Soil and Groundwater Contamination Survey and Countermeasure Technologies

Category of Tchnology	Treatment	On-site Extraction
Media	Soil, Groundwater, Soil Gas
Contaminants	Heavy Metal (Cd, Pb, As, Hg, Se, etc) Inorganic Compounds (total CN, etc) Reducible Inorganic Compounds (Cr6+, etc) Volatile Chlorinated Organic Compounds (TCE, PCE, etc) Semi Volatile Chlorinated Organic Compounds (PCB, etc) Volatile Hydrocarbon (Benzene, etc) Agricultural Chemicals (Organic Phosphorus Compounds, etc)
	Applied (Demonstrated) Substances	Trichloroethylene, Tetrachloroethylene
Scope	Concentration Range	It is difficult to solidify contaminants in their original liquid forms.
	Hydrogeological Conditions	Saturated Unsaturated	Permeable Layer Semi to Impermeable Layer
	Chemical Soil Properties
	Other Remarks
Technology Description	Classification
	Status	Under Demonstration Soil and Groundwater Countermeasure Test Study (Performed 1994)
	Outline of Technology	This is physical measures, in which rods are driven down to the required depth by water-jet hammer, to inject cement milk containing hardening agents into the ground in high pressure, thereby to displace the contaminated soil with hardened concrete. The technologies to remove the clay contaminated with VOCs, such as trichloroethylene, have been proven effective.
	Required Pre- and Post-treatment	The injection of cement milk breaks up an equivalent volume of clay body into slime, which surfaces and needs to be disposed of.
	Enhance Effectiveness through Combination
	Case History	Cement milk was injected into the section of 1.5 m in depth between GL-3 m to GL-4.5 m to form 195 cylindrical solid bodies of 1.6 m-diameter .  The sampled solid bodies were found to have formed the desired non-permeable layer (10-9 - 10-10 cm/s).  However, a solution test found that the conditions remained unchanged in some parts.  Thus, as a second step, the instant hardening/displacing method was used.  Resultantly, the solid bodieselution was proven to meet the Soil Environmental Quality Standards.
	Application Examples	The technology has been used for the restoration at one place in Chiba Prefecture.  Besides, it has been used in many cases to improve soft ground.
	Limitations	This method is difficult to apply to the area under buildings, etc.
	Properties of Treated Soil	Properties Change to Major Extent
Schematic Flow Process	System Devices for High-pressure Jet-propelled Agitation, Displacement, Solidification
Applicability	In Situ Applicability	Possible
	Ground Structures	Not Applicable
	Required Excavation	Rods have to be driven down by water-jet hammer.
	Groundwater Extraction	None
	Required Space	From 24 m2 to 90m2, depending on the scale, to install the machines.
	Operational Time	Depends on the scale.  In particular, the hardening speed of the injected cement milk is a determining factor.
	Installation Time
	Maintenance and Control Requirements	Disposal of the slime and preparation of the cement milk are required.
	Additional Remarks
Secondary Impacts to Environment	Secondary Treatment Required?	Off-gas Treatment
	Effects on Living Environment	Noise
	Additives	Air Water Others (Cement milk)
	Possibility of Contaminant Spreading	The injection of cement milk may disperse contaminants.
	Secondary By-products	None

• 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