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Quarterly Ground-Water Monitoring January 8, 1990 <br /> Beason Station No. `02. Lodi. California AGS 86091-7 <br /> FIELD PROCED1LMES <br /> Subjective Analysis of Monitoring I'Vells <br /> Ground-water samples -,-re collected for subjective analysis from the air-fluid interface in <br /> a monitoring well by lowering approximately half the length of a clean Tefluii :sailer s <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 Water in Monitoring Wells <br /> The depth of the groundwater 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. F <br /> f-� <br /> Purging and Sam lin of Monitoring Wells <br /> Before sample collection, a minimum-of 4 casing volumes of ground water is purged from <br /> each monitoring well using an electric submersible pump. The volume must be_-utzicient <br /> to produce stable temperature, pH, and conductivity measurements on field instruments. <br /> After the well is allowed to recover to static levels, a ground-water sample is collected by <br /> `a " ' 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 that contain <br /> concentrated hydrochloric acid as a preservative. The vials are flied completely, thereby It <br /> eliminating headspace, Labels are affixed to the vials, which show the site identification ' t <br /> number, the date and time of sample collection, the preservative used, and the sample <br /> identification number. The format of the identification number is:. ' 4. <br /> W-d-MWx W = water <br /> d = depth 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 listing each sample dumber, the site identification <br /> number, and the date sampled. This record will accompany the samples to the analytical <br /> { <br /> laboratory. <br /> i4pplred aeosysems <br /> t <br /> • <br /> E <br />