What a Dragline!

Martin Marietta's Berkeley Quarry Mines Underwater to Keep Afloat

The massive bucket breaks the surface, delving deep below the rich aquamarine to emerge seconds later with 52 tons of rock.

The boom swings to the left and the bucket is dumped over a pile of wet limestone. As the boom swings back toward the water, an end loader steadily loads material that has dried into trucks that then make their way to the plant. On the far end of the pond, a two-man crew drills a pattern of 54 holes, 65 feet below the water line. When the pattern is drilled out, the team will blast again and the cycle will continue.

Plant Manager Lin Kramer (seen below with Driller Dakota Stansell) describes the workflow and, for a moment, a typical morning at Berkeley Quarry sounds a bit more like a night at the ballet.

Lin Kramer speaks with Driller Dakota Stansell.

“It’s an interesting choreography,” he says. “We have a bit of a system to manage and if it’s not managed right, it won’t move forward. We’ve got to keep all of our parts moving and on point.”

While “massive” accurately describes anything capable of lifting 52 tons, the bucket on Berkeley’s Marion 7820 electric dragline is actually pretty average in the electric dragline world.

Still, getting the 1970s-era machine – with its 305-foot boom and 4.2 million pounds of metal – from its Pennsylvania home to Berkeley was no easy feat.

Martin Marietta purchased the dragline in late 2012, about two years after it had been idled. That’s when the challenge began.

The machine was dismantled over the course of several months and, in more than 170 truckloads over a three-month span, shipped more than 650 miles to Berkeley in Cross, South Carolina. It was then refurbished and reassembled before being brought online in August 2014.

The effort may seem a tad excessive until the reasons behind it are fully understood.

“We didn’t have a choice,” Kramer says. “Environmental regulations changed, so if we wanted to mine limestone here, we had to mine wet or not mine at all.”

Regardless of why the electric dragline was brought in, a more important fact moving forward is that it provides several distinct advantages over the smaller, diesel draglines often used in the area.

Scott Ellis, area production manager in the Carolina South District, says previous techniques used to mine the site left a roughly 20-foot layer of limestone behind. With the electric dragline, that layer – totaling several million tons of rock – is now accessible, adding to Berkeley’s reserves.

Other advantages of the electric dragline center on cost and return on investment.

While the Berkeley dragline project – including the machine; the disman­tling, shipping and reassembling; the addition of a number of upgrades to the internal mechanisms; and the purchase of a new Kelly bar drill rig need at the site – rep­resents a substantial capital expendi­ture, the purchase of a used machine over a new one saved the Company tens of millions of dollars, Kramer and Ellis say.

Kramer says the Marion 7820 was constructed using a design from the mid-20th century that was to keep it operating for about 100,000 hours, but that the design has proven so efficient that such machines typically yield more than twice that operation time.

“They really overbuilt these machines,” Ellis says. “Today, we’re finding that we can rebuild one and it’s like new. It’ll last another 30 or 40 years.”The Berkeley Quarry dragline

The success at Berkeley has led leadership in the Mid-Atlantic Division to purchase a pair of similar, though smaller, electric draglines for use at Georgetown II Quarry in Jamestown, South Carolina. One will be operation­al. The other will supply replacement parts when needed.

Kramer, who has spent decades of his life working around draglines, has taken a lead role in the Georgetown II project. When that work is complete, the site will join a select group of Martin Marietta locations utilizing the technology. Others include Bahama Rock and Perry Quarry in the South­east Division, Garwood Quarry in the Southwest Division, and Clarks and Castle Hayne quarries in the Mid-Atlantic Division.

The Georgetown machines will be a good fit, Ellis says.

“They’re going to make Georgetown more efficient,” he says. “They’re going to improve the flow of material through the plant.”

While production and cost are important considerations for any piece of machinery at Martin Marietta, another vital aspect of the dragline is its impact on the people who are expected to use it daily.

Dragline Operator Scott Taylor has 16 years behind the controls of such machines and joined Martin Marietta specifically to work at Berkeley. He says he’s enjoyed every moment of the experience and looks forward to working on the dragline each day.

“This machine is incredible. The technology and the engineering that has gone into it – the amount of power you have with just three fingers and a joystick is amazing,” he says. “To be able to operate this dragline for a living is something else. It’s the pinnacle of my career.”

processing request...