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sampling for volatile organics. These bottles are filled completely to prevent air from remaining in the bottle. A positive meniscus forms when the bottle is completely full. A convex Teflon septum is 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. Dissolved Metals To determine dissolved concentrations of metals, appropriate field filtration techniques are used. When using a Teflon bailer, the sample is filtered by emptying the contents of the bailer into a pressure transfer vessel. A disposable 0.45-micron acrylic copolymer filter is threaded onto the transfer vessel at the discharge point and the vessel is sealed. Pressure is applied to the vessel with a hand pump and the filtrate is directed into the appropriate containers. Each filter is used once and discarded. When using a bladder pump to collect samples for dissolved constituents, the sample is filtered by attaching a disposable 0.45-micron acrylic copolymer filter directly to the pump effluent line with a pressure fitting. As the pump cycles, the effluent is pressured through the filter and directed into the appropriate containers. Each filter is used once and discarded. Spring (or Surface Water) Sampling If sufficient flow is observed, spring(or surface water) samples are collected with a dipper consistent with the procedures listed in Section 9 of "Test Methods for Evaluating Solid Waste: Physical/Chemical Methods," SW-846, 3rd edition, November 1986. If low-flow conditions are encountered,a stainless steel scoop is used to collect samples. The flat bottom of the scoop is pressed against the bank and the water will flow with little disturbance into the scoop. Samples collected with a dipper or scoop are transferred into the appropriate sample containers. Spring (or surface water) samples are filtered as required. Leachate Sampling If leachate sampling and analysis is required, samples are collected after purging approximately one casing volume using a Teflon bailer. Leachate samples are filtered as required and transferred into the appropriate containers. Lysimeter Sampling If lysnneter sampling and analysis is required, a vacuum is applied to the lysnneter only if an electrical conductivity monitor indicates that the soil-moisture content and soil suction are adequate for attempting to collect a sample. Vacuum and pressure is alternately applied to lysimeter over a 72-hour period to achieve the sample volume required for analysis. If sufficient sample volume is not Groundwater Monitoring A-4 Department of Public Works/Solid Waste County of San Joaquin