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Arkholas New Dredge System Triples Ability to Load Barges

In 2009, Dredging Supply Company delivered a new 22-inch by 20-inch Custom Electric Marlin class, self-propelled, hydraulic cutter suction dredge to Arkhola Sand and Gravel’s operation in Fort Smith, Arkansas.

The barge-loading dredge was designed to integrate with Arkhola’s existing processing plant, while increasing efficiency by allowing continuous loading and repositioning of barges with no dredge downtime.

In Arkhola’s operation, the material is dredged and loaded onto barges moored to the dredge. When a barge becomes full, a tugboat takes the loaded barge to the processing area. From there, the material is blended to the customers’ specifications and loaded onto railcars for transportation directly to the customer. Prior to delivery of the new dredge, Arkhola was using two dredges to perform this work and on average only loading three barges per day.

The new Marlin will replace both dredges, produce more than its predecessors, and load nearly three times as many barges in a day. The barge loading process became dramatically more efficient with Arkhola’s new system. Once a barge is fully loaded, a tugboat moves it out of the way. At the same time, the plant begins to fill another barge while an empty barge is tied to the side of the plant barge, allowing for the seamless loading of barges. Production never stops, and barges are constantly loaded and transported to continue the endless process.

The dredge is designed for one-man operation from a central control room and furnished with a color touch-screen interface, allowing for simple operation. The dredge is fully automated and equipped with pump speed automation (similar to auto-pilot), as well as Prospector, DSC’s proprietary GPS mine management software. Outfitted with a submerged dredge pump, the dredge is capable of digging up to 45 feet deep. Areas that had already been dredged with the old dredges and were determined to be exhausted are now being re-dredged with the Marlin and producing new material.

DSC and Arkhola worked together in designing a 60-foot by 20-foot barge to accompany the dredge and existing sand plant. The barge features four individually-controlled spud carriages, and a pivoting, independently floating dredge front section. The aft barge contains the sand and gravel process plant equipment and serves as the dredge’s propulsion unit. Each of the four spud carriages has the capability of a 10-foot fore and aft movement. Three of the four spuds are required to hold the barge in position, while allowing one spud to reset the carriage position. This design allows the plant barge to advance in a seamless movement through the water during active dredging operations, eliminating the need to stop dredging and manually reposition the anchor cables.

Conventional dredging techniques require swing cables that are connected to manually positioned anchors. As the dredge advances, the cables need to be repositioned and anchored. To eliminate this inefficiency, the floating front dredge is connected to the bow of the 200-foot plant barge section by a pivoting gimbal. This gimbal allows the dredge front section to swing 45 degrees to each side of the plant barge’s heading, resulting in a coverage arc of 90 degrees. Swinging of the front dredge section is accomplished by hydraulic cylinders mounted on the dredge front section and attached to the gimbal mechanism. A spill containment area located below the hydraulic swing cylinders prevents oil from entering the water in the event of a hydraulic cylinder seal failure. The dredge front section floats independently of the plant barge, allowing for a change in draft of the plant barge, while not affecting the draft of the dredge front section. This is accomplished by a horizontal link, linking the dredge front section to the barge-mounted gimbal assembly.

Arkhola Sand and Gravel has been operating in Fort Smith, Arkansas since 1926, and is now expanding its services. The company dredges sand mainly from the Arkansas River. Company president Jerry Goodson says that this new addition will help them operate more smoothly and efficiently. Goodson also says that in the future this new facility will generate more jobs in the river valley area of Fort Smith, Arkansas.

On April 14, 2009, Arkhola hosted an open house to showcase their new dredge. Festivities included lunch and guest speaker Congressman Boozman, followed by a tour of the dredge. Attending the ceremony was DSC’s Charles Johnson (director of Sales), Damon Gonzales, PE (director of Engineering), mechanical engineers Randy Pearson and Jeffrey Stark, and Tan Nguyen (electrical engineer).

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