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• • 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 an approved 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 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 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 (i.e., samples will be field-filtered for dissolved metals).. • B. GROUNDWATER SAMPLE PRESERVATION AND HANDLING The following section specifies sample containers, preservation methods, and sample • handling procedures. • • 1. Sample Containers and Preservation • Sample containers vary with each type of analytical parameter. Container types and materials were selected to be nonreactive with the particular analytical parameter tested. • Required analytes, appropriate bottle types, and sample volumes are provided in Table 1. • • • • • Riverbank WWTP Workplan Nolte Associates,Inc. • March 2005 A-2 \\SasO\project\SA1542\mon_well\new\gwmwiwp\wp.doc •