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Contaminated Land, Acid Sulphate Soil, Dewatering

Contaminated Land

The land in the Georges River Council area has been used for many different things over the years, including homes, shops, and factories.

Contaminated sites can be found anywhere, but are mostly in areas that used to or still do have industrial activities. Some of these places were used before strict environmental rules were in place.

Land may need to be cleaned up (remediated) in certain cases, such as when:
  • The land is rezoned under a new plan.
  • A Development Application is made.
  • Cleanup is done voluntarily.
  • The Environmental Protection Authority orders it after pollution happens.

Contaminated land can cause problems for the community. It can limit what the land can be used for and make development more expensive.

Cleaning up contaminated land is important to protect people’s health and the environment.
 

Checking if Land is Contaminated

Council checks if land is contaminated and if it is safe for its planned use when considering Development Applications. Council also keeps a list of known contaminated sites in the area.

Under the Environmental Planning and Assessment Act 1979 (EP&A Act), land must not be developed unless contamination is investigated and fixed if needed.

According to the State Environmental Planning Policy (Resilience and Hazards) 2021, Council requires contamination reports with all Development Applications when:

  • The application is for a childcare centre or school, no matter the site’s history.

  • The application is for homes or parks on land that was once used for industry or business.

  • The site is known or suspected to be contaminated.

Below is a simple guide to help decide if land is suitable for its intended use:

  • Step 1 - Preliminary Site Investigation (PSI) Report

    A Preliminary Site Investigation (PSI) report is sent with the Development Application. This report looks at past land use and records to find out if there is any contamination.

    A PSI is also called a Phase I Environmental Site Assessment.

  • Step 2 - Detailed Site Investigation (DSI) Report

    If the Preliminary Site Investigation (PSI) shows more checking is needed, a Detailed Site Investigation (DSI) report must be given to Council before the development is approved.

    A DSI must be done by a Contaminated Land Consultant who is certified by the NSW EPA. The investigation must follow the rules set by State Environmental Planning Policy (Resilience and Hazards) 2021 and its guidelines.

    A DSI is also called a Phase II Environmental Site Assessment.

  • Step 3 - Remedial Action Plan

    A Remedial Action Plan (RAP) is a report that explains how contaminants will be cleaned up or removed from the site. It is usually sent to Council with the Detailed Site Investigation (DSI) report before the development is approved.

    A RAP must be prepared by a Contaminated Land Consultant who is certified by the NSW EPA.

    A RAP is also called a Phase III Environmental Site Assessment.

  • Step 4 - Site Validation Report

    A Site Validation Report shows that the contamination has been cleaned up properly.

    This report must be done by a Contaminated Land Consultant certified by the NSW EPA.

    Depending on the seriousness of the contamination, the report is needed either when the Construction Certificate is issued or before the Occupation Certificate is given.

  • Step 5 - Site Audit Statement

    Council will ask for a Site Audit Statement (SAS) when:

    • They need to check that the information meets the right standards and rules.

    • There is a good reason to think the information given is not correct or incomplete.

    • The contamination is complex and needs an independent review.

    A Site Audit is done by a Site Auditor who is accredited under the Contaminated Land Management Act 1997.

  • Step 6 - Environmental Monitoring Program

    An Environmental Monitoring Program (EMP) is needed when cleaning up a site is not possible, and the contamination must be monitored over time.

    An EMP is prepared by a Contaminated Land Consultant who is certified by the NSW EPA. It explains how the site will be managed and checked.

    The monitoring program usually includes:

    • The plan for how monitoring will be done.

    • What things will be checked.

    • Where monitoring will happen.

    • How often monitoring will occur.

    • How and when reports will be made.

  • More Information

 

Acid Sulphates

Acid sulphate soils are natural sediments found along the NSW coast. They contain iron sulphides.

These soils are safe as long as they stay wet and undisturbed.

But if the soils are drained, dug up, or exposed to air—such as when the water table drops—the iron sulphides react with oxygen and create sulphuric acid.

This acid can harm the environment and damage buildings, roads, and other structures.

The acid also breaks down soil minerals, releasing metals like aluminium and iron. Rain can wash the acid and metals from the soil into nearby waterways and land.

  • Impact of Acid Sulfates

    Environmental Impacts

    The acid and metals released from disturbed acid sulfate soils can cause many problems:

    • Damaging waterways and killing aquatic life — Rain can wash acid and toxic metals into rivers and lakes. This can kill animals that can’t move, like oysters, and those living in the mud. It can also make it harder for plants and animals to grow and survive, and cause diseases like red-spot disease in fish.

    • Killing plants — Very acidic soil can kill all the plants growing in it.

    • Toxic water and dust — Acidic soil and water can irritate your skin and eyes. Drinking acidic water can make animals sick.
       

    Building Impacts

    Acids and metals can also cause damage to buildings and structures. Sulphuric acid can eat away at concrete, iron, steel, and some types of aluminium.

  • Where can Acid Sulfate soils be found?

    The NSW government has made maps to show where acid sulfate soils are likely to be found.

    If you plan to dig or excavate near waterways, you need to think about the chance of coming across acid sulfate soils.

  • How Can We Prevent Damage from Acid Sulphate Soils?

    Minimising disturbance to acid sulfate soils can be simple. Some ways to do this include:

    • Planning the work to reduce how much digging is needed.

    • Moving the work to parts of the property where the acid sulfate soils are deeper underground, so less soil needs to be disturbed.

    Using building methods and site management that keep acid sulfate soils from being exposed to air without treatment.

  • Treatment

    If acid sulfate soil is disturbed, it must be treated to stop damage.

    The most common way to treat it is by mixing alkaline materials into the soil. These materials neutralise the acid. Agricultural lime (powdered calcium carbonate) is the most common neutraliser used.

    While it’s often easy to avoid disturbing these soils, managing them properly is more complex. It should be done by trained professionals.

  • Expert advice

    If you are planning a project near waterfront areas, it is important to hire an environmental consultant before you start. They can help make sure the work follows the right rules and protects the environment.

  • More Information

 

Dewatering

Dewatering is the removal of groundwater that collects on a site during excavation or construction. If not managed properly, dewatering can cause environmental harm, including pollution of waterways and damage to nearby land.

Dewatering activities are regulated under the Water Management Act 2000.

Poorly managed dewatering can pollute waterways and harm the environment. Planning dewatering early and getting the right approvals helps protect local waterways and avoids delays to your project.

Before groundwater is removed from a site, a licence may be required from WaterNSW.  

Dewater activities must comply with the Protection of the Environment Operations Act 1997 and the Protection of the Environment (General) Regulation 2022.  

  • Dewatering Licence

    Some dewatering activities require approval from WaterNSW.

    Whether a licence is needed depends on factors such as:

    • The volume of groundwater being removed.

    • How long dewatering will occur.

    • Where the water will be discharged.

    To find out if your project requires a licence, visit NSW Government: Dewatering - Licensing and Approvals.

  • Complying with the Protection of the Environment Operations Act 1997

    Any water released into the stormwater system, or into waterways such as creeks, rivers, or streams, must be clean. It must not contain pollutants. Heavy fines apply for polluting waterways. 

    Dewatering methods may include using a tanker truck or discharging into Council's stormwater drainage system.

  • Dewatering using Tanker Truck

    Groundwater can be pumped into a tanker truck and taken to a waste facility that is licensed by the EPA.

    Council approval is not required for this method. However, records showing where the water was disposed of must be kept. These records must be provided to Council officers if requested.

  • Discharging into Council Stormwater Drainage System

    Groundwater may be discharged into Council’s stormwater drainage system.

    The discharge must comply with the Protection of the Environment Operations Act 1997 and meet the following conditions:

    • Suspended solids must not exceed 50 mg/L.

    • pH levels must be between 6.5 and 8.5.

    • No visible oil or grease is permitted.

    • The water must not contain substances harmful to aquatic life.

    • Test results for pH and suspended solids from a NATA-accredited laboratory must be provided to Council if requested.



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