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1 <br /> FIELD PROCEDURES <br /> 1 <br /> Measurement of the Depth to Ground Water in Mowtoring Wells <br /> The depth of the ground-water surface in a monitonng well is measured from the top of the <br /> well casing to the nearest 0 01 foot with a Sohnst water-level indicator. <br /> i <br /> Subjective Analysis of Ground-Water <br /> Ground-water samples are collected for subjective analysis from the air-fluid interface in a <br /> monitoring well by lowering approximately half the length of a clean Teflon bailer through <br /> the interface The bailer is retrieved and the water sample is visually examined for floating <br /> 1 product, sheen, and other subjective evidence of hydrocarbons. <br /> Purging and Sampling of Monitoring Wells <br /> Before sample collection, a minimum of 3 borehole volumes of ground water is purged from <br /> each morutonng well using an electric submersible pump A sufficient volume is purged to <br /> allow temperature, pH, and conductivity of the purge water to stabilize After the water <br /> level in the well is allowed to recover to at least 80 percent of the initial level, a ground- <br /> water sample is collected by lowering a clean Teflon bailer past the air-water interface The <br /> bailer is retrieved, and the sample is slowly transferred to laboratory-cleaned, 40-mill1liter <br /> glass vials that contain concentrated hydrochloric acid as a preservative The vials are <br /> completely filled so as to prevent headspace The vials are labeled with the site <br /> identification number, the date and time of sample collection, the preservative used, and the <br /> sample identification number A Chain of Custody form is initiated that accompanies the <br /> sampies to the laboratory The samples are promptly placed in iced storage and delivered <br /> to a laboratory certified by the State of California. <br />