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I <br /> Quarterly Monitoring Report - Third Quarter 2002 <br /> • 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 in Figure 1 Structures and well <br />' locations associated with the site are depicted in Figure 2 <br /> This report documents soil vapor sampling events on 17 July and 20 August 2002 and a ground <br /> I water monitoring event on 30 August 2002, and presents the results of laboratory analysis of soil- <br /> vapor and ground water samples <br />' 2.0. PROCEDURES <br />' Field procedures for soil-vapor and ground water sampling are described below All field work was <br /> performed in accordance with Central Valley Regional Water Quality Control Board(CVRWQCB) <br /> guidelines for the investigation of underground storage tank(UST)sites Soil-vapor extraction and <br />' . in-situ air sparging monitoring were performed in accordance with procedures outlined in the ATC <br /> Associates Inc (ATC)-prepared Design Plans and Specifications For Soil and Groundwater <br /> Remediation, as approved by the San Joaquin County Environmental Health Department(EHD)by <br />' letter dated 03 January 2001 <br /> I2 1 SOIL-VAPOR EXTRACTION MONITORING <br />' A soil vapor extraction/in-situ air spargmg system (IAS/SVE) has been in operation since <br /> October 2001 The system was monitored monthly and inspected or maintained weekly during <br /> operation During each monitoring event, measurement of the SVE flow rate, vacuum (potential), <br />' concentrations of hydrocarbons in the extracted soil-vapor and collection of a set of soil-vapor <br /> samples were conducted by AGE personnel <br />' The flow rate of extracted soil-vapor(influent) was measured using a direct measure flow meter, a <br /> magnehelic vacuum gauge was used to measure the vacuum potential at the 2-mch influence line <br /> The organic vapor concentrations in the extracted soil-vapor stream was measured before entering <br />' the blower (influent stream) and after exiting the carbon units (effluent stream) using an organic <br /> vapor meter(OVM)equipped with a photo-ionization detector PID(Thermo Environmental 580B, <br /> 10 OeV, calibrated to isobutylene 100 ppb) Field measurements, recorded at regular intervals <br />' between June and August 2002, are summarized in Table 1 <br /> i <br /> IAdvanced GcoEnvironmental,Inc <br />