The soil test or site classification report includes site inspection and 2-3 shallow tests to assess subsurface soil conditions. Also, the site classification report is suitable to use as primary data for structural engineers to design footings for residential projects. As a result, the soil tests are performed in accordance with Australian standard AS2870-2011 residential slabs and footings.
Cost of Soil tests in Brisbane
Due to the number of boreholes and depth of tests, the cost of site classification reports varies. For small residential dwellings, small extensions, and new sheds or pools, 2-3 boreholes should be sufficient to find out the site classification and it costs around $450-$550 for flat sites. Each site has its own different type of soil and structural engineers or designers never should use the soil test from neighboring properties as each site is unique in terms of soil type and site classification.
What is site classification?
Each site has an appropriate site classification for footing design in accordance with
AS2870-2011 (refer Table 1).
Table 1 – Definition of Site Classifications (Australian Standard AS2870-2011)
| Class | Foundation |
| A | Most sand and rock sites with little or no ground movement from moisture changes |
| S | Slightly reactive clay sites with the only slight ground movement for moisture changes (ys<20mm). |
| M | Moderately reactive clay or silt sites, which can experience moderate ground movement from moisture changes (ys 20-40mm). |
| H1 | Highly reactive clay site, which can experience moderate to high ground movement from moisture changes (ys 40-60mm) |
| H2 | Highly reactive clay site, which can experience high ground movement from moisture changes (ys 60-75mm) |
| E P | Extremely reactive sites, which can experience extreme ground movement from moisture changes (ys>75mm) Class P – problem sites: ground movement as a result of moisture change may be very severe, you will need to consult a structural engineer before building a new house. |
ys: Characteristic Surface Movement
The standard site classification report will address;
- Subsurface conditions and interpreting the borehole tests.
- The existing soil classification is in accordance with AS2870-2011.
- Any earthworks required to obtain a classification suitable for development.
- Groundwater if it’s encountered.
- Borehole location plan.
The cost of a detailed geotechnical investigation report in Brisbane, Gold Coast, Sunshine Coast, and Logan
A detailed geotechnical investigation in Brisbane suburbs is required for complicated sites, sites prone to potential liquefaction hazards, prone landslide and slope failure, and commercial projects. The investigation and reporting are needed by local authorities and structural engineers to confirm requirements for complex sites and commercial sites. Depending on the size and complexity of each project, the geotechnical investigation will typically consist of:
- Shallow ground testing to 3.0m depth including Hand Augers, shear vane tests, and Scala Penetrometer tests.
- Deep ground testing, which will include cone penetrometer tests (CPT) to a minimum of 15-20m below ground level where ground conditions allow, or Machine Borehole Tests, where CPT tests cannot be undertaken.
Geotechnical Investigation Report
The price for a detailed geotechnical investigation and reporting is highly variable so there might be unforeseen conditions, that may require further testing excavation, laboratory testing of soils, and external peer review.
For our availability please contact our Brisbane branch and email us at [email protected]. For super urgent jobs, the turnaround time can be reduced.
Hillside Geotechnical Investigation (Brisbane, Gold Coast, Ipswich, Logan, Toowoomba & Sunshine Coast
The scope includes site inspection for a preliminary assessment of site stability and geohazards and carryout shallow testing to assess ground condition followed by a preliminary reporting including soil logs and a site plan.
The investigation and report will be required by local authorities and structural engineers to confirm foundation options and retaining wall design requirements. Two-three 3.0 -4.0m deep hand augers, Scala Penetrometer Tests, and shear vane tests.
The geotechnical report will include but is not limited to:
- Subsoil ground conditions and soil profile,
- Foundation Recommendations, or recommendations for further testing
A preliminary estimate of the price for the slope stability report within Brisbane, Gold Coast, Sunshine Coast, Logan, and Toowoomba areas is between $1,800 – $4,000.