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Some monitoring wells are expected to be evacuated to dryness after the removal of less <br /> than three casing volumes. These low-yield monitoring wells are allowed to recharge for <br /> up to 24 hours. Samples are collected as soon as the monitoring wells have recharged to <br /> a level sufficient for sample collection. If insufficient water has recharged after 24 hours, <br /> the monitoring well is recorded as dry for the sampling event. <br /> Field measurements are recorded on a water sample field data sheet on which field data <br /> are recorded. Field data sheets are reviewed by the sampling coordinator after the <br /> sampling event is completed. <br /> The pH, specific conductance, and temperature meter are calibrated each day before <br /> beginning field activities. The calibration is checked once each day to verify meter <br /> performance. Field meter calibrations are recorded on the water sample field data sheet. <br /> Well Sampling <br /> When samples for volatile organic analysis are being collected, the rate of transfer from <br /> bailer to sample bottle is regulated to approximately 100 milliliters per minute to <br /> minimize turbulence and aeration. Glass bottles of at least 40 milliliters volume and <br /> fitted with Teflon-lined septa are used in sampling for volatile organics. These bottles <br /> are filled completely to prevent air from remaining in the bottle. A positive meniscus <br /> forms when the bottle is completely full. A convex Teflon septum is placed over the <br /> positive meniscus to eliminate air. After the bottle is capped, it is inverted and tapped to <br /> verify that it contains no air bubbles. The sample containers for other parameters are <br /> filled and capped. <br /> To determine dissolved concentrations of metals, appropriate field filtration techniques <br /> are used. The samples are filtered by attaching a disposable 0.45-micron acrylic <br /> copolymer filter to a pressure vessel. The effluent is pressured through the filter and <br /> directed into the appropriate containers. Each filter is used once and discarded. <br /> Surface Water Sampling <br /> If sufficient flow is observed, surface water samples are collected with a dipper consistent <br /> with the procedures listed in Section 9 of the document entitled "Test Methods for <br /> Evaluating Solid Waste: Physical/Chemical Methods," SW-846, 3rd edition, <br /> November 1986. If low-flow conditions are encountered, a stainless steel scoop is used <br /> to collect samples. The flat bottom of the scoop is pressed against the bank and the water <br /> flows with little disturbance into the scoop. Samples collected with a dipper or scoop are <br /> transferred into the appropriate sample containers. Spring (or surface water) samples are <br /> not filtered. <br /> Foothill WQPS Rev Ldoc <br /> A-3 <br />