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Mr. W. Michael Carroll, PE Project 124601 <br /> June 7, 2010 <br /> Page 2 of 4 <br /> II. Is the location of this well appropriate? <br /> An appropriate location for it well is one that is down gradient from the landfill, so that <br /> monitoring of this well can indicate the impact to groundwater from the landfill, if any. <br /> Assessment of the location of the well in relation to the landfill and the groundwater <br /> gradient is complicated by the relatively flat hydraulic gradient in the aquifer at the landfill. <br /> Seasonal variations in depth to groundwater in the site wells are generally greater than the <br /> difference in elevations between wells during a monitoring event. Small seasonal <br /> inconsistencies in elevations between wells can, therefore, cause the estimated direction of <br /> groundwater flow to change noticeably. <br /> The water level at G-2 from the last six monitoring events (Ist quarter 2009 through 2nd <br /> quarter 2010) were added the previously prepared contour maps (attached). An assessment <br /> of the groundwater flow conditions at each monitoring event is as follows: <br /> • First Quarter 2009 Groundwater Contour Map — G-2 has the highest water elevation <br /> and is hydraulically up gradient of the landfill during this quarter. The direction of <br /> groundwater flow during this quarter is to the south. This is an unusual condition, <br /> but the early part of 2009 was dry and the hydraulic gradient across the site is <br /> shallow during this quarter. With a shallow hydraulic gradient across the site, small <br /> changes in water levels between wells can cause significant swings in the apparent <br /> direction of groundwater flow. Therefore, G-2 is not down gradient of the landfill <br /> during this quarter. <br /> • Second Quarter 2009 Groundwater Contour Map — Between first and second quarters <br /> of 2009 the groundwater levels recovered approximately 2 to 3 feet, which produced <br /> a 90-degree swing in the direction of groundwater flow. The direction of <br /> groundwater flow during this quarter is generally to the west, with a flow component <br /> from the northern portion of the landfill towards G-2. Therefore, G-2 is down <br /> gradient of the landfill during this quarter. <br /> • Third Quarter 2009 Groundwater Contour Map - Between second and third quarters of <br /> 2009 the groundwater levels fell approximately 3 to 4 feet. The direction of <br /> groundwater flow during this quarter is similar to last quarter and is generally to the <br /> west, with a flow component from the northern portion of the landfill towards G-2. <br /> Therefore, G-2 is down gradient of the landfill during this quarter. <br /> • Fourth Quarter 2009 Groundwater Contour Map - Between third and fourth quarters of <br /> 2009 the groundwater levels continued to fail. The greatest degree of fall was on the <br /> down gradient side of the site, which increased the gradient. The direction of <br /> groundwater flow during this quarter is similar to last quarter and is generally to the <br /> west, with a flow component from the northern portion of the landfill towards G-2. <br /> Therefore, G-2 is down gradient of the landfill during this quarter. <br /> Carroll NCLF G-2 dm <br />