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}
<br /> ATC Associates Inc
<br /> (:
<br /> VYJ%Tc
<br /> 1117 Lone Palin Avenue, Suite B
<br /> Modesto, California 95351
<br /> 209-579-2221
<br /> • a s s 0 c i A r e s i N c fax 209-579-2225
<br /> concentrations of petroleum hydrocarbons remained at the south and southeastern portion of the
<br /> excavation
<br /> On February 26, 1993, Parker Environmental Semces (P E S )advanced seven soil borings (BH l through
<br /> BH7) Soil samples were collected from each boring and a groundwater sample was collected from each
<br /> boring except BH7 Petroleum hydrocarbons were detected m soil samples collected from all the borings
<br /> except BHI and BH3 Petroleum hydrocarbons were detected in all of the groundwater samples Water
<br /> levels measured at the site on March 2, 1993, mdicated the groundwater flow direction was to the
<br /> southeast Refer to P E S 's Interim Report on Subsurface Investigation Work at Cheaper' 9 37 dated
<br /> April 20, 1993 for more details
<br /> From July to October 1995, P E S conducted subsurface investigation achvmes that included mstallmg
<br /> four monitoring wells (MW5 through MW8) 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, B 10
<br /> through B18, B20, B21, and MW5 through MW7 A groundwater sample was also collected from MW8
<br /> Petrol hydrocarbons were detected all of the soil samples except for the samples collected from
<br /> a� .eM MWIhrough m MW7, B 14 located east of the former UST location,and B20 and B21 located off-site to the
<br /> �• southwest and south, respectively Petroleum hydrocarbons were detected in the groundwater samples
<br /> except the samples collected from B14, B20, B21, MWl, MW2, MW3, MW6, and MW7 MW4 was not
<br /> sampled due to the presence of approximately 0 02 inches of free product The reported groundwater flow
<br /> direcbon on September 25, 1995, was approximately due north Refer to the report prepared by P E S
<br /> titled Environmental Site Investigation Methods and Findings Drilling of Soil Borings, DnIhng and
<br /> Installation of Groundwater Monitoring Wells Collection and Analyses of Soil and Groundwater
<br /> 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 upgradrent momtonng 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 refine the lateral and vertical extent of soil contamination In response to the EHD request,
<br /> H20GEOL submitted the Work Plan for Additional Soil Characterization dated June 10, 2003, which
<br /> proposed advancing 14 hand auger borings at the site for the purpose of collecting soil samples
<br /> On September I I and 12, 2003, a 500-gallon rapacity used oil UST was excavated and removed from the
<br /> site by Walton Engineering, Inc Petroleum hydrocarbons and metals were detected in a soil sample
<br /> collected frorn below the former location of the UST from a depth of approximately seven feet bgs Refer to
<br /> Grayland Envrronmental's Underground Storage Tank and Fuel Dispenser Removal Report, dated
<br /> October 16, 2003, for more information
<br /> In September 23 and 24, 2003, H20GEOL collected groundwater samples from MWl and MW4 through
<br /> MW8 Petroleum hydrocarbons were detected in groundwater samples collected from these wells The
<br /> reported groundwater flow direction was to the north Refer to H20GEOL's Third Quarter, 2003
<br /> Groundwater Monitoring Report, dated October 31, 2003, for more information
<br /> •i In a letter dated November 14, 2003, the EHD rnudicated that the proposed scope m the H2OGEOL
<br /> workplan was not adequate or necessary The EHD requested that a workplan be prepared in the context of
<br /> s'cnvuonxntiaU5847M374vpodsX4gr-2005 doe 2
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