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February 10, 1992 - i ARCO Station No. 2130, Stockton, California WORK DESCRIPTION The VET performed by RESNA on December 30, 1991, had two objectives: (1) to collect site specific data and evaluate the feasibility of vapor extraction as a soil remediation alternative and (2) to evaluate the off-gas treatment alternatives, if applicable. The equipment utilized for the VET consisted of(1) an internal combustion (I.C.) engine. (2) instrumentation for measuring air flow. air velocity, air pressure, and air temperature, (3) polyvinyl chloride piping, fittings, and wellhead connections, and (4) a portable organic vapor analyzer and air sampling apparatus. RESNA operated the vapor-extraction testing equipment for approximately 5.5 hours. Four vapor-extraction wells(VW-1 through VW-4) previously installed by RESNA were used during the VET. The location of these wells.and other pertinent site features, are shown on the Generalized Site Plan, Plate 2. Well VW-I was used as the initial vapor-extraction well for 2.5 hours while the wellhead ' vacuum, air velocity, organic vapor concentration, temperature, and observed vacuum influence on wells VIV-2, VW-3,and VW-4 were measured and recorded every 30 minutes. Wel! VW-4 was then used as the vapor-extraction well for 3 hours while the wellhead vacuum, air velocity, organic vapor concentration, temperature, and observed vacuum influence on wells VW-1. VW-2,and VW-3 were measured and recorded every 30 minutes. 4 • Two I.C.engine influent and one effluent vapor samples were collected from each extraction well, VW-I and VW-4, to assist in evaluating the appropriate off-gas treatment device and estimate the destruction efficiency of the I.C.engine. Operational data collected during the VET are summarized in Table 1. k' RESNA initiated a Chain of Custody Record that accompanied the vapor samples to a State-certified Iaboratory. We followed chain-of-custody protocol throughout field and laboratory procedures. The samples were analyzed at Sequoia Analytical in Sacramento, California(Hazardous Waste Testing LaboratoryCertificate No.6024),for benzene,toluene, ethylbenzene,and total xylene isomers by modified Environmental Protection Agency(EPA) Method 8020 and for total petroleum hydrocarbons reported as gasoline (TPHg) using modified EPA Method 8015. The results of laboratory analyses for the vapor samples are summarized in Table 1. Copies of the Chain of Custody Records and results of Iaboratory analyses of the vapor samples are attached. RESULTS - - The_highest observed vacuum reading was recorded-at-151-inches of water-from well -- while well VW-4 was undergoing an air flowrate of 99 cubic feet per minute (cfm) and a vacuum of 63 inches of water. The vacuum measurements obtained from this VET are sufficient for use in predicting vaporextraction system specifications. okay 3ODD3-5 2 . v