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1 <br /> Ced6gccal 7-ec%iics Inc. <br /> ' 1 101 7'h Street <br /> Modesto,California 95354 <br /> (209)522-4119/Fax(209)522-4227 <br /> 1 <br /> REPORT <br />' Groundwater Monitoring <br /> 3" Quarter 2003 <br /> tMorita Brothers <br /> 814 E. Charter Way <br />' Stockton, CA <br /> Project No 724 2 <br />' November 17, 2003 <br /> EXECUTIVE SUMMARY <br /> This report su nmarizes the 3rd Quarter 2003 round of groundwater monitoring and testing <br /> that occurred on September 26, 2003 The laboratory analyses indicate that seven of the ten <br /> monitoring wells on this site remain impacted by gasoline range petroleum hydrocarbons <br />' The groundwater contamination plume appears to be migrating off site as evident from <br /> detection in well MW-106 The contamination is present in well MW-106 at a depth of <br /> approximately 18 feet below the water table <br /> The average groundwater elevation in the water table wells at the site was —22 80 feet mean <br /> sea level (ms]) and this corresponds to approximately 37 feet below ground surface (bgs) <br /> This project's historic low groundwater levels in the early 1990's were 20 feet lower than <br /> the current level This is part of the problem with trapped residual hydrocarbons below <br /> gioundwater that act as a continuing source of groundwater contamination <br />' Groundwater gradient calculations demonstrate that groundwater flow in the water <br /> g g table <br /> wells MW-4 through MW-6 was S66°E at 0 015 tt/ft for the September 26, 2003 event The <br /> rose diagram shown in Figure 4A indicates that the water table groundwater gradients at this <br /> site consistently trend east to southeast A rose diagram was also constructed for the <br /> intermediate aquifer monitored by wells MW-1, MW-2, MW-3, MW-106 and MW-107 <br /> Figure 4B illustrates the historical intermediate aquifer gradients and the September 2003 <br /> gradient that was calculated to be S84°E at 00014 ft/ft Vertical flow component of <br /> 1 <br /> 1 <br />