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• qe0togical Techala Inc. <br />110 1 7"' street <br />Modesto, California 95354 <br />(209) 522-4119 / Fax (209) 522-4227 <br />' REPORT <br />Groundwater Monitoring <br />' 4t` Quarter 2005 <br />Morita Brothers <br />814 E. Charter Way <br />Stockton, CA <br />Project No 724 2 <br />February 13, 2006 <br />I <br />EXECUTIVE SUMMARY <br />This report summarizes the 4`h Quarter 2005 round of groundwater monitoring and sampling <br />that occurred on November 23, 2005 The Iaboratory analyses indicate that ten of the <br />nineteen monitoring wells on this site remain impacted by gasoline range petroleum <br />' hydrocarbons The groundwater contamination plume appears to have migrated off site to the <br />east This is evident in Figure 6 <br />' The average elevation of groundwater in the water table wells at the site was --22 41 feet <br />below mean sea level which corresponds to approximately 37 feet below grade This <br />project's historic low groundwater Ievels in the early 1990's were 20 feet lower than the <br />' current level This is part of the problem with trapped residual hydrocarbons below <br />groundwater that act as a continuing source of groundwater contamination <br />Groundwater gradient calculations demonstrate that groundwater flow in the three -aquifer <br />horizons investigated, water table, intermediate and deep wells, flowed in a northeast to <br />easterly direction The historical groundwater gradients at this site consistently trend to the <br />east, ranging from northeast to southeast The vertical flow component of shallow <br />groundwater gradient was negative for all three well pairs monitored this quarter Well pairs <br />MW -4/104, MW -6/106 and MW-7/MW-107 exhibited downward flow for the November <br />2005 event <br />