Features

Trenching and Excavation Safety: Part 2, The importance of OSHA’s general requirements

As discussed in Part 1 of the series, working in trenches and excavations is potentially one of the most hazardous types of work in the construction and utility industry. Each year, as many as 400 workers are killed, and several thousand are injured in the U.S. Most of these workers have received no training, and the trenches and excavations in which mishaps occur are relatively shallow (five to 15 feet deep).

The General Requirements section of OSHA’s 29 CFR 1926, Subpart P – Excavations, addresses a number of “common sense items” related to trenches and excavations.

SURFACE ENCUMBRANCES

These are described as telephone poles, trees, fire hydrants, street signs, sidewalks, curbs and gutters, and similar objects adjacent to an excavation. They should be removed or supported to ensure their stability and safeguard employees.

UNDERGROUND INSTALLATIONS

These include underground utilities such as sewer, gas, water, telephone and electric lines. Utility companies must be contacted within established or customary local lead times, advised of the proposed work, and asked to establish the location of the utilities prior to the start of actual excavation. All underground utilities must be protected, supported, or removed to protect workers.

ACCESS & EGRESS

These are just fancy words for getting in or out of an excavation. Trenches and excavations deeper than four feet require a means of access and egress. Each worker must be within 25 feet of a ladder, ramp or stair. The means of access and egress must be within a protected area.

FALLING LOADS

Workers are not permitted underneath overhead loads. In addition, employees must stand away from equipment being loaded or unloaded from vehicles.

WARNING SYSTEMS FOR MOBILE EQUIPMENT

When equipment is operated near the edge of an excavation, and the operator does not have a clear and direct view of that edge, warning systems — such as barricades, spotters or stop logs — are required.

HAZARDOUS ATMOSPHERES

This section of the OSHA Standard is designed to protect workers from so-called “bad air.” Concerns include too little oxygen, too much oxygen, flammable gases such as methane and natural gas, and toxic gases such as hydrogen sulfide or carbon monoxide. Testing and the use of ventilation equipment are two of the most common, and important, methods of addressing hazardous or potentially hazardous atmospheres.

WATER ACCUMULATION

Employees must not work in trenches or excavations where there is accumulated water, or where water is accumulating, unless adequate precautions are taken. If the excavation work interrupts the natural flow of surface water, then diversion ditches, dikes or other means may be required to keep water out.

ADJACENT STRUCTURES

The stability of sidewalks, streets, adjoining buildings, walls and other structures can be endangered by excavation operations. Specialized shoring systems, bracing, or underpinning may be required to ensure the stability of these structures and protect employees.

LOOSE SOIL OR ROCK

Spoils and equipment must be set back at least two feet from the edge of the trench or excavation.

INSPECTIONS

A properly trained and authorized “Competent Person” must inspect the excavation daily, prior to the start of work, as needed throughout the shift, after rainstorms, and following other hazard-increasing occurrences. The “Competent Person” must check adjacent areas, protective systems (before and during use), for indications of possible cave-ins, and hazardous or potentially hazardous conditions.

VEHICULAR TRAFFIC

Workers exposed to traffic must be provided with, and must wear, warning vests or other highly visible garments. Signs, signals, barricades and/or flagmen may also be required.

FALL PROTECTION

Walkways with standard guardrails are required when employees or equipment cross over excavations. Wells, pits, shafts, etc., must be barricaded or covered.
Paying close attention to each of these important potential dangerous circumstances will help insure worker safety, as well as help contractors and utilities “stay legal” with OSHA.

Editor’s Note: This is the second of four articles in this series that discusses specific steps that contractors and utilities can take to help insure the safety of their personnel. Obviously, this is an overview of the subject. It is impossible to properly cover the topic in just four relatively short articles. Contractors and utilities involved in underground work will need additional training to insure worker safety.

Coming in the next issue: Soils Analysis

David V. Dow is co-founder and Vice-President of TrenchSafety and Supply, Inc. Learn more about his company at www.trenchsafety.com.