Grading and Excavation Contractor

Rockin’ on the Jetty

By Rodney E. Garrett


	Running Smooth

Apart from the many private engineering firms that are involved in marine construction, there is the United States Army Corps of Engineers (USACE). The USACE has a specialized engineering group that is directly involved in the planning, designing, building, and operating of water resources and other civil works projects, including navigation, flood control, environmental protection, and disaster response.

An example of a private contracting company specializing in this segment of the construction industry is Coastal Design & Construction Inc. of Gloucester, VA. Since 1978 the company has established a very good reputation as a contractor capable of taking on challenging marine construction projects. Jeff Wiggins, professional engineer and a project manager for the USACE, Baltimore District, says he can attest to the quality work this contractor has performed for the USACE. “We have been happy working with this company on some of our projects, because Coastal does not bring problems to the project—it solves them. I have worked with Coastal on different projects over the past 13 years, and between the corps and this contractor the problems have always been efficiently solved. Often, Coastal gets the project completed ahead of time. One reason is that this contractor’s management and its excavator operators are very good. The results are high-quality work done within schedule. After all, it is USACE’s responsibility to ensure that a project has favorable results, so we want good contractors such as Coastal.”

Jim Gunn, the forward-thinking founder and president of Coastal Design & Construction, has the belief that it requires top professional people, from the project managers to the equipment operators, if his company is to maintain its good reputation. And it has accomplished this, one project at a time.

One of the more recent projects carried out by the company is the USACE Rockhold Creek, Section 107, Small Navigation Project in Arundel County, MD. Rockhold Creek is 20 miles south of Annapolis and west of the nearby Chesapeake Bay. Rockhold Creek’s east end joins the west side of Herring Bay.

This project calls for the construction of two 900-foot breakwaters. It also calls for the construction of a stone revetment along a section of the shoreline where valuable homes and other real estate are located. According to Wiggins, the revetment functions as a shoreline storm protector that serves in lieu of an attached breakwater. Here, the closest breakwater head is distanced 100 feet away from the shore to facilitate a pass-through for small sailboats. This eliminates having to sail the boats parallel to the breakwater for about 1,000 feet in order to pass around it. It was requested by the people who reside along the shore.

Unlike multiple-built jetty projects, which are typically constructed parallel to one another and perpendicular to the shore, these two offshore breakwaters are built in almost butt-to-butt alignment with one another. Further, they run parallel to a marina, protecting the marina from any high waves created by a storm. There is an open space between the two ends of the breakwaters for enabling small craft to pass through. The heads of the breakwaters are toe to toe, 432 feet apart with a 60-foot wide small craft pass-through channel that runs through the center of the opening.

Choice of Equipment
Like the revetment, the two breakwaters are built entirely of stone. This work calls for the use of cranes or else excavators to place the stones into position as the breakwater construction is advanced.

Coastal Design & Construction used excavators on this project. However, before the contractor could proceed in building the breakwaters, he had to excavate unsuitable ground found at the bottom of the creek where the structures were to be built. This was born out by a pattern of soil-core borings made by the USACE. The soil cores revealed that the top 12-foot layer of soil was unsuitable to serve as a foundation for the breakwaters.

Coastal Design & Construction brought in a subcontractor, who used a duty-cycle crane fitted with a clam bucket to excavate the soil. Upon completion of the excavation, the area was brought back to grade by backfilling it with stone.

Photo: Garrett

Ideal for breakwater installations, an excavator equipped with a bucket and hydraulic thumb allows the operator to place stones precisely.

Excavator or Crane?
Between an excavator and a crane, every contractor will have an opinion as to which equipment is better for building stone breakwaters. Based on his experience, Wiggins says, both kinds of equipment have their place in building stone structures such as jetties and breakwaters. For the mid- to smaller-size stone and where the maximum reach for placing the stone is not very critical, he says the excavator is the better choice. He points out that the stone pieces can individually be placed precisely with the excavator when equipped with a bucket featuring a hydraulic thumb. “The stone can easily be positioned by making multiple directions [using the excavator’s swing movements and movements of the arm, boom, and bucket] to get the best fit in relationship to the other previously installed stone,” he says. “While a crane can be used for placing the smaller stone, the excavator can do it faster. However, many contractors still use cranes because they prefer their reaching and lifting capacities. In fact, when placing extra-heavy stone pieces, the crane is the only option. It all depends on the contractor, too. Nonetheless, unless a contractor has highly skilled operators it does not matter what equipment is used. And poor build quality is not acceptable to us [USACE].”

Coastal Design & Construction prefers Link-Belt excavators and has made this brand its first choice since 1973, when Gunn bought his first Link-Belt excavator from Claude Jones, Link-Belt Mid-Atlantic’s sales representative. It was a model LS 2800. Jones, who still services the account, reminisces about that first excavator sale. “I was after Jim since 1971 to buy a Link-Belt excavator,” he says. “One day I visited with him at one of his projects where he was busy operating a rubber-wheeled backhoe-loader. Right then and there we worked out a deal for the excavator. I knew all along that if I could sell him one excavator we could keep him as a customer, because we offered very good after-sale service. So here we are, over 30 years later and we still are doing business together. In fact, since the first sale, I have sold Jim over 30 Link-Belt excavators.”

Three of the contractor’s Link-Belt excavators are being used on this project. One, a model 460LX, is mounted atop a barge in Herring Bay. Its position is about 300 yards from where the two breakwaters are being constructed. It is here the incoming stone-laden barges are moored for unloading. The barges hold 1,300 tons of stone and cannot be tugged to the breakwater construction site, which is on Rockhold Creek. There is a substantial water displacement when the big barges are loaded with stone, substantial enough to make their drafts too great for the creek, where the low mean water is only 2 feet.

All stone is delivered by barge because the rock quarry supplying it is close by the Susquehanna River in Maryland. Two classes of stone are used for building the breakwaters. One class is made up of stones ranging from 170 to 300 pounds each. This class of stone is used for building the core of each breakwater. A second class ranges from 1,500 to 3,500 pounds and is used for building the armor sections.

Photo: Garrett

Stones are transferred by excavator from a large delivery barge to a small barge for transport to the construction site.

The 460LX excavator is used to transfer the stone from the delivery barge to a barge with a capacity of 200 tons. A bucket-thumb attached to the excavator grabs each stone from the big barge and swings 180 degrees to load it onto the small barge. The operator is careful to pile the two different sizes of stone separately on the barge. Once loaded, a tug boat pulls the small barge, with its moderate draft, to the construction site.

At the construction site’s materials receiving area (at the beginning of the breakwater), a Link-Belt Quantum 4300 excavator is positioned to unload the barge. Each unloading pass made by the excavator is immediately followed by loading the stone into a 25-ton-capacity articulated truck. Once loaded, the truck is driven backward atop the breakwater’s crown to the other end of the breakwater, where a third excavator is placing the stone. It likewise is a model 460LX excavator. First, the core stone is placed, followed by placing the armor stone. This procedure is carried out in stages, with each length of constructed segment limited by the maximum stone placement reach of the excavator. Once a segment is built, the excavator, which also sits on top of the crown, is advanced to the end of the breakwater, and the building of a new segment is started.

Excavator Brand Choice
Coastal Design & Construction’s predominate equipment brand in its fleet is Link-Belt because Gunn is interested in the best results for his company. He continues to buy Link-Belt excavators, he says, because it makes good business sense. Jones is the first to say that his company continually provides efficient service for the contractor. “Jim continues to purchase the Link-Belt line because he finds it cost-effective for his company to do so. I am sure, if we no longer supplied quality products and service, Jim would switch brands to a company that will,” says Jones. All of this said, Dunn points out that using high-performance excavators does not ensure a contractor will be successful in carrying out this highly specialized work.

Still, good operators need good excavators to look good. Joe Benedetta, this project’s manager for Coastal Design & Construction, says the Link-Belt excavators have been high-performing with virtually no unscheduled downtime, including the company’s old Quantum model that has high machine hours on it.

Author and photographer Rodney E. Garrett specializes in construction subjects.

GEC - May 2007

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