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First Semiannual 20 f2 Groundwater Monitoring Report <br /> Former Texaco Service Station <br /> `r Chevron Site ID 309075 <br /> June 21, 2012 <br /> A summary of the site history and previous investigations is included in Attachment A. <br /> 3.0 GROUNDWATER MONITORING AND SAMPLING <br /> 3.1 Work Performed <br /> Gettler-Ryan Inc. (G-R) conducted semiannual groundwater monitoring and sampling on <br /> April 13, 2012. The groundwater monitoring and sampling program consists of water level <br /> elevation monitoring, sample collection, and chemical analysis of samples as described below. <br /> 3.2 Monitoring and Sampling Procedures <br /> G-R collected water level measurements on April 13, 2012 from the site monitoring well <br /> network, which consists of seven wells (MW-1, MW-2, MW-3, MW-4, MW-5, MW-6, and <br /> MW-6D, shown on Figure 2). <br /> G-R subsequently collected groundwater samples from each well in the site monitoring well <br /> network. Groundwater samples were collected in accordance with California Environmental <br /> Protection Agency (CaIEPA) procedures outlined in Representative Sampling of Groundwater <br /> for Hazardous Substances (CaIEPA Department of Toxic Substances Control 2008). <br /> An approximate three volume purging and sampling technique, using disposable bailers, was <br /> used for groundwater sample collection. Purging and sampling was performed using the <br /> following series of activities and protocols: <br /> • During the purge cycle, groundwater field parameter measurements consisting of <br /> specific conductance, pH and temperature were measured using a water quality meter <br /> • Approximately three times the volume of standing water. was removed from each <br /> monitoring well and field parameters were recorded on a well case volume basis <br /> • After the purge cycle was complete, a groundwater sample was collected for analysis <br /> with a disposable polyethylene bailer and transferred to the appropriate laboratory <br /> supplied sample containers prefilled with preservative; the water column was allowed to <br /> recharge to a minimum of 80 percent of its pre-purge elevation before a groundwater <br /> sample was collected <br /> Groundwater monitoring and sampling field data sheets are included in the G-R monitoring and <br /> sampling data package (Attachment B). <br /> g:\aproject\env\chevron\309075\6 deliverables\periodic monitoring\2012\1sa12\text\309075 1sa12 gmrfin 05212012.doc 2 tl <br />