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ARCADIS Site Investigation Work Plan 401 North San,lose Street,Stockton,California One soil sample was analyzed from each boring,at depths ranging from 4 to 12 ft bgs.A grab groundwater sample was collected from each boring.At least one of the analytes was detected in both soil and groundwater in eight out of the 10 locations. The data Indicate an absence of soil or groundwater impacts in the western portionof the Site.TPHg,TPHd, TPHmo,and BTEX were reportedly detected in soil and groundwater samples collected from the central and eastern portion of the Site.The highest TPHg and TPHd concentrations were reportedly measured In soil from boring GP-9,located on the eastem half of the property,at 1,690 milligrams per kilogram(mg/kg)and 939 mg/kg, respectively.The highest concentration of TPHg in groundwater(1,090 milligrams per liter [mg/Ll)was observed at boring location GP-8,which is approximately 504eet north of boring location GP-9. The highest concentration of TPHd in groundwater(124 mg/L)was reportedly observed at boring location GP-9.The highest concentrations of TPHmo In soil and groundwater were reportedly observed In boring GP-3. Based on Arcadis'review of these data, It appears that BTEX detections were correlated with TPHg detections. Reported benzene concentrations in groundwater ranged from 2.6 to 4.0 mg/L In the eastern portion of the Site. Methyl tertiary-butyl ether(MTBE)was not analyzed In soil or groundwater, The lateral extent of TPHg and TPHd In groundwater in 2001 was defined to the west of the central part of the Site by the absence of these compounds In boring locations GP-1,GP-2,and GP-3.The lateral extent of TPHg and TPHd was not defined toward the northern,eastem,and southern boundaries of the Site. Likewise,the vertical extent of TPHg and TPHd at the Site has not been defined. Groundwater was encountered at a depth of 12 ft bgs; the total depth of the borings was 16 ft bgs. Consequently,groundwater characterization Is limited to the top 4 ft of groundwater, from approximately 12 to16ftbgs. 3. Proposed Scope of Work ARCADIS proposes the following investigation activities: • Geophysical Survey • Cone Penetration Testing(CPT)with Laser Induced Fluorescence(LIF) • Groundwater monitoring well Installation and sampling • Soil sampling 3