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sensitivity control will compensate for highly saline or conductive water. The electric sounder is decontaminated after each use by rinsing with deionized water. Depth to water is recorded to the nearest 0.01 foot in the field logbook. The groundwater elevation at each monitoring well is calculated by subtracting the measured depth to water from the surveyed elevation of the top of the well casing. The total depth of the well is then measured in the monitoring wells scheduled for sampling by lowering the sounder to the bottom of the well. The total depth of the well, used to calculate purge volumes and to determine whether the well screen is partially obstructed by silt,is recorded to the nearest 0.5 foot in the field logbook. SAMPLE COLLECTION Sample collection procedures include equipment cleaning, water level and total well depth measurements,well purging and sampling, spring(or surface water)sampling,leachate sampling, and lysimeter sampling. Field measurements are recorded on a Water Sample Field Data Sheet(Figure A-2) contained in a waterproof field logbook. Field data sheets are reviewed by the sampling coordinator after the sampling event is completed. The pH, specific conductance, and temperature meter is calibrated each day before beginning field activities. The calibration is also checked once each day to verify meter performance. Field meter calibrations are recorded on the Water Sample Field Data Sheet. Equipment Cleaning Sample bottles, caps, and septa used in sampling for volatile and semivolatile organics are triple rinsed with high purity deionized water. After being rinsed, sample bottles are dried overnight at 200°C. Sample caps and septa are dried overnight at 60°C. All sample bottles, caps, and septa are protected from solvent contact between drying and actual use at the sampling site, and are used only once and discarded after analysis is complete. Plastic bottles and caps used in sampling for metals are soaked overnight in a 1 percent nitric acid solution. The bottles and caps are then triple rinsed with deionized water and air dried before being used at the site. Plastic bottles and caps used in sampling for general water quality parameters are not routinely washed. All plastic bottles and caps are constructed of linear polyethylene or polypropylene. They are used only once and discarded after analysis is complete. Before the sampling event is started, equipment that will be placed in the well or come in contact with groundwater is disassembled and cleaned thoroughly with detergent water and then steam cleaned with deionized water. Any parts that may absorb contaminants, such as plastic pump valves, bladders, etc., are cleaned as described above or replaced_ The inside surfaces of the Groundwater Monitoring A-2 Department of Public Works/Solid Waste County of San Joaquin