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4 . On-site chromatograph, capable of determining micrograms per liter Total Fuel Hydrocarbons . Photovac 1OS50 for field screening. 5 . Manometers, both mercury and water type for taking vacuum readings of the wells and the recovery system. Methods and Procedures : The pilot test was performed by attaching a dual orifice manifold to the well casing. A vapor extraction pump (Rotron DR404, Regenerative Blower) was then connected to the orifice manifold pulling the vapor from the well and pumping it into an ' activated carbon canister' to control emissions . A one day, vapor source test was conducted on March 14 , 1995 . Individual wells MW4 , S1, S2 and MW8 were vented to carbon scrub canisters; MW4 was subjected to a one hour and 10 minute test, S1 was vented for 50 minutes, S2 was vented for one hour and MW8 was subjected to the longest test of 5 hours . Vacuum influence readings were taken on all wells during various times throughout the testing of the individual wells, see Table 2 . The vapor stream was repeatedly sampled and tested during the pilot test by an ambient air Photoionization Detector (PID) Gas Chromatograph (Photovac 1OS50) . Flow rates and vacuum readings were taken concurrently with the vapor stream samples (see Table 2 ard_'"2)7� -The onsite portable chromatograph'- was used to calculate 'poundage removed' and to show any significant changes in the vapor concentration, in regards to time and flow rates, see Table 1 . Selected Tedlar bag samples were obtained during the test and submitted to WEGE ' non-certified' laboratory and analyzed with a GC/FID for C1 through C10 compounds . These vapor samples were also chain of custody delivered to a California State Certified Laboratory (American Environmental Network (AEN) , DHS##1172) and each analyzed for TFH, BTEX. CO2 and 02 were determined in the field using drager tubes/pump and Gastech LEL/02 meter, see Table 1 . The on--site portable chromatograph was used to calculate the concentrations of the vapor stream and also to determine efficacy and emmision control of the vapor extraction system. Flow rates in cubic feet per minute were determined at the site using a one inch orifice plate, the orifice plate was placed in line from the well, this restriction causes a pressure drop across the orifice . The pressure drop across the orifice is used to calculate the air flow rate . Pounds per day and/or hour recovered can be determined from this flow rate and the vapor stream concentration obtained from the sample collected during the flow rate measurement, in mg/L (see Table 1) . 2 USA55 Vapor Ext . Results