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KLEIN FELDER <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 />U <br />H <br />J <br />Ci <br />U <br />The locations of soil borings and monitoring wells, and the elevation of the ,top of the PVC <br />casings are usually surveyed and tied into permanent markers, if readily available. Survey <br />accuracy is 0.1 foot for the x aiid y coordinates and .01 foot for the z coordinate. The <br />depth to static groundwater is measured from a set location at the top of the PVC casing (usually <br />the north rim). The depth of water is then subtracted from the elevation of the top of the well <br />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 Y2 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 oenerally 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 />20-3978-03.\V3 6/2019766 <br />© 1999. Kleinfelder. Inc <br />Page A-6 <br />September 9. 1999 <br />