Friable Asbestos-Contaminated Soil Assessment, Remediation and Validation – Central Coast NSW
Prepared by Confluence Environmental — independent asbestos, contaminated land and occupational hygiene consultants supporting high-risk remediation projects across NSW.
Confluence Environmental was engaged following civil excavation works associated with the reconstruction of a large retaining wall on the Central Coast, NSW, where friable asbestos-contaminated soil was identified during construction activities.
The engagement involved a staged program of asbestos inspection and assessment, contaminated land delineation, waste classification, remediation planning, air monitoring and post-remediation validation to support safe site management and lawful remediation.
Project Background
During excavation works to facilitate the demolition and rebuild of an existing retaining wall, significant quantities of asbestos-containing materials were identified within soil and fill materials. These materials included both non-friable asbestos cement fragments and friable asbestos, including pipe lagging and degraded insulation materials.
Given the nature of the materials and the potential exposure risk, works were halted in the affected area and Confluence Environmental was engaged to independently assess the extent of asbestos contamination and develop a defensible remediation pathway.
Initial Inspection and Assessment
Confluence Environmental undertook a detailed asbestos contamination assessment of the impacted area, including:
Targeted inspection of exposed soils and excavations
Identification of asbestos material type and condition
Differentiation between friable and non-friable asbestos
Assessment of potential fibre release pathways
Preliminary delineation of impacted areas
Findings were documented in a detailed technical report that defined the nature and extent of asbestos contamination and provided the basis for remediation planning.
Remediation Strategy and Management Planning
Based on the assessment outcomes, Confluence Environmental prepared a remedial management plan to support safe remediation and long-term site management.
The remediation objectives were defined to:
Facilitate reconstruction of the retaining wall
Manage asbestos risk in remaining soils
Minimise disturbance beyond the required works area
Establish long-term controls appropriate for the site
The client elected to remove only the asbestos-contaminated soil required to facilitate the retaining wall rebuild, with remaining impacted areas managed through engineered capping and inclusion within the site’s asbestos documentation.
Waste Classification and Disposal Pathway
Confluence Environmental was subsequently engaged to undertake waste classification of the asbestos-contaminated soils to support lawful off-site disposal.
Laboratory analysis identified elevated concentrations of lead and mercury within the soil, exceeding criteria for both General Solid Waste and Restricted Solid Waste. To refine the classification and avoid unnecessary escalation to hazardous waste disposal, Toxicity Characteristic Leaching Procedure (TCLP) testing was undertaken.
Based on TCLP results, the material was classified as Special Waste (asbestos-contaminated material) mixed with General Solid Waste, allowing disposal to an appropriately licensed facility in accordance with NSW EPA requirements.
Remediation Works and Air Monitoring
Remediation works were undertaken by a Class A licensed asbestos removal contractor, engaged under Confluence Environmental’s technical oversight.
Confluence Environmental conducted daily asbestos air monitoring throughout remediation works to verify the effectiveness of control measures and protect workers, adjacent areas and the surrounding environment.
No airborne fibre exceedances were recorded during remediation.
Capping, Clearance and Validation
Following completion of soil removal works, the remaining impacted area was capped with an engineered barrier system incorporating a geotextile marker layer to provide long-term risk control and future disturbance warning.
Confluence Environmental then completed an independent asbestos clearance inspection, confirming that the remediated area met clearance requirements and was suitable for the intended use.
Post-Remediation Documentation and Long-Term Management
To support ongoing compliance and risk management, Confluence Environmental prepared:
An updated asbestos register incorporating remaining capped areas
A site-specific asbestos management plan
A long-term environmental management plan outlining inspection, maintenance and disturbance controls
These documents provide a clear framework for future site use, maintenance and any potential disturbance activities.
Outcomes
The project successfully delivered:
Safe and compliant remediation of friable asbestos-contaminated soil
Lawful disposal of asbestos-contaminated material through refined waste classification
Verification of remediation effectiveness through air monitoring and clearance
Practical long-term risk management without unnecessary over-remediation
The staged, evidence-based approach allowed the client to manage a complex asbestos contamination issue efficiently while maintaining regulatory compliance and site safety.
Why This Project Matters
Friable asbestos contamination in soil presents one of the highest risk scenarios encountered on civil construction projects. This project demonstrates the importance of:
Early independent assessment
Clear delineation of friable versus non-friable materials
Integration of waste classification and remediation planning
Independent air monitoring and clearance
Long-term management aligned with actual site risk
Confluence Environmental’s Role
Confluence Environmental provides independent friable asbestos assessment, contaminated soil remediation support, air monitoring and validation services across NSW.
Our approach focuses on proportionate remediation, defensible documentation and outcomes that protect health, satisfy regulators and support practical project delivery.