By Daniel C. Brown

A worker was recently killed in Madison, WI, because the quick coupler on an excavator accidentally released the bucket. The contractor was using the excavator to install water mains and laterals. An excavation for a lateral had just been dug and a worker entered the lateral excavation to install the pipe, according to a bulletin on the subject by OSHA.

Then the excavator operator changed buckets using a quick coupler. When the operator swung the bucket to continue digging on the main line, the bucket fell loose from the quick coupler, rolled and slid into the lateral excavation, struck the worker, and killed him. The investigation revealed that a locking pin had not been installed on the coupler to prevent accidental release of the bucket.

That is not an isolated incident, OSHA has found. OSHA’s accident data reveal that since 1998, 15 accidents—and eight deaths—have occurred involving the unexpected release of excavator buckets from hydraulic excavators.

Quick couplers are made by various manufacturers. In many cases, manufacturers have recognized the hazard of the bucket or other attachments being accidentally released and have provided users with a retrofit locking pin. Such pins are inserted behind the front lever (stick pin) or the rear lever (link pin) of the couplers to prevent unexpected releases.

Each of two Chicago-area contractors says he is very aware of the danger connected with quick couplers. And both also say they’re careful to prevent the hazards.

“We do an onsite inspection at the beginning of each day, to make sure everything is in good working order,” says Tom Burgin, project manager of the Site Work Division at C.J. Erickson Plumbing Co. The firm runs five site utility crews, and operates two Link-Belt excavators fitted with Hendrix quick couplers. (Erickson also has a number of backhoe loaders, but those don’t have quick couplers.)

Erickson’s quick couplers are equipped with a buzzer alarm that sounds off in the operator’s cab if the clamping mechanism on the coupler is not locked down. As well, Burgin says his company’s operators are trained to test the hydraulic coupling by shaking the bucket over flat ground with nobody around. “The buzzer lets you know if the clamping jaws are closed or not,” says Burgin.

“We had a safety class on quick couplers,” says Tony Friedsam, safety director at Nash Brothers Construction Co. “All of our operators have been made aware of the dangers of the quick couplers.” The company runs 12 loader-backhoes and four excavators. All of the backhoes are John Deere, and some of them have quick couplers.

Friedsam says the backhoes have a locking pin device. “We don’t use the machine unless the locking pin works,” he says. “And we make sure we have a competent person, as defined by OSHA, on the job at all times.”

To prevent quick coupler accidents, OSHA recommends

• inspecting all quick couplers to determine if they are subject to unexpected release hazards;
• obtaining and installing retrofits recommended by the manufacturers, including positive locking pins and other devices that need to be manually installed; and
• using an independent secondary system to retain the bucket or work tool from falling in the event that the primary system fails. The secondary system can be manual or automatic with a verification feature for the user to check for proper attachment.

Ground-Penetrating Radar Featured at Show
Despite broiling summer temperatures, the third annual Underground Focus Live industry trade show recently drew more than 1,600 safety-minded professionals to the Chicagoland Speedway in Joliet, IL. In all, some 90 public and private organizations exhibited at the two-day show, held July 20 and 21. The show sponsor was Underground Focus Events LLC of Bloomington, MN, with lead cosponsors the Chicagoland Construction Safety Council and the Underground Contractors Association of Illinois.

One up-and-coming technology, ground-penetrating radar (GPR) was demonstrated by Dearborn Engineers & Constructors Inc., which operates globally from offices in Bridgeview, IL. The company’s GPR system, which resembles a walk-behind lawn mower, is used to locate underground utilities and embedments in concrete.

Turner Construction Co., a major nationwide contractor, recently named Dearborn as its preferred GPR provider for both underground site locates and concrete examinations, says Dearborn President Michael Walsh. In fact, Dearborn has worked for Turner in five states—Ohio, Kentucky, Illinois, Indiana, and Florida.

GPR works like a land-based “fish finder.” Low energy pulses are emitted into the ground through a sophisticated antenna. Objects beneath the surface and changes in ground conditions reflect energy pulses back to the antenna. The antenna and a video logger collect these data and build 3D images from the echoes. A 3D map and image are then generated, accurately identifying subsurface conditions.

“A critical difference between our [GPR] services and those of one-call locates is that our system actually gives you depth of cover,” says Walsh. The system’s effective depth is altered by the substrate material that it’s working in. The Dearborn GPR system can “see” to a depth of about 4 feet in heavy clay, and up to 30 feet in sand. In clay, the signal gets diffused and will not bounce back as effectively as in sand.

Walsh says Dearborn has tied a Trimble global positioning system to the GPR so that when objects are located underground, they can be pegged to a survey grid.

“Our locates are more accurate than the one-call services,” says Walsh. “Ours provide locates within plus or minus 6 inches, although in heavy clays it’s tougher to locate objects precisely.”

In the past year, Dearborn has performed underground locating services or concrete examinations for 40 to 50 clients nationwide. “Now, we’re looking at opening branch locations,” says Walsh.

Daniel C. Brown is the owner of TechniComm, a communications business based in Des Plaines, IL.

GEC - November/December 2005