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Certified analytical reports and chain-of-custody documentation are included in Appendix D and copies of the groundwater sampling field notes are included in Appendix E. The groundwater flow direction during the July 28, 2010 monitoring event was toward the north-northwest at a calculated hydraulic gradient of o.001 feet per foot. The north-northwest flow direction is generally consistent with the predominantly northeast trends observed historically. During the July 28, 2010 (semi-annual) sampling event TPH in the diesel range was reported in only one monitoring well (MW-5) at a concentration of 170 µg/L. In addition, 1,2-DCA was also detected in well MW-7 at a concentration of 3.3 µg/L. 1,2-DCA has been detected at low concentrations in well MW-7 over the last four sampling events and the concentrations have remained relatively consistent. However, 1,2-DCA has never been detected above the laboratory reporting limit in the other two Site wells. No other analytes tested were reported at concentrations above the laboratory reporting limit in any of the three monitoring wells sampled during the July 28, 2olo event. A TPH-d isoconcentration map is presented in Figure 7. The concentrations of TPH-d in all Site monitoring wells have decreased over the past four monitoring events. Historically, monitoring well MW-5 had the highest reported concentrations of TPH-d. Historical concentrations trends for TPH-d in wells MW-5 through MW-7 are shown in Graphs 1 through 3. TPH-d and TPH-mo concentrations spiked in well MW-5 during the second and third quarters Of 20o9 and in well MW-6 during the second quarter of 2009. However,the TPH-d and TPH-mo concentrations in those wells have since decreased.TPH-mo and TPH-g were not detected above applicable laboratory limits in any of the wells sampled during the July 29, 2010 monitoring event. TPH-d was only detected above the laboratory reporting limit in MW-5 at a concentration of 170 µg/L. The spikes in TPH-d and TPH-mo concentrations coincide with a slight increase in the groundwater elevations reported for those wells during the second quarter 2oo9. This increase in dissolved-phase concentrations and coincident increase in the local groundwater elevation could indicate the presence of some residual TPH-d and TPH-mo impacts to soils immediately above current water table elevation, within the capillary fringe. However, the water table elevation beneath the Site has since increased to a higher elevation than the second quarter 2oo9 event and the TPH-d and TPH-mo concentrations have not increased. This would indicate that residual soil impacts within the capillary fringe are limited in extent and concentration or may have been significantly reduced in concentration through natural attenuation. Historically,benzene had been detected in wells MW-5 and MW-6. However,benzene is not currently present and has not been detected above the laboratory limit in either well since February 2009. 1,2-DCA has been detected at low concentrations in well MW-7 over the last five sampling events and the concentrations have increased slightly with current concentrations at 3.3 µg/L. However, 1,2-DCA concentrations have consistently been below the 5 µg/L maximum contaminant level (MCL)for drinking water as provided by the California Environmental Protection Agency. Furthermore, 1,2-DCA has never been detected above the laboratory reporting limit in other Site monitoring wells.