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• A completed Chain-of-Custody form, detailing the sample I.D., date and time collected, <br />analyses requested, and other project information, accompanied each sample to the <br />laboratory. The Chain-of-Custody forms were signed and dated by all personnel retaining <br />custody of the samples (Appendix C). <br /> <br />Field Equipment and Calibration <br /> <br />Proper maintenance, calibration, and operation of each field instrument are the responsibility <br />of the field personnel and the instrument technicians assigned to the project. All instruments <br />and equipment used during the program will be maintained, calibrated, and operated according <br />to the manufacturers' guidelines and recommendations. <br /> <br />Field equipment are calibrated prior to use in the field as appropriate. The calibration <br />procedures follow standard manufacturers' instructions to ensure that the equipment is <br />functioning within established tolerances and as required by the project. A record of field <br />calibration of analytical instruments is maintained in the calibration logbook by field personnel. <br />Copies of the instrument manuals and other equipment calibration records (e.g., <br />thermometers, sounders) are maintained. Any notes on unusual results, changing of standards, <br />battery charging, and operation and maintenance of the field equipment are included in the <br />calibration logbook. <br /> <br />All instruments are stored, transported, and handled with care to preserve equipment <br />accuracy. Damaged instruments will be taken out of service immediately and not used again <br />until a qualified technician repairs and recalibrates the instruments. <br /> <br />Calibration Procedures <br /> <br />Equipment calibration is performed in accordance with the manufacturer's instructions, and <br />calibration checks are performed each day prior to the start of work. Calibration of rental <br />equipment will be performed by a qualified technician prior to shipment of the equipment. <br /> <br />Calibration standards are used once. Spent calibration liquids are placed in plastic bottles and <br />transported off-site for disposal. A brief summary of the calibration procedures for field <br />measurement equipment is provided below: <br /> <br />• pH: Calibration for pH is performed prior to commencement of sampling activities, using <br />standard buffer solutions having pH values of 4, 7, and 10. Calibration checks for pH values <br />using buffer solutions of 4, 7, and 10 is performed daily. If the reading varies more than <br />0.10 of a unit between calibration checks, the meter will be recalibrated. <br />• Conductivity: Calibration for conductivity is performed prior to commencement of sampling <br />activities, using potassium chloride (KCl) standard solutions with conductivity values of <br />1,000 and 10,000 microsiemens/cm. The meter must read within one percent of full-scale <br />to be considered calibrated. A calibration check for conductivity is performed daily. <br />