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transport. Cooling samples will cause condensation of moisture within the sample, thereby distorting the laboratory analysis. To minimize the potential for cross-contamination between air samples, the polyethylene tubing is replaced with new tubing. Vapor samples are also subject to the same hold times and must be stored as stated in SOP-10. SOP-16 SOIL GAS SAMPLING FROM SOIL VAPOR POINT Installation of a soil vapor point may be performed with a hand auger or truck mounted auger drilling rig. Once the boring has achieved the desired depth, a 6-inch long slotted probe, capped on both ends with one end fitted with a Swagelok fitting attached to 3/16-inch diameter Nylon tubing of desired length is placed in the boring and 12 inches of filter pack placed in the annulus. A layer of dry bentonite powder or chips, followed by a layer of hydrated bentonite, and a final layer of dry bentonite powder or chips will be placed in the annulus above the filter pack. Excess tubing at the top is coiled and placed in a flush finished well box. Soil vapor samples will be collected no sooner than one week after probe installation to permit soil vapors to accumulate within the probe. Soil vapor sampling will occur after a minimum of five consecutive precipitation-free days and after any on site irrigation has ceased. The sampling equipment consists of a TedlarTm bag (available in 1, 3, 5, and 10 liter sizes), a diaphragm pump, and 3/16-inch-diameter polyethylene tubing (approximately 1 foot long). The TedlarTm bag should be fitted with an integral valve for filling and sealing the bag after sampling. The diaphragm pump inlet and outlet are fitted with 3/16-inch hose barbs for attaching the sample tubing. A sample label with the sample number and date and time of sample collection is prepared and placed on the Ted!arm" bag. The sampling procedure requires the end of the tubing from the probe be connected to the diaphragm pump inlet hose barb to form an air-tight connection. The sampling pump is then started and the pump is purged for 1 minute with the vapor to be sampled. Following purging, the discharge of the pump is then connected to the TedlarTm bag using a section of 3/16-inch tubing. The pump is restarted and the bag is opened and allowed to fill to approximately 3/4 of its capacity. Caution should be taken not to overfill the sampling bag. The sample is placed in a non-refrigerated dry cooler with sufficient packing to prevent damage during transport. Cooling samples will cause condensation of moisture within the sample, thereby distorting the laboratory analysis. To minimize the potential for cross-contamination between air samples, the polyethylene tubing on the discharge side of the pump is replaced with new tubing. Vapor samples are also subject to the same hold times and must be stored as stated in SOP-10. SOP-17 PRESSURIZED SOLUTION INJECTION For remediation purposes, a portable injection trailer is used to inject a solution of potable water and a chemical oxidant suited to remediate contamination at the site. The injection trailer consist of an air compressor, two 150-gallon polyethylene tanks, pneumatic pumps, and hoses. The injection hoses are attached to the desired injection wells via an injection access point. The injection access point consists of 1/2-inch stainless steel tee which screws into a coupling attached to the injection well and injection hose. The coupling is glued to the injection well at least 48 hours prior to the injection even to ensure the PVC glue has time to properly set and the well elevation is resurveyed. After the injection hoses are attached to the desired wells, the trailer-mounted tanks are filled with potable water from an onsite source. As the tanks fill, the chemical oxidant is mixed into the tank. The amount of oxidant mixed in the tank is dependent on the desired concentration of the solution. After the tanks have been filled, the trailer-mounted air compressor is started and air is supplied to the pneumatic pumps. The pneumatic pumps force the solution into the well through the injection hoses at a maximum of 20 pounds per square inch gauge (psig). The pressure of injection is controlled by a valve and can be reduced, if necessary to avoid damaging the well and well seal. Additionally, each injection access point is equipped with a pressure gauge to monitored the pressure at each injection well individually. After the total volume of solution has been injected, the tanks are washed down with potable water to remove any chemical residue from the tank. The rinsate water is then injected into the well to clean out the hoses. After the injection activities have terminated, the injection access points are left on the wells to ensure that pressure in the wells declines to background levels prior to removing the access points and hoses. A pressure relief valve is located on the access points to relieve any excess pressure above 20 psig.