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y <br /> i Ozone Sparging and Additional Monitoring Well Installation Work Plan <br /> FIRE STATION #2 <br /> 110 West Sonora Street, Stockton, California <br /> 1.0. INTRODUCTION <br /> At the request of the City of Stockton,Advanced GeoEnvironmental, Inc (AGE) has prepared the <br /> enclosed Ozone Sparging and Additional Monitoring Well Installation Work Plan for the <br /> unauthorized release of hydrocarbons from the common underground storage tank(UST)area at the <br /> north end of the property located at 110 West Sonora Street, Stockton, California (the site) The <br /> location of the site is illustrated on Figure 1 and a plan of the site is illustrated on Figure 2 <br /> This work plan was prepared in response to the San Joaquin County Environmental Health <br /> Department (EHD) letter, dated 01 May 2002 requesting additional vertical assessment of <br /> groundwater contamination(Appendix B) AGE proposes to install one depth-discrete groundwater <br /> monitoring well at the former UST location, screened from 65 to 70 feet below surface grade(bsg), <br /> the proposed well location is illustrated in Figures 2 In addition, the operation of the in-situ air <br /> sparing (IAS) system has produced only minor volatilization of the dissolved hydrocarbons in the <br /> ground water at the site, concentrations of hydrocarbons in the soil vapor extraction(SVE)influent <br /> have been reduced to levels below detection limits Therefore, AGE proposes to augment the in-situ <br /> . IAS system with a, low-flow, ozone generator <br /> Procedures outlined within this work plan are described in accordance with the California Regional <br /> Water Quality Control Board - Central Valley Region (CRWQCB-CR) guidelines for the <br /> investigation of UST sites <br /> 2.0. 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 diesellgasolme 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 EHD by <br /> letter dated 03 January 2001 <br /> A soil vapor extraction/in-situ air Sparging system was installed during August and September 2001 <br /> Soil vapor monitoring and sampling events, ground water sampling events and the results of <br /> . laboratory analysis of the samples collected have been documented in subsequent quarterly <br /> monitoring reports <br /> Advanced Geol:nvtmnmental,Inc <br />