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Date July 27,2005
<br /> Quarter 2°d Quarter,2005
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<br /> • ARCO QUARTERLY GROUNDWATER MONITORING REPORT
<br /> Facility No 2130
<br /> Address 7906 North EI Dorado Street, Stockton, CA
<br /> ARCO Environmental Engineer Paul Supple
<br /> Consulting Co/Contact Person URS/Vernon Elarth
<br /> Consultant Project No 38466468 OA 143
<br /> Primary Agency San Joaquin County Environmental Health Division
<br /> Assembly Bill 681 Status __Ero2erty owned by Atlantic Richfield Company
<br /> WORK PERFORMED THIS QUARTER (Second 2005):
<br /> 1 Performed quarterly groundwater monitoring and sampling from site wells VW-6 and VW-9 were not sampled
<br /> due to insufficient groundwater during this quarterly event
<br /> 2 Prepared and submitted quarterly groundwater monitoring report
<br /> 3 Continued to inject ambient air at low flow rates into well VW-10
<br /> WORK PROPOSED FOR NEXT QUARTER (Third 2005):
<br /> 1 Perform quarterly groundwater monitoring and sampling
<br /> 2 Prepare and submit quarterly groundwater monitoring report
<br /> 3 Continue bubbling of ambient air at low flow rates into well VW-10
<br /> QUARTERLY RESULTS SUMMARY (Second 2005):
<br /> Current Phase of Project Monitoring/Remediation
<br /> Frequency of Groundwater Sampling MW-1 through MW-7, and VW-1 through VW-12, MS-1A,
<br /> MS-1 B, MS-2A, MS-2B, MS-3A, and MS-3B sampled
<br /> quarterly
<br /> Frequency of Groundwater Monitoring Quarter)
<br /> Is Free Product (FP) Present onsite No
<br /> Current Remediation Techniques Natural attenuation/Air bubbling
<br /> Approximate Depth to Groundwater 40 99 to 43 22 feet below ground surface b s
<br /> Groundwater Flow and Gradient Northeast to Southeast @ 0 001 to 0 002 feet/foot ft/ft
<br /> ANALYTICAL DATA REVIEW:
<br /> Based on the review of the analytical and hardcopy data (chain-of-custody records, blanks,dilutions, holding times,
<br /> LCS/LCSD results,MS/MSD results,and surrogate recoveries),the data are acceptable as reported by the laboratory
<br /> with the following limitations
<br /> • The reported results for benzene in samples MW-3, MW-5, VW-2, VW-3, VW-5, VW-8, VW-10,
<br /> VW-11,VW-12,MS-IA,and MS-1B,ethylbenzene in samples VW-I,VW-3,VW-8,VW-l0,VW-11,
<br /> VW-12, and MS-IB, methyl tert-butyl ether (MtBE) in samples MW-1,MW-2,MW-5, VW-1,VW-3,
<br /> VW-5, VW-7,and VW-12,and gasoline range organics (GRO)in samples MW-6,VW-1,VW-2,VW-
<br /> 3, VW-4, VW-5, VW-7, VW-8, VW-10, VW-12,MS-IA, and MS-IB should be considered estimated
<br /> due to a high relative percent difference reported between the associated LCS and LCSD
<br /> K 1WpMess'J5 BP ARC0+021301Quaner1yV00512 QTR 0512130 GWMR 2Q05 do Page 1
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