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. Monitoring Well Installation Work Plan <br /> LANGSTON'S MARKET <br /> 15615 South 7" Street, Lathrop, California <br /> 1.0. INTRODUCTION <br /> At the request of Mr James Langston, Advanced GeoEnvironmental, Inc (AGE)has prepared the <br /> enclosed Monitoring Well Installation Work Plan for the Langston's Market location at 15615 South <br /> 7'h Street, Lathrop, California The purpose of the work is to further assess high concentrations of <br /> petroleum hydrocarbons discovered in ground water samples collected during a November 2002 site <br /> investigation The location of the site is illustrated on Figure 1 A plan of the site is illustrated on <br /> Figure 2 <br /> This work plan was prepared at the request of Mr Langston to expedite the site closure process,and <br /> was prepared in accordance with Central Valley Regional Water Quality Control Board (RWQCB) <br /> guidelines for the investigation of UST sites <br /> 2.0 BACKGROUND <br /> In June 1990 a 4,000-gallon gasoline UST failed and approximately 1,200 gallons of unleaded <br /> gasoline were released Between 1990 and 2000, 18 soil borings were advanced at the site for <br /> collection of soil and grab ground water samples, numerous side-wall samples were collected and <br /> analyzed during excavation activites and eight monitoring wells (including four destroyed original <br /> wells) were installed at the site <br /> In December 2000 four additional monitoring wells(MW-5 to MW-8)were installed by AGE Since <br /> AGE began quarterly ground water monitoring at the site in March 1999,the inferred ground water <br /> gradient has consistently been toward the northwest <br /> In November 2001, AGE advanced three soil borings (B5, B6 and B9) for collection of soil and <br /> ground water samples No analytes of concern were detected in the analyzed soil samples collected <br /> from the three borings However,high concentrations petroleum hydrocarbons were detected in the <br /> ground water sample collected from boring B9, located east of the former UST location, target <br /> analytes were not detected in ground water samples collected from borings B5 and B6,located at the <br /> former UST location and northwest of the former UST location, respectively <br /> Based on analytical results of ground water samples collected during quarterly monitoring and site <br /> assessment activities, the lateral extent of impacted ground water has been defined north (MW-4), <br /> south(MW-2, MW-7 and MW-8)and west(136)of the site However,the lateral extent of impacted <br /> ground water has not been defined east of the site <br /> Advanced GeoEnvironmental,Inc <br />