ISTT Educational Webinar: Trenchless vs Open Trenching for Gravity Sewer Installation

Traditional comparisons between trenchless and open trench construction often focus on productivity, cost, programme duration and carbon emissions. While important, these measures do not fully capture the broader impacts of gravity sewer installation, including worker safety, community disruption, environmental performance and long-term infrastructure outcomes.

This webinar compares open trenching and trenchless construction through the lens of safety exposure, construction complexity, community impact and whole-of-life asset stewardship.

Drawing on practical project experience, including the SA Water Munno Para Sewer Trunk Main project, the presentation examines how construction methodology influences workforce exposure, plant and people interactions, utility conflicts, traffic disruption, carbon emissions and future maintenance requirements.

A key focus is the relationship between construction complexity and risk. By comparing workforce size, concurrent activities, utility interactions, material movements and public interfaces, attendees will gain insight into how different approaches affect both safety and project performance.

The webinar also introduces the concept of Permanent Ground Disturbance, exploring whether infrastructure projects should be assessed not only on safe delivery, but also on the long-term impacts imposed on asset owners, road authorities and future generations.

Using real project data, including the successful installation of gravity sewer infrastructure on grades as low as 0.13 per cent, attendees will see how modern trenchless methods can reduce workforce exposure, minimise community disruption, avoid utility conflicts and deliver environmental benefits while maintaining productivity.

The session concludes by examining how whole-of-life assessment frameworks may influence future infrastructure decisions and why many asset owners are increasingly considering trenchless solutions for gravity sewer construction.

Attendees will gain an understanding of:

• Comparative safety risks associated with open trench and trenchless sewer construction.
• How construction complexity influences workforce exposure and project risk.
• Environmental and carbon impacts of different installation methodologies.
• Community and stakeholder impacts associated with gravity sewer construction.
• The concept of Permanent Ground Disturbance and whole-of-life infrastructure impacts.
• How trenchless construction aligns with the hierarchy of controls through hazard elimination.
• Emerging approaches to evaluating infrastructure projects beyond cost and productivity metrics.