Laserfiche WebLink
• <br /> Quart-rly Ground-Water Monitoring January 8. 1990 <br /> Beacon Station No. 502, Lodi, California AGS 86091-7 <br /> FIELD PROCEDURES <br /> ubiective Analysis of Mgnitoring 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, or other subjective evidence of hydrocarbon contamination. <br /> ' Measu e e t of the QeIRth Jo Ground Water itt Monitoring_Wells <br /> The depth of the ground-water surface in a monitoring well is measured from the top of <br /> I <br /> he well casing to the nearest 0.01 foot with a Solinst water-level indicator. <br /> Purging-and Samplin or N o it r' ells <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 ground-water 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-millititer glass vials that contain <br /> concentrated hydrochloric acid as a preservative. The vials are filled completely, thereby <br /> eliminating headspace. Labels are affixed to the vials, which show the site identification <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: <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. 'fie field geo-)gist <br /> initiates a Chain of Custody Record listing each sample number, the site identification <br /> dumber, and the date sampled. This record will accompany the samples to the analytical <br /> laboratory. <br /> _f <br />