Underground Services Related Hazards Pt.3
post-template-default,single,single-post,postid-3963,single-format-standard,bridge-core-3.0.6,qode-page-transition-enabled,ajax_fade,page_not_loaded,,qode-title-hidden,qode_grid_1300,qode-theme-ver-29.3,qode-theme-bridge,disabled_footer_bottom,wpb-js-composer js-comp-ver-6.10.0,vc_responsive,elementor-default,elementor-kit-3218

Underground Services Related Hazards Pt.3

No Time to Read? 

Let’s Explore the Blog Together to Know What’s Inside in 5 min summary video

Previously, we identified types and indications of underground services such as lamp posts, illuminated traffic signs, gas service pipes entering buildings, pit covers, pipeline marker posts, evidence of reinstated trenches, and how you should keep in mind that if there are no such indications, it does not mean there are no underground services.

Detecting, identifying and marking underground services

 There are several levels of surveys:

1. Desktop research include requesting and considering service drawings from the owners of underground services. This should be done for any project that involves digging or piercing ground.

2. Desktop study and site investigation: This includes using the information from the desktop study to assist with a physical inspection of the site, looking for tangible signs like inspection hatches, reinstated excavations, street lights, and telecom boxes, as well as conducting a survey using detection instruments.

3. Physical identification of services entails taking steps to locate and identify subsurface services using trial holes to confirm their position, depth, and identification. It may also require passing a tracing device through a pipe or tunnel.


The nature of the work site will determine the amount of survey required, and the decision should be made based on the information acquired for the work site. This decision should be made by the designer at the planning stage, after consulting with the contractor and surveyor.


To avoid inaccurate information and a false sense of security, decision makers who select detection tools and survey methods have to understand the range of methods and tools available, as well as their limitations, and be aware of the possibility of misleading readings or signals in certain techniques.

Operators of locators should have received sufficient training on their use and limitations. the impact of different ground conditions on survey findings, how to survey a specific region successfully, and how to recognize the limitations of plans and drawings provided by service owners. Always follow the manufacturer’s instructions when using detecting equipment, and check and calibrate them on a regular basis to ensure they are in good working order

Competent Worker

Types of detecting devices or locators

  • Hum detectors
  • Radio frequency detectors
  • Transmitter/receiver instruments
  • Metal detectors
  • Ground probing radar
  • Radio frequency identification


The degree of accuracy of detection depends on:

  • The training, skill, hearing and experience of the operator;
  • The characteristics of the device being used;
  • The calibration and reliability of the detecting device;
  • The type, length and depth of the service;
  • For cables, the magnitude of the current being carried;
  • The effects of other nearby services;
  • The nature of surface conditions, eg reinforced concrete;
  • The nature of the ground conditions;
  • Whether or not a signal generator is being used.




The results of the survey should be shared with the designer and recorded in a clear, usable format on working drawings to be shared with those working on the site and, where possible, marked out on site.

Safe excavation

a) Exposing services


In most circumstances, there will be no permanent surface marker posts or other obvious signs of an underground service. Even if they are not shown on plans or detected by a locator, there may be services present that are operational, and you should keep an eye out for any evidence of their presence.


For example


Valve boxes, pits, and housings can all be used to represent a gas plant. However, covers for valve boxes and pits will sometimes not clearly show whether gas is the service present; also, many communications and railway signalling cables cannot be located by detecting devices.

Underground Installation

Better a thousand times careful than once dead.

– Safety Advisor

Control Measures

  • Start with Using trial holes to accurately identify a service’s depth.
  • By safely exposing a service, status is checked and traced signal more easily.
  • Excavation work should follow safe digging practices.
      1. Once a detecting device has been, excavation may proceed,
      2. Trial holes dug to confirm the position of any detected service


  • Take special care when digging above or close to the assumed service.
  • Carefully plan and manage mechanical excavation,
  • Another person should assist the excavator driver:
      1. From a position where they can safely see into the excavation
      2. Warn the driver of any services or other obstacles.
      3. This person should remain outside the operating radius of the excavator arm and bucket.
  • Everyone involved in exposing services, as well as those supervising them, must be competent.
      1. Had enough information, education, and training
      2. Use detecting equipment, and use safe excavation procedures.
      3. Learn the benefits of hand digging
      4. The risks of utilizing power equipment or mechanical excavators.
  • Use insulated tools when hand digging near electric cables
  • Make frequent and repeated use of service locators while working.
  • Once exposed, services may require support and should never be utilized as handholds or footholds to climb out of excavations.
  • Assume all services are live until disconnected and proven safe at the point of work.
  • Obtain written confirmation of disconnection from the owner/ operator before removing a redundant service

Remember that:

  • The risk of destroying a gas pipe with an excavator is substantially higher than if the harm is done with a hand-held power tool; the opposite is true for work near electricity cables.
  • Harm to a service connection can cause hidden harm to the connection inside the structure.
  • Hand-held power tools can cause damage to services, so use them with caution until the exact position of the service is identified.
  • Make every attempt to excavate beside the service rather than straight over it.
  • Hand-held power tools should not be used over a service unless it has been exposed through excavating at a safe depth and physical precautions have been taken to prevent the instrument from striking it.
  • Excavators and power tools can be utilized if the survey indicates no services or if the services are deep enough to avoid harm.
  • Safe methods of excavating may include vacuum excavation
  • Excavating across or alongside gas pipes requires specific consideration; disruption of back-fill may raise stress and affect support for a gas pipe; thus, always check with the owner before starting work.
To Be Continued
Read more