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<br /> <br />m 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 "z" <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 />Prior to obtaining water level measurements, the monitoring wells would be opened and <br />allowed to equilibrate for a period of approximately V2 hour. <br />The water level probe is decontaminated in a trisodium ph6sphate or non-phosphate <br />detergent wash, followed by a distilled water rinse, prior to use in each well. <br />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 />24134.E01 / STO3R304 Page A-6 <br />Copyright 2003, Kleinfelder, Inc. February 26, 2003