With hundreds of US Navy and Coast Guard vessels, container ships, and barges entering and exiting the Port of Virginia every day, the 12 members of a construction crew working on a nearby island are hardly visible to travelers driving across the river on Interstate 664 between Newport News and Portsmouth, VA. The crew’s job is the type of behind-the-scenes activity that plays an important role in helping to keep the 50-foot-deep entrance channel operating as efficiently as possible.
“Our assignment, which began last fall, is to construct a mile-long barrier wall along the north side of Craney Island to curtail erosion,” says Gene Hand, project manager for Precon Marine Inc., the contractor handling the $11.6 million Craney Island Northern Shoreline Revetment Phase 3 project. “The island’s main function is as a depository for material dredged up from the shipping channels,” he says. “This very valuable, 2,500-acre property is officially called the Craney Island Dredged Material Management Area and, if it were to erode away, the impact on the movement of cargo both by the Navy and private firms would be significant.”
The port, one of the nation’s busiest, and the adjacent island are located where the James River, the Elizabeth River, and other smaller rivers meet near Portsmouth. Among the world’s largest natural harbors, the area is called Hampton Roads and is known for its big military presence (Norfolk Naval Station) and huge containerized cargo complex.
The Navy Supply Systems Command Fleet Logistics Center Norfolk is the oldest and largest naval supply center in the world. This location accounts for a substantial amount of marine traffic in and out of the port.
The Port of Virginia operates several terminals in the Hampton Roads area. The volume of cargo is the third highest on the east coast (behind New York/New Jersey and Savannah, GA). Through the first third of 2015, the number of container units entering and exiting the port grew by 8.8%. It is the only East Coast port with congressional authorization for 55-foot-depth channels.
Dredging Disposal
After approval by Congress as part of the River and Harbor Act of 1946, construction of Craney Island was completed in 1957, at a cost of $6 million. It was designed as a low-cost alternative for the placement of dredged material. By having a nearby place to dispose of material, the deep-water channel allowed the port to grow into one of the nation’s busiest.
The site is owned by the federal government and managed by the US Army Corps of Engineers. It has proven to be a valuable long-term disposal area. However, erosion has taken a toll, and it was time to replace the existing, randomly placed concrete rubble along the northern shoreline. The revetment project called for the construction of 4,100 linear feet of shoreline protection, eight breakwaters, and sand fill placed landward of the breakwaters.
To handle the work, the Corps of Engineers hired 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. Precon Marine, which was established in 1993, has two locations in Hampton Roads, VA.
Island Environment
“My first impression of the job was dealing with the environment,” says Hand, who has spent his entire career working in and around water. “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.”
Since September 2014, 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 offloaded by an excavator, placed into articulated dump trucks (ADTs), and delivered to the breakwater job site 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,” says Hand. “Doosan DA30 articulated dump trucks turned out to be the perfect fit for this roughapplication. We put wear plates in the bed of the trucks to absorb most of the abuse. With a month or so to go on the project, we have moved approximately 60,000 tons of armour stone in the trucks. They have held up exceptionally 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 365-net horsepower ADT is known for delivering superior performance in the toughest applications.
When not moving the armour stone, the trucks are hauling sand (reclaimed from dredging material) from the other side of the island to where the breakwaters are being built, a distance of about 1.5 miles. The trucks can travel up to 34 miles per hour and transport material faster than other material-handling machines.
“If we have a lot of rainfall, the roads disappear,” says Hand. “Last winter, which was very rare for this area, we had a six-inch snowfall one day and another seven inches the following day. Then the temperature dropped to 11 degrees Fahrenheit. As a result, the road froze and we had to shut down.”
When the roads are open, the trucks make dozens of trips each day hauling sand. By the time the project is completed, they will have delivered more than 160,000 cubic yards of sand to the breakwaters.
“I had no previous experience with Doosan trucks, but what I have seen is impressive,” says Hand. “This is 100% heavy-duty work. The trucks are durable, reliable, and quiet. They are very strong workhorses. The operators really like them.” Precon Marine purchased the DA30 ADTs from the local Doosan heavy equipment dealership, H&E Equipment, in Chesapeake, VA.
Along with using the trucks 10–12 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 to maneuver through some difficult situations,” says Hand.
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.
In addition to the pair of DA30 ADTs, Precon is also using a Doosan DL420-5 wheel loader on the Craney Island project. This is also Hand’s first experience with a Doosan wheel loader. He says the multitask machine is very tough and responds well to continuous use. It is used with the pallet fork attachment for moving equipment around the job site and offloading trucks, and with a bucket for loading stone. “The wheel loader is very user-friendly,” says Hand.
To complement the Doosan ADTs and wheel loader, the company rented
a third Doosan ADT and a pair of Doosan crawler excavators, a DX350LC-3
and DX350LC-5, to assist with various parts of the project.
While a high volume of marine traffic continues to move through the Hampton Roads harbor every day, the Craney Island revetment project will ensure that the valuable island property will not be going anywhere.
