CITB Specialists Excavation and Groundwork Safety

Question 1

Before a specialist contractor begins excavation work, what must be done to identify underground services?

Accepted Answer

Obtain service plans from utility companies, carry out a CAT and Genny survey, and use safe digging practices

Answer

Ask local residents if they know where pipes are

Answer

Dig a trial hole with a mechanical excavator

Answer

Only check for electricity cables as they are the most dangerous

Question 2

At what depth must an unsupported excavation in granular soil generally be considered as requiring engineered support under UK guidance?

Accepted Answer

No specific depth; a risk assessment must determine the need for support in all cases

Answer

Any depth over 3 metres

Answer

Any depth over 1.2 metres

Answer

Only excavations deeper than 5 metres

Question 3

How often must a specialist excavation be inspected by a competent person under the Construction (Design and Management) Regulations 2015?

Accepted Answer

At the start of each shift before work commences, and after any event likely to have affected stability

Answer

Once a week

Answer

Only after heavy rainfall

Answer

Monthly by a structural engineer

Question 4

What is the primary purpose of installing trench sheets and walers in a specialist deep excavation?

Accepted Answer

To prevent collapse of the excavation sides and protect workers from being buried

Answer

To keep the trench dry

Answer

To provide a working platform at the base

Answer

To mark the boundaries of the excavation

Question 5

A specialist groundwork supervisor notices that spoil from an excavation has been placed at the edge of the trench. What is the hazard and the correct action?

Accepted Answer

The weight of the spoil surcharges the trench sides, increasing collapse risk — it must be moved back at least 1 metre from the edge

Answer

The spoil may get wet; cover it with sheeting

Answer

The spoil is untidy; it should be spread evenly

Answer

No action required if the trench has support

Question 6

What precaution must a specialist contractor take when excavating near a building foundation?

Accepted Answer

Ensure the excavation does not undermine the foundation — use a design that maintains the bearing capacity of the soil supporting the building

Answer

Work quickly to minimise disruption

Answer

Only excavate during business hours

Answer

Place a fence around the excavation