Geotechnical Drilling

Summary

Geotechnical drilling is the specialised drilling undertaken to investigate soil, rock, and groundwater conditions that influence construction design, environmental risk, and site feasibility. It provides critical subsurface data for engineers, environmental consultants, and developers.

Definition

Geotechnical drilling is the controlled drilling and sampling of subsurface materials to characterise soil and rock properties, assess geotechnical stability, and inform the design of foundations, retaining structures, excavations, and remediation works. It supports both engineering design and environmental assessment, particularly on sites with contamination or complex ground conditions.

Why It Matters

Geotechnical drilling is essential for understanding the physical behaviour of the subsurface, which directly affects construction safety, structural performance, and environmental compliance. Without reliable drilling data, project teams face increased risks, including design failures, unexpected ground conditions, cost overruns, and construction delays.

Key reasons geotechnical drilling matters include:
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• Engineering certainty: Determines soil strength, bearing capacity, settlement parameters, permeability, and rock quality.‍
• Environmental assurance: Enables integrated investigations where contamination, groundwater, or geotechnical instability may influence remediation or construction feasibility.‍
• Regulatory compliance: Many development applications, environmental approvals, and remediation action plans (RAPs) require subsurface data to confirm risks and suitable land use.‍
• Hydrogeological insight: Supports groundwater modelling, dewatering design, and event-based monitoring where groundwater interactions are complex.‍
• Construction risk management: Identifies hazards such as fill material, voids, soft soils, acid sulfate soils, or geotechnical instability.
  
  

Geotechnical drilling also overlaps with environmental drilling, particularly on brownfield sites where both geotechnical and environmental samples must be obtained concurrently.

When It’s Required

Geotechnical drilling is typically undertaken during planning, design, or early construction stages to inform engineering decisions and risk assessments. Common triggers include:

Development Applications (DAs) and Approvals

Councils and planning authorities often require geotechnical investigations to support structural design, stormwater plans, or excavation risk assessments.

Major Civil and Infrastructure Projects

Road, rail, energy, and utilities projects require extensive drilling to map subsurface conditions along construction corridors.

Building and Construction Design

Drilling informs foundation selection, footing design, slab performance, retaining walls, and deep excavation support systems.

Contaminated Land and Remediation Projects

Where contamination intersects with geotechnical considerations—such as groundwater flow, soil permeability, or excavation feasibility—drilling provides essential data and sampling access.

Dewatering, Groundwater Management, and Hydrogeology

Installation of monitoring wells and groundwater extraction bores often begins with geotechnical drilling to characterise aquifer conditions.

Slope Stability or Geotechnical Hazard Assessment

Sites subject to landslip risk, erosion, or settlement require drilling to support stability modelling.

How We Can Help

Nova Group Pacific provides integrated geotechnical and environmental drilling programs, ensuring high-quality data that supports compliant, risk-aware design and remediation.

Our multidisciplinary services include:
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• Geotechnical Services‍
• Environmental & Geotechnical Drilling Services‍
• Environmental Compliance

Related Terms and Concepts

Explore related glossary entries to build your understanding of subsurface investigations:
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• Geotechnical Investigation‍
• Geotechnical Report‍
• Geotechnical Engineering‍
• Environmental Drilling‍
• Development Applications (DAs)‍
• Construction Environmental Management Plan (CEMP)‍
• Remediation Action Plan (RAP)