Geotechnical Investigations and testing, AS 1726

When a residential site classification won't cover the risk, the project needs a full geotechnical investigation. We drill, log and sample to AS 1726, test to AS 1289, and produce a report that sets out what is in the ground: the factual basis your design team, civil engineer or certifier needs to design, price and approve the work.

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When you need AS 1726 rather than AS 2870

An AS 2870 site classification covers a standard house on a conventional lot. It stops short of most other ground risk on a project. Commission an AS 1726 investigation when the job involves:

Commercial buildings, warehouses and industrial slabs

Subdivisions, roadworks, pavements and civil infrastructure

Proposed developments, feasibility and pre-purchase due diligence

Sites with undocumented or suspected fill

Slope and global stability, retaining walls, batters and deep cuts

Acid sulfate soil risk on coastal and low-lying land

Contamination and contaminated land

Pavement investigation and subgrade parameters

Bearing capacity or settlement that can't be assumed

Groundwater, seepage or excavation stability affecting the build method

Not sure which you need? Send the plans and we will tell you. Site classification, AS 2870

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What the investigation covers

Fieldwork. Boreholes and test pits set out across the site, not only at the proposed structure, positioned to establish topsoil and rock depths, unsuitable material and potential borrow areas as well as founding conditions. Soils logged and described to AS 1726, which sets the terminology for soil type, consistency, moisture condition and structure. Samples recovered from relevant design depths and areas of interest.

In situ testing. Dynamic cone penetrometer and hand auger profiling, with pocket penetrometer readings on cohesive soils. Standard penetration testing and shear vane testing arranged where the investigation calls for it.

Laboratory testing. Through NATA accredited facilities, scoped to what the project requires. Classification, strength, moisture and reactivity testing to the AS 1289 series.

Interpretation. Ground conditions interpreted and reported, covering bearing capacity, settlement, excavation conditions, groundwater, earthworks requirements and material suitability, as the factual basis for the project team's design.

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What you get

A site plan showing borehole and test pit locations

Borehole and test pit logs to AS 1726, with the profile described layer by layer

Laboratory results, with the methods stated

Groundwater observations where encountered

Ground parameters for your engineer to design from: bearing capacity, settlement estimates and founding depths

Earthworks and excavation advice, including material reuse and on-site borrow potential

A clear statement of the investigation's scope and limitations

RPEQ certification arranged where the approval requires it, for statutory, council and contractual submission

Sectors we work in

Residential subdivisions and multi lot developments · Civil infrastructure, roads, bridges and culverts · Commercial, retail and industrial development · Stormwater and drainage infrastructure · Bulk earthworks, cut and fill and borrow pit assessment · Local government infrastructure and development assessment

Seven years supervising and consulting on more than 300 civil construction sites. About Luke

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How a job runs

Scope. Send the drawings and tell us what the report has to support.

Fieldwork. Boreholes or test pits, logged and sampled on site.

Testing. Laboratory work through NATA accredited facilities, to the AS 1289 series.

Report. Ground parameters and interpretation, written for the engineers who have to design from them.

Ongoing project support as required.

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Get a fixed quote

Send the site address, the lot and plan, and any drawings you have.

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or Call 0408 861 788

Common questions


How deep can you drill?

Hand auger drilling to 1.8 metres, for sites with restricted or difficult access where conventional drilling equipment cannot be used. Outsourced 4WD truck-mounted drilling using hollow flight auger equipment, with drilling available to depths of up to 20 metres, subject to site conditions and access.

Can you combine a geotechnical investigation with wastewater or acid sulfate work?

Yes, where each scope still gets the investigation it needs. Tell us everything the project has to satisfy and we will scope it in one visit where we can.

How long does a geotechnical investigation take?

Subject to project scope. Field investigation is generally completed within a day. Laboratory testing time depends on the type and quantity of tests.

Do you provide geotechnical soil testing for existing structures?

Yes

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Coastal Geo Consulting Licensee: Luke James Whittaker Licensed under the QBCC Act · QBCC Licence No: 1534 8305


6am–5pm, seven days 


South East Queensland & Northern NSW

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