Underground Service Locating in Melbourne: A Practical Guide

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Underground service locating turns a plan set into usable field evidence. For a Melbourne excavation, design or investigation, the useful question is: what evidence do we have for each service in the actual work area, what are the limits of that evidence, and what must happen before the next activity starts?

HR Utilities provides utility locating services and Melbourne-specific support from its Huntingdale team. This guide explains the stages so project managers, supervisors and designers can request the right scope.

Start with the work area, not the whole property

Mark the proposed trench, bore, footing, pile, saw cut or excavation on a plan before requesting the locate. A clear work footprint lets the plan reviewer and field team focus on relevant crossings, access points and uncertainty.

Provide:

• the site address and a marked-up work area
• the activity, depth and planned plant
• current BYDA responses and asset-owner instructions
• site or as-built plans, including private services
• known pits, valves, meters, switchboards, drains and connection points
• required outputs, such as paint marks, a PDF sketch, survey pickup or CAD/GIS data
• the date the information will be used and any traffic, access or permit constraints

This information also helps separate a quick field mark-out from a design survey or a targeted service-proving investigation.

What BYDA plans do and do not tell you

Before You Dig Australia’s duty-of-care guidance says to lodge an enquiry before the job, check that every listed asset owner has responded, read each owner’s instructions, note permits and lodge a new enquiry when the scope changes or plan validity expires.

BYDA also states that owner plans detail the presence of infrastructure rather than its exact location, and generally do not show the whole domestic connection. Private, altered, abandoned or undocumented services may therefore require other records and field investigation.

Keep the enquiry confirmation and all owner responses together. A coloured line on one plan should never be separated from its legend, notes, validity period or duty-of-care document.

Read the site before switching on equipment

The WorkSafe Victoria and Energy Safe Victoria guide recommends a record search followed by a site assessment. Surface evidence can confirm, challenge or add to the plan picture.

Look for:

• pits, covers, valves, hydrants, meters and marker posts
• cables, conduits or pipes entering buildings or the ground
• inspection openings, drains and maintenance holes
• repaired pavement, trench scars and changes in surface material
• overhead assets and access restrictions that affect the proposed work

Record evidence that does not agree with the plans. A missing expected service, an extra pit or a route that cannot logically connect deserves investigation, not a neat line drawn through the gap.

Match the locating method to the service

Electromagnetic locating

Electromagnetic locating traces a signal on a conductive line. It can be effective for metallic pipes, power or communications cables, and non-metallic pipes fitted with an accessible, continuous tracer wire.

Results can be weakened by a broken tracer wire, poor connection, parallel conductors, signal coupling or electrical interference. A depth indication from the receiver is part of the field evidence; it should not be treated as a physical measurement.

See EM locating services for conductive, inductive and passive method selection.

Ground-penetrating radar

GPR records changes in subsurface response. It can support investigation of non-conductive pipes and other features, but detection depends on soil, moisture, target size and depth, surface access, reinforcement and site noise. It does not identify every target or automatically tell the operator what material caused a response.

Correlating GPR evidence with records, visible features and another method generally gives a stronger interpretation than treating a single radar response as a confirmed service.

Sonde, traceable insertion and CCTV

Where a pipe is accessible, a sonde or traceable rod may help establish its route. CCTV serves a different purpose: it shows internal pipe condition and features when access and visibility allow. A camera does not by itself produce a surveyed surface alignment; a sonde or other position-tracking method may be used with it.

WorkSafe Victoria’s alert on gas pipes intruding into stormwater drains and sewers explains why condition investigation and position investigation sometimes need to be combined before cutting equipment enters a drain.

Physical exposure

Non-destructive digging or another approved exposure method answers a narrower question: what is physically present at this selected point? It may be appropriate at a crossing, design clash or location where a clearance must be checked.

Exposure does not map an entire route by itself. The asset-owner conditions, safe work documents, surface reinstatement, spoil handling and survey needs should be agreed before work starts.

Marks are a handover, not the end of the process

Field marks should be explained to the person controlling the next activity. The handover should cover:

• what was detected and what was inferred
• which records and methods informed each alignment
• the limits of the surveyed or marked area
• any depth indicators and how they were obtained
• services expected from plans but not found in the field
• unknown responses or areas that could not be scanned
• marks that may fade, move or become obscured
• locations recommended for further investigation or exposure

WorkSafe Victoria says signage and markings are warnings and should not be the only control. If the work scope, surface, marks or site conditions change, stop and reassess the information rather than extending a line beyond the investigated area.

Choose the deliverable that matches the decision

For a short-duration field activity, paint or peg marks plus a site briefing may be useful. A design team may need survey pickup and CAD/GIS output. A high-consequence crossing may need a photographed and surveyed physical exposure.

Ask the quote to state:

1. the investigation boundary
2. the plan and site inputs required
3. the field methods included
4. whether survey pickup is included
5. the file formats and coordinate system, if applicable
6. how quality, confidence and limitations will be recorded
7. who owns any recommended follow-up work

Our utility data deliverables page explains common output formats. File type alone does not establish how confidently a service was identified.

Planning the next step

The Safe Work Australia excavation document is a model Code of Practice and tells readers to check whether it has legal effect in their jurisdiction. For Victorian work, use current Victorian regulator guidance, the asset owner’s instructions, the project safe system of work and any required permits.

To scope a Melbourne locate, send HR Utilities the marked work area, current plan set, planned activity, target date and required deliverable. Request a utility locating quote or review our Melbourne underground utility locator service.

Sources

• Before You Dig Australia: Duty of Care
• WorkSafe Victoria: Guide to undertaking work near underground services
• WorkSafe Victoria: Gas pipes in stormwater drains and sewers
• Safe Work Australia: Model Code of Practice—Excavation work

Frequently Asked Questions

Is a BYDA plan the same as a field locate? +

No. BYDA sends available information from affected asset owners. BYDA says those plans indicate the presence of infrastructure rather than its exact location. A field locate investigates the work area using site evidence and suitable locating methods.

Can one locator find every underground service? +

No. Electromagnetic locating needs a conductive signal path, while GPR response depends on the target and ground conditions. A competent scope may combine methods and recommend physical exposure where the evidence is not strong enough for the intended work.

What should a utility locating report include? +

The report should identify the work area, records reviewed, methods used, field findings, marks or survey output, assumptions, limitations and recommended next steps. Confirm the exact deliverable before work begins.

When is potholing used? +

Potholing or another approved exposure method may be used where a project needs physical evidence of a service at a crossing, clash point or excavation location. The asset owner's instructions and the site's safe system of work govern the method.