Soil testing is the foundation (pun intended) of every successful construction project. No matter what you’re planning to build, understanding the soil beneath your site is critical in the design phase, ensuring safety, compliance, and structural integrity.
For most residential construction projects a site classification report is required. For larger developments, a more comprehensive soil report called a Geotechnical investigation report is typically required.
At Southern Geotech, we specialise in providing detailed soil testing and analysis that gives engineers, architects, and builders the knowledge to design foundations that are appropriate.
Site Classification Report
Soil Testing for Residential Construction
In Victoria, a site classification report, often referred to as a soil test, is a vital first step required at the design stage of a residential construction project. All new constructions must have a soil report to obtain a building permit.
Soil testing helps determine the bearing capacity and stability of the ground the foundations are laid on, ensuring the structure’s safety and compliance with building regulations.
In Melbourne, residential structures that commonly require a site classification report include:
- New Buildings
- Extensions and Major Renovations
- Second Story Extensions
- Pools and Retaining Walls
During a site classification, a qualified geotechnical engineer will collect soil samples from your property. They’ll dig boreholes to analyse the soil profile and test various characteristics, like moisture content and plasticity. Once the samples are tested in a lab, the engineer can classify the site into one of several categories.
Here’s a look at each classification and its implications:
- Class A (Stable): Composed of sand or rock, these soils experience minimal movement. Foundations can be shallow with standard slab designs, as there’s little risk of shifting.
- Class S (Slightly Reactive): Slightly reactive clay sites may experience minor movement. Shallow footings with reinforced slabs are typically sufficient to accommodate slight shifts.
- Class M (Moderately Reactive): These clay or silt soils undergo moderate movement. Foundations might require deeper footings or stiffened slabs to prevent cracking due to moisture changes.
- Class H1 and H2 (Highly Reactive): Highly reactive clay sites experience significant movement. Deeper foundations with specialised designs, such as waffle slabs or piers, are necessary to manage the high reactivity.
- Class E (Extremely Reactive): These sites endure extreme movement, requiring very deep foundations and complex engineering solutions like suspended slabs to mitigate risks.
- Class P (Problematic): Includes soft soils, landslips, or areas with abnormal conditions. These sites need thorough investigation and custom foundation solutions such as deep piers or mat foundations to ensure stability.
In Victoria, the National Construction Code (NCC) and the Building Regulations 2018 use these classifications to guide foundation design. For instance, highly reactive soils (like Class H or E) may need deeper or specialised foundations to handle significant movement, while stable soils (Class A) can typically support standard designs.
The Victorian Building Authority (VBA) makes sure that all construction complies with these standards, ensuring architects and engineers create resilient structures that can handle Melbourne’s diverse soil conditions.
Additionally, this knowledge can inform other aspects of your project, including landscaping and drainage systems. For instance, knowing how your soil retains moisture can help you make informed choices about plant selection and water management.
Common Soil Types Found in Melbourne
Each type of soil also falls under specific classifications that indicate its reactivity and implications for building.
- Clay Soils: These dense and reactive soils are found throughout Melbourne. They expand when wet and contract as they dry, which can lead to foundation issues. Clay soils typically fall under Class H1 or H2, indicating a high potential for ground movement.
- Sandy Soils: Commonly found in coastal areas, sandy soils drain well but don’t retain moisture or nutrients effectively. These soils are generally classified as Class A (stable) or Class S (slightly reactive), depending on their specific characteristics.
- Loamy Soils: A balanced mix of sand, silt, and clay, loamy soils provide good drainage and moisture retention. They usually fall under Class A or Class S, supporting shallow foundations well and being ideal for gardening.
- Volcanic Soils: Found in regions like the Yarra Valley, volcanic soils are nutrient-rich and well-drained. These soils can be classified as Class A due to their stability but may require specific designs based on their unique properties.
- Silty Soils: Composed of fine particles that retain moisture but can compact easily, silty soils may be classified as Class M (moderately reactive) or even Class H1, depending on their behavior with moisture changes. Building on silty soil requires careful consideration of potential settlement issues.
In Melbourne, soil depth significantly affects bearing capacity across various soil types. Generally, the bearing capacity increases with depth due to the higher overburden pressure and reduced influence of surface conditions like moisture fluctuations.
Deeper soil layers tend to be more compact and stable, providing better support for structures. However, the specific impact on bearing capacity also depends on the soil type; for instance, clay may still exhibit reactivity at depth, while sandy soils might offer consistent support due to their drainage properties.
Soil Testing for Non Residential Projects
Geotechnical Investigation
When it comes to commercial, institutional, and Industrial developments, precision is paramount. At Southern Geotech, we specialise in crafting Geotechnical Reports & Investigations tailored for non-residential projects.
Our rigorous testing and experience-based approach delves deeper, essential for the success and longevity of your project.
Our Geotechnical Investigation Reports span a diverse spectrum of non-residential projects, including but not limited to:
- Factories/Warehouses
- Commercial Structures & Shopfronts
- Retaining Walls
- Sports Field Infrastructure inc. Netting and Scoreboards.
- Sporting Pavilions
- Lighting, Telecom & Meteorological Towers/Installations
- Pavement/CBR Investigations
- Playgrounds, Boardwalks and Shelters
- Schools, Kindergartens & Daycare Facilities
- Hospital, Medical & Aged Care Facilities and Upgrades
Soil Contamination Testing
Site Assessment / Characterisation
As part of our comprehensive service offerings, Southern Geotech also provides Soil Contamination Testing.
Contamination Testing is essential for assessing the presence and concentration of harmful substances or pollutants in soil samples. Various analytical techniques are employed to detect and quantify contaminants present in the soil.
Following the testing process, a detailed report is generated summarising the findings. This report includes contaminant concentrations, sampling methods utilised, and any recommendations for remediation or further action.
Soil contamination testing is crucial for regulatory compliance, environmental monitoring, and site remediation efforts, helping to safeguard public health and ecological balance.
Soil Testing for Stormwater
Saturated Hydraulic Conductivity (SHC) Test
In areas where offsite stormwater disposal is not permitted, onsite solutions become essential. A Saturated Hydraulic Conductivity (SHC) test evaluates the soil’s ability and rate it absorb water, providing crucial data for the design engineer to appropriately size the proposed system according to the site’s specific requirements.
By offering these specialised assessments, we ensure that your stormwater management systems are designed with precision and efficiency, tailored to the unique characteristics of your site while adhering to regulatory standards and environmental considerations.
