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TABLE 1 Second Quarter 1993 Monitor Well Physical Parameter Data Summary ' San Joaquin County Human Services Building Site Sample Date: June 3 and 4, 1993 ' Well Well Elevation' Depth to Groundwatce Groundwater Temperature' pH3 Electncal Conductivity ID (feet) (feet) Elevation' (feet) (°F) (umhos) ' MW-4 13 46 4990 -3644 67 1 77 1326 MW-5 1283 4806 -35 23 769 76 938 MW-6 13 17 49 13 -3596 682 74-- 1710 ' MW-7 13 14 5088 -3774 68 1 87 1601 MW-8 1376 5133 -3757 666 74 1257 I 1 Elevations are given in feet relative to Mean Sea Level (MSL) and are based upon measurements from top of PVC casing (TOC) 2 Measured from TOC 3 Measured at end of purge ' 4 MW-2 and MW-3 were dry 2.2 Chemical Analysis Summary ' Concurrent with the measurement of the physical parameters, groundwater samples were collected and analyzed for the following parameters by the methods referenced • Benzene, toluene, ethylbenzene and xylene (BTEX), EPA Method 602 • Total petroleum hydrocarbons as gasoline (TPH-G), Method 8015M ' 0 Total petroleum hydrocarbons as diesel (TPH-D), Method 8015M • Ethylene dlbromlde (EDB) (also known as 1,2-dlbromoethane), EPA Method 504 • Total lead, EPA Method 239 2 IThe chemical analytical results for the second quarter 1993 monitoring event are summarized in Table 2 while the complete analytical report is presented in Appendix B ' BTEX concentrations were all below the laboratory detection limit (ND) except for low concentrations of benzene 1n MW-4 at 3 µg/L and MW-7 at 1.5 µg/L. TPH-G was detected in only two wells at concentrations similar to the previous first quarter results; MW-4 at 96 µg/L, IMW-8 at 2,200 µg/L. TPH-D and EDB concentrations were either ND or dust slightly above the detection limit, therefore, per the direction of the EHD, these analyses will be discontinued during future quarterly sampling Also, because total lead concentrations were detected at very low levels thought to represent background levels in groundwater, this analysis will also be discontinued during future sampling events IWith regard to the quality control samples, analysis of the primary well sample MW-4 and the blind duplicate (labeled MW-10) had analytical results of 96 µg/L and 120 respectively, indicating fair repeatability of the laboratory analyses Analysis of the field decontamination sample, which was collected after sampling MW-8, indicated that there was no detectable compounds remaining in the field equipment after completion of standard field decontamination procedures ' MIRVrswc 2ND WP 4 O?n6M