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<br /> Laboratory Analysis
<br /> ' We submitted the groundwater samples from wells MW-1, MW-3 and GWX-1 to Moore Twining
<br /> Laboratories, Inc. (MTL), a California Department of Public Health-certified (CDPH) analytical
<br /> ' laboratory located in Fresno, California, for the analysis of TPHg following the United States
<br /> Environmental Protection Agency (EPA) Test Method 8015B. MTL also analyzed each sample for
<br /> BTEX, FOCs, 1,2-DCA, naphthalene and ethanol following EPA Test Method 8260B. We also
<br /> submitted groundwater samples from wells MW-1, MW-3 and GWX-1 to California Laboratory
<br /> ' Services (CLS), a CDPH-certified analytical laboratory located in Rancho Cordova, California, for the
<br /> analysis of CrVI following EPA Test Method 7199.
<br /> ' Groundwater Analytical Results
<br /> The laboratory reports and chain-of-custody documentation are in Appendix B.TPHg and BTEX were each
<br /> ' reported for the samples collected from wells MW-1, MW-3 and GWX-1, with TPHg concentrations of
<br /> 7,300, 1,200 and 210 µg/l, respectively. Benzene was reported at 500, 9.3 and 36 pg/I, respectively for the
<br /> three samples, and the reported toluene, ethylbenzene and total xylenes concentrations ranged from 2.2 µg/1
<br /> ' ethylbenzene (MW-3) to 403 pg/I total xylenes (MW-1). Naphthalene was reported at 56 and 3.0 µg/I
<br /> respectively, for samples MW-1 and MW-3. MTBE, ethanol, TAME, ETBE, DIPE, TBA and 1,2-DCA
<br /> were not reported at concentrations equal to or greater than their respective laboratory reporting limits(RLs)
<br /> ' for each of the samples analyzed. CrVI was reported at 10.0 µg/1 for the sample collected from well
<br /> GWX-l.The site-related groundwater data are summarized in Tables 1,2 and 3.
<br /> The field quality assurance/quality control (QA/QC) implemented for the October 2011 rebound
<br /> i ' monitoring included the collection of one duplicate groundwater sample and the submittal of a trip
<br /> blank. The duplicate sample was collected from MW-1 and labeled as MW-14, a non-existent
<br /> monitoring well. When comparing the results of primary sample MW-3 with its respective duplicate
<br /> sample (see Appendix B for MW-14 results), CrVI, FOCs, 1,2-DCA and ethanol were not reported at
<br /> concentrations equal to or greater than their respective RLs, and TPHg, BTEX and naphthalene were
<br /> each reported at similar concentrations [relative percent difference (RPD) < 25%] for both samples,
<br /> ' thus showing good repeatability for each of these analyses. None of the tested analytes were reported
<br /> equal to or greater than their respective laboratory RLs for the trip blank.
<br /> ' We also reviewed the QA/QC data provided with MTL's and CLS' analytical laboratory reports.
<br /> These data show acceptable surrogate recoveries and non-detect results for each of the method blanks
<br /> and acceptable recoveries and RPDs for each of the matrix spikes (MS), matrix spike duplicates
<br /> (MSDs) and laboratory control samples (LCS) except for the CrVI analyses MSD that had a recovery
<br /> greater than the upper limit of 125%. However, CLS states that the laboratory was in control because
<br /> the LCS was within acceptance limits. Based on the elevated MSD recovery,the CrVI result for sample
<br /> GWX-1 must be considered an estimated value with the potential to be less than the reported value.
<br /> ' Based on the field and laboratory QA/QC data, no additional qualification of the October 2011 data
<br /> presented herein is necessary, and the data are of sufficient quality for the purposes of this report.
<br /> ' FOURTH QUARTER — 2011 — NOVEMBER REBOUND MONITORING
<br /> Groundwater Level Measurements
<br /> tOn November 29, 2011, we measured the depth to groundwater in wells MW-1, MW-3 and GWX-1
<br /> using an electronic water level indicator. Groundwater was encountered at 26.76, 25.41 and 26.64 feet
<br /> ' below TOC in the three wells, respectively. A summary of the TOC elevations, depth to groundwater
<br /> measurements and groundwater elevations is presented in Table 1.
<br /> Project No.59183-06-03 -4- January 30,2012
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