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I S I AM FROM P t O Once at the desired sampling interval,extension rods are sent downhole until the leadeng rod contacts the bottom til the samples screen. The tool string is th,cn retracted approximately 44 inches (I I18 iritis) whsle the screen Ls held in place with the extension rods(Fig 2 1B) As tnc tool stung is retracted,the expendable point ic released From the sampler sheath An O-nng on the screen head maintains the seal at the top ofthe ' screen As a result, any liquid entering the sampler during screen deployment must first pass through the screen Me tool sinno and sheath may be retracted the full length of the screen oras little as a few inches if a small%arnpling interval is desired ' rhe Scieen Point 15 Sampler utilizes a screen with a standard slot srza of 0 004 inches (0 1 mire)and an exposed lengtn of 41 inches (1041 mna) Alternate slot sizes and lengths may be custorn ordered. Contact ' Geoprobe Systems fol available options The screen is constructed such that a check valve or mint-bailer can be smiertud into the screen cavity This makes direct sampling pu5saoleT from anywhere within the Saturated lone A removable plug in the lower end of the screen allows the user to grout as the sampler is exti-acted for further we. Groundwater samples can be obtained in a,number of ways. The most common method utzh=polyethyl- ene or Teflon® tubing and a'Tubing Bottom Check Valve(GW-42) The check valve (with check ball) is attached to one end of the tubing and inserted Clown the casing unto it is immersed in groundwater Water is pumped through the tubing and to the ground surface by oscillating,the tubing up and down Another means of collecting groundwater sanples is to attach a peristaltic or vacuum pump to the tubing This method is limited in that water can be pumped to the surface front a maximum depth of approximately 26 Leet(8 m) A final technique for groundwater Sampling is to use a stainless steel Mini-Batler Assembly l (GW-41) Tire mini-bailer is lowered down the inside ofthe casing below the water level where it fills with ie water and t� then retrieved from the casing I