Hard Rock

The success of Gunlake Quarries starts with the extraction of hard rock.

Australia is land of volcanos, or more specifically, the plugs remaining from volcanic activity where the surrounding area has been eroded by wind and water. Fortunately, they no longer erupt in our country, but, nonetheless, if we trace our history back by millions of years the NSW Southern Highlands would have been pretty active when it came to volcanos belching forth smoke, gas and lava.

Fast forward to today, and down in Marulan, NSW, the volcanic activity of prehistoric times has resulted in a thriving business surrounding the extraction of what geologists call pyroclastic rock.

Kenworth-Trucks_Hard-Rock_GunLake-Quarries_2Gunlake Quarries and Gunlake Concrete are divisions of an Australian-owned, independent company that draws on three generations of experience supplying the Australian construction industry.

Construction of the Gunlake Quarry in Marulan was set up in exploration in 2006, and started quarrying in 2009. This newly-built quarry produces a wide variety of premium bulk aggregates for concrete, construction and asphalt, and specified and non-specified road base. It also supplies specialist aggregate and materials for use in the Gunlake Concrete business, which has depots at Narellan, Glendenning, near Smeaton Grange and Silverwater.

Trevor Dennis, manager of the Gunlake Quarry site at Marulan, explained that pyroclastic rocks are formed by the accumulation of material generated by explosive fragmentation of previously solid rock during a volcanic eruption.

“It’s the flash that flies out of a volcano and lands in layers. The fault line we are excavating in the Southern Highlands extends in a circle that moves through the Blue Mountains and extends as far as Hawaii.

“As the flash blasted out of the volcano, cooled, and solidified, it produced extremely hard material that is ideal for road or rail base aggregate and for making concrete.

“It’s a hard rock product that we extract by drilling and blasting. We then crush it through the big primary crusher and then subsequent crushers to reduce it to 20 mm for use as general aggregate, or down to 4 mm for use as manufactured sand. It’s a very sustainable product,” said Trevor.

The life of the quarry at curreKenworth-Trucks_Hard-Rock_GunLake-Quarries_8nt estimates is at least over 200 years, and material currently being extracted is from a seam 130 metres wide, with an estimated depth of 2.0 km.

With much of the material carted from the quarry being destined for the company’s own concrete plants in Sydney, Gunlake Quarries has recently taken delivery of two new Kenworth SAR prime movers complete with B-double Stag trailers built by Sloanebuilt of Smeaton Grange.

“When carting to our own plants it makes it easier to have your own fleet. It can be an in-house cost rather than using someone else. Over the years, the family has always had their own fleet of trucks – we drill, we blast, we put it in concrete,” said Trevor.

Driver Kevin Bailey only recently joined Gunlake Quarries after working for a local operator in the region for the past 14 years. His obvious professionalism was rewarded by being one of just two drivers allocated to two brand-new Kenworth T409 SAR prime movers, each hauling two new B-double Stag design tipping trailers manufacturer by Sloanebuilt.

“I’ve been driving trucks for 30 years,” said Kevin.

“It’s all I know. As a young 18-year-old I drove a little Isuzu for a hardware store. I’ve been in and out of trucks all my life. My grandfather drove, and my great grandfather drove. I’ve got photos of my great grandfather at the main street of the Oaks with nine Clydesdales he used to pull iron ore out of the Burragorang Valley. Transport has been in the family for generations.

“I am very, very lucky in that regard. I am the second driver the family owners have hired for this type of work. The family has transport in their blood,” he added.Kenworth-Trucks_Hard-Rock_GunLake-Quarries_5

Supplied through Lloyd Moran, truck sales specialist at Kenworth dealership Gilbert & Roach of Huntingwood, the pair of new T409 SARs features the latest Cummins ISXe5 engines with Eaton UltraShift two-pedal automated manual transmissions.

With a GCM of 97,tonnes, maximum power of 431 kW (550 hp) is produced at 1,800 rpm, with peak torque of 2,508 Nm rated at 1,200 rpm. The steer axle is the DANA E14621 with a 6,700 kg rating on a Kenworth 7.2-tonnes-rated leaf spring suspension, while the drive axles are Meritor RT46-160GP units on a Kenworth Airglide 460 tandem suspension. The drive axle ratio is 4.3:1.

“In recent years I’ve driven two Cummins ISX EGR-only engines, plus a CAT C15 for a few years, then I drove a Mack Super-Liner also fitted with an ISX EGR engine, but with the first particulate filter they brought out,” said Kevin.

“The ISXe5 engine with AdBlue definitely runs cooler and is a little more responsive. The AdBlue use is surprising, I thought I would only be getting one week (tank capacity), but I would probably get two weeks out of a tank.

“They do run a lot cooler and the Horton fan is not screaming its head off. I hated the concept of automatic transmission, but, I tell you what, I love that. I had a pet hate with automatics but this is great. It’s all concrete running on freeways. We are driving into the concrete plants, tipping on concrete, no dirt, doing a U-bolt, into D, and then away again.

“Each day I cover two runs to Glendenning from Marulan, and then another to Smeaton Grange. In a twelve and a half hour day you’ve done 900 K’s, and then you are home each night. I think I am set for the next 20 years,” he added.Kenworth-Trucks_Hard-Rock_GunLake-Quarries_11

The Gunlake Concrete fleet boasts the largest number of eight-wheeled agitators in the country, with the current mixed fleet comprising Ford, Mack and Kenworth.

Some of the more recent acquisitions have been two Kenworth T359A units powered by Cummins ISLe5 engines and with Allison MD3200P fully automatic transmissions, also supplied through Kenworth dealership, Gilbert & Roach of Huntingwood.

With a GVM of 28.5 tonnes, maximum power from the ISLe5 engine is 250 kW produced at 2,100 rpm, and peak torque of 1,500 Nm is rated at 1,300 rpm. The front suspension is the Kenworth load-sharing twin-steer design using DANA E13221 steer axles with a combined rating of 12,000 kg. The drive axles are again DANA units, using the DD/RDH40P road-friendly Kenworth Airglide 400 tandem air suspension with a Spicer 1710 tailshaft. The drive axle ratios are 5.57:1.

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