Excavating oil-contaminated soil and removing contaminated groundwater in Madeira, Portugal

RSK was commissioned to address the environmental liabilities associated with the past use of land as an oil distribution terminal on the Portuguese island of Madeira before sale of the land for redevelopment could go ahead. The work comprised extensive excavation of hydrocarbon-contaminated soil, on-site material management and groundwater remediation. A RemedX team working on behalf of RSK was responsible for managing the entire project, from site investigation and design through to implementation of the work and regulatory sign-off. This enabled project completion within the proposed tight timeframe and below budget.

The project’s location presented several challenges that RSK managed. Madeira is 550 km from the coast of Morocco and more than 1000 km from mainland Portugal. This meant that minimising waste generation and maximising the use of local resources were critical for economic and sustainability reasons. Consequently, on-site segregation and screening were used during the excavation work to ensure that only fine materials contaminated with oil would be transported off-site for treatment. This resulted in a 35% reduction in the planned disposal volumes. Local subcontractors were responsible for supplying the plant for the excavation work and for the waste management and disposal of materials. A dedicated on-site RemedX team managed and directed the excavation and remediation work.

To satisfy the port authority and the stringent requirements for environmental protection, all off-site waste had to be placed in bulk bags before transportation to an off-site treatment centre. A waste tracking system was implemented to streamline the process and provide traceability of all material moved onto the site and disposed of off-site. On completion of the project, all the material was accounted for and documented.

A PetroFLAG field test kit and an InfraCal analyser were used on-site to determine the total petroleum hydrocarbons in soil, thereby optimising the decision-making process and speeding up the excavation, treatment and backfilling, which were critical during excavation work. This on-site analysis also reduced the number of samples shipped for laboratory analysis, thereby lowering the overall project costs.

The close proximity of the site to the sea and a tourist beach required robust and stringent environmental control during the work. The project was completed in nine months, during which time the total volume excavated, including overdig, was 50,000 m³. In total, 10,000 m³ of contaminated material was screened, 7800 m³ was reused and 2200 m³ was disposed of off-site.