Site Investigation and Soil Classification-factors to consider.

There is no place for guesswork when it comes to figuring out exactly what lies on or below a site. These features can have a big impact on a future development, potentially even bringing the project to a halt. 

A site classification will assess whether there are any geotechnical features that could have ramifications for development, or whether any contaminants are present on the site. 

Here are some questions to consider when investigating a site:


Do I need a Geotechnical Report? 

This is where a geotechnical engineer comes in. They are specialist consultants brought in to assess a site’s geotechnical features, including subsurface soil, rock and water conditions. The resulting geotechnical report is a vital tool for the structural engineer, architect and construction team, and absolutely necessary to ensure the project is safe and cost-effective. 


What information will a Geographical Report contain?

The basic essential information found in a report includes a summary of all subsurface exploration data. It will also contain analysis of the data, discussion of conditions for solution of anticipated problems, and any engineering recommendations.

For large projects or when complex geotechnical problems are expected it is common to carry out a “preliminary” geotechnical report. This may contain information necessary to establish basic concepts or design criteria early in the project. A “final” report is normally available at a later stage when the design has progressed.


Is Site Contamination an issue? 

Site contamination is the presence of man-made chemicals or other alterations to the natural soil environment. Contamination can often be the result of ruptured underground storage tanks, past pesticide use, wastes leaching from landfill or direct discharge of industrial waste to the soil. Soil contamination occurs when hazardous substances are either spilled or buried directly in the soil or migrate from spills that occurred elsewhere.


Will Site Contamination halt development?

It may still be possible to develop a contaminated site if certain steps are taken to make sure there won’t be any risk to human health or the surrounding environment. In this case a Remedial Action Plan will set out those steps and, once they are completed, an environmental engineer can issue a Site Clearance Certificate or Validation Certificate.


Why are Acid Sulphate Soils a concern?

Acid Sulphate Soils (ASS) are most commonly found in NSW along the coast and must be managed appropriately to avoid major environmental damage. ASS are those naturally occurring sediments and soils that contain sulphides, mainly iron sulphide and iron disulphide or their precursors. Exposure of these sulphides in the soil to oxygen – often as a result of drainage or excavation – can produce sulphuric acid, which may have a significant impact on the environment. Leaching of sulphuric acid into waterways can cause serious water quality problems, resulting in fish kills and damage to infrastructure, such as floodgates and bridges.  Understanding how to handle and dispose of both potential ASS (not yet oxidised) and actual ASS (already oxidised) is critical.


The module Site Investigation and Soil Classification counts towards your CPD points requirement for your builders licence.