In situ soil decontamination method and apparatus

A method for in situ decontamination of an earth material, comprising the steps of:

• forming one or more wells in a contaminated site;
• installing a casing in each said well so that a gas can be injected into the earth material from a bottom portion of the casing;
• forming a surface trench network between each said well so that at least one central trench collection point is defined;
• covering the contaminated site with an impervious material;
• pumping a heated gas down each said casing so that the heated gas is injected outwardly therefrom into the earth material at the bottom portion of the casing;
• forming a negative pressure at said central trench collection point for drawing vaporized contaminants from the surface of the contaminated site;
• and
• disposing of the contaminants.

A method for in situ decontamination of an earth material, comprising the steps of:

• pumping a gas down a borehole formed in a contaminated site, with a first pressure sufficient to purge the borehole of earth material liquid;
• reducing the pressure of the gas;
• pumping a heated gas down the borehole for an extended period of time to vaporize volatile contaminants in the earth material of the site;
• increasing the temperature of the heated gas after the volatile contaminants have been vaporized to vaporize less volatile contaminants;
• and
• collecting the vaporized contaminants at the surface of the site for disposal thereof.

A method for in situ decontamination of an earth material, comprising the steps of:

• defining a circumferential boundary of a contaminated site;
• forming wells at spaced apart locations proximate said boundary;
• and
• installing a gas directional casing in each said boundary well so that when a gas is injected into said casing, the gas substantially permeates the contaminated site defined by the boundary and is not substantially permeated in an area external to the boundary.

A method for in situ decontamination of an earth material, comprising the steps of:

• forming a gas injection well in a contaminated zone of the earth material;
• injecting a gas in the well and slowly raising the pressure to displace liquid water occluded in the earth pore space surrounding the well;
• and
• increasing the temperature of the gas injected into the well to evaporate the occluded water and increase the permeability of the earth material, said temperature increase being carried out slowly so that evaporated water is not recondensed in an area defined by a heat front to an extent that recondensed liquid substantially reduces the permeation of the gas therethrough.

A system for use in decontamination of an earth site having at least one borehole, comprising in combination:

• a burner for heating a gas;
• a compressor for forcing the gas through said burner so as to be heated and injected into the borehole;
• a vapor collection system for collecting vapor contaminants from the surface of the site;
• and
• an incinerator fired by said burner and connected to said vapor collection system for incinerating the contaminants.

A system for use in decontamination of an earth site having at least one borehole, comprising in combination:

• a burner for heating a pressurized gas;
• a compressor for supplying a compressed gas to said burner;
• an inlet to said burner for supplying vapor contaminants to said burner for combustion thereof;
• said burner having a mixing chamber for mixing heated and pressurized gases with combustion gases;
• an outlet of said burner, said outlet being coupled to said borehole for injecting therein heated combustion gases;
• and
• a recovery system for recovering contaminants vaporized by said injected gases, said recovery system being coupled to said burner inlet.