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3. Well Purging Monitoring wells will be purged prior to sampling to remove stagnant water from the well casing and filter pack using a bailer, centrifugal pump, or low-flow submersible pump. In most monitoring wells,the amount of water purged before sampling will be greater than or equal to three casing volumes. Samples will be collected as soon as the monitoring wells have recharged to a level sufficient for sample collection. If a monitoring well is evacuated to dryness after removing fewer than three casing volumes, the monitoring well will be allowed to recharge for up to 24 hours. The actual purge volume will be recorded on the field data sheet. If insufficient water has recharged after 24 hours, the monitoring well will be recorded as dry for the sampling event. Groundwater purged from the monitoring wells will be discharged onto the ground unless water quality results warrant discharge to onsite treatment facilities. Field measurements of pH, specific conductance, and temperature will be recorded on the field data sheet. The meter(s)used for measuring pH, specific conductance, and temperature will be calibrated each day before field activities are begun. Field meter calibrations will be recorded on the field data sheet. 4. Well Sampling All groundwater samples will be collected with either low-flow pump sampling techniques or a Teflon bailer. When samples for Total Trihalomethanes (TTHMs) are collected,the flow of groundwater will be regulated to minimize turbulence and aeration. Glass Volatile Organic Analysis (VOA) bottles of at least 40 milliliters volume and fitted with Teflon-lined septa will be used in sampling for TTHMs. The VOAs will be filled completely to prevent air from remaining in the bottle. A positive meniscus will form when the bottle is completely full. A convex Teflon septum will be placed over the positive meniscus to eliminate air. After the bottle is capped, it will be inverted and tapped to verify that it does not contain air bubbles. The sample containers for other parameters will be filled, filtered as required, and capped. Required analytes, appropriate bottle types, and sample volumes are presented in Table 1. When required, dissolved metals samples will be collected using appropriate field filtration techniques. The sample will be filtered by emptying the contents of the Teflon bailer into a pressure transfer vessel. .A disposable 0.45-micron acrylic copolymer filter will be threaded onto the transfer vessel at the discharge point, and the vessel will be sealed. Pressure will be applied to the vessel with a hand pump and the filtrate will be directed into the appropriate containers. If aperistaltic pump is used to filter samples, a new hose will be used for each sample. Similarly, each filter will be used once and discarded. Project Workplan A-2 SA1433 July 30,2004 n:\sa01433\gwmwiwp\workp1an.doc