VACUUM ENHANCED REMEDIATION
Vacuum Enhanced Recovery (VER) – This is an active remediation method that is used to remediate impacted groundwater and soils. Remediation is achieved by applying vacuum to a targeted well and extracting either Volatile Organic Vapours (VOCs), Light Non-Aqueous Phase Liquid (LNAPL) and impacted groundwater or both. The most common used VER methods include Soil Vapour Extraction (SVE) and Multi-Phase Extraction (MPE) or Dual-Phase Extraction (DPE).
SOIL VAPOUR EXTRACTION (SVE)
|How?||It involves injecting air (and nutrients) into the targeted contaminated zone via vertical injection wells, with the expectation that volatile contaminants will volatilize. A soil venting system (SVE) is usually employed to capture the contaminated/volatilized air.|
-Oxygenation of soil (and water) enhances in-situ biodegradation + volatiles hydrocarbons which can be extracted from nearby extraction wells.
-To treat contaminated soil situated above deep groundwater.
MULTI-PHASE EXTRACTION (MPE)
MPE a.k.a DPE is another physical in-situ treatment that uses a high-vacuum system to extract contamination in both the liquid and gas phases. Remediation can be achieved in both the unsaturated zone and saturated zone. There are two common pump configurations used for this method including single-pump MPE/DPE and multi-pump MDE/DPE.
Using the single-pump configuration the system relies on high-velocity airflow to lift suspended liquid droplets upwards by frictional drag. This system can be used to extract groundwater or a combination of separate phase products and groundwater.
The multi-pump configuration can be applied to a wider range of site conditions. A large volume of groundwater is extracted by use of a groundwater pump while extracting VOCs from the exposed unsaturated soil by simultaneously applying a vacuum.
The effectiveness of MPE/DPE is influenced by the permeability and volatility of the targeted compounds. The effectiveness of this method increases with permeability. With the same as SVE, the more volatile a compound the more effective the applied method will be.