Abandoned underground tanks

Work health and safety duties apply to abandoned tanks whether they are at a workplace, or locations other than a workplace such as on private land or under a council footpath or road. Under section 367 of the Work Health and Safety Regulation 2011, the person responsible for an abandoned tank must notify WHSQ as soon as practicable after a tank is abandoned (or a tank is discovered). This is done using the online eForm: Notification of an abandoned tank (s367).

At locations other than a workplace where dangerous goods are stored or handled, the occupier of the premises (e.g. property owner, mortgagee in possession, lessee) will be responsible for the abandonment. In some instances, more than one person may have duties in respect to an abandoned tank.

Some abandoned underground fuel tanks may be fitted with impressed current cathodic protection systems to manage corrosion of tanks, pipework, and equipment. Cathodic protection systems using an impressed direct electrical current can expose people to electrical risks if improperly installed, operated or maintained, or if disturbed. For example, when removing or decommissioning an underground tank.

The online eForm: Notification of an abandoned tank (s 367) allows details of an impressed current cathodic protection system to be included in a PCBU notification to WHSQ.

All cathodic protection systems capable of delivering an electrical current greater than 0.25A must be registered with the Electrical Safety Office. Read more information on cathodic protection systems, including system registration.

WHSQ must be notified as soon as practical after a tank is abandoned (or discovered) using the online eForm: Notification of an abandoned tank (s 367). This involves a two-step process:

1. Complete an online abandoned tank eForm and submit it to WHSQ as soon as practicable after a tank is abandoned or discovered. Do not delay notifying due to incomplete or missing tank technical information or wait to notify until a tank is removed, or decommissioned. Select initial notification in the online eForm, enter site and technical information available at the time, and submit the notification without delay to comply with section 367 of the Work Health and Safety Regulation 2011.
2. Submit a follow up notification after an abandoned tank is made safe (removed, decommissioned etc) using the online abandoned tank eForm. Provide the required site and technical information and supporting documentation from a competent person offering assurance of compliance with section 366 of the Work Health and Safety Regulation 2011.

Uncertainty about the presence or contents of underground fuel tanks can expose workers and the public to serious risks which must be properly managed. Identifying hazards is the starting point, and key to managing risk and ensuring health and safety. Specialist knowledge and skills are also needed to identify abandoned tanks, confirm their contents, and make them safe.

It can be challenging to identify abandoned tanks due to a lack of visible physical evidence (e.g. no fuel dispensers, vent pipes, fill or dip points) or the absence of documentation to confirm tank position, size, construction or contents. Never treat absent or inconclusive visual or documentary evidence about abandoned tanks as evidence that none are present, or that tanks have been made safe, and never accept unsupported assurances about abandoned tanks.

Even experienced businesses that have conducted thorough document searches and site inspections using advanced techniques have unexpectedly encountered abandoned tanks, highlighting the need for caution and to continually monitor and review systems of work to address any gaps or limitations. Established methods are available to assist in locating and verifying underground tanks as described in AS5488.2 (2022) Classification of Subsurface Utility Information.

Councils can provide useful information about previous owners, businesses that have operated on the land and the location and nature of approved infrastructure like underground fuel tanks and pipework. The manifest of hazardous chemicals for a current or former workplace can also be useful for identifying the location and contents of underground tanks.

WHSQ maintains an extensive database of manifests of hazardous chemicals for sites across Queensland that is accessible subject to appropriate privacy protections under right to information laws. In addition, land registers operating under Queensland environmental laws can be searched to identify potential locations of abandoned tanks.

Note. Council records, manifests, inspection records, or other documents, should be treated as informative, or a starting point, rather than conclusive evidence as over time they may become inaccurate or be superseded.

To properly identify hazards and manage risk, the best approach is to engage a competent person with suitable skills and knowledge to conduct document searches and a thorough site inspection using recognised inspection and testing techniques. Under work health and safety laws, a competent person is a person who has acquired the knowledge, and skills to carry out the task through training, qualification or experience.

Site inspections may include identifying and inspecting tank dip or fill points and vent pipes, using ground penetrating radar to locate tanks and pipework, sonic techniques to examine tank contents, or other devices to locate underground services. The scope and limitations of site inspections and measurement and testing techniques under various conditions should be made clear as well as their effect on inspection findings and conclusions. Inspection findings and conclusions should be made in writing and can help a PCBU make informed compliance decisions that protect people and property from harm.

PCBUs engaging consultants must be satisfied that the provider has the necessary qualifications and experience to undertake the task. WHSQ offers guidance on engaging hazardous chemical industry consultants as competent persons, including those offering professional engineering services. To assist industry, the guidance includes an alphabetical listing of consultants as well as a listing of consultants grouped by areas of speciality, including inspection, testing, removal and decommissioning of abandoned tanks.

Letters, certificates, inspection reports and other documents from competent persons offer key information and advice PCBUs need to make important decisions about work health and safety. They also offer assurance of PCBU compliance with relevant standards and work health and safety laws. PCBUs need to be satisfied abandoned tank documentation from a competent person is fit for purpose from their perspective as a person with health and safety duties and obligations and WHSQ as the regulator.

Assurance documents that are submitted with an abandoned tank notification and exhibit inconsistencies, errors, or omissions may not be fit for purpose and result in follow up enquiries by WHSQ and potential compliance and enforcement action. To help ensure assurance documents are fit for purpose, PCBUs and competent persons should confirm assurance documents include the following:

• name, ABN, address, contact details of the competent person
• location of the tank/s (e.g. address and GPS coordinates)
• tank or tank compartment ID (as per the most recent site manifest)
• tank construction, compartments, former/current contents, capacity
• method used to remove the tank, or make the tank/compartment safe including the relevant compliance standard
• tank or compartment contents post decommissioning in-situ. For example, liquid tanks—dry sand, gravel, slurry mixture or, gas tanks—gas free, gas purged or compressed gas (e.g. carbon dioxide, nitrogen).

Note. Abandoned tank assurance documents should be clear, concise, and specific to avoid confusion or ambiguity. They must detail what was done, how it was done, and why. Best practice examples include photo sequences, before and after images, readings, test results, analysis as well as assumptions or limitations and how they affect findings, conclusions, and advice. This allows PCBUs to make well informed compliance decisions that protect people, property and withstand scrutiny. Best practice assurance documents also offer clarity and certainty for current or prospective business stakeholders.

Section 366 of the Work Health and Safety Regulation 2011 specifies that when a PCBU intends that an underground hazardous chemical storage and handling system will no longer be used, or is to be disposed of, the PCBU must ensure, so far as is reasonably practicable, that the system is removed. If it is not reasonably practicable to remove the system, the PCBU must ensure, so far as is reasonably practicable, that the system is without risks to health and safety. Section 366 of the Work Health and Safety Regulation 2011 also applies to abandoned tanks.

Section 366 prescribes a hierarchy of risk control. Tank removal is the first and most effective risk control given it eliminates hazards and associated risks. To comply, PCBUs must consider risk controls in the order they are stated. PCBUs must not select tank decommissioning in-situ instead of removal merely based on reduced cost, less site disruption or convenience and service providers should not promote or encourage this.

PBCU decisions to adopt risk controls other than tank removal must be supported by objective, credible evidence. Unsupported claims or decisions by PCBUs or service providers do not assure compliance and may jeopardise work and public health and safety. In addition, under section 268 of the Work Health and Safety Act 2011 it is an offence for a person to provide false or misleading information.

PCBUs responsible for abandoned tanks should be mindful that steps to comply with section 366 of the Work Health and Safety Regulation 2011 must be undertaken in a timely fashion and safety must be maintained while risks are present (if necessary, through the implementation of interim risk controls).

PCBUs should not delay or defer steps to eliminate or minimise risks due to operational or administrative convenience or factors such as the pending sale or redevelopment of premises. Before removing an abandoned tank, PCBUs should carefully consider their duties relating to demolition and construction work.

Before an above ground or underground storage tank and/or associated pipework are removed or demolished, previous use should be determined, and appropriate action taken to identify and remove hazardous chemicals. Delivery lines and vent pipes should be purged. The tank should be emptied and certified by a competent person as being free of gas, flammable vapours or other hazardous chemicals.

A demolition licence is required for the demolition or dismantling of structures including underground tanks and pipes that involves load shifting equipment such as a combination front-end loader and backhoe, skid steer loader, excavator, or crane. Demolition work is also a type of ‘construction work’. Therefore, when carrying out demolition work, the requirements relating to construction work must be complied with.

A Safe Work Method Statement (SWMS) is required for ‘high risk construction work’ activities. The primary purpose of a SWMS is to help PCBUs, supervisors and workers implement and monitor the control measures established at the workplace to ensure high risk construction work is carried out safely.

During the demolition of tanks and pipework, the following precautions should be taken:

• make sure no flammable or toxic substance or combustible liquid is allowed to enter a drainage system or watercourse
• if excavating underground tanks and/or pipework, check the soil surrounding the tank/pipework to establish it is not contaminated either by leakage or spillage,
• hot work, for example welding/oxyacetylene cutting, should not be carried out where there is a chance flammable material may be present as a result of leakage or spillage or after cleaning out the tank/pipework.

The following steps outline how a PCBU can demonstrate compliance with section 366 of the Work Health and Safety Regulation 2011.

If the abandoned tank was removed, you must provide:

• a copy of a letter or certificate from a competent person confirming the method of removal was in accordance with AS4976 for flammable or combustible liquids, or other relevant standard. For example, AS1596 for LP gas with confirmation of the tank's gas-free status, or
• a statement from a competent person confirming the method of removal offered an equivalent or higher standard of work health and safety to the relevant standard
• a statement from a competent person (e.g. engineer) stating that the affected area is suitably stable post removal.

Proximity to structures or infrastructure. It may not be reasonably practicable to remove an underground tank due to its close proximity to surrounding structures or underground infrastructure (e.g. building foundations or other in-service underground tanks or pipework). A PCBU decision to not remove an abandoned tank due to proximity to structures or infrastructure should be supported by written evidence from a competent person such as a structural and/or geotechnical engineer. In such cases, the tank may need to be decommissioned 'in-situ' meaning the tank is left in its existing position and made safe by a competent person.

For underground fuel tanks decommissioning means, it is permanently out of

service, eliminating or minimising the likelihood of dangerous occurrences (e.g. is filled with an inert solid material). For flammable gas tanks, it may mean degassing the tank and/or filling the tank with an inert gas.

If removal of the abandoned tank was not reasonably practicable, you must provide:

• an explanation of why it was not reasonably practicable to remove the tank
• a copy of the letter or certificate from a competent person confirming the method of decommissioning in-situ was in accordance with AS4976 for flammable or combustible liquids, or other relevant standard. For example, AS1596 for LP gas with confirmation of the tank's gas-free status, or
• a statement from a competent person confirming the method of decommissioning offered an equivalent or higher standard of work health and safety to the relevant standard
• an amended site sketch/plan that identifies the position of the abandoned tank. Suitable dimensions must be included to clearly identify the position and footprint of the abandoned tank relative to a permanent reference point on the site.

If decommissioning in-situ was/is not reasonably practicable to ensure the tank is without risks to health and safety, you must provide:

• an explanation of why it was/is not reasonably practicable to decommission the tank
• a statement from a competent person confirming how, so far as is reasonably practicable, risks to health and safety have been (or will be) eliminated or minimised in accordance with Part 3.1 of the WHS Regulation and the applicable codes of practice including:
  • How to manage work health and safety risks Code of Practice 2021 (PDF, 0.65 MB)
  • Managing risks of hazardous chemicals in the workplace Code of Practice 2021 (PDF, 1.21 MB).

Where a tank risk management approach is applied, and the capacity of one or more tanks exceeds a relevant manifest quantity, the site is treated as a manifest quantity workplace (MQW) and the PCBU for the tank/s needs to comply with MQW-related duties. For example, manifest and emergency plan notification, Hazmat box and risk management duties would apply. Where applicable, the PCBU must ensure amendments to relevant documents such as the manifest and site plan. Sites not considered an MQW would need to develop an emergency plan as required under section 43 of the Work Health and Safety Regulation 2011 and be subject to relevant hazardous chemical requirements under Part 7.1.

If the underground tank is intended to be used again (within two years), an option may be to fill the tank with water and a corrosion inhibitor and conduct appropriate maintenance to maintain the system's integrity. Testing the tank's integrity is recommended before returning the tank to service.

If there is a change of duty holders, the outgoing PCBU should support ongoing work and public health and safety by providing the subsequent PCBU with information and documentation about abandoned tanks and underground hazardous chemical storage and handling systems.