Tate, who’s seen most types of drilling conditions and job sites in a long career, was still a little taken aback when, mid-year, he assessed bore holes at a local coal mine that had been started by another contractor more than four months earlier. It was, to put it kindly, a mess.
“The client needed four 22-inch de-watering bores cased with 18-inch casing to 470m for their underground operation,” he said. Lucas wasn’t available at the time the job started, but was called in when things went awry.
“They had a contractor start the project who spent about 4.5 months attempting to drill these bores. We were called in as we have a reasonable history with this drilling discipline. In fact the company has been doing this sort of work for 15 or so years.”
“We had to spend the first three weeks of the job cleaning up – grouting started holes, fishing for shanked bits, etc – then we started drilling in earnest. Once we assessed the job we realised that we required a bigger hammer we approached Atlas Copco and ordered a QL200 hammer.”
For Tate, the QL (Quantum Leap) 200 hammer was a bit of a revelation. Reduced to three bore holes, cased and grouted, due to time and underground issues, the job was finished early in September after some two months of drilling. Lucas used a Schramm TX 130 to drill the holes.
“Considering the start we had to the job, the drilling overall went well,” Tate said.
“The QL 200 was pulling 100m-plus shifts – exceptional considering the diameter of the hole.”
“At 22-inch diameter you have a water volume of 245 litres a minute by the time you get to 470m, so you potentially have a fair bit of water you’re trying to move and hammering a 22-inch face at the same time.”
“We would have been happy with 70m a shift. In the past with the competition’s 17-inch tooling we tended to get about 100m a shift at half the depth.”
“This [drilling with the QL200 hammer] certainly adds another string in our bow.”
“In the past we have stuck to 20-inch diameter maximum, but with the QL200 it opens up more options. It’ll drill to 28 inches comfortably.”
“There aren’t many drilling contractors that can offer that range of diameters.”