ARCHIVED REPORTS_MONITORING WELL INSTALLATION AND BIOSPARGE EVALUATION REPORT

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3.0 EVALUATION OF BIOSPARGE REMEDY This remedial alternative involves the injection of air at controlled rates (2-4 SCFM) per well ' to different parts of the aquifer through injection wells. The addition of oxygen in the aquifer from the injected air enhances aerobic biodegradation. Factors to consider when implementing any type of bioremediation include characteristics of the contaminant, physical, ' and geochemical conditions of the aquifer. Prior to planning a pilot test for the Site, PSC evaluated corrective action pilot testing and operations at two neighboring sites. PSC reviewed pilot tests performed for the Transmission Store located at 515 West Charter Way (Figure 2) by their consultant Shaw Environmental and Infrastructure, Inc. In addition, progress reports for the air sparging and soil vapor ' extraction (AS/SVE) system operating at the former Dolly Madison, 1426 South Lincoln Street were reviewed for performance. The following sections 3.1 and 3.2 summarize the review of these remedies and their application. In addition, sampling and analysis for ' nutrients and microbes conducted during the June 2009 monitoring well installations on-site was also evaluated and is discussed in Section 3.3. 3.1 Review of the Transmission Store Pilot Test The transmission store originally selected biosparging as a remedy in a 2007 Feasibility Study/Remedial Evaluation (FS/RE). In July 2008, a two-day pilot test was conducted on ' sparge well SP-1 (screened 47-49 feet bgs). The test consisted of collecting baseline geochemistry data, a step rate test, and a constant rate test. The step rate test was conducted over 1.5 days with injection pressure stepped from 10 pounds per square inch gauge (psig) up to 40 psig. The constant rate test was conducted at 20 psig over a 4-hour period the second day. Down hole instruments in selected observation wells measured dissolved oxygen (DO), Oxidation Reduction Potential (ORP), conductivity, pH, temperature, and water level, ' throughout the test. Vapor pressure, oxygen levels, carbon dioxide, methane, and total volatile organic compounds (VOC) concentrations (using a hand held photo-ionization detector) were also recorded for the observation wells and soil vapor wells. ' Baseline testing indicated that geochemical conditions in the subsurface were conducive to bioremediation with the exception of dissolved oxygen levels, which on average were less ' than 2.0 mg/L. No significant increases in dissolved oxygen levels were observed during the pilot test. Therefore, the test was inconclusive regarding distribution of oxygen or of oxygen demand in the subsurface. One observation documented during the pilot test was an increase ' in water levels in adjacent wells at 15 prig. This increase diminished at higher pressures and Shaw concluded that the results indicated that hydraulic control would not be necessary. Shaw's overall conclusion of the pilot test was that the duration was too short to evaluate the effectiveness of the remedy. An extended pilot test with additional sparge and monitoring points was proposed. ' CVRWQCB reviewed the proposed extended pilot test and suggested that air sparging at higher pressures and flow rates be included in order to evaluate a possible AS/SVE remedy. Additional sparging and monitoring points were not approved. An extended air Monitoring Well Installation and Biosparge Evaluation Report Prepared For:Some Ice Bakery Group,Inc. Sara L13 Prepared By:PSC Industrial Outaouming,LP ee-Lincoln Street 2009_12_03-M W Installation&BioSparge Evaluation Report(Final).doc Report Date:December 3,2009