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C I lk Ar \TATC %Vol ASS Q C I ATE s INC to remove the obstruction. The rig was used to advance drill rods to 30 feet bsg and approximately 70;gallons of grout was pumped into the well. On April 22, 1999, ATC performed a short-term air sparge test. Well NfW-1 was used as the air injection point. An air compressor capable of producing flows up to 10 cfm was used to pressurize the well casing to 10 pounds per square inch(psi). ATC attempted to initialize airflow but the airflow reading was zero. The pressure in the well was incrementally increased to 100 psi, the maximum pressure the compressor could produce. Helium tanks were also used to increase the pressure in the well but the ;airflow reading remained zero. Helium is used as a tracer in groundwater to aid in the determination of an effective radius of influence for air sparging. Helium measurements were taken from adjacent well VW-4, seven feet away, but no helium was detected. It was uncertain whether the lack of airflow was a result of compressor size or the subsurface stratigraphy. The air sparge test was terminated. During the subsequentvapor extraction test, a helium reading was taken from well VW-5s. Helium was measured at 20% at a distance:of 17 feet from the sparge well. Following the air sparge test, a vapor extraction test was performed using vapor well VW-1 as the vapor extraction point. 'Vapors were extracted for approximately 2 hours using an IC engine equipped with a 5-hp blower and a moisture knockout chamber. Two influent vapor samples and one effluent vapor 'sample were collected during the test. Results and field readings from the short-term vapor extraction and air sparge tests performed on .April 2 , 1999 are summarized in Tables 5 and 6. During the vapor extraction test, extraction flowrates ranging from 35 to 42 cfm resulted in vacuums of up to 0..6' inches of water in vadose well VW-5s located 17 feet from the extraction well, 'Vacuums measured in wells VW-5d, VW-2d, and RSV-1 were less than these measured during the first pilot test because the subsurface had not equilibrated following the sparge test, :Again, no response was observed in wells NM-1 and VW-4, ;located just 6 to 7' feet from the extraction well. Laboratory results of the vapor samples indicated that volatile hydrocarbons W:\62574.01\CAP report.ao 6