ARCHIVED REPORTS_MONITORING WELL INSTALLATION AND BIOSPARGE EVALUATION REPORT

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' sparging/biosparging treatability test was conducted by Shaw in March 2009. This test included additional baseline sampling, a biosparge test, an air sparge test, oxygen consumption monitoring, and follow-up groundwater sampling. The biosparge portion of the ' test was conducted at 20 psig for five days. The air-sparging portion was conducted at 45 psig over 10 days. The oxygen consumption was monitored for five days following the air- sparging test. The results of the biosparging test indicated an increase in oxygen to over 2.0 mg/L in one well, MW-8I. This well is located about 25 feet southeast of the sparge well SP-1 and is screened at 55-65 feet bgs, six to 16 feet lower than the sparge well. No significant increases ' in shallower and closer wells were observed. Shaw concluded that this indicated a preferential pathway to the permeable zone or to the screened interval in well MW-8I. ' Overall, Shaw concluded that the biosparging remedy would not be effective at the site. Based on soil vapor concentrations, Shaw concluded that AS/SVE would be an effective remedy for the site. The CVRWQCB agreed with this conclusion and recommendation. A ' Corrective Action Plan (CAP) was submitted in August 2009. The CVRWQCB conditionally approved the CAP on September 29, 2009. Documentation of the construction of the remediation system has not been uploaded to GeoTracker as of the preparation of this Report. Based on the review of the documents for the pilot testing, PSC agrees that the biosparge test was not conducted long enough, especially at the lower injection pressures. Given a static ' water level of 18.9 feet bgs and the top of the screen for the sparge well at 47 feet bgs, the breakthrough pressure for the sparge well would have been 12.64 psig. The injection pressure for biosparging should have been maintained at 5 to 10 psig over the breakthrough pressure ' until pressure stabilized. This may take a number of days. The flow rate should have also been recorded during the test. The maximum breakout pressure of injected air in a sparge well this deep is estimated to be 34.3 psig. This pressure was exceeded by 11 psig during the ' second day of testing,potentially resulting in the establishment of preferential flow channels. The duration of the biosparge portion of the second test was longer at 72 hours. However, the test was conducted at a rate of 20 psig. Obvious "hydraulic connectivity" was observed ' between the sparge well and MW-8I during this test. This may have been the result of fracturing the permeable zone and development of preferential pathways during the first test. The majority of the remainder of the second test was conducted at pressures exceeding the maximum pressure that should have been applied. ' 3.2 Review of the Dolly Madison Air Sparging/Soil Vapor Extraction Test Pilot testing at the former Dolly Madison site was completed with the evaluation of the AS/SVE remedy. Stratus Environmental Inc. selected this technology based on the success of AS/SVE as a source removal remedy at the former Texaco and Arco sites. The system was installed in May 2009 and consisted of soil vapor well VW-1 through VW-6 installed with the well screen from 5 to 25 feet bgs. The vapor wells are connected to a thermal oxidizer for ' treatment of contaminated soil vapors. The air sparge portion of the system includes 4 sparge wells with screens at 30 to 32.5 feet bgs. The sparge wells are connected to an oil-less compressor. Monitoring Well Installation and BioSparge Evaluation Report ' Prepared For.Sere Lee Bakery Group,Inc. 14 Prepared By:PSC Industrial Outsourcing,LP Sara Lee—Lincoln Street 2009_1203-MW Installation&BioSparge Evaluation Report(Final).dcc Report Date:December 3,2009