SITE INFORMATION AND CORRESPONDENCE_FILE 1

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{ As requested in your e-mail, dated July 23, 2013, Stratus Environmental, Inc. (Stratus) has prepared the following evaluation and summary of the 5-day dual phase extraction (DPE) pilot test conducted at the subject site on April 29, through May 3, 2013 . A site map and tables summarizing the data collected during the pilot test are attached . The following is a brief summary of the DPE pilot test findings : • Due to various reasons (sewer discharge permit requirements, generator malfunction/repair, missed propane delivery by supplier, etc. ), the DPE pilot test operated for a total of 82.4 hours during the 5-day test. On the final day/night of the test, the system operated for approximately 18 . 6 hours continuously, extracting from two wells (IW-7 and IW-8). • An applied vacuum ranging from 22 to 22 . 5 "Hg resulted in extracted air flow rate of approximately 98. 2 cfm (total influent air flow rates ranged from 88 .4 to 98 . 7 cfm, though during most of the operation, the rate was 98. 2 cfm) . p • Negligible to no induced vacuum was observed in the network of observation wells when the system operated sporadically. However, when the system operated continuously for nearly a 24-hour period (the last day of the test) on extraction wells IW-7 and IW-8, induced vacuum was observed in observation well IW-9 up to 0 . 8-inches of water column . Given this observation, the induced vacuum ROI was at least 25 feet, which is the distance between wells IW-7 and IW-9 . i • A maximum groundwater level drawdown of approximately 0 .61 feet was measured in well IW-2 ( 13 feet from well MW- 10) during the initial DPE test on well MW40 . i Approximately 19,850 gallons of groundwater was generated during the test (total up-time was 82 .4 hours), and thus groundwater was extracted at a rate of approximately 4 gpm . • Concentrations of system influent GRO ranged from 71 mg/m3 to 380 mg/m3; these concentrations-are-inclusiv"f-dilutiorrair added-to the thermal oxidizer-and-thus-actual concentrations of contaminants extracted from the subsurface would be higher than the values reported from laboratory testing . • Influent concentrations of GRO, DRO, and benzene in groundwater ranged from < 50 mg/L to 1 ,700 mg/L, < 50 mg/L to 150 mg/L, and < 0 . 050 mg/L to 90 mg/L, respectively. Based on the results of the pilot testing, short-term DPE (30-days) appears to be a viable remedial alternative for reducing the amount of fuel contaminants remaining beneath the site. Pending concurrence from the San Joaquin County Environmental Health Department, Stratus will proceed with proceed with the implementation of a 30-day DPE event. If you have any questions or concerns, please contact me at (415) 516-0373 . Sincerely, Kasey L. Jones Senior Project Manager STRATUS ENVIRONMENTAL, INC. PH (415) 516-0373 2