Excavation Safety – Key Terms

Vocabulary flashcards covering key terms from the Excavation Safety lecture notes.

Excavation

An opening created by removing earth to perform work below the ground surface (e.g., foundations, trenches, tunnels).

Trench

A narrow excavation with vertical sides used for installing utilities or foundations; often requires protective systems.

Cave-in

Sudden collapse or movement of soil/rock into an excavation, risking worker safety.

Soil testing

Testing performed by an accredited soil testing firm to identify soil type and strength and to determine protective measures.

Stable Rock

Natural solid mineral matter that can be excavated with vertical sides and remain intact.

Type A soil

Cohesive soil with unconfined compressive strength of 144 kPa or greater (e.g., clays and clay loams).

Type B soil

Cohesive soil with UCS greater than 48 kPa but less than 144 kPa (e.g., silt, sand, loams).

Type C soil

Cohesive soil with UCS 48 kPa or less (e.g., gravel, loamy sand, submerged soils).

Surface encumbrances

Objects on or near the ground surface (fencing, piping, structures) that must be removed or supported before excavation.

Utilities

Underground or overhead services located before digging; require deactivation, protection, or removal as needed.

Access/Egress

Safe entry and exit from an excavation; a ladder or other safe access within 25 ft (8 m) of a worker.

Barricades

Barriers used to prevent unauthorized access to excavation edges and work zones.

PPE

Personal protective equipment required for workers (hard hats, safety boots, high-visibility clothing, etc.).

Competent person

An individual designated to supervise excavation safety and perform daily inspections, recognizing hazards and protective needs.

Excavation safety inspection

A thorough check of the site, excavations, adjacent areas, and protective systems for hazards before, during, and after work.

Hazardous atmosphere

An atmosphere that could cause harm (e.g., gases, low oxygen); requires monitoring and testing.

Ventilation

Movement of air to displace hazardous gases; consider gas density and adequate volume to reduce concentrations.

Water accumulation

Water in or around the excavation; managed by pumping, runoff control, and possible dewatering.

Adjacent structures

Nearby buildings or structures whose stability must be maintained via shoring, bracing, underpinning, or PE evaluation.

Contributory factors in excavation collapse

Factors such as water, improper sloping, improper soil impoundment, equipment parking, barricading, and training deficiencies.

Maximum allowable slopes

Slope ratios permitted for different soil types to prevent cave-ins; note applies to depths under about 20 ft.

Sloping

A protection method where trench sides are inclined to a safe angle to prevent collapse.

Benching

A protection method that creates steps (benches) in the trench wall to stabilize it.

Shoring/Timbering

Support for trench sides using timbering to prevent movement and collapse.

Sheet Piles

Vertical piles used to retain soil around an excavation.

Shielding

Use of trench shields (trench boxes) to protect workers from cave-ins.

Dewatering system

System to remove groundwater to keep the excavation stable (e.g., pumping).

Protective systems

Methods or structures (sloping, benching, shoring, shielding, dewatering) used to prevent cave-ins.

OSHA/OSH requirements (Rule 1410/1413)

Standards governing construction safety and excavation safety requirements.

Public protection & traffic control

Measures to protect the public and manage site traffic, including barricades and signage.

Experienced supervisor

An experienced and trained worker designated to directly supervise each excavation project.

Daily site inspection

Daily checks by a competent person of excavations, adjacent areas, and protective systems for hazards.

Equipment & handtools

Common tools used in excavation work (e.g., backhoes, bulldozers, loaders; shovels, picks, pneumatic hammers).

Surface hazards

Hazards at the surface such as utilities, encumbrances, traffic, or falling loads that can affect excavations.