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EPA developed the Classification for drilling mud (PDF 74KB; the classification) to provide clarity for industry and reduce the regulatory burden associated with the management of drilling mud where there is low risk to human health and the environment.

As a liquid waste, drilling mud is a category A prescribed industrial waste (PIW) under the Environment Protection (Industrial Waste Resource) Regulations 2009 (IWR Regulations), requiring strict management conditions. Based on risks to human health and the environment, the classification recognises drilling mud as a non-PIW, provided appropriate measures are in place to prevent pollution to the environment.

The classification sets the minimum conditions EPA expects of industry.

Implementation of the classification

Table 1 summarises the sites and activities where the classification does and does not apply.

Table 1: Where does the classification apply?

For sites For these activities
Classification applies
  • when documented assessment shows no risk of soil contamination (testing may not necessarily be required)
  • contamination with industrial waste only (bricks, concrete, etc.)
  • when testing confirms soil is not PIW (needed for potential contamination)
  • Directional drilling through non-contaminated soils
    (unless specified below)
Classification doesn’t apply
  • when there is no documented assessment
  • when documented assessment indicates potential soil contamination and no further testing is done
  • when testing shows PIW contamination of the soils
  • drilling for mineral, gas or coal exploration
  • drilling through contaminated soils
  • drilling with the use of synthetic additivesdrilling in marine environment

When the classification applies, you must comply with general environmental requirements under the Act and all management options in the classification.

When the classification does not apply, you must comply with all relevant requirements under the Environment Protection Act 1970 (the Act), the IWR Regulations and the Environment Protection (Scheduled Premises) Regulations 2017. This includes licensing and waste transport certificates.

Compliance and enforcement

If you do not meet the requirements of the classification, the waste will be considered as PIW and EPA take compliance and enforcement action for managing PIW without necessary approvals. You must be able to demonstrate compliance to EPA through relevant records, systems and procedures.

When using this classification you must continue to comply with any licence conditions (where applicable). If there is conflict with these requirements you should comply with your licence.

You will also need to comply with general environmental requirements that apply to all industries under the Act and state environment protection policies (SEPPs). In particular, odour, noise and dust must not negatively impact the area surrounding your site.

Management options under the classification

The gazetted classification should always be your primary reference. EPA has provided some guidance to help you comply with management options. The management options are compulsory for anyone using the classification.

A copy of the classification (PDF 74KB) must be in any vehicle or site that accepts drilling mud.

Producers, transporters and receivers of drilling mud each have a responsibility to ensure that drilling mud management and documentation meets the classification. For example:

  • drilling mud producers are responsible for the documented assessment of the drilling site. If a documented assessment is not provided, transporters and receiving premises have a responsibility to refuse the waste or manage the drilling mud as category A PIW in accordance the requirements of the IWR Regulations.
  • while transporters and receiving premises are responsible for their own vehicles and sites, producers have a responsibility to ensure that drilling mud is received by an appropriate site and is transported in a suitable vehicle. This includes refusing services from unsuitable vehicles and sites.

Read more about the drilling mud classification further below.

Response to comments on the draft classification

The new publication is a revised version of the draft classification (publication 1580), which was released for public comment between 19 January 2015 and 27 February 2015. Twenty one submissions were received and these were considered in finalising the classification.

Table 2 sets out the key themes from public submissions received and EPA’s responses to them.

Table 2: Response to comments

Summary of comments EPA response
More detail on acceptable practices for dewatering naturally or by air drying.
The classification provides general requirements that industry has responsibility to comply with. Supporting information and references are provided above.
Expand management to ensure better protection of the environment.
Management options were updated. Please note some of the issues raised did not require specific management options as they are enforceable using existing provisions under the Environment Protection Act 1970.
Clarification required on the assessment of the drilling mud source.
The clause was simplified and supporting information on the assessment is provided on this page.
Comments questioned the exclusion of drilling muds from acid sulfate soil.
Acid sulfate soils are now included, provided their management satisfies clause 5.1.2 of the classification and the Industrial Waste Management Policy (Acid Sulfate Soils).
Comments questioned the exclusion of drilling muds from mineral, gas or coal exploration.
Drilling muds produced during mineral, gas or coal exploration are considered high risk and are excluded from the classification.
Requested broadening scope to include drilling muds containing incidental contamination, specifically septic wastewater.
Use of water and natural additives is included in the classification. Contamination with other substances, including sewage and synthetic drilling additives, would mean the liquid waste remains a Category A PIW.
Changes requested to the requirement for consolidation site. Both longer and shorter time frames were suggested.
This requirement remains at 30 days. This time limit does not apply to the site of drilling mud production or the dewatering facility or site.

 This page was copied from EPA's old website. It was last updated on 4 July 2017.

Drilling mud classification in more detail

  • Documented assessment (Clause 5.1)

    The documented assessment needs to be a clear record of research and observation for the site where the drilling mud will be produced.

    Producers must provide a copy of the documented assessment to the waste receiver.

    All Producers and waste receivers must keep a copy of the documented assessment for two years.

    At a minimum it will include the following:

    • Investigation of past and current use of the site – was the site previously an industrial facility, drycleaner, service station etc? What materials were handled there?
    • Investigation of past and current use of surrounding sites – as above
    • Observations indicating contamination – for example, hydrocarbon or chemical odours, oil sheen on surface waters or soil discolouration.

    A useful reference to assess the risk from site use is the Planning practice note: Potentially contaminated land.

    Sites with potential acid sulfate soils must be managed as per the Industrial Waste Management Policy (Waste Acid Sulfate Soil) (publication S125)

    The documented assessment does not need to be completed by an environmental auditor or consultant. However, where potential soil contamination is identified you may need to engage an environmental auditor or consultant for further investigation or to help manage your site.

    If the documented assessment indicates potential site contamination, test results must be attached to confirm there is no contamination in accordance with Soil hazard categorisation and management (publication IWRG 621).

  • Appropriate transport (Clauses 5.4 and 5.5)

    Transport must be safe, secure and leak-free. To meet this requirement please refer to Vehicle guidance: Tanker/tanker trailer (publication IWRG816).

    In addition, tankers should be clean and not contain PIW residues. Waste transporters should develop and use up-to-date procedures to ensure drilling mud is not contaminated with tanker PIW residues.

  • Records (Clause 5.6)

    Records must include:

    • name and address of waste producer
    • location from which waste was received
    • transport date, quantity and vehicle registration
    • date and quantity received.

    Records must be kept for a minimum of two years.

    Receivers of drilling mud should obtain this information from the producer and/or transporter.

  • Dewatering options (Clauses 5.8 and 5.9)

    Natural dewatering or air drying is only acceptable when you are confident that drilling mud comes from an uncontaminated site and is free from industrial contamination such as bricks and concrete.

    Regardless of the type of dewatering option the site must meet all requirements under the Act, and any relevant state environment protection policies (SEPPs) including, for example, SEPPs for water, groundwater and land.

    Natural or airdrying site

    Use only for drilling mud that meets the classification and when the documented assessment indicates no industrial waste or PIW contamination.

    Dewatering facilities

    Use is appropriate for managing drilling mud contaminated with industrial waste (bricks, concrete etc). However, the drilling mud must meet the classification requirements above, including having a documented low risk of PIW contamination.

    Natural or airdrying site

    Site must ensure the protection of surface, groundwater and land through appropriate siting and management, such as construction of a barrier or bunding.

    Placement of the drilling mud on site should allow evaporation of liquid and prevent liquid and mud from leaving the site or entering waterways, stormwater systems or groundwater.

    Dewatering facilities

    Site must have bunding per Liquid storage and handling guidelines (publication 1698) and management processes.

    Liquid generated must be directed to a wastewater treatment plant or managed in accordance with Victorian guideline for water recycling (publication 1910.1).

  • Spill management plan (Clause 5.10)

    Printed copies of your site-specific spill management plan must be kept on hand for quick reference during an incident. You must be able to provide the spill management plan to EPA on request.

    In addition, EPA must be immediately notified of any incident or spill that is likely to have an offsite impact.

  • Testing requirements (Clauses 5.1, 5.8 and 5.9)

    The information below summarises when testing is required, how it must be conducted, and what it means. Results must be kept for two years.

    Soil testing at the drilling site

    When testing is required

    Before drilling where:

    • the site has potential contamination
    • the drilling mud will be transported off site for dewatering.

    Testing requirements and management

    Manage as per Soil hazard categorisation and management (publication IWRG621).

    You should  to help investigate contamination of the site.


    Testing must meet fill material criteria; otherwise, the drilling mud is category A PIW and the classification does not apply.

    Drilling mud dryness testing

    When testing is required

    Before drilling mud residues are transported off the dewatering site.

    Testing requirements and management

    Test as per method 9095B Paint filter liquid test (US EPA 2004)


    Drilling mud that does not meet the test requires further dewatering.

    Residual soil testing

    When testing is required

    Before any solid drilling mud residues are transported off the dewatering site.

    Testing requirements and management

    Sample soil as per Soil sampling (publication IWRG702).

    Manage soil as per Soil hazard categorisation and management (publication IWRG621).


    Test results will inform the appropriate disposal and reuse options for the soil.

    Liquids from drilling and mud testing

    When testing is required

    Before determining water reuse options – required for all liquids from drilling mud not sent to a wastewater treatment plant.

    Testing requirements and management

    Manage liquid as per Victorian guideline for water recycling (publication 1910.1).


    Test results will inform the appropriate reuse or disposal options for the liquid.

Reviewed 9 September 2021