A vacuüm is applied to refresh the unsaturated zone of the soil. This causes volatilization of the contamination: primarily because the concentration of the contamination in the gas phase is reduced, causing a new balance between the soil and the gas phase. Secondly, the concentration of the contamination in the soil is reduced. In addition, soil vapor extraction increases the oxygen concentration, thus the biological degradation is (partly) stimulated. The extracted air is cleaned by an activated carbon filter (sorption), biofilter (biological decay) or catalyst (chemical decomposition).
Soil vapor extraction
Soil Vapor Extraction is applicable for volatile contaminants such as light mineral oil, chloro-ethenes (CVOC) and volatile aromatic compounds (TEX). Soil vapor extraction can be applied to the unsaturated zone of soil. The unsaturated zone can be increased by lowering the water table. A moderate/well permeability of the soil is required for this technique. The technique can be applied for both the source and the plume of the contamination if they consist mainly of volatile compounds. Soil vapor extraction is often combined with air injection and pump & treat.
The costs are primarily dependent on the concentration of the contamination and the selected air treatment technology. The duration of the remediation varies from several months to decades. This is dependent on the initial concentration, the permeability and the organic matter content in the soil. Using this technique usually causes a low site disturbance, depending on the selected air treatment technology. The equipment can be placed in a (sound-proof) container.
Related cases and HIP-pilots
Related cases: Aerobic bioremediation of oil and BTEX (The Hague)***, Amsterdam: mineral oil, BTEX **, Beek: Mineral oil Kerosine *, Bergen op Zoom (busstation): Mineral oil, BTEX en PAH’s***, Den Bosch (de Kruithoorn): CVOC*, Doetinchem (Saronix): CVOC, mineral oil and BTEX***, Hilversum: CVOC, Kampen (IJsseldijk): Mineral oil, BTEX, naphthalene**, Leidschendam (Neherpark): CVOC and BTEX***, Lochem: mineral oil,BTEX,PAH,naphthalene,creosote ***, Military petrol station: ISCO for mineral oil and BTEX*, Nijverdal (Smidsweg 100a):BTEX, PAH’s, naphthalene and mineral oil**, Petrol station: combined techniques for BTEXN and oil (Putten)***, Putten (Garage Koster): Mineral oil, BTEX, Naphthalene***, Rotterdam-Botlek: BTEX*, Rotterdam-Botlek: VAM-spill*, Veere (Neeltje Jans): Mineral oil***, Zwolle (Dellen Wuyts): CVOC *, Zwolle Russenweg: Mineral oil, turpentine **
Voor uitgebreide informatie over deze techniek: www.bodemrichtlijn.nl