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Closure Summary Report ELKHORN COUNTRY CLUB 1050 Elkhorn Drive, Stockton, California 1.0. . INTRODUCTION At the request of Mr. Bob Young of Elkhorn Country Club, Advanced GeoEnvironmental, Inc. (AGE) has prepared this closure summary report for the unauthorized release of petroleum- hydrocarbons at the Elkhorn Country Club located at 1050 Elkhorn Drive, Stockton, California(the site). The site and its surroundings are illustrated in Figure 1. Structures and ground water monitoring well locations on the site are depicted in Figure 2. The scope of work included monitoring the operation of a soil vapor extraction blower, collection of soil vapor samples, and conducting quarterly monitoring of the ground water monitoring well a network during the first quarter of 2001. 2.0. BACKGROUND The following is a brief summary of investigations and remediation activities of the unauthorized release from the former underground storage tank(UST) at the site: In 1991 one 1,000-gallon gasoline UST was removed from the site. Two soil samples were a . " collected from beneath the tank at a depth of approximately 10 feet below surface grade (bsg). Total petroleum hydrocarbons quantified as gasoline (TPH-g) and volatile aromatics (benzene, toluene, ethylbenzene and xylenes: BTEX) were detected in the soil.samples at concentrations up to 480 milligram per kilogram (mg/kg). In June 1994, one soil boring(B-1) was drilled at the site. The boring was drilled near the _? center of the former UST excavation, and advanced to a depth of 38 feet bsg. TPH-g and BTEX were detected in all four soil samples analyzed from boring B-1. The highest concentration of gasoline, 3,200 mg/kg, was detected in B-1 at a depth of 30 feet. Ground - water was encountered at 36 feet bsg during drilling. • Between 1994 and 1995 six ground water monitoring wells (MW-1 through MW-6) were installed on the site to delineate the extent of hydrocarbon-impacted soil and ground water in the vicinity of the former UST. Hydrocarbon-impacted soil and ground water were detected in two of the wells. • In January 1996, two borings were advanced around the former UST area and were _ completed as soil vapor extraction/in-situ air sparging pilot feasibility wells. Remedial feasibility studies were conducted in February 1996. In June 1996, a Corrective Action Plan (CAP)was submitted to the PHS-EHD. Recommendations in the CAP included installation of a soil vapor extraction(SVE) system to remediate hydrocarbon-impacted soil and an in- situ air sparging (1AS) system to remediate hydrocarbon-impacted ground water. i Advanced GeoEnvironmental,Inc.