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Serious equipment required for shoreline protection project

Winter 2016

You cannot have a picnic on Craney Island, and working there is no picnic either. The weather can be dreadful, the bugs pose an annoying problem, and if you are doing a construction project you had better bring along some reliable, heavy-duty equipment.

The island, located off the shore of the Hampton Roads area of Virginia, was constructed in the 1950s as a low-cost alternative for the placement of dredged material to keep the 55-foot-deep channel open for vessels, container ships and barges. By having a nearby place to dispose of material, the channel allowed the Port of Virginia to grow into one of the nation’s busiest.

Over time, erosion took its toll and recently the U.S. Army Corps of Engineers, which manages the island, decided to replace the existing, randomly placed concrete rubble along the northern shoreline. The contract was awarded to Precon Marine, a diversified contractor specializing in heavy marine construction, waterfront construction and related services. The company has a successful track record in major bridge, pier and bulkhead rehabilitation work and underwater utility installation.

The revetment project on Craney Island called for the construction of 4,100 linear feet of shoreline protection, eight breakwaters and sand-fill placed landward of the breakwaters. For Precon Marine, the job required some serious equipment.

“My first impression of the job was dealing with the environment,” says Gene Hand, Precon Marine’s project manager for the $11.6 million project. “The island is exposed to wind and storms on all sides. It is hot in summer, cold in winter. There is really no way to get out of the harsh weather. Along with abundant wildlife and birds, the place is overrun with bugs and insects. It is not the ideal location.”

Nevertheless, Precon Marine has been working around weather-related obstacles to build the breakwater structures. They consist of large armour stones and plastic baskets — commonly known as “mattresses” — filled with medium-size core stones, along with sand hauled in to construct a peninsula out to each breakwater.

The armour stones, which are resistant to wear and erosion, are delivered by barge down the upper James River from a nearby quarry. They are off-loaded by an excavator, placed into two Doosan DA30 articulated dump trucks (ADTs) and delivered to the breakwater jobsite or stockpiled for later use.

“Each stone weighs about 500 pounds, so one of our requirements was to use top-of-the-line, heavy-duty trucks,” Hand says. “The Doosan models turned out to be the perfect fit for this rough application. We put wear plates in the bed of the trucks to absorb most of the abuse. We have moved more than 60,000 tons of armour stone in the trucks. They have held up very well.”

The DA30, with a 23-cubic-yard body volume capacity, is capable of moving a significant amount of material every day, then dumping it from the truck box with a standard scissor-type tailgate. The high-production ADT is known for delivering superior performance in the toughest applications.

When not moving the armour stone, the trucks haul sand (reclaimed from dredging material) from the other side of the island to where the breakwaters are being built, a distance of about 1½ miles. The trucks can travel up to 34 miles per hour and transport material faster than other material-handling machines.

When the island roads are not shut down by heavy rain, the trucks make dozens of trips each day hauling sand. At the completion of the project, it is expected that they will have delivered more than 160,000 cubic yards of sand to the breakwaters.

“I had no previous experience with Doosan trucks prior to this assignment, but what I have seen is impressive,” says Hand, who has spent his entire career working in and around water. “This is 100 percent heavy-duty work. The trucks are durable, reliable and quiet. They are very strong workhorses. The operators really like them.”

Along with using the trucks 10 to 12 hours a day, the operators need the skill to negotiate the trucks on the breakwaters to dump the base material. “The trucks are very easy to operate and maneuver through some difficult situations,” Hand says.

A free-swinging rear tandem bogie helps to maintain ground contact for all six wheels for a smooth ride and good traction in soft and wet ground conditions.

The DA30 ADTs were purchased from the local Doosan heavy equipment dealership, H&E Equipment, in Chesapeake, Virginia. That is the same dealer who delivered another valuable machine — a Doosan DL420-5 wheel loader — that is used with the pallet fork attachment for moving equipment around the jobsite and off-loading trucks, and with a bucket for loading stone. Precon Marine also rented two Doosan crawler excavators, a DX350LC-3 and DX350LC-5, to assist on the project.

This was also Hand’s first experience with a Doosan wheel loader. He says the multi-task machine is very tough and responds well to continuous use. “It is very user-friendly,” Hand says.

Whether it is ADTs or wheel loaders, Doosan has demonstrated how durable equipment pays off in difficult working conditions.