ARCHIVED REPORTS_3RD QUARTER 2010 SITE STATUS REMEDIAL SUMMARY AND GROUNDWATER MONITORING REPORT

Home Browse Search

stantec t L & M OPERABLE UNIT-THIRD QUARTER 2010 SITE STATUS, REMEDIAL SUMMARY, AND GROUNDWATER MONITORING REPORT Groundwater Monitoring and Sampling ' October 27, 2010 Validation issues with report number 73872: ' Matrix Spike and MSD results associated with samples MW-54 and MW-65 for the analyte MtBE were outside of the stated QC limits. This may indicate a possible bias for the reporting ' accuracy. The RPD values are within range indicating precision in reporting. The LCS recoveries were within QC limits indicating accuracy in reporting. Therefore, the reported values are considered valid. ' 2.6 THIRD QUARTER 2010 D-ZONE GROUNDWATER RESULTS ' 2.6.1 D-Zone Groundwater Gradient Data D-Zone groundwater elevations at the Site ranged from 7.37 ft below MSL in well MW-71 to ' 7.02 ft below MSL in well MW-72 (Table 3 and Figure 24). Groundwater flow direction during the third quarter 2010 was observed in two sections of the site (northeast and northwest). Along the northeastern portion of the site, groundwater flow direction was to the northeast with an approximate hydraulic gradient of 0.0009 ft/ft. In the northwest portion of the site, groundwater flow direction was to the northwest with an approximate hydraulic gradient of 0.0003 ft/ft (Figure 24). The highest D-Zone groundwater elevation (7.02 ft below MSL) was reported in well MW-72, located in the southeast corner of the L&M OU site behind the remediation system. Historical groundwater flow direction and gradient data are summarized in Table 8, and vertical gradients summarized in Table 9. The D-Zone groundwater elevation contour map for the July ' 19, 2010 monitoring event is included as Figure 24. 2.6.2 D-Zone Groundwater Quality Data ' During the third quarter 2010, groundwater samples were collected from eight D-Zone wells between July 19 and 22, 2010 (Table 1). Groundwater analytical results are presented in Tables 4 through 7, and summarized below. TPHg, TPHd, TPHo, benzene, MtBE, and TBA isoconcentration contour maps are included as Figures 25 through 30, respectively. The certified laboratory analytical reports for the groundwater sampling event conducted for the L&M tOU are included in Appendix C. 2.6.2.1 Separate Phase Hydrocarbons ' During the third quarter 2010, measurable SPH or SPH-sheen was not observed in any D-Zone wells. h ide ateATWStoWon(Parcel 2A{1415)\Repons\QMRT010ZQ10\3Q10QSSRQRSRQMRSIockbn_FINALtloc 2.15