By Richard J. Mee
Chief, Construction Safety Division

MIOSHA records show that 88 Michigan construction workers have died in excavation cave-in incidents, just since the Construction Safety Division has been keeping records.

Eighty-eight people who left home in the morning for work, never to return alive. This number, of course, does not include the hundreds of thousands who died before we started keeping records. Neither does it include the tens of thousands or hundreds of thousands who were seriously injured or disabled in cave-in incidents.

In 1999, four more workers perished in Michigan trench cave-ins. This tragic upturn in trench deaths came during a period of reduced excavation accidents. In the four previous years, 1995 through 1998, one cave-in death each year was recorded. Statistics reveal a long decline in cave-in deaths with the last several years among the lowest average period.

Excavation and trenching work have proven to be very dangerous. Removing soil to create a trench or other cavity disrupts an equilibrium and will exert powerful forces to return the earth to that condition. Sometimes, natural forces work slowly and man-made scars in the landscape heal gradually over months or years. All too often, however, natural forces begin the healing process in bursts of great force that have no respect for the unfortunate worker who gets in the way.

These bursts of great force are the cave-ins that kill, maim and injure workers. Most soils weigh over 100 pounds per cubic foot, so it doesn't take a large chunk of earth falling off the side of a trench to have the effect of a moving automobile striking a person.

A slab of trench side only one foot thick, six feet long and four feet high can weigh as much as a typical mid-size car. Few cave-in deaths are caused by suffocation; most victims are crushed by the weight of the soil chunks.

Is trenching work inherently unsafe? No, if adequate precautions are taken no one need die or suffer serious injuries from a cave-in. Trench sides can be supported by shoring, a trench box, or can be sloped back to an angle appropriate to the type of soil encountered to eliminate the possibility of a large trench-side collapse. Indeed, the death toll could be eliminated if current MIOSHA standards were followed.

Looming large among the reasons hazardous trenches may still exist in this safety-conscious, modern era, is simply the cost. Excavation and trench safety can be very expensive. Trench box use and shoring installation slow down production and in some cases might result in doubling the time required to complete an underground project.

Sloping the excavation sides out to a safe angle can be even more expensive. In most cases, excavated spoil must be hauled away to distant fill sites and the voluminous trench back-filled with sand, which must be purchased, trucked to the site, and compacted.

Often, unsafe trenches exist because of the lack of a trained, qualified person. The MIOSHA standard requires that an ongoing inspection of an excavation or trench shall be made by a qualified person. The qualified person described in the standard is trained to recognize soil types, understand the characteristic hazards of each one, and design shoring and/or soil sloping as dictated by the unique site conditions.

The qualified person also monitors the progress of the work to identify hazardous conditions as they develop.

Because most soils can support themselves temporarily while a trench is open to install a pipe, inexperienced and uninformed workers may not realize the dangers to which they are exposed. Some clay soils are known to support themselves so well that a mile of vertical-sided trench can be excavated with not even a shovel-full of soil caving off the sides. Then suddenly, a thousand pounds or more can cave in and crush an unsuspecting worker.

Although the numbers of cave-in fatalities have been at lower levels on average during the six to eight years previous to 1999, last year's trend is alarming and cannot be ignored. Enforcement of the standards that apply to excavation and trenching workplaces will be receiving increased attention consistent with the MIOSHA Strategic Plan as the 2000 construction season gets underway. Each employer in the underground industry must pursue the goal of 100 percent compliance with the MIOSHA standards and zero cave-in injures and fatalities.

As tragic as the 1999 deaths were, the real tragedy would be to repeat the agony suffered by the survivors of the workers lost in trenches last year.