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The Callahan fault, as noted, passes over 1000 feet to the west of the site, if it extends <br />that far north. The eastern side of the fault is the downside of the normal fault. There is <br />no surficial evidence that there is any faulting on site, east of the Callahan fault. <br />However, the hydrology of the three northern wells, especially the much higher water <br />levels in MW-3, is better explained by a secondary fault or faults creating a smear zone <br />that acts as a semi-permeable dam (creating a damming effect). <br />3.0 SCOPE OF WORK <br />The following subsections of this workplan presents tasks to install a new monitoring <br />well (MW) in the vicinity of existing MW-6. <br />3.1 Safety Plan Preparation and Implementation <br />The Site Specific Health & Safety Plan (HSP) employed will be the same as that used <br />during previous site evaluations with any warranted updates. The equipment used for <br />the sampling and drilling operation will be the same as used previously. Modifications <br />to the plan may be implemented upon the Direction of the Site Safety Officer or Project <br />Manager if there are any changes in the site or work conditions. <br />3.2 Permitting <br />Prior to the performance of field activities, CE will secure a permit from the San Joaquin <br />County Public Health Service Environmental Health Division. Installation of the <br />groundwater monitoring well (MW) will be in accord with applicable local and State of <br />California requirements. <br />3.3 Additional Monitoring Well (MW-6B) <br />One (1) monitoring well is proposed for construction west of existing well MW-6 to an <br />estimated depth of approximately 60-70 ft bgs. <br />Drilling Methodology <br />Based on the past drilling experience onsite and in consulting various drillers, drilling will <br />be performed by a high torque hollow stem auger. <br />MW-6B will be drilled with a continuous core that will be logged by the onsite geologist, <br />and the cores that are not used for chemical analyses, will be drummed, profiled and <br />disposed of. <br />The logs of the borehole and well construction, similar to those of the past wells <br />(included in the reports) will be included in the subsequent report. <br />Well Completion <br />A two-inch diameter Schedule 40 polyvinyl chloride (PVC) plastic, with sufficient screen <br />(0.010-inch slot) to span the groundwater-bearing zone will be installed in each boring. <br />CE Project No. 99R-4041 <br />Additional Monitoring Well Work Plan 3