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4" <br /> OW M"' - <br /> r <br /> 10M,u ON <br /> _ <br /> 3r• r _ -- - <br /> .+xf2 <br /> a <br /> a 1 <br /> Quarterly Ground-Water Monitoring October 25, 1959 <br /> Beacon Station No. 502, Lodi, California AGS 86091-7 <br /> FIELD PROCEDURES <br /> $u bective Analysis of Monitoring Neils <br /> Ground-water samples are collected for subjective analysis from the air-fluid interface in <br /> a monitoring well by lowering approximately half the length of a clean Tenon bailer <br /> through the interface. The bailer is retrieved and the water sample examined for floating <br /> product, sheen, or other subjective evidence of hydrocarbon contamination. <br /> Measurement of the Depth to Ground Nater in Monitoring Wells <br /> The depth of the ground-water surface in a monitoring well is measured from the top of <br /> the well casing to the nearest 0.01-foot with a Solinst water-level indicator. <br /> Purging and Sampling of Monitorin Wells <br /> Before sample collection, a minimum of 4.casing volumes of groundwater is purg4r from <br /> each monitoring well using an electric submersible pump. The volume must be st,,fficient <br /> to produce stable temperature, pH, and conductivity measurements on field inst►,uments. <br /> After the well is allowed to recover to static levels, a ground-water sample is coll'_eted by <br /> :• lowering a clean Teflon bailer past the air-water interface. The bailer is retrieved:and the <br /> sample is slowly transferred to laboratory-cleaned 40-milliliter glass vials whic!i contain <br /> concentrated hydrochloric acid as a preservative. The vias are completely filled thereby <br /> eliminating headspace. Labels are affixed to the vials which show the site identificbtion <br /> number, the date and time of sample collection, the preservative used, and the sample <br /> idenlification number. The format of the identification number is: <br /> W-d-MWx W = water <br /> d = d4'-'.'n in feet <br /> MWx = monitoring well number. <br /> The samples are stored in an ice chest with ice to insure preservation. The field geologist <br /> initiates a Chain of Custody, Record Iisting each sample number, tF,;�]site identification <br /> number; and the date sampled. This record will accompany the samples to the analytical <br /> laboratory. <br /> APP/149d G'eOSVStiq <br /> 1)7S <br /> ,E <br />