Balancing the Scales: Geotech and Environmental Sustainability

In engineering, sustainability is the practice of designing and creating solutions that meet our needs while minimising the natural resources we use.

It’s important that a solution does not harm the environment where the structure is built, and the environment that the natural resources used to build it are sourced from.

We must also consider the resilience of what we are designing. With the effects of climate change being increasingly felt through extreme weather events, it is important that what we design today can withstand any changes in climate over its intended lifespan.

Sustainability is a broad subject with a lot of contributing factors, so a multifaceted approach is required to make a geotechnical engineering project sustainable. Key considerations include:

Minimising waste and pollution during construction

Every effort should be made to minimise the waste that a geotechnical engineering project generates, and to deal with any waste that is generated in a responsible manner. By working in collaboration with environmental scientists, geotechnical engineering projects can ensure any waste generated during construction is managed correctly and in an environmentally conscious manner.

For example, retaining walls will often be designed with dimensions that are multiples of 0.3m, because the timber industry tends to use this increment when they sell planks or poles. Timber pole walls will be spaced at 0.9m or 1.2m increments to reduce waste.

Optimising the use of natural resources

You should aim to use the natural materials that are readily available in the area, to avoid sourcing and transporting bulk materials, which can have a significant environmental impact: it reduces the fuel consumption of the project, and the environmental effects of extracting the materials from their source.

Say you’re designing a retaining system. If the region lacks large boulders, they should not form part of the solution, as they are very inefficient to transport. The retaining system should instead utilise whatever resources are native to the area – perhaps silt or clay soils. Using local materials has the added benefit of increasing the project’s potential to better blend into its local environment.

The best use of natural resources extends to the management of the resource already on site. By utilising soil stabilisation and ground improvement techniques, geotechnical engineers can reduce the excavation required. Knowing what you are dealing with at a specific site is crucial for the best management of resources. By conducting a thorough testing regime as part of a geotechnical site investigation, geotechnical engineers are best placed to provide the most suitable solutions that reduce the waste generated on the site and increase the use of available natural resources.

A geotechnical engineer may also suggest soil stabilisation and ground improvement techniques to reduce the levels of excavation or raw material needed at a site.

While waste minimisation and optimising use of natural resources are basic tenets of any economic design, there may be situations in which we choose to go in a different direction, in consultation with the client.

Reducing the carbon footprint of infrastructure projects

A geotechnical engineer should work to calculate the carbon footprint of different solutions, balancing this factor with others like lifespan, durability, cost and ongoing sustainability to find the best solution.

Modern techniques make calculating the carbon footprint of a project a relatively straightforward affair, allowing our clients to compare and contrast different solutions.

A steel-based retaining structure, for example, may have a smaller carbon footprint than a mass gravity wall, and for a nominal increase in price. Timber would evidently be an even better solution if it can deliver the same overall durability and resilience characteristics as concrete and steel.

The expected lifetime of the project is a key consideration in any carbon footprint assessment. A temporary structure designed for 20 years will have different needs than one designed for the next 100 years. For shorter-term projects, any materials with a design life of more than 20 years will be wasted at the end of the project, so concrete would not be the ideal choice.

Geotechnical engineers will also work closely with civil engineers in designing earthworks that minimise the soil removed from a site. By collaborating during the design stage, civil and geotechnical engineers can strive for efficiencies in earthworks, saving labour and fuel costs.

Enhancing the resilience of structures to climate change impacts

It is critical to design structures to be resilient to future climate change impacts, such as anticipating the need for future expansion of river embankments to accommodate changes in water levels.

A river embankment of a certain height may be under-dimensioned in 20 years and the project would thus need to be demolished and replaced with an improved one. In this case, it may be more sustainable to design for the future and allow for expansion.

By working alongside other engineering experts, the resilience of infrastructure projects can be enhanced against extreme weather events. During a geotechnical site investigation, it is important for a geotechnical engineer to assess the potential climate change impact on a site. Investigations such as a Coastal Hazard Assessment provide guidance for current and prospective land owners on the potential impacts of environmental effects on a property.

Promoting the use of renewable materials

Renewable materials like timber, which can be grown, may be worth considering over non-renewable materials like steel and concrete, which are extracted. There are also new materials, such as geosynthetic-reinforced soil (GRS) retaining walls and glass fibre reinforced plastic (GFRP) soil nail bars, that are more environmentally friendly than traditional materials.

It is important to compare the strengths and weaknesses of renewable materials to more conventional materials, not just in terms of environmental considerations, but project requirements too, to make an educated choice. All else being equal, the renewable option should be the preferred choice.

There is generally a direct relationship between the local availability of certain materials and the carbon footprint of using those materials within your project. If materials need to be brought in from far-flung sources, more fuel will be used, and more carbon will be released as part of the process. These materials will therefore be far less sustainable than locally available materials.

In retaining structures, geotechnical engineers are trained to use in-situ soils first. Replacement materials should only be brought in as a last resort.

With a range of sustainability-focused responsibilities, geotechnical engineers are one of the key drivers of sustainability within any development project.

Sustainability informs decisions at every stage of the design and construction process: site selection and assessment, foundation design, material choice, waste management, habitat preservation and more.

The long-term performance and resilience of a construction project is also reliant on the geotechnical engineer considering the effects of climate change. Any piece of infrastructure must be designed to deal with challenges like sea level rise and an increased number of extreme weather events.

By integrating environmental, social and economic considerations into their work, geotechnical engineers can maximise the sustainability of any development they work on, ensuring that their projects are safe, durable and environmentally responsible.

Collaboration and innovation in geotechnical engineering to increase the sustainability of development

As one of the first steps in any construction project, geotechnical engineers have a unique opportunity to shape sustainable outcomes in the construction industry. By collaborating across disciplines and across industries, geotechnical engineers can steer construction projects along a more sustainable path.

Within Eliot Sinclair, our Geotechnical Engineers rarely work alone. Rather, they form an integral part of the planning and design team. By working holistically with environmental scientists, civil engineers, urban designers and planners, geotechnical engineers can create solutions that address environmental challenges.

Integrating sustainably focused geotechnical expertise in the early stages of a construction project can result in energy efficient designs that minimise carbon emissions and their environmental footprint.

By working closely with environmental scientists and water engineers, a sustainably focused geotechnical engineering solution can enhance water management, promote ecological diversity and help minimise soil erosion.

Taking geotechnical engineering factors into consideration during town planning and urban design stages can contribute to infrastructure that is resilient to future climate change.

There are many factors to consider to ensure your next construction project has a sustainability focus:

• Minimise waste generated by construction projects
• Design earthworks that minimise the material removed from a site
• Deal with any waste generated in a responsible and environmentally conscious way
• Optimise the use of natural and local resources, ideally utilising resources already available on site
• Calculate the carbon footprint of different solutions, take into consideration the expected lifespan of a project and select materials appropriately
• Consider future climate change impacts, designing solutions that are resilient to climate change and extreme weather events
• Conduct comprehensive site investigations that that assess potential climate change impacts
• Promote renewable materials and consider the use of more environmentally friendly materials

At Eliot Sinclair we take environmental sustainability seriously. Our expert geotechnical engineers work alongside our other experts to use advanced technology and techniques to deliver solutions that minimise environmental impacts during construction and over the project’s lifespan.

By focusing on sustainability at the first step in a construction project, we can shape developments with more environmentally conscious outcomes. Eliot Sinclair can work alongside your project from concept to completion, ensuring you have the advice and expertise needed to shape your project into one that grows sustainable communities, from the ground up. Find out how we can help your project.