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- <br /> Quarterly Ground-Water Monitoring January 22, 1990 <br /> Beacon Station No. 502, Lodi, California AGS 86091-7 <br /> FIELD PROCEDURES <br /> ifeasu;ement of the De th to round Water 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 /> Subiective Analysis of Monitoring Wells <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 Teflon bailer <br /> through the interface. The bailer is retrieved and the water sample examined for floating <br /> �- product, sheen, and other subjective evidence of hydrocarbon contamination. <br /> Pur in and am lin of Manitorin 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'sufficient <br /> to produce stable temperature, pH, and conductivity measurements on field instruments. <br /> After the well is allowed 'to recover to static levels, a groundwater sample is collected 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 that contain <br /> concentrated hydrochloric acid as a preservative. The vials are tilled so as to prevent <br /> headspace. Labels which show the site identification number, the date and time of sample <br /> collection, the preservative used, and the sample identification number are affixed to the <br /> vials. The format of the identification number is: <br /> W-d-MWx W = water <br /> d depth in feet <br /> MWx - monitoring-well number <br /> The samples are promptly stored in an ice chest with ice. The field geologist initiates a <br /> Chain of Custody Record listing each sample number, the site identification number, and <br /> the date sampled. This record will accompany the samples to the analytical laboratory. <br /> ApplIva' GOOSystems <br />