Underground

Isolation of services 

Where possible, essential services MUST be isolated prior to undertaking work that is in close proximity to those services. This includes all underground, concealed and overhead essential services that may be impacted by the work.

All asset owners MUST be consulted prior to any isolation or de-energisation of service.

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How do I locate services?

All essential services (permanent or temporary) at or near the work location MUST be identified prior to any work commencing. Consider using existing As Built drawings and undertaking a visual inspection of the area.

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Where there is a need to verify the exact location of services, in-ground services location technologies MUST be used, ie, cable avoidance tools (CATs) or ground probing radar.

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Current (in date) plans MUST be obtained and referred to when working in a business-as-usual projects and brownfield projects (already developed land) prior to commencing works.

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For greenfield projects (bare undeveloped land), accurate As Built plans MUST be developed as services are installed throughout the project and made available to all on site.

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Any temporary services MUST be considered e.g. temporary power sources for portacoms .

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You can talk with people who have previously conducted underground works in the area, their knowledge may be very helpful.  You can also reach out to the GIS Team by emailing them at gis@contactenergy.co.nz to inquire about the services they have on record, but you MUST not rely on this information alone.

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You can use B4UDig GIS Surveyor for the region or the area that you are working in.

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Protection of services

All essential services MUST be protected from damage while work is being undertaken.

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Where there is a risk of a collision with mobile plant, services MUST be physically protected through the use of: 

• enclosures

• cable trays

• bollards.

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Services MUST have visual identifiers to alert workers of their location, they include:

• tapes

• locations marked on walls

• accurate temporary or as built plans

• tapes placed above services to give an early warning

• marker posts.

Be careful not to damage or move any cables or pipes. Remember, if you expose any long lengths of pipe or cables you MUST provide support to those pipes or cables. Discuss this with the asset owner on how best to achieve this. 

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Safe digging practices 

All essential services at or near the work location MUST be identified prior to any work commencing.

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All asset owners MUST be consulted prior to any isolation or de-energisation of service.

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Any excavation or penetration of ground more than 300mm requires an excavation permit. Once a permit is obtained there MUST be trained and experienced person/s in charge of authorising digging.

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A combination of service location methods MUST be used to help identify where and what the service might be. In conjunction with location technologies and plans, potholes dug by careful hand digging MUST be used to confirm exact location of strategic services before any excavation is commenced to ensure all services are found.

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While hand digging use insulated spades and shovels. Horizontal digging is recommended as the force applied to hand tools can be controlled more effectively. 

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Once using mechanical digging practices, excavate to permittable minimum approach distance (MADs) of the service. Once reached hand dig or hydro excavate.

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Use a spotter when working within or near MADs.

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Consider if you can use hydro excavation?

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If there is any doubt as to where the service are located, stop work, and consult with the asset owner.

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