GRUNDOMAT building the information super highway

05.04.17 - While fibre optic cables to the home are designed to provide access to the latest that technology has to offer, like high speed broadband internet and hundreds of high quality, high definition television programs, the tools that are often used to install those cables are often very basic. One in particular, the soil displacement hammer, has been performing just these types of service installations for over 40 years. While the accuracy of the tool has improved since the early days, the concept behind it has not and today’s crews are improving their efficiency, lowering the restoration costs and generating good public relations through the use of this piece of classic trenchless technology.
Verizon is one of the major telecommunication companies pushing fibre-to-the-premises (FTTP) services. The company began implementing its FTTP program in early 2002. Since then the program continues to expand and now includes projects in several states and large cities like Tampa, FL. In May of this year, Verizon announced that an initial group of more than 40,000 Tampa area households were now able to receive its product offerings through its all-digital fibre optic network. The company had already deployed over 3 million feet of fibre in the Tampa area. By the time the program is scheduled to be complete, five years from now, over 9 million feet (2,750 km) of fibre optic cable will be installed. Installing the conduit that houses the cable is part of Stuart Greenburg’s job. As owner of Arrow Construction, Dunedin, FL, his crews are installing conduit in various locations in Florida, helping Verizon complete its FTTP program. The GRUNDOMAT soil displacement hammer plays a major role in daily operations. Greenburg has been using piercing tools for over 15 years. Over the last five years his crews have been using them on a regular basis. For the Verizon project, they are using them daily. He said, “On a good day we’re trying to install 1,000 feet (305 m) of conduit. If I could use the piercing tool all the time, I would. With a directional drill if we get ten (10) 40-foot (12 m) shots that’s a good day. With piercing tools we can do over twice as much work. We can do 30 in a day with the missiles.”

GRUNDOMAT specialist Jason Land from trenchless equipment manufacturer TT Technologies, Aurora, Ill, supplies the displacement hammer and other pieces of trenchless equipment to Arrow Construction. According to Land in addition to its productivity, minimal disruption is a key benefit of the trenchless tool. He said, “Restoration is a time consuming and expensive process. It can make up almost 80 % of the cost of an installation project. With the cost of restoration so high, trenchless options are extremely attractive, soil displacement hammers especially. Plus the trenchless application is ideal for these last mile operations. Everyday Arrow Construction crews are working in established neighborhoods with driveways, sidewalks and landscaping. Not only are they saving money and time, they’re building goodwill with the residents.”

Arrow Construction partners Steve Vance, Miguel Esquival and Stuart Greenburg have over 18 years combined experience working with telephone, CATV, fibre optics and power industries. Arrow Construction crews have been working on the Verizon FTTP program for several years already. According to Greenburg the project has kept them busy. He said, “We’ve been putting in 8 to 10 hours days and half day Saturdays as well. Our regular activities include stitch boring primarily in front yards and going under driveways. We’ve got so many compliments on our work on this project and we let our work speak for itself. Now we’ve been flooded with calls for other projects. It’s almost at the point where we’re having to turn down work!”

Typically displacement hammers range in size from as small as 1.75 inches in diameter up to 7 inches and can bore accurately up 150 feet in length. A minimal crew compliment is needed to operate a piercing tool and only small entry and exits pits are required for most projects. The tools can usually be fitted with different types of cones or heads for various soil conditions. In addition, piercing tools can be used to perform a standard bore, or they can be outfitted with a range of pipe and cable pulling adapters/accessories to pull in product pipe, conduit or cable while boring.

Land said, “The GRUNDOMAT is very versatile. It can be used for other applications like pipe bursting and pipe ramming. Because the tool can be used in so many ways, it represents one of the most useful trenchless construction tools available. Contractors and utilities can get a lot out of their displacement hammers. For Arrow Construction the tools get put to the test everyday.”

Accuracy, which was once an issue with the hammers of 40 years ago, is not an issue with today's reciprocating chisel head, spring-loaded piercing tools, like the GRUNDOMAT. Greenburg said, “The guys put a level on there and shoot it. We recently bored under a parking lot, two bores at 80 feet and two at 88 feet. The pit was about two-shovel-lengths wide. And we hit it like a directional bore. People associated with the project were telling us, ‘You can’t shoot over 40 feet (42 m) with those missiles.’ I said, ‘Well, we completed two of them before you even got here!’ We’ve proved them wrong time and time again.”

According to Land, the Verizon project is giving the Arrow Construction crews the opportunity to use the piercing tools to the fullest. He said, “Arrow has two 12-man crews boring under driveways and yards everyday. Basically crews are installing single, double and triple conduit runs of inch and a quarter polyethylene. They probably have over a dozen piercing tools and they’re working them constantly.”

Arrow crews are installing conduit for terminal bores and path bores. Greenburg explained, “For the path bores we’re basically feeding the neighborhood. To accomplish that, we’re performing what’s called stitch boring with the GRUNDOMAT. There are small pits on either side of the driveway. You bore from one side to the other. Then you shoot the yard to the next driveway pit. The shots are usually 30 to 40 feet (9 - 42 m) long. With small pits, you’ve eliminated a large portion of restoration.
For the terminal bores, we’re dealing with a vault system. Basically we’re bringing the sub-duct up into a vault system from across the street. So, approximately, and it can vary, you’re placing a vault every 250 feet, (72 m) the conduit is installed to opposing corners and a small 4-inch (100 mm)piece of conduit sticks out in a bed of stone on the surface.”

For a majority of the horizontal boring work, Arrow crews use 2-inch (50 mm) through 3.75-inch (92.25 mm) diameter pneumatic piercing tools. Typically mule tape is pulled in while boring. Once the run is complete, crews pull the conduit in with the mule tape. In certain circumstances they will complete the bore, then attach the conduit to the front of the tool and back the tool through the boring, pulling in the conduit. Depending on soil conditions boring times range from a few minutes to a half an hour.
The Arrow crews, however, are not installing the fibre themselves. They are simply creating the path for the fibre installation. Most of the conduit being installed comes preloaded with mule tape to help facilitate the fibre installation. Greenburg said the installation of the fibre usually occurs within a week of the conduit installation depending on crew schedules. By that time, Arrow Construction crews have moved on to begin boring in the next neighborhood.



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