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• Turbidity Meter: Turbidity range calibration will be performed prior to initiation of <br />sampling activities, using turbidity gel standards of 0, 4.4, 45, and 483 NTUs. The <br />meter is also checked daily during the sampling period with the standard most <br />representative of the anticipated turbidity of the purged groundwater (typically 0 <br />NTUs to 10 NTUs). If the reading varies by more than one unit between calibration <br />checks, the meter will be recalibrated. Multiple physical conditions can cause <br />variations in readings, including bubbles in the sampled water, wet or dirty sample <br />containers, a wet or dirty lens, a wet or dirty optical sensor, or leakage of incidental <br />light into the sample chamber. <br />Multiple Sensor Meter (PH, Dissolved Oxv2en, Conductivitv, Temperature. <br />Turbidity): A multiple sensor meter may be used for multiple parameter <br />measurements during sampling. Calibration will be performed prior to initiation of <br />sampling activities, using manufacturer auto -calibration solution. If any of the <br />readings are outside of the manufacturers specifications, the meter will be recalibrated <br />for the parameter outside of the calibration range. Calibration checks will be <br />performed daily. <br />Equipment not listed herein will be calibrated according to manufacturers' <br />recommendations and/or generally accepted practice. Calibration procedures will be <br />documented for the project file. Instruments for which calibration cannot be easily <br />checked will be either tested against another instrument of a similar type, or will be <br />returned to the manufacturer for appropriate calibration. If tested against another <br />instrument capable of making the same measurements, variation between instruments <br />must not exceed five percent. If readings vary more than five percent, the instrument will <br />be returned to the manufacturer for calibration. <br />Scheduled periodic calibration of testing equipment will not relieve field personnel of the <br />responsibility of employing properly functioning equipment. If equipment malfunction is <br />suspected, the device will be removed from service, tagged so that it is not inadvertently <br />used, and the appropriate personnel notified so that re -calibration can be performed or a <br />substitute piece of equipment can be obtained. <br />Equipment Maintenance <br />Maintenance responsibilities for field equipment are coordinated through an instrument <br />technician who is responsible for ensuring that available equipment and instrumentation <br />are ready for use, and that returned equipment is inspected, serviced, and returned to <br />available inventory in a timely manner. Maintenance during use is the responsibility of <br />the field team using the equipment. Calibration logbooks contain information on <br />instrument maintenance, calibration, and repair. A separate logbook is maintained for <br />each instrument. The paperwork will include a detailed listing of the item that was <br />cleaned/replaced, and the make/model/serial number for the particular piece of <br />equipment. <br />5 Geo -Logic Associates <br />