23 December 2021 · 4 min read · Site Remediation
Soil contamination is a risk that many home buyers and developers underestimate — until it surfaces mid-project and derails timelines and budgets. If you are planning to build on a previously developed site in the Illawarra, understanding what soil contamination is, where it comes from, and how it is remediated will help you plan your project and protect your future home's occupants.
What Causes Soil Contamination?
Soil contamination is caused, for the most part, by previous land use — industrial, agricultural, or construction activity. In earlier decades, the safe disposal of waste and hazardous materials was not always a priority, and many contaminants were left on site, buried, or disposed of in ways that are now prohibited.
Common contaminants found on residential and light commercial sites in the Illawarra include:
- Asbestos — found in soil near buildings where asbestos-containing materials were used or improperly demolished.
- Heavy metals — lead, arsenic, chromium, and others, often from old painted structures, pesticide use, or industrial runoff.
- Hydrocarbons — petroleum products from underground fuel storage tanks, vehicle workshops, or fuel spills.
- Oily water and chemical residues — from manufacturing, cleaning operations, or agricultural chemical storage.
How Does Soil Contamination Affect Your Build?
Most site remediation work that WCED undertakes follows a demolition job — the previous building contained asbestos materials, and the demolition process, if not carefully managed, can fragment those materials and mix fibres with the surrounding soil. Before any new structure can be constructed, the site must be confirmed free of contamination.
Contaminated soil can affect your build in several ways: it may delay the issuance of a construction certificate, require costly excavation and off-site disposal, expose future occupants to long-term health risks, and — in severe cases — render a site temporarily unusable for residential purposes.
What Does Site Remediation Involve?
A professional remediation project typically follows this sequence:
- Site assessment — a licensed environmental consultant takes soil samples at defined grid points, or targeted locations based on the site history, and sends them for laboratory analysis.
- Remediation action plan — if contamination is confirmed, a plan is prepared that details the type and extent of remediation required, agreed with the NSW EPA or council as appropriate.
- Excavation and classification — contaminated soil is excavated, classified at a licensed facility, and either treated or disposed of at an appropriate waste facility.
- Validation sampling — after remediation, further soil samples confirm the site meets the required health-based investigation levels for the intended use.
- Site clearance report — a licensed assessor provides a report confirming the site is suitable for construction to proceed.
Why Use a Trusted Demolition and Remediation Contractor?
When conducting demolitions, WCED's team is trained to identify potential contamination risks and flag anything that may require sampling or specialist handling. We work alongside licensed environmental consultants and asbestos assessors to ensure that by the time your builder moves onto the site, the ground is clean, classified, and safe for your dream home.
Skipping proper remediation to save time or money is a false economy — contamination that is not addressed before construction can become a serious liability for future owners and occupants. If you have questions about site remediation for your Wollongong or Illawarra block, contact the WCED team for an obligation-free discussion.
Frequently asked questions
- Do I need a soil contamination report before building in NSW?
- It depends on the history of the land. If the site has been previously used for industrial, agricultural, or commercial purposes, or if a structure containing asbestos was demolished on it, a Phase 1 Environmental Site Assessment is usually required before a construction certificate will be issued.
- Can asbestos end up in the soil during demolition?
- Yes. If asbestos-containing materials are fragmented or improperly removed during demolition, fibres and fragments can become mixed with surrounding soil. This is why a pre-demolition asbestos inspection and licensed removal are critical steps before any mechanical demolition.
- Who is responsible for remediating contaminated soil — the current owner or the previous one?
- Under NSW law, contaminated land obligations can attach to the land itself, meaning the current owner may be responsible even if the contamination predates their ownership. Legal advice and an early environmental assessment can clarify your exposure before you purchase or develop a site.
- How long does site remediation take?
- Timelines depend heavily on the type and extent of contamination. Minor asbestos remediation following a residential demolition may be completed in a few days. Larger sites with widespread hydrocarbon or heavy-metal contamination may require weeks or months of remediation and validation work.