Non-invasive Service Location Safe Work Method Statement

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Non-invasive service location identifies underground utilities including electrical cables, gas pipes, water mains, telecommunications conduits, and sewer pipes without excavation using electromagnetic detection equipment, ground penetrating radar, and acoustic methods. This Safe Work Method Statement addresses hazards associated with service location activities including electromagnetic field exposure, false service detection, equipment operation on live traffic routes, and physical demands of sustained field work across Australian construction sites.

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Overview

What this SWMS covers

Non-invasive service location is a specialized activity using electromagnetic detection equipment, ground penetrating radar, and acoustic methods to identify underground utilities before excavation commences. The process prevents costly and dangerous strikes to buried services including electrocution from energized electrical cables, gas explosion from ruptured gas mains, water service damage causing flooding, telecommunications damage affecting critical communications, and sewer damage creating health hazards and environmental contamination. Service location specialists deploy electromagnetic (EM) locators comprising a transmitter applying electrical signal to conductive services and a receiver detecting electromagnetic fields generated by signal current flowing through services. Ground penetrating radar (GPR) systems use radio wave pulses reflecting from underground objects providing depth and position information for both conductive and non-conductive services. Acoustic methods detect water leak sounds from pressurized water pipes. GPS systems integrate with location equipment creating georeferenced utility maps with high positional accuracy. Typical projects requiring service location include all excavation activities near existing infrastructure, new development sites where service plans are unavailable or unreliable, infrastructure maintenance and upgrade projects requiring accurate service positioning, demolition projects requiring service isolation planning, and utility conflict identification for design coordination. Service location occurs at project planning stage informing design development and immediately before excavation commencement verifying current service positions. The complexity of service location varies with site conditions. Urban areas contain dense service congestion with multiple services in close proximity requiring careful discrimination between individual services. Shallow services above 600mm depth are relatively simple to locate while deep services below 1500mm challenge detection range. Conductive services including metallic water pipes, electrical cables, and telecommunications copper pairs are readily detected electromagnetically while non-conductive services including plastic water pipes, PVC conduits, and concrete stormwater pipes require GPR or other detection methods. Site conditions including reinforced concrete surfaces, high soil conductivity, and electromagnetic interference from overhead powerlines affect detection reliability. This SWMS applies to all non-invasive service location activities on Australian construction sites. It covers work by qualified service location technicians, utility locating contractors, and surveyors conducting utility mapping. The document addresses requirements under the WHS Act 2011, AS 5488 Classification of Subsurface Utility Information, and Dial Before You Dig code of practice requirements.

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Why this SWMS matters

Underground utility strikes cause significant injuries, fatalities, property damage, and service disruption across Australia annually. Safe Work Australia reports show electrical contact injuries including those from underground cable strikes cause approximately 5 fatalities annually in construction industry. Beyond immediate injury risk, utility strikes cause extensive indirect consequences including service interruption affecting hospitals, emergency services, and essential infrastructure; environmental contamination from sewer or fuel pipeline rupture; project delays from utility repairs and investigation; financial losses from repair costs, claims, and penalties; and regulatory enforcement including improvement notices and prosecution under WHS legislation. The WHS Act 2011 requires PCBUs to manage risks associated with excavation near underground services. Work Health and Safety Regulations classify excavation within 300mm of pressurized gas pipelines or 500mm of electrical cables as high-risk construction work requiring specific risk controls. Service location is a critical control measure enabling excavators to maintain safe clearances or implement additional protections where clearances cannot be maintained. Failure to locate services before excavation represents a breach of duty of care exposing responsible parties to prosecution, fines, and civil liability. Dial Before You Dig is a free national referral service providing utility service plans from participating asset owners. Legislation in several Australian jurisdictions makes Dial Before You Dig enquiries mandatory before excavation commencement with penalties for non-compliance. However, Dial Before You Dig plans show approximate service locations only typically accurate within 2-5 meters horizontally and may not show all services particularly private services not owned by utility authorities. Service plans are often decades old with service positions changed by subsequent works. Non-invasive location verifies actual service positions before excavation begins. Accuracy of service location determines whether excavation can proceed safely using mechanical equipment or requires hand excavation near services. AS 5488 defines quality levels for subsurface utility information ranging from QL-D (existence and type of utility known from plans) to QL-A (utility precisely located through exposure). Non-invasive location provides QL-B information where services are located using appropriate detection methods with horizontal accuracy typically ±300mm and depth accuracy ±15%. This accuracy allows mechanical excavation maintaining minimum clearances or hand excavation where mechanical methods are too hazardous. Electromagnetic field exposure affects technicians operating high-power transmitters during service location. While non-ionizing electromagnetic fields from location equipment are generally regarded as safe, technicians conducting sustained location work may accumulate significant cumulative exposure. Electromagnetic hypersensitivity affects some individuals causing symptoms including headaches, fatigue, and concentration difficulties when exposed to electromagnetic fields. Monitoring exposure and implementing work practices minimizing unnecessary transmitter power reduce electromagnetic exposure while maintaining location effectiveness.

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Hazard identification

Surface the critical risks tied to this work scope and communicate them to every worker.

Risk register

Low

Service location transmitters generate electromagnetic fields up to 10 watts power inducing currents in conductive services for detection by receivers. Technicians carry transmitters while surveying exposing them to electromagnetic fields throughout work shifts potentially multiple hours daily. High-power transmitter modes used for deep service detection or high-interference environments increase field strength. Transmitter antennas held close to body during transport and positioning create localized high-field exposure. Some individuals report electromagnetic hypersensitivity experiencing symptoms including headaches, nausea, fatigue, and concentration difficulty when exposed to electromagnetic fields. Cumulative exposure over career spanning thousands of hours creates long-term exposure exceeding general public limits. Combination of multiple transmitters operating simultaneously on large sites compounds exposure levels.

High

Service location equipment may fail to detect services due to equipment limitations, operator error, or site conditions. Non-conductive services including plastic water pipes, PVC electrical conduits, and concrete stormwater pipes produce no electromagnetic signal detectable by EM locators requiring GPR or other methods that may not be deployed. Deep services below equipment detection range remain undetected particularly in high-conductivity soils attenuating signals. Services running perpendicular to survey sweeps may be missed if survey line spacing too wide. Multiple services bundled together may appear as single service with additional services undetected. High soil conductivity in clay or moisture-saturated ground attenuates signals reducing detection range. Reinforced concrete surfaces prevent signal penetration making services beneath concrete undetectable. Electromagnetic interference from overhead powerlines, adjacent operating equipment, or radio transmissions masks weak service signals. Operator inexperience or inadequate survey methodology misses subtle signals indicating service presence.

High

Even with thorough service location, excavation may still strike services due to location inaccuracies, service movement, or excavation technique errors. Horizontal location accuracy of ±300mm means services may be offset from marked positions within tolerance but still struck by excavator bucket. Depth readings show measurement error ±15% meaning service marked at 1000mm depth could actually be at 850mm. Services shift position during ground movement from previous excavation, soil settlement, or tree root growth moving services from original detected position. Temporary construction services including electrical cables and water pipes may not appear on plans and are difficult to detect. Private services on private property may not be registered with utility authorities and not shown on Dial Before You Dig plans. Excavator operators may not recognize or respect service markings allowing machine to excavate directly on marked service position. Multiple services in congested areas create confusion about which service is which among multiple marked services.

High

Striking underground electrical cables with excavation equipment or hand tools causes electrocution to personnel contacting damaged cables or equipment. Underground electrical cables range from low-voltage 240V service connections to high-voltage 11kV or 66kV transmission cables. Voltage cannot be determined from external appearance. Cable damage exposes live conductors that remain energized until utility authority disconnects supply. Current flows through excavator body to ground potentially electrifying machine and surrounding area. Personnel touching machine or standing on wet ground within step potential zone receive electric shock. High-voltage cables arc over considerable distances electrocuting personnel without direct contact. Damaged cable sheath may appear minor externally but conductive moisture ingress creates electrocution hazard days after initial damage. Emergency services responding to incidents face electrocution risk from energized equipment and ground.

High

Service location on operational roads requires technicians to work in proximity to moving traffic while conducting surveys. Technicians walk survey patterns requiring attention on detection equipment preventing constant traffic awareness. Sudden direction changes while following service alignments may place technicians in traffic path. Equipment including transmitter cases, receivers, and survey wheels creates trip hazards causing falls into traffic lanes. High-visibility clothing provides visibility but does not prevent inattentive driver strikes. Location work on high-speed roads exposes technicians to vehicles traveling 80-100 km/h with little reaction time. Road curves and crest create low visibility areas where drivers cannot see technicians until close proximity. Night work requires additional lighting and reflective marking but visibility remains reduced. Technicians working alone without traffic controllers face elevated risk particularly on high-traffic roads.

Control measures

Deploy layered controls aligned to the hierarchy of hazard management.

Implementation guide

Combining electromagnetic location, ground penetrating radar, and acoustic methods provides comprehensive service detection minimizing false negative risks from single-method limitations.

Implementation

1. Deploy electromagnetic locators as primary detection method for conductive services including metallic water pipes, electrical cables, and telecommunications copper cables 2. Use ground penetrating radar to confirm electromagnetically-detected services and identify non-conductive services including plastic water pipes, PVC conduits, and concrete stormwater pipes 3. Apply acoustic detection methods for pressurized water services using leak detection equipment identifying pipe resonance 4. Implement GPS-based survey methods creating georeferenced utility maps with high positional accuracy for future reference 5. Conduct location using multiple transmitter frequencies including high frequencies for shallow service detection and low frequencies for deep service penetration 6. Apply multiple coupling methods including direct connection to service access points, induction for inaccessible services, and signal injection through hydrants or meter boxes 7. Verify detected services against Dial Before You Dig plans cross-checking detected services match planned service types and approximate locations 8. Mark detected services using color-coded paint per AS 5488 with confidence level annotations indicating quality of location data 9. Photograph marked services documenting service marking in relation to site features for future verification

Hand excavation exposing services at key locations verifies service positions, depths, and types before mechanical excavation commences eliminating reliance on location accuracy alone.

Implementation

1. Require potholing at minimum 10-meter intervals along service alignments providing physical verification of service position and depth 2. Conduct pothole excavation using hand tools or vacuum excavation eliminating mechanical excavation risks during verification 3. Expose services sufficiently to identify service type, size, depth, and condition enabling informed excavation planning 4. Measure actual service depth at pothole locations comparing to location equipment readings verifying depth accuracy 5. Mark exposed services with temporary markers maintaining surface indication throughout excavation work 6. Photograph exposed services documenting service characteristics and relationship to surface features 7. Update service location plans with pothole verification data adjusting marked positions if significant variance identified 8. Suspend mechanical excavation within 500mm of verified service locations requiring hand excavation within close proximity zone 9. Brief excavator operators on pothole findings including service types, depths, and exact positions before excavation commences

Regular calibration and verification of location equipment accuracy ensures reliable detection and measurement of underground services.

Implementation

1. Calibrate electromagnetic locators daily against services of known position and depth before commencing location work 2. Verify ground penetrating radar signal response using test targets confirming proper system operation and signal interpretation 3. Conduct blind testing where technician locates services without reference to plans then compares detected services to plan information assessing detection accuracy 4. Maintain equipment per manufacturer specifications including battery charging, firmware updates, and periodic factory servicing 5. Replace consumable components including worn cable connectors, damaged receiver antennae, and degraded signal clamps per maintenance schedule 6. Document equipment calibration and maintenance in equipment logbooks creating service history and compliance records 7. Withdraw defective equipment from service immediately preventing use of unreliable equipment compromising detection quality 8. Conduct inter-technician comparison exercises where multiple technicians locate same services independently comparing results identifying training needs 9. Participate in industry quality assurance programs including third-party audits verifying consistent detection quality

Comprehensive training ensures technicians understand service location principles, equipment operation, detection limitations, and quality requirements before conducting independent location work.

Implementation

1. Provide formal training covering electromagnetic theory, ground penetrating radar principles, equipment operation, survey methodology, and result interpretation 2. Include manufacturer-specific training for equipment models used ensuring understanding of unique features and operating procedures 3. Teach service types and characteristics including typical depths, construction methods, and detection signatures for various utility services 4. Train on site condition factors affecting detection including soil types, interference sources, and service configurations impacting detection reliability 5. Cover quality assurance requirements including calibration procedures, documentation standards, and marking conventions per AS 5488 6. Provide supervised field training progressing from simple sites with known services to complex sites requiring advanced detection techniques 7. Conduct formal competency assessment including written examination and practical field assessment observing complete location project 8. Require minimum experience threshold typically 40 hours supervised field work before authorizing independent location operations 9. Maintain training records documenting competency assessments, equipment authorized, and periodic refresher training

Traffic control measures protect service location technicians working on operational roads through speed reduction, lane closures, and physical barriers between workers and traffic.

Implementation

1. Implement traffic management per Traffic Management for Works on Roads establishing appropriate advance warning and speed reductions for road speed and classification 2. Use shadow vehicle with attenuator on high-speed roads providing physical barrier between technicians and approaching traffic 3. Deploy traffic controllers managing traffic flow at work zone extremities on roads requiring lane closures or single-lane operation 4. Install variable message signs providing advance warning and speed reduction messages to approaching traffic 5. Position safety barriers or water-filled barriers creating physical separation between work zone and live traffic where space permits 6. Schedule location work during low-traffic periods where feasible reducing traffic exposure and improving safety margins 7. Require technicians work in pairs on high-traffic roads enabling one person to maintain traffic watch while other conducts location work 8. Provide two-way radio communication between technicians, traffic controllers, and shadow vehicle operators maintaining coordination 9. Ensure all personnel wear high-visibility Class N clothing providing enhanced reflectivity for night work conditions

Work practices and equipment settings minimize electromagnetic field exposure while maintaining effective service detection capability.

Implementation

1. Use minimum transmitter power adequate for detection requirements avoiding unnecessarily high power settings 2. Position transmitters away from body during operation using remote positioning or extended connections maintaining distance 3. Limit continuous transmitter operation time implementing work-rest cycles allowing electromagnetic field recovery periods 4. Rotate tasks among crew members reducing individual cumulative exposure through shared exposure distribution 5. Monitor individual exposure time documenting daily transmitter operation hours for cumulative exposure assessment 6. Provide electromagnetic field meters enabling measurement of field strength during operation verifying compliance with exposure guidelines 7. Implement distance requirements maintaining minimum separation between transmitter and technician body typically 1 meter where practical 8. Use directional transmitter couplings focusing signal toward target services rather than omnidirectional radiation reducing overall field strength 9. Educate technicians on electromagnetic exposure health considerations enabling informed decisions about exposure management

Appropriate PPE protects service location technicians from traffic visibility hazards, physical demands, and environmental exposure during field operations.

Implementation

1. Require Class D day/night or Class N high-visibility clothing ensuring 360-degree visibility to traffic for road-based work 2. Provide safety footwear to AS/NZS 2210.3:2009 protecting feet during walking on varied terrain and potential service strike exposure 3. Supply sun protection including wide-brimmed hats, UV-protective sunglasses, and SPF 50+ sunscreen for outdoor work 4. Provide gloves protecting hands during equipment handling and potential contact with contaminated surfaces 5. Supply hearing protection when working adjacent to high-traffic roads where noise levels exceed 85 dB(A) 6. Provide knee pads for technicians conducting ground-level survey work and pothole inspections reducing knee strain 7. Ensure hard hats worn on construction sites where overhead hazards present from operating equipment or materials handling 8. Maintain adequate PPE stock in various sizes ensuring proper fit for all personnel 9. Replace damaged or worn PPE immediately maintaining protective effectiveness throughout service life

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Inspections & checks

Before work starts

✓Submit Dial Before You Dig enquiry minimum 2 working days before commencing location work obtaining current service plans from participating utilities
✓Review service plans identifying expected services including types, approximate depths, and service owner contact details
✓Assess site conditions including traffic volumes, road speeds, terrain characteristics, and environmental hazards affecting location work
✓Inspect service location equipment including electromagnetic locator, GPR system, and GPS receiver verifying proper operation
✓Calibrate electromagnetic locator against service of known position and depth confirming accurate detection and depth measurement
✓Charge all equipment batteries ensuring adequate capacity for planned survey duration typically 6-8 hours operation
✓Review traffic management plan for road-based work confirming appropriate controls for road classification and traffic conditions
✓Prepare survey equipment including marking paint, survey flags, measuring wheels, and documentation materials

During work

✓Verify electromagnetic locator detection signals match expected service types from Dial Before You Dig plans identifying discrepancies requiring investigation
✓Monitor signal strength and quality during surveys adjusting transmitter power or frequency as needed for optimal detection
✓Cross-check detected services using multiple detection methods confirming consistent results between electromagnetic and GPR surveys
✓Observe traffic management effectiveness ensuring traffic complies with speed reductions and maintains safe clearance from work zone
✓Check marked service positions maintaining consistent marking conventions including color coding and confidence level annotations
✓Monitor technician fatigue during sustained survey work implementing rest breaks and task rotation preventing attention lapses
✓Verify GPS position data quality ensuring adequate satellite reception for accurate georeferencing of detected services
✓Document site conditions affecting detection quality including electromagnetic interference, high-conductivity soils, or reinforced concrete surfaces

After work

✓Verify all detected services marked clearly using appropriate color-coded paint per AS 5488 requirements
✓Photograph marked services documenting service positions in relation to site features and structures
✓Create site plan showing detected service alignments, depths at key locations, service types, and confidence levels per AS 5488 quality classifications
✓Compare detected services to Dial Before You Dig plans documenting services found, services expected but not found, and unexpected services detected
✓Prepare location report including detection methods used, equipment settings, site conditions, service locations, and recommended excavation precautions
✓Identify services requiring pothole verification before mechanical excavation including deep services, congested service areas, or low-confidence detections
✓Provide service owner notifications if service damage suspected from previous works or concerning service conditions observed
✓Document equipment performance issues, calibration variations, or maintenance requirements in equipment logbook

Step-by-step work procedure

Give supervisors and crews a clear, auditable sequence for the task.

Field ready

Pre-Location Planning and Dial Before You Dig Enquiry

Submit Dial Before You Dig enquiry through online portal, phone service, or mobile app providing detailed work location information. Include site address, property identification, GPS coordinates if available, and detailed description of proposed works including excavation extent and depth. Specify required response time either standard (2 business days) or urgent (3 hours) depending on work urgency. Dial Before You Dig distributes enquiry to participating utility asset owners who respond with service plans showing approximate service locations. Review received plans identifying all services reported in work area including electrical cables, gas pipes, water mains, telecommunications cables, and sewer pipes. Check service information including typical depths, service owners, and any special cautions or restrictions. Contact service owners directly for additional information if plans unclear or services classified as high-risk. Identify services requiring direct connection access including electrical cables accessed through pits, water services accessed through meter boxes, or telecommunications cables accessed through inspection pits. Assess site hazards including traffic management requirements, terrain characteristics affecting accessibility, environmental conditions, and site access restrictions. Obtain necessary permits and approvals for road work including road occupancy permits from road authorities. Coordinate with project stakeholders including excavation contractors, designers, and project managers regarding location scope and reporting requirements.

Safety considerations

Dial Before You Dig provides approximate service locations only with typical horizontal accuracy within 2-5 meters. Plans may be decades old with service positions changed by subsequent work. Some services may not appear on plans including private services, temporary construction services, or unlicensed installations. Never rely solely on Dial Before You Dig plans without field verification through non-invasive location. Consider liability implications if excavation proceeds based solely on plans without location verification.

Equipment Calibration and Testing

Inspect electromagnetic locator transmitter checking battery charge, antenna condition, cable connections, and signal clamp operation. Test transmitter operation by applying signal to known conductive object verifying signal generation. Inspect receiver unit checking battery charge, display function, antenna integrity, and audio output. Calibrate receiver against service of known position and depth typically accessible electrical cable or water service with known burial depth. Place transmitter signal on calibration service using direct connection method. Walk receiver along service alignment verifying strong consistent signal detection along service route. Use depth measurement mode measuring service depth comparing receiver reading to actual known depth verifying accuracy within ±15%. Inspect ground penetrating radar system checking battery charge, antenna condition, and display clarity. Test GPR operation over known target verifying proper signal response and hyperbola formation in data display. Verify GPS receiver operation checking satellite reception quality and position accuracy in open area. Check auxiliary equipment including measuring wheels, survey flags, marking paint, and documentation materials. Load relevant site plans and Dial Before You Dig responses onto survey devices if using electronic data management. Brief survey team on planned survey approach, expected services, and safety requirements for day's work. Conduct pre-start safety meeting reviewing site hazards, traffic management, and emergency procedures.

Safety considerations

Equipment malfunction during surveys creates false confidence that thorough location occurred when unreliable equipment may have missed services. Never proceed with defective equipment. Maintain spare equipment for critical components enabling continuity if primary equipment fails. Document all calibration activities creating audit trail of equipment reliability. Replace consumable components proactively preventing field failures.

Electromagnetic Service Location

Establish site traffic management per approved plan before commencing road-based work. Position transmitter for optimal signal application using direct connection where accessible service points available. For electrical cables, access underground cable pits connecting transmitter directly to cable sheath or conductor. For water services, connect transmitter to exposed metallic components at meter boxes, valve boxes, or hydrants. For telecommunications, access inspection pits connecting to cable sheath or tracer wires. If direct connection not feasible, use induction method positioning transmitter above suspected service location inducing signal electromagnetically. Select appropriate transmitter frequency based on site conditions using high frequency 8-33 kHz for shallow service detection with good localization or low frequency 512-1024 Hz for deep service detection with better ground penetration. Apply transmitter signal monitoring signal strength indication ensuring adequate signal generation. Walk receiver along survey area holding antenna at consistent height typically 100-300mm above ground surface. Sweep receiver perpendicular to expected service alignment listening for audio signal peaks and observing signal strength display. When signal detected, follow service alignment marking ground at regular intervals typically 1-2 meters. Use peak positioning technique where receiver signal strength maximizes when directly above service. Engage depth measurement mode determining service depth at key locations typically every 10 meters along service route and at significant features including property boundaries, road crossings, and service branches. Mark services using color-coded paint per AS 5488 conventions: red for electrical, yellow for gas, blue for water, orange for telecommunications, green for sewer, white for proposed excavation, and pink for survey marks.

Safety considerations

Traffic exposure during road-based work creates significant strike hazards. Maintain constant awareness of traffic flow. Use traffic controllers managing traffic on high-speed roads. Focus on survey equipment can cause inattention to traffic requiring buddy system or traffic watch personnel. Transmitter signal application to services requires care as electrical cables may be energized creating electrocution risk. Never connect transmitter to live electrical conductors. Connection to cable sheaths is safe but verify connection to earth side not phase conductor.

Ground Penetrating Radar Confirmation

Survey electromagnetically-detected service locations using ground penetrating radar confirming service presence and measuring burial depth. Position GPR antenna at right angles to service alignment ensuring radar pulses cross service perpendicularly providing optimal reflection. Move antenna steadily along survey line maintaining consistent speed and surface contact. Observe GPR display identifying characteristic hyperbola patterns indicating subsurface objects. Service reflections appear as hyperbolic curves with apex directly above service position. Mark service positions where hyperbola apexes identified confirming electromagnetic detection results. Measure service depth from GPR data using time-of-arrival calculations. System displays depth estimates based on signal velocity through soil. Typical soil velocity is 100mm/ns but varies with moisture content and soil type affecting depth accuracy. Conduct GPR surveys perpendicular to electromagnetic surveys detecting non-conductive services including plastic water pipes, PVC conduits, concrete pipes, and other non-metallic utilities invisible to electromagnetic detection. Survey entire site systematically using parallel survey lines spaced typically 1-2 meters apart depending on required detection resolution. Mark non-conductive services detected by GPR using appropriate color codes based on suspected service type determined from Dial Before You Dig plans, depth, size, and site context. Document areas where GPR detection limited by site conditions including reinforced concrete surfaces preventing signal penetration, high-conductivity soils attenuating signals, or excessive surface roughness preventing antenna contact.

Safety considerations

GPR interpretation requires experience distinguishing service reflections from other subsurface objects including rocks, tree roots, previous excavation backfill, and soil changes. Ambiguous reflections should be investigated through potholing rather than assumed to be services or dismissed as irrelevant. Conservative approach marks all significant reflections for investigation. GPR provides depth information but service type identification is interpretive requiring correlation with Dial Before You Dig plans and local knowledge.

Service Depth Measurement and Mapping

Systematically measure service depths at key locations along all detected services. Position electromagnetic receiver or GPR system directly above marked service centerline. Activate depth measurement mode following manufacturer procedures typically requiring perpendicular receiver orientation to service alignment. Record depth measurement comparing to expected depths from Dial Before You Dig plans identifying significant variances requiring investigation. Measure depths at property boundaries, road edges, service branches, and changes in alignment documenting depths where excavation likely to occur. Use multiple measurement positions averaging results to improve accuracy accounting for measurement uncertainty. Create detailed site plan showing service alignments accurately positioned relative to site features including fences, buildings, road edges, kerbs, and other permanent references. Plot services using CAD software or hand-drawn plans with appropriate scale typically 1:100 or 1:200. Annotate plans with service types, depths at key locations, confidence levels per AS 5488 classifications, detection methods used, and date of survey. Photograph site conditions documenting service marking in relation to physical features enabling future re-identification if ground marking becomes unclear. Use GPS to record service positions creating georeferenced utility mapping providing high positional accuracy for future reference. Export GPS data in appropriate formats for integration with project CAD drawings or utility mapping databases. Identify service crossings where multiple services occupy same alignment noting vertical separation between services and potential for excavation to contact multiple services.

Safety considerations

Location accuracy determines safe excavation approach. Mark location uncertainty on plans using confidence level classifications. High confidence QL-B locations (horizontal ±300mm, depth ±15%) allow mechanical excavation with appropriate clearances. Lower confidence locations require more conservative approach including potholing verification or hand excavation. Document measurement uncertainties protecting against liability claims if subsequent service strikes occur despite location work.

Reporting and Excavation Cautions

Prepare comprehensive location report documenting complete service location findings. Include executive summary describing services detected, location methods used, site conditions, and key findings requiring attention. Provide detailed service descriptions for each detected service including service type, approximate route description, typical depth range, depth measurements at key locations, and confidence level rating per AS 5488. Include site plan showing all detected services with appropriate symbology and annotations. Document detection methods including electromagnetic frequency and coupling method, GPR system and antenna used, and GPS positioning method. Record site conditions affecting detection including soil types, electromagnetic interference sources, reinforced concrete areas, and other factors impacting detection reliability. Identify services requiring special attention including high-risk services like high-voltage electrical or high-pressure gas, services with unexpected positions compared to Dial Before You Dig plans, deep services approaching equipment detection limits, and congested areas with multiple services in close proximity. Specify recommended excavation precautions including pothole verification locations, hand excavation zones, service owner notification requirements, and standby requirements for live services. Provide maps showing pothole locations recommended before mechanical excavation typically at 10-meter intervals and service crossing points. Include contact details for service owners requiring notification before excavation near critical services. Attach all supporting documentation including Dial Before You Dig responses, service owner correspondence, calibration records, and photographic documentation. Distribute report to all stakeholders including excavation contractors, project managers, designers, and service owners as appropriate. Conduct toolbox meeting with excavation crews reviewing location findings and excavation precautions before work commences.

Safety considerations

Location report creates legal documentation of due diligence undertaken before excavation. Accurate comprehensive reporting protects all parties by documenting what was detected, what was expected but not detected, and what limitations affected detection process. If service strikes occur despite location work, report demonstrates reasonable precautions taken shifting liability analysis toward excavation technique and compliance with location recommendations rather than adequacy of location effort.

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Frequently asked questions

Is Dial Before You Dig mandatory in Australia before excavation?

Dial Before You Dig is mandatory in several Australian jurisdictions including New South Wales under WHS Regulation 2017 Part 4.5, Victoria under OH&S Regulations 2017, and Queensland under WHS Regulation 2011. Other jurisdictions strongly recommend Dial Before You Dig as industry best practice with WHS legislation requiring identification of underground services before excavation regardless of specific Dial Before You Dig mandate. Penalties for non-compliance where mandatory include fines up to $6,000 for individuals and $30,000 for companies. Beyond legal requirements, Dial Before You Dig provides critical safety information and liability protection. Service owners may refuse damage claims if Dial Before You Dig enquiry not conducted. Excavators conducting work without Dial Before You Dig reference face significant liability exposure if service strikes occur. Enquiries must be submitted minimum 2 business days before excavation or 3 hours for urgent works where available. Response includes service plans from participating utilities showing approximate service locations, service owner contact details for notifications, and special cautions for high-risk services.

What is the accuracy of non-invasive service location and when is potholing required?

Non-invasive service location provides QL-B quality level per AS 5488 with horizontal accuracy typically ±300mm and depth accuracy ±15% of measured depth. For example, service detected at 1000mm depth has actual depth range of 850-1150mm. This accuracy allows mechanical excavation maintaining minimum clearances of 300mm horizontal and 500mm vertical from detected service positions. However, accuracy varies with site conditions including soil type affecting signal strength, service depth with accuracy decreasing for deep services, service congestion where multiple services complicate detection, and electromagnetic interference masking signals. Potholing (hand excavation verification) is required when services are within mechanical excavation zone typically within 500mm of planned excavation, service depth or position uncertain due to site conditions, multiple services present in excavation area creating congestion, critical services including high-voltage electrical or high-pressure gas require physical confirmation, or detection confidence is low due to difficult site conditions. AS 5488 recommends potholing at 10-meter intervals along service alignments verifying location accuracy before mechanical excavation proceeds. Cost of potholing is minimal compared to service strike repair costs, service interruption impacts, and injury risks from unexpected service contact.

Why might services not be detected during non-invasive location?

Multiple factors cause services to remain undetected during location work. Non-conductive services including plastic water pipes, PVC electrical conduits, HDPE gas pipes, and concrete stormwater pipes produce no electromagnetic signal requiring ground penetrating radar or other detection methods that may not be deployed or may be ineffective in site conditions. Deep services below equipment detection range typically beyond 3-4 meters depth may not generate sufficient signal strength for reliable detection particularly in high-conductivity soils. Services running perpendicular to survey sweeps may be missed if survey line spacing too wide. Electromagnetic interference from overhead powerlines, operating equipment, or radio transmissions can mask service signals making detection impossible despite service presence. High-conductivity soils including clay or moisture-saturated ground attenuate electromagnetic signals reducing detection range. Reinforced concrete surfaces prevent signal penetration making services beneath concrete slabs or pavements undetectable without surface breaking. Private services on private property may not appear on Dial Before You Dig plans and may not follow typical installation patterns. Temporary construction services including site power and water are not recorded on permanent plans. Abandoned services remaining in ground appear same as active services during detection but may not appear on current utility plans. These limitations make multi-method detection, conservative excavation approach, and potholing verification essential despite comprehensive location efforts.

What should excavators do if they detect a service during excavation that was not identified during service location?

Stop excavation immediately when unexpected service encountered even if service location indicated area clear. Do not assume service is abandoned or inactive as many live services remain functional despite not appearing on plans. Expose service carefully using hand tools to identify service type, size, and condition. Look for identification marking, tracer wires, or warning tape indicating service type and owner. Photograph exposed service documenting position, depth, and characteristics. Contact service locator requesting investigation of unexpected service. Service locator should return to site verifying whether missed service during original location or service installed after location conducted. Contact Dial Before You Dig asset desk requesting information about exposed service providing description and photos. Dial Before You Dig can query asset owners identifying service ownership. If service owner identified, contact owner requesting attendance to verify service status and approve excavation near service. If service cannot be identified, assume it is live critical service implementing maximum precautions. Do not damage unidentified services regardless of appearance. Treat all services as potentially dangerous until confirmed abandoned. Document unexpected service on as-built drawings updating project records. Report service location company if missed service represents detection failure requiring service location methodology review. Unexpected services are common particularly in urban areas with extensive undocumented private services and historical infrastructure not appearing on modern plans.

What are the requirements for service location personnel competency in Australia?

Australia has no mandatory licensing or certification for service location personnel unlike some international jurisdictions. However, the WHS Act 2011 requires workers be adequately trained and competent for tasks assigned. Industry best practice includes formal training covering electromagnetic theory, ground penetrating radar principles, detection equipment operation, survey methodology, result interpretation, and AS 5488 quality classification. Equipment manufacturers provide training courses covering specific equipment operation ensuring proper use and maintenance. Many employers require personnel complete construction induction (White Card) for work on construction sites. Traffic control training (Yellow or Red Card depending on jurisdiction) is required for technicians setting up traffic management for road-based work. Industry bodies including Telstra, AusNet, and other utility asset owners provide asset-specific training covering their infrastructure characteristics and location protocols. Experience requirements vary but many employers require minimum 40-80 hours supervised field work before authorizing independent location. Some clients specify competency requirements in contracts including certification from equipment manufacturers or industry training organizations. Professional associations including Institute of Public Works Engineering Australasia (IPWEA) offer subsurface utility engineering courses. Formal competency assessment should include written examination testing theoretical knowledge and practical field assessment observing complete location project. Without mandatory certification, burden falls on employers to ensure adequate training and assessment demonstrating due diligence in personnel competency verification.

How long do service location markings remain valid before excavation?

Industry standard practice considers service location markings valid for approximately 14 days after placement in stable conditions. After this period, ground marking paint may fade, weather conditions may disturb marking, ground movement may alter service positions, and site conditions may change affecting location accuracy. Extended delays between location and excavation require re-location verifying services remain at marked positions particularly in active construction sites where ongoing works may disturb ground. Some factors requiring immediate re-location regardless of time elapsed include any ground disturbance in marked area from previous excavation or equipment traffic, significant rainfall or flooding potentially moving ground and services, extreme weather conditions degrading surface markings, site grading or surface preparation removing or obscuring markings, and installation of new services in area changing subsurface conditions. In litigious situations following service strikes, age of location markings is significant factor determining excavator liability. Excavating based on markings older than 30 days may indicate inadequate precautions despite original location work. Service location reports should specify marking validity period and re-location requirements. Excavators should photograph service markings before commencing work documenting marking condition and visibility. If markings unclear or absent, request re-location before excavation regardless of original location age. Cost of re-location is minimal compared to risks from excavating based on invalid or unclear service position information. Conservative approach protects all parties ensuring excavation based on current accurate service position information.

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Risk Rating

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After ControlsLow

Key Controls

• Pre-start briefing covering hazards
• PPE: hard hats, eye protection, gloves
• Emergency plan communicated to crew

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Non-invasive Service Location Safe Work Method Statement

What this SWMS covers

Why this SWMS matters

Hazard identification

Control measures

Personal protective equipment

Inspections & checks

Before work starts

During work

After work

Step-by-step work procedure

Pre-Location Planning and Dial Before You Dig Enquiry

Equipment Calibration and Testing

Electromagnetic Service Location

Ground Penetrating Radar Confirmation

Service Depth Measurement and Mapping

Reporting and Excavation Cautions

Frequently asked questions

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