ARCHIVED REPORTS_MONITORING WELL INSTALLATION AND BIOSPARGE EVALUATION REPORT

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aquifer characteristics that may limit the effectiveness of the biosparge technology include the following: • Variable Permeability - Intrinsic permeability is the ability of the soil to transmit fluid, ' both gases and liquids. The permeability used in the USEPA decision tree as a criteria for biosparging to be regarded as effective is 10-9 cm2 (Fetter 1999). Saturated silts ' encountered in the shallow permeable zone, typically have intrinsic permeability of 10-10 to 10-12 cm2, Fetter 1999. Biosparging in these shallow soils is considered only marginally effective. Silty sand soils encountered in all four permeable zone have 1 intrinsic permeability's that range from 10-9to 10-11 cm2 (Fetter 1999). Biosparging in these soils may be effective. Sands and gravelly sands encountered in the "A", `B", and "C" permeable zones have intrinsic permeability's higher than 10-9 cm2 (Fetter 1999). Biosparging is considered generally effective in these soils. • Stratified soils - The Site geology consist of sand and silty sand layers in silt and clay. There is an obvious hydraulic connection between permeable layers. However, on a ' localized level, the less permeable silt and clay would limit flow of fluid both vertically and horizontally. The stratified nature of the soil limits the effectiveness of biosparging. However, it is PSC's opinion that the stratified soil limits the effectiveness of AS/SVE to a greater degree. Biosparging at the correct interval with appropriate flow rate and appropriate injection pressure would be effective. ' • Nutrient levels — Nitrogen (expressed as ammonia) and phosphorous are required by bacteria to support cell growth. Some nutrients, found in excessive amounts will suppress the metabolic rate. The USEPA guidance document recommends a carbon: ' nitrogen: phosphorous ratio of 100:10:1. Samples of the permeable silty sand and sand layers were collected during monitoring well installation for analysis of total organic carbon, nitrogen, phosphorous, and sulfate. Unfortunately, concentrations of ' nitrate, ammonia and ortho-phosphate were non-detect and the nutrient ratios could not be determined from soil samples. The samples submitted were CT-MW-9-87 (68.5-70'), CT-MW-9-120 (80-81.5'), and CT-MW-9-120 (115-116.5'). The data is ' summarized in Table 6. 3.5 Evaluation of Baseline Groundwater Conditions ' Some of the baseline groundwater conditions, such as temperature and pH are known to be within the acceptable ranges of the guidance document. Analysis of additional indicator parameters can be helpful in evaluating biosparging. However, the results of these indicator parameter analyses from inside a contaminant plume should be compared to suitable background. The following paragraphs discuss the ' 3.5.1 Dissolved Oxygen and Oxidation Reduction Potential CVRWQCB used DO as a criteria to evaluate the effectiveness of biosparging during the ' review of the biosparge pilot test for the Transmission Store. A criteria cited in the reviews was a DO concentration less than 2.0 mg/L indicating an anaerobic environment. USEPA Monitoring Well Installation and BioSparge Evaluation Report ' Prepared For:Sara Lee Bakery Group,Inc. 17 Prepared By:PSC Industrial Outsourcing,LP Sara Lee—Lincoln Street 20091203-MW Installation&BioSparge Evaluation Report(Final).doc Report Date:December 3,2009