Stephenson Avenue Extension – Western Australia

Enveng Group has been engaged on the Stephenson Avenue Extension Project since 2020, providing environmental leadership, management and advisory services across both the planning and construction phases of this major urban transport infrastructure project. Delivered through the S2M Evolution Alliance, the project extends Stephenson Avenue between Scarborough Beach Road and Cedric Street, including associated interchange and rail interface works within a highly constrained urban environment.

The project presented significant environmental and technical challenges including contaminated land, acid sulfate soils (ASS), asbestos contamination, PFAS management, groundwater dewatering, environmental monitoring and regulatory compliance. Enveng was embedded within the Alliance team, supporting the integration of environmental requirements into project planning, construction delivery, risk management and regulatory approvals. Enveng’s involvement commenced during the Alliance Development Stage, where the team assisted in preparing key environmental management frameworks and construction strategies designed to manage high-risk activities and mitigate environmental impacts. These included:

• Construction Environmental Management Plan (CEMP)
• Acid Sulfate Soils Management Plan (ASSMP)
• Contaminated Sites Management Plan
• Asbestos Management Plan
• Noise and Vibration Management Plan
• Dewatering Management Plans
• Environmental Monitoring Programs
• Fauna Management and Testudines Management Plans

During construction, Enveng provided ongoing environmental management and specialist technical support across a range of workstreams including:

• Contaminated land investigation, classification and remediation.
• PFAS investigation and management.
• Groundwater investigations, dewatering design and monitoring.
• Acid sulfate soil investigations, treatment and management.
• Asbestos investigation and management.
• Waste classification and disposal management.
• Environmental compliance monitoring and reporting.
• Regulatory liaison with DWER and other stakeholders.
• Environmental auditing and assurance.
• Development of GIS and digital environmental monitoring systems.

A particularly notable aspect of the project involved responding to the discovery of asbestos-contaminated spoil and complex contamination issues associated with the former Hertha Road landfill area. Enveng led environmental incident management activities including site shutdown protocols, dust suppression measures, air quality monitoring, contamination investigations, remediation planning, stakeholder engagement and coordination with regulators and contaminated sites auditors.

Services Delivered

• Environmental Management and Leadership
• Construction Environmental Management
• Contaminated Sites Investigation and Remediation
• PFAS Assessment and Management
• Acid Sulfate Soil Investigations and Management
• Groundwater and Dewatering Management
• Environmental Monitoring Programs
• Noise and Vibration Management
• Asbestos Investigation and Management
• Compliance Auditing and Reporting
• Regulatory Engagement and Approvals Support
• GIS and Digital Environmental Reporting Systems
• Environmental Risk Assessment and Mitigation
• Sustainability and Environmental Performance Reporting

Value Delivered

Enveng’s involvement enabled the Alliance to proactively identify, manage and mitigate significant environmental risks that had the potential to impact programme, cost, stakeholder confidence and regulatory compliance. Through early planning and embedded project support, Enveng ensured environmental requirements were integrated into project execution rather than treated as standalone compliance obligations. Key value delivered included:

• Successful management of complex contamination, asbestos, PFAS and groundwater challenges within a highly constrained urban environment.
• Rapid response and management of environmental incidents, minimising project disruption and regulatory risk.
• Development of practical, construction-focused environmental controls that supported safe and efficient project delivery.
• Ongoing liaison with regulators, auditors and stakeholders to maintain compliance and stakeholder confidence.
• Implementation of real-time environmental monitoring and GIS-based reporting tools to improve project visibility and decision-making.
• Delivery of cost-effective environmental management solutions that supported programme progression while maintaining environmental performance standards.
• Integration of environmental risk management into Alliance governance and construction planning processes.
• Support of worker safety, community confidence and regulatory compliance throughout project delivery.

The Stephenson Avenue Extension Project demonstrates Enveng Group’s capability to successfully manage environmental risks on large-scale, high-profile infrastructure projects where contamination, groundwater, regulatory scrutiny and stakeholder expectations play a critical role in project success. The project highlights Enveng’s strength in providing embedded environmental leadership that bridges planning, approvals, construction and compliance to achieve practical and commercially focused outcomes.