Soil and Groundwater Contamination Survey and Countermeasure Technologies

Category of Tchnology	Treatment	In Situ Decomposition Technology
Media	Soil
Contaminants
	Applied (Demonstrated) Substances
Scope	Concentration Range	Approx. 10 mg/l of volatile chlorinated organic compounds
	Hydrogeological Conditions	Saturated	Semi to Impermeable Layer
	Chemical Soil Properties
	Other Remarks
Technology Description	Classification
	Status	Under Demonstration
	Outline of Technology	It is an In Situ agitation system in which lime is mixed in contaminated soil to induce hydration reaction and dehydration effect of the lime, and volatile chlorinated organic compounds are gasified by agitation & aeration.  This system is especially applied to soil with viscosity.
	Required Pre- and Post-treatment
	Enhance Effectiveness through Combination
	Case History	An In Situ agitation system using lime was applied to a site contaminated by trichloroethylene and cis-dichloroethylene.  As for the condition of contamination (GL 0m to 12m), soil concentration (results of an elution test) of trichloroethylene was 0.1 to 0.17 mg/l, and cis-dichloroethylene 0.01 to 7.0 mg/l.  After remediation of GL 0 to 5m with blade agitation speed 480 times (It is unknown why deeper soil was also remediated although agitation were carried out at 5m deep) and 150kg/jm3 of lime, the environmental standard for soil was satisfied at all depth.  The soil of the contaminated site included clay layer and sand layer which proved that this system can be applied to clay layer.  The groundwater level of the demonstrated contaminated site was very high, at 1 m, but this system could be applied.
	Application Examples	Yes or few.
	Limitations	At a demonstration test and indoor experiment, the system was applied to soil contaminated by trichloroethylene and the results showed the concentration of the contaminant was reduced below the environmental standard for soil.  However, the mass balance of trichloroethylene is not clarified yet, which gives some doubt to the credibility of the system.  Particularly, it is doubtful that in an elution test TCE can be recovered completely from the soil clotted with lime.
	Properties of Treated Soil	Possibility of Change in Properties
Schematic Flow Process
Applicability	In Situ Applicability	Possible
	Ground Structures
	Required Excavation	Excavated soil is treated (Applied excavated soils for excavated soil)
	Groundwater Extraction	None
	Required Space	Capable of operating the soil agitator unit shown in the flow chart.
	Operational Time
	Installation Time
	Maintenance and Control Requirements
	Additional Remarks
Secondary Impacts to Environment	Secondary Treatment Required?	Off-gas Treatment
	Effects on Living Environment	Noise Vibration
	Additives	Others (Lime)
	Possibility of Contaminant Spreading	Volatile chlorinated organic compounds may proliferate when agitating and mixing are carried out.
	Secondary By-products	Highly concentrated trichloroethylene should be treated with care since it may produce dichloroethylene from a reaction with alkaline.

• Understanding the Contamination Survey and Countermeasure Technology Description Sheet
• Where to make contact

Soil Environment Management Division, Water Environment Department, Environmental Management Bureau, Ministry of Environment
Tel: +81-3-5521-8319
E-mail: MOE@env.go.jp