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1 <br /> 1 <br /> reduction, such as soil or water samples, does provide the best evidence for successful <br /> bioremediation or biostimulation <br /> 5.3 Volatile Halocarbon Contamination <br /> 1,2-Dichloroethane (1,2-DCA) was detected in samples from MW-13, MW-14 and EW-1 <br /> Since the March 1994 sampling, the concentration of 1,2-DCA has decreased sharply in EW- <br />' 1 and increased slightly in MW-13 and MW-14 <br /> The concentrations of 1,2-DCA are fluctuating similar to the petroleum hydrocarbon <br />' concentration As stated in the previous Quarterly Reports, the maximum contaminant level <br /> (MCL) for 1,2-DCA in drinking water is 0 0005 mg/l (ppm) The concentrations at the site <br /> continue to exceed those levels However, the source of the 1,2-DCA still remains uncertain <br />' No other HVOC's were detected in any of the samples <br /> 5.4 Soluble Lead <br />' No lead was detected in any of the samples and it does not appear that lead poses a <br /> potential threat to groundwater at this site All concentrations detected during the past year <br /> Ihave been below the MCL for lead, which is 0 05 mg/L <br /> 5.5 Recommendations <br /> wGeoAudit recommends that the next quarterly monitoring be scheduled for September 1994 <br /> Furthermore, we recommend that lead and all HVOC constituents other than 1,2- <br /> Dichloroethane, be discontinued from the sampling program in the C & A order These <br /> potential contaminants have not shown to be present in significant concentrations to justify <br />' quarterly sampling <br /> According to the schedule recently submitted to GLDM and the CVRWQCB, the full-scale <br /> inoculation of soil and groundwater at the site is set for early August 1994 The monitoring <br /> program submitted in the June 10, 1994 letter to the CVRWQCB, will be initiated upon <br /> full-scale inoculation Results of the monitoring will be included in future quarterly <br /> monitoring reports <br /> 6.0 LIMITATIONS <br /> Our professional services were performed using that degree of care and skill ordinarily <br /> exercised by environmental consultants practicing in this or similar localities The findings <br /> were based upon analytical results provided by an independent laboratory Evaluations of <br /> the geologic/hydrogeologic conditions at the site for the purpose of this investigation are <br /> made from a limited number of available data points (i a monitoring wells) and subsurface <br /> conditions may vary away from these data points No other warranty, expressed or implied, <br /> is made as to the professional recommendations contained in this report <br /> 16 <br /> I.33F69MCl WM QM4 <br /> I <br />