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' Quarterly Report - Fourth Quarter 2004 <br /> • City of Stockton - FIRE STATION #2 <br />' 110 West Sonora Street, Stockton, California <br />' 1.0. INTRODUCTION AND SCOPE OF WORK <br /> At the request of the City of Stockton,Advanced GeoEnvironmental, Inc (AGE) has prepared this <br />' report for corrective action activities conducted at 110 West Sonora Street, Stockton,California(the <br /> site) The location of the site and its surroundings are illustrated on Figure 1 Structures and well <br />' locations associated with the site are depicted on Figure 2 <br /> An ozone air sparging system was installed 01 July 2003 on-site, utilizing the existing in-situ air <br />' sparging (IAS) system wells IAS-1 through 1AS-3 The system has operated continuously since <br /> installation This report documents ground water monitoring and sampling of monitoring wells on <br /> 03 December 2004 in order to determine concentration trends for the petroleum hydrocarbons <br /> 1 1 SITE BACKGROUND <br /> The site is bounded on the north by Sonora Street, on the west and south by Madison Street and on <br /> the east by Commerce Street Presently a single building is located at the northern portion of the site, <br /> • occupied by the City of Stockton-Fire Prevention Department The properties surrounding the site <br /> are mostly industrial, with a few residences east of the site <br />' A diesel/gasoline fueling system previously occupied the northwestern portion of the site, a <br /> petroleum hydrocarbons release from the associated underground storage tanks(USTs)is presently <br /> being remediated by procedures outlined in Design Plans and Specifications For Soil and <br /> Groundwater Remediation, prepared by ATC Associates Inc (ATC) and approved by the San <br /> Joaquin County Environmental Health Department (EHD) by letter dated 03 January 2001 <br /> 12 SITE REMEDIATION PROGRESS <br /> A soil vapor extraction/in-situ air sparging (SVE/IAS) system was installed during August and <br /> September 2001 Soil vapor monitoring and sampling events,groundwater sampling events and the <br /> results of laboratory analysis of the samples collected have been documented in subsequent quarterly <br /> monitoring reports The operation of the IAS system has produced only minor volatilization of the <br /> dissolved hydrocarbons in the deep ground water well samples at the site(VW-2D),but has reduced <br /> the dissolved hydrocarbon concentration in the shallow well samples (MW-1 and VW-1)as well as <br /> the concentrations of hydrocarbons in the soil vapor extraction (SVE) influent to below detection <br /> levels Subsequently, AGE had proposed to augment the IAS system with a low-flow ozone <br /> generator in the work plan dated 28 January 2003 Operation of the ozone injection system has been <br /> ongoing since July 2003, resulting in a general downward concentration trend <br /> Advanced GeoEnvlronmental,Inc <br />