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r Quarterly Report - First t Quarter 2008 MANTECA CITY CORPORATION YARD 210 East Wetmore Street, Manteca, California 1.0. INTRODUCTION At the request of Mr. Frederic Clark of the City of Manteca, Advanced GeoEnvironmental, Inc. (AGE) has prepared this quarterly report for the property located at 210 East Wetmore Street, Manteca, California. This report documents the procedures and results of the quarterly monitoring and sampling of ten monitoring wells.The site and the surrounding area are illustrated on Figure 1. Structures and well locations are illustrated on Figure 2. 2.0. PROCEDURES Monitoring well sampling was performed in accordance with a San Joaquin County Environmental Health Department letter,dated 18 March 2008,under which wells MW-1,MW-2,MW-4, MW-5, MW-6, MW-9, and MW-10 are to be sampled on a quarterly basis and wells MW-3, MW-7, and MW-8 are to be sampled on a semi-annual basis for methyl tertiary-butyl ether (MTBE). On 25 March 2008, 10 ground water monitoring wells were monitored and sampled for MTBE (MW-1 through MW-10). The operation of the in-situ ozone was terminated for post remediation monitoring. Field work was performed in accordance with guidelines issued by the Central Valley Regional Water Quality Control Board for the investigation ofunderground storage tank(UST)sites. 2.1. WELL MONITORING AND PURGING On 25 March 2008,the depth to ground water in wells MW-1 through MW-10 was measured from the top of each well casing to the nearest 0.01-foot, utilizing a Solinst water level meter. Ground water elevation in each measured well was calculated by subtracting the measured depth to ground water from the surveyed casing elevation (Table 1). After water levels were measured, between approximately five and seven gallons of water (a minimum of 3 casing-water volumes per well) was purged from each of monitoring wells MW-1 I through MW-10, using dedicated, disposable plastic bailers. Ground water temperature, pH, and ! conductivity were measured at regular intervals during purging using an Oakton water analyzer. Field sheets and data are included in Appendix A. Purged water was containerized in properly labeled Department of Transportation(DOT)-approved 55-gallon drums and stored on-site. 2.2. COLLECTION OF GROUND WATER SAMPLES Water samples were collected from each purged well, using new, disposable plastic bailers after allowing the wells to achieve a minimum 80%recovery of the pre-purge water volume. Each water Advanced GeoEnvironmental,Inc.