ARCHIVED REPORTS_MONITORING WELL INSTALLATION AND BIOSPARGE EVALUATION REPORT

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Alkalinity can be used as a marker to identify groundwater from similar permeable zones. The results from the July 2009 samples collected from "A" and `B" zone wells are similar. More importantly elevated total alkalinity can be indicative of aerobic respiration, denitrification, iron reduction, or sulfate reduction. To demonstrate this as a trend for the Site, ' increases of alkalinity inside the contaminant plume compared to concentration outside the contaminant plume should be observed over time. Increases in electron acceptors competing with oxygen, such as nitrate, sulfate, manganese, and ferric iron can also indicate biodegradation when the contaminant plume becomes more anaerobic. Dissolved iron in the aquifer can also oxidize and cause ferric iron to reduce permeability. The concentration used in the USEPA decision tree is 10 mg/L. Samples for dissolved iron were collected during the third quarter 2009 groundwater-monitoring event. The reported values for dissolved iron was non-detect at <0.05 mg/L for sample CT-MW-8-87. Concentrations were much less than 10 mg/L for samples MW-7S, MW-71), VE-1, and CT-MW-9-120. ' No detectable concentration of the nutrients ammonia and orthophosphate were reported with the exception of 0.24 mg/L of ammonia in the sample from CT-MW-9-120. These results were similar to results collected from soil samples collected from the permeable zones. Nutrient enhancement may be required for implementation of the biosparge remedy. Total aerobic heterotrophs in groundwater samples ranged from 3 to 3000 cfu/ml. These results are expected, given the results observed in the soil samples. These results indicate that biosparging will be an effective remedy. ' 3.6 Summary of Site Baseline Conditions for Biosparging The subsurface conditions beneath the Site and the rest of the commingle plume appear to be conducive to implementation of biosparging. Contaminants at each site in the commingled plume consist of petroleum hydrocarbons (BTEX and TPH-g) from gasoline releases. The chemical structure, vapor pressure, and Henry's Law Constant of the contaminants are effectively treated by biosparging. The concentrations at each site are similar and are not high enough to be toxic to bacteria. Based on the bacteria plate counts of samples from the `B" and "C ' permeable zones, the saturated soils contain sufficient hydrocarbon degrading bacteria. The results of the plate counts of groundwater samples support the soil results. The nutrient analysis of soil and groundwater samples indicates that enhancements may need to be included. Dissolved Oxygen and ORP measurements indicate that biodegradation is already occurring. It appears that this respiration is driving the reactions towards reducing conditions. Additional electron acceptor analysis of samples collected inside and outside the contaminant plume is needed for this assessment. Injection of air into the subsurface should move these reactions more towards aerobic biodegradation. This is dependent on the ability to inject air ' at a suitable pressure and flow rate in the permeable zones. Monitoring Well Installation and BioSparge Evaluation Repon ' Prepared For:Sate Lee Bakery Group,Inc. 19 Prepared By:PSC Industrial Outsourcing,LP Sats Lee—Lincoln Stree12009_12_03-MW Installation&BioSparge Evaluation Report(FnalLdoc Report Data:December 3,2009