Handling Excess Soil from Excavation and Hydroexcavation
Lisel Dingley • March 27, 2026

When is it a resource? When is it a waste?  And what do you actually need to do?

Managing excess soil from cut/fill activities and hydroexcavation is one of the most commonly misunderstood environmental and planning compliance risks on construction sites. Soil can be one of the most valuable resources on a construction site, but poor management can quickly become extremely costly.


1. Soil: Resource or Waste?

Soil is a resource when it is:

  • Suitable for its intended reuse, and
  • Reused for a lawful and beneficial purpose (either within the project or at another suitable location)


Soil becomes a waste when it is:

  • Surplus to requirements, and
  • Discarded, disposed of, or requires treatment before it can be reused


This distinction is critical. Stockpiling soil “just in case” without a defined reuse purpose can shift it from resource → waste.


2. Contamination Considerations

Before any off-site movement or reuse, you must understand if the material is potentially contaminated. Some indicators might be:

  • The land is listed on the EMR or CLR
  • Notifiable activities have occurred on the land (whether listed or not)
  • Known or suspected historical spills
  • Mine spoil or deeply excavated material
  • Naturally mineralised soils
  • Areas affected by demolition (e.g. potential asbestos containing material)
  • Imported fill of unknown origin
  • Presence of biosecurity matter (e.g. weeds)


These indicators signal a risk that the material may contain contaminants. Material may be contaminated, even if it appears clean. Laboratory analysis may be warranted, with comparison to regulated waste classification thresholds and/or National Environment Protection (Assessment of Site Contamination) Measure (NEPM), Schedule B1 as relevant.


3.  Can the receiving lot legally accept it?

Even if soil is suitable for reuse, the receiving site must be legally able to accept it.


If managed as a resource:

  • Placement must be for a lawful and beneficial purpose
  • If volumes exceed relevant Operational Works (Earthworks) thresholds under the local planning scheme, the receiving lot may require a Development Approval.  These thresholds vary by local government (often around 50 m³, but not always).

Important:  Even movement within a project can trigger regulatory requirements if material is transported across lot boundaries.


If managed as a waste:

  • The receiving site must be appropriately authorised, such as:

- ERA 60 (waste disposal), or

- ERA 62 (waste transfer and processing)

*Waste levy, transport, and disposal costs will apply (waste levy will be $100/tonne or more, in addition to haulage and landfill disposal fees)


There are potentially some opportunities for a receiving landfill to apply for a waste levy exemption for clean earth for use as day or intermediary landfill cover. It is up to the discretion and operational needs of the landfill to allow this as an option, but as the disposer, offering to pay for the preparation of the waste levy exemption application can position you well, and has the potential to save you millions of dollars from an investment of just a few thousand.


4. Hydroexcavation Material – Not Just “Water”

Hydroexcavation produces a slurry comprising:

  • Soil/sediment
  • Water
  • Potential contaminants (e.g. hydrocarbons, salts, metals)

This material is not simply “water” and should not be assumed to be suitable for discharge or reuse.


In most cases, hydroexcavation waste:

  • Requires assessment prior to reuse
  • Will be classified as a liquid waste or regulated waste, depending on contamination, unless a suitable on-site reuse opportunity is available


Key considerations include:

  • Can it be beneficially reused on-site without causing environmental harm?
  • Does it require dewatering prior to reuse or disposal?
  • Is disposal to a licensed facility required?
  • Does waste tracking apply?


Inappropriate discharge of hydroexcavation slurry can constitute environmental harm.


5. Temporary vs Permanent Stockpiling

Temporary Stockpiles (during construction) are generally acceptable where:

  • There is a clear reuse purpose
  • Stockpile duration is limited
  • Appropriate controls are in place:

- Erosion and sediment controls

- Stabilisation (if long duration)


Permanent Stockpiles

  • Permanent or long-term stockpiling introduces additional risk and often requires Development Approval.
  • Demonstration that the activity is not waste disposal


Generally, soil cannot be stockpiled indefinitely and without a defined use, unless it was indicated on the final landform approved as part of the Development Approval.


In Closing

Most soil management issues don’t arise from complex contamination — they arise from poor planning and unclear intent.


Soil is one of the most valuable resources on your site. Used well, it reduces costs and supports better environmental outcomes (particularly rehabilitation/revegetation). Managed poorly, it quickly becomes a liability — triggering approvals, disposal costs, and compliance risk.


Effective soil management begins with thoughtful cut and fill planning to minimise excess and avoid turning a valuable resource into a liability, and concludes with well-executed revegetation to stabilise the site and minimise future erosion and soil requirements.


Want to explore waste classification thresholds or NEPM further?  Check out our Resources page for direct links to these resources.

Resources

Groundwater Monitoring - Does compliance with your Environmental Authority mean you have met your General Environmental Duty?

By Lisel Dingley • November 19, 2024
Hypothetical Situation: A site’s Environmental Authority lists a number of groundwater bores, and states that they must be monitored for certain parameters 6 monthly. The EA has another condition which states that a groundwater review must be undertaken every 3 years by an appropriately experienced person (hydrogeologist). The site diligently samples the groundwater bores, and collates the field and laboratory results into a spreadsheet. However, those results are not reviewed when they are received… because the EA says that a groundwater review must be undertaken every 3 years, with no other specific review obligations. Given groundwater monitoring is intended as a warning system for contamination, is only reviewing the groundwater results every 3 years adequate to meet the General Environmental Duty of the Environmental Protection Act? Or a general EA condition such as the requirement to take all reasonable and practicable measure to prevent or minimise the likelihood of environmental harm being caused by the activities? When a dam containing hazardous waste is found to be leaking (found upon visual inspection), and subsequently the previous two years of groundwater data are reviewed and found to indicate this has been occurring prior to the visible leak being detected, it is likely this will not be looked upon favourably in a prosecution. “But it wasn’t time for our 3 yearly review!” is unlikely to be acceptable to the Regulator. Perhaps the EA has another condition which states that deterioration of groundwater quality must be reported to the Regulator within 14 days of receipt of the results. If data is only reviewed every 3 years, how is this condition being met? Perhaps the EA has a condition that requires the development and implementation of a Groundwater Monitoring Plan. It is suggested an adequate Groundwater Monitoring Plan should include guidance on interpretation of results, not just what, when and where to monitor. In our opinion, a Groundwater Monitoring Plan without interpretation guidance is defective and non-compliant with the intent of the condition. And if it does have guidance, is this clear enough to be accurately and swiftly executed by site personnel?  We see many shortcomings in groundwater monitoring. Some of the most common and most significant include: · Data that clearly demonstrates potential environmental harm, which has not been noticed or investigated. There are some really easy ones in this space – your groundwater should not have PFAS in it! If it does, you either have identified contamination of the aquifer or contamination of your samples by your sampling methodology or the laboratory. Regardless, this should be promptly investigated. · Sites not being aware which of their bores is a leak detection bore and which are aquifer monitoring bores. One should be dry and the second should not be dry, and if this is not the case, this needs investigating. · Sites not having modelled groundwater flow direction to determine what is an upgradient (background) monitoring bore, and what is downgradient (identification) monitoring bore, and therefore not being able to interpret results adequately. · Not monitoring water quality in ponds that have the potential to leak, and therefore being unaware of the potential contaminants that would indicate seepage into the aquifer from the pond. Groundwater monitoring can be a highly effective detection system of potential environmental harm, but only if it is undertaken well, by persons with a comprehensive understanding of monitoring well construction, groundwater and contaminants, and with an adequate system of bores in place.

Can you always legally clear Category X (White) Vegetation?

By Lisel Dingley • September 17, 2024
Definitely not! We have put together a quick list of aspects which might mean you cannot clear your Category X Vegetation. If Protected Plant Trigger Mapping exists across the area you intend to clear, and you have not had a flora survey undertaken and/or have a protected plant clearing permit. This can also apply if protected plants exist without trigger mapping. If the clearing is through a mapped waterway for waterway barrier works and may constitute a temporary (or permanent) barrier. If the clearing is through a watercourse, and does not meet the exemption requirements of a Riverine Protection Permit, and you do not hold a Riverine Protection Permit. If you are not within your lot boundary, for example, when you lot or your adjoining lots are intersected by a mapped easement such as for a river or road, or you want to clear in the road easement in front of your property. If your clearing will (or may) disturb an animal breeding place and you do not have a Species Management Program in place. If your clearing will include ground disturbance and you have not met your Cultural Heritage Duty of Care requirements. If the vegetation is mapped as protected under a local government planning scheme, and you do not have an approved clearing permit from the local government. We often work with landholders who have unintentionally undertaken unpermitted clearing, and are subject to enforcement action by the Regulator. Remedying this is costly and time consuming. This is not a space for ‘act now, and ask for forgiveness later’. You may find yourself planting back out the trees you cleared plus 50% more, and being committed to ensuring their survival for the next 15 years.

Subsurface Challenges: How Renewables Projects in Queensland Fail to Identify Dispersive Soils in Planning and Initial Stages, and the Subsequent Consequences

By Lisel Dingley • August 27, 2024
In Queensland, it's no secret that the renewables industry is booming. However, consistently, particularly in the south of the state, these projects are quickly encountering an unexpected challenge - dispersive soils. While those in the erosion and sediment control field could reasonably foresee this based just on the geographic location or through a brief site visit only, consistently renewables projects are not aware of this aspect until well into construction, when unexpected erosion issues start to emerge. It may be surprising that these very significant projects, with budgets of hundreds of millions of dollars, can overlook an aspect that is likely to cause considerable challenges if management is not planned and budgeted. Failure to identify dispersive soils in project scoping and planning can result in development of inappropriate erosion and sediment control plans, unsuitable rehabilitation plans, failing rehabilitation, and lengthy maintenance periods of erosion and sediment controls until groundcover is achieved (including desilting, reshaping, restabilising). Drains fail due to erosion, releasing sediment which settles downgradient, reducing drain capacity, resulting in drain overtopping and sediment deposition onto roads or hardstands (reducing trafficability) or releasing sediment into waterways. Erosion and poor stormwater management from failed drainage can mean water is not managed as per design and begins to erode in and around infrastructure, including roads, hardstands, solar panel piles, and waterway culvert crossings, resulting in expensive repairs of often difficult to access areas (particularly in solar construction due to tracking infrastructure). Some projects believe they will solve their erosion issues with hard reinforcing, like rock placement (riprap) or shotcrete or concrete, and are consequently shocked when these expensive repairs are promptly undermined. These impacts can result in landholder and broader community complaints, environmental consequences, compliance challenges, and costly rework. During project planning, there are multiple avenues to identify this challenge. From an initial desktop perspective, publicly available soil mapping with attached descriptions could be reviewed, which will indicate dispersiveness. Even at the highest level of state-wide soil classification, the considerable portion of the state mapped as sodosols should be an indication of potential dispersiveness, named due to high concentrations of exchangeable sodium, driving sodicity, which often results in dispersion. Assuming these aspects are overlooked, the early onsite inspections allow for an opportunity to visually observe indications of dispersive soil, often presenting as gully erosion along pre-existing roadsides and along farm tracks, or as gully or tunnel erosion adjacent to waterways, which contain the classic 'chocolate milk' water. These inspections are generally undertaken by ecologists and geotechnical engineers, and rarely, if ever, by erosion and sediment control specialists. Identifying this potential constraint is not in their purview, or skillset. Geotechnical investigations always include Emerson Testing, which is a measure of the dispersiveness of a soil, however this almost always is restricted to the depth of the base of foundations, well below the topsoils or subsoils likely to be disturbed, exposed, and requiring final stabilisation. However, even when shallower soils indicate dispersiveness, such as being Emerson Class 1 or 2, this is often only considered in foundation design, and is not considered in drainage design, erosion and sediment control or rehabilitation scoping, planning and budgeting. Due to these common oversights, it is important to turn our attention to developing improved recommendations for renewables developers to identify dispersive soils, and communication of these. Using a common ~40 turbine wind farm as an example, which is generally linear infrastructure (consisting of significant lengths of roads connecting turbines), and taking guidance from the IECA White Books, Chapter 3 Site Planning, Table 3.2, the required number of sample sites would be in excess of 930. Using an estimate of 1 sample location per 30 mins, it is unlikely that a wind developer will be interested in 232 days of soil sampling prior to/during project scoping. While the gold standard would likely consist of a full-scale soil survey including sampling for all relevant characteristics (including dispersiveness) and development of associated soil mapping, with final micrositing of project infrastructure (particularly wind turbines) having consideration of soil characteristics, it is unrealistic to move immediately from the current process to this. In order to identify the existence of dispersive soils, a well-designed reduced soil sampling program and analysis suite is possible, which will fast track the process and reduce costs. In our experience, Emerson Aggregate Testing has not proven to be a reliable indicator of dispersion, if other soil characteristics are disregarded. If targeting dispersion only, a more suitable suite is one that includes, at least, exchangeable basic cations (Calcium, Magnesium, Potassium, Sodium), Cation Exchange Capacity and Particle Size Distribution, in addition to Emerson Aggregate Testing (EAT). In our experience, soils can exhibit severe dispersion in the field, and have exchangeable cation aspects which would indicate a high likelihood of dispersiveness (such as sodic or magnesic soils), but have moderate to low dispersiveness based on Emerson testing. The reason for this is currently unknown comprehensively, though some theories are held and are under investigation. Furthermore, sands and gravels are unsuitable for Emerson testing, and failure to undertake Particle Size Distribution (or field assessment) to identify these may result in EAT scores that indicate negligible dispersiveness, yet the soil may lack soil cohesiveness, which tend to erode regardless of dispersiveness.  Identification of dispersive soils is critical in the planning and design stage of renewables projects to prevent budget blowout. Topsoils and shallow subsoils should be included in sampling regimes as part of project scoping, or at least, early works. A reduced sampling density and analysis scope is suggested to be sufficient for this purpose, and should be undertaken by all renewables developers.
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