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15 June 2009 <br /> AGE-NC Project No.05-1306 <br /> Page 22 of 33 <br /> of eight rounds)with a U statistic of 0.0 and 6.0 respectively. Results from 11 June 2002 through <br /> 19 March 2008 (in three separate groupings of eight rounds each group) indicate "no trend" at the <br /> 90 percent confidence level for all three data sets regarding TPH-g and regarding TPH-d for two data <br /> sets covering 03 June 2004 to 27 February 2006 and 11 May 2006 to 19 March 2008. For the most <br /> recent group of eight rounds,the results indicate"decreasing"at the 90 percent confidence level with <br /> respect to TPH-d(29 May 2007 to 05 March 2009). The U statistic relative to TPH-d ranges from <br /> 2.0 to 12.0 and relative to TPH-g ranges from 6.0 to 8.5.It should be noted that to maintain quarterly <br /> groupings of results to conform to the test requirements,the second group of eight rounds required <br /> removal of the June 2002 and December 2004 sampling event and the final grouping of eight rounds <br /> includes an overlap of four rounds from 29 May 2007 to 19 March 2008. Historically, TPH-g was <br /> only detected a total of six times, so most values were entered as zeros. Xylenes have only been <br /> detected a two times dating back to 2000 so statistical tests were not run concerning these <br /> constituents. Constituents that have never been detected historically include benzene, toluene, and <br /> ethylbenzene. <br /> Test results for MW-5 indicate an "increasing" trend at the 90 percent confidence level for TPH-d <br /> when considering results from 30 August 2004 through 11 May 2006 (first group of eight rounds) <br /> with a U statistic of 16.0. It should be noted that even though there is an increasing trend indicated <br /> over this time period,the highest detection for TPH-d was 100 µg11(20 May 2005)which meets the <br /> objective reported in the California Environmental Protection Agency Regional Water Quality <br /> t Control Board Central Valley Region Appendix A - Reports Tri-Regional Board Staff <br /> Recommendations For Preliminary Investigation and Evaluation of Underground TankSites(Table <br /> 1), dated 16 April 2004. Results from 11 May 2006 through 19 March 2008 indicate "no trend" at <br /> the 90 percent confidence level for TPH-d with a U statistic of 4.5. Results from 30 August 2004 <br /> through 11 May 2006 (includes an overlap of one round) indicate "no trend" at the 90 percent <br /> confidence level for TPH-d with a U statistic of 16.Historically,TPH-g and BTEX constituents have <br /> not been detected in this well. <br /> Test results for MW-6 indicate "no trend" at the 90 percent confidence level for TPH-d when <br /> considering results from 13 July 2000 through 19 March 2008. This time period represents two <br /> groups of eight rounds with a U statistic at 4.5 and 9.0 respectively. This represents three groupings <br /> of eight rounds with the final grouping of eight rounds with a U statistic of 4.0 to 8.0. Constituents <br /> j that have never been detected historically include TPH-g and BTEX. TPH-d has only been detected <br /> a total of three times including 03 June 2004 (170 µg11), 22 November 2005 (110 µg/1), and <br /> 21 August 2006 (60 gg/l) and has not been detected in the last six rounds of sampling. <br /> Test results for MW-7 indicate "no trend" at the 90 percent confidence level for TPH-d when <br /> considering results from 03 June 2004 through 19 March 2008. This time period represents two <br /> groups of eight rounds with a U statistic at 4.5 and 9.0 respectively. The final grouping of eight <br /> rte. rounds includes an overlap of four rounds from 29 May 2007 to 19 March 2008 and indicates an 4 <br /> Advanced GeoEnvir"nmental,Inc. <br /> 1 <br />