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Mr. W. Michael Carroll, PE Project 124601 <br /> June 7, 2010 <br /> Page 3 of 4 <br /> • First Quarter 2010 Groundwater Contour Map - Between fourth quarter 2009 and first <br /> quarter 2010 the groundwater levels recovered approximately 1 to 3 feet, with the <br /> greatest degree of rise on the down gradient side of the site. However, because there <br /> was not a significant difference between up gradient well G-1 and down gradient <br /> wells G-5 and G-31), an apparent U-shaped groundwater feature developed across <br /> the site. The direction of groundwater flow during this quarter could still generally <br /> be reported as to the west, with a flow component from the northern portion of the <br /> landfill towards G-2 and another component of flow to the south. Therefore, G-2 is <br /> down gradient of the landfill during this quarter. <br /> • Second Quarter 2010 Groundwater Contour Map - Between first and second quarters <br /> of 2010 the groundwater levels continued to uniformly recover approximately 2 feet <br /> across the site. The direction of groundwater flow during this quarter could still <br /> generally to the west, with a relatively steeper flow component from the northern <br /> portion of the landfill towards G-2 and shallower component of flow to the south. <br /> Therefore, G-2 is down gradient of the landfill during this quarter. <br /> Based this review of the water level data from G-2, it is apparent that G-2 is down gradient <br /> from the northern portion of the landfill during most of the recent monitoring events. Based <br /> on this information, and is in an appropriate location for groundwater monitoring. <br /> Conclusion <br /> Monitoring well G-2 appears to be in serviceable condition and appropriately located for <br /> groundwater monitoring. Shaw recommends that the County consider adding G-2 to the <br /> monitoring network for water quality sampling. Because of the relatively deep water level <br /> at G-2, a dedicated sampling pump should be installed to facilitate sampling if this well were <br /> put into service as a monitoring point. A sampling pumping can be installed in this well in <br /> time for the next semiannual monitoring event in third quarter 2010. <br /> If you have any questions,please call me at(916) 565-4361. <br /> Sincerely, <br /> SHAW ENVIRONMENTAL, INC. <br /> Dan Eas er,PG,CEG <br /> Project Manager <br /> Carrell NCLF G-2.d- <br />