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Ms. Lori Duncan ! <br /> San Joaquin County EHD I <br /> May 24, 2005 I <br /> Page 2 of 4 <br /> 1 k <br /> 11 <br /> hydrocarbons as gasoline (TPHI ); and total petroleum h drocarb� <br /> ons as diesel (TPH/d). <br /> Analysis of two wellhead vapor samples will be included on a semi-annual basis. <br /> GROUNDWATER MONITORING <br /> Quarterly groundwater monitoring will be completed in June, September, and December <br /> 2005; and March 2006. Monitoring well locations are shownll in attached Figure 1. <br /> Groundwater sampling will include up to twelve on-site wells (MW-9, MW-11, MW-12, <br /> MW 13, MW-14, MW-16, MW-19, MW-20, MW-24, MW-25, VM-1 and VM-2) and two <br /> QA/QC samples per event. Groundwater monitoring willjfinclude measurement of the <br /> depth-to-water in each well to prepare a groundwater elevation contour map of the site. <br /> From the groundwater contour map, the groundwater flow directio i and hydraulic gradient <br /> can be calculated. Groundwater purging of three well casing volumes will be completed <br /> prior;Ito sampling and p'H, conductivity, and temperature Iwill be measured after each. ' <br /> purg� <br /> Groundwater samples will be collected in laboratoryapproved containers using <br /> disposable bailers or dedicated sampling pumps and tubing and transported under chain- k <br /> of-cdstody for laboratory analysis. Electronic files of the water quality data in electronic <br /> deliverable format (EDF) will be uploaded to the State Water Resources Control Board <br /> (SW RCB), in accordance with §2729 and 2729.1 of Title 23, California Code of <br /> Regulations. Purge water generated during well purging will be containerized in properly <br /> lli <br /> abeled 55-gallon Department of Transportation (DOT) approved drums and stored on-site I <br /> i pending laboratory analyses. ' <br />} ANALYTICAL REQUIREMENTS <br /> Vapor and groundwater samples will be transported, to Advanced Technology <br /> Laboratories (ATL) in Signal Hill, California for analysis u"sing appropriate U.S. <br /> Environmental Protection Agency (USEPA) methodologies a ATLI�is certified through the <br /> California Department of Health Services Environmental Laboratory Accreditation <br /> Program, for the appropriate test methods. Two quai.ity assurance/quality control ' <br /> (QA/QC) samples, a travel and equipment blank, will be analyzed'with each groundwater <br /> event. Concentrations detected between maximum detection limitj( MDL) and the practical F <br /> quantitation limit (PQL) values will be reported with a "J"flag indicator. <br /> i <br /> Groundwater samples will be analyzed for BTEX, TPHg, TPHd, dissolved oxygen, <br /> oxidation/reduction potential, and ferrous iron. Sulfate `and nitrate analysis will be <br /> I:ICALTRANS\Stockton-Shop 1 MGW Monitoringli etter to SJ County_Final.doc i May 24,2005 <br /> Projectj No.940T.43148.00 l� SECOR Internationai Incorporated <br /> 1 P i <br /> i <br /> P i k <br />