Ground water extraction method and system

Abstract

A vacuum extraction tube is placed within a well casing which is permeable to gas and water at least within the vertical range of contaminated soil from which vapors and/or water are to be removed. The extraction tube has its lower open end extending a few inches above the water table. An internal venturi nozzle or passage adjacent the lower open end of the extraction tube is in exterior communication with one end of a siphon tube depending therefrom. The siphon tube has its opposite extend extending below the surface of the water in the casing, at least to a depth of contaminant-bearing soil from which vapors or water are to be removed. When vacuum is applied to the extraction tube through the exhaust end of a blower, self-priming air from within the casing is entrained upwardly through the open end of the extraction tube. As air velocity increases through the venturi passage, vacuum is created at the connection of the siphon tube to the venturi and lifts well water to the venturi passage where the water is atomized.

Having described my invention, I claim:  
     
         1 . The method of in situ extraction of ground water from a well casing for use, treatment or disposal at a location remote from the well casing; 
 introducing an open-ended extraction tube into said casing;    connecting a source of vacuum to said tube remote from said open end;    providing for continuous flow of air through said extraction tube from within said casing above the water table and to a collection area associated with said source of vacuum;    converting water in said casing into a mist above the water table; and    extracting the mist and air by means of air flow within said extraction tube.    
     
     
         2 . The method set forth in  claim 1  wherein the mist conversion is produced internally of the open-ended extraction tube through atomization, said method further including the steps of providing a venturi passage adjacent the open end of said extraction tube and providing an elongated auxiliary siphon tube having one open end in communication with said passage and the opposing end immersed in water in said casing below the water table.  
     
     
         3 . The method set forth in  claim 1  including the further step of separately collecting water and air substances at said collection area, decontaminating at least one of said substances and discharging the substance upon achievement of decontamination to an acceptable level.  
     
     
         4 . The method set forth in  claim 2  including the further step of separately collecting water and air substances at said collection area, decontaminating at least one of said substances and discharging the substance upon achievement of decontamination to an acceptable level.  
     
     
         5 . The method set forth in  claim 4  including the additional step of providing and maintaining air pressure within said casing above the water table, said pressure being maintained at a level consistent with maximum flow of mist through said extraction tube.  
     
     
         6 . Apparatus for practicing the method of  claim 2 , wherein said venturi passage is substantially annular.  
     
     
         7 . Apparatus according to  claim 6 , wherein a cross-tube is connected to said siphon tube, said cross-tube extending laterally across said venturi passage and having an open elongated slit facing in the direction of air flow to maximize water extraction through said siphon tube and thereby enhance mist creation in said extraction tube.  
     
     
         8 . Apparatus according to  claim 7 , wherein the liquid portion of said mist between said venturi passage and said vacuum source travels essentially as rivulets on the internal walls of the extraction tube.  
     
     
         9 . Apparatus for practicing the method of  claim 1  or  2  wherein volatile contaminants in the water are at least each partially stripped therefrom.  
     
     
         10 . The method of in situ extraction of vapor from soil within a region of interest defined by strata having an upper and a lower level and which region lies at least partially below a water table in the soil, said method comprising the steps of: 
 providing a vertical casing from grade level to said region of interest, which casing is pervious to liquid and gas at least in the range of said region of interest;    providing a vacuum extraction tube having an open lower end, said tube extending downwardly from grade level to a point above the water table;    creating a vacuum in said tube at a flow rate sufficient to exhaust a mist of water and gas to grade level for collection of water and gas thereat;    converting standing water in said casing into a mist above the water level;    evacuating the mist through said tube by means of vacuum and delivering it to a collection station at grade level; and    continuing to evacuate water and gas in mist form simultaneously through said pervious portion of said casing while maintaining the level of water in said casing below the static water table, whereby contaminant vapor contained in said soil within said region of interest is continuously extracted therefrom and removed through said tube by vacuum.    
     
     
         11 . The method set forth in  claim 10  wherein the mist is produced by means of increasing the velocity of air flowing through said tube to create a vacuum at a port at the side of the area of increased velocity, and providing a siphon tube extending from said port to a level below the water level in the casing whereby to draw water through said siphon tube and atomize the drawn water as it enters said tube in the area of increased air velocity.  
     
     
         12 . Apparatus for practicing the method of either of claims  10  or  11 .