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ys A S S O C I A T E S I N C 4_3 Vapor Extraction/Air Sparge Testing April 22, 1999 4.3.1 Methods and Procedures On April 22, 1999, ATC performed a short-term air sparge test and a short-term vapor extraction test The purpose of these tests was to evaluate petroleum hydrocarbon removal rates from the saturated zone as a result of sparging, evaluate the propagation of air and helium injected below the groundwater surface, and collect injection flowrate and pressure data for the possible design of an air sparge system ' The first pilot test involved air sparging only, with no vapor extraction Well MW-1 was used as the air injection point Prior to the test, vapor samples were collected from well MW-1, the injection point, and from well VW4, the closest observation well 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 subsequent vapor 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, vapor extraction test equipment (an IC engine) was set up on vapor ' well VW-4 A vapor extraction test was initiated but field personnel were unable to attain a vacuum on the well The equipment was subsequently reset using vapor well VW-I as the vapor extraction point while monitoring vacuum response in the surrounding wells The test was ' approximately 2 hours in length Flowrates, applied vacuums, influent and effluent VOC concentrations, and temperatures were also monitored during the test Vapors were extracted ' using an IC engine equipped with a 5-hp blower and a moisture knockout chamber Two influent vapor samples were collected during the test, one after 30 minutes of operation and one after 105 minutes of operation An effluent vapor sample was collected after 115 minutes of operation Samples were submitted under chain-of-custody to Sequoia Analytical (FLAP #1210) and analyzed for TPHg and BTEX ' 4.3.2 Results Results and field readings from the short-term vapor extraction and air sparge tests performed on April 22, 1999 are summarized in Tables 5 and 6 and contained in Appendix D During the air sparge test, field personnel were unable to obtain a measurable air flow rate into well MW-1 even though the well was pressurized to 100 psi A pressure of 10 psi should have been sufficient to evacuate the water from the well casing Helium was not detected in well VW- W 162574 Mpiiot-ft report doc 6