Excavation and Groundworks Flashcards
7 cards from real CITB practice questions. Tap to flip, then mark Knew It or Still Learning — missed cards come back until you master them.
Read the first 7 Excavation and Groundworks flashcards as text
What is 'made ground' and why does it present increased risk during excavation?
Answer: Previously disturbed or filled ground that may contain unknown voids, contamination, or unstable material
Made ground consists of previously disturbed or deposited material that may contain unexpected voids, contamination, buried objects, or variable stability, making it more hazardous to excavate than undisturbed natural ground.
What record must be kept following every formal inspection of an excavation?
Answer: A written inspection report (Form F91)
Regulation 33 of CDM 2015 requires that a written report, often on Form F91, is completed by the competent person following each formal excavation inspection and kept on site.
Which factor would MOST increase the risk of an excavation collapse?
Answer: Vibration from nearby plant or traffic
Vibration from nearby machinery, vehicles, or compaction equipment can loosen soil, break down cohesion, and significantly increase the likelihood of excavation wall collapse.
What is the function of a 'trench box' (also called a drag box)?
Answer: To provide a rigid steel enclosure that protects workers while allowing the box to be dragged along as work progresses
A trench box is a prefabricated steel or aluminum frame slid into the trench to shield workers from soil collapse; it can be dragged progressively along as the excavation advances.
Before starting hand excavation near a known buried service, what is the recommended maximum tool to use?
Answer: Insulated hand tools such as a spade or mattock
When working within the zone of buried services, only insulated hand tools should be used to reduce the risk of striking and damaging or cutting through a service, which could cause injury or death.
What does 'angle of repose' refer to in excavation groundwork?
Answer: The natural slope angle at which soil remains stable without support
The angle of repose is the steepest angle at which a given soil type will remain stable under gravity without slipping or collapsing, determining safe batter slopes when shoring is not used.
Who is responsible for ensuring excavations are properly supported and safe for workers on a CDM-notifiable construction project?
Answer: All duty holders including the principal contractor, contractors, and competent supervisors
CDM 2015 places duties on all relevant duty holders; the principal contractor must manage overall site safety, but contractors and competent supervisors also share responsibility for ensuring excavations are properly supported and safe.