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QUARTERLY GROUNDWATER MONITORING PROGRAM EAST BAY MUNICIPAL UTILITY DISTRICT THIRD QUARTER 1992 1.0 INTRODUCTION ' As required b San Joaquin Count Environmental Health Division's (the Count ) letter dated �l Y q Y Y March 27, 1992 issued to East Bay Municipal Utility District (EBMUD), seven monitor wells ' located at the EBMUD Stockton Center facility in Stockton, California (Figure 1) are to be tested quarterly The testing includes sampling of the groundwater in the wells and chemical ' analysis for Benzene, Toluene, Ethylbenzene, Xylene (BTEX, EPA Method 8020), Total Petroleum Hydrocarbons as gasoline (TPH-G, Method 8015-M) and Soluble Lead (EPA Method 239 2) 2.0 GROUNDWATER MONITORING SUMMARY ' The monitoring program consisted of two aspects 1) field measurement of physical parameters and 2) the collection and analysis of groundwater samples for specific analytes Sampling of all seven monitor wells (MW-1 through MW-7) was completed on October 2, 1992 The locations of these wells are shown in Figure 2 Two wells, MW-5 and MW-6, which had asphaltic material in and around the well casings during the second quarter 1992 monitoring event were cleaned and re-developed prior to the third quarter sampling Two quality control samples were also collected One sample (coded MW-8) was collected as a blind duplicate of the primary sample from MW-1 to evaluate analytical reproducibility and one sample (coded MW-9) was taken to evaluate field decontamination procedures A detailed description of field activities is ' presented in Appendix A 2.1 Physical Parameters Summary ' Field measurement of physical parameters included groundwater elevation, temperature, pH and electrical conductivity These data are presented in Table 1 ' 2.2 Chemical Analysis Summary ' Concurrent with the measurement of the physical parameters, groundwater samples were collected and analyzed for BTEX, TPH-G and soluble lead The resultant data is summarized in Table 2 and the complete analytical report is presented in Appendix B ' With regard to the quality control samples, the analysis of MW- (the primary isam le from ' monitor well MW-1) and the blind duplicate (labeled MW-8) had comparable analytical results indicating good repeatability of the laboratory analytical process Analytical results of the field decontamination sample, collected after sampling MW-1, indicated that there were no detectable ' compounds present in the field equipment after completion of a standard field decontamination procedure MMPTSTRMUD3RD WP 1 11!06192