THE CHALLENGE:
The primary activities undertaken at the site were associated with the surface preparation and corrosion protection of aircraft components— involving the electroplating of metal parts using various combinations of cobalt, chromium carbide, nickel, aluminium, tritium, cadmium and titanium. Post-demolition investigations carried out by Ramboll identified significantly elevated concentrations of Cobalt and Nickel in soils and shallow groundwater below the site, requiring remediation to a ‘baseline’ standard. A key challenge was the potentially significant cost implications of excessively excavating sub-base and underlying soils for uneconomic removal off-site, if not properly segregated and screened during the course of the works.
OUR SOLUTION:
Soilfix designed and delivered a cost-effective remediation solution across 2 phases, in collaboration with Ramboll, which included;
- Controlled breakout & off-site removal of surface slabs overlying contaminated hotspots;
- Decommissioning of groundwater monitoring wells to EA procotols;
- Supplementary trial pitting under supervision of a Ramboll Engineer to further delineate Nickel & Cobalt hotspot extents;
- Controlled excavation of contaminated soils, segregating into stockpiles for field screening using an XRF instrument by a qualified Soilfix Engineer to confirm waste classification based on Nickel & Cobalt concentrations;
- Hand-picking of asbestos cement fragments identified in localised areas for segregated removal off-site;
- Installation of groundwater recovery trenches / sumps to allow for ongoing pumping of significant Nickel / Cobalt impacted shallow groundwater;
- Off-site disposal of 2,000 tonnes segregated hazardous and non-hazardous waste, fully in accordance with Duty of Care;
- Importation of a 6F5 aggregate and backfilling of excavated hotspots; and,
- Periodic tanker visits for recovery of contaminated groundwater from both open excavations and recovery sumps—total 100,000 litres removed to a nearby permitted treatment facility.
All works were completed on programme and with zero lost time accidents / incidents to the satisfaction of Ramboll acting as the client’s supervising engineer.
