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Quarterly Monitoring Report - Second Quarter 2002 <br /> FIRE STATION #2 <br /> 110 West Sonora Street, Stockton, California <br /> 1.0. INTRODUCTION AND SCOPE OF WORK <br /> I 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 /> Ilocations associated with the site are depicted in Figure 2 <br /> This report documents soil vapor sampling events on 12 March, 16 April, 13 May and 11 June 2002 <br /> and a ground water monitoring event on 03 May 2002,and presents the results of laboratory analysis <br /> of soil-vapor and ground water samples <br /> I2.0. PROCEDURES <br /> All field work was performed in accordance with Central Valley Regional Water Quality Control <br /> Board(CVRWQCB)guidelines for the investigation of underground storage tank(UST)sites Soil- <br /> vapor extraction and in-situ air sparging monitoring were performed in accordance with procedures <br /> outlined in the ATC Associates Inc (ATC)-prepared Design Plans and Specifications For Soil and <br /> Groundwater Remediation, as approved by the San Joaquin County Environmental Health <br /> Department (EHD) by letter dated 03 January 2001 <br /> Field procedures for soil-vapor and ground water sampling are described below <br /> I <br /> 21 SOIL-VAPOR EXTRACTION MONITORING <br /> A soil vapor extraction/in-situ air spargmg system (IAS/SVE)has been in operation since October <br /> 2001 The system was monitored monthly and inspected or maintained weekly during operation <br /> 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-inch 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 580A, <br /> 10 OeV, calibrated to isobutylene 100 ppb) Field measurements, recorded at regular intervals <br /> between 1 I October 2001 and 11 June 2002, are summarized in Table 1 <br /> IAdvanced GeoEnvuonmental,inc <br /> I <br />