Prospan pneumatic shoring from Prospan Manufacturing Co. is designed to meet OSHA excavation standard 29CFR 1926.650 that governs the safety of workers in trenches five feet or deeper. While OSHA also recognizes sloping and shielding, those methods aren’t always practical, says company president James Sullivan.

To meet OSHA sloping requirements, cities would have to remove the street on most digs, and the trench wall would extend to the front steps of homes, he says. Shielding or trench boxes provide a more workable option but can be time-consuming to install and at times, impossible to place.

“If they were the only utility in the trench there would be no problem,” Sullivan says. “But a lot of times the sewer or water pipe runs one direction and the gas, telephone and fiber optics the other. You can’t lower the trench box because it hits other utilities, especially in newer communities and subdivisions.”

The use of timbers and hydraulics for shoring has been a safety standard since the 1970s.

“Shoring works by having direct contact with the trench wall,” Sullivan says. The Prospan shoring uses an air-driven system. When brought up to pressure, the shoring compresses the earth, creating an arch effect (soil arching).

“It’s like a shotgun blast that’s very focused at the point of contact with the trench wall,” says Sullivan. “For example, you put the shoring in at 120 to 150 psi, and it compresses the earth, and the compression rapidly fans out in all directions.” As long as workers are between two columns of shoring, they are protected by this soil arch. Except for certain soil situations, the system does not require the use of plywood.

“We’ve taken away most of the excuses for not using a protective system,” Sullivan says. Compressed air extends the system’s internal piston. Once the system is locked in place with a steel pin, pressure is released, creating a fixed mechanical strut. The shoring installs in minutes.

Made of anodized aluminum and stainless steel, the shoring is available in four sizes, spanning 21.5 to 105 inches and weighing 15 to 32 pounds. A variety of extensions and end attachments are available for greater distances and various applications. 888/413-8100; www.prospanshoring.com.