A Check Your Groundwater (CYG) area is an area or precinct where we know groundwater has been contaminated by:
- an activity
- waste
- pollution
- contaminated land.
If you're in management or control of land in a CYG area, the contaminated land duties apply to you.
A CYG area has one of 3 statuses. Each status has the same requirements and responsibilities for managing the groundwater.
To comply with the duties, you're responsible for minimising the risk of harm from the contaminated groundwater. This may include:
- clean-up and management of the contaminated groundwater
- telling anyone who's living on the land and providing regular updates to them
- telling potential buyers about the CYG if you're selling a property in a CYG area.
We contact you when we're assessing a potential CYG area.
To learn more about minimising the risk of harm when managing and cleaning up contaminated groundwater, refer to Guidance for the clean-up and management of contaminated groundwater.
Activities that impact groundwater behaviour
If you live in or near a CYG area, some activities may impact the behaviour of the surrounding groundwater. For example, excavations that intersect with or extend below the groundwater level. Consider if your activities:
- include extracting groundwater (dewatering)
- could affect groundwater levels or flow directions
- mean you could come into contact with shallow groundwater that may be contaminated
- could draw groundwater contamination from a neighbouring site
- pose a vapour risk if the contaminants are volatile (this is only a risk if you are extracting groundwater)
- could expose potential acid-generating geological materials
- could cause ground movement or geotechnical issues.
Any activity that moves groundwater contamination could breach the general environmental duty.
If you’re using or intercepting groundwater near a CYG area, be aware that contamination may extend to your site.
If you encounter unexpected contamination in groundwater, report it to us.
Developing your land
If you’re planning a new land use or development in a CYG area, consider how it could impact or be impacted by the contaminated groundwater. For example:
- If you want to install a bore or pump to use the groundwater, you may need to treat the groundwater for the intended use. For example, it may be safe to use for irrigation and stock watering but not for drinking.
- A deep foundation and/or basement may need special measures to manage the safety of construction workers or to prevent harmful vapours from accumulating.
- Groundwater may be corrosive to the structure.
The land may be considered potentially contaminated in the land use planning system. This can trigger specific requirements.
Dealing with corrosive groundwater
Contaminants in groundwater can be corrosive. This can affect buildings and structures – for example:
- concrete and steel structures
- drainage systems
- basement waterproofing membranes.
If corrosive groundwater has been identified in your CYG area, get advice from a qualified builder. They can help to:
- advise if you need any extra requirements during construction
- discuss concerns about any existing structures.
Communicating with stakeholders about a CYG area
If you manage or control land in a CYG area or proposed CYG area that extends off site, you must keep all stakeholders informed. This allows them to get more information and provide feedback.
Stakeholders for a CYG area that extends off site include:
- site owners and occupiers of any private properties
- owners corporations of multi-dwelling properties
- owners or occupiers of other land – for example, your local council or VicRoads
- utility owners with deeper assets that could interact with shallow groundwater (less than 3 metres below the surface).
For other scenarios, assess the likelihood for the utility owner to access groundwater, and contact them on a case-by-case basis.
It's important for utility owners to understand how contaminated groundwater can affect their assets. For example, they should consider:
- whether corrosive groundwater could damage their assets, such as concrete stormwater pipes
- the risks to maintenance works, such as vapour or contact with groundwater.
You should:
- confirm with us when you have sent the communication
- allow 2 weeks for stakeholders to provide any feedback to you
- provide any feedback to us for consideration.
Suggestions for communication
Below are some suggestions for communicating with stakeholders about a proposed CYG area that extends off site.
1. When you become aware that contaminated groundwater extends off your site
Purpose
- advise neighbours of contaminated groundwater on their property
- help them reduce the risk of harm to human health and the environment
- inform them of their duty to manage contaminated land.
Advice
- Inform that groundwater may pose a health risk if extracted.
- If the groundwater is shallow, inform that it may pose a health risk if people come into direct contact with it.
- If the contaminants are volatile, detail any potential vapour risks or considerations.
- Refer to our guidance for the duty to manage contaminated land.
- Provide details of any investigations to date and results.
- Provide details of any other contamination at the site.
- Provide maps or figures showing the extent of contamination and groundwater flow direction.
- Inform of next steps and any proposed future clean-up and management.
- Provide your (or your representative's) contact details for any questions or more information.
2. When we're assessing a CYG area at your source site
Purpose
- advise that we're assessing a potential CYG area that includes their property or asset
- provide information on what a CYG area is.
Advice
- Explain that a CYG area does not mean town water supply or rainwater is affected.
- Refer to our guidance about CYG areas, groundwater and the duty to manage contaminated land.
- Refer to any communications with the stakeholder about the contamination.
- Provide information on the current state of the contamination, including potential risks.
- Provide a figure showing the extent of the proposed CYG area.
- Inform of next steps and any proposed future clean-up and management.
- Provide contact details for:
- you (or your representative)
- EPA officer.
3. When we've identified a CYG area at your source site that extends off site
Purpose
Advise that we have identified a CYG area that includes their property.
Advice
- Explain the site owner must tell prospective purchasers about the CYG area as part of their duty to manage contaminated land.
- Refer to our guidance about CYG areas, groundwater and the duty to manage contaminated land.
- Provide a copy of the CYG area map.
- Provide your (or your representative's) contact details for any questions or more information.
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