What must I check before a machine digs?

The sequence, dated

Plant hitting services is the most common of the incidents SafeWork NSW sees in earthmoving, and it says it continues to receive notifications of mobile plant coming into contact with both overhead and underground services. One telecommunication asset owner reported 20,000 strikes per year, resulting in $20 million of damages annually, the same page records, and it warns that the result of an incident involving earthmoving plant or excavations can be fatal.

The four steps below sit in the order the law and Before You Dig Australia’s own guidance put them, and each carries the clock its source attaches. The rules are New South Wales rules, so the sequence runs in Sydney as across the state.

1. The enquiry, before the work is directed or allowed to start. The law’s trigger for this step is the moment someone directs or allows the excavation work to start. Before You Dig Australia’s homeowner pages describe its service as a single point of contact for the underground networks at a proposed site, so a digger does not have to approach the utility organisations one at a time. The same pages say to settle who lodges the enquiry before any contractor or tradesperson begins excavation work on the property. Then the waiting starts, and its length belongs to the asset owners: plans typically arrive within minutes, but the guide asks you to allow up to two business days, and it says plainly that Before You Dig Australia does not send them out itself.
2. The plans, minutes to two business days after the enquiry. The plans come from the infrastructure owners, and they indicate the presence of underground assets only, not exact locations: Before You Dig Australia says to treat them as a guide only. Its homeowner pages are plainer still: a plan is indicative only, it may show a lead-in to the property or a main running through the boundary, and it may hold no specific detail inside the boundary itself. Two housekeeping rules come with them. Make sure every registered member’s plan has arrived and is on site at the project, and if the scope of works changes or a plan’s validity dates expire, lodge a new enquiry.
3. The locating, once the plans leave a position uncertain. Before You Dig Australia says to engage an accredited locator if the asset owner instructs it, or if you need help locating underground assets, and its homeowner tips suggest a skilled locator for the assets on private property. Where a cable’s exact position cannot be determined, the NSW excavation code’s answer is potholing, which it describes as digging with hand tools to a set depth to confirm whether an asset is in the ground at that spot. Two cautions travel with this step: never assume that pipes and cables run in a straight line or sit at a set depth, and read the surface before the machine arrives, for clues such as pits, marker posts, meters and warning signs.
4. The digging, from the machine’s arrival until the excavation is finished. While the machine works, the information has to be within reach. The regulation requires the person who obtained it to give it to the person engaged to carry out the excavation work, and the service’s page on avoiding damage says not to proceed until the relevant information has arrived from every asset owner affected by the project. The record outlives the dig. The regulation requires the information to be available until the excavation work is completed, and for at least two years after the incident if a notifiable incident happens in connection with the work.

SafeWork NSW frames the same duties as a checklist for the person in charge. It reads, in its own words: You must:

• obtain current essential services information where work is being carried out, and any adjacent area, before directing or allowing the work to commence.
• ensure the information is readily available for inspection until the work is completed, unless a notifiable incident occurs then it must be kept for two years after completion of excavation.

The two do not match on one point: SafeWork NSW’s page counts the two years from the completion of the excavation, and the Regulation counts at least two years from the incident. The Regulation is the law.

Before You Dig Australia gives this routine a name of its own, the 5Ps of Safe Excavation, and its page on avoiding damage asks every digger to follow it.

The trench rule at 1.5 m

New South Wales puts one number under the ground for trenches: 1.5 m. A business or undertaking that intends to dig a trench 1.5 m deep or deeper must, as far as is reasonably practicable, secure the work area against unauthorised access, including inadvertent entry, and must minimise the risk of the trench collapsing by making sure all of its sides are adequately supported, by one or more of shoring (with shielding or something comparable), benching, or battering. The regulation states one exception to the support requirement: where a geotechnical engineer’s written advice says all sides of the trench are safe from collapse, that requirement does not apply, and the duty to secure the work area, so far as is reasonably practicable, still stands. The advice must say how long it applies for, and it may carry a condition that specified natural occurrences could create a risk of collapse.

Two more points from the NSW excavation code sit beside the number. One is for the machine at the edge: powered mobile plant should stay back from the edge of a dig unless the ground support system there was designed by a competent person to take those loads, and it notes that, in built-up areas or streets, an excavation may need full or partial sheeting or support, because vehicles moving nearby can make the ground give way. Its summary of what the depth means for a person is blunt: no worker should be in a trench deeper than 1.5 m unless the support has been installed.

The depth also changes the paperwork, on Safe Work Australia’s national guidance. Its list of high risk construction work reads, in its own words: “Some excavation work is high risk construction work. For example, if work is being carried out:”

• in or near a shaft or trench that is 1.5 metres deep, or a tunnel.

What that brings, Safe Work Australia states plainly: a Safe Work Method Statement must be prepared before high risk construction work begins. SafeWork NSW says the same and names the provision, Clause 299 of the WHS Regulations. Underground services have their own line in the NSW excavation code: where the excavation involves them, a Safe Work Method Statement has to be prepared to manage the risks.

What the service is not

Before You Dig Australia is a referral service, not an authority, and its own pages mark the edges. It states plainly that it is not an emergency service, and its own page carries what to do in a life-threatening situation. The homeowner case is the one its tips are written for: it records that householders have dug up underground infrastructure by accident before now, and the results have run to service disruptions, financial penalties, and injuries to the people digging and those around them, and it adds that an asset owner may seek compensation for damage done to its assets.

Underground is only half of the story in a yard with power beside it. SafeWork NSW says overhead powerlines are most often contacted by mobile plant and delivery vehicles, or when something sits too close to scaffolds, and it directs planning to its Look Up and Live tool, which carries exclusion zones and advice. The NSW excavation code gives the machinery its own instruction: specific control measures before an excavator or other earthmoving machine is used near overhead powerlines, and a check with the relevant authority on the approach distances that keep the plant, or anything it carries, clear of them.