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Ms. Connie Davis/Aggregate Industries - F Street October 2001 QMR Project Number 100(018 PnRncoN November ]6, 2001 Page 6 northerly component east of the spill area. The hydraulic gradient was estimated to range from approximately 0.009 to 0.02 for the overall site while the hydraulic gradient was estimated to range from approximately 0.002 to 0.006 for the spill area. The groundwater flow directions and hydraulic gradients estimated for October 2001 are similar to previous observations at the site. 3. BTEX and TEPH concentrations were not observed above the laboratory detection limits in the groundwater samples collected from wells MW-I through MW-5 and EW-1 on October 18, 2001. 4. BTEX concentrations observed in the groundwater samples collected from the site during October 2001 did not exceed the MCLs. 5. BTEX and TEPH concentrations were not observed above the laboratory detection limits in the surface water sample collected from the North Dewatering Trench on October l8, 2001. 6. The benzene, toluene and ethylbenzene concentrations observed in the surface water sample collected from the North Dewatering Trench on October 18, 2001 did not exceed the Surface Water Standards. The following recommendations are made based on information obtained during the quarterly sampling activities. 1. The quarterly monitoring program should be continued for two (2) additional sampling episodes as recommended in the October 9, 2001 SCR. 2. If BTEX concentrations remain below the MCLs for the next two (2) quarterly sampling episodes, a request for site closure should be submitted to the DMG. 7. GENERAL COMMENTS Th.e analyses and opinions expressed in this report are based on data obtained from the groundwater monitoring wells installed at the indicated locations along with other information described in this report. This report does not reflect any variations in subsurface geohydrology or contaminant distribution which may occur between wells and or across the site. Actual subsurface conditions may vary and may not become evident without further exploration. Due to the dynamic nature of groundwater flow and contaminant migration, subsurface conditions will vary with time.