Reusing trench excavation materials as on-site backfill

When a trench opening needs to be reinstated in a road, there are four key issues to be addressed: minimising costs, minimising the environmental impact, minimising the time before the road is re-opened and ensuring adequate performance in service. This paper describes the development of a new, environmentally appropriate process and piece of plant for trench reinstatement. It is designed to be mobile and able to recycle the excavated soil at the trench-side in order to deliver a backfill material with high performance qualities. Costs and environmental impacts are reduced through buying much less newly quarried aggregate because much less of the excavated spoil is sent to landfill. As the device can be transported and used directly at the trench site, this reduces even further the transport costs, congestion and length of time that the trench will remain open. The development process is described in this paper; it is based on laboratory and field tests to assess the treatments and machinery needed. The final device allows the recycling of at least 70% of the excavations.