Trenching Deaths Double Since Last Year

The good news is that trenching injuries are down since last year. The bad news is that deaths in trenching accidents are up. They’ve gone up quite a bit actually; they’ve doubled.

Trench deaths have more than doubled nationwide since last year – an alarming and unacceptable trend that must be halted,” said Dr. David Michaels, assistant secretary of labor for the Occupational Safety and Health Administration. “There is no excuse. These fatalities are completely preventable by complying with OSHA standards that every construction contractor should know.

trenchinginjuries_chart

It starts with education. Check out our five-part series here:

Part 1, Part 2, Part 3, Part 4, Part 5


Trenching and Excavation Safety (Part 5)

Trench Protective Systems

There are four basic ways to protect workers in a trench. Trenches that are more than 20 feet deep must be protected by a protective system that was designed by a registered professional engineer.

  1. Sloping
    The type of soil will determine the ratio of the slope:
    1. Type A soil should have a ¾ to 1 ratio
    2. Type B Soil should have a 1 to 1 ratio
    3. Type C soil should have a 1 ½ to 1 ratio

    If different layers of soil are encountered as you go deeper, the slope must be adjusted in order to have the right ratio for each.

  2. Benching
    Benching follows the same ratios as for sloping with the last 4 feet being straight down (without a slope) and the top of this 4 foot deep trench within a trench being at least 4 feet from the slope of the rest of the trench
  3. Shoring
    Shoring is essentially plating that is held in place with expandable braces. There are different types of shoring systems but the basic system is similar. The plates are lowered in and the brace is expanded until it holds them in place and keeps the soil on either side of the trench from collapsing.
  4. Shielding
    Shields are similar in nature to shoring except that the plates and the braces are permanently fixed together. The braces are not expandable.

Trenching and Excavation Safety

Stumble It! Digg! Add to Mixx! Pownce

OSHA has been keenly aware of the danger to workers in open trench work since it was rated as the fourth deadliest job in the US sometime the middle of the last decade. Collapsing walls that bury trench workers resulting in death and injury continue to plague the water, sewer, pipeline and construction industry.

OSHA comments on this issue: “Because of the continuing incidence of trench collapses and accompanying loss of life, the agency has determined that an increased OSHA enforcement presence at worksites where such operations are being conducted is warranted.”

Because it continues to be one of the highest areas of fatality as well as the one with the highest number of safety violations, OSHA has made it a high priority.

Additional trenching hazards include electrocution, explosions, toxic fumes, and drowning.

OSHA defines “Excavation” as any man-made cut, cavity, trench, or depression in an earth surface, formed by earth removal and a “trench” as a narrow excavation (in relation to its length) made below the surface of the ground. In general, the depth is greater than the width, but the width of a trench (measured at the bottom) is not greater than 15 feet (4.6 m). If forms or other structures are installed or constructed in an excavation so as to reduce the dimension measured from the forms or structure to the side of the excavation to 15 feet (4.6 m) or less (measured at the bottom of the excavation), the excavation is also considered to be a trench.

OSHA provides plenty of help for anyone who is involved in trenching and excavation.

http://www.osha.gov/SLTC/trenchingexcavation/index.html contains etools, quickcards, downloads and much more. Spend some time studying the proposed solutions and answers the include identifying underground cables and utilities, monitoring for harmful gases and displaced oxygen as well as a number of other tools.