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1 I • INTRODUCTION At the request of Exxon Company, U.S.A. , a Soil Gas Survey and a Performance Test were conducted at the subject site. Included in this report are a description of the investigation procedures, the results of the Soil Gas Survey and the Performance Test, an interpretation of the results, and conclusions. BACKGROUND The subject site is that of a former Exxon rest stop located at the northwest corner of Hammer Lane and Sacramento Road in Stockton, California. The service station structures have been demolished and the tanks and pipelines have been removed. The site is currently a vacant lot. The surface material at the site consists of bare soil and patches of asphalt. The approximate depth to groundwater is 48 to 58 feet. PURPOSE AND SCOPE The specific objectives of this investigation were 1) to delineate the lateral and vertical boundaries of hydrocarbon vapors and 2) to evaluate the feasibility of soil remediation by vacuum extraction. These objectives were met through completion of the following tasks: 1) Soil Gas I Survey and 2) Performance Test. All data collected in this investigation are considered confidential and will not be released to a third party without the written consent of an authorized representative of Exxon Company, U.S .A. PROCEDURES Soil Gas Survey The Soil Gas Survey was initiated on 12 March 1990 and was completed the following day at this site. Thirteen temporary vapor probes were installed for the investigation. ! Placement of the temporary vapor probes was determined in the field by the site investigator as the survey progressed (Figure 1) . Soil gases extracted from the temporary vapor probes and five existing groundwater monitoring wells were analyzed for total hydrocarbon concentration as vapor (TVH) during the Soil Gas Survey.