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1 <br /> Geofogicaf Technks Inc. <br /> 2741 R,imr Raid <br /> Mafesta,Ca&farma 95351 <br /> (209)538-6424/faX#538-5852 <br /> 1 <br /> Work Plan <br /> 1 Additional Soil and Groundwater Investigation <br />' Valentine (Castle Motors) <br /> 2315 N. El Dorado St. <br /> Stockton, CA <br /> Project No 723 2 <br /> April 11, 2000 <br /> 1.0 INTRODUCTION <br /> t On October 4, 1999, Geological Technics Inc (GTI) submitted an Additional Site <br /> Characterization Report which documented the installation of a deep, discretely screened <br /> monitoring well and a deeper soil boring Analytical data shows the presence of gasoline <br /> range petroleum hydrocarbons an the soil and groundwater to a depth of at least 110 feet bgs <br /> On February 16, 2000, Mr Jeff Wong of SJC PHS/EHD issued a letter requesting that a work <br /> plan for the investigation of the lateral and vertical definition of the plume be submitted <br />' This work plan addresses that request <br />' 2.0 PROPOSED INVESTIGATION <br /> To investigate the lateral extent of soil and groundwater contamination, Geological Technics <br /> Inc proposes to drill ten (10) GeoProbe boreholes to a depth of approximately 30 feet and <br />' collect soil and groundwater samples as described below <br /> Quarterly groundwater monitoring of the existing 7 monitoring wells and the domestic well <br />' located at 60 E Castle Street as proposed for a one year period of time <br /> Further vertical investigation will be proposed after several additional quarters of <br /> groundwater monitoring have been completed As of this date, the deep monitoring well has <br /> been monitored for only two events and has shown a significant reduction of contamination <br /> from the first event to the second event It has been GTI's experience that groundwater <br /> samples from deep monitoring wells will often reach non-detect levels after four or five <br /> monitoring events Continued vertical exploration at the site will require the use of <br /> expensive drilling technologies, such as mud-rotary, due to the heaving sands Several <br /> quarters of monitoring the deep monitoring well would be prudent to determine if further <br /> vertical investigation as warranted <br />