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Air Sparging Pilot Test Related Activities Report and Remedial Action Work Plan Former Countryside Market, Stockton, California April 30, 2015 were monitored for air and helium injection flow rates, pressure, and temperature using the rotameters, pressure gauges, and temperature gauges installed on the AS manifold. Background soil vapor samples were collected from OBS-1 and VW-1 for laboratory analysis on January 19, 2015 prior to the start of injection. Soil vapor samples were also collected from OBS-1 and VW-1 for laboratory analysis at the end of each AS test. Background groundwater samples (low-flow purge) were collected from OBS-1, AS-1, and AS-2 for laboratory analysis on January 13, 2015 prior to the start of injection. Low-flow purge groundwater samples were also collected from OBS-1, AS-1, and AS-2 for laboratory analysis after the final test. All groundwater samples were submitted to a State-certified laboratory for analysis. The field monitoring data (tabulated) collected during the test is provided as Appendix I. Raw data collected by the data loggers is provided as Appendix J. The laboratory reports and COC documents from the soil vapor and groundwater samples are provided as Appendix E. 4.4 AS-1 Testing Discussion and Results 4.4.1 Breakthrough Testing (AS-1 Testing) After conducting pre-test sampling and monitoring/shakedown of the equipment, initial breakthrough testing was started (January 27, 201 at approximately 11:00 AM) by initiating air flow into AS well AS-1. Injection air pressure was incrementally increased to determine the minimum pressure required to displace the groundwater above the top of the screened interval and induce measurable airflow into the sparge well (min). Estimated Breakthrough Pressure: Grnin (psi) = 0.4 (psi/foot) x Water Column above Top of Screen (feet) Breakthrough pressure was observed between 9 and 12 pounds per square inch gauge pressure (psig). This pressure is greater than the estimated breakthrough pressure, and below the overburden pressure of the formation. The overburden pressure (Gmax ) represents the upper limit for injected air pressure and is calculated as follows assuming a dry soil density of 100 pounds per cubic foot: Gmax (psi) = 0.7 (psi/foot) x Total Depth (feet)(base of screen) 4.4.2 Injection Flow (AS-1 Testing) Once breakthrough testing was completed, SGI conducted "low-flow", "medium-flow", and "high- flow" steps to evaluate the feasibility of air sparging within a range of flows. During low-flow testing, the injection flow rate was maintained at approximately 5 scfm at an average pressure of 8 psig. During medium-flow testing, the injection flow rate was maintained at approximately 10 scfm at an average pressure of 10 psig. During high-flow testing, the injection flow rate was maintained at approximately 20 scfm at an average of 13 psig. Air injection at AS-1 was conducted for a total of 4-4 The Source Group, Inc.