Geotechnical Engineering
Before you design foundations, retaining structures or earthworks, you need to understand the ground. Cook Costello identifies risks like settlement, slope instability and liquefaction early, giving you the evidence needed to manage ground risk before it becomes a construction, consent or long-term performance problem.
Uncertainty is what makes ground expensive
If the ground at a site is unclear, the project carries that uncertainty through the design. That can mean more conservative foundations, bulkier retaining walls, more ground improvement, larger contingencies or late redesign.
We reduce that uncertainty early. By combining geotechnical engineering with in-house geophysics and accredited testing through Geocivil, we build a clearer understanding of how the soil, rock and groundwater are likely to behave. That means our recommendations are based on site-specific evidence rather than broad assumptions. The result is engineering that is safe, defensible and proportionate to the real ground conditions, rather than made more conservative because the ground has not been properly understood.
We operate in Northland, Auckland, Wellington and Christchurch, with knowledge of local ground behaviour, council expectations and common development risks in each region.
OUR CAPABILITIES
How we can help you
From early feasibility through to construction monitoring, we help clients understand the ground, manage risk, and design foundations, retaining and earthworks suited to the real site conditions rather than cautious assumptions.
Site Investigation & Testing
We investigate soil, rock and groundwater through drilling, sampling, in-situ testing and in-house geophysics. For complex projects, fieldwork can be supported by accredited laboratory testing through Geocivil, giving the design team reliable, site-specific information. Includes:
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CPT, machine boreholes, drilling and sampling
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Hand augers, Scala tests and excavated test pits
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In-house geophysics surveys
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Laboratory soil and rock testing
Feasibility & Site Suitability
We assess whether land is suitable for development and identify ground-related constraints early. Our advice helps clients understand risk, likely foundation implications and consenting requirements before committing to purchase, design or development. Includes:
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Pre-purchase assessments
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Geotechnical feasibility studies
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Natural hazard screening
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Development risk reviews
Geotechnical Reporting for Consent
We prepare clear, council-ready geotechnical reports to support resource consent and building consent applications. Our recommendations are clear, defensible and aligned with current standards, site constraints and local authority requirements. Includes:
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Resource consent reports
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Building consent geotechnical reports
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Liquefaction and seismic assessments
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Hazard hazard risk assessments
Foundation & Ground Improvement Design
We design foundation systems suited to the site, natural hazard risks and ground behaviour identified through investigation. Where conditions are difficult, we design ground improvements to manage risk and keep cost in check. Includes:
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Shallow and deep foundation design
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Ground improvement design and verification
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Bearing capacity analysis
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Settlement assessment
Slopes, Retaining Walls & Earthworks
We assess slope stability and design retaining structures, earthworks and temporary works solutions to manage land movement, support construction and improve long-term performance. Includes:
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Slope stability assessments
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Retaining wall design
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Earthworks specifications
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Temporary works advice
Construction Monitoring & Certification
We provide construction-phase observation, testing and certification to help confirm geotechnical works are completed in line with the design, consent provisions and project requirements before the next stage proceeds. Includes:
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Foundation inspections
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Earthworks monitoring
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Subgrade certification
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Producer Statements (PS4)
OUR PROCESS
What happens during a geotechnical asssessment
Every site is unique. These steps outline what typically happens during a geotechnical assessment, depending on the geological setting, site constraints and proposed development.
1. Initial Discussion & Scope
You contact us to discuss your project. We ask a few key questions about the site, proposed development and consenting requirements, then confirm the level of investigation likely to be needed.
2. Review of Available Information
We review existing reports, site plans, hazard maps, council records and other available information to understand known ground conditions and risks before attending site.
3. Site Investigation & Testing
We carry out field investigations such as drilling, test pits, in-house geophysical surveys or in-situ testing to understand soil, rock and groundwater conditions. Samples may be laboratory tested where required.
4. Engineering Assessment & Design
We analyse the investigation results to assess ground risks and develop clear recommendations for foundations, retaining walls, or ground improvement matched to the site-specific characteristics and natural hazard risks.
5. Reporting & Next Steps
We provide a clear, council-ready report outlining the ground profile, identified risks and recommended design solutions. We then discuss the findings and support you through consent, design or construction where required.
Connecting ground investigation to design
Geotechnical questions rarely sit on their own. The ground affects foundations, earthworks, retaining structures, drainage, construction sequencing and long-term performance, so connecting the investigation to the rest of the project is where real value is added.
At Cook Costello, our geotechnical engineers work alongside in-house structural, civil and surveying teams, supported by geophysics specialists and accredited testing through Geocivil. That means ground conditions can be investigated, interpreted and carried through into design without unnecessary handovers between separate consultants.
Because the disciplines work together from the beginning, the ground model informs the design earlier. This helps reduce delays, avoid duplicated effort and identify risks while there are still alternative options available.
Selected projects across New Zealand
OUR LOCATIONS
Geotechnical services by region
Ground conditions vary significantly across New Zealand. Choose your region for guidance on local ground behaviour, common development risks and geotechnical input likely to be needed.
Geotechnical engineering in Auckland
Auckland projects often involve volcanic terrain, highly variable residual soils, coastal slopes, flood-prone land and constrained urban sites. These ground conditions affect subdivision feasibility, foundation design, retaining walls and construction methodology.
Geotechnical engineering in Wellington
Wellington’s steep terrain, high seismic demands, variable ground and tight urban sites can make geotechnical risk central to feasibility and buildability. Early geotechnical input helps identify development constraints and keeps projects moving on difficult ground.
Know your ground before you design or build
Tell us about your site and what you are planning. Our geotechnical engineers will review your project and give you clear advice on the investigation likely to be needed, the ground risks to be aware of, and the next steps before you commit to purchase, design or consent.