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the rods approximately 12 inches, exposing the brass sleeves in the borehole. The sampler is then driven into native soil. Groundwater and Li uid-Phase Petroleum Hydrocarbon Depth Assessment A water/hydrocarbon interface probe is used to assess the liquid-phase petroleum hydrocarbon (LPH) thickness, if present, and a water level indicator is used to measure the groundwater depth in monitoring wells that do not contain LPH. Depth to ground water or LPH is measured from a datum point at the top of each monitoring well casing. The datum point is typically a notch cut in the north side of the casing edge. If a water level indicator is used, the tip is subjectively analyzed for hydrocarbon sheen. Subjective Analysis of Groundwater Prior to purging, a water sample is collected from the monitoring well for subjective assessment. The sample is retrieved by gently lowering a clean, disposable bailer to approximately one-half the bailer length past the air/liquid interface. The bailer is then retrieved, and the sample contained within the bailer is examined for floating LPH and the appearance of a LPH sheen. Monito6n We01 1Pu in and Bann lin If the depth to groundwater is above the top of the screens of the monitoring well, then the wells are purged. Monitoring wells are purged using a electrical submersible pump or bailer until pH, temperature, and conductivity of the purge water has stabilized and a minimum of three well volumes of water have been removed. Wells are typically purged at the rate of 1 gallon per minute (gpm), though will not exceed 2 gpm. If three well volumes can not be removed in one half hour's time the well is allowed to recharge to 80% of the original level. After recharging, a ground water sample is then removed from each of the wells using a disposable bailer. Groundwater purged from the monitoring wells is typically transported to a holding facility in West Sacramento. A Teflon bailer will be the only equipment used for well sampling. When samples for volatile organic analysis are being collected, the flow of groundwater from the bailer will be regulated to minimize turbulence and aeration. Glass bottles of at least 40-milliliters volume and fitted with Teflon TM-lined septa will be used in sampling for volatile organics. These bottles will be filled completely to prevent air from remaining in the bottle. A positive meniscus forms when the bottle is completely full. A convex TeflonTM septum will be placed over the positive meniscus to eliminate air. After the bottle is capped, it is inverted and tapped to verify that it contains no air bubbles. The sample containers for other parameters will be filled, filtered as required, and capped. The water sample is collected, labeled, and handled according to the Quality Assurance Plan. Water generated during the monitoring events is disposed of at approved water recycling facilities. Appendix A Page 6