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Third Quarter 2000 Ground Water Monitornng Report Cleam� and Ahate�nent(hder No 5-00-7(}7 EAI Project No 1232 4.5 Investigation and Cleanup Activities Assessment A quarterly report summarizing the effectiveness of the air sparge/vapor extraction activities at ' the Wards site was previously submitted to the RWQCB on October 10, 2000 (see Section 1 1 4) A Work Plan outlining areas of the site that require additional investigation to assess the vertical and lateral extent of hydrocarbon impacted soil and ground water will be presented to the RWQCB by October 16, 2000 The Work Plan will also provide conclusions and recommendations for additional site assessment 46 Analytical Testing Results No MTBE, TBA, DIPE, ETBE, TAME, EDB, ethanol or methanol, above laboratory reporting limits, were detected in any of the ground water samples ' Methylene chloride was detected in seven ground water samples at concentrations ranging from 184 pg/L in well MW-11 to 14 2 pg/L, in well MW-19S This compound has not been detected ' during prior sampling events and is a common laboratory contaminant It is EAI's opinion that this compound may have originated from the laboratory Therefore, it was not included in Table 1 If future testing results indicate this compound is present in site ground water, this compound will be added to Table I Hydrocarbon concentrations in ground water are generally similar to the prior quarter testing results with three exceptions (MW-10, MW-10A, and MW-12) During recent sampling events, MW-10 and MW-10A had TPH-G and benzene concentrations below the laboratory detection limit However, during the September 2000 sampling event, MW-10 contained TPH- ' G and benzene at 121 pg/L and 11 4 pg/l, respectively Even higher concentrations of TPH-G (1,770 pg/L) and benzene (408 Vg/L) were detected in well MW-10A Well MW-12 had a significant decrease in hydrocarbon concentrations with all constituents below the laboratory ' detection limit However, these concentrations are similar to concentrations observed in this well in September 1998 (see Table 1) ' Data continue to indicate that the air sparging/vapor extraction system is effectively removing hydrocarbons from beneath the Wards site as a significant reduction in hydrocarbon concentrations in ground water has been observed since operation of the remediation system was initiated 4.7 Future Activities The next quarterly ground water monitoring for the site is scheduled for December 2000 A report documenting results of the ground water monitoring will be submitted to the RWQCB by January 15, 2001 BHM 1232ROO92 8 ENVIRONMENTAL AUDIT, INC