The Challenge
Ramboll’s client required a disused 60,000 litre underground diesel storage tank (UST) to be excavated and removed with the resulting excavation then reinstated back up to ground level. The tank was located within an active HGV distribution depot— the excavation footprint therefore required reinstatement with a reinforced concrete slab and new surface water drainage to tie into an existing network.
Due to the requirement for net import of material to backfill the tank void space, targeted segregation of potentially contaminated materials and validation testing of excavated soils to demonstrate compliance with the remediation strategy and enable their re-use was of paramount importance to limit site export and import.
Due to loose sands & gravels surrounding the UST and close proximity of HGV movements and a raised embankment, comprehensive temporary works were required installed to facilitate safe excavation and removal of the tank.
Our Solution
- Comprehensive Temporary Works design in accordance with Soilfix procedures;
- Trench sheeting and bracing solution installed around the tank to enable safe excavation and removal of the tank and surrounding soils;
- Removal of residual diesel fuel within the UST and contaminated perched groundwater, cleaning to render ‘gas free’;
- Segregation, testing and verification of excavated soils to validate as suitable for re-use against the remediation strategy, with small volume of unsuitable material exported under full Duty of Care;
- Controlled excavation and removal of the UST under full Duty of Care;
- Reinstatement and compaction of imported backfill/site won materials to ground level, with geotechnical testing to validate compaction; and,
- Installation of new reinforced concrete slab and drainage to tie into existing distribution yard.
Soilfix successfully removed the UST, met all Remedial Strategy objectives whilst ensuring sustainable re-use of selected materials— all with zero lost-time accidents.
The area was backfilled and all hard standing/drainage reinstated to the required specification without significant disruption to the client’s operations.
