The Opportunity

Geotechnical engineering can and should be considered more often for better sustainability outcomes. All facets and stages of projects can be more sustainable.

Buildings are responsible for ~39% of global CO² emissions.

The operational phase of a building contributes ~71% of this total, and opportunities for emission reduction arise during the building’s lifetime.​

Typically, 29% of total building emissions come from the construction process (the ’embodied carbon’ of the building). This phase includes materials manufacturing and transportation, construction, maintenance, renovation, and demolition.

The examples below show how initial geotechnical input doesn’t have to include anything more than investigation. In these examples, further geotechnical involvement occurred later during the design development stage which resulted in positive outcomes.​

Key Learnings

Generally speaking, using these approaches have a higher perceived risk than ‘conventional’ geotechnical engineering solutions. This highlights the importance of stakeholder collaboration to discuss the potential environmental outcomes, cost savings and associated risk profiles with adopting alternative geotechnical solutions.​

Example 1 – Uncontrolled Fill​

This project involved construction of a fill embankment for a new road and roundabout. Initial site investigation identified significant uncontrolled fill. Recommendations led to a design that minimised the earthworks excavation and rework operations (i.e. to leave as much uncontrolled fill in the ground as possible).​

Saved the removal of ~60 000 cubic metres of material​

• No transport of this material by road​
• No placement of this material in landfill​
• No transport of imported fill to be placed instead​

​Construction saving estimated at 2M AUD​

Example 2 – Shallow Foundation vs Piles​

Initial site investigation of an 8 storey building with no basement concluded that foundation design options were limited to rafts and piled foundations. Additional testing to investigate the feasibility of shallow foundations found that they would be suitable, subject to monitoring of foundations base during construction and shallow remediation of upper ~1m of loose silty sand.​

Saved  ~900 cubic metres of concrete and steel, which is equivalent to 450t CO²​

• No additional equipment or machinery required at the site​

Construction saving estimated at 1M AUD​

Example 3 – Better Geotechnical Parameters​

A multi-storey apartment building founded on limestone had previously been reported to have an allowable bearing pressures for shallow foundations of up to 250kPa. through discussion between the geotechnical and structural engineers / teams this was increased to 400kPa. By using higher allowable bearing pressures, smaller footings were possible across parts of the site. ​

​Saved  ~900kg CO² per footing – which equates to 38% less carbon​

Construction saving estimated at 50 000 AUD​​