ARCHIVED REPORTS_GROUNDWATER MONITORING AND PROGRESS REPORT 4TH QUARTER 2011

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1 Well Purging and Sampling ' We used a portable I2-volt submersible pump to extract approximately three casing volumes of groundwater(69 to 97 gallons) from wells MW-1, MW-3 and GWX-1. We decontaminated the pump; ' monitored the extracted water for pH, electrical conductivity and temperature; and placed the extracted groundwater in five DOT-approved drums as previously described. Copies of the Monitoring Well Sampling Data sheets are in Appendix A. Following well purging, we collected and packaged a groundwater sample from each well as previously described. ' Laboratory Analysis ' We submitted the groundwater samples from wells MW-1, MW-3 and GWX-1 to MTL for the analysis of TPHg following EPA Test Method 8015B; and BTEX, FOCs, 1,2-DCA, naphthalene and ethanol following EPA Test Method 8260B. We also submitted groundwater samples from wells MW-I, ' MW-3 and GWX-1 to CLS for the analysis of CrVI following EPA Test Method 7199. Groundwater Analytical Results ' The laboratory reports and chain-of-custody documentation are in Appendix B. TPHg, BTEX and naphthalene were each reported for the samples collected from wells MW-1, MW-3 and GWX-1, with TPHg concentrations of 5,900, 1,100 and 190 pg/l, respectively. Benzene was reported at 510, 6.0 and 27 µg/I, respectively for the three samples, and the reported toluene, ethylbenzene and total xylenes concentrations ranged from 1.8 pg/l toluene (MW-3) to 400 µg/1 total xylenes (MW-1). Naphthalene was reported at 72, 6.0 and 4.1 µg/1 respectively, for samples MW-1, MW-3 and GWX-1. MTBE, ' ethanol, TAME, ETBE, DIPE, TBA and 1,2-DCA were not reported at concentrations equal to or greater than their respective laboratory RLs for each of the samples analyzed. CrVI was reported at 4.1 µg/I for well GWX-1. The site-related groundwater data are summarized in Tables 1, 2 and 3. ' The field QA/QC implemented for the November 2012 rebound monitoring included the collection of one duplicate groundwater sample and the submittal of a trip blank. The duplicate sample was collected from MW-3 and labeled as MW-14, a non-existent monitoring well. When comparing the results of primary sample MW-1 with its respective duplicate sample(see Appendix B for MW-14 results), CrVI, FOCs, 1,2-DCA and ethanol were not reported at concentrations equal to or greater than their ' respective RLs, and TPHg, BTEX and naphthalene were each reported at similar concentrations (RPD<25%) for both samples, thus showing good repeatability for each of these analyses. None of the tested analytes were reported equal to or greater than their respective laboratory RLs for the trip blank. ' We also reviewed the QA/QC data provided with MTL's and CLS' analytical laboratory reports. These data show acceptable surrogate recoveries and non-detect results for each of the method blanks and acceptable recoveries and RPDs for each of the MS, MSDs and LCS except for the CrVI analyses MS ' and MSDs that had recoveries less than the lower limit of 75%. However, CLS states that the laboratory was in control because the LCS was within acceptance limits. Based on the low MS/MSD recoveries,the CrVI result for sample GWX-1 must be considered an estimated value with the potential ' to be greater than the reported value. Based on the field and laboratory QA/QC data, no additional qualification of the November 2011 data presented herein is necessary, and the data are of sufficient quality for the purposes of this report. 1 Project No.59183-06-03 -5 - January 30,2012