Excavation Techniques & Site Management Flashcards

When excavating near an existing underground utility line, what is the minimum hand-digging buffer zone typically required once you are within what distance of the marked utility?

Answer: 18 inches

Most utility safety standards require hand-digging within 18 inches (45 cm) of a marked utility to avoid accidental strikes.

During a trenching operation, you notice the trench walls are beginning to show horizontal cracks. What does this indicate?

Answer: Imminent wall collapse

Horizontal cracks in trench walls are a warning sign of imminent collapse and all personnel must exit immediately.

What excavation technique is best suited for removing material from a confined area where the excavator cannot reposition?

Answer: Radial swing digging

Radial swing digging allows the operator to excavate around the machine's radius without repositioning in tight spaces.

What is the primary purpose of establishing a spoil pile set-back distance from the edge of an excavation?

Answer: To prevent surcharge loads from destabilizing trench walls

Spoil piles placed too close add surcharge pressure that can cause trench wall failure.

When grading a slope with a mini excavator, which bucket technique minimizes surface scarring?

Answer: Using the back of the bucket in a feathering motion

Feathering with the back of the bucket creates a smooth, graded surface with minimal disturbance.

A site plan shows a 1:2 slope ratio for a cut embankment. What does this mean?

Answer: 2 feet horizontal for every 1 foot vertical

A 1:2 slope means for every 1 unit of vertical rise there are 2 units of horizontal distance, creating a gradual embankment.

Which condition would require you to stop excavation and reassess soil classification on-site?

Answer: Soil changes from granular to cohesive mid-excavation

A change in soil type during excavation requires reclassification because sloping and shoring requirements differ between soil types.