Trenching, Shoring and Excavations

Classify soil for trenching and shoring as solid rock, type a cohesive soil, type b, or type c by unconfined strength thresholds, using a penetrometer to guide safety decisions.

Classify soil quickly using plasticity, thumb penetration, and pocket penetrometer tests. Take fresh spoil pile samples to determine soil type (A, B, or C) and guide trenching decisions.

Define granular and cohesive soils, noting that granular soil, like sand, falls apart when molded and lacks clay, while cohesive soil, rich in clay, holds shape and resists compression.

classify soil safety by treating all soil as type c and applying protective measures, then visually inspect the soil and spoil pile for water, fissures, and layering.

Competent persons perform safety checks at shift start and after rain, rechecking soil samples with plasticity tests or pocket penetrometers, and inspecting barriers, shoring, and PPE, evacuating if hazards arise.

Provide safe access in and out of trenches with ramps, stairwells, or ladders, follow four-foot depth and 25-foot length rules, ensuring two-part ramps stay connected, uniform, and slip resistant.

Prevent 95% of deaths in trenches and excavations by using protective systems like shoring, sloping, benching, and shielding; classify soil (type C) and take personal responsibility to stay safe.

Explore how trench and excavation collapses occur, from spoil pile slides to lip slides, belly slough, boiling, and heaving, and learn to evacuate at signs of trouble.

Identify surface encumbrances and subsurface installations near trenching sites to prevent cave-ins. Notify owners within ten feet and preplan to avoid damage to footings, water, sewer, and electrical lines.

Identify high priority subsurface installations—gas lines, petroleum and hazardous material pipelines, pressurized sewage lines, and high-voltage conductors—through a competent person.

Understand shielding and shoring for trench safety, including cross-member types like timber, aluminum hydraulic, trench shields; ensure 25 ft access and 18 in top clearance.

Learn protective measures for excavation safety, including sloping for type a, b, and c soils. Understand benching limits and the need for a professional engineer beyond 20 ft.

Assess the site with a competent person, classify soil daily, and keep spoil piles away from trench edges while ensuring PPE, fall protection, and shielding or shoring to prevent cave-ins.