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Advanced <br /> Inc . <br /> GeoEnvironmental, ---- ' <br /> 18 May 2001 <br /> AGE-NC Project No. 97-0326 <br /> Ms. Margaret Lagorio, Supervisor <br /> SAN JOAQUIN COUNTY PHS-EHD <br /> 304 East Weber Avenue, 3rd Floor <br /> Stockton, CA 95201 <br /> Subject: Work Plan Addendum- May 2001 <br /> K& S Gas & Grocery <br /> 701 East Charter Way, Stockton, California <br /> Dear Ms. Lagorio: <br /> At the request of Mr.Khaldoon Othman of K&S Gas&Grocery,Advanced GeoEnvironmental,Inc. <br /> (AGE)has prepared this work plan addendum for additional assessment of hydrocarbon-impacted <br /> soil and ground water at and near 701 East Charter Way, Stockton, California. The scope of work <br /> includes acquiring and analyzing additional geotechnical information(continuous lithologic record <br /> from CPT data for definition of hydrologic units) as well as soil and grab ground water samples at <br /> two proposed locations,the UST area and on the west side of Stanislaus Street for delineation of the <br /> extent of impacted ground water prior to the installation of up to seven additional ground water <br /> monitoring wells as proposed in the October 2000 work plan addendum. <br /> BACKGROUND <br /> AGE submitted Work Plan Addendum - 19 October 2000 that included: 1) acquisition of three <br /> continuous lithologic records from CPT borings and grab ground water and soil samples from three <br /> paired soil borings,and 2)subsequently installation of up to seven monitoring wells whose locations <br /> would be based on laboratory results from the new borings. On 14 and 15 February 2001 four <br /> borings (two CPTs and two paired soil borings) were advanced to 100 feet bsg at the K & S site; <br /> petroleum-hydrocarbons odor was detected in ground water samples collected at 100 feet,indicating <br /> that the vertical zone of impacted groundwater had not yet been determined. The third CPT and the <br /> third paired soil boring were advanced at an off-site location across Charter Way. The borings were <br /> terminated at a total depth of 122 feet bsg after encountering refusal; the grab water sample <br /> recovered at 122 feet was also impacted. Neither the vertical nor the horizontal extent of impacted <br /> ground water had been determined at that time. <br /> Ground water occurred at a depth of approximately 31 feet below surface grade (bsg) during the <br /> March 2001 quarterly monitoring event; historical ground water depths based on the San Joaquin <br /> County Flood Control District ground water maps from 1971 to 1999 range from 40 to 70 feet bsg. <br /> Total petroleum hydrocarbons quantified as gasoline(TPH-g)was detected at concentrations as high <br /> as 160,000 µg/1 in water samples collected from the wells. <br /> 837 Shaw Road,Stockton,California 95215 <br /> Telephone (209) 467-1006 FAX(209) 467-1118 <br />