SITE: Fuel depot – storage capacity 55.000 m3
Geostream Africa supplied, installed and operates an active skimming system for a multinational consultancy company, within their environmental service agreement with a major oil&gas company.
The groundwater contamination from volatile organic compounds and LNAPL (Light Non-Aqueous Phase Liquid), impacted the aquifer below the petrol station and the plume migrated off-site, reaching the downgradient private boreholes.
The hydrogeological setting with low aquifer permeability and the restrictions on groundwater extraction, represented appropriate conditions for the implementation of an active skimming technology for LNAPL recovery.
The remediation plant is connected to 7 extraction wells to intercept the plume of contamination where most of the LNAPL is adsorbed. The system included a control panel with PLC, an air compressor connected to the pneumatic skimmer pumps, a controller and an oil/water storage tank of 5 m3. The small amount of water separated into this tank is treated through 2 activated carbon filters, before discharging into 2 IBC containers for analytical testing. The clean water is then discharged by gravity into an infiltration trench. The system has been running in automatic mode in the past 20 months with an outstanding operational performance that lead to the recovery of approximately 4000 litres of free-phase product and the treatment of 2000 litres of contaminated water.