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KLEINFELDER <br /> A-3.3 Equipment Decontamination <br /> To reduce the potential for cross-contamination between wells, developing equipment is washed <br /> in a trisodium phosphate or non-phosphate detergent solution and rinsed in distilled water or <br /> steam cleaned prior to use in the next monitoring well. <br /> A-3.4 Well Survey <br /> The locations of soil borings and monitoring wells, and the elevation of the top of the PVC <br /> casings are surveyed (by a professional surveyor) and tied into permanent markers, if readily <br /> available. Survey accuracy is 0.1 foot for the "x" and "y" coordinates and .01 foot for the 'Y' <br /> coordinate. The depth to static groundwater is measured from a set location at the top of the <br /> PVC casing (usually the north rim). The depth of water is then subtracted from the elevation of <br /> the top of the well casing to provide a groundwater elevation for each monitoring well location. <br /> A-4 GROUNDWATER MONITORING <br /> A-4.1 Water Level Measurements <br /> Water level measurements are made in the wells prior to purging and sampling the wells. <br /> Measurement protocol is as follows: <br /> 1. Prior to obtaining water level measurements, the monitoring wells would be opened and <br /> allowed to equilibrate for a period of approximately%hour. <br /> 2. The water level probe is decontaminated in a trisodium phosphate or non-phosphate <br /> detergent wash, followed by a distilled water rinse, prior to use in each well. <br /> 3. Water level measurements are made using a conductivity-based water-level meter. <br /> Depth-to-water is generally measured from a surveyed mark on the north rim of the PVC <br /> well casing. <br /> The water level measurements are converted to elevations using the surveyed casing elevations. <br /> 204587-02.WP2/2002R489 Page A-6 <br /> Copyright 2002,Kleinfelder,Inc. June 6,2002 <br />