Contaminated land

Land contamination can affect one or more media of the environment including soil, groundwater and soil vapour. Land contamination can occur as a result of poor environmental management and waste disposal practices or accidental spills in industrial or commercial activities. In the past, land was sometimes contaminated by activities that were not known to be dangerous at the time, often using chemicals that have since been banned or now are subject to much stricter controls.

Assessment of site contamination may be required as a results of various triggers. The triggers may include change in land ownership, the proposed change of a site for a more sensitive land use, a requirement of the development approval process, regulatory requirements of the Environmental Protection Authority (EPA) or a due diligence assessment. Investigation of contaminated land is undertaken in accordance with a national risk-based framework known as National Environmental Protection (Assessment of Site Contamination) Measure 1999 (ASC NEMP). Individual states have legislation and guidelines providing additional information on assessments and remediation.

Types of contaminated land

Any substance in the soil that exceeds naturally occurring levels and poses a health risk is a soil contaminant. Site of special concern include:

Service stations and fuel depots

Petrochemical contamination around service stations is common on old service stations. The contamination can often be unnoticed until significant leakage has occurred resulting in extensive and costly clean up requirements.

Industrial and manufacturing sites

Industrial and manufacturing sites often have a range of contaminants polluting their soils. The types of contamination will depend on the process undertaken. Contamination can occur when chemicals leak out onto the soil from buildings. In other instances, the factory may have a waste stockpile or holding area that was once considered safe, but now known to be a pollution problem.

Landfills and disposal sites

Landfill and disposal sites have a high risk of soil contamination. They often contain a large mix of contamination types like heavy metals, petrochemical and asbestos. Landfills can contain hazardous gasses and methane production can occur for over 50 years depending on the buried substances. Containment and remediation can be costly, technical, complex and logistically challenging.

Highway corridors, roads and parking areas

Lead is a common contaminant along highway corridors, roads and parking areas as it was used in petrol until 1989. Petroleum oil leaks on roads can accumulate in nearby soils. Tar used in the manufacture of bitumen and asphalt can also result in accumulation of petrochemical in the soil.

Households

Lead is a common contaminant in urban area as it was used in paint until 1989. Old paint residue from renovations is a common soil contaminant. Asbestos can be present from damage, building waste or introduced fill. Residual pesticides were commonly used as termiticides under buildings until 1995. Other potential contaminants include petroleum products, overuse of pesticides and fertilisers.

Farmland

Many pesticides used in farmland until 1990 are persistent and can accumulate in the soil. High risk farmland includes horticultural enterprises, stockyards and dips, orchards and pesticide storage areas. Fertilisers and biosolids can contain heavy metals that can accumulate over time.

Acid sulphate

Excavation of soil around coastal and wet area can result in the production of acid sulphate soil. Identification is undertaken through risk mapping and soil testing.

Naturally occurring asbestos

Geological risk mapping identifies areas with a risk of the occurrence of naturally occurring asbestos. Naturally occurring asbestos generally impacts known areas and has significant implications for development activities.

Fill

Many hazardous chemicals can be included in fill which are dependent on the source.

Neighbouring site

Land impacted by contaminants can often be a result of migration from neighbouring land. Migration can occur by sediment movement, groundwater or dust. For example, a hydrocarbon groundwater plume from a service station can migrate long distances dependant on the topography and soil conditions. Common impacts from service stations can occur through groundwater contamination and vapour intrusion into basements.

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Contamination conditions

The principal reason for investigating the contamination conditions on a site is to provide the architect and relevant specialist consultants with the following information:

• The nature of the contamination and other relevant facts concerning its potential effect on the occupants or users.
• Advice that can be used to prepare construction documents that mitigate claims by contractors for additional costs associated with the demolition, construction or future use of the building and the site on which it is built.

Contaminants include but are not necessarily limited to:

• asbestos or asbestos-containing materials (ACMs)
• petrochemical contaminants (fuels, oils, gas, etc)
• agricultural pesticides
• the presence of fill that may contain contaminants
• firefighting foams
• the presence of natural occurring contaminants (asbestos, acid sulphate, metals or others)
• any other hazardous material that poses a hazard to persons, such as flammable or explosive liquid or gas, toxic, infective or contaminated material, radioactive material, noxious or explosive chemical, hazardous substances including PCB, or anything that may have contained or been contaminated by any of them.

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Stages of investigation and remediation

Site characterisation and remediation is undertaken in a staged process:

• Preliminary or Stage 1 investigation – identify potential for a site to be contaminated from a site history review and limited sampling.
• Detailed investigation – sampling is undertaken to delineate potential or actual contamination in accordance with a Sampling Analysis Quality Plan.
• Remediation action plan – describes contamination and proposes a method to reduce risks to enable a proposed land-use.
• Validation – describes the remediation undertaken and testing to confirm suitability for the proposed land-use.
• Site management plan.

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Planning legislation

Through the planning legislation of the various states and territories, the land use planning process is used when there is a change of land use or when a subdivision application is made, to determine the public and environmental exposure to contaminated land. The planning acts provide a process to appropriately investigate the land (through a contaminated site investigation) using the process stipulated in the relevant environmental protection legislation.

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Environmental protection legislation

Significantly contaminated land is usually managed by the EPA under the environmental protection legislation in the jurisdiction concerned. The emphasis of the legislation is on the management of the environment within the principles of ecologically sustainable development. Contaminated land is managed through statutory processes leading to the minimisation of health and environmental risks through the environmental management of potentially contaminating activities.

Each state and territory have enacted environmental protection legislation which includes reporting requirements in relation to activities that are considered likely to cause contamination. The legislation also includes requirements relating to activities on sites that are known to be contaminated and actions that must be taken where contamination is discovered.

The public-access registers that contain land use planning information are the:

• Public databases of historical land-use
• Contaminated Land Register
• Register of environmental protection licences

Information on how to notify or search the registers can be downloaded from the EPA website in the relevant state or territory.

Under the relevant legislation, the EPA assesses site reports, approves management plans and provides advice to local government, business and the community on legislative and technical requirements for contaminated land matters.

Public databases of historical land uses

Public databases of historical and uses contain registers of potential contaminating activities. Victoria’s, South Australia’s and Queensland’s EPAs have registers on potentially contaminated land based on past land use. Other states have compiles by local councils.

The state based registers are:

• EPA Queensland – Environmental Management Register
• EPA Victoria – Historical Business Listing
• EPA South Australia – Site contamination index

The databases of historical land uses are planning and management registers for land that has been or is being used for a notifiable activity. The databases provide information on historical and current land use, including notifiable activities and hazardous contaminants. In most circumstances, sites in the databases pose low risk to human health or the environment in their current use. It does not necessarily mean that the land must be cleaned up or that the current land use must stop.

In some cases (for example, land used for industrial purposes or parkland), it is not necessary or practicable to remove the entire contaminated area. The land can be partly remediated, and the relevant EPA can approve a site management plan, which states the conditions under which the site can be used while preventing the contamination from causing environmental harm or posing a risk to human health.

Contaminated Land Register

The Contaminated Land Register (or equivalent) is a public register of proven contaminated land (risk sites) that is causing or may cause serious environmental harm. Land is recorded in the Contaminated Land Register when a scientific investigation shows that the land is contaminated, and that action needs to be taken to remediate or manage the land (for example, technical measures to prevent migration or full removal and off-site treatment) to prevent serious environmental harm or adverse public health risks.

Under the relevant planning legislation, when a development application is made for a change of use or a subdivision of land recorded on the Environmental Management Register or Contaminated Land Register, a site investigation – and where necessary – remediation is required.

The contamination status of the land includes declarations, remediation, and management orders.

Environmental protection licences

The production of wastes by factories and businesses is licenced and State EPAs compile public registers of environmental protection licences. The licences can assist is determining potential contamination activities that have been undertaken on lands. Prior to 1999 the licences were issued as Pollution Control Licences.

Certificate of title

Property title deeds list known contamination and restrictions on use. Certificates of tile can reference the contamination status and include Environmental Management plans that may restrict activities that can be undertaken on the land.

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Responsibilities

Local governments have obligations under the relevant environmental protection legislation relating to the identification, notification and management of contaminated land. Under the relevant environmental protection legislation, local government authorities are required to notify the relevant EPA of land that has been or is currently used for a 'notifiable activity' within their local government area. This information is gathered by local governments through sources such as historical information, local knowledge and town planning records.

Architect responsibilities

While architects may be familiar with the nature of a location, they should recommend that their clients establish, as far as possible, the conditions on a site including the existence or not of contamination at the pre-design stage. Contamination on a site can impact on the costs of demolition, excavation, design and construction and in some cases, may be the dominant influence.

Where an environmental investigation has not been carried out, the architect should still thoroughly examine the conditions and, if appropriate, make provision in the construction documents for an environmental investigation when the contract commences, and suitable equipment is available on site. The architect should, as part of the design process, recommend to the client that the nature of the contamination conditions on the site are properly investigated so that the site will be safe when the demolition or construction work is complete. It may be necessary to consider contamination on surrounding land in case this affects the contamination of the client's site.

In most cases, it will be necessary to engage a specialist environmental consultant to provide a report on the contamination conditions. If the engagement of this consultant is not covered in the Client and Architect Agreement, this matter should be discussed and agreed with the client prior to the engagement of the environmental consultant. See Acumen note Client Architect Agreement (CAA2019).

To assist the specialist environmental consultant in the performance of the investigations, the following information should be provided by the client or the architect on behalf of the client:

• Accurate information defining the site
• A datum to which the depth of holes can be related
• The location on site and nature of the proposed works on the site
• Volumes soil, building materials or pavement to be removed
• Source and amount of imported fill

Examples of the information which should be provided by an environmental consultant include:

• evidence of any previous use of the site
• extent of any filling on the site
• evidence of any potential soil contamination by hazardous substances such as heavy metals, asbestos, pesticides, petrochemicals or others
• documented evidence of the contamination status of the land
• recommendations on methods of excavation
• remediation measures proposed in a documented in a Remedial Action Plan
• reports prepared by a suitably qualified person, if contamination has been removed.

The environmental consultant will recommend the extent of site investigations necessary to provide an adequate report sufficient for the architect to design the proposed building and new land-use.

Client responsibilities

Landowners are required under the relevant environmental protection legislation to inform the relevant EPA of any known notifiable activity on their property that is significant and may impact adjoining people or the environment. The owner is also required to inform any occupier, such as persons who are renting, managing or leasing the land, if the property is listed in the Contaminated Land Register or historical databases, public databases and subject to the conditions of any site management plan.

Anyone selling or otherwise disposing of land that is listed on either of the registers is required to give written notice of the land’s listing to any potential purchaser before agreeing to dispose of the land.

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Remediation

Remediation of land will be required if the proposed land use is impacted by existing contamination. Site assessment will assess the practical, economic, environmental and social factors to determine the optimum solution. The remediation hierarchy for remediation activities adopted by the EPA is:

• On-site treatment so the contaminant is either destroyed or the associated hazard is reduced to an acceptable risk.
• Off-site treatment, the contaminant is either destroyed or the associated hazard is reduced to an acceptable risk after which the water/soil is returned to the site.
• Consolidation and isolation of the soil and groundwater on-site by containment with a barrier.
• Removal of the groundwater and contaminant to an approved site.

Remediation of contaminated material on site is usually the preferred option to the removal of contaminated material and disposal off site. The method of treatment and remediation depends on the type of contamination encountered. Recommendations and proposals will normally be available or should be provided by a specialised environmental consultant.

Specialist advice should be sought regarding the remediation of contaminated material and those recommendations should be strictly followed. There are no short cuts and ultimately it is likely that the relevant EPA will be required to sign off on the satisfactory remediation of any contaminated material.

Capping or encapsulation of some contaminants may be the selected method for remediation. Retaining contamination on site is an intergeneration cost as restrictions on the land-use will need to be implemented.

Under the relevant environmental protection legislation, polluters of a site are usually primarily responsible for any contaminated soils that are generated on a property because of their activities. The EPA generally supports the national target of a 50% reduction in waste going to landfill and promote on-site remediation as the preferred option for dealing with contaminated soils where appropriate.

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Removing contaminated soil

Disposal to landfill should be used only when no other method of dealing with the contaminated soil is available and the operator of the landfill agrees to the disposal. If disposal is the only viable option, all possible efforts should be made to reduce the volume of soil requiring disposal. Very highly contaminated or leachable soils should be separated from less contaminated soils. Separation will reduce volumes requiring specific treatment and will significantly reduce the disposal and treatment costs associated with highly contaminated soil.

An in-situ investigation based on laboratory sampling, may be required to delineate the extent of contamination and determine the volume and level of contamination before commencement of any excavation. This will ensure that mixing of contaminated soils with uncontaminated soils does not occur. Reducing contaminant concentrations by dilution is not an acceptable remediation strategy.

Dangerous goods transport

Many contaminants in soil are classified as dangerous goods or hazardous wastes. Permits are required for the transport of dangerous goods and the transport needs to be undertaken by operators who are licensed.

Waste

All excavated soil and building materials transported from land is considered waste unless it has been demonstrated to not be contaminated. Some testing is usually required to demonstrate the soil is not contaminated unless from a quarry site.

Testing and classification will determine the location where soil can be disposed. Formal approval from the EPA for the disposal of soil is required in some states. Landfill operators may need to review the contamination status prior to accepting to determine if they are licenced to accept.

When deciding whether to grant or refuse an application for a disposal permit, the EPA considers the standard criteria defined in the relevant environmental protection legislation, including:

• the principles of ecologically sustainable development as set out in the National Strategy for Ecologically Sustainable Development
• best practice environmental management.

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Applying for a disposal permit or landfill approval to accept waste

In states where disposal permits are not required, less background information is needed. The waste generator is responsible for appropriate classification and testing must be undertaken.

In states where permits are required, applications for a disposal permit must be lodged on the appropriate form available from the relevant EPA, and accompanied by documents such as the following:

• A written agreement from the owner of the disposal site to accept the contaminated soil, stating any conditions to be placed on the soil disposal.
• Information which demonstrates the contaminated soil may be accepted under licence conditions issued under the relevant environmental-protection legislation.
• A copy of the Certificate of Title of the site from which soil is to be removed.
• A copy of the Certificate of Title of the site receiving the contaminated soil (if the soil is not going to a local government-administered landfill).
• Copies of all laboratory reports for contaminated soil analyses (one laboratory sample/50m³ soil is considered a minimum for stockpile sampling) and leachate testing results.
• A plan showing the location of sampling sites in relation to the contamination source.
• Completed notification of land form (if the site from which the soil is being removed is not listed on the Environmental Management Register or Contaminated Land Register).

In situations where a site investigation report has already been lodged with the relevant EPA, duplication of information provided in that report is not normally required. When completing the relevant disposal permit form, the applicant can refer to relevant pages of the report.

Applicants should allow sufficient time for the application for a disposal permit to be considered and the permit issued before extracting the material.

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Likely causes of contamination

Activities that have been identified as likely to cause land contamination are listed in the table below. Note, this list is advisory in nature and is not exhaustive:

¹ Strategies or programs may apply for regional historical goldmining activities.

Source: Land uses with potential to contaminant land (DELWP 2021)

References

DELWP (Department of Environment, Land Water and Planning) (2021) Planning Practice Note 30: Potentially Contaminated Land [PDF], Table 2: Land uses with potential to contaminate land, DELWP.