Bulk Excavations

Consider:

• Potential impacts on an adjoining property, particularly concerning drainage or collapse

• Instability to adjoining or nearby structures

Any excavation below the level of the footing of any structure, including retaining walls that could affect the stability of the structure, must be assessed by a competent person and secured by a suitable ground support system, which has been designed by a competent person. Suitable supports to brace the structure may also be required and will be identified by a competent person

Proprietary documents (detailed drawings / specifications, details for use / storage / precautions, criteria for rejection)

Element documents

• Proposed sequence of work and SWMS

• Stabilisation methods (temporary and permanent)

• Signed copies of any –

  • Changes made to specifications and/or signed instructions, advice or diagrams made or issued by an engineer

  • Notification to the relevant authority for works

  • Exemptions from the requirements of regulation granted by any authority

  • Inspection reports if required

  • Any report, licence or authority required for carrying out construction work

Planning for the work should include the primary contractor, geotechnical consultant (or appropriate Engineer as appropriate)

Assess intended site limitations. Check:

• Layout is suitable

• Overhead obstructions (including power lines)

• Sufficient delivery access

• Sufficient working room.

Working alone:

• Ensure a second person knows your location and expected time of return

• Use mobile phone, telephone, or radio to periodically check-in

• Communication equipment within easy reach at all times

• Take extra care to work safely and methodically

• Have first aid kit readily available and stocked appropriately

• Where the risk assessment has identified particularly high-risk tasks, utilise a second person (buddy) to assist or backup

  • Do not expose both people to the hazard simultaneously. The second person should be within sight but safely removed from the immediate area

The ‘buddy’ must be trained in the specific activities the worker he/she is observing for is undertaking, be properly equipped with emergency equipment, and be capable of undertaking pre-planned rescue or emergency operations where needed. If it is safe to do so.

Implement a site-specific Trench Collapse Emergency Response Plan

Emergency plan to consider unexpected incidents, such as ground slip, flooding, gas leaks, and workers' rescue from an excavation.

Ensure underground services identified and marked accurately for depth and position:

• Contact Dial Before You Dig

• Use an accredited cable locator contractor to test the area

• Contact relevant authorities/companies for ‘as constructed’ plans if necessary

• Hand excavate using a shovel to locate services and mark out before any trenching or battering works

• Use “Potholing” techniques as required:

  • Use extreme care when working near gas mains

  • When using hand prodders to locate pipes, do not use hammers or other implements

Mark all exposed services with flags or devices that can be readily seen

Ensure all marked services continue to be visible for the duration of the work.

Ensure work is not conducted in close proximity to electrical power lines. Check for:

• Overhead power lines (including high and low voltage distribution conductors)

• Single wire earth return (SWER)

• Service cables to premises

• Communications cables

• Electrical transformers (mounted lower than cables)

Identify the maximum range of equipment and how close equipment or load can come to an asset (known as a design envelope). The following dimensions are taken from the closest point of an extended component of the machine, e.g. extended long reach boom

In general, for up to and including 132,000 volts:

• 3m above, either side and below power lines is No Go Zone

• Between 3-6.4m of power lines, a Spotter is required

• Further than 6.4m of power lines is an open area

• No work to be conducted within a 10m radius of the SWER transformer.

No work to be conducted within Minimum Clearance Zones without written permission from the power supplier.

Approach distances will vary based on the voltage level of the live electrical apparatus. Always contact your local power asset owner for information before commencing crane operations if unsure.

Determine if the excavation is a confined space; if so, ensure a separate, dedicated SWMS for working in a confined space and that workers/employees have relevant training.

Note: A confined space is defined as an enclosed or partially enclosed space that is likely to be a risk to health and safety when a person’s head or upper body is within the boundary of the confined space because of:

• An atmosphere that does not have a safe oxygen level, or

• Contaminants, including airborne gases, vapours and dust that may cause injury from fire or explosion, or

• Harmful concentrations of airborne contaminants.

Additional Spotters may be needed to be available to ensure vehicles/plant/equipment/materials and workers do not breach exclusion zones.

Plant, equipment, vehicles and people will cast shadows, and allowance must be made to install and/or move portable lighting to reduce dark zones as required.

Luminous (fluoro) triangles/bollards to be positioned to assist with traffic management and worker zones wherever possible. For example, mark out the load/unload area's perimeter to help guide drivers and warn workers on the ground of moving vehicles.