Soil and Groundwater Contamination Survey and Countermeasure Technologies


Air Sparging For Groundwater Treatment
 
Category of Tchnology Treatment  In Situ Extraction Technology
Media Groundwater, Soil Gas
Contaminants
  • Volatile Chlorinated Organic Compounds (TCE, PCE, etc)
  • Volatile Hydrocarbon (Benzene, etc)
Applied (Demonstrated) Substances Toluene, PCe, TCE, Carbon-Tetrachloride
Scope Concentration Range higher concentration
Hydrogeological Conditions
  • Saturated
  • Permeable Layer
Chemical Soil Properties  
Other Remarks It can be regarded as an in-situ air stripping, and groundwater is no more needed to be pumped up.
In US and in Europe, it’s expected to promote aerobic biodegradation as it injects air into groundwater.
Technology Description Classification  
Status
  • Under Demonstration
  • Soil and Groundwater Countermeasure Test Study (Performed 1995)
Outline of Technology As an analogy to Soil Vapor Extraction.  Air Sparging involves injection of air into unsaturated soil and/or groundwater which is contaminated with VOC’s, excites airflow through soil pore volume and promotes volatilization of contaminant.  Injected air is recovered as soil gas, contributes to the remediation.
Required Pre- and Post-treatment More volume of air is required to be recovered than injected, and some treatment is needed for the recovered air for discharge.
Enhance Effectiveness through Combination  
Case History In a perched water contaminated with Toluene and TCE (the geology is volcanic ash clay, the depth from GL is -3.9 ~ -5.15m), 0.12 ~ 0.56 [m3/min] of air for each is injected through 3 injection well and 0.18 ~ 0.87 [m3/min] of air for each is recovered through 3 extraction wells.
Total of 3.47 [kg] of contaminant was recovered in the test operation of 184.8 [hr]. (quantity of the collected air this time was 19g/hour).
Radius of influence of the injected air was estimated to be roughly 2m by an observation of the groundwater mounding.
Application Examples Commonly applied to treatment of VOC contaminated sites in US and in Europe.
Limitations Permeability of the media is required to be high.
For some sites with high groundwater flowrate, countermeasures are required to restrict migration of contaminated groundwater.
Properties of Treated Soil
-
Schematic Flow Process
The Location of Injections and Extraction Wells
Applicability In Situ Applicability Possible
Ground Structures Applicable even if Ground Structures are Present
Required Excavation A little amount of soil excavation is required to install injection wells, extraction wells and monitoring well.
Groundwater Extraction Sometimes, required to countermeasure to the migration of contaminated groundwater.
Required Space Usually, 20 - 50 m2
Operational Time Possibly, shorter than the conventional pump and treat.
Installation Time  
Maintenance and Control Requirements As well as measurement of injection / extraction flowrate and contaminant concentration in extracted soil gas, monitoring of contaminant concentration in adjacent groundwater and soil gas is necessary.
Additional Remarks
  • Effluent Water Treatment 
  • Off-gas Treatment
    •
    Secondary Impacts to Environment Secondary Treatment Required?  
    Effects on Living Environment Noise 
    Additives Air
    Possibility of Contaminant Spreading Migration of Contaminated soil gas’s possible unless proper design and operation of soil gas extraction system
    Secondary By-products None
    (July 2002)
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