Where Does All the Soil Go?

You see lots of building developments going up, and large construction sites. When developers clear the site and make the soil level or dig holes for footings or basement carparks - where does all that soil go?

Generally, the soil is treated as waste in order to get it offsite quickly.  Sometimes it has historical industrial waste mixed with it (asbestos, gasworks waste, coke, slag, metals, hydrocarbons). You need to classify the soil into a waste category before knowing how much it will cost. That is done by sampling it and comparing it to relevant state waste classification guidelines.

That step is extremely important and can be a significant cost consideration in a development/construction project. It can also cause delays and management and regulatory issues during your already time-poor project.

Soil management during developments is a significant factor for developers with large implications for cost, timeframes and sustainability.  A little knowledge of each state's waste, exemption and environmental regulations and approvals is essential.

In addition to soil, groundwater entering large excavations needs to be dewatered, sometimes treated, and get approvals for discharge to help manage it.  That can also be a tricky business and a thorough knowledge of waste guidelines and exemptions, and approval processes are essential to minimising the cost and minimising delays during your project.

An example of this is if you are a developer and need to excavate a 50 m x 40 m x 10 m deep level basement car park - that will be 20,000 m3 of soil to manage. 

Often in particular around city areas, there is historical fill impacted with old industrial waste and the soil requires testing a waste classification to determine where it can go.  Furthermore, stockpiling and then testing soil and waiting for laboratory results can take 1 week, and development/construction sites never have the available space.  The required truck movements for a truckload of 20, 000 m3 (excavated this is maybe 25,000 m3 or more, and may be equivalent to 40,000 tonnes or more of soil) may be in the hundreds of truck movements, which is not sustainable and leads to congestion and traffic management issues to overcome.

Furthermore, disposal of soil as waste to landfill (the easiest but most expensive option) is not sustainable.  In many states contaminated soil may cost $400 per tonne or more to transport and dispose to a landfill including government levies. 

Think for a second, for our  50 m x 40 m x 10 m deep level basement car park - that will be 20,000 m3 = about 40,000 tonnes, if all of that had historical contamination and the waste category landfill disposal and transport cost was $400/tonne, the total cost would be $16M in soil disposal costs alone.  

Sending soil to landfill is also not a preferred strategy in each state EPA Waste Hierarchies as it results in a contaminated landfill to later manage and emissions and additional transport risks with truck movements. Most EPA bodies prefer avoidance, reuse or treatment where possible. Most developers' budgets prefer that also.

iEnvi Advice 

Characterising your waste early is key to having time to select cost-effective solutions. iEnvi has a team that specialises in waste reuse and management to provide more sustainable and cost-effective innovative solutions for how you manage your soil and excavate waste and wastewater.  

We can help you look at retaining some soils for landscaping, onsite containment cells, subdividing lots with containment cells so that your site is unimpaired, and sorting and treating soil so that waste categorisation is reduced in level to significantly reduce the cost.

We also help navigate all the 'hidden' exemptions and approvals for your waste soil and water, so that your project will run smoothly and at considerably lower cost and disruption.

Useful Links: 

NSW:

Waste Classification Guidelines

Existing Resource Recovery Orders

General Immobilisation Approvals

QLD:

Waste Classification Guidelines

End of waste (EOW) framework

Exempt Waste and Applications

VIC:

Waste Classification

How to Manage Industrial Waste

Reuse of PIW - direct and secondary beneficial reuse

SA:

Characterising your waste

Resource recovery policy (2010)

iEnvi Website Related Links:

https://www.ienvi.com.au/waste-and-beneficial-reuse/