Launch Slideshow

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Utility microsurgery

Utility microsurgery

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    Coring the street in a residential area is done quickly and easily by a two-man crew.

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    The advantages of small keyhole cuts are readily apparent in these two utility cuts, which cause large, unsightly scars in the street.

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    The core from a utility cut is set aside. It will eventually be replaced and fused into place with a bonding material.

Since workers operate at street level instead of down in excavated pits, they no longer risk potential sidewall cave-ins associated with open pits. A keyhole process typically is performed within a work shift, and traffic can resume over the repair in short order upon completion. The community suffers less from traffic disruption. Finally, the utility company saves on street restoration costs and call back costs associated with poor street restoration.

With all of these benefits, it's no wonder that many gas distribution companies have invested in the technology. PECO made an initial investment in the technology about two years ago and worked closely with Omega Tools Inc., the vacuum equipment and extension tool provider, and GTI to launch its implementation effort.

Entry into the world of keyhole technology is an investment of substantial dollars and effort, but several implementation strategies undertaken during a recent pilot program to implement the technology at PECO mitigated some of the investment without negatively impacting performance.

Using modular equipment for coring and vacuum excavation, PECO blended the two modules onto the same truck chassis. This strategy not only eliminated one truck from the initial investment outlay, it also provided a means for reassembling the modules into other truck configurations as the learning process with the technology unfolded. The flexibility of placing the modules on one or two chassis and adding accessories to enhance production proved to be a major advantage in recovering the initial investment quickly. Since the technology implementation changed the way work was scheduled and managed, the modular concept allowed for restructuring the equipment relative to those issues.

Technology development

Keyhole technology continues to develop with the growing sophistication of locating equipment, street coring equipment, and vacuum excavation improvements. The extension tooling and the small-hole processes that can be performed with these specialized tools also continue to expand the technologies applications. Omega Tools, a major development source for small-hole technology tooling and processes, reports that it supports more than 30 infrastructure repair and restoration processes that can currently be performed through the 18-inch diameter holes.

The integrity of the repaired street surface via the reinstatement of the plug is at the heart of the technology's overall viability and cost savings. GTI has been instrumental in assisting the industry in developing and testing all aspects of this technology set. GTI has been working with more than 25 companies in this effort, including working directly with the major manufacturers of the cement-type bonding products that essentially secure the street plug into the original parent street surface.

In a practical assessment of the street restoration process, Omega Tools has more than 4000 street cores reinstated in the past three years in Pennsylvania, reporting zero core failures and inconsequential call backs on repairs. Michael Berlin—senior vice president of marketing, promotion, and governmental affairs of Heartland Cement, one of the major manufacturers of the bonding cement—said his product, called Utili-Grout, “is a patented, rapid hardening, sulfate resistant, general purpose grout that is easily mixed for reinserting cores in either concrete or asphalt streets.”

Utili-Grout has been used to reinstate thousands of cores (plugs) without failure, said Berlin. Minimal failure, however, is partly attributable to adherence to the reinstatement procedure. Although not difficult to perform, reinstatement requires a modest level of attention to the details of mixing the cement bonding material, flowing the bonding material into a properly prepared plug hole, maintaining the integrity of the plug itself, and finishing off the freshly inserted core in the hole.

The cement bonding products are designed as a rapid-hardening compound, said Berlin. This feature provides not only lasting durability and street integrity; it also allows traffic to resume over the repaired site in as few as 30 minutes.

The overall technology continues to advance as more infrastructure repairs and installation processes are developed. In addition, the technology components—especially street coring equipment and vacuum excavation equipment—are improving to provide better operator ergonomics and improved operation throughout seasonal changes. These advances are increasing the technology's overall productivity and return on investment capabilities.