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barometric pressure)to affect the water levels non-uniformly. <br /> 3.2.2 Field Sensor Calibration <br /> During sample collection, pH, specific conductance, oxidation reduction potential (ORP), <br /> dissolved oxygen, and temperature of water samples will be measured utilizing a <br /> flow-through cell. Stabilization will be considered achieved when three sequential <br /> measurements are within the following ranges: pH to t0.1 units; specific conductance to <br /> t3%; ORP to t 10 mV; dissolved oxygen to f10%;turbidity to fl ft and temperature to <br /> f10%. At least twice daily, field instruments will be calibrated following manufacturer's <br /> recommended procedures using known, standard solutions. Calibration procedures, date, <br /> and time will be recorded in the field notebook. Instrument maintenance will be <br /> performed as deemed appropriate by the manufacturer. <br /> 3.2.3 "Low-Flow" Groundwater Sampling <br /> Groundwater monitoring well sampling will be conducted using "low-flow" sampling <br /> techniques in accordance with the USEPA Low-Flow Groundwater Monitoring <br /> Procedures (USEPA/540/S-95/504, April 1996). Prior to sampling, depth-to-water <br /> measurements will be used to determine the static water level in each well. A <br /> submersible or peristaltic pump with new, disposable tubing will be placed in the well so <br /> that the pump or tubing intake is located at approximately the mid-point of the screened <br /> interval. The well will be purged at a flow rate of approximately 0.5 liters per minute, or <br /> slower if drawdown in the well is observed to exceed 0.3 feet from the static level. <br /> During purging, field parameters including: pH, conductivity, temperature, <br /> oxidation-reduction potential (ORP), and dissolved oxygen will be measured utilizing a <br /> flow-through cell. Groundwater samples will be collected after at least three sequential <br /> field parameter readings have stabilized to within the limits specified in the USEPA <br /> procedure. Field sampling data will be recorded on FSDSs. ETG's standard operating <br /> procedures for"low-flow" sampling is presented in Appendix B. <br /> 3.2.4 Groundwater Sample Designation <br /> All groundwater samples collected from the newly installed monitoring wells, including <br /> any duplicate samples, will be recorded on field sampling data sheets. Each primary <br /> groundwater sample will designated as the corresponding well designation,with duplicate <br /> samples given the added designation of DUP following the well designation. <br /> Sampling and Analysis Plan-Final 5/18/2012 <br /> 3-3 <br />