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URS <br /> Ms.Margaret Lagorio, Supervising REHS Page 4 <br /> San Joaquin County Environmental Health Department <br /> October 11, 2004 <br /> WORKPLAN FOR ADDITIONAL ASSESSMENT <br /> Analytical data from the March 2004 investigation determined that the western extent of 1,2-DCA- <br /> impacted groundwater is not yet defined. In addition,during recent telephone conversations, SJCEHD <br /> reaffirmed their interest in defining/monitoring the eastern extent of impacted groundwater between the <br /> site and municipal well#1R. <br /> Based on current information,URS proposes the following: <br /> • Advance one vertical soil boring on Lodi Avenue west of the site and collect a grab sample to <br /> define the western extent of 1,2-DCA impacted groundwater. <br /> • Install one shallow groundwater monitoring well on the east side of Cherokee Lane between <br /> the site and the City of Lodi municipal well to monitor the eastern extent of impacted <br /> groundwater. <br /> i • Install one on-site deep groundwater monitoring well in the area reporting the highest 1,2-DCA <br /> concentration to assess the vertical extent of impacted groundwater. <br /> Presented below is a discussion of permitting; underground utility location; drilling and soil sampling; <br /> groundwater grab sampling; shallow and deep monitoring well installation; groundwater monitoring <br /> well development, sampling, and surveying; equipment decontamination and soil cutting and wastewater <br /> disposal procedures; and report preparation. <br /> Permitting <br /> The City of Lodi and SJCEHD require that soil boring permits be obtained prior to drilling.URS will <br /> submit the appropriate permit application(s) with fees to the City of Lodi and SJCEHD prior to <br /> conducting any field activities. <br /> Underground Utility Location <br /> All proposed drilling locations will be marked, and Underground Service Alert(USA)will be notified a <br /> _ minimum of 48 hours prior to commencement of any field activities for each phase of work. A private <br /> utility locator will also be contracted to survey proposed boring locations for private utilities prior to <br /> i commencement of field activities. In addition,the first 5 feet bgs in each boring will be cleared with an <br /> ± air or water knife to a diameter of 8.25 inches. <br /> Drilling and Soil Sampling <br /> Three vertical borings will be drilled using an HAS-equipped drill rig(see Figure 2 for locations). Two <br /> of the borings will be located off site and will be advanced to first encountered groundwater.A shallow <br /> 2-inch-diameter groundwater monitoring well will be constructed in one of the borings,and grab <br /> K:\WprocessU5 BP ARCO\00760\2004 Assessment\760 site assessment report with workplan V2 04.doc <br />