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Bjorn Raasch
Principal Engineering Geologist
Geotechnical engineering
Our experienced geotechnical engineers and engineering geologists assess soil, rock and groundwater conditions to inform design, consenting and construction.
South Island-wide Geotechnical investigations and reports Expert witness and independent advice South Island-wide Geotechnical investigations and reports Expert witness and independent advice South Island-wide Geotechnical investigations and reports Expert witness and independent advice South Island-wide Geotechnical investigations and reports Expert witness and independent advice
OUR SERVICES
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We undertake geotechnical investigations to understand soil, rock and groundwater conditions and how these vary across a site.
We scope and undertake a geotechnical investigation that best suits your project to help you understand the ground conditions at your site and prepare relevant geotechnical reports to support design, building and resource consent decisions.
The scope of investigation is tailored to suit the project and may include a site walkover, test pits, boreholes, CPT testing, groundwater level assessment and geomorphological mapping.
We then bring this information together in a geotechnical report, sometimes referred to as a soil report. Our reports describe site conditions and set out geotechnical considerations relevant to design, building consent, resource consent or subdivision.
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We use site-specific ground information to inform foundation recommendations for the proposed development.
Once ground conditions are understood, the next step is working out how the site can be developed. We provide foundation recommendations that reflect the identified conditions and the type of development proposed.
This may include consideration of variable soils, sloping ground, liquefaction potential, and shallow groundwater. Our geotechnical engineers identify geotechnical constraints and considerations that the structural engineers can take into account when developing foundation solutions for the site.
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Geotechnical assessment of slope stability and rockfall hazards on sloping and hillside sites.
Hillside and sloping sites often bring more complex geotechnical considerations. We assess slope stability and potential rockfall hazards to understand the nature and extent of risk associated with landform, geology and erosion processes.
Depending on the site, our work may include stability analysis, hazard assessment and input into mitigation or protection measures.
We prepare reporting to support building or subdivision consent requirements and to inform decisions about site layout, earthworks and design responses.
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Our geotechnical engineers can provide construction monitoring and subgrade inspections throughout construction as your project comes out of the ground.
We provide earthworks monitoring to observe ground conditions encountered during excavation and filling and to confirm works are carried out in accordance with approved designs and consent conditions.
This may include observation and testing of subgrade conditions, ground preparation and fill placement, with monitoring records and reporting completed as required by consent or project documentation.
We work closely with contractors and the civil project team during construction, as this is often the stage where ground conditions are exposed and quick site decisions are required.
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Independent geotechnical peer review and expert advice.
We provide independent geotechnical peer review where an objective assessment of investigation scope, assessment methods, reporting or design inputs is needed.
Our team also provides expert witness services where clear explanation of geotechnical matters is required for consenting, dispute resolution or legal proceedings.
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Assessing liquefaction and lateral spreading where earthquake-related ground behaviour needs to be understood.
Where liquefaction is a potential hazard, we assess liquefaction susceptibility and likely ground response, including lateral spreading when relevant. This work is often linked to Technical Category assessments (TC1, TC2 and TC3) and is documented as part of geotechnical reporting.
We take time to explain what has been assessed, what has been found and what the practical implications are for design, foundations and consenting. For residential projects and subdivision in particular, this allows project teams to discuss early what performance measures may be required.
HOW WE HELP
Geotechnical input is one part of a wider picture, helping to support decisions as a project moves from concept through design, consenting and construction.
If you’re building, subdividing, working on infrastructure or flood protection, we will work with you to understand the ground conditions and any geotechnical constraints relevant to your project.
We’re involved at different points depending on the site and what’s being planned. Sometimes that’s early, when options are still being explored. Other times, it’s to support design, consenting or construction once decisions are underway.
Across these stages, geotechnical input helps project teams understand ground conditions, identify relevant considerations and discuss what those mean for the project as it develops.
01
UNDERSTANDING THE GROUND
Geotechnical input begins with building an understanding of the ground conditions. This may involve reviewing existing information, site walkovers or field investigations, depending on what’s already known and the decisions being considered early in the project.
02
INTERPRETING & REPORTING CONDITIONS
Information from investigations is assessed and documented in a geotechnical report. This brings together observations, test results and engineering expertise so designers, builders and councils have a shared reference for site conditions and relevant geotechnical considerations.
03
SUPPORTING DESIGN & CONSENTING
As designs develop, geotechnical input is used to inform foundations, earthworks and site constraints. We work alongside architects, engineers and planners so ground conditions are considered in context and reflected appropriately in design and consent documentation.
04
CONSTRUCTION & REVIEW
For most projects, geotechnical involvement continues during construction. This may include earthworks monitoring, responding to site conditions as they’re exposed or providing independent review where an objective geotechnical perspective is required.
Contact our leaders
Have a project in mind? Contact our multidisciplinary team to see how we can help.
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We work with a wide range of clients, from homeowners to councils and project teams, and no two sites are ever the same. Our role is to understand the ground and work alongside the project team to provide geotechnical input and advice to help make informed decisions and manage risk from natural hazards.
Samantha Webb
Technical Director - Engineering Geologist
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Tall to a geotechnical engineer
Tell us about your project or what you need and we’ll be in touch.
FAQ
Got questions? We’ve got answers.
If your project involves the ground, you’ll likely need a geotechnical engineer. This includes building or extending a home, subdividing land, constructing driveways, retaining walls, roads or infrastructure, or developing on sloping or challenging sites.
Geotechnical advice helps you understand how the ground will behave, what natural hazards the site is subject to and what foundation or earthworks approaches are appropriate for your project.
A geotechnical investigation looks at the ground conditions beneath your site; for sloping or hill sites, this also includes what’s above and below your site. Depending on the project, this may include a site walkover, test pits, drilling or CPT testing, soil and rock sampling and laboratory testing.
We analyse the results to understand ground behaviour, identify potential natural hazards and provide clear, practical recommendations to support design, construction and consenting requirements.
A geotechnical report is a key part of the building and consenting process. It provides essential information for your builder, architect, structural engineer and consenting authority.
The report documents ground conditions, identifies any geotechnical hazards and explains how those conditions may influence foundation design, earthworks and construction. It’s commonly required to support building and resource consent applications.
Yes. Prepurchase assessments for residential sites are typically undertaken as a desktop exercise with a site visit to consider any potential geotechnical risks for properties being considered for purchase. We understand the time constraints of going unconditional and can typically get to the site within 1 or 2 days.
All subdivisions require a geotechnical investigation that includes a Statement of Professional Opinion on the Suitability of the Land for Subdivision signed by a CPEng geotechnical engineer to obtain subdivision consent. This typically includes test pits, boreholes and or CPT testing, along with an assessment of natural hazards under Section 106 of the Resource Management Act.
The amount of testing depends on the size of your property and the number of lots the land is being subdivided into. We’ll work with you to develop a geotechnical investigation that fits your subdivision plans and consenting needs.
Technical Categories (TC1, TC2 and TC3) describe how land is expected to perform during an earthquake, specifically in relation to liquefaction.
- TC1 sites are expected to perform well, with little or no liquefaction damage
- TC2 sites may experience minor to moderate damage
- TC3 sites may experience moderate to significant damage
We assess site conditions to determine the Technical Category and explain what it means for foundation design and consenting. TC2 and TC3 sites will require specifically engineered design (SED) foundations.
Yes. For sloping or hillside sites, we assess slope stability and potential rockfall hazards to understand whether natural hazards need to be addressed.
This work can include slope stability analysis, rockfall hazard assessment and, where appropriate, the design of rockfall protection structures. These assessments often form part of subdivision or building consent requirements.
If available, it helps to share architectural plans, previous geotechnical reports, subdivision information and any fill certificates for the site.
If you don’t have everything, that’s fine. We can talk through what’s available and what else may be needed based on your project.