Ground Investigation Safety

Ground investigation uses boreholes, trial pits, and in-situ testing to assess soil and groundwater conditions.
The work involves drilling rigs, tracked excavators, and sampling equipment on potentially contaminated sites.
Buried services must be located before any drilling or excavation using plans, CAT, and Genny detection.
Trial pits expose operatives to excavation collapse hazards — support may be needed in unstable ground.
Ground gases including methane and carbon dioxide can be released from boreholes during drilling.
Contaminated soil, groundwater, and vapours may contain heavy metals, hydrocarbons, or asbestos fibres.
CDM 2015 and COSHH 2002 require risk assessment for all ground investigation activities.
Drilling rigs must be set up on stable, level ground with outriggers fully extended before operation.
Access roads for rigs on greenfield sites may cross soft ground, slopes, and watercourses.
Sample handling, labelling, and chain of custody procedures must prevent cross-contamination.

Service strikes	Drilling into buried cables or gas mains causes fatal electrocution and explosions.
Contamination exposure	Workers handling contaminated samples face chemical and biological health risks.
Excavation collapse	Trial pits in unstable ground collapse without warning, trapping workers.
Gas release	Boreholes can release explosive or toxic ground gases during and after drilling.

Do

Don't

Locate all buried services using plans and a CAT and Genny before drilling.
Set up drilling rigs on stable, level ground with outriggers fully deployed.
Monitor for ground gases at every borehole during and after drilling operations.
Wear chemical-resistant PPE when working on known or suspected contaminated sites.
Support trial pit sides in unstable ground before allowing anyone to enter.
Follow the COSHH assessment for the specific contaminants expected at the site.
Handle and label samples using chain of custody procedures to prevent contamination.
Brief all operatives on the expected ground conditions and hazards before starting.
Wash hands and face before eating, drinking, or smoking during investigation work.
Cap and secure all boreholes after drilling to prevent falls and gas escape.

DON'T drill without confirming all buried services are located and clear.
DON'T enter trial pits in unstable ground without support systems in place.
DON'T handle contaminated soil or water without chemical-resistant PPE.
DON'T ignore gas readings from boreholes — they can change rapidly.
DON'T set up the drilling rig on soft or sloping ground without stabilisation.
DON'T eat, drink, or smoke in contaminated ground investigation work areas.
DON'T leave open boreholes or trial pits unguarded at the end of the day.
DON'T mix samples or use contaminated equipment between locations.
DON'T position the rig beneath overhead power lines without a safe approach plan.
DON'T assume clean-looking ground is uncontaminated — rely on laboratory results.

See also: Groundworks Safety Awareness | CAT and Genny Safe Use

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