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i <br /> c7co6gicat Technics Inc, <br /> i1 101 7A Street <br /> Modesto,California 95354 <br /> (209)522-4119/Fax(209)5224227 <br /> ' REPORT <br />' Groundwater Monitoring <br /> 1St Quarter 2003 <br />' Morita Brothers <br /> 814 E. Charter Way <br /> iStockton, CA <br /> Project No 724 2 <br />' May 15, 2003 <br /> EXECUTIVE SUMMARY <br /> This report summarizes the V Quarter 2003 round of groundwater monitoring and testing <br /> that occurred on March 13, 2003 The laboratory analyses indicate that six 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 20 feet below the water table <br />' The average groundwater elevation in the water table wells at the site was—20 71 feet mean <br /> sea level (msl) and this corresponds to approximately 36 feet below ground surface (bgs) <br />' Project historic low groundwater levels 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 water table <br /> wells MW-4 through MW-6 was S48°E at 0 0042 ft/ft for the March 13, 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 413 illustrates the historical intermediate aquifer gradients and the March 13 gradient <br /> that was calculated to be East at 0 0029 ft/ft <br />