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xA 4' v�M h a. 1.4 - SITE INVESTIGATION REPORT GEWEKE LODI PROPERTY Brown and Caldwell (BC) was retained by Gewel:e Properties to conduct a site investigation on their property in Lodi, California. The Geweke Lodi property is located near the w corner of Oak Street and Cherokee Lane. The purpose of the investigation was to determine the source of hydrocarbon contamination found in soils and groundwater beneath the site. The presence of hydrocarbans was detected by previous investigations conducted by J. H. Kleinfelder & Associates (JHK) . - The site is a former Gas-N--Save gasoline station. Four underground storage tanks had been previously removed from t the site (Figure 1 ) . No soils samples were taken from the e:zcavations during tank removal. According to previous reports x by JHK, a San Joaquin County (County) representative on site during excavatioai did not note hydrocarbons in the excavated soil. Geweke Properties was directed by the County to conduct a site investigation to determine if hydrocarbons were present in the soil. due to possible leakage from a 1,000-gallon waste oil tank (Figure 1 ) . JHK drilled four boreholes and installed monitoring wells, MW-1 through MW-4 as shown on Figure 1 , to roughly 60 feet deep which they completed with 2-inch ID PVC casing and screen. During drilling, soil samples were selectively taken to be analyied for benzene, toluene and xylene (BTX) , and total petroleum hydrocarbons (TPH) . Groundwater samples were taken from each of the four wells and analyzed for the same constituents. Two soil samples, one from 40 feet in MW-3 and one from 40 feet in MW-4 showed detectable levels of BTX and TPH . Soils lags of MW-2 through MW-4 indicated no gasoline odor down to 40 feet. Below 40 feet to the total depth of each hole, gasoline odor was present. The soils log of MW-1 indicates gasoline odor noted to roughly 25 feet and no odor detected from 25 to 58 feet. However, positive photoionization detector readings were obtained throughout the borehole interval. Soils and groundwater analysis for MW-1 were either nondetectable or very low for BTX or TPH. BC Site Investigation BC met with a representative from the County Environmental Health Division and the California Regional Water Quality Control Board, Central Valley Region (Regional Board) , to discuss the JHK investigations and follow-up work at the site. - - A work plan was agreed upon, and a description of the BC work is included herein.