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2 . 0 GROUNDWATER FLOW DIRECTION AND GRADIENT <br /> On November 30 and December 1, 1999, ASE associate geologist Ian Reed <br /> measured the depth to water in each site groundwater monitoring well <br /> using an electric water level sounder The surface of the groundwater was <br /> also checked for the presence of free-floating hydrocarbons or sheen <br /> using an oil/water interface probe and a product thickness bailer <br /> Monitoring well MW-5 contained 0 01-feet of free-floating hydrocarbons <br /> The free-floating hydrocarbons appeared yellow and is believed to be <br /> gasoline A hydrocarbon sheen was present on the groundwater surface <br /> in monitoring well MW-6 No free-floating hydrocarbons or sheen were <br /> observed in any other site monitoring well Groundwater elevation data is <br /> presented as Table One <br /> Due to the presence of free-floating hydrocarbons in monitoring wells <br /> MW-5 and MW-6, ASE began measuring the thickness of the free-floating <br /> hydrocarbons in these wells every two weeks ASE then removed any <br /> accumulated product in these wells with a bailer The free-floating <br /> hydrocarbon thickness measurements are tabulated in Table One <br /> Groundwater elevation (potentiometric surface) contours are plotted on <br /> Figures 2, 3 and 4 On November 30, 1999, groundwater in the shallow <br /> zone (less than 19-feet bgs) appeared to flow to the north/northwest <br /> beneath the site with a relatively flat gradient of approximately 0 0026- <br /> feet/foot This groundwater flow direction is generally consistent with <br /> previous findings (Figure 5) Potentiometric surface contours for t h e <br /> deeper zones (55 to 70-feet bgs and below 100-feet bgs) could not be <br /> plotted because three non-linear points for each zone are required for <br /> contouring However, since the potentiometric surface in monitoring well <br /> MW-7 is higher than the potentiometric surface in monitoring well MW-9 <br /> (both wells screened between 55 and 70-feet bgs) and since t h e <br /> potentiometric surface in monitoring well MW-8 is higher than t h e <br /> potentiometric surface in monitoring well MW-10 (both wells screened <br /> below 100-feet bgs), it appears that groundwater in these deeper zones <br /> may have a flow component to the south, probably being influenced by <br /> pumping from the on-site drinking water well In addition, there was a <br /> hydraulic head decrease with depth between monitoring wells MW-6, <br /> MW-7 and MW-8, all installed adjacent to each other and screened at <br /> different depths, suggesting downward groundwater flow This decreasing <br /> hydraulic head with depth relationship is also present in monitoring wells <br /> MW-9 and MW-10 installed adjacent to each other and screened at <br /> different depths Once again, this suggests that there is a downward <br />. component to groundwater flow probably related to pumping <br /> Frank's One Stop Quarterly Report -- December 1999 Sampling <br /> -2- <br />