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guidance documents use a DO level of less than 1.0 mg/L as the criteria of an anaerobic <br /> environment. DO levels can be misleading depending on the method of measurement. <br /> Samples collected during purging and inadvertently aerated would be biased high. <br /> ' Measurements taken with a probe down hole consume oxygen during measurement and can <br /> be biased low. Another process that complicates the measurement of dissolved oxygen is the <br /> effect that ongoing respiration from biodegradation has on measured levels. If petroleum <br /> hydrocarbons are degraded and oxygen is the electron acceptor, CO2 would be generated and <br /> the DO levels would decrease. Baseline DO levels should be used with caution <br /> ORP can also indicate oxidizing or reducing environments suitable for aerobic or anaerobic <br /> bacteria respectively. A negative number should indicate a reducing environment. Caution <br /> should also be applied to evaluation of ORP results due to the interactions of inorganic and <br /> organic compounds along with microbial byproducts. A summary of the DO, ORP, and <br /> ' TPH-g levels from July 2009 for the new and existing wells, as well as the Texaco wells on <br /> site are presented in the table below. <br /> ' Screen DO ORP TPH-g <br /> Well Interval Concentration* Measurement* Concentrations <br /> (b s) (m ) (mV) (m <br /> MW-1 26-46 1.90 -153.1 7,500 <br /> MW-lA 43-55 2.84 -152.9 230 <br /> ' MW-2A 40-50 0.71 -81.1 <50 <br /> MW-3A 44-50 2.70 -93.6 100 <br /> MW-4A 37-45 16.9 -104.9 50 <br /> MW-7S 55-63 1.32 -130.9 22,000 <br /> MW-71) 80-85 3.61 -140.5 600 <br /> VE-1 15-35 1.55 -65.8 100,000 <br /> CT-MW-8-87 77-87 0.59 -124.7 290 <br /> CT-MW-9-120 110-120 9.10 -111.4 85 <br /> TX-MW-8-50 40-50** 13.63 -73.6 <50 <br /> TX-MW-14-49 39-49** 0.95 70.1 <50 <br /> TX-MW-21-80 70-80 22.5 -225.7 2,800 <br /> * Measurements were made in a flow through cell during well purging in July 2009 <br /> ** Screen interval is assumed based on well ID. <br /> ' 3.5.2 Additional Groundwater Geochemistry <br /> In order to evaluate general aquifer geochemistry, competing electron acceptors, metabolic <br /> byproducts, indicators of biodegradation, and additional geochemistry parameters were <br /> analyzed in groundwater samples collected from selected wells. The results of the additional <br /> analyses are presented on Table 7. A summary of the additional analytical results are <br /> presented below. <br /> 1 Monitoring Well Installation <br /> and <br /> BioSparge Evaluation Report <br /> Prepared For:Sates Lee Bakery Group,Inc. is Prepared By:PSC Industrial Outsourcing,LP <br /> Sam Lee—Lincoln Street 2009_12_03-MW Installation&BioSparge Evaluation Report(Finap.doc Report Date:December 3,2009 <br />