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► ATC Associates Inc
<br /> ., M%TC
<br /> r 1117 Lone Palm Avenue, Suite B
<br /> Modesto, California 95351
<br /> 209-579-2221
<br /> fax 209-579-2225
<br /> ASSOCIATES INC
<br /> On February 26, 1993, Parker Environmental Services (P E S ) advanced seven soil borings (BH 1
<br /> through BH7) Soil samples were collected from each boring and a groundwater sample was collected
<br /> from each boring except BH7 Petroleum hydrocarbons were detected in soil samples collected from all
<br /> the borings except BH 1 and BH3 Petroleum hydrocarbons were detected in all of the groundwater
<br /> samples Water levels measured at the site on March 2, 1993, indicated the groundwater flow direction
<br /> was to the southeast Refer to P E S 's Interim Report on Subsurface Investigation Work at Cheapen #37
<br /> dated April 20, 1993 for more details
<br /> From July to October 1995, P E S conducted subsurface investigation activities that included installing
<br /> four monitoring wells (MW5 through MWS) and advancing 14 hand augured soil borings (138 through
<br /> B21) B15 through B21 were advanced off-site to the west, southwest, and south Groundwater was
<br /> encountered at approximately 6 5 feet bgs Soil and groundwater samples were collected from B8, 1310
<br /> through B18, B20, B21, and MWS through MW7 A groundwater sample was also collected from MWS
<br /> Petrol um hydrocarbons were detected in all of the soil samples except for the samples collected from
<br /> 4* MWAhrough MW7, B14 located east of the former UST location, and B20 and B21 located off-site to
<br /> Q \1� the southwest and south, respectively Petroleum hydrocarbons were detected to the groundwater
<br /> samples except the samples collected from B14, B20, B21, MW1, MW2,MW3, MW6, and MW7 MW4
<br /> was not sampled due to the presence of approximately 0 02 inches of free product The reported
<br /> groundwater flow direction on September 25, 1995, was approximately due north Refer to the report
<br /> prepared by P E S titled Environmental Site ,Investigation Methods and Findings Drilling of Soil
<br /> Borings, Drilling and Installation of Groundwater Monitoring Wells Collection and Analyses of Soil and
<br /> • Groundwater Samples, dated November 17, 1995 for more information
<br /> In a letter dated April 11, 2002, the San Joaquin County Environmental Health Department (EHD)
<br /> indicated that upgradient monitoring wells MW2 and MW3 could be reduced to annual monitoring and
<br /> that the lateral and vertical extent of soil contamination remains undefined The EHD requested submittal
<br /> of a workplan to define the lateral and vertical extent of soil contamination In response to the EHD
<br /> request, H2OGEOL submitted the Work Plan for Additional Soil Characterization dated June 10, 2003,
<br /> which proposed advancing 14 hand auger borings at the site for the purpose of collecting soil samples
<br /> On September 11 and 12, 2003, a 500-gallon used oil UST was excavated and removed from the site by
<br /> Walton Engineering, Inc Petroleum hydrocarbons and metals were detected in a soil sample collected
<br /> base of the UST from a depth of approximately seven feet bgs Refer to Grayland Environmental's
<br /> Underground Storage Tank and Fuel Dispenser Removal Report, dated October 16, 2003, for more,-
<br /> information
<br /> ore,-
<br /> information
<br /> In September 23 and 24, 2003, H2OGEOL collected groundwater samples from MW I and MW4 through
<br /> MWS Petroleum hydrocarbons were detected in groundwater samples collected from these wells The
<br /> reported groundwater flow direction was to the north Refer to H2OGEOL's Third Quarter, 2003
<br /> Groundwater Monitoring Report, dated October 31, 2003, for more information
<br /> In a letter dated November 14, 2003, the EHD indicated that the proposed scope in the 142OGEOL
<br /> workplan was not adequate or necessary The EHD requested that a workplan be prepared in the context
<br /> of a site conceptual model that includes analytical data collected during removal of a waste oil tank from
<br /> 0 the site in September 2003 The requested workplan was submitted by ATC on February 2, 2004
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