than conventional auger drilling methods, according to the Sweden-based Sandvik Mining and Construction Middle East.

Drilling rates of up to 540 m per shift for dewatering wells in the sand are being achieved by contractors on the Dubai Waterfront project in Jebel Ali with Sandvik Ranger 780 Rock Pilot drill rigs and tools.
Two contractors are each using a Ranger 780 Rock Pilot and Sandvik rock tools to drill 6-m-deep holes in compacted sand at 1-m spacing for a dewatering system, producing up to 90 holes in each shift.
According to Jukka Naapuri, general manager for Sandvik Mining and Construction Middle East, the concept, although not particularly new, has not been extensively utilised in the UAE. “But, with the sharp increase in dewatering requirements on major projects, such as the Waterfront, two contractors recognised the potential and each took delivery of Ranger 780 Tophammer rigs,” he adds.
“Advances in Sandvik’s hydraulic control system over recent years have also been a factor in using this technique,” he says. “The system is able to sense strata changes when drilling and is able to react to different layers of sand and mud much faster.”
Operator Rodolfo Bumatay, who has many years experience of Sandvik rigs and jumbos in Saudi Arabia, the UAE and the Philippines was surprised and sceptical when he first saw the application. “I was really surprised because Sandvik rigs are designed for drilling rock and even though this was compacted sand, I had my doubts,” he explains.
He goes on to say that the flushing system plays a key role in the sand, getting activated if the drilling is too fast in the soft sand. “Similarly, it is important to observe the flushing pressure to avoid jamming so drilling must be done in a controlled way.”
It is also essential to ensure that no mud enters the dust collector to avoid having to wash out.
Despite initial doubts, Bumatay is confident about the Sandvik’s performance and in achieving the high performance rates.
The Ranger 780 Rock Pilot is fitted with 3.66-m-long Sandvik T51 rods and 102-mm Retrac button bits, which feature a ballistic button design to provide fast penetration and better flushing. Five months after the delivery of the rigs to site, the button bits have not worn out and are still in service, says Naapuri.
The Waterfront is considered to be the largest and most ambitious urban development project in the world. The coastal development includes the world’s largest master-planned city, encompassing an area of 1.4 billion sq ft – twice the size of Hong Kong.
The Sandvik rigs are currently being used to prepare dewatering wells to allow construction of 3-4-m sewer pipeline trenches in the first residential areas of construction off the Palm Cove canal.