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18 October 2013 <br />AGE Project No. 99-0559 <br />Page 4 of 5 <br />TPH-g were detected in the effluent of the air stripper during the July and September 2013 <br />sampling event; while MTBE and TBA were detected in the effluent of the air stripper <br />during the third quarter 2013 (September) at concentrations of 12 pg/I and 290 pg/I, <br />respectively. <br />Petroleum (BTEX) and fuel additives were not detected at the effluent samples collected <br />during the quarter. <br />Analytical results of pump-and-treat influent and effluent water samples are summarized <br />in Tables 1 and 2. <br />CTEL laboratory reports (CTEL Project Nos. 1307133, 1308129, 1309122) with quality <br />assurance/quality control (QA/QC) reports and chain-of-custody forms, are included in <br />Appendix B. GeoTracker confirmation numbers of the submitted laboratory electronic <br />deliverable format (EDF) files are 3583774626, 9112212419 and 3013172209. <br />2.5. MASS-VOLUME REMOVAL CALCULATIONS <br />Between 21 June 2013 and 25 September 2013, the groundwater extraction system <br />recovered an estimated total of 83.2 lbs of TPH-g, 3.3 lbs of benzene and 1.4 lbs of MTBE. <br />Since May 2003 a total of 13,625.3 lbs of TPH-g, 783.3 lbs of benzene and 1,321.4 lbs of <br />MTBE have been extracted from groundwater. The volumetric calculations from the <br />groundwater pump-and-treat system are presented in Appendix C. <br />3.0. SUMMARY AND CONCLUSIONS <br />Based on data collected during the monitoring event, AGE concludes: <br />Between June and September 2013, the highest concentrations of petroleum <br />hydrocarbons were detected in extracted groundwater from wells EW-1 and lesser <br />at wells EW-2/EW-4, surrounding the former UST area and dispensers and <br />downgradient. <br />MTBE concentrations in extracted groundwater continue to decrease or fluctuate <br />to a stable concentration near 2,000 pg/I, after decreasing significantly in 2012, with <br />the exception of EW-2; however, MTBE concentrations increased during the third <br />quarter 2013 in influent samples collected from EW-1. Trends of the extraction rates <br />for MTBE are depicted in Appendix E. <br />Advanced GeoEnvironmental, Inc.